• 한국군사과학기술학회지
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• 제14권3호
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• pp.532-537
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• 2011

This paper describes the development of SPH(Smooth Particle Hydrodynamics) scheme and integration into the multi-material shock physics code(ExLO) for the purpose of the application to the extreme large deformation problems. SPH numerical scheme has been extended into the fluid dynamics and the high-speed impact events, such as space structure protection against space debris and meteorite catering. Like other hydrocodes, SPH scheme also solves the conservation equations with the constitutive equation including equation of state. The benchmark problem, Taylor-Impact test, was simulated and the predictions show good agreements with both the published numerical data and experimental data. Currently, the contact treatment between materials is under development.

• 한국건축시공학회지
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• 제14권4호
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• pp.350-358
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• 2014

공동주택의 구조형식이 기둥식 구조로 이행되면서 경량벽체의 수요가 증가하고 있다. 경량벽체는 구조적 안전을 위해 소정의 내충격성을 확보할 필요가 있다. 본 연구에서는 질량과 형상이 다른 경질 충격체 7종류와 일상적으로 벽체에 충격하중을 가하는 단단한 물체 5종류를 대상으로 하중해석 실험을 실시하였다. 충격에너지가 같아도 추의 질량이 다르면 하중의 크기가 최대 2배 이상 차이가 난다는 것을 실험적으로 규명하였다. 또한 경질 충격체의 하중과 실제 물체의 하중을 비교 분석하여 경량벽체의 재료설계를 위한 기초적 자료로서 제시하였다.

• 품질경영학회지
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• 제52권2호
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• pp.287-301
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• 2024

Purpose: This paper aims to verify the difference in production resilience between local clusters and regions without clusters before and after a major crisis. Furthermore, this paper aims to identify the clusters' quality factors that impact clusters' shock vulnerability and resilience. Methods: Utilizing open-source data from the US Cluster Mapping platform, this paper compares regions with industrial clusters to those without using the Differences-in-Differences (DID) estimator. It considers the regions with industrial clusters as a treatment group and others as the control group, comparing the period before and after the pandemic. Additionally, the paper examines which cluster factors make a difference in economic resilience during the crisis using Regression Discontinuity Design (RDD). Results: The study finds that regions with industrial clusters show higher production resilience compared to regions without clusters. Moreover, the number of establishments, annual payrolls, and employment can have a positive impact on resilience during the pandemic shock. Conclusion: Though clusters could be vulnerable during the global crisis, industrial clusters can contribute to regional economic development and production resilience in the long-term aspect. Thus, it is required to construct a high-quality local cluster and support it during the economic crisis in the long-term aspect.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.111-116
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• 2018

본 논문은 시스템 에어컨 실외기 포장품의 낙하충격해석 및 시험검증을 수행한 내용을 다룬다. 포장은 낙하충격으로 부터 제품을 보호할 수 있도록 충격에너지를 흡수할 수 있는 완충재질과 이를 제품에 고정하기 위한 부재로 구성되는데 작은 부피로 충분한 완충성능을 발휘하는 포장 설계를 위해서는 충격 시 제품에 가해지는 충격가속도 등을 정확히 평가하는 것이 필수적이다. 본 논문에서는 외연적 시간적분을 활용하는 유한요소해석 기법을 활용하여 실외기 포장품의 낙하충격해석을 수행하였다. 정확한 해석을 위한 해석모델 구축, 재료 시험을 통한 데이터 획득 및 재료 모델의 선정, 신뢰성 있는 해석 데이터 확보를 위한 계측 센서의 모델링 등이 수행되었으며 이렇게 구해진 해석데이터와 시험으로 구해진 가속도 및 변형률 시간이력을 비교하였다. 해석모델에 반영된 감쇄계수 등의 오차로 인하여 대체로 해석결과가 시험 결과에 비해 충격 가속도 및 변형률을 크게 예측하고 있으나 전체적인 데이터의 경향과 낙하 방향의 충격가속도는 정확하게 계산되었다. 이에 본 연구에 사용된 모델 및 해석기법을 에어컨 실외기 포장 설계에 활용할 수 있음을 확인하였다.

• Structural Engineering and Mechanics
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• 제48권4호
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• pp.569-585
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• 2013

The use of the rigid polyurethane foam (RPF) to strengthen sandwich structures against blast terror has great interests from engineering experts in structural retrofitting. The aim of this study is to use the RPF to strengthen sandwich steel structure under blast load. The sandwich steel structure is assembled to study the RPF as structural retrofitting. The filed blast test is conducted. The finite element analysis (FEA) is also used to model the sandwich steel structure under shock wave. The sandwich steel structure performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the field blast test and the numerical model. The RPF improves the sandwich steel structure performance under the blast wave propagation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1109-1112
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• 2004

This study reports on the pressure relief design and braided composite of surge arrester. Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. As a solution, this study describes pressure relief design performance of arresters with braided composite module. In general, braided composite has Potential for improved impact and delamination resistance. Manufacturing processes of the braided composite could also be automated and could potentially lead to lower costs. Therefore, in consideration of characteristics of pressure relief for polymer arrester, the fabric pattern of braided composite was decided. And Polymer arrester module was manufactured with braid. The mechanisms of pressure occurrence and relief were investigated basically by analyzing arc energy and the correlation between thermal shock and indoor pressure in pressure relief test.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.91-94
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• 2003

The present study addresses experimental results to investigate the details of the near field flow structures produced in the under-expanded, dual, coaxial, swirling, jet. The sonic swilling jets are emitted from a sonic inner nozzle and the outer annular nozzle produces the co/counter swirling streams against the primary swirling jet, respectively. The interactions between both the secondary annular swirling and primary inner supersonic swirling jets are quantified by the pilot impact and static pressure measurements, and visualized by using the Schlieren optical method. The experiment has been performed fur different swirl intensities and pressure ratios. The results obtained show that the secondary co-swirling jet significantly changes the inner under-expanded swirling jet, such as the recirculation zone, pressure distribution, through strong interactions between both the swirling jets, and the effect of the secondary counter-swirling jet on the primary inner jet is similar to the secondary co-swirl jet case.

• 대한기계학회논문집A
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• 제30권3호
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• pp.241-248
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• 2006

Shoe cushioning systems are important to prevent body injuries. This study developed and evaluated a cushioning system to reduce impact force on the heel. The cushioning system suggested consist of a polyurethane pocket, which contains water and porous grains of open cell to dissipate the energy effectively. Load-displacement curves fer the shoe cushioning system were obtained from an instrumented testing machine and the results were compared with various pockets with air, water or grains. Mechanical testings showed that the pocket with 5g porous grain was the best for the cushioning system. This system can be applied to the design of various kind of sport shoes.

• 유공압시스템학회논문집
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• 제2권2호
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• pp.14-20
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• 2005

This study developed and evaluated a shoe cushioning system to reduce impact force patterns during running. The shoe cushioning system is composed with a poly urethane pocket, which contains water and porous grains to absorb the force against the weight inside the pocket. Load-displacement curves for the shoe cushioning system were obtained from an instrumented testing machine and the results were compared with various pockets that have air, water or grains. Mechanical testings showed that the pocket with 5 g particles was the best for the shoe cushioning system. This founding will be helpful to designing the shoe.

• Earthquakes and Structures
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• 제2권1호
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• pp.1-24
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• 2011

During very strong earthquakes, seismically isolated buildings may experience large horizontal relative displacements, which may lead to poundings if an insufficiently wide clearance is provided around the building. This paper investigates, through numerical simulations, the effectiveness of using rubber bumpers, which could be attached at locations where it is likely to have impacts, in order to act as shock-absorbers. For the simulation of the dynamic behavior of such rubber bumpers during impacts, a nonlinear force-based impact model, which takes into account the finite thickness of the rubber bumpers, has been developed. Subsequently, a series of parametric analyses are performed to assess the effect of the gap size, the earthquake characteristics and the thickness, compressive capacity and damping of the bumpers. The stiffness of the moat wall is also parametrically considered during poundings of a seismically isolated building, as another potential mitigation measure for poundings of seismically isolated buildings.