전조 핀관의 열전달 성능에 관한 연구

조동현 대진대학교 생산기술연구소 1998 생산기술연구소 논문집 Vol.1 No.-

Low integral-fins tubes and finned tubes with caves are tested. In case of condensation CFC-11 condensates at saturation state of 32℃ on the outside surface cooled by inside cooling water flows. And in case of boiling the refrigerant evaporates at a saturation state of 1 bar on the outside tube surface and heat is supplied by hot water which circulates inside of the tube. The tube having fin density of 1299fpm and 30grooves has the best boiling overall heat transfer coefficient. However, as far as boiling heat transfer coefficient concerns, fin tubes with cave show higher value than low fin tube having fin density of 1299fpm and 30 grooves.

평관 및 낮은 핀관으로 제작한 열사이폰의 열전달 성능에 관한 실험적 연구

조동현 대진대학교 생산기술연구소 1999 생산기술연구소 논문집 Vol.2 No.-

관 외벽에 낮은 핀을 가진 수직 및 경사 열사이폰의 열전달 성능에 관한 실험적인 연구를 하였다. 관 외벽에 낮은 핀을 가진 이상밀폐 열사이폰의 열전달 성능을 비교 분석하기 위하여 동일한 규격의 평활관에서도 실험적인 연구를 하였다. 작동유체는 증류수와 CFC-30을 사용하였다. 열사이폰의 경사각과 작동온도를 변화시키면서 실험한 결과 경사각의 변화에 따라 열사이폰의 열전달 성능은 큰 변화를 나나태었다. 그리고 평활관으로 제작한 열사이폰보다 관 외벽에 낮은 핀관을 가진 낮은 핀관으로 제작한 열사이폰의 열전달 성능이 높게 나타났다. 그러므로 관외벽에 낮은 핀관을 가진 경사 열사이폰을 태양에너지 열교환 장치로 활용할 경우 고성능화, 소형화 할 수 있다. Experimental investigation of hte heat transfer performance of closed-type thermosyphon with low intergral-fins in which boiling and condensation occurred has been carried out. For comparison, tests are made using a plain thermosyphon having the same inside diameter and outside diameter as that of the root of fins of finned thermosyphon Water and CFC-30 have been used as the working fluids. The inclination angle of thermosyphon and the operating themperature have been used as the experimental parameters. As a result of the experimental investigation we can state the inclination angle of a thermosyphon has a notable influence on the condensation coefficient and the optimum inclination shows from 20˚to 50˚. The maximum overall heat transfer coefficients enhancement of thermosy;hon (i.e, the ratio of everall heat transfer coefficient of finned to plain tubes)is about 1.3 Also, the inchined closed two-phase thermosyphon with low intergral-fins can be used to achieve some inexpensive and compact heat exchangers in solar energy utilization at low temperature.

스탬핑 성형해석을 위한 유한요소의 자동생성

유동진,윤정환 대진대학교 생산기술연구소 1999 생산기술연구소 논문집 Vol.2 No.-

In the present study, a general method for the mathematical description of arbitrarily shaped surface is proposed by introducing the parametric surface. A polynomial function is employed to descrive the base parametric surface and the boundary curves are defined to describe arbitrary three - dimensional trimmed surfaces. For the mesh generation of initial sheet blank, a grid-based mesh generation algorithm using quadtree is proposed. In order to generate the finite element mesh for tool surface, a hybrid method based on the grid approach and the Delaunay triangulation if proposed. To verify the validity of the proposed method, automatic mesh generation is carried out for some chosen complicated parts including actral automotive panel.

CPLD를 이용한 3채널 PWM 신호발생기의 설계

정규홍 대진대학교 생산기술연구소 2000 생산기술연구소 논문집 Vol.3 No.-

In this research, Pulse-Width-Modulation signal generator of which carrier frequency and resolution is superior to the that of conventional peripheral functions of micro-controllers was designed with the combination of digital logic gate and 3-channels of PWM signal generators were implemented with the single Altera's EPM7128S CPLD. We established the model of digital logic circuit and verified its overall function with MAX+PLUS II software which is offered by Altera for digital logic design engineers. From the experiment of PWM signal test on the integrated hydraulic system control board, we can conclude that it works fairly good as we expected and since the speed of PLD is quite fast, there is no parallel-interfacing problem with the host micro-controller. 주요기술용어: Pulse-Width-Modulation(펄스폭 변조), CPLD(고집적 프로그래머블 논리소자)

승용차의 시계 요소 조사 및 개선 방향

최재호 대진대학교 생산기술연구소 1999 생산기술연구소 논문집 Vol.2 No.-

자동차 내장 설계의 주요 검토 사항으로 거주성, 조작성, 시인/시계성, 승강성, 적재성, 안전성 등을 들 수 있다. 특히, 승용차의 주행 시 운전자는 주위 환경에서 일어나는 상황의 대부분을 눈을 통해 인식하게 되므로, 주행 중 운전자에게 충분한 시계를 확보해 주는 ㄴ것이 자동차의 설계에서 중요한 요인이 된다. 본 연구에서는 시계성을 중심으로 미국의 FMVSS(Federal Motor Vehicle Safety Standard), 유럽의 EEC(European Economy Community), 한국공업규격 등ㅇ에서 규정하고 있는 시계 요소들을 조사 비교하고, 시계성 평가의 기준으로 활용한다. 시계성을 평가하기 위해 전방가시거리, 전방수평시계, Inside Rear View Mirror와 Outside Rear View Mirror를 통해 볼 수 있는 Viewing angle, Inside Rear View Mirror와 95%ile Eyellipse와 높이 등의 요소를 측정하였다. 측정결과는 승용차의 운전 공간 내의 Optimal Eye Poing를 결정하는 데 이용되며, 시인/시계성을 개선하는 Seating Packaging Procedure 개발의 기초 자료로 활용될 수 있을 것이다.

휠로더 자동변속기용 속도센서 신호처리회로의 설계 및 분석

정규홍 대진대학교 생산기술연구소 1999 생산기술연구소 논문집 Vol.2 No.-

In this work, an appropriate seed signal conditioning circuit is designed on the basis of the characteristics of wheel loader speed sensor output voltage and the each electronic component which are obtained from experiment. We investigant the problems of the previous version of signal conditioning circuit for hall-effect sensors of passenger-car. From the experimental result, we could conclude that the newly designed signal conditioning circuit that is consists of high-pass filter and operational amplifier comparator is adequate for interfacing the wheel loader speed sensors to TCU.

Approximation Models for Multi-Objective Optimization

Yeun, Y.S.,Yang, Y.S.,Jang, B.S.,Ruy, W.S. 대진대학교 생산기술연구소 2000 생산기술연구소 논문집 Vol.3 No.-

In engineering problems, computationally intensive high-fidelity models or expensive computer simulations hinder the use of standard optimization techniques because they should be invoked repeatedly during optimization, despite the alarming growth of computer capability. Therefore, these expensive analyses are often replaced with approximation models that can be evaluated nearly free. However, due to their limited accuracy, it is practically impossible to exactly find an actual optimum(or a set of actual noninferior solutions) of the original single(or multi-objective) optimization problem. Significant efforts have been made to overcome this problem, The model management framework is one of such endeavours. The approximation models are sequentially updated during the iterative optimization process in such a way that their capability to accurately model original functions especially in the region of our interests can be improved. The models are modified using one or several sample points generated by making good use of the predictive ability of the approximation models. However, theses approaches have been restricted to a single objective optimization problem. It seems that there is no reported management framework that can handle a multi-objective optimization problem. This paper will suggest strategies that can successfully treat not only a single objective but also multiple objectives by extending the concept of sequentially managing approximation models and combining this extended concept with the Genetic Algorithm which can treat multiple objective s(MOGA). Consequently, the number of exact analysis required to converge an actual optimum or to generate a sufficiently accurate Pareto set can be reduced considerably. Especially, the approach for multiple objectives will lead to the surprising reduction in the number. We will confirm these effects through several illustrating examples. Key words : optimization, approximation model, model management framework, multi-objective

Petri-Net Synthesis for FMS Control

Kim,Hoon-Tae 대진대학교 생산기술연구소 1998 생산기술연구소 논문집 Vol.1 No.-

Developing FMS controllers has been a difficult problem largely because of the variety of the system configuration. The purpose of this paper is to develop a method of building an FMS controller. The controllerconsists of a control module, an execution module. THe control module generates abstract-level execution requests by identifying a set of activities that can be executed without creating any irregular state. The execution module transmits the requests to physical device controllers and reports back the completion of the requests to the control module. Both of these two modules use Petri Net-based models. In this paper, a controllable Petri Net model is automatically synthesized from declarative definitions provided by a user. An execution Petri Net model for the execution module is designed to ensure the consistency between the control module and the real target system.

통합 BOM 관리 시스템 설계에 관한 연구

강금석,신기태 대진대학교 생산기술연구소 1998 생산기술연구소 논문집 Vol.1 No.-

In this study, we introduce an integrated BOM management system managing multiple views integratedly. This system will not only reduce the amount of data but also reduce the incrooectness and the inconsistency in data. The aim of this research is to provide the structure of integrated BOM management system consisting of a common database schema and supporting multiple views used in different areas of business functions. We decomposed the structure of the proposed system into four layers respecting ANSI-SPARC database three level schema and designed each layer. Four layers are external layer, conceptual layer, logical layer, and physical layer. We used HSPN method for effective BOM explosion and implosion and extended it to support multiple views. At logical layer and physical layer, we designed database schema considering the relational database model.

기본곡면을 이용한 사각형 유한요소의 자동생성

유동진,김성무 대진대학교 생산기술연구소 2000 생산기술연구소 논문집 Vol.3 No.-

Many surface theories and techniques have been developed and being applied to the development of commercial CAD packages. Especially many complex geometric shapes can be defined simply by combining and operating primitive surface. In this paper some primitive surface theories are used to generate the rectangular mesh on the surface. These surface generation algorithms include a bilinear surface, a ruled surface and a pipe shape surface generations with specific base curves. Surfaces generated from theses algorithms are eventually transformed into the rectangular meshes. 주요기술용어 : Primitive surface(기본곡면), Finite Element(유한요소), Ruled Surface(룰드곡면), Bilinear Surface(선형곡면)