• 소성∙가공
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• 제20권6호
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• pp.409-419
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• 2011

Membrane structures are widely used for LNG(Liquefied Natural Gas) storage tanks. This study presents a membrane structure based on the Mark-III type. For its development, a series of numerical simulation was conducted using ABAQUS and experimental investigation was carried out. The manufacturing process of the membrane was simulated. The thickness distribution predicted by the numerical approach agreed well with the experimental results.

• 열처리공학회지
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• 제23권3호
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• pp.137-141
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• 2010

The Co-Cr alloys have clinical histories in dental and orthopaedic implants, and recently in cardiovascular stent applications because the alloys exhibit a high elastic modulus and radiopacity. In order to improve mechanical property of the Co-Cr alloys, electropolishing is employed as the final process. Electropolishing, an anodic dissolution process in the transpassive state, is sensitively affected by process conditions such as current density, machining time, electrode gap. In this study, the effect of heat treatment conditions on surface roughness and inclusion analysis is investigated in Co-Cr alloy (L605). The most smooth surface of Co-Cr alloy is obtained when electropolishing is performed at 15-20 V for 15-30 sec with a electrode gap of 3.5 mm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.342-344
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• 2001

The single phase control system may become noisy when speed is controlled with a conventional triac AC controller. This paper describes that a simple modification to the triac circuit is shown to reduce the effect, at the cost of increased power dissipation in the controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1797-1799
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• 1998

Plasma source ion implantation(PSII) is a non-line-of-sight technique for surface modification of materials which is effective for non-planar targets. A apparatus of 30kV PSII is established and plasma characteristics are diagnosed by using a Langmuir probe. A spherical target is immersed in argon plasma and biased negatively by a series of high voltage pulses. Sheath evolution is measured by using a Langmuir probe and compared with the result of computer simulations.

• Bulletin of the Korean Chemical Society
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• 제29권7호
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• pp.1344-1348
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• 2008

A microbial fuel cell (MFC) has been regarded as noble clean energy technology that can directly convert biomass to electricity. However, its low power density is a main limitation to be used as a new energy source. To overcome this limitation, we focused on the anode improvement in a mediator-type MFC using P. vulgaris as a biocatalyst. Fuel cell performance increased when the anode was coated with carbon black or polypyrrole. The best performance was observed when polypyrrole/carbon black (Ppy/CB) composite material was coated on a carbon paper electrode. Our obtained value of 452 mW $m^{-2}$ is the highest value among the reported ones for the similar system. The effects of amount of Ppy/CB, mediator concentration, and amount of P. vulgaris have also been examined.

• 한국CDE학회논문집
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• 제10권6호
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• pp.381-391
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• 2005

The design methodology of injection molding die has been changed from two-dimensional drafting to three-dimensional solid modeling, which is due to many advantages over the conventional methodology in terms of design modification and data associativity. In addition to the solid modeling capability, it is required for a mold designer to utilize a database management system that facilitates efficient mold design. In the paper presented is the implementation of a software program which automatically generates three-dimensional mold-bases including standard parts and slider parts, conforming to given geometric constraints. It is based on a commercial CAD system (Unigraphics NX) along with related API (application program interface) libraries. The research is expected to reduce design efforts and simplify construction of a complex three-dimensional mold-base model that is comprised of standard parts and slider parts, by use of the three-dimensional database and automatized geometric dimensioning.

• 대한산업공학회지
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• 제19권4호
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• pp.3-11
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• 1993

We propose a new dual simplex method using a primal interior point. The dropping variable is chosen by utilizing the primal feasible interior point. For a given dual feasible basis, its corresponding primal infeasible basic vector and the interior point are used for obtaining a decreasing primal feasible point The computation time of moving on interior point in our method takes much less than that od Karmarker-type interior methods. Since any polynomial time interior methods can be applied to our method we conjectured that a slight modification of our method can give a polynomial time complexity.

• 대한화장품학회지
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• 제13권1호
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• pp.15-28
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• 1987

Silica spheres were prepared by interfacial reaction method. Factors in-fluencing to the mean particle size and specific surface area of silica spheres were investigated. The experiment about the surface modification of silica spheres was carried out. It was observed that silica spheres have characteristics of the spherical shape with the vacancy in the inner side, high surface area, and reaction tendency by many silanol group. The mean particle size of silica spheres is dependent on the surfactant concentration and W/O ratio. The specific surface area is influenced by SiO2/Na2O mole ratio in sodium silicate. Silica spheres coated with titanium dioxide or zirconium dioxide improve the UV protection effect. Titanate and silane coupling agent make chemical bond with silica surface and improve the organophile and the dispersibility of silica spheres.

• 한국진공학회지
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• 제12권S1호
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• pp.10-14
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• 2003

Coatings of hydroxyapatite (HA) and tricalcium phosphate/HA (TCP/HA) on titanium were fabricated by ion beam assisted deposition (IBAD). Significant effect of the Ca-P coatings on human Gingival Fibroblasts (HGFs) attachment and formation of type I collagen were found by using immunofluorescence microscope. TCP/HA and HA coatings exerted more HGFs attachment and collagen I formation. Comparing with HA coating, TCP/HA coating exhibited better responses during the late period of the tests. This investigation indicated that this surface modification method may enhance the biological seal at the cervical level of the titanium dental implants.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.562-567
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• 2003

This paper presents the method of Rate of Loading(ROL) improvement for the Motor Operated Gate Valve operating in high differential pressure condition. The character of ROL and Stem Factor is analyzed. Static test and dynamic test were performed and acquired the diagnosis signal for the valve closing stroke. The result of this study is the modification of stem factor is very important factor for the ROL improvement. In order to obtain the same value of dynamic test thread friction coefficient stem and stem nut should be combined appropriately.