• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.38-45
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• 2020

A magnetically levitating capsule train, which runs inside the sub-vacuum tube, can reach ultra-fast speeds by dramatically reducing the aerodynamic drag and friction. The capsule train uses the superconductor electrodynamic suspension (SC-EDS) method for levitation. The SC-EDS method has advantages, such as a large levitation gap and free of gap control, which could reduce the infra-construction cost. On the other hand, disadvantages, such as the large variation of the levitation-guidance gap and small damping characteristics in levitation-guidance force, could degrade the running stability and ride comfort of the capsule train. In this study, a dynamic analytical model of a capsule train based on the SC-EDS was developed to analyze the running dynamic characteristics. First, as important factors in the capsule train dynamics, the levitation and guidance stiffness in the SC-EDS system were derived, which depend non-linearly on the velocity and gap variation. A 3D dynamic analysis model for capsule trains was developed based on the derived stiffness. Through the developed model, the effects of the different running speeds on the ride comfort were analyzed. The effects of a disturbance from infrastructure, such as the curve radius, tube sag, and connection joint difference, on the running stability of the capsule train, were also analyzed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.327-343
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• 2004

During tunnel construction, ground failures often occur due to existence of weak zones, such as faults, joints, and cavities, ahead of tunnel face. It is hard to detect effectively weak zones, which can lead underground structure to fail after excavation and before supporting, by using conventional characterization methods. In this study, an enhanced analytical method of predicting weak zones ahead of tunnel face is developed to overcome some problems in the conventional geophysical exploration methods. The analytical method is based on Coulomb's and Gauss' laws with considering the characteristics of electric fields subjected to rock mass. Using the developed method, closed form solutions are obtained to detect a spherical shaped zone and an oriented fault ahead of tunnel face respectively. The analytical results suggest that the presence of weak zones and their sizes, location, and states can be accurately predicted by combining a proper inversion process with resistance measured from several electrodes on the tunnel face. It appears that the skin depth or resistivity in rock mass is affected by the diameter of tunnel face, natural electric potential and noises induced by experimental measurement and spatial distribution of uncertain properties. The developed analytical solution is verified through experimental tests. About 1800 concrete blocks of 5cm by 5cm by 5cm in size are prepared and used to model a joint rock mass around tunnel face. Weak zones are simulated ahead of tunnel face with a material which has relatively higher conductivity than concrete blocks. Experimental results on the model test show a good agreement with analytical results.

• Journal of the Korean Geophysical Society
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• v.6 no.3
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• pp.165-177
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• 2003

The purpose of this paper is to analyze the behavior and to study the safety evaluation of the Unmun Dam located in Cheongdo-Gun of GyeongBuk Province, Korea. For this purpose, soil analyses including boring data, geophysical surveys were conducted. In this paper, especially many geophysical methods were adopted to configure out the subsurface situation of dam. Applied geophysical methods were: 1) electric resistivity survey, 2) high frequency magnetotelluric (HFMT) survey, 3) ground penetrating radar (GPR) survey, 4) seismic refraction survey, 5) seismic cross-hole tomography survey, and 6) high frequency impedance (ZHF) survey. Each of geophysical surveys were analyzed and joint analyses between geophysical surveys were also performed to deduce the more reliable subsurface information of Dam by using the features and characteristics of each geophysical survey. Since many defects, such as gravel and weathered rock blocks in the dam core, and lots of amounts of leakage, by boring analyses were found, reinforcement by compaction grouting system (CGS) has been conducted in some range of dam. Some geophysical data and data of geotechnical gauges were also used to confirm the effects of reinforcement. Electric resistivity, EM, GPR, ZHF, seismic refraction and seismic tomography surveys show that left side of dam is weak, which means the possibility of existence of gravel, rock block, water and cavities in the core of dam. This result coincides with the boring data. Especially, electric survey after reinforcement shows that even the right side of the dam has been deformed by the strong pressure during the reinforcement itself. As a conclusion, some problems in the dam found. Especially, the dam near spillway shows the high possibility of leakage. It should be pointed out that only the left side of he dam has not a leakage problem. As a whole, the dam has problems of weakness, because of unsatisfactory construction. It is strongly recommended that highly intensive monitoring is required.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.1 s.2
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• pp.15-24
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• 2003

While public institutions and privite coperations have constructed the data collecting infrastructure and commercialized it to service traffic information, inaccuracy with information, insufficiency with the public sector, overapping investment and the rest are arising from the differences of data treatment, offering method, communication protocal and the like. For these reasons, we need standardization it as a national enterprise. In this paper, we would like to present the unity management and joint method of traffic information based on the present position of system construction and national ITS standardization. At first, we presented the relation between data elements and message sets and then analyzed how message sets have been used to message sets to share traffic information so far in public institutions and private coperations like Korea freeway cooperation-ITS model city-Cheonan-Nonsan expressway, In-cheon international airport expressway-Korea freeway cooperation and Seoul metropolitan police agency-Seoul metropolitan government. As the results of analyzing message sets, it had disclosed that data transmission is impossible or a system is unchangeable because data form and each items to transmission were different from each other and its own address and link IDS were not determined yet. Also it showed these message sets did not abidy by The Draft of National ITS Standards. First of all, we proposed data basic form and elements which were form by items used in each center in common and the elements to manage traffic information suggested by Standards based on the results of analyses.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.447-454
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• 2016

In the meantime, looking at the present status of how to estimationte the quantity of rebar based on 3D BIM getting the limelight in these days, commercial BIM tools provide rebar modeling functions however it takes a vast amount of modeling time for modeling of rebar in use of that function hence there is no BIM software at present for practical use. Therefore, in this study, we organized and presented a practical rebar quantity estimationtion process in BIM-based design work-site and intended to develop a program named Rebar Automatic Arrangement Program - hereinafter called RAAP - which enables automatic rebar arrangement based on much more precise cross-sectional information of bars in column, beam, slab and wall than the one from existing 2D method under the conditions without any cross-sectional information in the initial design phase. In addition, we intended to establish rebar quantity estimationtion process in the initial design phase through interworking of modeling & quantity estimationtion functions in consideration of joint, anchoring length of BuilderHUB as a BIM software with RAAP. The results from this study are practical in developing a technology that is able to estimationte quantity with more improved reliability than the one from existing 2D-based methods with less effort when the quantity of framework is estimationted in the uncompleted state of cross-sectional design for structural members in the initial design phase of a construction project. And it is expected that it could be utilized as a basic study from which a reasonable quantity estimationtion program can be established in the initial design phase.

• Journal of Korea Port Economic Association
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• v.31 no.1
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• pp.15-36
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• 2015

The purpose of this paper is "A Study on the Establishment of Distribution and Logistics System in the unified Korea". The main conclusion of this paper are as follows : North and South Korea shall conjunctionally foster the exchange and cooperation area and operate the joint pilot project to combine distribution and logistics system. To solve the problems of the maritime affairs, Fisheries, and international logistics, the cooperative agreement between North and South Korea will be needed to protect and develop of shipping, aviation and shipbuilding industry. Unification of two Koreas must be prepared as stage by stage ; ${\cdot}$Stage1(preparation period) : initiation of peace area. ${\cdot}$Stage2(development period) : forming the exchange and cooperation area ${\cdot}$Stage3(settlement period) : establishing peace belt on border area. After the unification, two Koreas must plan and undertake the construction of the distribution and logistics infrastructures, establishment of SCM system through Network and the connection to China through railway and road Network.

• Journal of Science and Technology Studies
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• v.4 no.1 s.7
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• pp.1-30
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• 2004

In this paper, I have attempted to show how the environmental controversy surrounding the Saemangeurn Reclamation Project in Korea has been framed as narrow scientific debates. First of all, science, or specifically the Expert Review Pane, has played dual roles in the controversy. On the one hand, it has contributed to illuminating the future environmental impacts of reclamation, by so doing, to providing a momentum to reconsider the project. This has significant meaning that environmental concerns successfully checked the symbolic national project of developmental era through adopting a joint-investigation scheme that guaranteed participation of environmental groups on an equal footing with the government. On the other hand, by limiting the scope and participants of discussion, it fundamentally blocked the possibilities of public debates and deliberative decision-making with full considerations of the political, social, and cultural aspects of the controversy. I have shown that this is due to the realist belief shared by both the developers and the environmentalists in Korea that 'proper' science would disclose the truth. Environmental groups, in particular, were naive in evaluating the role of scientific expertise in the controversy and neglected the political role of the Expert Review Pane as a ritual. In opposition to the realist argument, I have shown through the analysis of the water quality debates concerning the future fresh water lakes that scientific 'facts' were not discovered but constructed through complex negotiations, conflicts, and compromises among related actors. The framing of the controversy as an experts' debate has resulted in the exclusion of an important actor from the discussion. Little attention has been paid throughout the controversy to the very people who have lived in the Saemangeum area for generations and will lose their livelihood all together soon. About 20,000 fishermen are living on the Saemangeum tidal flats.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.433-441
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• 2006

With a development of electrical technology in recent, it is possible to measure distance without direct contact to object using laser which launched at instrument and reflect from object. Furthermore, the advent of non prism total station brought the increment of application in many fields including not only road, airport, and harbors but also measurement and monitoring of structural displacement in construction fields. In this study, therefore, to evaluate accuracy of non prism total station, accuracy was analyzed by measuring certain distance which classified by both certain materials and angle of reflection. By this method, the derived values were applied to topographical survey for the efficient applicability. According to a study, result value of non prism total station was satisfBctory regardless of material when the angle of reflection was 90 degrees. RMSE increased when the angle of reflection are gradually increased to acute angle. In result of regression analysis using certain distance which classified by both materials and angles of reflection, there is relationship between distance and angle of reflection, but material has no relevance to the result value. When carrying out general topographical survey, proper application of non prism total station will go far conducting safe and prompt survey at the dangerous site such a road which have lots of traffic flow and rock joint which have high angles of inclination.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.105-114
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• 2006

A popular alternative to extend the life of aged pavement is asphalt overlay. However, it has a very serious and inherent shortcoming in deterring a reflection crack. Although joint-rehabilitation and stress-relief techniques have been applied to deter such reflection cracks in aged pavement, the techniques had a limited success only in slowing down the progress of a reflection crack. Rubblization technique rubblizes the concrete pavement slab in situ and uses the rubblized slab as the base material. Then, pavement overlay is applied to finish off the rehabilitation of aged pavement. This rubblization technique has the advantage of solving the problem of reflection cracking completely. When rubblization technique is applied, the upper layer of aged concrete pavement is rubblized between 40mm-70mm in depth. However, the lower layer is typically rubblized more than 100mm in depth. Nevertheless, it is difficult to turn the entire concrete pavement of more than 30cm in depth into rubblized aggregate of appropriate size. Thus, a simulation experiment was carried out to find the appropriate rubblized depth, which avoids the reflection cracking and still maintains the function of subbase, by varying the depth of rubblized depth in loom increments of 0cm, 10cm, and 20cm. The result indicated the optimum rubblized depth was 10cm (Lee, 2006). Additionally, a small rubblizinge equipment was developed in order to derive the rubblization technique appropriate for thick concrete pavement. This equipment was tested out on an experimental pavement, which was constructed with the same standard and specification for the road in actual use, by varying its rubblizing head shape and energy as well as the effective area of rubblization. This experiment led to a prototype equipment for rubblization of thick concrete pavement. The prototype was put into use on a highway, undergoing a test construction and monitoring afterwards. This entire process was necessary for the validation of the proposed rubblization technique.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.136-143
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• 2011

The oversized and slotted holes are frequently required for the built-up in construction sites. The foreign provisions specify the reduction of the slip load subjected to the size of bolt holes and the direction of load. There are no domestic building codes and researches on the bolt holes. Therefore, it is necessary to evaluate a change of joint strength quantitatively according to the bolt-hole size and surface condition by means of experiment. This study was conducted to evaluate the slip load subjected to the size of bolt holes, and measured on a change of clamping force of high strength bolts during 168 and 800 hours to analyze the trend of relaxation after fastening bolts. Torque shear bolts defined on KS B 2819 was used for the specimen. Test results exhibit that the variation on the slip load of the others was below 10% by contrast with the standard hole and the highest rate of relaxation was 2.66% of the initial clamping force at the case of the long-slotted hole of 2.5D.