• 한국의학물리학회지:의학물리
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• 제10권2호
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• pp.63-71
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• 1999

입체조형 치료와 전신 방사선 수술에의 이용을 목적으로 3차원 전신 정위 방사선 치료 장치를 개발하였다. Couch 위에 놓을 수 있는 전신 정위 치료판을 제작하여 방사선 비투과성 카테타 선을 이용하여 치료판 위에 좌표계를 설치하고, MeV-Green(전성 물산, 한국)으로 고정틀을 만들어 환자 자세를 고정시키고, 플라스틱 봉과 봉 지지판을 이용하여 고정틀을 고정하였다. 이러한 설계, 제작으로 입체 조형 치료 등에서 갠트리 회전에 의한 기하학적 제약을 최소화하고 방사선 조사 투과율 이 특정한 방향에서 영향을 받는 문제점을 해소하였다. CT 영상을 통해 치료 표적의 위치를 파악하고 치료판 기준점에 대하여 좌표화하여 모의 치료시와 방사선 치료시의 환자 자세 변화 오차를 줄였다. 3대의 CCTV 카메라를 사용하여 환자 자세 변화를 감지, 수정함으로써 체표변의 외곽선으로 부터 setup 오차를 최소화 할 수 있었다. 치료 효용성을 높이기 위해 이러한 과정을 모니터를 보면서 실시간으로 처리 할 수 있도록 하였고, IDL(Interactive Data Language, RSI, U.S.A.)을 사용하여 image subtraction 방식으로 환자 자세 변화를 가시화하여 오차를 줄이도록 하였다. 내부 장기 움직임에 따른 표적의 움직임을 추적할 목적으로 rotating X-ray 장치를 제작하였다. Landmark 나사를 표적주위 뼈나 표적중심에 삽입하여 이 rotating X-ray 장치를 이용해서 anterior, lateral 두 방향에서 얻은 영상 정보로부터 marker 에 대한 표적의 위치 변화를 가시화 하여 내부 표적의 움직임에 따른 setup 오차를 줄였다. CT 모의치료를 할 수 있도록 IDL 을 이용하여 PC용 모의치료 프로그램을 GUI 환경에서 구현하였고 이 프로그램을 통해서 치료 계획을 위해 CT 에서 수집된 영상정 보를 이용하여 표적을 포함한 장기들의 그래픽 처리, 편집, 전송 등의 작업을 수행하도록 하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권2호
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• pp.75-86
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• 2010

In this work the possibility of obtaining a rectilinear motion of bodies partially or totally submerged without using propellers is evaluated. The system propulsion is based on a pair of counter rotating masses that generate the thrust. The fluid-body system has been schematized in order to carry out a very simple model. Using this model an evaluation of the body motion along a longitudinal direction was performed. The motion equations of the system were written and integrated. The external forces applied to the body depend on its velocity in relation to the water. These forces were obtained by fluid dynamic simulations. Regarding the mechanical configuration suggested, the results obtained show that a certain displacement of the body along a fixed direction is obtainable.

• 한국생산제조학회지
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• 제19권3호
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• pp.307-312
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• 2010

In this study, advanced computational technique for mechatronic analysis has been developed for the efficient design and test of typical machine tool models. Flexible multi-body dynamic (FMBD) analysis method combined with motion controller including control logics is used to simulate typical operation conditions. The present FMBD machine tool model is composed of flexible column structure, rigid body spindle, vertical motion guide (arm) and screw elements. Driving motor clement with rotating degree-of-freedom is interconnected and governed by the designed Matlab Simulink control logic, and then the position of the spindle is feedback into the control logic. It is practically shown from the results that the investigation of designed machine tools with controller can be effectively conducted and verified.

• Wind and Structures
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• 제13권2호
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• pp.169-189
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• 2010

This paper describes the use of coupled Computational Fluid Dynamics (CFD) and Rigid Body Dynamics (RBD) in modelling the aerodynamic behaviour of wind-borne plate type objects. Unsteady 2D and 3D Reynolds Averaged Navier-Stokes (RANS) CFD models are used to simulate the unsteady and non-uniform flow field surrounding static, forced rotating, auto-rotating and free-flying plates. The auto-rotation phenomenon itself is strongly influenced by vortex shedding, and the realisable k-epsilon turbulence modelling approach is used, with a second order implicit time advancement scheme and equal or higher order advection schemes for the flow variables. Sequentially coupling the CFD code with a RBD solver allows a more detailed modelling of the Fluid-Structure Interaction (FSI) behaviour of the plate and how this influences plate motion. The results are compared against wind tunnel experiments on auto-rotating plates and an existing 3D analytical model.

• 한국정밀공학회지
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• 제15권1호
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• pp.130-136
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• 1998

A procedure of stress and strength analysis has been proposed for the centrifuge rotor of composite materials of quasi-isotropic laminates. The goal in this study is to maximize the allowable rotating speed, that is, to minimize maximum strength ratio with the given path length by changing the geometric parameter-outer radius and ply angles in quasi-isotropic laminates. Optimum values of the geometric parameter-outer radius and ply angles are obtained by multilevel optimization. All the geometric dimensions and stresses are normalized such that the result can be extended to a general case. Two dimensional analysis at each cross section with an elliptic tube hole subjected to internal hydrostatic pressures by samples as well as the centrifugal body forces has been performed along the height to calculate the stress distribution with the plane stress assumption, and Tsai-Wu failure criterion is used to calculate the strength ratio. The maximum allowable rotating speed can be increased by changing the radii of the outer surface along the height with the maximum strength ratio under the unit value : The optimal number of ply angles maximizing the allowable rotating speed in quasi-isotropic laminates is found to be the half number of tube hole, and the optimal laminate rotation angle is the half of $[{\pi}/m]$. A $[{\pi}/3]$ laminate, for instance, is stronger than a $[{\pi}/4]$ laminate for the centrifuge rotor of 6 tube hole number even though they have the same stiffness.

• 한국해양공학회지
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• 제19권3호
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• pp.1-10
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• 2005

The effect of rotation on the unsteady laminar flaw past a circular cylinder is numerically investigated in the present study. The numerical solutions for the 2D Navier-Stokes equation obtained, using two different numerical methods. One is an accurate spectral method and the other is a finite volume method(FVM). First, the flaw around a stationary circular cylinder is investigated to understand the basic phenomenon of flaw separation and bluff body wake. Next, the flow characteristics of the laminar flow, past a rotating circular cylinder, are investigated, using a FVM developed in this study. By the effect of rotation, it is seen that values of lift increase, while the values of mean drag decrease. Further, the criteria of angular velocity, at which the Karman vorteces disappear, is also determined.

• Ocean Systems Engineering
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• 제7권4호
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• pp.329-344
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• 2017

This paper introduces a BEM/RANS interactive scheme to predict the contra-rotating propeller (CRP) performance. In this scheme, the forward propeller and the aft propeller are handled by two separate BEM models while the interactions between them are achieved by coupling them with a RANS solver. By using the body force field and mass source field to represent the propeller in the RANS model, the number of RANS cells and the number of required RANS iterations reduce significantly. The method provides an efficient way to predict the effective wake, the steady/unsteady propeller forces, etc. The BEM/RANS interactive scheme is first applied to a CRP in both an axisymmetric manner and a non-axisymmetric manner. Results are shown in good agreement with the experimental data in moderate to high advance ratios. It is proved that the difference between the axisymmetric scheme and the non-axisymmetric scheme mainly comes from the non-axisymmetric bodies. It is also found that the error is larger at lower advance ratios. Possible explanations are given. Finally, some additional cases are tested which justifies that the non-axisymmetric BEM/RANS scheme is able to handle a podded CRP working at given inclination angles.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.32-36
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• 2003

This paper deals with a theoretical method for the design of a biased asymmetric preswirl stator propulsion system which has been used to increase efficiency by the recovery of a propeller slipstream rotational energy by the counter rotating flow of a stator. In the case of full slow-speed ship, the upward flow is generated at the propeller plane by the after body hull form. The generated upward flow cancells the rotating flow of the propeller at the starboard part while it increases at port part. A biased asymmetric preswirl stator propulsion system consists of three blades at the port and one blade at the starboard which can recover the biased rotating flow effectively. This paper provides the design concept which gives more simple and a high degree of efficiency. The model tests for the designed compound propulsion system will be carried out later.

• 전자공학회논문지
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• 제53권1호
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• pp.129-136
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• 2016

초전형 적외선(pyroelectric infrared : PIR) 센서를 이용하여 정지 및 이동인체 감지 시스템을 개발하였다. 감지 시스템은 전원부, 초전형 적외선 센서 인터페이스 회로, 극소형 스템핑 모터, 그리고 디지털 제어부로 구성된다. 정지된 인체를 감지하는 원리는 PIR 센서와 프레넬 렌즈(Fresnel lens)를 부착한 스템핑 모터를 180도로 6초 간격으로 회전하여 인체의 유무를 검출하고 일정기간 동안 인체 감지 신호가 없으면 모터를 정지시키는 것이다. 제안한 감지 시스템에 필요한 제어 알고리즘을 개발하였다. 실험을 통해 감지 시스템은 $37^{\circ}C$의 정지 및 이동하는 인체에 대하여 6m의 감지거리와 30도의 감지 각도를 갖고 있다는 것을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.179-184
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• 2001

A shrouded rotating disk airflow has a simple figure on geometric basis, but has various and complicated forms of flow. This flow type can be applied to many turbo devices such as information storage device(optical disk). Circumferential velocity frequency in the middle plane between disk and shroud wall is measured using laser Doppler velocimeter. Solid body region of flow was founded when low Reynolds number relatively. Through the informations of the experimental results. we could examine the number and distribution of the vortices. When Reynolds number $3.80{\times}10^5$ there is a dominant frequency of which vortices number is 5.