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.

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.

장력법을 적용한 필릿용접변형 제어에 관한 연구

이주성,김철호,Lee, Joo-Sung,Kim, Cheul-Ho 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.4

As it has been well appreciated, the weld-induced deformation control is one of the most important issues from view point of efficiency in ship production. The weld-induced deformation is more serious in the case of thin plate block than in the case of relatively thick plate block, since, for example, heat affect zone of thin plates is wider than that of thick plates for the same heat input. Among weld-induced deformation, buckling deformation due to shrinkage and residual stress in weld line direction is one of the most serious deformation type. This paper is concerned with the controling the buckling deformation of thin plate fillet weld by applying the tensioning method. Weld experiments have been carried out for specimens with varying the magnitude and direction of tension load. The results are graphically represented to show the effect of tensioning method upon reducing the weld-induced deformation. From the present findings, its has been seen that tensioning method is one of the useful ways to control the weld-induced deformation of fillet weld of thin plates.

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.

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.

On the Structural Analysis Using the Isogeometry Analysis Approach

이주성,장경식,노명일,Lee, Joo-Sung,Chang, Kyoung-Sik,Roh, Myoung-Il Computational Structural Engineering Institute of 2011 한국전산구조공학회논문집 Vol.24 No.1

본 논문에서는 NURBS의 기저함수를 이용하는 등기하 해석을 선형 탄성 문제에 적용하였다. 등기하 해석의 목적은 기하학적 모델링 (CAD)와 수치적 해석 (CAE)를 통합하는 것인데, 이는 계산 망으로써 NURBS에 의한 기하학적 모델링 결과를 직접 이용해서 이룰 수 있다. NURBS 곡면은 조정점과 노트 벡터들을 이용하여 정확한 기하학적 형상을 표현할 수 있으며, 또한 요소의 정밀화 과정이 상대적으로 용이하다는 장점이 있다. 본 연구를 통해 개발된 컴퓨터 코드의 정당성을 보이기 위해 비교적 단순한 형태의 두 가지 구조모델에 적용하였다 ; 1) 균일 내압을 받는 실린더, 2) 균일 인장력이 작용하는 중앙에 구멍이 있는 정사각형 판. 이 두 모델은 정해가 있는 경우로서 절점을 추가하는 h-정밀화와 기저함수의 차수를 증가하는 p-정밀화에 의한 등기하 해석법을 적용한 근사해의 수렴성을 분석하였다. In the present work, isogeometric analysis in linear elasticity problem is conducted using the basis functions from NURBS. The objectives of isogeometric analysis introduced is to integrate both geometric modeling(CAD) and computational analysis(CAE), and this can be accomplished from direct usage of geometric modeling by NURBS as the computational mesh. The merit of the isogeometry analysis is that NURBS surface are able to represent exact geometry from the control points and knot vectors, and also subsequent refinement is relatively simple relatively. In order to verify the computer codes developed in this study, it has been applied to two structural models of which geometry are simple ; 1) circular cylinder subjected to the constant internal pressure loading, 2) square plate with circular hole at center subjected to uniform tension. The exact solutions of these two models are available. Convergence of the approximate solutions by the present code for the isogeometry analysis are investigated by mesh refinement with inserting knots (h-refinement) and by mesh refinement with order elevation of the basis functions (p-refinement).

선상가열 변형예측식 자동 산출을 위한 지식기반 방법의 개발

이주성,Lee, Joo-Sung 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.1

For the last couple of decades many studies have been carried out to find out solutions to improve the effectiveness and productivity of the plate forming process. The practical way for the automation of the plate forming process has not been, however, developed yet. Since the characteristics of heating machines may be different form each other, it is necessary to investigate the thermal deformation characteristics of the heating machine to be used in the automation system. And their characteristics may be updated as new information about thermal deformation by heating is accumulated. In this paper, data base system has been constructed based on the results of experiments and numerical analyses, which will be used in deriving the deformation estimation formula. The computer code which can automatically derive the deformation estimation formula has been also developed. This paper also illustrates how the formula is updated as experimental data are added. From the present findings, it can be said that the automatic deriving procedure may be important in the automated plate forming system since the heating line information to be generated must be directly influenced by the deformation estimation formula.

목포항 해안가 경관조명 - 가작 : 중부전기전자㈜ -

이주성,Lee, Ju-Seong 한국조명전기설비학회 2007 조명.전기설비 Vol.21 No.1

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.

열성형 판 부재의 동적거동에 관련된 재료상수 산출에 관한 연구

이주성,임형균,Lee, Joo-Sung,Lim, Hyung-Kyun 한국전산구조공학회 2016 한국전산구조공학회논문집 Vol.29 No.2

구조물에 충격하중이 작용하면, 그 구조물은 통상적으로 대변형을 동반하는 소성변형과 최종적으로 그에 따른 파단을 경험하게 된다. 본 연구에서는 사고적 극한 상태에 대한 합리적인 설계를 위해 열성형된 판과 냉간성형된 판의 재료상수를 고속인장시험에 대한 수치시현을 통해 정의하였다. 변형율이 중간 속도 이하인 경우에는 변형율 속도의 영향을 무시할 수 있다는 가정과 함께 Cower-Symond 모델과 John-Cook 모델에 포함되는 재료상수들의 유용성을 참고문헌들의 결과와 비교하여 입증하였다. 본 논문은 향후 연구 내용에 대한 언급을 포함하면서 마무리하였다. When impact load is applied to a plate structure, a common phenomenon that occurs in structures is plastic deformation accompanied by a large strain and eventually it will experience a fracture accordingly. In this study, for the rational design against accidental limit state, the plastic material constants of steel plate which is formed by line heating and by cold bending procedure have been defined through the numerical simulation for the high speed tension test. The usefulness of the material constants included in Cowper-Symonds model and Johnson-Cook model with the assumption that strain rate can be neglected when strain rate is less than the intermediate speed is verified through comparing the present numerical results with those in references. This paper ends with describing the future study.