• Journal of Korea Society of Industrial Information Systems
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• v.29 no.1
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• pp.63-76
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• 2024

In this study, we analyzed queue length and sojourn time of discrete-time BMAP/G/1 queues under the workload control. Group customers (packets) with correlations arrive at the system following a discrete-time Markovian arrival process. The server starts busy period when the total service time of the arrived customers exceeds a predetermined workload threshold D and serves customers until the system is empty. From the analysis of workload and waiting time, distributions of queue length at the departure epoch and arbitrary time epoch and system sojourn time are derived. We also derived the mean value as a performance measure. Through numerical examples, we confirmed that we can obtain results represented by complex forms of equations, and we verified the validity of the theoretical values by comparing them with simulation results. From the results, we can obtain key performance measures of complex systems that operate similarly in various industrial fields and to analyze various optimization problems.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.27-35
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• 2015

We analyze an M/G/1/K queueing system with queue-length dependent service and arrival rates. There are a single server and a buffer with finite capacity K including a customer in service. The customers are served by a first-come-first-service basis. We put two thresholds $L_1$ and $L_2$($${\geq_-}L_1$$ ) on the buffer. If the queue length at the service initiation epoch is less than the threshold $L_1$, the service time of customers follows $S_1$ with a mean of ${\mu}_1$ and the arrival of customers follows a Poisson process with a rate of ${\lambda}_1$. When the queue length at the service initiation epoch is equal to or greater than $L_1$ and less than $L_2$, the service time is changed to $S_2$ with a mean of $${\mu}_2{\geq_-}{\mu}_1$$. The arrival rate is still ${\lambda}_1$. Finally, if the queue length at the service initiation epoch is greater than $L_2$, the arrival rate of customers are also changed to a value of $${\lambda}_2({\leq_-}{\lambda}_1)$$ and the mean of the service times is ${\mu}_2$. By using the embedded Markov chain method, we derive queue length distribution at departure epochs. We also obtain the queue length distribution at an arbitrary time by the supplementary variable method. Finally, performance measures such as loss probability and mean waiting time are presented.

• Progress in Medical Physics
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• v.24 no.2
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• pp.92-98
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• 2013

The experimental verification of treatment planning on the treatment spot is the ultimate method to assure quality of radiotherapy, so in-vivo skin dose measurement is the essential procedure to confirm treatment dose. In this study, glass rod dosimeter (GRD), which is a kind of photo-luminescent based dosimeters, was studied to produce a guideline to use GRDs in vivo dosimetry for quality assurance of radiotherapy. The pre-processing procedure is essential to use GRDs. This is a heating operation for stabilization. Two kinds of pre-processing methods are recommended by manufacturer: a heating method (70 degree, 30 minutes) and a waiting method (room temperature, 24 hours). We equally irradiated 1.0 Gy to 20 GRD elements, and then different preprocessing were performed to 10 GRDs each. In heating method, reading deviation of GRDs at same time were relatively high, but the deviation was very low as time went on. In waiting method, the deviation among GRDs was low, but the deviation was relatively high as time went on. The meaningful difference was found between mean reading values of two pre-processing methods. Both methods present mean dose deviation under 5%, but the relatively high effect by reading time was observed in waiting method. Finally, GRD is best to perform in-vivo dosimetry in the viewpoint of accuracy and efficiency, and the understanding of how pre-processing affect the accuracy is asked to perform most accurate in-vivo dosimetry. The further study is asked to acquire more stable accuracy in spite of different irradiation conditions for GRD usage.

• Journal of Korean Academy of Nursing Administration
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• v.4 no.2
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• pp.405-418
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• 1998

The purpose of this study was to describe patients satisfaction with nursing care in the emergency department and factors influencing satisfaction rates. 1. The mean score of patient satisfaction with nursing care in the emergency departments was 2.70. The mean scores of patient satisfaction with different aspects of nursing care services were 3.05 for nursing services for psychological safety: 2.67 for technical competence: 2.49 for information giving: and 1.35 for discharge teaching. 2. Patient satisfaction with nursing care services provided. according to the general characteristics of the patients. was revealed as being significantly high for the groups of patients made up of those who were male. those over 51years of age. married subjects. those with an education level of high school or below level. housewives. Buddhists. and those in the middle economic level. Patient satisfaction with nursing care according to their service utilization in the emergency departments revealed that satisfaction was significantly high for patients who were in internal medicine. neurology or psychiatry. those admitted for the first time. those for whom the distance from the department to home was less than 30 minutes. patients who visited between monday and Friday and between 8AM and 4PM. patients who did not have to wait to be seen and those who stayed in the department less than 24 hours. 3. The correlation between the patients' general characteristics. nursing service utilization of the patients in the department and their satisfaction with nursing care showed that patients with longer waiting time had lower satisfactory scores for nursing service. 4. The registered nurses working in the emergency department reported that the main reasons for low satisfaction rates included 'over worked nurses' and 'too many patients' in the emergency department. In conclusion. the results of this study suggest the necessity of developing relevant nursing interventions for discharge teaching to increase patient satisfaction with nursing care services in emergency departments: and the need for adequate support from hospital administrators to improve patients' service utilization.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.289-295
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• 2004

The objective of this paper is to analyze the equipment combination of stevedoring system at port container terminal. In general, the productivity of container terminal is evaluated by productivity of container cranes at apron, but there are other equipment such as transport vehicles and yard cranes. Therefore, a method that can estimate the optimal equipment combination of stevedoring system in container terminal is required. We perform various simulation experiment and analyze equipment combination to improve the productivity. From the application of the case study, we demonstrated the savings effect using mean waiting time rates by the equipment combination.

• The Journal of Korean Physical Therapy
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• v.1 no.1
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• pp.73-82
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• 1989

The purpose of this study was to contribute to the relatively neglected area of out -patient satisfaction with physical therapy service by measuring and determining the factors affecting patient satisfaction in the Andong region. One hundred and forty-five subjects (81 males and 64 females) at 11 facilities with a mean age of 39.2 years (SD=16.2) responded to the satisfaction questionnaire. Each questionnaire contained a set of demographic questions and 19 patient satisfaction items. Cronbach's alpha test of reliability was used as the measure of internal consistency . The satisfaction scale had a good reliability coefficient : Cronbach's alpha=.8688. The average satisfaction score (minimum score=19, maximum score=95) was 75.4 ranging from 38 to 90. Respondent variables including sex, education, marital status, religion, medical security, average monthly income, and number of physical therapy out-patient department treatment visits were analyzed by t-test, ANOVA, and ANCOVA. Satisfaction with the service was largely unrelated to mallets of sex, education, occupation, or other demographic variables. However, marital status, age, average monthly income, and number of treatment visits in the out-patient department were significantly related to patient satisfaction. The analysis presented here could be replicatied with a larger sample in other areas. Other factors such as physical therapist availability, physical therapist competence, accessibility, waiting time, and atmosphere of the treatment area should be considered in further studies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6B
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• pp.895-900
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• 2010

As the diverse telecommunication services have been developed, network designers need to prevent congestion which may be caused by properties of timecorrelation and burstiness, and unpredictable statistical fluctuation of traffic streams. This paper considers the leaky bucket scheme with combined control of arrival and token rates, in which the arrival rate and the token generation interval are controlled according to the queue length. By using the embedded Markov chain and the supplementary variable methods, we obtain the queue length distribution as well as the loss probability and the mean waiting time.

• Journal of the Korean Institute of Navigation
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• v.15 no.3
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• pp.1-11
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• 1991

As increasing needs of marine transportation , world merchant fleet and ship's size were enlarged and it caused frequent disasters in human lives and natural environment. By the reason of the above, they started to establish the Vessel Traffic System (VTS) at the European coast in 1960' and most of advanced contries established and managed it to prevent the sea traffic accidents in these days. The concept of traffic control at sea can be divided into three types. First, the initial gathering of informations about ship's identity and movement etc.. Second, monitoring of the traffic flow and amendment of instructions. Third , organization and direction of ships by allocating routes and speeds. Where the goal of traffic control is safety of traffics and developing effectiveness of navigation channel, if traffic volume is less tan channel capacity then the above first or second level of control would be sufficient but if it is bigger than that , more positive policy of control should be adopted as same as third type of the above. In this paper where the strategy of VTS is focused on the control of traffic density to be spread equality, as possible , all over the navigation channels and also improvement of effectiveness , it suggests algorithm to assign the vessels to the channels with balanced traffic density , and other algorithms using D.P. to sequence the vessels assigned to one channel in optimum order which decreases the mean waiting time in sense of channel effectiveness with numerical examples.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.26 no.4
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• pp.325-332
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• 2022

Backgrounds/Aims: To analyze relationships of hepatic histopathological findings and bile microbiological profiles with perioperative outcomes and risk of late biliary stricture in individuals undergoing surgical bile duct injury (BDI) repair. Methods: A historical cohort study was carried out at a tertiary university hospital. Fifty-six individuals who underwent surgical BDI repair from 2014-2018 with a minimal follow-up of 24 months were enrolled. Liver biopsies were performed to analyze histopathology. Bile samples were collected during repair procedures. Hepatic histopathological findings and bile microbiological profiles were then correlated with perioperative and late outcomes through uni- and multi-variate analyses. Results: Forty-three individuals (76.8%) were females and average age was 47.2 ± 13.2 years; mean follow-up was 38.1 ± 18.6 months. The commonest histopathological finding was hepatic fibrosis (87.5%). Bile cultures were positive in 53.5%. The main surgical technique was Roux-en-Y hepaticojejunostomy (96.4%). Overall morbidity was 35.7%. In univariate analysis, liver fibrosis correlated with the duration of the operation (R = 0.3; p = 0.02). In multivariate analysis, fibrosis (R = 0.36; p = 0.02) and cholestasis (R = 0.34; p = 0.02) independently correlated with operative time. Strasberg classification independently correlated with estimated bleeding (R = 0.31; p = 0.049). The time elapsed between primary cholecystectomy and BDI repair correlated with hepatic fibrosis (R = 0.4; p = 0.01). Conclusions: Bacterial contamination of bile was observed in most cases. The degree of fibrosis and cholestasis correlated with operative time. The waiting time for definitive repair correlated with the severity of liver fibrosis.

• Journal of muscle and joint health
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• v.3 no.2
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• pp.166-176
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• 1996

This is a study through survey with the purpose of analysing of treatment cost for arthritis. Treatment cost can be devided Into two characteristics, one is the direct cost and the other is the indirect cost. Direct cost contains fees of medical treatment Including cost of self treatment & purchsing price of herb durg. On the other hand indirect cost means the using money of tansportation, lodging charge & labor-losing-time cost. For the succession of medical treatment of chronic diseases patients have to control themselves to go shopping around for the cure remeadies. And also it is important that the cost for unefficient or probably hamful folk remeadies should be reduced in order to distribute appropriatively the limited financial resources. As the result of this study, the fees for self treatment & herb drug are two times as much as those of regural medical treatment. Within the direct cost, there are the mean cost of regural medical treatment 59,630 won/mon., self-treatment 42,790 won/mon., and herb drug 78,380won/mon. therefore total mean direct cost is 180,800won per month. Moreover patients intermittently pay the cost of prostheses If folk remedies, these are added to the direct cost as above mentioned. Attributes of folk remedies are various from cure & analgesics to nutrients and their virtues as medicine are not clear in view of scientific knowledge. But 56% of arthritis patients have ever been experienced folk remedies. the cost for these remedies has wide ranges from 40,000 won to 1,000,000won. Total mean indirect cost including the transfortation fee, lodging charge & labor-losing-time cost has the range from 82,825won/month to 106,150won/month. Among these cost, labor-losing-time cost has a mojority because the waiting times are too long for seeing a doctor. In conclusion those patients having arthritis have a large burden against the treatment cost for continuous care. Therefore health professional should make effort to guide the patient to determine themselves informed choice about the treatment process.