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Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for near-term human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of 100 MWth and an electricity generation mode of 100 kWth, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and thermohydraulics was carried out. The result indicates that the innovative design has great potential for high propellant efficiency and thrust-to-weight of engine ratio, compared with the existing NTR designs. However, the build-up of fission products in fuel has a significant impact on the bimodal operation of the moderated reactor such as xenon-induced dead time. This issue can be overcome by building in excess reactivity and control margin for the reactor design.

Recently, supercritical CO2 (S-CO2) power system have received much attention due to their high efficiency and small size. S-CO2 exhibits a dramatic nonlinear property change near the critical point. Owing to this sensitivity, a bottleneck of S-CO2 system off-design analysis can be the turbomachinery off-design prediction. Conventionally, to reflect off-design performances of turbomachines within the system analysis, performance map with the correction method has been exploited. It is because computationally expensive to solve the Euler turbine equation for every iteration. However, due to the aforementioned behavior near the critical point, it is questionable if the method developed under air condition can still be valid for the S-CO2 system. The authors are proposing a method using Deep Neural Network (DNN) to build an S-CO2 turbomachinery off-design model. A statistical analysis revealed that the method showed 101 to 104 times better Mean Squared Error (MSE) and Mean Absolute Percentage Error (MAPE) indices than those of the existing correction methods. Analysis from the system point of view was also carried out. The results of the pre-trained DNN S-CO2 turbomachinery off-design model and the correction methods were compared by analyzing the off-design steady-state performance of an S-CO2 simple recuperated cycle. The results showed that system off-design performance predictions can be significantly distorted with the conventional correction methodologies, and that it can be avoided through the developed DNN based S-CO2 turbomachinery off-design model.

This paper first presents a review of compact heat exchanger technology for a supercritical carbon dioxide (S-CO2) power cycle application to provide holistic insights for designing a power system and selecting appropriate heat exchangers. This is because a compact heat exchanger plays a key role in the S-CO2 power system to have small footprint while maintaining structural integrity. The developments and characteristics of various compact heat exchangers are briefly described, and their heat transfer mechanisms and correlations obtained from open literatures are summarized, enabling the researchers to obtain information quickly for their needs. From the selected correlations, thermal hydraulic performances of compact heat exchangers are compared for the S-CO2 recuperator operating region.

Nuclear thermal-hydraulic system analysis codes with the Best Estimate plus Uncertainty approach are unavoidably uncertain and naturally, an uncertainty analysis has been an important issue. In general, the system is discretized depending on the user while satisfying some criteria. Previously, uncertainties related to spatial discretization in nodalization have been less considered due to their difficulty in quantification. However, there are some results that they are comparable to other uncertainties. Previous studies have been conducted by evaluating and optimizing the uncertainty related to user effect by performing iterative calculations. Since these methods consume a large amount of resources for computation, this study suggests a method of consuming less resources. For this purpose, the adjoint method is applied to the code for node optimization in this study. The proposed methodology is applied to two cases and confirmed its applicability for the node optimization and its utility in the node uncertainty quantification.

The non-base load operation of nuclear power plants is expected to be unavoidable in future due to the increasing shares of the intermittent renewables. In this paper, the physics conditions required for a passively autonomous frequency control operation (PAFO) in a 3400 MWt conventional pressurized water reactor (PWR) design is investigated. The PAFO scheme allows a PWR to passively achieve the requested power maneuverability for primary and secondary frequency regulations on the electrical grid. This study is carried out for a conventional coolant system with a typical critical boron concentration, which yields a less negative coolant temperature coefficient (CTC) than that in a soluble-boron-free (SBF) core. The PAFO scheme is expected to be more challenging in the conventional PWRs than in an SBF small modular reactor, particularly for the secondary frequency regulation. This is mainly due to the weaker coolant reactivity feedback and the higher fuel temperature, which yields a stronger Doppler reactivity feedback during the passive power transients. Numerical simulations of PAFO are performed, for typical power ranges and power ramping rates required for frequency regulations, using a lumped PWR model that is solved by an in-house Fortran-95 computer code. In conventional PWRs, the progressive dilution of the soluble-boron throughout the cycle and the fuel depletion vary the reactivity coefficients. Therefore, we perform sensitivity analyses on CTC, FTC, and Xe worth to assess the feasibility of PAFO throughout the fuel cycle. In addition, sensitivity analysis on the fuel temperature is done to study its role in altering the reactor performance during PAFO.

Recent climate initiatives had initiated a wave of reducing CO2 emissions for power generation. Many countries have been striving to develop and deploy low carbon emission technologies for power generation through efficiency improvement and use of renewable energy. For the regions that gain sufficient amount of solar to make solar power attractive overall, the challenge of intermittency still poses an issue for the electricity grid. The complementary role of natural gas power for the incoming renewables will be reinforced in the near future, but emission of CO2 needs to be avoided through means such as carbon capture and storage. A novel solution of integrating the s-CO2 oxy-combustion system with the concentrated solar power (CSP) is devised. The suggested concept will provide direction to satisfy the growing electricity demand, yet with environmental sustainability. The evaluation of this system in several regions possible for CSP installation shows reduction of fuel consumption by 17–38% compared to conventionally separated systems.

Using CFD simulations, this study presents: (1) LES and RANS comparisons for a unit cell geometry of heat transferring pebbles in flowing FLiBe; (2) statistical distributions of pebble heat transfer coefficients due to the random packing; (3) development of a heat transfer coefficient correlation for randomly-packed heat transferring pebbles in flowing FLiBe in the representative Fluoride High-temperature Reactor (FHR) operating condition; and (4) comparison of the developed heat transfer coefficient correlation with existing ones obtained in different fluids and pebble sizes. The LES and RANS comparison has shown that the k-ω Shear Stress Transport (SST) with low Reynolds number approach performance gives the best result in comparison to the two eddy-viscosity based k-e and k-ω SST models. The statistical distribution of pebble heat transfer coefficients due to random packing has been quantified; random arrangements of pebbles result in non-negligible uncertainties in heat transfer coefficients following normal distributions. This uncertainty needs to be accounted for fuel temperature prediction in reactor design and analyses. A Nusselt number correlation for the randomly packed heat transferring pebble in flowing FLiBe has been computationally developed: Nu = 0.016Re0.72Pr0.31.

In nuclear safety analyses, a 1-D thermal hydraulic system analysis code with the best estimate plus uncertainty (BEPU) approach is generally used. There are sources of uncertainty such as nodalization, physical models, and numerical scheme. Among them, the authors specifically focused on the node configuration uncertainty related to spatial discretization that is regarded as less dominant sources of uncertainty in the code previously. Furthermore, it was not easy to quantify the uncertainty from the node configuration. The authors quantified and analyzed the node configuration uncertainty to understand how much it affects the solution. In this study, the effect of spatial discretization are studied by discussing simulation results for various spatially discretized node systems. The discussion on the node configuration uncertainty will be presented by examples of SUbcooled BOiling (SUBO) test simulation and Loss Of Fluid Test (LOFT) simulation using Multi-dimensional Analysis of Reactor Safety (MARS) code developed in South Korea. From SUBO test simulation, it was found that when the number of nodes is small than the node configuration uncertainty can overwhelm the uncertainty from the physical model. From LOFT simulation, it was revealed that the node configuration can cause bifurcation in the complex nuclear system analyses. Thus, it is concluded that the node configuration uncertainty can be quite significant and has to be considered in the nuclear system analyses.

With the increased role of intermittent renewables in the energy mix, it is important for the Nuclear Power Plants (NPPs) to develop flexible load-follow capabilities in order to be economically competitive. By combining NPP with external superheaters, there is possibility to increase power conversion cycle efficiency and reduce load to some extent while maintaining the nuclear reactor operation at 100% of its rated power and thus maximizing its economic value. In this paper, parametric study of a Small Modular Boiling Water Reactor (SMBWR) conceptual design combined with external superheaters is presented quantifying its performance at different system pressure. The first part of the work is focusing on how operating pressure will affect the SMBWR system as a whole, which includes neutronics, thermal hydraulics, and thermodynamics. WIMS-PANTHER package and COBRA-EN were used as the neutronic and thermal hydraulic tools. In addition, MATLAB models of the SMBWR natural circulation loop and balance of plant were developed for the study. The second part of the work examines the maneuvering capability of SMBWR. It is found that increasing the pressure from 6.5 to 10.0 MPa has no significant neutronic effects, while thermal efficiency is slightly improved. It is also found that SMBWR is able to reduce the load to 65% while maintaining the reactor power at 100% of its rated value.

Nowadays Small Modular Reactors (SMRs) have been receiving considerable attentions worldwide for potential advantages of an excellent flexibility for siting, low capital investment, and advanced safety. In Korea, a new research project has launched for the development of a conceptual design of a further advanced SMR which aims for a naturally-safe and autonomous operation, so called Autonomous Transportable On-demand reactor Module (ATOM). Major design objectives of the ATOM system are focused on the soluble boron-free (SBF) primary coolant system which enables the SMR to operate automatically in a load following mode. For the secondary system, the SCO2 power conversion cycle with air-cooling system as a final heat sink is being considered. The air-cooling system is expected to show flexible response even to extreme environmental conditions, such as a desert where utilization of cooling water is limited. The objective of this study is a feasibility assessment for applying the air-cooling system as a final heat sink of the ATOM by means of experimental work. As a 1st phase of the ATOM development, we first conducted the experiments using a typically considered primary coolant, water-steam, to verify that air flow has enough cooling capability to remove developed heat which the coolant carries. An Integrated Condensation Loop with Air-cooling System (ICLASS) experimental facility with three pressure boundaries (Steam, coolant, and air) was established. The cooling capability of the air-cooling system was evaluated by varying steam mass flow rate, coolant flow rate, and air environment temperature as experiment variables. Overall heat transfer rate by condensation was compared with numerical simulations of a 1D thermal-hydraulics analysis code, using the MARS model of the ICLASS facility.

Modification of multilayer graphene films was investigated for a cathode of organic light-emitting diodes (OLEDs). By doping the graphene/electron transport layer (ETL) interface with Li, the driving voltage of the OLED was reduced dramatically from 24.5 to 3.2 V at a luminance of 1000 cd/m2. The external quantum efficiency was also enhanced from 3.4 to 12.9%. Surface analyses showed that the Li doping significantly lowers the lowest unoccupied molecular orbital level of the ETL, thereby reducing the electron injection barrier and facilitating electron injection from the cathode. Impedance spectroscopy analyses performed on electron-only devices (EODs) revealed the existence of distributed trap states with a well-defined activation energy, which is successfully described by the Havriliak-Negami capacitance functions and the temperature-independent frequency dispersion parameters. In particular, the graphene EOD showed a unique high-frequency feature as compared to the indium tin oxide one, which could be explained by an additional parallel capacitance element.

From the observation of previous experimental results, it was recognized that the amount of external losses at the external flow paths can be substantial. Understanding the external loss mechanisms, and reducing the external losses are crucial to the design of a high performance S-CO2 compressor. Therefore, this study first focused on verifying the existing external loss models by estimating the internal loss accurately through a high fidelity CFD calculation and then substituting from the total losses. By analyzing the CFD result and energy balance data obtained from the experiment, the authors are suggesting the best combination of the external loss models for the S-CO2 compressor. This is followed by the investigation of the condensation effect in the impeller by utilizing a two-phase VOF model with metastable properties. As a result, it is re-confirmed that there is a negligible amount of condensation effect.

The Supercritical CO2 power cycle (S-CO2 cycle) is the power cycle that adopts CO2 as a working fluid and is designed to have a compression process near the critical point of CO2. Due to the non-linearity of CO2 pyhsical properties near the critical point, the S-CO2 cycle needs relatively less compression work. Therefore, the efficiency of the S-CO2 cycle is higher than traditional gas cycles. Furthermore, because of the relatively high system minimum pressure (near the critical point, ∼7.39 MPa), an S-CO2 cycle can be composed of smaller turbomachines. Considering these advantages, nowadays, there are many attempts to apply S-CO2 cycles to various fields, such as waste heat recovery, nuclear, coal, concentrated solar power plant and so on. These non-linear pyhsical properties become the cause of some unique issues. One of the most significant issues is the internal pinch point problem in a recuperator. Unlike the traditional gas-to-gas heat exchanger, each hot and cold side of the S-CO2 recuperator goes through the severe change of specific heat. This dramatic change of specific heat may cause the internal pinch point of the recuperator. When the internal pinch point phenomenon occurs, the performance of the recuperator may not able to be evaluated from the pre-fixed effectiveness. This can be an issue when the compressor inlet temperature decreases to transcritical or subcritical region. This may alter the optimal point of the S-CO2 power cycle. In this paper, optimal design points and optimal performance of the S-CO2 power cycle are tracked with the consideration of the internal pinch point phenomenon. While changing the system boundary conditions, the optimal point variation due to internal pinch point phenomenon is evaluated and compared with a traditional methodology. This research is progressed with an in-house integrated S-CO2 power cycle analysis code, which is named KAIST – ESCA (Evaluator for Supercritical CO2 Cycle based on Adjoint method). The target cycle layouts are Simple Recuperated, Intercooling, Recompression and Recompression with intercooling layouts. Both of the S-CO2 Rankine and Brayton cycles conditions are considered.

Supercritical CO2 (S-CO2) has the potential to be used as the working fluid in a power cycle since S-CO2 shows a density value high as its liquid phase while the viscosity value remains closer to its gaseous phase. Thus, it requires much less work to compress due to its low compressibility as well as relatively small flow resistance. However, the S-CO2 leakage flow from turbo-machinery via seal becomes one of the important issues since not only it influences the cycle efficiency due to parasitic loss but also it is important for evaluating the system safety under various operating conditions. In the previous turbo expo paper, the effect of the tooth length on the critical flow and comparing the results to the existing two phase system analysis code calculation were presented. In this paper, the gap effect, which is simulated by changing the diameter of a orifice and the number of tooth effect in a labyrinth seal geometry nozzle are presented by using the same experimental facility described in the previous paper. In addition, this paper includes the experimental results under various conditions including not only single phase flow such as supercritical, and gaseous state only but also two phase flow condition.

The supercritical carbon dioxide (S-CO2) Brayton power cycle has been receiving worldwide attention due to the high thermal efficiency and compact system configuration. Because of the incompressible liquid like characteristic (e.g. high density, low compressibility) of the CO2 near the critical point (30.98 °C, 7.38MPa), an S-CO2 Brayton cycle can achieve high efficiency by reducing compression work. In order to utilize the S-CO2 power conversion technology in various applications, such as distributed power generation and marine propulsion, air-cooled waste heat removal system is necessary. However, the critical temperature of CO2 (30.98 °C) is an intrinsic limitation on the system minimum temperature. Because of the small difference with atmospheric temperature, a large amount of cooling air flow or a very large heat exchanger is required to reach the target minimum temperature. In this paper, to improve the system efficiency and ease the problem of air-cooled waste heat removal system, the mixture of supercritical CO2 with other fluids has been studied. Also, the preliminary performance test results of CO2 mixture with pre-existing experimental facility are evaluated.

Recently, we have addressed that a formation mechanism of a nanolens array (NLA) fabricated by using a maskless vacuum deposition is explained as the increase in surface tension of organic molecules induced by their crystallization. Here, as another research using finite difference time domain simulations, not electric field intensities but transmitted energies of electromagnetic waves inside and outside top-emitting blue organic light-emitting diodes (TOLEDs), without and with NLAs, are obtained, to easily grasp the effect of NLA formation on the light extraction of TOLEDs. Interestingly, the calculations show that NLA acts as an efficient light extraction structure. With NLA, larger transmitted energies in the direction from emitting layer to air are observed, indicating that NLAs send more light to air otherwise trapped in the devices by reducing the losses by waveguide and absorption. This is more significant for higher refractive index of NLA. Simulation and measurement results are consistent. A successful increase in both light extraction efficiency and color stability of blue TOLEDs, rarely reported before, is accomplished by introducing the highly process-compatible NLA technology using the one-step dry process. Blue TOLEDs integrated with a N, N'-di(1-naphthyl)- N, N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine NLA with a refractive index of 1.8 show a 1.55-times-higher light extraction efficiency, compared to those without it. In addition, viewing angle characteristics are enhanced and image blurring is reduced, indicating that the manufacturer-adaptable technology satisfies the requirements of highly efficient and color-stable top-emission displays.

For the concentrating solar power (CSP) applications, the supercritical carbon dioxide (s-CO2) power cycle is beneficial in many aspects, including high cycle efficiencies, reduced component sizing, and potential for the dry cooling option. More research is involved in improving this technology to realize the s-CO2 cycle as a candidate to replace the conventional power conversion systems for CSP applications. In this study, an isothermal compressor, a turbomachine which undergoes the compression process at constant temperature to minimize compression work, is applied to the s-CO2 power cycle layout. To investigate the cycle performance changes of adopting the novel technology, a framework for defining the efficiency of the isothermal compressor is revised and suggested. This study demonstrates how the compression work for the isothermal compressor is reduced, up to 50%, compared to that of the conventional compressor under varying compressor inlet conditions. Furthermore, the simple recuperated and recompression Brayton cycle layouts using s-CO2 as a working fluid are evaluated for the CSP applications. Results show that for compressor inlet temperatures (CIT) near the critical point, the recompression Brayton cycle using an isothermal compressor has 0.2–1.0% point higher cycle thermal efficiency compared to its reference cycle. For higher CIT values, the recompression cycle using an isothermal compressor can perform above 50% in thermal efficiency for a wider range of CIT than the reference cycle. Adopting an isothermal compressor in the s-CO2 layout can imply larger heat exchange area for the compressor which requires further development.

From the efforts of many researchers and engineers related to the S-CO2 Brayton cycle technology development, the S-CO2 Brayton cycle is now considered as one of the key power technologies for the future. Since the S-CO2 Brayton cycle has advantages in economics due to high efficiency and compactness of the system, various industries have been trying to develop baseline technology on the design and analysis of the S-CO2 Brayton cycle components. According to the previous researches on the S-CO2 Brayton cycle component technology, the treatment of a thermodynamic property near the critical point of CO2 is one of the main concerns since conventional design and analysis methodologies cannot be used for the near critical point region. Among many thermodynamic properties, the stagnation to static condition conversion process is important since the flow in a compressor is at high flow velocity. In this paper, the impact of various stagnation to static conversion methods on the S-CO2 compressor design near the critical point will be evaluated. From the evaluation, the limitation of a certain stagnation to static conversion method will be discussed to provide a guideline for the future S-CO2 compressor designers.

For environmental reason, buildings increasingly install smart windows, which can dim incoming daylight based on active electrochromic devices (ECDs). In this work, multi-layered graphene (MLG) was investigated as an ECD window electrode, to minimize carbon dioxide (CO2) emissions by decreasing the electricity consumption for building space cooling and heating and as an alternative to the transparent conductor tin-doped indium oxide (ITO) in order to decrease dependence on it. Various MLG electrodes with different numbers of graphene layers were prepared with environmentally friendly poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) to produce ECD cells. Tests demonstrated the reproducibility and uniformity in optical performance, as well as the flexibility of the ECD fabrication. With the optimized MLG electrode, the ECD cells exhibited a very fast switching response for optical changes from transparent to dark states of a few hundred msec.

Stem cell therapy has prompted the expansion of veterinary medicine both experimentally and clinically, with the potential to contribute to contemporary treatment strategies for various diseases and conditions for which limited or no therapeutic options are presently available. Although the application of various types of stem cells, such as bone marrow-derived mesenchymal stem cells (BM-MSCs), adipose tissue-derived mesenchymal stem cells (AT-MSCs), and umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs), has promising potential to improve the health of different species, it is crucial that the benefits and drawbacks are completely evaluated before use. Umbilical cord blood (UCB) is a rich source of stem cells; nonetheless, isolation of mesenchymal stem cells (MSCs) from UCB presents technical challenges. Although MSCs have been isolated from UCB of diverse species such as human, equine, sheep, goat, and canine, there are inherent limitations of using UCB from these species for the expansion of MSCs. In this review, we investigated canine UCB (cUCB) and compared it with UCB from other species by reviewing recent articles published from February 2003 to June 2017 to gain an understanding of the limitations of cUCB in the acquisition of MSCs and to determine other suitable sources for the isolation of MSCs from canine. Our review indicates that cUCB is not an ideal source of MSCs because of insufficient volume and ethical issues. However, canine reproductive organs discarded during neutering may help broaden our understanding of effective isolation of MSCs. We recommend exploring canine reproductive and adipose tissue rather than UCB to fulfill the current need in veterinary medicine for the well-designed and ethically approved source of MSCs.

Background It is necessary to store the transplantable sources for a certain period during the variety of manipulation processing steps. The method used to preserve (depending on conditions of solvent, temperature, periods, density, and physical impulse, etc.) can affect the safety and efficacy of the samples. Supercooling refers to a phenomenon of lowering the temperature below its freezing point without freezing. We investigated the possibility of supercooling for the preservation of cells and organs according to the limited conditions. Method The viability of mesenchymal stem cells (MSCs) derived from the intra-abdominal fat of the New Zealand white rabbit were observed, and the neonatal rat kidneys were maintained in histidine-tryptophan-ketoglutarate solution and stored at various temperatures for 48 hours. The supercooling refrigerator was used for −2 °C and −5 °C in controlled preservation conditions. We observed and compared histopathological changes of samples at each temperature condition. Results As time passed, the number of rabbit MSCs decreased in each group with storage temperature. At room temperature, the number of viable MSCs decreased rapidly, but the number of MSCs tended to decrease slowly in the cooling and supercooling groups. The rat kidneys preserved on supercooling temperature at −2 °C tended to have the least damage on the cortex and medulla parenchyma. Conclusions The difference in damage of transplantable sources by storage temperature conditions is the evidence that effectiveness may depend on the storage method. It is necessary to determine further optimal supercooling temperature of the preservation methods with various cells, tissues, and organs in the future.

Although SIGN-R1-mediated complement activation pathway has been shown to enhance the systemic clearance of apoptotic cells, the role of SIGN-R1 in the clearance of radiation-induced apoptotic cells has not been characterized and was investigated in this study. Our data indicated that whole-body γ-irradiation of mice increased caspase-3(+) apoptotic lymphocyte numbers in secondary lymphoid organs. Following γ-irradiation, SIGN-R1 and complements (C4 and C3) were simultaneously increased only in the mice spleen tissue among the assessed tissues. In particular, C3 was exclusively activated in the spleen. The delayed clearance of apoptotic cells was markedly prevalent in the spleen and liver of SIGN-R1 KO mice, followed by a significant increase of CD11b(+) cells. These results indicate that SIGN-R1 and complement factors play an important role in the systemic clearance of radiation-induced apoptotic innate immune cells to maintain tissue homeostasis after γ-irradiation.

The trend of regenerative medicine has been gaining a rising global attention and has been the target of growing research funds. This includes the importance of the application of cell-based therapy, especially stem cells, for various diseases. Hence, regulations on the use of cells and the pros and cons of its application in the clinical level should also be given equal attention. Recently, regulations in Japan have been reviewed and revised to create more effective and competitive marketing strategy. The Regenerative Medicine Promotion Law was established to provide prompt and safe regenerative medicine products. The Acts on the Safety of Regenerative Medicine entails that medical technologies can be categorized into 3 classes of regenerative medicines based on their risks potentials. It also determines the proper regulation or requirement for each class. Amendment of Pharmaceutical Affairs Act, on the other hand, is regulation in which products can be approved with temporary conditions to enable prompt provision of the products to patients after the safety and efficacy is confirmed. Due to these mitigations in Japan in the advancement of regenerative medicines, we can predict that Japan can be one of the top nations in the production and marketing stem cell therapeutic products by attracting Japanese as well as global companies. Hence, monitoring the changes in the legal policies of regenerative medicine in Japan could be advantageous in the advancement of the current provisions in South Korea geared towards the better achievements in providing the human population with safe, prompt, and effective regenerative medicine therapeutic strategies and products.

The stem cell therapy in veterinary medicine continues to grow both experimentally and clinically. Application of adipose-derived mesenchymal stem cell (MSC), umbilical cord blood-derived MSC, bone marrow-derived MSC and skeletal muscle-derived MSC for treatment of various diseases are currently in use for several species. However, the differential efficacies of various approaches are still being investigated. In stem cell therapy, common disease animal models include mouse, rat, rabbit, swine, canine, caprine, equine and dolphin are used. Whereas for clinical models, canine, equine are dolphin are used. We need attention and participation from the researchers of tissue engineering and regenerative medicine, and now it is necessary to develop mutual understanding and cooperation between veterinary and human medicine fields. This review is focused on some of the recent status of stem cell therapy in the veterinary medicine.

One of the most promising approaches to recover the waste heat from internal combustion engines is the Organic Rankine Cycle owing to its efficiency and reliability. The design optimization of ORC, however, is nontrivial because there exist many design variables and practical considerations. The present paper proposes a comprehensive design methodology to optimize the Organic Rankine Cycles (ORC) considering a wide range of design variables as well as practical aspects such as component limitations and costs. The design process is comprised of three steps: heat source selection, candidate fluid selection, and thermodynamic cycle optimization. In order to select the best waste heat source, the available energy and other practical considerations of various heat sources have been compared. Among others, the Exhaust Gas Recirculation (EGR) cooler is found to be the best heat source, and thus used for the rest of this study. Based on a systematic working fluid analysis, Ethanol, Pentane, and R245fa are selected as three candidate fluids. For the comprehensive ORC optimization, four types of cycle layouts are considered; 1) subcritical cycle without a recuperator, 2) subcritical cycle with a recuperator, 3) supercritical without a recuperator, and 4) supercritical cycle with a recuperator. Four cycle layouts coupled with three candidate fluids give a total of twelve cycle analyses. Results show that the best performance is provided by the regenerative subcritical cycle with Ethanol, while the solution with minimum capital cost is the subcritical cycles with Ethanol but without a recuperator.

In the development of novel tissue engineering and regenerative medicine techniques in humans, preclinical studies using laboratory animal models are required to examine the pathogenic mechanisms and the potential treatment of diseases for the clinics and an indispensable step for determination of their safety and efficacy. Regrettably, the etiological pathology of diseases of spontaneous diseases may not be exactly the same despite the similarities in signs and symptoms observed in artificial laboratory animal models. Therefore, the artificial laboratory animal model is not fully suitable for studies on specific target diseases. However, the animals, especially companion animal, that have spontaneous and frequently occurring diseases due to genetic and environmental factors mostly likely mimic the naive pathology of diseases in humans. Consequently, these species can be better subjects of preclinical studies and veterinary clinical trials in order to possibly gauge the effectiveness of the therapeutic strategies in the clinical stage. Hence, research on the spontaneous and frequently diagnosed diseases of animals predisposed by the type of breeding, age, and gender that are applicable in tissue engineering and regenerative medicine could be an important data for future advancements. In this study, we conducted a survey on the spontaneous and common diseases of canine and feline species to provide a foundation on the effectiveness and practical application of clinical studies. Therefore, this review can contribute significant development in tissue engineering and regenerative medicine in the future. Tissue Eng Regen Med 2015;12(Suppl 2):84-93

This article overall describes the development of histological method especially, cartilage and bone research in regenerative medicine. Kawamoto’s film method, which has been recently introduced into our laboratory, has been applied in various fields that make sectioning of hard tissues easier than the conventional method. Moreover, this method also does not require the time-consuming chemical fixation and/or decalcification process. Kawamoto method involves the use of the adhesive plastic film instead of a cover glass where the thin tissue sections are attached efficiently at low temperatures (-25°C). Furthermore, the histological method preserves the enzymatic activity in the fresh sections in comparison to that of chemically-treated tissue sections. In fact, we used this Kawamoto’s film method in one of our researches in which drug repositioning was employed for cartilage regeneration. Some of the Kawamoto-processed tissue sections are featured in this review article. Therefore, the application of this tissue preparation technique allowed effective and histological and histochemical studies within a shorter preparation time with ease and convenience. In the future, this Kawamoto method may offer further applications in the preparation of a more diverse tissues and samples not only in the preclinical but also in the clinical studies.

Optical, interfacial and patterning issues of anode graphene films in organic light emitting diode (OLED) applications were investigated. In the optical part, the microcavities of graphene and indium tin oxide (ITO) anode OLEDs were contrasted. With the use of graphene one may avoid spectral and organic stack design problems related to microcavity problems. However, due to the weak microcavity, emission enhancement using interference designs is practically impossible. By inserting an electron acceptor insert at the graphene/hole transport layer (HTL) interface, it was possible to enhance the current density by factor of three. Based on in situ ultraviolet photoelectron spectroscopy (UPS) results, the insert was interpreted as being a charge generation layer. Graphene patterning using laser or plasma methods turned out to be problematic. None of those methods could offer acceptable dimension accuracy and preserved graphene quality.

Reported in this work is the fabrication of white transparent organic light-emitting diodes (TOLEDs) with high color rendering indices (CRIs). An architecture in which the green and red emission layers are sandwiched between two blue emissions layers was used. By tuning the thicknesses of the green and red emission layers, CRI and power efficiency values of 90/20.5 and 87/6.8 lm/W were achieved in the bottom and top emissions, respectively. The study results suggest an effective engineering approach for realizing high CRI white TOLED lighting sources.

We report on a novel fabrication method for organic lightemitting diodes (OLEDs) by using a multilayered graphene (MLG) film and a lamination technique. The OLED structure with the MLG top electrode has higher transmittance and lower reflectance than the OLED structure with the conventional thin metal electrode. Moreover, higher luminous current efficiency of the device with the MLG top electrode has been achieved compared with that of the conventional bottom-emission OLEDs with aluminum metal electrode.

Supercritical-CO2 Brayton cycle has been recently gaining a lot of attention for the mild temperature (450–650 °C) heat source application due to its high efficiency and compact footprint as the system layout of S–CO2 cycle is simple and small turbomachinery and compact micro-channel heat exchangers are utilized. As CO2 properties behave more like an incompressible fluid near the critical point (30.98 °C, 7.38 MPa), the control of compressor operating condition and stability is the key technology that influences the cycle efficiency. Based on the previous works on the S–CO2 test facilities from various research institutions, a Korean research team designed the SCIEL (Supercritical CO2 Integral Experiment Loop) to achieve higher efficiency with higher pressure ratio with S–CO2 power cycle compared to other pre-existing facilities. This paper will describe the underlying design principles of the integral experiment facility and the current status of SCIEL which is being constructed in KAERI (Korea Atomic Energy Research Institute).

Mixed convection in vertical upward heated flow has been intensively studied in the last few years since it reduces the heat transfer capability of the system in the deteriorated turbulent heat transfer (DTHT) regime. Several mixed turbulent heat transfer correlations have been proposed, but the best correlation to be used in DTHT regime for water in vertical upward heated flow is yet to be determined. Furthermore, the relation between momentum flux and heat flux in mixed convection regime is still unclear. This paper presents comparison of several mixed turbulent heat transfer correlations performance of water up-flow in a circular tube by numerical approach using v2–f turbulence model. The existing correlation of Symolon et al. showed the best agreement with the numerical analysis results in predicting the heat transfer capability of a water-cooled system while Petukhov and Polyakov correlation showed a good agreement to correlate the momentum and heat transport behavior in the mixed convection turbulent regime.

In this paper, we suggest the conceptual design of a water-cooled reactor system for a low-pressure inherent heat sink nuclear desalination plant (LIND) that applies the safety-related design concepts of high temperature gas-cooled reactors to a water-cooled reactor for inherent and passive safety features. Through a scoping analysis, we found that the current LIND design satisfied several essential thermal–hydraulic and neutronic design requirements. In a thermal–hydraulic analysis using an analytical method based on the Wooton–Epstein correlation, we checked the possibility of safely removing decay heat through the steel containment even if all the active safety systems failed. In a neutronic analysis using the Monte Carlo N-particle transport code, we estimated a cycle length of approximately 6 years under 200 MWth and 4.5% enrichment. The very long cycle length and simple safety features minimize the burdens from the operation, maintenance, and spent-fuel management, with a positive impact on the economic feasibility. Finally, because a nuclear reactor should not be directly coupled to a desalination system to prevent the leakage of radioactive material into the desalinated water, three types of intermediate systems were studied: a steam producing system, a hot water system, and an organic Rankine cycle system.

The new assymmetric limb-structured blue light emitting material, composed of anthracene main core, naphthalene units at 9, 10-position of anthracene and xylene units at 2,3-positon of anthracene, was designed and synthesized. The three-dimensional structure from theoretical calculation was characterized to elucidate non-copolar structure with inhibited intermolecular interaction. The limb-structured blue material was thermally stable up to 373 degrees C with T(g) of 143 degrees C. ITO/TAPC/CBP (3% BMPNA)/Bphen/LiF/Al device exhibits the maximum quantum efficiency of 3.42% and maximum current efficiency of 3.07 cd/A with deep blue emission of (0.141, 0.115) CIE coordinates.

A High Temperature Gas-cooled Reactor (HTGR) system was generally designed and planned to be constructed in a medium size reactor (around 600 MWe power output) in the past. In this paper, authors are exploring the potential of very small modular type HTGR with a special attention given to the power conversion system. Since HTGR is relatively less challenging to achieve passive safety while easy to adopt an air-cooled Brayton cycle for a power conversion system, HTGR can be suitable for a small modular reactor application. However, as the size of the power system decreases the consisting component performance usually degrades and the final effect on the total system performance was not seriously studied before for a small size HTGR system. 20 MWth reactor was chosen for this study to investigate how helium Brayton cycle performance can be affected by the component level performance and how the optimal operating condition shifts when the system size reduces. The discussion of component design that can deliver assumed performance for the cycle estimation will be briefly presented as well. Furthermore, a supercritical CO 2 cycle option will be compared to the helium Brayton cycle to show that the S-CO 2 cycle can be a good alternative for a very small scale system.

Due to the very low light extraction efficiency of conventional organic light-emitting diodes (OLEDs), the application of OLEDs for next-generation lighting remains limited. Therefore, in order to enhance the light extraction efficiencies that result in improving the luminous efficacy (LE, lm W−1) and external quantum efficiency (ηEQE, %) of OLEDs, three different geometrically profiled, negatively nanostructured periodic semi-pyramid polydimethylsiloxane (PDMS) layers are used to create a hole at depths of 500 nm, 650 nm, and 1000 nm; these are designated as the polymeric lighting extraction film (PLEF) I, PLEF II, and PLEF III, respectively. These layers are placed directly on the backside of the green emissive bottom-emitting OLED (BE-OLED) glass substrates as an outcoupling enhancement PLEF that improves the glass substrate/air interface. Through the simple combination with three different nanostructures on each green emissive BE-OLED, a maximum enhancement of up to 50% is achieved in the LE and ηEQE measured at the same brightness, which is 1.5 times higher than the reference green emissive BE-OLED without a PLEF. Therefore, global energy saving can be achieved through reducing the power consumption by up to 30% possibly estimated from LE using the integrated PLEFs.

Islet Encapsulation Using Chondrocyte Jeong Ik Lee, D.V.M., Joon Ye Kim, M.S., Jae Geun Lee, M.D. and Yu Seun Kim, M.D. Departments of Veterinary Medicine, College of Veterinary Medicine and Biomedical Science and Technology, Konkuk University, The Research Institute for Transplantation, Yonsei University College of Medicine, Department of Transplantation Surgery, Severance Hospital, Yonsei University Health System, Seoul, Korea

Various supercritical carbon dioxide (S–CO 2 ) cycles for a power conversion system of a Molten Carbonate Fuel Cell (MCFC) hybrid system are studied in this paper. Re-Compressing Brayton (RCB) cycle, Simple Recuperated Brayton (SRB) cycle and Simple Recuperated Transcritical (SRT) cycle layouts were selected as candidates for this study. In addition, a novel concept of S–CO 2 cycle which combines Brayton cycle and Rankine cycle is proposed and intensively studied with other S–CO 2 layouts. A parametric study is performed to optimize the total system to be compact and to achieve wider operating range. Performances of each S–CO 2 cycle are compared in terms of the thermal efficiency, net electricity of the MCFC hybrid system and approximate total volumes of each S–CO 2 cycle. As a result, performance and total physical size of S–CO 2 cycle can be better understood for MCFC S–CO 2 hybrid system and especially, newly suggested S–CO 2 cycle shows some success.

Structural integrity of intermediate Printed Circuit Heat Exchanger (PCHE) for Sodium-cooled Fast Reactor (SFR) attached to Supercritical CO 2 (S-CO 2 ) is investigated. ANSYS-Mechanical was used to simulate stress fields of representative PCHE channels, with temperature fields imported from FLUENT simulation. Mechanical stress induced by pressure loading is found to be the primary source of stress. As plasticity sufficiently lowers local stress concentration at PCHE channel tips, PCHE type intermediate heat exchangers made of SS316 are anticipated to reliably assure compliance with design standards prescribed in the ASME standards, thanks to the structure temperature that is below the effective creep inducing point. The actual life time of PCHE for SFR-SCO 2 is likely to be affected by mechanical behavior change of SS316 with reactions with S-CO 2 and fatigue.

The carrier injection efficiencies of organic light-emitting diodes with a multilayer graphene (MLG) anode were compared for different hole injection layers (HIL). The energy level alignments at the hole injecting interface were also studied by using the ultraviolet photoelectron spectroscopy (UPS). We employed 1,1-bis[4-[N,N′-di(p-tolyl)amino]phenyl]cyclohexane (TAPC) as the hole transporting materials, while N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine (NPB) or 1,4,5,8,9,12-hexaaza-triphenylene-2,3,6,7,10,11-hexacarbonitrile (HAT-CN) was used as the HIL. The current–voltage characteristics of hole-only devices showed that the MLG anode was only slightly inferior to the indium-tin oxide (ITO) anode in hole injection performance for all the HIL layers. The best efficiency was observed for both MLG and ITO anodes with HAT-CN HIL. We compared UPS-measured energy level alignment of TAPC/HIL/MLG interface for different HILs and concluded that the unique charge generation interface at TAPC/HAT-CN played a crucial role for the improved performance of HAT-CN HIL.

From the Fukushima accident, protection of NPPs from any imaginable natural disasters became very important. In this study, the authors suggest a new concept of ocean nuclear power plant (ONPP) by using SMART as a reference reactor, which is the most recent Small Modular Reactor (SMR) developed by Korea, to demonstrate that the proposed concept can improve the safety of NPP from earthquake and tsunami. The proposed concept utilizes Gravity Based Structure (GBS), which is a widely spread construction technique of offshore plants. Because, floating type or submerged type NPPs can be easily affected by severe ocean environments such as tsunamis and storms, additional safety features have to be added to the existing land based plant. In contrast, the newly proposed GBS-type ONPP does not require going through significant design modifications due to inherent characteristics of the construction method. The authors have demonstrated this concept can be applied to the large nuclear power plant in the previous work and will expand this concept for SMRs in this paper. The authors discuss the new concept by presenting design parameters, design requirements, and the new total general arrangement. Furthermore, due to the unique configuration of ONPP SMART, innovative passive safety features can be added to the existing SMART design. The performance of proposed concept to resist earthquake as well as newly added passive safety feature will be discussed by presenting simplified analysis results.

We developed a highly refractive index planarization layer showing a very smooth surface for organic light-emitting diode (OLED) light extraction, and we successfully prepared a highly efficient white OLED device with an embossed nano-structure and highly refractive index planarization layers. White OLEDs act as an internal out-coupling layer. We used a spin-coating method and two types of TiO2 solutions for a planarization of the embossed nano-structure on a glass substrate. The first TiO2 solution was TiO2 sol, which consists of TiO2 colloidal particles in an acidic aqueous solution and several organic additives. The second solution was an organic and inorganic hybrid solution of TiO2. The surface roughness (Ra) and refractive index of the TiO2 planarization films on a flat glass were 0.4 nm and 2.0 at 550 nm, respectively. The J–V characteristics of the OLED including the embossed nano-structure and the TiO2 planarization film were almost the same as those of an OLED with a flat glass, and the luminous efficacy of the aforementioned OLED was enhanced by 34% compared to that of an OLED with a flat glass.

As a part of Sodium-cooled Fast Reactor (SFR) development, the supercritical CO2 (S-CO2) Brayton cycle is considered as an alternative power conversion system to eliminate sodium-water reaction (SWR) from the current conventional steam Rankine cycle is utilized with SFR. The leakage flow of S-CO2 from turbo-machinery via seal becomes one of important issues since not only it influences the cycle efficiency due to parasitic loss but also it is important for evaluating the system safety under various operating conditions. Thus, a transient simulation for estimating the critical flow in a turbo-machinery seal is essential to predict the leakage flow rate and calculate the required total mass of working fluid in a S-CO2 power system. This paper briefly reviews the advantages of supercritical CO2 Brayton cycle relative to a typical steam Rankine cycle used in the Sodium-cooled Fast Reactor. In addition, this paper describes the test data using a CO2 critical flow experimental facility with three orifice configurations to model the flow resistance of a rotating shaft labyrinth seal. This data is used for validation of an existing transient analytical tool developed for transient hydraulic system analysis. Contained within this code is the analysis approach of Henry/Fauske from 1971 for two phase critical flow of one-component mixtures. This paper presents prediction of transient pressure, temperature, and flow profiles for critical and sub-critical flows of CO2 relative to blowdown test data to show that reasonable results are obtained. Similar analyses relative to test results of three orifice configurations are conducted and it shows that multiple orifices increase the time to equalize pressure in the blowdown system and therefore equates to higher flow resistance and lower leakage.

For the concentrating solar power (CSP) applications, the supercritical carbon dioxide (s-CO2) power cycle is beneficial in many aspects, including higher cycle efficiencies, reduced component sizing, and potential for the dry cooling option, in comparison to the conventional steam Rankine cycle. Increasing number of investigations and research projects are involved in improving this technology to realize the s-CO2 cycle as a candidate to replace the conventional power conversion systems. In this conceptual study, an isothermal compressor, a turbomachine which undergoes the compression process at constant temperature to minimize compression work, is applied to the s-CO2 power cycle layout. To investigate the cycle performance changes of adopting the novel technology, a framework for defining the efficiency of the isothermal compressor is revised and suggested. This study demonstrates how the compression work for the isothermal compressor is reduced compared to that of the conventional compressor under varying compressor inlet conditions. Furthermore, the recompression Brayton cycle layout using s-CO2 as a working fluid is evaluated for the CSP applications. Results show that for compressor inlet temperatures (CIT) near the critical point, the simple recuperated Brayton cycle with an isothermal compressor performs better than the given reference recompression cycle by 6–10% points in terms of cycle thermal efficiency. For higher CIT values, the recompression cycle using an isothermal compressor can perform above 50% in thermal efficiency. Adopting an isothermal compressor in the s-CO2 layout, however, can imply larger heat exchange area for the compressor which requires further detailed design for realization in the future.

Immune tolerance at feto-maternal interfaces is a complex phenomenon. Although maternal decidual macrophages are well-known immune cells, little is known about fetal-derived macrophages (Hofbauer cells) within chorionic villi. Preeclampsia (PE) is a major cause of maternal mortality in the field of obstetrics, and the innate immunological role of maternal decidual macrophages is well known. In this study, we assessed the differential phenotypes and marker expression in fetal macrophages, known as dendritic cell-specific ICAM-grabbing non-integrin (DC-SIGN)-positive Hofbauer cells. We compared Hofbauer cell properties between normal and PE placenta chorionic villi and performed sequential staining of DC-SIGN, CD14, and CD68 to evaluate the existence of Hofbauer cells. Furthermore, to evaluate the immunological function of these cells, we stained the cells for CD163, a marker of immunoregulatory type 2 (M2) macrophages. Additionally, we examined the expression of the immunosuppressive cytokine interleukin (IL)-10, which is known to be produced by M2 macrophages. DC-SIGN+/CD14+, DC-SIGN+/CD68+, and CD163+/DC-SIGN+ cells were quantified based on photomicrographs. The results showed that CD14, CD163, DC-SIGN, and IL-10 levels were significantly downregulated in PE compared with normal. Additionally, CD163+/DC-SIGN+ Hofbauer cells were significantly less frequent in PE than in normal. DC-SIGN Hofbauer cells produced IL-10 at lower levels in the PE than in the normal. Thus, we speculate that fetal-derived Hofbauer cells may play an important role in normal pregnancy with immunosuppressive effects based on their M2 macrophage characteristics to maintain immune tolerance during pregnancy. Additionally, in PE, these functions were defective, supporting the roles of these macrophages in PE development.

Semi-transparent, colored organic light-emitting diodes (OLEDs) were demonstrated by comprising a microcavity-embedded structure that uses an organic layer sandwiched between thin metal layers as the cathode. Without bias, the colored OLEDs exhibited various colors depending on the metal/organic/metal cathode configuration, by means of internal interference effects under ambient illumination. By varying the thickness of the organic layer, the transmittance and reflectance of the colored OLEDs could be controlled. The influence of the microcavity cathode on the light-emitting performances of OLEDs, such as the efficiencies and the electroluminescence spectra, was also studied.