• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.141-147
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• 1991

This paper presents extended model for the vehicle routing problem, which allows multiple visits to a node by multiple vehicles. Multiple visits enables us split delivery. After formulating this multiple visits model mathematically, a two stage heuristic algorithm is developed by decomposition approach. This model consists of two sub-problem. The one is fixed cost transportation problem and the other is transportation problem.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1740-1745
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• 2006

This paper is concerned with a novel heuristic algorithm for the multi-trip vehicle routing problem with time windows. The objective function is the minimization of total vehicle operating time, fixed cost of vehicle and the minimization of total lateness of customer. A mixed integer programming formulation and a heuristic algorithm for a practical use are suggested. A heuristic algorithm is constructed two phases such as clustering and routing. Clustering is progressed in order to assign appropriate vehicle to customer, and then vehicle trip and route are decided considering traveling distance and time window. It is shown that the suggested heuristic algorithm gives good solutions within a short computation time by experimental result.

• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.89-97
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• 2004

The Korea Air Force(KAF) has operated freight flights based on the prefixed time and route schedule, which is adjusted once in a month. The major purpose of the operation of freight flights in the KAF is to distribute necessary supplies from the home air base to other air bases. The secondary purpose is to train the young pilots to get more experiences in navigation. Each freight flight starts from and returned to the home air base everyday except holidays, while it visits several other air bases to accomplish its missions. The study aims to forecast freight demand at each base by using time series analysis, and then it tried to optimize the cost of operating flights by solving vehicle routing problem. For more specifically, first, several constraints in operating cargos were defined by reviewing the Korea Air Force manuals and regulation. With such constraints, an integer programming problem was formulated for this specific routing problem allowing several visits in a tour with limitation of maximum number of visits. Then, an algorithm to solve the routing problem was developed. Second, the time series analysis method was applied to find out the freight demand at each air base from the mother air base in the next month. With the forecasted demands and the developed solution algorithm, the oprimum routes are calculated for each flight. Finally, the study compared the solved routing system by the developed algorithm with the existing routing system of the Korea Air Force. Through this comparison, the study proved that the proposed method can provide more (economically) efficient routing system than the existing system in terms of computing and monetary cost. In summary, the study suggested objective criteria for air routing plan in the KAF. It also developed the methods which could forecast properly the freight demands at each bases by using time series analysis and which could find the optimum routing which minimizes number of cargo needed. Finally, the study showed the economical savings with the optimized routing system by using real case example.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.1
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• pp.63-70
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• 2009

Objective: This study was performed to investigate the effectiveness of minimal stimulation using rhFSH and GnRH antagonist compared with GnRH antagonist multidose protocol (MDP) in IVF treated patients with aged 40 and above. Methods: Seventy-five patients with aged 40 and above were equally randomized to minimal stimulation group (n=37) or GnRH antagonist MDP group (n=38). For minimal stimulation group, ultrasound monitoring was started on cycle day 7 or 8. Daily injections of 0.25 mg cetrorelix together with 150 IU rhFSH were started from the day at 13${\sim}$14 mm of a leading follicle diameter. For GnRH antagonist MDP group, daily injections of 225 IU rhFSH were initiated from cycle day 2 and GnRH antagonist was started at a dose of 0.25 mg/day on rhFSH stimulation day 6 or the day at 13${\sim}$14 mm of leading follicle diameter. In both groups, transvaginal ultrasound-guided oocyte retrieval was performed. According to cleavage and morphologic characteristics of embryos, embryos were transferred 3 to 5 days after oocyte retrieval. Results: There were no differences in patients' characteristics and cycle cancellation rate between the two groups. Total dose and duration of rhFSH used were significantly fewer and shorter in minimal stimulation group than those in GnRH antagonist MDP group. The numbers of oocytes retrieved, mature oocytes and transferred embryos were also lower in minimal stimulation group. However, there were no significant differences in the clinical pregnancy rate and miscarriage rate between the two groups. Conclusions: This study demonstrates that minimal stimulation protocol provides comparable pregnancy rates to GnRH antagonist MDP with fewer dose and days of rhFSH used, and thus can be a cost-effective alternative in women aged 40 and above.

• Journal of Yeungnam Medical Science
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• v.6 no.2
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• pp.159-172
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• 1989

This study was conducted to compare the date on knowledge, attitude and motivation toward blood donation between donors and nondonors. The study population included 622 donors and 322 nondonors who visited the mobile blood donation car of Taegu Red Cross Blood Center and participated the group appointed blood donation campaign managed by the center from March 1 to March 31, 1989. The donors and nondonors were questioned above mentioned items with a formulated questionnaire. Among the general characteristics of the subjects in the study, male predominace(84.1% in donors and 73.6% in nondonors) in young age group (16-24 years) was the outstanding feature. As a medium of information about blood donation, "television" was playing a dominant role(donors ; 75.2%, nondonors ; 78.9%), while "magazine"played more important roles among donors. Of the donors, 70.6% and of the nondonors, 58.1% replied that they had ever been induced to donate blood (p<0.01). Major inducers were friend and personnel of mobile blood donation vehicle. On the measuring of knowledge level, the average rates of correct answer was higher in donors (62.6%) than in nondonors (54.1%) (p<0.01). Higher the education level was presented, higher the knowledge level (p<0.05). There have been noticeable difference between donors and nondonors in blood replying the questionnaire set to measure their attitude toward blood donation. especially in the items such as "impression toward blood", "selection of transfusion blood source" and "view on the situation of blood shortage." The major motivation toward blood donation of the groups were "possible future need" and "altruism or humanitarian interest". The major reasons for not donating blood in both groups were "fear of the needle" and around to visit to mobile car or center."