• 한국기계연구소 소보
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• 통권16호
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• pp.83-94
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• 1986

Grinding machine, one of the precision machine tool, requires high accuracy in spindle system. But, recent Inspection and Test reports by KIMM shows high inferio¬rity ratio in home-made grinding machines and points out that this is mainly due to the lack of design ability and assembling technique of spindle system. In this paper, therefore, static stiffness, dynamic characteristics, thermal defor¬mation and error motion of spindle system were studied. With these results, we presented the general data to design and assemble the spindle system. Test of spindle system modified by this study showed that several factors affecting machining accuracy were improved largely.

• 유공압시스템학회:학술대회논문집
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• 유공압시스템학회 2010년도 춘계학술대회
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• pp.18-24
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• 2010

Because of the increasing demand on the high precision and high response of a machinery, electronic control valves are widely adopted at various application fields. This paper studies on the static characteristic of a first-stage proportional pressure control valve. At first an experimental apparatus including hyd. pump variable speed inverter, pressure and data aquisition system was setted up with the experimental apparatus, various tests such as P-Q-W test, hyd, pump, dynamic, static, frequency response test of the proportional valve was carride out and the results are discussed.

• 연구논문집
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• 통권22호
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• pp.75-83
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• 1992

The beating motion of a high speed shuttleless loom is driven by cams. Two cams become one system and their shaft laid across each other. Moreover, the shape of the cams is very complex and requires high precision for successful weft insertion and good interlacing with warp yarn. The iterative contact method is developed for use in design and analysis of the driving mechanism of a disk type cam with oscillating roller follower. The optimum design is performed by utilizing a CAD program, DISKCAM. The 8th order polynomial is selected to interpolate the desired shape trajectory of the cam, the optimal shape of the cams is defined based on the demension of the follower. The kinematic motion of the beating cam mechanism is investigated. The phase angle is determined to achive harmonious cam motions

• 한국정밀공학회지
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• 제30권6호
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• pp.573-577
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• 2013

The one of the most important issue in roll-to-roll gravure printing is increase of ink transfer ratio or printability. As the result of high ink transfer ratio or printability, we can assess the quality of the printed patterns. The rheological properties are the important factors for the printability of electrodes patterning. In this study, the rheological properties of conductive ink are controlled by adding the solvent. The inks with different rheological properties are used for the patterning of the electrodes of $100{\mu}m$ by gravure printing equipment. The various printing speed, which also affect the rheological properties of conductive ink, is applied and the printed patterns are compared for their width and aspect ratio. Decreasing in the ink viscosity as well as increasing in the printing speed decreases the printability in gravure patterning, which shows that the rheological properties are important factors for the printability of gravure patterning.

• 한국정밀공학회지
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• 제29권2호
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• pp.156-160
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• 2012

Recently, the demands of the large scale machine tools gradually increase to machine the large parts, such as large scale crankshaft, yaw and pitch bearings for the wind power generator and the vehicle or aircraft components. But the high technology is necessary in order to develop the huge machine tools. Furthermore, the global market of it has been monopolized by a few companies. So, we need to develop the large scale machine tools and study its core technology to rush into the increasing market. In this study, we carried out the researches for the important core technology of a multi-tasking, machine tool; a large scale 5-axis machine tool of gantry type for multi-task machining. This study is focused on the design of large size gantry type multi-axis machine. In the case of large size of machine the cross rail deflection in the X-axis is significant. To reduce the deflection due to the eccentric spindle head, a special hollow type design in the cross rail with outside ram is adapted in this study. Also, the Zig-Zag motion in the Y-axis is inevitable with the gantry geometry, which is by the un-balancing, different motion at the left and the right columns moving. We tried to reduce the influence of Zig-Zag motion using FEM with different loading conditions at the left and the right side column.

• 한국재료학회지
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• 제15권11호
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• pp.705-710
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• 2005

NIL (nanoimprint lithography) technique has demonstrated a high potential for wafer size definition of nanometer as well as micrometer size patterns. During the replication process by NIL, the stiction between the stamp and the polymer is one of major problems. This stiction problem is moi·e important in small sized patterns. An antistiction layer prevents this stiction ana insures a clean demolding process. In this paper, we were using a TCP (transfer coupled plasma) equipment and $C_4F_8$ as a precursor to make a Teflon-like antistiction layer. This antistiction layer was deposited on a 6 inch silicon wafer to have nanometer scale thicknesses. The thickness of deposited antistiction layer was measured by ellipsometry. To optimize the process factor such as table height (TH), substrate temperature (ST), working pressure (WP) and plasma power (PP), we were using a design of experimental (DOE) method. The table of full factorial arrays was set by the 4 factors and 2 levels. Using this table, experiments were organized to achieve 2 responses such as deposition rate and non-uniformity. It was investigated that the main effects and interaction effects between parameters. Deposition rate was in proportion to table height, working pressure and plasma power. Non-uniformity was in proportion to substrate temperature and working pressure. Using a response optimization, we were able to get the optimized deposition condition at desired deposition rate and an experimental deposition rate showed similar results.

• 무역학회지
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• 제41권1호
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• pp.159-186
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• 2016

본 연구는 1991-2012년간 동아시아 국가 간 산업별 부품무역의 비교우위를 분석하여, 동아시아 FTA 체결 시 예상되는 무역과 생산분할 구조를 분석한다. 분석기간 중 동아시아 내 부품무역의 상호의존도는 지속적으로 증가하여 왔으며, 동아시아 FAT 체결 시 구조적 변화가 없다면 한국과 일본이 동아시아 내 전기 및 전자기기, 수송기기 부품수출을 더 강화하고, 중국과 ASEAN이 최종재를 수출하는 구조는 유지될 것으로 예상된다.

• 한국유체기계학회 논문집
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• 제19권1호
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• pp.24-30
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• 2016

In this study, a 2W micro-gas turbine engine was designed using micro-electro-mechanical systems (MEMS) technology, and experimental investigations of its potential under actual combustion conditions were performed. A micro-gas turbine (MGT) contains a turbo-charger, combustor, and generator. Compressor and turbine blades, and generator coil were manufactured using MEMS technology. The shaft was supported by a precision computer numerical control (CNC) machined static air bearing, and a permanent magnet was attached to the end of the shaft for generation. A heat transfer analysis found that the cooling effect of the air bearing and compressor was sufficient to cover the combustor's high temperature, which was verified in an actual experiment. The generator performance test showed that it can generate 2W at design rotational speed. Prototype micro-gas turbine generated maximum 1 mW electric power and lasted up to 15 minutes.

• 한국군사과학기술학회지
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• 제21권5호
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• pp.607-613
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• 2018

Hydraulic systems are widely used in the field of defense, construction machinery, agricultural machinery, and general industries, due to various advantages such as quick response speed and precision control. The defense equipments such as light rescue vehicle is operated in very harsh environments, so hydraulic components used in defense equipment are required to have very high reliability. In particular, hydraulic piston pump is very important component in a hydraulic systems, so life prediction of pump is essential. Therefore, in this study, we analyze the potential failure and the main failure mode of the hydraulic piston pump for the light rescue vehicle through the FMEA analysis, and predict the life of the pump by the accelerated life test considering the usage conditions.

• 한국유체기계학회 논문집
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• 제2권2호
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• pp.19-26
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• 1999

Thermal output in a nuclear power plant is verified with calorimetric heat balance on the secondary plant. The calorimetry involves the precise measurement of the feedwater flow rate. However, the correct indication of feedwater flow rate obtained by a pressure-difference measurement across a venturi can be affected by instrument errors, fouling or a poorly developed velocity profile. This can result in an inaccurate mass flow rate and consequently an inaccurate estimate of power. The purpose of this study is to develop verification methods with accuracy better than $0.5\%$ for high precision flow measurement to be used for measuring feedwater flow rate. This chemical tracer method is a testing process that uses tracers which can be applied to quantify losses in electrical output due to the incorrect measurements of feedwater flow rate. And this system has good response to the variation of the flow rate. Accuracy of better than 0.5 percent can be expected for feedwater flow measurement, providing that the system can be stabilized during the test. This methodology is applicable to other flow systems well.