• ETRI Journal
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• v.40 no.2
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• pp.237-245
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• 2018

The Distributed Modulated Wideband Converter (DMWC) is a networking system developed from the Modulated Wideband Converter, which converts all sampling channels into sensing nodes with number variables to implement signal undersampling. When the number of sparse subbands changes, the number of nodes can be adjusted flexibly to improve the reconstruction rate. Owing to the different attenuations of distributed nodes in different locations, it is worthwhile to find out how to select the optimal sensing node as the sampling channel. This paper proposes the spectrum sensing of DMWC based on a Markov random field (MRF) to select the ideal node, which is compared to the image edge segmentation. The attenuation of the candidate nodes is estimated based on the attenuation of the neighboring nodes that have participated in the DMWC system. Theoretical analysis and numerical simulations show that neighboring attenuation plays an important role in determining the node selection, and selecting the node using MRF can avoid serious transmission attenuation. Furthermore, DMWC can greatly improve recovery performance by using a Markov random field compared with random selection.

• Korean Journal of Health Education and Promotion
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• v.17 no.1
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• pp.171-184
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• 2000

In present paper, author proposed an effective health education strategy for local health department, which was revised from the PATCH of CDC. The author suggested that an health department should follow several steps to have an effective health promotion programs in their community. First step would be community mobilization that encourage key persons and major organizations and agencies to participate in the program. The second step is collecting demographic and vital statistics in the community or for a target audience as well as social, psychological and behavioral data. Based on the data analysis, the next step is to choose a target audience and health problem(s) for the target audience in question. The fourth step is the development of health education strategy for the target audience and the health problem. The fourth step also includes selecting a proper communication channel and educational materials as well as pre- and post-testing. The final step is implementing health education programs and evaluating the process, outcome and impact of the program. Korean Institute for Health and Social Affairs(KIHASA) has developed a model for health education programs used in local health department. KIHASA can provide technical assistance and health education materials to assist local health departments in Korea.

• Advances in Energy Research
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• v.4 no.4
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• pp.285-297
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• 2016

Fundamental understanding of vanadium ion transport and the detrimental effects of cross-contamination on vanadium redox flow battery (VRFB) performance is critical for developing low-cost, robust, and highly selective proton-conducting membranes for VRFBs. The objective of this work is to examine the effect of conductivity and diffusivity, two key membrane parameters, on long-cycle performance of a VRFB at different operating conditions using a transient 2D multi-component model. This single-channel model combines the transport of vanadium ions, chemical reactions between permeated ions, and electrochemical reactions. It has been discovered that membrane selecting criterion for long cycles depends critically on current density and operating voltage range of the cell. The conducted simulation work is also designed to study the synergistic effects of the membrane properties on dynamics of VRFBs as well as to provide general guidelines for future membrane material development.

• Knowledge Management Research
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• v.16 no.4
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• pp.35-45
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• 2015

Fintech, which means the convergence of finance and information technology, becomes a hot topic in the financial sector. Through innovative activities on financial services, ICT(Information and Communication Technology) is integrated into the overall financial industry, and a new form of financial services could be expected to improve the existing financial system. On the other hand, fintech services are relatively vulnerable to security issues. Due to the process simplication and the channel fusion, the leakage of personal and financial informations, authentication bypass, phishing, and pharming are getting more concerned. In this study we investigated the security risk of fintech services in the viewpoints of service provider, technology adoption, and security policy. The possible countermeasures to reduce those risks are suggested because security is an important criterion for selecting financial services. This study basically offers quantification of the potential security risks and step-by-step control measures about business processes in the fintech services. The suggested security model includes user authentication, terminal security, payment information protection, API(Application Programming Interface) security, and abnormal transaction monitoring. This study might contribute to an understanding of the security risks and some possible measures for mitigating those risks on the practical perspective.

• Journal of KIISE:Information Networking
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• v.35 no.1
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• pp.56-66
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• 2008

Contention-based forwarding in wireless ad-hoc networks reduces transmission failure rate by selecting one receiver with good channel among multiple receivers. However, contention-based forwarding may increase transmission latency due to the collision problem caused by the simultaneous transmission among multiple receivers. In this paper, we present an analytic model that reflects the delay and collision rate of contention-based forwarding in lossy wireless links. Through the analytic model, we calculate the expected delay and progress in one-hop transmission under given wireless link model and delay model. Based on the analytic results, we observe that delay model should be adapted to wireless link model for optimal performance in contention-based forwarding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1286-1291
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• 2013

Intensive researches on multiuser-based Massive MIMO are performed to increase the spectral efficiency. Although the Massive MIMO scheme based on huge number of antennas inevitably causes hardware and computational complexity in baseband and radio frequency (RF) elements, the problem can be mitigated without serious performance degradation by limiting the number of baseband and RF elements below the number of transmit antennas of base station and opportunistically selecting transmit antennas according to channel states. Accordingly, this paper proposes a simple antenna selection scheme for multiuser-based Massive MIMO systems.

• Journal of Communications and Networks
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• v.12 no.4
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• pp.358-365
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• 2010

We develop a low complexity cooperative diversity protocol for low energy adaptive clustering hierarchy (LEACH) based wireless sensor networks. A cross layer approach is used to obtain spatial diversity in the physical layer. In this paper, a simple modification in clustering algorithm of the LEACH protocol is proposed to exploit virtual multiple-input multiple-output (MIMO) based user cooperation. In lieu of selecting a single cluster-head at network layer, we proposed M cluster-heads in each cluster to obtain a diversity order of M in long distance communication. Due to the broadcast nature of wireless transmission, cluster-heads are able to receive data from sensor nodes at the same time. This fact ensures the synchronization required to implement a virtual MIMO based space time block code (STBC) in cluster-head to sink node transmission. An analytical method to evaluate the energy consumption based on BER curve is presented. Analysis and simulation results show that proposed cooperative LEACH protocol can save a huge amount of energy over LEACH protocol with same data rate, bit error rate, delay and bandwidth requirements. Moreover, this proposal can achieve higher order diversity with improved spectral efficiency compared to other virtual MIMO based protocols.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.51-58
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• 2008

We propose a new duplex which does not require guard resources in MIMO environments. In the proposed duplex, two virtual channels in spatial domain are generated by preceding and postcoding MIMO channels, not to use guard resources in either the time or frequency domain. The capacity can be improved by properly selecting precoder and postcoder. We show the improved capacity of the proposed duplex outperforms conventional duplexes even without guard resources.

• Journal of Korean Public Health Nursing
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• v.29 no.2
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• pp.325-343
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• 2015

Purpose: This study was conducted in order to identify and describe the experiences of health care during pregnancy, birthing, and postpartum period for Vietnamese marriage immigrants. Methods: The participants were 15 Vietnamese married immigrant women who became pregnant and gave birth within the last five years. Data were collected by in-depth interview with Vietnamese women. Data were analyzed using Colaizzi's method of phenomenology. Results: Six theme clusters were extracted as follows: 'being left with no other option in loneliness and longing filled in a limited life', 'continued trials and errors amidst frustration and fear', 'silently following orders despite the quality of medical services that change with each medical care provider', 'compromise by selecting amidst confusion between the Korean way and the way at home', 'depending on family, who is the communication channel, but becoming disappointed', and 'finding the reason for existence and struggling by herself to become a mother amidst doubled confusion'. Conclusion: A program for effective empowerment of Vietnamese immigrant women should be developed. In addition multicultural family centered programs should be developed with emphasis on acceptance of women's culture, respect for her culture, and supports. Medical staffs and nurses should also improve culturally sensitive competence in order to provide care for immigrant women.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.905-911
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• 2005

We propose an efficient adaptive subcarrier selection scheme, in which the active subcarriers and their modulation and coding schemes (MCSs) are selected at the receiver, and subsequently conveyed to the transmitter using limited feedback We theoretically show that capacity maximization can be achieved by selecting subcarriers with highest signal-to-noise ratios (SNRs) and adapting the number of active subcarriers according to channel environments. Furthermore, an ordering based adaptive subcarrier selection algorithm is proposed to select the optimal active subcarriers with low complexity. Numerical results show that the proposed adaptive subcarrier selection scheme provides higher capacity than that obtained by water-filling approaches, even with limited feedback.