• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1036-1039
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• 2005

하상유지시설의 하류에 설치되는 바닥보호공은 국내의 경우 일반적으로 사석(riprap)이나 돌망태(gabion mattress) 등을 이용하여 시공되고 있으며, 바닥보호공에 사용되는 재료는 유속에 따라 적절한 입경의 재료를 결정하여 사용하게 된다. 1970년대 중반부터 적절한 하상보호공 재료를 결정하기 위한 연구는 사석, 돌망태, 콘크리트 보호 블록 등에 대하여 순차적으로 이루어져 왔다, 초기 연구는 주로 사석에 대해서 이루어졌으며, 중량과 유속 관계를 이용하여 사석 입경 결정 공식을 제안하였으며, 점차 수심 및 하상 경사, 난류 강도 등을 고려하여 재료 입경 결정 공식을 정밀화시켜왔다. 공식에 난류 강도를 고려하기 시작하면서, 단순한 하상보호공 재료를 결정하기 위해서 제안되었던 공식들은 하천 구조물 하류에 설치되는 바닥보호공으로 관심의 대상이 옮겨가기 시작하였다. 기존의 공식들이 일반적인 평탄한 하상보호공으로부터 구조물 하류의 바닥보호공 까지 그 적용이 확장되었던 반면에, Escarameia와 May는 연구의 대상을 수리구조물 하류의 강한 난류 흐름이 발생하는 구간으로 범위를 한정하여 연구를 진행하였으며, Izbash 형태의 식을 기초로 하여, 난류 강도가 주요 변수가 되는 입경 결정 공식을 제안하였다. 본 연구에서는 Escarameia와 May의 연구 결과를 기초로 하여, 국내 하상유지시설 하류에 설치되는 사석 바닥보호공 재료의 입경을 결정하기 위한 실험을 수행하였다. 하천설계기준을 만족하는 실험용 보를 설치한 후 유량 및 실험에 사용된 사석의 입경을 변화시키면서, 유속을 측정하여, 입경별 한계 유속(threshold velocity)의 상관관계를 분석하였다. 실험 결과, Escarameia와 May가 제안한 공식을 더 확장하여 적용할 수 있는 실험 공식으로 개선하였으며 다양한 조건에 대한 실험을 수행하여 보다 정밀한 공식으로 개선할 수 있었다.$10,924m^3/s$ 및 $10,075m^3/s$로서 실험 I의 $2,757m^3/s$에 비해 통수능이 많이 개선되었음을 알 수 있다.함을 알 수 있다. 상수관로 설계 기준에서는 관로내 수압을 $1.5\~4.0kg/cm^2$으로 나타내고 있는데 $6kg/cm^2$보다 과수압을 나타내는 경우가 $100\%$로 밸브를 개방하였을 때보다 $60\%,\;80\%$ 개방하였을 때가 더 빈번히 발생하고 있으므로 대상지역의 밸브 개폐는 $100\%$ 개방하는 것이 선계기준에 적합한 것으로 나타났다. 밸브 개폐에 따른 수압 변화를 모의한 결과 밸브 개폐도를 적절히 유지하여 필요수량의 확보 및 누수방지대책에 활용할 수 있을 것으로 판단된다.8R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며 $10\% 경사일 때를 기준으로 $Ro(mm)=Ro_{10}{\times}0.797{\times}e^{-0.021s(\%)}$로 나타났다.천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러나 진단 즉시 직접 좌관상동맥-대동맥 이식술로 수술적 교정을 해줌으로써 좋은 성적을 기대할 수 있음을 보여주었다.특히 교사들이 중요하게 인식하는 해방적 행동에 대한 목표를 강조하여 적용할 필요가 있음을 시사하고 있다.교하여 유의한 차이가 관찰되지 않았다. 또한 HSP 환자군에서도

• The Journal of Engineering Geology
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• v.21 no.3
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• pp.239-246
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• 2011

Upon encountering weathering soil at a construction site, it may be necessary to change the design and construction plans for geotechnical structures. When weathering soil is exposed to air, the weathering process proceeds rapidly, resulting in significant damage to geotechnical structures, particle defects, and an increase in moisture sensitivity. The management of weathering-soil compaction is challenging. Because the engineering properties of weathering-soils vary regionally, it is important to report the result of research into the regional characteristics of such soils. At two locations of granite gneiss in the Gansung area of Gangwon-do, geological studies were performed at 22 and 8 sites, respectively. At each site, test samples were collected for analysis by XRD and to measure particle size, consistency, and compaction. To evaluate the suitability of the material for road subgrade, we examined the interrelationship between CBR value and the uniformity coefficient, the 200 sieve passing ratio and the aggregate ${\geq}$ 2 mm) content. We found that for the weathered granite soil, aggregate sized > 2 mm has a significant effect on the CBR value. In addition, the mixing of aggregate sized > 2 mm with sub-quality soil improves the soil condition.

• International Journal of Highway Engineering
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• v.20 no.3
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• pp.1-9
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• 2018

PURPOSES : In order to evaluate a crack resistance at cold joint, sealing tape was adopted to apply at cold joint instead of typical tack coat material(RSC-4). The sealing tape was made by hot sealing material. The crack resistance as function of environmental and traffic loading was measured with visual observation. METHODS : In this study, the crack resistance was evaluated as function of environmental and traffic loading. The freeze-thaw method was adopted for environmental loading of asphalt pavement. condition. The damage of cold joint under freeze-thaw action is initiated by ice expansion load and accelerated by the interfacial damage between new and old asphalt pavement. The traffic loading was applied with wheel tracking machine on the cold joint area of the asphalt pavement for 3 hours at $25^{\circ}C$. The evaluation of crack resistance was measured with visual observation. The freeze-thaw results shows that the sealing tape was significantly increased the crack resistance based on. RESULTS : To estimate the crack resistance at cold joint area due to the environmental loading, the Freeze-thaw test was conducted by exposing the product to freezing temperature(approximately $-18^{\circ}C$) for 24 hours, and then allowing it to thaw at $60^{\circ}C$ for 24 hours. The tack coat material(RSC-4) was debonded after 21 cycles of the Freeze-thaw test. The first crack was observed after 14 freeze-thaw cycle with RSC-4 material. But, the sealing tape was not debonded after 24 cycle test. Also, the sealing tape shows the better performance of the crack resistance under the traffic loading with wheel track test. The crack was generated the under traffic loading with RSC-4(tack coating), however, the crack was not shown with sealing tape. It indicates that the sealing tape has a strong resistance of tensile stress due to traffic loading. CONCLUSIONS :Based on limited laboratory test result, a performance of crack resistance using the sealing tape is better than that of general tack coat material(RSC-4). It means that the sealing tape is possible to extend a pavement service life because the crack, one of the main pavement distresses, will be delayed.

• Environmental and Resource Economics Review
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• v.21 no.4
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• pp.999-1024
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• 2012

The Purpose of this study was to assess the willingness to pay(WTP) for the new road construction plan(slip road of urban highway which was advertising extensively to reduce the time to the core of metropolitan area) on housing prices using contingent valuation method(CVM). And this study was an empirical study which was based on the consciousness of residents whose apartment was within the Suwon Si's new plan of 47th road construction zone. In this study, it was revealed that the resident's WTP for the plan of new road construction which was built on the neighborhood of apartment was within the 10 percent of housing prices that was similar to the standard declared price of MLTM(Ministry of Land, Transport and Maritime Affairs). And also revealed that the difference of sale prices of real estate company was 24 percent. The statistical assessment results show that both the resident's characteristic variables such as gender, incomes, size of apartment and the accessability variables such as distance to parks, schools, department stores, living facilities were positive effects on the prices of apartments significantly. Finally, the house has depreciated than that of MLTM and WTO since torpedoed the road construction plan. These results imply that, we have to take capital appreciation of the property into account due to road construction since the accessibility was very significantly positive internal effects on the apartment housing prices.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.47-47
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• 2011

에너지자원이 부족하여 에너지 해외의존도가 약 80% 이상인 우리나라의 특성상 에너지 해외의존도를 경감시키고 에너지부족 상황을 안정시키기 위하여 국내의 부존에너지를 최대한 활용하는 것이 필요하다. 또한 지구온난화에 대처하는 범세계적인 규제에 대비하기 위하여, 청정에너지를 적극 개발하여 에너지자립도를 향상시켜야 한다. 신재생에너지 중 하나인 소수력은 친환경적인 청정에너지 중 하나로 다른 대체 에너지원에 비해 높은 에너지 밀도를 가지고 있어 개발 가치가 큰 부존자원으로 평가되고 있다. 그리고 소수력은 여러측면의 사회적 환경적 이점으로 최근에는 선진국에서도 매우 큰 관심을 끌고 있으며, 에너지 자원이 빈약하여 대부분 석유수입에 의존하는 우리나라는 지역에너지로 소수력을 적극 개발하여야 한다. 소수력 부존량이 풍부한 우리나라는 1982년에 소수력 개발 활성화 방안이 공표되면서부터 정부주도 하에 소수력 발전소 건설에 관한 연구를 적극적으로 지원하게 되었다. 대수력과 비교하여 소수력의 장점으로는 비교적 짧은 계획 및 시공기간, 낮은 투자비용, 개인이나 기업을 통한 투자참여, 주위 인력이나 자재를 이용한 쉬운 설치, 적은 환경적인 피해 등이 있다. 이와 같이 청정에너지 중 하나인 소수력의 개발과 활용을 위하여 IT 기술을 접목한 다양한 응용시스템 구축이 진행되고 있다. 특히, 한국에너지기술연구원에서는 신재생에너지 개발 및 보급 확대를 목표로 2006년에 신재생에너지 자원지도시스템을 구축하였으며, 이를 웹상에서 제공하고 있다. 소수력 발전시설의 적극적인 활용을 위해서는 초기설계시 장기유출 특성분석을 통해 해당유역의 수자원을 최대로 활용하고, 지형적인 요소를 이용하여 전기의 생산이 최대가 되도록 하는 최적설계가 이루어 져야 한다. 따라서 본 연구에서는 소수력 발전시설의 최적설계를 위해 한강수계 258개 표준유역 중 섬강합류점에 대하여 자원지도를 활용하여 연평균유량을 추정한 후 소수력 자원량을 산정하였고, 그 결과로 시설용량과 연간전기생산량은 각각 1,633kW, 6,224MWh로 산정되었다. 또한 유출량의 미계측 유역에서의 소수력 발전성능을 예측하기 위한 방법으로 Weibull 분포의 특성화 방법을 선택하여 그 적용성을 검토하였다. 섬강합류점 표준유역 내에 위치하고 있는 목계관측소, 앙성관측소에서의 10개년(1999~2008) 강우자료를 바탕으로 유황곡선을 작성하여 상관관계분석을 실시한 결과 목계관측소에서 0.994701, 앙성관측소에서 0.992616으로 관측치와 계산값이 상당히 유사한 것으로 나타났다.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.133-142
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• 2011

The objective of this study is to validate the number of gyrations of Superpave gyratory compactor(SGC) for compaction of hot-mix asphalt (HMA) and warm-mix asphalt(WMA) mixtures. Marshall compaction was also used for comparison purpose. The 13mm and 19mm aggregates of 1st class quality shape were used. A PG64-22 and a PG76-22 for HMA and a PG70-22 for WMA. Four compaction temperatures based on the suggested value were used for each binder using 100 gyrations for SGC and 75 blows per side for Marshall compactor. It was found that SGC compaction was somewhat better than Marshall compaction. The analysis of variance showed that two compactors were significantly different in air voids of 19mm mixtures at ${\alpha}=0.05$ level. The 13mm mixture did not show a significant statistical difference. When compacted at the temperature below a certain level, however, the compaction of two compactors were fond to be proor. Therefore, observing compaction temperature above the minimum level is important to secure proper compaction work. If the minimum temperatures were maintained, 100 gyrations, which was given for HMA of arterial road pavement by the Korean Guide, was found to be appropriate compaction, showing similar or better compaction work than 75 blows per side of Marshall compaction.

• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.55-64
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• 2009

This study is aimed to derive the optimum mix proportion of the combined self compacting concrete according to cement types (blast-furnace slag cement and belite cement) and to propose the basic data to field construction work after evaluating the quality properties. Specially, lime stone powder (LSP) as binder and viscosity agent are used in the combined self compacting concrete because slurry wall of an underground LNG storage tank should be kept stability of quality during concrete working. Replacement ratio of LSP is determined by confined water ratio test and main design factors including fine aggregate ratio ($S_r$), coarse aggregate ratio ($G_v$) and water-cement ratio (W/C) are selected. Also, quality properties including setting time, bleeding content, shortening depth and hydration heat on the optimum mix proportion of the combined self compacting concrete according to cement type are compared and analyzed. As test results, the optimum mix proportion of the combined self compacting concrete according to cement type is as followings. 1) Slag cement type-replacement ratio of LSP 13.5%, $S_r$ 47% and W/C 41%. 2) Belite cement type-replacement ratio of LSP 42.7%, Sr 43% and W/C 51%. But optimum coarse aggregate ratio is 53% regardless of cement types. Also, as test results regarding setting time, bleeding content, shortening depth and hydration heat of the combined self compacting concrete by cement type, belite cement type is most stable in the quality properties and is to apply the actual construction work.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.39-47
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• 2003

Rockbursts are mainly caused by a sudden release or the stored strain energy in the rock mass. They have been the major hazard in deep hard rock mines but rarely occur in tunnels. Due to the short history and limited information on rockbursts, the topic has rarely been studied in Korea. Some cases of rockbursts, however, have been reported during construction of a mountain tunnel for waterway. This study focuses on analyzing data on rockbursts obtained from a TBM (Tunnel Boring Machine) tunnel and suggests methods for a comprehensive understanding on rockbursts. From the analysis of the field data of rockbursts, it was found that most rockbursts mainly occurred at the section between the tunnel face and the TBM operating room, and the rock bursting phenomena lasted up to 20 days after excavation in certain areas. The data also show that the bursting spots are located all around the tunnel surface including the face, the wall, and the roof, The maximum size of bursting spots is usually less than 100cm. This study also suggests new scale systems of brittleness and uniaxial compressive strength to evaluate the possible tendency for a rockburst. These systems are scaled based on the scale system of strain energy density. In addition, with these scale systems, this research shows that there are potentially higher tendencies for rockbursts in this specific tunnel. Moreover this research suggests that properties of rock and rock mass, RMR (Rock Mass Rating) value, tunneling method, excavating speed, and depth of tunnel have a strong correlation with rockbursts.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.631-639
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• 2013

Non-linear finite element analysis for newly developed precast concrete details for beam-to-column connection which can be used in moderate seismic region was carried out in this study. Developed precast system is based on composite structure and which have steel tube in column and steel plate in beam. Improving cracking strength of joint under reversed cyclic loading, joint area was casted with ECC (Engineering Cementitious Composites). Since this newly developed precast system have complex sectional properties and newly developed material, new analysis method should be developed. Using embedded elements and models of non-linear finite element analysis program ABAQUS previously tested specimens were successfully analyzed. Analysis results show comparatively accurate and conservative prediction. Using finite element model, effect of axial load magnitude and flexural strength ratio were investigated. Developed connection have optimized performance under axial load of 10~20% of compressive strength of column. Plastic hinge was successfully developed with flexural strength ratio greater than 1.2.

• Journal of the Korea Concrete Institute
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• v.25 no.6
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• pp.601-612
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• 2013

In the construction of nuclear power plants using massive walls, the use of high-strength re-bars for shear design is necessary to enhance the constructability and economy. In this study, low-rise walls (aspect ratio of 1.0) with grade 550 MPa bars were tested under cyclic loading to investigate the shear capacity and deformation capacity. The test parameters were the grade of horizontal re-bars (550 MPa, 420 MPa), strength of concrete compressive strength (46 MPa, 70 MPa), horizontal/vertical reinforcement ratio, use of lateral confinement hoops, shape of cross section, and failure modes (shear failure before or after flexural yielding). The test results were compared with those of walls with grade 420 MPa bars and predicted strength by current design codes. The results showed that the shear strength of the walls with 550 MPa bars was comparable to that of the walls with 420 MPa bars though the safe margin slightly decreased. ACI 349 provides underestimated shear strength for the walls with 550 MPa bars. In case of the wall with flexural yielding, a large deformation capacity was achieved. This result indicates that the ACI 349 provisions can be safely applied to seismic design of the low-rise walls (aspect ratio of 1.0) with grade 550 MPa bars.