• Korean Management Science Review
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• v.26 no.3
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• pp.117-131
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• 2009

Over the last three decades, there are many researches focusing on the practice and theory of RM in airlines. Most of them have dealt with a seat assignment problem for maximizing the total revenue. In this study, we focus on a seat assignment problem in airlines. The seat assignment problem can be modeled as a stochastic programming model which is difficulty to solve optimally. However, with some assumptions on the demand distribution functions and a linear approximation technique, we can transform the complex stochastic programming model to a Linear Programming model. Some computational experiments are performed to evaluate out model with randomly generated data. They show that our model has a good performance comparing to existing models, and can be considered as a basis for further studies on improving existing seat assignment models.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.3
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• pp.46-55
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• 2001

Following the previous paper on development of the spatial location-allocation model of center villages (SLAMCV), this paper, the 2nd stage of the this study, aims to check up its applicability for several planning scenarios by the case study. Among 72 natural villages of Ucheon-myeon, Gangwon-do, Korea the highest single center was simulated as Uhang village and the higher double centers as Uhang and Jeonggeum villages, which coincided exactly with the existing centers. The SLAMCV was well operated for three planning scenarios such as selection of the 3rd center village and its hinter villages for Ucheon-myeon, Gargwon-do, Korea by dividing three living spheres, impact assessment evaluation of road improvement projects on the spatial accessibility, and analysis of centerality changes of settlement units by new road construction.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.120-127
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• 2002

The multicasting is defined as the distribution of the same information stream from one to many nodes concurrently. There has been an intensive research effort to design protocols and construct multicast routing graphs for a single multicast group. However. there have been few researches about the relation between multiple and concurrent multicast groups. In this paper, the multiple multicast tree allocation algorithm to avoid congestion is proposed. The multicast group with different bandwidth requirement is also considered. A two-phase algorithm is proposed. The first phase is for basic search and the second phase for further improvement. The performance of the proposed algorithm is experimented with computational results. Computational results show that the proposed algorithm outperforms an existing algorithm.

• Journal of the Korean Data and Information Science Society
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• v.10 no.1
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• pp.79-89
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• 1999

A counting rule that allows an element to be linked to more than one enumeration unit is called a multiplicity counting rule. Sample designs that use multiplicity counting rules are called network samples. Defining a network to be a set of observation units with a given linkage pattern, a network may be linked with more than one selection unit, and a single selection unit may be linked with more than one network. This paper considers allocation for multivariate stratified random sampling with multiplicity.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.60-64
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• 1999

Recently in manufacturing environment, manufacturing order is characterized by unstable market demand, shorter product life cycle, a variety of product and shorter production lead time. In order to adapt this manufacturing order, flexible manufacturing system(FMS) in manufacturing technology advances into the direction that machines become further versatile functionally and that tools are controlled by fast tool delivery device. Unlike conventional FMS to mainly focus on part flow, it is important to control tool flow in single-stage multimachine systems(SSMS), consisting of versatile machines and fast tool delivery device. In this paper, in SSMS under dynamic tool allocation strategy to share tools among machines, we propose real-time part release and tool allocation algorithms which can apply real factory and which can improve system performance.

• Journal of Applied Reliability
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• v.1 no.1
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• pp.1-8
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• 2001

Redundancy allocation problems have been considered at single-level systems and it may be the best policy in some specific situations, but not in general. With regards to reliability, it is most effective to allocate the lowest objects, because parallel-series systems are more reliable than series-parallel systems. However, the smaller and lower in the system an object is, the more time and accuracy are needed for duplicating it, and so, the cost can be decreased by using modular redundancy Therefore, providing redundancy at high levels like as modules or subsystems, can be more economical than providing redundancy at low levels or duplicating components. In this paper, the problem in which redundancy is allocated at all level in a series system is addressed, a mixed integer nonlinear programming model is presented and a genetic algorithm is proposed. An example illustrates the procedure.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.4
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• pp.541-553
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• 1995

An efficient algorithm is proposed for a buffer allocation in a continuous flow line. The problem is formulated as a non-linear programming with linear constraints. The concept of pseudo gradient and gradient projection is employed in developing the algorithm. Numerical experiments show that the algorithm gives the actual optimal solutions to the problems with single linear constraint limiting the total buffer capacity. Also, even in longer production lines, it gives quite good solutions to the problems with the general linear resource constraints within a few seconds.

• Journal of IKEEE
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• v.23 no.2
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• pp.735-738
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• 2019

Recently, orthogonal non-orthogonal multiple access (O NOMA) with polar on-off keying (POOK) has been proposed to mitigate the severe effect of the superposition. However, it is observed that the performance of the O NOMA strong channel user is better than that of the perfect successive interference cancellation (SIC), i.e., the performance of a single user transmission with binary phase shift keying (BPSK). Can the performance of the BPSK modulation be better that that of itself? It is not normal. It should be clearly understood theoretically, with the ultimate bound, i.e., the channel capacity. This paper proves that the channel capacity of the O NOMA strong channel user is non-zero with zero power allocation. Thus, it is shown that the interference is transformed effectively into the meaningful signal.

• Journal of Families and Better Life
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• v.20 no.6
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• pp.197-208
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• 2002

The purpose of this study was to investigate the economic lives of single households with the age of 30 through less than 50. The economic life was examined in three aspects; income, assets, and consumption expenditures and patterns. One hundred sixty single households were surveyed, with questionnaires for 15days from April 1 to April 15 of 2002, and analyzed with descriptive statistics. The results were as follows: about 30.8% of total single households in the sample were in the income group of 1,500,000 thought less than 2,000,000 won. The size of income for the 30's was less than that for the 40's. Compared with male single households, female single households were more in both low and high levels of income. The saving rate tended more or less to be low. The more the age, the higher the saving rate. As for debt, the 40's single households, male single households, high school single households (compared to the 30's single households, female single households, university and graduate single households, respectively) were relatively higher. In general, the single households tended to have debts due to preparation for housing, credit over use. The assets tended to be managed by themselves. The economic preparation for the old life was done by banking system rather than insurance. The average monthly living costs was higher in the age of the 40's single than the age of the 30's single. The living costs of the female single households was higher or lower than those of the male single households. As for consumption patterns, there was the most in the expenditure allocation for food away from home, then for culture entertainmentㆍsocial life, and for clothing and shoes. As for the convenience of the consumption life in overall, there were more responses in moderation and inconvenience than in convenience.

• Journal of the Korea Society for Simulation
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• v.28 no.1
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• pp.1-9
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• 2019

Recently, as the importance of warehouses has increased, much efforts are being made to improve the picking process in order to cope with a small amount of high frequency and fast delivery. This study proposes an algorithm to assign orders to pickers in the situation where Single Order Picking policy is used. This algorithm utilizes five attributes related to picking such as picking processing time, elapsed time after receipt of order, inspection/packing workstation situation, picker error, customer importance. A measure of urgency is introduced so that the units of measure for each attribute are the same. The higher the urgency, the higher the allocation priority. In the proposed algorithm, the allocation policy can be flexibly adjusted according to the operational goal of the picking system by changing the weight of each attribute. Simulation experiments were performed on a hypothetical small logistics warehouse. The results showed excellent performance in terms of system throughput and flow time.