• 융합정보논문지
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• 제9권2호
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• pp.34-42
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• 2019

본 연구에서는 자동제어시스템이 리액터 운전에 미치는 영향을 분석해 보았다. Propylene 리액터 공정은 복잡하게 구성되어 일반적으로 효율이 낮고, 생산성이 떨어지는 문제로 인해 경제적 손실이 많다. 본 연구에서는 장애요인을 보완하여 운전효율을 높이고, 생산성을 향상시키는 목적으로 연구 모델을 제시하였다. 기존 공정의 구성을 분석하여 하드웨어 시스템 및 소프트웨어 시스템을 독창성 있는 모델로 보완하였다. 설비의 구성을 연간 60 만톤/Year 프로플린을 생산하는 리액터 8기를 기준으로 적용하였다. 연구 모델 적용결과 운전 효율이 높아졌고, 안정성 91%과 더불어 생산량이 90~95% 으로 증가하였다. 향후 연구는 생산성 100% 향상을 위한 연구모델을 제시할 예정이다. 추가적으로 프로플린 부산물인 수소 생산공정인 PSA 시스템의 안정성과 생산성 향상 방안에 대해 연구하고자 한다.

• 한국환경보건학회지
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• 제45권1호
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• pp.42-53
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• 2019

Objectives: The Yongpung reservoir in Korea is a crucial facility that supplies water to farms in its surrounding $2km^2$ area. However, its water quality is not suited to the needs of current residents who wish for the availability of environmentally friendly agricultural products and desire to use the waterfront area. The aim of this research was to evaluate the reservoir's fish and benthic macroinvertebrate distributions and determine its water quality and the heavy metal content in its sediment. This basic data can be used to establish environmentally protective plans for the Yongpung reservoir. Methods: Six sites were selected for analysis in this investigation. Three points (YP-1, YP-2, and YP-3) were evaluated for water quality and metal content in sediments; they were located upstream, midstream, and downstream of the reservoir. Samplings of the fish and benthic macroinvertebrate populations were performed at three other sites: St. 1, St. 2, and St. 3. Results: Based on chemical oxygen demand (COD) and total nitrogen (T-N) data, the quality of the Yongpung reservoir water corresponds to Class VI (very poor) according to Korea's lake environmental standards. The lead levels measured in the sediment at the midstream and downstream points of the reservoir were 76.7 and 72.7 mg/kg, respectively, while 8 orders, 15 families, and 16 species of benthic macroinvertebrates were identified in the reservoir. The ecological score of the benthic macroinvertebrate community (ESB) was between 8 and 23, denoting poor to very poor environmental conditions. Further, 4 families and 7 species of fish were identified in the reservoir, with Cyprinidae accounting for 94.3% of all observed freshwater fish. Conclusion: Based on these findings, we conclude that management plans, including the removal of lead from the sediment, are necessary to improve the quality of the agricultural water in this reservoir. The T. japonica, which cover almost 30% of the water area, must also be removed.

• 산업융합연구
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• 제14권2호
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• pp.33-38
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• 2016

The Korean shipbuilding industry, which started in the 1970s with the advance of three shipbuilding companies, has been ranked as the world's largest and most successful model of the heavy and heavy chemical industry in the world since the 1990s, and has become a driving force for Korea's economic growth for several decades, including job creation and trade surplus. The domestic shipbuilding industry has won a lot of orders in favorable market environment, expanded facilities and manpower, built many ships and delivered them to shipowners, earning a lot of foreign currency and creating a 'successful myth.' However, when the global economic crisis broke out in 2008, shipbuilding in Chosun was stagnant and shipbuilding orders sharply decreased.As the facility and manpower increased in the boom period, the economy and the facilities become overcrowded as a result of the crisis, signs of a crisis in 2013 begin to appear. In 2015, three major Korean shipbuilders lost more than 6 trillion won in operating losses. Now, Korea's shipbuilding industry is facing a crisis such as massive insolvency and restructuring. Would not it have been possible to prevent the loss and restructuring of a trillion won if we recognized the recession of the global economy and understood the appropriate timing of technological innovation and prepared countermeasures against the crisis? Therefore, we analyze trends and trends of global shipbuilding industry such as Europe, China, and Japan in the competition structure of the shipbuilding industry and identify the problems of our shipbuilding industry and suggest suggestions.

• 급식외식위생학회지
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• 제2권2호
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• pp.103-110
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• 2021

This study was conducted to compare and evaluate the difference in washing and disinfection when the Hazard Analysis and Critical Control Point (HACCP) protocol was applied to foodservice operations. The results of the survey were as follows: Among the 116 foodservice operations surveyed, 67.2% were HACCP-compliant and 32.8% were not HACCP-compliant. Also, 62.9% served meals once daily, and 79.3% conducted food safety education once a month. Compared to HACCP non-compliant foodservice operations, the disinfection performance of HACCP-compliant operations was significantly better concerning worktables (p<0.001), food inspection tables (p<0.001), preparation tables for distribution (p<0.01), serving tables (p<0.01), overflow and trenches(p<0.05), sinks (p<0.05), and insect attracting lamps (p<0.01). Similarly, the disinfection performance of HACCP-compliant foodservice operations was significantly better for 18 cooking utensils and personal tools such as food slicers (p<0.001), multiple cooking machines (p<0.05), tray carts (p<0.001), stainless steel tools (p<0.001), rubber gloves (p<0.05). Worktables (45.1%), serving tables (29.6%), sinks (37.0%), and scales (21.6%) were most often disinfected 'at the end of each task', while food inspection tables (36.5%), food preparation tables for distribution (31.2%), dish machines (34.2%), overflow and trenches (25.7%), and floors (25.8%) were most often disinfected 'once a day'. All cooking utensils were most often disinfected 'at the end of each task'. 'Chemical disinfection' was most frequently used in all foodservice facilities. To improve the food safety management of foodservice operations, it is necessary to apply the HACCP protocol and comply with the washing and disinfection manual.

• Animal Bioscience
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• 제35권2호
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• pp.308-316
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• 2022

Objective: This study was conducted to determine reduction of various odorous materials from a swine farm equipped with a continuous pit recirculation system (CPRS) with aerobically treated liquid manure. Methods: The CPRS is used in swine farms in South Korea, primarily to improve air quality in pig houses. In this study, CPRS consists of a manure aerobic treatment system and a fit recirculation system; the solid fraction is separated and composted, whereas the aerobically treated liquid fraction (290.0%±21.0% per day of total stored swine slurry) is continuously returned to the pit. Four confinement pig barns in three piggery farms were used; two were equipped with CPRS and the other two operated a slurry pit under the slatted floor. Results: All chemical contents of slurry pit manure in the control were greater than those of slurry pit manure in the CRPS treatment (p<0.05). Electrical conductivity and pH contents did not differ among treatments. The biological oxygen demand of the slurry pit treatment was greater than that of the other treatments (p<0.05). Total nitrogen, total phosphorus, and ammonia nitrogen contents of the slurry pit treatment were greater than those of other treatments (p<0.05). Odor intensity of the CPRS treatment was lower than that of the control at indoor, exhaust, and outside sampling points (p<0.05). The temperature and carbon dioxide of the CPRS treatment in the pig barn was significantly lower than those of control (p<0.05). All measured odorous material contents of the CPRS group were significantly lower than those of the control group (p<0.05). Conclusion: The CPRS application in pig farms is considered a good option as it continuously reduces the organic load of animal manure and lowers the average odorant concentration below the threshold of detecting odorous materials.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2077-2083
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• 2022

In the unlikely event of core disruptive accident in sodium cooled fast reactors, the reactor containment building would be bottled up with sodium and fission product aerosols. The behavior of these aerosols is crucial to estimate the in-containment source term as a part of nuclear reactor safety analysis. In this work, the evolution of sodium aerosol characteristics (mass concentration and size) is simulated using HAARM-S code. The code is based on the method of moments to solve the integro-differential equation. The code is updated to FORTRAN-77 and run in Microsoft FORTRAN PowerStation 4.0 (on Desktop). The sodium aerosol characteristics simulated by HAARM-S code are compared with the measured values at Aerosol Test Facility. The maximum deviation between measured and simulated mass concentrations is 30% at initial period (up to 60 min) and around 50% in the later period. In addition, the influence of humidity on aerosol size growth for two different aerosol mass concentrations is studied. The measured and simulated growth factors of aerosol size (ratio of saturated size to initial size) are found to be matched at reasonable extent. Since sodium is highly reactive with atmospheric constituents, the aerosol growth factor depends on the hygroscopic growth, chemical transformation and density variations besides coagulation. Further, there is a scope for the improvement of the code to estimate the aerosol dynamics in confined environment.

• Advances in aircraft and spacecraft science
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• 제9권3호
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• pp.195-215
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• 2022

The increasing interest in CubeSat platforms ant their capability of enlarging the frontier of possible missions impose technology improvements. Miniaturized electrical propulsion (EP) systems enable new mission for multi-unit CubeSats (6U+). While electric propulsion systems have achieved important level of knowledge at equipment level, the investigation of the mutual impact between EP system and CubeSat technology at system level can provide a decisive improvement for both the technologies. The interaction between CubeSat and EP system should be assessed in terms of electromagnetic emissions (both radiated and conducted), thermal gradients, high electrical power management, surface chemical deposition, and quick and reliable data exchanges. This paper shows how a versatile CubeSat Test Platform (CTP), together with standardized procedures and specialized facilities enable the acquisition fundamental and unprecedented information. Measurements can be taken both by specific ground support equipment placed inside the vacuum facility and by dedicated sensors and subsystems installed on the CTP, providing a completely new set of data never obtained before. CTP is constituted of a 6U primary structure hosting the EP system, representative CubeSat avionics and batteries. For the first test campaign, CTP hosts the ambipolar plasma propulsion system, called Regulus and developed by T4I. After the integration and the functional test in laboratory environment, CTP + Regulus performed a Test campaign in relevant environment in the vacuum chamber at CISAS, University of Padua. This paper is focused on the test campaign description and the main results achieved at different power levels for different duration of the firings.

• 한국산업융합학회 논문집
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• 제26권4_2호
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• pp.705-713
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• 2023

The phenomenon of abnormal climate conditions resulting from greenhouse gas-induced global warming is increasingly prevalent. To address this challenge, global initiatives are underway to adopt environmentally friendly, zero-emission fuels. In this study, we investigate the hydrogen embrittlement characteristics of materials used for eco-friendly hydrogen storage systems. The effects of hydrogen embrittlement on austenitic stainless steels of the FCC series and structural steel of the BCC series were examined. Initially, test samples of three different steel types were prepared in 2t and 3t sizes, and hydrogen was injected into the specimens using an electrochemical method over a 24-hour period. Subsequently, a universal material testing machine (UTM) was employed to monitor changes in mechanical strength and elongation. The FCC series stainless steels exhibited a tendency for elongation to decrease, indicating low sensitivity to hydrogen. In contrast, the mechanical strength and elongation of the BCC series steel changed significantly upon hydrogen charging, posing challenges for prediction. The results of the present study are expected to serve as a fundamental database for analyzing the impact of hydrogen embrittlement on both FCC and BCC series steel materials.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.128-128
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• 2021

Most of the studies about stormwater low impact development technologies used generalized observations without fully understanding the mechanisms affecting the whole performance of the systems from catchment to the facility itself. At present, these LID technologies have been treated as black box due to fluctuating flow and environmental conditions affecting its operation and treatment performance. As such, the implications of microbial community to the overall performance of the tree-box filter were investigated in this study. Summer season was found to be the most suitable season for microorganism growth since more microorganism were found during this season. Least microorganism count was found in spring because of the plant growth during this season since plant penology influences the seasonal dynamics of soil microorganisms. Litterfall during fall season might have affected the microorganism count during winter since, during this season, the compositional variety of soil organic matter changes affecting growth of soil microbial communities. Microbial analyses of sediment samples collected in the system revealed that the most dominant microorganism phylum is Proteobacteria in all the seasons in both inlet and outlet comprising 37% to 47% of the total microorganism count. Proteobacteria was followed by Acidobacteria, Actinobacteria and Chloroflexi which comprises 6% to 20%, 9% to 20% and 2% to 27%, respectively of the total microorganism count for each season. These findings were useful in optimizing the design and performance of tree box filters considering physical, chemical and biological pollutant removal mechanisms.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.837-845
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• 2017

D염색공단의 폴리에스테르 알카리 감량폐수 및 호발폐수가 혼합된 실제 종합염색폐수를 처리하기 위하여 D염색공단의 종합폐수처리장 반송슬러지를 고정한 폐타이어담체를 충전한 재순환 유동상 바이오필터와 소성된 $TiO_2$ 코팅-glass bead를 광촉매담체로 적용한 UV/광촉매반응기를 결합한 재순환 통합시스템을 구축하여 운전하였다. 그 결과로서 재순환 통합시스템의 총 $COD_{cr}$ 제거율과 총 색도 제거율 추이는 각각 약 81% 및 55% 정도를 유지하였다. 이러한 재순환 통합시스템의 총 $COD_{cr}$ 및 총 색도 제거율의 제고효과는 각각 최대 약 7% 및 3%로 평가되었다. 재순환 통합시스템의 유동상 바이오필터 및 광촉매반응공정은 총 제거율에 대한 상대기여도로서 각각 총 $COD_{cr}$ 제거율의 약 94% 및 6%를 처리하고, 총 색도 제거율의 약 86% 및 14%를 처리하였다. 이와 같이 재순환 통합시스템의 광촉매반응공정에서는 총 제거율에 대한 색도 제거율의 상대기여도가 $COD_{cr}$ 제거율의 상대기여도보다 약 2.4배 정도 컸다. 따라서 본 연구의 재순환 통합시스템에서 광촉매반응공정은 $COD_{cr}$ 제거보다 아조결합과 같이 염료에서 색을 나타내는 화학결합을 깨는 역할에 더욱 효율성이 있었다. 또한 본 연구의 재순환 통합시스템에서 각 단위공정들의 $COD_{cr}$ 및 색도 제거율이, 재순환 통합시스템의 총 $COD_{cr}$ 및 색도 제거율에 미치는 영향에 대한 모델식과 대수적 상관관계를 구하고 분석하였다.