• 로봇학회논문지
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• 제5권3호
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• pp.231-239
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• 2010

For indoor mobile robots, the performance of autonomous navigation is affected by a variety of factors. In this paper, we focus on the characteristics of indoor absolute positioning systems. Two commercially available sensor systems are experimentally tested under various conditions. Mobile robot navigation experiments were carried out, and the results show that resultant performance of navigation is highly dependent upon the characteristics of positioning systems. The limitations and characteristics of positioning systems are analyzed from both quantitative and qualitative point of view. On the basis of the analysis, the relationship between the positioning system characteristics and the controller design are presented.

• 한국자동차공학회논문집
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• 제13권2호
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• pp.10-15
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• 2005

This study was initiated to evaluate the cooling performance of CAC (charged air cooler) and radiator in the engine room of a mini bus. So we had firstly to predict the mass flow rate coming from radiator grille and front bum per opening using computational fluid dynamics (CFD) simulation based on 3D configuration. And simulations were carried out for different cooling module layout and bum per opening hole size on sam e vehicle operating condition. Simulation results show that CAC cooling performance at reverse protecting plate-applying model was much efficient than that of the bum per opening hole size-increasing model in IMTD point of view. Part of the CFD simulation results was com pared to with experimental data. It was confirm ed that the CFD approach using STAR-CD based on pursuing no-com promise solution could provide design engineers with useful design information in the early design stage of vehicle development.

• 조명전기설비학회논문지
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• 제22권3호
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• pp.79-87
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• 2008

This paper presents a simple circuit topology of the auxiliary active quasi-resonant DC link snubber-assisted three phase voltage source soft-switching inverter for small scale PM motor drive applications. The pulse processing drive circuit interface and its soft-switching operation are discussed from an experimental point of view. Moreover, its conductive noise is measured and evaluated for electrical AC servo motor drive as compared with that of the conventional hard switching inverter.

• 한국소음진동공학회논문집
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• 제17권6호
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• pp.498-506
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• 2007

Using wind tunnel, experimental approaches were employed to investigate fluidelastic instability of tube bundles, subjected to uniform cross flow. There are several flow-induced vibration excitation mechanisms, such as fluidelastic instability, periodic wake shedding resonance, turbulence-induced excitation and acoustic resonance, which could cause excessive vibration in shell-and tube heat exchanges. Fluidelastic is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to cross flow. The system comprised of cantilevered flexible cylinder(s) and rigid cylinders of normal square array, In order to see the characteristics of flow in tube bundles, particle image velocimetry was used. From a practical design point of view, Fluidelastic instability may be expressed simply in terms of dimensionless flow velocity and dimensionless mass-damping. The threshold flow velocity for dynamic instability of cylinder rows is evaluated and the data for design guideline is proposed for the tube bundles of normal square array.

• 한국광학회지
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• 제15권5호
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• pp.423-428
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• 2004

320${\times}$240 배열의 중적외선 대역(3.7 $\mu\textrm{m}$∼4.8 $\mu\textrm{m}$) MCT(HgCdTe) 검출기를 이용하여 분해능과 신뢰도가 대폭 향상된 소형$.$고성능의 적외선 열상센서를 설계, 제작하였다. 개발된 열상센서는 1∼20배의 고배율 줌 광학계로 설계하고 미세주사 기법을 적용하여 640${\times}$480의 화소를 재현하여 항공기의 항법 보조로부터 표적획득에 이르기까지 다양한 활용이 가능하다. 적용된 적외선 줌 광학계는 릴레이 형태의 재결상계로 설계되었으며 미세주사 장치의 개발로 7.6 cycles/mrad 까지 분해가 가능하며 최저배율에서 40$^{\circ}$${\times}$30$^{\circ}$의 초광각(super wide field of view)의 시계를 갖는다. 또한 불균일 보정기법과 히스토그램 가변방식의 결합을 통한 첨단 열 영상처리 기법을 제안하여 열상센서에 적용함으로써 고성능의 실시간 디지털 영상처리를 가능케 하였다. 본 신호처리기의 개발을 통해 획득된 열영상의 최소분해가능 온도차는 고배율에서 0.05K(＠1cycles/mrad) 이하의 우수한 결과를 보였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.987-993
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• 2003

The module UPS can flexibly implement expansion of power system capacities. Furthermore, it can be used to build up the parallel redundant system to improve the reliability of power system operation. To realize the module UPS, load sharing without interconnection among parallel connecting modules as well as a small scale and lightweight topology is necessary. In this paper, the three-arm converter/inverter is compared with the general full-bridge and half-bridge topology from a practical point of view and chosen as the module UPS topology. The switching control approaches based on a pulse width modulation of the converter and inverter of the system are presented independently The frequency and voltage droop method is applied to parallel operation control to achieve load sharing. Two prototype 3kVA modules are designed and implemented to confirm the effectiveness of the proposed approaches. Experimental results show that the three-arm UPS system has a high power factor, a low distortion of output voltage and input current, and good load sharing characteristic.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2242-2244
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• 1999

Recently, An important research field of pulsed power is high voltage, high power generation with exploding wire opening switch. Another point of view exploding wire effects have been researched for generation of the pulsed high pressure shock wave. Theoretical considerations of the shock pressure generation along with experiment results are presented in this paper and. Some experimental results of hard rock fracturing show the possibilities of commercial using.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.964-969
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• 2008

The recently those of various gatherings or events are gradually increasing not only at the general public performance hall but also at the outdoor performance hall. However, since the most of the domestic outdoor performance halls are being designed and executed without the proper consideration and care for Acoustic Characteristic thereat, a satisfying acoustic management are not established due to above reason. From this point of view, this study presents the basic data that will increase the sound performance in designing of the outdoor performance hall, by conducting the comparative analysis on the architectural sound characteristics through the field survey on to the 3 outdoor performance halls that have different characteristics, in order to present the appropriate standards.

• 전기화학회지
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• 제6권3호
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• pp.187-195
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• 2003

The present article is concerned with the overview of carbonaceous materials used as anode materials for lithium ion secondary batteries. This article first classified carbonaceous materials into graphite, soft carbon and hard carbon according to their crystal structures, and then summarised the previous works on the characteristics of lithium intercalation/deintercalation into/from the carbonaceous materials. Finally this article reviewed our recent research works on the mechanism of lithium transport through graphite, soft carbon and hard carbon electrodes from the kinetic view point by the analysis of the theoretical and experimental potentiostatic current transients.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.250-253
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• 2003

In general, AC transport current loss of vertically stacked HTS tapes is larger than simple multiplication of single tape by stacked number. In this study we investigated the transport current and current distribution in face-to-face stacked conductor Numerical method has been developed for loss estimation and compared to the experimental works. Two results showed goof agreement each other The stacked conductor behaved like a single watching current distribution, From this point of view it is possible to suggest the other analogy to predict the transport current loss. All results were presented and checked the validities of the loss estimation.