• 전기학회논문지
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• 제61권4호
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• pp.585-589
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• 2012

The characteristics of interface layer and the effect of mole fraction of inlet gas mixture($B_2H_6/H_2/N_2/TiCl_4$) on the microstructure of Ti(B,N) films were studied by microwave plasma hot filament CVD process. Ti(B,N) films were deposited on a substrate(STD-61) to develop a high performance of resistance wear coating tool. Ti(B,N) films were obtained at a gas pressure of 1 torr, bias voltage of 300 V and substrate temperature of $480^{\circ}C$ in $B_2H_6/H_2/N_2/TiCl_4$gas system. It was found that TiN, $TiB_2$, TiB and hexagonal boron nitride(h-BN) phases exist in thin layer on the STD-61.

• Tribology and Lubricants
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• 제12권3호
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• pp.48-54
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• 1996

Examined in this paper, is the effect of B$_{4}$C addition on the frictional characteristics of Cu-Sn based sintered friction materials. For the specimens 1wt%, 2wt% and 4wt% of B$_{4}$C were added into the reference material. A pin-on-disk type friction tester was used to,measure the friction torque with respect to the surface temperature and sliding distance. Wear mechanism of each specimen is analyzed in the view point of the oxide film formation. The specimen containing 4wt% of B$_{4}$C showed stable friction and low wear since the oxide film was sustained up to higher surface temperature ranges.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.898-901
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• 2000

It is known that Si3N4 ceramic insert has less hardness than Al2O3 ceramic insert. But Si3N4 ceramic insert has not only high toughness and strength but also low thermal expansion coefficient, which makes it has longer tool life under thermal stress condition. In this study, commercial Si3N4 ceramic insert and home-made SiC-Si3N4 ceramic insert which has different sintering time and chemical composition is tested under various cutting conditions. The experimental result is compared in terms of tool life and cutting force. Generally, As the cutting speed and the feed rate increased, the cutting force and the flank wear increased too. The performance of SiC-Si3N4 ceramic insert shows the possibility to be a new ceramic tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.817-821
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• 1997

Ever since the nonlinearity of machine tool dynamics was established, researchers attempted to make use of this fact to devise better monitoring, diagnostics and system, which were hitherto based on linear models. Theory of chaos, which explains many nonlinear phenomena comes handy for furthering the analysis using nonlinear model. In this study, measuring system will be constructed using multi-sensor (Tool Dynamometer, Acoustic Emission) in end millingprocess. Then, it will be verified that cutting force is low-dimensional deterministic chaos calculating Lyapunov exponents, Fractal dimension, Embedding dimension. Aen it will be investigated that the relations between characteristic parameter caculated form sensor signal and tool wear.

• 한국철도학회논문집
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• 제8권5호
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• pp.483-489
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• 2005

Railway wheel/rail contact conditions have influences on dynamic behavior of the rolling stock. If there are incompatibility problems between the wheel and rail, damages like wheel wear, wheel spalling, rail wear, etc are occurred. Especially wheel and rail profiles are important factors of vehicle curving performance, so compatibility studies between wheel and rail profiles have to be carried out preferentially. In this study, we have studied the compatibility between wheel and rail profiles of KNR conventional line to analyze the dynamic performances of the rolling-stock. Thus we showed the results relating to wheel/rail geometric contact, vehicle running performances as the change of wheel/rail combination.

• Tribology and Lubricants
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• 제29권4호
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• pp.242-247
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• 2013

This study aims to establish the fundamental basis for the design of materials used in high-speed trains, by using a lab-scale dynamometer to evaluate the characteristic behavior of metallic sintered friction materials in relation to the shape of graphite. The test results clearly demonstrate that when flake graphite and granular graphite are added equivalently, the average coefficient of friction is much lower, and it is less influenced by speed variation; moreover, friction wear is observed to be insignificantly low. Adding flake graphite increases the coefficient of friction, which leads to higher friction wear. In addition, the roughness of the disc surface was equivalent regardless of the shape of the graphite.

• 한국세라믹학회지
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• 제32권9호
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• pp.1027-1032
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• 1995

SiC had been widely applied for mechanical sealing as a sealing material. SiC sintering is commonly made of reaction sintering, presureless sintering, and hot isostatic pressing (HIP) sintering. In this investigation, however, clay bonded sintering was used to avoide any complications of the special sintering methods as mentioned above. In order to prevent harmful SiC oxidation in the clay bonded sintering, clay and frit were used to form the SiC oxidation protecting layer and graphite was added to provide high solid lubricity. As a result, the material with 6% clay (clay 5.4% and frit 0.6%) and 2~4% graphite (45 mesh) sintered at 140$0^{\circ}C$ for 3 hours, showed the following physical properties; porosity 6%, static friction coefficient 0.15, kinematic coefficient 0.1,. and specific wear rate 4.8$\times$10-8 $\textrm{mm}^2$kgf-1. On the other hand, the flexural strength was 900kgf/$\textrm{cm}^2$. This tribological characteristic properties were similar to those of the reaction sintered SiC except the flexural strength.

• 한국기계가공학회지
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• 제11권6호
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• pp.139-144
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• 2012

In the automobile industry, the various efforts to lower their industrial cost and enhance fuel efficiency have been made through process improvement or weight saving of automobile parts. Gear is one of significant parts of transmission, which is made by cast iron or alloy steel. It is expensive due to complex processing, inferior materials and large machining allowance. In this study, alternative gear cars oil which is based on fluid applications materials is produced by reducing surface induction hardening and carburizing hardened in production. And then, wear characteristic and mechanical properties such as hardness of the sintered alloy which is used as a substitute for small machining allowance is investigated.

• 한국생활과학회지
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• 제23권3호
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• pp.515-527
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• 2014

This study is intended to develop the creative and high value-added products as well as the development of diversity for jump suit for the future by analyzing the trend and feature shown in jump suit in the modern fashion. In the research methodology, the analysis was carried out over a total of 351 work pieces on jump suit among those presented in the collection of Paris, Milan, New York and London from 2006S/S to 2013F/W as well as literature review. The aesthetic features on suit jump design introduced in the modern fashion could be characterized as the following. First, both upper and lower garments are composed with a simple array of items and the stress was put on modernity feature through minimal expression technique. The feature of solid simplicity was also given with achromatic color or neutral monochrome. Second, the feminity image was emphasized with adoption of such highlighting items as detailed add-ons, tops, camisoles and blouses that stress the organically curved streamline including silhouette, material itself, crease and drape that enable the direct and indirect exposition of human body and the expression of smooth curve in human body. Third, jump suit revealed the multipurpose feature as item available for the diverse wear such as working habiliment, sports wear, uniform, office wear and evening wear, depending on the terms and conditions. Fourth, the deconstructive characteristic appeared through integration with various items, destruction of formative structure, non-structural shape, and ambiguity in wearing method.

• 한국의류산업학회지
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• 제20권4호
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• pp.449-456
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• 2018

This study conducted a survey of members at sports climbing centers on the purchasing and wearing conditions of sports climbing wear and design preferences. 140 participants were in their 20's and 30's, and many of them engaged in sports climbing activities over 20 times a month. They put emphasis on the motion adaptability, durability, price and functional material when purchasing a climbing wear. However, only 23% of them used sports climbing wear. The reasons for wearing sports climbing wears were suitability for physical activity, comfort, and design. On the other hand, the reasons for not purchasing them were expensive prices and lack of designs. They experienced inconveniences at sleeves and waist in shirts. In case of pants, participants experienced inconveniences with the knee and thigh when they climbing. Concerning the damage of shirts, the majority experienced the elbow part was worn out, and the knee part was either worn out or torn at pants. Design preference results showed participants preferred loose-fit short-sleeved shirts that could cover half of the hip. In case of pants, they preferred basic-fit long trousers and basic hems with no functional characteristic. 3 sports climbing instructors answered that climbing wears should put emphasis on deodorization and antimicrobial effects as well as durability and suitability for physical activity. They also pointed out limitations in price and design and presented opinions about creating various sizes for different body parts by taking into account the growth of muscles.