Engineered Barrier Systems (EBS) are a key element of deep geological repositories (DGR) and play an important role in safely isolating radioactive materials from the ecosystem. In the environment of a DGR, gases can be generated due to several factors, including canister corrosion. If the gas production rate exceeds the diffusion rate, pore pressures may increase, potentially inducing structural deterioration that impairs the function of the buffer material. Therefore, understanding the hydraulic-mechanical behavior of EBS due to gas generation is essential for evaluating the longterm stability of DGR. This study employed X-ray computed tomography (CT) technology to observe cracks created inside the buffer material after laboratory-scale gas injection experiments. After CT scanning, we identified cracks more clearly using an image analysis method based on machine learning techniques, enabling us to examine internal crack patterns caused by gas injection. In the samples observed in this study, no cracks were observed penetrating the entire buffer block, and it was confirmed that most cracks were created through the radial surface of the block. This is similar to the results observed in the LASGIT field experiment in which the paths of the gas migration were observed through the interface between the container and the buffer material. This study confirmed the applicability of high-resolution X-ray CT imaging and image analysis techniques for qualitative analysis of internal crack patterns and cracks generated by gas breakthrough phenomena. This is expected to be used as basic data and crack analysis techniques in future research to understand gas migration in the buffer material.

Gases such as hydrogen can generate from the disposal canister in high-level radioactive waste disposal systems owing to the corrosion of cooper container in anoxic conditions. The gas can be accumulated in the voids of bentonite buffer around the disposal canister if gas generation rates become larger than the gas diffusion rate of bentonite buffer with the low-permeability. Continuous gas accumulations result in the increase in gas pressure, causing sudden dilation flow of gases with the gas pressure exceeding the gas breakthrough pressure. Given that the gas dilation flow can cause radionuclide leakage out of the engineered barrier system, it is necessary to consider possible damages affected by the radionuclide leakage and to properly understand the complicated behaviors of gas flow in the bentonite buffer with low permeability. In this study, the coupled hydro-mechanical model combined with the damage model that considers two-phase fluid flow and changes in hydraulic properties affected by mechanical deformations is applied to numerical simulations of 1-D gas injection test on saturated bentonite samples (refer to DECOVALEX-2019 Task A Stage 1A). To simulate the mechanical behavior of microcracks which occur due to the dilation flow caused by increase in gas pressure, a concept of elastic damage constitutive law is considered in the coupled hydro-mechanical model. When the TOUGH-FLAC coupling-based model proposed in this study is applied, changes in hydraulic properties affected by mechanical deformations combined with the mechanical damage are appropriately considered, and changes in gas injection pressure, pore pressures at radial filters and outlet, and stress recorded during the gas injection test are accurately simulated.

The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and CO2 gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and specific length at 40 and 50% moisture contents with CO2 gas injection increased while piece density decreased. On the contrary, the expansion ratio and specific length of extruded SPI at 60% moisture content with CO₂ gas injection decreased while piece density increased. Extruded SPI with CO2 gas injection had small cell size and higher amount of cell than extruded SPI without CO2 gas injection. The water holding capacity and nitrogen solubility index increased with CO2 gas injection increased while the integrity index and the springiness and cohesiveness decreased. In conclusion, extruded SPI with CO2 gas injection showed better expansion properties and cell formation than extruded SPI without CO2 gas injection.

The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and CO2 gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and the specific length increased, but piece density decreased with the increase in CO2 gas injection from 0 to 800 mL/ min at both 40 and 50% moisture contents. On the contrary, the expansion ratio and the specific length decreased, but piece density increased with the increase in CO2 gas injection from 0 to 800 mL/min at 60% moisture content. Extruded SPI with CO2 gas injection at 800 mL/min had small cell size and higher amount of cell than extruded SPI without CO2 gas injection. The water holding capacity and nitrogen solubility index increased, and the integrity index and the texture decreased with the increase in CO2 gas injection from 0 to 800 mL/min. In conclusion, extruded SPI with the CO2 gas injection at 800 mL/min showed better expansion properties and cell formation than extruded SPI without the CO2 gas injection.

The objective of this study was to determine the effect of moisture contents (40, 50, 60%) and CO2 gas injection (0 and 800 mL/min) on physicochemical properties of extruded soy protein isolate (SPI). The expansion ratio and the specific length increased, but piece density decreased with the increase in CO2 gas injection from 0 to 800 mL/ min at both 40 and 50% moisture contents. On the contrary, the expansion ratio and the specific length decreased, but piece density increased with the increase in CO2 gas injection from 0 to 800 mL/min at 60% moisture content. Extruded SPI with CO2 gas injection at 800 mL/min had small cell size and higher amount of cell than extruded SPI without CO2 gas injection. The water holding capacity and nitrogen solubility index increased, and the integrity index and the texture decreased with the increase in CO2 gas injection from 0 to 800 mL/min. In conclusion, extruded SPI with the CO2 gas injection at 800 mL/min showed better expansion properties and cell formation than extruded SPI without the CO2 gas injection.

전세계적으로 화석연료의 과다한 사용으로 인한 지구온난화 및 고유가 시대에 직면하고 있다. 이에 따라 세계 각국은 신재생에너지 개발 및 적용을 통해 지구온난화문제와 에너지 자립화를 위한 노력을 기울이고 있다. 바이오 메탄은 실현 가능성이 가장 높은 분야의 하나로, 대부분 음식물 쓰레기 처리장, 매립지, 축산폐수 및 하폐수 처리시설에서 혐기성소화공정을 통해 얻어진다. 발생된 메탄가스를 정제하여 고순도로 이용하는 기술은 설치비가 저렴하고 운전이 편리하여 유럽을 비롯한 전세계에서 상용화되어 왔으며 IEA 자료에 의하면 고순도화 플랜트의 설치사례가 2011년 이후 급격히 증가되었다. 본 발표에서는 전세계 정제플랜트의 시장규모, 국내외 기술현황, 화학연구원에서 개발중인 분리막 정제기술의 연구를 소개하고자 한다.

The smoke emission of biodiesel fuel was reduced remarkably in comparison with diesel fuel, that is, it was reduced approximately 36% at 2000rpm, full load condition. And, power, torque and brake specific energy consumption showed no significant differences. However, NOx emission of biodiesel fuel was increased compared with commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) to reduce the NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel(20vol-%) and cooled EGR method(10∼15%).

The OGS model is configured and used for simulation of the LASGIT project. The modeling conditions and the simulation results from the previous work by Walsh and Calder (2009) are analyzed to see if the simulation configuration is done correctly and to apply for the LASGIT project. Except for the unrealistic modeling conditions used previously, the simulation results successfully demonstrated helium propagation that is typical for the two-phase flow. The results indicated that the relations of capillary pressure and the relative permeability against water saturation used previously should be updated. An elaborated simulation with more realistic parameters should be used to improve the weak points of preliminary work.

Gas surface treatment is considered to be effective for titanium because of its high reactivity. In this study, we investigated the gas nitriding mechanism in titanium sintered parts produced by metal powder injection molding (MIM) process. The microstructure and nitrogen content of sintered MIM parts were greatly affected by nitriding conditions. Nitriding process strongly depended on the specimen size, for example, the size of micro metal injection molding (μ-MIM) product is so small and the specific surface is so large that the mechanical and functional properties can be modified by nitriding.

사염화우라늄을 제조하기 위한 가장 효율적인 반응계는 이산화우라늄, 염소가스와 탄소분말이다. 여러 가지 실험변수 가운데 이산화우라늄의 염소화반응에 사용된 염소가스 주입량과 탄소의 양이 사염화우라늄 제조에 미치는 영향에 관하여 연구하였다. 각각의 실험변수들에 대한 전화율과 휘발률 계산을 통해 효율적인 반응을 위한 적정 염소가스 주입량과 탄소의 양을 구하였고, 이산화우라늄의 증가함에 따라 직접접촉에 의한 기체-고체반응에서는 전화율과 휘발률은 증가했으나 이후 과량을 첨가함에 따라 감소하였고, 용융염내의 기체-액체반응에서는 전화율의 미미한 증가와 휘발률의 감소를 확인하였가. 염소주입량이 증가함에 따라 전화율과 휘발률이 증가했으며, 과량의 염소가수 주입시 고이온가 염화물의 생성량이 증가하였다.

Landfill gas (LFG) has received considerable attention to produce a renewable energy source from waste because LFG contains about 45 ~ 55% methane. In order to improve LFG, the concept of bioreactor landfill is applied to Sudokown Landfill site. In landfill field test, the research area 3A (300 m × 300 m) and reference area 2A (300 m × 300) are prepared to compare the effect of leachate recirculation. Using injection wells, leachate is injected into the research area in the 2nd Landfill site and the distribution of moisture content in the research area is homogeneously saturated by the injected leachate. Leachate characteristics such as Alkalinity, BOD, COD, TKN, and TOC are increased with the input of the injected leachate because wastes are decomposed by the injected leachate but pH of leachate is almost not affected by the injected leachate. The production of LFG in the reseach area is improved by about 40% comparing with that in the reference area and the content of CH4 in LFG is consistently higher than 50%. Hence, it can be summarized that the production and the quality of LFG can be improved by the injection of leachate into landfill site.