• Journal of the Korea Society for Simulation
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• v.25 no.2
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• pp.75-81
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• 2016

By using simulation, fixed location production method and flow production method have been compared to improve the productivity of deckhouse preceding outfitting process. In this paper, we analyze that the suggested flow production system instead of fixed location production can improve productivity. In current preceding outfit production system which adopts fixed location production, where a block occupies an area and does not move until the work finishes. On the other hand, in improved flow production system, the block moves instead of workers and equipment. Though the output of two systems are almost the same when we did not consider the moving time and waiting time of blocks, the flow production will be better when the variability of task time will be reduced.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.187-194
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• 2011

Optimizing truck dispatching-intervals is imperative in ready mixed concrete (RMC) delivery process. Intervals shorter than optimal may induce queuing of idle trucks at a construction site, resulting in a long delivery cycle time. On the other hand, intervals longer than optimal can trigger work discontinuity due to a lack of available trucks where required. Therefore, the RMC delivery process should be systematically scheduled in order to minimize the occurrence of waiting trucks as well as guarantee work continuity. However, it is challenging to find optimal intervals, particularly in urban areas, due to variations in both traffic conditions and concrete placement rates at the site. Truck dispatching intervals are usually determined based on the concrete plant managers' intuitive judgments, without sufficient and reliable information regarding traffic and site conditions. Accordingly, the RMC delivery process often experiences inefficiency and/or work discontinuity. Automatic data collection (ADC) techniques (e.g., RFID or GPS) can be effective tools to assist plant managers in finding optimal dispatching intervals, thereby enhancing delivery performance. However, quantitative evidence of the extent of performance improvement has rarely been reported to data, and this is a central reason for a general reluctance within the industry to embrace these techniques, despite their potential benefits. To address this issue, this research reports on the development of a discrete event simulation model and its application to a large-scale building project in Abu Dhabi. The simulation results indicate that ADC techniques can reduce the truck idle time at site by 57% and also enhance the pouring continuity in the RMC delivery process.

• Korean Journal of Community Nutrition
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• v.2 no.2
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• pp.206-217
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• 1997

This study was designed to analyze and compare production management practices and labor productivity between conventional and commissary school foodservices and 46 dietitians of commissary school foodservices in Kyunggi-do. The response rates were 89.7% and 91.3$\%$, respectively. The number of meals served was ranged from less than 100 to over 1, 900 in conventional school foodservices and from 200 to 1, 600 in commissary foodservices. Thirty three conventional foodservices(42.3%) produced less than 300 meals per day. Numbers of satellite school per central kitchen were ranged from 1 to 5 schools ; fifty percent of commissary foodservices have contained 3 satellite schools. Meals for satellite schools were transported between 11:00 a.m.and 12:00 a.m ; transportation time was from 10 to 90 minutes. Waiting time before service in satellite schools was between 10 minutes and 80 minutes. Part time employees supported by parents were hired in 37.3$\%$ of conventional and 50$\%$ of commissary school foodservices. Voluntary workers were supplied for 64.9$\%$ of conventional and 52.4$\%$ of commissary school foodservices. Labor productivity was calculated from work schedule. Labor productivity(labor minutes per meal)was lowest in foodservices with 101-4-- meals(8.48 min)was lower than that of foodservices with above 401 meals ; no significant differences were found among 401-700(6.02 min), 701-1, 100(4.01 min), 1, 101-1, 500(3.41 min), and 1, 501-1, 900(3.15 min)meals in conventional foodservices. Labor minutes per meal of foodservices which served less than 400 meals(6.90 min) per day was significantly lower than those of foodservices which served 401-1, 900 meal(3.41-4.92 min) in commissary foodservices(p<0.05)

• Journal of radiological science and technology
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• v.35 no.1
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• pp.45-50
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• 2012

Nowadays, most of the hospital serves "one stop service" for CT scan. The patients could be taken the CT scan in the day they register for scan. On the contrary to the time convenience, patients are not satisfied with long waiting time and unkindness of staff. The objective of this study is to improve the patient's satisfaction for the CT scan, by analyzing inconvenience factors and improving the service qualities. From April 1 to August 30 in 2011, we investigated the satisfaction of patients who did examined abdomen CT scan with contrast media. We analyzed the 89 questionnaires before and after the service improvements from them. The worker's kindness, the environment of CT room and understanding about CT scan were answered by questionnaire and the waiting time of a day CT scan was drawn by medical information statistics. Also, the period before improvement was from April to June and the period after improvement was from July to September. And these questionnaire was analyzed through SPSS V. 15.0. In this study, kindness of staff, environment of CT room, intelligibility for CT scan and waiting time was explored and analyzed by SPSS V.15.0. The score of kindness was improved by 32%, satisfaction level of the environment was improved by 52.54%. The understanding level about CT scan was improved by 52.36% and the wating time of a day CT was shortened by 21% through our service enhancement programs. Consequentially, it is considered that these efforts would contribute to increase the revenue of hospital.

• The Journal of Korea Robotics Society
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• v.15 no.2
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• pp.100-106
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• 2020

In the agricultural field, interests in research using robots for fruit harvesting are continuously increasing. Dual arm manipulators are promising because of its abilities like task-distribution and role-sharing. To operate it efficiently, the task sequence must be planned adequately. In our previous study, a collision-free path planning method based on a genetic algorithm is proposed for dual arm manipulators doing tasks cooperatively. However, in order to simplify the complicated collision-check problem, the movement between tasks of two robots should be synchronized, and thus there is a problem that the robots must wait and resume their movement. In this paper, we propose a heuristic algorithm that can reduce the total time of the optimal solution obtained by using the previously proposed genetic algorithm. It iteratively desynchronizes the task sequence of two robots and reduces the waiting time. For evaluation, the proposed algorithm is applied to the same work as the previous study. As a result, we can obtain a faster solution having 22.57 s than that of the previous study having 24.081 s. It will be further studied to apply the proposed algorithm to the fruit harvesting.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.3
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• pp.151-157
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• 1993

In this paper, we investigate the effects of yield randomness for lot-sizing in a multi-stage production system. The practical importance of incorporating yield randomness into production models has been emphasized by many researchers. Yield randomness, especially in semiconductor manufacturing, poses a mojor challenge for production planning and control. The task becomes even more difficult if the demand for final product is uncertain. An attempt to meet the demand with a higher level of confidence forces one to release more input in the fabrication line. This leads to excessive work-in-process (WIP) inventories which cause jobs to spend unpredictably longer time waiting for the machines. The result is that it is more difficult to meet demand with exceptionally long cycle time and puts further pressure to increase the safety stocks. Due to this spiral effect, it is common to find that the capital tied in inventory is the msot significant factor undermining profitability. We propose a policy to determine the quantity to be processed at each stage of a multi-stage production system in which the yield at each stage may be random and may need rework.

• Journal of the Korean Home Economics Association
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• v.38 no.8
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• pp.99-110
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• 2000

The purpose of this study was to investigate the differences in traditional baby-delivery practices between young mother and grandmother generations. The subjects were 118 young mothers and 118 their own mothers or mothers-in-law in Tae Gu district. Young mothers had the first baby aged from 2-to 2.5-year-old. The subjects answered the questionnaires on Korean traditional baby-delivery practices developed by the researchers based on literature reviews. The data were analyzed using Frequencies, Percentages, Crosstabs, and t-test. The results of this study were as follows: 1. More grandmothers believed in supernatural being who influenced pregnancy and used to be called as 'grandma Sam Shin', expected to have son, and had charms then young mothers. But less grandmothers had sexual intercourse at the time of ovulation, took physical care, and practiced fetal education than young mothers 2. On the other hand, no generation differences were found in dreaming of foretelling conception(Te Mong), eating a restroative and food to get pregnancy, and washing own's hair or body and avoiding attending a funeral near the time of baby-delivery. 3. Most of young mothers gave birth in hospital with the doctor's heap, whereas most of grandmothers did at their home with the help of the experienced old women. Most of young mothers'husbands were at the waiting room in the hospital, but about half of grandmothers'husbands were at work when their wives grove birth.

• Korea Journal of Hospital Management
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• v.25 no.1
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• pp.1-12
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• 2020

Purposes: The aim of this study is to evaluate whether the contents of hospital reservation and reception applications(apps) are qualitatively useful in meeting the needs of medical consumers and improving hospital accessibility and convenience. Methodology: (1) identify consumer needs through social data web mining, (2) describe the status of key contents of mobile apps to improve accessibility and convenience of care, and (3) verify the quality of apps through validated tools Finding: The contents of 'mobile reservation function' and 'waiting time information provision' that can contribute to reduction of delay time of care and efficiency of desk work were supported, but the level of utilization was insufficient. The quality level of the app, including the level of consumers' needs, has shown a wide gap between the apps. Implications: The recent development of mobile apps for hospital accessibility and consumer needs has shown a wide gap in the quality of apps, including information and aesthetic. Therefore, it is necessary to develop apps based on user interface(UI), user experience(UX) based designs that can promote the usefulness and convenience of apps while monitoring needs of consumers continuously.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.29-39
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• 2011

The appointment system is widely used to facilitate customer access to service in many industries including healthcare and others. Because of its importance, much research has investigated how to build an effective appointment policy under various environments. However, most research has considered a single-server service system. The objective of this work is to evaluate several appointment policies in a two-stage service system in which multiple servers are available and build separate appointments at the second-stage. In such a system, we propose and evaluate the staggering appointment policy. Simulation experiments indicate that the proposed staggering appointment policy outperforms other traditional appointment policies in terms of customer waiting time, server idle time, and the number of customers who are later to scheduled appointments.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.151-158
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• 2005

In order to use the existing map data base in the mobile phone, the dynamic creation technique of the radio map which will be able to be converted into the raster image and transmitted was proposed. We transferred the client module functions such as the coordinate conversion, data compression and decoding to server, and made driving of JAVA browser in the mobile phone which has the restricted resources possible for the dynamic creation of the radio map. We made the radio electronic map service possible without map data base for the mobile phone use only by performing the general work of the map at the sever. And we guaranteed the client waiting time less then the limit time by performing the filtering work of the map at the server also. After we input the keyword at the user interface for searching the region or facility, and verified the performance of the proposed technique by confirming that the raster electronic map usable at the mobile phone was created dynamically.