• 한국수자원학회논문집
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• 제30권6호
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• pp.629-639
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• 1997

1960년대 이래로 우리나라 주요수계에는 이·치수를 목적으로 많은 댐들이 건설되어 운영되어 오고 있다. 계속 증가하는 용수수요를 충족시키기 위한 신규댐 개발이 국가 장기 수자원 개발계획에 포함되어 있어 수자원 시스템은 더욱 복잡해 질 것으로 예상된다. 이와 같은 특징은 장래 수자원 관리 정책 결정문제에서 보다 많은 대안 검토를 요구하게 되므로 이를 해결할 수 있는 합리적인 접근방법의 개발이 요구된다. 본 연구는 10여개 이상의 대구모 저수지 시스템 문제를 해결하기 위한 방법중 문제를 간략화하기 위한 시도로 중·소규모 댐에 대해서는 모의모형(HEC-5)을 적용하고 이의 결과를 대용량의 댐으로 구성된 최적화 모형(IDP)의 입력자료로 이용하여 최종적인 결과를 얻는 2단계 해석 방법을 한강유역 물수지 분석에 적용하였다. 아울러 한강수계의 기존 다목적댐과 장래 개발 계획댐을 하나의 시스템으로 구성하고 DPSA를 이용하여 유역 개념의 수자원 평가에 적용하였다.

• Ocean Systems Engineering
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• 제3권4호
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• pp.309-325
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• 2013

Ocean Thermal Energy Conversion (OTEC) systems utilize the temperature difference between the surface water and deep ocean water to generate electrical energy. In addition to ocean surface waves, wind and current, in certain locations like the Andaman Sea, Sulu Sea and the South China Sea the presence of strong internal waves may become a concern in floating OTEC system design. The current paper focuses on studying the dependence of the CWP hydrodynamic drag on relative velocity of the flow around the pipe, the effect of drag amplification due to vortex induced vibrations and the influence of internal waves on the floating semi and the cold water pipe integrated OTEC system. Two CWP sizes are modeled; the 4m diameter pipe represents a small scale prototype and the 10m diameter pipe represents a full commercial size CWP. are considered in the study.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.270-273
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• 2011

Water management is important in proton exchange membrane fuel cell because the water balance has a significant impact on the overall fuel cell system performance. In fuel cell vehicle, the vehicle's power demand is dynamic; therefore, the dynamic water management system is required. This present study proposes a method to control the humidity of the input air in cathode side of the fuel cell vehicle. The simulation using several driving cycles shows the proposed air humidification control obtains a relatively good result. The liquid saturation level is seen constant at the target level although still there are small deviations at driving cycles which having averagely high power demands.

• 한국분무공학회지
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• 제2권3호
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• pp.8-16
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• 1997

Ta investigate characteristics and spray of emulsified fuet we are mixed water with diesel oil using ultrasonic energy fuel feeding system. Separation ratio of emulsified fuel was shown good condition that of water content is small and longer ultrasonic energy adding time. Viscosity of emulsified fuel increased 79% with addition to water content and surface tension increased 1.6% in comparision to pure diesel oil. The SMD of emulsified fuel adding ultrasonic energy decreased with 3% in comparision to pure diesel oil. With increasing 5, 10% water content the SMD decreased 15.6, 20.1% in comparision to pure diesel oil. The mind-explosion was investigated with 4step.

• Asian Journal of Innovation and Policy
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• 제11권3호
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• pp.293-319
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• 2022

By analyzing the adaptive capacity, market formation and policy direction as functional areas of Technological Innovation System (TIS), the article evaluates the progress of renewable energy transition in the Maldives, with the inclusion of ideas from Mauritius and Cabo Verde. On the policy direction in the Maldives, technology roadmaps produced with assistance from International Renewable Energy Agency (IRENA) and Asian Development Bank (ADB) are evaluated. Although there are inducing factors such as the Solar Risk Management Initiative, the progress of energy transition is hindered by the lack of technical capacity and local value chain. The findings indicate the importance of facilitating and establishing industry and knowledge networks, incorporating innovation policies, greater involvement of the local private sector along with international investors, and taking water-energy nexus to achieve complementary targets. The study adds value to knowledge by offering a simplified TIS framework, with a current insight of the energy transition in Small Island Developing States with a focus on the Maldives.

• 한국수자원학회논문집
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• 제40권11호
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• pp.909-920
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• 2007

하천환경에 대한 사회적 요구에 의해 다양한 하천 복원 및 환경개선사업이 진행되고 있으므로, 이와 같은 사업의 효과를 평가할 방법론이 제공되어야 한다. PHABSIM은 하천 흐름과 관련되어 있는 수생 생물의 수리적 서식처 적합도를 평가하기 위해 제안된 방법이다. 본 연구에서는 보 철거 구간에 PHABSIM을 적용하여, 보 철거에 따른 피라미의 물리서식처 변화와 모형의 적절성을 평가하였다. 그 결과 일반적으로 보를 철거할 경우가 존치할 때보다 물리서식처가 향상된 것으로 나타났다. 그러나 유영력이 약한 산란기의 물리서식처는 보 상류의 유속이 증가되어 감소하는 것으로 나타났으며, 이에 대한 적절한 대책이 필요하다. 본 연구에 적용한 PHABSIM은 보 철거 사업을 포한한 다양한 하천사업의 평가와 필요성을 제시하는 효과적인 방법으로 활용될 수 있을 것이다.

• 한국물환경학회지
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• 제31권4호
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• pp.418-427
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• 2015

This study was carried out to evaluate the performance of a lab-scale novel septic tank system for improving the conventional septic tank in the developing countries of water shortages. The lab-scale novel septic tank system consists of sepetic tank, aeration tank with HBC-ring, and sand filter. Optimum HRT was reguired about 1.5days to get a total COD removal efficiency of 90%, COD, BOD and SS removal efficiency was about 70%, 60%, and 85% in sepetic tank only. The structure of sepetic tank with two stages results in the high removal efficiency of organic matter. When sepetic tank, aeration tank, and sand filter were more than HRT 1.5days, 18hrs, and 12hrs, respectively, final effluent was less than 20 mg/L of BOD, 14 mg/L of SS, so that there is a high potential of its use for reusing water in flush toilet. There is no significant effect of HRT change on nutrient removal. Total nitrogen removal efficiency was about 40%, final effluent was 30~40 mg/L of TN, total phosphorus removal efficiency was about 11~25%, final effluent was 9~12 mg/L of TP. Because there is very small amounts of organic nitrogen and phosphorus in effluent, it was possible to reuse water for agricultural use.

• 적정기술학회지
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• 제5권1호
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• pp.8-17
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• 2019

Solar pumps, for water lift systems, is becoming popular in rural areas for supplying drinking water in dry seasons when its need is elevated. The development in technology has also made solar pumps readily available and cheap which has increased its demands. So, for scattered settlements having a limited budget for operation and maintenance costs, solar pump is preferred over grid connected electrical pumping systems. This primary objective of the study was to design a solar photovoltaic pumping drinking water supply system for a small health post which is about 45 km east from Kathmandu, the capital city of Nepal. The study also compared and verified the final design with the system's existing design prepared by a development agency. The water source for this study was a confined aquifer 115m below the surface. The water demand was calculated to be 11m³ per day. A 1500 kPa submersible pump attached to a motor was selected and installed. Along with that twelve solar panels, reservoir, transmission main and distribution main was designed. The outcomes conclude solar photovoltaic pumping water supply systems to be cost-effective with an estimated cost of only USD 0.84 million per MLD. Solar pumps require low maintenance and operation costs and its repairs can quickly be done by the local people. The study also shows that solar technology produces no sound, needs no fuel making it environmentally friendly.

• 한국물환경학회지
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• 제28권1호
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• pp.121-128
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• 2012

The purpose of this study is to solve the problem of nutrient removal due to rapid hydraulic retention time (HRT) variation in small size private sewage treatment facility and to have better effluent quality by using natural zeolite as a coagulant aid. The experiments were conducted by applying different conditions of HRT, coagulant, and zeolite dosages. As an experimental result, $TBOD_{5}$, TSS, and TP removal efficiencies were 64.9%, 94.5%, and 98.8% at co-injection with zeolite. Overall removal efficiencies of $TBOD_{5}$, TSS, and TP have improved 15.7, 28.7, 6.1%, respectively. This result shows that zeolite addition could improve flocculation, increase setting velocity, and thus have better treatment. Therefore the use of zeolite as a coagulant aid can be useful in small size private sewage treatment facility, where especially extra nutrient removal is required to meet the legal standard for discharge.

• 동력기계공학회지
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• 제16권5호
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• pp.32-39
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• 2012

The study experimented to understand ice-on-coil type ice making characteristics on to 3 kinds of circular tube, oval tube and small diameter tube using ice maker. The experiment were carried out under various conditions, that used brine temperature($-10^{\circ}C$, $-6^{\circ}C$), brine flow rate(1.0m/s, 1.8m/s) and inlet water temperature ($6^{\circ}C$, $12^{\circ}C$) etc. Mass of ice per ice making area increased according to the decrease of the brine temperature and inlet water temperature, but that was increased according to the increase of the brine flow rate. Oval ice making tube produced ice 1.11 to 2.46 times that of 9mm circular ice making tube, and 3mm small diameter ice making tube produced ice 1.06 to 1.51 times that of 9mm circular ice making tube.