• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.15-22
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• 2003

In the conventional load transfer analysis for a steel pipe drilled shaft, it was assumed that the concrete's strain is the same as the measured steel's strain and the elastic modulus of the steel and the concrete calculated by the formular as prescribed by specification is used in the calculation of pile axial load. But, the pile axial load calculation by conventional method differed to some extent from the actual pile load. So, the behavior of a steel pipe drilled shaft could not be analyzed exactly. Thus, the necessity to measure the strain for each pile component was proposed. In this study, a new approach for load transfer measurement of large diameter drilled shafts was suggested ; the strain of each pile component(i. e., steel and concrete) was measured by DRS(Deformable Rod Sensor), the elastic modulus was determined by the uniaxial compression test for concrete specimens made at test site and a value of elastic modulus was evaluated as average tangential modulus corresponding to the stress level of the (0.2-0.6)$f_{ck}$. Field application was confirmed by the results of load transfer measurement tests for 3 drilled shafts. The errors for calculated pile head load were -11 ∼16% and 3.4% separately.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.4
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• pp.395-404
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• 2000

A damage detection and assessment algorithm is developed by measuring accelerations at limited locations of a structure under forced vibrations. The developed algorithm applies a time-domain system identification (SI) method that identifies a structure by solving a linearly constrained nonlinear optimization problem for optimal structural parameters. An equation error of the dynamic equilibrium of motion is minimized to estimate optimal parameters. An adaptive parameter grouping scheme is applied to localize damaged members with sparse measured accelerations. Damage is assessed in a statistical manner by applying a time-windowing technique to the measured time history of acceleration. Displacements and velocities at the measured degrees of freedom (DOF) are computed by integrating the measured accelerations. The displacements at the unmeasured DOF are estimated as additional unknowns to the unknown structural parameters, and the corresponding velocities and accelerations we computed by a numerical differentiation. A numerical simulation study with a truss structure is carried out to examine the efficiency of the algorithm. A data perturbation scheme is applied to determine the thresholds lot damage indices and to compute the damage possibility of each member.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.371-382
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• 2008

The objective of this study is to develop the laboratory testing method for evaluating the loading capacity of lattice girder used for support in tunnel structure. 3-point flexible strength test and 4-point flexible strength test were performed on three types of lattice girder, such as $LG-50{\times}20{\times}30$, $LG-70{\times}20{\times}30$, and $LG-95{\times}22{\times}32$, mainly used in Korea. Two types of loading position for each flexible strength test were used to analyze the behavior of load-deformation. The loading distribution in the lattice girder was analyzed by means of strains measured by strain gauges attached on chords and diagonal bars. In 3-point flexible strength test, the difference of the average of maximum flexible strength according to loading position had the range from 10% to 33%. In 4-point flexible strength test, the average of maximum flexible strength according to loading position was almost no difference. The difference between the average of maximum flexible strengths obtained from 3-point and 4-point flexible strength tests was from 13.56 to 31.55%. The load applied on the lattice girder was concentrated to the main chord in 3-point flexible strength test. The load applied on the lattice girder in 4-point flexible strength test was distributed to three chords and diagonal bars.

• Journal of the Korean Society for information Management
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• v.19 no.3
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• pp.91-110
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• 2002

Recently, to overcome the limit of keyword based retrieval system, the study based structured document has been studied. But it is hard for structured retrieval system to adapt a real service, in this paper, we propose a method of retrieval mechanism for the fulltext of XML documents. We explain DTD of XML based report, extracting navigation information and planing to adapt the retrieval system for article retrieval. Using the fulttext retrieval scheme, suggested system can be an alternative plan of professional structured based retrieval system.

• Journal of Welding and Joining
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• v.10 no.4
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• pp.33-38
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• 1992

우리나라의 용접재료는 산업구조 및 그 발전 속도와 용접재료 제조업체의 기술 및 연구개발 수 준과 더불어 발전하여 왔다. 용접이 본격적으로 이용되기 시작하여 약 40년이 경과되고 용접재료 제조업체가 현대적인 제조설비를 도입하여 체계적으로 용접재료를 생산하고 개발하기 시작하여 30년이 경과되었다. 용접재료가 양 및 질에 있어서 비약적인 발전으로 이룩할 수 있는 계기가 마련된 것은 제1차 경제개발5개년 계획의 수립과 추진으로 다양한 종류의 수요창출과 높은 수 준의 품질이 요구되면서 부터다. 1970년대에 조선공업등 강구조물을 주류로 하는 양적 수요 증 가의 기반이 조성되고 화학 프랜트, 원자력 발전등의 건설이 주축이 되어 관련 주변 기술이 발 전하므로서 용접재료의 품질보증 SYSTEM확보등 기술 발전의 획기적인 전기를 맞이하게 되 었다. 용접재료용 고품질의 원재료 및 일부 부재료가 국산화되고 용접재료 제조업체의 연구소 설립과 기술 및 연구개발 인력 확보, 그리고 대학 및 관공 연구소에서의 용접재료 관련 연구의 활성화에 힘입어 용접재료 기술은 국내 자체 기술로서 정착하게 되었다. 1941년 용접봉의 FLUX를 수제로 피복한 피복아크 용접봉(일미나이트계와 고산화철계의 혼합계통) 년산 17톤을 생산하기 시작하여 현재 년 12만톤을 생산하는 장족의 발전을 하게 되었다. 특히 1985년부터 1991년까지 용접재료의 고도성장은 종례가 없었던 기간이지만 1992년부터는 수요가 진정되고 경제의 불황이 예고되면서 저성장 추세는 상당기간 지속될 전망이다.

• Fire Science and Engineering
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• v.24 no.6
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• pp.112-119
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• 2010

In this research paper, the analysis, and improvement, of conditions of fire investigation related to products were derived. The results of the research showed that the main entity that plays the role of coordinator on the scene of fire investigation is unclear, systematic devices to protect the rights and interests of fire victims are inadequate, there are limitations in deriving the cause of fire due to the lack of fire appraisal organizations in fire departments, and the product companies are passive in their initial actions. As for improvement measures, it was found that the adoption of the system in which fire departments can play the role of mediator on the scene of fire investigation, the establishment and operation of fire appraisal organizations and research institutes in fire departments, and the establishment of network between fire departments and product companies are needed.

• Proceedings of the Safety Management and Science Conference
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• 2012.04a
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• pp.447-460
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• 2012

현재 위험물 운송 사고는 점차 감소하는 추세이지만 위험물 운송 사고는 특성상 한번의 사고로 인해 주변의 인명 및 환경에 막대한 피해를 입히게 된다. 이러한 위험물 운송 사고의 대응을 위해 각 기관들이 있지만 기관별로 메뉴얼 및 방침이 다르게 적용되어 있어 운송 사고에 대한 정확한 정보전달이 미비한 실정이다. 결과적으로 운송사고에 대한 정보가 부족하여 잘못된 대응계획으로 사고처리가 늦어질 수도 있다. 사고시 적절한 대응을 위해서는 위험물질의 종류와 양, 사고위치, 주변상황 등에 대한 정보가 전달되어야 사고대응에 대한 장비, 인력 편성 등 정확한 대응이 이루어질 수 있다. 현재 국내의 정부 유관기관별로 위험물질 사고대응메뉴얼을 구축하여 제공하고 있으나, 운송 및 수송 사고에 대한 사고대응메뉴얼의 부재로 2차적인 피해가 발생되고 있다. 따라서 본 논문에서는 위험물질의 표준화하고 이에 대한 사고대응매뉴얼을 개발하여 위험물 운송 사고시 사고에 대한 정보를 유관기관에게 신속 정확하게 전파하여 통합적인 초동대응이 이루어질 수 있도록 하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.145-148
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• 2008

Recently, most of the international design code for concrete structures are trying to develope performance-based design specification with the limit state concept. To accomplish this object, it is necessary to define required performance and to measure the performance level of structure. The reliability index is one of the most attractive indexes to express the level of performance. In this paper, prestressed concrete beam is designed following member resistance factor and material resistance factor format and the reliability indexes are obtained and compared for different sets of resistance factors. Compatible sets of safety factors could be calibrated for given level of target reliability index applying the similar method presented in this paper.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.237-238
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• 2019

현시대에 자율주행 기술이 자동차를 단순 이동수단에서 이동성을 확보한 생활공간으로 자동차의 근본적인 개념을 변화시켜 새로운 산업 패러다임적 가치뿐 아니라, 사회 경제적 변혁을 예고하고 있다. 이미 전 세계적인 기업들은 자율주행 시스템을 구축하고 개발하여 실제 생활에서 활용도 하고 있다. 그럼에도 불구하고 상용화를 하기 위해선 아직 법/제도의 부재, 안정성, 가격 등 여러부분에서 문제점들을 극복해야한다. 본 과제인 라인트레이서와 GPS를 활용한 자율주행시스템이 목적지를 지정하면 자율적으로 길이나 도로를 따라 이동하면서 장애물을 피해가게 만들어 안정성을 확보하고 이동하는 시간에 개인 여가 시간이나 생산적인 활동을 할수 있게 만들어 삶의 질 개선에 기여할 것이다. 이러한 기술들을 적극 활용하여 목적지를 설정하면 자율주행 하는 자동차로 설정하였고, 장애물 감지와 현재 방향 감지를 추가하였다. 장애물 감지와 방향 그리고 위치를 수신받기 위해 5개의 센서를 활용하였고 한번에 구동을 시키기 위해 센서 쉴드를 활용하여 기능을 확장 시켰다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.573-579
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• 2016

Studies on the deformation behavior of materials subjected to impact loads have been carried out in various fields of engineering and industry. The deformation and fracture of members for these machines/structures are known to correspond to the intermediate strain-rate region. Therefore, for the structural design, it is necessary to consider the dynamic deformation behavior in these intermediate strain-rate ranges. However, there have been few reports with useful data about the deformation and fracture behavior at intermediate strain-rate ranges. Because the intermediate strain-rate region is located between quasi-static and high strain-rate regions, it is difficult to obtain the intermediate strain-rate using conventional reasonable test equipment. To solve this problem, in this study, the measurement reliability of the constructed drop-bar impact tensile test apparatus was established and the dynamic behavior at the intermediate strain-rate range of carbon steels was evaluated by utilizing the apparatus.