• 수산해양기술연구
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• 제24권2호
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• pp.94-100
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• 1988

평면 굽힘부식피로 시험기를 사용하여 선박용 알루미늄합금재의 부식피로파양에 관한 연구를 한 결과 다음과 같은 결론을 얻었다. 1. 비저항이 증가함에 따라서 초기 부식피로균열발생까지의 반복회수는 지연되고, 그 부식감수성은 감소하는 양상을 나타낸다. 2. 비저항이 감소할수록 Paris rule의 실험상수 m 값은 작아지면서 응력강도 계수값에 비해 부식에 의한 영향이 더욱 민감해 진다. 3. 알루미늄 5086 합금의 부식피로균열은 입계균열파양의 양상을 보이고 있다. 4. 응력강도계수값이 증가함에 따라 부식감수성은 감소되어지고 응력강도계수값이 40kg.mm super(-3/2) 이상일 때 부식감수성은 거의 균일하게 된다.

• 대한화학회지
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• 제7권2호
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• pp.182-185
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• 1963

In the previous paper of the series of researches on the graphitic properties of anthracites, authors have already reported the results on the electrical specific resistance measurements for Korean anthracites in order to develope a simple methods which differentiate graphite from anthracite. In this paper, the X-ray diffraction method and oxidation have been applied and compared with the results which were obtained by the specific resistance measurements in the previous paper. It has been confirmed that there is a parallel relation between the value of specific resistance measurement and height of hexagonal peak by X-ray diffraction, but the color reaction due to graphitic acid by oxidation does not show any definite critical points between graphite and anthracite.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.673-681
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• 2014

In this paper, a novel low specific on-resistance SOI LDMOS Device with P+P-top layer in the drift region is proposed and investigated using a two dimensional device simulator, MEDICI. The structure is characterized by a heavily-doped $P^+$ region which is connected to the P-top layer in the drift region. The $P^+$ region can modulates the surface electric field profile, increases the drift doping concentration and reduces the sensitivity of the breakdown voltage on the geometry parameters. Compared to the conventional D-RESURF device, a 25.8% decrease in specific on-resistance and a 48.2% increase in figure of merit can be obtained in the novel device. Furthermore, the novel $P^+P$-top device also present cost efficiency due to the fact that the $P^+$ region can be fabricated together with the P-type body contact region without any additional mask.

• 전기전자학회논문지
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• 제20권2호
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• pp.181-183
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• 2016

탄화규소(Silicon Carbide) 기반의 1200 V급 Merged Pin Schottky(MPS) 다이오드의 구조를 2D-atlas simulation tool을 사용하여 최적화 및 설계하였다. 최적화된 항복전압과 온-저항 값을 얻기 위해 본 소자에서 중요한 파라미터인 P-Grid의 도핑농도와 에피층의 도핑농도를 각각 $2{\sim}10{\times}10^{17}cm^{-3}$, $2{\sim}10{\times}10^{16}cm^{-3}$으로 변화시키면서 소자의 전기적 특성을 분석하였으며, 그 후 P-Grid의 Space값을 $1{\sim}5{\mu}m$로 설계하여 이에 따른 항복전압과 온-저항의 값을 확인하였다. 항복전압과 온-저항은 서로 trade-off 관계에 있기 때문에 각 변수에서 도출된 값들을 Baliga's Figure Of Merit (BFOM)식에 대입하여 비교하였다. 그 결과 고전압 소자에 적용 가능한 1200 V급 4H-SiC MPS다이오드를 최적화 및 설계를 도출하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권8호
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• pp.438-444
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• 2000

We report the effects of etch process parameters on the ohmic contact formation in the plasma etching of GaN. Planar inductively coupled plasma system with $CH_4/H_2/Ar$gas chemistry has been used as etch reactor. The contact resistance and the specific contact resistance have been investigated using transfer length method as a function of RF bias power and %Ar gas concentration in total flow rate. AES(Auger electron spectroscopy) analysis revealed that the etched GaN has nonstoichiometric Ga rich surface and was contaminated by carbon and oxygen. Especially large amount of carbon was detected at the sample etched for high bias power (or voltage) condition, where severe degradation of contact resistance was occurred. We achieved the low ohmic contact of $2.4{\times}10^{-3} {\Omega}cm^2$ specific contact resistance at the input power 400 W, RF bias power 150 W, and working pressure 10mTorr with 10 sccm $CH_4$, 15 sccm H2, 5 sccm Ar gas composition.

• BMB Reports
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• 제28권3호
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• pp.227-231
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• 1995

In order to figure out the relationships between structural features and biological activity of the host-specific HC-toxin in maize, structurally related cyclic tetrapeptides, chlamydocin and CYL-2 were isolated, and their biological activities in maize were examined. Biological activities of preparations were determined by root growth inhibition and electrolyte leakage bioassays. Chlamydocin and CYL-2 showed toxicities to maize. However, the toxicities of these compounds were non-specific. Thus, the precise peptide ring structure of HC-toxin apparently does not play an important role in toxicity, while resistance of maize to HC-toxin is based on a precise ring conformation.

• ETRI Journal
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• 제34권1호
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• pp.134-137
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• 2012

Power metal-oxide semiconductor field-effect transistor (MOSFET) devices are widely used in power electronics applications, such as brushless direct current motors and power modules. For a conventional power MOSFET device such as trench double-diffused MOSFET (TDMOS), there is a tradeoff relationship between specific on-state resistance and breakdown voltage. To overcome the tradeoff relationship, a super-junction (SJ) trench MOSFET (TMOSFET) structure is studied and designed in this letter. The processing conditions are proposed, and studies on the unit cell are performed for optimal design. The structure modeling and the characteristic analyses for doping density, potential distribution, electric field, width, and depth of trench in an SJ TMOSFET are performed and simulated by using of the SILVACO TCAD 2D device simulator, Atlas. As a result, the specific on-state resistance of 1.2 $m{\Omega}-cm^2$ at the class of 100 V and 100 A is successfully optimized in the SJ TMOSFET, which has the better performance than TDMOS in design parameters.

• 공업화학
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• 제27권2호
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• pp.210-216
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• 2016

본 연구에서는 무전해 니켈 도금 시간을 달리하여 제조한 자동차 시트용 탄소섬유 발열체의 발열 및 전기적 특성에 관하여 고찰하였다. 무전해 니켈 도금된 탄소섬유의 비저항 및 비열은 4-point probe method 및 differential scanning calorimetry (DSC)를 이용하여 분석하였으며, 표면 형상 및 표면 온도는 scanning electron microscope (SEM) 및 열화상 카메라를 이용하여 관찰하였다. 실험 결과, 도금시간의 증가에 따라 니켈 도금 두께 및 표면 온도는 증가하였으며, 반면에 비열 및 비저항은 도금시간이 증가함에 따라 감소하였다. 결과적으로 무전해 니켈 도금은 자동차 시트용 탄소섬유 발열체의 저항 발열 및 전기적 특성을 크게 향상시키는 것으로 판단된다.

• 열처리공학회지
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• 제12권2호
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• pp.166-173
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• 1999

Commercial carbon steels containing 0.2~0.55 wt.----C were plasma-nitrided or plasma nitrocarburized at $550^{\circ}C$ for 21.6Ks using $H_2-N_2$ or $H_2-N_2$-CO mixed gas respectively. The characteristics of hardening and wear-resistance of each treatment were studied and compared. And also microstructure of nitrided layer and nitrides formed in compound layer near surface were studied. All plasma-nitrided steels investigated showed remarkable increase of surface hardness with the increase of carbon content. But nitrocarburized steels resulted in higher surface-hardness than plasma-nitrided steels, which means that nitrocarburized has higher surface-hardening effect. Plasma-nitrided steels showed hardness increase in through-thickness direction near surface. And also nitrocarburized steels showed similar hardness distribution in through-thickness direction to that of plasma-nitrided steel. However, nitrocarburized steels had higher cross-sectional maximum-hardness than plasma-nitrided steels as much as 100Hv. Wear test showed that the amount of specific wear was reduced by both plasma-nitriding and nitrocarburized, showing that the amount of specific wear was not related to the hardness. But non-treated specimen showed that the amount of specific wear was related to the hardness.

• 한국응용과학기술학회지
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• 제31권2호
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• pp.329-336
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• 2014

The conductive polymer composites have attracted considerable attention in the field of industry due to their electrical properties. To understand electrical properties of the composites, their volume specific resistance was measured. Electrical conductivity results showed percolation phenomena. Percolation theories are frequently applied to describe the insulator-to-conductor transitions in the composites composed of conductive filler and insulating matrix. It was found that the percolation threshold strongly depends on the aspect ratio of filler particles. The critical concentration of percolation formed is defined as the percolation threshold. The purpose of this study was to examine electrical properties of the epoxy resins filled with nickel. The sample was prepared using vehicle such as epoxy resin replenished with nickel powder, and the evaluation on their practical use was performed in order to apply them to electric and electronic industry as well as general field. The volume specific resistance of epoxy resin composites was 4.666~13.074 when using nickel powder. Weight loss of the conductive composites took place at $350^{\circ}C{\sim}470^{\circ}C$.