• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.365-374
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• 1998

The SHE(Selected Harmonic Elimination) PWM scheme which eliminates specific lower order harmonics can generate h high quality output waveforms in 3-level PWM inverters. However. its application has limited since SHE switching a angles cannot be calculated on-line by a microprocessor-implemented control system. Based on off-line optimization. in which multiple SHE solutions were found and analysed for 2 to 5 switching angles per quarter in the 3-level SHE PWM pattern. this paper presents an algebraic algorithm for an ordinary microprocessor to calculate approximate SHE S switching angles on-line with such high resolution that it makes no practical difference between the accurate and the a approximate SHE switching angles. By employing the variable of the dc-link voltage Vdc' the proposed SHE PWM p pattern can ideally compensate the dc input fluctuation together with selected harmonics eliminated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.753-763
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• 1989

The transient response of a three-dimensional straight fin of constant cross sectional area and perimeter with unequal top, bottom, left, right and tip surface convection coefficients is analyzed using separation variables and Laplace transforms when the fin base is subjected to a step change in temperature. The three-dimensional effects of fin dimensions and unequal fin surface convection coefficients on the fin performance which is expressed in terms of the heat flowrates through the fin base are investigated, and errors in one-dimensions and unequal fin surface coefficients. Typical results are represented in tabular and graphical forms.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.131-142
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• 1999

The general behavior of the curved girder including the warping effects can be presented as the series of differential equations developed by Vlasov. Generally, bending moment is the most important factor for engineer to decide the section of the girder. In order to accommodate easiness of the structural analysis for the curved girder bridge, this paper suggest the ratios of bending moment of curved gilder to that of straight girder. These ratios are presented by an approximate formula setting central angle ${\theta}(L/R)$ as a variable. The approximate formula of the maximum bending moment ratios and influence lines of all stress resultants can be used to design the three-span curved girder bridges.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2770-2773
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• 2002

본 논문은 지능형 안전 자동차(ASV)의 범주인 차선이탈경보 및 방지시스템에 적용을 위한 차선검출 알고리즘을 나타낸다. 그러기 위해서는 차선검출의 높은 신뢰도가 우선 되어야 한다. 대부분의 고속도로는 직선로와 곡선로로 이루어져있고, 곡선 도로는 차선을 검출하는데 여러 가지 제약이 있다. 본 논문에서는 곡선 차선의 직선 근사화를 통한 신뢰성 있는 차선 검출을 위해서 입력되는 연속영상의 효율적인 처리 기법을 제안하고자 한다.

• Computational Structural Engineering
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• v.5 no.1
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• pp.75-82
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• 1992

In the h-version of F.E.M., all piecewisely smooth curved boundaries can be approximated by a sufficient number of straight-sided elements. However, in the p-version the size of the element is usually large and hence the probability of distortions is more. An attempt has been made to generate a curved boundary by using a transfinite interpolation technique to avoid the discretization errors. In the following sections, it will be shown how to construct transfinite interpolants both in h-version and in p-version over polygonal and nonpolygonal regions. Three numerical tests are shown to validate the applicability and superior capability of transfinite interpolation technique.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.7-14
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• 1983

Linear feature such as lines and curves are one of important features in image processing. In this paper, new method of linear feature detection is suggested. Also, we have studied approximation technique which transforms detected linear feature into data structure for the practical. This method is based on graph theory and principle of this method is based on minimal spanning tree concept which is widely used in edge linking process. By postprocessing, Hairs and inconsistent line segments are removed. To approximate and describe traced linear feature, piecewise linear approximation is adapted. The algorithm is demonstrated through computer simulations.

• The Journal of the Korea Contents Association
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• v.15 no.5
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• pp.436-443
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• 2015

The purpose of this study was to develop a self-diagnostic linearity quality control techniques of computed tomography (CT) by using measured CT number values from the various concentrations of iodine contrast media (CM) is diluted with distilled water under each condition of the tube voltage. The equipment was used for four-channel MDCT, the iodine concentration were using 300 mgI/ml, 350 mgI/ml, 370 mgI/ml and 400mgI/ml. Dilution of CM in distilled water was increased by each 5% until the maximum CT number values were measured. We applied the tube voltages for 90 kVp, 120 kVp, 140 kVp. As a result, we was obtained to the nearest linearity as 0.993 of correlation coefficient between the iodinated CM from 5% to 25% in 400 mgI/ml and the CT number values by 90 kVp. In conclusion, the proposed self-diagnostic linearity quality assurance technique by using iodine CM can be utilized to replace the AAPM CT performance phantom.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.302-315
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• 2018

Highly non-linear electro-optical transfer function of the Perceptual Quantizer was approximated by a truncated Taylor series, resulting in a closed form solution for luma adjustment. This previous solution is fast and quite suitable for the hardware implementation of luma adjustment, but the approximation error becomes relatively large in the range of 600~3,900 cd/m2 linear light. In order to reduce such approximation error, we propose a new linear model, for which a correction is performed on the position and the slope of line based on the scope of approximation. In order to verify the approximation capability of the proposed linear model, a comparative study on the luma adjustment schemes was conducted using various high dynamic range test video sequences. Via the comparative study, we identified a significant performance enhancement over the previous fast luma adjustment scheme, where a 4.65dB of adjusted luma t-PSNR gain was obtained for a test sequence having a large portion of saturated color pixels.

• Journal of KIISE:Software and Applications
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• v.28 no.7
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• pp.511-523
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• 2001

필기 한글의 문자나 단어 인식에 있어 패턴을 구성하는 획 성분을 추출하는 작업은 매우 중요하다. 세선화와 직선근사에 기반한 고전적인 방법은 원래 패턴을 크게 왜곡한다는 단점을 가지고 있다. 우리는 이러한 문제점을 해결하기 위하여 한글 패턴에 적합한 모양 분해 알고리즘을 제안한다. 한글 패턴은 T-접점과 B-접점이라는 두가지 모양 특징을 중심으로 분할할 수 있다고 관찰에 근거하여 알고리즘을 설계하였다. 또한 세 개 이상의 획이 복잡한 형태로 만나는 결합 지점을 강전하게 처리하는 방법도 제시한다. 제안한 알고리즘을 PE92 데이터베이스에 적용한 결과를 제시한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.81-84
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• 2002

최근, 사회의 요구의 다양성, 고도화에 동반하여 지도정보 시스템에 대한 수요가 증가하고 있다. 이 시스템을 구축할 때, 지도 중에서 각 선도형이 갖는 방대한 데이터를 어떻게 압축하여 시스템에 입력하여, 축적할까하는 것이 문제가 된다. 자동차의 네비게이션 등에 이용하는 도로지도에 한해서는, 도로의 접속관계만 유지된다면, 원래의 도로지도와 다소 차이가 있다고 하여도 충분히 유효하다. 본 연구에서는 이 네비게이션을 목적으로 한, 시가지의 도로망 지도에 대하여, 특징점 추출과 직선 근사를 이용한 데이터 압축법을 제안한다.