• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.282-288
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• 2001

This paper deals with determining the proper friction welding condition and analyzing various mechanical properties of friction welded joints of the bladepart heat resisting steel(STD11) for cold die punch to the shank part alloy steel(SCM440). And the in-process real-time weld quality evaluation technique by acoustic emission during friction welding of STD11 to SCM440 steels with higher confidence and reliability has been much required even though it might be the first trial approach for developing it. Also, the high temperature properties of STD11-SCM440 weld were considered in this paper.

• Journal of Surface Science and Engineering
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• v.31 no.5
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• pp.266-277
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• 1998

The effects of $H_2S$ gas ratio, temperature and time on the case depth, hardness, and sulfide and nitride formation on the surface of sulfnitrided SCM440 steel have been studied by micro-pulse plasma technique. The thickness of compound layer of sulfide and nitride increased with the increase of time, temperautre and $H_2S$ gas ratio. But surface hardness decreased with the increase of soft sulfide layer because the hard nitride layer formed beneath the sulfide. The thickness of sulfide layer was about 10$\mu\textrm{m}$ abpve 0.0088% of $H_2S$ gas. The highest surface hardness of the compound layer was Hv835 at $530^{\circ}C$, 1hr and 0.06% of $H_2S$ gas. X-ray diffraction indicated that the surface products were $Fe_{1_x}S$, $Fe_{2.5}N$ and $Fe_4N$. It was confirmed by EPMA that sulfide only existed in the surface.

• Textile Coloration and Finishing
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• v.2 no.2
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• pp.14-19
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• 1990

The setting behavior of disulfide-enriched wool and disulfide-crosslinked silk obtained by treatment with a disulfide-containing crosslinking agent, bis $(\beta-isocyanatoethyl)$ dissulfide was compared with that of untreated wool and silk under the absence and the presence of a reducing agent. Rearrangment of secondary bonds facilitated by cleavage of crosslinks as well as rearrangement of crosslinks itself seems to play an important role in the set stability.

• Annual Conference of KIPS
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• 2019.10a
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• pp.440-441
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• 2019

오늘날, 우리는 운영체제에 사용할 수 있는 기술과 보안 방어에 초점을 맞추고 있다. 사람이 현장에서 찾아야 하는 가장 일반적인 서버 빛 워크스테이션 운영체제에 대한 기본적인 지식을 제공하며 OS 의 주요 특징, 약점, 그리고 기본적인 보안 방어에 대해 이야기 한다.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.42-48
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• 2011

440A martensitic stainless steels which were modified with reduced carbon content(~0.5%) and addition of small amount of nickel, vanadium, tungsten and molybdenum were manufactured. Effects of alloying elements and tempering temperatures on the uniform corrosion in the solution of lN H2S04 were investigated through the electrochemical polarization test. When tempering temperature is constant, corrosion current density in active-passive transition point, Icorr, decreased a little with an increase of austenitizing temperature. In addition to this, when austenitizing temperature is constant, longer holding time showed a little lower Icorr and Ipass, passive current density. And when austenitized at $1050^{\circ}C$ and tempered in a range of $350{\sim}750^{\circ}C$, best anti-corrosion properties were obtained at $350^{\circ}C$ tempering temperature while worst at $450^{\circ}C$ or $550^{\circ}C$. The specimens tempered at below $450^{\circ}C$ and above $550^{\circ}C$, similar and good anti-corrosion characteristics were obtained regardless of alloying elements added, showing anti-corrosion characteristics are influenced more by tempering temperature than by alloying elements.

• Proceedings of the KWS Conference
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• 1995.10a
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• pp.165-169
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• 1995

This paper deals with determining the proper friction welding condition and analyzing mechanical in of friction welded joints of sintered carbide tool materials (SKNM50 for the blade part of press punch) to alloy steel (SCM440 for the shank part of press punch), the alloy steel to aluminum(A6061 for the interlayer material between the blade part and the shank) and sintered carbide tool materials to aluminum. And also acoustic emission test will be carried out during fiction welding to evaluate the weld quality.

• Annual Conference of KIPS
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• 2012.04a
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• pp.440-442
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• 2012

데이터를 대량 생산하는 스마트 기기가 대거 등장한 요즘 빅데이터는 대용량 데이터를 분석하여 가치 있는 정보를 추출하고 이 지식을 바탕으로 위기에 대응하거나 변화를 예측하는 정보기술이다. 그러나 아직 빅데이터에 대해 분류하거나 분석하는 기술의 연구가 미비하다. 따라서 본 논문에서는 빅 데이터의 개념, 배경, 분석기술 현황에 대해 분석하고 빅 데이터 유형 분석 및 분석 기술의 향후 전망을 제시한다.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.8
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• pp.779-784
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• 2013

Increased efficiency and improved performance associated with light-weight materials were investigated in this study. Numerous studies have investigated surface treatments to improve the fatigue strength of metals. Laser heat treatment is a promising method because the power and spot size can be easily controlled, allowing a small heat affected zone (HAZ). However, changes in the material properties can result; in particular, the material can become more brittle. In this study, a combination of laser heat treatment and vibration peening was proposed to increase fatigue strength without changing the material characteristics. SCM440H was investigated experimentally, and specimens were tested using a giga-cycle ultrasonic fatigue tester. The results show that the combination of these two processes significantly increased the fatigue strength and, furthermore, different fracture types were observed after a small and large number of cycles.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.372-375
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• 2021

A three-leg inverter-type isolated DC-DC Converter that can use 220 and 440 V grid input voltages is introduced. The secondary circuit structure of the proposed topology is center-tap, which is the same as the conventional phase-shifted full-bridge converter. However, the primary circuit structure is composed of a three-leg inverter structure and a transformer, in which two primary windings are connected in series. The proposed circuit structure has a wider input voltage range than the conventional phase-shifted full-bridge converter, and the circulating-current on the primary-side is reduced. In addition, the voltage stress at the secondary rectifier is greatly improved, and high efficiency can be achieved at a high input voltage by removing the snubber circuit added to the conventional converter. Prototype converters with input DC of 311 V, output of 622 V, and 50 V and 6 kW class specifications were designed and manufactured to verify the validity of the proposed topology; the experimental results are presented.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.571-576
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• 2023

In this study, the harmless crack size(a_hml) according to the residual stress depth was evaluated using the fatigue limit of SCM440 steel by quenching-tempering(QT) and induction hardening(IH), and threshold stress intensity factor of QT steel. Because the residual stress increased rapidly as the crack depth increased, a_hml was determined at the depth of all the crack aspect ratio(As) regardless of Type I-III, and a_hml also increased according to the residual stress depth. a_hml was minimal at As=1.0 and maximal at As=0.1, but was almost similar on each Type. a_hml was small the dependence on As.