• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.461-462
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• 2006

This paper reports on the development of a scanning probe microscopy(SPM) tip with caborn nanotubes. We used an electric field which causes dielectrophoresis(DEP), to align and deposit CNTs on a metal-coated SPM tip. Using the CNT attached SPM tip, we have obtained an enhanced resolution and wear property compared to that from the bare silicon tip through the scanning of the surface of the bio materials. The carbon nanotube tip align toward the source of the ion beam allowing their orientation to be changed at precise angles. By this technique, metal coated carbon nanotube tips that are several micrometer in length are prepared for scanning probe microscopy.

• 한국생산제조학회지
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• 제21권6호
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• pp.860-864
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• 2012

The contact tip is higher the wear of resistance and the longer life are demanded to GMA welding process. In this study, four different contact tips with three different compositions by two wires were evaluated their wear resistance by measuring in every one hour the area of enlarged hole at the exit side during actual wleding. Experimental results clearly showed that the Cr-containing tips strengthened by precipitation hardening have much better resistance to wear than those made by work hardening. In addition, flux cored wire is excellent abrasion resistance test results showed. Based on these results, the domestic industry, the life of the contact tip to know will be used as basic data.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.65-75
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• 2001

Modern vehicles require a high degree of refinement including good driveability. Vehicle driveability, which becomes a key decisive factor f3r marketability, is affected by many parameters such as engine control and the dynamic characteristics in drive lines. Therefore engine and drive train characteristics should be considered to achieve a well balanced vehicle response simultaneously. This paper describes experimental procedures which have been developed to measure engine torque and investigate shuffle characteristics. To analyze the vehicle dynamic behavior, fractional torques and inertia mass moment of engine, and drive train were measured. Shuffle characteristics during tip-in condition were investigated in an experimental vehicle at 2nd and 3rd gear stages. It was found that the shuffle characteristics were caused by sudden changes of engine torque and have a different vibration frequency with gear stage variation. Inertia mass moment of engine including flywheel rotation showed a key factor for the shuffle characteristics.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.101-116
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• 2002

Modern vehicles require a high degree of refinement, including good driveability to meet customer demands. Vehicle driveability, which becomes a key decisive factor for marketability, is affected by many parameters such as engine control and the dynamic characteristics in drive lines. Therefore, Engine and drive train characteristics should be considered to achieve a well balanced vehicle response simultaneously. This paper describes analysis procedures using a mathematical model which has been developed to simulate spark timing control logic. Inertia mass moment, stiffness and damping coefficient of engine and drive train were simulated to analyze the effect of parameters which were related vehicle dynamic behavior. Inertia mass moment of engine and stiffness of drive line were shown key factors for the shuffle characteristics. It was found that torque increase rate, torque reduction rate and torque recovery timing and rate influenced the shuffle characteristics at the tip-in condition for the given system in this study.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1004-1008
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• 2003

Near-filed optical storage using cantilever aperture tip is a promising way fer next generation optical data storage. To enhance the speed of reading and writing data, gap between tip and media should be controlled fast and precisely within near field region. In this paper, several PZT actuators are analyzed far constructing dual servo control algorithm: coarse actuators(stact. PZT, bimorph PZI) for media surface inclination and One actuator(film PZT) for media surface roughness. Dynamic analysis of stack PZT, bimorph PZT, and film PZT are performed through the frequency response. Based on the frequency response and mathematical model, fast analog controller is designed.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.160-163
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• 2010

부분흡입형 초음속 터빈의 노즐과 1단 로터 사이의 축방향 간극이 터빈의 단 성능과 유동장에 어떤 영향을 미치는지 알아보기 위해 터빈에 대한 3차원 유동해석을 수행하고 그 결과를 분석하였다. 상용 유동해석 프로그램 $FLUENT^{TM}$를 사용하였으며 다섯 가지 경우의 축간극에 대해 계산을 하였다. 노즐-로터 축간극이 팁 누설 유량의 증가와 로터 출구의 유동각에 영향을 주는 것을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.540-545
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• 2001

In this paper dynamic responses of an engine, which is supported by hydraulic mount, to throttle tip-in/tip out are analyzed. Because the hydraulic mounts have non-linearity which the characteristics of stiffness and damping vary with frequencies, it is difficult to analyze the dynamic behavior of an engine using general integral algorithms. Convolution integrals and relationships between unit impulse response functions and frequency response functions are therefore used to simulate the transient behavior of an engine indirectly. In time domain, impulse response functions are calculated by two-side discrete inverse Fourier transform of frequency response function achieved by Laplace transform of equations of motion. Considering the fact that the shapes of behavior of an engine simulated by the proposed method are in good agreement with test results, it is confirmed that the proposed method is very effective for the analysis of transient response to throttle tip-in/out of an engine with hydraulic mounts.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1126-1129
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• 2004

Because of the various length condition of carbon nanotube, it is very confined the application area of the single CNT tip. In this paper, it was proposed the cutting technique of single CNT tip and the relationship between the etched volume and the amount of the applied charge. It is possible to control the length of single CNT tip arbitrary using this technique. The etched volume and length in the single CNT tip can be predicted with the amount of the applied charge. It is very easy to make a single CNT tip with proper length using this technique and to make nanotweezer that was composed two single CNT tips.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1189-1194
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• 2004

In this paper, the effect of tip clearance on the cooling performance of the microchannel heat sink is presented under the fixed pumping power condition. For the various types of microchannel heat sink having different size of fin width and channel width, experimental study is conducted. Through the experiment, the tip clearance effect is investigated by increasing tip clearance from zero. As a result, it is shown that cooling performance of heat sink with tip clearance is better than that of heat sink without tip clearance. For the microchannel heat sink with tip clearance, the optimum conditions for cooling performance is also studied.

• 한국기계가공학회지
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• 제11권6호
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• pp.183-188
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• 2012

This study was carried out to design the spray nozzle tip for airless spray coating. Airless spray coating is the process of coating an object with a liquid spray of paint or other fluid. The nozzle tip controls the fluid flow rate and creates back pressure in the system. The nozzle tip also defines the spray pattern by the size and shape of the orifice. The spray pattern of nozzle tip was investigated numerically using ANSYS CFX ver. 14.0. It was observed that performance result of designed nozzle tip was correspond well, compared with that of GARCO nozzle tip.