• Journal of computational fluids engineering
• /
• v.18 no.4
• /
• pp.17-24
• /
• 2013

In this study, we consider the characteristics of channel flow in the presence of an infinite streamwise array of equispaced identical rotating circular cylinders. This flow configuration can be regarded as a model representing a micro channel or an internal heat exchanger with cylindrical vortex generators. A numerical parametric study has been carried out by varying Reynolds number based on the bulk mean velocity and the cylinder diameter, and the gap between the cylinders and the channel wall for some selected angular speeds. An immersed boundary method was employed to facilitate implementing the cylinders on a Cartesian grid system. No-slip condition is employed at all solid boundaries including the cylinders, and the flow is assumed to be periodic in the streamwise direction. The presence of the rotating circular cylinders arranged periodically in the streamwise direction causes a significant topological change of the flow, leading to increase of mean friction on the channel walls. More quantitative results as well as qualitative physical explanations are presented to justify the effectiveness of rotating cylinders to modify flow topology, which might be used to enhance heat transfer on the channel walls.

• Journal of Distribution Science
• /
• v.19 no.12
• /
• pp.23-32
• /
• 2021

Purpose: By integrating multiple separate online, offline distribution channels, omnichannel distribution has modernized and revolutionized the retailing sector. Omnichannel distribution supports firms by delivering seamless shopping experiences for customers throughout all touchpoints of the shopping journey. This paper aims at exploring the impact of channel integration quality on customer experience and patronage intentions in the omnichannel distribution context. Research design, data and methodology: An online survey was taken with 351 omnichannel experienced shoppers by utilizing the structured questionnaire. The partial least square-structural equation modeling (PLS-SEM) and Smart PLS software were employed to analyze and test proposed hypotheses. Results: The findings reveal that channel integration quality dimensions including breadth of channel-service choice, transparency of channel-service configuration, content consistency, and process consistency, play crucial roles in the customer shopping experience. The perceived compatibility has been influenced by the integrated interactions in which content consistency and process consistency. The findings also demonstrate the positive and direct impact of perceived compatibility on customer experience, and both factors have substantial effects on customers' patronage intentions. Conclusions: This study sheds light on the literature on channel integration quality, omnichannel retailing experience and customer patronage. In addition, this study provides practical implications for omnichannel retailers in enhancing customer experience and patronage.

• Journal of Korea Water Resources Association
• /
• v.40 no.5
• /
• pp.359-369
• /
• 2007

In this study the evaluation method for riverine naturalness proposed previously by other researcher has been modified to assess stream naturalness of small scaled streams. Two evaluation items have been added to the previously proposed method. That is, the modified method for evaluating naturalness of small scaled streams contains 16 evaluation items with two categories - river morphology and river environments. The three evaluation items have been improved based on the results of stream configuration and characteristics investigation. To prepare evaluation index for channel configuration of small scaled stream, 55 small scaled streams have been selected to analyze sinuosity, wavelength, etc. It has been shown that the values of sinuosity are around 1.2 and one wavelength appears approximately every 500 m in the sample streams. An equation implied diversity for width of normal flow has been proposed to add the evaluation index for diversity of channel width. The every 500 m 1,000 m along small scaled stream is also recommended through the investigation as the interval of evaluation unit. The modified method has been applied to the DangWang stream to estimate the effect of stream rectification project. It has shown that the proposed method would appropriately reflect channel morphology and environments before and after the rectification project.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.9A
• /
• pp.788-794
• /
• 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 Transactions of the Korea Information Processing Society
• /
• v.6 no.11S
• /
• pp.3367-3378
• /
• 1999

ATM technology, which acts as a representative high-speed bandwidth technology, plays an important role in Internet environment. ATM network, supporting QoS(Quality of Service) and various traffic characters in high speed, configures many VPC(Virtual Path Connection)/VCC(Virtual Channel Connection). It is important to guarantee the QoS of each connection and it is necessary for the network manager to search element affecting the QoS of VPC/VCC and to control ATM network correctly. In the paper, the management information of VPC/VCC, that ATM network manager Using the fault notification for ATM switch, we can manage the configuration, fault and performance of ATM network. Thus, we extracted the configuration, fault and performance monitoring item from the ATM-MIB and SNMP M4 Network Element View MIB. And we designed the ATM network configuration, fault and performance management system based on the extracted item.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.4
• /
• pp.339-345
• /
• 2007

In the present study, a 10-cell PEMFC stack with straight type cathode flow channels is employed to investigate the effect of inlet air flow header configuration on the overall fuel cell performance. Four different types of inlet flow headers are considered and the flow patterns according to the air inlet flow header configuration are numerically obtained. The computed result for a modified header predicts about 8.5% improvement in the air flow distribution at 10-cell cathode channel inlets. Experiments are also carried out to confirm the numerical findings by measuring actual air flow distributions and the polarization curves of the PEMFC stack.

• ETRI Journal
• /
• v.44 no.6
• /
• pp.966-976
• /
• 2022

Optical wireless communication, or free space optics, is a promising solution for backhauls in sixth-generation mobile systems. However, the susceptibility of optical links to weather conditions has led to FSO links being furnished with radio frequency (RF) backups. These Hybrid FSO/RF systems provide enhanced link availability but lead to RF resource wastage. Cognitive radio technology, in contrast, is well known for its optimal use of RF resources and may be combined with an FSO link to create a Cognitive Hybrid FSO/RF system. This work uses such a system to analyze a configuration for a mobile backhaul in sixth-generation mobile systems. This configuration can seamlessly coexist with established large scale RF cellular networks. The performance of this configuration is analyzed with respect to outage probability and average bit error by considering the impact of optical channel turbulence, misalignment loss, RF interference, and noise. Mathematical closed-form expressions are verified by simulations.

• Korean Journal of Optics and Photonics
• /
• v.33 no.6
• /
• pp.245-251
• /
• 2022

We have developed a multi-channel fiber laser for tiled laser beam combining and a laser output array system for multi-beam alignment. The fiber laser is a master oscillator power amplifier configuration that has a common seed, a preamplifier, and a 7-channel amplifier. The output power of each channel is more than 10 W. The laser output array system is a packed cylindrical configuration for a high fill-factor, and it has capabilities for collimation and tilt control with built-in PZT. Multi-beam alignment to a target is successfully implemented using PZT controlled with a stochastic parallel gradient descent (SPGD) algorithm.

• Proceedings of the KOSOMBE Conference
• /
• v.1994 no.05
• /
• pp.142-145
• /
• 1994

Calcium(Ca) ion plays an important role to trigger the secretion of important neurotransmitters. Since Ca ion flows into the cell thru the ion selective channel, the conductance of which depends on the transmembrane potential, the voltage-dependent characteristic of Ca ion channel is crucial to elucidate the stimulus-secretion coupling of exocytosis. The present study measured the Ca ion currents thru a whole-cell configuration patch at the transmembrane potential clamped at various desired levels in the rat chromaffin cell. The resultant current-voltage relationship was differentiated to obtain dynamic conductance at each clamped voltage. Based on these measured data, five numerical parameters were extracted to reveal electrical properties of Ca ion inflow process thru the voltage-gated channel. The present study can be applied to comparing the electrical characteristics of Ca channel under different experimental conditions. Also, further study is warranted to model the conformational changes of the channel molecules.

• Archives of Pharmacal Research
• /
• v.29 no.10
• /
• pp.834-839
• /
• 2006

Torilin was purified from Torilis japonica (Houtt.) DC., and its effects on a rapidly activating delayed rectifier $K^+$ channel (hKv1.5), cloned from human heart and stably expressed in Ltk cells, as well as the corresponding $K^+$ current (the ultrarapid delayed rectifier, $I_{KUR}$) were assessed in human atrial myocytes. Using the whole cell configuration of the patch-clamp technique, torilin was found to inhibit the hKv1.5 current in time and voltage-dependent manners, with an $IC_50$ value of $2.51{\pm}0.34\;{\mu}M$ at +60 mV. Torilin accelerated the inactivation kinetics of the hKv1.5 channel, and slowed the deactivation kinetics of the hKv1.5 current, resulting in a tail crossover phenomenon. Additionally, torilin inhibited the hKv1.5 current in a use dependent manner. These results strongly suggest that torilin is a type of open-channel blocker of the hKv1.5 channel.