• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.80-86
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• 2012

From 1982, the Korean Ministry of Employment and Labor has executed the risk assessment regulation for manufacturing industries. When a manufacturing company install, transfer, or modify the major facilities, the program inspects and verifies safety of the working place to ensure safety against risks. This study performed cost-benefit analysis of the program for the eight industrial categories that were free from the program. The cost-benefit analysis is the basic method to estimate the effect of the policy execution, and used to justify the policy effectiveness. As a result, there is the biggest benefit in the manufacture of basic metal products and then motor vehicles, trailers and semitrailers, other manufacturing, other machinery and equipment, wood products of wood and cork, rubber and plastic products, food products, furniture in order. Thus the hazard prevention program should be applied into the 8 industrial categories in order to strengthen national competitiveness, protect labors's safety, reduce the social cost and improve the welfare.

• Transactions of the KSME C: Technology and Education
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• v.4 no.2
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• pp.93-99
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• 2016

High pressure nozzles and turbines of a gas turbine engine should be required to be operated under extreme operating conditions in order to maximize the performance. Engine manufactures have utilized nickel-base superalloys, enhanced cooling design, and thermal barrier coating techniques to overcome them and furthermore, material modeling, finite element analysis, optimization techniques, and etc. have been utilized widely for elaborate predictions. We aim to evaluate the effects on the low cycle fatigue life of the high pressure turbine blade caused by thermal barrier coatings and the cooling design of the endwall of the first stage turbine nozzle. To achieve it, the structural analysis, which utilized the results of conjugate heat transfer analysis as loading boundary conditions, was performed and then the results were the input for the assessment of low cycle fatigue life at several critical zones.

• Conservation Science in Museum
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• v.5
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• pp.49-57
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• 2004

The Divine Bell of King Seongdeok was completed in 771 A.D. It is a true masterpiece both grand in its size and style (height 3.66 m, diameter 2.23 m, thickness 20.3 cm, weight 18.9 ton), illustrating the essence of the Korean bronze culture. However, there are no remaining records about its casting: where the raw material came from, how the materials were mixed and how the bell was casted. The absence of such records has limited the understanding of the bell. This article contains analysis of three samples collected from a protruding part inside of the bell during a safety test for the bell by the Gyeongju National Museum. The main issues are the element composition of the bell, microstructure on the casting time and the source where the raw material came from.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.9-15
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• 2017

Natural gas fuel has known to be very promising in terms of abundancy and economic value. Therefore it is widely treated as research topics in a variety field of production, storage and utilization. Natural gas has become one of the major sources for the power generation by using internal combustion engines(ICE). Development of natural gas fuel injection device should be preceded to realize a reliable natural gas fuel supply system for a MW class power generation reciprocating ICE. In this research, an injection valve which consists of solenoid and body part with a moving plate was designed and its dynamic performance was experimented in the engine-like environment. Displacement length and diameter of an armature and diameter of a solenoid coil were tested at former study. In this research the effect of materials of solenoid core, size of main housing inlet and supply gas pressure are examined.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.76-76
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• 2010

무연솔더 재료를 자동차 전장품에 적용하기 위해서는 고온환경에 대한 내구성 및 진동 인자에 대한 영향을 고려해야한다. 특히, ELV(End of Life Vehicles) 지침이 개정됨에 따라 고온용 무연솔더 재료에 대한 재평가가 반드시 필요한 시점이다. 이에 대해 본연구에서는 현재 상용화 된 Pb-free솔더의 재료들 중 총 4종의 Solder을 선정하여 자동차 환경에 부합하는 진동조건하에서 시험해보았다. 그리고 미세조직의 특성, 접합부 형성시의 기계적 강도 및 접합부의 신뢰성을 평가하여 보았다. 각각의 조성에 대한 CHIP type과 QFP type의 실장부품을 준비하였으며, 각각의 조성별로 솔더 페이스트로 Daisy Chain PCB에 접합하여 조성에 따른 비교 데이터를 구축할 수 있었다. 리플로우 공정후 초기의 미세조직 및 전당강도, 저항값을 측정하여 진동시험에 따른 데이터와 비교하였다. 주파수는 10Hz~1,000Hz였으며, 진동가속도는 $29.4m/s^2$, 20시간의 랜덤진동이 적용되는 동안 챔버내의 온도는 상온으로 유지되었다. 진동시험과 이에 따른 저항측정을 통하여 진동 주파수와 시간에 따른 실장 부품이 받는 진동 영향과 실시간 저항값을 측정하였으며, 이때의 미세조직 비교를 통해 진동특성을 평가하였다. 진동 주파수에 따른 저항값의 변화가 있었으며, 진동전후 전단강도에도 영향을 주었다. QFP type에서는 SAC105가 진동에 가장 취약하였으며, CHIP type에서는 SACX0307이 진동에 가장 취약하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.13-13
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• 2010

개요- 반도체 시장의 확대 및 소자의 고집적화와 장비의 초정밀화 등 고정도 생산성을 요구하는 현대 진공산업 시장에서는 정밀한 제품을 대량으로 생산할 수 있도록 지원할 수 있는 대용량 장비의 수요가 급증하고 있다. 서론- 하루가 다르게 발전하는 기술 경쟁 사회에서는 보다 성능이 좋은 제품을 다른 국가 또는 다른 업체와 차별화된 기술적 우위를 선점해야 한다. 본문-이에따라, 고신뢰도, 고생산성이 요구되는 진공산업 시장에 발맞추기 위한 일환으로 크라이오 펌프의 재생시간을 단축시켜 생산성 향상을 높이고, 기존의 제품에서 소비자가 느꼈던 진동을 최소로 줄일 수 있도록 저진동 제품의 설계를 통한 고객 만족의 제품을 개발함과 동시에, 맥동관 냉동기의 기술상업화를 꾀한 극저온기술 영역의 발전을 함께 도모하고자 한다. 현재까지는 국내의 일부 정부출연 연구소와 학교, 일부 특수산업 분야에서만 크라이오 펌프를 사용하고 있으나, 상업적인 설계 및 생산은 완전히 전무한 상태이다. 이는 진공시장의 잠재적인 성장을 고려할 때 국산화가 시급한 상황이다. 이러한, 상황을 고려하여 현재 기계연구원과 우성진공, 국민대학교가 맥동관 냉동기를 접목시킨 급속재생형 저진동 크라이오 펌프를 지난 2008년부터 산학연 협동으로 개발 진행 중에 있다. 크라이오 펌프의 핵심 기술은 냉동기의 효율에 있다고 볼 수 있으며, 이러한 냉동기의 효과를 높이기 위하여, 제작 공정에 진공 브레이징을 사용하여, 열교환기와 교환기 내의 충진재들과의 정확한 간극을 유지하면서 접합을 할 수 있는 환경요건을 지속적인 실험을 통해 지식을 습득하고 있다. 진공 브레이징은 외관을 아름답고 정교하게 접합할 수 있으므로, 추후 상품으로의 가치를 높일 수 있으며, 서로 다른 이종금속 간의 접합이 가능하여 열교환기의 무산소동과 스테인레스 튜브와의 접합을 가능하게 할 수 있었다. 진공브레이징에 쓰이는 모재는 여러가지가 있으며, 접합의 환경 또한 일반 용접보다 다양하므로 여러번의 실험을 통한다면, 성능은 우수하면서 외관으로 손색이 없는 개발품이 나올수 있겠다는 의견이 모아지고 있는 중이다. 본론- 아직까지는 미국의 CTI사나 일본의 ULVAC 등의 크라이오 펌프의 선진 기업에 비해 기술력이 많이 부족하기는 하지만, 아직 많은 부분이 미개발된 분야이고, 향후 후발국과의 차별을 두어 선진기술을 확보하기 위해서는 기존의 방식을 단순히 따라하는 것이 아닌 남들과 다른 원천기술의 확보가 더 필요하며, 이를 위해 부단한 노력과 시행착오를 거쳐 맥동관 냉동기형 크라이오 펌프라는 기술을 확보할 예정이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.773-780
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• 2015

Traditionally, additive manufacturing (AM) technology has been used to fabricate prototypes in the early development phase of a product. This technology is being applied to release manufacturing of a product because of its low cost and fast fabrication. AM technology is a process of joining materials to fabricate a product from the 3D CAD data in a layer-by-layer manner. The orientation of a layer during manufacturing can affect the mechanical properties of the product because of its anisotropy. In this paper, tensile testing of polymer-based specimens were built with a typical AM process (FDM, PolyJet and SLA) to study the mechanical properties of the AM materials. The ASTM D 638 tensile testing standard was followed for building the specimens. The mechanical properties of the specimens were determined on the basis of stress-strain curves formed by tensile tests. In addition, the fracture surfaces of the specimens were observed by SEM to analyze the results.

• Polymer(Korea)
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• v.33 no.3
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• pp.203-206
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• 2009

Polyaniline Emeraldine salt (PANI-salt) prepared by the common chemical oxidative polymerization caused the corrosion of the metallic injection mold by protonic acid such as HCl which used as a dopant. PANI-salt, polyaniline doped with dodecylbenzenesulfonic acid (DBSA), was obtained by the emulsion polymerization in nonpolar organic solvent, toluene. In this study DBSA was used as a dopant along with a surfactant. PANI-salt and high impact polystyrene (HIPS) have a good solubility in toluene. Blends with different ratio of PANI and HIPS were prepared through a solution-cast blending. The structure of PANI-salt was characterized by FT-IR and UV-Vis. The morphology, thermal, and electrical properties for PANI-HIPS blends were investigated. Injection molded under $103^{\circ}C$, 120 psi, PANI-HIPS showed the highest electrical conductivity ($6.02{\times}10^{-5}\;S/cm$) after blending PANI (50 mL) and HIPS (1 g).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.296-302
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• 2019

In this study, a basic durability assessment was performed by selecting the main part of a trial product of a shale shaker, which is one of components for a mud circular system. For a preliminary durability assessment, it was assumed that the lifetime of the bearing for the vibrator motor and the stiffness of the support spring are affected by the vibration when the motor operates continuously. In the case of the motor, the initial p-p level was 0.72 g, but after 100 hours of operation, the p-p level was rapidly increased to 1.26 g. Bearing defects could be estimated through ball defect frequency analysis. In the case of the spring, the stiffness of the spring was reduced by approximately 3.78% at the end of 2,000 hours of the fatigue-durability test by applying excitation conditions to shale shaker body. In the future, we will analyze the influence of the particle removal efficiency of the shale shaker.

• Journal of Korea Foundry Society
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• v.43 no.4
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• pp.187-193
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• 2023

Shell core making is an excellent process in terms of formability and desanding, but when the molten aluminum comes into con- tact with the shell core, gas generation by pyrolysis of the resin is inevitable. In addition, when the ventilation is inadequate, pores will remain inside the casting, which can directly lead to defects of the casting. While studies on the gas generation behavior of shell core making have been reported, the modeling of gas generation has not been extensively investigated. We will develop a gas evolution analysis method that considers the relationship between temperature and gas quantity for the core to be developed. We then use the developed method to analyze the flow and solidification behavior of metal molten metal during core mold design and low-pressure casting of cylinder head products, and predict the occurrence of casting defects to derive a casting method that min- imizes the occurrence of defects.