• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1240-1243
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• 2016

In this paper, we analyze the queueing performance of cumulative distribution function (CDF)-based opportunistic scheduling over Nakagami-m Markov fading channels. We derive the formula for the average queueing delay and the queue length distribution by constructing a two-dimensional Markov chain. Using our formula, we investigate the queueing performance for various fading parameters.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.237-240
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• 2015

We derived the average bit error rate (BER) of coherent free-space optical (FSO) systems with digital binary phase shift keying (BPSK) modulations over atmospheric turbulence channels with a gamma-gamma distribution. To obtain a generalized derivation in a closed-form expression, we used special integrals and transformations of the Meijer G function. Furthermore, we numerically analyzed and simulated the average BER behavior according to the average SNR for different turbulence strengths. Simulation results are demonstrated to confirm the analytical results.

• Journal of Distribution Science
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• v.22 no.1
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• pp.115-125
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• 2024

Purpose: This study is to analyze the purchasing process and distribution management requirements for teaching materials that have important meaning in the practical field of preschool education. Research design, data and methodology: A structured questionnaire was used to survey 103 childcare staffs regarding the purchasing process and distribution managements. The collected data underwent Likert's 5-point scale analysis and keyword grouping. Additionally, ANOVA was conducted to examine the distribution management demands based on demographic characteristics. Results: The purchasing of teaching materials involved more offline channels than online, and the purchase decisions were predominantly made by principals rather than teachers. Although the purchasing process is similar to that of general businesses, there are difficulties in purchasing due to the disorganized distribution channels and limited accessibility to product information. Additionally, the management of inventory for teaching materials is challenging due to limited personnel and storage. Childcare staffs have requirements for classification systems, evaluation criteria, environments and policies related to teaching materials distribution. The need to introduce a teaching material evaluation and certification system to ensure quality was not high. Conclusions: Most of the respondents recognized that strict management and measures should be taken for the distribution of teaching materials. There were differences in the demand of teaching material distribution depending on the respondents' status, age, education, and experience.

• Journal of Distribution Science
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• v.19 no.12
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• pp.103-114
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• 2021

Purpose: This study was conducted with the goal of increasing research interest in H&B stores as a new distribution channel to identify factors influencing the revitalization of the H&B stores in Korea in distribution channels, in detail, the relationships among perceived values, satisfaction, trust, and loyalty. Research design, data and methodology: With 499 respondents, this study used exploratory factor analysis and reliability analysis to verify the reliability and validity of measured variables. Multiple regression was employed as a statistical method for the hypotheses of the study. Results: According to the results of the analysis, H&B stores are targeted by female customers in their 20s and 30s. The findings showed that four perceived values affect store satisfaction and trust. Store satisfaction and trust have positive effects on loyalty. Comparing the two variables, store satisfaction had a slightly stronger effect on loyalty than on trust. Conclusions: This study identified the store’s diverse values for the revitalization of the H&B stores need to provide to customers. The stores need to form facilities that can enhance the value of shops perceived by customers, and to establish distribution strategies that can further increase store satisfaction, trust, and loyalty to expand trading areas as multi-brand shops.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.9
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• pp.26-33
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• 1994

In this paper, the performance of the trellis coded CPFSK with the coherent detection over mobile communication channels is calculated. The characteristics of channels, including phase jitter effects and fading effects, are examined and modeled. The phase jitter channel is modeled to have a nonzero mean and a gaussian distribution. The fading channel has a Rayleigh distribution in the multipath. For the optimal decoding method(MLSE), the Viterbi algorithm is used for the trellis structure of trellis coded CPFSK. The results indicate that the trellis coded CPFSK with a small moulation indes gets more sensitive, as the index gets smaller, to the phase noise under the phase jitter channel. Using the interleaving method. It gives considerable improvements in the error rate under the fading channel.

• Journal of Distribution Research
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• v.4 no.1
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• pp.123-140
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• 1999

For more than a decade, trust and commitment have received much attention in marketing channels literature. This study investigates the effects of these two core relational dimensions on the performance of EDI-supported marketing channels. A survey of the 92 suppliers of large department stores in Korea indicates that commitment to EDI increases significantly the organizational and economic performance of EDI-supported marketing channels. Trust was found to increase EDI performance indirectly by enhancing commitment to EDI. Based on the Social Information Processing(SIP) theory the present study also explored the effects of time on trust and commitment to EDI and their impacts on EDI performance. Analyses supported the hypothesized time effects that trust and commitment to EDI develop positively as EDI moves from initial stage to application stage. However, the impacts of these two dimensions on EDI performance did not change significantly over time.

• Journal of Mechanical Science and Technology
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• v.20 no.6
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• pp.840-848
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• 2006

We carried out numerical studies to investigate the single- and two-phase flow characteristics in the single- and multi-channels. We used the finite volume method to solve the mass and momentum conservation equations. The volume of fluid model is used to predict the two-phase flow in the channel. We obtained the distribution of velocity fields, pressure drop and air volume fraction for different water mass flow rates. We also calculated the distribution of mass flow rates in the multi-channels to understand how the flow is distributed in the channels. The calculated results for the single- and two-phase flow are partly compared with the present experimental data both qualitatively and quantitatively, showing relatively good agreement between them. The numerical scheme used in this study predicts well the characteristics of single-and two-phase flow in a multi-channel.

• Journal of Korean Society of Transportation
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• v.26 no.6
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• pp.17-27
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• 2008

Logistic activities of shippers contains only origin-destin commodity flow information, but also contract relationships, cash flows and distribution channels. Under the lack of understanding of physical distribution channels, most studies have focused on the social and psychological aspects between manufacturers and retailers (e.g., mutual trust, power, conflict, reciprocal commitment, and so on). This study reports empirical results of distribution channel choice drawn from 2001 Korean Commodity Flow Survey(CFS) conducted by Korean government. Based on the CFS data, four distribution channels are classified. This study scrutinized how various factors including mode, commodity and firms characteristics affect distribution channel choice, and reported the problems of 2001 CFS survey questionaires and future directions.

• Ecology and Resilient Infrastructure
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• v.4 no.4
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• pp.207-215
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• 2017

Hydraulic issues such as flow resistance, side wall correction, sediment, erosion and deposition, and channel design have close relation with distribution of bed shear stresses but the measurement of the distribution of bed shear stresses is not easy. In this study the Preston tube which makes possible relatively simple measurement of bed shear stresses is used to analyze the characteristics of bed shear distribution in compound open channels with different depth ratio. The Preston tubes are made and calibrated to develop the calibration formula and then they are applied to measure bed shear stress distribution in 5 cases depth ratio condition of compound channels. The results are compared with former experiment data, and characteristics of bed shear stress distributions are studied with different channel scales and Reynolds numbers. Although bed shear distributions with depth ratio show overall agreement with former studies, some differences are verified in bed shear variation, formation of inflection point in main channel, and distribution near floodplain junction which are due to high Reynolds number. Through the study applicability of the Preston tubes are also verified and characteristics of bed shear distribution in compound channels are suggested with Reynolds number and depth ratio.

• Journal of Distribution Science
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• v.14 no.12
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• pp.43-51
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• 2016

Purpose - The purpose of this paper is to discuss success factors behind ATO distribution channels by examining successful partnerships between producers and alternative trading organizations (ATOs). Research design, data, and methodology - This is a case study, an analytical approach, which illustrates how the partnership between producers and ATOs has strengthened the fair trade and the performance of participants in the trade based on the example of the trading relationship between Beautiful Coffee, an alternative trading organization dealing coffee related products, and the coffee cooperative union (CCU), a coffee producing cooperative in Gulmi, Nepal. Results - Beautiful Coffee in the partnership with HELVETAS empowered small coffee farmers by a successful institutionalization of CCU that consolidated the distribution channel to be more efficient. Also, Beautiful Coffee and its partnership with KOICA have tried to increase productivity and quality of coffee beans. Conclusions - The case of Beautiful Coffee demonstrates that the partnership between producers and alternative trading organizations (ATOs) has benefited the fair trade partners. In other words, Beautiful Coffee's partnerships with a NGO working in the local producing area, HELVETAS, and a government aid agency, KOICA could strengthen the relationship between the producers and the ATO, and thus contributes to the whole distribution channel.