• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.71.1-71.1
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• 2014

To investigate physical properties of Solar pores, we use SDO/HMI data from 2010 to 2013. For this, we select single and isolated pores from the active region (Axx, Bxo, Bxi and Bxc-type) listed in Solar Region Summary. Pore is defined by connected pixels satisfying the intensity threshold from pixel of minimum intensity. We try to obtain area, intensity, magnetic field, and Doppler velocity of pores from HMI data. After removing the effects of orbital motion of the SDO satellite and differential rotation of the Sun, we identify that significant daily variations of Doppler velocity with non-zero ordinates still remain in the umbral region, and the artifact is quite dependent on the strength of magnetic field and radial component of velocity of SDO satellite. In this study we develope empirical model to remove the artifact. A preliminary result on the elimination of the artifact will be presented.

• Journal of Power Electronics
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• v.3 no.3
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• pp.151-158
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• 2003

Three-phase four-wire electrical distribution systems are widely employed in manufacturing plants, commercial and residential buildings Due to the nonlinear loads connected to the distribution system, the neutral conductor carries excessive harmonic currents even under balanced loading since the triplen harmonics in phase currents do not cancel each other This may result in wiring failure of the neutral conductor and overloading of the distribution transformer In response to these concerns, a cost-effective neutral current harmonic suppressor system has been proposed. This paper proposes an improved control method for the harmonic suppressor system under unbalanced load conditions The proposed control method compensates for only the harmonic components in the neutral conductor, and the zero-sequence fundamental component due to unbalanced loading is prevented from flowing through the harmonic suppressor system This remedies overloading and power loss of the system The experimental results on a prototype validate the proposed control approach.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.1002-1005
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• 1995

This paper presents an enhanced preprocessing and recognition algorithm for automatic vehicle license plate recognition system. The algorithm first applies horizontal gradient filter followed by thresholding and mathematical morphology operation for preprocessing. The final stage of the preprocessing is the application of connected component analysis in order to estimate the license plate region. For the recognition of the serial numbers of the plates, we developed a very effective algorithm. We call this zerocrossing count algorithm. This paper presents a detail of this algorithm and compare the performance with a template matching algorithm which utilizes correlation coefficient.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.105-111
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• 2016

Trust models in the literature of MANETs commonly assume that packets have different security requirements. Before a node forwards a packet, if the recipient's trust level does not meet the packet's requirement level, then the recipient must perform certain security association procedures, such as re-authentication. We present in this paper an analysis of the epidemic broadcast delay in such context. The network, mobility and trust models presented in this paper are quite generic and allow us to obtain the delay component induced only by the security associations along a path. Numerical results obtained by simulations also confirm the accuracy of the analysis. In particular, we can observe from both simulation's and analysis results that, for large and sparsely connected networks, the delay caused by security associations is very small compared to the total delay of a packet. This also means that parameters like network density and nodes' velocity, rather than any trust model parameter, have more impact on the overall delay.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.143-151
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• 2008

This paper presents the operation of Fuel Cell Distributed Generation(FCDG) systems in distribution systems. Hence, modeling, controller design, and simulation study of a Solid Oxide Fuel Cell(SOFC) distributed generation(DG) system are investigated. The physical model of the fuel cell stack and dynamic models of power conditioning units are described. Then, suitable control architecture based on fuzzy logic and the neural network for the overall system is presented in order to activate power control and power quality improvement. A MATLAB/Simulink simulation model is developed for the SOFC DG system by combining the individual component models and the controllers designed for the power conditioning units. Simulation results are given to show the overall system performance including active power control and voltage regulation capability of the distribution system.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.11a
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• pp.85-88
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• 2006

본 논문에서는 강의 영상에 포함되어 있는 텍스트 정보를 바탕으로 학습에 의미 있는 영역을 추출한다. 실시간으로 입력되는 컬러 영상에서 Canny 연산자를 이용하여 에지 정보를 구하고, 모폴로지 연산(Morphological Operation)과 연결 성분(Connected Component)을 통해 후보 영역을 검색한다. 그리고 검색된 후보 영역내의 색 정보 분석을 통해서 의미 있는 학습 영역을 추출하였다. 본 논문에서 제안한 학습에 의미 있는 영역을 추출한 결과, 비교적 단순한 강의 영상과 복잡한 강의 영상 모두에서 정확한 학습 영역의 추출이 가능함을 알 수 있고, 학습에 의미 있는 정보만을 구성함으로써 적은 용량으로 최적화된 강의 영상을 제공할 수 있음을 확인할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.805-808
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• 2001

본 논문은 비디오 영상에서 내용 기반 검색을 위한 비디오 텍스트를 검출하는 방법을 제안한다. 영어와 달리 한글과 같이 다중 분할된 문자가 포함된 비디오 텍스트를 자동으로 검출하기 위해 형태와 크기 및 위치 정보를 이용하고 이러한 정보들은 K-mean 클러스트링 알고리즘을 이용해 얻어진 템플릿의 형태로 표현 된다. 연결 성분 분석(connected component analysis)방법을 통해 비디오 영상을 분할하고, 잡음을 제거한 후 정확한 문자 성분을 검출하기 위해 클러스터 기반의 템플릿 매칭을 한다. 제안된 방법은 정확도와 에러율에서 기존의 방법보다 효과적 이었다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.45-48
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• 2000

A typical map image is consisted of number, symbols and lines that represent contour lines, geographical bounaries, roads, rivers and etc. This paper describe the separation. The separation algorithm is based on structural relation. The separation of proposed method is better than method using only a size of connected component. This proposed method will be used in GIS input system efficiently.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1353-1355
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• 2003

Total six units of 3kW photovoltaic (PV) system and data acquisition system (DAS) are constructed for analyzing performance of PV system at field demonstration test center of Gwang-Ju in Korea. As climatic and irradiation conditions are varied, operation characteristics of the PV system are collected and analyzed in data-acquisition system. Furthermore, not only performance test of each PV system component such as PV module and power conditioning system, but also performance of total PV system e.g. system efficiency, electric power and loss factor at the site are reviewed.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.357-362
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• 1996

A way of quantitatively describing the tissue architecture we have investigated when developing a computer program for malignancy grading of transitional cell bladder carcinoma. The minimum spanning trees, MST was created by connecting the center points of the nuclei in the tissue section image. These nuclei were found by thresholding the image at an automatically determined threshold followed by a connected component labeling and a watershed algorithm for separation of overlapping nuclei. Clusters were defined in the MST by thresholding the edge lengths. For these clusters geometric and densitometric features were measures. These features were compared by multivariate statistical methods to the subjective grading by the pathologists and the resulting correspondence was 85% on a material of 40 samples.