• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.1-9
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• 2015

In this paper, the RC column-based joint connection part carry out loading test by reinforced hollow or extended Base Plate in order to confirm that RC joint punching shear reinforcement effect of applying the Base Plate. Base Plate thickness, extension length, size, and type as the variable, Base Plate suitable for the stress distribution and shape and dimensions confirmed through experiment and then reinforcing effect was analyzed. Experimentally, vertical load transmitted to the Base Plate from column to foundation is effective to stress distribution and then, type of hollow reinforcement more efficient than a closed. Through experiment, improve performance and ductility due to reinforcement and relative to the thickness of the existing foundation reduced even showed better performance than the existing. The behavior of the reinforced specimens be able to induce from brittle to ductile. Experiment on loading to destroy performed the pattern of cracks, destruction aspect before and after reinforcement.

• Journal of Ocean Engineering and Technology
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• v.17 no.4
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• pp.43-51
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• 2003

The resistance mechanism of anchor changes according to the types of anchor. Friction anchors are classified into tension and compression types. In this study, the characteristics and mechanism of pullout are analysed, and the design method of anchor and computer program for design are developed through compression test results of anchor body grout. The characteristics of compression anchor, compared with tension anchor, are summarized mainly as follows: (1) The effect of progressive failure of compression anchor body are much smaller than those of tension anchor during pullout of anchor: (2) The skin friction resistance is increased by Possion effect of grout (anchor body) during pullout of compression anchor.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.893-896
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• 2002

네트워크 발달로 컴퓨터 시스템에 대한 접근이 용이해 지면서 호기심 또는 악의로 시스템을 침입 및 파괴하려는 다양한 형태의 침입 행위가 날로 증가하고 있다. 이러한 침입에 대비하여 대상 시스템에 대한 비 인가된 행위를 탐지 및 구별하고 이에 대응하는 기능을 가진 침입 탐지 시스템(IDS: Intrusion Detection System)에 대한 연구가 폭 넓게 진행되어 왔으며 다양한 형태의 IDS 들이 컴퓨터 및 네트워크 시스템에 적용되고 있다. 그러나 일반적인 IDS 는 단일 시스템에 대한 침입을 탐지하고 방어하는 것에 그 목적이 있으므로, 하나의 단위 네트워크 시스템을 효과적으로 보호하기 위해서는 단일 시스템에 대한 침입정보를 신속하게 상호 공유할 필요가 있다. 따라서 개별 Host 나 Network 장비에 분산되어 동작하는 다중의 IDS 에 대해서 통합 관리를 수행하는 통합 침입 관리시스템이 요구되어진다. 본 논문에서 제안하는 시스템은 각 IDS 들이 침입을 탐지하는 순간 이에 대한 정보를 수집하여 다른 IDS 들에게 침입에 대한 정보를 신속하게 전달하고, 정보의 종류와 수행 기능에 따른 요구사항을 프로토콜에 적절하게 반영 할 수 있는 시스템을 제안한다.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1994.03a
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• pp.12-23
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• 1994

터널의 방수형식은 배수형(Wet System)과 방수형(Dry System)으로 대별된다. 배수형은 터널의 아치부와 측벽부에만 방수막을 설치하고 이의 배면과 바닥으로부터 유입되는 지하수를 배수공을 통하여 배수처리하는 방식이며 경제성과 시공성이 우수하여 대부분의 도로 터널 및 지하철 등에 적용되어 왔다. 방수형은 터널의 주변장 전체를 방수시공하여 터널내로 유입되는 지하수를 완전히 차단하는 방법으로서, 이러한 방수형 터널은 경제성과 시공성은 불리하나, 지하수위 저하에 따른 압밀침하나 생태계 파괴 방지, 터널의 장기적 환경보전 및 운영유지비 감소 등의 이유로 최근 상당수의 도심지 지하철 터널에 계획되어 시공중에 있다. (중략)

• Journal of Welding and Joining
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• v.17 no.2
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• pp.36-43
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• 1999

The effect of microstructure on the fracture toughness of multi pass weld metal has been investigated. The micromechanisms of fracture process are identified by in-situ scanning electron microscopy(SEM) fracture observation using single edge notched specimen. The notches of the in-situ fracture specimens were carefully located such that the ends of the notches were in the as-deposited top bead and the reheated weld metal respectively. The observation of in-situ fracture process for as-deposited top bead indicated that as strains are applied, microcracks are formed at the interfaces between soft proeutectoid ferrite and acicular ferrite under relatively low stress intensity factor. Then, the microcracks propagate easily along the proeutectoid ferrite phase, leading to final fracture. These findings suggest that proeutectoid ferrite plays an important role in reducing the toughness of the weld metal. On the other hand, reheated regions showed that the microcrack initiated at the notch tip grows along the localized shear bands under relatively high stress intensity factor, confirming that reheated area showing momogeneous and fine microstructure would be beneficial to the fracture resistance of weld metal.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.159-167
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• 2017

A precast concrete deck system is considered an effective alternative in terms of its rapid construction and quality assurance than cast-in-place concrete deck. In precast concrete deck system, structural performance and serviceability are mostly determined by the connection methods between the precast decks. This research proposes more improved precast deck system with asymmetric ribbed connection details improving the disadvantage of previous precast deck system such as difficulties in assembling precast decks. And in this precast deck system, a separate form is not required at the site because partition wall of the precast decks serves as a form when placing non-shrinkage mortar in the connection part of the precast decks. Therefore, rapid construction is possible. Flexural performance is verified through load tests considering main parameter such as rib length in the precast deck connection. From the test results, it can be inferred that the development of the rebar and prevention of adhesion failure in the partition wall of the precast deck system are important factors in securing the flexural performance. Although the structural performance of the precast deck system with asymmetric connection details is gradually reduced as the rib length in the precast deck connection increases, the proposed precast deck system shows sufficient flexural performance and can be applied to the connection part of precast decks effectively.

• Journal of Korean Society of Transportation
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• v.21 no.1
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• pp.115-125
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• 2003

The concrete median barriers are the most popular safety appurtenance that can be installed on narrow medians and are effective in keeping uncontrolled vehicles from crossing into opposing lanes of traffic. It is necessary to install and maintain median barriers because it is very difficult to reserve enough room required for medians in KOREA. Also, concrete median barriers are accepted as the actual alternatives for median barriers, mostly because they require almost no maintenance even after serious collisions. Typical concrete median barriers are 810mm high and have 596mm high glare screens on top of them. However we have experienced a number of "climb" and "roll-over" accidents of heavy vehicles and most of all, there have been some serious accidents caused by the part of broken glare screens. So the improvement study of concrete median barriers started. Prior to this study, a new type of concrete median barrier was suggested which is 1,270mm high and has no glare screens on top of it. So it was required to compare the properties of various types of concrete median barriers including the new type to find the optimal type of concrete median barrier. In this study, we have evaluated the characteristics of four types of concrete median barriers (New Jersey type, F type, constant slope type, and wall type). We have performed many computer simulations for the evaluation of the crashworthiness of them, and through the simulations we have tried to find a proper type of concrete median barrier. Through the computer simulations, we evaluated the structural stability and safety of the four types of concrete median barriers. We confirmed the structural stability and safety of them But in regard to the probability of "roll-over" of heavy vehicles, the higher concrete median barriers showed better performances than the lower. As the result of this study a new type of concrete median barrier was recommended.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.529-537
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• 2021

Membrane-type hull and cargo holds have been designed and built for large ship. However, there is a growing interest in applying the same technology to small and medium-sized Liquefied natural gas(LNG) carriers to meet the recent increase in demand for LNG as an ecofriendly fuel and for expanding LNG bunkering infrastructure. The purpose of this study is to apply the IMO Type-B tank to small and medium-sized LNG carriers and verify the safety and suitability of the design. Fatigue crack propagation analysis was performed to install a partial second drip tray installed at the lower part of the LNG cargo tank by calculating the amount of leaked gas in the support structure supporting the cargo tank. First, a program for fatigue crack propagation analysis was developed, in which Paris' law and British Standard 7910 (BS 79110) were applied based on the International Code for the Construction of Equipment and Ships Carrying Liquefied Gases in Bulk, an international standard for LNG carriers. In addition, a surface crack propagation analysis was performed. Next, a methodology for assuming the initial through-crack size was developed to determine the size of the partial second barrier. The analysis was performed for 15 days, which is a possible return time after cracks are detected. Finally, the safety and suitability of the IMO Type-B for LNG cargo tanks required by international regulations were verified. For the accurate analysis of fatigue crack propagation, it is necessary to develop and verify the analysis procedure based on direct analysis and international regulations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.23-34
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• 2013

In this study, a safe, economic, and rapid construction method of underground roadway using PSC girder is developed to reduce traffic congestion and maximize space usage in urban area. For an efficient application of the method, a rigid joint connection is proposed and tested. For the testing, cantilever specimens were used to verify its capacity. The parameters for this study were cross beam length and joint connection type. The results of the test showed that the proposed connection system has superior performances. Despite having differences of cross beam length and joint connection type, the stable flexural behavior was shown in all of the tested specimens. Also, the behaviors of PSC girders and upper slabs connected by the proposed method showed superior performance. Moreover, the improvement of structure performance according to the increase of length of cross beams has been verified.

• Sijohaknonchong
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• v.21
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• pp.5-22
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• 2004

If Sijo poetry is referred to a text which is composed of sentences. its textuality can be explored in terms of 1) the figurative words used in each line. 2) the logical sequence between lines. 3) the syntactic composition of each line. With the ancient Sijo poem. 1) it is composed of logical sentences as a result of extremely restraining from using figurative words that could prevent the reader from grasping the logical sequence within the work; 2) there is a clear cohesion between lines that can make each work perfectly coherent; 3) each line has a balanced syntactic structure, so the entire structure of a Sijo poem is '6 phrases in lines'. With the modem Sijo peom. 1) it abounds in figurative words, which prevent the work from having a logical sequence, and sometimes even from having three lines; 2) there is a loose cohesion between lines which can't make each work coherent; 3) it sometimes destroys the syntactic structure, '6 phrases in 3 lines', unique to traditional Sijo poetry. I think that this trend of modern Sijo poetry can cause haphazard the existence of modern Sijo poetry.