• Title/Summary/Keyword: 중심축하중

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Experimental Evaluation of Fire Behavior of High-Strength CFT Column with Constant Axial Load (일정축력하에 고온을 받는 고강도 콘크리트 충전강관 기둥의 구조적 거동에 관한 연구)

  • Chung, Kyung Soo;Choi, In Rak;Kim, Do Hwan;Kim, Jin Ho
    • Journal of Korean Society of Steel Construction
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    • v.25 no.1
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    • pp.71-80
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    • 2013
  • Fire-resistant (FR) test data for a square concrete-filled steel tube (CFT) columns consisting of high-strength steel (fy>650MPa) and high strength concrete (fck>100MPa) under axial loads are insufficient. The FR behavior of square high-strength CFT members was investigated experimentally for two specimens having ${\Box}-400{\times}400{\times}15{\times}3,000mm$ with two axial load cases (5,000kN and 2,500kN). The results show that the FR performance of the high-strength CFT was rapidly decreased at earlier time (much earlier at high axial load) than expected due to high strength concrete spalling and cracks. In addition, a fiber element analysis (FEA) model was proposed and used to simulate the fiber behaviour of the columns. For steel and concrete, the mechanical and thermal properties recommended in EN 1994-1-2 are adopted. Test results were compared to those of numerical analyses considering a combination of temperature and axial compression. The numerical model can reasonably predict the time-axial deformation relationship.

Experimental Study on the Compressive Strength of yLRC Composite Columns (yLRC 합성기둥의 압축강도에 관한 실험 연구)

  • Kim, Hyung Geun;Kim, Myeong Han;Cho, Nam Gyu;Kim, Sang Seup;Kim, Sang Dae
    • Journal of Korean Society of Steel Construction
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    • v.21 no.5
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    • pp.545-552
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    • 2009
  • An experimental study was performed on the yLRC composite column. Its external surface was manufactured with y-shape steel sheets and L-shape steel angles, and concrete was poured inside in the field. This composite column has improved the section capacity due to the composite action of steel and concrete, and provides good efficiency in reducing the terms of construction works because of its abridged formworks. The stub column specimens (three small and three large specimens) were tested through concentrical axial loading, and the effect of the width-to-thickness ratio of the steel angle on the column axial strength was examined. The axial strength and behavior of the composite columns were analyzed, and a formula for predicting the axial load capacity was proposed.

자동차 ALC에 대응하는 Job Shop의 동기화 생산시스템에 관한 연구

  • 권보식;김경섭
    • Proceedings of the Korea Society for Simulation Conference
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    • 1997.04a
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    • pp.100-100
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    • 1997
  • 본 연구에서는 우리 자동차산업이 직면한 총체적인 위기상황을 극복하기 위한 방 안으로, 자동차 생산방식의 변혁, 인적자원관리의 혁신을 통한 생산성 제고, 독자 기술개발 능력의 조기확보, 효율적인 부품조달체제의 형성 등 산업전반에 걸친 혁신으로, 내적인 경 쟁력을 축적함과 동시에, 지역주의화의 진전에 따른 수출 여건의 악화를 극복하기 위해 선 진권 및 개발도상국으로의 현지화 노력이 적극적으로 추진되지 않으면 안될, 중대한 시점에 와 있다고 진단하면서, 본 연구의 목적을, 생산현장을 중심으로 한 내적 경쟁력 확보로 정 의하고, 그 실현방안으로서, 급변하는 시장환경에 적극 대응하기 위한 생산방식의 도입과, 이를 지원하는 생산정보시스템의 구축 모델을 제시하고자 한다. 첫 번째는, 변화가 급격한 시장환경에 적극 대응하는 생산방식의 도입으로, 철저한 낭비 배제 사상 - 생산현장의 낭비 소요를 배제(개선)하는 것만이 아니라 배제하고 바로 체계를 바꾸어 (개혁) 원래의 상태로 되돌아가지 않도록 하는 -을 기본으로, 정보, 관리, 생산, 제품, 물류 등에 관련된 손실 비 용을 감축시킴으로서 원가를 낮추고, 고객이 요구하는 다양하고, 좋은 품질이 제품을 신속 히 공급할 수 있는 체계를 갖추는 것이다. 이러한 낭비 배제 사상은 생산현장에서 필요한 것을, 필요한 때에, 필요한 만큼 만들고 운반하며 전달하는 관리 개선 등을 의미하며, 이것 을 적은 인원 및 설비로 최대한 빨리 (리드 타임의 단축), 계획대로 수행하도록 하는 것이 동기화 생산방식이다. 따라서, 본 연구에서는 자동차 생산공정 중 주 조립공정의 ALC(Assembly Line Control)에 대응하여, 선행 공정으로서 부품을 공급하는 Job Shop의 동기화 생산방식을 실제 적용한 사례 중심으로 전개하고자 한다. 두 번째의 접근방식은, 동 기화 생산방식에 컴퓨터 통합생산 (CIM, Computer Integrated Manufacturing)의 기술을 구 현, 적용하는 것이다. 즉, 동기화 생산 시스템 (SPS, Syncronized Production Sytem)을 구 축하는 것인데, 이것은 최신의 컴퓨터 기술을 생산현장에 적용함으로써 새로운 생산방식의 혁신에 버금가는 기술혁신이라 할 수 있을 것이다. 따라서, 이러한 접근은 컴퓨터 및 통신 기술의 눈부신 발전을 기초로 가능해진 것인데, 제조업에서의 심각한 고비용, 저효율 문제 를 해결하기 위해 필수적으로 도입해야만 하는 실정이다. 또한 소비자의 다양한 요구로 인 하여 제품의 종류와 사양면에서 심한 변동을 보이는 시장 수요에, 신속한 정보처리로 대응 하는데도 크게 기여하고 있다. 이에 본 연구에서는, 자동차 Job Shop의 동기화 생산방식을 지원하는 동기화 생산시스템의 구축 모델을 제시하고자 한다.

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Evaluation of Axial Behavior of Strengthened Columns according to Different Peripheral Closed Hoops in Jacket Section (확대단면에서 폐쇄형 외부 띠철근 배근 방법에 따른 보강기둥의 중심축하중 거동 평가)

  • Hwang, Yong-Ha;Yang, Keun-Hyeok;Sim, Jae-Il;Choi, Yong-Soo
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.35 no.7
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    • pp.139-146
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    • 2019
  • This study examined the effect of various arrangement methods for forming peripheral closed hoops in the jacket section on the axial behavior of section enlargement strengthening columns. Four types of peripheral closed hoops arranged in the jacket section were prepared as follows: 1) Closed connection of prefabricated bar units (column P); 2) V-clip installation across the overlapped legs of channel-type bars (column V); 3) Use of glass fiber mesh for an alternative of steel bars (column F); and 4) combination of prefabricated bar units and glass fiber mesh (column PF). The V-clip is designed to form the closed hoops in the jacket section using the overlapped channel-type bars, preventing the opening of the channel bar legs. The glass fiber mesh is to examine the feasibility to apply for closed hoops in the jacket section as an alternative for steel bars, considering the easy construction. In the jacket section of all the strengthened columns, V-ties were arranged for supplementary ties, avoiding the interruption of the existing column. The axial stiffness and strength of the strengthened columns were insignificantly affected by the arrangement methods of closed hoops in the jacket section. The axial ductility ratio of the strengthened columns P, V, and PF was enhanced more than twice of that measured in the non-seismic existing column. However, the column F exhibited a lower ductility than the other strengthened columns because of the fracture of the mesh at the ultimate strength of the column. The V-clip approach was favorable to enhance the ductility of the strengthened column, preventing the opening of the legs of channel-type bars.

The Panel Analysis of Youth Employment Expectation (청년층의 취업 눈높이 패널 분석)

  • Kim, Hye Jin;Oh, Ho Young
    • Journal of Labour Economics
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    • v.39 no.3
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    • pp.1-32
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    • 2016
  • The purpose of this article is to examine the change of employment expectation using the wave 7-11 (2010-2014) of Korea Education and Employment Panel(KEEP). The three main variables are the reservation wage, which has been studied by labor economists for a long time, the convenient working environment factor, the desired job factor. Last two of which are extracted from the 15 survey questions about employment expectation using the factor analysis. Our estimates suggest that male have a higher reservation wage than female while female have a higher level of expectation overall. Women attach more importance to working environment especially. Also, university students have a higher reservation wage and set a higher value on the desired job than employees and job seekers.

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Social network analysis of keyword community network in IoT patent data (키워드 커뮤니티 네트워크의 소셜 네트워크 분석을 이용한 사물 인터넷 특허 분석)

  • Kim, Do Hyun;Kim, Hyon Hee;Kim, Donggeon;Jo, Jinnam
    • The Korean Journal of Applied Statistics
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    • v.29 no.4
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    • pp.719-728
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    • 2016
  • In this paper, we analyzed IoT patent data using the social network analysis of keyword community network in patents related to Internet of Things technology. To identify the difference of IoT patent trends between Korea and USA, 100 Korea patents and 100 USA patents were collected, respectively. First, we first extracted important keywords from IoT patent abstracts using the TF-IDF weight and their correlation and then constructed the keyword network based on the selected keywords. Second, we constructed a keyword community network based on the keyword community and performed social network analysis. Our experimental results showed while Korea patents focus on the core technologies of IoT (such as security, semiconductors and image process areas), USA patents focus on the applications of IoT (such as the smart home, interactive media and telecommunications).

Analysis of Post-tensioned Slab Bridge by Means of Specially Orthotropic Laminates Theory (특별직교이방성 복합적층판 이론을 응용한 포스트텐션된 슬래브 교량의 해석)

  • Han, Bong Koo;Kim, Yun Pyo
    • Journal of Korean Society of Steel Construction
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    • v.14 no.1
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    • pp.105-111
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    • 2002
  • A post-tensioned slab bridge is analyzed by the specially orthotropic laminates theory. Both the geometry and the material of the cross section of the slab are considered symmetrical with respect to the mid-surface so that the bending extension coupling stiffness, $B_{ij}=0$, and $D_{16}=D_{26}=0$. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of rule of mixture. This bridge with simple support is under uniformly distributed vertical and axial loads. In this paper, the finite difference method and the beam theory are used for analysis. The result of beam analysis is modified to obtain the solution of the plate analysis. The result of this paper can be used for post-tensioned slab bridge analysis by the engineers with undergraduate study in near future.

Effects of Cover Thickness on Confining Transverse Reinforcement of RC Bridge Columns (철근콘크리트 교각 심부구속 횡방향철근량 산정식의 피복두께 영향)

  • Son, Hyeok-Soo;Lee, Jae-Hoon;Suh, Suk-Koo;Oh, Myung-Seok;Yoon, Cheol-Kyun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.81-84
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    • 2008
  • The equation, specified in current bridge design code, for calculating the confining transverse reinforcement amount of RC bridge columns has been made to provide additional load-carrying strength for concentrically loaded columns equal to or slightly greater than the strength lost when the cover concrete spalls off. However, this equation does not directly consider ductile behavior, which is an important factor for the seismic behavior of bridge columns. Consequently, if the section area is relatively small or if the section area ratio becomes excessively large due to the concrete cover thickness increased for durability, too large an amount of transverse reinforcement, which could deteriorate the constructability and economy of piers, will be required. This study intends to analyze what effects the concrete cover thickness has on the equation for determining the confining transverse reinforcement amount.

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Influence of Anchorage of T-Plate on the Seismic Performance of RC Columns Strengthened with Unbounded Wire Rope Units (와이어로프 기반 비부착 보강된 RC 기둥의 내진거동에 대한 T형 강판 정착의 영향)

  • Sim, Jae-Il;Yang, Keun-Hyeok
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.1
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    • pp.133-140
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    • 2010
  • Five strengthened columns and an unstrengthened column were tested under constant axial load and cyclic lateral loads to examine the seismic performance of the unbounded strengthening procedure using wire ropes and T-plates. Main variables considered were the presence of mortar cover for strengthening steel element and anchorage method of T-plate. Test results clearly showed that T-plates having a proper anchorage contribute to transfer of applied moment as well as enhancement of ductility of reinforced concrete columns. However, T-plate not anchored fully into a column base can seldom transfer the externally applied moment, though it highly improves the ductility of column. The presence of mortar cover for strengthening steel elements is significantly effective in enhancing the initial stiffness and flexural capacity of the strengthened columns, but has an adversely effect on enhancing the ductility. The ultimate moment strength predicted from the extended section laminae method in better agreement with test results compared with predictions obtained using stress black specified in ACI 318-05.

An Analysis of Industrial Security Curriculums in Colleges (국내 산업보안학과의 교과과정 분석: 교육 영역과 과목별 분류를 중심으로)

  • Jung, Jinhyo;Lee, Chang-Moo
    • The Journal of Society for e-Business Studies
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    • v.24 no.2
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    • pp.29-53
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    • 2019
  • Of all the 55 security departments in colleges, the information security departments occupies the majority of 45. Though existing security focused too much on information security, a new research stream on industrial security from a perspective of convergence has emerged. Since the first department of industrial security was established in a college in 2014, the total of four departments have been established until 2018. A new discipline to solve the existing problems and an opportunity to cultivate industrial security professionals have been greatly appreciated; however, the definition of industrial security is not yet specific, and more discussions on education categories and subjects with a focus on the characteristics of convergence are needed. The demand for industrial security professionals has gradually increasing and the departments of industrial security have been established to meet the demand. It is necessary, in this circumstance, to find out how the industrial security departments are teaching students. To this end, the purpose of this article is to deliver an overview of the educational curriculums of the four industrial security departments. This study analyzed 127 subjects in the curriculums, categorized educational areas, and employed Social Network Analysis to understand the relationships between subjects of each departments.