• Magazine of the Korean Society of Agricultural Engineers
• /
• v.15 no.1
• /
• pp.2853-2877
• /
• 1973

Models of cross-sections and channels were made in order to measure seepage losses. Cross-sections were made of sand, sandy clay loam and loam, their thicknesses being 30cm and 40cm, respectively. Flow depths kept in the cross-sections were 4cm, 6cm, 8cm and 10cm. Straight and curved channel models were provided so as to measure seepage losses, when constant water depths maintained at the heads of the channels were 7.3cm and 5.7cm, respectively. The results obtained in this experiment are presented as follows: 1) A cumulative seepage loss per unit length at a point in the channel varies in accordance with time and flow depth. The general equation of cumulative seepage loss may be as follows(Ref. to Table V.25): $$q_{cum}=\int_{o}^aq(a)dt+\int_a^bq(b)dt+\int_b^tq(c)dt$$ 2) In case that the variation of water depth through the channel is slight, the total seepage loss may be computed by applying the following general equation: $$\={q}_{cum}{\cdot}x=\int_o^tq_{cum}\frac{{\partial}x}{{\partial}t}dt$$ 3) Because seepage loss varies considerably according to water depth in case that the variation of flow depth through the channel is great, seepage loss should be computed by taking account of the change of flow depth. 4) The relation between time and traveling distance of water flow may be presented as the following general equation(Ref. to Table V.29): $$x=pt^r$$ 5) The ratios of the seepage losses of the straight channel to the curved channel are 1:1.03 for a flow depth of 7.3cm and 1:1.068 for that of 5.7cm. 6) The ratios of the seepage losses occurring through the bottom to those through the inclined plane in the channel cross-section are 1:2.24 for a water depth of 8cm and 1:2.47 for a depth of 10cm in case that soil-layer is 30cm in thickness. Similarly, those ratios are 1:2.62 and 1:2.93 in case of a soil-layer thickness of 40cm(Ref. to Table V.5).

• Journal of information and communication convergence engineering
• /
• v.8 no.2
• /
• pp.163-167
• /
• 2010

In underwater acoustic communication, acoustic signals from transducers or hydrophones are used. And the underwater acoustic communication channels are very complicated, because of vertical distribution of acoustic velocity according depths, and reflections from boundaries like as surface or bottom. For the implementation of the underwater acoustic communication channel, the image method or ray tracing method have been used. In this paper, we introduce a new approach for implementation of underwater acoustic communication channel using the simulation of the Transmission Line Matrix Modeling and cross-correlations from the input and output signals.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.4 no.3
• /
• pp.324-340
• /
• 2010

Video streaming service over wireless networks is a challenging task because of the changes in the wireless channel conditions that can occur due to interference, fading, and station mobility. To provide an efficient wireless video streaming service, the rate adaptation scheme should improve wireless node performance and channel utilization. Moreover, the quality adaptation scheme should be considered at the streaming application. To meet these requirements, we propose a new cross-layer design for video streaming over wireless networks. This design includes the rate and quality adaptation schemes. The rate adaptation scheme selects the optimal transmission mode and resolves the performance anomaly problem. Based on performance improvement by the proposed rate adaptation scheme, our quality adaptation scheme improves the quality of video streaming. Through performance evaluations, we prove that our cross-layer design improves the wireless channel utilization and the quality of video streaming.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.7C
• /
• pp.467-474
• /
• 2011

The performance of pilot-symbol-assisted channel estimation widely used for OFDM systems is degraded due to the small number of pilot symbols used for higher transmission efficiency. In this paper, we propose a pilot symbol based channel estimation using cross-correlation to improve the estimation performance of the OFDM system with small number of pilot symbols. The proposed technique detects a data symbol using the channel estimated by the pilot symbol and estimates the channel using the estimated data symbol and the pilot symbol. It is shown by computer simulations that the proposed technique outperforms the conventional pilot symbol assisted estimation technique.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.5
• /
• pp.19-26
• /
• 2014

The cross flow turbine attracts more and more attention for its relatively wide operating range and simple structure. In this study, a novel type of micro cross flow turbine is developed for application to a step in an irrigational channel. The head of the turbine is only H=4.3m and the turbine inlet channel is open ducted type, which has barely been studied. The efficiency of the turbine with inlet open duct channel is relatively low. Therefore, a guide nozzle on the turbine inlet is attached to improve the performance of the turbine. The guide nozzle shapes are investigated to find the best shape for the turbine. The guide nozzle plays an important role on directing flow at the runner entry, and it also decreases the negative torque loss by reducing the pressure difference in Region 1. There is 12.5% of efficiency improvement by attaching a well shaped guide nozzle on the turbine inlet.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.3
• /
• pp.225-236
• /
• 2002

In this paper, to counteract a cross-polarization interference caused by co-channel dual polarization technique of digital radio relay system(DRRS), we analyze the theoretical model and digital design of cross-polarization interference canceller(XPIC). In addition a complex adaptive time domain equalizer(ATDE) is designed using a finite impulse response filter, and the structure of XPIC and its control method are also illustrated including ATDE. Our computer simulation shows that about 25 dB signature and more than 23 dB XPIC improvement factor can be obtained with XPIC and ATDE. In order to verify the operation of designed XPIC, we review the simulated results in view of tap number, algorithm convergence, system signature, and XPlC improvement factor in connection with 64-QAM DRRS with co-channel dual polarization.

• Journal of Distribution Science
• /
• v.21 no.1
• /
• pp.13-22
• /
• 2023

Purpose: This study aims to investigate the linkages among cross-channel integration capability (CCI), showrooming, webrooming, and customer value of retail enterprises. From the literature review, this research proposes the research model on the direct impact of showrooming and webrooming on customer value as well as the indirect impact of cross-channel integration capability on customer value which is mediated by both showrooming and webrooming of retail enterprises. Research design, data, and methodology: By conducting a survey of 304 consumers in the five biggest retailers in Hanoi-Vietnam from mid-September 2021 to the end of November 2021, the PLS-SEM was used to test the hypotheses. Results: The research results reveal the favorable impact of (CCI) on improving showrooming and webrooming, and the important role of developing both showrooming and webrooming in bringing more value to the customer of retail enterprises. The findings also express that showrooming and webrooming acts mediating role in the favorable relationship between (CCI) and customer value of retailers. Conclusions: This research clarifies the positive impact of (CCI), showrooming, and webrooming on customer value. In addition, this study suggests practical implications for retail managers to provide more value for customers by enhancing (CCI) and developing both showrooming and webrooming.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2001.11a
• /
• pp.25-28
• /
• 2001

In this paper. to eliminate a cross-polarization interference caused by co-channel dual polarization technique of digital radio relay system(DRRS), a cross-polarization interference canceller(XPIC) is analysed in terms of the analytical modeling, digital design, and its performance. By virtue of a 13-tap adaptive equalizer and XPIC, about 23dB in XPIC improvement can be obtained by computer simulation. To show the operation of designed XPIC, some simulated results are reviewed under 64-QAM DRRS with co -channel dual Polarization.

• Fashion & Textile Research Journal
• /
• v.17 no.5
• /
• pp.741-753
• /
• 2015

This study identified factors that influenced fashion consumers' purchase intentions for cross-border online shopping. This study utilized three outshopping motivation dimensions (utilitarian, social, and hedonic) to empirically verify research questions. The moderating effects of consumers' perceived risks between cross-border online shopping motivations and behavioral intention were also tested on Korean female consumers in their 20s to 40s who had experience purchasing fashion goods through a cross-border online shopping channel within a year. The research are as follows. First, the three motivations have positive effects on cross-border online shopping purchase intentions. Fashion consumers are greatly influenced by hedonic motivation compared to utilitarian and social motivations. Second, perceived risks do not negatively influence cross-border online shopping purchase intentions. Finally, there exists moderating effects of perceived risks between utilitarian motivation and cross-border online shopping purchase intentions. This study reveals motivational and moderating factors that influence fashion consumers to shop through a cross-border online shopping channel. It contributes to prior studies by extending the research range of cross-border online shopping into fashion. Marketers and retailers should note that fashion consumers are most influenced by hedonic motivation when shopping in cross-border online malls.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.12
• /
• pp.5149-5173
• /
• 2016

Cooperative forwarding has shown a substantial network performance improvement compared to traditional routing in multi-hop wireless network. To further enhance the system throughput, especially in the presence of highly congested multiple cross traffic flows, a promising way is to incorporate the multi-radio multi-channel (MRMC) capability into cooperative forwarding. However, it requires to jointly address multiple issues. These include radio-channel assignment, routing metric computation, candidate relay set selection, candidate relay prioritization, data broadcasting over multi-radio multi-channel, and best relay selection using a coordination scheme. In this paper, we propose a simple and efficient cluster-based cooperative data forwarding (CCDF) which jointly addresses all these issues. We study the performance impact when the same candidate relay set is being used for multiple cross traffic flows in the network. The network simulation shows that the CCDF with MRMC not only retains the advantage of receiver diversity in cooperative forwarding but also minimizes the interference, which therefore further enhances the system throughput for the network with multiple cross traffic flows.