• 수산해양기술연구
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• 제17권1호
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• pp.35-40
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• 1981

회전축계의 모델로서 구동원과 상호작용을 고려한 2개원판이 부착된 비대칭축계의 안정성을 연명하기 위해 안정오을 유도하고 수치계기을 행하여 제일, 이공진검성의 불안정구간을 구하였다. 비대칭축계의 위험속도 초과시의 불안정은 축의 비대칭도에 의한 불안정과 Torque 특성에 발생하는 불안정의 2종류로 분류된다. 편심의 위상용이 불안정에 미치는 영향은 매우크며, 이는 후자에 의한 불안정에 기인한다. 감양는 전자에 의해 생기는 불안정을 감소 시키나, 후자에 의한 불안정은 오히려 증가시켜서 자려진동을 유발하므로 주의를 요한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.396-397
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• 2015

With the increasing utilization of high-voltage, direct current (HVDC) transmissions in modern power systems, the DC grid is becoming a hot topic in academic and practical systems. In the DC grid, one of the urgent problems is the fast clearance of the DC fault in the DC network. One preferred method is to isolate the faulty point from the DC network in a short time. The DC circuit breaker is to interrupt the overcurrent after DC faults occur. In this paper, a self-excited resonant DC circuit breaker is an easy and cheap equipment to interrupt the DC fault current. The Mayr's arc model is utilized to simulate the self-excited DC circuit breaker in a DC test system in PSCAD/EMTDC.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.403-404
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• 2010

태양전지는 일사량 및 온도에 의해 출력 특성이 변화하여 최대전력을 얻을 수 있는 위치도 변화한다. 따라서 태양전지의 동작점을 최대 전력점에서 동작하게 하는 최대전력점 추적(MPPT, Maximum Power Point Tracking) 이 필요하다. 본 논문에서는 P&O 방식처럼 자려진동을 하지 않고 최대 동작점에서 머물면서 동작하는 NOC(Non-Oscillation Control) 방법을 제안한다. 이 방식은 빠르게 최대 동작점을 찾을 수 있고 특히 급격한 일사량 변동에 대해 유리한 장점을 갖는다. 최종적으로 제안된 제어기법의 타당성을 검증하기 위하여 3KW급으로 수행된 MPPT 모의 실험을 제시한다.

• 한국생산제조학회지
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• 제7권5호
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• pp.59-65
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• 1998

In order to utilize the information of well-know grinding database or grinding machine characteristics, a database needs to be designed by considering the delicate property of the machine tools for the high precision and quality of the demanding specification. Among the machine tools for the high precision and quality of the demanding specification. Among the machine tools, machining conditions of the grinding are various and knowledge repeatance obtained form the grinding process are less credable. therefore it is desirable for database, which is used to set the grinding conditions, to utilize the maximum machine tool capability. The present paper studied on the occurance limit of chatter vibration and burn considering the characteristics of machine tool. And also basic experiments were performed to establish the optimum grinding conditions which could maximize the grinding efficiency.

• 한국소음진동공학회논문집
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• 제14권8호
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• pp.702-708
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• 2004

This paper deals with friction-induced vibration of disc brake system under constant friction coefficient. A linear, lumped and distributed parameter model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the theoretical model, the experimental modal test and the dynamometer test are performed. The comparison of experimental and theoretical results shows a good agreement and the analysis indicates that mode coupling due to friction force is responsible for disc brake squeal. And squeal type Instability is Investigated by using the parametric analysis. This indicates parameters which have influence on the propensity of brake squeal. This helped to validate the analysis model and establish confidence in the analysis results. Also they may be useful during system development or diagnostic analysis.

• 한국자동차공학회논문집
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• 제2권5호
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• pp.93-100
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• 1994

Friction-induced vibration characteristics of automotive brake lining pad are investigated on the basis of experimental observations from a pin-on-disk type friction-induced vibration experimental apparatus. The measured responses of the experimental apparatus show limit cycles of quasi-harmonics type and beat phenomena due to the velocity dependence of friction force. To deduce the friction coefficient vs. relative velocity Lienard method is adopted with least square fit. It shows Scurve which characterizes a quasi-harmonic vibration. The calculation of amplitudes and friquencies of the limit cycles is done using slowly changing phase and amplitude method. The theoretical and numerical results show fairly good agreements with those of experiments.

• 대한조선학회논문집
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• 제50권5호
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• pp.343-348
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• 2013

When a natural frequency of the trailing edge of a wing is close to a vortex shedding frequency, an amplitude of the edge oscillation becomes maximal; it makes intensive noise called singing. Motion of the trailing edge may also feedback to the vortex shedding so that self-sustained oscillation appears, and a resonant frequency is locked in some interval of the speed of the incident flow. In this study, we first evaluate main features of oscillating characteristics of the wing. Second we simulate fluid-structure interaction of the wing with a flap using a commercial code, ANSYS-CFX, and investigate lift characteristics in a frequency domain.

• 대한전자공학회논문지
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• 제3권4호
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• pp.16-24
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• 1966

레이저 증폭기를 능동영역(Ruby Rod)에서의 Fabry-Perot 공진기의 방법으로 취급했고 5층, 즉 공기일반사판-Ruby-반사판-공기의 구조로 고찰했다. 일차원 스캘라파동방정식으로 Maxwell 전자방정식을 이용하여 입사계가 연속이라는 가정하에 경계치문제로 봤으며 모든 폭사계는 각경계면에 수직으로 입사한다고 생각했다. 모든 방정식은 Laplace 변환으로 과도현상론적으로 취급했으며 증폭기로서의 안정영역과 자려발진기로서의 불안정영역을 고찰했다. 또한 과도항과 관련된 레이저 증폭기 설계상의 문제도 생각했다.

• 대한기계학회논문집A
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• 제28권5호
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• pp.603-609
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• 2004

This paper deals with the issue of Neural Network-based control for a rodless pneumatic cylinder system which is utilized for a pneumatic XY-plotter. In order to identify the system design parameters, the open loop response of a pneumatic rodless cylinder controlled by a pneumatic servovalve is investigated by applying a self-excited oscillation method. Based on the system design parameters, the PD feedback compensator is designed and then Neural Network is incorporated with it. The experiment of a trajectory tracking control using a PD-NN has been performed and proved its excellent performance by comparing with that of a PD feedback compensator.

• 한국생산제조학회지
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• 제19권3호
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• pp.340-345
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• 2010

This paper presents the chatter stability lobes of high speed spindle of five-axis machine tools. Using a FEM, we obtained the frequency response function of a spindle and the stability lobes for evaluation of chatter. In addition, this paper suggest FRF using by FEM for the prediction of chatter stable region and critical cutting depth. Therefore, critical cutting depth of is 1.3586mm and X, Y direction's chatter frequency is 901Hz and 900Hz, respectively.