In this study, defects generated in the YSZ coating layer of the IN738LC turbine blade are investigated using an optical microscope and SEM/EDS. The blade YSZ coating layer is composed of a Y-Zr component top coat layer and a Co component bond coat layer. A large amount of Cr/Ni component that diffused from the base is also measured in the bond coat. The blade hot corrosion is concentrated on the surface of the concave part, accompanied by separation of the coating layer due to the concentration of combustion gas collisions here. In the top coating layer of the blade, cracks occur in the vertical and horizontal directions, along with pits in the top coating layer. Combustion gas components such as Na and S are contained inside the pits and cracks, so it is considered that the pits/cracks are caused by the corrosion of the combustion gases. Also, a thermally grown oxide (TGO) layer of several μm thick composed of Al oxide is observed between the top coat and the bond coat, and a similar inner TGO with a thickness of several μm is also observed between the bond coat and the matrix. A PFZ (precipitate free zone) deficient in γ' (Ni3Al) forms as a band around the TGO, in which the Al component is integrated. Although TGO can resist high temperature corrosion of the top coat, it should also be considered that if its shape is irregular and contains pore defects, it may degrade the blade high temperature creep properties. Compositional and microstructural analysis results for hightemperature corrosion and TGO defects in the blade coating layer used at high temperatures are expected to be applied to sound YSZ coating and blade design technology.

Microbiologically Influenced Corrosion (MIC) occurring in underground buried pipes of API 5L X65 steel was investigated. MIC is a corrosion phenomenon caused by microorganisms in soil; it affects steel materials in wet atmosphere. The microstructure and mechanical properties resulting from MIC were analyzed by OM, SEM/EDS, and mapping. Corrosion of pipe cross section was composed of ① surface film, ② iron oxide, and ③ surface/internal microbial corrosive by-product similar to surface corrosion pattern. The surface film is an area where concentrations of C/O components are on average 65 %/ 16 %; the main components of Fe Oxide were measured and found to be 48Fe-42O. The MIC area is divided into surface and inner areas, where high concentrations of N of 6 %/5 % are detected, respectively, in addition to the C/O component. The high concentration of C/O components observed on pipe surfaces and cross sections is considered to be MIC due to the various bacteria present. It is assumed that this is related to the heat-shrinkable sheet, which is a corrosion-resistant coating layer that becomes the MIC by-product component. The MIC generated on the pipe surface and cross section is inferred to have a high concentration of N components. High concentrations of N components occur frequently on surface and inner regions; these regions were investigated and Na/Mg/Ca basic substances were found to have accumulated as well. Therefore, it is presumed that the corrosion of buried pipes is due to the MIC of the NRB (nitrate reducing bacteria) reaction in the soil.

The purpose of this study is to present the future policy direction in terms of sustainability through the diagnosis of trends related to the domestic and foreign agricultural development cooperation between Korea and Myanmar, considering the internal and external situation of Myanmar, such as military coup and Coronavirus Disease 2019 (COVID-19). Agriculture accounts for the third largest share of Myanmar's entire industry, after the service industry and manufacturing industry. In fact, agriculture accounts for more than 22% of the Gross Domestic Product (GDP) in Myanmar, and the agriculture industry employs 68% of the total labor population, making agriculture one of the national infrastructure industries representing Myanmar. However, sluggish production structure and sluggish agricultural modernization have hindered the competitiveness of Myanmar's agricultural development projects. In this study, the following directions were derived based on the existing policy trends and current status from the perspective of cooperation in agricultural development projects between Korea and Myanmar: First, it is necessary to take into account the long-term policies and strategies that fully consider Myanmar's internal and external conditions. Second, technical discussions following the Fourth Industrial Revolution need to be performed not only at the government level, but also at the private level. Finally, the impact of political instability in Myanmar requires continuous diplomatic monitoring, research on agricultural technology transfer, and establishment of cooperative governance with universities.

This paper analyzed the correlation between injection molding factors through correlation analysis. In addition, the decision-tree model, which is a white box model with excellent explanatory power, was used to obtain optimal molding conditions that satisfy multiple constraint conditions. First, 243 data to be used in the experiment were created through a full factorial design. Second, a correlation analysis was conducted to understand the correlation. Third, to verify the decision-tree model, the prediction performance was evaluated using RMSE. As a result, good prediction performance was confirmed. A decision-tree experiment analysis was conducted. As a result of the progress, the same results as the correlation analysis were derived. Based on the previous analysis results, optimal molding conditions were applied to CAE. As a result, the amount of deformation in the multi-cavity could be improved by about 1.1% and 2.72% while satisfying the constraint.

In severe acute pancreatitis, accompanied by local complications such as acute peripancreatic fluid collection, pancreatic pseudocyst, acute necrotic collection and walled-off necrosis, the mortality rate is as high as 12-25%. In many cases, interventional procedure or surgical treatment are required at an appropriate time. Conservative treatment is considered for acute peripancreatic fluid collection. Endoscopic drainage could be considered preferentially for the treatment of pancreatic pseudocysts with clinical symptoms or complications. In the case of necrotizing pancreatitis, conservative treatment is preferred, but therapeutic intervention should be considered if infectious pancreatic necrosis with clinical deterioration is suspected. For therapeutic intervention, it is recommended to proceed with a step-up approach in which drainage is first performed and, if necessary, necrosectomy is performed. The optimal timing of intervention is considered 4 weeks after the onset of pancreatitis when necrosis become walled-off, but early drainage within 4 weeks can be considered depending on the patient's condition. This guideline provides an overview of current treatment strategies for local complications of acute pancreatitis.

환경시설물, 댐과 같은 유체를 저장하는 시설물을 대상으로 엄밀하게 지진 거동을 평가하기 위해서는 유체-구조물 상호작용을 고 려한 해석이 필요하다. 특히, 댐-호소 계와 같이 상류 방향으로 무한 영역을 가지는 경우에는 이를 적절히 고려해야 할 필요가 있다. 본 연구에서는 댐-호소 계와 같은 반무한 유체 영역을 갖는 시스템을 대상으로 무한 영역의 파전파 해석 및 유체-구조물 상호작용 해석을 위한 실용적인 수치 모형을 제시하였다. 시간영역에 적용가능한 방법으로 정확하면서도 경계적인 해석이 가능하다. 무한 유체 영역 에 대해서는 일반 acoustic finite element 대신 작은 개수의 mid-point integrated acoustic finite element를 적용하고 최종 경계에는 점성 경계를 부과한다. 제안하는 방법의 유효성과 정확성을 검증하기 위해 강체 댐체를 가정한 반무한 호소계를 대상으로 적용하는 요소 의 개수, 모델링 영역 크기 등을 매개변수로 해석해와 비교·검증하였다. 제안된 방법을 적용하여 댐-호소 계의 유체-구조물 상호작용 을 부가질량을 사용하는 경우와 비교하였다.

Yogurt is mostly consumed dairy food and considered as a nutritious food because of its probiotics such as lactic acid bacteria (LAB). LABs are known to possess antioxidant, anticarcinogenic and antimicrobial effects. Corni fructus has healthy and pharmacological effects such as the inhibition of apidogenesis and angiopoiesis. Thus, the purpose of this study was to evaluate quality characteristics and antioxidant activity of yogurt supplemented with water and ethanol extracts of corni fructus. Yogurt was manufactured with addition of 0.1%-0.2% (w/v) water or ethanol corni fructus extracts, respectively. For quality characteristics, pH, chromaticity, viscosity and syneresis were determined during refrigeration storage (1, 7, 14, and 21 day). For antioxidant activities, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activities were examined during storage. The pH showed no significant difference between groups but showed decreasing pattern for all groups during storage period. In chromaticity, redness increased, and lightness decreased as the amount of corni furctus extracts increases. Yogurt with corni furctus ethanol extracts showed more color changes than yogurt with corni furctus water extracts. Viscosity increased in corni furctus extract added groups, compared to control. Syneresis was approximately 2-fold higher in corni fructus extract added groups, while there were no significant changes between control and extract added groups. Both DPPH and ABTS radical scavenging activities were significantly higher than control group in corni fructus extract added groups, compared to control. In conclusion, addition of corni fructus extracts in yogurt improved quality characteristics during storage and antioxidant properties.

본 연구에서는 대추 열수추출물에 대한 유산균 발효를 통해 기능성 소재로서의 가능성을 알아보고자 하여 열수추출물에 L. plantarum 을 접종하여 유산균 발효물을 제조하였으며, 열수추출물과 유산균 발효물의 영양성분 및 항산화능을 비교 ․ 분석하였다. 대추 열수추 출물에 접종한 유산균은 초기 12시간 만에 증가하였으며, 이후 72 시간까지 큰 증감없이 그 수를 유지하여 대추 열수추출물은 유산균 의 생육에 큰 영향을 미치지 않았다. 열수추출물과 유산균 발효물 의 당도, pH 및 총산도를 측정한 결과, 당도는 유산균 발효 여부와 관계없이 열수추출횟수가 증가할수록 높아졌으며, pH는 유산균 발 효 이후 현저히 감소하였고, 총산도는 2차 열수추출물의 발효물에 서만 유의적으로 증가하였다. 2차 열수추출물의 유산균 발효 여부 에 따른 일반영양성분 분석 결과, 모든 성분에서 유의적 차이를 보 이지 않았으며, DPPH 및 ABTS free radical 소거활성능은 유산 균 발효 여부에 관계없이 열수 추출횟수에 비례하여 증가하여 2차 열수추출물과 그의 발효물에서 가장 높은 결과를 나타내었다. 총폴 리페놀 함량 또한 유산균 발효여부에 관계없이 1차 열수추출물에 서 가장 높은 값이 관찰되었다. 본 연구를 통해 대추 열수추출물은 유산균 생육에 전혀 영향을 미치지 않아 유산균 발효물 제조 가능 성을 확인했으며, 또한 항산화능과 총폴리페놀 함량은 열수추출횟 수에 의해 영향을 받는다는 사실을 알 수 있었다. 하지만, 열수추출 물과 유산균 발효물 사이에 일반영양성분 및 항산화능에 큰 차이 는 없었으며, 이는 L. plantarum 단일 균주로만 연구를 진행했기 때문으로 여겨진다. 따라서 추후에 다양한 유산균주를 사용하여 대추 열수추출물의 발효를 시도해 항산화능을 비롯한 다양한 기능 성을 증가시킬 수 있는 유산균주를 탐색할 필요가 있을 것으로 사 료된다.

본 연구에서는 낮은 막 저항을 가지는 알칼리 수전해 시스템 적용을 위한 격리막 제조를 위하여 PPS (Polyphenylene sulfide)를 지지체로 사용하고 Polysulfone과 무기물 첨가제를 이용하여 격리막을 제조한 뒤, 지지체의 두께와 다공도에 대한 영향을 분석하였다. 지지체로 사용된 PPS 펠트를 온도(100°C, 150°C, 200°C)와 압력(1톤, 2톤, 3톤, 5톤)의 변수를 두어 압축을 진행 하여 두께를 조절하고자 하였으며, 무기입자로서 친수성이 높고 내알칼리성이 뛰어난 BaTiO3와 ZrO2를 사용하여 polysulfone과 함께 슬러리를 제조하고 압축한 PPS 펠트 위에 캐스팅하여 다공성 격리막을 제조할 수 있었다. 전자주사현미경(SEM)을 통해 압축 조건에 따른 분리막의 모폴로지 변화를 확인하고, 기공도를 계산하였으며, 압축 조건이 증가할수록 두께와 기공도가 감소하는 경향을 확인하였다. 수전해용 격리막으로서 사용이 가능한지를 확인하기 위하여 다양한 특성 평가를 진행하였다. 기계적강도를 측정한 결과 압축 조건(온도와 압력)이 증가할수록 인장강도가 점차 증가하는 경향을 확인하였다. 최종적으로 내알칼리성 테스트 를 통하여 제조한 다공성 격리막이 우수한 내알칼리성을 가지는 것을 확인하였고, I-V 테스트를 통하여 100°C와 150°C 조건에서 압축된 막들이 기존의 압축하지 않은 막보다 낮은 전압을 가지며 성능이 향상되었다는 것을 확인하였다.

The effect of solidification rate on micro-segregation in investment casting of IN738LC superalloy was studied. In Ni-based superalloys, the micro-segregation of solute atoms is formed due to limited diffusion during cast and solidification. The microstructure of cast Ni-based superalloys is largely divided into dendrite core of initial solidification and interdendrite of final solidification. In particular, mosaic shaped eutectic γ/γ’ and carbides are formed in the interdendrite of the final solidification region in some cases. The micro-segregation phenomena formed in regions of dendrite core and interdendrite including eutectic γ/γ’ and carbides were analyzed using OM, SEM/EDS and micro Vickers hardness. As a result of analysis, the lack of (Cr, W) and the accumulation of Ti were measured in the eutectic γ/γ’, and the accumulation of (Cr, Mo) and the lack of Ti were measured in the interdendrite between dendrite and eutectic. Carbides formed in interdendritic region were composed of (Ti, W, Mo, C). The segregation applied to each microstructure is mainly due to the formation of γ’ with Ni3(Al,Ti) composition. The Ni accumulation accompanied by Cr depletion, and the Ti accumulated in the eutectic region as a γ’ forming elements. The Mo tends to diffuse out from the dendrite core to the interdendrite, and the W diffuse out from the interdendrite to the dendrite core. Therefore, the accumulation of Mo in the interdendrite and the deficiency of W occur in the eutectic region located in the interdendrite. Heat treatment makes the degree of the micro-segregation decrease due to the diffusion during solid solution. This study could be applied to the heat treatment technology for the micro-segregation control in cast Ni-based superalloys.

In this study, we used a numerical analysis program to study the molding conditions that affect the flow rate at the time of injection, using a spiral mold, which is mainly used for the evaluation of the flow rate of plastic resin. The mold temperature, melt temperature, and flow rate are composed of experimental factors. The three plastic forming factors were divided into five to six levels each. Since then, changes in the flow rate temperature were analyzed as the level of each forming factor increased. Experiments showed that all three forming factors increased the filling length of the spiral mold and the temperature of the flow front by a total of 34.53°C, melt temperatures increased the temperature of the flow front by a total of 34.53°C, the temperature increased by the flow rate was 23.5°C, and the temperature increased by the mold temperature was 1.99°C. It was shown that the melt temperature was the largest, followed by the flow rate and mold temperature. It was also possible to check the effect of plastic forming factors on the speed of the flow front.