• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.331-331
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• 2020

급격한 산업화와 도시화로 인한 도시유역의 불투수면의 증가와 이에 따른 배수능력의 저하로 인해 도시 물순환의 왜곡이 발생하였다. 따라서 과거 도시 물관리 기법의 한계가 나타났으며 이를 위해 저영향개발 기법 등과 같은 도시 물관리 기법의 패러다임이 변화하였다. 본 연구에서는 저영향개발 기법에서 도시유역 내 활용이 유용한 침투형 시설 중 투수블럭에 대한 물순환 성능평가를 실외실험을 통해 분석하였다. 성능평가 실험은 부산대학교 양산캠퍼스 한국 GI&LID 센터 내 투수블록 뿐만 아니라 블록 하부 골재층까지 설치가 가능하도록 되어있어 실제 현장과 유사한 환경을 구축이 가능한 2.4×10.9×0.4 (m) 규모의 주차장형 LID 실증시험시설을 활용하였다. 인공강우 분사를 위한 실외 인공강우모사 장치 크기는 2×2(m)으로 본 시험을 위하여 5개의 인공강우모사 장치를 연결하여 활용하였으며, 본 시험장치는 강우를 공급하기 위한 수조와 펌프, 일정한 유량을 유입하기 위한 유량계, 강우를 분사하기 위한 노즐, 인공강우가 실제 강우와 같이 자유낙하 하도록 구현하기 위한 오실레이터 등으로 구성되었다. 시험대상인 틈새투수블록은 석재블록 규격 400×600×100 mm이며 재질은 받침안정층(흙), 투수블록(화강석)으로 구성되어 있다. 실험의 시나리오는 시험체에 강우강도 30mm/hr, 50mm/hr, 100mm/hr에 해당하는 양을 1시간 동안 유입하여 시험 시작 후, 강우지속시간, 표면유출지속시간, 표면유출량을 1분 단위로 측정. 시험체에 유공관이 설치된 경우에는 침투유출지속시간, 침투유출량도 함께 1분 단위로 측정하였으며 각 강우강도별로 측정하고, 1회 측정 후, 각 시험별 시험 대상체의 조건을 같게 하기 위한(하부 지반의 건조) 약 3일 이후(상황에 따라 변동 가능) 시험하였다. 본 실험의 결과, 강우강도가 30 mm/hr와 50 mm/hr인 경우에는 화강석 틈새투수블록포장에서 지표 유출이 발생하지 않았으며, 강우강도 100 mm/hr의 경우 260 L의 지표 유출이 발생하여, 불투수표면 대비 84%의 지표유출 저감률을 보여줌으로서 투수블럭에 물순환 성능에 대한 효과를 분석하였다.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.257-264
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• 2015

To maintain sustainability of nuclear energy as an important energy source, both safety problem and Spent Nuclear Fuels(SNFs) problem should be solved. In case of Gen-IV reactors such as fast reactor, SNFs can be used as fuels by using fast neutrons. It can be a suitable treatment method of high-level waste in near future. Liquid metals such as Sodium or Lead-Bismuth Eutectic (LBE) can be possibly used as a coolant to use fast neutrons. In this paper, it was described that natural circulation parameter studies, design analyses, material selections and a completion of facilities. To develop a natural circulation facility, thermal hydraulic analyses were performed. Installation technique of liquid metal natural circulation were secured.

• Journal of the Korean Solar Energy Society
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• v.28 no.5
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• pp.21-27
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• 2008

In this study, the design of the solar heating system for district heating as well as it's operating characteristics and the performance analysis was carried out. This solar district heating system was composed of two different types of solar collector circuit, flat plate and vacuum tube solar collector, in a system. This system supply constant temperature of hot water without solar buffer tank. For this, the proportional(variable flow rate) control was used. The experimental facility for this study was used the Bundang district solar heating system which was installed in the end of 2006. The operating characteristics and behaviour of each collector circuits are investigated especially for the system design and control. The yearly solar thermal efficiency is 47.5% on the basis of aperture area and 39.8% on the basis of gross area of collector. As a result this solar heating system without solar buffer tank and with proportional controller was testified a very effective and simplified system for district heating. It varied especially depend on the weather condition like as solar radiation and ambient temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.4
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• pp.213-219
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• 2015

A thermal storage tank with internal heat exchange coils is commonly used in solar thermal systems with a collector area below $100m^2$. The coils are installed in the lower part of the tank because the temperature of the upper part of the tank can drop if the outlet temperature of the collector becomes lower than the upper temperature of the tank, which is a kind of temperature reversal. As an alternative to the well-mixed storage tank with lower coil only, we have proposed a tank with lower and upper coils and have achieved superior thermal stratification in the tank, which results in increased collector efficiency and solar fraction. But, the phenomenon of temperature reversal was often observed in the tank when the load or solar radiation changed rapidly. In the present work, revised control was successfully applied, i.e., to heat only the lower coil using a three way valve if temperature reversal occurs and to operate the collector at a low flow rate when the quality of solar radiation is not good.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.173-181
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• 2011

This paper proposes photovoltaic thermal hybrid module to get the electrical and thermal performance of building integrated photovoltaic(BIPV) system. BIPV system is decreased the system efficiency because output of PV is decreased by the thermal rising on generating. In order to improve the efficiency of BIPV module, water cooling system is applied and generated thermal is used the warm water system. Water cooling system uses the flux control algorithm considering water temperature and power loss. Electrical and thermal performance of proposed photovoltaic thermal hybrid module is confirmed through the actual experiment and herby proved the valid of this paper.

• Communications for Statistical Applications and Methods
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• v.17 no.1
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• pp.39-45
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• 2010

As the value of environment is increasing, the water quality has been a matter of interest to the nation and people. Research on water quality has been widely studied, but focused on geographical characteristic and river characteristics like inflow, outflow, quantity and speed of water. In this paper, two approaches to measure the similarity of sampling sites by using water quality data are discussed and compared with two-years empirical data of Yongdam-Dam. The existing method has calculated their similarities with principal component scores. The proposed approach in this paper use correlation matrix of water quality related variables and MDS for measuring the similarity, which is shown to be better in the sense of being clustering which is identical to geographical clustering since it can consider the time series pattern of water quality.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.4
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• pp.418-423
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• 2014

Small hydropower has been considered as a solution to resolve the problem of exhaustion of fossil fuel and industrial pollution. In this study, we developed and tested a Cross-Flow Turbine with two guide vanes to optimize the small hydropower for the site condition with large fluctuation of head and flow rate. Furthermore, in the condition of constant inlet head, CFD analysis was carried out to analyze the effect of air suction and valve position on the performance characteristics. The results showed that the air suction can minimize the hydraulic loss caused by the Recirculation flow in the runner passage and flow impact on main shaft so that it can increase the turbine efficiency and output power.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.43-46
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• 2022

The optimal operation of the water purification plant can be carried out only when the required flow rate is supplied in a timely manner using the minimum electrical energy by accurately predicting the pattern and amount of tap water used in the consumer. In order to ensure the stability of tap water production and supply, a system that can be pre-verified before applying AI-based composite sensors to the water purification plant was established to derive complementary matters through the pre-verification model for each composite sensor and improve the quality and operation stability of the composite sensor data.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.269-269
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• 2020

수자원은 유역 내에서 제한적인 범위 내에서 무한하게 순환한다. 이러한 물의 순환의 특성을 지속적으로 파악하는 것은 지속적인 수자원 확보, 자연 환경에 대한 변화를 유연하게 대처할 수 있는 가장 중요한 연구 중 하나이다. 유역 내에 물의 유입은 대표적으로 강우량이 있고 유출로는 하천 및 지하수의 유출량과, 증발산량이 있다. 유입의 형태와 지면의 상태에 의해 다양한 유출 특성이 나타나기 때문에 지면 내에서의 물의 이동 특성을 분석하는 것은 필수적이다. 본 연구에서는 토양수분량을 지속적으로 측정하여 토양내의 물의 저류량을 실증적으로 추정하였으며 초기 토양수분량과 토양 저류량의 관계를 분석하였다. 또한 유역내의 얼마만큼의 강우량이 토양 내에서 저류하고 유출 발생에 기여하는지에 대해 분석하고자 하였다. 이를 위해 토양수분량과 강우량이 안정적으로 측정되고 있는 2018, 2019년 설마천 유역에 적용하였다. 특히 선정된 설마천 유역은 증발산량과 유역 하단부에 유량 관측소가 존재하여 물수지 분석에 유리한 조건을 가지고 있어 유역 내에 물 흐름에 정량적으로 비교 및 파악할 수 있는 지역이다. 사양토 성질을 가진 설마천 유역은 20%때의 습윤 구간에서 중력에 의한 직접유출이 발생하며 이때를 기준으로 초기토양수분과 선행토양수분량의 조건에 따라 토양내의 저류량의 거동의 경향성이 뚜렷하게 나타났다. 향후 본 연구를 통해 각 유역의 토양 성질에 따른 토양 저류량을 파악하고 그에 따라 유출량 자료를 결합한다면 수자원 재해에 대한 예보 및 피해 저감 방안을 마련할 수 있을 것이라 판단된다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.2
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• pp.153-170
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• 2022

Waterjet has been comprehensively used in urban areas owing to a suitable technique for cutting concrete and rock, and low noise and vibration. Recently, the abrasive waterjet technique has been adopted and applied by the Korea Atomic Energy Research Institute to demolish concrete plugging without disturbing and damaging In-situ Demonstration of Engineered Barrier System in the disposal research tunnel. In this study, the use of abrasive waterjet in the tunnel was evaluated for practical applicability and the existing cutting model was compared with the experimental results. As a variable for waterjet cutting, multi-cutting, water flow rate, abrasive flow rate, and standoff distance were selected for the diversity of analysis. As regarding the practical application, the waterjet facilitated path selection for cutting the concrete plugging and prevented additional disturbances in the periphery. The pump's noise at idling was 64.9 dB which is satisfied with the noise regulatory standard, but it exceeded the standard at ejection to air and target concrete because the experiment was performed in the tunnel space. The experimental result showed that the error between the predicted and measured cutting volume was 12~13% for the first cut and 16% for second cut. The standoff distance had a significant influence on the cutting depth and width, and the error tended to decrease with decrement of standoff distance.