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The CoFe2O4–Er0.4Bi1.6O3 as a novel bifunctional oxygen electrode exhibits efficient ORR and OER bifunctionality for reversible SOCs at intermediate temperatures.

Solid oxide fuel cells (SOFCs) are promising energy conversion devices because of their high electrical efficiency, even for small power systems. However, when the anode is exposed to reduction and oxidation (redox) cycles, the Ni phase causes a large microstructural change as a result of its chemical expansion and contraction. This negatively affects the electrochemical performance. However, most studies have focused on the redox cycling behaviors of SOFCs at high operation temperatures (≥ 800 °C). Therefore, in this study, we investigate the degradation behavior of the SOFC anode during redox cycles at 500 °C. To identify the individual steps of the electrochemical processes of the anode, in-situ monitored impedance spectra were analyzed using the distribution of relaxation time method at various oxygen and hydrogen partial pressures. Consequently, the electrode polarization process was deconvoluted into five sub-processes. During the redox cycles, three major peaks were altered: gas phase diffusion in the anode substrate (10–1–101 Hz), gas diffusion coupled with charge transfer reaction and ionic transport (102–103 Hz) and charged species across the Ni–yttria stabilized zirconia interface at the anode (103–104 Hz). The major degradation of the electrode performance at 500 °C was attributed to the increase in gas phase diffusion resistance due to Ni phase aggregation and the decrease in porosity in the anode during the redox cycles. This was confirmed by microstructural analysis. By contrast, the other two processes (102–103 and 103–104 Hz) compensated each other, thus having negligible effect on performance degradation.

Solid oxide cells (SOCs) are mutually convertible energy devices capable of generating electricity from chemical fuels including hydrogen in the fuel cell mode and producing green hydrogen using electricity from renewable but intermittent solar and wind resources in the electrolysis cell mode. An effective approach to enhance the performance of SOCs at reduced temperatures is by developing highly active oxygen electrodes for both oxygen reduction and oxygen evolution reactions. Herein, highly conductive Sm3+ and Nd3+ double-doped ceria (Sm0.075Nd0.075Ce0.85O2-δ, SNDC) is utilized as an active component for reversible SOC applications. We develop a novel La0.6Sr0.4Co0.2Fe0.8O3 -δ (LSCF)-SNDC composite oxygen electrode. Compared with the conventional LSCF-Gd-doped ceria oxygen electrode, the LSCF-SNDC exhibits ∼35% lower cathode polarization resistance (0.042 Ω cm2 at 750 °C) owing to rapid oxygen incorporation and surface diffusion kinetics. Furthermore, the SOC with the LSCF-SNDC oxygen electrode and the SNDC buffer layer yields a remarkable performance in both the fuel cell (1.54 W cm-2 at 750 °C) and electrolysis cell (1.37 A cm-2 at 750 °C) modes because the incorporation of SNDC promotes the surface diffusion kinetics at the oxygen electrode bulk and the activity of the triple phase boundary at the interface. These findings suggest that the highly conductive SNDC material effectively enhances both oxygen reduction and oxygen evolution reactions, thus serving as a promising material in reversible SOC applications at reduced temperatures.

Reversible solid oxide cells (SOCs) are unique devices that perform interconversion between chemical energy (particularly hydrogen) and electricity, providing efficient energy storage for site-specific and weather-dependent solar and wind resources. One of the key requirements for achieving high-performance reversible SOCs is the development of highly active bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, we investigate a La0.2Sr0.8Co0.8Fe0.2O3−δ (LSCF2882) material as a novel oxygen electrode for reversible SOCs at intermediate temperatures. Unlike most widely used La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF6428) with a rhombohedrally distorted perovskite structure, LSCF2882 possesses a simple cubic perovskite structure with a symmetric BO6 octahedral network. Furthermore, the 3D bond valence sum calculation of the LSCF2882 structure suggests a reduction in oxygen ion conduction barrier energy. Oxygen surface exchange (kchem) and diffusion (Dchem) coefficients of LSCF2882 determined by electrical conductivity relaxation are consistently remarkably higher by >2 and 20 times compared to those of LSCF6428 at 700 °C, respectively. This result is further supported by a 43% reduction in the oxygen vacancy formation energy of LSCF2882 determined from density functional theory calculations. The reversible SOCs with LSCF2882 oxygen electrodes greatly outperform LSCF6428 cells in both fuel cell (2.55 W cm−2) and electrolysis mode (2.09 A cm−2 at 1.3 V) at 800 °C, with excellent reversible cycling stability. Our findings strongly suggest that LSCF2882 is a promising candidate as a bifunctional oxygen electrode for high performance reversible SOCs at reduced temperatures.

The main objective is to identify the level of advancement of safety systems in various levels of smart factories. Smart level verification systems are being implemented in Korea, but safety systems are not paying much attention to smart factory level checks. Using a checklist, nine Korean electronics manufacturing enterprises checked their level of safety system. The checklist consists of 142 items, which were divided into four dimensions (laws and certifications, safety designs and configurations at the facilities, safety devices and guards, and maintenance and training). As a result, a high-ranked enterprise in smart factory level showed excellence in the safety system maturity level as well. Compared to the level of the company's smart factory, the level of advancement of safety systems has been confirmed to be lower.

We demonstrate ultra-fast fabrication of anode-supported solid oxide fuel cells (SOFCs) using microwave-assisted sintering technology. Due to the nature of microwaves that transfers heat directly into the material, the SOFC sintering process was completed within 8 h, ∼ six times faster compared to a conventional sintering process (∼47 h). Despite extremely rapid processing time, the microstructure of the SOFC fabricated by microwave-assisted sintering (M-SOFC) was almost identical to that of the conventionally sintered SOFC. Moreover, the electrochemical performance of the M-SOFC at 750 °C was 0.52 W/cm2 in peak power density, which is even higher than that of the conventionally sintered sample (0.49W/cm2). Thus, our results demonstrate that the ultra-fast microwave-assisted sintering process is a highly effective and practically promising technology for fabricating high performance SOFCs.

There has been very little reported on ginsenoside composition and antioxidant activity of hydroponic-cultured ginseng roots (HCR), leaves (HCL), and stems (HCS). We profiled 6 ginsenoside compounds in HCR, HCL, and HCS using high-performance liquid chromatography. Antioxidative activity of HCR, HCL, and HCS were evaluated using total phenolic content (TPC) and total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical-scavenging activity assays, and ferric reducing antioxidant power (FRAP) assays. Total ginsenoside contents of HCL and HCS were significantly higher than that of HCR (P

The Sr segregation at the surface of a perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) oxygen electrode is detrimental to the electrochemical performance and durability of energy conversion devices such as solid oxide fuel cells. However, a quantitative correlation of degradation of the oxygen surface exchange kinetics with Sr precipitation formation at the LSCF surface is not clearly understood yet. Herein, the correlation of the time-dependent degradation mechanisms of the LSCF catalysts with respect to Sr segregation phenomenon at the surface were investigated at 800 °C for a prolonged annealing time (∼800 h) by combining in situ electrochemical measurements, and ex situ chemical and structural analyses at the multiscale. The in situ monitored surface exchange coefficient (kchem) was found to drastically drop by ∼86% over the 800 h, and it was accompanied by the formation of Sr-containing secondary phases on the bulk LSCF surface, as expected. However, the estimated coverage of Sr segregation on the LSCF surface was only ∼15%, even after 800 h of aging time, showing significant deviation from the kchem degradation rate (∼86%). The surface chemistry evolution at the clean surface area, which is believed to be electrochemically active, was further analyzed on the nanoscale. The quantified results showed that the Sr elemental fraction of the A-site at the outermost surface of the LSCF samples was becoming deficient from ∼4.0 at 0 h to ∼0.27 at 800 h annealing. Interestingly, the time-dependent behavioral tendencies between kchem degradation and surface Sr fractional changes were highly analogous. Thus, our results suggest that this Sr deficiency at the clean surface region more dominantly impacts the degradation process rather than an electrochemical activity passivation by the SrOx precipitates, which has been shown to be a major degradation mechanism of LSCF performance.

Herein, we developed a nanostructured Co3O4 and bio-inspired carbon (BIC) composite by a facile hydrothermal reaction as a supercapacitor electrode material. Microstructural analysis revealed that the BIC-Co3O4 composites possessed the hierarchical structure with a microflower shape consisting of thin nano-petals. Due to its characteristic nanostructure, the BIC-Co3O4 electrode exhibited a high specific capacitance of 473 F/g at a current density of 1 A/g. Moreover, the all-solid-state symmetric device with this electrode delivered the energy density of 17 Wh/kg at a power density of 184 W/kg with remarkable cycling stability over 10,000 cycles.

Herein, for the first time, we demonstrate ultra-fast fabrication of a tape casted NiO-yttria stabilized zirconia (YSZ) anode support for solid oxide fuel cells (SOFCs) using resonant acoustic mixing (RAM) technology. Due to its characteristics of non-contact and high-intensity acoustic field-assisted mixing, NiO-YSZ tape-cast slurry is prepared via a RAM process within ∼0.5 h, > 140 times faster than use of a conventional ball-milling (BM) process (∼72 h). During the RAM process, liquid binders more effectively penetrate into soft agglomerated ceramic powders and covered larger surface area than the case of BM process. The optimization of RAM procedure requires more subdivided mixing sequence and higher content of binders and plasticizers compared to that of the BM. Despite drastically reduced mixing time, the microstructures of RAM Ni-YSZ anode, quantified via a 3D reconstruction, are statistically identical to that of BM Ni-YSZ. The SOFC employing RAM Ni-YSZ anode support achieves 0.55 W/cm2 at 750 °C in peak power density and exhibits high durability for 300 h without noticeable degradation. Thus, our results demonstrate that the RAM process is a highly effective and ultra-fast mixing technology to produce high performance SOFC components.

The rational design and exploration of the metal oxide-carbon composite are greatly desired for enhanced supercapacitor application. Herein, we develop a novel Bi2MoO6 and carbon sphere hybrid mate...

Monolayer MoS2 layered crystals have attracted significant attention owing to their potential applicability in emerging devices, and chemical vapor deposition (CVD) is the best method so far to obtain monolayer MoS2 single crystals. Although many studies have been published on MoS2 monolayer crystals grown by CVD, there is a lack of understanding of its synthesis pathway. Therefore, in this paper, we studied the mechanism of the synthesis pathway when monolayer MoS2 crystals are synthesized by conventional CVD using MoO3 and sulfur powders. It was found that solid MoO2 produced by the reduction of MoO3 by sulfur plays a very important role in the synthesis of MoS2 layered crystals as an intermediate phase.

Composite cathodes comprising nanoscale powders are expected to impart with high specific surface area and triple phase boundary (TPB) density, which will lead to better performance. However, uniformly mixing nanosized heterophase powders remains a challenge due to their high surface energy and thus ease with which they agglomerate into their individual phases during the mixing and sintering processes. In this study, we successfully synthesized La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF)–Gd0.1Ce0.9O1.95 (GDC) composite cathode nanoscale powders via an in situ sol–gel process. High-angle annular dark field scanning transmission electron microscopy analysis of in situ prepared LSCF–GDC composite powders revealed that both the LSCF and GDC phases were uniformly distributed with a particle size of ∼90 nm without cation intermixing. The in situ LSCF–GDC cathode sintered on a GDC electrolyte showed a low polarization resistance of 0.044 Ω cm2 at 750 °C. The active TPB density and the specific two phase (LSCF/pore) boundary...

Solid oxide fuel cells (SOFCs) are attracting much attention as alternative energy conversion devices owing to their high energy conversion efficiency and fuel flexibility. Currently, Ni-based cermets or Ni-based bimetal are often being used as anode materials for SOFCs. However, in anode materials, metallic spherical particles generally agglomerate, which affects the electrode reaction under reduction conditions at high temperature. Furthermore, such agglomeration affects both microstructure of the electrode and the cell stability. To overcome this problem, in this study, we designed a bimetallic anode and fabricate it by electrospinning. This Ni-Fe fiber anode exhibits enhanced anodic activity and tolerance to coarsening of metallic particle compared to the Ni-Fe spherical powder. The ohmic and polarization resistance of Ni-Fe fiber anode is lower than Ni-Fe powder anode at all operation temperature. In addition, the single cell using Ni-Fe fiber anode shows higher maximum power densities of 0.40, 0.80, and 1.64 W/cm2 at 973, 1073, and 1173 K, respectively. Such enhanced power generation properties and lower resistance originated from continuous pathways for excellent charge transport pathways generated by electrospinning and the enhanced gas-diffusion properties of the nanofibers. These results demonstrate that the introduction of Ni-Fe fiber anode in SOFCs is an effective approach to enhance their power generation properties and stability.

A unique nanostructured NiO-yttria-stabilized zirconia (YSZ) composite is synthesized in-situ via a water-in-oil microemulsion technique for the solid oxide fuel cell (SOFC) anode. Thermogravimetric analysis and X-ray diffraction confirm that as-synthesized powders are crystallized in-situ at ∼500 °C as the distinct NiO and YSZ phases without any impurities. Moreover, transmission electron microscopy analysis reveals that the as-synthesized primary particles via microemulsion are ∼40 nm in size and have a characteristic structure in which NiO and YSZ nanograins are heterogeneously distributed. The electrochemical activity of the nanostructured NiO-YSZ composite is evaluated using an YSZ supported cell with a La0.8Sr0.2MnO3-δ-YSZ (50:50 wt.%) cathode. The maximum power density of the SOFC employing the microemulsion-mediated NiO-YSZ anode is 2.2 times greater than that of the SOFC with the conventionally ball-milled nano-sized NiO-YSZ anode. The higher performance with our nanocomposite NiO-YSZ anode is primarily attributed to its heterogeneous nanograin structure, thus leading to a significant increase in triple phase boundary densities.

The Sr segregation at the surface of a perovskite La

There has been very little reported on ginsenoside composition and antioxidant activity of hydroponic-cultured ginseng roots (HCR), leaves (HCL), and stems (HCS). We profiled 6 ginsenoside compounds in HCR, HCL, and HCS using high-performance liquid chromatography. Antioxidative activity of HCR, HCL, and HCS were evaluated using total phenolic content (TPC) and total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical-scavenging activity assays, and ferric reducing antioxidant power (FRAP) assays. Total ginsenoside contents of HCL and HCS were significantly higher than that of HCR (P

Solid oxide cells (SOCs) have been reported as promising energy production and storage devices due to their high efficiency and low pollutant emissions. A key barrier to achieve high performance of SOCs is high electrode polarization resistance which attributes to the sluggish kinetics of oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) at reduced temperatures. One of the potential oxygen electrodes is a perovskite La0.6Sr0.4Co0.2Fe0.8O3- δ(LSCF6428) with mixed ionic and electronic conduction (MIEC) because of its considerable conductivities and good chemical compatibility with conventional electrolyte materials such as ceria-based oxides. However, upon long-term operation under fuel cell conditions, the LSCF6428 electrode is usually subjected to severe degradation of ORR kinetics owing to chemical instability. It has been well known that the tailoring the chemical composition of the perovskite material strongly modulates their electrochemical activities and oxygen ion transport properties. In this study, we synthesized the La0.2Sr0.8Co0.8Fe0.2O3- δ (LSCF2882) and systematically investigated its characteristics on intrinsic properties. In addition, we evaluated oxygen transport kinetics and electrochemical performance of LSCF2882 as an oxygen electrode for reversible SOC applications.

To lower the carbon emission from the rising consumption of fossil fuels, electrochemical devices such as fuel cells and batteries, which can produce or store electricity from renewable resources, are attracting attention. Both systems require an electronically insulating solid membrane, which separates the cathode and anode to prevent short-circuiting. To improve the performance of porous electrodes, researchers have focused on tuning the electrode microstructure. The addition of highly ionic conducting materials to the electrode is commonly used to maximize the reaction site density. However, microstructural features, such as particle size distribution, electrochemically active site density and connectivity of each phase, are difficult to quantify only using conventionally used characterization methods such as scanning electron microscopy (SEM). One well-established method for obtaining three-dimensionally interconnected microstructural information is serial sectioning using a FIB/SEM dual beam system. Using this technique, more reliable and accurate quantification of the SOFC and ASSLIB electrodes microstructure are available. Also, the quantified features will be reflected in the responses of electrochemical impedance spectroscopy (EIS) measurements. These results can provide a link between them. Therefore, the aim of this study is to three-dimensionally reconstruct the microstructure of solid-state energy devices via FIB/SEM dual beam system and to quantify their microstructural features. Also, these results will be combined with the electrochemically analyzed properties to further understanding their relationship with microstructural properties.

벼 재배시 경운과 재배방법 따른 메탄 발생량 및 토양탄소함량변화를 구명하기위해 경운-이앙, 경운-무논점파, 최소경운-건답직파 및 무경운-건답직파를 비교하는 시험을 수행한 결과 다음과 같다. 1. 메탄 발생량은 경운-이앙 처리구에서 가장 많았으며 경운-무논점파>최소경운-건답직파=무경운 건답직파 순으로 적었다...

No-tillage dry-seeding of rice can offer potential benefits by reducing time and labor cost compared with conventional tillage practices. This study was conducted to investigate the effects of no-tillage dry-seeding on rice growth and soil hardness in comparison with other rice cultivation methods, machine transplanting and wet-hill-seeding on puddled paddy. The seedling stand fell within optimum range for both no-till dry-seeding and wet-hill-seeding on puddled paddy. Plant height, number of tillers and SPAD values in no-tillage dry-seeding cultivation were higher than those observed in other methods. There were no significant differences in grain yield of rice among three cultivation methods. The quality characteristics of milled rice grown in no-tillage dry-seeding were similar to those grown in other cultivation methods. Soil hardness in top 10 cm depth was significantly higher in no-tillage dry-seeding than other cultivation methods, while soil hardness below 10 cm depth was highest in machine transplanting cultivation. Results indicate that no-tillage dry-seeding practice is comparable to conventional tillage system in terms of seedling establishment, growth, yield and grain quality.

Ultra-fine Gd-doped ceria (GDC) powders were synthesized via co-precipitation using ammonium carbonate as the precipitant. The crystallite size of the resultant GDC powders was measured as ∼33 nm. The dilatometry test of the powder compacts and the relative density measurement of sintered pellets with various sintering temperatures revealed the synthesized nano-GDC powders had superior sinterability compared to commercial GDC powders (e.g., 96% vs 78% in relative density at 1300 °C, respectively). Based on the total conductivity measurement of the co-precipitated GDC via electrochemical impedance spectroscopy, we found there was an optimum sintering temperature range (1300–1400 °C) to achieve both high density and high conductivity due to significant increase in grain boundary resistance at higher temperature (1500 °C). Moreover, the nano-sized and highly sinterable co-precipitated GDC effectively enhanced oxygen reduction reaction at the La0.6Sr0.4Co0.2Fe0.8O3−δ/GDC composite cathode due to increase in active reaction sites as well as enhanced phase connectivity in 3D-bulk at lower sintering temperatures.

We develop a novel nanocomposite electrolyte, consisting of yttria-stabilized zirconia (YSZ) and erbia-stabilized bismuth oxide (ESB). The 20 mol% ESB-incorporated YSZ composite (20ESB-YSZ) achieves the high density (>97%) at the low sintering temperature of 800 °C. The microstructural analysis of 20ESB-YSZ reveals the characteristic nanocomposite structure of the highly percolated ESB phase at the YSZ grain boundaries (a few ∼ nm thick). The ionic conductivity of 20ESB-YSZ is increased by 5 times compared to that of the conventional YSZ due to the fast oxygen ion transport along the ESB phase. Moreover, this high conductivity is maintained up to 580 h, indicating high stability of the ESB-YSZ nanocomposite. In addition, the oxygen reduction reaction at the composite electrolyte/cathode interface is effectively enhanced (∼70%) at the temperature below 650 °C, mainly due to the fast dissociative oxygen adsorption on the ESB surface as well as the rapid oxygen ion incorporation into the ESB lattice. Thus, we believe this ESB-YSZ nanocomposite is a promising electrolyte for high performance solid oxide fuel cells at reduced temperatures.

Buckwheat (Fagopyrum esculentum MOENCH) is a traditional Korean crop that gaining global attention as a health food due to its rich nutrition. Climate change effects such as high temperature, cold weather, flooding, and drought induce plant stress, reduced production yield of upland crops. In general, buckwheat is grown during the fall season in Korea. Flooding is a severe environmental stress factor, and flooding during the early growth stage of buckwheat causes large reductions in yield. Therefore, we established optimum growth parameters to maximize buckwheat yield. The optimum temperature for harvesting of buckwheat was approximately 1,083 ~ 1,515°C. The number of growing degree days (G.D.D.) from flowering to harvest was 509 ~ 673°C. Plant hight, stem diameter, and dry matter weight were reduced as planting date was delayed (p < 0.05). We investigated buckwheat sowing time during fall, and established an optimum cropping system according to the local climate conditions in central Korea. The growth period of buckwheat cultivar ‘Yangjueol’ was approximately 56 ~ 60 days during fall, and yield was higher than that of cultivar ‘Daesan’. The results indicated that buckwheat yield in central Korea was maximized by sowing cultivar on 25th August and cultivar ‘Daesan’ on 15th August. The yield of Yangjeol sown in spring was 119 kg 10a-1, whereas the yield of Daesan sown in summer was 158kg 10a-1. The results of this study established the effects of sowing time on growth and yield in central Korea. We propose an optimum cropping system for improving quality.

The purpose of this study was to investigate self-esteem, empathy, communication skill and clinical competency, and to identify the influencing factors on clinical competency of nursing students. The data was collectedusing questionnaires from 212 nursing students who were 3rd and 4th years in 2 nursing universities in Daejeon,September 2014. Data was analyzed using Pearson correlation and stepwise multiple regression with IBM SPSS 21. Significant relationships were found among self-esteem, empathy, communication skill and clinical competency in nursing students. The result of stepwise multiple regression indicates that communication skill and self-esteem (F=37.010, p

A functionally graded Bi1.6Er0.4O3 (ESB)/Y0.16Zr0.84O1.92 (YSZ) bilayer electrolyte is successfully developed via a cost-effective screen printing process using nanoscale ESB powders on the tape-cast NiO-YSZ anode support. Because of the highly enhanced oxygen incorporation process at the cathode/electrolyte interface, a novel bilayer solid oxide fuel cell (SOFC) yields extremely high power density of ∼2.1 W cm–2 at 700 °C, which is a 2.4 times increase compared to that of the YSZ single electrolyte SOFC.

A 3-month depot formulation of leuprolide acetate (Luphere 3M Depot) with a mean microsphere diameter of 22.3 μm was prepared aseptically by spray-drying glacial acetic acid solution of the drug and polylactic acid, and lyophilization in a d-mannitol solution. The encapsulation efficiency and loading content of the drug in the Luphere 3M Depot were 94.7% and 9.92% (w/w), respectively. The in vitro release of leuprolide from the depot was substantially delayed and the release profile was similar to that of Lucrin Depot (Abbott Korea, Korea). The safety and pharmacokinetics of leuprolide were investigated over a period of 42 days in 20 prostate cancer patients following a subcutaneous injection of Luphere 3M or Lucrin Depot suspensions (leuprolide acetate dose of 11.25 mg) in a multi-center, randomized, single dose, parallel study. Both formulations were well tolerated by the patients and no serious adverse effects were observed during and after the study. No significant differences were observed in the maximum serum concentration (C

This study was carried out to find optimal rice varieties and selection index for sushi. The suitability tests about appearance and palatability were conducted by 31 professional sushi chefs and the physicochemical and pasting properties of the selected 7 rice varieties (Koshihikari, Dami, Deuraechan, Boramchan, Juanbyeo, Sindongjin and Hopum) of milled and cooked rice were evaluated. According to the adaptability for sushi shape and taste of rice, Hopum and Sindongjin showed more suitable appearance and taste than others. Also, they showed remarkable pasting properties similar to Koshihikari which is widely known as a suitable for sushi. In the relationship between suitability and pasting properties for sushi, peak viscosity and breakdown viscosity showed highly positive correlation, and setback viscosity showed negative correlation. These results suggest that pasting properties can be applied to select the suitable varieties for sushi.

This paper presents a group based propagation method for multi-hop transmission, in order to deliver an emergency message to the reasonable size of vehicle troop. A group head is selected in considering of the position information of vehicles and radio transmission range. With benefits of the group based transmission, it is possible to minimize the unnecessary transmissions and the possibility of message collisions. We evaluate the performance of the proposed scheme compared with conventional schemes. Simulation results show that the message propagation performance is so stable regardless of vehicle`s congestion degree.

An engineering scale test, which is called KENTEX, was carried out to understand and to analyze the coupled thermal, hydrological and mechanical phenomena in the engineered barrier system(EBS) of Korean reference disposal system. Using the experimental data obtained from KENTEX, the water saturation processes in bentonite could be analyzed. From the comparison between the model calculation using ABAQUS and the experimental results, the difference of the water content between them in the unsaturating part was large because the drying phenomena due to moisture redistribution by the temperature gradient could not be included in the model. In the saturating part, the difference of the water content between them was decreased gradually and showed to be small in the full saturation. And the time of about 95% saturation could be estimated about 500 days from the model calculation and experimental results. Also it could be known that the moisture redistribution in the unsaturated part could not be affected on the saturation time of bentonite in the repository. Therefore, it is considered that this model could be used to quantitatively predict the water saturation time in bentonite as EBS for the disposal system.

The thermo–hydro–mechanical (T–H–M) behaviors of a clay barrier are of importance from a performance and safety viewpoint of the engineered barrier system (EBS) for a high-level waste (HLW) repository. An engineering-scale test was carried out to investigate the T–H–M behaviors in the buffer of the Korean reference disposal system (KRS). The test started on May 31, 2005 and is still in operation. The experimental data obtained allowed a preliminary and qualitative interpretation of the T–H–M behavior in bentonite blocks. The temperature was higher as it became closer to the heater, while it became lower as it was farther away from the heater. The water content had a higher value in the part close to the hydration surface than that in the heater part. The relative humidity data suggested that a hydration of the bentonite blocks might occur by different drying–wetting processes, depending on their position. The total pressure was continuously increased by the evolution of the saturation front in the bentonite blocks and thereby the swelling pressure. There was also a contribution of the thermal expansion of the bentonite blocks near the heater and the capillary force in the dry bentonite blocks which the water did not reach from the hydration surface.