• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.453-463
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• 2012

Steel-concrete composite rigid-frame bridge is a type of integral bridge having advantages in bridge maintenance and structural efficiency from eliminating expansion joints and bridge supports, the main problems in bridge maintenance. The typical steel-concrete composite rigid-frame bridge has the girder-abutment connection where a part of its steel girder is embedded in abutment for integrity. However, the detail of typical girder-abutment connection is complex and increases the construction cost, especially when a part of steel girder is embedded. Recently, a new type of bridge was proposed to compensate for the disadvantages of complex details and cost increase. The compensation are expected to improve efficiency of construction by simplifying the construction detail of the girder-abutment connection. In this study, a static load test has been carried out to examine the behavior of the girder-abutment connection using real-scale specimens. The results of the test showed that the girder-abutment connection of proposed girder bridge has sufficient flexural capacity and rebars to control concrete crack should be placed on the top of abutment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.124-135
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• 2011

The capacity of bearings installed at abutments and piers for continuous bridges is usually determined by the magnitude of the maximum vertical reaction at each support and the capacity of bearings placed at piers is higher than that at abutments. In this study, the possibility of the improved seismic performance of base-isolated continuous skew bridges was investigated by analysing the variation of the seismic behavior of them according to three arrangements of bearings. Based on the conventional arrangement of bearings(Case A), three arrangements of bearings such as Case A, Case B and Case C were selected considering the variation of the horizontal stiffness of the lead rubber bearing(LRB) installed at the pier. The seismic behavior of the total 36 skew bridges was investigated by conducting the response spectrum analysis using the hybrid response spectrum considered the effect of LRB's damping. Results of analyses show that a more desirable seismic behavior of base-isolated continuous skew bridges can be obtained by reducing the magnitude of the horizontal stiffness of LRB placed at the pier to similar to or less than that of LRB installed at abutments. The variation of LRB's stiffness at the pier brings about period elongation and the change of mode shapes of base-isolated skew bridges and results in the reduction of the total base shear, the maximum base shear at the pier and the girder stresses. Although positive effects on the seismic behavior of base-isolated skew bridges caused by the change of arrangement of bearings decreased slighty with an increase in the flexibility of the substructure, the proposed arrangements of bearings bring about the improved seismic performance of base-isolated continuous skew plate girder bridges with less than 10m height of piers.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.249-258
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• 2012

Integral and rigid frame bridges have advantages in bridge maintenance and structural efficiency by eliminating expansion joints and bridge supports. However, the detail of typical girder-abutment connection is rather complex and increases construction cost depending on construction detail. For the purpose of compensating disadvantages such as complexity and additional cost, a new type of bridge is proposed in this study, which improves the efficiency of construction by simplifying the construction detail of girder-abutment connection. The proposed bridge has the connection detail of steel girder and abutment integrated by prestressed PS bar installed in the connection. In this study, finite element analysis and fatigue load test are conducted to evaluate the fatigue capacity of the proposed girder-abutment connection. The results of the finite element analysis revealed that the possibility of the fatigue damage in the girder-abutment connection is very low. The results of the fatigue load test verified that the integrity of the girder and abutment connection is maintained after 2,000,000 cycles of fatigue loading.

• International Commerce and Information Review
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• v.18 no.3
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• pp.47-72
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• 2016

The Government of Korea has always focused on developing and maintaining a surplus on the balance of payments as a successful trade policy. The focus should now be on spatial information hiding, revealing patterns in trade activities that enable viewing trade in a more sophisticated manner. This study utilizes trade statistical data such as the United States-South Korea imports and exports from 2003 to 2015 officially released by the two countries. It allows us to analyze and extract the spatial information pertaining to the origin, transit, and destination. First, in the case of export data to the United States, the origin of the trade goods has expanded and decentralized from the metropolitan area. With regard to transit, in 2003, most of the exported goods were shipped by ocean vessels and arrived at the ports on the western coast of the United States. However, trade patterns have changed over the 12-year period and now more of that trade has moved to the southern ports of the United States. In terms of destination, California and Texas were importing goods from South Korea. With the development of the automotive industry in Georgia and Alabama, these two states also imported huge volumes of automobile parts. Second, in case of import data, most imported goods from the United States originated from California and Texas. In this case, 40% of goods were shipped by air freight and arrived at the Incheon-Seoul International Airport; most ocean freight was handled at the Port of Busan. The purpose of this study is to decompose the spatial information from the trade statistics data between Korea and the United States and to depict visualized bilateral trade structure by origin, transit, and destination.

• The Journal of the Korean bone and joint tumor society
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• v.13 no.2
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• pp.105-112
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• 2007

Purpose: Recent studies have shown increased levels of cyclooxygenase-2 (COX-2) in various human malignancies to include various bone and soft tissue tumors. However, little is known with regard to COX-2 expression patterns in chondroid tumors. Materials and Methods: Immunohistochemistry assays were performed for COX-2 in enchondromas (n=10), chondroblastomas (n=11), chondromyxoid fibromas (n=5), conventional chondrosarcomas (n=17), clear cell chondrosarcomas (n=7), and mesenchymal chondrosarcomas (n=6). Results: Among the benign chondroid tumors, chondroblastomas revealed characteristic strong positivity in 6 of 11 cases(54.5%). All enchondromas and chondromyxoid fibromas were negative except in one case. In conventional chondrosarcomas, three cases(17.6%) were strongly reactive with COX-2 and all positive cases represented grade III chondrosarcomas. Clear cell chondrosarcomas were found to be focally positive in two cases(28.5%), while all mesenchymal chondrosarcomas were negative. Conclusions: These findings suggest that COX-2 overexpression in conventional chondrosarcoma may represent an advanced histologic grade. Interestingly, expression of COX-2 in chondroblastomas could be an important factor for inducing peritumoral inflammatory changes in these specific tumors.

• Journal of the Korean Geosynthetics Society
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• v.8 no.3
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• pp.25-34
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• 2009

Determination of design parameters of composite ground including colluvial soil layer is far difficult because the maximum particle size of such a soil is remarkably large and particle distribution may vary from area to area. The stress-strain behavior of colluvial soils is in fact dependent upon the engineering characteristics at the boundary between coarse and fine materials. However, strength parameters are in general determined based on the characteristics of fine material, which causes an underestimation of such parameters. In this study, strength parameters of colluvial soil are evaluated by means of BIMROCK model curve. In addition, limit equilibrium analysis is carried out to verify the rational shear strength evaluation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1679-1687
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• 2016

Mobile robots are effectively used in industrial fields that require flexible manufacturing systems. Mobile robots have to move with mechanical loads such as product parts along the specified paths, and are usually equipped with kinematic controllers. When the loads and nonlinear frictions are too high, satisfactory control performances can not be expected with the kinematic controllers, so some dynamic controllers have been developed. Conventional dynamic controllers require the exact weights and locations of the loads; however, the loads are frequently changed and unknown so that the control performances of the conventional controllers are limited. This paper proposes an adaptive PD control method using gradient descent learning to have sufficient dynamic control performance for unknown loads. Simulation studies have been conducted for various load conditions to verify that the adaptive PD control method have much broader convergence region than the convention method.

• Journal of Periodontal and Implant Science
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• v.26 no.3
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• pp.567-577
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• 1996

탈회냉동건조골 (DFDBA)과 ePTFE막을 사용한 경우와 ePTFE만을 사용한 경우의 조직유도 재생술의 효과를 관찰하였다 . 12명의 환자에서 12개의 골내낭결손부(한 환자당 하나의 결손부)를 통상적인 치주수술 시행한 경우를 대조군(GFS)으로 , 12명의 환자에서 12개의 결손부는 ePTFE(GTR)막 만으로 , 또 다른 환자의 12개결손부는 ePTFE+DFDBA로 시행하였다. 창상안정과 감염방지를 강조한 술후계획이 사용되었다. 술후 6개월째 임상적 치유상태를 평가 하였다. 대조군에서 치주낭깊이, 부착수준, 탐침골깊이, 치은퇴축의 각각의 평균치는 $3.4{\pm}1.3mm$, $2.0{\pm}1.2mm$, $1.3{\pm}2.0mm$, $-1.7{\pm}0.8mm$, GTR 군에서는 $4.3{\pm}l.3mm$, $3.1{\pm}1.5mm$, $4.2{\pm}2.2mm$, $-11{\pm}1.4mm$ 그리고 GTR+DFDBA 군에서는 $3.4{\pm}2.1mm$, $2.4{\pm}1.9mm$, $2.6{\pm}1.6mm$, $-1.2{\pm}1.7mm$를 보였다. 대조군과 GTR+DFDBA 군의 술전 평균 치주낭깊이는 각각 $6.9{\pm}1.1$, $7.4{\pm}1.2$, $7.0{\pm}2.0mm$였다. GTR, GTR+DFDBA군에서는 뚜렸한 치주낭감소와 부착획득을 보였다(P<0.01). GTR, GTR+DFDBA 에서는 대조군에 비해 탐침골수준의 뚜렷한 향상을 보였으나(P<0.001), GTR 과 GTR+DFDBA 사이에는 뚜렷한 차이가 없었다. 이 실험결과로 골내낭 결손부에서 GTR과 GTR+DFDBA의 사용은 골형성을 제외한 임상결과 에서 대조군과 유사한 결과를 보였다.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1359-1368
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• 2013

An "admission officer system" has been introduced for the purpose of changing the paradigm from the "current admission system". This is because the current admission system mainly reflects the scholastic ability test (SAT) score regulating student selection for entering university. The admission officer system focuses on not only the students' school records but also, their potential. In addition, this system lets the university screen the students according to its own founding philosophy. One feature of the admission officer system is to cultivate men of ability by caring for the selected students consistently. Typically, students are selected by an admission officer system according to document screening which includes curriculum and non-curriculum scores, discussions, and interviews. On the other hand, the admission officer system might create a lack of objectivity in the way a student is selected because of the admission officer's own subjectivity. In this study, an algorithm in which the admission officer system can maintain the objectivity on student selection is presented. This is so that the student does not experience any disadvantage from the process of the admission officer system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.4
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• pp.255-262
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• 2016

There has been intense research on self-diagnosis systems in railway applications, since stability and reliability have become more and more significant issues. Wired sensors have been widely used in the railway vehicles, but because of the difficulty in their maintenance and accessibility, they ar not considered for self-diagnosis systems. To have a self-monitoring system, wireless data transmission and self-powered sensors are required. For this purpose, a thermoelectric energy harvesting module that can generate electricity from temperature gradient between the bogie axle box and ambient environment was introduced in this work. The temperature gradient was measured under actual operation conditions, and the behavior of the thermoelectric module with an external load resistance and booster circuits was studied. The proposed energy harvesting system can be applied for wireless sensor nodes in railroad vehicles with optimization of thermal management.