• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1994.10a
• /
• pp.231-237
• /
• 1994

컴퓨터의 눈부신 발달에 힙입어 실험 또는 해석적 방법으로 일반 구조물이나 기계구조물의 진동특성을 손쉽고 정확하게 파악하는 것이 가능하게 되었다. 그런데 최근의 산업현장은 지금까지의 정확한 구조해석에만 그치지 않고 이를 바탕으로 강도 개선, 재료 절감을 통한 원가절감, 중량 최소화 문제등의 차원에서 동적인 특성의 변경을 요구하고 있다. 이러한 문제는 그 중요성에도 불구하고 여전히 설계자의 경험이나 시행착오에 의존하고 있는 실정이다. 본 연구에서는 구조물 결합부분에 주목하여 동특성의 변경 문제를 해석하고자 하였다. 즉 거의 모든 구조물이 결합부를 가지고 있는데 결합부 특성을 정확히 파악할 수 없기 때문에 리벳이나 보울트나 어떤 특수한 형태 결합부가 구조물의 특성에 주는 영향을 예측하기 어렵다. 이러한 결합부이 특성을 알아내고 구조물 동특성 변경 및 개선안을 제시하는 최적설계를 위해 감도해석기법은 아주 유효하게 쓰일 수 있다. 한편 구조물의 대형화, 복잡화는 구조물 동특성 해석에 더욱 많은 계산시간과 용량이 큰 전자계산기를 필요로 하게 되었으며, 분계의 결합부위가 변경되거나 결합형태가 변했을 때 전계의 동특성을 다시 해석할 필요없이 분계만의 정보로부터 전계의 동특성을 알아낼 필요가 생겼다. 이러한 의미에서 구조물의 분계로부터 전계의 동특성을 해석을 위한 부분구조합성법이 대두되게 되었다. 본 연구에서는 이러한 감도해석과 부분구조합성법의 공통된 문제를 일치화하고자 하였다. 즉 감도해석기법을 이용하여 필요한 구조물의 동특성에 부합하는 결합부의 최적한 설계변수를 규명하였고 이렇게 구해진 결합부의 설계변수와 분계의 정보를 알고리즘이 비교적 간단하고 오차가 적은 축소임피던스 합성법에 적용하여 전계의 동특성을 해석함으로써 감도해석기법과 축소임피던스 합성법의 통합적용이 최적설계와 이에 따른 동특성 해석에 효과적인 방법임을 보이고자 하였다. 대상구조물은 구조물 결합의 기본적인 형태인 T형을 선택하였다. T형 구조물은 분계 A(16개의 사각요소)와 분계 B(8개의 사각요소)로 이루어져 있으며 두개의 스프링으로 결합되어 있다. 설계변수는 강성에 국한하였으며 결합부의 결합형태는 탄성결합과 강결합으로 하였다. 감도해석과 축소임피던스 합성법에 의해 구해진 고유진동수와 FRF를 상용 유한 요소 해석 패키지인 MSC/NASTRAN을 통하여 검증하여 이 연구의 타당성을 검토하였다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.12
• /
• pp.5655-5660
• /
• 2012

The objective of this study is theoretically to suggest the effective heat exchanger design method using boundary layer analysis. The boundary layer formation and interruption on rectangular plate and round plate fins are explained and the heat transfer coefficients showed with the variation of the velocity and temperature boundary layer. In addition, the flow pattern on one plate fin surface considered as external flow and flow pattern between fins considered as internal flow. As a result, theoretical method for the boundary layer interruption avoidance is suggested and the heat transfer coefficient of the round plate fin was higher than that of the rectangular plate fin because of the less thermal and velocity boundary layer thickness except the centerline.

• Journal of the Korea Convergence Society
• /
• v.9 no.10
• /
• pp.37-44
• /
• 2018

In this thesis, the traffic signal system is generally applied to the intersection of urban side streets, where blind spots and cramped areas are high risk of accidents, contributing to the prevention of accidents and smooth traffic communication. Therefore, the purpose of the system is to prevent accidents and facilitate traffic communication by providing a light traffic signal at street intersections in busy cities. Also, this study is a universal application of traffic angle to vehicles without the need for a separate terminal installation, and the provision of traffic signals in cities In addition, it is thought that the narrow loss of life on the road can serve as a catalyst to help optimize its function as a signal system that can minimize damage.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.4C
• /
• pp.149-157
• /
• 2012

In order to investigate the soil disturbance induced by anchor-shoe for PVD installation and the anchoring mechanism, a new two dimensional testing system was developed. By using the developed testing system, 1g and centrifuge model tests were performed, simulating the driving-retrieval process of both conventional symmetric anchor shoe and new asymmetric anchor shoe. Various size anchor-shoes were simulated and the results were compared. The images recorded during the installation were analyzed by image processing technique. The results of the image analysis presented the clay disturbance depending on the size and type of anchor shoe. In addition, from the retrieval process, the anchoring mechanism was revealed and the holding capacity was measured. As results, the size of anchor shoe influences the soil disturbance and holding capacity. The new asymmetric anchor shoe reduces the soil disturbance and improves anchoring performance.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37C no.12
• /
• pp.1271-1280
• /
• 2012

In the recent parking assistant systems, finding out the distance to the object behind a car is often performed by the range sensors such as ultrasonic sensors, radars. However, the installation of additional sensors on the used vehicle could be difficult and require extra cost. On the other hand, the motion stereo technique that extracts distance information using only an image sensor was also proposed. However, In the stereo rectification step, the motion stereo requires good features and exacts matching result. In this paper, we propose a fast algorithm that extracts the accurate distance information for the parallel parking situation using the consecutive images that is acquired by a rear-view camera. The proposed algorithm uses the quadrangle transform of the image, the horizontal line integral projection, and the blocking-based correlation measurement. In the experiment with the magna parallel test sequence, the result shows that the line-accurate distance measurement with the image sequence from the rear-view camera is possible.

• KDI Journal of Economic Policy
• /
• v.33 no.2
• /
• pp.111-143
• /
• 2011

As the 'jobless growth' is developing into a worldwide phenomenon, many countries try to recover a virtuous relationship between the growth and employment using various wage subsidy programs. This study focuses on wage subsidy to employers, labor demand-side wage subsidy for which one can think of two types-a tax credit(a flat wage subsidy) and a social insurance premium exemption(a proportional wage subsidy). For job creation, Korean government reintroduced a tax credit to small and medium-sized enterprises(SMEs) which have increased their employment level in 2010. But many experts has continuously insisted that it should be replaced with a social insurance premium exemption arguing only a few SMEs benefit from the tax credit as most of them are actually not paying any corporate or general income tax bills. However, as the insurance premium exemption accompanies an increase in the amount of budget with the coverage widen, one cannot confirm its cost effectiveness over the tax credit. This paper aims to provide a theoretical analysis to derive some formal conditions under which a social insurance premium exemption creates more jobs than a tax credit does given a budget constraint. We show that the former's dominance over the latter depends on whether there exists a dead zone of social insurance or not. If there does not exist a dead zone, a social insurance premium exemption is more desirable in many cases, whereas one cannot guarantees its dominance over a tax credit if there exists a dead zone. Therefore in order to realize its dominance, the government should minimize a dead zone so that most SMEs effectively benefit from the insurance premium exemption. In addition, applying discriminative exemption rates which reflect each firm's job conditions such as wage level and labor demand/supply sensitivity, the government try to enhance job creation effect.

• Journal of Korean Society of Transportation
• /
• v.32 no.4
• /
• pp.293-302
• /
• 2014

Recently, advanced sensors and communication technologies have been widely applied to advanced safety vehicles for reducing traffic accidents and injury severity. To apply the advanced safety vehicle technologies, it is important to quantify safety benefits, which is a fundamental for justifying application. This study proposed a methodology for quantifying the effectiveness of the Advanced Driver Assistant System (ADAS) with the Analytic Hierarchy Process (AHP). When the proposed methodology is applied to 2008-2010 Gyeonggi-province crash data, ADAS would reduce about 10.18% of crashes. In addition, Adaptive Cruise Control, Automatic Emergency Braking System, Lane Departure Warning System and Blind Spot Detection System are expected to reduce about 10.43%, 10.17%, 9.96%, and 10.18%, respectively. The outcomes of this study might support decision making for developing not only vehicular technologies but also relevant safety policies.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.3
• /
• pp.277-285
• /
• 2023

Recently, as the magnitude and frequency of earthquakes increases, research is needed to increase the ductility of the columns in order to prevent the collapse of structures. In this study, to evaluate the performance of columns reinforced with continuous transverse reinforcing bars, the FE model for the dynamic analysis of structures reinforced with continuous transverse reinforcing bars for circular and rectangular columns is to be verified using the results of uniaxial compression experiments in the previous study. As a result, the experimental value of the column reinforced with continuous transverse reinforcement and the result value related to the dynamic analysis showed similar behavior, and the reliability was high. As a result of the analysis, the usability of the rectangular column reinforced with continuous lateral reinforcing bars was confirmed because the dissipated energy performance of the columns reinforced with spiral reinforcing bars was higher than that of the columns reinforced with band reinforcing bars.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2013.06a
• /
• pp.40-42
• /
• 2013

본 논문에서는 사각 평면이 아닌 실린더나 구 형태의 비평면 스크린에 고품질 파노라마 영상을 렌더링 하기 위해 스틸 카메라를 이용한 자동 캘리브레이션과 멀티 프로젝터를 이용한 파노라마 렌더링 시스템을 제안한다. 스틸 카메라를 이용한 비평면 스크린 캘리브레이션은 특정 패턴을 스크린에 투사하고 이를 촬영하여 프로젝터의 투사 왜곡을 보정하고 멀티 프로젝터간의 중첩 영역에 대한 보정을 자동 수행한다. 캘리브레이션이 완료된 이후에 멀티 프로젝터를 이용하여 고품질의 파노라마 비디오를 렌더링 하기 위해서 본 논문에서는 복수의 멀티 시스템과 동기화 카드를 이용하여 렌더링 시스템간의 재생 동기화를 수행 하였다. 제안하는 렌더링 시스템을 적용하면 기존의 전문가의 수동작업에 의한 인력 및 보정 시간을 줄일 수 있으며, 시스템 환경이 변하더라도 쉽게 적응적으로 렌더링 환경을 구축하는 것이 가능하고 고품질의 파노라마 비디오를 렌더링 하는 것이 가능하다.

• Proceedings of the KAIS Fall Conference
• /
• 2004.06a
• /
• pp.162-164
• /
• 2004

슈뢰딩거와 포아송 방정식의 연계풀이에 의해 수치해석적으로 구한 파동함수와 에너지 준위를 이용하여 $300^{\circ}$K에서 사각우물을 형성하는 $Al_xGa_{1-x}As/Ga_yIn_{l-y}As/GaAs$ HEMT 소자 채널 영역에서의 극성광학 포논, 음향 포논, 압전 산란, 이은화된 불순물 산란, 그리고 합금 산란에 대한 2차원 산란율을 계산하여, 같은 영역에서의 3차원 산란율과 비교하였다. 그 결과 bulk영역에서 가장 우세한 이온화된 불순물 산란이, 2-DEG 시스템에서 크게 감소되었음을 알 수 있었는데, 이는 변조 도핑에 의하여 이온화된 불순물을 2-DEG가 존재하는 채널영역의 불순물 양을 감소시켰기 때문으로 해석된다.