• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.1-10
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• 2005

In this study, accelerated pavement tester(APT) was performed on long-life asphalt pavements that can save maintenance and user costs by increasing the design life twice longer than conventional asphalt pavements. Basic material testings are first conducted on a high modulus base(HMB) mixture developed in this study. Four different pavement sections including thin and thick conventional and thin and thick HMB courses are constructed to compare the load-carrying capacities and to investigate the fatigue and rutting performances using an accelerated pavement tester. Tensile strain values at the bottom of base courses under the various loading levels are measured. The tensile strain values of the HMB sections are lower than those of the conventional sections. It is observed from the APT performed on the thin pavement sections that no significant cracks are developed up to the 180,000 cycles of a wheel load. In terms of rutting, only 3mm of rutting is developed in the thick HMB section while 5.3mm of rutting is developed in the thick conventional section at the 90,000 cycles of the wheel load. The HMB material developed in this study can be successfully used in the long-life asphalt pavements because of its excellent fatigue and rutting performances. It is estimated from a series of structural analysis that the use of the HMB material instead of the conventional base materials may reduce the asphalt thickness at least 5cm because of its better load-carrying capacity.

• Economic and Environmental Geology
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• v.39 no.4 s.179
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• pp.473-483
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• 2006

Although application of electrical methods in Korea began with observation of self potentials before World War II, the methods were developed slowly by the beginning of 1980's when a major burst of development activity took place. DC resistivity methods are applied in Korea more to geotechnical problems rather than to environmental ones unlike other developed countries. As with every other branch of technology, the evolving speed of the silicon chip and of streaming data to hard disk has revolutionized data collection and noise reduction processing. The last two decades saw major advances in data collection, processing, and interpretation of electrical data. Development of smooth-model two-dimensional (2D) resistivity inversion is one of the most visible changes to geophysical interpretation of the last 40 years and is now routinely applied to apparent resistivity data. The ability to represent resistivities in section rather than pseudosection view has revolutionized interpretation. Although calculation of sensitivities for general electromagnetic problems require numerous forward modelings, DC resistivity methods can enjoy computational efficiencies if sources and receivers occupy the same position, and previously intractable 3D inversion is now becoming available.

• Journal of the Korean Geotechnical Society
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• v.26 no.8
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• pp.15-25
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• 2010

The thin-layered sand seam in clay affects the soil behavior. Although the standard cone penetrometer (A: $10cm^2$) have been used to evaluate the thin-layered soil, the smaller diameter cone penetrometer have been commonly recommended because of the high resolution. The purpose of this study is the development and application of the Cone Resistivity Penetrometer (CRP), which detects qc, fs, and electrical resistivity at cone tip for the evaluation of thin layered soils. Two sizes of the CRP are developed for the laboratory and field test. The projected areas of CRP for the laboratory and field tests are $0.78cm^2$ (d: 1.0 cm) and $1.76cm^2$ (d: 1.5 cm), repectively. The length of friction sleeve is designed in consideration of ratio of the projected area to the friction sleeve area. The application tests are carried out by using the artificially prepared thin-layered soils in the laboratory. In addition, the field tests are conducted at the depth of 6 to 15 m in Kwangyang. In the laboratory test, the measured electrical resistivity and cone tip resistance detect the soil layers. Moreover, in the field test the CRP investigates the three thin-layered soils. This study suggests that the CRP may be a useful tool for detecting thin-layered in soft soils.

• Tunnel and Underground Space
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• v.28 no.3
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• pp.247-257
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• 2018

High-speed trains have been developed widely in many countries in order to transport large quantity of people and commodities rapidly. When a high speed train enters a tunnel, aerodynamic resistance is generated suddenly. The resistance caused from air pressure induces micro pressure wave and discomfort to passengers in a train. Therefore, a pressure relief system should be installed in a tunnel to reduce the resistance acting against the running train in a tunnel. Additionally, the shape of a grain should be streamlined in order to reduce aerodynamic resistance caused by a high-speed train. The cross-section of a tunnel also should be carefully designed to reduce discomfort of passengers. This study represents the effect of pressure relief ducts installed between two running tunnels. The pressure relief duct was integrated with a cross-passage in order to save cost and construction time. One-dimensional network numerical simulations were carried out in order to estimate the effect of pressure relief systems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.165-179
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• 2007

For the purpose of optimum design of reinforced concrete structures, pre-determined section database of column and beam are constructed and arranged in order of the resisting capacity. Then, regression equations representing the relation between section number and section resisting capacity are derived. In advance, effective optimization algorithms which search optimized solution quickly using direct search method from these database are proposed. In practice, from the fact that engineers conduct member design close to capacity optimization rather than cost optimization, both capacity and cost optimization using proposed algorithms are performed, and the review for the obtained results are followed. Moreover, the investigation for the applicability and effectiveness of the Introduced design procedure is conducted through correlation study for example structures. Because of no restriction in constructing objective functions with very simple optimization processes and fast convergence, the introduced method can effectively be used in the preliminary design stage. Especially, selected solutions from database are directly applicable in practice because these sections already satisfy all the requirements in design codes and practical restrictions.

• Journal of the Korea Convergence Society
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• v.5 no.2
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• pp.19-23
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• 2014

In this study, the air resistance is studied by using flow analysis near automotive body due to the its shape. Flow velocities of airs entering into inlet plane are two kinds of 70 km/h and 100 km/h. Air resistance in case of high speed driving(100 km/h) becomes higher than regular speed driving(70 km/h) and the resistance in case of the car with wider cross section at front side becomes higher than narrower cross section. By using this analysis result, the shape of automotive body can be effectively designed in order to reduce the air resistance.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.234-239
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• 2016

본 논문에서는 흔히 볼 수 있는 전봇대가 속이 꽉 차있다는 점에서 문제제기를 시작하였다. 전봇대를 설계 할 때에 속을 꽉 채우는 것이 과연 효율적이고 경제적인 설계인지 알아보고, 그것이 아니라면 어떤 단면으로 설계를 해야 하는지에 대해 문제접근을 하게 되었고, 결과적으로 속이 빈 파이프형 부재가 실제로 저항하는 하중은 작지만 경제적으로 보았을 때 현재의 전봇대보다 효율적이라는 결론을 낼 수 있었다. 추가적으로 본 논문에서는 수직력과 Bending moment외에 다른 힘을 생각하지 않았으므로 그런 것에 대한 충분한 연구가 있은 후에 이러한 설계가 적용되면 좋을 것이라고 본다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.376-379
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• 2009

본 논문에서는 다양한 사용목적을 가지고 물성적 특징의 변화 및 발전이 지속적으로 이루어지고 있는 고분자 유기소재의 응용범위를 중량과 기계적 강도면에서 우수한 유기전선으로 활용하기 위한 기초 연구로서 유기도전성 섬유인 아크릴-F의 전기적 특성을 분석하였다. 아크릴-F의 저항값을 길이와 단면적에 대하여 각각 6단계 또는 5단계로 변화시켜 측정하였으며, 기존의 구리전선의 저항값에 대하여 지수함수 2차항에 의한 특성비교를 수행하였다. 실험결과 아크릴-F는 일반 구리전선과 비교하여 저항값은 매우 높게 나타났지만 전선과 매우 유사한 저항 특성을 가지는 것을 확인하였다.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.1-10
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• 2012

As old concrete pavements of over 20years in age are increasing in expressways, the repair and rehabilitation of concrete pavement have become an important issue. Although asphalt overlay is widely used as an alternative to rehabilitate the old concrete pavement, problems due to infiltrated water such as reflection crack and pothole are imposing a very serious threat to its performance. This study proposes waterproof membrane as a solution to minimize the damage due to reflection crack and infiltrated water, and accelerated pavement testing was carried out for the performance comparison of composite pavement with waterproof membrane and ordinary tack coating. The experiment used water spraying to simulate rainfall, and the behavior and moisture resistance characteristics of overlay pavement were analyzed. The experimental result indicated that the strain pattern of waterproof membrane section differed from ordinary tack coating section because waterproof membrane caused the asphalt pavement and concrete pavement to move together. Additionally, since waterproof membrane minimized the infiltration of water and delayed the occurrence of reflection crack by about 70% in comparison to ordinary tack coating method. Moreover, the damage due to infiltrated water also decreased.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.119-124
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• 2008

Due to the recent development of instruments which enabled the measurements of subtle IP effect in the ground and analysis algorithms, complex resistivity (CR) method was expanding its application to various field. In this study, we applied the CR method to the test site where the ground reinforcement had been done by injecting the cement mortar for investigating the effect of ground reinforcement. For this site, resistivity monitoring and tomography survey was carried out while the ground reinforcement had been made by the grouting. From the result, the anomalous region that was shown on the result of resistivity 4D monitoring was coincident with those of phase section in the CR method, because the cement grouting material had the strong IP effects. It might be expected that the CR method should be very powerful surveying tool for the similar purpose.