• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.99-106
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• 2002

For the development of a ultra-precision CNC polishing system including on-machine measurement system, we study a corrective polishing algorithm. We calculated unit removal profiles for various flat type polishing tools and polishing tool positions. Using these results we simulate the corrective polishing process based on dwell time control. We calculate dwell time distributions and residual error of the polishing simulation method and the FFT calculation method. We test corrective polishing algorithm with an optical glass. The target removal shape is a sine wave that has amplitude 0.3 micro meters. We find this polishing process has a machining resolution of nanometer order and is effective for sub-micrometer order machining. This result will be used for the software development of the CNC polishing system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.95-99
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• 1996

The form accuracy of parts has become an important parameter. Therefore dimensional tolerance and geometric tolerance are used in design to satisfy required quility and functions of parts. But the informations for machining conditions, which can satisfy the assigned geometric tolerance in design, are insufficient. The objectives of this research are to study the effects of the grinding parameters such as traverse speed, work speed, depth of cut, and dwell time on the after-ground workpiece shape, and to find out the major parameters among these parameters. Finally, a methodology is proposed for getting the optimal grinding condition for precision workpiece The results are as follows; The effects of work speed and depth of cut on workpiece shape are ignorable compared to the effect of traverse speed. These is the optimal dwell time depending on the traverse speed. The optimal dwell time is decreasing when the traverse speed is increased.

• Journal of architectural history
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• v.6 no.2 s.12
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• pp.53-64
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• 1997

The language of architecture is a kind of tool which helps people to experience the environment not as the thing itself but as a meaningful one. It, gathered by place, constitutes 'genius loci', as the existential structures. It, in other words, gives a thing 'cognitive quality', and serve people to 'dwell' because 'a place is a gathering thing with concrete presence.' Our environment, only when it possesses the language, presents itself as a namable thing or an understood world. Such a meaningful identification is dwelling. The modern world is a complex melting-pot. It is 'complexities' and 'contradiction'. The language of architecture is never created, rather it is selected by needs of the time and the place. In this sense, architectural design means discovery and interpretation of the poetic order of architypal form and style, and the poetic order is a way for people to dwell in the humanistic sense. These reminds me of Martin Heidegger's statement : "Architecture belongs to poetry, and its purpose is to help man to dwell."

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.696-701
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• 2006

In this paper, we analyze the performance of double-dwell hybrid initial acquisition in DS-UWB system via detection, miss, false alarm probabilities and mean acquisition time. In the analysis, we consider the effect of the acquisition sequence, and deployment scenario of the abundant multipath components over the small coverage of the piconet in DS-UWB system. Based on the simulation, we obtain various performance on the mean acquisition time by varying the parameters, such as the total number of hypotheses to be searched, subgroup size, and dwell time. Then, we suggest the optimum parameter set for the initial acquisition in DS-UWB system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.5
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• pp.27-37
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• 2012

Even thought the firefighters have to hurry to the scene to extinguish the blaze, the fire engines could not rushed out due to the worst of traffic condition. Traffic signal control is one of the most important methods to minimize the fire engines's travel time. The focus of this paper is to develop a traffic control strategy, which is emergency vehicle preemption algorithm considering pedestrian in order to reduce travel time of emergency vehicle. This algorithm also includes recovering strategy after preemption signal to minimize the other vehicle's delay. In order to estimate the effectiveness of traffic control, traffic simulation was performed using VISSIM micro simulation tool for two different kinds of networks, which were non-coordinated corridor and coordinated corridor. The differences of travel time and average delay between emergency vehicle and ordinary vehicle were respectively estimated under pre-existed pretimed signal and preemption traffic control at two respective networks. The results of the simulation for the emergency vehicle, travel time was reduced to 36.8~43.3% under "Add or Subtract" method whereas it was reduced to 30.7~46.0% under "Dwell" method. In addition, in non-coordinated corridor case of ordinary vehicle, average control delay of "Dwell" method was increased 33.5% whereas it grew 0.5% under coordinated corridor. And "Add or Subtract" method was confirmed that average control delay of ordinary vehicle was increased 0.7% under non-coordinated corridor whereas it swelled 4.5% under coordinated corridor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.35-35
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• 2000

터빈의 핵심구동부품은 손상이 누적되어 파괴에 이를 경우 치명적인 결과를 야기할 수 있기 때문에, 부품사용조건에서의 소성변형과 이에 따른 손상 누적을 정확히 예측하고 평가함으로써 균열생성 시점을 정확히 파악하여야 할 필요가 있다. 현재 터빈디스크와 같이 고온 고응력에서 사용되고 있는 소재부품의 수명은 궁극적으로 크리프변형과 피로시험의 공동작용으로 결정되며, 재료특성모델링 시험에 있어서도 dwell time 피로시험을 통해 dwell time 효과를 점검하고 점소성 재료변형에 근거하여 피로에 의한 변형 현상을 설명할 수 있다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.233-236
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• 2000

In this paper, we consider a code acquisition of W-CDMA signals over multipath Rayleigh fading channel when double-dwell serial search code acquisition is used for initial synchronization. We derive the detection and false alarm probability, and mean acquisition time mathematically by taking into account of multiple H$_1$ cells and double-dwell serial search. It is noteworthy that the more the number of the post-detection integration, the shorter the mean acquisition time in low SNR.

• Journal of applied mathematics & informatics
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• v.31 no.5_6
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• pp.895-906
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• 2013

In this paper, we study the stabilization problem of switched systems with both controllable and uncontrollable subsystems. By using an average dwell time approach, we first establish a sufficient condition such that the switched system is exponentially stabilizable under appropriate switching signals. We also extend this result to the switched system with nonlinear impulse effects and disturbances. Numerical examples are given to illustrate the theoretical results.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.161-161
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• 2009

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.955-957
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• 1998

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia, and high poer rate per unit volume. However, position sensor isessential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system, and tend to reduce system reliability. This paper investigtes the speed control of sensorless SRM. The proposed system consists of position detection circuit, dwell angle controller, digital logic commutator, PI speed controller and 4-phase inverter. The performances in the proposed system are verified through the experiment.