전단변형을 고려한 역대칭 적층판의 해석

정진오(Jin Oh Jung),임성순(Sung Soon Yhim),장석윤(Suk Yoon Chang) 한국강구조학회 1993 韓國鋼構造學會誌 Vol.5 No.2

Plates laminated by the multilayers of the composite materials show different behaviors at each layer. Coupling effects of shearing stresses at layers make it more difficult to analyze them. In this paper, it is possible to analyze the simply-supported cross-ply or simply-supported antisymmetric angle-ply laminated composite rectangular plates in closed-form solutions of linear theory. From the numerical results, it is clarified that the effects of transverse shear strain and coupling between stretching and bending due to variation of ply-angle are quite significant components for small ratio of side length to thickness. Theory and analysis of laminated plate proposed in this paper should be used in design of them.

감마선을 이용한 아크릴산이 도입된 골조직공학용 PCL/BCP 나노섬유 지지체의 개발

정진오(Jin-Oh Jeong),정성린(Sung In Jeong),신영민(Young Min Shin),박종석(Jong-Seok Park),권희정(Hui-Jeong Gwon),안성준(Sung-Jun An),허중보(Jung-Bo Huh),신흥수(Heungsoo Shin),임윤묵(Youn-Mook Lim) 한국고분자학회 2015 폴리머 Vol.39 No.3

Polycaprolactone(PCL)과 biphasic calcium phosphate(BCP)는 생체적합성 및 골 형성 촉진 등으로 인해 정형외과 소재로 사용되고 있다. 하지만, PCL은 표면이 소수성으로 인해 세포의 부착 및 증식에 제한적이기 때문에 이를 극복하기 위해 본 연구에서는 감마선을 이용하여 골 재생을 위한 친수성이 향상된 PCL/BCP 나노섬유를 제조하였다. 나노섬유는 전기방사를 통해 제작했으며, 감마선을 이용하여 acrylic acid(AAc)를 도입하였다. SEM을 통해 나노섬유 표면을 확인하였고, AAc가 도입된 나노섬유 위에서 MG63의 초기 생존율이 현저히 증가한 것을 확인하였다. 알칼리성 포스파테이즈 활성은 1.239±0.226 nmole/μg/min으로 개질되지 않은 나노섬유(0.590±0.286 nmole/μg/min) 보다 증가하였다. 따라서, AAc가 도입된 PCL/BCP 나노섬유는 골조직 재생에 활용될 수 있을 것으로 기대된다. Polycaprolactone (PCL) and biphasic calcium phosphate (BCP) have been considered as useful materials for orthopedic devices and osseous implants because of their biocompatibility and bone-forming activity. However, PCLbased scaffolds have hydrophobic surfaces reducing initial cell adhesion or proliferation. To overcome the limitation, we fabricated surface-modified PCL/BCP nanofibers using gamma-irradiation for bone tissue engineering. PCL/BCP nanofibers were prepared by electrospinning and then we supplemented hydrophilicity by introducing acrylic acid (AAc) through gamma-irradiation. We confirmed the surface of nanofibers by SEM, and then the initial viability of MG63 was significantly increased on the AAc grafted nanofibers, and alkaline phosphatase activity(1.239±0.226 nmole/μg/min) improved on the modified nanofibers than that on the non-modified nanofibers(0.590±0.286 nmole/μg/min). Therefore, AAc-grafted nanofibers may be a good tool for bone tissue engineering applications.

브레이크 패드에 함유된 섬유재의 성분변화에 따른 마찰특성 연구

박정환(Jung Hwan Park),정진오(Jin Oh Chung),김향래(Hyang Rae Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

To access the effect of fiber ingredients on friction characteristics of brake pad material, two kinds of specimens with different fibers were prepared. Fiber materials used in the study are aramid and acrylic fiber respectively, while keeping other ingredients, such as binders, lubricants, abrasives and fillers the same. Two different materials(FC25 and FC17) were used for disk rubbing the friction material. The friction materials were tested by 1/5 scale brake dynamometer and test mode is modified JASO C406-P1. The temperature changes showed almost the same variation throughout the entire mode of fiction test regardless of different materials. However the tested friction coefficient of each specimen showed a variation with different disks and friction materials. In the effective mode, friction coefficients of aramid-containing friction material showed higher friction coefficients than acrylic-containing friction material. The excellent fade resistance was observed when aramid-containing friction material was rubbed against the FC25 disk. The Recovery of fiction coefficient after fade was suitable for all the specimens except that acrylic-containing friction material was rubbed against the FC25 disk. On the other hand, high temperature test result that aramid-containing fiction material exhibited higher friction coefficients than acrylic-containing friction material. The friction stability was excellent for specimens containing acrylic fiber.

LCD TV BOTTOM CHASSIS 스프링백 해석

이성근,정진오,김승규,정완진,Lee, Sung-Geun,Jung, Jin-Oh,Kim, Seung-Kyu,Chung, Wan-Jin 한국금형공학회 2012 한국금형공학회지 Vol.6 No.1

In the manufacturing of a LCD TV bottom chassis, the distortion after forming should be suppressed below pre-defined amount to avoid contact with electric components. Finite element analysis procedure of forming and springback of a LCD TV bottom chassis is developed to investigate the distortion behaviour. It is shown that after the first forming large distortion occur due to uneven metal flow induced by various embossings. In the second forming, distortion is decreased by introducing bead that absorbs the excessive metal flow. It is proved that analysis method could describe these behaviour effectively. The developed analysis method can be used to find the proper location and shape of bead more quickly and effectively.

댄스스포츠심판의 스트레스원인 탐색

이영란 ( Young Ran Lee ),정진오 ( Jin Oh Jung ) 한국리듬운동학회 2011 한국리듬운동학회지 Vol.4 No.1

The purpose of this research is to identify the stressors experienced by DanceSport adjudicators. Participants in this research have been selected from among DanceSport adjudicators who were previously DanceSport athletes in the Professional Event of the Standard Dance Division and who have adjudication experience of more than ten years. Data has been collected from October 1, 2008 to April 15, 2009, about six months. As for in-depth interviews, about 60 to 90 minutes were spent per interview based on a semi-structured questionnaire. In terms of analysis methods: domain analysis, taxonomic analysis, and component analysis as proposed by Spradley(1979) were conducted in an inductive analysis method. As a result of having in-depth interviews with five research participants and analyzing the interview results, five main stressors have been identified. The first stressor is found to be judgment protest and error. Judgment protest is recognized as a stressor of adjudicators. when competition results fail to correspond with DanceSport athletes` expectations. Also, judgment error is regarded as a stressor: adjudicators get stressed when there is a discrepancy between an athlete`s current lower-than-expected competition performance and the judge`s high expectation resulting from his/her previous good competition results(the hallo effect). The second stressor concerns adjudicators` negative speech and action and an unreasonable allotment of adjudicators. Adjudicator`s negative speech and action are found to be conversation between athletes and adjudicators and inappropriate attire. As for an unreasonable allotment, when the relationship between two adjudicators who used to be in a student-teacher relationship has become uncomfortable, the adjudicator who used to be the other adjudicator`s student receives stress when he/she is assigned to the same DanceSport event. Also, the assignment of adjudicators to unsuitable events and tacit pressure by parties related to DanceSport competitions are pointed out as stressors. The third stressor is the mental burden resulting from discrepancies in judgment results between adjudicators in major competitions. The fourth stressor concerns negative feedback between adjudicators. adjudicators feel pressured to give favor to students of their colleagues due to personal connections, and collusion among adjudicators(negative feedback) is found to be a stressor. Fifth, other stressors include winning adjudicators over to their side, the physical burden, and domestic problems and financial difficulties. As stated above, the research participants` stressors have been identified through their own language and interpretation based on their adjudication experience built over a number of competitions. Thus, this research is considered to provide empirical knowledge that enables us to directly understand and explain adjudicators` stress in competitions.

브레이크페드에 함유된 연마재의 성분변화에 따른 마찰특성 연구

서영철(Young Chul Seo),정진오(Jin Oh Chung),박정환(Jung Hwan Park) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_3

To access the influence of a type and content of abrasive materials on friction characteristics, five kinds of specimens with different abrasive components were specially manufactured by a company for this study. Specimens have different abrasive components as ZrSiO₄, Zeolite, ZrO₂, Al₂O₃, while keeping other components fibers, binders, lubricants, fillers, besides the same. The specimens were tested using a 1/5 scale brake dynamometer to analyze the friction characteristics of the abrasive material. After the friction test, rotors of specimens were cut and polished to observe transfer film formation on the rotor surface by SEM, and the EDX analysis is followed to study the component variation through the transfer film thickness.

브레이크 패드에 함유된 아라미드 섬유와 미네랄 섬유의 마찰특성 연구

공지운(Ji Woon Kong),박정환(Jung Hwan Park),정진오(Jin Oh Chung),김향래(Hyang Rae Kim) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Friction characteristics of automotive friction materials according to the types of fiber were investigated by using a 115 scale brake dynamometer. fiber materials used in the study are aramid, mineral fiber respectively, while keeping other ingredients, such as binders, lubricants, abrasives, fillers the same. In the entire mode of friction test the friction coefficients of all the specimens show different among different pads even under the same temperature condition. In the effectiveness test, friction coefficients decrease with increase in the mineral fiber and aramid-containing friction material FB4 shows the highest coefficients. In the 1st fade test, fade phenomena is decreased with increase in the mineral fiber. The fade rate of FB1(scotching) is higher than the FB1. And 2nd fade rate is higher than 1st fade rate for each specimen. All the specimens tested showed a good recovery rate. The standard deviations of friction coefficient during entire mode for all the specimens were more stable with increase in the mineral fiber and FB1(scotching) is more stable than FB1.

VR 블록코딩을 활용한 소프트웨어 교육 개선방안 연구

유상욱 ( Sang-wook Yoo ),이청호 ( Cheong-ho Lee ),정진오 ( Jin-oh Jung ),조성혁 ( Sung-hyuk Cho ),한솔 ( Sol Han ) 한국정보처리학회 2021 한국정보처리학회 학술대회논문집 Vol.28 No.2

소프트웨어의 중요성이 커지면서 코딩열풍이 불고 있다. 코딩열풍은 소프트웨어 교육 의무화로 이어졌다. 본 연구는 소프트웨어 교육 개선방안으로 VR 블록코딩을 제안하였다. 본 연구에서 제안한 VR 블록코딩은 최단경로 찾기 모델을 기반으로 교육과정에 따른 컴퓨팅 모델을 설계하여 구현하였다. 컴퓨팅 모델은 입력과 출력, 변수와 연산, 제어구조, 함수생성 및 호출이다. 본 연구에서 제안한 VR 블록코딩이 가능해짐에 따라 초현실사회에 새로운 디지털 교육 콘텐츠에 기여할 것이다.

정보디자인의 원격교육 교수설계 모델 연구

정진오 한국디자인과학학회 1998 디자인과학연구 Vol.1 No.-

시각정보디자인은 정보의 홍수 속에서 빠른 속도로 지식이 변화해 가는 정보 혁명의 시대에 "정보의 가치"를 창조하는 중요한 학문으로 발전하고 있다. 하지만 자신이 필요로 하는 올바른 정보를 평가하여 선택할 수 있고 정보를 스스로 개발할 수 있으며, 능률적으로 문제를 해결할 수 있는 능력을 가진 창조적인 디자이너를 기르기 위한 디자인 정보화 교육의 도입은 아직은 초보적인 상황이다. 이는 교육의 사회적 중요도에 비추어 볼 때 새로운 미디어와 기술의 도입에 상대적으로 신중해야 할 필요가 있기 때문이다. 하지만 디자인 각 분야에서 컴퓨터 기술은 이미 역행할 수 없는 중요한 역할을 수행하고 있으며 이는 교육적으로도 새로운 패러다임을 예고하고 있다. 본 연구는 인터넷을 활용한 새로운 다자간 공유 커뮤니케이션 미디어의 도입에 따른 디자인 분야의 교육적 효과와 문제에 대한 체계적 이해와 가능성을 모색하기 위한 것이다. Visual Information design is developing to important study that is creating the value of info. in the information revolution age. Introduction of information-oriented education is a kind of transitional situation to bring up the spontaneous human being that can solve the problem efficiently, create the information themselves, and are able to evaluate and choose the right Information what they need. in the view of the social importance of education, there is a necessary to prudent for the introduction of a new media and a technology. However, computer technology, in the each par has been discharging an importance of its role preview of new paradigm as an education. This research is (or a trying to find a solution and understanding of educational effects an accordance with an introduction of new m computer in the design collaborative education.

Larson-Miller 법을 이용한 보일러튜브의 크립 잔존수명에 관한 연구

정진오,김봉수,김갑중 順天大學校 1999 論文集 Vol.18 No.1

The boiler components are operated at high temperature, and their materials are subject to the time dependent creep deformation. The materials eventually reach the fracture stage due to the creep damage, and thus the designer should pay attention to the creep damage, and thus the designer should pay attention to the creep lifetime to prevent the catastrophic fracture of those components. In this study, test specimens were prepared from the primary superheater in Yousu power plant which have been used for 11 years, and the creep tests were performed to measure the remaining lifetime. To predict the remaining lifetime of used materials, an equation was proposed by using the Larson-Miller parameter which can estimate the lifetime of unused materials. The primary superheater was turned out to be risky, and the remaining lifetime was predicted to be about 2 years. The fractography captured by the scanning electron microscope showed that the fracture was transgranular with dimples for all the specimens.