• KDI Journal of Economic Policy
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• v.36 no.3
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• pp.61-93
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• 2014

This paper analyzes Onbid car auction data by employing various methods, including structural estimation, to identify main factors which decides auction prices and figure out what effects those factors are making on the auction price. I then discuss on how to maximize sellers' revenue in OnBid car auctions. The government and public institutes sell their assets through the OnBid auction, hence the optimal design of the OnBid auction is important. The paper's main findings are as follows: (ⅰ) The independent private value model explains OnBid car auction data better than the correlated private value model or the interdependent value model; (ⅱ) Both the number of bidders and the ratios of the auction price to the evaluation value were lower in the auctions posted by the Kamco than auctions by institutes other than the Kamco; (ⅲ) Some auctions require that at least two bidders should submit a bid no less than the reserve price for sale. In those auctions, both the number of bidders and each bidder's valuation on the auctioned object were lower than in auctions without that requirement; (ⅳ) The sum of sellers' revenue would be decreased in the simulation with the reserve price higher by 5%, 10%, and 20% across auctions by institutes other than Kamco.

• Polymer(Korea)
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• v.34 no.1
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• pp.79-83
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• 2010

Alginate beads were prepared using poly(N-isopropylacrylamide-co-dimethylamino ethyl methacrylate)(P(NIPAM-co-DMAEMA)). First, P(NIPAM-co-DMAEMA) was immobilized on the surface of alginate beads by taking advantage of electrostatic interaction between alginate and P(NIPAM-co-DMAEMA). Second, P(NIPAM-co-DMAEMA) was contained in the matrix of alginate beads. P(NIPAM-co-DMAEMA) were prepared by a free radical polymerization at $74^{\circ}C$ for 12 h. The weight ratio of NIPAM to DMAEMA monomer was 95/5. The copolymer was identified by $^1H$-NMR. Releases from the alginate beads were observed at 30, 37, and $45^{\circ}C$ using blue dextran or FITC-dextran(fluorescein isothiocyanate-dextran) as a model drug. The effect of temperature on the degree of release from the beads was insignificant. FITC-dextran was released more than blue dextran possibly due to its smaller molecular weight.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.821-823
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• 2011

본 논문에서는 초고온/고압의 환경에서 사용되는 메탈 구루부드 가스켓의 품질 및 생산성 향상 그리고 원가절감을 목표로 Gasket제작 전용기계시스템을 개발하여 제작기술혁신을 하고자 하였으며, 전용기계시스템의 구성은 그루부 가공전용기, 벤딩 전용기, 후열처리 전용기, 용접비드 황삭전용기, 용접비드 연삭전용기로 이루어져 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.455-467
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• 2017

In this study, a finite element analysis of a cylindrical multi-pass weldment for dissimilar metals was performed. The effects of the heat input method and weld bead generation method were considered. We compared two heat input methods: the heat flux method and the temperature method. We also compared two weld bead generation methods: the element birth method and the quiet element method. Although the results of the thermal analysis show deviations between the two heat input methods, the welding residual stresses were similar. Because the areas exposed to high temperature were similar and the strength of the material was very low in high temperature (above the $1000^{\circ}C$), the effects of the weld bead temperature were insignificant. The distributions of the welding residual stress were similar to each other. However, gaps and overlaps occurred on the welding boundary surfaces when the element birth method was applied. The quiet element method is more suitable for a large deformation model in order to simulate a more accurate weld shape.

• Korean Chemical Engineering Research
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• v.44 no.3
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• pp.300-306
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• 2006

Photocatalyst deposited beads were prepared by fluidized bed chemical vapor deposition (FB-CVD) under various operating conditions of substrates, bed temperature, pressure, and oxygen concentration. Photocatalytic degradation of acetaldehyde was carried out to determine the optimum operating condition of prepared photocatalysts. They were characterized by using FE-SEM, XRD, and XPS. From the FE-SEM photographs, it was found that the surfaces of titania-coated beads were covered with crystal form, particle form, and slick form of titania on alumina, silica-gel, and glass beads, respectively. From the result of photocatalytic degradation of acetaldehyde, it was found that prepared titania/ alumina beads at $600^{\circ}C$, 5 torr showed superior performance to others, and oxygen flow rate has no significant effect.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2004.10a
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• pp.78-81
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• 2004

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.100-102
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• 2004

인장강도 600MPa 이상을 가지는 TRIP형 고장력 강판인 60TR-R과 석출경화형 합금인 CHSP60C는 자동차용 소재로 주목을 받고 있다. 또한 레이저 용접은 열 변형이 적고 비드 외관이 미려할 뿐만 아니라 연속 및 고속 용접이 가능하여 생산성 및 정밀성, 안정성이 높아 자동차조립 및 부품 제조공정에 적용되고 있다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.177-183
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• 2005

In this work, Inconel 600, Inconel 625 and Haynes 230 are welding using Nd:YAG laser and electron bear. These heat-resistant alloys are typically used for the liquid thruster. To examine, the affects of experimental parameters on weld ability, the plate welding of these materials were carried out using both Nd:YAG laser and electron bear. Also, the micro-structure, micro-hardness, and tensile strength of the specimens were analyzed. from the analysis of the experimental results of laser and electron beam welding, we have obtained the optimal welding conditions.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.3-3
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• 2009

선박의 건조과정에서 필수적으로 선체 외판에는 선박의 안전과 운항 및 정비 등에 필요한 정보를 나타내기 위해 다양한 종류의 마크 및 문자가 마킹되어진다. 하지만, 단순한 도장 작업만으로는 해상과 같은 부식 환경에서 마크 및 문자가 쉽게 지워지거나 손상되기 때문에 마크 및 문자를 용접 비드(welding bead)로 표시하거나 미리 절단된 강판(steel plate)을 수동으로 용접한 뒤 도장을 함으로써 마크 및 문자의 손상을 방지하고 있다. 이러한 문자마킹작업을 하기 위해서는 작업자가 수작업으로 기준선과 마크 및 문자의 위치를 먹줄 등을 이용하여 마킹을 하고, 해당 마크 및 문자의 템플렛(template)을 이용하여 펀칭을 실시한 후 수동으로 용접을 실시한다. 하지만, 수작업을 통한 선체외판 문자마킹 작업은 작업자의 기량에 따라 품질이 상이하여 품질 저하의 원인이 된다. 또한 대조립 및 탑재 단계에서 문자 마킹 작업시 수직자세의 용접을 요구함으로써 작업자가 안전사고에 노출되어 있으며, 선박의 각 단계별 주요 공정보다 작업시간이 길어져 전체 선박 건조공정을 지연시키는 문제점 등을 야기시킬 수 있다. 이러한 문제점들을 해결하기 위해 조선업계에서는 선체 외판의 마크 및 문자를 자동으로 용접할 수 있는 장치를 개발하기 위해 노력해왔으며, 몇몇 개발 사례가 보고되고 있다. 하지만, 그 실효성 부분에서는 아직까지 해결하지 못한 문제점들로 인해 현장 적용에는 어려움을 보이고 있다. 본 연구에서는 선박외판 문자 자동용접장치의 기능성뿐만 아니라 현업 적용성을 가장 우선적으로 고려하여 문자마킹장치(Marking Robot for Shipbuilding) 개발을 진행하였다. 우선, 적절한 용접 재료를 선정하기 위해서 솔리드 와이어(Solid Wire)와 플럭스 코어드 와이어(Flux Cored Wire)에 대한 비드온 용접(Bead-On Welding)을 아래보기자세와 수직자세에 대해서 실시하여 적절한 용접 조건을 설정하였다. 본 연구에서 개발된 문자마킹 자동용접장치는 3축으로 구성되어 있으며 각 축들을 분리할 수 있도록 개발하여 이동성을 향상시켰으며, 작업면과 용접토치간의 거리를 일정하게 유지시킬 수 있도록 용접전류 센서(Welding Current Sensor)를 이용하여 토치 높이(Wire Extension)를 제어함으로써 균일한 품질의 용접비드를 얻을 수 있었다. 또한 문자마킹 자동용접장치는 본체 구동부와 제어부(Touch Screen)가 쉽게 분리되고 장착이 가능한 구조로 개발되었으며, 용접시 각 용접자세별로 용접전압, 전류 그리고 용접속도 설정이 가능하여 아래보기 자세뿐만 아니라 어떠한 자세에서도 같은 모양의 비드형상을 가지는 문자마킹용접이 가능하도록 개발하였으며, 이는 실험과 현장적용을 통해 검증하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.217-223
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• 2019

The application of 3D printing technology is expanding due to the production of the complex-shape parts and the one-step manufacturing process. Moreover, various technical solutions in 3D printing are emerging through continuous research and development. Representative technologies include SLS technology, in which a desired area is sintered and laminated by irradiating a powder-type material with a laser. In addition, high-performance engineering plastic parts are being manufactured in increasing numbers. In this study, tensile specimens were fabricated from polyamide 12, a widely available polymer, and the glass bead-reinforced polyamide 12. The specimen-build orientation was divided into 0°, 45°, and 90° on the fabrication platform, and the tensile test temperature was -25℃, 25℃, and 60℃. The test results showed that the tensile modulus of both materials decreases as the build orientation becomes closer to 90°. In addition, the tensile strength of glass bead-reinforced PA12 showed more dependence on the build orientation than PA12. In addition, the tensile modulus and tensile strength decreased with increasing test temperature.