• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.36-41
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• 2016

Visible Light Communication (VLC) using Light Emitting Diodes (LEDs) within the existing lighting infrastructure can reduce the implementation cost and may gain higher throughput than radio frequency (RF) or Infrared (IR) based wireless systems. Current indoor VLC systems may suffer from poor downlink resource allocation problems and small system throughput. To address these two issues, we propose an algorithm called a conflict graph scheduling (CGS) algorithm, including a conflict graph and a scheme that is based on the conflict graph. The conflict graph can ensure that users are able to transmit data without interference. The scheme considers the user fairness and system throughput, so that they both can get optimum values. Simulation results show that the proposed algorithm can guarantee significant improvement of system throughput under the premise of fairness.

• Journal of Family Resource Management and Policy Review
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• v.12 no.1
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• pp.41-55
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• 2008

The purpose of this study was to clarify variables affecting time management practice and the relationship between the practice and academic achievement of middle school students. Questionnaires including a time management scale were used for this study and the survey data were taken from 352 middle school students in Seoul and Gyeonggi-do. The statistical methods for the analysis were frequency, percentage, average, t-test, ANOVA and Pearson's correlation. The variables affecting student time management were gender, their standard of living, parental educational level and parental occupation. Religion and residential area were indicated as variables affecting several subscales of time management but the academic year of student had no effect on student time management behavior. The relationship between time management and the academic achievement of middle school students was slightly positive. Developing programs for time management in the field of family resource management is also necessary.

• Journal of electromagnetic engineering and science
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• v.15 no.1
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• pp.14-19
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• 2015

In multicellular wireless networks, intercell interference limits system performance, especially cell edge user performance. One promising approach to solve this problem is the intercell interference coordination (ICIC) scheme. In this paper, we propose a new ICIC scheme based on a resource partitioning approach to enhance cell edge user performance in a wireless multicellular system. The most important feature of the proposed scheme is that the algorithm is performed at each base station in a distributed manner and therefore minimizes the required information exchange between neighboring base stations. The proposed scheme has benefits in a practical environment where the traffic load distribution is not uniform among base stations and the backhaul capacity between the base stations is limited.

• Journal of Communications and Networks
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• v.18 no.5
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• pp.773-783
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• 2016

Both coordinated multi-point transmission and frequency reuse are effective approaches to mitigate inter-cell interference and improve network coverage. The motivation of this work is to explore the manner to effectively utilize the spectrum resource by reasonably combining cooperation and frequency reuse. The $Mat{\acute{e}}rn$ cluster process, which is appropriate to model networks with hot spots, is used to model the spatial distribution of base stations. Two cooperative mechanisms, coherent and non-coherent joint transmission (JT), are analyzed and compared. We also evaluate the effect of multiple antennas and imperfect channel state information. The simulation reveals that the proposed approach to combine cooperation and frequency reuse is effective to improve the network coverage for users located at both the center and the boundary of the cooperative region.

• Journal of the military operations research society of Korea
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• v.26 no.1
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• pp.56-69
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• 2000

A frequency assignment problem on time division duplex system is considered. Republic of Korea Army (ROKA) has been establishing an infrastructure of tactical communication (SPIDER) system for next generation and it will be a core network structure of system. VHF system is the backbone network of SPIDER, that performs transmission of data such as voice, text and images. So, it is a significant problem finding the frequency assignment with no interference under very restricted resource environment. With a given arbitrary configuration of communications network, we find a feasible solution that guarantees communication without interference between sites and relay stations. We formulate a frequency assignment problem as an Integer Programming model, which has NP-hard complexity. To find the assignment results within a reasonable time, we take a genetic algorithm approach which represents the solution structure with available frequency order, and develop a genetic operation strategies. Computational result shows that the network configuration of SPIDER can be solved efficiently within a very short time.

• Journal of Family Resource Management and Policy Review
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• v.22 no.1
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• pp.23-37
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• 2018

This study aimed to investigate resource transfer for baby boomers' adult children and related factors pertaining to baby boomers' later-life preparation. This study was conducted in 2016 using written questionnaires completed by 405 baby boomers residing in Seoul and metropolitan cities in South Korea. The data were analyzed using IBM SPSS Statistics 23.0 and the following statistical methods: frequency, percentiles, the mean, standard deviation, a t-test, one-way ANOVA, Cronbach's alpha, and hierarchical multiple linear regression analysis. Baby boomers' average level of later-life preparation was found to be 3.45/5, a relatively rational score. Baby boomers tended to transfer more resource from their adult children when they had many adult children, were more satisfied with their romantic relationship. Baby boomers' level of later-life preparation was higher when there was lesser resource transfer of their adult children. The greatest influential variables pertaining to the respondents' later-life preparation were their family's income, children's marital status, satisfaction with their romantic relationship, and level of transfer from their adult children. It was concluded that baby boomers have insufficient later-life preparation in terms of finances due to their need to support their adult children; thus, nation-wide practical programs are needed to prepare baby boomers for a happy life.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.414-420
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• 2009

In this paper, we investigate throughput performance of OFDMA-based relay systems according to the "sub-cell coverage configuration" of the base station (RS) and the relay station (RS). RS is exploited for improved quality of the received signal with a tradeoff of additional radio resource consumption which may result in degradation of the throughput performance of the system. Therefore, "radio resource reuse" may be necessary for high performance in relay systems. However, it also causes system performance degradation since resource reuse between RSs incurs channel interference. Therefore, effective resource reuse also should be considered for "high throughput coverage configuration" when relays are employed. We relate the resource reuse patterns of neighboring RSs to sub-cell coverage configuration. We determine the sub-cell coverage of the system depending on the ratio of received signal-interference-noise-ratio (SINR) of the mobile station (MS) from the BS and RS, respectively. Simulations illustrate the throughput performance as the function of SINR ratio, and it has different optimal point depending on the resource reuse patterns. Therefore, the "resource reuse pattern" and the "effective sub-cell coverage configuration" should be considered together for the high throughput performance of the relay system.

• Korean Security Journal
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• no.54
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• pp.181-202
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• 2018

This study was conducted to investigate the effect of strategic human resource management on job stress and occupational commitment of security workers. A sample of 188 persons was extracted using the SPSS 18.0 program as a significant sampling method for the security worker. Frequency analysis, correlation analysis, and multiple regression analysis were conducted according to the purpose of the data, and the following conclusions were drawn. First, strategic human resource management has a significant effect on job stress. Second, strategic human resource management has a significant impact on occupation. Third, job stress had a significant effect on occupation commitment. That is, two factors of strategic human resource management and job stress play a decisive role in occupation commitment, and job stress plays an important role as a parameter. In conclusion, if we select the factors of strategic human resource management needed for each organization and develop new methods and competitiveness, it will be very helpful for qualitative growth of security industry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1440-1442
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• 2016

As long term evolution (LTE) is the most widely deployed broadband communication technology so far, efforts are being made to develop LTE-based mission critical public safety (PS) communication systems. In this paper, we propose a device-to-device (D2D) discovery-based radio resource acquisition scheme to support the LTE D2D communication to PS systems and the realization of resource forwarding for user equipments in emergency area.

• The KIPS Transactions:PartC
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• v.8C no.1
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• pp.41-50
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• 2001

With growth of Internet, real time multimedia application services require guarantee of QoS (Quality of Service). However, the existing Internet based on best-effort service is not enough to support those services, so MARS model to support IP multicast over ATM networks and RSVP to provide heterogeneous QoS by resource reservation scheme are proposed. As a simulation result, it is proved that processing delay of MARS is increased and success of resource reservation is decreased as a number of QoS change request of a receiver is increased. Therefore, it is important to provide heterogeneous QoS that distribute a load of MARS caused by convergence of messages and efficiently manage the resource of network as to find out scale of receivers and frequency of QoS change request.