• Journal of the Korea Institute of Building Construction
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• v.16 no.4
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• pp.349-357
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• 2016

Recently, the quantity of risk in construction project has been inflated due to the fact that current construction projects have been large and complicated. Therefore, a study on the risk management methods is necessary that can predict and respond to the need in complicated modern construction projects. In this study, the objective is to analyze the cause of accident in actual construction sites and develop a risk assessment model based on insurance claims records. To reach the goal of this study, first, the frequency and severity of accidents are analyzed the causes of accidents based on the classification; progress rate, season, and total construction costs. Second, a risk assessment model is developed by utilizing a multiple regression analysis. The dependent variable is loss ratio of material damage and three categories; natural hazards, geographic information, and construction method & ability, are used as the independent variables. The model's adjusted R-square is 0.455. The contributions of this study will be used as a material for a quantitative risk analysis model development and review of the construction risk factors for future study.

• Korean Journal of Remote Sensing
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• v.38 no.6_3
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• pp.1761-1775
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• 2022

Due to unpredictable climate change, the frequency of occurrence of water-related disasters and the scale of damage are also continuously increasing. In terms of disaster management, it is essential to identify the damaged area in a wide area and monitor for mid-term and long-term forecasting. In the field of water disasters, research on remote sensing technology using Synthetic Aperture Radar (SAR) satellite images for wide-area monitoring is being actively conducted. Time-series analysis for monitoring requires a complex preprocessing process that collects a large amount of images and considers the noisy radar characteristics, and for this, a considerable amount of time is required. With the recent development of cloud computing technology, many platforms capable of performing spatiotemporal analysis using satellite big data have been proposed. Google Earth Engine (GEE)is a representative platform that provides about 600 satellite data for free and enables semi real time space time analysis based on the analysis preparation data of satellite images. Therefore, in this study, immediate water disaster damage detection and mid to long term time series observation studies were conducted using GEE. Through the Otsu technique, which is mainly used for change detection, changes in river width and flood area due to river flooding were confirmed, centered on the torrential rains that occurred in 2020. In addition, in terms of disaster management, the change trend of the time series waterbody from 2018 to 2022 was confirmed. The short processing time through javascript based coding, and the strength of spatiotemporal analysis and result expression, are expected to enable use in the field of water disasters. In addition, it is expected that the field of application will be expanded through connection with various satellite bigdata in the future.

• Korean Journal of Construction Engineering and Management
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• v.23 no.6
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• pp.30-42
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• 2022

OSC is a type of supply chain and value chain that spans the entire process of construction production (planning, design, construction, maintenance, etc.). It is a method of producing the final object by manufacturing it in a factory, transporting it to the site, installing and construction. This research as is the construction cost was compared for each case A, which applied the PC method, and case B, which applied the RC method. In the case of applying the PC method (excluding the PC design cost), compared to the case where only the RC method was applied, the frame construction cost per unit quantity (m³) increased by about 70% (50% based on the total RC construction type). Of the total frame construction cost of PC method application, PC accounted for 90.2%, 'PC manufacturing cost' 54.8%, 'PC assembly cost' 28.5%, and 'transportation cost' accounted for 6.89%. Also a decision-making framework that can consider both costs and benefits was established. In the case of benefits, the construction period, defect repair, disaster occurrence, energy efficiency, noise/dust/waste, and greenhouse gas emission indicators reflecting OSC technical advantages were presented. It can contribute to providing a basis for helping decision-making on the introduction of PC apartment houses using OSC.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.213-213
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• 2020

최근 나타나는 지구온난화와 이상기후로 인해 가뭄과 홍수피해 같은 자연재해 발생 빈도가 높아졌고, 하천에서는 오염된 수질과 수생태계 복원 및 수변공간 조성, 수자원 관리 등의 목적으로 수질환경 개선사업이 진행되고 있다. 수질환경 측면에서 하천에서 발생하는 가장 큰 문제점으로는 녹조 즉, 남조류의 발생을 예로 들 수 있다. 본 연구에서는 최근 보 개방을 통하여 수질개선 효과가 나타나고 있는 금강을 대상으로 세종보, 공주보, 백제보 구간에 대하여 주요 수질인자에 대한 상관관계 분석을 수행하였다. 특히 남조류 세포수와 주요 하천 수질인자를 Pearson's correlation analysis를 이용하여 상관관계를 분석하였고, 보 위치별 남조류 세포수를 종속변수로 하고, 상관도가 높은 수질인자를 독립변수로 하는 다중회귀식을 도출하여 금강 내 주요 하천 수질인자의 농도에 따른 남조류 세포수 관계를 규명하고자 하였다. 분석기간은 2012년 1월부터 2019년 12월까지 보 건설 이후 시점으로 선정하였고, 월 평균 남조류 개체수가 조류경보제 발령기준 관심단계이상에 해당하는 금강수계의 3개 보에 대하여 남조류 세포수와 수질에 영향을 끼치는 인자인 강수량, (수온)W·T, (수소이온농도)pH, (용존산소)DO, (생물화학적산소요구량)BOD, (화학적산소요구량)COD, (부유물질량)SS, (총질소)TN, (총인)TP, (클로로필-a)Chl-a, (전기전도도)EC, (질산성질소)NO₃-N, (암모니아성 질소)NH₃-N, (인산염 인)PO₄-P, (용존총질소)DTN, (용존총인)DTP, (총유기탄소)TOC 와의 상관관계를 분석하였다. 분석 결과 측정 지점별 남조류 세포수와 상관관계가 있는 인자는 서로 상이했지만 (수온)W·T과 pH의 경우 모든 지점에서 남조류 세포수와 양의 상관관계가 나타났다. 세종보는 W·T(0.383, P<0.01), pH(0.391, P<0.05)의 양의 상관계수를 나타냈고, 공주보에서는 (수온)W·T(0.436, P<0.05), pH(0.412, P<0.05)의 양의 상관관계를 나타냈다. 백제보에서는 (수온)W·T(0.415, P<0.01), pH(0.221, P<0.01)의 양의 상관성을 나타냈다. 남조류 세포수와 수질인자 간의 상관관계 분석에 따라 통계적으로 유의한 인자 중 (수온)W·T과 pH에 영향을 받는 영양염류와 퇴적물에 대한 후속 연구가 필요할 것으로 사료되며, 연구를 통해 제시된 남조류 세포수 다중회귀식은 주요 수질인자 농도에 따라 발생 가능한 남조류세포수를 예측하여 금강의 수질 관리에 활용될 수 있을 것으로 기대된다.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.194-199
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• 2020

Unlike in the past, the world is facing water shortages due to climate change and difficulties in simultaneously managing the risks of flooding. The Four Major Rivers project was carried out with the aim of realizing a powerful nation of water by managing water resources and fostering the water industry, and the construction period was relatively short compared to the unprecedented scale. Therefore, the prediction and analysis of how the river environment changes after the Four Major Rivers Project is insufficient. Currently, part of the construction section of the Four Major Rivers Project is caused by repeated erosion and sedimentation due to the effects of sandification caused by large dredging and flood-time reservoirs, and the head erosion of the tributaries occurs. In order to solve these problems, the riverbed maintenance work was installed, but it resulted in erosion of both sides of the river and the development of new approaches and techniques to keep the river bed stable, such as erosion and excessive sedimentation, is required. The water agent plays a role of securing a certain depth of water for the main stream by concentrating the flow so much in the center and preventing levee erosion by controlling the flow direction and flow velocity. In addition, Groyne products provide various ecological environments by forming a natural form of riverbeds by inducing local erosion and deposition in addition to the protection functions of the river bank and embankment. Therefore, after reviewing the method of determining the shape of the Groyne structure currently in use by utilizing the mobile limit flow rate and marginal reflux force, a new Critical Movement Velocity(${\bar{U}}_d$) and a new resistance coefficient formula considering the mathematical factors applicable to the actual domestic stream were developed and the measures applicable to Groyne installation were proposed.

• Korean Journal of Environment and Ecology
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• v.27 no.4
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• pp.487-497
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• 2013

This study was conducted to suggest vegetation management plan for Gugok landscape maintenance and improvement by deducing the vegetation landscape factors inherent in Yongha Gugok and understanding vegetation structure through the investigate of existing vegetation and plant community structure of Yongha valley in Woraksan National Park. There were broad and flat rocks, natural layered stones, clear water, light stones, stream, valleys, waterfalls, Pinus densiflora and Acer pseudosieboldianum as a result of deducing natural factors on poetry. There were P. densiflora and A. pseudosieboldianum appeared as one of main vegetation landscape elements. The actual vegetation analysis results were as followed. The natural vegetation occupied 67.5% and it was classified as P. densiflora community, Quercus variabilis community, Q. variabilis-P. densiflora community, Q. variabilis-Q. serrata community, Q. serrata community, Q. mongolica community, Q. mongolica-P. densiflora community, Deciduous broad-leaved tree community. The artificial vegetation(18.7%) was classified as Q. serrata community-Larix kaempferi community, Q. mongolica- Castanea crenata community, L. kaempferi community, L. kaempferi-C. crenata community, fruticeta, L. kaempferi-Q. mongolica community. The grassland area(2.0%) was classified as Miscanthus sinensis community, Phragmites communis community, and other areas were classified as landscape tree planting area, farm, orchard, residential area. The representative vegetation were P. densiflora community, Q. variabilis-Q. serrata community, L. kaempferi community, Deciduous broad-leaved tree community in Yongha Gugok. The species diversity index of Shannon was 0.6274~0.9908 on the whole. Yongha Gugok, as a symbol of succession on confucianism and reverence for nature, should be preserved natural valley landscape being clean and wijungchuksa at the end of Joseon Dynasty and Japanese Colonial era. In this historical and cultural Gugok, vegetation landscape management plan is needed to landscape maintenance with P. densiflora community, density control with L. kaempferi community. And it is considered when natural disasters and artificial damages happened, P. densiflora-oriented vegetation restoration plan should be applied in order to restore.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.180-194
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• 2017

Agricultural hazards management technology, which would allow individual farms to respond preemptively, has been developed. A preliminary system developed in the previous study provides precise weather forecasts by farms, notification of weather hazards by crops and delivery of response guidelines (http://www.agmet.kr). Although the GIS map-based alarm system has been implemented for a number of farmers and their farms, its user interface was not designed for individual users who seek information at their farms. In this study, we have developed a mobile application to provide early warnings of weather hazards up to 10 days in advance. A set of information including field-specific weather, crop growth stages and weather hazard alerts can be delivered to individual farmers through their mobile phone. This would guide users to access the map-based system using their smartphone to obtain field-specific weather information by the growth stage of cultivated crops. This would help the farmers make the better use of the existing weather-hazard GIS map-based alarm system.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.5
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• pp.43-50
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• 2012

The Green Infrastructure Framework refers to an interconnected network formed by greenways that links gardens, parks, green spaces, streams, wetlands, agricultural lands, and green belts. Green infrastructure supports diverse functions to environment, provides various benefits to people, and helps in the community's health and viability. It can store stormwater runoff and abate its non-point source pollutants. Due to its advantages and profits, advanced countries in environment policies have adopted green infrastructure in planning and implementing urban and regional development. The Korean government and municipalities have focused upon grey infrastructure investment in the past, which causes occurrence of natural disasters such as draught, flood, and landslides, degradation of water and air quality, decline of biodiversity, and even inhibition of economic activities. In order to alleviate these problems, it is requested to formulate and implement policies for green infrastructure at the national government level. USA and Korean situation of green infrastructure were investigated; forty components of green infrastructure were drawn. Nine policies utilized in the USA cases were identified, which are applicable to Korea. Among them, five policies can be implemented in public sector and four in private one. The green infrastructure law needed in Korea was suggested. The amendments of laws regarding green infrastructure and alternatives expending it were proposed.

• Tunnel and Underground Space
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• v.27 no.6
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• pp.343-350
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• 2017

Amid increasingly saturated ground space, development of underground space has been booming throughout the world and excavation has been underway near the structure above or under the ground level. But the ground subsidence caused by improper or poor construction technologies, underground water leakage, sudden changes of stratum and the problem with earth retaining system component has been emerged as hot social issue. To deal with such problems nationwide, establishment of preventive and proactive disaster management and rapid restoration system has been pushed now. In this study, collection of the data on technology development trend to secure the underground safety was made, taking into account of internal change elements (changing groundwater level, damage to underground utilities, etc) and external change elements (vehicle load, earthquake and ground excavation, etc) during excavation. Amid the growing need of ground behavior analysis, ground subsidence evaluation technology, safe excavation to prevent ground subsidence and reinforcement technology, improvement of rapid restoration technology in preparation for ground subsidence and development of independent capability, this study is intended to introduce the technology development in a bid to prevent the ground subsidence during excavation. It's categorized into prediction/evaluation technology, complex detect technology, waterproof reinforcement technology, rapid restoration technology and excavation technology which, in part, has been in process now.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.69-77
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• 2015

In Korea, local governments have decided the location of shelters as part of their disaster planning. However, no quantitative standards, such as assuming different hazard and shelter types, shelters' capacity, are specified in that planning. To propose the direction of disaster evacuation policy, first of all, the current state of shelters' location and evacuation area is needed to be analyzed. In addition, considering topographical condition such as road slope and physical strength by age are important factors to measure optimal evacuation route. The purpose is to suggest a new methodology of estimating optimal evacuation route considering resistance of road slope and difference of walking speed by age. Moreover, as a case study of Seoul, Korea, using coverage analysis of GIS analysis tool, the accessible area (or vulnerable area) to the shelters is evaluated based on the spatial distribution of disaster evacuation shelters and their accommodation capacity, according to evacuation time within 7.5, 15 and 30 minutes. The main results are summarized as follows: 1) The average area of disaster evacuation shelter per person is calculated as 0.45 square meters. Considering that the minimum shelters' area per person is 1 square meters, only 45% of people in Seoul can be accommodated. 2) The ratio of inhabitants who live in accessible area within 7.5 minutes presents only 33% of all. Furthermore, the ratio of inhabitants by age group of 5~9 or over 65 years old shows significantly lower percentage in comparison with 15~49 years old people.