• 지능정보연구
• /
• 제12권2호
• /
• pp.99-123
• /
• 2006

본 연구는 최적의 공급사슬을 구성하기 위해 다수의 주문을 다수의 참여자에게 할당하기 위한 방법으로 에이전트 협상을 이용하였다. 본 에이전트 협상은 투명한 정보공유를 바탕으로 참여자간의 전략적 협력관계를 형성하기 위한 조정 메커니즘을 제공하고 있으며, 모든 참여자(주문자, 제조자, 공급자)가 자신의 이득을 달성하고, 공급사슬 전체 관점에서도 파레토 최적해가 달성됨을 보여주고 있다. SET 모델기반의 스케줄링에서 지연생산비용과 조기생산비용이 발생되고, 경쟁적 관계에 놓인 다수의 참여자를 고려하였다. 이러한 동적공급사슬 환경에서 에이전트 협상의 결과가 파레토 최적해임을 증명하고, 성능을 검증하기 위해 수리적 모형을 수립하고, 휴리스틱 방법론과 비교하는 실험을 진행하였다.

• Industrial Engineering and Management Systems
• /
• 제8권2호
• /
• pp.80-92
• /
• 2009

This paper addresses the inventory rationing issue embedded in the regional supply chain inventory replenishment problem (RSIRP). The concerned supply chain, which was fed by the national supply chain, consisted of a single warehouse distributing a single product to multiple stores (M-stores) with independent and normally distributed customer demand. It was assumed that the supply chain operated under the order-up-to level inventory replenishment system and had only one truck at the regional warehouse. The truck could make one replenishment trip to one store per period (a round trip per period). Based on current inventories and the vehicle constraint, the warehouse must make two decisions in each period: which store in the region to replenish and what was the replenishment quantity? The objective was to position inventories so as to minimize lost sales in the region. The warehouse inventory was replenished in every fixed-interval from a source outside the region, but the store inventory could be replenished daily. The truck destination (store) in each period was selected based on its maximum expected shortage. The replenishment quantity was then determined based on the predetermined order-up-to level system. In case of insufficient warehouse inventories to fulfill all projected store demands, an inventory rationing rule must be applied. In this paper, a new inventory rationing rule named Expected Cost Minimization (ECM) was proposed based on the practical purpose. The numerical results based on real data from a selective industry show that its performance was better and more robust than the current practice and other sharing rules in the existing literature.

• The Plant Pathology Journal
• /
• 제29권3호
• /
• pp.338-343
• /
• 2013

A detection system based on a multiplex reverse transcription (RT) polymerase chain reaction (PCR) was developed to simultaneously identify multiple viruses in the lily plant. The most common viruses infecting lily plants are the cucumber mosaic virus (CMV), lily mottle virus (LMoV), lily symptomless virus (LSV). Leaf samples were collected at lily-cultivation facilities located in the Kangwon province of Korea and used to evaluate the detection system. Simplex and multiplex RT-PCR were performed using virus-specific primers to detect single- or mixed viral infections in lily plants. Our results demonstrate the selective detection of 3 different viruses (CMV, LMoV and LSV) by using specific primers as well as the potential of simultaneously detecting 2 or 3 different viruses in lily plants with mixed infections. Three sets of primers for each target virus, and one set of internal control primers were used to evaluate the detection system for efficiency, reliability, and reproducibility.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권5호
• /
• pp.2499-2522
• /
• 2017

Multi-hop networks are a low-setup-cost solution for enlarging an area of network coverage through multi-hop routing. Carrier sense multiple access with collision avoidance (CSMA/CA) is frequently used in multi-hop networks. Multi-hop networks face multiple problems, such as a rise in contention for the medium, and packet loss under heavy-load, saturated conditions, which consumes more bandwidth due to re-transmissions. The number of re-transmissions carried out in a multi-hop network plays a major role in the achievable quality of service (QoS). This paper presents a statistical, analytical model for the end-to-end delay of contention-based medium access control (MAC) strategies. These strategies schedule a packet before performing the back-off contention for both differentiated heterogeneous data and homogeneous data under saturation conditions. The analytical model is an application of Markov chain theory and queuing theory. The M/M/1 model is used to derive access queue waiting times, and an absorbing Markov chain is used to determine the expected number of re-transmissions in a multi-hop scenario. This is then used to calculate the expected end-to-end delay. The prediction by the proposed model is compared to the simulation results, and shows close correlation for the different test cases with different arrival rates.

• Industrial Engineering and Management Systems
• /
• 제11권4호
• /
• pp.397-405
• /
• 2012

This research proposes a framework of buffer management for multi-project systems in the critical chain project management (CCPM) method, expressed in the form of max-plus linear (MPL) representation. Since time buffers are inserted in the projects for absorbing uncertainties in task durations and protecting the completion times, the proposed method provides a procedure for frequently surveying the rates of consumed buffers and the rate of elapsed times. Their relation expresses the performance of the projects which is plotted on a chart through the completed processes. The chart presents the current performance of the projects and their interaction, which alerts managers to make necessary decisions at the right time for managing each project and the entire multi-project system. The proposed framework can analyze the complex system readily, and it enables managers to make an effective decision on scheduling. The effectiveness of the framework is demonstrated through a numerical example.

• Journal of Communications and Networks
• /
• 제14권5호
• /
• pp.578-587
• /
• 2012

One of the key elements in the emerging, packet-based long term evolution (LTE) cellular systems is the deployment of multiple femtocells for the improvement of coverage and data rate. However, arbitrary overlaps in the coverage of these femtocells make the handover operation more complex and challenging. As the existing handover strategy of LTE systems considers only carrier to interference plus noise ratio (CINR), it often suffers from resource constraints in the target femtocell, thereby leading to handover failure. In this paper, we propose a new efficient, multi-objective handover solution for LTE cellular systems. The proposed solution considers multiple parameters like signal strength and available bandwidth in the selection of the optimal target cell. This results in a significant increase in the handover success rate, thereby reducing the blocking of handover and new sessions. The overall handover process is modeled and analyzed by a three-dimensional Markov chain. The analytical results for the major performance metrics closely resemble the simulation results. The simulation results show that the proposed multi-objective handover offers considerable improvement in the session blocking rates, session queuing delay, handover latency, and goodput during handover.

• Communications for Statistical Applications and Methods
• /
• 제27권2호
• /
• pp.189-199
• /
• 2020

This paper studies a Bayesian ordered multiple linear regression model with skew normal error. It is reasonable that the kind of inherent information available in an applied regression requires some constraints on the coefficients to be estimated. In addition, the assumption of normality of the errors is sometimes not appropriate in the real data. Therefore, to explain such situations more flexibly, we use the skew-normal distribution given by Sahu et al. (The Canadian Journal of Statistics, 31, 129-150, 2003) for error-terms including normal distribution. For Bayesian methodology, the Markov chain Monte Carlo method is employed to resolve complicated integration problems. Also, under the improper priors, the propriety of the associated posterior density is shown. Our Bayesian proposed model is applied to NZAPB's apple data. For model comparison between the skew normal error model and the normal error model, we use the Bayes factor and deviance information criterion given by Spiegelhalter et al. (Journal of the Royal Statistical Society Series B (Statistical Methodology), 64, 583-639, 2002). We also consider the problem of detecting an influential point concerning skewness using Bayes factors. Finally, concluding remarks are discussed.

• Journal of Audiology & Otology
• /
• 제25권3호
• /
• pp.159-162
• /
• 2021

Temporal bone trauma can cause hearing loss and in case of prolonged conductive hearing loss, traumatic ossicular injury should be considered. Separation of the incudostapedial joint is the most common lesion, and stapediovestibular dislocation is relatively rare but can easily cause perilymphatic fistula. Here, we report a very rare case of external stapediovestibular dislocation after trauma, ending up with successful surgical outcome. A 27-year-old man with non-progressive hearing loss on the right side since childhood visited the clinic. Audiogram showed a conductive hearing loss with air-bone gap of 55 dB on the right side. Temporal bone CT revealed the disruption of ossicular chain. An exploratory tympanotomy identified multiple ossicular disruptions including external stapediovestibular dislocation with shiny fibrous membrane sealing the oval window. Ossicular chain reconstruction was performed using the total ossicular replacement prosthesis of titanium. A postoperative audiogram showed a recovery of air-bone gap less than 10 dB. To the best of our knowledge, this is the first case of external long-standing stapediovestibular dislocation, with oval window completely sealed with fibrous membrane, ending up with successful hearing recovery by surgery. This case would help dealing with such condition which can be encountered in the clinic.

• 대한청각학회지
• /
• 제25권3호
• /
• pp.159-162
• /
• 2021

Temporal bone trauma can cause hearing loss and in case of prolonged conductive hearing loss, traumatic ossicular injury should be considered. Separation of the incudostapedial joint is the most common lesion, and stapediovestibular dislocation is relatively rare but can easily cause perilymphatic fistula. Here, we report a very rare case of external stapediovestibular dislocation after trauma, ending up with successful surgical outcome. A 27-year-old man with non-progressive hearing loss on the right side since childhood visited the clinic. Audiogram showed a conductive hearing loss with air-bone gap of 55 dB on the right side. Temporal bone CT revealed the disruption of ossicular chain. An exploratory tympanotomy identified multiple ossicular disruptions including external stapediovestibular dislocation with shiny fibrous membrane sealing the oval window. Ossicular chain reconstruction was performed using the total ossicular replacement prosthesis of titanium. A postoperative audiogram showed a recovery of air-bone gap less than 10 dB. To the best of our knowledge, this is the first case of external long-standing stapediovestibular dislocation, with oval window completely sealed with fibrous membrane, ending up with successful hearing recovery by surgery. This case would help dealing with such condition which can be encountered in the clinic.

• 한국전자통신학회논문지
• /
• 제18권4호
• /
• pp.579-586
• /
• 2023

무선 센서 네트워크(Wireless Sensor Network : WSN)는 저가의 소형 센서를 활용해서 무선으로 사용되기 때문에 제한된 배터리 전력을 가지고 있다. 배터리를 교체할 수 없으므로 센서 노드의 수명은 배터리의 수명과 직결되므로 전력을 효율적으로 사용하여 네트워크의 수명을 극대화해야 한다. 본 연구에서는 대표적인 에너지 효율적 라우팅 프로토콜인 PEGASIS(: Power-Efficient Gathering in Sensor Information System)를 기반으로 싱크 노드로부터의 거리에 따라 계층화하여 하나의 체인이 아닌 다중 체인을 구성하는 프로토콜을 제안한다. 제안하는 프로토콜은 노드 간 전송 거리를 줄여서 불필요한 에너지 소모를 막아 네트워크 수명을 높일 수 있음을 확인하였다.