• Electric Engineers Magazine
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• v.208 no.12
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• pp.37-43
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• 1999

서지전압은 전산시스템과 같은 전자장비에 대표적인 장해원으로 급속하게 증가되고 있다. 통계자료에 의하면 서지 전압에 기인한 장비의 파손 방생률이 매3~4년마다 배가되고 있다.

• Polymer Science and Technology
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• v.10 no.1
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• pp.65-71
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• 1999

• Korean Journal of Construction Engineering and Management
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• v.11 no.6
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• pp.111-121
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• 2010

As the customer's interest for sidewalk block in the street or apartment complex is increasing, the materials of block which had been a concrete block exclusively are varied to clay paver, native rock and wood etc. Especially, the sales volume of clay paver which is environment-friendly and ergonomic is dramatically increasing every year with two digits growth rate, however, many problems like "Edge Cracking" "Freezing Breakage" "Bending Breakage" "Joint Gap" are happening frequently within a couple of hours after installation due to the durabilities. Because of the characteristics of Ceramic products, clay pavers are very easy to be broken when they are bumped against each other. In addition, they are relatively fragile by a freezing expansion breakage when exposed to water due to hydrophilic property as well as the intensity and absorptance of the products are varied with small difference from the production process such as production equipment and process control. Therefore, it costs a lot of money to repair the breakdown unless production and installation is carried out according to the strict criteria of the quality control. In this study, the symptoms of breakdown frequently happened in clay paver are classified by each type and finally the solution for this problem in the production of brick, installation and criteria of quality control through compressive strength and absorptance test is suggested.

• Composites Research
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• v.17 no.1
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• pp.18-28
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• 2004

In order to evaluate the strength of carbody structures of railway rolling stock made of laminated fiber-reinforced composite materials, total laminate approach was introduced. Structural analyses were conducted to check the basic design of hybrid composite carbody structures of the Korean Tilting Train eXpress(TTX) with the service speed of 180km/h. The mechanical tests were also conducted to obtain strengths of composite laminates. The results show that all stress components of composite carbody structures are inside of failure envelopes and total laminate approach is recommended to predict the failure of hybrid composite carbody structures at the stage of the basic design.

• Composites Research
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• v.22 no.2
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• pp.18-23
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• 2009

Failure of Kevlar29/Phenolic composite plate under high velocity impact of FSP(Fragment Simulation Projectile) is investigated using a non-linear explicit finite element code, LS-DYNA. Composite laminate and impactor are idealized by solid element and interface between laminas are modeled by tied-break element in LS-DYNA. Interaction between impactor and laminate is simulated face-to-face eroding contact algorithm. When the stress level meets a failure criteria, the layer in the element is eroded. Numerical results are verified by existing test results.

• Composites Research
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• v.29 no.2
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• pp.53-59
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• 2016

Aircraft wing structure is used as a fuel tank containing the fluid. Fuel tank and joint parts are consists of composite structure. Hydrodynamic Ram(HRAM) effect occurs when the high speed object pass through the aircraft wing or explosion and the high pressure are generated in the fuel tank by HRAM effect. High pressure can cause failure of the fuel tank and the joint parts as well as the aircraft wing structure. To ensure the aircraft survivability design, we shall examine the behavior of the joint parts in HRAM effect. In this study, static tensile tests were conducted on four kind of the composite T-Joints. The failure behavior of the composite T-joint was examined by strain gauges and high speed camera. We examine the validity of the Finite Element Modeling by comparing the results of FEA and static tensile tests. The failure stresses and failure pressure of the composite T-Joint were calculated by FEA.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.59-67
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• 2012

This study presents the evaluation of the patching materials that are used to repair the distress of asphalt pavement. Four kinds of patching materials currently used in practice were tested in both laboratory and field. The laboratory tests included the dry and soaked Marshall stability test, indirect tensile test, wheel tracking test and adhesive strength between the asphalt pavement and the repairing material was tested as a performance test. The field study was conducted using the slab samples placed on the location of vehicle tire passing and the performance of the repairing materials were investigated as passing the traffic load. The result of the laboratory tests were satisfied with the current design criteria and material standard except for water-immersion stability. Type C patching material showed the highest adhesive shear strength among the patching materials tested. However, the mature distress, such as rutting and stripping were monitored after construction in 10 days. It was found that performance of patching material is lack of quality behavior when they were applied in the field and required to develop and applu to prevent the mature distress of the current patching materials.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.111-116
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• 2010

To improve occupants' safety in an emergency, crashworthy design is necessary to rotorcraft design and development. Especially, landing gear has the important role for crashworthy design because landing gear absorbs relatively large energy for the crash landing. In addition, military specifications require failure of landing gear shall not increase danger to any occupants by penetration of the airframe. To meet the specification requirements, crashworthiness device like failure mechanism should be prepared so that landing gear is collapsed safely and doesn't penetrate the airframe. In this study, design and design development test of the failure mechanism which is necessary for the rotorcraft landing gear was performed. First, collapse scenario was determined for the landing gear not to penetrate the airframe. Then, the failure pin which is the most important part of the failure mechanism was designed with 2 strength range in order to meet design criteria. Finally, design of the failure mechanism was verified successfully by design development test.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2007.10a
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• pp.265-270
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• 2007

국가기준점은 측량을 위한 주요 시설물로서 관리가 매우 중요하다. 그러나 국가기준점이 설치되어 있는 환경은 측량을 위한 시야 확보가 필요하기 때문에 삼각점의 경우 산 정상이나 인근 기준점과 시통이 가능한 위치에 설치하며, 수준점의 경우 도로변이나 하천변에 설치한다. 국가기준점은 화강암으로 된 표석 형태로 설치되기 때문에 이렇게 외부환경에 노출될 경우 자연 풍화, 인위적인 훼손, 파손 등이 발생할 수 있다. 이러한 현황 파악을 위하여 주기적인 방문관리가 필요하다. 그러나 전국적으로 약 22,000개 가량 설치되어 관리가 어려운 실정이다. 본 연구에서는 국가기준점 관리의 효율성을 높이고 기준점 정책 수립을 위한 통계자료수집을 위한 국가기준점 모니터링 시스템을 개발하였다.본 시스템은RFID가 부착된 국가기준점을 사용할 경우 RFID를 인식하는 단말기는 실시간으로 CDMA 망을 이용하여 모니터링 시스템에 정보를 전송하고, 웹 시스템 상에서 실시간으로 현재 사용중인 기준점이 표시된다. 사용중인 기준점의 사용용도 및 사용자의 현황도 화면에 표시된다. 이러한 정보는 이력관리가 되며, 사용 및 관리에 관한 이력정보 보고서, 기준점별 사용 빈도 및 사용 목적별 빈도 등이 저장되어 기준점 설치, 관리 대상 기준점 선정 등을 위한 기준점 정책 수립을 위한 통계자료를 생산할 수 있다. 이러한 시스템 개발을 통하여 실시간 기준점 모니터링이 가능하며, 관리대상 기준점 선정, 전산화된 이력관리 구현 등으로 인하여 관리비용을 절감하고, 관리인력을 최소화 하는 효율적인 기준점 관리가 가능하게 될 것이다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.261-266
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• 1998

This paper presents a numerical simulation of the failure behaviour for the pipeline which has external corroded parts along the axis. The numerical study for the pipeline failure analysis is based on an FEM with an elastic-plastic and large-deformation. The predicted failure assessments for the simulated corrosion defects are compared with ANSI/ASME B31G code and a modified B31G method.