• 한국통신학회논문지
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• 제37권8A호
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• pp.618-631
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• 2012

본 논문에서는 근접장 MIMO 전송 환경에서의 수신 신호의 향상을 위해 편파적응을 이용하였다. 중첩의 원리에 기초하여 각각의 수신 안테나에 적응화 된 송신 안테나의 가중치를 정하는 것이 이 논문의 목적이다. 편파의 원리를 이용하여 수신 안테나의 개수가 송신 안테나의 개수보다 많을 때 송신신호는 특정한 수신기로 방향성을 가질 수 있다. 수치해석적 시뮬레이션을 통하여 본 연구의 우수성을 보여주었다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제13권6호
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• pp.343-357
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• 2007

본 논문에서는 사용자에게 적응화된 콘텐츠를 서비스를 제공하기 위해 필요한 프로파일들을 효율적으로 관리하기 위한 기법들을 제안한다. 프로파일들은 사용자에게 적응화된 서비스를 제공하기 위해 사용자 관련 정보들로 구성되며 사용자 디바이스, 프로파일 저장소, 콘텐츠 적응화 서버, 콘텐츠 저장 서버간에 주기적 비주기적 또는 이벤트에 따라 교환이 가능해야 한다. 또한 프로파일들은 적응화된 콘텐츠 서비스를 위해 프로파일을 필요로 하는 콘텐츠 제공 업체들에게 제공되어야 한다. 이와 같은 기능들을 효율적으로 지원하기 위해 필요한 프로파일 관리 기술을 제안하고, 이를 지원하는 프로파일 관리 프레임워크를 설계한다. 제안된 프로파일 관리 프레임워크에서는 사용자의 다양한 정보를 이용하여 프로파일을 구성하였으며 다양한 디바이스와 플랫폼에 관계없이 프로파일 교환 및 제공을 위해 웹 서비스를 사용하였다. 또한 프로파일의 효율적인 운영을 위해 메타데이타 구성 방법, 동적 구성 방법, 가중치를 이용한 제공 방법 등을 프레임워크에 적용하였다. 성능평가 결과 프로파일 관리 기술에 제안된 기법들이 프로파일 처리에 효율적임을 나타내었다.

• 경영과학
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• 제23권1호
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• pp.43-61
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• 2006

This research is an empirical investigation into the dimensions determining the website quality of domestic online shopping malls. A research model that has been formed to find the website quality dimensions is based on DeLone and McLean's information system success model that we adapted to fit the B2C electronic commerce environment by incorporating existing research on IS service quality and website quality. The model incorporates three quality dimensions including the information quality, system quality and service quality, and an attempt was made to empirically examine the relationship between variables of these dimensions and the revisit intent. The results of the study revealed that five quality-related variables were found to importantly contribute to the user's intent to revisit a site : the information accuracy and relevancy, system reliability, ease of use, and on-line support. The paper concludes that the three quality dimensions can serve as a useful framework to evaluate the quality of online shopping mall websites in an attempt to improve the website revisit rate.

• Journal of Mechanical Science and Technology
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• 제20권4호
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• pp.447-454
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• 2006

Hydraulic actuators are important in modern industry due to high power, fast response, and high stiffness. In recent years, hybrid actuation system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. Moreover, the hybrid actuation system has dealt with the energy consumption and noise problem existed in the conventional hydraulic system. Therefore, hybrid actuator has a wide range of application fields such as plastic injection-molding and metal forming technology, where force or pressure control is the most important technology. In this paper, the solution for force control of hybrid system is presented. However, some limitations still exist such as deterioration of the performance of transient response due to the variable environment stiffness. Therefore, intelligent switching control using Learning Vector Quantization Neural Network (LVQNN) is newly proposed in this paper in order to overcome these limitations. Experiments are carried out to evaluate the effectiveness of the proposed algorithm with large variation of stiffness of external environment. In addition, it is understood that the new system has energy saving effect even though it has almost the same response as that of valve controlled system.

• 한국미생물·생명공학회지
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• 제47권4호
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• pp.473-486
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• 2019

In the aquatic environment, microorganisms are predominantly organized as biofilms. Biofilms are formed by the aggregation of microbial cells and are surrounded by a matrix of extracellular polymeric substances (EPS) secreted by the microbial cells. Biofilms are attached to various surfaces, such as the living tissues, indwelling medical devices, and piping of the industrial potable water system. Biofilms formed from a single species has been extensively studied. However, there is an increased research focus on multispecies biofilms in recent years. It is important to assess the microbial mechanisms underlying the regulation of multispecies biofilm formation to determine the drinking water microbial composition. These mechanisms contribute to the predominance of the best-adapted species in an aquatic environment. This review focuses on the interactions in the multispecies biofilms, such as coaggregation, co-metabolism, cross-species protection, jamming of quorum sensing, lateral gene transfer, synergism, and antagonism. Further, this review explores the dynamics and the factors favoring biofilm formation and pathogen transmission within the drinking water distribution systems. The understanding of the physiology and biodiversity of microbial species in the biofilm may aid in the development of novel biofilm control and drinking water disinfection processes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.290-295
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• 2005

Hydraulic actuators are important in modern industry due to high power, fast response, and high stiffness. In recent years, hybrid actuation system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. Moreover, the hybrid actuation system has dealt with the energy consumption and noise problem existed in the conventional hydraulic system. Therefore, hybrid actuator has a wide range of application fields such as plastic injection-molding and metal forming technology, where force or pressure control is the most important technology. In this paper, the solution for force control of hybrid system is presented. However, some limitations still exist such as deterioration of the performance of transient response due to the variable environment stiffness. Therefore, intelligent switching control using Learning Vector Quantization Neural Network (LVQNN) is newly proposed in this paper in order to overcome these limitations. Experiments are carried out to evaluate the effectiveness of the proposed algorithm with large variation of stiffness of external environment. In addition, it is understood that the new system has energy saving effect even though it has almost the same response as that of valve controlled system.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.623-629
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• 2010

A geographical routing protocol is typically utilized for a route selection of VANET. Even if it is conceptually well adapted into VANET, message delivery tends to be unreliable with frequent network partitions, which mainly come from the inherent characteristics such as high mobility and irregular traffic density. In this paper, we deal with a method to enable reliable message delivery with reflecting the traffic density on routing decision. By concatenating the message delivery cost of each of inbetween junction section, $1^{st}$ and $2^{nd}$ shortest paths are initially determined. When it is not possible to deliver the message on a junction on the 1st path, we utilize two novel ideas, that is, letting the message stay on the junction to find out a new relay node, and putting a replicated copy to reach via a detour path. By using the NS-2 network simulator, our method has been examined in terms of message delivery rate and delay. It shows that our method is much efficient than the other method in the low density environment, while it brings similar results in the high density environment.

• 한국농공학회논문집
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• 제59권3호
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• pp.51-62
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• 2017

Since living environment has improved, waterfront space using and clear water demand have increased. Ministry of Environment (ME) designated polluted reservoir (worse than 4th grade) as a priority management reservoir to improve water quality (better than 3rd grade) accordingly. Minstry of Agriculture, Food and Rural Affairs (MAFRA) aims reservoir water quality 4th not 3rd grade. And water quality of agricultural reservoirs was not a great interest. For this reason, there are very few water quality monitoring data. However after designating as a priority management reservoir, reservoir manager should start water quality and flow monitoring of reservoirs and inflow streams. This process makes it possible setting complex model to accurate prediction of reservoir water quality and volume. Mulwang reservoir designated as a priority management reservoir in September 2014. In this study, BASINS/WinHSPF and EFDC-WASP were used to predict effect of water quality improvement countermeasures in Mulwang reservoir. To improve water quality of Mulwang reservoir, Siheung-si and Korea Rural Community Corporation (KRCC) established water quality improvement countermeasures. However result of simulation adapting these countermeasures cannot achieve 3rd grade. So 4 additional scenarios were adapted and the result satisfied 3rd grade. This study could help to establish water quality improvement countermeasure by using complex modeling.

• 인터넷정보학회논문지
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• 제24권6호
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• pp.1-11
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• 2023

Federated learning (FL) is a ground breaking machine learning paradigm that allow smultiple participants to collaboratively train models in a cloud environment, all while maintaining the privacy of their raw data. This approach is in valuable in applications involving sensitive or geographically distributed data. However, one of the challenges in FL is dealing with heterogeneous and non-independent and identically distributed (non-IID) data across participants, which can result in suboptimal model performance compared to traditionalmachine learning methods. To tackle this, we introduce FedGCD, a novel FL algorithm that employs Graph Neural Network (GNN)-based community detection to enhance model convergence in federated settings. In our experiments, FedGCD consistently outperformed existing FL algorithms in various scenarios: for instance, in a non-IID environment, it achieved an accuracy of 0.9113, a precision of 0.8798,and an F1-Score of 0.8972. In a semi-IID setting, it demonstrated the highest accuracy at 0.9315 and an impressive F1-Score of 0.9312. We also introduce a new metric, nonIIDness, to quantitatively measure the degree of data heterogeneity. Our results indicate that FedGCD not only addresses the challenges of data heterogeneity and non-IIDness but also sets new benchmarks for FL algorithms. The community detection approach adopted in FedGCD has broader implications, suggesting that it could be adapted for other distributed machine learning scenarios, thereby improving model performance and convergence across a range of applications.

• Molecules and Cells
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• 제39권10호
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• pp.715-721
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• 2016

Plants have become physiologically adapted to a seasonally shifting environment by evolving many sensory mechanisms. Seasonal flowering is a good example of adaptation to local environmental demands and is crucial for maximizing reproductive fitness. Photoperiod and temperature are major environmental stimuli that control flowering through expression of a floral inducer, FLOWERING LOCUS T (FT) protein. Recent discoveries made using the model plant Arabidopsis thaliana have shown that the functions of photoreceptors are essential for the timing of FT gene induction, via modulation of the transcriptional activator CONSTANS (CO) at transcriptional and post-translational levels in response to seasonal variations. The activation of FT transcription by the fine-tuned CO protein enables plants to switch from vegetative growth to flowering under inductive environmental conditions. The present review briefly summarizes our current understanding of the molecular mechanisms by which the information of environmental stimuli is sensed and transduced to trigger FT induction in leaves.