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태양광발전을 이용한 냉동.냉장창고용 냉수펌프의 에너지절감 기법
김대균,전기영,이상집,정춘병,이훈구,한경희,Kim, Dae-Gyun,Jeon, Kee-Young,Lee, Sang-Chip,Chung, Choon-Byeong,Lee, Hoon-Goo,Han, Kyung-Hee 한국조명전기설비학회 2005 조명·전기설비학회논문지 Vol.19 No.6
냉동 냉장창고용 냉수펌프 시스템을 태양광발전 시스템과 연계하여 펌프의 양정 및 유량의 변화에 따른 압력의 변화에도 불구하고 목표치 압력을 일정하게 제어할 수 있도록 하였다. BLDC 모터를 벡터제어 함으로써 각 운전속도의 영역에서 최대토크 운전 및 높은 신뢰성을 가능하도록 하여 냉동 냉장창고용 냉수 펌프 시스템의 에너지 절감 효과를 실현하였다. We are interaction refrigeration warehouse cold water pump system and photovoltaic generation system. At this time, a target pressure is able to control in spite of change of the pressure according to pump head and rate of flow of pump. Also, we carry out the vector control of BLDC motor with the maximum torque operation and a high reliability from territory of each operation speed. Therefore, in this paper, we conclude energy saving technique of refrigeration warehouse cold water pump system.
김대균,이윤동,Kim, Dae-Gyun,Lee, Yoon-Dong 한국통계학회 2011 응용통계연구 Vol.24 No.6
Since the research of Black and Scholes (1973), modeling methods using diffusion processes have performed principal roles in financial engineering. In modern financial theories, various types of diffusion processes were suggested and applied in real situations. An estimation of the model parameters is an indispensible step to analyze financial data using diffusion process models. Many estimation methods were suggested and their properties were investigated. This paper reviews the statistical properties of the, Euler approximation method, New Local Linearization(NLL) method, and Generalized Methods of Moment(GMM) that are known as the most practical methods. From the simulation study, we found the NLL and Euler methods performed better than GMM. GMM is frequently used to estimate the parameters because of its simplicity; however this paper shows the performance of GMM is poorer than the Euler approximation method or the NLL method that are even simpler than GMM. This paper shows the performance of the GMM is extremely poor especially when the parameters in diffusion coefficient are to be estimated. 현대금융공학에 있어서 확산모형은 중요한 역할을 담당하고 있다. 다양한 형태의 확산모형이 제안되어왔고 현실에 응용되어 왔다. 확산모형을 이용하여 금융자료를 분석하기 위하여는 확산모형의 모수를 추정하는 것이 필수불가결한 단계이다. 이들 모수에 대한 다양한 추정방법들이 제안되어 왔고, 많은 연구에서 이러한 추정방법들이 갖는 성질에 대하여 연구되어져왔다. 이 연구에서는 그 적용방법이 단순하여 가장 자주 사용되는 것으로 알려진, 오일러 근사법과 신국소근사법(NLL) 그리고 일반화 적률법(GMM)과 같은 세 가지 추정방법들에 대한 통계적 성질을 검토하게 될 것이다. 모의실험연구를 통하여 오일러근사법이나 NLL방법이 GMM 방법에 비하여 훨씬 좋은 성질을 가지고 있음을 보이게 된다. 특히 GMM은 적용방법이 단순할 뿐만 아니라 강건성(robustness)이라는 좋은 성질을 가지고 있는 것으로 알려져 있어서 많은 연구에서 매우 자주 사용되는 추정방법이다. 그러나 본 연구에서 확인해 본 바와 같이 GMM은 그 사용법이 오히려 더욱 단순한 NLL이나 오일러방법에 비하여 열등한 통계적 성질을 보여주고 있었다. 특히나 확산계수에 추정모수가 포함된 경우에 GMM은 매우 좋지 못한 성질을 보이게 된다.
회야댐 저수지에서 물리,화학적 환경요인에 따른 식물플랑크톤과 세균 군집의 변화
김대균 ( Kim Dae Gyun ),최애란 ( Choe Ae Lan ),이혜경 ( Lee Hye Gyeong ),권오섭 ( Kwon O Seob ),김종설 ( Kim Jong Seol ) 한국하천호수학회 2004 생태와 환경 Vol.37 No.1
We inverstigated the effect of physicochemical environmental factors on the community dynamics of phytoplanktons and bacteria at the Hoeya Dam Reservoir, a drinking water reservoir for Ulsan city. Water samples were collected and analyzed every two to four weeks at three sites alon the reservoir from April to October, 2001. During the study period, the Secchi depths were between 0.4 and 3.5m. At the surface layer of water column, temperature ranged 10.2∼32.0℃, pH 7.3∼9.6, dissolved oxygen 5.5∼12.4㎎L^(-1),BOD_(5)0.8∼5.0㎎L^(-1),COD_(Mn)3.7∼10.0㎎L^(-1),and Chl-a 8.9∼60.9㎎ m^(-3). At the bottom layer, tenperature varied 7.2∼28.9℃, pH 7.1∼9.3, dissolved oxygen 0.6∼9.7㎎L^(-1), BOD_(5)0.8∼4.5㎎L^(-1),COD_(Mn)3.9∼10.0㎎L^(-1),and Chl-a 4.3∼81.9㎎ m^(-3). The numbers of phytoplanktons were 7.4×10²∼2.6×10^(5) cells mL^(-1) at surface and 2.5×10²∼2.4×10⁴cells mL^(-1) at bottom, and were positively correlated with water temperature and Chl-a concentration. Genus Stephanodiscus and genus Oscillatoria dominated on April and on May, respectively. Cyanobacterial boolms of Aphanizomenon, Microcystis, Anabaena were observed from June to early Srptember, and thereagter Stephanodiscus and Aulacoseria dominated again. Total microbial counts tanged 1.73×10⁴∼1.68×10^(5) cells mL^(-1), and were positively correlated with water temperature and phytoplankton counts at surface water. Heterotrophic plate counts (HPCs) ranged 30∼4.1×10³CFU mL^(-1), and were positively correlated with BOD_(5) and NO₃^(-)-n concentration at bottom water. Unlike the total microbial counts, the numbers of fecal coliforms and fecal streptococci as well as HPCs were higher at the bottom than the surface layer and were highest at the upper a site among the three sampling sites. Since the concentrations of fecal coliforms and strsptococci were still high at the bottom of site c, where intake for water tratment plant is located, it appeared that special management of water treatment processed may be needed especially after strong rainfall.
김대균(Dae-Gyun Kim),전기영(Kee-Young Jeon),함년근(Nyun-Gun Hahm),이상집(Sang-Chip Lee),오봉환(Bong-Hwan Oh),정춘병(Choon-Byeong Chung),김용주(Yong-Joo Kim),한경희(Kyung-Hee Han) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-
The paper proposes the solar photovoltaic power generation system method for photovoltaic system to solve the power shortage due the sudden power demand. So that supplied electric power to system at appearance during surplus electric power minute and unit moment link driving with common use system is available, digital PLL circuit system voltage through composition and phase of solar photovoltatic power generation system to do synchronization do. Feed forward controller was applied to get fast current response. Solar cell that is changed by solar radiation always kept the maximum output when it used Step up chopper. The dynamic character had checked through simulation used Matlab Sumulink and confirmed through an experiment.