• International Area Studies Review
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• v.15 no.3
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• pp.513-532
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• 2011

Green supply chain management(GSCM) has emerged as a key approach for firms seeking to become sustainable environmentally. GSCM is a system in which the firm takes life cycle responsibility of the products through material recycling, environment-friendly production, and reverse logistics in addition to the classical operations in a supply chain. This paper endeavors to identify the relationship between the GSCM practice implementation and firms' performance among a sample of Korean manufacturing firms. Based on a literature review, eight hypotheses are put forward. First of all, a factor analysis was conducted to derive groupings of GSCM practice from the survey data which included 54 responses. Then, the first regression was conducted to examine the link between GSCM practice implementation and firms' financial performance. The result shows that green purchasing and green production are significant. The second regression was conducted to examine the impact of GSCM practice implementation on the firms' competitiveness. The result reveals that green purchasing, green production, and reverse logistics are positively signifiant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.788-794
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• 2005

In this paper, we focus on the potential of dual polarized antennas in mobile system. thus, this paper designs exact dual polarized channel with Spatial Channel Model (SCM) and investigates the performance for certain environment. Using proposed the channel model; we know estimates of the channel capacity as a function of cross polarization discrimination (XPD) and spatial fading correlation. It is important that the MIMO channel matrix consists of Kronecker product dividable spatial and polarized channel. Through the channel characteristics, we propose an algorithm for the adaptation of transmit antenna configuration to time varying propagation environments. The optimal active transmit antenna subset is determined with equal power allocated to the active transmit antennas, assuming no feedback information on types of the selected antennas. We first consider a heuristic decision strategy in which the optimal active transmit antenna subset and its system capacity are determined such that the transmission data rate is maximized among all possible types. This paper then proposes singular values decision procedure consisting of Kronecker product with spatial and polarize channel. This method of singular value decision, which the first channel environments is determined using singular values of spatial channel part which is made of environment parameters and distance between antennas. level of correlation. Then we will select antenna which have various polarization type. After spatial channel structure is decided, we contact polarization types which have considerable cases It is note that the proposed algorithms and analysis of dual polarized channel using SCM (Spatial Channel Model) optimize channel capacity and reduce the number of transmit antenna selection compare to heuristic method which has considerable 100 cases.

• The KIPS Transactions:PartD
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• v.12D no.7 s.103
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• pp.1039-1048
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• 2005

A software configuration management(SCM) is essential for processing large scale project. The scope of SCM involves each developer's work space management, software building management, and development process control as wet] as version control. In this paper we focus on what parts should be controlled systematically for the optimized software build that is an important part of the SCM. We also analyze that to increase the efficiency of software build, what kind of configuration management information should be reported. Based on the analysis, we have actually designed and implemented a new reporting system and evaluated it. The evaluation includes comparative evaluation in efficiency based on the analysis about the related functions provided by existing tools and some additional qualitative evaluation through the questionnaires from stakeholders.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.514-524
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• 2005

In optical burst switching(OBS) networks, the ingress edge router assembles packets in the same class queue into the appropriate size of burst. A burst control packet(BCP) is generated for channel reservation of corresponding data burst and sent earlier than the corresponding data burst with an offset time. Offset time is determined considering the number of hops from source to destination and the required quality of service(QoS). After offset time, the burst data is passed through tile pre-configured optical switches without any O/E/O conversion. But a failure in OBS networks may lead to the loss of bursts until the ingress nodes receive the failure indication signal. This results in a significant degradation in QoS. Therefore, in this paper, we propose a fault-tolerant node architecture based on sub-carrier multiplexing to reduce the effects of failure in OBS networks. The Performance of the proposed fault-tolerant node architecture exhibits considerable improvement as compared with the previous ones.

• Journal of Sasang Constitutional Medicine
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• v.34 no.2
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• pp.48-64
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• 2022

Objectives The purpose of this study was to review and evaluate the clinical evidence of the efficacy and safety of treatment based on Sasang constitutional medicine (SCM) for post-stroke patients by systematic review and meta-analysis. Methods Randomized controlled trials (RCTs), published in 10 electronic databases up to December 2020, were searched. For the included studies, Cochrane's risk of bias assessment was performed to analyze the methodological quality. The strength of evidence was evaluated using the grading of recommendations assessment, development, and evaluation system based on the results of analyses. All review processes were performed by two independent researchers. Results Five RCTs were finally included. All included RCTs were conducted for one month on post-stroke patients in 60-80s, four studies on Tae-Eum patients and one study on So-Yang patients. Four types of constitution-specific herbal medicine (Chungpyesagan-tang, Cheongsimsanyak-tang, Yeoldahanso-tang, and Yangkyuksanhwa-tang) and constitution-specific acupuncture therapy were identified as interventions. More than half of the included studies were evaluated as low quality due to the high-risk of bias in selection, performance, and detection. The combination of constitution-specific herbal medicine, acupuncture, and conventional treatment was more effective in improving the patients' motor impairment, dysphagia, aphasia, and depression than conventional treatment alone. No serious adverse events by SCM treatment were reported. Conclusions SCM treatment may improve the sequelae of post-stroke patients safely in combination with conventional treatment. Since the quality of clinical evidence included in this study was low, higher quality clinical evidence obtained in well-designed clinical studies will be needed.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.6
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• pp.554-562
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• 2002

This paper presents a new sensorless control scheme using simple duty signal feedback technique in DC/DC converters. The proposed Duty Feedback Control(DFC) has the characteristics that they show the same as operation performance of current mode control by using duty feedback technique without current sensor as well as present faster dynamic response performance than conventional Sensorless Current Mode(SCM) control in case that input source is perturbed by step change or DC input source includes the harmonics. Also, the proposed control scheme has good noise immunity and simple control circuits since they have one feedback loop, and can be applied to all DC/DC converters. The concept and control principles of the proposed control scheme are explained in detail and the validity of the proposed control scheme is verified through several interesting simulated and experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.7
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• pp.723-731
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• 2016

A core technological base to provide enhanced data rates required by 5G mobile wireless communications is the improved bandwidth efficiency using massive multiple-input multiple-output (MIMO) transmission. MIMO transmission requires the channel estimation using the channel state information reference signaling (CSI-RS) and appropriate beamforming, thus the design of the codebook defining proper beamforming vectors is an important issue. In this paper, we propose a multi-rank codebook based on the discrete Fourier transform (DFT) matrix, by utilizing statistical properties of the channel generated by the spatial channel model (SCM). The proposed method includes a structural change of the precoding matrix indicator (PMI) by considering the phase difference distributions between adjacent antenna elements, as well as the selected codevector characteristics of each transmission layer. Performance gain of the proposed method is evaluated and verified by making the performance comparison to the 3GPP standard codebooks adopted by Long-Term Evolution (LTE) systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1091-1097
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• 2022

In this paper, we implement the eXclusive OR-based Cast (XC) system that is a video streaming system using exclusive OR operations, and measure various performance metrics in wireless local area network (WLAN) environments. In addition, we investigate the performance improvement of the XC system considering various practical video streaming environments, while conventional studies analyzed the performance of XC through computer simulations in limited environments. To this end, we propose new control messages such as STR_REQ_MSG (SRM) that clients transmit to a video streaming server and STR_CON_MSG (SCM) that is used for the video streaming server to control the clients, and develop a new protocol by using the new control messages. According to the various measurement results using the implemented XC system, XC video streaming system can reduce the consumption of network bandwidth by 8.6% on average and up to 25% compared to the conventional video streaming system. In addition, the outage probability can be also reduced up to 76%.

• Korean Management Science Review
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• v.25 no.1
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• pp.11-27
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• 2008

Through collaboration between buyers and suppliers, their companies try to achieve their own objectives and competitive advantages. And it is known that trust between them also would influence the effects of collaboration, which would increase their performances. In this study, above three domains of constructs : trust, collaborative behavior, performance are handled. From gathering data about a mobile networks industry and building a research model, we acquire the results of the study. Through nine hypotheses, the study show the results. The end of this paper describes managerial implications for collaborative performance and SCM strategy.

• 연구논문집
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• s.28
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• pp.193-207
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• 1998

Fully dense THCN) based carbonitride ceramics were fabricated by pressureless sintering. During sintering, solid solutions were formed from the ceramic ingredients. The ceramics exhibited microvickers hardness of 1560-2050kgf/mm2, fracture toughness of 3.0-5.4 MPa $m^(1/2)$, and three point flexural strength of 645-1072 MPa. Some of the ceramics were shaped in a cutting tool, and the cutting performance was evaluated. In case of cutting SCM440 alloy steel, the ceramics showed better performance than the commercially available alumina-titanium carbide ceramic cutting tool. Considering the excellent productivity of pressureless sintering compared with other densification methods and their cutting performance, this new class of ceramics are very promising for wear resistant applications.