• Journal of Soil and Groundwater Environment
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• v.12 no.1
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• pp.87-96
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• 2007

Risk assessment was carried out in order to improve the remediation and management strategy on a contaminated gunnery site, where a flood control reservoir is under construction nearby. Six chemicals, including explosive chemicals and heavy metals, which were suspected to possess risk to humans by leaching events from the site were the target pollutants for the assessment. A site-specific conceptual site model was constructed based on effective, reasonable exposure pathways to avoid any overestimation of the risk. Also, conservative default values were adapted to prevent underestimation of the risk when site-specific values were not available. The risks of the six contaminants were calculated by API's Decision Support System for Exposure and Risk Assessment with several assumptions. In the crater-formed-area(Ac), the non-carcinogenic risks(i.e., HI values) of TNT(Tri-Nitro-Toluene) and Cd were slightly larger than 1, and for RDX(Royal Demolition Explosives), over 50. The total non-carcinogenic risk of the whole gunnery range calculated to a significantly high value of 62.5. Carcinogenicity of Cd was estimated to be about $10^{-3}$, while that of Pb was about $5\;{\times}\;10^{-4}$, which greatly exceeded the generally acceptable carcinogenic risk level of $10^{-4}{\sim}10^{-6}$. The risk assessment results suggest that an immediate remediation practice for both carcinogens and non-carcinogens are required before the reservoir construction. However, for more accurate risk assessment, more specific estimations on condition shifts due to the construction of the reservoir are required, and more over, the effects of the pollutants to the ecosystem is also necessary to be evaluated.

• Journal of the Korean Institute of Educational Facilities
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• v.3 no.3
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• pp.59-70
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• 1996

장안초등학교는 한국전쟁 이후인 1955년에 개교된 초등학교이다. 처음에는 8학급의 가교사시설에 18학급으로 편성되어 초기부터 시설이 양적으로 부족하였다. 또한 이 지역의 학생수 증가로 거의 매년에 걸쳐 학급수의 증가와 교실증축이 함께 이루어 졌다. 현재 건물의 건립년도를 살펴보면 1965년 6월에 처음 신관 1층 부분이 건설되어 70년대와 80년대에 걸쳐 꾸준히 증축되어 왔으며, 대지 동측의 별관은 1993년 12월에 건설된 새건물로, 학교교사 건물이 30년된 건물과 최근의 건물이 함께 공존하고 있다. 철근콘크리트 건물이 구조적으로는 100년도 견딘다 하지만 실제로는 약 30년이면 콘크리트의 산성화가 가속화되면서 구조적으로 안전하지 못하다는 학설이 인정되어, 최근 30년이 경과된 학교 건축의 재건축이 사회적 문제로 대두되고 있다. 실제로는 25년이상 경과된 건물에서도 구조적인 하자가 발생하는 예 가 많아 교육부에서는 대체로 25년이상 경과된 건물에 대하여 재건축을 실시하고 있다. 장안초등학교는 20년에서 30년 경과된 건물이 많은 부분을 차지하는 관계로 재건축이 실시되는 예이다. 아직까지 사용이 가능하다고 판단되는 건물은 본관의 남측부분의 교사(1983년 증축)과 신관의 우측부분(1985년 9월 23일 증축)과 별관(1993년 12월 14일 신축)교사동을 들수 있다. 때문에 이 부분에 대하여 철거할 것인가 혹은 그대로 사용할 것인가에 대한 의견이 있어, 최종적으로 별관은 그대로 사용하는 것을 원칙으로 하고 본관 남측부분은 가장 마지막 건설시기에 철거하고 신관 우측부분은 규모가 작아 철거하기로 하였다. 학교건축은 다른 일반건물과는 달리 교육이라는 기능을 충분히 발휘할수 있는 공간구성이 필수적이라 할수 있다. 여기서 말하는 교육이란 예전의 주입식 교육이 아니라 21세기를 바라보는 정보화 세계화를 지향하는 교육으로 학생 개개인의 창의성과 자주성을 발휘시킬수 있는 교육이라는 점에 대하여 의견은 없을 것이다. 이러한 교육이란 다양한 교육방법을 전제로 하며 하나의 학년을 하나의 학습그룹으로 생각하는 것은 중요한 출발점이 될 것이다. 한 학년의 그룹을 교대상의 기본으로하여 이러한 그룹에 대하여 일제학습, 그룹학습, 팀티칭, 개별학습이 이루어 질수 있는 공간을 제공하는 점을 본 장안초등학교 기본계획에서 출발점으로 하였다. 물론 학교전체 학생을 콘트롤할 수 있는 교육방법도 존재한다. 선진 외국의 예를 살펴보면 아동의 능력별 교육을 위하여 무학년제(Non-Grade)를 도입하는 경우도 있지만 아직 우리나라에서는 학급단위가 중요시되고 있다. 이 학급단위는 교육단위이면서 생활지도 단위이기도 하다. 이러한 점을 인식하여 학교건축의 간장 기본 단위가 되는 보통교실 계획을 보통교실과 오픈스페이스를 연속시킨 유니트로 계획하여 일제학습, 그룹학습, 팀티칭, 개별학습 등이 이루어 질수 있도록 하였다. 실제로는 36학급을 계획할 경우, 한학년의 6개 학급이 하나의 공통된 공간내에 그룹핑 되는 것이 바람직하지만(제3안의 배치에서 제안하여 보았지만 북측교실, 오픈스페이스의 통로화등의 문제점이 있었다), 그 규모가 너무 커서 3개학급을 하나의 유니트로 하였다. 물론 한학년이 동일한 층에 배치시켜 서로의 관련성을 높게 하였다. 특별교실 계획은 보통교실과의 관련성과 장래 지역개방의 역할을 고려하여 계획하여야 할 것이다. 장안 초등학교의 경우는 별관을 그대로 사용 한다는 조건이 있기 때문에 기존의 편복도 형식의 교실에서는 보통교실 계획의 어려움이 있어 특별 교실동으로 고려하였다. 때문에 지역개방에 대해서는 문제점을 안고 있다. 체육관은 기준령에는 권장시설로 되어 있지만 학교시설에 필수적인 시설이라 생각한다. 체육은 국민건강에 직결되기 때문이다. 또한 체육관 건설은 실외체육 실내체육에 대응할 뿐 아니라 학교 행사등에 유용히 사용되기 때문에 더욱 필요시설이라 할수 있겠다. 또한 지역개방을 위하여 정문 혹은 후문 가까이에 배치시키는 것은 필수적이다. 별관, 체육관, 운동장, 후문측에 12학급용의 단독건물 등의 기본적인 제약조건을 고려하여 배치하자면 자연히 교실동들이 분산되는 결과를 낳게된다. 이러한 각각의 교사동을 A동을 중심으로 구름다리로 연결하여 동선의 불편함을 해소시켰다. 주차장은 후문 가까이에 약 10정도의 주차공간이 확보가능하다. 이외에는 운동장을 사용하는 방법과 체육관의 1층부분을 필로티로 하여 그곳에 20대 정도 주차시키는 방안이 있다. 주차는 많을수록 편리는 하겠지만 제한된 대지에 모두 만족 시켜주기는 불가능하다. 공공용의 주차와 소방에 필요한 동선이 요구된다. 특히 도심주차난을 생각할 때는 차라리 적극적으로 지하주차장을 계획하는 방안이 있을 것이다. 마지막으로 현재 67학급은 초대형 규모로 초등학교 규모로는 적합하지 못하다. 장래를 고려하여 48학급에서 최종적으로 36학급으로 계획하였으나 한동안은 67학급이 그대로 유지될 것으로 보인다. 신설 초등학교가 가까운 시기에 개교될 것을 기대한다.

• Journal of Korean Society of Transportation
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• v.33 no.4
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• pp.337-347
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• 2015

Since the application of roundabouts by 2010 have been started, more than 350 roundabouts were installed in Korea. Recently the types of constructed roundabouts become various, and the intersection conditions for installing roundabouts were also various. However, there were some difficulties to install roundabouts around school zone due to safety problems. In this study, appropriate distance from adjacent signal crosswalks to roundabouts were estimated for securing pedestrian safety and operation efficiency around school zone. With the analyses, the minimum distance standard was suggested to obtain operational effectiveness of roundabout according to traffic volume, traffic flow, pedestrian green time and secures pedestrian safety and convenience. In this paper, average delay of roundabout as various length of distances between an adjacent crosswalk and a roundabout as different pedestrian signal times, traffic volumes, traffic flow rates were analyzed. Through this study, it was found that about four times of delay in a roundabout was generated if there was adjacent signal crosswalk. However if there is enough distance between an adjacent crosswalk and a roundabout, the value of increasing delay on roundabouts with adjacent a signalized crosswalk can be considerably reduced. Critical value of the distance between a roundabout and a signal crosswalk in case of roundabouts within 200-500 vehicle/hour/lane entry traffic flow, 20-40% of left turn traffic, and over 15 seconds pedestrian green time was about 50 meters. In conclusion, if there is minimum 40 meter distance from roundabouts, adjacent signal crosswalks can be installed and operated for students' safety around school zone.

• Journal of the Korea Institute of Building Construction
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• v.9 no.4
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• pp.119-129
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• 2009

Building construction trends have been changed dramatically in terms of size and mass. With the need to maximize land usage, there has been an increase in the construction of high-rise buildings. This affects not only the entire construction duration and cost, but also subsequent construction activities, such as work to increase underground facilities and in reclamation land area construction. These types of site conditions require soft ground reinforcement and the proper uplift water pressure treatment. In general, two kinds of methods have been used for uplift water pressure treatment systems. However, there have been some problems arising as the result of a lack of research and analysis on underground construction techniques, and a reliance on experiments over actual survey and analysis of site conditions. This paper focused on the problems of conventional selection procedure, by analyzing drawings and proposing a kind of modeling for a reasonable procedure. The results were applied to OO project as a sample construction case to be verified in this research. The initial plan in the case project was the Rock Anchor System. However, as there were terrible miscalculations of basic site conditions that had an extraordinary influence on the underground water level, such as the site's proximity to the Han-river, it was necessary to change the plan to include apermanent drainage system. This achieved a direct construction cost reduction \ 406,702,000 and a maximum sayings of 4% of operational cost, based on the 50-year building Life Cycle Cost.

• Journal of the Korean GEO-environmental Society
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• v.10 no.4
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• pp.49-57
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• 2009

The governmental investment to SOC facilities currently has increasedthe construction of new roads and the consistent extension of already-existing roads or the line-shape revision of those roads. As a result, the road cut slopes have been increasingrapidly. Unfortunately, human-life damages and property damages frequently occur due to the rockfall and the landslide every year. To reduce those damages, many studies have been performed. The present regulation regarding rockfall protection facilities follows the "Guide for Installation and Management of Road Safety Facilities" issued by MLTM (the Ministry of Land, Transport, and Maritime Affairs) that indicates the standard size of facilities and energy absorbing efficiencies. Most domestic road slopes use standardized rockfall protection facilities based on the regulation. However, there have been doubted about the effectiveness of rockfall protection facilities and the damages caused by rockfalls havebeen increasedevery year. Thus, it seems that relevant studies are necessary on the rockfall protection net being capable of supporting rockfall energies. Accordingly, this study reviews previous literature to investigate the function and the feature of rockfall protection nets and analyzetheir limitations by each type. After that, by using the pullout test device for a rockfall protection net, an experiment on the PVC coating net and the expanded metal is performed under the exact same condition. Finally, the features of the Expended metal is explained with the comparison analysises of load-variation and the confirmation of damaged forms. As a result, there have been founded the problemsof net breaking down and not being able to support due to PVC coating net's material property of disintegration. On the other hand, the Expanded Metal might be expected as a substituteof rockfall protection net according to its capability of support and integration.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.961-964
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• 2008

There are researches in progress on ensuring the safety of the high impact concrete in case of fire which is a current rising social problem and this research institute also developed PFB technology, the explosion preventing technology. PFB technology is to apply POSCO E&C Fire Board, a fireproof board, with an adhesive agent on the construction site, and this technology passed 3-hour fireproof test and this technology was proven from a previous research that the temperature of main root is maintained under $200^{\circ}C$. Therefore, tests on basic contents was performed in this research before the actual construction, with a full scale of wooden prototype to apply PFB technology to actual construction sites and the tests were done on the workability of fireproof board, the adhesive power, the resistance against imprint of wooden nail, the heat conductivity and etc. As the results of these tests, PFB technology was proven to have an excellent workability at a construction site and to be easy for processing and also, this technology was proven to have a great resisting power against imprint of wooden nail. Therefore, this research has confirmed that PFB technology has no problem to be applied on a construction site.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.749-760
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• 2017

Recently, the proportion of tunnel structures in roads and railways has increased rapidly. Along with this trend, the rate of occurrence of cracks and dropouts in concrete lining of tunnel structures is increasing. Generally, maintenance of such concrete lining is normalized and managed as the core of maintenance work in tunnel maintenance. However, the maintenance of the tunnel pavement is important in securing driver in the tunnel. In the design of tunnels, the underground condition of the tunnel is designed to be in good rock condition, so there have not been many cases of cracks in the tunnel pavement in the past. Recently, the construction of tunnel structures has been rapidly increased, and the length of the tunnels has become longer.Tunnel pavement installed in these ground conditions is increasing the occurrence of cracks in the pavement due to decrease of bearing capacity of the pavement after a long time. In this study, FWD and GPR were conducted to analyze the types of cracks and the reduction of bearing capacity in the tunnel.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.262-269
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• 2016

Subway station scales are determined by peak predictions. In this study, the purpose behind the installation of a subway is public transportation convenience and public interest, but economic validity is also important. By proving that the scale of the station is excessive with regard to the target station size for Seoul subway Line 5-8, a reasonable plan. can be sought. According to station installation standards, the area of the station under investigation here is out of the service levels by six stages (A~F), and it must be four or more levels (D). The Actual level for the B level is a two-step design. The Actual ratio for over- Peak predictions is only 17.8% on average. The results of measurements of the excess area and determination of the excessive costs were analyzed by subdividing the area and by calculating it based on the B level, finding that it is possible to provide benefits for customers only in the current design, with an area ratio of 16.3%. Given the weight, it was estimated that current conditions can meet the needs of only 18.6% of the current area. Simplifying the scale calculation method of the station, it is convenient, safe, and advantageous to move citizens only if the scale can be streamlined. Then, with a reduced initial investment, maintenance costs during the operation can be reduced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.699-707
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• 2008

For most structural evaluation of bridge integrity, it is very important to measure the geometric profile, which is a major factor representing the global behavior of civil structures, especially bridges. In the past, because of the lack of appropriate methods to measure the deflection profile of bridges on site, the measurement of deflection has been restricted to just a few discrete points along the bridge, and the measuring points have been limited to the locations installed with displacement transducers. Thus, some methods for predicting the static deflection by using fiber optic strain sensors has been applied to simply supported bridges. In this study, a method of estimating the static deflection profile by using strains measured from suspension bridges was proposed. Based on the classical deflection theory of suspension bridges, an equation of deflection profile was derived and applied to obtain the actual deflection profile on Namhae suspension bridge. Field load tests were carried out to measure strains from FBG strain sensors attached inside the stiffening girder of the bridge. The predicted deflection profiles were compared with both precise surveying data and numerical analysis results. Thus, it is found that the equation of predicting the deflection profiles proposed in this study could be applicable to suspension bridges and the FBG strain sensors could be reliable on acquiring the strain data from bridges on site.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.47-58
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• 2024

This study were conduced experimentally to analyze the heat-generating performance, flexural strength, and microstructure of conductive mortar mixed with micro steel fiber and multi-wall carbon nanotube (MWCNT). In the conductive mortar heat-generating performance and flexural strength tests, the mixing concentration of MWCNT was selected as 0.0wt%, 0.5wt%, and 1.0wt% relative to the weight of cement, and micro steel fibers were mixed at 2.0vol% relative to the volume. The performance experiments were conducted with various applied voltages (DC 10V, 30V, 60V) and different electrode spacings (40 mm, 120 mm) as parameters, and the flexural strength was measured at the curing age of 28 days and compared and analyzed with the normal mortar. Furthermore, the surface shape and microstructure of conductive mortar were analyzed using a field emission scanning electron microscope (FE-SEM). The results showed that the heat-generating performance improved as the mixing concentration of MWCNT and the applied voltage increased, and it further improved as the electrode spacing became narrower. However, even if the mixing concentration of MWCNT was added up to 1.0 wt%, the heat-generating performance was not significantly improved. As a result of the flexural strength test, the average flexural strength of all specimens except the PM specimen and the MWCNT mixed specimens was 4.5 MPa or more, showing high flexural strength due to the incorporation of micro steel fibers. Through FE-SEM image analysis, Through FE-SEM image analysis, it was confirmed that a conductive network was formed between micro steel fibers and MWCNT particles in the cement matrix.