• 한국전기전자재료학회논문지
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• 제14권9호
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• pp.707-713
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• 2001

As the integrated circuit device shrinks to smaller dimensions, chemical mechanical polishing (CMP) process was requirdfo the global planarization of inter-metal dielectric (IMD) layer with free-defect. However, as the IMD layer gest thinner, micro-scratches are becoming as major defects. However, as the IMD layer gets thinner, micro-scratches are becoming as major defects. Micro-scratches are generated by agglomerated slurry, solidified and attached slurry in pipe line of slurry supply system. To prevent agglomerated slurry particle from inflow, we installed 0.5${\mu}{\textrm}{m}$ point of use (POU) filter, which is depth-type filter and has 80% filtering efficiency for the 1.0${\mu}{\textrm}{m}$ size particle. In this paper, we studied the relationship between defect generation and polished wafer counts to understand the exact efficiency fo the slurry filteration, and to find out the appropriate pad usage. Our experimental results showed that it sis impossible to prevent defect-causing particles perfectly through the depth-type filter. Thus, we suggest that it is necessary to optimize the slurry flow rate, and to install the high spray bar of de-ionized water (DIW) with high pressure, to overcome the weak-point of depth type filter.

• 한국정밀공학회지
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• 제15권6호
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• pp.22-32
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• 1998

This paper describes a research work of developing a computer-aided design of irregularly shaped-sheet metal product with bending and piercing operation for progressive working. An approach to the CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of five main modules, which are input and shape treatment, flat pattern-layout, production feasibility check, blank-layout, and strip-layout module. Based on knowledge-based rules, the system is designed by considering several factors, such as radius and angle of bend, material and thickness of product, complexities of blank geometry and punch profile, and availability of press. This system is capable of unfolding a formed sheet metal part to give flat pattern and automatically account for the adjustment of bend allowances to match tooling requirements by checking dimensions and the best utilization ratio of blank-layout within bending production feasibility area which is beyond ${\pm}30^{\circ}$ degrees intersecting angle between grain flow and bending edge line and which is suitable to progressive bending operation. Also the strip-layout drawing generated by a bending and a piercing operation according to punch profiles divided into automatically for external area of irregularly shaped-sheet metal product is displayed in graphic forms.

• 한국대기환경학회지
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• 제19권3호
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• pp.297-306
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• 2003

Works were focused on back pressure characteristics of ceramic fiber filter on DPF (Diesel Particulate Filter) system and experiments were performed to select appropriate filter which can filter particulates. Filters were installed on metal -support tube which has openings for exhaust gas flow. Ceramic fiber filters with high specific surface area and adequate high temperature strength are commercially available for filtration of diesel particulates and in -situ hot regeneration. Thus, ceramic blanket and ceramic board which are used as insulating media were applied to filter and filtration apparatus was installed on exhaust gas line connected to 2.0 L diesel engine. Alternating filter structure to adapt DPF system, collection efficiency test of diesel particulates was measured. In case of ceramic blanket, pressure drop was low, caused by the destruction of soft structures. Also, particulate collection efficiency was decreased depending on loading time. In case of ceramic board, structure design was altered to reduce back pressure on DPF system. Structure design was altered to induce Z-flow by making 10 mm and 5 mm holes on the surface of media. Alteration of 5 mm hole showed that media have low back pressure but particulate collection efficiency was 77%, while 10 mm hole showed that of 90%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1475-1480
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• 2007

In the last few years, lasers have found new applications in production engineering as tools for surface treatment, cutting, welding, drilling and marking. So far, the laser has mainly been used in special laser processing machines ('laser-only') directly integrated into a production line or serving as stand-alone stations in the workshop. By combining conventional metal cutting technologies with laser processes in one machine, complete processing of a workpiece with different technologies in one setting can be realized. The main advantages are a reduction of the material flow between the production machines, which leads to a reduction in processing time and logistics, and an enhancement of manufacturing quality due to the processing in one setting. In addition to this approach new processing technologies such as laser-assisted machining are possible.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.258-261
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• 2000

Geophysical surveys (electrical resistivity, self-potential, and magnetic methods) and streamwater sample analysis have been carried out at a site of tailings of waste deposits in an abandoned mine, Jangpoong, which is situated in Kowesan-Gun, Chungbuk-Do. The research was aimed at investigating the suitability of the various geophysical methods for detection of AMD (acid mine drainage) paths, and ultimately mapping of preferred AMD flow channels by incorporating the water sample analysis. Electrical resistivity section from the dipole-dipole line represents the low-resistivity zone trending northwest toward the stream nearby. The positions of the resistivity anomalies for AMD channels are well correlated to the ones from the various geophysical surveys. In addition they correspond to the sites of the higher peaks for the pH, EC, heavy metal content for the water sample data.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.81-87
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• 2006

In this paper, the belt-pulley mechanical loss is investigated. A bondgraph model for the mechanical loss is developed from the viewpoint of the power flow by assuming that all power losses are attributed to the torque loss. The mechanical loss model consists of transient and steady state part. The coefficients of the power loss model are obtained from the experiments. It is found from the simulations and experiments that the steady state loss depends on the line pressure, input torque and rotational speed while the transient loss depends on the rotational speed, shift speed and the inertial torque.

• 융복합기술연구소 논문집
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• 제3권2호
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• pp.17-21
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• 2013

Hot cross wedge rolling process as an incremental forming has many advantages such as the material usage, the short process time, the automatic equipment line and the low forming load. However, it occurs some defects such as the surface groove, the axis warping and the Mannesmann hole. In this paper, the defect of the Mannesmann hole was carried out. Finite element analysis was utilized to reveal the stress distribution, the rotation of the specimen and the change of section profile. Cross wedge rolling experiment was also conducted on the generation of the Mannesmann hole. It was demonstrated according to the spreading angle with respect to the various types of material. In the view point of metal flow, the smaller forming angle and the larger spreading angle increase opportunities of the defect hole generations.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1040-1044
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• 1999

A micro porous PTFE membrane desolvator (MMD) was built and evaluated for the on-line removal of organic solvents to facilitate the determination of trace metal contaminants in the solvents by ICP-AES. Three organic solvents, isopropyl alcohol (IPA), methanol, and dimethy sulfoxide (DMSO) were studied. The MMD reduced organic solvent concentration in the sample aerosol stream by 82% to 89%, as indicated by monitoring C(I) emission. Net signal intensity of Fe, Al, and Cu was increasing with higher organic solvent concentration, with the rate of increase being solvent dependent. The signal intensities for Mg and Pb followed the trend with the C(I) signal. Changing the sweep gas flow rate affected the optimum signal intensity. Wine samples were analyzed by the method of standard addition. The concentrations of B, Al, and Mg were determined with a relative precision of less than 2.3%.

• 에너지공학
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• 제11권1호
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• pp.18-25
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• 2002

침부식 (FAC, Flow-Accelerated Corrosion)에 의한 감육 문제는 원자력 발전소 배관관리에 있어서 매우 중요하다. 특히 FAC는 배관 내부 유체의 pH, 용존산소 농도, 유체 온도, 유속 및 습증기 분율 등과 배관의 형상 및 재료 등의 특정 조건에서만 발생하므로, FAC 문제를 관리하기 위해서는 체계적인 접근이 필요하다. 본 연구에서는 국내 특정 CANDU원전의 2차계통 배관을 대상으로 관련 데이터베이스 구축, 구축된 데이터베이스를 이용한 FAC감육율의 예측 및 배관 잔여수명의 평가 등을 수행하였다. 또한 FAC 발생기구 및 FAC에 영향을 주는 요인에 대해서도 조사하였다. 습분분리기와 플래시탱크 사이 배관 라인의 해석 예로부터 FAC 문제를 관리하는 방안을 제시하였다. 제시된 방안은 국내 다른 원자력발전소의 배관 관리에도 활용될 수 있을 것이다.

• 한국전자파학회논문지
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• 제29권7호
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• pp.477-483
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• 2018

본 논문에서는 FM 방송대역(88~108 MHz)에서 동작하는 자동차 전면 글래스 상에 설계되는 투명 안테나를 제안한다. 투명 안테나는 전형적으로 차량 지붕에 설치된 샤크핀 안테나의 공간적 제한을 피하기 위해 차량 전면 글래스에 구현하였다. 전면 글래스에 설계되는 안테나는 낮은 수심감도와 다른 서비스대역의 안테나로부터의 방사간섭 문제를 합리적으로 해결할 수 있다. 전면 글래스는 고유한 closed-line 구조를 가지고 있으며, 이 구조로 인해 전면 글래스 외곽의 차체 표면으로 전류가 흐르게 되어 FM 방송대역 이전 부분에서 첫 공진점이 발생한다. Closed-line 구조를 이용한 표면 전류 길이 제어를 통해 첫 공진점이 FM 대역에서 동작하는 안테나를 설계하였다. 또한, RF 수동소자로 설계하기 적합한 투명전극 소자 마이크로 메탈메쉬 필름의 투명성을 통해 시각적 인식의 최소화 하였다. 측정된 안테나는 FM 대역에서 반사계수는 -6 dB 이하이며, average peak gain은 -0.9 dB이다. 본 연구를 통해 제안된 전면 글래스 투명안테나는 미래의 자동차 안테나 개발에 필요한 공간과 설계 자유에 대한 가능성을 보여주었다.