• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.9-16
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• 2003

In this paper, we propose a method for supporting VCR operations in a patching based multicast VOD system. Random access, pause and resume operations are supported in our system, and the channel and session scheduling algorithms for the VCR operations are proposed. When it is necessary to join a sharable multicast channel in the admission control for the VCR operations, the patching technique, which shares an on-going regular channel and allocates a new patching channel for the missing data, is used. Therefore, unlike the previous approach that allocates an excessive number of I-channels, service latency is minimized and channel usage is optimized in our system. Moreover buffered data. which is saved in disk during patching, is reused to prevent unnecessary patching channel allocation. For this. the patching management information is extended and a buffed data management scheme is proposed. In our system, the First-Come-First-Served scheduling is used to inform clients the service latency for the VCR operations immediately.

• Journal of Information Technology Applications and Management
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• v.26 no.2
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• pp.41-60
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• 2019

O2O(Online-to-Offline) commerce, a kind of multi-channel, is used in various industries such as accommodation, food and beverage, transportation, and real estate. The O2O commerce, a channel of integrating online and offline, overcomes the limitations of traditional online commerce, where a customer made a purchase decision without direct experience. Despite this advantage of O2O, if the online-offline channel is not effectively linked, customer's complaints would occur due to service failure. This study, with regard to O2O service failure circumstances, intends to investigate the effect of customer's perceived justice on their emotional response, recovery satisfaction, followed by intention to repurchase. Perceived justice in this study is composed of distributive justice, interactional justice, and procedural justice. Furthermore, this study explores the moderation effect of O2O industry types in the relationship between perceived justice and emotion. An O2O industry type is classified into accommodation, food and beverage, and transportation. A hypothesized research model was empirically tested using a structural equation model. The current study collected 433 questionnaires and the target respondents are customers who have experienced service failure in O2O commerce. The empirical results showed that O2O commerce more effectively conducts service recovery strategy and causes positive customer response by integrating online and offline channel. One of the ultimate purposes of O2O service providers is to reduce the likelihood of service failures and to recover more quickly and efficiently by linking two channels rather than using a single channel. This study suggested that the O2O channel is effective in influencing customer satisfaction and loyalty by inducing customer's positive emotions in recovering service failure.

• The Korean Journal of Franchise Management
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• v.4 no.1
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• pp.91-112
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• 2013

In modern society the Lubricants is widely used everyday life such as transportation and industrial plant. This study aims to provide an overview of the distribution channel of Lubricant and it's history of development in Korea. For this purpose, this study explores the basic knowledge and it's characteristics of lubricant which is essential goods for all transportation including cars and for all industrial facilities to produce their own products. According to development of industry and economic grow, the distribution channel also expended and become more complicated. Especially as Lubricants has both characteristics of consumer products and industrial products, the distribution channel is also developed different ways. I will attempt to summarize the differences between each distribution channels including franchise network of automotive repair shop and issues on role and responsibility of manufacturer and distributor. And then I hope to suggest the improvement of distribution channel.

• Journal of Digital Convergence
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• v.16 no.5
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• pp.231-237
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• 2018

This paper investigates the impact of the channel variations and channel estimation errors on the error performance of convolutional coded STBC systems. We consider the orthogonal Almouti STBC and the quasi-orthogonal Jafarkhani STBC, and the error performance of the convolutional coded STBC system is investigated according to the channel variation and channel estimation error via numerical simulations. Simulation results show that, if the channel variation speed is slow, time diversity effects improve the error performance compared to the static-channel cases. However, if the channel variation speed is fast, unlike ZF or MMSE detection, the conventional STBC detection has the significant performance degradation especially with the quasi-orthogonal Jafarkhani STBC. Further, the error performance of the system is significantly degraded as the channel estimation errors become stronger, regardless of the detection scheme and channel variation speed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.179-187
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• 2007

As wireless networks evolve to orthogonal frequency division multiple access(OFDMA) systems, inter-cell interference control becomes a critical issue in radio resource management. The allocation of the same channels in neighbor cells cause inter-cell interference, so the channel allocation needs to be taken carefully to lower the inter-cell interference. In distributed channel allocation, each cell independently tries to allocate channels that suffer low interference level. In this paper, under the assumption of static users, we introduce the concept of interference range and use it in designing our two algorithms; basic and combined. The basic algorithm performs interference range detection and determines whether to use the considered channel, while the combined algorithm checks the channel quality in addition to detecting the interference range. The two algorithms dynamically perform channel allocation with low complexity and show good throughput and fairness performance.

• Journal of Distribution Science
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• v.16 no.1
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• pp.47-58
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• 2018

Purpose - China has become the world's largest market of Korean culture goods. However the distribution and information channel from which Chinese consumers can access to Korean contents remains under-explored. This study aimed to investigate Chinese consumers' information accessing behavior. Research design, data, and methodology - We collected the sample of 800 customers who are exposed to Korean Wave in China. Regression analysis is used to confirm the relationships in the research model. Results - The results showed that official channels such as state owned sites still play a significant role, Chinese consumers prefer to use unofficial channels and the private SNS is the most popular one. It is also found that users with low interests in Korean contents prefer offline/indirect channels while people who are highly immersed into Korean culture and spend longer time on it tend to favor online/unofficial channels. The results confirms that there are some users' characteristics such as gender, age, income and experience of visiting Korea are relevant to explain their propensity to select distribution and information channels for Korean contents. Conclusions - The study enables managers to develop the more effective distribution channel strategies according to the different target consumer groups.

• Journal of Korean Neurosurgical Society
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• v.47 no.6
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• pp.433-436
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• 2010

Objective : Arachnoid cysts (ACs) can be cured by making the definite and wide communication between the cyst and arachnoid space using endoscopy, but often it is impossible only through the usual working-channel (intra-channel) procedures. We discuss and propose a more valuable endoscopic technique with the presentation of our series of cases. Methods : We treated 9 patients with cortical AC in various locations with extra-channel endoscopic techniques. The patients ranged in age from 3 years to 60 years (mean age, 37.2 yrs). The follow-up period ranged from 12 to 26 months (mean follow-up duration, 17.2 months). All patients had large AC compressing the adjacent brain with clinical symptoms or signs. The authors performed extensive fenestration via single burr hole with the aid of endoscope. Being bypassed the rigid endoscope, through the space between the shaft of endoscope and guiding cannula (extra-channel method), fenestration procedures were done in the dry fields. Results : Eight (88.9%) patients had been treated successfully with endoscope. One patient required shunt procedure. Among the eight patients who were treated with endoscopic procedure, 6 patients (66.7%) showed cyst reduction, and two (22.2%) showed disappearance of cyst. Conclusion : We suggest that extra-channel method will be simple and easy to perform using more valuable instruments with wider working area, and may promise better results compared to the conventional intra-channel endoscopic procedures.

• Journal of Communications and Networks
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• v.6 no.3
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• pp.245-257
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• 2004

Driven by the growing number of the mobile subscribers, efficient channel resource management plays a key role for provisioning multimedia service in the next generation personal communication systems. To reuse limited channel resources, diminishing the coverage areas of cells seems to be the ultimate solution. Thus, however, causes more handover events. To provide seamless connection environment for mobile terminals and applications, this article presents a novel handover scheme called the intelligent channel reservation (ICR) scheme, which exploits the location prediction technologies to accurately reserve channel resources for handover connections. Considering the fact that each mobile terminal has its individual mobility characteristic, the ICR scheme utilizes a channel reserving notification procedure (CRNP) to collect adequate parameters for predicting the future location of individual mobile terminals. These parameters will be utilized by the handover prediction function to estimate the expected handover blocking rate and the expected number of idle channels. Based on the handover prediction estimations, a cost function for calculating the damages from blocking the handover connections and idling channel resources, and a corresponding algorithm for minimizing the cost function are proposed. In addition, a guard channel decision maker (GCDM) determines the appropriate number of guard channels. The experimental results show that the ICR scheme does reduce the handover-blocking rate while keeping the number of idle channels small.

• Journal of the Korean Institute of Navigation
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• v.18 no.2
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• pp.41-56
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• 1994

This paper was a part of the risk management in planning a channel. It utilized Korea Marine Training & Research Institutes(KMTRI) which Houses a real-time, full-mission shiphandling simulator to examine the safety of the ship's transit in the planned channel of Asan port. 6 competent Captains participated in this study. The vessel modelled was a 60,000-ton ship. The two variables(factors) examined were environ-mental conditions such as flood-and-ebb current condition and day-and-night condition. The two variables were combined to produce four experimental conditions. To evaluate the safety of the environmental conditions, two categories of performance measures were analyzed. They were vessel's proximity to channel boundary and vessel controalbility. The findings regar-ding the effects of environmental conditions were as follows : - Closest Point of Approach(CPA) to channel boundary was enough for 60,000-ton ship to transit th-rough the channel with 99.999% confidence level. - Closest Point of Approach(CPA) to channel boundary further was under against-current condition than under with-current condition. -Vessel controlability was better under against-current condition than under with-current condition. -Vessel controlability was better under inbound transit than under outbound transit.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.8
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• pp.2648-2665
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• 2022

Device-to-device (D2D) multicast has become a promising technology to provide specific services within a small geographical region with a high data rate, low delay and low energy consumption. However, D2D multicast communications are allowed to reuse the same channels with cellular uplinks and result in mutual interference in a cell. In this paper, an intelligent channel assignment algorithm is designed in D2D underlaid cellular networks with the target of maximizing network throughput. We first model the channel assignment problem to be a throughput maximizing problem which is NP-hard. To solve the problem in a feasible way, a novel channel assignment algorithm is proposed. The key idea is to find the appropriate cellular communications and D2D multicast groups to share a channel without causing critical interference, i.e., finding a channel for a D2D multicast group which generates the least interference to network based on current channel assignment status. In order to show the efficacy and effectiveness of our proposed algorithm, a novel search algorithm is proposed to find the near-optimal solution as the baseline for comparisons. Simulation results show that the proposed algorithm improves the network throughput.