• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.41-49
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• 2006

Through the 1982 Urahawa-ohi and the 1995 Kobe earthquakes, a number of bridge columns were observed to develop a flexural-shear failure due to the bond slip as a consequence of premature termination of the column longitudinal reinforcement. Because the seismic behavior of RC bridge piers is largely dependent on the performance of the plastic hinge legion of RC bridge piers, it is desirable that the seismic capacity of RC bridge pier is to evaluate as a curvature ductility. The provision for the lap splice of longitudinal steel was not specified in KHBDS(Korea Highway Bridge Design Specification) before the implementation of 1992 seismic design code, but the lap splice of not more than 50%, longitudinal reinforcement was newly allowed in the 2005 version of the KHBDS. The objective of this research is to investigate the distribution and ductility of the curvature of RC bridge column with the lap splice of longitudinal reinforcement in the plastic hinge legion. Six (6) specimens were made in 600 mm diameter with an aspect ratio of 2.5 or 3.5. These piers were cyclically subjected to the quasi-static loads with the uniform axial load of $P=0.1f_{ck}A_g$. According to the slip failure of longitudinal steels of the lap spliced specimen by cyclic loads, the curvatures of the lower and upper parts of the lap spliced region were bigger and smaller than the corresponding paris of the specimen without a lap splice, respectively. Therefore, the damage of the lap spliced test column was concentrated almost on the lower part of the lap spliced region, that appeared io be failed in flexure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.67-76
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• 2011

The use of glass-fiber-reinforced polymer (GFRP) bars in reinforced concrete (RC) structures has emerged as an alternative to traditional RC due to the corrosion of steel in aggressive environments. Although the number of analytical and experimental studies on RC beams with GFRP reinforcement has increased in recent decades, it is still lower than the number of such studies related to steel RC structures. This paper presents the experimental moment deflection relations of GFRP reinforced beam which are spliced. Test variables were different reinforcement ratio and cover thickness of GFRP rebars. Seven concrete beams reinforced with steel GFRP re-Bars were tested. All the specimens had a span of 4000mm, provided with 12.7mm nominal diameter steel and GFRP rebars. All test specimens were tested under 2-point loads so that the spliced region be subject to constant moment. The experimental results show that the ultimate moment capacity of beam increasing of the reinforcement ratio. Failure mode of these specimens was sensitively vary according to the reinforcement ratio. The change of beam effective depth, which was caused by cover thickness variation, controlled the maximum strength and deflection because of cover spalling in tension face.

• Korean Journal of Heritage: History & Science
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• v.38
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• pp.329-358
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• 2005

The Three storied Stone pagoda in Gameunsa Temple site, one of the early staged stone pagodas, has been known as a standard for Silla stone pagodas. A stone pagoda is not only a stone art work and but also a stone structure. Most studies and investigation of the stone pagoda has done mainly based on style and chronological research according to an art historical view. However, there is not an attempt to research the stone pagoda as a stone architecture. Most Korean experts at the stone pagoda has art history in their background. Engineers who can understand the structure of the stone pagoda are very limited. More architectural and engineering approach is need to research not only art historial understanding but also safety as a structure. We can find many technical know-how from our ancestors who made stone pagodas. 1. To reduce any deformation such as relaxation and sinking of BuJae which is caused by a heavy load, the BuJae (consist of a foundation stone and lower stereobates) should be enlarged. 2. A special construction method for connection between Myonsuk and Tangjoo was invented. This unique method is not used any longer after the Three storied Stone pagoda in Gameunsa Temple site. 3. The upper BuJae and the lower BuJae are missed each other by making a difference of Okgaesuk and Okgaebatchim in size. It is done for a distribution of perpendicular load and a prevention for relaxation of BuJae. 4. The center of gravity in the BuJae is located to the center of the stone pagoda by trimming the upper surface of the Okgaebatchim into a convex shape. The man who made stone pagodas had excellent knowledge on the engineering and techniques to understand the structure of the stone pagodas. We can confirm it as follows: the enlarged BuJae, dislocated connection between upper Bujae and lower BuJae, and moving the center of gravity close to the center of the stone pagoda.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.531-542
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• 2022

As buildings become taller, the strength of structural materials must increase and the amount of rebar reinforcement also increases while the application of an appropriate rebar splice method in the construction process become one of the essential factors. In this research, the current status of quality check for rebar coupler is identified by an expert questionnaire and an appropriate quality check method is proposed through a quality test on specimens similar to actual on-site construction. In the test results, it was revealed that, among the quality check methods for rebar coupler joints, the coupler tightening method and face to face degree of between upper and lower rebar did not affect the strength the specimen. Therefore, it is considered to be an appropriate way to check the coupler quality check to check whether the threads are completely assembled during on-site construction through manufacture the number of threads of rebar and coupler with a margin beyond the calculated thread number.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.691-697
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• 2008

Coating the high tension bolted frictional joint has been generally allowed for anti-corrosion purpose. However in case of painting on paying surface of the high tension bolt, the influence on a slip strength of the joint depending on precision of painting has remained controversial. The study thus was intended to identify the slip behavior on high tension bolted frictional joint when applying ceramic painting, which has been currently developed. A slip test was conducted on a high tension bolted frictional joint specimen on which ceramic painting has been applied and a slip load and slip coefficient were measured. Based on result, the safety and usability of ceramic painting-applied high tension bolted frictional joint was evaluated. As a result, a difference to some extent by specimen in terms of load-displacement when a slip occurred was observed but an average slip coefficient appeared to have exceeded 0.4, which is the design frictional coefficient set forth in the specification. To secure the safety and usability of ceramic painting-applied high tension bolted frictional joint, it's necessary to establish the standard for painting as well as to revise the relevant specification.

• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.271-280
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• 2010

This study was programmed to fabricate a beam-to-column connection that is limited to a steel-welded moment connection with full-scale members, using SN steel. A cyclic seismic test was conducted of the nine specimens that were fabricated by choosing the test variable for the weld access hole geometry, connection design method, and RBS. From the test results, failure modes, the moment-drift behavior, and the strain distribution were provided. From the specimen material properties, the beam's nominal plastic flexural capacity and classified qualified connection as a special moment flame were calculated. By analyzing the skeleton part and the baushinger part, a range of strength-raising effects, and deformation ratios were provided, with which the seismic performance of the specimens were evaluated. The test results showed that the specimens eliminated their weld access holes that demonstrated higher seismic performance than the specimens' existing weld access holes, and that the WUF-W connection that was reinforced by the supplemental fillet weld around the shear tap that was fastened by five bolts demonstrated superior seismic performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7244-7249
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• 2015

In this study, in order to asses the structural performance of trapezoidal PSC girder using a socket joint system and it is possible to calculate the optimized cross-section of the web element tests were carried out for each specimens. we conducted a socket joint performance test, web bending and shear performance tests and all tests were performed at 4 point loading method. The initial crack load of socket joint specimen was significantly lower than the reference specimen but post peak behavior was no significant differences. And the length of the loop joint of the reinforcing bars had no significant effect on the maximum load. As a web shear tests, to obtain a maximum load of the specimen has a prestressing rod reinforced at tension side. As a web flexural tests, to obtain higher diagonal cracking load in specimen of reinforced using prestressing rod than reference specimen.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.1-9
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• 2022

Purpose: In this study, we used hydrophilic waterstop used in geosynthetics vertical barrier system to evaluate the performance of impermeability under sealing conditions. Method: ASTM D5887 and ASTM D6766 were applied to determine the capability of the connection during the geosynthetics vertical barrier system. Hydrophilic waterstop was saturated in each solution and the weight, thickness, and volume changes were analyzed over elapsed time. Hydrophilic waterstop was installed at the geosynthetics vertical barrier system connection to evaluate the permeability characteristics. Results: As the expansion reaction time of hydrophilic waterstop increased relatively under saline conditions, the decrease in permeability also showed a smaller decrease in fresh water. Furthermore, the method of engagement of the geosynthetics vertical barrier system showed somewhat better performance of the impermeability due to the large pressure resistance caused by the roll joint type than interlock type. Conclusion: In urban pollutants, which can estimate the outflow of pollutants such as oil storage facilities and industrial complexes, proactive response technologies that can prevent the contaminant diffusion can significantly reduce the damage.

• Review of KIISC
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• v.14 no.1
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• pp.46-55
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• 2004

21세기에는 정보기술의 혁명적 발전과 함께 전쟁양상이 파격적으로 변화될 것으로 예측되며, 전력체계의 특성이 근본적으로 변화됨과 더불어 전쟁 패러다임이 획기적으로 변하고 있다. 특히, 정보과학기술을 이용한 정밀감시, 통제, 타격 복합체계의 구축이 군사력 발전의 근간이 되고 있으며, 앞으로 디지털, 인터넷, 생명공학, 나노기술 등을 복합적으로 활용하는 것이 전력체계의 중심 축이 될 것이다. 특히 전쟁 수행 방식 및 수단의 변혁과 군사패러다임의 보편적 변화추세에 능동적으로 대비하기 위하여 유선과 무선 그리고 근거리 무선 사이에 이음매 없는 통신망이 실현됨으로써 누구든지 어디서나 네트워크로부터 자신이 필요한 정보를 얻을 수 있는 유비쿼터스 컴퓨팅을 민간분야에 활용하여 스마트 흠과 물류에 적용한 사례를 살펴보았다. 유비쿼터스 컴퓨팅과 네트워크 기술은 21세기 변화될 형태의 전쟁을 수행하기 위해 국방 분야 적용이 필수적이며, 이를 통해 전술적인 감지$.$추적 능력의 차대 및 고도화된 전술 정보의 실시간 교환$.$공유, 전술부대의 커뮤니티 파워증대 효과를 가져 올 수 있다. 따라서 유비쿼터스 국방(u-Defense) 시대로 가기 위해 개발하여 적용 가능한 핵심 분야인 내장형 모바일 ad-hoc 네트워크 프로토콜, 무선 센서 네트워크, RFID(Radio Frequency Identification)를 활용한 유비쿼터스 군수지원 등을 제시하였다. 이러한 유비쿼터스 국방을 위하여 우선 비용 측면과 민간분야에 비해 훨씬 강화된 정보 보호 및 무기체계간 상호인증 환경을 고려해야 하며, 국방 정보화에 전력증강차원의 과감한 투자가 요구된다. 또한, 저 비용 고효율의 군사력을 구축해야할 것이며, 첨단 정보체계 건설을 주도할 수 있는 정보 인력을 양성하여, 장기적으로 종합적인 발전계획을 수립하고 국방 정보 체계를 효율적으로 구축하면 군 전력향상에 획기적으로 기여할 수 있을 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.298-307
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• 2006

TEE Forming process for HDPE(High Density PolyEthylen) pipe has been analyzed by using rigid plastic finite element code, DEFORM-3D. TEE of HDPE pipes is necessary to connect main pipe with branch pipe and change the flow direction of hot water. A HDPE pipe is used as a insulator to maintain the temperature of hot water A butt welding process through TEE forming for a HDPE pipe is a updated process improving the strength of welding part compared to conventional extrusion welding process. The Experiment of Hot and Cold Forming have been performed. The design parameters such as a initial hole shape have been obtained through rigid-plastic finite element analysis, which is applied to the actual manufacturing process.