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Zig-Zag 귄선에 의한 내철형 주상변압기 개발에 관한 연구
민윤홍,신대철,Min, Yun-Hong,Shin, Dae-Chul 한국조명전기설비학회 2007 조명·전기설비학회논문지 Vol.21 No.8
본 논문에서는 세계최초로 내철형 주상변압기 코일의 권선을 일반적인 권선방법에서 Zig-Zag(가칭) 권선방법으로 설계 제작하는 방법을 제안하였으며, 또한 바니시 함침공정을 생략하고 단락강도 및 절연내력을 향상시킬 수 있는 내철형 변압기용 권선의 신프레임 구조개발 내용을 제안하였다. 기존의 주상변압기 권선방법에 비하여 전기절연 측면에서 층간 절연지의 사용매수 및 두께를 획기적으로 절감할 수 있는 장점이 있다. 또한 원가절감과 손실저감 및 단락기계력 대처능력이 우수함을 검증하였으며 국내전력회사 배전계통 주상변압기에 유용하게 활용할 수 있다. In this thesis, we would show how to lay out and produce the shell-type transformer using the world's first Zig-Zag winding way, instead of a general winding. Also, we omit the progress of varnish-impregnation, so that we could develop the new shell-type transformer winding which improves the short-circuit characteristics and dielectric strength. It has a copernican effect to reduce the thickness and the number of insulation papers, as compared with a general winding transformer. We would prove that it is far superior in cost reduction, loss reduction, and mechanical force of short-circuit. And eventually you must find it useful in the pole transformer for power distribution in the domestic power companies.
혼합절연을 이용한 초저손실급 주상변압기 개발에 관한 연구
민윤홍,신대철,Min, Yun-Hong,Shin, Dae-Chul 한국조명전기설비학회 2007 조명·전기설비학회논문지 Vol.21 No.7
주상변압기는 고객에게 직접 전력을 공급하는 설비로서 전력공급의 안정성확보를 위한 중요한 기자재 중 하나이다. 하지만 제조결함에 의한 3년 이내의 초기고장 또는 13년이 초과 사용한 후의 열화고장이 빈번히 발생하고 있어 변압기 품질분석을 통한 신뢰성이 개선된 주상변압기 개발이 필요하다. 본 논문에서는 열적, 기계적, 전기적으로 성능이 향상된 새로운 모델의 혼합절연 주상변압기를 개발하였다. 변압기의 기계적, 열적특성을 향상시키기 위한 혼합절연 방식에 대한 설계 및 제작방법을 제시하고 과부하시험을 시행하여 순간최대부하에 대응할 수 있도록 과부하내량 160[%] 까지 증가시킬 수 있음을 확인하였다. 또한 본 논문에서는 100[kVA] 1대를 시제품으로 제작하여 단락강도시험과 변압기 관련 절연시험을 시행하여 전자기계력의 분석과 단락강도설계 향상 방안에 대하여 설명하고 이와 관련하여 연구한 결과에 대해 논하였다. The pole transformer is one of the most important facility to insure the stability of electric power supply. which distributes electricity to customers directly. However there are a lot of defects which are caused by manufacturing fails(in 3 years) or deterioration (in 13 years), so we need a more improved transformer which insures quality. This thesis talks about the development of the new-type transformer using the hybrid insulation that is durable thermally, mechanically, and electrically. It would show how to lay out and produce the transformer using the hybrid insulation. And finally we are sure that we could increase the utilization rate of a transformer by 160% as compared with its own capacity through the overload test. Also, we carried out the examination about the short-circuit and insulation with a 100[kVA] model transformer, so that we expound the analysis of magnetic-mechanical forces intensity and the measure for improving short-circuit efficiency.
민윤홍(Yunhong Min) 한국컴퓨터정보학회 2018 韓國컴퓨터情報學會論文誌 Vol.23 No.5
For an efficient management of electricity market and power systems, accurate forecasts for electricity demand are essential. Since there are many factors, either known or unknown, determining the realized loads, it is difficult to forecast the demands with the past time series only. In this paper we perform a cluster analysis on electricity demand data collected from Jan. 2000 to Dec. 2017. Our purpose of clustering on electricity demand data is that each cluster is expected to consist of data whose latent variables are same or similar values. Then, if properly clustered, it is possible to develop an accurate forecasting model for each cluster separately. To validate the feasibility of this approach for building better forecasting models, we clustered data with t-SNE. To apply t-SNE to time series data effectively, we adopt the dynamic time warping as a similarity measure. From the result of experiments, we found that several clusters are well observed and each cluster can be interpreted as a mix of well-known factors such as trends, seasonality and holiday effects and other unknown factors. These findings can motivate the approaches which build forecasting models with respect to each cluster independently.
LES 및 음향상사 모델을 이용한 에어컨 실내기의 공력 소음원에 대한 수치해석적 연구
민윤홍(Yunhong Min),강성원(Seongwon Kang),허남건(Nahmgeon Hur),박정택(Jeongtaek Park) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In the present study, the aerodynamic noise source was analyzed for air-conditioner indoor unit. The 3-D LES was used because the noise prediction using acoustic analogy method requires the accurate flow result in a vicinity of noise source. For 3-D computation, the sound correction method which is derived by Kato was used to take account of longer span length. Since the quadrupole contribution is negligible in subsonic flow of air-conditioner indoor unit, the Farassat formulation 1A which considers only monopole and dipole source was applied to predict far-field acoustic pressure. In air-conditioner indoor unit, the three noise sources are blade and two fan casings. The predicted SPL (Sound Pressure Level) using the three noise sources was good agreement with the experimental data. When the separated vortex interacts with each noise source, the pressure fluctuation on the surfaces causes the main noise in subsonic flow. Especially the blade was dominant source because there were the most active form of interaction between blades and vortex. Also the blade had the effect of BPF (Blade Passing Frequency) peak noise as the specific flow structures in the cross-flow fan.
민윤홍(Yun-Hong Min),정예림(Yerim Chung) 한국컴퓨터정보학회 2016 韓國컴퓨터情報學會論文誌 Vol.21 No.9
In this paper we consider the problem of finding the triplet (S, π, f,) where S ⊆ V, πis a sequence of nodes in S and f :V ╲S →S for a given complete graph G = . In particular, there exist two costs, c u v <SUP>V</SUP> and c u v <SUP>D</SUP> for (u, v) ∊ E, and the cost of triplet (S,π, f)is defined as [수식 기호 본문 참조] . This problem is motivated by the integrated routing of the vehicle and drone for urban delivery services. Since a well-known NP-complete TSP (Traveling Salesman Problem) is a special case of our problem, we cannot expect to have any polynomial-time algorithm unless P=NP. Furthermore, for practical purposes, we may not rely on time-exhaustive enumeration method such as branch-and-bound and branch-and-cut. This paper suggests the simple heuristic which is motivated by the MST (minimum spanning tree)-based approximation algorithm and neighborhood search heuristic for TSP.
에어컨 실내기의 공력소음 예측을 위한 RANS 난류모델의 성능 평가
민윤홍(Y.H. Min),강성원(S. Kang),허남건(N. Hur),이창훈(C. Lee),박정택(J. Park) 한국전산유체공학회 2012 한국전산유체공학회지 Vol.17 No.4
The objective of the present study is to investigate the effects of various turbulence models on the aerodynamic noise of an air-conditioner (AC) indoor unit. The results from URANS (unsteady Reynolds-averaged Navier-Stokes) simulations with the standard k-ε, k-ω shear stress transport (SST) and Spalart-Allmaras (S-A) turbulence models were analyzed and compared with the noise data from the experiments. The frequency spectra of the far-field acoustic pressure were computed using the Farrasat equation derived from the Ffowcs Williams-Hawkings (FW-H) equation based on the acoustic analogy model. Two fixed fan casings and the rotating cross-flow fan were used as the source surfaces of the dipole noise in the Farrasat equation. The result with the standard k-ε model showed a much better agreement with the experimental data compared to the k-w SST and S-A models. The differences in the pressure spectra from the different turbulence models were discussed based on the instantaneous vorticity fields. It was found that the over-estimated power spectra with the k-w SST and S-A models are related to the emphasized small-scale vortices produced with these models.