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.

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.

유체기구를 이용한 유압계통의 충격치제어에 수탄되는 반응지연에 관한 연구

이주성,이계복,Lee, Joo-Seong,Lee, Kye-Bock 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.11

The response time represents how fast a system responds to a given disturbance at the system boundary. Flow restricting devices for controlling transients can result in a decrease in the peakm pressure, but may change response time. Response lag in a hydraulic system leads to inefficient working cycle and operator discomfort. The experiments were conducted in order to get information on the parameters which exert appreciable influence on the response time. The experimental apparatu including a hydraulic actuator, orifice and a hydraulic pump was an idealization of a bucket hydraulic shifting system. Experimental results show that the response time depends on operating pressure and flow rate. The effects of orifice type and size on the response time are quantified.

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.

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.

목포항 해안가 경관조명 - 가작 : 중부전기전자㈜ -

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

신뢰성 해석에 기초한 선체 중앙단면 설계

이주성,Lee, Joo-Sung 한국전산구조공학회 2011 한국전산구조공학회논문집 Vol.24 No.5

본 논문에서는 종굽힘 최종강도에 대한 선체 중앙단면 구조의 구조신뢰성 해석과 이에 기초한 설계를 다루었다. 길이 100m이상인 8척의 산적화물운반선과 7척의 탱커를 본 연구의 대상 모델로 선정하였다. 본 대상 선박 모델들에 대한 구조 신뢰성 해석결과를 토대로 목표신뢰성 지수를 도출하였다. 두 선종의 중앙단면 설계시 목표신뢰성 지수를 만족할 수 있는 설계공식을 제안하였고, 이를 본 연구대상 선박 모델들의 재설계에 적용하여 그 타당성을 보였다. 이러한 결과로부터 구조 신뢰성 해석에 기초하여 개발한 설계공식에 의한 설계결과는 보다 균일한 수준의 안전성을 제공할 수 있었다. This study is concerned with the reliability analysis and its based design of midship section against the ultimate bending strength. Eight bulk carriers and seven oil tankers over 100m length are chosen for the present study. Target reliability indices for the two ship types have been derived based on the results reliability analysis of the present ship models. Reliability-based structural design codes are proposed for use in design of midship section of bulk carriers and oil tankers. The design codes proposed in this study have been successfully applied to re-design of midship section of the present ship types. It has been found that the proposed codes can provide more uniform structural design results.

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.

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.