• 대한산업공학회지
• /
• 제25권1호
• /
• pp.130-140
• /
• 1999

This paper deals with a priority queueing model in an ATM system. Two types of customers are considered. Type-1 customers have push-put priority over type-2 customers. Type-1 customers can enter the service only when the number of type-2 customers is less than a threshold T. We derive the joint probability of the number of customers in the buffer, the mean waiting time, and the loss probabilities of each type. We also propose an optimal control policy that satisfies a given quality of service.

• 한국경영과학회지
• /
• 제18권3호
• /
• pp.51-63
• /
• 1993

We consider a cyclid server system under N-policy. This system consists of multiple queues served in a cyclic order by a single server. In this paper, we consider the following control policy. Every time server polls one queue, the server inspects the state of the queue. If the total number of units is found to have reached or exceeded a pre-specified value, the server begins to serve the queue until it is empty. As soon as the queue becomes empty, the server polls next queue. An approximate analysis of this system is presented. Sever vacation model is used as an analytical tool. However, server vacation periods are considered to be dependent on the service times of respective queues. The results obtained from the approximate analysis are ompared with simulation results.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
• /
• pp.55-60
• /
• 1992

The IEEE 802.4 priority mechanism can be used to handle multiple data access classes of traffic. Several timers are used to realize the priority mechanism. The performance and stability of a token bus network depend on the assignment of such timers. In this peper, we present a dynamic timer assignment algorithm for the token passing bus network. The presented algorithm has simple structure for real-time applications and adaptively controls the set of initial timer values according to the offered traffic load. The assignment of the set of timers becomes easy due to the presented algorithm. Based on the iterative algorithm, some solutions such as mean waiting time are derived.

• 한국시뮬레이션학회논문지
• /
• 제8권4호
• /
• pp.73-87
• /
• 1999

Order Review/Release (ORR) System is the linkage between planning system and actual production. Reduction of the waiting time on the machines, work in process and lead time variation may be achieved by adopting ORR strategies. But researchers on the ORR do not agree on the effectiveness of ORR. Some say that the overall system flow time may be increased if ORR is adopted, but others say that ORR can reduce work in process, flow time and variation of flow time. The objective of this research is to clarify under what environments order release strategy is effective. Simulation study was conducted in a hypothetical job shop. The experimental results show that dispatching rule is much more important than ORR is in controlling the shop floor. But the results indicate that ORR can reduce mean shop flow time, average work in process and variation of shop flow time under such environments where utilization level is high and planned order is weekly released to the order pool. And the results also show that the effect of plan smoothing on the ORR is insignificant, which is inconsistent with the results of the previous researches.

• 대한산업공학회지
• /
• 제19권2호
• /
• pp.23-34
• /
• 1993

Although there are numerous studies that address the problem of optimal machine grouping and part family classification for cellular manufacturing, little research has been reported that studies the conditions where cellular manufacturing is appropriate. This paper, in order to evaluate and compare the job shop with the GT cellular shop, the performance of those shops were simulated by using SIMAN. We tested the effect of independent variables including changes of product demands, intercell flow level, group setup time, processing time variability, variety of material handling systems, and job properties (ratio of processing time and material handling time). And also performance measures (dependent variables), such as machine utilization, mean flow time, average waiting time, and throughput rate, are discussed. Job shop model and GT cellular shop written in SIMAN simulation language were used in this study. These systems have sixteen machines which are aggregated as five machine stations using the macro feature of SIMAN. The results of this research help to better understand the effect of production factors on the performance of cellular manufacturing systems and to identify some of the necessary conditions required to make these systems perform better than traditional job shops. Therefore, this research represents one more step towards the characterization of shops which may benefit from cellular manufacturing.

• 핵의학기술
• /
• 제17권1호
• /
• pp.30-35
• /
• 2013

의료서비스의 만족도를 향상시키기 위한 방안으로 체감 대기시간 단축과 정확한 의료정보 제공, 검사의 정확도 등이 긍정적인 반응을 보여주고 있다. 이와 같은 방안에 동영상 홍보물이 유용성이 있는지 평가하였으며, 휴대용 DVD플레이어를 구입하여 검사 전 개인적으로 동영상을 시청하도록 한 방법이 서비스 만족도 향상에 도움이 되는 것으로 조사되었다. 체감대기시간 단축에 의한 만족도 향상은 예약시간보다 지연 되는 경우 보다 효과적이며, 현재 제공되고 있는 동영상의 활용도 향상을 위한 홍보를 적극적으로 시행한다면 정확한 의료정보 제공에 의한 만족도 역시 향상될 것이다. 방사성의약품 투여 후 표준섭취시간을 초과하는 시간대 중 가장 많은 부분을 차지하는 1~~3분대를 최소화하기 위해 약 7분 정도의 홍보 동영상을 제공한 결과 미준수 건수가 2.3% 감소하였으며, 이는 정확한 검사를 제공하여 고객의 만족도를 높일 수 있다. 향후 동영상 제공에 대한 홍보를 적극적으로 시행하고 검사 전 개별적으로 동영상을 시청할 수 있도록 휴대용 DVD 플레이어를 제공할 수 있는 구조적인 시스템이 갖춰진다면 의료서비스에 의한 고객 만족도 향상에 기여하리라 생각된다.

• 보건교육건강증진학회지
• /
• 제1권1호
• /
• pp.72-82
• /
• 1983

The purpose of this study is to provide the basic data necessary for the effective performance of administrative readjustment and demend and suppley medical care service by of analysing the extent of satisfaction of outpatient toward hospital. The subjects of this study are the 832 outpatients (398 male and 434 female) visit to 2 different university hospital in Seoul. The data were collected through self-administered techniques with a structured questionnaire from Oct.21 to Nov. 9, 1982. All the collected data were analyzed by means of percentage, mean and standard deviation. The results were as follows: 1. Those who are between :30 and 39 of age constitute the largest part of them as being 31.7 percent of the whole body. 40.0 percent of them graduated from the college and they take the lergest part of those who answered the questionnaire. 43.3 percent of the patients visit to the hospital by the reason for the reputation of a doctor and they take the largest part of the subjects. 2. The extent of satisfaction for hospital system. The mean extent of satisfaction for hospital system was revealed 2.50 scores, which is evaluated to neutral. The mean extent of satisfaction for waiting time of prescribed medicine presented 1.51 scores, the lowest among the component of hospital system, which is evaluated to high dissatisfaction. 3. The extent of satisfaction for the environment and facilities of hospital. The mean extent of satisfaction for the environment and facilities of hospital was revealed 3.08 scores, which is evaluated to moderate satisfaction. 4. The extent of satisfaction for doctor and other hospital employees. The mean extent of satisfaction for doctor and other hospital employees was revealed 3.05 scores which is evaluated to moderate satisfaction. The mean extent of satisfaction for doctor presented 3.39 scores, the highest among the components of doctor and other hospital employees. 5. The extent of satisfaction for charge of hospital. The mean extent of satisfaction for charge of hospital was revealed 2.74 scores, which is evaluated to neutral. 6. The extent of whole satisfaction for hospital. The mean extent of whole satisfaction for hospital was revealed 2.84 scores which is evaluated to neutral.

• 한국치위생학회지
• /
• 제13권6호
• /
• pp.977-985
• /
• 2013

Objectives : The purpose of the study is to investigate Korean scaling fear (KSF)-1.1 and related factors in scaling patients. Methods : The subjects were 314 scaling patients in 7 dental clinics in Daegu from April to June, 2013. Data were analyzed for simple frequency rate, t-test and ANOVA(Sheffes's post hoc) for the identification of the differences between KSF-1.1 and variables. Multiple regression was analyzed for the impact of independent variable on the score of KSF-1.1. Results : Mean score of KSF-1.1 in 314 scaling patients was 2.60. Female patients (2.71) had a higher score than male (2.47) (p<0.01). Those who didn't get a regular dental check up(2.87) tended to have higher fear level than those who had regular checkup (2.46) (p<0.001). Those who experienced dental pain (2.90) had significantly higher score than those who had not (2.46) (p<0.001). There was a significant difference between three groups (yes 3.03, ordinary 2.79, and no 2.42) in scaling (p<0.001) and financial burden (p<0.001). Variables associated with score of KSF-1.1 were gender(${\beta}$=0.21, p<0.05), waiting time for scaling(${\beta}$=0.24, p<0.01) and financial burden (${\beta}$=0.22, p<0.02) by multiple regression analysis. Conclusions : The influencing factors of scaling were gender, financial burden, waiting time for scaling that may effect on a score of KSF-1.1.

• 한국식생활문화학회지
• /
• 제13권5호
• /
• pp.423-430
• /
• 1998

The purposes of this study were to (a) measuring attitude and satisfaction of Yonsei university students towards contracted vs. rented university foodservices, (b) determine university students' overall satisfaction & perception regarding the factors improved towards university foodservice and (c) provide recommendation on marketing strategies for university foodservices. Questionnaires were hand delivered to 600 Yonsei University students by designated coordinators. A total of 549 questionnaires were usable; resulting in an 93% response rate. The survey was conducted between October 12 to October 18, 1995. Statistical data analysis was completed using the SAS Programs for descriptive analysis, T-test, ${\chi}^2-test$, ANOVA, Factor Analysis and Stepwise Multiple Regression. The results of this study can be summarized as follows: 1. Performance mean score for contracted foodservice management in terms of food, menu, price, hygiene, facilities was higher than for rented foodservice management. 2. The average satisfaction score for contracted foodservice management in terms of price was lower than for rented foodservice management. There was no gap between contracted foodservice management and rented foodservice management in overall satisfaction score and price satisfaction score. 3. Perception regarding the factors improved of thirteen factors to be improved except operating hours, waiting time, price, food quantity were perceived as better by students. 4. Perception regarding the factors improved have correlation with foodservice qualify attribute's performance. 5. According to multiple regression analysis, 92.05% of the variance in respondents' satisfaction score could be explained by procedure after meal, purchasing procedure, operating hours, availability of breakfast, waiting time, atmosphere, price, facilities, service endeavor to survey satisfaction in foodservice, availability of kitchen and wall space, portion size, taste of food, change of cafeteria name, the number of seats, and variety of menu.

• Journal of Trauma and Injury
• /
• 제32권2호
• /
• pp.80-85
• /
• 2019

Purpose: To compare the time intervals to magnetic resonance imaging (MRI) and surgical treatment in patients having traumatic cervical spinal cord injury (SCI) with and without bony lesions. Methods: Retrospectively analyzed adult patients visited Kyungpook National University Hospital and underwent surgical treatment for cervical SCI within 24 hours. The patients who were suspected of having cervical SCI underwent plain radiography and computed tomography (CT) upon arrival. After the initial evaluation, we evaluated the MRI findings to determine surgical treatment. Waiting times for MRI and surgery were evaluated. Results: Thirty-four patients were included. Patients' mean age was 57 (range, 23-80) years. Patients with definite bony lesions were classified into group A, and 10 cases were identified (fracture-dislocation, seven; fracture alone, three). Patients without bony lesions were classified into group B, and 24 cases were identified (ossification of the posterior longitudinal ligament, 16; cervical spondylotic myelopathy, eight). Mean intervals between emergency room arrival and start of MRI were 93.60 (${\pm}60.08$) minutes in group A and 313.75 (${\pm}264.89$) minutes in group B, and the interval was significantly shorter in group A than in group B (p=0.01). The mean times to surgery were 248.4 (${\pm}76.03$) minutes in group A and 560.5 (${\pm}372.56$) minutes in group B, and the difference was statistically significant (p=0.001). The American Spinal Injury Association scale at the time of arrival showed that group A had a relatively severe neurologic deficit compared with group B (p=0.046). There was no statistical significance, but it seems to be good neurological recovery, if we start treatment sooner among patients treated within 24 hours (p=0.198). Conclusions: If fracture or dislocation is detected by CT, cervical SCI can be easily predicted resulting in MRI and surgical treatment being performed more rapidly. Additionally, fracture or dislocation tends to cause more severe neurological damage, so it is assumed that rapid diagnosis and treatment are possible.