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Fractography of stress corrosion cracking (SCC) of 20% cold worked Type 304 H stainless steel containing δ-ferrite was studied using a compact tension (CT) specimen in oxidizing primary water with a scanning electron microscope (SEM) and electron back scattered diffraction (EBSD). The stress corrosion crack propagated mostly in transgranular stress corrosion cracking (TGSCC) mode and sometimes in intergranular stress corrosion cracking (IGSCC) mode. TGSCC paths were along the {111} plane with both high resolved shear stress and high resolved tensile stress. IGSCC preferentially propagated along the grain boundary perpendicular to the loading axis. The findings in this work suggest that TGSCC proceeds through formation of a weakening zone at the head of the crack tip by interaction of slip and corrosion and then cracking of the weakened zone by tensile stress.

A combination of flow-accelerated corrosion (FAC) tests and corresponding computational fluid dynamics (CFD) tests were performed to determine the hydrodynamic parameters that could help predict the highly susceptible location to FAC in the elbow section. The accelerated FAC tests were performed on a specimen containing elbow sections fabricated using commercial 2-inch carbon steel pipe. The tests were conducted at flow rates of 9 m/s under the following conditions: water temperature of 150 °C, dissolved oxygen

We present a novel data-efficient semi-supervised framework to improve the generalization of image captioning models. Constructing a large-scale labeled image captioning dataset is expensive in terms of labor, time, and cost. In contrast to manually annotating all the training samples, separately collecting uni-modal datasets is immensely easier, e.g., a large-scale image dataset and a sentence dataset. We leverage such massive unpaired image and caption data upon standard paired data by learning to associate them. To this end, our novel semi-supervised learning method assigns pseudo-labels to unpaired images and captions in an adversarial learning fashion, where the joint distribution of image and caption is learned. This approach shows noticeable performance improvement even in challenging scenarios, including out-of-task data and web-crawled data. We also show that our proposed method is theoretically well-motivated and has a favorable global optimal property. Our extensive and comprehensive empirical results on captioning datasets, followed by a comprehensive analysis of the scarcely-paired COCO dataset, demonstrate the consistent effectiveness of our method compared to competing ones.

In infrapatellar bursitis, an acute or chronic inflammation of the infrapatellar bursa causes pain and swelling at the front of the knee. To date, only a few studies have reported cases of infrapatellar bursitis that are treated using Korean medicine. The aim of the present study is to report a case of a 27-year-old male with front knee pain caused by infrapatellar bursitis that was treated with integrated Korean medicine treatments (e.g., acupuncture, pharmacopuncture, herbal medicine). The patient- reported numeric rating scale confirmed that the patient’s pain was relieved, while the physical function tests also indicated a significant improvement. Based on the findings of this study, it can be suggested that integrated Korean medicine treatments could be an effective therapeutic option for patients diagnosed with infrapatellar bursitis.

The triangular fibrocartilage complex (TFCC) is crucial for stabilizing the ulnar side of the wrist but can be partially torn due to degenerative changes, falling, or sudden injuries. However, only a few studies have focused on the use of Korean medicine treatments for TFCC-related wrist pain. This case report presents the successful outcomes of integrated Korean medicine treatment in a patient with a partial TFCC tear. The diagnosis was confirmed via magnetic resonance imaging, which revealed the tear. Subsequently, the patient received integrated Korean medicine treatments. The assessment of the pain scale scores revealed a significant reduction in wrist pain and an improvement in daily life activities. Based on the findings of this study, integrated Korean medicine treatments have been proven to be an effective treatment option for patients with a partial TFCC tear. However, further research is needed to determine the potential benefits and mechanisms of these treatments in managing TFCC-related wrist pain.

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow.

The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μ as and modest azimuthal brightness asymmetry, consistent with the expected appearance of a black hole with mass M ≈ 4 × 10 ^6 M _⊙ . From these observations, we present the first resolved linear and circular polarimetric images of Sgr A*. The linear polarization images demonstrate that the emission ring is highly polarized, exhibiting a prominent spiral electric vector polarization angle pattern with a peak fractional polarization of ∼40% in the western portion of the ring. The circular polarization images feature a modestly (∼5%–10%) polarized dipole structure along the emission ring, with negative circular polarization in the western region and positive circular polarization in the eastern region, although our methods exhibit stronger disagreement than for linear polarization. We analyze the data using multiple independent imaging and modeling methods, each of which is validated using a standardized suite of synthetic data sets. While the detailed spatial distribution of the linear polarization along the ring remains uncertain owing to the intrinsic variability of the source, the spiraling polarization structure is robust to methodological choices. The degree and orientation of the linear polarization provide stringent constraints for the black hole and its surrounding magnetic fields, which we discuss in an accompanying publication.

Non-reactor nuclear facilities are increasing remarkably in Korea combined with advanced technologies such as life and space engineering, and the diversification of the nuclear industry. However, the absence of a basic classification guideline related to the design of non-reactor nuclear facilities has created confusion whenever related projects are carried out. In this paper, related domestic and international technical guidelines are reviewed to present the classification criteria of non-reactor nuclear facilities in Korea. Based on these criteria, the classification of structures, systems and components (SSCs) for safety controls is presented. Using the presented classification criteria, classification of a hot cell facility, a representative non-reactor nuclear facility, was performed. As a result of the classification, the hot cell facility is classified as the hazard category 3, accordingly, the safety class was classified as non-nuclear safety, the seismic category as non-seismic (RW-IIb), and the quality class as manufacturers’ standards (S).

Counterfactuals have been shown to be a powerful method in Visual Question Answering in the alleviation of Visual Question Answering’s unimodal bias. However, existing counterfactual methods tend to generate samples that are not diverse or require auxiliary models to synthesize additional data. In this regard, we propose a more diverse and simple counterfactual sample synthesis method called Counterfactual Mix-Up (CoMiU), which generates counterfactual image features and questions through batch-wise swapping in local object- and word-level. This method efficiently facilitates the generation of more abundant and diverse counterfactual samples, which help improve the robustness of Visual Question Answering models. Moreover, with the creation of diverse counterfactual samples, we introduce two more robust and stable contrastive loss functions, namely Batch-Contrastive loss and Answer-Contrastive loss. We test our method on various challenging Visual Question Answering robustness testing setups to show the advantages of the proposed method compared with the current state-of-the-art methods.

Enzymes have potential for recycling plastics such as PET, a polyester used in textiles and single-use packaging. Here, the authors identify and characterize additional PET-active biocatalysts and expand the number and diversity of thermotolerant scaffolds for enzymatic PET deconstruction.

We report a free-floating planet (FFP) candidate identified from the analysis of the microlensing event KMT-2023-BLG-2669. The lensing light curve is characterized by a short duration (≲3 days) and a small amplitude (≲0.7 mag). From the analysis, we find an Einstein timescale of t _E ⋍ 0.33 days and an Einstein radius of θ _E ⋍ 4.41 μ as. These measurements enable us to infer the lens mass as $M=8\,{M}_{\oplus }{\left({\pi }_{\mathrm{rel}}/0.1\,\mathrm{mas}\right)}^{-1}$ , where π _rel is the relative lens–source parallax. The inference implies that the lens is a sub-Neptune- to Saturn-mass object, depending on its unknown distance. This is the ninth isolated planetary mass microlens with θ _E < 10 μ as, which is a useful threshold for an FFP candidate. We conduct extensive searches for possible signals of a host star in the light curve, but find no strong evidence for the host. We investigate the possibility of using late-time high-resolution imaging to probe for possible hosts. In particular, we discuss the case of finite-source point-lens FFP candidates, for which it would be possible to search for very-wide-separation hosts immediately, although such searches are “high risk, high reward.”

The first very long baseline interferometry (VLBI) detections at 870 μ m wavelength (345 GHz frequency) are reported, achieving the highest diffraction-limited angular resolution yet obtained from the surface of the Earth and the highest-frequency example of the VLBI technique to date. These include strong detections for multiple sources observed on intercontinental baselines between telescopes in Chile, Hawaii, and Spain, obtained during observations in 2018 October. The longest-baseline detections approach 11 G λ , corresponding to an angular resolution, or fringe spacing, of 19 μ as. The Allan deviation of the visibility phase at 870 μ m is comparable to that at 1.3 mm on the relevant integration timescales between 2 and 100 s. The detections confirm that the sensitivity and signal chain stability of stations in the Event Horizon Telescope (EHT) array are suitable for VLBI observations at 870 μ m. Operation at this short wavelength, combined with anticipated enhancements of the EHT, will lead to a unique high angular resolution instrument for black hole studies, capable of resolving the event horizons of supermassive black holes in both space and time.

We report the analysis of four unambiguous planets and one possible planet from the subprime fields (Γ ≤ 1 hr ^−1 ) of the 2017 Korea Microlensing Telescope Network (KMTNet) microlensing survey, to complete the KMTNet AnomalyFinder planetary sample for the 2017 subprime fields. They are KMT-2017-BLG-0849, KMT-2017-BLG-1057, OGLE-2017-BLG-0364, and KMT-2017-BLG-2331 (unambiguous), as well as KMT-2017-BLG-0958 (possible). For the four unambiguous planets, the mean planet–host mass ratios, q , are (1.0, 1.2, 4.6, 13) × 10 ^−4 , the median planetary masses are (6.4, 24, 76, 171) M _⊕ , and the median host masses are (0.19, 0.57, 0.49, 0.40) M _⊙ , respectively, found from a Bayesian analysis. We have completed the Anomaly Finder planetary sample from the first 4 yr of KMTNet data (2016–2019), with 112 unambiguous planets in total, which nearly tripled the microlensing planetary sample. The “sub-Saturn desert” ( $\mathrm{log}q=\left[-3.6,-3.0\right]$ ) found in the 2018 and 2019 KMTNet samples is confirmed by the 2016 and 2017 KMTNet samples.

Following Shin et al. (2023b), which is a part of the “Systematic KMTNet Planetary Anomaly Search” series (i.e., a search for planets in the 2016 KMTNet prime fields), we conduct a systematic search of the 2016 KMTNet subprime fields using a semi-machine-based algorithm to identify hidden anomalous events missed by the conventional by-eye search. We find four new planets and seven planet candidates that were buried in the KMTNet archive. The new planets are OGLE-2016-BLG-1598Lb, OGLE-2016-BLG-1800Lb, MOA-2016-BLG-526Lb, and KMT-2016-BLG-2321Lb, which show typical properties of microlensing planets, i.e., giant planets orbit M-dwarf host stars beyond their snow lines. For the planet candidates, we find planet/binary or 2L1S/1L2S degeneracies, which are an obstacle to firmly claiming planet detections. By combining the results of Shin et al. (2023b) and this work, we find a total of nine hidden planets, which is about half the number of planets discovered by eye in 2016. With this work, we have met the goal of the systematic search series for 2016, which is to build a complete microlensing planet sample. We also show that our systematic searches significantly contribute to completing the planet sample, especially for planet/host mass ratios smaller than 10 ^−3 , which were incomplete in previous by-eye searches of the KMTNet archive.

The gravitational microlensing technique is most sensitive to planets in a Jupiter-like orbit and has detected more than 200 planets. However, only a few wide-orbit ( s > 2) microlensing planets have been discovered, where s is the planet-to-host separation normalized to the angular Einstein ring radius, θ _E . Here, we present the discovery and analysis of a strong candidate wide-orbit microlensing planet in the event OGLE-2017-BLG-0448. The whole light curve exhibits long-term residuals to the static binary-lens single-source model, so we investigate the residuals by adding the microlensing parallax, microlensing xallarap, an additional lens, or an additional source. For the first time, we observe a complex degeneracy between all four effects. The wide-orbit models with s ∼ 2.5 and a planet-to-host mass ratio of q ∼ 10 ^−4 are significantly preferred, but we cannot rule out the close models with s ∼ 0.35 and q ∼ 10 ^−3 . A Bayesian analysis based on a Galactic model indicates that, despite the complicated degeneracy, the surviving wide-orbit models all contain a super-Earth-mass to Neptune-mass planet at a projected planet-host separation of ∼6 au and the surviving close-orbit models all consist of a Jovian-mass planet at ∼1 au. The host star is probably an M or K dwarf. We discuss the implications of this dimension-degeneracy disaster on microlensing light-curve analysis and its potential impact on statistical studies.

We complete the analysis of planetary candidates found by the KMT AnomalyFinder for the 2017 prime fields that cover ∼13 deg ^2 . We report three unambiguous planets: OGLE-2017-BLG-0640, OGLE-2017-BLG-1275, and OGLE-2017-BLG-1237. The first two of these were not previously identified, while the last was not previously published due to technical complications induced by a nearby variable. We further report that a fourth anomalous event, the previously recognized OGLE-2017-BLG-1777, is very likely to be planetary, although its light curve requires unusually complex modeling because the lens and source both have orbiting companions. One of the three unambiguous planets, OGLE-2017-BLG-1275, is the first AnomalyFinder discovery that has a Spitzer microlens parallax measurement, π _E ≃ 0.045 ± 0.015, implying that this planetary system almost certainly lies in the Galactic bulge. In the order listed, the four planetary events have planet-host mass ratios q and normalized projected separations s of $(\mathrm{log}q,s)=(-2.31,0.61)$ , (−2.06, 0.63/1.09), (−2.10, 1.04), and (−2.86, 0.72). Combined with previously published events, the 2017 prime fields contain 11 unambiguous planets with well-measured q and one very likely candidate, of which three are AnomalyFinder discoveries. In addition to these 12, there are three other unambiguous planets with large uncertainties in q .

South Korea is promoting digital healthcare services in the public sector. One notable initiative is the “artificial intelligence and the internet of things (AI–IoT)-based healthcare project for senior citizens”, which was implemented by the Korea Health Promotion Institute (KHPI). This project utilized an IoT-based digital healthcare service that integrates information technology and screen-based AI speaker functions. Services through this project are intended for senior citizens aged 65 years (or older) who face challenges in visiting public healthcare institutions owing to limitations on outdoor activities, especially in the post-coronavirus 2019 era. This article shares the recent outcomes of this project and outlines the mid-to-long-term development strategies for this style of South Korean digital healthcare initiatives.

This study introduces global path planning for autonomous ships in port environments, with a focus on the Port of Ulsan, where various environmental factors are modeled for analysis. Global path planning is considered to take place from departure to berth, specifically accounting for scenarios involving a need to navigate via anchorage areas as waypoints due to unexpected increases in port traffic or when direct access to the berth is obstructed. In this study, a navigable grid for autonomous ships was constructed using land, breakwater, and water depth data. The modeling of the Port of Ulsan’s traffic lanes and anchorage areas reflects the port’s essential maritime characteristics for global path planning. In this study, an improved A* algorithm, along with grid-based path planning, was utilized to determine a global path plan. We used smoothing algorithms to refine the global paths for practical navigation, and the validation of these paths was achieved through conducting ship maneuvering simulations from model tests, which approximate real-world navigation in navigational simulation. This approach lays the groundwork for enhanced route generation studies in complex port environments.

The construction of reinforced concrete (RC) structures inevitably consumes an excessive number of rebars, leading to significant cutting waste and carbon emissions. Extensive research has been conducted to minimize this issue and its consequences; however, these methods consistently consume a substantial number of rebars. This includes a previous study that utilizes the lap splice position optimization and special-length rebar concept without considering the lapping zone regulation. Moreover, conventional lap splices pose inherent drawbacks that could jeopardize the structural integrity of RC members. In contrast, mechanical couplers eliminate the need for rebar lapping, effectively reducing rebar consumption. This research aims to evaluate the impact of an integrated mechanical coupler and special-length-priority minimization algorithm on the reduction in rebar consumption and cutting waste in RC columns, achieving near-zero cutting waste. To validate the effectiveness of the proposed algorithm, it was applied to the column rebars of an RC building. The results revealed a significant reduction in the ordered rebar consumption by 18.25%, accompanied by substantial reductions in the cutting waste (8.93%), carbon emissions (12.99%), and total costs (9.94%) compared with a previous study. The outcomes provide the industry with insights into further reducing rebar consumption and its related consequences. Applying the proposed algorithm to various construction projects will further amplify the corresponding benefits.

The production of steel rebar is an energy-intensive process that generates CO2 emissions. In construction, waste is generated by cutting stock-length rebar to the required lengths. The reduction rate achieved in most previous studies was limited due to adherence to lap splice positions mandated by building codes and the use of stock-length rebar. A previous study demonstrated a significant reduction in rebar usage and cutting waste, approaching zero, upon optimizing the lap splice position, reducing the number of splices, and utilizing special-length rebar. However, the reference length used to determine the special-length rebar was not clearly optimized. This study proposes a special length priority optimization model to minimize wall rebar usage and waste by reducing the number of splices while simultaneously ensuring an optimal reference length. The proposed model was validated using a case study wall with a standard hook anchorage at the top of the wall reinforcement. The optimization model reduced rebar cutting waste to 0.18% and decreased rebar usage from the original design by 16.16%.

Flow accelerated corrosion (FAC) is a type of pipe corrosion in which the pipe thickness decreases depending on the fluid flow conditions. In nuclear power plants, FAC mainly occurs in the carbon steel pipes of a secondary system. However, because the temperature of a secondary system pipe is over 150 °C, in situ monitoring using a conventional ultrasonic non-destructive testing method is difficult. In our previous study, we developed a waveguide ultrasonic thickness measurement system. In this study, we applied a waveguide ultrasonic thickness measurement system to monitor the thinning of the pipe according to the change in pH.The Korea Atomic Energy Research Institute installed FAC-proof facilities, enabling the monitoring of internal fluid flow conditions, which were fixed for ~1000 h to analyze the effect of the pH. The measurement system operated without failure for ~3000 h and the pipe thickness was found to be reduced by ~10% at pH 9 compared to that at pH 7. The thickness of the pipe was measured using a microscope after the experiment, and the reliability of the system was confirmed with less than 1% error. This technology is expected to also be applicable to the thickness-reduction monitoring of other high-temperature materials.

In this study, the proportional, integral, and differential control constants for a self-propulsion point search were investigated using free running Computational Fluid Dynamics (CFD) simulations. The experimental data obtained using a 1/100 scale model of KVLCC2 were used to verify the calculation results. A range of initial propeller rotational speeds from 30% to 140% of the self-propulsion point of the experiment was considered. The controller constants were estimated using the trial-and-error and the Ziegler-Nichols methods, and the two results were similar. As a result, a robust numerical result was obtained within a 0.01% difference of the target speed, and a 0.5% difference of the self-propulsion point of the experiment with P and I constants of 180/m and 30 RPS/m, respectively, for a straight-ahead time of 12.5 L/V. Under the straight-ahead condition, a time step of 0.005 L/V was sufficient. However, in the turning simulation, a time step of 0.0025 L/V or less was required. The key findings obtained from this study are believed to provide a practical guideline for self-propulsion and maneuvering simulation using CFD.

The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagittarius A*. Polarimetric data from these observations contain a wealth of information on the black hole and accretion flow properties. In this work, we develop polarimetric geometric modeling methods for mm-VLBI data, focusing on approaches that fit data products with differing degrees of invariance to broad classes of calibration errors. We establish a fitting procedure using a polarimetric “m-ring” model to approximate the image structure near a black hole. By fitting this model to synthetic EHT data from general relativistic magnetohydrodynamic models, we show that the linear and circular polarization structure can be successfully approximated with relatively few model parameters. We then fit this model to EHT observations of M87* taken in 2017. In total intensity and linear polarization, the m-ring fits are consistent with previous results from imaging methods. In circular polarization, the m-ring fits indicate the presence of event-horizon-scale circular polarization structure, with a persistent dipolar asymmetry and orientation across several days. The same structure was recovered independently of observing band, used data products, and model assumptions. Despite this broad agreement, imaging methods do not produce similarly consistent results. Our circular polarization results, which imposed additional assumptions on the source structure, should thus be interpreted with some caution. Polarimetric geometric modeling provides a useful and powerful method to constrain the properties of horizon-scale polarized emission, particularly for sparse arrays like the EHT.

Event Horizon Telescope (EHT) observations have revealed a bright ring of emission around the supermassive black hole at the center of the M87 galaxy. EHT images in linear polarization have further identified a coherent spiral pattern around the black hole, produced from ordered magnetic fields threading the emitting plasma. Here we present the first analysis of circular polarization using EHT data, acquired in 2017, which can potentially provide additional insights into the magnetic fields and plasma composition near the black hole. Interferometric closure quantities provide convincing evidence for the presence of circularly polarized emission on event-horizon scales. We produce images of the circular polarization using both traditional and newly developed methods. All methods find a moderate level of resolved circular polarization across the image (〈∣ v ∣〉 < 3.7%), consistent with the low image-integrated circular polarization fraction measured by the Atacama Large Millimeter/submillimeter Array (∣ v _int ∣ < 1%). Despite this broad agreement, the methods show substantial variation in the morphology of the circularly polarized emission, indicating that our conclusions are strongly dependent on the imaging assumptions because of the limited baseline coverage, uncertain telescope gain calibration, and weakly polarized signal. We include this upper limit in an updated comparison to general relativistic magnetohydrodynamic simulation models. This analysis reinforces the previously reported preference for magnetically arrested accretion flow models. We find that most simulations naturally produce a low level of circular polarization consistent with our upper limit and that Faraday conversion is likely the dominant production mechanism for circular polarization at 230 GHz in M87*.

Flow-accelerated corrosion (FAC) of carbon steel piping is a significant problem in nuclear power plants. The basic process of FAC is currently understood relatively well; however, the accuracy of prediction models of the wall-thinning rate under an FAC environment is not reliable. Herein, we propose a methodology to construct pipe wall-thinning rate prediction models using artificial neural networks and a convolutional neural network, which is confined to a straight pipe without geometric changes. Furthermore, a methodology to generate training data is proposed to efficiently train the neural network for the development of a machine learning-based FAC prediction model. Consequently, it is concluded that machine learning can be used to construct pipe wall thinning rate prediction models and optimize the number of training datasets for training the machine learning algorithm. The proposed methodology can be applied to efficiently generate a large dataset from an FAC test to develop a wall thinning rate prediction model for a real situation.

A FAC (flow-accelerated corrosion) test was performed for a straight pipe composed of the SA335 Gr P22 and SA106 Gr B (SA106-SA335-SA106) types of steel with welds as a function of the flow rate in the range of 7–12 m/s at 150 °C and with DO

Abstract Background Cell lines are often used to assess the resistance of anticancer drugs when in vivo analysis is not possible. However, the process for establishing anti-cancer drug resistance in cell cultures in vitro and the subsequent method of then evaluating resistance are not clearly established. Traditionally, the IC50 is the most commonly used indicator of resistance evaluation but it cannot represent the effectiveness of anti-cancer drugs in a clinical setting and lacks reliability because it is heavily affected by the cell doubling time. Hence, new indicators that can evaluate anti-cancer drug resistance are needed. Methods A novel resistance evaluation methodology was validated in this present study by establishing sunitinib resistance in renal cell carcinoma cells and assessing the cross-resistance of five different anti-cancer drugs. Results It was confirmed in this present study that the IC50 does not reflect the cell proliferation rates in a way that represents anti-cancer drug resistance. An alternative indicator that can also be clinically meaningful when using in vitro cell line systems is GI100. Additionally, the GR100 allows different cell populations to be calibrated on the same basis when multiple experimental results are compared. Conclusion Since the GR100 has properties that indicate the efficiency of anti-cancer drugs, both the efficacy and GR100 of a particular anti-cancer drug can be used to effectively assess the resistance.

The dislocation density in strain-hardened Alloy 690 was analyzed using scanning transmission electron microscopy (STEM) to study the relationship between the local plastic strain and susceptibility to primary water stress corrosion cracking (PWSCC) in nuclear power plants. The test material was cold-rolled at various thickness reduction ratios from 10% to 40% to simulate the strain-hardening condition of plant components. The dislocation densities were measured at grain boundaries (GB) and in grain interiors of strain-hardened specimens from STEM images. The dislocation density in the grain interior monotonically increased as the strain-hardening proceeded, while the dislocation density at the GB increased with strain-hardening up to 20% but slightly decreases upon further deformation to 40%. The decreased dislocation density at the GB was attributed to the formation of deformation twins. After the PWSCC growth test of strain-hardened Alloy 690, the fraction of intergranular (IG) fracture was obtained from fractography. In contrast to the change in the dislocation density with strain-hardening, the fraction of IG fracture increased remarkably when strain-hardened over 20%. From the results, it was suggested that the PWSCC growth behavior of strain-hardened Alloy 690 not only depends on the dislocation density, but also on the microstructural defects at the GB.

In this paper, we present an electric field analysis for the optimal structural design of lightning rods for high performance with a charge transfer system (CTS). In the case of a conventional rod that is produced with an empirical design and structure without quantitative data because the design is structurally very simple, only the materials and radius of curvature of the lightning rod to concentrate the electric field at the tip part of the rod are considered. Recently, the development of new types of lightning rods, such as early streamer emission (ESE) and charge transfer system (CTS), has been introduced through simulation analysis and experiments, but detailed specifications and information about the optimal design and structure have not been fully reported. In this paper, we performed an electric field analysis of the structures and materials for the optimal structural design of lightning rods with a function of CTS through computer software analysis with consideration for the radius of curvature, the size of corona ring, and optimal position (X-axis and Y-axis) of the floating electrode. For optimal structural design of lightning rods based on electric field analysis, we used a source of lightning voltage with 1.2/50 µs based on a double exponential equation. The results revealed that the electric field on the relaxation part decreases as the radius of curvature and corona ring increases. For the radius of curvature, the electric field first decreases and then increases with increasing radius of curvature and reaches a minimum at 7 mm and a maximum above 8 mm. For the case of the corona ring, the electric field decreases with increasing corona ring, and the optimal size of the corona ring was selected as 4 mm; the size of the 4 mm corona ring uniformly formed the electric field both at the tip part of the ground current collector and the corona ring. For the electric field concentration part, we found that the optimal X-axis position of the floating electrode and the Y-axis position between the ionizer conductor and floating electrode are 7 mm and 0.1 mm, respectively. These simulation results in this paper are expected to provide useful information for the design of optimized CTS-type lightning rods.

Abstract Background Vascular calcification (VC) is a risk factor for cardiovascular disease in end-stage renal disease (ESRD) patients undergoing maintenance haemodialysis (MHD). However, evidence is still insufficient about the association between dialysis parameters and VC. Thus, this study was to evaluate association of dialysis parameters with VC. Methods We enrolled 297 ESRD patients undergoing MHD at six distinct centers in Korea. Study participants were categorized into 3 groups by the scoring system of abdominal aortic calcification based on lateral lumbar radiography (no VC group: 0, mild VC group: 1–7 and advanced VC group: 8–24). We compared the features of dialysis parameters according to the severity of VC. Multivariate logistic regression analysis was used to calculate adjusted odd ratios (ORs) and 95% confidence interval (CI) for mild and advanced VC in each haemodialysis parameter (adjusted OR [95% CI]). Results Pooled Kt/V (spKt/V), equilibrated Kt/V (eKt/V), standard Kt/V (stdKt/V) and the proportion of haemodiafiltration were increased along with the severity of VC. Multivariate regression analysis indicated that advanced VC was positively associated with spKt/V (5.27 [1.51–18.41]), eKt/V (6.16 [1.45–26.10]), stdKt/V (10.67 [1.74–65.52]) and haemodiafiltration (3.27 [1.74 to 6.16]). Conclusion High dose dialysis and haemodiafiltration were significantly associated with advanced VC.

We present detailed analyses of updated eclipse timing diagrams for 32 contact binary merger candidates in the Galactic bulge. The photometric data was obtained from 2016 to 2021 using the Korea Microlensing Telescope Network with the 1.6 m telescopes located at three southern sites (CTIO, SAAO, and SSO). The times of minimum lights were determined by applying the binary-star model to full light curves created at half-year intervals from the observations. The orbital period variations of the binary systems were analyzed using the O − C diagrams from our new timings with the others published in the literature, which are based on the OGLE observations from 2001 to 2015. As results, the orbital periods and period-decreasing rates of 32 binary systems were located to be in the ranges of 0.370 to 1.238 days and from −3.0 to −13.1 × 10 ^−6 day yr ^−1 , respectively. Out of these stars, 24 systems show a combination effect of a parabola and a light travel time caused by a third body, and their outer orbital periods are in the range of 9.1–26.5 yr. We propose that all of our merger candidates need additional monitoring observations to study a luminous-red nova progenitor.

In 2017 the Event Horizon Telescope (EHT) observed the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz ( λ = 1.3 mm). The fundamental physics tests that even a single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT data sets. The high observing frequency means that pulsars—which typically exhibit steep emission spectra—are expected to be very faint. However, it also negates pulse scattering, an effect that could hinder pulsar detections in the Galactic center. Additionally, magnetars or a secondary inverse Compton emission could be stronger at millimeter wavelengths than at lower frequencies. We present a search for pulsars close to Sgr A* using the data from the three most sensitive stations in the EHT 2017 campaign: the Atacama Large Millimeter/submillimeter Array, the Large Millimeter Telescope, and the IRAM 30 m Telescope. We apply three detection methods based on Fourier-domain analysis, the fast folding algorithm, and single-pulse searches targeting both pulsars and burst-like transient emission. We use the simultaneity of the observations to confirm potential candidates. No new pulsars or significant bursts were found. Being the first pulsar search ever carried out at such high radio frequencies, we detail our analysis methods and give a detailed estimation of the sensitivity of the search. We conclude that the EHT 2017 observations are only sensitive to a small fraction (≲2.2%) of the pulsars that may exist close to Sgr A*, motivating further searches for fainter pulsars in the region.

We report on the discovery and analysis of the planetary microlensing event OGLE-2019-BLG-1180 with a planet-to-star mass ratio q ∼ 0.003. The event OGLE-2019-BLG-1180 has unambiguous cusp-passing and caustic-crossing anomalies, which were caused by a wide planetary caustic with s ≃ 2, where s is the star–planet separation in units of the angular Einstein radius θ _E . Thanks to well-covered anomalies by the Korea Micorolensing Telescope Network (KMTNet), we measure both the angular Einstein radius and the microlens parallax in spite of a relatively short event timescale of t _E = 28 days. However, because of a weak constraint on the parallax, we conduct a Bayesian analysis to estimate the physical lens parameters. We find that the lens system is a super-Jupiter-mass planet of ${M}_{{\rm{p}}}={1.75}_{-0.51}^{+0.53}\,{M}_{{\rm{J}}}$ orbiting a late-type star of ${M}_{{\rm{h}}}={0.55}_{-0.26}^{+0.27}\,{M}_{\odot }$ at a distance ${D}_{{\rm{L}}}={6.1}_{-1.3}^{+0.9}\,\mathrm{kpc}$ . The projected star–planet separation is ${a}_{\perp }={5.19}_{-1.23}^{+0.90}\,\mathrm{au}$ , which means that the planet orbits at about four times the snow line of the host star. Considering the relative lens–source proper motion of μ _rel = 6 mas yr ^−1 , the lens will be separated from the source by 60 mas in 2029. At that time one can measure the lens flux from adaptive optics imaging of Keck or a next-generation 30 m class telescope. OGLE-2019-BLG-1180Lb represents a growing population of wide-orbit planets detected by KMTNet, so we also present a general investigation into prospects for further expanding the sample of such planets.

We present an analysis of microlensing event OGLE-2019-BLG-0825. This event was identified as a planetary candidate by preliminary modeling. We find that significant residuals from the best-fit static binary-lens model exist and a xallarap effect can fit the residuals very well and significantly improves χ ^2 values. On the other hand, by including the xallarap effect in our models, we find that binary-lens parameters such as mass ratio, q , and separation, s , cannot be constrained well. However, we also find that the parameters for the source system such as the orbital period and semimajor axis are consistent between all the models we analyzed. We therefore constrain the properties of the source system better than the properties of the lens system. The source system comprises a G-type main-sequence star orbited by a brown dwarf with a period of P ∼ 5 days. This analysis is the first to demonstrate that the xallarap effect does affect binary-lens parameters in planetary events. It would not be common for the presence or absence of the xallarap effect to affect lens parameters in events with long orbital periods of the source system or events with transits to caustics, but in other cases, such as this event, the xallarap effect can affect binary-lens parameters.

As a part of the “Systematic KMTNet Planetary Anomaly Search” series, we report five new planets (namely, OGLE-2016-BLG-1635Lb, MOA-2016-BLG-532Lb, KMT-2016-BLG-0625Lb, OGLE-2016-BLG-1850Lb, and KMT-2016-BLG-1751Lb) and one planet candidate (KMT-2016-BLG-1855), which were found by searching 2016 KMTNet prime fields. These buried planets show a wide range of masses from Earth-class to super-Jupiter-class and are located in both the disk and the bulge. The ultimate goal of this series is to build a complete planet sample. Because our work provides a complementary sample to other planet detection methods, which have different detection sensitivities, our complete sample will help us to obtain a better understanding of planet demographics in our Galaxy.

We measure the Einstein radius of the single-lens microlensing event KMT-2022-BLG-2397 to be θ _E = 24.8 ± 3.6 μ as, placing it at the upper shore of the Einstein Desert, 9 ≲ θ _E / μ as ≲ 25, between free-floating planets (FFPs) and bulge brown dwarfs (BDs). In contrast to the six BD (25 ≲ θ _E ≲ 50) events presented by Gould et al. ( 2022 ), which all had giant-star source stars, KMT-2022-BLG-2397 has a dwarf-star source, with angular radius θ _ast ∼ 0.9 μ as. This prompts us to study the relative utility of dwarf and giant sources for characterizing FFPs and BDs from finite-source point-lens (FSPL) microlensing events. We find “dwarfs” (including main-sequence stars and subgiants) are likely to yield twice as many θ _E measurements for BDs and a comparable (but more difficult to quantify) improvement for FFPs. We show that neither current nor planned experiments will yield complete mass measurements of isolated bulge BDs, nor will any other planned experiment yield as many θ _E measurements for these objects as the Korea Microlensing Telescope (KMT). Thus, the currently anticipated 10 yr KMT survey will remain the best way to study bulge BDs for several decades to come.

Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT Collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I , Q , U , and V , respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties.

We complete the publication of all microlensing planets (and “possible planets”) identified by the uniform approach of the KMT AnomalyFinder system in the 21 KMT subprime fields during the 2019 observing season, namely, KMT-2019-BLG-0298, KMT-2019-BLG-1216, KMT-2019-BLG-2783, OGLE-2019-BLG-0249, and OGLE-2019-BLG-0679 (planets), as well as OGLE-2019-BLG-0344 and KMT-2019-BLG-0304 (possible planets). The five planets have mean log mass ratio measurements of (−2.6, −3.6, −2.5, −2.2, −2.3), median mass estimates of (1.81, 0.094, 1.16, 7.12, 3.34) M _Jup , and median distance estimates of (6.7, 2.7, 5.9, 6.4, 5.6) kpc, respectively. The main scientific interest of these planets is that they complete the AnomalyFinder sample for 2019, which has a total of 25 planets that are likely to enter the statistical sample. We find statistical consistency with the previously published 33 planets from the 2018 AnomalyFinder analysis according to an ensemble of five tests. Of the 58 planets from 2018–2019, 23 were newly discovered by AnomalyFinder. Within statistical precision, half of the planets have caustic crossings, while half do not; an equal number of detected planets result from major- and minor-image light-curve perturbations; and an equal number come from KMT prime fields versus subprime fields.

We report on the observations of the quasar NRAO 530 with the Event Horizon Telescope (EHT) on 2017 April 5−7, when NRAO 530 was used as a calibrator for the EHT observations of Sagittarius A*. At z = 0.902, this is the most distant object imaged by the EHT so far. We reconstruct the first images of the source at 230 GHz, at an unprecedented angular resolution of ∼20 μ as, both in total intensity and in linear polarization (LP). We do not detect source variability, allowing us to represent the whole data set with static images. The images reveal a bright feature located on the southern end of the jet, which we associate with the core. The feature is linearly polarized, with a fractional polarization of ∼5%–8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the energy density of the jet is dominated by the magnetic field. The jet extends over 60 μ as along a position angle ∼ −28°. It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has a particularly high degree of LP, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the variability of the jet structure on microarcsecond scales, while simultaneous multiwavelength monitoring will provide insight into the high-energy emission origin.

We analyze the MOA-2020-BLG-208 gravitational microlensing event and present the discovery and characterization of a new planet, MOA-2020-BLG-208Lb, with an estimated sub-Saturn mass. With a mass ratio $q={3.17}_{-0.26}^{+0.28}\times {10}^{-4}$ , the planet lies near the peak of the mass-ratio function derived by the MOA collaboration and near the edge of expected sample sensitivity. For these estimates we provide results using two mass-law priors: one assuming that all stars have an equal planet-hosting probability, and the other assuming that planets are more likely to orbit around more massive stars. In the first scenario, we estimate that the lens system is likely to be a planet of mass ${m}_{\mathrm{planet}}={46}_{-24}^{+42}\,{M}_{\oplus }$ and a host star of mass ${M}_{\mathrm{host}}={0.43}_{-0.23}^{+0.39}\,{M}_{\odot }$ , located at a distance ${D}_{L}={7.49}_{-1.13}^{+0.99}\,\mathrm{kpc}$ . For the second scenario, we estimate ${m}_{\mathrm{planet}}={69}_{-34}^{+37}\,{M}_{\oplus }$ , ${M}_{\mathrm{host}}={0.66}_{-0.32}^{+0.35}\,{M}_{\odot }$ , and ${D}_{L}={7.81}_{-0.93}^{+0.93}\,\mathrm{kpc}$ . The planet has a projected separation as a fraction of the Einstein ring radius $s={1.3807}_{-0.0018}^{+0.0018}$ . As a cool sub-Saturn-mass planet, this planet adds to a growing collection of evidence for revised planetary formation models.

We continue our program of publishing all planets (and possible planets) found by eye in 2021 Korea Microlensing Telescope Network (KMTNet) online data. We present four planets (KMT-2021-BLG-0712Lb, KMT-2021-BLG-0909Lb, KMT-2021-BLG-2478Lb, and KMT-2021-BLG-1105Lb), with planet-to-host mass ratios in the range $-3.3\lesssim \mathrm{log}q\lesssim -2.2$ . This brings the total of secure, by-eye, 2021 KMTNet planets to 16, including 8 in this series. The by-eye sample is an important check of the completeness of semiautomated detections, which are the basis for statistical analyses. One of the planets, KMT-2021-BLG-1105Lb, is blended with a relatively bright ( I , V ) ∼ (18.9, 21.6) star that may be the host. This could be verified immediately by high-resolution imaging. If so, the host is an early G dwarf, and the planet could be characterized by radial velocity observations on 30 m class telescopes.

We present the analysis of seven microlensing planetary events with planet/host mass ratios q < 10 ^−4 : KMT-2017-BLG-1194, KMT-2017-BLG-0428, KMT-2019-BLG-1806, KMT-2017-BLG-1003, KMT-2019-BLG-1367, OGLE-2017-BLG-1806, and KMT-2016-BLG-1105. They were identified by applying the Korea Microlensing Telescope Network (KMTNet) AnomalyFinder algorithm to 2016–2019 KMTNet events. A Bayesian analysis indicates that all the lens systems consist of a cold super-Earth orbiting an M or K dwarf. Together with 17 previously published and three that will be published elsewhere, AnomalyFinder has found a total of 27 planets that have solutions with q < 10 ^−4 from 2016–2019 KMTNet events, which lays the foundation for the first statistical analysis of the planetary mass-ratio function based on KMTNet data. By reviewing the 27 planets, we find that the missing planetary caustics problem in the KMTNet planetary sample has been solved by AnomalyFinder. We also find a desert of high-magnification planetary signals ( A ≳ 65), and a follow-up project for KMTNet high-magnification events could detect at least two more q < 10 ^−4 planets per year and form an independent statistical sample.

We report results from the TESS photometric data and new high-resolution spectra of the Algol system X Tri showing short-period pulsations. From the echelle spectra, the radial velocities of the eclipsing pair were measured, and the rotational rate and effective temperature of the primary star were obtained to be v _1 sin i = 84 ± 6 km s ^−1 and T _eff,1 = 7900 ± 110 K, respectively. The synthetic modeling of these observations implies that X Tri is in synchronous rotation and is physically linked to a visual companion TIC 28391715 at a separation of about 6.″5. The absolute parameters of our target star were accurately and directly determined to be M _1 = 2.137 ± 0.018 M _⊙ , M _2 = 1.101 ± 0.010 M _⊙ , R _1 = 1.664 ± 0.010 R _⊙ , R _2 = 1.972 ± 0.010 R _⊙ , L _1 = 9.67 ± 0.55 L _⊙ , and L _2 = 2.16 ± 0.09 L _⊙ . The phase-binned mean light curve was used to remove the binary effect from the observed TESS data. Multifrequency analysis of the residuals revealed 16 significant frequencies, of which the high-frequency signals between 37 day ^−1 and 48 day ^−1 can be considered probable pulsation modes. Their oscillation periods of 0.021−0.027 days and pulsation constants of 0.014−0.018 days are typical values of δ Sct variables. The overall results demonstrate that X Tri is an oEA star system consisting of a δ Sct primary and its lobe-filling companion in the semidetached configuration.

Spectroscopy in the mm/sub-mm wavelength range is a powerful tool to study the gaseous medium in various astrophysical environments. The next generation Event Horizon Telescope (ngEHT) equipped with a wide-bandwidth backend system has great potential for science using high angular resolution spectroscopy. Spectral line VLBI studies using the ngEHT will enable us to scrutinize compact astrophysical objects obscured by an optically thick medium on unprecedented angular scales. However, the capabilities of ngEHT for spectroscopy and specific scientific applications have not been properly envisioned. In this white paper, we briefly address science cases newly achievable via spectral line VLBI observations in the mm/sub-mm wavelength ranges, and suggest technical requirements to facilitate spectral line VLBI studies in the ngEHT era.

In this paper, we present the optimized air space of the lightning protection rod (SK-AOR380) with the function of a charge transfer system (CTS). For evaluation of CTS in the laboratory setting, some studies have focused on the modification of the structure and shape of the CTS; the air space is designed (>2 mm) as an empirical design without quantitative data. However, in this paper, we have focused on the air space between the ionizer conductor and current collector to control the inception and occurrence position of corona discharge in air insulation. This is because the performance, such as the initial corona discharge inception of CTS, is determined by the air space. The simulation analysis was performed in a narrow, micro-sized air space as a first step, where the air space was reduced to the extent possible for simulation. To evaluate the performance of SK-AOR380 according to the narrow air space, we considered the numerical analysis method. The fundamental equations consist of Poisson’s equation and the charge continuity equation. Poisson’s equation for electric fields is a fully coupled numerical model based on the charge continuity equations for a positively charged ion, negatively charged ion, and free electron. Fowler–Nordheim electron emission was employed for the boundary condition at the surface of the ionizer conductor. To simulate the corona discharge behavior under standard lightning impulse voltage, we used a source of lightning voltage with 1.2/50 μs based on a double exponential equation; the corona discharge behaviors (electric field distribution, free electron density, positive and negative ion density) were investigated dependent on each time step (0.5, 1 and 1.2 μs) until 3.5 μs. The results revealed that the characteristics graph of free electron density, positive and negative ion density showed similar trends, with lightning impulse voltage increasing with increasing time steps until 1.2 μs and each density resulted in a decreasing trend from 1.2 μs to 3.5 μs. The SK-AOR380 is improved with a decreasing air space in terms of electric field distribution, electron, and ion density. In other words, the 0.0005 mm air space created a non-uniform electric field distribution with a large field enhancement, causing ionization to initiate corona discharge. In addition, in the case of a 0.0005 mm air space, the electric field and electron density are increased by 1.3 and 1.9 times, respectively, than that of 0.001 mm. However, there was no longer a significant difference under 0.0005 mm in the simulation results. To improve the CTS, we suggest the air space between the ionizer conductor and current collector should be less than 2 mm than that of conventional CTS from our research work.

The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries. EAVN currently consists of 16 radio telescopes and three correlators located in China, Japan, and Korea, and is operated mainly at three frequency bands, 6.7, 22, and 43 GHz with the longest baseline length of 5078 km, resulting in the highest angular resolution of 0.28 milliarcseconds at 43 GHz. One of distinct capabilities of EAVN is multi-frequency simultaneous data reception at nine telescopes, which enable us to employ the frequency phase transfer technique to obtain better sensitivity at higher observing frequencies. EAVN started its open-use program in the second half of 2018, providing a total observing time of more than 1100 h in a year. EAVN fills geographical gap in global VLBI array, resulting in enabling us to conduct contiguous high-resolution VLBI observations. EAVN has produced various scientific accomplishments especially in observations toward active galactic nuclei, evolved stars, and star-forming regions. These activities motivate us to initiate launch of the ’Global VLBI Alliance’ to provide an opportunity of VLBI observation with the longest baselines on the earth.

The early-stage M23C6 morphology at the phase boundary between austenite and δ ferrite grain in Type 304L austenitic stainless steel was investigated with transmission electron microscopy (TEM). The M23C6 has coherency with austenite grains at phase boundary. The phase boundary between the M23C6 and austenite grains has curved appearance. The curved phase boundary might be a faceted interface composed of (111) plane and the other low-index planes on the atomic scale. The M23C6 morphology at the phase boundary was identified to be a complex pyramid-like shape that has {111}, {110} and {100} interfaces. The slight deviation in the angle measured between edges of carbide in the TEM images from that calculated between edges expected from the M23C6 morphology might be attributed to multilayer growth in the interior region of the M23C6 face.

This study was carried out to evaluate the aspect of microstructure and mechanical property development on additive manufactured pure Ti at elevated heat-input. For this work, pure Ti powder (commercial purity, grade 1) was selected, and selective laser melting was conducted from 0.5 to 1.4 J/mm. As a result, increase in heat-input led to the significant grain growth form 4 μm to 12 μm, accompanying with the change of grain shape, correctly widmanstätten structured grains. In addition, Vickers microhardness was notably increased from 228 Hv to 358 Hv in accordance with elevated heat-input, which was attributed to the increased concentration of oxygen and nitrogen mainly occurred during selected laser melting process.

This work aims to establish a model of a primary water stress corrosion crack growth rate of Alloy 690 material for the head penetration nozzles of Korean pressurized water reactors. The test material had an inhomogeneous microstructure with bands of fine-grains and intragranular carbides in the matrix of coarse-grains, which was similar to the archive materials of the head penetration nozzles. The crack growth rate was measured from the strain-hardened materials as a function of the stress intensity factor in simulated primary water at various temperatures and dissolved hydrogen contents. The effects of strain-hardening, temperature, and dissolved hydrogen on the crack growth rate were analyzed independently, and were then introduced as normalizing factors in the crack growth rate model. The crack growth rate model proposed in this work provides a key element of the tools needed to assess the progress of a stress corrosion crack when detected in thick-wall Alloy 690 components in Korean reactors. Keywords: Alloy 690, Crack growth rate, Hybrid model, Primary water, Strain rate theory, Stress corrosion cracking