• 한국공간구조학회논문집
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• 제10권3호
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• pp.81-90
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• 2010

대공간구조물은 일반 라멘구조와는 다른 동적특성을 가지고 있으며, 이런 동적특성에 관해 많은 연구가 수행되고 있다. 그러나 대부분의 연구는 특정 형태의 대공간구조물에 대해 수행되었으며, 내진설계를 위해 직접적으로 이용 가능한 연구결과는 매우 제한적이다. 본 연구에서는 대공간구조물의 기본적인 동적특성을 내재한 트러스-아치구조물을 대상으로 양단의 기둥의 길이가 다른 경우에 트러스-아치구조물의 지진응답변화를 분석하고자 한다. 양단 기둥 길이의 차이에 따라, 가속도 응답이 수평방향에 비해 수직방향에서 더 많은 영향을 받는다. 따라서 상부구조물을 지지하는 하부구조물의 강성이 다른 경우에 대공간구조물의 내진설계에 있어서 수직방향 응답에 대한 고려가 더욱 많이 요구된다.

• 한국산학기술학회논문지
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• 제18권6호
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• pp.209-218
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• 2017

본 연구는 대학생의 사회적 지지(가족의 사회적 지지, 친구의 사회적 지지), 심리적 행동특성(자기존중감, 대인의존행동특성, 통제신념) 및 스트레스가 우울수준에 미치는 영향을 알아보기 위해 실시하였다. 조사대상은 D광역시의 남녀 대학생 546명으로 하였으며, 연구방법은 2015년 10월에 자기기입식 설문조사에 의하였다. 연구결과, 조사대상자의 우울수준은 가족의 사회적 지지, 친구의 사회적 지지, 자기존중감 및 통제신념이 높은 군보다 낮은 군에서 유의하게 높은 반면, 대인의존행동 특성과 스트레스가 낮은 군보다 높은 군에서 유의하게 높았다. 또한, 조사대상자의 우울수준은 가족의 사회적 지지, 친구의 사회적 지지, 자기존중감 및 통제신념과는 유의한 음의 상관관계를 보인 반면, 대인의존행동특성 및 스트레스와는 유의한 양의 상관관계를 보였다. 공분산 구조분석 결과, 스트레스원의 인지는 사회적 지지의 인지나 심리적 행동특성보다 우울수준에 더 큰 영향을 미쳤으며, 스트레스원의 인지가 높을수록, 사회적 지지의 인지나 심리적 행동특성이 낮을수록 우울수준을 증가시키는 효과가 있는 것으로 나타났다. 위와 같은 결과는 대학생들의 우울수준은 사회적 지지와 심리적 행동특성이 낮고, 스트레스가 높을 경우 증가한다는 것을 시사하고 있으며, 특히 다른 요인들보다 스트레스에 의해 더 큰 영향을 받고 있음을 알 수 있다. 따라서 대학생들의 우울수준을 감소시키기 위해서는 학생들이 경험하는 주요 스트레스원이 무엇인지 파악하고 스트레스원을 감소시키기 위한 노력이 필요하다고 생각된다.

• 한국안전학회지
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• 제23권4호
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• pp.67-71
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• 2008

Formwork is a temporary structure that supports its weight and that of fresh concrete as well as construction live loads. Slab formwork consists of sheathing, stringer, hanger and shore. In construction site, pipe supports are usually used as shores which are consisted of the slab formwork. In this study, compressive strength of 80 pipe supports was measured by knife edge test and plate test. Buckling load of pipe supports was analyzed by structural analysis program(MlDAS). Theoretical buckling load with/without initial deformation was got by theoretical analysis. According to these results, buckling load which was analyzed by structural analysis program(MlDAS) was larger than compressive strength of knife edge test and plate test. Theoretical buckling load without initial deformation was larger than compressive strength of knife edge test and plate test. But Theoretical buckling load with initial deformation was lower than compressive strength of knife edge test and plate test. Initial deformation equation for test method according to the pipe support length was suggested. Therefore, the present study results will be used to design the slab formwork safely.

• 한국기계가공학회지
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• 제20권7호
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• pp.1-7
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• 2021

Restrictions on the emissions of nitrogen oxides, sulfur oxides, carbon dioxide, and particulate matter from marine engines are being tightened. Each of these emissions requires different reduction technologies, which are costly and require many pieces of equipment to meet the requirements. Liquefied natural gas (LNG) fuel has a great advantage in reducing harmful emissions emitted from ships. Therefore, the marine engine application of LNG fuel is significantly increasing in new ship buildings. Accordingly, this study analyzed the internal support structure, insulation type, and fuel supply piping system of a 35 m3 International Maritime Organization C type pressurized storage tank of an LNG-fueled ship. Analysis of the heat transfer characteristics revealed that A304L stainless steel has a lower heat flux than A553 nickel steel, but the effect is not significant. The heat flux of pearlite insulation is much lower than that of vacuum insulation. Moreover, the analysis results of the constraint method of the support ring showed no significant difference. A553 steel containing 9% nickel has a higher strength and lower coefficient of thermal expansion than A304L, making it a suitable material for cryogenic containers.

• 한국안전학회지
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• 제21권3호
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• pp.101-106
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• 2006

Formwork is a temporary structure that supports its weight and that of freshly placed concrete as well as construction live loads. In constructions site, pipe supports are usually used as shores which are consisted of the slab formwork. The strength of a pipe support is decreasing as it is frequently being used at the construction site. Among the accidents and failures that occur during concrete construction, there are many formwork failures which usually happen at the time concrete is being placed. The objective of this study is to find out the strength change of used pipe support and unused pipe supports according to aging. In this study, 2857 pipe supports were prepared. Among these pipe supports, 2337 pipe supports were lent to the construction companies free of charge. 520 pipe supports were kept on the outside. Compressive strength was measured by knife edge test and plate test at each 3 month. Test results show that the strength of unused pipe supports as well as used pipe supports was decreasing according to age, use frequency and load carrier, and the strength of used pipe supports was lower than the strength of unused pipe supports at the same age. So, the strength of used pipe supports from 191 days to present day was not satisfied the specification of KS F 8001. In this study, the strength of pipe support according to age, use frequency and load carrier was predicted using SPSS 12.0. It was known that the strength of pipe support using for 5 years was reduced to 42.8%. According to these results, it shows that attention has to be paid to formwork design using used pipe supports. Therefore, the present study results will be able to provide a finn base to prevent formwork collapses.

• 건설안전기술
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• 통권38호
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• pp.79-87
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• 2006

Formwork is a temporary structure that supports its weight and that of freshly placed concrete as well as construction live loads. In constructions site, pipe supports are usually used as shores which are consisted of the stab formwork. The strength of a pipe support is decreasing as it is frequently being used at the construction site. Among the accidents and failures that occur during concrete construction, there are many formwork failures which usually happen at the time concrete is being placed. The objective of this study is to find out the strength change of used pipe support and unused pipe supports according to aging. In this study, 2857 pipe supports were prepared. Among these pipe supports, 2337 pipe supports were lent to the construction companies free of charge. 520 pipe supports were kept on the outside. Compressive strength was measured by knife edge test and plate test at each 3 month. Test results show that the strength of unused pipe supports as well as used pipe supports was decreasing according to age, use frequency and load carrier, and the strength of used pipe supports was lower than the strength of unused pipe supports at the same age. So, the strength of used pipe supports from 191 days to present day was not satisfied the specification of KSF 8001. In this study, the strength of pipe support according to age, use frequency and load carrier was predicted using SPSS 12.0. It was known that the strength of pipe support using for 5 years was reduced to 42.8%. According to these results, it shows that attention has to be paid to formwork design using used pipe supports. Therefore, the present study results will be able to provide a firm base to prevent formwork collapses.

• 한국경영과학회지
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• 제31권2호
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• pp.69-85
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• 2006

Transductive Support Vector Machine(TSVM) is one of semi-supervised learning algorithms which exploit the domain structure of the whole data by considering labeled and unlabeled data together. Although it was proposed several years ago, there has been no efficient algorithm which can handle problems with more than hundreds of training examples. In this paper, we propose an efficient branch-and-bound algorithm which can solve large-scale TSVM problems with thousands of training examples. The proposed algorithm uses two bounding techniques: min-cut bound and reduced SVM bound. The min-cut bound is derived from a capacitated graph whose cuts represent a lower bound to the optimal objective function value of the dual problem. The reduced SVM bound is obtained by constructing the SVM problem with only labeled data. Experimental results show that the accuracy rate of TSVM can be significantly improved by learning from the optimal solution of TSVM, rather than an approximated solution.

• 건축역사연구
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• 제17권3호
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• pp.7-21
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• 2008

Three-story Stone pagodas in Gameunsa Temple site, one of the early staged stone pagodas, has been known as a standard of Silla stone pagodas. A stone pagoda is not only a stone art work and but also a stone architecture. In understanding the stone pagoda it is very important to be approached with technological side in which we can investigate the stone pagoda deeply and as well as to have been approached with art historical view. Also it needs that we should see the stone pagoda in view of structural safety. We can get many high technique from our ancestors who made Gameunsajiseoktap. 1. To reduce any deformation such as relaxation and sinking of members which is caused by a heavy load the members such as the lower tier of the base is made up of the foundation stone and side stone in each, comprising one stone. 2. A special construction method for connection between wall stone and column stone in stereobates was invented. It is to make column stone projected partially and wall stone be caved in that two members should be jointed well. This unique method is not used any longer after the three-story Stone pagodas in Gameunsa Temple Site. 3. In each side upper and lower member are not engaged as the size of roof stones and support stones of roof stones are different. It can be done for a distribution of perpendicular load and a prevention for relaxation of members. 4. It makes sure that to make upper ends of support stones 10mm lower was to be avoid upper loads to it judging from survey in disassemblying east pagoda. It proves that ancestors who made this stone pagoda had a technique to understand the structural matters to make small members as big as possible, not to engage in joint, to avoid in ends of members from upper load.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.4995-5004
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• 2011

본 연구는 노인들의 신체적 기능, 사회적 지지, 가족지지 및 우울수준을 실태를 알아보고 이들 상호간의 관련성을 파악하며, 공분산구조분석을 통하여 신체적 기능, 사회적지지 및 가족지지가 우울수준에 미치는 영향을 파악하고자 하였다. 조사대상은 대전광역시에 거주하고 있는 노인 995명이었으며, 조사는 2010년 4월 1일부터 6월 30일까지의 기간 동안에 표준화된 무기명식 면접조사용 설문지를 사용하여 면접조사 하였다. 연구결과 사회적지지, 가족지지 및 신체적 기능(ADL, IADL)이 높을수록 우울수준은 낮은 경향을 보였다. 또한 공분산 구조분석 결과, 사회적 지지는 가족지지나 신체적 기능보다 우울수준에 더 큰 영향을 미쳤으며, 사회적지지, 가족지지 및 신체적 기능이 높을수록 우울수준을 감소시키는 효과가 있는 것으로 나타났다.

• 대한기계학회논문집A
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• 제40권1호
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• pp.97-102
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• 2016

회전 기계에서 회전에 따른 진동은 성능 저하 및 고장의 직접적 원인이 되어, 진동을 예측하고 저감 방안을 수립하는 것이 매우 중요하지만, 회전 기계의 조립이나 설치 과정에서 발생하는 불평형의 변화나 지지 구조물의 진동 모드는 예측이 어려워 그 영향을 사전에 평가하기 어렵다. 본 논문에서는 자기베어링에 의해 지지된 터보 압축기의 전달함수를 시스템 식별과정을 통해 구하고 이를 활용하여 압축기의 불평형 응답을 예측한다. 식별된 전달함수는 회전체의 진동 모드와 지지 구조물의 진동 모드를 함께 포함하고 있어, 불평형 응답에 대한 지지 구조물의 영향을 실질적으로 평가할 수 있다. 저속 운전에 의해 불평형을 추정하고 정격 속도까지의 불평형 응답을 시험 결과와 비교하여 예측의 적절성과 문제점을 파악하였다.