• 열처리공학회지
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• 제26권1호
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• pp.7-13
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• 2013

Vacuum heat treatment(indirect heating method) has long exposure time at high temperature and low quenching rate. Contrarily salt bath heat treatment (direct heating method) has short exposure time at high temperature and fast cooling rate. With these different features of processes, mechanical properties such as hardness, tensile strength and impact strength of products show very different results. In this study, Salt bath heat treated products showed higher tensile strength and impact strength than vacuum heat treated products but hardness was not much different. These lower mechanical properties of vacuum heat treated products are due to differences in heat process and secondary hardening with high temperature tempering process. Consequently, It indicates that salt bath heat treatment is better way than vacuum heat treatment for product to have high mechanical properties.

• 대한금속재료학회지
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• 제48권3호
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• pp.225-234
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• 2010

Salt bath nitriding, which has been developed recently by domestic company, is an emerging ecofriendly surface treatment. The salt bath nitriding is accompanied by the electrolysis process in the pretreatment step, and this whole processis called Pseudo-Electrolysised Salt bath Nitriding (PESN). The PESN creates only $NH_3$ and non-toxic salts without harmful $CN^{-}$ or toxic gas such as that found in previous salt bath nitriding. In general, ion nitriding and gas nitriding create high hardness and a strong brittle white layer on the surface. However, the PESN shows a thin white and gray layer. The PESN was applied to the defense material, 3%Cr-Mo-V steel, to study the surface characteristics at $480^{\circ}C$, $530^{\circ}C$, and $580^{\circ}C$ for 4 hrs, 20 hrs, 40 hrs, and 60 hrs of nitriding time condition. As a result, the best nitriding layer was found at $530^{\circ}C$ for 40 hrs. If we improve corrosion resistance and nitriding layer depth, the PESN will be able to be applied to the defense industry parts.

• Design & Manufacturing
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• 제8권2호
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• pp.23-29
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• 2014

Salt bath heat treatment is usually used but recently vacuum heat treatment is increased for the heat treatment of hot work die steels. The differences in two heat treatment processes were compared by testing the mechanical properties of heat treated products. With two different features of processes, mechanical properties such as hardness, tensile strength and impact strength of products show very different results. In this study salt bath heat treated products showed higher tensile strength and impact strength than vacuum heat treated products but hardness was not much different. These lower mechanical properties of vacuum heat treated products are due to differences in heating and quenching process.

• 한국군사과학기술학회지
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• 제13권2호
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• pp.275-282
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• 2010

The improved properties of surface layer can be achieved by so-called "new salt bath nitriding(NSBN)", which has been developed by a domestic company. This process based upon modified traditional salt bath nitriding process, increased hardenability with minimum toughness deterioration. This process also offers not only less white layer surfaces but also more eco-friendly one. That is, NSBN is the new eco-friendly surface treatment technology removing harmful $CN^-$ and toxic gas. According to the research of applying NSBN to Cr-Mo-V steel which has been used in defense industry, showed the improved result of wear resistance and surface hardening than non-coated condition. In further, we expect NSBN to curtail expenses and productivity improvement applied to the various defense industry parts.

• 소음진동
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• 제7권2호
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• pp.261-272
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• 1997

Recently washing machines are to be in lower vibration and lower sound because of better environment. Vibration problems in washing machines occur in both washing mode and spinning mode, but vibration in spinning mode becomes main problem because of its high rotating speed and continuity. Vibration while spinning is mainly due to rigid body motion of total washing system which includes suspending rods, washing bath, spinning bath, and gear sets. In this study, some researches were done in order to analyze the rigid body motion of washing system and flexible vibration of spinning bath. A basic mathematical model was established, and the effect of position of salt water and shape change of salt water case were considered. And the effect of lengths of suspending rods, attaching angles, vertical and horizontal position, stiffness of spring on the change of vibration were also considered. To identify the effect of salt water on vibration, some measurements were done. When salt water was positioned at upper part, the effect was most and this coincides with the tendency of simulation.

• 한국염색가공학회지
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• 제12권1호
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• pp.44-51
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• 2000

The conventional one bath exhaust dyeing system of nylon]/cotton blends with acid dye/direct dye involves a lot of neutral salt which affect dyeability of acid dyes. Because of conventional one bath exhaust dyeing system of nylonl/cotton blends with acid dye/direct dye needs acid dyes adjusted at a neutral liquor, suitable acid dye is limited. To improve dyeing property of nylon/cotton blends, cotton component was pretreated with cationizing agent containing chlorohydrine group in aqueous solution of sodium hydroxide. This study was carried out to investigate dyeing possibilities of nylon/cationized cotton blends with acid dye/direct dye in a non-neutral salt dyebath by one bath two step method. The concentration of direct dye was 1.0%, 0.7%, 0.3%o.w.f. respectively at a non, 1%, 3%owf of reserving agent for being almost equal color strength between nylon and 3% cationized cotton when nylon/3% cationized cotton blends was dyed with acid dye/direct dye at concentration of acid dye(1%o.w.f.) by one bath two step method.

• 한국표면공학회지
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• 제47권6호
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• pp.282-286
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• 2014

Wear characteristic of the nitrided SKD61 which is a typical mold material using for the extrusion of Al6061 alloy was investigated. The surface of SKD61 was nitrided by salt bath and plasma processes. The thickness of surface nitride layer was about $8.9{\mu}m{\sim}21.3{\mu}m$. Reciprocating friction wear test conducted using pin on disk type indicated the plasma treatment followed salt bath has a lower friction coefficient and a smaller adhesive wear with Al6061 alloy. That was identified by the $Fe_4N$ which has a better wear resistance than FeN mainly formed by plasma nitriding.

• Advances in materials Research
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• 제1권3호
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• pp.233-243
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• 2012

Thermal reactive diffusion coating of vanadium carbide on DIN 2714 steel substrate was performed in a molten borax bath at $950-1050^{\circ}C$. The coating formed on the surface of the substrate had uniform thickness ($1-12{\mu}m$) all over the surface and the coating layer was hard (2430-2700 HV), dense, smooth and compact. The influence of the kinetics parameters, temperature and time, has been investigated. Vanadium carbide coating was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction analysis (XRD). The corrosion resistance of the coating was evaluated by potentiodynamic polarization in 3.5% NaCl solution. The results obtained showed that decrease of coating microhardness following increasing time and temperature is owing to the coarsening of carbides and coating grain size.

• 자원리싸이클링
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• 제31권3호
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• pp.81-87
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• 2022

용융염 전해 채취 공정에서 가장 중요한 경제 지표 중 하나는 에너지 원단위(kwh/kg of metal)이다. 이는 외부로 손실되는 에너지와 전류 효율에 관련된다. 전류 효율은 전해온도에 의해 크게 좌우된다. 한편 염욕의 온도는 전해 초기에 염욕의 열수지 차이로 인해 급격히 상승하여 처음에 목표했던 전해온도와 상이해질 수 있다. 염욕의 의도치 않은 온도 변화는 전류 효율에 악 영향을 미친다. 따라서 전해 초기를 대상으로 열수지 검토를 통해 염욕의 온도 변화에 대한 계산치와 실측치를 비교해 보고 외부로 손실되는 에너지를 평가하는 것은 에너지 원단위를 줄이는 데 도움이 될 것이다. 본 논문에서는 저자들의 실험 데이터를 이용하여 용융염 전해 채취 중의 열수지에 대해 검토하였으며 이를 통해 외부로의 열 손실과 염욕의 온도 상승을 정량적으로 평가할 수 있었다. 이와 같은 방법을 통하면 열 손실을 줄일 수 있는 방안을 도출하고 전해온도를 제어하여 전류 효율을 제고시킴으로써 에너지 원단위를 줄일 수 있다.

• 한국염색가공학회지
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• 제10권2호
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• pp.18-28
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• 1998

in order to overcome disadvantage of the conventional two bath dyeing method of polyester/cotton blends, it had prompted significant effort to the development of the one bath dyeing method which can accomplish sayings in time, energy and water usage. Also, when dyeing polyester/cotton blends by the one bath dyeing method, the high salt concentrations needed for the reactive dye can cause particles of disperse dye, used for the polyester component, to aggregate. A supplementary problem that can occasionally be happened is the change of hue that occurs on dyed polyester in an alkaline dyebath. To improve dyeing property of polyester/cotton blends, cotton component was pretreated with epichlolohydrine-trimethylamine hydrochloride in aqueous solution of sodium hydroxide to produce a cationized cotton that can be dyed under neutral conditions with reactive dye in a non-electrolytic or il little electrolytic dyebath. The one bath dyeing method of polyester/cationized cotton blends with disperse dye/reactive dye mixture resulted in a satisfactory dyeing property and color yield in comparison with ordinary two bath dyeing method.