• International Journal of Concrete Structures and Materials
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• v.1 no.1
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• pp.75-81
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• 2007

The concrete pavement of the Seohae Highway in Korea has suffered from serious distress, only four to seven years after construction. Deterioration due to Alkali-Silica Reaction (ASR) has seldom been reported per se in Korea, because the aggregate used for the cement concrete has been considered safe against alkali-silica reaction so far. The purpose of this study is to examine the deterioration caused by an alkali-silica reaction of concrete pavement in Korea. The investigation methods included visual inspection and Automatic Road Analyzer (ARAN) analysis of surface cracks, coring for internal cracks, stereo microscopic analysis, scanning electronic microscope (SEM) analysis, and electron dispersive X-ray spectrometer (EDX) analysis. The results are presented as follows: the crack pattern of the concrete pavement in Korea was longitudinal cracking, map cracking or D-cracking. Local areas of damage were noticed four to five years after construction. The cracks started from edges or joints and spread out to slabs. The most intensive cracking was observed at the intersection of the transverse and longitudinal joints. Where cracking was the most intense, pieces of concrete and aggregate had spalled away from top surface and joint interface area. The progress of deterioration was very fast. The reaction product of alkali-silica gel was clearly identified by its generally colorless, white, or very pale yellow hue seen through a stereo optical microscopy. The typical locations of the reaction product were at the interface between aggregate and cement paste in a shape of a rim, within aggregate particles in the cracks, and in the large void in the cement paste. Most of the white products were found at interface or internal aggregates. SEM and EDX analysis confirmed that the white gel was a typical reaction product of ASR. The ASR gel in Korea mainly consisted of Silicate (Si) and Potassium (K) from the cement. The crack in the concrete pavement was caused by ASR. It seems that Korea is no longer safe from alkali-silica reaction.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.211-223
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• 2018

Mobile relay systems have been adopted by $4^{th}$ generation mobile systems as an alternative method to extend cell coverage as well as to enhance the system throughput at cell-edges. In order to achieve such performance gains, the mobile relay systems require path selection and resource allocation schemes that are specifically designed for these systems which make use of additional radio resources not needed in single-hop systems. This paper proposes an integrated path selection and resource allocation scheme for LTE-Advanced relay systems using collaborative communication. We first define the problem of maximizing the downlink throughput of LTE-Advanced relay systems using collaborative communication and transform it into a multi-dimensional multi-choice backpacking problem. The proposed Lagrange multiplier-based heuristic algorithm is then applied to derive the approximate solution to the maximization problem. It is shown through simulations that the approximate solution obtained by the proposed scheme can achieve a near-optimal performance.

• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.325-337
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• 2020

Versatile Video Coding (VVC) is a new video coding standard that is being developed by the Joint Video Experts Team of ISO/IEC/ITU-T and it has adopted various technologies including screen content coding tools. Screen contents have a feature that blocks are likely to have diagonal edges like character regions. If triangular partitioning coding is allowed for screen contents having such the feature, coding efficiency would increase. This paper proposes a intra prediction method using triangular partitioning prediction for screen content coding. Similar to the Triangular Prediction Mode of VVC that supports the triangular partitioning prediction, the proposed method derives two prediction blocks using Horizontal and Vertical modes and then it blends the predicted blocks applying masks with triangle shape to generate a final prediction block. The experimental results of the proposed method showed an average of 1.86%, 1.49%, and 1.55% coding efficiency in YUV, respectively, for VVC screen content test sequences.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.531-539
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• 2017

This paper deals with the development of bonded joints for fibre reinforced plastic (FRP) hull structures using moulding-in concept. Focus is placed on bonded in-plane connections between two adjacent panels that could form the boundaries of hull structural module. Traditional construction in FRP hull structures requires the construction of a mould, usually from steel or aluminium. In this construction the FRP materials are laid in the mould, and resin is saturated, and then the structural member is cured. This is expensive since it involves the fabrication of metal hull mould for every different hull type, which is sacrificed after the production of the FRP ship. One way of encouraging greater use of FRP in ship construction is to investigate the possible construction of FRP hull structures in a similar manner to metallic ships, that is in terms of blocks or modules. Such a manner of construction would eliminate the need for expensive hull moulds permitting greater flexibility in the construction of FRP ships. The main issue then would be the design and construction of adequate bonded connections between adjacent panels. To fulfill this object, the simplified and automated way of manufacturing joint edge shapes for bonded joints is developed, and their structural assessment is performed in both experimentally and numerically.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.129-138
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• 2020

Due to the nature of the Rosenberg Method, the patient needs to maintain posture for a certain period of time, and the joint space is observed in various forms depending on the angle of knee flexion, which causes difficulties in examination. In order to solve these problems, Image quality was evaluated in order to evaluate the usefulness of the assistive device by making the assistive device itself. SNR and CNR analysis about the presence or absence of an assistive device using the extremity phantom and the angle of the assistive device itself were not statistically significant(p < 0.05). As a result of measuring the distance between the right and left edges of the medial condyle based on the presence or absence of an assist device, and the absence of assist device (96.00±40.6 mm) and presence of an assist device (134.86±17.68 mm) were statistically significant (p <0.05). To find the aLDFA relationship about the femur and tibia, we measured the right and left aLDFA based on the presence or absence of assist device. As a result, the absence of the right-side aLDFA assist device (74.63°±4.87) and the presence of assist device (79.64°±3.65) were statistically significant (p <0.05). The absence of the left-side aLDFA assist device (76.39°±4.62) and the presence of assist device (79.64°±3.65) were statistically significant (p < 0.05). but, As a result of measuring the distance of the overlapping parts of the right and left proximal tibiofibular joint and the lateral condyle, There were no statistically significant differences between the right and left sides. In conclusion, we confirmed that we can obtain Diagnostically valuable images with a constant knee-to-knee spacing using an assist device we self-created. In addition, we could learn through aLDFA relationship between femur and tibial that the smaller the angle, the more medial condyle overlaps with JSW, We also confirmed the significance by deriving similar values on the normal range values of aLDFA using assist devices. However, it is considered necessary to pay attention to internal and external rotations in order to obtain good quality images by evaluating the distance of overlapping parts between proximal tibiofibular joint and lateral condyle.