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The lack of plant-side energy storage analysis to support nuclear power plants (NPP), has setup this research endeavor to understand the characteristics and role of specific storage technologies and the integration to an NPP. The paper provides a qualitative review of a wide range of configurations for integrating the energy storage system (ESS) to an operating NPP with pressurized water reactor (PWR). The role of ESS technologies most suitable for large-scale storage are evaluated, including thermal energy storage, compressed gas energy storage, and liquid air energy storage. The methods of integration to the NPP steam cycle are introduced and categorized as electrical, mechanical, and thermal, with a review on developments in the integration of ESS with an operating PWR. By adopting simplified off-design modeling for the steam turbines and heat exchangers, the results show the performance of the PWR steam cycle changes with respect to steam bypass rate for thermal and mechanical storage integration options. Analysis of the integrated system characteristics of proposed concepts for three different ESS suggests that certain storage technologies could support steady operation of an NPP. After having reviewed what have been accomplished through the years, the research team presents a list of possible future works.

Organic light-emitting diode (OLED) microdisplays have attracted much attention as displays for small form factor augmented reality (AR) devices. To realize glass-like thin and wide field of view (FoV) AR devices, we designed a display module with a high aspect ratio microdisplay and a thin optical component. For the high aspect ratio microdisplay, we developed the color OLED microdisplay with a 32:9 aspect ratio and a 0.8-inch diagonal ∼2,490-ppi CMOS backplane. To express color and reduce optical crosstalk, we fabricated the color filter (C/F) patterning directly on the white OLED. We also developed a pin mirror lens with 11 pin mirrors to improve the optical efficiency and quality with a thin lens. By combining the microdisplay with LetinAR’s pin mirror lens, we successfully demonstrated an AR device with a wide horizontal FoV of 46° but with a small form factor 4 mm lens.

From the very first time that graphene was used as a transparent electrode for OLED applications, the emergence of active-matrix (AM)-graphene OLED displays has been envisioned. Realizing this expectation, however, turned out to be difficult. Two obstacles are the growth and transfer of a large-area graphene film and the patterning of a graphene film into pixels. To solve these problems, a process of patterning a graphene film without surface contamination was developed. The fabrication of OLED panels by the patterned graphene anode on Gen 2(370 × 470 mm)-sized and flexible substrates was successfully demonstrated. In this work, oxide TFT arrays were combined as a switching backplane, and a pixelated graphene OLED was used as an emissive layer, to realize AM-graphene OLED displays. To explore the technical feasibility of flexible AM-graphene OLED displays, the aforementioned components were formed on a flexible substrate. For commercial-level production, all the processes that were used were chosen to be compatible with the conventional display processes.

A nuclear power plant is one of the power sources that shares a large portion of base-load. However, as the proportion of renewable energy increases, nuclear power plants will be required to generate power more flexibly due to the intermittency of the renewable energy sources. This paper reviews a layout thermally integrating the liquid air energy storage system with a nuclear power plant. To evaluate the performance realistically while optimizing the layout, operating nuclear power plant conditions are used. After revisiting the analysis, the optimized performance of the proposed system is predicted to achieve 59.96% of the round-trip efficiency. However, it is further shown that external environmental conditions could deteriorate the performance. For the design of liquid air energy storage-nuclear power plant integrated systems, both the steam properties of the linked plants and external factors should be considered.

Air pollution sensors based on organic transistors have attracted much interest recently; however, the devices suffer from low responsivity and slow response and recovery rates for gas analytes. These shortcomings are attributed to the low charge-carrier mobility of organic semiconductors and to a structural limitation resulting from the use of a thick and continuous active layer. In the present work, we investigated the material properties of a multiscale porous zeolitic imidazolate framework, [Zn(2-methylimidazole)2]n (ZIF-8), and examined its potential as an analyte channel material inserted at an organic-transistor active layer. A series of carbonized zeolitic imidazolate frameworks (ZIFs) were prepared by thermal conversion of ZIF-8 and also studied for comparison. The microstructures, morphologies, and optical/electrical characteristics of polythiophene/ZIF-8 hybrid films were systematically investigated. Organic-transistor-type nitrogen dioxide sensors based on the polythiophene/ZIF-8 hybrid films showed substantially improved sensing properties, including responsivity, response rate, and recovery rate. The electrical conductivity of the carbonized ZIF-8s enhanced the field-effect mobility of the organic transistors; however, the sensing performance was not improved, because of the closed pore structures resulting from the carbonization. These results provide invaluable information and useful insights into the design of transistor-type gas sensors based on organic semiconductor/metal-organic framework hybrid films.

Objective To evaluate the distribution of multiple anterior bridging bone (ABB) patterns using a newly designed interbody cage with 4 anterior holes that enable communication between the inside and outside of the cage and to estimate its mechanical effect by finite element analysis (FEA). Methods Patients underwent single-level lumbar interbody fusion using ABB cages. Two raters evaluated the distribution patterns of ABB on computed tomography scans 1 year after surgery. We defined the term H-fusion as the presence of complete anterior extracage and intracage bone bridging, with ≥1 ABBs between them. We performed finite element analysis to investigate the effect of ABB on maximal stiffness. Results The study enrolled 98 patients. ABB was most frequently observed in the medial hole of the cages (73.7%). The mean number of ABBs was 3.65, and H-fusion was observed at 135 levels (34%). Postoperative improvement in the Oswestry Disability Index was significantly higher in patients who achieved interbody fusion and H-fusion than in patients who did not. As ABB was added, the increment in the relative maximal stiffness was most affected under flexion and extension forces. Conclusions We observed an average of 3.65 complete ABBs. Finite element analysis demonstrated that ABB could increase the stability in fused segments, especially under flexion and extension stress. Our results suggest that the ABB cage, which allows communicating cross-bridging between inside and outside of the cage, may facilitate a more stable fusion process than a conventionally designed cage.

Microdisplay is a key technology for realizing augmented reality (AR) and mixed reality (MR) devices, which have attracted much attention of late. Even though the operating voltage in the tandem structure is higher than that in the single structure, 2-stack tandem OLED exhibited 20,000 cd/m2 at 9 V, which is compatible with CMOS circuit driving. Due to its top-emitting geometry with a tandem structure, the OLED device with a well-controlled thickness exhibited a white spectrum with (0.26, 0.26) color coordinates. The pixel density of the fabricated microdisplay panel with a white tandem OLED was about 2350 pixels per inch, and the active area of the panel was 0.7 inch diagonally. The resolution of the panel was 1280 × 1024, corresponding to SXGA, and the maximal luminance was 3,000 cd/m2.

Operation with reduced number of operators is considered as an important operational mode to improve economics of a nuclear power plant (NPP) in the future and it will be more important for the small modular reactors (SMRs). To control NPPs efficiently and safely with a reduced number of operators, an intelligent operation system can be very useful. However, reduced number of operators will result in larger consequence in human error due to simultaneous multi-unit failures are now more probable than the conventional operational mode. Thus, to decrease the probability of human error occurrence for the reduced number of operators, the development of an autonomous operation system with certain level of intelligence is inevitable. The prediction capability of system’s behavior as well as understanding the root cause for the current situation should be an essential function of the designed autonomous operation system. The authors propose to use the current system thermal–hydraulic (STH) analysis code platform to develop such intelligence. As a demonstration of the suggested method, the authors used the STH code to track the accident initiator of both large pressurized water reactor (PWR) and SMR. The discussions on how this method can be useful for future NPP operation and how generic differences in system design actually influence the system behavior are presented.

We investigated the optical reflectance, surface roughness, and sheet resistance of aluminum (Al)/titanium nitride (TiN), titanium (Ti), and tungsten (W) layers on Si substrates, which are available in the CMOS foundry, for organic light-emitting diode (OLED) microdisplays. The devices with different metal anode layers exhibited different hole-injection properties and OLED performances, owing to the different optical and electrical properties of metal anode layers. Based on the OLED characteristics, the Al/TiN layer was selected as an anode layer for OLED microdisplays. A green monochromatic OLED microdisplay panel was designed and implemented using the 0.11-μm CMOS process. The density of pixels was ~2 351 pixels per inch and the panel's active area was 0.7 in in diagonal. The resolution of the panel was 1 280 × 3 × 1 024, corresponding to SXGA. The panel was successfully operated, and the maximal luminance was ~460 cd/m2.

Study Design: Prospective observational study. Objectives: We aimed to analysis the distributional patterns of the intra- and extra-cage bridging bone (InCBB and ExCBB) and the significance of ExCBB using suggested lumbar interbody fusion criterion. Methods: This study included the patients with planned single-level transforaminal lumbar interbody fusion. We divided bridging bone into InCBB (in void of right or left cage) and ExCBB (outside of cages; anterior, posterior, intermediate, right, or left) and graded bridging scores from 0 to 2 on postoperative 1-year computed tomography. The fusion was defined as at least having one or more graded 2 and the evaluation were conducted twice by 2 raters. Results: Sixty-five patients were enrolled. All values of intra- and inter-rater reliability in left InCBB, anterior, and posterior ExCBB showed good agreements (≥0.75). Both InCBBs showed similar mean bridging scores (Rt:1.43 vs Lt:1.48), and in ExCBBs, the anterior was the highest (1.43), followed by the posterior (1.14); the right and left were the lowest (0.49 and 0.52 respectively). In subjects determined as fusion (85.4%), complete bridging was observed more in ExCBB (88.8%) than in InCBB (69.9%). Conclusions: Given the higher bridging scores in both InCBBs and Ant. ExCBB, bone grafting is important promoting factor to increase the interbody bridging bone regardless of outside or in void of cages. Based on our suggested criterion, ExCBB has a greater proportion compared to InCBBs for determining the fusion and extra-cage bone grafting should be considered as important procedures for interbody fusion.

Due to small footprint and high efficiency, a Supercritical CO2 (S-CO2) power cycle is considered to be one of the promising next-generation power cycles. Although S-CO2 is reported as a powerful cleaning agent, the performance of a power system operating with S-CO2 will also inevitably degrade over time. Previous researchers have shown that turbomachinery deterioration could be a major subject regarding the system performance degradation. Nevertheless, no quantitative evaluation has yet been made so far. In this study, the impact of the performance degradation of the S-CO2 turbomachinery on the overall performance of the system is analyzed quantitatively. The concept of Health Parameter is used to simulate turbomachinery degradation. To quantify the impact, an S-CO2 direct-cycle small modular reactor is selected as a target system. A transient analysis platform is built using a nuclear system safety analysis code and the deep neural network (DNN)-based S-CO2 turbomachinery off-design performance model. System dynamics are evaluated for primary frequency control ability and secondary load-following capability. Results show that the control problems during the transient state can occur when the output fluctuations are large and the performance degradation is severe. It has been confirmed that even control failures of the PID controllers can occur. Therefore, the performance degradation of turbomachinery must be monitored and considered, for an operation strategy for S-CO2 systems.

The ability to image pressure distribution over complex three-dimensional surfaces would significantly augment the potential applications of electronic skin. However, existing methods show poor spatial and temporal fidelity due to their limited pixel density, low sensitivity, or low conformability. Here, we report an ultraflexible and transparent electroluminescent skin that autonomously displays super-resolution images of pressure distribution in real time. The device comprises a transparent pressure-sensing film with a solution-processable cellulose/nanowire nanohybrid network featuring ultrahigh sensor sensitivity (>5000 kPa−1) and a fast response time (1000 dpi) pressure imaging without the need for pixel structures. Our approach provides a new framework for visualizing accurate stimulus distribution with potential applications in skin prosthesis, robotics, and advanced human-machine interfaces., Electronic skin that spatially maps pressure distribution through imaging shows limited performance despite improvements to data acquisition. Here, the authors report ultraflexible, transparent electroluminescent skin capable of high-resolution imaging of pressure distribution over 3D surfaces.

Background Vertebral fragility fracture (VFF) is a common fracture related to osteoporosis. However, VFF might be asymptomatic and often occurs in patients without osteoporosis. Therefore, we investigated the characteristics of age-related VFF and their correlation with bone mineral density (BMD). Furthermore, we analyzed other factors affecting VFF Methods Medical records from a single center were retrospectively reviewed for 2,216 patients over 50 years old with vertebral fractures conservatively treated from 2005 to 2016. Patients' age, gender, body mass index (BMI), BMD, fracture level, previous vertebral fractures, and anti-osteoporosis medications were obtained. Patients were divided into fragility/non-fragility groups and age sub-groups. The odds ratio for VFF in relation to BMD was evaluated. We also identified other predictive factors for VFF by age groups. Results The fragility group had a higher women ratio, older age, lower BMI, lower BMD, and greater incidence of previous vertebral fractures than the non-fragility group. VFFs were seen in 41.18% of normal BMD patients aged 50–59 and 67.82% of those aged 60–69. The proportion of VFFs increased with age in all WHO osteoporosis classifications. Patients with osteopenia and osteoporosis were 1.57 and 2.62 fold more likely to develop VFFs than normal BMD. In the younger group (under 70), age, women, BMD, and previous vertebral fracture were significant factors affecting VFF, and in the older group (70 and over), age, women, and BMD were factors. In the fragility group, anti-osteoporosis medication rates were 25.08% before and 45.96% after fracture. Conclusion Considerable VFFs occurred in the younger age groups without osteoporosis and age itself was another important predictor of VFF especially in older age groups. The discrepancy between the incidence of VFF and BMD suggests the necessity of supplemental screening factors and anti-osteoporosis treatment guidelines using only BMD should be reconsidered., Graphical Abstract

This chapter delineates the technical issues and integration scheme related to the use of graphene as a transparent electrode in organic light–emitting diode (OLED) applications. We address fundamental issues related to the use of graphene electrode in OLED. Later, we deal with patterning of graphene films into pixels on array scale and their integration into OLED panels. In this course, we emphasize the importance of strong adhesion of graphene film to its support and geometrically correct patterning. Finally, we demonstrate a fully operational two-color OLED module and a flexible OLED module. Our results signify the technical possibility of using graphene films as actual components in commercial OLED products.

The significant increase of renewable energy source is expected to induce stability issue of electric grid due to the intermittency of renewable energy. The challenge of intermittency is making energy storage system more important. Among the grid-scale energy storage systems, a Liquid Air Energy Storage System is increasingly popular with its high energy density, long expected service lifetime, less operation and maintenance cost, and less geographical constraint. At the same time, flexibility of nuclear power plant is becoming more important with higher penetration of renewable energy sources. However, load-following operation not only causes safety issues on the fuel integrity, but also leads to economic deterioration of nuclear power plant. In this study, the new concept is suggested by mechanically integrating nuclear steam cycle and liquid air energy storage system to achieve high flexibility and economy of a nuclear power plant. At off peak hour, nuclear energy is stored by bypassing steam from nuclear steam cycle to external steam turbine which mechanically connected to air compressor in the liquid air energy storage system. Air is compressed by air compressor and liquefied by cold energy storage system. At peak hours, the stored energy is recovered by evaporating and expanding. The thermodynamic and economic analyses are conducted on standalone liquid air energy storage system and nuclear integrated liquid air energy storage system to further examine the benefits of the proposed system. The results show that the round-trip efficiency of the proposed system is around 51% and the energy density is 116 kWh/m3. The round-trip efficiency is competitive and the energy density is superior to other grid-scale energy storage system. Also, the integration improves the capacity factor of nuclear power plant by 3%p. The Levelized Cost of Electricity shows $219.8/MWh for standalone liquid air energy storage system and $182.6/MWh for nuclear integrated liquid air energy storage system, reducing 17% of the standalone systems’ cost. The results show that the proposed concept can achieve better economy than using standalone liquid air energy storage system as well as other energy storage systems. In conclusion, the proposed nuclear integrated liquid air energy storage system has very good potential to become a competitive energy storage option and can assist to stabilize the future electricity grid with high reliance on renewable energy.

A solar-nuclear hybrid system that combines Concentrating Solar Power (CSP) and nuclear power was suggested previously to meet the electricity demands for remote microgrids. The hybrid system combines CSP, Thermal Energy Storage (TES) and a Micro Modular Reactor (MMR). A Supercritical Carbon dioxide (sCO2) power system is used for power generation system. CSP, which has relatively high efficiency, no refueling, low operation and installation costs, is suitable as an energy source for the microgrid. However, since it is challenging to meet 100% electricity demand with a standalone CSP system due to excessive energy storage system and large land area requirement, a hybrid system is proposed by adding a nuclear system to resolve this issue. The hybrid system showed a higher capacity factor than the standalone CSP system while reducing the required energy storage. However, the TES capacity was still excessive to meet 100% of the electricity demand in the previous study to overcome seasonal variation. Therefore, in this study, the hybrid system is re-designed by optimizing solar to nuclear ratio while tracing change in the Levelized Cost Of Electricity (LCOE) of the system. A sensitivity analysis is performed with respect to the five variables; nuclear to solar heat ratio, direct normal irradiation, peak-to-average electricity demand ratio, nuclear island cost, discount rate affecting LCOE. As a result of economic evaluation, it is confirmed that the hybrid system is cost competitive to the standalone CSP system. This study showed that the nuclear-CSP hybrid system can be utilized as a power source with a high potential for isolated microgrid.

The new application of phase change material for passively cooling the containment building of a nuclear power plant provides many benefits such as minimized wall penetration, low maintenance cost, and the possibility of installation in currently operating power plants with a minimal design change. In this study, the applicability of PCM as a passive containment cooling system is verified through design and evaluation of the PCM condenser. In addition, the effective heat capacity method is verified for simulating the melting process of PCM in the condition of a reactor accident. The PCM condenser design is optimized with five design parameters; melting point, volume, heat transfer area, effective thermal conductivity, and total heat absorbed. The performance of the PCM condenser is evaluated by containment safety analysis and is compared to that of an active containment cooling system. Although the PCM condenser had a limitation for absorbing only a fixed amount of thermal energy due to the absence of an external heat sink, the PCM condenser shows better performance in the early stage after the accident initiation compared to the single spray system and finally maintains the integrity of the containment building.

The enhancement of the luminance of organic light-emitting diode (OLED) panels with various areas (2.25–6084 mm2) using a microlens array (MLA) film was investigated. The luminance enhancement was dependent on the viewing angle, and the largest enhancement (64%) was observed in the normal direction while 60 and 18% enhancements were observed at 60 and 30°, which led to lower enhancement (38%) of the total luminous flux compared with the luminance enhancement (64%) in the normal direction. The luminance enhancement with the MLA film also depended on the panel area, and the smaller panels showed lower luminance enhancement than the larger ones. As for the small panels, the straying light beyond the panel areas significantly affected the luminance of the panels, and over 60% luminance enhancement was observed in the normal direction for the large panels (2500 and 6084 mm2) with the MLA film while only 48 and 58% luminance enhancements were observed at the small panels (2.25 and 70 mm2).

After the Fukushima accident, the importance of an emergency power supply for a nuclear power plant has been emphasized more. In order to maximize the performance of the existing emergency power source in operating nuclear power plants, adding a waste heat recovery system for the emergency power source is suggested for the first time in this study. In order to explore the possibility of the idea, a comparison of six supercritical carbon dioxide (S-CO2) power cycle layouts recovering waste heat from a 7.2 MW alternate alternating current diesel generator (AAC DG) is first presented. The diesel engine can supply two heat sources to the waste heat recovery system: one from exhaust gas and the other from scavenged air. Moreover, a sensitivity study of the cycles for different design parameters is performed, and the thermodynamic performances of the various cycles were evaluated. The main components, including turbomachinery and heat exchangers, are designed with in-house codes which have been validated with experiment data. Based on the designed cycle and components, the bottoming S-CO2 cycle performance under part load operating condition of AAC DG is analyzed by using a quasi-steady state cycle analysis method. It was found that a partial heating cycle has relatively higher net produced work while enjoying the benefit of a simple layout and smaller number of components. This study also revealed that further waste heat can be recovered by adjusting the flow split merging point of the partial heating cycle.

A new structure for a switchable mirror device based on reversible electrodeposition is proposed. This device does not contain Cu ions in the electrolyte and adapts a counter electrode. The feasibility of the device was evaluated with a WO3 film, which is a well-known electrochromic material, as a counter electrode. Even in the absence of Cu ions, the WO3 film facilitates a clean erase feature in the device. Furthermore, using a pre-deposited Ag film as a working electrode, Ag deposition can be driven at a substantially lower voltage than that in conventional devices. Moreover the deposition current decreases with the progress of Ag deposition, and stops after completion of the deposition process. The results clearly indicate that the tri-bromine ion, which makes the self-erasing circulation, is not generated during Ag deposition process. The new switchable mirror shows excellent bistability and size scale-up is possible because it does not consume continuous current in the mirror state. By appling the proposed technology, a switchable mirror device with a 7 cm × 9 cm active area was successfully fabricated.

With increasing demand for transparent conducting electrodes, graphene has attracted considerable attention, owing to its high electrical conductivity, high transmittance, low reflectance, flexibility, and tunable work function. Two faces of single-layer graphene are indistinguishable in its nature, and this idea has not been doubted even in multilayered graphene (MLG) because it is difficult to separately characterize the front (first-born) and the rear face (last-born) of MLG by using conventional analysis tools, such as Raman and ultraviolet spectroscopy, scanning probe microscopy, and sheet resistance. In this paper, we report the striking difference of the emission pattern and performance of transparent organic light-emitting diodes (OLEDs) depending on the adopted face of MLG and show the resolved chemical and physical states of both faces by using depth-selected absorption spectroscopy. Our results strongly support that the interface property between two different materials rules over the bulk property in the driving performance of OLEDs.

To meet the energy requirement for a remote and isolated region, a concept of supercritical CO 2 (S-CO 2 ) cooled micro modular reactor (MMR) has been developed, which is easy to transport by fully modularizing the nuclear power system. From the previous work, only the on-design performances of MMR were presented. However, since the nuclear system needs to meet high safety standard, the design can be finalized only after the evaluation of the nuclear system response under multiple transient conditions. Such transient conditions may include part load operation and postulated accidents. The system response can be evaluated only with a high fidelity computer simulation, since it is almost impossible to construct a nuclear facility to test at such conditions. The simulation is performed to guarantee its autonomous operability and safety. Unfortunately, a system analysis computer code available for the S-CO 2 cycle analysis is yet to be developed for the MMR safety evaluation. Description of a S-CO 2 system analysis code platform is first presented in this paper. After that, the developed code is validated with experimental data. The steady state of MMR is first modeled with the code, which is followed by simulations of part load operation and postulated accidents of MMR. All simulation results show that the current design of MMR has the ability to maintain its safety and structural integrity even under extreme conditions to protect the public from radiation hazard at all times.

This paper presents the neutronics and transient studies of a supercritical CO2-cooled micro modular reactor (MMR). The suggested MMR is an extremely compact, integrated, and truck-transportable reactor with 36.2 MWth power and a 20-year lifetime without refueling. A salient feature of the MMR is that all the components including the generator are contained in a small reactor vessel. For a minimum volume and maximum lifetime of the MMR core, a fast neutron spectrum is utilized. To improve the fuel-coolant compatibility and to maximize the fuel volume fraction, UC fuel is considered. A unique replaceable fixed absorber (RFA) is also introduced in order to maintain the excess reactivity at less than 1 dollar during the whole operational period. A drum-type reactivity control system is adopted in the MMR as the primary control system to prevent a control rod ejection accident and a single absorber rod located at the core center is used as the secondary ultimate shutdown system. The neutronics analysis is performed by using the continuous energy Monte Carlo code Serpent with the ENDF/B-VII.1 library. In addition, an unprotected loss of flow (ULOF) accident is simulated by the system analysis code GAMMA+ to show the passive safety of the MMR system.

In this paper, a thermodynamic study of newly suggested supercritical carbon dioxide (s-CO2) cycle layouts using an isothermal compressor is presented. The isothermal compressor is conceptually defined using the ‘infinitesimal approach’ in attempt to resolve the ambiguity in its performance framework. As part of preliminary investigation, the isothermal compressor is demonstrated thermodynamically, and the calculations highlight that it reduces the compression work significantly under s-CO2 power cycle operating conditions over other representative working fluids. The in-house code is modified to allow the analysis of three s-CO2 cycle layouts, simple recuperated Brayton cycle, recompression Brayton cycle, and partial heating Brayton cycle, adopting the isothermal compressor. The cycle performance is evaluated through a sensitivity analysis of cycle design parameters, pressure ratio and flow split ratio. When the machinery is applied, the cycle net efficiency of the simple recuperated cycle and the recompression cycle is improved by 0.5% point and 1–3% points, respectively. Moreover, the partial heating cycle layout, known for its outstanding performance in waste heat recovery applications as a bottoming cycle, produces 15–18% more net work when using an isothermal compressor, compared to the reference cycle. Overall, the use of the isothermal compressor not only improves the general cycle performance, but also provides another degree of freedom for cycle design optimization of s-CO2 cycles.

As the share of renewable energy will be increasing, there is a growing interest in flexible power sources and energy storage systems due to the intermittent nature of renewable energy. We propose the Energy Storage System (ESS) integrated Nuclear Power Plant (NPP) as a solution. The system operates on load-following by branching the mass flow from the steam cycle to the ESS without changing the reactor thermal output. However, the merging point can be different for heat storing ESS and work storing ESS because the outlet conditions of the ESS vary depending on the type of ESS. In this study, the merging points are categorized into two types, feedwater heater and condenser. At each merging point, cycle optimization is performed while increasing the branch flow into ESS. The optimization goal is to maintain the feedwater temperature at the inlet of a steam generator. The power output and energy delivered to the ESS according to the merging point are estimated. From this study, it was found that when 25% of the inlet mass flow rate to the low-pressure turbine is diverted to ESS, the overall output of the steam cycle is decreased by 44.17% for the heat conversion ESS and 49.95% for the work conversion ESS.

In a sodium-cooled fast reactor, a sodium-water reaction (SWR) could be occurred at pressure boundaries between the two separated systems, the steam Rankine cycle and the sodium coolant system, which results in a serious problem in the system. Since it has been a design challenge for researchers, as an alternative system, the supercritical CO 2 (S-CO 2 ) Brayton cycle was suggested. To utilize the S-CO 2 Brayton cycle to a SFR, a series of studies on the coupled system have been conducted at Korea Atomic Energy Research Institute (KAERI). The studies were mainly focused on the pressure boundary failure events and their consequences including Na-CO 2 reactions. Prior to the experimental studies, the authors classified the reaction behaviors of Na-CO 2 reaction based on the possible scenarios that could take place at pressure boundaries. Through experimental studies, it was found that the reaction follows typical chemical formulas and it is essentially dependent on the reaction temperature. More importantly, the reaction rate changed drastically at the specific temperatures and the reaction became flammable exceeding a certain temperature. To specify the design conditions of the SFR system coupled with the S-CO 2 Brayton cycle, by means of a dedicated set-up the self-ignition temperature has been evaluated. Exceeding this threshold temperature a significant increase in the reaction speed is observed. We setup an experimental apparatus and a test matrix based on one of possible scenarios where the flammable Na-CO 2 reaction takes place and we installed a visualized chemical reactor to watch reaction phenomenon around the self-ignition temperature. The experimental apparatus was designed to be easy to control heaters, to regulate gas supply, and to measure reaction temperature. Through the experiment, it was found that the flammable temperature of Na-CO 2 reaction lies between 598.3˚C and 599.9˚C and how liquid sodium reacts with gaseous carbon dioxide at these temperatures. The results will be help to set design criteria for the pressure boundary and it will take long time but an appropriate safety system would be introduced.

Organic wrinkle structures are investigated as an internal scattering layer for the fabrication of highly efficient organic light-emitting diodes (OLEDs). The solution-processed wrinkle structures are planarized with a high-index layer, resulting in a reduced surface roughness and optical haze simultaneously. The OLED device including the wrinkle structures achieved external quantum efficiency (EQE) of 24.2%, corresponding to a 1.24 time enhancement with respect to that of a control device having no internal scattering layer. By attaching a micro lens array (MLA) or a half ball lens (HBL) on the external surface of the substrate, the proposed device exhibits an EQE of 30.5% (1.56 time enhancement) and 41.8% (2.14 time enhancement), respectively. Randomness of the distributed wrinkle structures is shown to provide additional benefits of reduced angular spectral distortion and Lambertian-like emission properties. Trans-scale optical simulation combining wave-optics and the geometrical effect are used for the quantitative analysis of the emission characteristics of the device.

To realize transparent organic light-emitting diodes (OLEDs), a top electrode should have excellent optical, electrical, and mechanical properties. Conventionally, transparent conductive oxides and semitransparent metal have been widely used for transparent top electrodes, but they have several fundamental drawbacks. We herein report efficient large-area inverted transparent OLEDs using a vacuum-laminated top electrode with an embedded metal mesh. The laminated device with 1 mm pitch exhibits superior optical properties including a high transmittance of 75.9% at 550 nm, a low reflectance of 12.0% at 550 nm, and spectrally flat characteristics over the entire visible region and shows nearly ideal Lambertian angular emission characteristics with little angular color shift in both directions. Moreover, the lowered sheet resistance of 4 Ω/sq originating from the embedded metal mesh (1 mm pitch) led to efficient and uniform emission characteristics. As a result, the device shows a relatively high maximum curre...

The supercritical CO 2 (S-CO 2 ) power cycle is receiving worldwide attention as one of the promising advanced future electricity generation technologies. Since the S-CO 2 power cycle can achieve high efficiency with simple system configuration, the role of compact heat exchanger becomes more important to achieve smaller system footprint. As an example of successful compact heat exchanger, the printed circuit heat exchanger (PCHE) was recently suggested for the S-CO 2 power cycle application due to the capability of enduring high pressure difference while providing large heat transfer area within a small volume. However, the S-CO 2 precooler operates very close to the critical point of CO 2 where the conventional design methodology may not be suitable due to substantial variation of the thermo-physical properties near the critical point. Thus, in this paper the design and operation issues of PCHE as the precooler are addressed. In this study, the verification of developed PCHE core design code and experimental test results are presented. The test conditions were 26–43 °C and 7.3–8.6 MPa in temperature and pressure, respectively. In terms of non-dimensional numbers, the Reynolds number range is 15,000–100,000 and the Prandtl number range is 2–33. Friction factor and heat transfer correlations were developed with the experimental data and computational analysis for the future PCHE design as a precooler in the S-CO 2 power cycle.

We have developed down-conversion outcoupling films to enhance the light outcoupling efficiency in white organic light-emitting diodes (OLEDs). The down-conversion outcoupling films consist of outcoupling structures and color conversion materials, which are prepared by a simple solution-based micro-imprint process and are adopted into OLEDs. The down-conversion films successfully realize white light by converting blue rays from blue phosphorescent OLED. The OLEDs based on the down-conversion films with outcoupling structures show a great improvement of power efficiency by a factor of 1.32 compared to the reference OLED based on down-conversion films without outcoupling structures. Furthermore, the influence of a concentration of color conversion materials on color rendering index of OLEDs is investigated. The results strongly indicate that readily fabricated down-conversion light outcoupling films by a simple micro-imprint process are highly promising for enhanced light extraction performance and high color rendering index of white OLEDs.

As potential lighting-emitting devices, electrochemiluminescence (ECL) devices are promising in terms of device structure and fabrication and involve low processing cost compared to organic light-emitting devices (OLEDs). Herein, liquid electrolyte-based multi-colored ECL devices (ECLDs) were prepared with organic materials dissolved in electrolyte solution, which generated red, yellow, green, and blue emissions under an applied square-wave AC bias voltage. Among the four different emissive colors, yellow showed a strong and stable emission, which enabled quantitative measurements, including a luminance of 12 cd m−2 at 4.5 V.

Objective We have reported the surgical outcomes of an anterior column support procedure, the intravertebral cage augmentation technique for the osteoporotic spine. Methods A total of 10 consecutive osteoporotic patients with severely collapsed plana-type vertebrae, causing delayed neurologic deficits, were enrolled in cohort manner. They underwent intravertebral cage augmentation using a single posterior approach. The postoperative follow-up period was >2 years. The patients were divided into 2 groups: group I, fractured index vertebra at the thoracolumbar; and group II, fractured index vertebra at the lower lumbar. The radiographic analysis included the restored ratio of anterior vertebral height, local kyphotic angle, thoracolumbar kyphosis, and lumbar lordosis. The radiographic and clinical results, ambulatory status, and Oswestry disability index were evaluated. Results Compared with preoperatively, the average restored ratio of the anterior vertebral height was 2.98 and 2.35 times greater, and the local kyphotic angle had been corrected from an average of 20.3° and 14.8° to an average of 3.0° and 0.2° at the final follow-up visit in groups I and II, respectively. The thoracolumbar kyphosis in group I had been corrected from an average of 32.9° to 19.7° and the lumbar lordosis in group II had improved from an average of −15.8° to −32.3° at the final follow-up visit. All patients who could not independently ambulate preoperatively became able to walk, except for 2 patients who required a cane. Also, all the patients showed significant improvement in the Oswestry disability index (group I: average, from 38.2 to 12.8; group II, from 37.3 to 19.3). Conclusions The introduced technique is a valuable surgical option for obtaining anterior column support in osteoporotic patients with severely collapsed Kummel disease who require decompression and stabilization procedures using only a posterior approach.

Most of the power plants operating nowadays mainly have adopted a steam Rankine cycle or a gas Brayton cycle. To devise a better power conversion cycle, various approaches were taken by researchers and one of the examples is an S-CO2 (supercritical CO2) power cycle. Over the past decades, the S-CO2 power cycle was invented and studied. Eventually the cycle was successful for attracting attentions from a wide range of applications. Basically, an S-CO2 power cycle is a variation of a gas Brayton cycle. In contrast to the fact that an ordinary Brayton cycle operates with a gas phase fluid, the S-CO2 power cycle operates with a supercritical phase fluid, where temperatures and pressures of working fluid are above the critical point. Many advantages of S-CO2 power cycle are rooted from its novel characteristics. Particularly, a compressor in an S-CO2 power cycle operates near the critical point, where the compressibility is greatly reduced. Since the S-CO2 power cycle greatly benefits from the reduced compression work, an S-CO2 compressor prediction under off-design condition has a huge impact on overall cycle performance. When off-design operations of a power cycle are considered, the compressor performance needs to be specified. One of the approaches for a compressor off-design performance evaluation is to use the correction methods based on similitude analysis. However, there are several approaches for deriving the equivalent conditions but none of the approaches has been thoroughly examined for S-CO2 conditions based on data. The purpose of this paper is comparing these correction models to identify the best fitted approach, in order to predict a compressor off-design operation performance more accurately from limited amount of information. Each correction method was applied to two sets of data, SCEIL experiment data and 1D turbomachinery code off-design prediction code generated data, and evaluated in this paper.

This study explores heat transfer behaviour in mixed convection of a fluid with internal heat generation, a situation found in chemical and nuclear engineering contexts. Computational fluid dynamics is used to simulate laminar ascending mixed convection flow of a heat-generating fluid in a vertical cylinder with uniformly cooled wall, based on a liquid nuclear fuel concept. A new non-dimensional parameter, the IHG-flux number Ω , is developed to express the balance of axial convection versus radial conduction heat transfer. It was found that heat transfer behaviour depends on this parameter, and it can be used as the transition criterion to categorise the simulated results into three distinct heat transfer regimes. A heat transfer correlation using Ω was also developed for Regime I with small values of Ω , where convection and conduction effects are balanced in a stable flow. In Regime II at intermediate Ω , stronger convection gives rise to flow instability. In Regime III with large Ω , convection dominates and the temperature profile inverts so that the maximum temperature occurs at the wall, while instability remains likely.

A switchable diffraction device capable of driving with segment electrodes has been proposed and its operating characteristics were analyzed. The switchable diffraction device is based on a variable cavity structure using reversible electrodeposition technology and two kinds of diffraction gratings are designed to be selectively switched according to the driving electrode. The fabricated device was able to switch the diffraction patterns without any interference between the electrodes, which means that the interference between the electrodes will not be a problem in further device integration with driving circuits. However, when the electrode isolation is not perfect due to parasitic resistance between the electrodes, a weak interference between the electrodes is observed in the diffraction pattern. Therefore, it is expected that ensuring complete insulation between the electrodes will be a very important in the integration of the device. The proposed device can be used as a light control device, an image switchable hologram, etc. Furthermore, it is expected to be applied to reconfigurable metasurfaces through integration with active matrix circuits in the future.

To supply electricity for islands or remote regions, conventional energy sources relying on frequent refueling face issues with high fuel transportation cost and reliability. The Concentrating Solar Power (CSP), which has relatively high efficiency and low installation and operation cost compared to other solar technology, is considered for this purpose in this study. A CSP is mainly connected to Thermal Energy Storage (TES) to be more flexible, and the related technology has high maturity, but TES cannot completely resolve intermittency issue. Therefore, a base energy source suitable for an island or remote region to support CSP is required. A Micro Modular Reactor (MMR) concept by combining a supercritical CO2 power cycle and a small long-life reactor core is utilized to supplement CSP in this study. An MMR is designed to be easily transported via road system while it can produce power over 20 years without refueling. The solar-nuclear hybrid system is expected to solve the intermittency problem of CSP while maintaining high capacity factor of the MMR. This study first presents a concept of a solar-nuclear hybrid system that combines MMR, CSP, and TES altogether for the distributed power source application considering the electricity demand of the region to be installed. The proposed hybrid system is further evaluated in terms of capacity factor and electricity demand fulfillment ratio for a hypothetical microgrid to demonstrate the technical feasibility of the proposed system.

Due to the lack of test data of a supercritical CO2 compressor operating under supercritical CO2 conditions, the work of loss model validation for supercritical CO2 compressor could not be conducted successfully before. Therefore, as the first step, this study gathers the existing accessible experiment data as much as possible while conducting additional supercritical CO2 compressor performance experiments to validate the loss models for the supercritical CO2 compressor. To evaluate the reliability of test results, the measurement uncertainty is estimated from the experiment data. Then, three different combinations of loss models based on the mean streamline method are compared with six available experimental cases to find the most suitable combination of loss models for the supercritical CO2 compressor design and analysis. The combination of loss models proposed by Lee was found to predict pressure ratio and isentropic efficiency of supercritical CO2 compressors operating both on-design and off-design conditions successfully. It is expected that the set of loss models presented herein can be utilized as a conceptual design tool in the preliminary design stage of supercritical CO2 compressors.

To utilize the Northern Sea Route as a future commercial maritime transport route, a container ship with nuclear power and icebreaking capability was considered as an alternative to fossil fuel engines due to better reliability and reduce greenhouse gas emission. SMART was selected due to the possibility of near-term deployment and a high degree of safety, and a trans-critical CO2 cycle was considered for its power conversion system because of its expected good performance under the selected sailing environment. In part 1, major components and passive systems were designed based on thermodynamic cycle optimization. In part 2, GAMMA + code is modified to simulate CO2 two-phase flow, and the code is validated with experimental data. SMART with trans-critical CO2 cycle is modeled with the modified GAMMA + code to check the controllability of the system under icebreaking conditions, and evaluate safety after an accident event with CO2 Passive Residual Heat Removal System (PRHRS), using a natural circulation loop.

The Northern Sea Route is a new way to connect Asia and Europe. To utilize the sea route, merchant ships are required to have the icebreaking capability. Since conventional fossil fuel engines have limitations for the icebreaking merchant ship propulsion, nuclear power having a long refueling period for icebreaking merchant ship is proposed in this paper. To evaluate the technical feasibility of the nuclear power for the icebreaking ship’s engine, 330MWth SMART is selected for the reference reactor core. The power conversion system for the SMART core is substituted with the trans-critical CO2 recompression cycle that has advantageous in low-temperature heat sink as in Northern Sea Route and low-temperature heat source, Pressurized Water Reactor operating conditions. In this paper, the major components of the trans-critical CO2 cycle are designed. Then, CO2 PRHRS, which is driven by CO2 natural circulation loop, is designed to substitute steam-water based PRHRS.

In this paper, a new light-adaptable display (LAD) structure with minimum power consumption is proposed for the future advertising service, and the demonstrated results are reported. An organic light-emitting diode with color reflection (colored OLED) was applied for the reflective- and emissive-mode device, and a guest-host liquid-crystal device (GH-LC) was adopted for the light shutter device. The current efficiency and reflectance of the colored OLED were 35.15 cd/A at 457 cd/m2 luminance and 63% for the yellow color, respectively. The measured contrast ratio of GH-LC was 15.5:1 at dark-room conditions, respectively. Transparent oxide thin-film transistors were used for the backplane, and their average mobility was 9.08 cm2/V s, with a 0.5 standard deviation. Through the optimization of the fabrication process and the structures of each device, the LAD adaptively operating according to the environmental illuminance from dark to 10,000 nits was successfully demonstrated. Moreover, a new LAD driv...

Drug discovery and development has been garnering an increasing trend of research due to the growing incidence of the diverse types of diseases. Recently, drug repositioning, also known as drug repurposing, has been emerging parallel to cancer and tissue engineering studies. Drug repositioning involves the application of currently approved or even abandoned drugs as alternative treatments to other diseases or as biomaterials in other fields including cell therapy and tissue engineering. In this review, the advancement of the antiangiogenesis drugs that were used as treatment for cancer and other diseases, with particular focus on bevacizumab, will be described. This will include an overview of the nature and progression of osteoarthritis (OA), one of the leading global degenerative diseases that cause morbidity, and the development of its therapeutic strategies. In addition, this will also feature the nonsteroidal anti-inflammatory drugs that are commonly prescribed for OA and the benefits of repositioning bevacizumab as alternative treatments for other diseases and as biomaterials for cartilage regeneration. To date, a few number of studies, employing different modes of administration and varying dosages in diverse animal models, have shown that bevacizumab can be used as a signal and can promote both in vitro and in vivo cartilage regeneration. However, other antiangiogenesis drugs and their effects in chondrogenesis and cartilage regeneration are also worth investigating.

Summary Most of the small modular reactor (SMR) concepts developed in the past have compact size and a longer life reactor core than the conventional nuclear power plants. However, these concepts have not achieved the full modularization including power conversion system. This study suggests an innovative concept of a reactor cooled by supercritical state carbon dioxide (S-CO2). A reactor core with uranium carbide fuel controlled by drum type control rods was designed. The core has long life (20 years) without refueling or reshuffling as well as inherent safety features. The reactor can be used as a distributed power source and replace outdated fossil fuel power plants for small cities. Moreover, the authors propose the S-CO2 Brayton cycle as a power conversion system to achieve compact and lightweight module. Because of compact core and power conversion system, the entire system can be contained in a single module. The target of the system is to be able to transport a single core and power conversion system module via ground transportation. In order to meet this target, single module's total weight is minimized in the order of 100 tons. The external size of a module is less than 7 m in length and 4 m in diameter. It produces 12MWe electricity from 36MWt reactor core. The S-CO2 Brayton cycle was optimized, and the cycle components such as turbomachineries and heat exchangers were designed preliminarily to observe the potential to maximize the performance while minimizing the weight. Moreover, a dry air-cooling option to reject waste heat for inland installation was selected for the suggested nuclear system. A concept of passive decay heat removal system was developed, and its performance was examined to determine the required heat removal capacity of the system to assure the system's safety under various anticipated accidents. Copyright © 2016 John Wiley & Sons, Ltd.

In this paper, a comparison of nine supercritical carbon dioxide (S-CO2) bottoming power cycles in conjunction with a topping cycle of landfill gas (LFG) fired 5MWe gas turbine is presented. For the comparison purpose, a sensitivity study of the cycle design parameters for nine different cycles was conducted and each cycle thermodynamic performance is evaluated. In addition, the cycle performance evaluation dependency on the compressor inlet temperature variation is performed to investigate how S-CO2 cycles sensitive to the heat sink temperature variation. Furthermore, the development of new S-CO2 cycle layouts is reported and the suggested cycles' performances are compared to the existing cycle layouts. It was found that a recompression cycle is not suitable for the bottoming cycle application, but a partial heating cycle has relatively higher net produced work with a simple layout and small number of components. Although a dual heated and flow split cycle has the highest net produced work, it has disadvantages of having numerous components and complex process which requires more sophisticated operational strategies. This study identified that the recuperation process is much more important than the intercooling process to the S-CO2 cycle design for increasing the thermal efficiency and the net produced work point of view.