고분자 포움의 초음파 가공 ( Ultrasonic Processing of Polymer Foam )

변성광,윤재륜 대한기계학회 1989 대한기계학회 춘추학술대회 Vol.- No.-

인장시편의 사출성형시 충전과정의 수치해석에 관한 연구

변성광,정정훈,Byeon, Seong-Gwang,Jeong, Jeong-Hun 한국섬유공학회 1996 한국섬유공학회지 Vol.33 No.2

In order to accomplish injection molding process effectively and to eliminate the need for costly iteration of mold design and tooling, analysis of the filling stage is essential. For complex problems, numerical methods are commonly used for modeling of the filling stage. With development of CAD/CAM, numerical methods are widely used for simulation of the injection molding which is one of the most important net shape manufacturing processes. For better implementation of numerical analysis, a delivery system was considered by employing tubular elements. Pressure and mold wall temperature variations were measured by Pressure transducers and thermocouples and the results were compared with simulations. It has been shown that the results of the experiment and the simulation are in good agreement with respect to melt fronts and pressure profiles. in thes study, a hybrid finite element/finite difference control volume method and an automatic mesh generation scheme were developed and successfully applied to numerical simulation of filling process in injection molding. The developed program provided useful information on flow front advancement, pressure Profile, weld line location and shape, and temperature distribution during mold filling stage.

고분자 포움의 초음파 가공

변성광,윤재륜 대한기계학회 1989 대한기계학회논문집 Vol.13 No.4

본 연구의 목적은 낮은 포화 압력하에서의 초음파에 의한 미세포 포움 구조 획득의 가능성을 평가하기 위한 것으로, 이 초음파 가공을 고분자 포움의 연속적인 압출 가공에 적용하기 위한 기초 연구를 이론적 및 실험적으로 수행함에 있다.따라서 미세포구조의 획득이 본 연구의 목적은 아니며 초음파를 이용한 열가소성 수지내의 핵생성 거동에 대한 고찰을 하고자 한다. Ultrasonically induced bubble formation in thermoplastic matrix was investigated experimentally and theoretically. polystyrene was saturated with nitrogen under the pressure of 0.2 to 3.45 MPa in a pressure chamber, followed by pressure release and ultrasonic bubble nucleation. Zinc stearate was added to polystyrene as the nucleating agent to induce heterogeneous nucleation. Various mixture of low density polyethylene and polyethylene wax was also saturated with the gas. The foamed specimens with or without ultrasonically induced bubble nucleation was modeled by modifying the classical nucleation theory. The rate of ultrasonic nucleation was predicted for homogeneous and heterogeneous nucleation at a conical cavity. This study showed that the heterogeneous and heterogeneous nucleation at a conical cavity. This study showed that the heterogeneous nucleation must be employed for ultrasonic production of bubbles in a viscous fluid and the homogeneous nucleation for ultrasonic production of bubbles in a low viscosity fluid.

[논문] 시각 문화콘텐츠로서의 TV 영상자막 연구

변성광 동국대학교 영상문화콘텐츠연구원 2013 영상문화콘텐츠연구 Vol.6 No.-

오늘날 TV예능프로그램에서 영상자막은 매우 중요한 영상연출 수단이 되고 있다. 특히 많은 자막을 사용하는 리얼 버라이어티 프로그램에서는 오히려 영상보다 자막이 더 중요한 메시지 전달 수단으로 사용되고 있는 현실이다. TV 영상자막은 그동안 영상의 보조적 장치이자 수단이며 방송영상의 열린 미디어텍스트의 기능을 제한하는 닫힌 미디어텍스트로서의 부정적인 기능이 부각되어왔다. 하지만 오늘날 오락프로그램에서 사용되는 영상자막들은 이제 시청자들에게 더 이상 영상시청 방해의 대상이 아니다. 오히려 화면의 내용보다 더 재미있는 내용을 영상자막을 통해 접하고 즐길 수 있는 하나의 독립적인 시각 문화콘텐츠로 발전하고 있다. 이러한 현상을 분석하기 위해서 본 연구에서는 최근 가장 화제가 되고 있는 ‘무한도전’, ‘1박2일’, ‘꽃보다 할배’ 등 리얼버라이어티 프로그램에 사용된 영상자막을 분석했다. 각각의 프로그램에 사용된 영상자막을 1) 상황 설명형 자막, 2) 대사형 자막, 3) 코믹 및 효과 자막, 4) 관찰자 시점형 자막으로 크게 네 가지로 분류하고 다시 그 자막들이 수행하고 있는 기능들을 살펴보았다. 그 결과 TV 영상자막은 TV 영상매체가 표현하고자 하는 화면을 보조하기 위해서 사용되던 영상자막의 범주를 벗어나 TV 영상자막 자체가 또 다른 하나의 의미생성소로서의 기능을 하고 있다는 것을 알 수 있다. 그 결과 프로그램을 시청하는 시청자들은 화면을 통한 재미는 물론 영상자막으로 인해서 새로운 즐거움을 느끼고 있었고 바로 이러한 영상자막의 2차적인 의미생성 기능이 본 연구에서 분석하려고 했던 TV 영상자막의 독립적인 시각 문화콘텐츠로서의 역할이다. TV 영상자막은 문화콘텐츠가 가지는 기본적인 속성인 스토리를 가지고 즐거움을 생산하며 그 자체로 유통 판매 할 수 있는 문화상품의 역할을 하고 있었고, 또한 화면을 분석한 바와 같이 프로그램의 성격과 특징을 나타낼 수 있다. 이제 TV 영상자막은 더 이상 영상의 부수적이고 보조적인 표현수단이 아니고 그 자체로 가치와 의미를 갖는 시각 문화콘텐츠의 역할을 하고 있다고 볼 수 있겠다. Today visual subtitles in TV entertainment programs have become a very important means to create images. Particularly in real variety programs, which use lots of subtitles, subtitle is used as the more important means to deliver important messages, rather than images. TV image subtitle had emerged its negative function as a closed media text which restricted the function of open media text of broadcasting image, which used to be the accessorial equipment and means of image in the meantime. However, today’s image subtitle used in entertainment programs does not interrupt the audience with watching images any more. The other way, it is developing as an independent visual culture content through which the audience can meet and enjoy more interesting content rather than that on the screen. In order to analyze this phenomenon, this research analyzed image subtitles used in the real variety programs, e.g. ‘Moohandojeon’, ‘Ilbak-Yi-yil(1 Night 2 Days)’, ‘Kkotboda halbae(Grandfathers than flowers)’, etc., which are becoming national topics. The researcher classified the image subtitles used in each of the programs largely into four groups according to 1) situation explaining subtitles, 2) dialogue subtitles, 3) comic and effect subtitles, 4) observer’s viewpoint subtitles, and again investigated the functions that the subtitles perform. As the result, TV image subtitles were turned out to function another creator of meaning by itself, going beyond the range of image subtitles which had been used to assist the images that TV media of image intended to express. In conclusion, the audience of programs enjoyed a new pleasure thanks to image subtitles as well as fun through the screen, and this secondary meaning-creating function of the image subtitles is the role of independent visual culture contents of TV image subtitles that this research intended to analyze. TV image subtitle produces fun with the story, which is the basic attribute that culture contents have, taking the role as a cultural production which can distribute and sell by itself, also, as it was turned out through the analysis of screen, it can display the nature and characteristics of programs. Now, TV image subtitle is not an ancillary and accessorial means of expression of images any more, but it can be said to take a role of visual culture contents, which has value and significance in itself.

압입축 끝단의 손상저감을 위한 보스부 형상 최적설계

변성광 한국기계가공학회 2015 한국기계가공학회지 Vol.14 No.3

The press-fit shaft is an important part used in automobiles, vessels, and trains. This study proposes an optimized design method to reduce damage that may occur in the press-fitted shaft by modifying the shape of the boss step of the press-fitted shaft. To reduce the time and cost of running the optimized design method, an approximate design optimization is applied and an optimized algorithm is generated using a genetic algorithm that is widely used in engineering fields and an approximate model using a response surface method. The planned experiments for the data that are needed to generate the approximate model use a central composite design (CCD) and Latin hypercube sampling (LHS), and the results of the approximate optimization using the above two design of experiments are to be compared.

압입축의 파손 저감을 위한 설계 방법에 대한 연구

변성광(Sung-Kwang Byon),최하영(Ha-Young Choi),이동형(Dong-Hyung Lee) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.5

A press-fitted shaft is an essential part used in industrial machines, and it is generally used to transmit large quantities of power. Very high contact pressure occurs at the end parts of the contact between the shaft and boss, which are press-fitted shaft components. Such contact pressure not only damages the contact surface of a press-fitted shaft but also reduces its fatigue strength. To improve a press-fitted shaft’s fatigue strength, the contact pressure on the contact surface, which directly affects the fatigue strength, should be minimized. Thus, in this study, the design configuration optimization of the end part of the boss was based on the approximate optimization method and was aimed at minimizing the contact pressure at the end of a press-fitted shaft. Comparison of the contact pressure and the contact stress of a conventional press-fitted shaft with those of the optimized press-fitted shaft showed that the boss design of the optimized press-fitted shaft effectively improved the fatigue life.

듀얼 레일 형상에 적합한 철도차량의 차륜 형상 설계

변성광(Sung-Kwang Byon),이동형(Dong-Hyeong Lee),최하영(Ha-Young Choi) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.3

When a wheel profile of a train-tram is designed, both train and tram tracks should be considered. This study designed a wheel profile that enables high-speed driving(200km/h) on the train track and low speed driving on the tram track with multiple sharp curves. The study used the approximation optimization method to reduce cost and time, used the sequential quadratic programming method as the optimized algorithm, and the central composite design and response surface method as an approximate model. The optimized wheel shape based on this approximation optimization method reduced wear of the initial wheel showed a better performance in terms of derailment and lateral force.

초음파 진동을 이용한 빙축열 시스템의 아이스 슬러리 생성 연구

변성광(Byon, Sung-Kwang),공춘수(Gong, Chun-Su),김남웅(Kim, Nam-Woong) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.2

아이스 슬러리는 유동성이 좋고 증발잠열이 커서 빙축열 시스템의 전열 유체로 선호되고 있다. 일반적으로 아이스 슬러리는 과냉각된 유체로부터 생성되는데, 동결이 과할 경우 배관을 막히게 하는 단점이 있다. 더욱이 아이 스 슬러리 생성을 쉽게 하기 위해 과냉각온도를 낮출 경우 빙축열 시스템의 효율을 떨어뜨리기도 한다. 따라서 아이 스 슬러리 생성을 효율적으로 제어할 수 있는 방법이 요구되고 있다. 본 논문에서는 초음파 진동에 의해 과냉각수에 캐비테이션 충격을 가하여 아이스 슬러리를 생성하는 새로운 방식의 빙축열 시스템에 관한 실험연구를 수행하여, 초 음파 진동과 아이스 슬러리 생성과의 상관관계를 규명하고, 초음파 진동이 아이스 슬러리 생성을 성공적으로 촉진할 수 있음을 확인하였다. Ice slurry that is a mixture of fine ice crystals and liquid water is a widely used working fluid in the ice thermal energy storage system due to its flowability and large latent heat of fusion. Generally ice slurry is made from supercooled water. But the excessive supercooling causes the water to freeze even worse to block the pipe. Additionally large degree of supercooling of water degrades the efficiency of the ice thermal energy storage system. Therefore the effective method to control the phase change from supercooled water to ice slurry is needed. In this paper we experimentally studied a novel method to generate the ice slurry from the supercooled water using the ultrasonic vibration. It was found that the cavitation impact of supercooled water by ultrasonic vibration can help the generation of ice slurry.

의료용 베드 헤드 콘솔의 강도조건을 고려한 최적 설계

변성광(Sung-Kwang Byon),최하영(Ha-Young Choi),이봉구(Bong-Gu Lee) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.3

Medical bed head consoles (BHC) are generally used to increase the efficiency of medical equipment and speed the medical treatment response time. The BHC design has been consistently improved including a movable shelf unit that is embedded to mount stably medical instruments on the lower part of the main console. The cost of a BHC can be reduced through design optimization to limit the overall weight. However, as the size of a head console might decrease due to design optimization, the BHC deflection could be increased. In this study, multi-objective optimal design was adopted to consider this BHC design problem. In order to reduce the cost of optimization planning, an approximate model was applied for the design optimization. In the context of approximate optimization, we used the response surface method and non-dominant sorting genetic algorithm developed from various fields. Multi-objective optimal solutions were also compared with a single objective optimal design.

근사 최적화 방법을 이용한 사출금형 설계에 관한 연구

변성광(Sung-Kwang Byon),최하영(Ha-Young Choi) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.6

The injection molding technique is a processing method widely used for the production of plastic parts. In this study, the gate position, gate size, packing time, and melt temperature were optimized to minimize both the stress and deformation that occur during the injection molding process of medical suction device components. We used a central composite design and Latin hypercube sampling to acquire the data and adopted the response surface method as an approximation method. The efficiency of the optimization of the injection molding problem was determined by comparing the results of a genetic algorithm, sequential quadratic programming, and a non-dominant classification genetic algorithm.