• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.147-154
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• 2009

Antenna grouping algorithm is hybrid of beamforming and spatial multiplexing. In antenna grouping system, we partition $N_t$ transmit antennas into $N_r$ groups and use beamforming in a group, spatial multiplexing between groups. We can transmit $N_r$ data streams in the $N_t{\times}N_r$ antenna grouping system. With antenna grouping, we can achieve diversity gain through beamforming, and high spectral efficiency through spatial multiplexing. But if channel is ill-conditioned or there are some correlations between antennas, the performance of antenna grouping is seriously degraded and in that case, beamforming is the best transmit strategy. By selecting the antenna grouping mode when channel is well-conditioned and by selecting the beamforming mode when channel is ill-conditioned, we can prevent serious fluctuation of BER performance caused by varying channel condition and achieve the best BER performance. In this paper, we investigate mode selection algorithm which can select antenna grouping mode or beamforming mode. we also propose a simple mode selection criterion.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3862-3888
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• 2017

In high diversity node situation, single-channel MAC protocols suffer from many collisions. To solve this problem, the research of multichannel MAC protocol has become a hotspot. And the cyclic quorum-based multichannel (CQM) MAC protocol outperformed others owing to its high frequency utilization. In addition, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The metrics (throughput and average packet transmission delay) are calculated in performance analysis, with respect to node number, packet rate, channel slot length and channel number. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm (BSA). Finally, the Markov chain model and saturation bound are verified by Qualnet platform. And the simulation results show that the analytic and simulation results match very well.

• The Journal of Bigdata
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• v.2 no.1
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• pp.27-39
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• 2017

The importance of online communication is getting increased by the rapid growth of smartphone supply and Social Network Service (SNS) use. Catching up with the trend, firms are actively use SNS to improve brand image, promote products, and communicate with customer. On the one hand, SNS is the channel for firms' marketing activities, but on the other, it is also the channel where the events related to the firms propagate in real time. Firms are led to unexpected state of crisis, when events are quickly spread out on SNS. Then firms are assessed their image by the way they deal with the state of crisis. This paper proposes to figure out user response on SNS according to each crisis response strategies by analyzing event-related twitter data when crisis situations of firms arise. We classify crisis response strategies into response attitude, defensive and accommodative response, and response speed, fast and slow response. This paper suggests optimal crisis response strategy to firms regarding state of crisis propagated on SNS.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.70-80
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• 2008

CSMA(Carrier Sense Multiple Access) is a media access control protocol when nodes use a shared channel. To reduce the probability of collision and increase the performance, the station lust checks the state of the channel. In this paper, we study the performance improvement method based on p-persistent strategy. The p-persistent method reduces the chance of collision and improves the efficiency. However, a probability p and the number of station affect the performance. This paper proposes a dynamic CSMA multiple access based on the network status. If the possibility of collision is low, the station increases the probability p to improve the performance. In the opposite case, the station decreases the probability p. Our simulation results show that the proposed scheme outperforms any methods of CSMA multiple access according to the current persistent strategy.

• Information Systems Review
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• v.5 no.2
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• pp.1-21
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• 2003

In this paper, we investigate industrial product intermediary's transformation strategy by exploiting advantages afforded by web based information technologies. Our motivation for this research stems from exploring intermediary's responding strategy to cope with supplier's threatening to disintermediation. From transaction cost perspective, internet can induce both the vertical quasi-integration (electronic hierarchy) and outsourcing (electronic market). Our rationale on directing one of these bi-directional movements is specified on intermediary's value adding on the supply chain. As such, we investigated supply chain performance, IT effects on customer's requirement of channel functions, and channel power structure. Propositions to suggest contingent e-transforming strategic alternatives are logically derived from dyadic nature of supply chain characteristics such as efficiency versus customer services, and supplier dominant versus easy replaceability of suppliers. The contingent e-transformation framework developed from intermediary's perspective is reviewed through longitudinal industry case analysis. Implications from the industry case analysis give us insights for the effectiveness of the framework to combine supply chain characteristics with intermediary's e-transformation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4748-4765
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• 2016

We consider a virtualized cognitive radio (CR) network, where multiple virtual network operators (VNOs) who own different virtual cognitive base stations (VCBSs) share the same physical CBS (PCBS) which is owned by an infrastructure provider (InP), sharing the spectrum with the primary user (PU). The uplink scenario is considered where the secondary users (SUs) transmit to the VCBSs. The PU is protected by constraining the interference power from the SUs. Such constraint is applied by the InP through pricing the interference. A Stackelberg game is formulated to jointly maximize the revenue of the InP and the individual utilities of the VNOs, and then the Stackelberg equilibrium is investigated. Specifically, the optimal interference price and channel allocation for the VNOs to maximize the revenue of the InP and the optimal power allocation for the SUs to maximize the individual utilities of the VNOs are derived. In addition, a low‐complexity ±‐optimal solution is also proposed for obtaining the interference price and channel allocation for the VNOs. Simulations are provided to verify the proposed strategies. It is shown that the proposed strategies are effective in resource allocation and the ±‐optimal strategy achieves practically the same performance as the optimal strategy can achieve. It is also shown that the InP will not benefit from a large interference power limit, and selecting VNOs with higher unit rate utility gain to share the resources of the InP is beneficial to both the InP and the VNOs.

• Korea Science and Art Forum
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• v.37 no.3
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• pp.113-123
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• 2019

In line with policy support and demand, mobile videos about science and technology have growth potential. For activation of domestic mobile video contents about science and technology, this article aims to analysis current global leading contents and draw implications for benchmarking. Therefore, this paper attempted to analyzed types and storytelling strategy of Science and technology channels on YouTube, which has the most influence among the mobile video media. The results are as follows. Fist, the YouTube contents about science technology are categorized into three types, activity-, explain-, review-centered type. Second, activity type channels are classified into 4 sub-types. Third, The core storytelling strategy of activity type channels is a combination of familiarity and unfamiliarity to deal with everyday material through specialized scientific and technological methods. Based on the results of this research, we expect to plan and produce global killer contents.

• Journal of Digital Convergence
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• v.10 no.8
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• pp.119-133
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• 2012

Recent rise of social media channel is changing social and economic paradigm and is being used as an effective communication in marketing. The following research analyzes the most employed social marketing tools such as portal advertisement, blogs, and SNS channels to effectively execute social media marketing from performance indicator and ICSI perspective, analyzes each channel's characteristics and results based on Korea distribution companies' case studies and suggests a framework to effectively use each channel. Portal site advertisements are the most effective channel to draw customers with new information and are thus linked to profit by corporations with excessive budget and workforce. Blogs target a specific range of customers providing quality information and knowledge thus improving a corporation's and its product's trustworthiness, spread the word by allowing customers to scrap the information, form social groups and synthesize ideas, events, new contents and social involvement with loyal customers. SNS channels allow customers to get involved in real time information and events, grow through network by the power of customers, react immediately to customers' needs, and execute real-time market and customer reports. Though national corporations currently rely heavily on portal site advertisements, insightful marketing professionals are showing financial results with blog and SNS. In the future, based on a precise understanding of each channel's benefits and expected results, and with a focus on flexibility, timeliness and integrated use of each channel, a portfolio of dynamic marketing as a maximizing strategy could be synthesized.

• Journal of Distribution Science
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• v.9 no.4
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• pp.63-73
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• 2011

The relationship between buyers and sellers is changing into a long-term relationship. A number of distribution channel researchers have determined that the behavior of distribution channel members can be characterized by relational exchanges. The members of relational distribution channels may be perceived as strategic partners; however, even within these arrangements, member asymmetries may exist, which can create unequal distributions of power and dependence. Thus, as all distribution channel members may not be equal in power, it is possible that a less-dependent channel leader may emerge. Therefore, leadership in distribution channels is a very important variable. Distribution channel leadership can be defined as the activities undertaken by the distribution channel leader to influence the marketing programs and strategies of channel members. A distribution channel's performance is influenced by the leadership style of the channel leader. Although research on channel leadership styles can be broadly categorized, many researchers have dealt with analyzing distribution channel leadership by using the power-influence approach, which includes looking at variables, such as power, power base, and influence strategies. Moreover, they have examined the direct relationship between leadership styles and performance. Many distribution channel scholars have attempted to justify the application of leadership styles identified in alternative leadership theories to the inter-organizational context of distribution channels. They have made suggestions regarding how great the usefulness of leadership style as a strategy is to secure the compliance of distribution channel members and have conceptually and empirically linked it to channel-related phenomena, such as manifest conflict, cooperation, channel efficiency, and effectiveness. However, as few empirical studies have examined the antecedents and consequences of leadership styles, research on leadership style can be considered nascent. Thus, it is required to investigate the antecedents and consequences of the leadership style of a distribution channel leader. This study aims to empirically identify whether there are influences of the antecedents of leadership on two different leadership styles, and to reveal whether these leadership styles induce any consequences. The research subjects were 220 franchisees. Research findings are as follows: First, the results show a positive effect of technological capability on transformational relationships. However, it does not have a significant effect on transactional leadership. Second, innovation-oriented organizational culture has negatively influenced both leaderships. However, task-oriented organizational culture positively and significantly influenced both forms of leadership. Third, the ethics of leaders has influenced both leadership styles positively and significantly. Fourth, regarding consequences, transformational leadership strengthens financial performances, whereas it weakens relational citizenship behaviors. However, transactional leadership positively influences relational citizenship behavior whilst negatively affecting financial performance.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.369-381
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• 2011

Ginseng in Korea has not only the big production value but also till a good reputation from overseas in the name of 'Korea Ginseng'. Having spread rapidly nationwide from 2000 year, its production keeps on increasing but its consumption becomes lazy and its price is also falling down because of comsumer's concern about mainly overusing pesticide for ginseng. In order to cope with this problem, the government introduced the GAP certification system to ginseng in 2006 to reflect consumer's needs for food safety. This system will be a good opportunity to promote ginseng consumption dramatically. In this aspect it is very important to know how well this system is established and how ginseng farmers build marketing strategies to draw new wind in the market. This study was carried out to look over the GAP certified ginseng system and show its marketing strategies using 4P's(product, place, promotion and price). The main results are as follows. GAP ginseng system currently has some weaknesses such as lack of systematic certification management and after-service, nonrealistic certification fee and poor linkage from production to consumption. In the marketing mix strategies, product strategy suggests that the most desirable appearance be transplanted ginseng filled with branch roots and 4 to 5 year-ginseng, and it is necessary to choose multi-brand strategy divided for present into for self-sufficiency and family brand strategy by use if its brand enlarges to processed products in the future. In the place strategy, 3 stages like 'producer group' - 'GAP certified facility' - 'sales shop' are based as the physical marketing channel according to traceability, and connected with giant retail market and environment friendly stand, and if its sales volume enlarges, it should be considered the GAP ginseng specialized marketplace which is a type of chain store. In the promotion strategy, the promotion of government level is necessary at first and producer alliances require the promotion targeting at the group of women under 40 with differentiation from price, quality, and safety. In the price strategy, the early stage-high price strategy which sets 20~25% higher for self-sufficiency and 30~35% for present is desirable.