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지하수위 시계열 예측 모델 기반 하천수위 영향 필터링 기법 개발 및 지하수 함양률 산정 연구
윤희성,박은규,김규범,하규철,윤필선,이승현,Yoon, Heesung,Park, Eungyu,Kim, Gyoo-Bum,Ha, Kyoochul,Yoon, Pilsun,Lee, Seung-Hyun 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.3
A method to filter out the effect of river stage fluctuations on groundwater level was designed using an artificial neural network-based time series model of groundwater level prediction. The designed method was applied to daily groundwater level data near the Gangjeong-Koryeong Barrage in the Nakdong river. Direct prediction time series models were successfully developed for both cases of before and after the barrage construction using past measurement data of rainfall, river stage, and groundwater level as inputs. The correlation coefficient values between observed and predicted data were over 0.97. Using the time series models the effect of river stage on groundwater level data was filtered out by setting a constant value for river stage inputs. The filtered data were applied to the hybrid water table fluctuation method in order to estimate the groundwater recharge. The calculated ratios of groundwater recharge to precipitation before and after the barrage construction were 11.0% and 4.3%, respectively. It is expected that the proposed method can be a useful tool for groundwater level prediction and recharge estimation in the riverside area.
삼상 몰드변압기의 T-joint 형상에 따른 철손의 비교
윤희성(Heesung Yoon),신판석(Pan Seok Shin),고창섭(Chang Seop Koh) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.10
본 논문에서는 삼상 몰드 변압기의 T-joint 형상이 변압기의 무부하 철손에 미치는 영향을 알아보고자 하며, 이를 위해 3가지 종류의 T-joint 형상을 비교 하였다. 변압기 코어에서 발생하는 교번자계와 회전자계 특성을 정확히 표현하기 위해 Chua-type vector hysteresis model을 전기강판의 자가 특성 모델링에 적용하였으며, 이를 유한요소법과 결합하여 3MVA급 삼상 몰드 변압기의 자계 해석 및 철손 해석에 적용하였다.
열전냉각방식을 적용한 냉각시스템의 성능개선에 관한 연구
윤희성(Heesung Yoon),오율권(Yoolkwon Oh) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
This study investigated on performance improvement of cooling system applying thermoelectric cooling. Cooling system consisted of thermoelectric module, heat sink, cooling fan and heat insulator. The experimental apparatus for temperature distribution measurement consisted T-type thermocouples and data acquisition unit. To investigate on performance improvement of cooling system, thermoelectric module was applied 1, 2 and 3, respectively. Cooling effect was calculated in respective measurement temperature result of cooling system. The experimental result of the temperature distributions provided that the cooling effect of cooling system was improved when two thermoelectric modules were applied. As a result, it was certified that the more the number of thermoelectric module was increased, the more performance of cooling system was improved.
전기강판의 벡터 자기특성을 고려한 전기기기의 손실특성 해석
윤희성(Heesung Yoon),고창섭(Chang Seop Koh) 대한전기학회 2012 전기학회논문지 Vol.61 No.12
This paper presents vector magnetic properties of an electrical steel sheet (ESS) employed for electric machine and iron loss analysis considering the vector magnetic properties of the ESS. The vector magnetic properties of the ESS are measured by using a two-dimensional single sheet tester and modeled by an E&S vector hysteresis model to be applied to finite element method. The finite element analysis considering the vector magnetic properties is applied to iron loss analysis of a three-phase induction motor model, and the influences of the vector magnetic properties on the iron loss distribution are verified by comparing with numerical results from a typical B-H curve model.
윤희성(Heesung Yoon),오율권(Yoolkwon Oh) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
This study investigated on cooling characteristics in cooling region when the acoustic streaming was generated. In this study, piezoelectric actuator was used for generating acoustic streaming in cooling region of thermoelectric cooling device. When the acoustic streaming was generated by the piezoelectric actuator, temperature distribution was measured using thermocouples for investigating cooling characteristics in the cooling region of thermoelectric cooling device. Also, He-Ne laser and CCD camera were used for thermo-flow visualization in the cooling region. The experimental set-up for temperature measurement and the thermo-flow visualization in the cooling region consisted of thermoelectric module, piezoelectric actuator, thermocouples, data acquisition units, He-Ne laser, CCD camera, image grabber and PC. As a result, it was certified that the piezoelectric actuator generated the acoustic streaming, and the cooling effect in the cooling region was improved when the acoustic streaming was generated.
시간차분 유한요소법을 이용한 대용량 삼상 변압기의 정상상태 해석에 관한 연구
윤희성(Heesung Yoon),서민규(Min Kyu Seo),고창섭(Chang Seop Koh) 대한전기학회 2012 전기학회논문지 Vol.61 No.8
This paper presents the fast steady state analysis using time-stepping finite element method for a high power three-phase transformer. The high power transformer spends huge computational cost of the time-stepping finite element method. It is because that the high power transformer requires a lot of time to reach steady state by its large inductance component. In order to reduce computational cost, in this paper, the adaptive time-step control algorithm combined with the embedded 2nd 4th singly diagonally implicit Runge-Kutta method and the analysis strategy using variation of the winding resistance are studied, and their numerical results are compared with those from the typical time-stepping finite element method.
전압원 문제 해석을 위한 Singly Diagonally Implicit Runge-Kutta법을 이용한 적응 시간차분 유한요소 해석
윤희성(Heesung Yoon),고창섭(Chang Seop Koh) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.10
본 논문애서는 전압원 문제의 정확한 해석을 위해 적응 시간차분 유한요소 해석법에 대해 소개한다. 이 방법에서 전압원 해석시 고려되는 미분 대수방정식은 Singly diagonally implicit Runge-Kutta법을 이용하여 표현된다. 이 해석 방법은 단상 변압기 모델의 전압원 해석에 적용되며, 해석 방법의 타당성 검증을 위해 통상적으로 사용되는 θ-method에 의한 해석 결과와 비교된다.
열전냉각시스템 냉각영역의 성능개선을 위한 압전구동기 적용에 관한 연구
윤희성(Heesung Yoon),최제세(Jese Choi),오율권(Yoolkwon Oh) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
This study investigated on performance improvement of cooling region in thermoelectric cooling system when piezoelectric actuator was applied. In this study, piezoelectric actuator was used for generating vibration in cooling region of thermoelectric cooling system. When vibration was generated by the piezoelectric actuator, temperature distribution was measured using thermocouples for investigating cooling characteristics in cooling region of thermoelectric cooling system. Also, He-Ne laser and CCD camera were used for flow visualization in cooling region. The experimental set-up for temperature measurement and the flow visualization in cooling region consisted of thermoelectric cooling system, piezoelectric actuator, thermocouples, data acquisition units, He-Ne laser, CCD camera, image grabber and PC. As a result, it was certified that vibration of piezoelectric actuator generated forced convection, and the cooling efficiency in the cooling region was improved when piezoelectric actuator was applied.