• 대한전자공학회논문지SP
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• 제44권1호
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• pp.64-69
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• 2007

본 논문은 고속 UWB(Ultra Wide Band) 시스템을 위한 인터폴레이터를 구현한다. 구현된 고속 UWB 시스템용 인터폴레이터는 기존 가변 파라미터를 이용한 큐빅 인터폴레이터에 병렬 처리 기술과 파이프라인 기법을 동시에 적용한다. Stratix II EP2S60F1020C3를 타겟 디바이스로 실험한 결과, 최대지연경로 속도와 최대지연경로 주기가 각각 최대 102.42MHz와 9.764ns가 되었고, 동작속도는 최대 대략 190%이상 향상되었음을 알 수 있다.

• 한국철도학회지
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• 제10권2호
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• pp.9-15
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• 2007

• 월간포장계
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• 통권375호
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• pp.54-58
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• 2024

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.243-249
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• 2001

This paper has been presented the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existed investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. In this paper, the pressure behavior in theory of air film according to the eccentricity of journal and the source positions analyzed. The theoretical analysis have been identified by experiments. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• 한국정밀공학회지
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• 제20권9호
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• pp.40-46
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• 2003

Synchronizing errors between the spindle motor and the z-axis motor directly influences the cutting characteristics and the thread quality in tapping, because the tapping process is accomplished by synchronizing the movement of the z-axis with the revolutionary spindle motion. Generally synchronizing errors are decided by tile parameters of the servo system and commanded velocity. The excessive synchronizing errors which are induced by the parameter mismatch and high cutting velocity can cause tap breakage due to the abrupt increase of cutting torque or damage the thread accuracy by overcutting the already cut threads. In this paper, the influences of the synchronizing errors on the tapping characteristics in the ultra high-speed tapping will be described and a minimum level of synchronizing errors necessary to maintain the quality of the cut thread will be presented.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.24-25
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• 2006

High-Speed Centrifugal Compaction Process is one of slip-using compacting method originally developed for processing of oxide ceramics. In this study, we apply the HCP to ultra-fine (0.1 micron) WC powder. Organic liquid of heptane was chosen as dispersing media to avoid possible oxidation of WC. The mixing apparatus was a key to obtain dense compacts. Only the slips mixed by high energy planetary ball mill were packed up to 55% by the HCP, and sintered to almost full density at 1673 K without any sintering aids. This sintered compact marked Vickers hardness of Hv 2750 at maximum.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.442-447
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• 2007

A very abnormal vibration was occurred at the LP(low pressure) turbine continuously during the pre-operation for a 550MW class USC(ultra super critical) steam turbine. This vibration was initiated at the rotating speed of about 3,450rpm and then the vibration amplitude was highly increased the number by $2{\sim}3$ times with the increase of the rotating speed to the rated speed(3,600rpm). In this paper, this abnormal vibration named spike vibration. This spike vibration was caused by the rubbing between the rotating bucket tip seal and the Lower Half of spill strip. Also, this paper presents the mechanism of the spike vibration and the proper method to eliminate this abnormal vibration problem. This result would be good practice to find the solution of similar high vibration in the USC steam turbines for power plant as well as industrial rotating machineries.

• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1238-1245
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• 2007

A very abnormal vibration was occurred at the LP(low pressure) turbine continuously during the pre-operation for a 550MW class USC(ultra super critical) steam turbine. This vibration was initiated at the rotating speed of about 3,450 rpm and then the vibration amplitude was highly increased the number by $2{\sim}3$ times with the increase of the rotating speed to the rated speed (3,600 rpm). In this paper, this abnormal vibration named spike vibration. This spike vibration was caused by the rubbing between the rotating bucket tip seal and the lower half of spill strip. Also, this paper presents the mechanism of the spike vibration and the proper method to eliminate this abnormal vibration problem. This result would be good practice to find the solution of similar high vibration in the USC steam turbines for power plant as well as industrial rotating machineries.

• 한국통신학회논문지
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• 제11권3호
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• pp.153-163
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• 1986

III-V족 복합물 반도체인 GaAs를 이용한 초고속소자는 DBS(Direct Broadcast Satellite), 광통신, microwave 및 digital 집적회로에 널리 사용되낟. 이와 같은 GaAS를 substrate재료로 D/E MESFET'S을 이용한 4Kx4bit SRAM, HEMT'S에 의한 4K bit SRAM과 X-band용 수신기전단부의 MMIC화가 보고되였고, 3차원적인 광집적회로의 연구도 가까운 장래에 완성될 것이다. 본 논문에서는 현재까지 널리 사용되어온 GaAs반도체 재료, 제조공정기술, 소자응용과 집적회로 설계면을 고찰 검토한다. 마지막으로 초고속소자의 전망을 논의한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1649-1651
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• 2002

Ultra-wide bandwidth (UWB) detection method has been widely used as a front end detection scheme for the ultra-high frequency (UHF) partial discharge (PD) monitoring systems. A broad-band video detector module was developed and characterized for the UHF UWB PD detection systems. The useable bandwidth of the module is more than 2 GHz and it is optimized for 50-ohm systems. The detection sensitivity and dynamic range of the module were characterized by using a known ns-width RF pulses of GHz range. The dynamic range is more than 6-decades and the module can detect pulsed RF signals down to 1 nW. The detector module can eliminate expensive equipment such as high speed oscilloscopes and radio frequency (RF) spectrum analyzers. Therefore, it enables one to use slow speed data acquisition systems for the PD monitoring at the UHF range. The detector module was used to detect real PDs of about <3 pC. The module converts the UWB PD signals into a low-bandwidth video signal with a high signal-to-noise ratio.