• Journal of Communications and Networks
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• v.16 no.5
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• pp.523-533
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• 2014

Orthogonal frequency division multiple access (OFDMA) is a promising technique, which can provide high downlink capacity for the future wireless systems. The total capacity of OFDMA can be maximized by adaptively assigning subchannels to the user with the best gain for that subchannel, with power subsequently distributed by water-filling. In this paper, we propose the use of composite differential evolution (CoDE) algorithm to allocate the subchannels. The CoDE algorithm is population-based where a set of potential solutions evolves to approach a near-optimal solution for the problem under study. CoDE uses three trial vector generation strategies and three control parameter settings. It randomly combines them to generate trial vectors. In CoDE, three trial vectors are generated for each target vector unlike other differential evolution (DE) techniques where only a single trial vector is generated. Then the best one enters the next generation if it is better than its target vector. It is shown that the proposed method obtains higher sum capacities as compared to that obtained by previous works, with comparable computational complexity.

• The Journal of the Korea Contents Association
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• v.6 no.3
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• pp.116-124
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• 2006

Mentoring is defined as a sustained relationship between a mentor and a mentee. Through continued involvement, the mentor offers support, guidance, and assistance as the mentee faces new challenges, or works to correct earlier problems. A mentoring for cooperative learning has many merits including higher order thinking, collaborative competencies, socialization and development. In this paper, a U(Ubiquitous)-CoMM(Community of mentor & mentee) system was supposed to design an instructional learning strategy using cyber community of mentor & mentee in a ubiquitous environment. The proposed system provides participants with campus mentoring program in which they share their experience and expertise. By experimental result showed that the proposed system is effect in education about cooperative learning than existing system.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.566-570
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• 2006

웹데브(WebDAV)는 웹상의 분산 저작활동을 지원하기 위한 IETF의 표준 프로토콜이며 최근 발표된 웹데브 접근 제어 프로토콜은 웹데브 서버에 의하여 관리되는 자원과 이들의 속성에 대한 접근을 제어할 수 있는 기능을 제공한다. 이를 이용하여 협업 시스템을 구성하면 높은 수준의 그룹작업을 할 수 있을 것이다. 본 논문에서는 웹데브 접근 제어 프로토콜을 기반으로 협업작업을 하는 사용자들 간의 자료 교환이나 공유를 체계적으로 지원하는 협업 시스템인 CoSlide의 개발에 대하여 기술하다. 협업에 필요한 자원을 효과적이면서도 안전하게 관리하기 위하여 CoSlide 협업시스템에서 지원하는 작업장의 종류는 다음과 같다. 개인이 작업한 자료를 등록하고 관리할 수 있는 공개작업장, 협업시스템 서버에 소속되지 않은 사용자들이 협업에 참가하여 공동의 작업을 수행할 수 있는 공개작업장 그리고 공동의 과제를 수행하는 작업그룹을 위한 작업공간인 그룹작업장이 있다. 이러한 협업작업의 지원을 위하여 웹데브 접근 제어 프로토콜을 지원하는 웹데브 서버인 Jakarta Slide를 이용하여 CoSlide 협업시스템 서버를 구축하였으며,.Net 프레임워크 기반의 협업시스템 전용 클라이언트인 CoSlide 클라이언트를 개발하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.829-834
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• 2009

Alluvial soil is one of the most difficult grounds for tunneling works due to the insufficient ground strength and excessive ground water inflow. Dduk island in Seoul has a wide alluvium developed by two rivers, Han and Jung-Ryang. Subway tunnel of $\bigcirc\bigcirc$ line planed across Dduk island has highly poor ground conditions due to small cover and deeply developed alluvium. Moreover, much part of this tunnel is located parallel to the bridge foundations of another railway with a small horizontal distance. Original design was done in 2002 and construction has been in progress. During the construction, tunnel design has been partly changed and adjusted for the complex ground condition and the demand from related organizations. This paper intend to introduce the urban tunnel design and construction in alluvial soils. This line could be divided three sections(A, B, C) according to ground and adjacent conditions. Section A is featured by mixed tunnel faces consisted with alluvial soils and weathered or weak rocks. The feature of section B is that tunnel underpasses near the bridge foundations of another subway. Lastly, section C with a very short length is the most difficult construction conditions due to the small cover, poor ground, obstacles on and underneath ground surface.

• ETRI Journal
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• v.37 no.5
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• pp.1032-1043
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• 2015

ETRI's Co-Pilot project is aimed at the development of an automated vehicle that cooperates with a driver and interacts with other vehicles on the road while obeying traffic rules without collisions. This paper presents a core block within the Co-Pilot system; the block is named "Co-Pilot agent" and consists of several main modules, such as road map generation, decision-making, and trajectory generation. The road map generation builds road map data to provide enhanced and detailed map data. The decision-making, designed to serve situation assessment and behavior planning, evaluates a collision risk of traffic situations and determines maneuvers to follow a global path as well as to avoid collisions. The trajectory generation generates a trajectory to achieve the given maneuver by the decision-making module. The system is implemented in an open-source robot operating system to provide a reusable, hardware-independent software platform; it is then tested on a closed road with other vehicles in several scenarios similar to real road environments to verify that it works properly for cooperative driving with a driver and automated driving.

• Journal of Korea Multimedia Society
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• v.22 no.9
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• pp.1000-1010
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• 2019

Image semantic segmentation and dehazing are key tasks in the computer vision. In recent years, researches in both tasks have achieved substantial improvements in performance with the development of Convolutional Neural Network (CNN). However, most of the previous works for semantic segmentation assume the images are captured in clear weather and show degraded performance under hazy images with low contrast and faded color. Meanwhile, dehazing aims to recover clear image given observed hazy image, which is an ill-posed problem and can be alleviated with additional information about the image. In this work, we propose a deep multi-task network for simultaneous semantic segmentation and dehazing. The proposed network takes single haze image as input and predicts dense semantic segmentation map and clear image. The visual information getting refined during the dehazing process can help the recognition task of semantic segmentation. On the other hand, semantic features obtained during the semantic segmentation process can provide cues for color priors for objects, which can help dehazing process. Experimental results demonstrate the effectiveness of the proposed multi-task approach, showing improved performance compared to the separate networks.

• Journal of Korea Multimedia Society
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• v.22 no.1
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• pp.1-9
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• 2019

Single image rain removal is a typical inverse problem which decomposes the image into a background scene and a rain streak. Recent works have witnessed a substantial progress on the task due to the development of convolutional neural network (CNN). However, existing CNN-based approaches train the network with synthetically generated training examples. These data tend to make the network bias to the synthetic scenes. In this paper, we present an unsupervised framework for removing rain streaks from real-world rainy images. We focus on the natural phenomena that static rainy scenes capture a common background but different rain streak. From this observation, we train siamese network with the real rain image pairs, which outputs identical backgrounds from the pairs. To train our network, a real rainy dataset is constructed via web-crawling. We show that our unsupervised framework outperforms the recent CNN-based approaches, which are trained by supervised manner. Experimental results demonstrate that the effectiveness of our framework on both synthetic and real-world datasets, showing improved performance over previous approaches.

• Analyses & Alternatives
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• v.7 no.2
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• pp.7-33
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• 2023

Extant literature has emphasized the role of citizen participation in creating a successful smart city. However, previous works are lacking in a systematic analysis of the specific mechanisms by which citizen participation makes a positive impact on smart city projects. We attempt to bridge the gap by focusing on the role of the living lab, a citizen-driven mechanism that has used innovative ideas, new technologies, and cooperation with various participants to address local problems. As co-creation is the common ground for smart cities and living labs in terms of citizen participation, we provide a theoretical framework in which the notion of co-creation mediates smart cities and living labs. To examine the living lab's effect of co-creation on smart cities, we conduct a comparative case study of two Northeast Asian cities: Taipei and Busan. We explore (1) the factors behind the different outcomes in these two cities, despite many similarities that might affect smart cities' effectiveness, and (2) the relationship between smart cities and living labs and how to systematically understand the interaction between the two. We find that living labs have played a key role in making Taipei's smart city projects effective and successful, which allows the city to keep showing a high level of performance. In contrast, citizens could not find channels to participate in such projects in Busan. We conclude that the living lab explains why the smart cities in Busan have been less successful than in Taipei.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.177-183
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• 2010

Bum-type $CO_2$ generators are widely used in greenhouses for the purpose of $CO_2$ supply for photosynthesis and greenhouse heating. However harmful gases included in the air might give severe effects on the plant growth. For investigating the possible emission of harmful gases from commercial bum-type $CO_2$ generators, we carried out the analysis of the harmful by-products (NO, NOx, $NO_2$, CO, and VOCs) and $CO_2$ caused by using a bum-type $CO_2$ generator in greenhouses. And the harmful by-products from different type of fuels such as kerosene, LPG, and LNG were quantified. In order to minimize the uncertainties from a $CO_2$ generator, 4 different $CO_2$ generators were utilized in four plastic greenhouses and a glasshouse located at different places during the experimental works. The results showed that the concentration of NOx is proportional to $CO_2$ concentration. Levels of harmful gases in the most of greenhouses, where the new bum-type $CO_2$ generators were installed, were lower than 1.0 ppm when $CO_2$ concentration was set at 1,000 ppm. In case of LNG combustion, the concentration of CO reached out up to 300 ppm and pre-treatment for CO reduction, such as the adsorption process, would be inevitable to abate the adverse effects on plant growth.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.4
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• pp.318-326
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• 2016

Two phosphate solubilizing bacteria, Pantoea rodasii PSB-11and Enterobacter aerogenes PSB-12, were isolated from button mushroom compost and employed to assess their synergistic effect in liquid medium and on growth of green gram plants by single and co-inoculation of the strains. Co-inoculation of two strains was found to release the highest content of soluble phosphorus ($521{\mu}g\;ml^{-1}$) into the medium, followed by single inoculation of Pantoea strain ($485{\mu}g\;ml^{-1}$) and Enterobacter strain ($470{\mu}g\;ml^{-1}$). However, there was no significant difference between single inoculation of bacterial strain and co-inoculation of two bacterial strains in terms of phosphorous release. The highest pH reduction, organic acid production and glucose consumption was observed in the E. aerogenes PSB-12 single inoculated culture medium rather than those of co-inoculation. According to the plant growth promotion bioassay, co-inoculated mung bean seedlings recorded 10.6% and 10.7% higher shoot and root growth respectively compared to the control. Therefore, in concluding, co-inoculation of the strains P. rodasii and E. aerogenes displayed better performance in stimulating plant growth than inoculation of each strain alone. However, being short assessment period of the present study, we recommend in engaging further works under field conditions in order to test the suitability of the strains to be used as bio-inoculants.