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Study on Spring-Back Effect according to Roll Gap and Forming Velocity of Roll Forming Process
김동홍(Dong Hong Kim),윤대환(Dae-Hwan Yoon),설상석(Sang-Seok Seol),정동원(Dong Won Jung) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.6
The spring-back and bow phenomenon in the roll forming process are important factors regarding the accuracy of evaluation of production goods. The purpose of this study was to determine the influence of spring-back and bow phenomenon according to the main variables (forming velocity and roll gap). The material of the forming sheet was high tension steel (SPFH 590), which has been used commonly in recent years. In order to accurately measure the spring-back and bow phenomenon, the forming sheet was formed into a V-shape. The study was applied to OFAT (One Factor at a Time) experimentation, with respect to the experimental variables (the forming speed and the roll gap). In the experimental results, the forming speed had a small influence on the spring-back and bow phenomenon. However, the roll gap had a greater influence on the springback and the bow phenomenon, as opposed to the forming speed.
김동홍(Dong Hong Kim),채수하(Soo Ha Chae),윤순종(Soon Jong Yoon),윤종열(Chong Yul Yoon),이원복(Won Bok Lee) 한국강구조학회 1996 韓國鋼構造學會誌 Vol.8 No.2
Elastic buckling behavior of an orthotropic plate with an intermediate stiffener, placed parallel to the longitudinal axis, is investigated. Non-dimensional closed-form solution that predicts the buckling strength and the effect of ratio of plate and stiffener widths on the buckling coefficients is developed. When the orthotropic material property in this solution is replaced by an isotropic material property, the result agrees with that obtained by Bulson. Parameter study shows the buckling coefficient of the plate is linearly proportional to the ratio of plate and stiffener widths in the range between 0.2 to 0.4.
발달장애인의 개인예산제 참여경험에 관한 사례연구 : 경계성 발달장애인을 중심으로
김동홍(Kim, Dong Hong),정종화(Jeong, Jong Hwa) 한국장애인복지학회 2021 한국장애인복지학 Vol.51 No.51
본 연구는 장애인 당사자주의에 기초한 개인예산제의 역사적 맥락에 근거하여, 아직 국내에는 제도화되지 않은 개인예산제 시범사업에 참여한 경계성 발달장애인 및 그 액티브 서포터를 대상으로 발달장애인복지서비스 환경, 개인예산제 참여를 통한 자기주도 활동, 개인예산제 참여가 가져온 일상의 변화, 서포터의 역할 등을 연구참여자들의 경험을 통해 심층적으로 탐색한 연구이다. 사례연구 방법으로 Creswell(2007)의 사례 내 분석과 사례 간 분석을 통해 연구참여자들의 경험으로부터 6개의 공통주제를 도출하였고, 이는 “내가 없는 내 방”, “나의 한계령 넘기”, “서포터와의 동행”, “한 걸음 더 가기”, “시행착오의 수레바퀴”, “승리자 거북이”로 나타났다. 본 연구를 통해 경계성 발달장애인을 위한 복지서비스의 운영에 있어 전통적인 제공자 중심의 서비스가 아닌 당사자주도의 개별화 서비스를 지향하는 개인예산제 도입의 가능성을 실천적으로 확인하였고, 향후 제도의 도입 및 안착을 위해 자기주도 생활을 위한 맞춤형(당사자 중심) 훈련과 이를 조력하기 위한 지원체계의 필요를 제언하였다. This study was based on the historical context of the individual budget system based on the disability partyism. It targets people with borderline developmental disabilities and their active supporters who have participated in the individual budget pilot project that has not been institutionalized in Korea. This study explores the welfare service environment of the developmental disability concerned, self-directed activities through participation in the individual budget system, changes in daily life brought about by participation in the individual budget system, and the role of supporters through the experiences of the research participants. This study deduced six common themes from the partcipants experiences by applying Creswell (2007) method of within-case and in-between cases analyses: “My Room Without Me”, “Overcoming My Limits”, “One more step”, “A Walk With Support”, “Rail of Trial and Error” and “Winning Turtle”. This study practically confirmed the possibility of introducing a individual budget system for the borderline developmental disabilities aimed at individualized services, not traditional provider-centered services, and suggested the need for customized (people centered) training and cooperation for self-directed living.
레이저 보조 가공을 위한 2-축 틸팅의 회전각에 대한 연구
김동홍(Dong Hong Kim),정동원(Dong Won Jung),이춘만(Choon Man Lee) Korean Society for Precision Engineering 2014 한국정밀공학회지 Vol.31 No.2
Laser Assisted Machining (LAM) was often used in process of difficulty-to-cut materials. In previous study, Laser assisted machining was a straight path processing using 1-axis manipulator in laser module. But 1-axis manipulator in laser module was able to process only straight path. So, in this study, laser module in laser assisted machining equipped to 2-axis manipulator. 2-axis manipulator has two motors. First motor is machining direction motor and second motor is Vertical Motor. Machining direction motor rotates in the direction of machining and vertical motor rotates vertical direction in the direction of machining. Machining path of laser assisted machining was considered diagonal path and curved path of laser heat source. This study calculated the 2-axis manipulators rotation angle in diagonal path and curved path.
롤 포밍 공정에서의 롤 패스의 수에 따른 스프링 백 영향 연구
김동홍(Dong-Hong Kim),장애(Ya Zhang),정동원(Dong-Won Jung) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.1
This study was analyed V-bending in order to analyze the spring-back phenomenon in the roll forming process. The material of forming sheet used in the roll forming process is high tension steel and the product name of sheet material is POSTEN 60. The most important variable is the number of roll passes (3-Pass, 4-Pass, 5-Pass, 6-Pass and 10-Pass) and other roll forming process variables were fixed. To determine the characteristics of the tension and compression, the forming sheet was analyzed by dividing the layer (Upper and Bottom) in the thickness direction from the center line. The results of FEM simulation analysis was derived to von-mises stress equivalent strain, and the spring-back value was calculated according to the final forming shape. The more number of the roll pass, von-mises stress and equivalent strain value of forming sheet were lowed. Also, spring-back values tended to decrease. The results of this study can be utilized for prediction and trend of spring-back value in the roll forming process applied to high tension steel sheet. So, development time and cost of the roll forming process is expected to be reduced.
Roll Forming Analysis for High Strength Steel Bumper Process
Dong Hong Kim(김동홍),Dong Won Jung(정동원) Korean Society for Precision Engineering 2013 한국정밀공학회지 Vol.30 No.8
Today’s automotive industry is evolving toward low-emissions or zero-emissions high-efficiency vehicles. Highly efficient power sources are required, as well as high strength steels for various parts to increase safety. In this study, we investigated the roll-forming process for the development of high strength, lightweight steel bumper beams. The roll-forming process was analyzed using the software package Shape-RF in combination with a rigid-plastic finite element method model. An optimal roll-forming process based on roll-pass was obtained using finite element method simulations.
레이저 열원을 이용한 난삭재 열처리 공정의 온도 효과에 관한 연구
김동홍(Dong Hong Kim),정동원(Dong Won Jung),이춘만(Choon-Man Lee) Korean Society for Precision Engineering 2014 한국정밀공학회지 Vol.31 No.1
Abstract Recently, Difficult-to-cut materials are used in many manufacturing industry. But the difficult-to-cut materials are difficult-to-cutting process. So difficult to cut material cutting process was used after heat treatment through preheating for easy cutting process. In this study, Inconel 625 was preheating using laser heat source in computer simulation. Laser heat source temperature applied 1290℃ that suitable preheating temperature for Inconel 625. And temperature effects such as temperature distribution for moving heat source studied apply to similar actual process condition. Simulation results for heat treatment effects through temperature distribution verified.
정동원(Dong Won Jung),김동홍(Dong Hong Kim),김봉천(Bong Chun Kim),김동현(Dong Hyeon Kim) Korean Society for Precision Engineering 2012 한국정밀공학회지 Vol.29 No.5
Laser assisted machining is the processing method that preheating brittle materials by laser heat source and cutting the soften area. This processing applied to various industries because it can be cutting difficult-to-cut materials. However, the laser assisted machining appeared the limitations of processing for equipped with the spindle. So, it assumed separate model that spindle and laser assisted machining. In feed, the calculation of changing the angle of the laser module according to preheat point and the shape of the feed is important and it tried easy calculating changing angle of 1-axis Manipulator in separate model. In 3 types feed shape, angle of 1-axis Manipulator was calculated when fixed and moved in the outside of spindle. In this study, suggest 2 types of methods for laser module when fixed and moved.