부분 탄성기초를 갖고 종동력을 받는 보의 플러터 불안정

류봉조,류시웅,조창기,이종원 한밭대학교 생산융합기술연구소 2004 생산기반기술연구소 논문집 Vol.4 No.1

In this paper, the dynamic stability of a cantilevered beam partially attached to elastic foundations and subjected to a follower force is studied. The beam has a concentrated mass at an arbitrary position on it. Governing equations are derived by extended Hamilton's principle and the finite element formulations are applied to obtain discretized equations. The influence of some parameters, such as the elastic foundation parameter, the position of partial elastic foundations, mass ratios and rotary inertia of the concentrated mass on the critical flutter load is investigated. Finally, the optimal attachment ratio of partial elastic foundation which maximizes the critical flutter load is found.

공기재생용 고온건식탈황제의 가압유동층 반응기에서의 사이클 성능실험

조성호,이봉희,이중범,류청걸,진경태,이창근 한국화학공학회 2002 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.40 No.2

고온고압 기포유동층 반응기에서 분무건조기로 성형제조한 아연계 탈황제(ZAC C)에 대하여 총 6회 황화-재생 반복실험을 500℃, 5atm 조건에서 수행하였다. 1% H_2S를 포함한 석탄모사가스를 반응기에 주입하여 황화반응을 시킨 결과 배출가스 중 H_2S 농도는 10ppmv 이하로 유지되었다. ZAC C의 황흡수력은 6회 황화반응 동안 각각 11.1, 10.9, 11.1, 11.1, 10.9, 10.5g S/100g sorbent으로 유지되어 초기 황흡수력을 유지하였다. 공기를 이용한 500℃ 재생반응에서 배출되는 SO_2의 최대농도는 양론적으로 이론값과 일치하였다. 재생반응에서 탈황제 층의 온도는 발열반응에 의해 500℃에서 최대 750℃까지 상승하였다. 연속 70시간 동안 유동층 반응기내에서 실시된 ZAC C 탈황제의 비산되어 유출된 양은 1.07%이고, 실험 후 탈황제의 크기와 조직특성의 변화도 적었다. 고온고압반응기 multi-cyclone 실험결과 ZAC C 탈황제는 이론 황흡수력의 50% 이상을 유지하였고, 공기를 사용한 500℃의 재생반응이 원활하고 완전히 이루어졌고, 황산염생성과 같은 부반응이 없었다. Two desulfurization-regeneration experiments for a spray-dried zinc-based sorbent(ZAC C) were performed at 500℃ and 5 atm in a fluidized-bed reactor(ID 0.097㎜) facility. The H_S concentration after each desulfurization run was maintained below 10 ppmv from a simulated coal gas of 1% H_2S. The estimated sulfur absorption capacities of ZAC C sorbent were 11.1, 10.9, 11.1, 11.1, 10.9, 10.5 g S/100g sorbent, and the sorption capacity of sorbent was maintained in spite of six times sorption experiments. The maximum SO_2 concentration in regeneration effluent gas agreed with a stoichiometric value of 500℃(ca. 14vol%). In regeneration run, the peak temperature of sorbent bed in the reactor reached up to 750 due to the vigorous exothermicity of regeneration reaction with neat air. While entrainment rate for 70h continuous run in fluidized-bed reactor is 1.07%, the size and the textural properties of ZAC C sorbent also show a little change. Multi-cycle tests in fluidized-bed show that ZAC C sorbent maintains over 50% of its theoretical sorption capacity during 70h run and regeneration reaction undergoes smoothly and completely without side reactions such as sulfate formation.

지지행거를 갖는 배관계의 구조해석

류봉조,임경빈,이규섭,송영봉,공용식,오부진 한밭대학교 생산기반기술연구소 2002 생산기반기술연구소 논문집 Vol.2 No.1

The paper deals with stress and deflection analyses for newly developed PP-pipe structures of LG-Caltex company. In order to calculate the values of stress and deflection, the elements of pipes and its hanger supports are discretized. Through the numerical simulations using commercial FEM code, stresses and deflections of pipes with two or more hanger supports are obtained, and the stability of pipes are checked. Finally, optimal numbers of hanger supports satisfying allowable bending stress is proposed.

아접선력을 받는 보의 동적안정성에 미치는 고유치 감도해석

류봉조,최상경 한밭대학교 산업과학기술연구소 2001 논문집 Vol.5 No.-

This paper deals with the eigenvalue sensitivity of a finite element formulation on vibration and dynamic stability of an elastically restrained cantilevered beam under subtangential forces. Governing equations are derived by energy expressions using extended Hamilton's principle. In order to more quickly and efficiently obtain the critical subtangential force for a given system, a technique which utilizes the eigenvalue sensitivity with respect to the system parameter is introduced. More accurate results are obtained for both variations in the spring position, spring stiffness, as well as the subtangential parameter.

배관계의 진동 및 소음특성

류봉조,임경빈,이규섭,송영봉,임경빈 한밭대학교 생산기반기술연구소 2003 생산기반기술연구소 논문집 Vol.3 No.1

This paper deals with the vibration and noise characteristics of three different kinds of pipe structures (PVC pipe, cast-iron pipe and newly developed pp pipe). In order to measure the structure born noise, an impact force generated by dropping a small ball was applied to three different kinds of pipes. It was confirmed that the structure born noise could be reduced by employing a high damping material. Also, transmission loss of a pipe was investigated for various frequency ranges by using a speaker as a sound source.

비보존계의 동적 안정성과 진동에 관한 연구동향

류봉조 大田産業大學校 1995 한밭대학교 논문집 Vol.12 No.0201

The present paper describes the study trends on vibaration charateristics and dynamic stability of beams subjected to a nonconservative force. One specific objective of the study is to introduce the three groups of non-conservative problems and their characteristics proposed so far. A second objective is to introduce the techinque solving the governing differential equations of nonconservative stability problems approximately. Comparison of the critical force of the experiment and finite element formulation of cantilevers is shown, and the existence of a good correlation between two solutions is highlighted.

마찰력을 받은 자유 Timoshenko보의 진동과 동적안정성

류봉조,이규섭 大田産業大學校 1994 한밭대학교 논문집 Vol.11 No.0201

구속운동을 받는 외팔보의 혼돈진동

최봉문,류봉조,윤충섭,임경빈 大田産業大學校 2000 한밭대학교 논문집 Vol.17 No.1

When the motion of vibrating structure is restrained by the adjacent objects, its vibration frequencies and mode shapes are changed. In general, the vibration characteristics of the system becomes unpredictable. Although the importance of the study on this type of vibration model increases in many engineering areas, most studies conducted to date were focused to the theoretical study on dynamic responses of the structure with stops, including a few experimental works. Specially, the study on the nonlinear phenomena due to the impact between a structure and stops have been mainly performed theoretically. It is, therefore, desired to find a way to have a better understanding on the vibration characteristics caused by the impact of a structure to stops. In the paper, both numerical analyses and experiments are conducted for a fixed-free beam that is restrained by the stops at the free end. The chaotic vibration characteristics of the nonlinear motion and the dynamic response of the system are investigated and presented for various magnetic forces between stops.

불균일 Winkler 탄성 기초위에 놓인 보의 자유진동과 안정성

최봉문,윤영식,윤충섭,류봉조 建陽大學校 1999 建陽論叢 Vol.- No.7

The paper deals with free vibration and stability analysis of a uniform Euler-Bernoulli beam resting on non-uniform Winkler elastic foundation. governing equations for the system are derived by using energy expressions. Solutions are approximately and numerically calculated by means of the finite element formulation. The solutions in the present paper are compared with other available ones without axial force. Finally, stability for cantilever and simply supported beams under a pure axial force is investigated.

탐촉자 시스템의 처짐과 응력해석

공용식,류봉조,정훈택,박홍원 한밭대학교 생산기반기술연구소 2001 생산기반기술연구소 논문집 Vol.1 No.1

This paper deals with stress analysis and deflections for probe stage systems connected to semi-conductor apparatus. Most of the real probe stage systems are composed of three mechanical parts such as slider, X-base and Y-base. In order to calculate the maximum stress and deflection for probe stage systems, three-dimensional finite element model is applied. Numerical results are obtained by changing various design parameters related to the above three parts. Through the numerical simulation, optimal design shape satisfying von Mises yield criterion is presented. The analysis was performed by using commercial COSMOS/M FEA code.