• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1067-1072
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• 2003

Generally dual mass flywheel(DMF) is used as a solution to reduce noise and vibration of power train system and to improve the comfortability of passenger car. In this paper, design concept of new DMF model, analytical/numerical model, test procedure and tuning results are presented. Design parameters are studied by some numerical methods and tests. As the result, we can find more efficient model of DMF and reduce vibration level in power train system.

• Computers and Concrete
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• 제4권1호
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• pp.49-66
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• 2007

The objective of this paper is to provide experimental data on the propagation of curved crack-surfaces and the respective load-displacement diagrams for the validation of numerical models for cracking of concrete, subjected to three-dimensional stress states. To this end beam-shaped specimens are subjected to combined bending and torsional loading, leading to the formation of a spatially curved crack-surface. The experimental data contain the evolution of the load and of the strains at selected points in terms of the crack mouth opening displacement and the propagation of the crack surface.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제5권2호
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• pp.39-51
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• 2001

This paper shows how boundary element method can be used to calculate torsion geometrical stiffness of cross-sections of various beams and airfoil profiles. Using the BEM direct formulation, the technique for determining bending and torsional geometrical characteristics of arbitrary multiply connected cross-sections is presented. The application limits of several well-known formulae on some test problems have been demonstrated and discused.

• 전자공학회논문지SC
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• 제40권3호
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• pp.189-198
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• 2003

영상 안진기(VOG, Videooculograph)는 전정 안반사의 객관적 평가 방법으로 이용되고 있는 안구 운동 측정 방법 중의 하나이다. 영상 안진기의 핵심 기술은 눈꺼풀이나 속눈셉, 각막 반사, 그리고 눈 깜박임과 같은 영향에 덜 민감하면서 동공의 중점과 회전 운동을 정확하게 찾는 것이다. 회전 운동의 측정에 있어 부정확한 동공의 중점은 부정확한 회전 운동 측정으로 이어지므로 3차원 영상 안진기에서는 중점의 정확한 추정이 매우 중요하다. 이를 위해 잡음에 영향을 적게 받는 동공 중점을 찾는 새로운 알고리즘을 제안하고 알고리즘의 성능에 영향을 주는 인자에 대해 분석하여 최적의 조건을 찾았다. 그리고 제안한 방법을 이용하여 안구의 수평, 수직, 회전 운동, 그리고 동공의 크기 변화를 측정할 수 있는 실시간 3차원 VOG 시스템을 구현하였다.

• Wind and Structures
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• 제9권6호
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• pp.441-455
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• 2006

A more applicable optimization model for extracting flutter derivatives of bridge decks is presented, which is suitable for time-varying weights for fitting errors and different lengths of vertical bending and torsional free vibration data. A stochastic search technique for searching the optimal solution of optimization problem is developed, which is more convenient in understanding and programming than the alternate iteration technique, and testified to be a valid and efficient method using two numerical examples. On the basis of the section model test of Sutong Bridge deck, the flutter derivatives are extracted by the stochastic search technique, and compared with the identification results using the modified least-square method. The Empirical Mode Decomposition method is employed to eliminate noise, trends and zero excursion of the collected free vibration data of vertical bending and torsional motion, by which the identification precision of flutter derivatives is improved.

• Wind and Structures
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• 제11권4호
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• pp.323-340
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• 2008

In this paper, the along-wind, across-wind as well as torsional dynamic wind loads on three kinds of lattice tower models are investigated using the base balance technique in a boundary layer wind tunnel. The models were specially designed, and their fundamental frequencies in the directions of the three principal axes are still in the frequency range of the spectra of wind loads on lattice towers. In order to clear contaminations to the spectra of wind loads induced by model resonance, the generalized force spectra of the first mode of the models in along-wind, across-wind and torsional directions were derived based on measured base moments of the models. The RMS generalized force coefficients are also obtained by removing the contributions of model resonance. Finally, the characteristics of the 3-D dynamic wind loads, especially those of the across-wind dynamic loads, on the three kinds of lattice towers are presented and discussed.

• 한국산학기술학회논문지
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• 제7권4호
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• pp.679-683
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• 2006

진동타입기에 의한 말뚝의 관입과정을 운동방정식으로 나타내고 수치적분법을 이용하여 말뚝의 관입속도를 예측할 수 있는 프로그램을 개발하였다. 개발된 프로그램에 의한 관입속도 계산결과를 기존의 현장시험결과와 비교분석하였다. 프로그램에 의해 계산된 관입속도값은 말뚝의 근입깊이가 클수록 실측값에 가까운 값을 보였다. 작은 근입 깊이에서 실측값과 계산값의 차이가 큰 이유는 실제 시공시 작은 근입깊이에서는 말뚝의 휨운동과 비틀림운동이 커서 결과적으로 말뚝에 전달되는 연직방향 압축력이 감소되어 나타난 결과로 판단되었다.

• Wind and Structures
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• 제8권3호
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• pp.197-212
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• 2005

Tall buildings under wind action usually oscillate simultaneously in the along-wind and across-wind directions as well as in torsional modes. While several procedures have been developed for predicting wind-induced loads and responses in along-wind direction, accurate analytical methods for estimating across-wind and torsional response have not been possible yet. Simplified empirical formulas for estimation of the across-wind dynamic responses of rectangular tall buildings are presented in this paper. Unlike established empirical formulas in codifications, the formulas proposed in this paper are developed based on simultaneous pressure measurements from a series of tall building models with various side and aspect ratios in a boundary layer wind tunnel. Comparisons of the across-wind responses determined by the proposed formulas and the results obtained from the wind tunnel tests as well as those estimated by two well-known wind loading codes are made to examine the applicability and accuracy of the proposed simplified formulas. It is shown through the comparisons that the proposed simplified formulas can be served as an alternative and useful tool for the design and analysis of wind effects on rectangular tall buildings.

• 한국지반공학회논문집
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• 제16권1호
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• pp.65-73
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• 2000

본 연구에서는 미소변형률에서 대변형률까지의 거동을 모델할 수 있는 탄소성 구성모델을 개발하였다. 제안된 구성모델은 일반 등방경화규칙에 근거한 비등방 경화규칙과 전응력 개념을 토대로 개발하였다. 그리고 제안된 구성관계가 기존의 대표적 구성모델을 포함하고 있음을 수학적으로 입증하였다. 국내 화강풍화토에 대한 공진주시험, 비틂전단시험, 삼축시험 등 일련의 실내시험 결과를 이용하여 검증한 결과, 쌍곡선 모델 및 Ramberg-Osgood모델과 비교하여 제안된 모델은 미소변형률에서 대변형률까지의 거동을 더욱 일관되고 정확하게 모델할 수 있다. 또한 비틂전단시험 결과와의 비교에서는, 미소변형률 조건에서 나타나는 비선형성을 적합하게 예측할 수 있었다.

• 한국해양공학회지
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• 제19권2호
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• pp.53-59
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• 2005

The effect of pH on the corrosion characteristics in the dissimilar friction welded zone of IN713LC-SCM440 in the loaded torsional stress was studied. The corrosion experiment was performed for 120 hours on the specimens with five steps of pH. The surface corrosion pattern of the SCM440 area showed global corrosion and narrow pitting, which was caused by galvanic corrosion between friction welded IN713LC and SCM440, but corrosion did not proceeded from the IN713LC area. The average relative electrode potential gradually tends to decrease with the elapse of the immersion time in the acidity area. The average corrosion current also gradually tend to decrease The corrosion rate showed a larger value when the average relative electrode potential was higher and the average relative current was lower. The corrosion rate showed a larger value when the average relative electrode potential was higher in the acidity area, and it showed large when the average relative electrode potential was lower in the alkalinity area.