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The evolution of non-metallic inclusions (> 10 µm) for the Al-killed steel in the stainless steelmaking is described. The effects of the slag basicity at the AOD/VOD process, Ca treatment, raw materials (dolomite and spent refractory), reoxidation and vacuum condition on the evolution of the non-metallic inclusion were investigated using the thermo-chemical program (FactSageTM) and the SEM-EDS analysis of the non-metallic inclusions sampled at each process (AOD/VOD-ladle treatment-tundish-continuous casting) and discussed for the beneficial modification of the non-metallic inclusions to obtain better surface quality of the steel in the secondary refining process. The phase stability diagram of the inclusion newly developed from the analysis results and the mechanism for the evolution of non-metallic inclusion in Al-killed stainless steel was suggested.

Background Low-intensity transcranial focused ultrasound stimulation is a promising candidate for noninvasive brain stimulation and accurate targeting of brain circuits because of its focusing capability and long penetration depth. However, achieving a sufficiently high spatial resolution to target small animal sub-regions is still challenging, especially in the axial direction. Objective To achieve high axial resolution, we designed a dual-crossed transducer system that achieved high spatial resolution in the axial direction without complex microfabrication, beamforming circuitry, and signal processing. Methods High axial resolution was achieved by crossing two ultrasound beams of commercially available piezoelectric curved transducers at the focal length of each transducer. After implementation of the fixture for the dual-crossed transducer system, three sets of in vivo animal experiments were conducted to demonstrate high target specificity of ultrasound neuromodulation using the dual-crossed transducer system (n = 38). Results The full-width at half maximum (FWHM) focal volume of our dual-crossed transducer system was under 0.52 μm3. We report a focal diameter in both lateral and axial directions of 1 mm. To demonstrate successful in vivo brain stimulation of wild-type mice, we observed the movement of the forepaws. In addition, we targeted the habenula and verified the high spatial specificity of our dual-crossed transducer system. Conclusions Our results demonstrate the ability of the dual-crossed transducer system to target highly specific regions of mice brains using ultrasound stimulation. The proposed system is a valuable tool to study the complex neurological circuitry of the brain noninvasively.

Neuromorphic devices have been extensively studied to overcome the limitations of a von Neumann system for artificial intelligence. A synaptic device is one of the most important components in the hardware integration for a neuromorphic system because a number of synaptic devices can be connected to a neuron with compactness as high as possible. Therefore, synaptic devices using silicon-based memory, which are advantageous for a high packing density and mass production due to matured fabrication technologies, have attracted considerable attention. In this study, a segmented transistor devoted to an artificial synapse is proposed for the first time to improve the linearity of the potentiation and depression (P/D). It is a complementary metal oxide semiconductor (CMOS)-compatible device that harnesses both non-ohmic Schottky junctions of the source and drain for improved weight linearity and double-layered nitride for enhanced speed. It shows three distinct and unique segments in drain current-gate voltage transfer characteristics induced by Schottky junctions. In addition, the different stoichiometries of Si

Background Adolescence to young adulthood is a critical developmental period that determines lifelong patterns of tobacco use. We examined the longitudinal trajectories of tobacco use, and risk factors for its use, and explored the association between the trajectories of mobile phone dependency and smoking throughout the life-course among adolescents and young adults. Methods Data of 1,723 subjects (853 boys and 870 girls) were obtained from six waves of the Korean Children and Youth Panel Survey (mean age = 13.9–19.9 years). To identify trajectories of smoking and mobile phone dependency, group-based trajectory modelling (GBTM) was conducted. A multinomial logistic regression analysis was performed to identify the characteristics of the trajectory groups. Results GBTM identified four distinct smoking trajectories: never smokers (69.1%), persistent light smokers (8.7%), early established smokers (12.0%), and late escalators (10.3%). Successful school adjustment decreased the risk of being an early established smoker (odds ratio [OR] 0.46, 95% confidence interval [CI] 0.27–0.78). The number of days not supervised by a guardian after school was positively associated with the risk of being an early established smoker (OR 1.96, 95% CI 1.23–3.13). Dependency on mobile phones throughout the life-course was positively associated with the risk of being a persistent light smoker (OR 4.04, 95% CI 1.32–12.34) or early established smoker (OR 8.18, 95% CI 4.04–16.56). Conclusions Based on the group-based modeling approach, we identified four distinctive smoking trajectories and highlight the long-term effects of mobile phone dependency, from early adolescence to young adulthood, on smoking patterns.

The dissolution behavior of Sn in CaO– $$\hbox {CaF}_2$$ flux was investigated. A chemical equilibration technique was employed which allows pure liquid Sn dissolves into the molten flux under various oxygen partial pressure and the flux composition. At an equilibrium, (% Sn) in the flux increased by increasing (% CaO) and $$p_{\text{O}_2}$$ . It was found that Sn dissolves into the molten flux as ( $$\hbox {SnO}_3$$ ) $$^{4-}$$ in the condition of the present study. Distribution of Sn between CaO saturated flux and C saturated liquid Fe was measured under a pure CO atmosphere. Sn distribution ratio ( $$L_{\text{Sn}} = (\%\,\text{Sn})_{\text{flux}}/[\%\,\text{Sn}]_{\text{iron}}$$ ) was as low as $$\sim 10^{-4}$$ , which was consistent with a thermodynamic prediction. Sn distribution was favored at a lower temperature. Thermodynamic modeling was carried out for the Sn dissolution in the flux. A noticeable negative deviation between CaO and SnO was identified.

The evolution of non-metallic inclusions (> 10 μm) for the Si-killed stainless steelmaking process is studied. The effects of the slag basicity in the AOD (argon oxygen decarburization) process, Ca treatment, refractory in the casting ladle, impurities (Ti, Al) in scraps and tapping temperature in the AOD process on the evolution of the non-metallic inclusions are investigated using the thermo-chemical program (FactSageTM) and SEM analysis of the non-metallic inclusions at each process (AOD—ladle treatment—tundish—continuous casting). A new phase stability diagram of the non-metallic inclusion was developed from the analysis results, and we discuss the mechanism of the formation of spinel Mg[Al,Cr]2O4 in the inclusion with the aid of the diagram.

Self-heating effects (SHEs) were investigated through simulations for 3-D V- NAND flash memory. The SHEs are varied by adjusting the thickness of the poly-crystalline channel, the number of stacked cells along with a bitline, and the configuration of the multilevel cell. The simulation data show that the temperature change was smaller than 3 K under read operation; therefore, SHEs are no longer a concern for advances in 3-D V- NAND flash memory technology. In addition, we investigated whether SHEs are influenced by a thermally isolated channel, as in a novel architecture named peripheral-under-cell (PUC), which is a peripheral circuit under cell for 3-D V- NAND flash memory.

A series of steel-flux reaction experiments was conducted to elucidate the reaction mechanism between high Mn-high Al steel and CaO- $${\text{SiO}}_2$$ -type molten mold flux of low MgO content $$(({\text{pct MgO}})_0 = 0$$ to 1.8) at 1723 K ( $$1450\,^\circ \text {C}$$ ). Composition evolutions in the liquid steel and the molten flux during the reaction and microstructure change in the flux near the steel-flux interface were investigated by employing different experimental techniques. $$4{\underline{{\text{Al}}}} + 3({\text{SiO}}_2) = 3{\underline{\text{Si}}} + 2({{\text{Al}}_2} {{\text{O}}_3}$$ ) was confirmed as a major reaction in the system. It was found that rate of $${{\text{Al}}_2} {{\text{O}}_3}$$ accumulation in the flux was retarded as the initial Al content in the steel ( $$[{\text{pct Al}}]_0$$ ) increased from 1 to 5 or 11, approximately. Moreover, keeping the initial content of MgO in the flux ( $$({\text{pct MgO}})_0$$ ) < 1.8) resulted in a slower reaction rate than that with the normal MgO content ( $$({\text{pct MgO}})_0 = \sim 2.5$$ ) reported previously, even at high Al content ( $$[{\text{pct Al}}]_0 = 4.6 {\text{to}} 5.8$$ ). From the microstructure analysis in the flux, the $${{\text{Al}}_2} {{\text{O}}_3}$$ -rich zone and calcium aluminate layer were observed near the interface. A rapid increase of $${{\text{Al}}_2} {{\text{O}}_3}$$ in the flux near the interface was found at the early stage of the reaction. As the reaction proceeded, however, the concentration gradients in the flux did not show noticeable changes. This suggests that mass transport in the flux was hindered by accumulation of the reaction products near the interface. The formation mechanism of the calcium aluminate layer was discussed by considering the measured flux compositions and phase diagram analysis calculated using the CALPHAD technique. Several kinetic analyses indicated that mass transport in the flux significantly affects the overall reaction rate in the high Mn-high Al steel and CaO- $${\text{SiO}}_2$$ -type molten mold flux system with high Al $$([{\text{pct Al}}]_0 \ge 5$$ ) and low MgO content $$(({\text{pct MgO}})_0 \le 1.8$$ ). The formation of a calcium aluminate layer in the low-MgO flux was beneficial to retarding the reaction rate.

High-pressure (HP) deuterium (D2) annealing was applied to a gate-all-around (GAA) MOSFET to improve device reliability and memory performance. The structure had gate dielectrics of oxide–nitride–oxide (ONO), which completely straddled vertically stacked multiple silicon nanowires (Si-NWs) with n+ poly-Si gates. The HP D2 annealing was effective for the vertically stacked GAA MOSFET as it was for a conventional planar MOSFET. In addition, the resistance of the n+ poly-Si gate was also reduced after the HP D2 annealing. This is attributed to the passivation of defects among adjacent poly-Si grains by the HP D2. The reduced gate resistance ( ${R}_{G}$ ) is advantageous for decreasing RC delay. Direct characterizations of dc ${I}$ – ${V}$ and analyses of ac low-frequency noise (LFN) supported the abovementioned behaviors.

In this letter, we propose an area-efficient series-connected resonant tunneling diode pair device (SCRTD) to utilize as a binary neuron device in cellular neural networks (CNNs). The proposed SCRTD (P-SCRTD) consists of two RTDs interconnected by a floating metal layer with a high-doped epitaxial layer. The P-SCRTD shows a 48 % reduction in area by eliminating the isolation area in the conventional SCRTD (C-SCRTD) owing to the symmetrical I-V characteristic of the RTD, without any performance penalty on the DC and RF characteristics by means of adopting the floating metal layer, compared to the C-SCRTD. CNN application of the P-SCRTD is investigated, showing inherent threshold operation and high-speed (12.5 Gbps) low-power (21 mW) performance, despite using the $2~\mu \text{m}$ technology node, for a unit cell for edge extraction.

For the first time, a leaky integrate-and-fire (LIF) neuron with both excitatory and inhibitory characteristics is demonstrated using a single MOSFET. No additional circuits such as comparator, reset circuit, or current-to-voltage converter as well as a membrane capacitor are needed, and thus the LIF neuron is realized with a footprint of 6 F2. Because of its gate terminal, neuron firing is selectively inhibited, which can improve the energy efficiency of the neuromorphic system by inducing sparse activity. Furthermore, the spiking property of the neuron can be controlled by the gate, which can provide additional room to enhance the classification accuracy.

The effects of high temperature on an asymmetrically doped vertical pillar-type metal-oxide-semiconductor field-effect transistor (MOSFET) were investigated. An asymmetrically doped source and drain (S/D) can be easily formed in a vertical pillar-type FET due to the unique pillar structure. When high temperature is applied to the asymmetric S/D of a vertical pillar-typed silicon nanowire, it affects mobility and carrier injection differently. It decreases mobility by phonon scattering for heavily doped S and intermediately doped D. In contrast, it enhances carrier injection for intermediately doped S and heavily doped D. Thus the ON-state current ( I ON) shows opposite dependencies at high temperature. This tendency was verified by electrical measurements and supporting simulations.

Background Subbrow blepharoplasty (SBB) has advantages over traditional blepharoplasty in that it results in more natural-looking creases and contours and is more effective for lateral periorbital rejuvenation. However, in older patients with sunken upper eyelid, this procedure might make the superior eyelid sulcus appear worse because the thicker upper eyelid tissue in the subbrow area is replaced by thinner tissue. To overcome this limitation, we developed a de-epithelialized musculocutaneous flap for SBB. Methods From August 2016 to January 2018, 13 patients with sunken upper eyelid deformity underwent SBB. For each of these patients, a typical SBB incision was made, but the tissue usually removed in SBB was dissected as a flap based on the branch of the ophthalmic vessel. After elevation, the flap was transposed or folded to correct the sunken deformity. The results were assessed by the patients themselves and by three plastic surgeons at 6 months postoperatively. Results The mean age of the patients was 63 years (range, 47–81 years). There were no postoperative complications related to wound dehiscence, hypertrophic scarring, or sensory changes. All patients and plastic surgeons provided scores indicating good to excellent results and were satisfied with the cosmetic outcomes. All patients reported improved functional visual acuity after surgery. Conclusions Our technique is simple and effectively addresses both sunken upper eyelid deformity and dermatochalasis. Unlike fat or dermofat grafting, our new technique does not require an additional donor site, and it is more reliable in terms of vascularity.

The causes of through-thickness cracking in a continuous casting steel slab with low carbon and high alloys were investigated by observation of the fractured surface and microstructures of a fractured slab, and analysis of phase transformation through a continuous cooling transformation (CCT) diagram. Intergranular brittle fracture and ductile fracture were observed on the surface of the slab and inside the slab, respectively. A bainite and martensite microstructure was transformed in the vicinity of the slab surface where intergranular fracture occurred due to excessive water-cooling during continuous casting, and ferrite and pearlite were transformed inside the slab due to a slow cooling rate and relatively high temperature. Immediately after continuous casting, the temperature and the cooling rate for the surface of the slab were 300–450 °C and about 0.1 °C/s, respectively, and thus bainite and martensite on the surface of the slab were tempered simultaneously during transfer to the slab yard. As a result, the tempered bainite and martensite on the surface of the slab and the mixed microstructure of ferrite and pearlite inside the slab were transformed. However, segregation of P and S at grain boundaries was observed in the tempered bainite and martensite at the surface of the slab. The segregation of P and S at grain boundaries could occur by tempering at the temperature between 300–450 °C and the cooling rate as slow as 0.1 °C/s at the surface of the slab, and is a critical cause on ‘temper embrittlement’. Therefore, it is believed that the intergranular fracture at the surface of the slab was due to the temper embrittlement, and ductile fracture occurred inside the slab having a mixed microstructure of ferrite and pearlite, which is ductile.

This study investigates the uncertainties associated with estimates of the long-range transport SO2 (LRT-SO2) flow rate calculated hourly using Geostationary Environment Monitoring Spectrometer (GEMS) synthetic radiances. These radiances were simulated over the Korean Peninsula and the surrounding regions using inputs from the GEOS-Chem model for January, April, July, and October 2016. The LRT-SO2 calculation method, which requires SO2 vertical column densities, wind data, and planetary boundary layer information, was used to quantify the effects of the SO2 slant column density (SCD) retrieval error and uncertainties in wind data on the accuracy of the LRT-SO2 estimates. The effects were estimated for simulations of three anthropogenic and three volcanic SO2 transport events. When there were no errors in the GEMS SO2 SCD and wind data, the average true LRT-SO2 flow rates (standard deviation) and those calculated for these events were 1.17 (± 0.44) and 1.21 (±0.44) Mg/h, respectively. However, the averages of the true LRT-SO2 flow rates and those calculated for the three anthropogenic (volcanic) SO2 events were 0.61 (1.17) and 0.64 (1.20) Mg/h, respectively, in the presence of GEMS SO2 SCD errors. In the presence of both errors in the GEMS SO2 SCD and wind data, the averages of the true LRT-SO2 flow rates and those calculated for the three anthropogenic (volcanic) SO2 events were 0.61 (1.17) and 0.61 (1.04) Mg/h, respectively. This corresponds to differences of 2.1% to 23.1% between the simulated and true mean LRT-SO2 flow rates. The mean correlation coefficient (R), intercept, and slope between the true and simulated LRT-SO2 flow rates were 0.51, 0.43, and 0.45 for the six simulated events, respectively. This study demonstrates that SO2 SCD accuracy is an important factor in improving estimates of LRT-SO2 flow rates.

An erasing method capable of speeds 104-fold faster compared with those by the conventional Fowler–Nordheim (FN) erasing technique is experimentally demonstrated in a gate-all-around junctionless (JL) charge-trap flash memory device using thermal excitation with the aid of electric field. A gate electrode serving as a built-in heater generates Joule heat for thermal excitation of trapped electrons in the charge-trap layer. The electrons excited by thermal excitation are further accelerated for injection into the silicon body by an in-situ applied E-field between the gate and the JL body. Hence, the trapped electrons are removed within 70 ns by electro-thermal erasing.

Self-heating effects (SHEs) in 3-D V-NAND flash memory are investigated using simulations. First, temperature increase is estimated during the read operation, and a hot spot region along the bit-line is identified. Then, a novel bilayered macaroni filler is proposed to relieve the SHEs. A highly thermally conductive layer is plugged into the macaroni oxide filler as a heat sink. The heat dissipation efficiency is improved by up to 21% in the proposed structure. As a result, the reliability issues induced by SHEs can be avoided in V-NAND flash.

Background Salivary cortisol is routinely used as a diagnostic test for Cushing syndrome. The diagnostic use of salivary cortisol for adrenal insufficiency (AI), however, is less established. We aimed to investigate the utility of morning basal and adrenocorticotropic hormone-stimulated salivary cortisol in diagnosing AI in Korean adults. Methods We prospectively included 120 subjects (female, n=70) from Seoul National University Hospital. AI was defined as a stimulated serum cortisol level of l496.8 nmol/L during the short Synacthen test (SST). Serum and saliva samples were drawn between 8:00 AM and 10:00 AM. Salivary cortisol levels were measured using an enzyme immunoassay kit. Results Thirty-four patients were diagnosed with AI according to the SST results. Age, sex, body mass index, serum albumin levels, and serum creatinine levels did not significantly differ between the normal and AI groups. Basal and stimulated salivary cortisol levels were positively correlated with basal (r=0.538) and stimulated serum cortisol levels (r=0.750), respectively (all Pl0.001). Receiver operating characteristic curve analysis yielded a cutoff level of morning basal salivary cortisol of 3.2 nmol/L (sensitivity, 84.9%; specificity, 73.5%; area under the curve [AUC]=0.822). The optimal cutoff value of stimulated salivary cortisol was 13.2 nmol/L (sensitivity, 90.7%; specificity, 94.1%; AUC=0.959). Subjects with a stimulated salivary cortisol level above 13.2 nmol/L but a stimulated serum cortisol level below 496.8 nmol/L (n=2) had lower serum albumin levels than those showing a concordant response. Conclusion The diagnostic performance of stimulated salivary cortisol measurements after the SST was comparable to serum cortisol measurements for diagnosing AI.

This study demonstrated the thermally-assisted (TA) programming of a NOR flash memory device, which was composed of a junctionless silicon nanowire with gate-all-around structure. Fast programming was achieved with the aid of Joule heat, which was generated in a homogeneously heavily doped SiNW by a voltage difference between the source and drain. Its programming speed is the fastest among various NOR flash memories ever reported. The mechanism for programming NOR flash memory inevitably degrades the quality of the tunneling oxide. But the proposed thermally-assisted programming provides simultaneous curing of the damaged tunneling oxide.

Since 2015, universal comprehensive school-based tobacco control programs have been provided in all primary and secondary schools in Korea. This study explored the association of school-level tobacco control with adolescent smoking, and the interactions to investigate whether gender moderates the impact of school tobacco control programs and school-level norms. Both school- and individual-level data were drawn from the 2015 School-Based Tobacco Prevention Program Survey. Multilevel logistic regression analyses were performed using data from 4631 students (ages 10&ndash, 18 years) who were nested in 62 secondary schools in Seoul, Korea. Students who participated in more prevention programs were less likely to smoke (OR = 0.47, 95% CI 0.30&ndash, 0.74). The effect of the programs was significantly moderated by gender. For boys, exposure to a greater number of programs decreased the risk of smoking (OR = 0.32, 95% CI 0.18&ndash, 0.57) but not for girls. At the school level, the school norm regarding tobacco control regulations was negatively associated with smoking (OR = 0.28, 95% CI 0.11&ndash, 0.76), and its effect was significant for girls only (OR = 0.35, 95% CI 0.17&ndash, 0.76). This study highlights how the school environment is associated with adolescent smoking behavior, and the effects of programs and norms are different by gender. The findings suggest the need to develop strategies to enhance school-based tobacco control programs and the school norm considering gender differences.