• Nuclear Engineering and Technology
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• 제41권7호
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• pp.945-952
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• 2009

The Three Mile Island Unit 2 (TMI-2) accident provides unique full scale data, thus providing opportunities to check the capability of codes to model overall plant behavior and to perform a spectrum of sensitivity and uncertainty calculations. As part of the TMI-2 analysis benchmark exercise sponsored by the Organization for Economic Cooperation and Development Nuclear Energy Agency (OECD NEA), several member countries are continuing to improve their system analysis codes using the TMI-2 data. The Republic of Korea joined this benchmark exercise in November 2005. Seoul National University has analyzed the TMI-2 accident as well as the currently proposed alternative scenario along with a sensitivity study using the Modular Accident Analysis Program Version 4.03 (MAAP4.03) code in collaboration with the Korea Hydro and Nuclear Power Company. Two input files are required to simulate the TMI-2 accident with MAAP4: the parameter file and an input deck. The user inputs various parameters, such as volumes or masses, for each component. The parameter file contains the information on TMI-2 relevant to the plant geometry, system performance, controls, and initial conditions used to perform these benchmark calculations. The input deck defines the operator actions and boundary conditions during the course of the accident. The TMI-2 accident analysis provided good estimates of the accident output data compared with the OECD TMI-2 standard reference. The alternative scenario has proposed the initial event as a loss of main feed water and a small break on the hot leg. Analysis is in progress along with a sensitivity study concerning the break size and elevation.

• Advances in environmental research
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• 제1권1호
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• pp.37-55
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• 2012

Here we show that perchlorate reduction during pitting corrosion of zero-valent titanium (ZVT) is likely caused by dissolved titanium species, especially Ti(II). Several possible mechanisms were suggested based on the literature and were evaluated based on experimental observations. Direct reduction of perchlorate on the bare metal of the ZVT electrode was thermodynamically infeasible due to the high anodic potential that was applied. Other potential mechanisms were considered such as reduction by small ZVT metal particles released from the electrode and direct reduction on the oxide layer of the electrode where potential was sufficiently reduced by a high ohmic potential drop. However, these mechanisms were not supported by experimental results. The most likely mechanism for perchlorate reduction was that during pitting corrosion, in which ZVT is partially oxidized to form dissolved ions such as Ti(II), which diffuse from the electrode surface and react with perchlorate in solution. This mechanism is supported by measurements of the dissolution valence and the molar ratio of ZVT consumed to perchlorate reduced (${\Delta}Ti(0)/{\Delta}ClO_4{^-}$). The results shown in this study demonstrate that ZVT undergoing pitting corrosion has the capability to chemically reduce perchlorate by producing dissolved Ti(II) and therefore, it has the potential to be applied in treatment systems. On the other hand, the results of this research imply that the application of ZVT undergoing pitting corrosion in treatment systems may not be feasible now due to several factors, including material and electricity costs and possible chloride oxidation.

• KIEAE Journal
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• 제10권1호
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• pp.33-44
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• 2010

These days, the use of alternative energy is recognized as one of countermeasures to rising oil prices and climate-change agreements. Especially, it is regarded as a main element to realize 'Low-Carbon Green Growth', one of the key policies of MB government. However, though alternative energy, renewable energy, is a main policy issue of the present administration, there are many problems to solve: the lack of recognition of its energy, the low level of its technology, its expert's shortage, and its limited application fields. Therefore, to stimulate the use of alternative energy in Korea and to change the recognition of this energy, it is needed to utilize it to urban street furniture that many people visit and use. In particular, if alternative energy is first applied to street furniture that needs energy for its management, the effect of publicity and energy saving will be so great. In this study, for the basic research to introduce and promote various alternative energy sources such as solar power, wind power, small hydro power, and human power, we analyzed the present condition of development of Korean and foreign street furniture items. Furthermore, we evaluated the level of development of these street furniture products and the design types of them and from these evaluations suggested the design direction that can solve problems in development and improve the possibility of application of these energy sources to these street furniture items. Through these analyses, this study aims to enhance the image of future environment-friendly city and make new index for the application of alternative energy.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.11-17
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• 2012

The Waikato River is New Zealand's longest River, though relatively small on international scales. It drains the central North Island and has New Zealand's largest lake (Lake Taupo) at its headwaters. The upper reaches have sustained flows fed by large aquifers which are recharged by rainfall events providing relatively constant river flows, whereas the lower reaches respond more directly to rainfall events having more peaky flows after rainfall and extreme low flows during dry periods. Consumptive allocation from the river is relatively low with only about 3% of the mean annual flow being allocated. However, more than seven times the river's flow is allocated for non-consumptive purposes before discharging to the Tasman Sea. The majority of this non-consumptive allocation is for hydro power generation and as cooling water at both thermal and geothermal power stations which produce up to 25% of New Zealand's electricity. The upper half of the river has been heavily modified with the construction of eight dams for power generation. This has resulted in a succession of cascading dams replacing the previously uncontrolled river. The Waikato River also provides drinking water for Auckland City (NZ's largest city) and Hamilton City (NZ's 4th largest city). In recent years there has also been considerable growth in water requirements for pasture irrigation to support the intensification of dairy farming in the catchment. Operators of the power stations are concerned that any further consumptive allocation will further reduce their ability to generate electricity. The Waikato Regional Council, who is charged with managing the river and allocation of water, has recently set new rules for managing the conflicting allocation demands on the Waikato River. This has resulted in an end to further allocation of water where it results in a loss of water for electricity generation from renewable resources (fresh water and geothermal water). The exception to this is the prioritisation of water for municipal supplies ahead of other consumptive uses such as industries and irrigators.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.270-270
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• 2015

소수력은 물이 가지는 위치 에너지나 운동 에너지를 동력으로서 이용하는 것 또는 그렇게 얻을 수 있는 에너지로 소수력발전에 의해 생산되는 에너지는 부존자원이 풍부하여 다른 신재생에너지에 비해 높은 잠재력을 가지고 있어 개발가치가 충분한 부존자원이다. 또한, 친환경적인 청정에너지 중 하나로 대체 에너지원에 비해 높은 에너지를 가지고 있어 개발가치가 큰 부존자원으로 평가되고 있으며, 초기투자비에 비해 유지관리비용이 낮은 편이다. 이러한 개발가치가 있는 잠재 소수력 에너지를 알아보기 위해 한강권역의 표준유역인 안양천을 대상으로 산정해 보았다. 안양천의 잠재 소수력 에너지 산정을 위해 2004년 1월 1일부터 2013년 12월 31일까지의 구로 강우관측소의 일강우자료와 신정수문관측소의 일수위자료 및 유량자료를 수집하였으며, 하상정보를 파악하였다. 낙차는 수차발전기를 회전시켜 전기를 생산하여 상용발전이 가능하며 소수력 발전을 최대치로 생산할 수 있는 조건의 낙차인 2m로 선정하여 소수력 산정공식에 적용하였다. 이에 본 연구에서는 여름인 7월에 1,421.1Kw로 최대값으로 나타났으며, 겨울인 12월에 최소값인 141.9Kw로 나타나 안양천에는 월간 최소 100Kw이상의 전력을 생산할 수 있는 잠재 소수력 에너지를 보유하고 있는 것으로 판단된다. 추후, 국토교통부와의 협력을 통해 관측되는 수문자료(강우, 수위, 유량)를 실시간으로 제공받아 일단위, 월단위, 년단위, 계절단위의 잠재 소수력 에너지를 실시간으로 산정할 수 있는 환경을 구축하여 지속적으로 잠재 소수력 에너지를 평가하고 재생에너지 확보를 통해 추구할 수 있는 경제적 이익 또한 분석되어야 할 것으로 판단된다.

• 한국기후변화학회지
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• 제6권2호
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• pp.73-85
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• 2015

With 12 environmental basic facilities (EBF) in Busan, each business place's present situation of the operation of new and renewable energy as well as the feasibility to establish additional systems of utilizing solar energy (photovoltaic power generation system [PPGS] and solar heating system [SHS]) were investigated. Currently, with the environmental basic facilities, the new and renewable energies (such as, waste heat, biogas, PPGS, SHS, and small hydro power) can produce 195 GWh per year as electric power unit. Among the energy sources, except waste heat, biogas (154 GWh/yr) appears as the highest. Next, PPGS is the second most widely used system and produces 5,560 MWh/yr at 11 business places. Through a field survey, it appears that 19 business places of total 27 places at 12 EBFs have good locational conditions and they need an introduction of PPGS. Through it, it is investigated that it would be possible to produce 5,311 MWh/yr and to reduce $2,348tCO_2/yr$. And, it is identified that SHS can be additionally introduced in only 4 EBFs. This can reduce energy cost as much as one ten million won/yr and green-house gas as much as $28tCO_2/yr$. A cost-benefic analysis shows that the use of governmental support or private investment can be the most efficient way, when PPGS and SHS are introduced in EBFs.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3990-4002
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• 2021

CSPACE (Core meltdown, Safety and Performance Analysis CodE for nuclear power plants) for a simulation of severe accident progression in a Pressurized Water Reactor (PWR) is developed by coupling of verified system thermal hydraulic code of SPACE (Safety and Performance Analysis CodE for nuclear power plants) and core damage progression code of COMPASS (Core Meltdown Progression Accident Simulation Software). SPACE is responsible for the description of fluid state in nuclear system nodes, while COMPASS is responsible for the prediction of thermal and mechanical responses of core fuels and reactor vessel heat structures. New heat transfer models to each phase of the fluid, flow blockage, corium behavior in the lower head are added to COMPASS. Then, an interface module for the data transfer between two codes was developed to enable coupling. An implicit coupling scheme of wall heat transfer was applied to prevent fluid temperature oscillation. To validate the performance of newly developed code CSPACE, we analyzed typical severe accident scenarios for OPR1000 (Optimized Power Reactor 1000), which were initiated from large break loss of coolant accident, small break loss of coolant accident, and station black out accident. The results including thermal hydraulic behavior of RCS, core damage progression, hydrogen generation, corium behavior in the lower head, reactor vessel failure were reasonable and consistent. We demonstrate that CSPACE provides a good platform for the prediction of severe accident progression by detailed review of analysis results and a qualitative comparison with the results of previous MELCOR analysis.

• 한국수자원학회논문집
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• 제54권11호
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• pp.863-873
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• 2021

다공성 매질에서 오염물 이동에 지배적인 기작인 역학적 분산은 공극 내 유속 차이에 의해서 발생한다. 종분산계수와 종분산지수는 이송확산 모형의 수리분산 매개변수이며, 실험을 통하여 얻어야만 한다. 수리평균반경은 공극 내 물의 흐름 양의 크기와 강도를 표현할 수 있으며, 매질의 물리적 특성인자를 이용하여 계산할 수 있다. 본 연구는 순간주입 추적자실험을 통하여 자갈 다공성매질에서 수리평균반경을 이용하여 종분산지수를 구할 수 있는 거듭제곱형의 경험식을 도출하였다. 경험식은 스케일상수 계산식이 포함되어 있어 이동거리에 따른 종분산지수의 산정이 가능하며, 소규모 유량의 균질한 자갈로 구성된 수로에 적용이 가능할 것으로 기대된다.

• 한국수자원학회논문집
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• 제51권1호
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• pp.11-18
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• 2018

본 연구에서는 다중 기후모델에 의한 미래 기후자료를 기반으로 SWAT-K 유역모형을 적용하여, 제주도 지역의 미래 기후변화에 따른 수자원 영향을 평가하였다. 기후모델에 따른 미래 전망자료의 불확실성을 고려하여 9개의 GCM 모델의 기후자료를 미래기간(2010~2099년)에 대한 SWAT-K 모형의 기상자료로 적용하였다. 과거(1992~2013년) 및 미래기간에 대한 연도별 수문변화를 분석한 결과 강수량, 유출량, 증발산량, 함양량 모두 증가하는 추세로 나타났다. 과거기간에 비해 유출량의 변화가 가장 크게 나타났으며(최대 50% 증가), 증발산량은 상대적으로 작게 나타났다(최대 11% 증가). 월별로는 8월과 9월의 강수량 증가에 따라 유출량과 함양량도 크게 증가하는 반면, 동일기간에 대한 증발산량은 감소하는 것으로 분석되었다. 1월과 12월은 반대의 경향이 나타났다. 미래의 물수지 변화를 분석한 결과 강수량 대비 유출량, 증발산량, 함양량의 비율은 변화가 크지 않으나, 과거와 비교했을 때 RCP 8.5 시나리오에서 유출량 비율은 최대 4.3% 증가하는 반면, 증발산량 비율은 최대 3.5% 감소하는 것으로 나타났다. 기존의 타 연구와 본 연구에서 도출한 결과를 종합해 볼 때, 현재 제시되고 있는 기후변화 시나리오 가정 하에서는 미래로 갈수록 점차 강수량과 유출량이 증가할 것이고 특히 여름철 강수량 및 유출량의 증가가 예상된다. 이로 인해 제주도 지역의 함양량도 함께 증가할 것으로 판단할 수 있다. 다만, 본 연구는 장기적인 측면에서 자연적인 기후변화로 인한 영향을 분석한 것이며, 추가적으로 단기적인 수재해 대응을 위한 홍수와 가뭄관리, 인위적인 용수 수급 관리 등에 대한 종합적인 분석을 통해 제주도 수자원의 지속가능한 이용을 위한 대응방안이 필요하다고 판단된다.

• 한국지리정보학회지
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• 제8권3호
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• pp.96-106
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• 2005

원격탐사와 GIS 기법는 시공간 측면에서 매우 귀중한 정보를 제공할 수 있으며, 홍수와 같은 재해 발생시 홍수발생 지역에 대한 매핑, 모니터링 빚 재해지역 관리 등에 있어 매우 유용한 정보를 제공할 수 있다. 지난 2000년 메콩강 유역의 Tonle Sap호에서 발생한 홍수에 의해 많은 피해가 발생하였으며, 특히 7월과 10월 사이에 두 차례의 홍수 피크가 기록되었다. 본 연구에서는 홍수피해에 대한 정량적인 분석을 위해 ISODATA와 세크멘테이션 기법을 이용하여 Landsat ETM+와 RADARSAT 영상을 분석하였다. 그러나, 영상으로부터 분석된 범람면적이 구름과 복잡한 지표피복물 등으로 인해 실제 홍수피해 상황을 정확히 반영하지 못했다. 따라서, 이러한 문제점을 해결하고자 GIS 기능 중 비용-거리 (cost-distance) 기법을 이용하여 홍수범람 면적을 분석하였으며, 분석결과는 수치표고자료(DEM)와 중첩하여 홍수량을 계산하였다. 계산된 홍수량은 수리모형인 MIKE 11의 모델링 결과와 비교하였다. 계산결과 영상 내에 많은 구름이 존재하는 Landsat ETM+ 영상의 경우와 복잡한 지표피복이나 시스템 변수 등의 영향으로 홍수피해 지역을 정확히 분류하기 어려운 RADARSAT 영상에서도 좋은 결과를 얻을 수 있었다.