• 한국농공학회논문집
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• 제54권1호
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• pp.27-38
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• 2012

This study is to analyse the hydrological behavior of agricultural reservoir using CAT (Catchment hydrologic cycle Assessment Tool). The CAT is a water cycle analysis model in order to quantitatively assess the characteristics of the short/long-term changes in watershed. It supports the effective design of water cycle improvement facilities by supplementing the strengths and weaknesses of existing conceptual parameter-based lumped hydrologic models and physical parameter-based distributed hydrologic models. The CAT especially supports the analysis of runoff processes in paddy fields and reservoirs. To evaluate the impact of agricultural reservoir operation and irrigation water supply on long-term rainfall-runoff process, the CAT was applied to Idong experimental catchment, operated for research on the rural catchment characteristics and accumulated long term data by hydrological observation equipments since 2000. From the results of the main control points, Idong, Yongdeok and Misan reservoirs, the daily water levels of those points are consistent well with observed water levels, and the Nash-Sutcliffe model efficiencies were 0.32~0.89 (2001~2007) and correlation coefficients were 0.73~0.98.

• 대한조선학회논문집
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• 제42권6호
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• pp.673-678
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• 2005

IMO adopted ' International Convention for The Control and Management of Ships' Ballast Water and Sediments ' on February 13th 2004. According to this convention, a ballast water treatment system should be installed in all ships obligatorily up to a standard date. When the system is installed, economic propriety should be considered. The economic propriety analysis examines the profit of a relevant project which can be presented by a equation, (Profit) = (income) - (expense) - (tax). However, the ballast water system is not for the profit during the life cycle but for the satisfaction of the regulation. Therefore, the expense should be minimum against the profit. This study presents the LCC(Life-Cycle Cost) analysis for economic evaluation of several ballast water system of foreign products.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1424-1428
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• 2009

The performance of a heat pump using river water as a heat source was compared with that of a conventional air-conditioner for cooling and a boiler system for heating. The heat pump system using river water considered the 1-stage cycle for cooling and the 2-stage cycle for heating. The COPs of the river water source heat pump were $0.5{\sim}1.1$ higher than those of the conventional system in the cooling season. The LCC of the river water source heat pump system was lower 13.5% and 32.4% than that of the conventional system I and II. In addition, when the initial cost ratios of the river water source heat pump system to the conventional system I and II were less than 1.2 and 1.4, respectively, an acceptable payback was found to be less than 5 years.

• Membrane and Water Treatment
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• 제10권4호
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• pp.299-305
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• 2019

Managed aquifer recharge (MAR) systems are gaining interest as an alternative to conventional water resources. However, when the water recovered in MAR systems, dissolved iron and manganese species may easily oxidize and they cause well screen clogging or require abandonment of extraction wells. In this study, both oxic and anoxic conditions were analyzed to verify the feasibility of the membrane filtration performance under various solution chemistries. The fouling mechanisms of the metal ions under anoxic conditions were also investigated by employing synthetic wastewater. The fouled membranes were then further analyzed to verify the major causes of inorganic fouling through SEM and XPS. The newly suggested anoxic process refining existing membrane process is expected to provide more precious information about nanofiltration (NF) membrane fouling, especially for demonstrating the potential advantages to chemical-free drinking water production for indirect potable reuse.

• 태양에너지
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• 제19권3호
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• pp.101-113
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• 1999

Thermodynamic performance of a simple Rankine cycle, regenerative Rankine cycle, and Kalina cycle for Ocean thermal Energy Conversion(OTEC) is evaluated under the same condition with various working fluids. The evaporator and condenser are modeled by a UA and LMTD method while the turbine and pump are modeled by considering isentropic efficiencies. As for the working fluids, R22, R134a, R32, propylene, ammonia are used for the Rankine cycles while ammonia/water and R32/R134a mixtures are used for Kalina cycle. Calculated results show that newly developed fluids such non-ozone depleting refrigerants as R134a and R32 perform as well as R22 and ammonia. The regenerative Rankine cycle showed a 1.2 to 2.8% increase in energy efficiency as compared to the simple Rankine cycle while the Kalina cycle with ammonia/water mixture showed a 1.8% increase in energy efficiency. The efficiency of the Kalina cycle with R32/R134a mixtures is the same as that of a simple Rankine cycle using R22. Therefore, the regenerative Rankine cycle turns out to be best choice for OTEC applications.

• 대한기계학회논문집B
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• 제36권3호
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• pp.293-299
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• 2012

대형 선박의 추진용 디젤엔진에서 버려지는 배기가스의 열을 회수하기 위한 랭킨사이클이 적용된 발전시스템에 대하여 R245fa 및 water 의 작동유체들에 따른 열역학적 효율 특성을 분석하였다. 그 이론적인 계산 결과로, 고정된 질량유량의 R245fa 에 대하여 터빈입구의 압력이 증가할수록 사이클, 시스템, 및 전체적 효율이 증가하였고, 사이클에 의해 발생되는 순동력도 증가하는 특성을 보였다. 반면, water 의 경우에는 R245fa 에 비하여 더 낮은 질량유량 및 터빈입구 압력의 비율에서 최대의 시스템 효율을 보였다. 또한 water 에 대하여 최적화된 사이클의 순출력, 시스템 효율, 및 전체적 효율의 값들은 R245fa 의 경우보다 더 크게 나타났다.

• 한국수소및신에너지학회논문집
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• 제29권2호
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• pp.148-154
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• 2018

This paper presents a comparative analysis of thermodynamic performance of ammonia-water Rankine cycles with and without regeneration and Kalina cycle for recovery of low-temperature heat source. Special attention is paid to the effect of system parameters such as ammonia mass fraction and turbine inlet pressure on the characteristics of the system. Results show that maximum net power can be obtained in the regenerative Rankine cycle for high turbine inlet pressures. However, Kalina cycle shows better net power and thermal efficiency for low turbine inlet pressures, and the optimum ammonia mass fractions of Kalina cycle are lower than Rankine cycles.

• 한국지구과학회지
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• 제28권6호
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• pp.699-706
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• 2007

본 연구의 목적은 지구 시스템 과학을 학습하는 학생의 개념과 사고에 직접적인 영향을 미치게 될 지구과학 예비 교사들의 물 순환의 구성 요소와 순환 과정에 대한 인식을 밝히는 것이다. 국립사범대 지구과학교육학과에 재학 중인 지구과학 예비 교사 50명을 대상으로 개념 그리기 방법을 적용하여 물 순환의 구성요소로 응답한 개념들을 지구 시스템의 하위계인 수권, 기권, 암권, 생물권의 범주로 코딩하고, 물의 순환 과정으로 응답한 요소들로부터 지구 시스템 하위계의 상호작용에 대한 인식을 분석하였다. 예비 지구과학 교사들은 물 순환의 구성요소를 주로 수권과 기권에 한정하여 인식하고 있으며, 생물권에서 식물과 동물의 작용에 대한 인식이 매우 부족하고 특히 인간이 물의 순환에 미치는 영향에 대한 인식은 극히 드물었다. 물의 순환 과정에 대해서는 대부분의 예비 교사들이 증발과 강수만을 순환 과정으로 인식하고 있으며, 지표면의 이동에 비해 지하에서의 이동에 대한 인식이 부족하였다.

• 토지주택연구
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• 제3권3호
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• pp.271-278
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• 2012

전 지구적인 기후변화와 지구 온난화에 따라 서구 선진 국가들을 중심으로 저탄소 녹색성장(green growth)이 이슈로 등장하고 있고 이 전략은 미래의 성장동력으로까지 발전되고 있다. 저탄소 사회를 달성하기 위하여 세계 각국은 교토의정서를 체결하고 온실가스배출량을 2008년부터 2012년까지 1990년도 수준의 5.2%까지 줄이도록 선언하였다. 한편 급속한 도시개발과 불투수면적의 증가는 도시의 물순환의 변화를 초래한다. 본 연구에서는 녹색도시 개념을 검토하고 기존의 연구를 바탕으로 도시 및 단지수준에 적합한 물순환 계획요소를 검토하였다. 추가적으로 본 연구에서는 SWMM5-LID 수문모형을 이용하여 시범유역에 물순환 효과를 분석하였다. 물순환 분석은 개발전, 개발후, 녹색도시계획요소적용후(LID시설 적용후)에 대한 시범유역의 도시유출연속모의를 통하여 수행되었다.

• 대한기계학회논문집
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• 제19권1호
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• pp.231-239
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• 1995

This paper describes a computer simulation of the triple effect, water-lithium bromide absorption cooling cycles. The performance of the absorption systems is investigated through cycle simulation to obtain the system characteristics with the cooling water inlet temperature, the working solution concentrations, the ratio of the amount of the weak solution to the high, middle and low temperature generators, and the temperature difference of each solution heat exchanger. The efficiency of different cycles has been studied and the simulation results show that higher coefficient of performance could be obtained for the parallel cycle of constant solution distribution rate. As a result of this analysis, the optimum designs and operating conditions were determined based on the operating conditions and coefficient of performance.