• Journal of the Korean Geotechnical Society
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• v.26 no.2
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• pp.45-54
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• 2010

The SCW numerical model described in the companion paper was used to carry out a comprehensive parametric study to evaluate the performance of the SCW. The five ground related parameters, which are porosity, hydraulic conductivity, thermal conductivity, specific heat, geothermal gradient, and five SCW design parameters, which are pumping rate, well depth, well diameter, dip tube diameter, bleeding rate, were used in the study. Two types of numerical simulations were performed. The first type was used to perform short-term (24-hour) simulation, while the second type 14 day simulation. The study results indicate that the parameters that have important influence on the performance of SCW were hydraulic conductivity, thermal conductivity, geothermal gradient, pumping rate, and bleeding rate. The thermal conductivity had the most important influence on the performance of the SCW. With the increase in the geothermal gradient, the performance increased in the heat mode, but decreased in the cooling mode. The hydraulic conductivity influenced the performance when the value was larger than $10^{-4}m/s$. The depth of the well increased the performance, but at the cost of increased cost of boring. The bleeding had an important influence on SCW, greatly enhancing the performance at a limited increased cost of operation. Overall, this study showed that various factors had a cumulative influence on the performance of the SCW, and a numerical simulation can be used to accurately predict the performance of the SCW.

• Korean Journal of Construction Engineering and Management
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• v.24 no.1
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• pp.31-39
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• 2023

To reduce facility management costs and safety concerns due to aging of facilities, it is important to estimate the future facilities' condition based on facility management data and utilize predictive information for management decision making. To this end, this study proposed a methodology to estimate facility elements' condition using XGBoost. To validate the proposed methodology, this study constructed sample data for road bridges and developed a model to estimate condition grades of major elements expected in the next inspection. As a result, the developed model showed satisfactory performance in estimating the condition grades of deck, girder, and abutment/pier (average F1 score 0.869). In addition, a testbed was established that provides data management function and element condition estimation function to demonstrate the practical applicability of the proposed methodology. It was confirmed that the facility management data and predictive information in this study could help managers in making facility management decisions.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.561-562
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• 2015

2013년 이후, 한국전력공사에서는 신규건설 변전소로 디지털변전소(Digital Substation)를 건설하고 있다. 디지털변전소 내에는 서버(IED, 지능형전자장치), 클라이언트(상위운영시스템)가 필수요소들이며, 이 둘은 서로 서버/클라이언트 통신 서비스를 수행하고 있고 IEC61850 기반으로 하고 있다. 바뀐 정책과 프로토콜 때문에 사용되는 기기 역시 기존 디지털 보호 계전기에서 IED로 성능이 변화하였고, 기존에 수행하던 보호성능검증 방법인 동특성시험 역시 IEC61850 기반 통신서비스 성능도 함께 보아야 한다는 관점에서 본 연구가 시작되었다. 본 논문에서는 RTDS를 이용한 IEC 61850 기반 IED 동특성 시험 성능검증 방법에 대하여 살펴보고, 그 결과를 알아보고자 한다.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.804-807
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• 2008

Recently, with the increase of high rise and huge scale building construction, the use of high strength concrete has been increasing. High strength concrete has dense pore structure, which is susceptible to be damaged due to fire attack. For this, many researchers provide proper fire endurance method. In this paper, to provide the priority for selecting fire endurance method in high strength concrete execution, AHP technique is applied based on expert questionnaire. Fire endurance performance efficiency and ordinary performance efficiency was selected for level 1. Fire endurance performance efficiency had larger weight than ordinary one.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.309-309
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• 2023

자연재해대책법에 따라 방재성능목표를 달성하기 위해 행안부 및 지자체는 방재성능목표강우량을 설정·운영하고 있다. 현재, 기후변화로 인한 할증률을 산정하여 방재성능목표강우량 산정에 포함하고 있으나, 기후의 내적변동성으로 인한 강수의 변화는 반영하지 못하고 있는 실정이다. 이에 본 연구에서는 기후변화뿐만 아니라, 엘리뇨, 라니뇨, ENSO 등과 같이 지구의 내적인 원인들로 인해 변화하는 기후내적변동성(Climate Internal Variability, CIV)을 추가적으로 고려하여 할증률 개념을 확장하고자 한다. 외부의 Forcing 변화(즉 기후변화)가 없더라도 자연적으로 기후가 변동하는 현상을 모의하기 위해, 크게 3개 동역학적, 통계학적, 추계학적 방법들이 적용되어 기후내적 변동성을 정량화하고 있다. 본 연구에서는 기후에 대한 일기를 추계학적으로 오랜 기간 동안 생성하고 생성된 시계열을 바탕으로 자연적인 변동성을 추출(Stochastic Approach)하는 방법을 사용하여 기후내적변동성을 추정할 것이다. 구체적으로, 생성된 앙상블 시계열에 Detrended 방법과Differenced 방법을 각각 적용하여 기후내적변동성의 크기를 정량화하고 상호 비교할 예정이다. 정량화된 기후내적변동성의 크기는 추계학적 할증률로 변환될 것이며 방재성능목표강우량 산정에 포함시켜 과거 기왕최대강우량을 갱신하는 지역에 대한 위험도를 추가로 제시할 수 있을 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.351-361
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• 2006

In this study, nonlinear finite element analysis procedures are presented for the seismic performance assessment of circular reinforced concrete bridge piers with confinement steel. This paper defines a damage index based on the predicted hysteretic behavior of a circular reinforced concrete bridge pier. Damage indices aim to provide a means of quantifying numerically the damage in circular reinforced concrete bridge piers sustained under earthquake loading. The proposed numerical method is applied to circular reinforced concrete bridge piers with confinement steel tested by the authors. The proposed numerical method gives a realistic prediction of seismic performance throughout the loading cycles for several test specimens investigated.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.323-332
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• 2019

Non-curable rubberized polymer asphalt waterproof coating materials in Korea and China are manufactured without advanced quality control techniques and common standard, And they are exposed consistent water leakage problems. Import and application of Korean waterproofing products and installation methods is difficult in the present situation as the Chinese standard(JC/T 2428) is different in nature with the Korean counterpart products, And quality assurance is inevitable based on mutual standards. In order to resolve this issue, alternatives such as using standards provided by the ISO (International Organization for Standardization) are generally employed, but there is no such ISO standard as a waterproof material for non-curable rubberized polymer asphalt material. Furthermore, it is unreasonable to develop the ISO standard for rubber asphalt seals for exchange in terms of time and cost. This study proposes that the establishment of a quality standard that can be applied for both countries will be required via an joint international standard that outlines the properties of materials if applied in mutual trade exchange.

• Land and Housing Review
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• v.13 no.3
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• pp.93-106
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• 2022

Ventilation plays an important role in controlling indoor air quality. Due to the recent spread of infectious diseases such as COVID-19 and with people spending more time indoors, there's been increased attention on the importance of ventilation performance. In many countries, ventilation is regulated by airflow rates and the number of air changes per hour (ACH). However, airflow rates and ACH alone do not provide an accurate account of actual indoor pollutant removal and ventilation uniformity in a space. This study looked into the ventilation performance of an actual residential unit using several sampling points instead of basing it off of airflow and air change rates. Literature review was used to derive relevant influencing factors and the tracer gas dilution method was used for the field test. The study measured air velocity, age of air, and ventilation efficiency at several locations and compared them to the average value at the center of the test space to determine the differences in ventilation performance at the selected measurement points. The study showed that different sampling locations resulted in different ventilation values. Findings of this study will be used to develop an experimental procedure for evaluating indoor ventilation performance of actual residential spaces.

• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.905-918
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• 2023

This study aimed to assess runoff reduction performance and determine installation priorities for Permeable Pavement (PP) and Rain Barrel (RB) within the Mokgam Stream basin. Optimal design parameters were determined to maximize the effectiveness of PP and RB in reducing runoff. Furthermore, the optimal parameters were incorporated to compare the runoff reduction performance of PP and RB. Analysis of the runoff curve at the basin outlet indicated that PP demonstrated superior performance in reducing runoff during the rising limb of the curve. At the same time, RB excelled within the falling limb. Comparisons of total runoff and peak runoff reduction by sub-catchment revealed that in larger sub-catchment areas, PP outperformed RB in runoff reduction. In contrast, RB exhibited higher performance in areas with a higher impervious ratio. Based on the evaluation of runoff reduction performance for PP and RB, installation priorities were determined within the Mokgam Stream basin. The results showed that PP and RB installations were prioritized for sub-catchments with larger areas and a higher impervious ratio. Furthermore, the correlation between the ranking of runoff reduction performance and sub-catchment characteristics showed a high correlation with both the impervious area ratio and sub-catchment geometrical properties in sub-watersheds exhibiting the top 25% runoff reduction performance. These results emphasize that when determining the priority for installing LID facilities in developed urban areas, it is necessary to consider not only the impervious area ratio but also the geometrical properties of the sub-catchment.

• Korean Journal of Construction Engineering and Management
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• v.22 no.6
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• pp.138-146
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• 2021

135 Degree standard hook workability crossed in the Reinforced Concrete (RC) Structure is improved and it reinforces in one side 90° hook binding. As a result, we proposed a One-touch Rebar Reinforcing Clip(RCC Device) that demonstrates the same performance as the 135° standard hook. It was developed through the evaluation of construction and economic analysis. As a result of analyzing 13 sites applied from June 2020, As expected, most of the cases were applied to the structural supervision or the point of the construction supervisor as an irresistible measure. therefore, Through field performance analysis, Various methods such as the method that the original contractor first purchases and then provides after contract with the partner company were proposed for the use of efficient and voluntary reinforcing clip. As a result, It is expected that the contribution in the field will be very high in terms of quality and process management through active utilization.