• Journal of Advanced Marine Engineering and Technology
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• 제22권3호
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• pp.328-336
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• 1998

Marine reduction gears are usually used to increase the propulsion efficiency of propellers for ships powered by medium and small sized high speed diesel engines. Most of shaft systems adopt flexible couplings to absorb the transmitted vibratory torque from the engines to the reduction gears and to prevent the chattering phenomenon of reduction gears. However some elastic couplings show non-linear characteristics due to the variable torque transmitted from the main engines and the change of ambient temperature. In this study dynamic characteristics of flexible couplings sare investigated and their effects upon various vibratory conditions of propulsion systems are clarified. A calculation program of torsional vibration for the propulsion systems are clarified. A calculation program of Results of the program developed are compared with ones of the existing linear method and propulsion systems with the elastic couplings the transfer matrix method is adopted which is found to give satisfied results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.269-274
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• 2007

With the importance of comfortable environment, research about noise reduction of construction is consisting much. If construction receives the input force, noise will be generated thereby. We must predict vibration and noise characteristic to reduce structured borne noise, and construction which become a basis of such research is plate. In order to predict the radiating noise from the vibrating surface. It is required to know the velocity distribution of vibration surface exactly. It is good to use bead for reducing vibration and noise of plate. In this study, we have analyzed structure-borne noise of plate with bead and compare with plate that there is no bead about equal exciting force.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.742-744
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• 2001

Moving flat core LOA consists of iron flat core as a mover and electric magnet as a stator and operated by electromagnetic force between mover and stator. In a moving flat core type, it takes advantage of doing not have to be equipped with power supply device, having a lower manufacturing cost. But it has a lower linearity and precision. In this paper, a static characteristics of LOA were studied and analyzed using FEA. Experiments, electromagnetic force and inductance according to air gap and input currents, were carried by exciting coil. And we compared these results one another.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.147-150
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• 1999

SRM drives generate large vibration and acoustic noise because it is commutated individually by step pulse m.m.f on each phase pole. The frequency or motor speed of peak vibrations and acoustic noises is coincided with the natural resonant frequency of the magnetic structure and frame material. And this radial vibration force is induced on the phase commutation region. This paper suggest the new electromagnetic structure of SRM with auxiliary commutation winding excited d.c e.m.f.. This phase- commutating winding is coupled magnetically between one phase winding and the vibrating force is falled down. As a result, SRM with d.c exciting commutation winding is very useful to reduce vibration and acoustic noise of SRM drive.

• 한국음향학회지
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• 제15권2호
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• pp.33-39
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• 1996

비선형 건마찰 감쇠를 가진 외팔보의 강제진동 응답을 건마찰 감쇠기와 가진력의 위치변화에 대하여 미끄러진 변위와 힘레벨을 수치해석하였다. 구성모드의 분석은 비선형 감쇠를 가진 계를 해석하기 위해 구속조건과 Lagrange 승수에 기초를 두고 분석하였다. 외팔보의 진동분석 결과 건마찰 감쇠기가 부착된 단순 지지된 보(beam)에서 보여진 응답특성과 유사한 특성이 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.211-214
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• 1997

This paper describes the position accuracy performance improvement of hybrid type LPM. The harmonics are included in the thrust force component of LPM, those are generated from the the nonlinearity of intrinsic magnetic saturation characteristic and mechanical construction, and so on. In this paper, the performance improvable methode is proposed for the better thrust force by the corrected exciting current injection, and precise position control is achieved.

• 한국해양공학회지
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• 제2권2호
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• pp.27-36
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• 1988

For the purposes of drilling oil field and extracting oil deep water in more rough weather, the size of drilling rigs must be estimated. In this paper, the three dimensional source distribution method is used and we assume 10 deg. heeling and trimming condition of the drilling rig(SR-192). Also, the effects of the hydrodynamic forces which include the drift forces for field method, and the motion responses are studied with changing the incident wave direction in the assumed inclining condition. The theory and numerical codes used in this thesis appeared to be very useful for the preliminary design of drilling rigs.

• 대한조선학회지
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• 제21권3호
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• pp.35-42
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• 1984

In this paper, the lateral motions of a ship in the time domain are treated by applying the Impulse Response Function Technique. The acceleration, and displacement of a ship in the time domain are needed for the purpose of such automatic controls as the fire control system and the auto-pilot of ocean-going vessels, etc. The response Amplitude Operators of a ship are calculated by the Strip Method of Salvesen-Tuck-Faltinsen, and the Pierson-Moskowitz Spectrum multiplied by spreading function is used to represent the short crested ocean waves. The ocean wave elevations in the time domain are simulated according to the Method of Borgman. Finally the rudder effect is considered by simply adding the force and moment due to the rudder to the wave exciting force. And the results of lateral motions with and without rudder are shown.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 추계학술대회 논문집
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• pp.85-87
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• 2008

This paper presents dynamic characteristics in Switched Reluctance Motor (SRM) with rotor eccentricity and proposes the reduction method of rotor eccentricity effects by the different winding connections. These characteristics investigations are computed by 2D transient magnetic FEM analysis coupled with external circuits. The radial and unbalance magnetic force in the stator, which is the main exciting force of the vibration, is calculated using Maxwell stress method and compared with the performance characteristics according to the serial and parallel connections of windings. The influence of winding method counteracting unbalance forces on the rotor vibration behavior is estimated by the current waveforms of the paralleled paths under rotor eccentricity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.815-824
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• 2013

Pneumatic exciters can be good replacements of electrodynamic, piezoelectric and hydraulic exciters owing to simple structure and large exciting force. One problem to be solved is a slow response caused by compressibility of air. Desirable frequency response characteristics of exciter are constant magnitude and zero degree phase, because users want no time delay between input signal and output force. For this reason, frequency range of pneumatic exciters is limited about 0~1 Hz. Therefore, expansion of frequency range is an important issue when designing the pneumatic exciter. In this paper, the pneumatic exciter which has same structure with active pneumatic isolator is dealt with. The dynamic characteristics are presented, and its limitation of expanding frequency range is shown based on analytical studies. Then the pneumatic exciter with dual-chamber is suggested to overcome this problem. Based on simulation study, a design method is presented.