• International Journal of Precision Engineering and Manufacturing
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• 제3권1호
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• pp.20-25
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• 2002

Electrical damages to critical parts in rotating machinery have caused many machinery failures and hours of costly downtime. The problem of shaft currents generated in non-electrical machines has puzzled both users and manufacturers of these machines. The main solution for preventing electromagnetic type damage is to demagnetize all of the machinery parts, however this is costly and time consuming. Therefore a thorough investigation into the causes and physical characteristics of electromagnetic shaft currents is needed. In this paper, the self excitation theory was developed far a simple model, an axial flux Faraday disk machine surrounded by a long solenoid. Experimental tests were conducted to investigate the physical characteristics on an electromagnetic self excitation rig. The theory showed that the directions of both the shaft rotation and the coil turns should be identical if self excitation is to occur. From the tests, the electromagnetic type shaft current had both AC and DC components occurred at all vibration frequencies. This could point to a way to detect small instabilities or natural frequency locations by monitoring shaft currents.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
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• pp.143-151
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• 2000

Dissolved silica is make some critical trouble at steam turbine. And, we must measure it to ppb level. We were looking for the best measuring method of the silica. Via this study, we could found it in the N-IR spectroscopy technology. This dissertation have been discuss about system structure, system fundamentals and performance test. At the test, we were study in the spectral interference of $NH_3$. We know that existing system had some problem. It is structural frailties of single beam type. Therefore we were study for double beam type structure. And we obtain a good result. In the result, it have been discuss that conduct a test of $NH_3$ effect.

• 한국자동차공학회논문집
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• 제4권3호
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• pp.220-231
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• 1996

In this research, we use IDI type constant volume combustion chamber which may make up stratified combustion to construct the design back data of lean-burn engine. Some experiments are conducted by the passagehole angle in the adapter of main chamber and sub-chamber. The effects on the combustion characteristics according to the ignition timing are investigated. The used fuel is methanol prospective for alternative fuel. Fuel is injected under 10.78MPa using solenoid and accumulator. As the results of the experiment, combustion characteristics reveals that ignition timing, passagehole angle and shape greatly effects on. Lean inflammability limit is extended to 0.45 in equivalence ratio.

• 한국염색가공학회지
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• 제12권4호
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• pp.233-238
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• 2000

In this study, the control system of sodium hydroxide was demonstrated to systemize hydrolysis process in polyester dyeing. We mainly focused on the application method of acid-alkali titration for the polyester hydrolysis machine of liquor-flow type. Industrial pH meter with electrode type was used for identifying equivalence point. Three units which were analogue-to-digital card, microprocessor and digital output card were used to control NaOH concentration in the control part of the system. The yielded data are translated to the microprocessor through analogue-digital interfacing card. After calculating, NaOH concentration in NaOH storage tank was controlled through the digital output card and solenoid valves.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.220-223
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• 2003

High-Tc superconducting(HT S) systems are commercialized by many study on high-Tc superconductor. For the successful commercialization of superconducting systems using Bi-2223 wires, the database on the degradation of critical current is essentially needed. In this paper, critical current variation of Bi-2223 wires according to the transport time was investigated. The degradation rate of critical current was also calculated. Solenoid type specimens have the length of 190cm Bi-2223 wire and double-pancake type specimens have the length of l0m wire were tested. Tested Bi-2223 wires are commercialized products of AMSC (American Superconductor) and Innost. When the transportation current was 95% of critical current, the degradation of critical current was appeared after 5 hours of transport time.

• 유공압시스템학회논문집
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• 제1권2호
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• pp.15-19
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• 2004

In this study, Design and simulation for low power consumption type pneumatic on-off micro valve was performed. And flow characteristics of the micro valve by stroke change was numerically investigated. As a result, it is shown that magnetic force(6.8N) is exerted enough to move poppet with 0.438mm stroke with 0.01 seconds of response time, and that there is no magnetic force emitted by yoke. Under the condition of poppet stroke smaller than about 0.4mm, dynamic pressure acts to poppet wall up to supply pressure level. But, that is decreasing to 40% when poppet stroke is 0.8mm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.760-762
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• 2000

Hybrid type LPM can be widely applied in the precise position controlled devic because precise linear motion can be directly obtained by the simple control circuit without backlash in the rotary-type stepping motor. Also, LPM can increase the Position resolution, which was limited by mechanical manufacturing limit and characteristic of magnetic material. using micro-step drive method to decrease the noise and vibration further. Especially, Double-side LPM may be replaced the solenoid as the valve driving device without difficulty and give full play to control the valve accurately. Hence, In this paper, magnetic circuit of double-side LPM was confirmed and static thrust force curve according to the relative displacement between stator and mover, was analyzed by the two dimensional finite element method. From this results, we can suppose the excitation current to be controlled optimally.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.10-13
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• 2003

6.6㎸rms/200Arms DC reactor type superconducting fault current limiter (SFCL) has been developed. This paper deals with the manufacture and short-circuit test of the SFCL. DC reactor was the HTS solenoid coil whose inductance was 84mH. AC/DC power converter was performed as the dual-mode operation. The short-term run(1 sec) and short-circuit test of this SFCL was performed successfully. The experimental results have a similar tendency to the simulation results. In short-circuit test, at 2 cycles after the fault, fault current limitation rate was about 30％.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.428-430
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• 2021

기상이변으로 인해 농업은 많은 피해를 입고 있다. 이에 대응하여 베란다형 스마트팜을 설계하고 직접 농작물을 재배함으로써 이 결과물이 현대사회에 가져올 수 있는 영향

• 전력전자학회논문지
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• 제15권5호
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• pp.381-386
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• 2010

본 논문에서는 자동차의 전장용 자기신호를 측정할 수 있는 비접촉식 측정장치를 개발하였다. 자동차에는 솔레노이드, 릴레이, 모터, 인젝터 등 많은 자기적 에너지로 동작하는 액츄에이터들이 장착되어있다. 그러나 이 장치들은 커넥터로 모두 연결되어 있으므로 전선의 피복을 벗기지 않고는 동작여부를 확인하기가 매우 어렵다. 따라서 본 논문에서는 홀효과를 이용한 센서를 사용하여 비접촉으로 액츄에이터의 작동 여부를 판단할 수 있는 장치를 개발하였다. 개발된 장치는 비접촉식이므로 액츄에이터들이 동작상태에 있을 때 전선의 피복을 벗기지 않고도 작동 여부 판단을 쉽게 할 수 있는 장점을 가진다. 시뮬레이션과 실험을 통하여 개발된 장치의 성능과 유용성을 보여주었다.