• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.339-344
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• 2006

Secure delivery of multicast data can be achieved with the use of a group key for data encryption in mobile ad hoc network (MANET) applications based on the group communication. However, for the support of dynamic group membership, the group key has to be updated for each member joining/leaving and, consequently, a mechanism distributing an updated group key to members is required. The two major categories of the group key distribution mechanisms proposed for wired networks are the naive and the tree-based approaches. The naive approach is based on unicast, so it is not appropriate for large group communication environment. On the other hand, the tree-based approach is scalable in terms of the group size, but requires the reliable multicast mechanism for the group key distribution. In the sense that the reliable multicast mechanism requires a large amount of computing resources from mobile nodes, the tree-based approach is not desirable for the small-sized MANET environment. Therefore, in this paper, we propose a new key distribution protocol, called the proxy-based key management protocol (PROMPT), which is based on the naive approach in the small-sized MANET environment. PROMPT reduces the message overhead of the naive through the first-hop grouping from a source node and the last-hop grouping from proxy nodes using the characteristics of a wireless channel.

• Journal of Distribution Science
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• v.14 no.4
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• pp.55-66
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• 2016

Purpose - This article aims to explore the characteristics of disaster risk distribution information in China. Also, this research attempts to analyze the findings of risk communication using case study in chronological order in terms of social amplification of risk. To achieve the purpose, the paper reviews the trends and issues of risk communication in China, with an emphasis on examining earthquakes by a chronological approach. In these regards, we hope that some relevant findings from this empirical study with cases will be able to enhance national risk communication and provide implications in Korea as well. Research design, data, and methodology - The conceptual framework of this study is theoretically based on the risk amplification model, which describes signals about risk transmitted and processed by individuals and social groups. The social amplification of risk also reflects the interactions of social groups about disaster-related risk issues, which are potential amplifiers or attenuators of communication signals. The key concept of social amplification implies that the risks pertaining to natural disasters interact with social, psychological, institutional, and cultural processes in ways that can affect public perceptions of risk. SMCRE Model is methodologically employed to examine risk communication history of China with the focus on natural disaster. Four earthquakes are selected to figure out the chronological characteristics of risk communication since 1970s. He bei Tang Shan earthquake is selected as an example disaster before 1990's, while the earthquake in Yun Nan Jiang is explored for the case study of 1990's. The earthquake in Si Chuan Wen Chuan is also examined as a example disaster of 2000's. The recent earthquake in Si Chuan Ya An Lu Shan is selected as a case of 2010s. Results - SMCRE model in this case study is operationally defined as a methodology and applied to the four earthquakes occurred in China. SMCRE model describes the exchange of risk information and is also applied to all forms of communication between stake holders. Each factor of risk communication includes source, message, channel, receiver and effect. It is notable that a big progress has been made on disaster risk communication in China for the past 40 years. We also found that highly developed information technology has enabled Chinese society to better cope with natural disaster, leading to enhanced disaster risk communication. It is mainly found from case study that the disaster risk communication of China has been involved with political situation, which derived from the change of government for the past 40 years. Conclusion - From this historical research, it can be inferred that the policies and politics of Chinese leaders have had a more critical role to play in the process of source of risk communication than those of any other countries. The results of this paper also support that the effective risk communication involves not only the improved reliability of local government as a key factor of disaster risk communication, but also is accompanied by international cooperation for substantial collaboration with stake holders.

• Journal of Distribution Science
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• v.13 no.1
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• pp.93-103
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• 2015

Purpose - This study plans to adopt a more sophisticated approach toward service recognition by customers in general supermarkets in order to revise the service quality measurement methods that suit the context of Korean distribution channels. In particular, in general supermarkets, where much of the shopping process is in the form of self-service, there is high reliance on the service recognized by the consumers; therefore, it is highly likely that consumers would make their purchasing decisions based on their recognition of service quality or guarantees. It also utilized service quality elements of a basic level in the KD-SQS development model in order to indicate that the quality recognized by consumers impacts their loyalty to the stores with financial value and abstract value. Research design, data, and methodology - The study suggested a theoretical model comprising 13 hypotheses on relations between theoretic variables, and conducted surveys with consumers using discount stores in Seoul and Gyunggi Metropolitan area in order to verify the hypotheses, while using SPSS 20.0, AMOS 21.0 as the verification program. The survey sheets used amounted to 332, and a structural equation model was used to analyze the reliability and validity of constituent elements and to verify the suggested hypothesis. Therefore, this study analyzes the interrelations between service quality and guarantee factors in the distribution channel and their relations with the loyalty to stores as a dependent variable. Results - First, the results of the hypotheses tests helped identify the relations between service quality, service guarantees, service value, and customer loyalty, providing an opportunity to define the relations between constituent elements. In particular, service convenience in service quality has no impact on financial values. Further, stores' service policy had no impact on abstract values. Service recognition by service convenience has an impact on abstract values such as good image, comfort, and usability, while mileage systems promote financial values for consumers. In order to improve consumer values in service quality and values, general supermarkets should improve their service convenience, membership, and mileage programs using various strategies. Conclusion - In order to improve consumer values in service quality and values, general supermarkets should improve their service convenience, membership, and mileage programs using various strategies. Further, as service guarantee systems have a significant and direct impact on customer loyalty, rather than customer value recognition, service guarantees should be used to encourage customers to re-visit the stores. Finally, this study applied the findings of preceding studies in terms of service quality measurement; it had limitations in referencing preceding studies in a comprehensive manner. It also had limits in expanding upon various preceding studies because it was difficult to apply new measurement tools due to the lack of service quality measurement tools for general supermarkets. Therefore, it is necessary to conduct more studies on service quality to measure service quality and develop measurement tools by incorporating various industry characteristics.

• KSBB Journal
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• v.10 no.1
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• pp.63-70
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• 1995

The effect of operating conditions on separation of soybean proteins in a home-made free-flow electrophoresis apparatus was investigated. Measurement of the pH, conductivity, and UV-absorbance(280 nm) were carried out at each run and the purity of the sample was tested with SDS-PAGE analysis. The soybean extract pretreated with Tris and boric acid was mixed with the amino acids composed of glutamic acid, histidine, arginine, glycine(1 mM each) with glycyl-glycine(2mM) and KCl(1mM). When the cellulose acetate was used as a compartment between the electrode and the buffer solution in the cell, pH distribution in the separation cell varied from 3.0 at the anodic side to 8.0 at the cathodic side and had two inflection point. The applied voltage was from 300V to 1000V and the separation was better at a higher voltage but the voltage was limited by the capability of the cooling system due to Joule heat. The proteins focused near the middle of the channel. From the change of pH and conductivity it was found that the ions in the channel moved out to the electrodes through the membrane. In the case when the concentration of the buffer solution was increased 5 times, proteins were focused at 300V. We could not increase up to the ten times of the concentration since the temperature difference between inlet and outlet was more than $25^{\circ}C$ and denaturation of proteins was expected. When ion-exchange membranes were used U-type pH distribution was set up due to the ionic polarization near the membrane. The commercial ampholytes, instead of the mixed amino acids showed not much improvements in purity of the separated sample.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.3
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• pp.221-231
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• 1997

This paper presents an analysis of a hybrid direct-sequence/slow frequency hopped code division multiple access(DS/SFH-CDMA) system employing noncoherent M-ary frequency shift keying(MFSK) modulation in a multiple m-distribution fading environment. Multipath interfer- ence(MPI) and multiuser interference(MUI) is taken into accout and the spectral efficiency is calculated for uncoded as well as simple channel coding systems. The predetection multipath CCI canceller in conjunction with convolution coding is employed for improving the bit error rate(BER) performance. The BER of noncoherent hybrid system is obtained using a Gaussian interference approximation. From the results, we know that the error performance more deteriorates as the depth of fading becomes deeper. The DS part of the modulation combats the multipath interference, whereas the FH part is a predetection against large multiuser interference. It is shown that, for the con- sidered types of a channel coding, the use of a predetection coding is still essential for obtained a satisfactory bit error performance. The results show that the capacity of the DS/SFG-CDMA MFSK communication system increases in proportion to the length of PN code sequence in the presence of AWGN and MUI. In m-distribution fading environment the capacity increases in proportion to the fading index. The capacity is increased and error performance is improved when the CCI Canceller and Convolution code technique are adopted, respectively. From the results, it is known that the error performance of $4\times10^{-2}$ by adopting Canceller technique. Also convolutional coding technique is the improvement of error performance attains about $10^{-5}$ in code rate 1/2.

• Journal of Distribution Research
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• v.9 no.3
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• pp.69-96
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• 2004

This study is based upon the assumption that trust is a pedestal of much importance in the relationship behavior marketing channel members conduct in their arena. Unlike the existing studies that consider trust to be a circular simple concept with the emphasis on mutually symmetrical relationship level, this study focuses on the asymmetrically different levels of asymmetric trust concept. The major results of this study are as follows: First, among the individual characteristics which could affect on trust, reputation plays a significant role in transaction. Second, in the domain of the relation between trust and relationship characteristics, opportunistic behavior is shown to influence upon trust. Communication is turn out not to be a significant factor in trust; in a further analysis, it is also shown to influence upon willingness to make future relationship behavior. Third, willingness to make future relationship behavior plays a significant influence on trust, which shows that trust is the very core factor in the long-term relationship behavior. We can find that the antecedent factors influencing upon the trust build-up are different between agents and buyers and the established trust influences upon the future relationship behavior. This study tries to show how trust is established and what role the trust conducts.

• Journal of Distribution Science
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• v.13 no.11
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• pp.47-58
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• 2015

Purpose - This study aims to seek determinants of department store sales commission rates under consignment contracts based on transaction cost theory, the power-dependence view, and the resource-based view. A consignment contract is a unique contract where the retailer, over a given period, takes possession of goods owned by a supplier, promotes the sales of these goods, and receives a profit share from their sales. Under this contract, the supplier owns the goods until they are sold. In department stores in South Korea, over 70% of overall sales comes through consignment contracts. In other words, this is the most popular contract agreement between large retailers and vendors in South Korea. Consignment contracts yield high profits to department stores with minimal sales uncertainty, stock cost, and marketing investment. Many suppliers believe the consignment contract commission rates are too high. However, department stores disagree. They state that the commissions are not high as they generate new value for the suppliers by accumulating up-to-date merchandise and supporting various marketing programs on their behalf. Recently, consignment contracts have been critically examined and scrutinized by politicians, mass media, and the public of Korea. This study further intends to derive implications reflecting both buyer and seller perspectives as well as offer insights to policy makers in making appropriate decisions. Research design, data, and methodology - To verify the proposed research model and test hypotheses, the authors selected 164 suppliers, which currently have relationships with department stores. This study carefully investigated the reliability, content validity, convergent validity, and discriminant validity of the proposed model. The data were analyzed using SPSS 18.0 and AMOS structural equation modeling program Results - For the transaction cost theory and the power-dependence view, the results indicated that product diversity and demand volatility had a positive impact on the sales dependence on a department store. Dependence in turn had a positive effect on the sales commission under the consignment contract. Based on the resource-based view, the department store's marketing capability, the supplier's perception toward merchandising, and supporting activities could enhance the department store's channel leadership in the buyer-seller relationship. Subsequently, the channel leadership had a positive effect on the sales commission. However, product complexity had no relationship with department store dependence. Conclusions - This is the first empirical research that investigates the determinants of sales commissions under consignment contracts in the domestic retail industry. This study reveals several theoretical and practical implications for both marketing scholars and marketers. In terms of theoretical implication, this study integrated and enlarged certain theoretical background, such as transaction cost theory, the power-dependence view, and the resource-based view, to explain the determinants of sales commissions under consignment contracts that include sales revenue. From a business management viewpoint, this research offers useful insights for policy makers by applying two different perspectives, both the manufacturer and the retailer, in terms of the sales commission issue under a consignment contract.

• Journal of Distribution Science
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• v.4 no.1
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• pp.27-51
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• 2006

This study is to understand the existing relation-marketing based on a result that social-relationship in market can effect on customer's action with expanding the seller-purchaser relationship, and understanding purchaser-purchaser relationship in the community. The result of this study could be summarized as below: First, the customer-sales person friendly relationship effects respectively on customer satisfaction and loyalty. Second, friendly relationship of customers effects on customer satisfaction and loyalty. Third, customers' satisfaction and trust increases customers loyalty. Considering that they could cause others to re-buy, friendly word of mouth, recommendations, we should know improving customers loyalty about a company(department store) is very important. This study presents not only customers and sales clerks relationship but also developing customer-customer relationship is important as well. From the viewpoint, this study gives the following strategic tactics to companies. First, customer's relationship with sales clerk is not able to be built in a short time unlike discount or gifts. Second, relationship around customers effects on loyalty of the department store, over the relationship of simple customer-sales clerk. Finally, companies, to make a relationship like fabric, should escape a two-level channel, a company to a customer, then recognize a three-level channel, a company to a friendly customer to a neutral or a unfriendly customer. That means a business should use the positive to make the negative or the neutral change their behavior to it.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.1
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• pp.12-21
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• 2012

IEEE 802.11 MAC protocol standard, DCF(CSMA/CA), is originally designed to ensure the fair channel access between mobile nodes sharing the local wireless channel. It has been, however, revealed that some misbehavior nodes transmit more data than other nodes through artificial means in hot spot area spreaded rapidly. The misbehavior nodes may modify the internal process of their MAC protocol or interrupt the MAC procedure of normal nodes to achieve more data transmission. This problem has been referred to as a selfish node problem and almost literatures has proposed methods of analyzing the MAC procedures of all mobile nodes to detect the selfish nodes. However, these kinds of protocol analysis methods is not effective at detecting all kinds of selfish nodes enough. This paper address this problem of detecting selfish node using Tsallis-Entropy which is a kind of statistical method. Tsallis-Entropy is a criteria which can show how much is the density or deviation of a probability distribution. The proposed algorithm which operates at a AP node of wireless LAN extracts the probability distribution of data interval time for each node, then compares the one with a threshold value to detect the selfish nodes. To evaluate the performance of proposed algorithm, simulation experiments are performed in various wireless LAN environments (congestion level, how selfish node behaviors, threshold level) using ns2. The simulation results show that the proposed algorithm achieves higher successful detection rate.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.329-345
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• 2016

In order to study the community structure and distribution pattern of macrobenthos in the subtidal area of Shia Sea between Haenam peninsula and Shinan-Jindo area at southwest coast of Korea, duplicate sediment samples were taken seasonally by van Veen grab (surface area, $0.1m^2$) from 49 stations between November 2001 and August 2002. The surface sediment facies were muddy sandy gravel near Mokpo-Gu channel, gravel in the Myoungrang channel with high tidal currents, and sandy muddy in the southern Uido area. Ignition loss in the sediment ranged from 0.5 to 1.5% with a mean of 0.6%. A total of 271 taxa were collected with a mean density of $166ind.\;m^{-2}$ and a mean biomass of $29.2g\;m^{-2}$. Polychaetes were dominant faunal group in terms of species richness and abundance, accounting for 34% and 40% of total species number and abundance, respectively. Molluscs accounted for 44% of biomass. Bio-Env analysis revealed that sediment composition and ignition loss affected the spatial distribution of subtidal macrobenthic community in the study area. Major dominant species were Photis longicaudata, Septifer keenae, Maldane cristata, Lumbrineris longifolia, Heteromastus filiformis and Coptothyris grayi. Based on cluster analysis, four station groups were classified. They were associated with sediment types. Bivalve, Striarca symmetrica, polychaetes, Glycera chirori, Heteromastus filiformis and decapod Latreutes planirostris were major contributing fauna in station group A, B, C, and D, respectively. These results suggest that macrobenthic community of the Shia Sea is normally influenced by sediment type and related ignition loss.