• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.964-965
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• 2008

본 논문은 고속 영구자석형 동기전동기의 센서리스 제어에 관한 것이다. 정지상태에서 초기 기동시 부터 고속영역까지 센서리스 알고리즘을 구현하기 위하여 슬라이딩 모드 관측기를 적용하여 회전자의 회전각을 실시간으로 관측하여 벡터제어 알고리즘을 구현하였다. 슬라이딩 모드 관측기의 채트링을 개선하고 넓은 속도 범위에서 안정된 응답을 얻기 위하여 속도에 따른 가변 이득 알고리즘과 관측기의 수렴을 여부를 판별하여 제한된 PWM 주기 내에서 관측기를 반복수행 관측기의 성능을 개선하는 알고리즘을 제안 하였다. 또한 제안된 알고리즘을 실험을 통하여 검증을 하였다. 초기 기동시 및 고속 영역에서 우수한 성능의 센서리스 알고리즘 구현되었을 확인하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.698-702
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• 2013

This paper considers the vertical pumps resonance and soundness. Normally large vertical pump's rotating speed is low, so the low natural mode can make a resonance on the motor and motor stand assembly. The pump resonance makes a very high vibration and trouble on the pump systems. Thus to avoid pump resonance when the pump is on the resonance region, we give the added mass method and evaluate the structure soundness by computer simulation and test on the site. Furthermore we evaluate the modal sensitivity and expect running conditions by the using ISO10814.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.77-82
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• 1999

대형 화물트럭의 차실 내에 높은 수준의 차바닥 진동을 수반한 높은 소음이 발생하였다. 측정 및 분석결과 문제의 진동 소음은 추진축의 회전 1차 및 2차 성분으로 나타났다. 진동 전달경로상의 구성계 및 구성요소들에 대해 모드해석과 실차 주행 모드 해석시험을 실시한 결과 드라이브라인 및 프레임의 공진주파수가 문제가 되는 소음진동 주파수와 거의 일치하였으며, 또한 캡의 실내음향 공진 모드가 문제되는 주파수에서 존재하였다. 실험결과에 따라 액슬과 액슬간의 축의 장착각도를 변경하여 가진력을 줄이고, 비틀림 동흡진기를 추진축에 장착하여 드라이브라인계 공진을 제어함으로써 문제의 시내진동소음을 현저히 개선하였다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.489-494
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• 2000

In the high speed driving conditions, the vibrational phenomena with relation to chassis system are becoming more important factors in chassis design and development. In this paper Commercial Dynamic program is used to model middle size bus for brake judder phenomenon. To verify the effects of a body structure in brake judder, body structure is modeled in flexible. Also mode shapes and frequencies are obtained from Commercial FEA program in the same condition of experimental test. The simulation results are compared to the experimental results and summarized

• Journal of the Korean Society for Precision Engineering
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• v.23 no.7 s.184
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• pp.168-176
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• 2006

Nowadays, Three dimensional printing (3DP) technique that is one of solid freeform fabrication (SFF) technology has been notable issue, and has been applied by various fields. The SFF system can fabricate three dimensional objects of solid freeform with high speed and low cost using ink jet printing technology. In this research, a SFF system to analyze 3DP process technology is developed. We applied sliding mode control with sliding perturbation observer (SMCSPO) algorithm and minimized position error to the developed SFF system. We analyzed and optimized process variables such as jetted volume, layer thickness, powder bed and so on experimentally. Also. the dimensional error of a developed SFF system is evaluated. Finally, the feasibility of application to bio manufacturing is presented through successful fabrication of teeth and cranium model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1281-1288
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• 2009

Variation of dynamic characteristics of a low pressure turbine blade with crack length is studied in this paper via both experiments and finite element model. Since most of the turbine blades used in domestic power plants are imported from abroad, it is necessary to understand their dynamic behavior in advance. When experimentally obtained natural frequencies and mode shapes are compared with those from FEM results, they are close to each other in their magnitude. Then, it is more feasible to use finite element model for analyzing the dynamic characteristics of a blade under various operation conditions (rotation speed, temperature, etc) as well as with a crack in the blade.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.303-306
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• 2002

본 논문에서는 ATM(Asynchronous Transfer Mode) 기반의 Ka 대역 초고속 위성 TDMA(Time Division Multiple Access) 지구국 시스템인 HiSTARS (High-Speed Satellite TDMA Ground System )시스템에서 망 전체의 형상 및 자원 정보를 관리하며, 장애상태 및 사용 채널에 대한 과금 정보를 관리하며, 장애와 망 전체에서의 망 운용성능과 관련된 통계 정보를 운용자에게 알려주는 망운용관리시스템(Network Management System)을 소개한다. NMS는 운용자의 요구사항을 HiSTARS 시스템의 기준지구국에 위치한 중앙처리시스템과의 빠르고, 정확한 메시지 통신을 통해 즉각적으로 처리하며, 모듈별로 독립적으로 기능들이 구현되어 있으며. 이들 모듈간의 원활한 통신 및 데이터베이스를 통한 데이터 관리를 통해 HiSTARS 시스템의 망 전체를 효과적으로 관리하고 운용할 수 있도록 한다. 본 논문에서는 이러한 NMS의 디자인 및 구현 방법을 구체적으로 보이겠다.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.271-274
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• 2003

This paper presents a Built-in Current Sensor that detect defects in CMOS integrated circuits using the current testing technique. This scheme employs a cross-coupled connected PMOS transistors, it is used as a current comparator. Our proposed scheme is a negligible impart on the performance of the circuit undo. test (CUT). In addition, in the normal mode of the CUT not dissipation extra power, high speed detection time and applicable deep submicron process. The validity and effectiveness are verified through the HSPICE simulation on circuits with defects. The entire area of the test chip is $116{\times}65{\mu}m^2$. The BICS occupies only $41{\times}17{\mu}m^2$ of area in the test chip. The area overhead of a BICS versus the entire chip is about 9.2%. The chip was fabricated with Hynix $0.35{\mu}m$ 2-poly 4-metal N-well CMOS technology.

• Wind and Structures
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• v.9 no.5
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• pp.397-412
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• 2006

This paper presents the wind excited acceleration responses of a 50 m guyed mast under the action of Typhoon Dujuan. The response of the structure is reconstructed from using a full finite element model and an equivalent beam-column model. The wind load is modelled based on the measured wind speed and recommendations for high-rise structures. The nonlinear time response analysis is conducted using the Newton Raphson iteration procedure. Comparative studies on the measured and computed frequencies and acceleration responses show that the torsional vibration of the structure is significant particularly in the higher vibration modes after the first few bending modes. The equivalent model, in general, gives less accurate amplitude predictions than the full model because of the omission of torsional stiffness of the mast in the vibration analysis, but the root-mean-square value is close to the measured value in general with an error of less than 10%.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2195-2199
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• 2008

The concern on sustainable development is increased to solve the global warming which is environmental issue over nations. Sustainable development is the concept of minimizing the consumption of resource and environment burden. In transportation, there are some trials of shifting to green transportation mode through low energy consumption and high efficiency. Korea Tilting Train eXpress (TTX) can run higher speed than existing train and save energy through light weight. In this study, Tilting bogie, the core equipment of tilting train, was compared with that of existing train.