• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.5
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• pp.412-423
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• 2000

By using the relation between stress intensity factor and AE parameter, new approach method for assessing the crack length and detectability of crack was proposed. Laboratory experiment was carried out to identify AE characteristics of fatigue cracks for compact tension specimen. The relationship between a stress intensity factor and AE signals activity as well as conventional AE parameter analysis was discussed. As a result, the features of specific parameter such as the length of crack growth the AE energy, the AE peak amplitude, and the cumulative AE hits, showed the almost same trend in their increase as the number of fatigue cycle increased. From the comparisons of peak amplitude and AE energy with stress intensity factor, it was verified that the higher stress intensity factors generated AE signals with higher peak amplitude and a larger number of AE counts. If we can get more reliable database for the relation between AE parameters and stress intensity factor, this approach will provide a good information for evaluating both the existence of crack and the minimum detectable size of crack.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.41-49
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• 2005

Recently, ground has been often exposed to high temperature environments such as chemical ground improvement, thermal energy storage system, and underground nuclear waste disposal system. Since the behavior of clay is sensitive to temperature change, the studies on the engineering properties of clay subjected to high temperature history may be important. This paper presents the mechanical behavior of clay with high temperature condition. $\bar{CU}$ tests using a high temperature and pressure triaxial compression test apparatus were carried out in order to investigate characteristics of deformation, shear strength, compression and consolidation of clay. During tests, the temperature was varied from $20^{\circ}C,\;50^{\circ}C,\;75^{\circ}C,\;80^{\circ}C\;to\;100^{\circ}C$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.11 no.1 s.22
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• pp.53-59
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• 2005

It is very dongerous for ship‘s fire which occurs from navigating because of it will not be able to expect fire fighting from land so that handle with the oneself to control. Additionally, in the case of passenger ship is more serious for the reason of not only the property damage but also large life accident can be occurred continuously. When the fire occurs, the many smoke to occur simultaneously as well as the heat from combustion process and the poisonous smoke is brought the life damage as the death from suffocation The purpose of this study is to examine the smoke movement characteristics in the ship's indoor spaces with fire size and location An experimental study was carried out with two sized of fires and three typed of fire source locations. As the results, the smoke and heat diffusion characteristics Ms been showed the most quick rise curve in the case of comer type fire.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.167-173
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• 2005

It is very dangerous for ship‘s fire which occurs from navigating because of it will not be able to expect fire fighting from land so that handle with the oneself to control. Additionally, in the case of passenger ship is more serious for the reason of not only the properly damage but also large life accident can be occurred continuously. When the fire occurs, the many smoke to occur simultaneously as well as the heat from combustion process and the poisonous smoke is brought the life damage as the death from suffocation. The purpose of this study is to examine the smoke movement characteristics in the ship's indoor spaces with fire size and location An experimental study was carried out with two sized of fires and three typed of fire source locations. As the result of it, the smoke and heat diffusion characteristics has been showed the most quick rise curve in the case of comer type fire.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.164-164
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• 2017

토지이용 및 토지피복 변화는 인간의 활동에 따른 결과를 반영하며 자연환경의 변화와도 밀접한 관련이 있다. 수문환경의 변화는 수로 건설이나 하천정비, 사진개간, 도시화 등과 같은 인위적인 변화와 지구온난화에 따라 변화하는 기후 패턴에도 많은 영향을 받고 있다. 본 연구에서는 안성천 공도수위관측소 상류유역을 대상으로 SWAT(Soil and Water Assessment) 모형을 이용하여 현재의 유역 수문환경조건을 보다 현실적으로 분석하기 위해 연구를 실시하였다. 유역의 수문환경 조건을 정량적으로 파악하기 위하여 CLUE-s 모형을 이용한 토지이용변화가 기후변화 시나리오에 따른 수문학적 거동(지표유출, 증발산량, 총유출량, 수질거동)에 미치는 영향을 SWAT모형을 이용하여 파악하고자 하였다. 안성천의 공도 수위관측소($366.5km^2$)을 대상으로 유역 내 3지점의 기상관측소(이천, 수원, 천안)를 대상으로 40년(1976~2015)동안의 일 기상자료를 수집하여 SWAT 모형을 구축하였다. 평년 및 가뭄년을 포함하는 선별된 기간에 대하여 다양한 목적함수($R^2$, NSE, RMSE)를 활용하여 일반적인 전체기간 검보정 방법이 아닌 각각의 조합된 기간의 극단적 유출특성에 초점을 맞추어 검보정을 수행하였다. 이와 같이, 앞서 실시한 연구로 모형의 매개변수들을 해당 유역에 가뭄과 같은 극단적 유출상황에 따라 선행보정 실시하였으며, 이는 이번 연구에서의 모형의 신뢰성 있는 수문 및 수질 거동 분석을 할 수 있을 것이라 생각된다. 선행 연구 자료를 이용하여 토지이용변화를 고려한 본 연구를 통해 미래의 유역 수문환경조건 변화에 따라 수자원을 정량적으로 파악하는 데에 도움이 될 수 있을 것으로 판단된다.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.121-129
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• 2008

Numerical analysis for the in-situ top base foundation (In-situ TBF) was carried out in order to investigate the effect of bearing capacity and the load delivering mechanisms in granular soil. The input data for the numerical model was prepared from the result obtained from the plate load test and full size in-situ TBF field tests. According to the result of numerical analysis, the behavior of in-situ TBF showed that bearing capacity of the foundation increased by $50{\sim}100%$ and settlement was reduced up to $1/2{\sim}1/3$ comparing to other types foundation. The effect of cone-shaped part of the in-situ TBF was as important as pile part for the improvement of foundation stability. The variation of the length of pile part indicated that the present length was proved satisfactory in terms of effectiveness.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.135-144
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• 2009

The cable system of suspension bridges is a very important non-elastic element which caries an external load by a tension force of the cable, such that creates the integrity of a structure. It is not easy to find if cable system have been changed by the maintenance activities such as repairs or reinforcement. Sometimes the maintenance can cause structural deformations and changes of the tension force in cables. In most cases, the cable stayed bridges are managed by health monitering system, however, the main cable of suspension bridges need to develop more accurate and efficient monitoring system. The Namhee Bridge was constructed 35 years ago and it has been continually repaired and reinforced after then. This study describes the behavior of the cable system by analysing many of inspective reports and by using the results of hanger rope test and for the shape of main cables surveys.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.2
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• pp.13-22
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• 1998

This paper summarizes a study on the application of the friction pendulum system in bridge seismic isolation. Shaking table tests have been carried out on a model structure isolated with F.P.S and the obtained structural responses are compared to those of non-isolated. It can be concluded the F.P.S increases the earthquake resistance capacity of the isolated structure. It is also found that the stiffness of bearing, being controlled by the radius of curvature of the spherical sliding interface, is unaffected by the amplitude of the input excitation. Furthermore, the coefficient of sliding friction is velocity dependent so that in weak excitation the sliding velocity is low and, accordingly, the mobilized friction force is less than the one mobilized in strong excitation. Also, the frictional properties of the bearings remain markedly stable after extensive testing, and the permanent displacements are small and not cumulative in successive earthquakes.

• Journal of the Korean Geotechnical Society
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• v.32 no.10
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• pp.31-40
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• 2016

In order to investigate the change in soil arch structure developed within the soil subjected to trapdoor movement, various responses in the deformed particle assembly were observed via photoelastic measurement technique. The particle assembly was composed of the regularly stacked model particles coated by thin photoelastic material. Variation of the internal structure transmitting contact forces were observed by taking images showing the photoelastic responses and compared with the change in slip lines and pressures measured by load cells placed beneath the assembly. Initial soil arch structure established immediately after the trapdoor movement collapsed progressively and meanwhile a new extended structure was developed against further movement of the trapdoor. For the sufficient movement of the trapdoor, initially identical regions bounded by the soil arch structure and slip lines were separated and the region enclosed by slip lines became a part of the region loosing the transmitting contact forces identified by photoelastic measurement.

• Tunnel and Underground Space
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• v.17 no.3 s.68
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• pp.175-185
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• 2007

When filling material such as clay is included along the discontinuity, it may cause instability on a slope even if the direction of discontinuity works in a positive way. In the study area, slope sliding occurred at the boundary between a clay filling material and weathered soil because the physical properties differ across the boundary; and this is very similar to the situation where foliation in a rock works as a weak zone during a structural behavior, causing an inter-layer slip. In most analysis, if there exists a clay filling material, a single discontinuity is assumed to perform analysis. In those cases, the discontinuity is modeled as a slip surface within clay. Therefore, the characteristics of the boundary are not considered in the analysis, so that ultimately the physical property of clay usually prevails. The result of evaluating the slope stability affected by clay filling material shows the significant difference in the safety level due to the strength parameter depending on the failure type of the discontinuity by a filling material.