• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3C
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• pp.224-232
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• 2012

Priority MAC is an important issue in every communication system when we consider differentiated service applications. In this paper, we propose a mechanism to support priority MAC based on multi-parameters for IEEE 802.15.7 visible light communication (VLC). By using three parameters such as number of backoff times (NB), backoff exponent (BE) and contention window (CW), we provide priority for multi-level differentiated service applications. We consider beacon-enabled VLC personal area network (VPAN) mode with slotted version for random access algorithm in this paper. Based on a discrete-time Markov chain, we analyze the performance of proposed mechanism under non-saturation environments. By building a Markov chain model for multi-parameters, this paper presents the throughput and transmission delay time for VLC system. Numerical results show that we can apply three parameters to control the priority for VLC MAC protocol.

• Korean Journal of Veterinary Service
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• v.23 no.3
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• pp.227-233
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• 2000

Salmonella enteritidis is the most prevalent etiologic agents of foodborne acute gastroenteritis. Direct isolation and identification of S enteritidis are time consuming work and not so highly sensitive. This study was conducted to develop for the specific detection of S enteritidis using polymerase chain reaction(PCR). PCR primers were selected to amplify a 351-base pair(bp) DNA fragment from the salmonella plasmid virulence A(spv A) gene of S enteritidis. With the primers, 351 bp DNA products were amplified from S enteritidis but not from other B, D, Cl serogroup Salmonella spp. It was sensitive to detect up to 40 pg of template DNA by agarose gel electrophoresis. This PCR assay is very rapid and specific method and less time consuming than the standard bacteriological methods.

• Management Science and Financial Engineering
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• v.10 no.2
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• pp.1-28
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• 2004

The integrated supply chain of business partners for e-Commerce in cyber space is defined as Logistics Chain if the cooperative activities are logistics-related. Logistics Chain could be managed effectively and efficiently by cooperative technologies of logistics chain execution. In this paper, we propose a routing and scheduling algorithm based on the Tabu search by adding geographical information into existing constraint for pick-up and delivery process to minimize service time and cost in logistics chain. And, we also consider an uncertainty processing for the tracing of moving object to control pick-up and delivery vehicles based on GPS/GIS/ITS. Uncertainty processing is required to minimize amount of telecommunication and database on vehicles tracing. Finally, we describe the Logistics Chain Execution (LCE) system to perform plan and control activities for postal logistics chain. To evaluate practical effects of the routing and scheduling system, we perform a pretest for the performance of the tabu search algorithm. And then we compare our result with the result of the pick-up and delivery routing plan generated manually by postmen.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.9
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• pp.3858-3869
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• 2020

In this paper, we propose a hash-chain based friendly force identification protocol for personal combatants equipped with a personal combat system in a tactical wireless network. It is imperative in military operations to effectively and quickly identify friendly forces. If the identification of friendly forces is not correct, this can cause friendly fire. In current ground operations, the identification of friendly forces by personal combatants is neither secure nor safe. To address this issue, the proposed protocol uses a hash-chain to determine if a detected person is friendly. Only friendly forces with the same materials that are assigned before they deploy can construct an initial hash-chain. Moreover, the hash-chain is changed at specific times. The performance of the proposed protocol is evaluated on the assumption that the secret key is leaked, which is the worst scenario in the security research field. We verify that the proposed protocol is secure for the various attack scenarios, such as message replay attack, fabrication attack, and Denial of Service attack.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.5
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• pp.511-520
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• 2015

Inventory, cost, and the level of service are three interrelated key metrics that most supply chain organizations are striving to optimize. One way to achieve this goal is to create a simulation model to conduct sensitivity analysis and optimization on several different supply chain policies that can be implemented in actual operation. In this paper, a case of Xerox global supply chain modeling and analysis to assess several "what if" scenarios for the consumable policy safety stock is presented. The simulation model, combined with analytical cost model and optimization module, is used to optimize the policy safety stock level to achieve the lowest total value chain cost. It was shown quantitatively that the policy safety stock can be reduced, but it is offset by the inbound premium transportation cost to expedite supplies in shortage, and the outbound premium transportation cost to send supplies to customers via express shipment, requiring fine balance.

• Journal of Korea Multimedia Society
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• v.6 no.7
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• pp.1219-1230
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• 2003

We analyze an integrated voice/data CDMA system, where the whole channels are divided into voice prioritized channels and voice non-prioritized channels. For real-time voice service, a preemptivc priority is granted in the voice prioritized channels. And, for delay-tolerant data service, the employment of buffer is considered. On the other hand, the transmission permission probability in best-effort packet-data service is controlled by estimating the residual capacity available for users. We build a 2-dimensional markov chain about prioritized-voice and stream-data services and accomplish numerical analysis in combination with packet-data traffic based on residual capacity equation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.1
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• pp.81-88
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• 2013

As social network service(SNS) has grown rapidly, the variety information being shared through SNS. However, the privacy of individuals can be violated due to the shared information through a SNS or the post written in the past at the SNS. Although, many researches concerned about it, they did not suggest key management and access control especially. In this paper, we propose the method for the protection of the message in SNS using access control and hash-chain.

• Journal of Distribution Science
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• v.22 no.7
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• pp.95-106
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• 2024

Purpose: This study explores the effect on supply chain agility and logistics performance of building mutual trust between manufacturing companies that have adopted supply chain management. Previous studies have categorized trust into affective and cognitive types, and speed, flexibility, and responsiveness are recognized as subfactors of supply chain agility. Methodology: A survey gathered responses from employees of domestic manufacturing firms with supply chain management implementations. 254 valid responses underwent statistical analysis using structural equation modeling (SPSS 23.0 and AMOS 23.0). Results: Affective trust positively influences speed and responsiveness but not flexibility. Cognitive trust positively affects speed, flexibility, and responsiveness. Supply chain agility positively impacts logistics performance. However, neither affective nor cognitive trust significantly influences logistics performance. Conclusions: The study suggests that cognitive trust based on capabilities is more important than affective trust for flexibility in corporate relationships, a subfactor of supply chain agility. However, trust alone cannot enhance corporate performance. This research is significant as it examines the roles of trust and agility in the context of the COVID-19 pandemic, which has exacerbated the manufacturing business environment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.2
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• pp.29-36
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• 2007

This study was concerned about mobile web-service of a VMI in the SCM system. The VMI would be a main module part of the SCM and regarded as very important thing on supply chain. Therefore, it was essential to react in real time of materials production and situation of used auto-part in procurement company. We could find an affordable method to realize the VMI in a web service. The web service has made inter relevant enterprise easy to collaborate because of supporting most operating system and frame-work. Moreover, the use of a mobile tools was guaranteed a product recording and requirement of materials to real time in a rapid changing of production environments. The result of this research was very useful to apply the VMI system in medium and small sized auto parts company. This web service package has programmed the Visual Studio Dot Net 2003 and the MS SQL 2000 as database.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.9
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• pp.828-840
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• 2014

There is a new evolution in technological advancement taking place called the Internet of Things (IoT). The IoT enables physical world objects in our surroundings to be connected to the Internet. For this idea to come to life, two architectures are required: the Sensing Entity in the environment which collects data and connects to the cloud and the Cloud Service that hosts the data. In particular, the combination of wireless sensor network for sensing and cloud computing for managing sensor data is becoming a popular intervention for the IoT era. The pharmaceutical cold chain requires controlled environmental conditions for the sensitive products in order for them to maintain their potency and fit for consumption. The monitoring of distribution process is the only assurance that a process has been successfully validated. The distribution process is so critical that anomaly at any point will result in the process being no longer valid. Taking the cold chain monitoring to IoT and using its benefits and power will result in better management and product handling in the cold chain. In this paper, Arduino based wireless sensor network for storage and logistics (land and sea) is presented and integrated with Xively cloud service to offer a real-time and innovative solution for pharmaceutical cold chain monitoring.