http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
김낙근 ( Nak Geun Kim ),이계복 ( Kye Bock Lee ) 충북대학교 건설기술연구소 2012 建設技術論文集 Vol.31 No.1
항구로 바닷물이 들어올 때 수문의 자려 진동은 수문 아래의 와류에 수문의 자려진동을 예측하기 위해 2차원 비정상 유동 특성을 수치적으로 해석하였다. 의해 발생하는 것을 확인하였다. 진동수와 평균속도에 대한 수문개도의 영향과 수문 아래에 발생하는 와류에 대해 연구하였다. 수문 개도가 증가할수록, 진동수는 감소하였다. Numerical analysis on the flow induced vibration in the water gate has been carried out by 2-dimensional unsteady CFD simulation when sea water flows into the port in the river. The results show that the sources of disturbed frequency are the vortex shed from the bottom of the water gate. Effect of gate opening on the frequency and the mean velocity and the vortex shed from under the water gate were studied. As the gate opening ratio increases, the predicted vibration frequency decreases.
두 액체로 충전된 회전체의 자려진동에 관한 실험적 연구
양보석,유영훈 대한기계학회 1989 대한기계학회논문집 Vol.13 No.3
본 논문에서는 상기와 같은 문제들을 규명하기 위하여 비교적 긴 원통에 액체를 내장할 수 있도록 회전체를 제작하여 액체의 종류, 점도, 액체의 양 등을 파라미터로 하여 불안정영역의 범위와 진동진폭에 관해서 실험적으로 조사하였고, 비중이 다른 2액체를 동시에 내장한 경우 액체의 자유표면과 경계면에 의한 진동특성을 을 검토하였다. The motions of a spinning rotor and a fluid enclosed in its cavity are known to have mutual interactions, which change the frequencies of forced vibrations and cause instabilities. These phenomena are of technical importance for fluid-cooled turbines as well as spin-stabilized satellites or rockets containing liquid fuels. In this paper the characteristics of unstable whirling of a rotor containing a partitioned cavity filled with two kinds of liquids are investigated experimentally. It studies the influence of rotational speed and filling ratio of two kinds of liquids on unstable whiring. As a result, it is found that the whirl velocity is approximately equal to, or slightly lower for large masses of trapped fluid than rotor critical speed. In case of a spinning rotor partially filled with two kinds of liquids the boundary surface plays a similar role to the free surface, and cases unstable forward whirl.
이계복 ( Kye Bock Lee ),조용 ( Yong Cho ) 충북대학교 건설기술연구소 2014 建設技術論文集 Vol.33 No.1
항구로 바닷물이 들어올 때 수문개도와 수위차에 따른 수문하부의 유동특성과 자려진동을 2차원 비정상 상태로 수치적으로 해석하였다. 진동수에 대한 결과는 수문아래의 외류에 의해 발생하였다. 수문 하부에서 발생하는 역류와 전단력, 와유출 등의 유동특성을 분석하였고 수문 개도가 증가할수록, 진동수는 감소하였다. 수문의 고유진동수에 근접하는 수위차와 수문개도의 유동조건을 예측하였다. The goal of the present work is to investigate the flow characteristics under the water gate and the flow induced vibration by 2-dimensional unsteady CFD simulation for different opening gaps of the water gate and the wawter level differences. The flow characteristics such as velocity profile. shear stress and vortex shedding under the water gate are analyzed. As the gate opening gap increases, the oscillated frequency decreases. The prediction results show the dangerous operating conditions on the gate opening gap and the water level difference which could be resonant.
자려 진동형 히트 파이프를 이용한 저온 폐열 회수 열교환기의 성능 실험
이욱현,이종현,김종수 대한설비공학회 2000 설비공학 논문집 Vol.12 No.9
In this study, low temperature waste heat recovery heat exchanger was developed using a principle of self-excited oscillating heat pipe. The heat exchanger of serpentine type was composed of extruded flat aluminum tube with 6 channels (3 nm$\times$ 2.75nm) and louvered fin. The heat transfer area density of heat exchanger was $331.9 m^2/m^3$. Working fluid is R141b and charge ratio was 40% by volume. Heat transfer rate and the effectiveness of heat exchanger was primary concern of this study. As a result, the effectiveness of heat exchanger was about 0.4-0.67, and recovered waste heat rate was about 4.5 kW per one unit of heat exchanger.
마찰 기인 2자유도계 시스템의 자려진동에 대한 댐핑의 영향
조용구,신기홍,이유엽,오재응 한국소음진동공학회 2002 한국소음진동공학회 논문집 Vol.12 No.7
A two-degree of freedom model Is suggested to understand the basic dynamical behaviors of the interaction between two masses of the friction induced vibration system. The two masses may be considered as the pad and the dusk of the brake. The phase space analysis is performed to understand complicated dynamics of the non-linear model. Attractors in the phase space are examined for various conditions of the parameters of the model especially by emphasizing on the damping parameters. In certain conditions, the attractor becomes a limit cycle showing the stick-slip phenomena. In this Paper, not only titre existence of the limit cycle but also the sloe of the limit cycle is examined to demonstrate the non-linear dynamics that leads the unstable state. For the two different cases of the system frequency[(1) Two masses with same natural frequencies, (2) with different natural frequencies] . the propensity of limit cycle Is discussed In detail. The results show an important fact that it may make the system worse when too much damping Is present in the only one part of the masses.
분포매개변수를 이용한 디스크 브레이크의 마찰기인 불안정성 해석
차병규,조용구,홍정혁,이유엽,이정윤,오재응 한국소음진동공학회 2004 한국소음진동공학회 논문집 Vol.14 No.8
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.