고 에너지 밀링 공정으로 제조된 지르콘 나노분말의 소결특성에 관한 연구

이주성,강종봉,Lee, Ju Seong,Kang, Jong Bong 한국재료학회 2016 한국재료학회지 Vol.26 No.2

In this study, 5 um sized $ZrSiO_4$ was ground to 1.9 um, 0.3 um, and 0.1 um sized powders by wet high energy milling process, and the sintering characteristics were observed. Pure $ZrSiO_4$ itself can-not be sintered to these levels of theoretical density, but it was possible to sinter $ZrSiO_4$ powder of nano-scale size of, -0.1 um to the theoretical density and to lower the sintering temperature for full density. Also, the decomposition of $ZrSiO_4$ with a size in the micron range resulted in the formation of monoclinic $ZrO_2$; however, in the nano sized range, the decomposition resulted in the tetragonal phase of $ZrO_2$. So, it was possible to improve the sintering characteristics of nano-sized $ZrSiO_4$ powders.

고유변형률 기반 등가하중법을 이용한 판의 용접변형 해석

이주성,Lee, Joo-Sung 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.2

IIn this study, used is the equivalent loading method based on the inherent strain to predict the welding deformation of panel members. Equivalent loads are computed from the inherent strain distribution around weld line, and then applied for the linear finite element analysis. Thermal deformation of panel members can be, of course, carried out through the rigorous thermal elasto-plastic analysis procedure but it is not practical in applying to predicting the welding deformation of large structures such as blocks found in a ship structure from view of computing time. The present equivalent load approach has been applied to flat plate model to verify the present approach, and to several curved plate models having the curvature in the welding direction to investigate the effect of the longitudinal curvature upon the weld-induced deformation. The results are compared with those by thermal elasto-plastic analysis. As far as the present results are concerned, it can be said that the present approach shows good agreement with the results by welding experiment and the rigorous thermal elasto-plastic analysis. The present approach has been also applied to predict the welding deformation of panel block as for application illustration to practical model.

FPSO Moon Pool 구조에서 발생되는 용접 잔류응력에 관한 연구

이주성,한성우,이상훈,김상일,Lee, Joo-Sung,Han, Sung-Woo,Lee, Sang-Hoon,Kim, Sang-Il 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.3

Welding process generates distortion and residual stress in the weldment due to rapid heating and cooling. Welding distortion and residual stress in the welded structure result in many troubles such as dimensional inaccuracies in assembling and safety problem during service. The accurate prediction of welding residual stress is thus very important to improve the quality of weldment and find the way to reduce itself. This paper presents the simulation of welding-induced residual stress analysis to examine the cause of cracking in the SUS-overlay welding specimen at FPSO Moon Pool structure.

최종강도에 기초한 리프팅 러그의 설계

이주성,Lee, Joo-Sung 한국전산구조공학회 2016 한국전산구조공학회논문집 Vol.29 No.1

러그는 선박 및 해양구조물의 블록을 이동하거나 반전에 많이 사용되는 부품이다. 선박이나 해양구조물의 제작기술이 발전함에 따라 블록이 점차 대형화되고 있어, 생산성 향상을 위해 블록을 보다 효율적으로 다루는 기술에 대한 중요성이 대두되고 있다. 러그 구조의 안전하고 경제적인 설계를 위하여 비선형 구조해석 결과를 토대로 도출한 최종강도를 기준으로 한 보다 합리적인 설계과정이 필요하다. 본 연구는 조선소에서 자주 사용하는 T형 러그의 최적 구조설계를 다루고 있다. 본 연구에서의 T형 러그에 대한 최적 구조설계 결과는 충분한 구조적 안전성이 보장될 것으로 판단되고, 러그 용량별 최적 구조설계 결과의 중량 감소량에 어떤 규칙성을 발견할 수 없었는데, 이는, 현재의 설계과정에 대한 검토가 필요한 것으로 생각된다. 여기에서 제시한 비선형 구조해석에 기초한 최적 구조설계 과정은 향후 보다 다양한 경우의 러그 설계에 적용될 수 있을 것이다. Lifting lugs are frequently used to transport and to turn over blocks of ship and offshore structures in a shipyard. As the shipbuilding technology has been developed, blocks has become bigger and bigger, and block management technology takes a more important role in shipbuilding to enhance the productivity. For the sake of economy as well as safety in design of lug structure, needed is a more rational design procedure based on the ultimate strength derived through the rigorous non-linear structural analysis considering both the material and geometric non-linearity. This study is aimed at deriving the optimum design of T type lug structure which is frequently used in a shipyard. The optimum thickness of lug's main body is to be determined based on the results of non-linear strength analysis. As far as the present results for T type lugs having various capacity are concerned, it can be said that the present optimum design result can guarantee both safety and economy. From the fact that any regular trend cannot be found in weight reduction to the capacity of lugs, it seems to be necessary to review the current design procedure of lug structure. The present design procedure can be extensively used in design of various types of lug structures used in shipyard.

오리피스를 이용한 유압 액추에이터의 충격치 제어특성에 관한 실험적 연구

이주성,이계복,Lee, Ju-Seong,Lee, Gye-Bok 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.11

Control of shock may be important in the hydraulic system and necessary to avoid failure and to improve the efficiency of operation. This study addresses the design and use of an orifice to provide the desired control of the hydraulic actuator system. The experimental apparatus is an idealization of an automobile shift system. Control is accomplished by installing three different types of orifices at appropriate locations in the system. Experimental results show that the orifice can be used to obtain the control of shock and control level depends on the orifice size, orifice type, operating pressure and flow rate.

초등학생의 자기주도학습을 위한 LMS 활용방안

이주성,전석주,Lee, Ju-Sung,Chun, Seok-Ju 한국정보교육학회 2019 정보교육학회논문지 Vol.23 No.2

최근에는 ICT기술을 학습에 도입한 학습관리시스템이 학생들의 자기주도 학습능력을 향상시키는데 도움을 주고 있다. 학습관리시스템을 활용한 자기주도 학습은 학습자원의 효율적인 활용과 의사소통 확산의 장점을 중심으로 학습자의 학습참여를 촉진시키고 흥미를 유발시켜준다. 본 연구에서는 학습관리시스템을 활용한 자기주도 학습이 초등학생의 학습동기와 학업성취취도에 미치는 영향에 대해 알아보았다. 학습자들은 제안한 학습관리시스템의 알고리즘을 통해 자신의 수준에 맞는 문제를 학습하므로 효과적인 학업 성취를 달성할 수 있을 것이다. 연구를 위하여 S초등학교 21명에 대한 제안한 학습관리시스템을 활용한 수업을 8주 동안 매주 2차시씩 총 16차 시를 진행하였다. 연구결과로 실험에 참여한 학습자의 학습지향성과 흥미 영역에 유의미한 향상을 보였다. Recently, a learning management system incorporating ICT technology into learning has helped students improve self-directed learning skills. Self-directed learning using LMS promotes and stimulates learners' participation in learning, focusing on the advantages of efficient use of learning resources and the spread of communication. In this study, we study the impact of self-directed learning using the learning management system on elementary school students' motivation and academic performance. We expect learners will be able to achieve effective academic achievement by learning problems that fit their level through the algorithms of the proposed learning management system. For this study, a total of 16 classes were conducted for eight weeks using the proposed learning management system for 21 elementary school students. Research has shown significant improvement in the learning orientation and interest areas of the learners who participated in the experiment.

지방대학 특성화 사업의 공학교육에 주는 효과

이주성,Lee Joo-Sung 한국공학교육학회 2004 공학교육연구 Vol.7 No.1

지방대학 교육의 활성화를 위해 교육인적자원부는 1997년에 지방대학 특성화사업을 위한 지원 대상 학부의 하나로 울산대학교 수송시스템공학부를 지정하였다. 동 사업을 시행한 결과, 교육 프로그램의 개발, 교수법의 향상 등 여러 분야에서 많은 성과가 있었다. 이 논문에서는 특성화사업 시행의 성과로써 교육측면에서의 성과를 소개하고자 하는데, 특성화 전공 교육프로그램의 특징과 성과 그리고 공학교육에 미친 효과에 대해 기술하였다. This paper concerns with the effects of the specialized projected for the local universities on engineering education which was planned and conducted in 1998 by the Ministry Education and Human Resources Development in Korea. Some characteristics of the specialized education program conducted by School of Transportation Systems Engineering at the University of Ulsan are described with effects on engineering education

熱處理溫度에 따른 Soft Carbon과 Hard Carbon 結晶子 크기와 物理的 特性

이주성,Ju Seong Lee 대한화학회 1969 대한화학회지 Vol.13 No.4

On the soft carbon made from petroleum coke, it was found that the graphitization began at around 2,000$^{\circ}C and crystallite diameters were almost saturated at 2,400$^{\circ}C., and that the molecular planes were difficult to arrange into an ideal graphite lattice in spite of the saturation of crystallinity by heat treatment temperature. On the hard carbon made from cross-linked thermosetting plastics, phenol-formaldehyde filler and phenol-benzaldehyde binder, it was very difficult to rotate the molecular planes into a regular directional arrangement and into a consecutive order corresponding to the large graphite crystals. In addition to the above mentioned crystallinity, it was also determined in relation to electric conductivity, resistivity, hardness and apparent density of carbons.

연구개발 분야의 IT 서비스 전략: e-R&D를 중심으로

이주성,장인수,Lee, Joosung,Jang, Insu 서비스사이언스학회 2012 서비스연구 Vol.2 No.2

e-R&D 활동이란 가상공간에서 인터넷 등의 네트워크나 컴퓨터 소프트웨어를 이용하여 R&D 활동을 전개해 나가는 것을 의미한다. 최근 빠른 속도의 기술변화와 다양해진 고객의 수요로 인해 기업은 생산성 향상의 문제에 직면하면서 e-R&D 필요성을 절감하고 있다. 본 논문에서는 e-R&D의 동향, 적용 사례 및 e-R&D 활성화를 위한 전략적 시사점을 살펴보고, 이를 통하여 미래기업의 e-R&D 모델과 디지털산업 육성 및 기술경쟁력 확보를 위한 e-R&D 정책을 제시하였다. e-R&D means conducting research and development with network or computer software in cyber space. Given the rapid technology paradigm shift and diversified customer needs, companies face the problem of new product and service innovation. This paper introduces the strategic view for e-R&D status, case examples, and e-R&D service. We state e-R&D adoption stages for strengthening the industry competitiveness and IT service utilization.

알칼리 축전지의 활물질에 관한 연구. 카드뮴 전극에 관하여

이주성,주충렬,박수길,Ju Seong Lee,Choong Yeoul Joo,Park, Su Gil 대한화학회 1981 대한화학회지 Vol.25 No.5

Ni-Cd 전지 중 카드뮴 전극을 수산화 칼륨용액 중에서 각종 조건의 변화에 따른 cyclic voltammetry를 행하여 카드뮴전극의 전기화학적 거동을 검토하였으며 voltammogram에 나타나는 peak전위 근처의 각 전위에서 정전위 전해를 하여 충, 방전상태의 전기화학적 거동을 X-선 회절선도의 해석 결과와 결부시켜 전극반응 메카니즘을 종합적으로 검토하였다. 수산화카드뮴 마이너스 전극의 음극분극 곡선에는 두 개의 peak가 나타난다. 마이너스극의 수산화카드뮴은 제 1 peak 전위에서 카드뮴 금속으로 환원되고 제 2 peak 전위에 도달하면 매우 활성이 큰 금속 상태로 되며 (002)면이 (101)면보다 성장이 매우 크다. 또한 제 2 peak 전위의 카드뮴은 산소와의 선택적인 반응이 급속히 일어남을 알 수 있었다. 본 실험의 결과 카드뮴극과 산소와의 반응은 화학적 반응인 $2Cd + O_2 + 2H_2O\;{\longrightarrow}\;2Cd(OH)_2$으로 진행된다고 추정하였다. The electrochemical behavior of cadmium electrode for the nickel-cadmium battery system has been studied by cyclic voltammetry, controlled potential electrolysis and X-ray diffraction method. Cathodic polarization curve for cadmium hydroxide electrode prepared by electrochemical pretreatment of metallic cadmium showed two peaks. It has been found that cadmium hydroxide was reduced to cadmium metal at the first peak potential, whereas very activated metal of cadmium which was strongly oriented (002) rather than (101) was formed at the second peak potential. It was also found that the cadmium formed at the second peak potential reacted rapidly with oxygen. Therefore, it could be presumed that the cadmium recombination reaction with the oxygen was chemical, and could be represented as $2Cd + O_2 + 2H_2O\;{\longrightarrow}\;2Cd(OH)_2$.