• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.153-162
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• 1997

M/G/1 queueing system is one of the most widely used one to model the real system. When operating a real systems, since it often takes cost, some control policies that change the operation scheme are adopted. In particular, the N-policy is the most popular among many control policies. Almost all researches on queueing system are based on the assumption that the arrival rates of customers into the queueing system is constant, In this paper, we consider the M/G/1 queueing system whose arrival rate varies according to the servers status : idle, set-up and busy states. For this study, we construct the steady state equations of queue lengths by means of the supplementary variable method, and derive the PGF(probability generating function) of them. The L-S-T(Laplace Stieltjes transform) of waiting time and average waiting time are also presented. We also develop an algorithm to find the optimal N-value from which the server starts his set-up. An analysis on the performance measures to minimize total operation cost of queueing system is included. We finally investigate the behavior of system operation cost as the optimal N and arrival rate change by a numerical study.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.111-116
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• 1999

The daily irrigation water intakes from five reservoirs were measured and the water management characteristics analyzed . During the irrigation seasons in 1998 , the total water supply rates ranged from 534 to 864 mm, and thedelivery losses varied from5 to 17 pervent. Major factors affecting the water supply rates were rice transplanting and water management , and rainfall distributions during the growing seasons. The consumptive uses and effective rainfall from each researvoir were compared satisfactorily with the simulated results from the Daily Irrigation Reservoir Operation Model , DIROM.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.3
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• pp.251-258
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• 2019

This study was conducted to propose an effective port operation method in terms of the design capacity of waiting anchorage by comparing the ratio and the number of waiting anchorage according to the port operation method of Busan New Port. For this, the Arena simulation program compared the rates of waiting vessels according to the application of the multi-user terminal, liner terminal and hybrid liner terminal operation methods. As a result, analysis suggested the necessary anchorage space can be reduced to about 18 % when using the multi-user terminal operation method and about 15.6 % when using the hybrid liner terminal operation method, as compared with the liner terminal operation method. Specifically, it was effective to apply the multi-user terminal operation method in terms of the anchorage capacity to be designated to Busan New Port. This study can apply to the designation of the new anchorage in the Busan New Port by reflecting the contents of the design of the anchorage in accordance with the port operation method.

• Journal of the Korean School Mathematics Society
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• v.20 no.2
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• pp.141-161
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• 2017

As it's important to understand the order of operation in the mixed calculation of natural number and perform it, mathematics curriculums and textbooks focused that students can calculate with understanding the order of operation and its principles. For attaining the implications of teaching about the mixed calculations, this study analyzed the problem solving abilities and error types of 67 elementary students and 57 pre-service teachers using questionnaire which was developed in this study and composed of numeric expressions and word problems. The conclusions drawn from this study were as follows: Students were revealed the correct rates(86.2% and 73.5%) in numeric expressions and word problems, but they were showed the paradigmatic error types-the errors of the order of operation and the composition of numeric expression from word problems. Even though the correct rates of the preservice teachers were extremely high, the result of problem solving processes required that it's needed to be interested in teaching the principles of the order of operation in the mixed calculations. In addition, subjects were revealed the problems about using parentheses and equal sign.

• KCID journal
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• v.17 no.2
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• pp.57-70
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• 2010

This study was performed to analyze the affect of water supply capacity followed by allocating flood control volume in heightening reservoir, of which Baekgog reservoir was selected as a case study in here. Baekgog reservoir is located in Jincheon county, Chungbuk province, of which full water level will be heightened from EL. 100. 1m to EL. 102.1m, and total storage from 21.75M $m^3$ to 26.67M $m^3$. Flood inflow with 200year frequency was estimated to 997 $m^3$/s in peak flow and 22.54M $m^3$ in total volume. Reservoir flood routing was conducted to determine flood limited water levels, which was determined to have scenarios such as EL 97-98-99m in periods of 6.21.-7.20., 7.21.-8.20., and 8.21.-9.20., respectively, EL 97-97-97m, EL 98-98-98m in present reservoir, and EL 99-100-101m, EL 99-99-99m, and EL 100-100-100m in heightened reservoir. Reservoir inflow was simulated by DAWAST model. Annual paddy irrigation requirement was estimated to 33.19M $m^3$ to 2,975ha. Instream flow was allocated to 0.14mm/d from October to April. Operation rule curve was drawn using inflow, irrigation and instream flow requirements data. In case of withdrawal limit reservoir operation using operation rule curve, reduction rates of annual irrigation supply before and after flood control by reservoir were 2.0~4.3% in present size and 1.5~3.6% in heightened size. Reliability on water supply was decreased from 77.3% to 63.6~68.2% in present size and from 81.6% to 72.7~79.5% in heightened size. And reduction rates of water storage at the end of year before and after flood control by reservoir were 7.3~16.5% in present size and 7.7~16.9% in heightened size. But water supplies were done without any water deficiency through withdrawal limit reservoir operation in spite of low flood regulating water level.

• Archives of Craniofacial Surgery
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• v.21 no.1
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• pp.3-6
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• 2020

Nowadays, the incidence of nasal bone fracture is increasing because of social complexity with frequent social activity, and reduction of fractures is relatively simple and can be corrected in short operation time. However, the postoperative results are known to be less satisfied with higher complication rates relatively. These problems could have resulted from inaccurate recognition and interpretation of fracture aspect, inaccurate planning of operation resulting in under or overcorrection, ignoring septal management, complication related nasal packings with removal, postoperative management, and patient satisfaction with complication.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.278-283
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• 2005

Generally Jar-Test is available to determine the coagulant dosage rate. Disadventages associated with Jar-Test are that regular samples have to be taken requiring manual intervention and the limitation to feedback control. To deal with this difficulty, determined optimized dosage rates of coagulant to investigates the union operation method of the statistical equation which uses the multi-regression method and the SCD.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.275-281
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• 2004

Generally Jar-Test is available to determine the coagulant dosage rate. Disadventages associated with Jar-Test are that regular samples have to be taken requiring manual intervention and the limitation to feedback control. To deal with this difficulty, determined optimized dosage rates of coagulant to Investigates the union operation method of the statistical equation which uses the multi-regression method and the SCD.

• Journal of Korean Clinical Nursing Research
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• v.16 no.3
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• pp.63-71
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• 2010

Purpose: This study was conducted to evaluate the incidence and risk factors for surgical glove perforation during operation. Methods: During the month of december 2008, a total of 1,400 pairs of surgical gloves used in major operations was collected in a tertiary hospital. All gloves were examined immediately after operation using the standardized water-leak method to detect any perforation. Incidence of the glove perforation was counted according to the type of operation, operation time, the number of involved personnel, perforation sites, and the manufacturing companies. Results: Out of 2,800 gloves examined, 312 perforations were detected comprising 11.1% of samples. In terms of the type of operation, the perforation incidence varied from 5% to 20%, and the perforation rates in CS (20%) and NS (18%) (p<.001) were significantly higher than those in other departments. The 1st assistant or scrub nurse got glove perforation more frequently than the 2nd assistant or operator (p<.001). Longer operation time was associated with higher incidence of perforation evidently (p<.001). In terms of the sites, the thumb and index finger were more frequently perforated than other sites (4.1% and 3.4% respectively) without any differences between left and right side. Conclusion: Risk factors for glove perforation including the department of operation, operation time, participating personnel, and location of perforation should be taken into account to improve surgical safety.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.584-589
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• 2003

The hot cell facility which is designed to permit safe handling of source materials with radioactivity levels up to 1,385 TBq, is planned to be built. To meet this goal, the facility is designed to keep gamma and neutron radiation lower than the recommended dose-rate in normally occupied areas. The calculations performed with QAD-CGGP and MCNP-4C are used to evaluate the proposed engineering design concepts that would provide acceptable dose-rates during a normal operation in hot cell facility. The maximum effective gamma dose-rates on the surfaces of the facility at operation area and at service area calculated by QAD-CGGP are estimated to be $2.10{\times}10^{-3}$, $2.97{\times}10^{-2}$ and $1.01{\times}10^{-1}$ mSv/h, respectively. And those calculated by MCNP-4C are $1.60{\times}10^{-3}$, $2.99{\times}10^{-3}$ and $7.88{\times}10^{-2}$ mSv/h, respectively The dose-rates contributed by neutrons are one order of magnitude less than that of gamma sources, and penetration and toboggan will be partly reinforced by lead shield.