• Explosives and Blasting
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• v.24 no.1
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• pp.57-62
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• 2006

The typical blasting method adopted in Pasir Coal Mine is a surface blasting technique with a single free face. It means that there is only one free face, which is usually the ground surface. This kind of blasting method is easy to use but inevitably causes enormous ground vibrations, which, in turn, can affect the stability of the slopes comprising the various boundaries of the open pit mine. In addition, the method also has the problem of lowering the blast efficiency compared to other methods such as bench blasting methods or ones with more than two free faces. In this respect, a project was launched to develop a new blasting method that is suitable for controling the ground vibration and enhancing the blast efficiency. As a part of the project, authors investigated the current blasting method as well as the overall pit developing process in the mine, and established some important guidelines that should be observed during the whole development process. This paper presents the details of the typical blasting pattern and the pit developing method in the mine, and suggests the guidelines determined from the results of the observations.

• Fire Science and Engineering
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• v.29 no.1
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• pp.19-26
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• 2015

This study covers securing legal systems and institutions regarding the standards for installing fire prevention facilities to prevent fire on wooden architectural heritage. Conflicts among relevant laws were revealed and problems related to fire prevention performance, technical standards, responsibilities, etc. in the process of establishing legal fire prevention equipment and the equipment for self-extinguishing were identified through pondering over current legal systems of fire prevention facilities. To resolve the problems, at least the principle to preserve original shapes of wooden architectural heritage should be secured even though fire prevention facilities are installed and the installation process should be regulated by laws considering features of fire on wooden architectural heritage so that fire prevention performance can be guaranteed. The directions to improve installing system through legalization of design, construction, and audit review institutions and legalization of the technical standards for fire prevention facilities were suggested to guarantee performance when establishing fire prevention facilities for wooden architectural heritage.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.683-692
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• 2012

The girders of cable stayed bridge are subjected to not only the bending moments but also additional compressive axial forces due to the horizontal components of cable forces. Because of these axial forces, the stiffness of girder can be decreased, and this problem should be considered especially for under-construction model rather than the full model. Korean domestic design specification suggests the linear elastic eigen value analysis for the stability problem of cable stayed bridges. However, this method cannot be applied to the under construction model because various geometric nonlinear characteristics cannot be considered. Therefore, in this study, 3 models which are assumed to be constructed by balanced cantilever will be considered experimentally and analytically to analyze the behavior of steel cable stayed bridges.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.3 s.43
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• pp.59-68
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• 2005

The energy-based seismic design method Is more rational in comparison with current seismic design code in that it can directly account for the effects of cumulative damage by earthquake and hysteretic behavior of the structure. However there are research results that don't reach a consensus depending on the ground motion characteristic and structural properties. For that reason in this study the influences of ground motion characteristics and structural properties on energy demands were evaluated using 100 earthquake ground motions recorded in different soil conditions, and the results obtained were compared with those of previous works. Results show that ductility ratios and sue conditions have significant influence on input energy. The results show that the ratio of hysteretic to input energy is considerably influenced by the ductility ratio, damping ratio, and strong motion duration, while the effect of site condition is insignificant.

• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.105-115
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• 2016

This paper describes a restoration of retaining wall, which was collapsed by rainfall. The failure causes was analyzed by field case, and then the countermeasure was suggested. The failure causes confirmed that observance of design and construction criteria was insufficient. It also was the climate condition like a rainfall and inappropriate construction management. The stability analysis for retaining wall, soil improvement and reinforced earth wall was conducted to confirm validity of the countermeasure. The analysis results showed that the suggested construction method satisfied in required safety factors. Therefore, it should be secured the stability of the structure based on the application of appropriate design method and construction management, when structure was constructed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.735-742
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• 2006

In this study, the ultimate shear strength behavior of transversely stiffened curved web panels was investigated through nonlinear finite element analysis. It was found that if the transverse stiffener has a sufficient rigidity, then curved web panels used in practical designs are able to develop the postbuckling strength that is equivalent to that of straight girder web panels having the same dimensional and material properties. The nonlinear analysis results indicate that in order for curved web panels to develop the potential postbuckling strength. The rigidity of the transverse stiffener needs to be increased several times the value obtained from the Guide Specifications (AASHTO, 2003). However, in the case of thick web panels where the shear design is governed by shear yielding, the stiffener rigidity does not have to be increased. From the analysis results, a simple design formula is suggested for the rigidity of transverse stiffener under strength limit state.

• 한국가스학회:학술대회논문집
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• 2003.10a
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• pp.65-72
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• 2003

현행 가스법상 지상식 LNG 저장탱크에 있어서 일정 용량의 저장탱크 주위에는 액상의 가스가 누출된 경우에 그 유출을 방지할 수 있는 방류둑(Dike) 또는 이와 동등 이상의 효과가 있는 시설을 설치하도록 규정하고 있어, 실제로 모든 지상식 LNG 저장탱크에 대해서 별도의 방류둑 설치를 의무화하고 있다. 또한, 예외규정으로 국제기준(international codes and standards)에 의해 설계되는 저장탱크는 심의를 통해 방류둑 기능을 인정할 수 있도록 하고 있다. 외국의 경우 LNG 저장탱크는 일반적으로 자국내 법령보다는 국제기준에 의해 건설됨으로써 1차 탱크로부터 일정거리의 둘레에 방류둑이 필요한 단일방호식 저장탱크 이외에 이중방호식, 완전방호식(full-containment) 및 멤브레인식(membrane) 저장탱크의 경우 외부(콘크리트, 강재)탱크가 방류둑 기능을 가지고 있어 별도의 방류둑이 필요없는 구조로 규정하고 있다. 멤브레인 LNG 저장탱크의 경우 프랑스, 일본 및 한국이 설계기술을 보유하고 있고, 최근 프랑스 및 한국에서 별도의 방류둑 없는 지상식 멤브레인 저장탱크 건설이 추진되고 있으나 양국 모두 자국법의 방류둑 규정에 의해 건설의 장애요소로 작용하고 있다. 따라서 지상식 멤브레인 LNG 저장탱크의 방류둑 기능에 대한 각 국의 법령 및 기준을 조사하고, 방류둑 일체형 저장탱크(완전방호식 및 멤브레인 저장탱크)의 형식별 안전성 평가 자료를 비교 검토함으로써 방류둑 일체형 멤브레인 저장탱크의 국내 도입의 타당성을 검토하고자 하였다. 조사결과 유럽, 미국 및 일본에서는 이중벽 LNG 저장탱크의 경우 콘크리트 외부탱크가 방류둑 기능을 가지는 것으로 규정하고 있으며, 특히 EN 1473과 제정중인 prEN 265002에서는 멤브레인 저장탱크의 경우 내부 멤브레인 탱크 누출시 단열시스템과 함께 외부 콘크리트 탱크가 액밀성 및 기밀성을 동시에 가지는 것으로 별도의 방류둑이 불필요함을 규정하고 있다. 프랑스 및 일본의 방류둑 일체형 LNG 저장탱크에 대한 위험성 평가 결과를 검토한 결과 멤브레인 저장탱크와 완정방호식 저장탱크는 안전성 차원에서 거의 동일한 것으로 나타났다. 따라서 국내에서 개발한 지상식 멤브레인 LNG 저장탱크 설계모델에 대한 안전성 제고 및 안전성 평가 등을 통해 객관적인 안전성 근거가 확보된다면 동 탱크의 경우에도 완전방호식 LNG 저장탱크와 같이 외부콘크리트 저장탱크의 방류둑 기능인정이 가능할 것으로 판단된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.179-193
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• 1994

In the development of engineering designs, decisions are required irrespective of the state of completeness and quality of information, and are formulated under conditions of uncertainty. Furthermore, under conditions of uncertainty the design invokes risks. Thus, in the design of the structures, the currently used deterministic design method does not provide a realistic assessment of the actual safety or the reliability of the structures. It is desirable that decisions required in The process of the design invariably must be made based on the reliability analysis. Properties of soil material are subject to more uncertainty than those of other structural material. In the field of soil mechanics and foundation engineering, it needed to develop reliability-based design methods. In order to simplify the reliability analysis or the reliability-based design process of the structures associated with the active earth pressure, it is necessary to find the variation and the distribution type of the active earth pressure calculated from the basic properties of soils. Monte Carlo simulation is performed to obtain the relationship between the variation of the active earth pressure for cohessionless soils calculated by using Rankine formula and the basic soil properties and the distribution type of the earth pressure. A series of regression equations obtained by utilizing the multi-linear regression analysis is suggested in this paper and the sensitivity of the basic soil properties to the variation of The earth pressure is investigated. The type of distribution of the active earth pressure was found to be the beta distribution in most cases or to be very similar to the beta distribution, if the basic soil variables are normally distributed.

• Journal of Korean Society of Steel Construction
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• v.29 no.6
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• pp.467-477
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• 2017

The live load effect of KL-510 of the current Korean bridge design code is examined by comparing with that of the multiple trucks of which the weights are statistically estimated from measured traffic data as well as with those of the related live load models. The truck weight data measured on the expressway before and after overweight enforcement are used to obtain the truck weights following the same procedures in deciding the live load model of the design codes and the results are compared with the load effect of KL-510. KL-510 yields a very uniform loading effect compared with the multiple truck effects when the weights are estimated from the data which contains some of the heavy trucks over the operational weight limit. KL-510 yields consistent results with the live load of AASHTO LRFD and shows less variation than the past load model DB-24 over the span lengths considered in this study. As a result of this research, the actual truck combinations equivalent to the notional KL-510 load model are constructed and it can be applied to the evaluation of the existing bridge and the calibration of the load factor of the permit vehicle.

• Fire Science and Engineering
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• v.31 no.6
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• pp.47-52
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• 2017

The recent tragic outbreak of fire at the Grenfell Tower in the United Kingdom compels all branches of government to reexamine and reassess the safety measures against fires in high-rise buildings from a broad perspective. Accordingly, this study examined what problems stem from the current evacuation codes by comparative analysis of the high-rise apartment evacuation codes that range over various individual laws before introducing a new evacuation code. The outcome of this study can be utilized as basic data for amending the existing evacuation codes for high-rise buildings. The codes related to high-rise building evacuation include the Building Act, the Housing Act, the Skyscraper Disaster Management Act, and the Fire-Fighting System Act. Some local governments have also drawn up their own codes and put them into practice. Comparative analysis of the major evacuation codes has helped identify a variety of problems, such as different codes being applied to each individual law and ordinance, the use of additional codes other than the provisions of laws and ordinances, and the in effectiveness of evacuation codes. Most of these problems occur when diverse codes are applied to a single building, which means that cooperation among the relevant ministries is urgently needed to improve the related codes in the future.