• 한국가정과학회지
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• 제8권1호
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• pp.19-24
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• 2005

This paper is to know the possibility of coloration of synthetic fibers with loess. Fabrics woven with polyester, nylon, and acrylic fibers were dyed by a dip-pad operation with a laboratory mangle. Drying, curing at 180$^{\circ}C$ for 10 minutes and washing were followed. Effect of curing after drying were investigated in terms of K/S values and SEM microphotographes. Reddish-yellow(a:75.13, B:15.14, ${\Delta}$E:45.31) colored fabric ascertain possibility of coloration of synthetic fibers with loess. Acrylic fiber shows highest dye uptake of the three kinds of fibers and fastness increases by curing after drying.

• 동력기계공학회지
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• 제5권3호
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• pp.48-55
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• 2001

In many applications. rubber components undergo dynamic stresses or deformations of fairly large magnitude. Since rubbers are not fully elastic, a part of the mechanical energy is converted into heat due to the hysteresis loss. Heat generation without adequate heat dissipation leads to heat build up. i. e. internal temperature rise. The purpose of this paper is to predict temperature rise caused by the hysteresis loss, in a rubber pad subjected to complex dynamic deformation. In this unsteady thermal analysis, the temperature distributions of track components are displayed in contour shapes and the temperature variations of some important nodes are represented graphically with respect to the running time of the tank.

• Tribology and Lubricants
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• 제26권4호
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• pp.219-223
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• 2010

Despite the increasing need of nanometer-scale accuracy in abrasive machining using ultrasmall particles such as abrasive jet and chemical mechanical polishing(CMP), the process mechanism is still unknown. Based on the background, research on the effects of various process parameters on the machined surface at abrasive machining was motivated and performed by using finite element analysis where the effect of slurry fluid flow involved. The effect of particle shape on the machined surface during particle-surface collision was discussed in this paper. The results from FEA simulation revealed that any damage or defect generation on machined surface by the impact may occur only if the particle has enough impact energy. Therefore, it could be concluded that generation of the defects and damage on the wafer surface after CMP process was mainly due to direct contact of the 3 bodies, i.e., pad-particle-wafer.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.769-772
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• 1995

Most turbo machines, which operate at high speeds, such as gas turbines, jet engines, pumps, and compressors are prone to perrturbing vibrations. The best vibration control method for rotors is to eliminate destabilizing factors. Careful balancing application of "more stable" oil-lubricated bearing, such as tilting pad bearings or use of anti-swirl devices in seals, are examplse of passive vibration control methods. the use of magnetic bearing is an active control method. An obvious advantage of active control is that it provides damping (or modifies system stiffness or other parameters) only when there is a need for that, i.e., in emergency states, while not affecting the rotor normal operational conditions. Moreover, active control methods provide exact position control through on-line control. In this study, a magnetic actuator, digital contrliier using DSP, and bipolar operational power supply/amplifiers were developed to show the effectiveness of reducing robot vibration. Also the curve fitting procedure to obtain the transfer function of frequency dependent component was developed. Results presented in this dissertation will provide a well-defined technical parameters in designing magnetic damper system.er system.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.90-96
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• 1998

There are various noises generated by friction. Among the rest, eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. The parameters affecting brake squeal noise are the material properties of the braking pad, the dynamic properties of the brake parts and the dimensions of the brake assemble etc. Also, the squeal noise changes its inherent form(i.e. its sound pressure level and its frequency) with the normal load and sliding speed. In this study, the characteristics of brake squeal noise generated by friction is analyzed experimentally. The experiment focused on the analysis of friction self-excited vibrationand squeal noise level. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding speeds. And Friction self-excited vibration is raised the brake squeal noise.

• 천문학회지
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• 제31권1호
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• pp.39-50
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• 1998

We present UBV CCD photometry of Be 2, previously unstudied open cluster. Our photometry covers a field of $3'.2\times3'.8$ of the sky centered on the cluster, which is slightly smaller than the cluster diameter estimated to be about 260'. We have determined the reddening, distance, age and metallicity of the cluster by fitting the Pad ova isochrones to the observed stellar distributions in color-magnitude diagram as well as main sequence fitting: $E(B-V)=0.8\pm0.05,\;(m-M)_o=13.6\pm0.1,\;log(t) =8.9\pm0.1$, and Z=0.008. The present photometry shows that Be 2 is a distant open cluster of intermediate age. that it is a distant intermediate-age open duster.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.873-878
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• 2000

Semiconductor packaging technology is changed rapidly according to the trends of the micro miniaturization of multimedia and information equipment. For I/O limitation and fine pitch limitation, DIP and SOP/QFP are replaced by BGA/CSP. This is one of the surface mount technology(SMT). Solder ball is bumped n the die pad and connected onto mounting board. In ball bump formation, vacuum suction type ball alignment process is widely used, However this type has some problems such as ionization, static electricity and difficulty of fifo(first-input first-out) of solder balls. Seesaw type is reducing these problems and has a structural simplicity and economic efficiency. Ball cartridge velocity and ball aligned plate angle are Important variables to improve the ball alignment Process. In this paper, seesaw-type CSP solder ball loader is developed and the optimal velocity and plate angle are proposed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.361-364
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• 2002

In this paper, we propose a new method to deal with the optimized auto-tuning for the PID controller which is used to the process-control in various fields. First of all, in this method, 1st order delay system with dead time which is modelled from the unit step response of the system is $Pad'{e}$-approximated, then initial values are determined by the Ziegler-Nickels method. So deciding binary strings of parents generation using by the fitness values of genetic algorithms, we perform selection, crossover and mutation to generate the descendant generation. The advantage of this method is better than the Ziegler-Nickels method in characteristic of output, and has extent of applying without limit of K, L, T parameters.

• Ocean Systems Engineering
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• 제6권1호
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• pp.117-128
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• 2016

A theoretical study of Boussinesq equations (BEs) for internal waves propagating in a two-fluid system is presented in this paper. The two-fluid system is assumed to be bounded by two rigid plates. A set of three equations is firstly derived which has three main unknowns, the interfacial displacement and two velocity potentials at arbitrary elevations for upper and lower fluids, respectively. The determination of the optimal BEs requires a solution of depth parameters which can be uniquely solved by applying the $Pad{\acute{e}}$ approximation to dispersion relation. Some wave properties predicted by the optimal BEs are examined. The optimal model not only increases the applicable range of traditional BEs but also provides a novel aspect of internal wave studies.

• TTA 저널
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• 통권130호
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• pp.24-29
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• 2010

최근 전자책 시장이 활성화 된 계기는 잘 알다시피 2007년 아마존에서 킨들(Kindle)이란 전자책 단말기를 출시하고 부터이다. 전자잉크(e-Ink) 디스플레이 화면 기술을 적용하여 매우 가볍고 읽기 편한 화면의 단말기를 출시하였다. 2008년에는 빈스앤노블에서 Nook라는 단말기를 출시했으며 올해 4월에는 애플에서 LCD 화면에 태블릿 형태의 아이패드(iPad)라는 단말기를 출시해 사용자들의 획기적인 반응을 얻고 있다. 단말기 하드웨어가 전자책 시장의 중요한 성공요인 중에 하나이지만 이에 못지않게 콘텐츠의 확보와 서비스 모델이 중요하다. 이들 회사는 도서유통에서 시작해 다량의 전자출판 콘텐츠를 확보하고 또한 독자들이 용이하게 콘텐츠에 접근하도록 서비스하고 있다. 전지출판물 콘텐츠 시장에서 사용자들이 원하는 콘텐츠를 제작업체나 공급업체에 독립적으로 서비스 받으려면 콘텐츠 포맷과 DRM 기술 등에 대한 표준화가 지원되어야 한다. 이러한 표준화를 통하여 저자가 작성한 전자책 콘텐츠를 어느 출판사든 사용할 수 있어야 하며, 어느 유통사를 통해서든 최종 독자들에게 근본적인 변환 없이 서비스될 수 있어야 한다. 이번 특집호에서는 최근 주목을 받고 없는 전자출판물 시장의 동향을 살펴보고 국내에서의 전자출판물 육성방안, 전자책 포맷의 표준화 동향, 디지털교과서 표준화 동향, 그리고 전자출판 서비스 및 솔루션 기술에 대해 살펴보기로 한다. 이를 통해 전자출판물에 대한 이해를 돕고 향후 전자출판물 시장이 성장하는데 도움이 되기를 기대한다.