• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.1
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• pp.57-70
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• 2002

Since early in the 90's, the need for construction of underground rock structures such as long and large section traffic tunnel, energy storage cavern, industrial facility, etc. has been largely increased because the Korean territory is not wide and about 65 % of the land consists of mountainous region. The initial rock stress measurement has been widely conducted to provide the quantitative information on the stress state of engineering site at the design stage of underground rock structures. Among the diverse methods developed for measuring rock stress, hydraulic fracturing test is most popularly used because it is applicable at pre-construction stage and has no limit in testing depth. In this paper, the characteristics of initial rock stress state in mountainous region were studied on the basis of the in-situ hydraulic fracturing stress measurement results from the 60 test boreholes in various parts of Korea.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.2
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• pp.83-96
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• 2011

Currently, the commonly used tunneling method in Korea is NATM (New Austrian Tunneling Method). This method uses the rock bolt, shotcrete, and supporting system to maintain the strength of original soil and ensures the stability of tunnel by stabilizing the soil using the original strength of the soil in maximum after the excavation. In past years, wire-mesh reinforced shotcrete was common ones but currently steel-fiber reinforced shotcrete is being widely used for the tunnel construction site in Korea to save construction time with the advanced construction technology. The results further indicate that needs for the establishment of not only the specifications for shotcrete but the strengthening methods for the under reinforced shotcrete sections. Therefore, this study deals with the development of a new steel-fiber to ensure the stability of tunnels that are under reinforced with steel-fibers and to overcome the shortcomings of conventional method.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.109-115
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• 2008

Malfunction of gutter systems in the slope area accelerate to percolate surface flow into underground and to cause the decrease of soil strength, Overflowing from gutter causes soil erosion from slope surface, secondary it is one of the main reasons to cause disaster in the hillside area. Much researches were reported and are undergoing about flood disaster in the down stream area, but rare in the upper reach(hillside). It is considered that improving function of gutter in the hillside is very important to prevent the disaster caused by rainfall. In this paper, After analyzing relationship between rainfall and disaster on the hillside in Busan, researches about having surface flow run into gutter effectively and preventing from overflowing outside of gutter on the hillside in Busan were carried out. Improved design methods of gutter are suggested to mitigate disaster in the sloping area by analysis of collected data and hydraulic model test.

• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.503-513
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• 2007

The seismic responses of a building are affected by the connection characteristics that have effects on structural stiffness. In this study, push-over analysis and time history analysis were performed to estimate structural behavior of 2D eight-story unbraced steel structures with partially restrained composite connections using a nonlinear dynamic analysis program. Nonlinear $M-{\theta}$characteristics of connection and material inelastic characteristics of composite beam and steel column were considered. The idealization of composite semi-rigid connection as fully rigid connection yielded an increase in initial stiffness and ultimate strength in the push-over analysis. In time history analysis, the stiffness and hysteretic behavior of connections have effects on base-shear force, maximum story-drift and maximum moment in beams and columns. For seismic waves with PGA of 0.4 g, the structure with the semi-rigid composite connections shows the maximum story-drift with less than the life safety criteria by FEMA 273 and no inelastic behavior of beam and column, whereas in the structure with rigid connections, beams and columns have experienced inelastic behaviors.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.91-96
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• 2011

The design, construction and management of underground facilities as infrastructure of nation should be properly carried out. One of reasons for underground facilitie's failure is a non-proper construction of backfill materials. This is common for circular underground pipes. A non-proper compaction is the cause of settlement and decrease of performance of underground facilities. The use of controlled low strength materials is an alternative to reduce the couple of failure problems. The flowability, self-cementation, and non-compaction are the major advantages to use the controlled low strength materials. In this research, couple of recycled materials, such as in-situ soil, water-treatment sludge, and crumb rubbers, were adopted. The basic properties of each materials were determined according to KS or ASTM. Also, couple of laboratory tests were carried out to get the design parameters for geotechnical and roadway area.

• Journal of Practical Engineering Education
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• v.11 no.1
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• pp.33-41
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• 2019

A pavement construction process consists of series of lay-down operation for pavement materials to form a designated thickness and compaction operation for the lay-down layer to form a designated strength. A technological breakthrough in pavement compaction equipment was made in last 15 years in western countries: intelligent compaction roller, that is equipped with GPS along with other pavement response sensors is becoming a game-changer in pavement construction. This paper introduces AR system that may be used in asphalt pavement compaction operation using intelligent compactor. Since AR technology is very new concept in road construction society, a suggestion for accompanying education program was also made for specific task group in pavement compaction operation. Since AR technology has not been introduced in asphalt pavement compaction operation, the AR compaction management would lead the construction quality of asphalt pavement to the beyond level.

• Explosives and Blasting
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• v.39 no.2
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• pp.15-26
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• 2021

Domestic electronic detonators are used widely in many quarry and construction sites since its launch at 2013. In the case of SOC projects conducted in the city, most of them are designed in high-depth to reduce complaints. The high-depth excavation needs a long construction period and huge cost for building shaft and ventilation hole. Mechanical excavation method is applied when safety things are located nearby the site. Solidity of rock and machine's performance affect on the method's efficiency. So as the efficiency is getting lower, the construction period is extended, and the cost is increases as well. This case study is about changing the machine excavation method to the blasting method which is electronic detonator applied at the shaft construction site in the city. This is an example of using electronic detonators on the construction site in reducing blast-noise and vibration while meeting environmental regulatory standards.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.386-394
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• 2022

In this study, the mechanical properties and frost resistance of concrete with steel and nylon fibers were experimentally investigated. Both of OPC concrete with 100 % ordinary portland cement and SGC concrete replaced with 50 % GGBFS were manufactured to evaluate effects of fibers to the performance of concrete. Compressive and split tensile strength, ultrasonic pulse velocity and surface electric resistivity measurements of concrete were carried out at a predetermined interval. In addition, the freezing & thawing resistance of concrete in accordance with ASTM C666 standard was also examined. As a result, it is seemed that the effect of fibers was remarkable to improve the mechanical properties and frost resistance of concrete, especially for the concrete incorporating steel fiber.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.355-355
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• 2020

최근 쓰나미와 해일 등 이상기후에 의한 해수면 상승 등으로 인한 해안지역의 침수가 빈번해지고 있다. 태풍 매미의 경우, 피해규모는 인명피해 130명, 이재민 4089세대 10975명, 재산피해 4조 7810억원이며 침수피해는 규모는 주택 21,015동과 농경지 37,986ha으로 나타났다. 특히 이 태풍은 경남 사천시 부근 해안에 상륙할 때의 중심기압은 950hPa로 중심부근 최대풍속 40m/s 이었으며 풍속 15 m/s 이상으로로, 태풍의 강도는 [강], 크기는 [중형]이었음에도 그 피해는 과거에 비해 크게 나타났다. 내륙과는 달리 해일 등의 피해로 인한 해안지역의 침수피해 저감기법은 월파방지 파라펫 설치 또는 침수예상 지역의 지반고를 높이는 이외에는 확실한 대책이 없는 것이 특징이라 하겠다. 따라서 해안지역 침수예방은 월파방지 파라펫과 함께 인명피해 최소화를 위해서는 충분한 선행시간을 통한 대피안내와 가장 효율적인 대피경로를 제공하는 것이 최선이라 할 수 있다. 본 연구에서는 경남 창원지역의 해수면 상승으로 인한 해안지역 침수를 모의할 수 있는 2차원 부정류 프로그램을 개발하고 매미 당시 창원지역의 침수피해 결과와 비교하여 프로그램 모의 결과를 검증하였다. 해안을 따라 다양한 높이의 월파방지 파라펫을 모의하여 시간대별 대상지역의 침수규모를 시간대별로 예측하였다. 모의결과 월파방지 파라펫 규모 별 침수규모와 이에 따른 경제적 피해규모를 산정하였으며 경제성 원칙에 따른 최적의 파라펫 규모를 제시하였다. 또한 이때 시간대별 침수범위 예측 결과를 바탕으로 시간대별 등침수선을 제시하고 일정 시간대별 등침수선을 모의결과를 이용하여 산정하였다. 도로 경사와 대피자의 연령 등을 고려한 대피소요 시간을 산정하여 침수 소요 시간과 비교하여 대피가 가능한 대피경로를 제시하는 알고리즘을 제안하였다. 본 연구결과는 기존에 알려진 대피경로와는 달리 다양한 침수저감 기법규모에 따라 다양한 대피경로를 제안할 수 있었으며 이는 추후 다양한 대피 시나리오를 제시할 수 있는 기초자료를 제공할 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.360-360
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• 2020

조립식 빗물침투형 저류블록은 우수유출 저감시설로, 황토 및 친환경 무기질 결합재를 이용하여 제작한 고강도 투수성 블록의 적층 및 요철에 의한 끼움식 조립에 의해 형성된 공간에 빗물을 저류하고, 저장된 빗물은 시간이 지남에 따라 지반으로 침투시키는 우수유출 저감용 빗물관리시설로, 집중강우 시 유출수가 발생하는 해당지역에 분산식으로 설치하여 국지적 호우 발생에 대처할 수 있으며, 지속적인 침투를 통한 지하수위 확보 및 가뭄현상의 저감은 물론, 미기후 조성과 건전한 물순환 구조 형성에 이바지하는 빗물관리기술이다. 본 기술은 집중형 대규모 빗물저류조의 적용상의 문제점과 단순저류의 한계성을 극복하고, 기존 침투시설의 낮은 침투능을 증대시키고자 저류기능과 침투기능을 동시에 확보하여 집중호우시 빠른 침투저류능을 향상시킨 조립식 빗물침투형 저류시설이다. 보다 구체적으로는 집중강우에 대한 방재적 측면과 함께 가뭄으로 발생하는 지하수위 저하 등에 친환경적으로 대응하기 위한 복합적인 빗물관리 기술로서, 빗물 유출저감과 함께 물순환 회복 및 저영향개발을 위한 각 지자체의 지침과도 부합될 수 있다. 또한, 콘크리트 제품의 환경적 문제점과 플라스틱 제품의 낮은 물성을 극복하였고, 시공 시에는 보다 현장상황에 맞게 가변적 형태로 적용이 가능한 단순조립 적층공법으로 공기단축에 탁월한 장점이 있으며, 유지관리 시에는 별도의 동력이 요구되지 않는 형태로 개발하였다. 조립식 빗물침투저류블록의 구조체를 이루는 단위 블록유닛은 투수성 소재로 제작되며, 상하부가 개방되어 있고 사각형의 내부에 힘을 받는 격벽과 전후벽이 상호 대응되는 요철로 형성되어 있으며, 단위블록 유닛 다수개가 수직수평으로 연속적으로 조립되어 규모의 제한, 형태의 제한이 없는 구조물 형성이 가능하다. 본 구조체의 저류공극율은 80%이상 확보 가능하며, 또한 블록자체의 투수율이 0.83mm/sec로서 순모래나 순자갈의 포화투수계수보다 투수율이 높아 침투저류 효율성이 높으며 시공 후 상부 토지는 자유롭게 활용 가능하다. 본 조립식 빗물 침투형 저류블록을 이용하여 저영향개발 계획, 우수유출 저감대책 수립, 빗물관리시설 계획시 기존의 시설들에 비하여 경제적, 효율적인 설계가 가능하다.