• 한국전기전자재료학회논문지
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• 제35권5호
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• pp.494-498
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• 2022

In this study, SiO₂ 20 phr, ATH 70 phr, and platinum flame retardant were mixed with raw silicone rubber and -10 kV was applied to measure electrostatic charge attenuation voltage, surface resistance, and volume resistance, and the following conclusions were obtained. When the platinum flame retardant was 0 phr, the humidity 74.6% and the temperature was 21.8℃, the potential was half-reduced to 0.63 kV, 0.57 kV, and 0.44 kV when the applied voltage was changed from -10 kV to -8 kV, and the time halved to 50% was increased to 2.40 seconds, 2.47 seconds, and 2.61 seconds. It was confirmed that as the platinum flame retardant increased from 0.1 to 0.3 phr, the potential half-reduced to 0.67 kV, 0.60 kV, and 0.595 kV decreased, and the charge potential attenuation time half-reduced to 50% decreased to 3.44 seconds, 1.78 seconds, and 1.60 seconds. It was confirmed that the surface resistance increased as the humidity decreased, and the volume resistance decreased as the platinum flame retardant increased.

• Progress in Superconductivity
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• 제3권1호
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• pp.104-110
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• 2001

Since the strand-to-strand type joint far CICC (Cable-In-Conduit Conductor) is small in size and has low DC resistance, it is expected to be useful type fur a superconducting magnet system which had a compact structure like the KSTAR (Korea Superconducting Tokamak Advanced Research) coil system. The DC resistance is changed according to the distribution patterns of strands in cables connected together in the joint. A commercial code was used for the calculation of the DC resistance. With the decrease of outer diameter of the Joint, Which means the increase of strand volume fraction in the joint, the calculated DC resistance decrease rapidly and non-lineally. The variation of resistance depends mainly on the volume fraction of solder which has higher resistivity than copper. The resistance decrease inversely with the increase of the length of the joint. The resistance increase with increase of number of triplets in each stack contacted with that of another terminal cable. In case of the strand-to-strand joint that has 62mm of outer diameter, 52mm of inner diameter, 100mm of overlap length, and four triplets in each stack, the calculated DC resistance is less than 1 n-Ohm.

• Journal of Forest and Environmental Science
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• 제24권2호
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• pp.111-118
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• 2008

산림 훼손지 비탈면 녹화에 주로 사용되는 관목류 7종에 대한 인발저항실험을 실시하였다. 조사수종의 평균인발력은 두릅나무 37.26 kgf, 버드나무 34.56 kgf, 국수나무 26.00kgf의 순으로 측정되었으며, 뿌리의 근원경 및 뿌리체적이 크면 클수록 인발력은 높게 산출되었다. 뿌리 근원경과 뿌리 체적에 대한 인발력은 산딸기나무가 가장 상관관계가 높았으며, 산초나무가 가장 낮았다. 그리고 뿌리의 근원경에 따른 인발력은 대부분 유의적인 차이가 있는 것으로 나타났으며, 뿌리체적에 따른 인발력은 뿌리체적이 20 ml미만에서만 수종간의 인발력 차이가 있는 것으로 나타났다.

• 한국전산유체공학회지
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• 제20권1호
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• pp.57-64
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• 2015

This paper describes a volume of fluid(VOF) method, mRHRIC for the simulation of free surface flows around ship hulls and provides its validation against benchmark test cases. The VOF method is developed on the basis of RHRIC method developed by Park et al. that uses high resolution differencing schemes to algebraically preserve both the sharpness of interface and the boundedness of volume fraction. A finite volume method is used to solve the governing equations, while the realizable ${\kappa}-{\varepsilon}$ model is used for turbulence closure. The present numerical results of the resistance performance tests for DTMB5415 and KCS hull forms show a good agreement with available experimental data and those of other free surface methods.

• Transactions on Electrical and Electronic Materials
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• 제14권1호
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• pp.43-46
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• 2013

In order to develop electrical insulation material, organically modified layered silicate was incorporated into an epoxy matrix to prepare nanocomposite. Transmission electron microscopy (TEM) observation showed that organophillic clay was in an exfoliated state, while hydrophilic clay was not dispersed into nanolayers within the epoxy matrix. Epoxy/organophilic clay (2.8 wt%) nanocomposite was mixed and cured at $150^{\circ}C$ for 4.5 hr. I-V characteristics, volume resistance and dielectric properties for the cured nanocomposite were estimated. Current density increased with increasing temperature, and volume resistance decreased with increasing temperature, in neat epoxy and epoxy/organophilic clay (2.8 wt%) nanocomposite. As frequency increased, the dielectric loss value decreased in the two systems.

• 한국해양공학회지
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• 제17권2호
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• pp.40-46
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• 2003

The corrosion resistance of super duplex stainless steel on both its fibrous and dispersed phase was investigated. These structures consist of various volume fraction and distribution of austenite structure, which were obtained by changing the heat treatment temperature and cycle. The fibrous phase had higher austenite volume fraction than that of the dispersed phase at the same temperature. Corrosion resistance of super duplex stainless steel was evaluated through an immersion test and an impingement test, using 35% HCI and sea water, respectively. Super duplex stainless steel was compared with STS316L and STS304. The corrosion resistance of super duplex stainless steel was superior to ST316L and STS304. The dispersed phase of super duplex stainless steel was more stabilized than the fibrous phase in corrosion. The magnitude of corrosion rate was in order STS304, STS316L, fibrous phase of super duplex stainless steel and dispersed phase of super duplex stainless steel.

• 대한전자공학회논문지
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• 제26권10호
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• pp.1545-1553
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• 1989

The ohmic contact behavior in HEMT structure was compared with that in MESFET one throughout the specific contact resistance and microstructural change in both structures. A Au-Ge-Ni based metallization scheme was used and the alloying temperature of the ohmic materials was changed from 330\ulcorner to 550\ulcorner. The alloying temperature to obtain the minimum specific contact resistance in HEMT structure was 60k higher than that in MESFET. The volume fraction of NiAs (Ge) in MESFET structure increases with alloying temperature and/or the alloying time, which makes the decrease of specific contact resistance at the initial stage of ohmic metallization. In contrast, the volume fraction of NiAs(Ge) in HEMT structure was not dependent upon the specific contact resistance, which implies that the ohmic contacts are dominantly formed by the Ge diffusion to 2-DEG(two dimensional electron gas) layer.

• Journal of Welding and Joining
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• 제20권3호
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• pp.54-59
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• 2002

Overlays is a treatment of the surface and near-surface regions of a material to allow the surface to perform functions that are distinct from those frictions demanded far the bulk of the material. Welding, thermal spray, quenching, carburizing and nitration have been used as the surface treatment. Especially, weld overlay is a relatively thick layer of filler metal applied to a carbon or low-alloy steel base metal for the purpose of providing a wear resistant surface. In this study, weld overlay was performed by MAG welding on the base metal(SS400) with filler metal which contain composite powders($Cr_3C_2+Mn+Mo+NbC$) and solid wire(JIS-YGW11). Characteristics of hardness and wear resistance on overlays were analyzed by EDS, EPMA, XRD and microstructures. Carbide formations were $M(Cr, Fe)_7C_3$ and NbC phases. And carbide volume fraction, hardness and specific wear resistance of overlays were increased with increasing powder feed rate and decreasing wire fred rate. Hardness and wear resistance were almost proportioned to carbide volume fraction of overlay.

• 대한토목학회논문집
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• 제31권2A호
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• pp.105-113
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• 2011

본 연구는 보강섬유의 종류(마섬유, 펄프섬유, PVA섬유, 나이론섬유) 및 혼입률(0.0%, 0.1%, 0.2%, 0.3%)이 다공성 식생콘크리트의 역학적 특성과 내약품성에 미치는 효과를 평가하였다. 시험은 섬유의 종류 및 혼입률의 변화에 따른 다공성 식생콘크리트의 압축강도, 공극률, pH, 휨강도 및 내약품성 특성을 분석하기 위하여 수행하였다. 섬유의 종류 및 혼입률은 다공성 식생콘크리트의 압축강도, 공극률 및 내약품성에 영향을 미쳤다. 섬유의 혼입률이 증가할수록 압축강도, 휨강도 및 공극률은 증가하였다. 그렇지만 다공성 식생콘크리트의 pH 값과 내약품성은 섬유의 종류 및 혼입률의 변화에 큰 영향이 없었다.

• 대한기계학회논문집
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• 제10권3호
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• pp.316-325
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• 1986

본 연구에서는 이상배합조직강에 있어서 피로균열진전거동의 미시조직 의존 성을 밟히기 위하여 제이상 마르텐사이트가 모상 페라이트를 둘러싼 마르텐사이트페라 이트 복합조직강을 준비하고 미시조직이 각각 다른 4종류의 시험편에 대하여 피로시험 을 실시한후 이에 의해 얻어진 피로균열진전속도를 균열휨과 균열닫힘을 통하여 검토 하였다.