• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.2
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• pp.105-115
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• 2005

By committing to a long-term replenishment contract, buyers can purchase a product at a lower price from a supplier who is less pressured to find new customers due to the long-term contract and can charge a discounted price. We develop an analytical model from the buyer's perspective to investigate a capacity reservation contract. We are considering the system with a single supplier and a buyer. The buyer can purchases any desired amount from a spot market at a higher price in addition to the contracted amount. For such a system, we propose an algorithm to derive the optimal contract terms. The result of computational experiments shows that the algorithm finds the global optimum solution in a resonable amount of time.

• The Transactions of the Korea Information Processing Society
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• v.6 no.10
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• pp.2790-2796
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• 1999

In video-on-demand systems, the I.O bandwidth of video servers is the critical resource which contributes to increase in latency. Several approaches: bridging, piggybacking are used to reduce the I/O demand on the video server through sharing. Batching delays the requests for the different videos for a batching window so that more requests for the same video arriving during the current batching window may be served using the same stream. In this paper, we propose an adaptive reservation-based batching policy which dynamically reserves video server capacity for popoular videos according to video server loads. The performance of the proposed policy is evaluated through a simulation, and is compared with simple batching and static reservation-based batching policies. As the result, we know that the adaptive reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching policy more improves service ratio and average waiting time than simple batching and simple reservation-based batching polices.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.12-18
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• 2018

As of 2016, the cremation rates in the capital area are 91.2% in Incheon Metropolitan City, 87.5% in Seoul Special City, and 87.1% in Gyeonggi-do Province, of which Incheon has the highest rate, and cremation of general corpses through the online cremation reservation service of the funeral information system is continuously increasing every year. And as of 2017, the ratio of the cremation for those outside the jurisdiction (residents of other regions) among the users of public cremation establishment in Incheon, is about 32%. As the supply capacity is expected to reach the limit within several years due to the increase in demand for such a cremation facility, I would like to suggest a policy as follows. The expansion of cremation supply capacity by increasing the number of operations in the cremation furnace; The attractions of operating funds through contracts for joint use of the cremation facility with other local governments and investment funds for the expansion of cremation facilities; The plan for controlling the demand in cremation such as an increase in cremation charge for those outside the jurisdiction(residents of other regions), should be considered.

• Journal of Navigation and Port Research
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• v.41 no.2
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• pp.63-70
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• 2017

Despite the remarkable continual growth of the world cruise industry, studies have yet to be attempted on many revenue management problems in cruise operations. This paper suggests two schemes that can be easily applied to cruise revenue management: optimal dual pricing and passenger safety level. In optimal dual pricing, a pair of higher and lower prices is applied to cabin reservation through market segmentation. This scheme can be executed with a linear price-response function for the current unreserved cabins. A cruise line could benefit from this scheme to maximize reservation revenue while attaining full occupancy. The dual pricing scheme is also devised to produce only integer demands to suit real management practices. The life boat capacity is an additional service capacity unique to the cruise industry, catering to passengers' safety. The concept of passenger safety level is defined and computed for any passenger life boat capacity of a cruise ship. It can be used to evaluate the passenger safety of a cruise ship in operation, as well as to determine the number of life boat seats required for a new cruise ship. Hypothetical examples are used to illustrate the operation of these two schemes.

• ETRI Journal
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• v.23 no.2
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• pp.52-60
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• 2001

In this paper, a medium access control protocol is proposed for integrated voice and data services in wireless local networks. Uplink channels for the proposed protocol are composed of time slots with multiple spreading codes per slot based on slotted code division multiple access (CDMA) systems. The proposed protocol uses spreading code sensing and reservation schemes. This protocol gives higher access priority to delay-sensitive voice traffic than to data traffic. The voice terminal reserves an available spreading code to transmit multiple voice packets during a talkspurt. On the other hand, the data terminal transmits a packet without making a reservation over one of the available spreading codes that are not used by voice terminals. In this protocol, voice packets do not come into collision with data packets. The numerical results show that this protocol can increase the system capacity for voice service by applying the reservation scheme. The performance for data traffic will decrease in the case of high voice traffic load because of its low access priority. But it shows that the data traffic performance can be increased in proportion to the number of spreading codes.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.656-665
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• 2000

A critical issue in the performance of a video-on-demand system is the I/O bandwidth required in order to satisfy client requests. Several approaches: batching, bridging, piggybacking are used ot reduce the I/O demand on the video server through sharing. Piggybacking is the policy for altering display rates of requests in progress fro the same object, for the purpose of merging their corresponding I/O streams into a single stream, which can serve the entire group of merged requests. In this paper, we propose a new policy called an adaptive reservation-based piggybacking that dynamically reserves the I/O stream capacity of video server for popular videos according to video server loads to immediately schedule the requests for popular videos. The performance of the proposed policy is evaluated through simulations, and is compared with that of simple piggybacking. As the result, we know that the adaptive reservation-based piggybacking provides better service probability, average waiting time and percentages saving in frames than simple piggybacking.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4356-4371
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• 2014

When the load in a multi-cell orthogonal frequency division multiple access (OFDMA) system is allowed to excessively increase in face of frequent handover, the cell area becomes smaller than the designed size, and thus continuity of quality of service (QoS) for handover requests cannot be guaranteed. To efficiently support the mobility of a mobile terminal (MT), we should adaptively cope with the resource demand of handover calls. This paper proposes a twofold resource-reservation scheme for OFDMA systems to guarantee continuity of QoS for various mobile multimedia services during MT handover from lightly to heavily loaded cells. Our twofold scheme attempts to guarantee service continuity for handover and to maximize resource allocation efficiency. We performed a simulation to evaluate our scheme in terms of outage probability, handover failure rate, total throughput, and blocking rate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.237-241
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• 2003

To improve competitive power of the container terminal, we must enhance the yark efficiency of a domestic container terminal in the chronic shortage situation, Therefore, we investigate the basic concept and the expected effect delivery reservation when applying at existing container terminal.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.1
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• pp.32-43
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• 2000

In this paper, we investigate the existing medium access control (MAC) protocols to integrate the voice and data services in packet-based CDMA networks and furthermore, propose a new approach to circumvent the operational limits inherent in them. We propose the $P^2R$-CDMA (Prioritized Packet Reservation Code Division Multiple Access) protocol for the uplink in the synchronous multi-code CDMA system, which employs the centralized frame-based slot reservation along with the dynamic slot assignment in the base station using the QoS-oriented dynamic priority of individual terminal. The simulation results show that, as compared with the existing scheme based on the adaptive permission probability control (APC), the proposed approach can significantly improve the system capacity while guaranteeing the real-time requirement of voice service.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.64
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• pp.53-62
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• 2001

In make-to-order manufacturing, if orders are processed and promise first-served base, then the urgent orders from important customers in .practice, orders are not confirmed upon receipt; and delayed as uncertainty of due date causes significant waste of cost and time. propose a new concept of reserved capacity as an alternative to accommodate the urgent orders from important customers, while the due dale of all of orders arrival; and suggest a flew operational policies.