• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.87-96
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• 2011

DEVS(Discrete Event Systems Specification) is a set theoretic formalism developed for specifying discrete event system. For execution of DEVS, we need an execution environment, which consists of simulation engine and models interpreted by the simulation engine. Common existing environments use hierarchical scheduling algorithm for DEVS execution. This hierarchical scheduling is a proper algorithm for DEVS execution because of hierarchical and modular characteristics. But this algorithm has overheads owing to message passing and time management. To overcome these overheads, we apply event-oriented simulation to DEVS execution and we remove hierarchical overheads. In eventoriented simulation, the scheduling of model execution is performed by events and event list. We propose three event-oriented execution environments for DEVS and experiment about the performance of our proposed environments in comparison with the existing execution environment using the hierarchical scheduling. The experimental results show our environments works better than existing environment using the hierarchical scheduling.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.27-36
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• 2018

In this paper, we design and implement a real time IoT messaging system that can collect location information of moving vehicles and pedestrians in real time using MQTT protocol and provides location based information service in administrative area. We implemented MQTT based IoT device for vehicle location information collection and communication and MQTT based smartphone application for pedestrian location information service. IoT clients can send messages to the server in administrative units by using the MQTT Topic which is equal to administrative names. The SLIMS (Seoul Location based IoT Messaging System) implemented in this study is able to analyze the real time traffic volume of pedestrians and vehicles by tracking clients. It also can deliver messages to clients based on coordinate range. SLIMS can be used as a real-time location-based information service for large-scale IoT devices such as real-time flow population and vehicle traffic analysis and location-based message delivery.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.3
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• pp.83-89
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• 2010

Scalable routing is one of the key challenges in designing and operating large scale MANETs. Performance of routing protocols proposed so far is only guaranteed under various limitation, i.e., dependent of the number of nodes in the network or needs the location information of destination node. Due to the dependency to the number of nodes in the network, as the number of nodes increases the performance of previous routing protocols degrade dramatically. We propose Cluster Overlay Dynamic Source Routing (CODSR) protocol. We conduct performance analysis by means of computer simulation under various conditions - diameter scaling and density scaling. Developed algorithm outperforms the DSR algorithm, e.g., more than 90% improvement as for the normalized routing load. Operation of CODSR is very simple and we show that the message and time complexity of CODSR is independent of the number of nodes in the network which makes CODSR highly scalable.

• The Journal of Society for e-Business Studies
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• v.16 no.4
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• pp.241-256
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• 2011

The present study examines the impact of eWOM on consumer decision making process by viewing eWOM as the product information supplier. We employ the concept of information entropy which was proposed in the information theory to explain different consumer responses to various types of product information in eWOM. Information entropy is the degree of uncertainty associated with the information in the message. In eWOM, a variety of information with different levels of entropy is available, and these different entropy levels result in different impacts on consumer behavior. The preliminary hypotheses are formulated to examine the impact of eWOM on consumer behavior, at the product attribute level and the purchase action level separately. An experiment was conducted to online shopping mall users and the analysis gives valuable insights into our future research.

• Journal of Venture Innovation
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• v.2 no.1
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• pp.13-21
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• 2019

In LTE environment, which is 4th generation mobile communication systems, there is concern about private information exposure by transmitting initial identifier in plain text. This paper suggest mutual authentication protocol, which uses one-time password utilizing challenge-response and AES-based Milenage key generation algorithm, as solution for safe initial identification communication, preventing unique identification information leaking. Milenage key generation algorithm has been used in LTE Security protocol for generating Cipher key, Integrity key, Message Authentication Code. Performance analysis evaluates the suitability of LTE Security protocol and LTE network by comparing LTE Security protocol with proposed protocol about algorithm operation count and Latency.Thus, this paper figures out initial identification communication's weak points of currently used LTE security protocol and complements in accordance with traditional protocol. So, it can be applied for traditional LTE communication on account of providing additional confidentiality to initial identifier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1958-1968
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• 2015

Things intelligence communication (M2M or IoT) service activation and global company of OneM2M-related business on aggressive investing and has led to the acceleration of change in the ICT market. But a variety of hacking security technology because of the possibility of secure communication (data exposure, theft, modification, deletion, etc.) has been issued as an important requirement. In this paper, we propose a mutual authentication protocol for secure communications chameleon hash based on the M2M environment. The results of performance analysis efficiency is encryption and decryption an average of 0.7%, calculated rate showed good results as compared to the target algorithm, equivalent to a 3%(Average 0.003 seconds) difference, mutual authentication and encryption region by using the key update advantage of ECC(Elliptic Curve Cryptography)based Chameleon hash function is signed of the operational efficiency, using a collision message verifiable properties demonstrated strong security of the communication section.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6C
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• pp.483-491
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• 2012

In vehicle-to-vehicle (V2V) communications, each vehicle should periodically disseminate a beacon message including the kinematics information, such as position, speed, steering, etc., so that a neighbor vehicle can better perceive and predict the movement of the vehicle. However, a simple broadcasting of such messages may lead to a low reception probability as well as an excessive delay. In this paper, we attempt to analyze the impact of the following key parameters of the beacon dissemination on the performance of vehicular networks: beacon period, carrier-sensing range, and contention window (CW) size. We first derive a beacon period which is inversely proportional to the vehicle speed. Next, we mathematically formulate the maximum beacon load to demonstrate the necessity of the transmit power control. We finally present an approximate closed-form solution of the optimal CW size that leads to the maximum throughput of beacon messages in vehicular networks.

• Management & Information Systems Review
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• v.14
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• pp.151-180
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• 2004

Owing to the digital revolution, Internet Commerce and Electronic commerce, revolutionize the way of doing business and making payment. The entrance of the Internet has a prominent for spread of Electronic Commerce and those phenomenons will result in paperless trading and cashless trade. By virtue of Internet, an increasing share of business transactions occurs online. Electronic payment is essential for the smooth progress of the electronic commerce as electronic payment plays the important role in the electronic commerce, that is, the value transfer restyling from the electronic commerce. Traditionally international settlement systems such as letters of credits, remittance and documentary collections operated as important and poplar method of payment, Now, information technology has made it possible to pay for the sale of goods and services over the internet. In international trade, there are service providers (bolero, TradeCard, BeXcom) to settle payment electronically through the Internet. The purpose of this study is to Conduct comparative analysis with approach manner functional respect systematic respect, role. It is shown which the Electronic payment system is better. In this study, the author attempts to find the problems is (bolero, TradeCard, BeXcom) and solutions in switching from the documentary payment system to the electronic one. This conclusion of this study can be summarized as followings. In resoect of the law, bolero should seek to prevert the users from being treated unfairly due to multilateral agreement on Rulebook. TradeCard, BeXcom do not have the proper law that users are governed. so far as the practice problems concerned, stability of computer's operation and security of message interchange should be warranted and improved continuously. Through the standardization of the electronic document and the development of software, the examination of the shipping occuments must be done automatically. Bolero should induce more banks to take part in Bolero, and make the carrier the cost and time in managing the traditional document which will be used for the time being. In respect of information technology and security, to deduce the risk in the electronic settlement system and positively uses the global authentication guideline(Identrus).

• Spatial Information Research
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• v.7 no.2
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• pp.209-221
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• 1999

In this research, AVL-GIS(Automatic Vehicle Location System linked with Geographic Information System) system was developed using integration of core techniques of GIS engine written by Java language, GOS(Global Positioning System) and wireless telecommunication interfacing techniques. IDGPS(Inverted differential GPS) techniques was employed to estimate accurate position of mobile vehicle and to supervise their path from AVL-GLS control center system. Between mobile vehicle and AVL-GLS control center system which has spatial data analysis function, road network and rleate ddata base were connected wireless phone to communicate for position an dmessage in real time. The developed system from this research has more enhanced GIS functions rather than previous AVL oriented system which has MDT for message display and voice communication only. This system can support build-up application system such as fleet management like bus, taxi, truck, disaster and emergency and monitoring of transportation status for customer s order via web browser in filed of EC/CALS in low cost.

• Journal of the Korean Society of Costume
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• v.60 no.9
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• pp.1-15
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• 2010

Fashion designer Jean Paul Gaultier incorporated his own boundless and unique artistic Into his design of dance costumes, presenting an unobstructed imaginary world that was filled with freedom, which is no less than one would expect from the one-time enfant t${\'{e}}$rrible of Paris fashion. This creativity of Gaultier was made possible only through the fantastic partnership he formed with the French modern dancer, R${\'{e}}$gine Chopinot. Gaultier and Chopinot shared a deep-rooted sympathy that enabled their own artistic worlds to fully mingle and cross over, resulting in a doubled synergy of their talent and their fame. This study analyzed 11 dancing costumes created through the collaborated efforts of those two enfants t${\'{e}}$rribles, one from the fashion industry and the other from the world of dance. The following are the results of my analysis. Gaultier's dance costumes served as a artistic venue for experimenting with a number of creative inspirations lurking in his mind, which were sometimes expressed in pr${\^{e}}$t-${\`{a}}$-porter collections. Instead of the decorative and expressive features of conventional dance costumes, his was the revival of the dancer's persona as a human being, ablaze with individuality and uniqueness. He pointed out that there is no good in the distorted turturro's fixed point of view, and the great joy of an opposing way of thinking that overturned the established. Leotard material was used as a second skin by transforming it into various styles and delivering his message. In addition, obscene and sexual expressions were delivered in a direct narrative. His eccentric ideas provided entertainment while showing his oppositional way of thinking. In the dance, the effect of the costumes was doubled by the use of cumbersome and exaggerated accessories, which is generally forbidden in modern dance.