• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1992.10a
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• pp.25-30
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• 1992

최근 전자계산기를 이용한 진동해석 방법이 눈부시게 발달하여, 일반 구조물 이나 기계 구조물 등의 동특성을 설계 단계에서 정도 높게 예측하는 것이 가능하게 되었다. 그러나 종래의 구조해석은 주어진 시스템의 동특성을 위한 것으로 얻어진 동특성으로부터 질량, 관성제원 및 스프링상수값 등의 설계상 수값을 규명하는 연구는 미미한 실정이다. 이것에 대한 해결방법으로 크게 해석적인 방법과 실험적인 방법으로의 접근이 있어 왔다. 해석적인 방법으로 유한요소해석에서 얻은 모드좌표를 물리좌표로 변환하는 방법으로 Guyan의 정축소와 같은 절점축소를 행하는 방법이 고찰되었다. 실험적인 방법으로 가 진실험에서 얻은 전달함수나 모드파라미터로부터 [M], [K] 행렬을 결정하는 연구가 있었지만 어떤것도 질량, 스프링상수 등의 설계상수를 완전히 규명하 지는 못하였다. 또한, 설계 단계에서 필요한 질량, 관성제원 또는 스프링상수 등의 최적한 값이나, 원하는 시스템특성을 얻을 수 있는 설계상수의 적정한 폭을 구하는 연구는 설계자의 경험과 반복된 시행착오에 의존하는 실정이다. 감도해석은 이러한 문제점을 개선하는 수단으로 설계변수에 대한 동특성의 변화율을 구하는 것이다. 감도해석을 수행하는 것은 어느 설계변수를 수정하 는 것이 주어진 동특성에 부합되는 지를 알려주고, 어느 것을 수정하는 것이 원하는 방향의 동특성변화에 가장 효과적인지를 알려주는 것이다. 따라서 감 도해석을 이용하여 설계의 최적화 프로그램을 만들수 있고, 이것은 설계자가 요구하는 동특성을 목적함수로 하여 주어진 구조물을 최적화하는 설계상수 값을 얻을 수 있게 한다. 본 논문에서는 강체모델의 동특성으로부터 모델의 설계 상수를 규명하고, 동특성의 개선을 위하여 설계변수의 변경량을 물리좌 표계에서 얻는것을 목적으로 한다. 강체 마운트계의 관성제원 및 마운트강성 의 규명을 위하여 임으로 주어진 설계상수를 모델데이타로 하여 관성제원과 스프링 강성을 구하였다. 관성제원의 규명은 주어진 모델의 관성값을 모르는 것으로 하여 임의의 초기 관성값으로 감도해석에 의해 주어진 계의 관성값 을 물리 좌표계에서 규명하였다. 마운트 강성의 규명도 관성제원의 규명과 같은 방법으로 임의의 강성값으로 감도해석을 하여 강성값을 규명하였다. 또 한 감도해석에 의한 동특성 변경은 특정한 고유진동 수의 변경이 필요할 때, 고유진동수의 이동을 위한 관성제원의 변경 및 마운트 강성변경값을 예측할 수 있다. 본 연구수행의 기본적인 흐름도는 Fig.1.1과 같다. 위와 같은 작업 으로 엔진 마운트와 같은 강체 모델의 시스템 규명을 행하는 경우에 유한요 소해석 및 가진 실험으로 얻은 고유진동수의 정보 또는 원하는 고유진동수 의 특성을 기본으로 실제 설계에서 사용이 가능하도록 물리 좌표계에서 관 성 제원 및 스프링상수를 구할 수 있을 것이다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.113-120
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• 2005

3D reconstruction of a scene structure from un-calibrated image sequences has been long one of the central problems in computer vision. For 3D reconstruction in Euclidean space, projective reconstruction, which is classified into the merging method and the factorization, is needed as a preceding step. By calculating all camera projection matrices and structures at the same time, the factorization method suffers less from dia and error accumulation than the merging. However, the factorization is hard to analyze precisely long sequences because it is based on the assumption that all correspondences must remain in all views from the first frame to the last. This paper presents a new projective reconstruction method for recovery of 3D structure over long sequences. We break a full sequence into sub-sequences based on a quantitative measure considering the number of matching points between frames, the homography error, and the distribution of matching points on the frame. All of the projective reconstructions of sub-sequences are registered into the same coordinate frame for a complete description of the scene. no experimental results showed that the proposed method can recover more precise 3D structure than the merging method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.5
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• pp.277-283
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• 2016

Tetrapod is one of the most widely used concrete armor units for rubble mound breakwaters. The calculation of the stability number of Tetrapods is necessary to determine the optimal weight of Tetrapods. Many empirical formulas have been developed to calculate the stability number of Tetrapods, from the Hudson formula in 1950s to the recent one developed by Suh and Kang. They were developed by using the regression analysis to determine the coefficients of an assumed formula using the experimental data. Recently, software engineering (or machine learning) methods are introduced as a large amount of experimental data becomes available, e.g. artificial neural network (ANN) models for rock armors. However, these methods are seldom used probably because they did not significantly improve the accuracy compared with the empirical formula and/or the engineers are not familiar with them. In this study, we propose an explicit method to calculate the stability number of Tetrapods using the weights and biases of an ANN model. This method can be used by an engineer who has basic knowledge of matrix operation without requiring knowledge of ANN, and it is more accurate than previous empirical formulas.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.183-192
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• 2003

A transformation methode of the chromaticity coordinates was proposed to calibrate the measured data obtained by a urine analysis system which implemented in our previous study. Generally. the reacted color of a reagent strip by urine analysis system often exhibit the color distortions due to nonlinear characteristics of the various devices that is the optic module mechanism. hardware, and surround circumstance. A color correction method for minimizing the color distortion play a few role in maintaining high accuracy and reproduction of the urine analysis system. In this work, we used the compensation method such as the shading correction, the characteristic curve extraction of RGB color by means of third order spline interpolation, and linear transformation using a reference color. In addition, 1931 CIE XYZ color space was used to compensate the color of the measured data by a standard reference system as colorimeter. A compensation matrix was obtained so that the output values of the urine analysis system is nearly equal to that of a standard reference system for identical color sample. Color correction obtained by a urine analysis system which implemented in our previous study exhibited a good color accuracy when it was compared with the reference data. Observed result from an experiments on ten items or a urinalysis strip that color difference or between two urine analysis system was 1.28.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.51-56
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• 2008

The waveform inversion for isotropic media has ever been studied since the 1980s, but there has been few studies for anisotropic media. We present a seismic waveform inversion algorithm for 2-D heterogeneous transversely isotropic structures. A cell-based finite difference algorithm for anisotropic media in time domain is adopted. The steepest descent during the non-linear iterative inversion approach is obtained by backpropagating residual errors using a reverse time migration technique. For scaling the gradient of a misfit function, we use the pseudo Hessian matrix which is assumed to neglect the zero-lag auto-correlation terms of impulse responses in the approximate Hessian matrix of the Gauss-Newton method. We demonstrate the use of these waveform inversion algorithm by applying them to a two layer model and the anisotropic Marmousi model data. With numerical examples, we show that it's difficult to converge to the true model when we assumed that anisotropic media are isotropic. Therefore, it is expected that our waveform inversion algorithm for anisotropic media is adequate to interpret real seismic exploration data.

• The Magazine of the IEIE
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• v.11 no.5
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• pp.42-50
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• 1984

국내의 다음세대 컴퓨터 개발을 위한 VLSI 설계와 CAD 분야에 대한 연구 방향을 제시한다. 연구의 목표는 국제적으로 경쟁할 수 있는 VLSI 설계능력과 백만개 정도의 트랜지스터로 자성된 회로를 경제적으로 설계하기 위한 CAD 기술과 System의 확립이다. ·새로운 회로 구조와 알고리즘에 대한 연구 · CAD 도구와 언어의 개발에 관한 첨단 CAD 기술개발연구 · VLSI 설계에 필요한 CAD 도구 이용과 개발에 필요한 표준 인터페이스, 네트워킹, 컴퓨팅 하드웨어. 시스템 소프트웨어에 대한 연구등의 부분으로 크게 나눌 수 있다. 이용 가능한 CAD system을 평가하고 개선하며 첨단 CAD에 대한 소프트웨어와 하드웨어에 대해 · 컴퓨팅 하드웨어 · 프로그램 분위기 · 네트워킹 능력 ·자료 교환을 위한 표준인터페이스 등에 관해 조사분석도 병행한다. CAD에 관한 세부적인 연구 과제는 · 시스템 사양언어 · 설계 검증 ·시스템시뮬레이션· 설계 합성 · 설계 해석· 설계 방법론·디바이스와 공정 모델링 프로그램 등이다. 고속 계산용 VLSI에 관한 구조와 알고리즘은 행렬 계산을 위한 ·분산 배열 처리 회로 ·시스토릭 (Systolic) 배열 회로 ·셀률라(Cellular) 논리 회로 · 3차원 배열 회로 와 · 비규칙적 계산 알고리즘을 갖는 VLSI가 있다. VLSI설계훈련과 CAD 기술 축적을 위해 CAD enter를 설립하여 전국적인 CAD 네트워킹을 관계 연구소와 여러 대학에 가설하며, MPC 계획을 추진한다. VLSI설계 가능성이 입증되면 VLSI 설계능력을 더욱 향상 시키기 위해 0.5∼1.0mm기술의 silicon faundary를 설립한다. 연구 개발 조직은 대학, 산업체. 연구소가 삼위일체가 되어 수행될 수 있도록 연구 개발 위원회를 설치 운영하며 경쟁적이며 경제적으로 연구 업무를 집행하는 것이 바람직하다.았다.형질에 관여하는 귀전자에 미치는 기구에 대하여 검토할 여타가 있다고 보여진다. 분해능의 특징으로 미루어 앞으로는 레이저를 이용한 계측 방법이 그 주류를 이룰 것으로 사료된다. 우선 본 해설은 기체의 온도 및 농도의 광학적 측정방법중 Raman산란광 검출법에 대하여 실제로 측정하는 입장에서 간단히 소개한다.lity)이, 높은 $GA_3$함량에 기인된다'는 주장은 본실험(本實驗)으로 부인(否認)되었다. 따라서, 응용학적(應用學的) 측면에서 고려해 볼 때, 리베스식물(植物)의 육종기간 단축을 위한 모든 화아분화(花芽分化) 촉진 조치는 P.J.-식물(植物)이 20. node이상 생육하였을 때 취하는 것이 효율적인 것으로 결론 지어진다.앞당겨진 7月 셋째 週였다. 8. Culex (Culex) tritaeniorhynchus summoro년의 最大發生 peak는 1981年, 1982年 모두 8月 둘째 週였다. 9. Anopheles (Anopheles) sinensis의 最大發生 peak는 1981年에 7月 다섯째 週, 1982年은 2週 앞당겨진 7月 셋째 週였다. 10. 重要 3種의 最大 peak를 比城하면 Culex (Culex) pipiens pallens와 Anopheles (Anopheles) sinensis는 1981年과 1982年 모두 最大 peak時期가 同一하였으며, Culex (Culex) tritaeniorhynchus summoro년는 2年間 모두 8月둘째 週에 나타났다.osterior to manubrium and anterior to aortic arch) replacing the normal mediastinal fat. (2) In benign thymoma, the marging of the mass was smooth and the normal fat

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.4 s.310
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• pp.9-18
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• 2006

In the digital camera system, CMOS image sensor (CIS) is widely used because its size and weight become smaller and power consumption becomes lower. However, there are common problems that colors of the recorded image do not match those of the photographed object and that spectral sensitivity of the CIS used in different cameras varies largely in each case. Therefore, color correction is needed because the spectral sensitivity of the CIS in each color is neither the same color component for most standard colors nor the appropriate color representation for any output devices. In the conventional method, a color correction is empirically obtained by a large number of iterative experiments, but the result is not so satisfied. In this paper, a new method to obtain the efficient color correction matrix for digital camera using CIS is proposed. We obtain camera transfer matrix under the certain white-balance point, and color correction matrix that makes the transfer characteristic of digital camera close to the transfer characteristic of ideal camera is obtained. The experimental results show that the transfer characteristic of digital camera by the proposed method is close to that of the ideal camera. In addition, the image quality of pictures of digital camera using the proposed method is dramatically improved.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.3
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• pp.99-106
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• 1998

The performance of the turbofan engine, a medium scale civil aircraft which has been developing in Rep. of Korea, was analyzed and the control scheme for optimization the performance was studied. The dynamic and real-time linear simulation was performed in the previous study The result was that the fuel scedule of the step increase overshoot the limit temperature(3105 $^{\cire}R$) of the high pressure turbine and got small surge margine of the high pressure compressor. Therefore a control scheme such as the LQR(Linear Quadratic Regulator) was applied to optimizing the performance in this studies. The linear model was expected for designing controller and the real time linear model was developed to be closed to nonlinear simulation results. The system matrices were derived from sampling operating points in the scheduled range and then the least square method was applied to the interpolation between these sampling points, where each element of matrices was a function of the rotor speed. The control variables were the fuel flow and the low pressure compressor bleed air. The controlled linear model eliminated the inlet temperature overshoot of the high pressure turbine and obtained maximum surge margins within 0.55. The SFC was stabilized in the range of 0.355 to 0.43.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.441-449
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• 2015

In this paper we perform a linearized buckling analysis using the Kirchhoff plate theory and the von Karman nonlinear strain-displacement relation. Design sensitivity analysis(DSA) expressions for plane elasticity and buckling problems are derived with respect to Young's modulus and thickness. Using the design sensitivity, we can formulate the topology optimization method for minimizing the compliance and maximizing eigenvalues. We develop a topology optimization method applicable to plate buckling problems using the prestress for buckling analysis. Since the prestress is needed to assemble the stress matrix for buckling problem using the von Karman nonlinear strain, we introduced out-of-plane motion. The design variables are parameterized into normalized bulk material densities. The objective functions are the minimum compliance and the maximum eigenvalues and the constraint is the allowable volume. Through several numerical examples, the developed DSA method is verified to yield very accurate sensitivity results compared with the finite difference ones and the topology optimization yields physically meaningful results.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.34 no.4
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• pp.51-56
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• 2016

Old-growth and giant tree is a nonrenewable resource with great value. The purpose of this study is to provide scientific and reasonable evaluations for the preservation and management of the old-growth and giant tree. Until now the research of old-growth and giant tree's value evaluation and authoritative index is so insufficient and imperfection. Combining with the particularity of the old-growth and giant tree, this study analyzed the main value factors of the old-growth and giant tree and objectively selected the evaluation indicators. According to the actual situation value appraisal model of the old-growth and giant tree was builded. The main value factors can be divided into economic value, cultural history, growing place, tree state, tree form, tree vigor, protection level, growth environment, tree species, tree canopy, and so on. The evaluate indicators can be selected and the indicators' weight can be calculate using analytic hierarchy process methods(AHP). Based on economic value and indicators' weight, tree's total value can be revealed. After calculation and analysis, Gyeongju Gyerim Zelkova serrata's value evaluation results is 491,503,300 won. The research results of this study can provide scientific basis and reference to the old-growth and giant trees' value appraisal and loss compensation, and arouse people's environmental awareness.