• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.34-37
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• 2001

This paper evaluate reliability indices of a part of transmission network of KEPCO system. Quantitative evaluation of transmission system reliability is very important because successful operation of an electric power system in the deregulated electricity market depends on transmission system reliability management. Monte Carlo methods are often preferable, when complex operating conditions are involved and/or the number of sever events is relatively large. Monte Carlo simulation methods and CMELDC(CoMposite power system Effective Load Duration Curve) were used in this paper.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.538-538
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• 2017

우리나라의 현행 수질오염총량제도에서 비점오염원에 대한 배출량은 배출원별로 유량조건에 따라 배출계수를 적용하여 산정하고 있으나, 강우 및 유역특성에 따라 크게 좌우되는 비점오염 배출특성을 반영하는 것에는 어려움이 있다. 한편, 역산모델링은 결과를 바탕으로 원인 값을 추정하는 방식으로 유량 및 수질측정결과, 점오염원 배출량 등 실측결과를 바탕으로 비점오염 배출량을 추정할 수 있다. 본 연구에서는 역산 모델링 기법을 이용하여 경안천 유역에서 배출되는 총인의 비점오염 배출량을 추정하고, 부하지속곡선을 통해 비점배출기준을 산정하고자 한다. 경안천 유역의 수질 및 유량측정자료, 하수처리장 현황, 오염원 자료 등을 수집하여, 점오염원 배출량을 추정하고 역산 모델링을 수행하였으며, 비점배출총량을 산정하였다. 본 연구의 결과는 현행 수질오염 총량제도의 배출계수에 대한 재검토와 향후 유량조건에 따른 차별적인 비점오염원 관리 필요성에 대한 기초자료로 활용될 수 있을 것으로 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.239-241
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• 1998

The probabilistic production simulation of power system generally has been used to formulate a reasonable power production plan or generation planning. It integrates the convolution process of a generating unit's random outage(FOR) with equivalent load duration curve(ELDC), and provides the reliability indices of power system. This paper presents the reliability characteristics of power system reflected on demand side management and proposes the modified ELDC representation technique due to the high-efficient end-use diffusion among the customers. Load reductions are simulated from the multi-state deconvolution process with the saved capacity of end-use. Case study shows the computed reliability from the power system production simulation incorporated with DSM planning scheme.

• 한국물환경학회지
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• 제28권2호
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• pp.247-254
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• 2012

Soil and Water Assessment Tool (SWAT) model has been widely used in estimation of flow and water quality at various watersheds worldwide, and it has an auto-calibration tool that could calibrate the flow and water quality data automatically from thousands of simulations. However, only continuous measured day flow/water quality data could be used in the current SWAT auto-calibration tool. Therefore, 8-day interval flow and water quality data measured nationwide by Korean Ministry of Environment (MOE) could not be used in SWAT auto-calibration even though long-term flow and water quality data in the Korean Total Maximum Daily Load (TMDL) watersheds available. In this study, current SWAT auto-calibration was modified to calibrate flow and water quality using 8-day interval flow and water quality data. As a result of this study, the Nash and Sutcliffe Efficiency (NSE) values for flow estimation using auto-calibration are 0.77 (calibration period) and 0.68 (validation period), and NSE value for water quality (T-P load) estimation (using the 8-day interval water quality data) is 0.80. The enhanced SWAT auto-calibration could be used in the estimation of continuous flow and water quality data at the outlet of TMDL watersheds and ungaged point of watersheds. In the next study, the enhanced SWAT auto-calibration will be integrated with Web based Load Duration Curve (LDC) system, and it could be suggested as methods of appraisal of TMDL in South Korea.

• 한국전산구조공학회논문집
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• 제37권3호
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• pp.179-186
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• 2024

본 논문에서는 충격파 형태의 폭발 하중을 받는 부재의 소성 범위를 고려한 SDOF 해석의 수정계수를 개발하였다. SDOF 해석의 수정계수는 MDOF 해석 결과 값을 비교하여 도출하였다. SDOF 해석에 영향을 미치는 매개변수로 부재의 경계조건, 폭발 하중 지속시간과 고유주기 비를 선정하였다. 수정계수는 탄성 하중-질량 변환 계수를 기준으로 산정하였다. 수정계수 곡선은 상한, 하한 매개변수 경계 사이에 있도록 타원 방정식을 이용하여 도출하였다. 서로 다른 단면과 경계조건을 가지는 예제에 수정계수를 적용한 결과 SDOF 해석의 오차율이 15%에서 3%로 감소하였다. 본 연구의 결과는 수정계수를 적용하여 SDOF 해석의 정확도를 높임에 따라 폭발 해석에 널리 활용될 수 있다.

• 한국습지학회지
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• 제18권4호
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• pp.424-431
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• 2016

생태저류지와 같은 LID 시설은 강우유출수를 관리하기 위하여 적용된다. LID 개념이 강우유출수 관리 계획의 중요한 부분이 되면서, LID 시설의 수문학적 성능과 LID 시설이 배수분구의 수문환경에 미치는 영향에 대한 명확한 이해가 필요한 상황이다. 본 연구는 설계 전략으로서 유황곡선의 활용에 관한 사항을 다루고 있다. 많은 LID 시설들과 마찬가지로 생태저류지는 자연 상태의 수문현상을 재현하고자 설치된다. 본 연구에서는 유황곡선 기준을 만족하는 생태저류지의 크기를 결정하려는 시도가 수행된다. 연구 결과, 현재 비점오염저감시설의 용량기준인 "5mm * 처리대상구역의면적"은 불투수율 20-30%인 지역에 유효함을 살펴볼 수 있다. LID 시설이 전형적으로 설치되는 100% 불투수 지역의 경우 자연상태 유황곡선의 재현을 기준으로 보면 47mm 정도의 유출고를 차집할 수 있는 용량이 요구되며, 이는 처리대상구역 면적의 11% 정도가 생태저류지로 활용되어야함을 의미한다. 하지만, 시설의 용량과 시설 면적의 기준은현실적으로 구현 가능한 조건에서 설정되어야 할 것이며, 또한 처리대상구역의 개별적인 수문학적 특성을 반영하여 결정되어야 할 것이다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.85-85
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• 2020

South Korea experiences few large scale erosion and sedimentation problems, however, there are numerous local sedimentation problems. A reliable and consistent approach to modelling and management for sediment processes are desirable in the country. In this study, field measurements of sediment concentration from 34 alluvial river basins in South Korea were used with the Modified Einstein Procedure (MEP) to determine the total sediment load at the sampling locations. And then the Flow Duration-Sediment Rating Curve (FD-SRC) method was used to estimate the specific degradation for all gauging stations. The specific degradation of most rivers were found to be typically 50-300 tons/㎢·yr. A model tree data mining technique was applied to develop a model for the specific degradation based on various watershed characteristics of each watershed from GIS analysis. The meaningful parameters are: 1) elevation at the middle relative area of the hypsometric curve [m], 2) percentage of wetland and water [%], 3) percentage of urbanized area [%], and 4) Main stream length [km]. The Root Mean Square Error (RMSE) of existing models is in excess of 1,250 tons/㎢·yr and the RMSE of the proposed model with 6 additional validations decreased to 65 tons/㎢·yr. Erosion loss maps from the Revised Universal Soil Loss Equation (RUSLE), satellite images, and aerial photographs were used to delineate the geospatial features affecting erosion and sedimentation. The results of the geospatial analysis clearly shows that the high risk erosion area (hill slopes and construction sites at urbanized area) and sedimentation features (wetlands and agricultural reservoirs). The result of physiographical analysis also indicates that the watershed morphometric characteristic well explain the sediment transport. Sustainable management with the data mining methodologies and geospatial analysis could be helpful to solve various erosion and sedimentation problems under different conditions.

• 한국초전도ㆍ저온공학회논문지
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• 제7권4호
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• pp.28-31
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• 2005

To verify the feasibility of bifilar winding type superconducting fault current limiter (SFCL) using BSCCO tape, two types of magnets were fabricated and tested by short-circuit in this research. Even if the FCL using high Tc superconducting (HTS) tape has zero resistance in normal state, it needs to be wound as a bifilar winding for zero inductance. Solenoid type and pancake type bifilar winding magnets are designed and fabricated with the same length of BSCCO tape. The test system consists of AC power supply, transformer, fault switch, load and bifilar winding magnet. The applied AC voltages during fault duration, 0.1s, were from 0.5V to 20V. The test results without bifilar winding magnet were compared with those with each type magnets. The test results include voltage against magnet, transport current and generated resistance curve. Thermal stability, the recovery time, was studied from the results of two type magnets. The pancake type was the most effective to limit fault current but the solenoid type was thermally the most stable. From this research, short-circuit characteristics of the two types were obtained.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.590-599
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• 2006

In this study, Liquefaction characteristics of saturated sand under various dynamic loadings such as sinusoidal loading, increasing wedge loading, and real earthquake loading were investigated focusing on the dissipated energy. From the results of cyclic triaxial test, liquefaction resistance strength was calculated by the concept of energy according to the type of input loading. Liquefaction resistance strength was expressed in accumulated dissipated energy calculated from stress-strain curve(hysteresis loop). The dissipated energy according to loading type was compared and the energy-based evaluation was proposed. The procedures are presented in terms of normalized energy demand(NED), normalized energy capacity(NEC), and factor of safely, where NED is the load imparted to the soil by the loading(both amplitude and duration), NEC is the demand required to induce liquefaction, and factor of safely is defined as the ratio of NEC and NED.

• 한국가구학회지
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• 제12권1호
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• pp.47-55
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• 2001

Violin bridge blank cut from maple wood with good quality has typical pattern of the radial direction in the side edge with minimal dispersion. This experimental study was designed and carried out to examine the effect of the physical and macroscopical characteristics on the compressive creep of violin bridge blank which had been imported from European manufacturer. This research arose from the idea that the maple solid wood with heterogeneous wood density and ray direction in the side edge would have uneven rheological property of violin bridge blank which is supposed to be pressed by the tension of strings. Experimentally, the compressive creep of bridge blank became smaller with the higher density of imported maple wood and showed clear density-dependence for the duration of load under the string tension of 5 kgf. Every bridge blank showed the behavior of primary creep stage(stress stabilization) having logarithmic regression creep curve with high correlation coefficient under the designed stress level. Even though the relationship between compressive creep and ray direction on the side edge of bridge was not so clear contrary to expectation, we could conclude that wood density and ray direction should be the quality decisive factors affecting the acoustical characteristics and performance of the bridge, the core member of violin-family bow instruments.