• 대한기계학회논문집A
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• 제32권8호
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• pp.660-667
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• 2008

During the last two decades, lots of efforts have been devoted to resolve thermal stratification phenomenon and primary water environment issues. While several effective methods were proposed especially in related to thermally stratified flow analyses and corrosive material resistance experiments, however, lack of details on specific stress and fatigue evaluation make it difficult to quantify structural behaviors. In the present work, effects of the thermal stratification and primary water are numerically examined from a structural integrity point of view. First, a representative austenitic nuclear piping is selected and its stress components at critical locations are calculated in use of four stratified temperature inputs and eight transient conditions. Subsequently, both metal and environmental fatigue usage factors of the piping are determined by manipulating the stress components in accordance with NUREG/CR-5704 as well as ASME B&PV Codes. Key findings from the fatigue evaluation with applicability of pipe and three-dimensional solid finite elements are fully discussed and a recommendation for realistic evaluation is suggested.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.381-385
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• 2005

Characterization of particle behavior is becoming more important in performance evaluation of water treatment system as well as in operation of the system because conventional parameter, turbidity has lack of explaining ability on small sized microorganisms such like Cryptosporidium etc. Accordingly, particle counter has been introduced in evaluation and operation of the treatment system. However researches on the relationship between turbidity, particle count and/or different sand/anthracite sizes have not been concurrent. Therefore in this study, the relationship was investigated to improve performance evaluation of sand filter so as to help choosing sand/anthracite effective size as a design parameter of water treatment facility. According to the results, too small or too large effective size media filter reached to turbidity limit(0.1 NTU)earlier. However, because shallow sand layer may cause early breakthrough, the depth of sand layer should be provided enough in order to compromise water quality and productivity.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1438-1445
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• 2008

The purpose of this study is to evaluate the fundamental frequency of the dam by the various methods using real microearthquake records which were measured on 'H' dam site and to compare each results. In this study, the fundamental frequency was evaluated by the frequency analysis of the microearthquake records which were measured on the dam crest, by the evaluation of acceleration amplification ratio between the foundation and the crest of dam, and by the evaluation of acceleration response spectrum ratio between the foundation and the crest of dam, respectively. Among these methods, it was found that the method by the evaluation of acceleration response spectrum ratio between the foundation and the crest of dam was the most effective method. But, if the simple engineering judgement can be considered, it was thought that the all three methods could reasonably evaluate the fundamental frequency of the dam.

• 한국지열·수열에너지학회논문집
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• 제13권3호
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• pp.16-22
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• 2017

It has become important for unutilized energy to be used for air conditioning of building. Economic evaluation on energy system by using treated sewage water as heat source, which is one of unutilized energy, was performed. The floor area of the subject building and the distance between heat source equipment and sewage treatment plant was assumed $30,000m^2$ and 200m. Absorption chiller-heater system was used for comparing to the energy efficient system, and payback period method was applied to carry out economic evaluation. Although the operating cost of this system is reduced compared to general heat source system, the ratio is not meaningful compared to the initial investment cost increase, and payback period was calculated to be about 36.1 years. However, when calculated based on the 2014 rate of electricity and city gas, it will be greatly reduced to 3.1 years. International commodity prices are constantly changing, and therefore national policy on the spread of unutilized energy should be maintained.

• 한국수자원학회논문집
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• 제46권7호
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• pp.745-754
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• 2013

수돗물의 생산 및 공급과정에 소요되는 에너지에 대한 체계적인 분석 및 평가는 최근의 전력부족 사태와 온실가스 감축의 필요성에 따라 관심이 증가되고 있다. 본 연구에서는 기존의 연구에서 제시한 결과에 대한 검토를 통하여 실용적으로 적용 가능한 에너지 분석기법 및 평가기법을 제시하였다. 본 연구에서는 EPANET2의 수리해석 결과를 이용하여 에너지를 평가할 수 있는 모형을 MATLAB 플랫폼 기반 하에서 개발하였다. 제안된 기법은 상수관망의 입지, 관로의 상태, 누수정도 등에 따라 시설물이 내재적으로 가지는 에너지관리 효율과 운영 효율을 분리하여 평가할 수 있는 성능평가 지표를 제시하였다. 개발모형은 시험관망과 실제관망에 대하여 각각의 상수관망 구성요소에 대한 에너지 분석 및 평가결과를 제시함으로써 적용성 평가를 실시하였다. 본 연구의 결과는 상수관망 에너지관리의 최적화를 도모함으로써 피크시간대의 전력수요 관리 및 에너지 절감형 상수도 시스템 계획 및 운영에 활용될 수 있을 것으로 기대된다.

• 환경영향평가
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• 제28권3호
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• pp.263-274
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• 2019

본 연구의 목적은 도시하천의 생태복원사업 이후 친수시설의 모니터링 방법을 연구하고 그 결과를 바탕으로 관리구역의 설정과 유지관리방안을 제시하는데 있다. 이를 위해 친수시설의 유지관리모니터링 항목을 '이용공간 시설물', '산책로 및 자전거도로', '접근로', '안내판'으로 구분하였다. 각 친수시설의 평가는 '관리상태', '안전성', '이용정도'를 기준으로, '양호', '보통', '불량' 등급으로 구분하였다. 전주천을 대상으로 500m간격의 총 15개 구간을 조사 및 평가하여 친수시설마다 '우선관리', '일반관리', '유지/제거', '제거' 여부를 결정하고 이를 바탕으로 구간별 관리구역설정과 유지관리방안을 제시하였다. 전주천에서 '우선관리'가 필요한 시설이 5~9개로 나타난 J2, J3, J4, J9 구간은 '집중관리구역', '우선관리'가 필요한 시설이 1~3개로 나타난 J5, J6, J7, J8, J11, J14 구간은 '정기관리구역'으로 설정되었다. '우선관리'할 시설이 없는 J1, J10, J12, J13, J15구간은 '최소관리구역'으로 설정되었다. 본 연구의 모니터링 및 평가, 유지관리구역 설정과정은 향후 거버넌스가 참여하여 하천 친수시설물의 체계적인 유지관리계획을 마련하는데 적용될 수 있다.

• 한국가스학회지
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• 제22권6호
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• pp.65-75
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• 2018

풍력에너지는 낮에 비해 야간에 많은 잉여전력을 발생시키기 때문에 야간에 생산되는 전력은 버려지고 있는데, 이 문제를 해결하기 위해 풍력 등 재생에너지를 연계한 수전해 하이브리드 시스템 개발이 활발히 이루어지고 있다. 본 연구에서는 하이브리드 시스템 안전성 향상을 위해 국내 외 수전해 시스템 기준의 평가항목을 분석하였고, 평가 항목을 토대로 수전해 시스템의 안전성능 시험항목을 도출하였다. $5Nm^3/hr$급 수전해 시스템의 안전성능 평가를 위하여 시험항목 중 효율측정시험, 수소발생압력시험, 수소 순도시험을 평가하였다. 그 결과 수소발생량은 $5.10Nm^3/hr$, 스택효율은 $4.97kWh/Nm^3$로 산출되었고, 이때 발생한 수소의 순도는 99.993%로 국제기준 ISO 14687, SAE J2719에 명시된 순도보다 높은 순도의 수소를 생산하였음을 확인할 수 있었다. 본 연구 결과는 향후 수전해 시스템의 구축과 안전성능을 평가에 도움이 될 것이라고 기대한다.

• 한국수소및신에너지학회논문집
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• 제19권2호
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• pp.145-155
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• 2008

This paper deals with an economic evaluation of hydrogen production by fermentation. We evaluate the economic feasibility of domestic hydrogen production by fermentation utilizing glucose and waste water sludge in terms of hydrogen production prices. In addition, we make some sensitivity analysis of hydrogen prices by changing the values of input factors such as the price of glucose, the capital cost of the hydrogen production system, and the hydrogen production yields. The estimated hydrogen prices of the two-step dark-light hydrogen production by fermentation utilizing glucose was $5,347won/kgH_2$, and the single-step hydrogen production by anaerobic fermentation utilizing waste water sludge was $4,255won/kgH_2$, respectively. It is expected that the hydrogen production price by anaerobic fermentation can be reduced if we produce methane or hydrogen utilizing by-products such as alcohols and organic acids, or the government imposes some legal regulations on the treatment of waste water sludge.

• 한국물환경학회지
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• 제24권2호
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• pp.230-238
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• 2008

This study evaluated the economic aspect of the rainwater harvesting facilities by hydrologically analyzing the inflow, rainwater consumption, rainfall loss, tank storage, and overflow time series to derive the net rainwater consumption and the number of days of rainwater available. This study considers several rainwater harvesting facilities in Seoul National University, Korea Institute of Construction Technology and Daejon World Cup Stadium and the results derived are as follows. (1) Increasing the water consumption decreases the number of days of rainwater available. (2) Due to the climate in Korea, a larger tank storage does not increase the amount and the number of days of water consumption during wet season (June to September), but a little in October. (3) Economic evaluation of the rainwater harvesting facilities considered in this study shows no net benefit (private benefit). (5) Flood reduction effect of rainwater harvesting facilities was estimated very small to be about 1% even in the case that 10% of all the basin is used as the rainwater collecting area.

• 한국식품영양과학회지
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• 제13권4호
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• pp.381-388
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• 1984

The objective of this study was to evaluate the effect of the amount of water and several kinds of sweeteners on the texture such as grain appearance, softness, moistness, chewiness, cohesiveness, gumminess and elasticity of Backsulgi when one manufactures Backsulgi. Different amount of water of 30 ml, 60 ml and 90 ml/350 g of powdered rice and such sweetners as sugar, honey and syrup were employed for the experimental treatments. The evaluation of these results were dependent on statistical data of some scores that were obtained through sensory evaluation and Instron Universal Testing Machine. According to this sensory evaluation, the texture of Backsulgi was more affected by the change of water quantity than that of sweeteners. Judging from the results of Instron Universal Testing Machine, it was found that there were no statistically significant differences in each treatment of the cohesiveness, elasticity and hardness of Backsulgi, but some statistically significant difference was observed in each treatment of the gumminess and chewiness of Backsulgi(p<0.05).