• Geotechnical Engineering
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• v.14 no.3
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• pp.123-134
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• 1998

To analyse the stability of a slope composed of waste material produced in a closed lead mine, numerical modeling has been carried out in two dimension using FLAC, finite difference program. The research was focused on the effect of the earthquake as well as a rise of water table upon slope stability. The numerical results have shown that the slope would not be safe against earthquake event and that the increase of pore pressure due to a rise of water table up to the ground level may result in a failure of the slope. On the basis of numerical analyses and site investigation, two sorts of measures have been taken. In short term, removal of a part of materials deposited on the top of the pile is required to increase immediately safety factor of the slope even a little. In ling term, it is necessary to repair drainage facilities and dam which covers waste material so that the slope is prevented from failure in a radical manner. It has been confirmed by numerical analyses that an improvenment of the stability can be in a great extent expected after such measures have been performed.

• Journal of Korea Water Resources Association
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• v.49 no.2
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• pp.121-132
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• 2016

The DAMBRK is applied to Janghyeon and Dongmak reservoirs in Namdaecheon basin, where two reservoirs were failed due to Typhoon Rusa in 2002. Relaxation scheme is added to DAMBRK to consider the tributary cross-section because two reservoirs are in tributary valleys. In addition, this study suggests the method to utilize the reservoir breach formation time of ASDSO (2005) and empirical formulas for peak break outflow from dam to reduce the uncertainty of reservoir breach formulation time. The single break of Janghyeon reservoir and consecutive break of Janghyeon and Dongmak reservoirs with the suggested method are considered. While the breach discharge from reservoirs rushes down, the discharge and water surface elevation along the river are predicted, and the predictions show the attenuation phenomena of reservoir break floodwave. The applicability of the model is validated by comparing the predicted height with field surveyed data, and showing good agreements between predictions and measurements.

• Journal of the Korean GEO-environmental Society
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• v.22 no.10
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• pp.21-29
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• 2021

Most concrete gravity-type dams in and out of the country were constructed by column method to control cracks caused by concrete hydration heat generated during construction, resulting in a certain level of leakage after impoundment through various causes, such as contraction joints and construction joints. However, due to the characteristics of concrete structures that shrink and expand according to temperature, concrete dams have vertical joints and drains to allow penetration. PVC waterproof shows excellent effects in completion of the dam, which however increases the possibility of interfacial failure due to different thermal expansion. Other causes of penetration may include problems with quality control during installation, generation of cracks due to heat of hydration of concrete, waterproofing methods, etc. In the case of Bohyunsan Dam in Yeongcheon, North Gyeongsang Province, the amount of drainage in the gallery was checked and underwater, and it was confirmed that there are many penetrations from drainage holes connected to vertical joints, and that some of the PVC waterproofs are not fully operated. As a new method to prevent penetration through vertical joints, D.S.I.M. (Dam Sealing Innovation Method) developed by World E&C was applied to Bohyunsan Dam and checked the amount of drainage in the gallery. As a result of first testing three most leaking vertical joints, the drain in the gallery was reduced by 87% on the average and then applied to the remaining 13 locations, which showed a 83% reduction effect based on the total drain in the gallery. Summing up these results, it was found that D.S.I.M. preventing water leakage from the upstream face is a valid construction method to reduce the water see-through and penetration quantity seen in downstream faces of concrete dams. If D.S.I.M. is applied to other concrete dams at domestic and abroad, it is expected that it will be very effective to prevent water leakage through vertical joints that are visible from downstream faces.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.4
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• pp.327-330
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• 2015

The safety and success of dental sedation for children depend mainly on respiratory status of patients. A special condition, that is, nasal breathing in supine position with their oral airway blocked by rubber dam, should be considered. Therefore, irrespective of medical consultation, pediatric dentists themselves should do respiratory assessment especially adenotonsillar hypertrophy, nasal obstruction, posterior nasal drainage and airway hypersensitivity. Patients with sinusitis, allergic rhinitis, asthma, snoring and OSAS(obstructive sleep apnea syndrome) can induce the sedation failure and complete management of these can improve the safety of dental sedation.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.361-372
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• 2012

In order to establish the methodology for estimating an emergency drinking water supply in Korea, overseas cases and accidents history of cutting off water supply were investigated, and questionnaire was conducted. Investigating accidents history of cutting off water supply in Korea, actual cutting off times of most cases were less than 13hours. Also, cases related with water quality and facility failure have been not enough to derive useful information for estimating an emergency water. From the results of questionnaire and cross-tabulation analysis, about 1,066 lpcd(liter per capita${\cdot}$day) as an emergency water and 14 days as tolerable outages time could be estimated. The results of water quality simulation could tell us that it might take 5-16 days for pollutant matter to travel from 15 contamination points to source water intake point in the selected reservoir(D-dam). This travel time was in good accordance with the estimated tolerable outage time, 14days.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1757-1761
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• 2007

이 연구는 1999년 7월 31일부터 8월 3일까지 경기도 북부지방의 임진강 전유역에 걸쳐 내린 집중호우로 발생한 연천댐 일부 유실에 따른 사고에 대해 댐파괴를 모의하였다. 댐지점의 홍수량 분석은 HEC-HMS모형을 사용하여 한탄강 유역을 15개의 소유역으로 분할하여 분석하였고 댐유출량 산정은 FLDWAV모형의 DAMBRK모듈을 사용해 모의하였다. 댐파괴 홍수량에 의해 발생되어지는 홍수파 해석은 HEC-RAS모형을 구축하여 모의하였다. HEC-RAS모형의 검증은 1999년 7월 31일부터 8월 2일 까지 한탄강수계 내 전곡수위표에서 관측된 관측수위와 비교하여 검증하였다. 연구분석은 댐이 없는 자연상태(Case1)와 댐이 있는 경우 (Case2) 그리고 댐파괴된 경우(Case3) 세가지로 구분하여 분석하였다. 연구결과 연천댐 지점의 첨두 홍수량은 Case1의 경우 $10,324m^3/sec$, Case2의 경우 $10,117m^3/sec$, Case3의 경우 $11,485m^3/sec$로 모의 되었고 이때의 관측수위는 각각 EL.43.59m, EL.43.38m, EL.44.03m였다. 댐이 있는 경우와 댐파괴된 경우를 비교 하였을때 첨두 홍수량은 $1368m^3/sec$증가하였고 수위상승은 0.65m였다. 댐이 없는 자연상태와 댐파괴된 경우를 비교 하였을땐 첨두 홍수량은 $1161m^3/sec$증가하였고 수위상승은 0.65m였다.

• Journal of the Korean GEO-environmental Society
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• v.13 no.4
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• pp.71-76
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• 2012

Shear strength of soil is power that resists failure and sliding according to any face in soils and one of the most important factors during engineering properties of soil. Shear strength is used for engineering science problems as bearing capacity methods of foundation or piles, slope stability after dam or Cutting Embankment and stability problem analysis of soils as lateral earth pressure of soil structures, ets. This study has analyzed shear strength change of samples classified 2.00mm(10sieve)와 0.85mm(20sieve), 0.475mm(40sieve) using direct shear tester after removing and drying cohesive soil ingredient of Weathered granite soil Therefore, this study would help studies about shear strength properties by particle size.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1248-1257
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• 2014

Overhead transmission lines are crucial components in power transmission systems. Well-designed maintenance strategy for overhead lines is required for power utilities to minimize operating costs, while improving the reliability of the power system. This paper presents a maintenance priority index (MPI) of overhead lines for a reliability centered approach. Proposed maintenance strategy is composed of a state index and importance indices, taking into account a transmission condition and importance in system reliability, respectively. The state index is used to determine the condition of overhead lines. On the other hand, the proposed importance indices indicate their criticality analysis in transmission system, by using a load effect index (LEI) and failure effect index (FEI). The proposed maintenance method using the MPI has been tested on an IEEE 9-bus system, and a numerical result demonstrates that our strategy is more cost effective than traditional maintenance strategies.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.1027-1044
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• 2017

Membrane penetration is the most important factor influencing the measurement of volume change for triaxial consolidated-drained shear test for coarse-grained soil. The effective pressure p, average particle size $d_{50}$, thickness $t_m$ and elastic modulus $E_m$ of membrane, contact area between membrane and soil $A_m$ as well as the initial void ratio e are the major factors influencing membrane penetration. According to the membrane deformation model given by Kramer and Sivaneswaran, an analytical solution of the membrane penetration considering the initial void ratio is deduced using the energy conservation law. The basic equations from theory of plates and shells and the elastic mechanics are employed during the derivation. To verify the presented solution, isotropic consolidation tests of a coarse-grained soil are performed by using the method of embedding different diameter of iron rods in the triaxial samples, and volume changes due to membrane penetration are obtained. The predictions from presented solution and previous analytical solutions are compared with the test results. It is found that the prediction from presented analytical solution agrees well with the test results.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.10
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• pp.171-180
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• 2019

In Korea, the seismic design of non-structural elements was interested by Earthquake of the 2016 Gyeong-ju and 2017 Po-hang. Among the non-structural elements, the ceiling system with steel panel used in Po-hang station showed failure examples of non-seismic design ceiling. In this study, the seismic performance of suspended ceiling with steel-panel, such as those used in Po-hang Station, was evaluated by shaking table tests. The shaking table tests were performed in accordance with the ICC-ES AC156 standard with floor acceleration being applied horizontally in one direction using a $3.3{\times}3.3m^2$ frame. The ceiling system consists of steel-panels, carrying channels, main and cross T-bars, and anti-falling clips. The anti-falling clip prevents the steel panel falling completely. The shaking table test confirmed that the damage at the previous stage had a direct impact on the damage state at the next stage. Through the shaking table test, the damage state of the T-bar type steel-panel suspended ceiling system was defined.