• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.586-594
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• 2009

This paper is the study on random, sinusoidal and shock vibration responses for the STSAT-3(science and technology satellite-3) proto-model which is the first small size all-composite satellite in Korea. The structure system of the STSAT-3 forms box type structure by joining several hybrid sandwich panels comprised of honeycomb core and carbon fiber reinforced laminated composite skins on both side. Mode shape, stress, displacement and acceleration responses are obtained on both the frequency domain and time domain by means of a commercial FEA software MSC/NASTRAN. From these analysis results, failure, safety factor and design validity are assessed. These results can be successfully applicable as reference data when a new satellite is developed as well as giving out an excellent criteria in satellite vibration treatment design.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.35-43
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• 2006

In this paper, procedures and research results involved in the development of glass reinforced composite bridge deck of hollow section were presented. Laminate design for the 3 cell deck section was performed. Structural characteristics such as serviceability, strength, failure and stability for DB24 load were analytically studied through the finite element analysis for the composite deck plate girder bridge. Composite deck tube was fabricated with pultrusion and extensive tests such as flexural test, girder-connection test, barrier-connection test, compression fatigue test and flexural fatigue test were carried out to evaluate structural behavior experimentally. Also, field load test was conducted for the demonstration plate girder bridge with composite deck and requirements for the strength and serviceability were reviewed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.1-8
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• 1991

Recently, researches for buried lifelines such as pipelines have been carried out to provide for safe design. On of the major causes to the damage of buried pipelines has been soil liquefaction. Analytical models have been presented to compare with the results from recent model experiment under a soil liquefaction environment induced by seismic shaking table. The analytical results were more than two times those those of experimental measurement. Thus the objective of this study is to introduce a rigorous nonlinear analysis of equation of motion with more realistic parameters which are dynamic soil and water pressure, dynamic subgrade reaction coefficient, and damping coefficient for soil liquefaction environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5558-5565
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• 2012

Roadside barriers are facility for preventing cars from out of path, and 7 classes of barrier are prescribed in criteria of road grades and speed limit, etc. However, overload and overspeed are increased according to improvement of vehicle performance, and falling over frequently occur in vehicle accident related in barriers. Therefore, enhancement of the existing design criteria of roadside barriers is demanded. In this research, vehicle crash simulation was carried out, and the condition for fracture of roadside barriers and vehicle overturn was evaluated in order to verify the defence performance of the barriers, which are SB5 steel barrier and SB6 concrete barrier adapted mainly to highway.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.1
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• pp.49-58
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• 1997

The membrane type LNG tank is non self-supporting tank which consists of both primary and secondary membrane supported through the insulation boxes by the adjacent hull struc¬ture. Although the membranes are not structural member. They are subject to periodical cyclic loads due to the thermal expansion and other expansions or contraction of membrane. At the design stage of the tank, an analytical and experimental approach on the fatigue strengths of membrane and its welds is necessary in order to assist the designer and the inpector. In this study the evaluation method of fatigue strength of membrane type LNG tank is pre¬sented with FEM analysis and fatigue test of lap welds and it contains the following:1) The fatigue tests and preparation of design S - N curve for lap welds 2) FEM analysis of test specimens 3) Estimation of cumulative damage factor of lap welds 4) Guideline for inspection of lap welds of membrane type LNG tank As the results of analytical and experimental approaches in this study, the evaluation method of fatigue strengths of membrane type LNG tank is proposed, which is expected to be useful for design and inspection of membrane type LNG tank.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.417-420
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• 2009

The purpose of the present study is to evaluate high temperature fracture toughness through the experimental and analytical method. The analysis method is proposed to simulate the fracture toughness of high temperatures. Load-COD curves of compact test specimen acquired by finite element method analysis using hypo elastic model are simulated to determine the crack initiation load on high temperatures. The results of experimental work are in accord with analysis in thermal shock test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.350-353
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• 2009

In the fatigue analysis and the components design, uncertainties are caused by the variances of geometry data and applied loads, and the scatter of material properties. In this paper, fatigue crack growth life of turbine is evaluated by fracture mechanics and the reliability analysis is accessed by the fist order second moment method and Monte Carlo simulation.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.125-130
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• 2011

발전 설비는 기대 수명동안의 안정성을 확보하기 위하여 해당 규격에 부합하도록 설계하여 건설된다. 하지만 가동 중 다양한 복합 환경에 노출됨에 따라 구조물을 이루고 있는 재료의 열화 현상이 가속화되어 예기치 못한 파손이 발생할 수 있다. 기계적 물성은 재료의 기계적 거동을 나타내는 주요 척도가 되며 이는 신뢰성 및 안전과 직결된다. 하지만 기존의 역학물성을 측정하는 대부분의 시험법들은 특정 크기의 시편을 요구하고 파괴적인 시험법이기 때문에 가동 중 시설물에 적용하기가 불가능하였다. 이러한 한계점을 극복하고자 비파괴적이고 정량적인 시험이 가능한 연속압입시험법이 최근 각광받는 시험법으로서 많은 연구자들에 의해 연구되고 있다. 이 시험법은 시험 대상물의 형상에 제약을 받지 않으며 시험 절차가 매우 간단하다는 장점을 가진다. 또한 대상의 국소 부위에 시험할 수 있어 취약 부위 판별이 가능하다. 본 연구에서는 대표응력-대표변형률 기법을 통하여 인장물성을 평가하고, 압입 하중 차이를 이용하여 소재에 존재하는 잔류응력을 평가하는 기법을 소개한다. 또한, 연속압입시험을 이용하여 실제 발전소 파이프의 취약부위로 알려진 용접부에 대하여 인장물성 및 잔류응력을 측정함으로써 실제 산업체의 신뢰성 평가가 적용할 수 있음을 확인하였다.

• Magazine of the Korea Concrete Institute
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• v.8 no.6
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• pp.141-149
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• 1996

The reinforced high-strength-concrete beam subjected to flexure moment behaves more brittly than the moderate-strength-concrete beam reinforced with equal reinforcement ratio($\rho$/$\rho_b$). Test results show that when the concrete strength exceeds 830kg/$cm^2$, the maximum reinforcement ratio should be less than $0.6{\rho}_b$ for ductile behavior (${\rho}_b$=balanced steel ratio). The ratio of flexural strength between experimental results and analytical results with rectangular stress block decrease as the compressive strength of concrete increase. The shape of the compressive stress block distributed triangularly. because the ascending part of the stress-strain curve shows fairly linear response up to maximum stress in contrast to the nonlinear behavior of the medium and low strength specimens.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.582-585
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• 2000

인터넷의 급속한 발전으로 빠른 데이터 전송이나 대용량의 데이터 전송이 현실화 되고 있다. 또한 신속한 정보 획득으로 인한 생활의 질적 향상은 물론 국가 경쟁력의 확보등을 이룰 수 있다는 긍정적인 효과가 있는 반면 인터넷의 확장으로 인한 시스템의 불법침입, 중요 정보 유출, 시스템 파괴.변경등의 부정적인 사례들이 계속 증가하고 있다. 특히, 최근에 컴퓨터 시스템의 침해 사고가 국내.외적으로 빈번히 일어나고 있어, 이에 대한 대책이 절실히 요구되고 있다. 이와 같은 요구에 대비하고자 하는 대표적인 보안 대책으로는 암호화, 복호화 기술과 시스템 보안 기술등이 있다. 특히, 이러한 기술중의 하나인 침입 탐지 기술은 침입 차단 기술과 함께 정보 시스템의 안전한 운영을 위해 필수적인 기술이라고 할 수 있다. 본 논문에서는 분산 시스템 환경에서 자연 면역시스템을 적용하여 실시간적으로 침입을 탐지하는 시스템을 제안한다.