• 대한전기학회논문지
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• 제35권12호
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• pp.541-554
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• 1986

This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

• 한국유체기계학회 논문집
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• 제9권3호
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• pp.29-35
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• 2006

There are high expectations of improving the performance of a centrifugal pump in the range of very low specific speed which has been developed recently for the use instead of a conventional positive displacement pump. However, even though elaborated studies has been done for the pump intensively, the pump performance has not increased so much. Also, it is difficult to find detailed information from published literatures for suction performance of the very low specific speed centrifugal pump. Therefore, this study is aimed to improve the pump performance more and to make clear suction performance of the very low specific speed centrifugal pump. Recircular flow stopper is installed on the pump casing wall at the region of impeller outlet to improve the pump performance and J-Groove is also installed at the inlet of the pump casing for the purpose of suppressing occurrence of cavitation as well as improving pump performance. The result suggests that the simultaneous improvement of pump performance and suction performance of the very low specific speed centrifugal pump is possible by adopting optimum configuration of the recirculation flow stopper and J-Groove.

• 대한전자공학회논문지SP
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• 제43권1호
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• pp.85-90
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• 2006

본 논문에서는 빠르고 안정적이면서도 높은 검색 성공률을 보장하는 내용기반 음악 정보 검색 시스템을 구축하였다. 시스템 질의 구간이나 질의 길이에 따른 시스템 불안정성 문제를 해결할 수 있는 DB 구축 방법인 MFC기법과 각 Superclass별로 특징 벡터의 차수를 차등 적용하여 시스템의 검색 속도를 향상시킬 수 있는 기법을 적용하였다. Superclass를 적용한 시스템은 SuperClass를 적용하지 않은 시스템과의 검색 성공률, 검색 속도 그리고 검색 Precision 비교 실험에서 대등한 성능을 유지하면서 검색 속도를 $20\%\~40\%$ 향상시켰다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.207-210
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• 1995

In this paper, two representative schemes for vector control of induction motor without speed sensor are studied. First, the two sensorless systems which are implemented by voltage and current source are presented with new ideas and interpretations. Then a linear model around an operating point is proposed. Finally, the stability improvement of these systems are studied and evaluated by computing the trajectories of poles and zeros.

• 제어로봇시스템학회논문지
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• 제9권1호
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• pp.37-43
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• 2003

A faster autofocusing method is proposed. The searching speed of microscope camera is limited by the long focusing time due to too much sampled digital image data. The improvement of autofocusing speed based on the down sampling is discussed analytically and is proved by experiments. The anticipated aliasing is found negligible in shilling rate of focus measure.

• 대한전기학회논문지
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• 제43권7호
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• pp.1075-1083
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• 1994

In this paper, a study on the improvement of the IM speed response against load torque variation is presented. A VSCS(Variable Structure Control System) is proposed which gives the desired robustness against load torque variation using a new kind of time-varing switching plane. In order to eliminate the reaching phase of the states from one switching plane to another during variation, the switching plane is varied continuously. To verify the high dynamic performance of the proposed VSCS, simulation and experimental results are presented.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.958-963
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• 2005

Much research for speed elevation of old first move of internal railroad is achieved. Also, several fees of foreign flag age of forty years improvement of a signal system and development accomplish. This treatise examines about. improvement and development. of consisting signal system in internal. Also, examine about development for technological reduced scale of internal relationship and research propulsion system. Wish to present direction accordingly.

• 한국ITS학회 논문지
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• 제5권1호
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• pp.55-63
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• 2006

차량의 과속은 도시부 도로에서 번번하게 일어나는 교통사고의 중요한 원인 중 하나이다. 교통사고의 감소를 위하여 설치하는 교통통제창치의 일종인 과속경보장치(DFS)는 국내에서는 차대사람 교통사고를 예방하기 위하여 점차 다양한 곳에 적용을 확산해나가고 있다. 본 연구에서는 이 교통통제장치의 효과가 어느정도인지를 파악하기 위하여 설치전후로 첨두시간과 비첨두시간대로 나누어 필드 조사를 수행하였고, 수집자료의 분석에는 차량평균속도 및 속도분산을 포함한 여러 가지 종속변수에 대하여 실험결과에 대한 통계적 검증과 함께 논의 되어졌다. 따라서 본 연구에서는 사고감소 및 교통안전도 향상을 위한 교통통제장치로써 과속경보장치(DFS)가 단속에 의한 강제적 방법을 사용하지 않고도 교통류의 속도를 효과적으로 통제하여 보다 안전한 보행환경을 제공하고, 사고율을 낮춤으로써 교통안전도를 향상시키는 것으로 파악되었다.

• Tribology and Lubricants
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• 제28권6호
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• pp.265-271
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• 2012

In the preceding Part I study, for improving the unbalance response vibration of a large PRT motor-generator rotor fundamentally by design, a series of design analyses were carried out for bearing improvement by retrofitting from original plain partial journal bearings, applied for operation at a rated speed of 1,800 rpm, to final tilting pad journal bearings. To satisfy evenly key basic lubrication performances such as the minimum lift-off speed and maximum oil-film temperature, a design solution of 5-pad tilting pad journal bearings and maximizing the direct stiffness by about two times has been achieved. In this Part II study, a detailed rotordynamic analysis of the large PRT motor-generator rotor-bearing system will be performed, applying both the original plain partial journal bearings and the retrofitted tilting pad journal bearings, to confirm the effect of rotordynamic vibration improvement after retrofitting. The results show that the rotor unbalance response vibrations with the tilting pad journal bearings are greatly reduced by as much as about one ninth of those with the plain partial journal bearings. In addition, for the tilting pad journal bearings there exist no critical speed up to the rated speed and just one instance of a concerned critical speed around the rated speed, whereas for the plain partial journal bearings there exist one instance of a critical speed up to the rated speed and two instances of concerned critical speeds around the rated speed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.964-968
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• 2005

The standardization of information communication is doing a Internal each other connection and each other characteristic stability operation security in objective. From the low-speed network of the subway operation beginning currently it changes with the superhigh speed digital information transmission communication service environment which is a quality service, the hazard which plans the quality improvement of the efficient communication service use which hits to here and passenger service the standardization of the technical standard which stands and the improvement which hits to an engineering standard and facility must come to accomplish. The facility which existing is been old or the enclosure communication equipments which are insufficient. it improves, establishment itexpands efficiently, like this facilities it is stabilized and it is economic and rationally use maintenance it manages with the plan for the inside and outside of the country information communication relation technical standard and engineering standard service feature improvement and future expandability and economical efficiency, the possibility of having a pliability in order to be, rational technical standard and standard it takes a triangular position, efficient characteristic security of information communication service there is a place objective which promises the rational development of course city railroad communication system with character. Function improvement of enclosure communication base equipment, against an improvement and standardization plan it described trom the prosecution which it sees.