• Journal of Communications and Networks
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• v.7 no.4
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• pp.408-416
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• 2005

Quality of service (QoS) provision is an important and indispensable function for multi-service wireless networks. In this paper, we present a new scheduling/admission control frame­work, including an efficient rate-guaranteed opportunistic scheduling (ROS) scheme and a coordinated admission control (ROS­CAC) policy to support statistic QoS guarantee in multi-service wireless networks. Based on our proposed mathematical model, we derive the probability distribution function (PDF) of queue length under ROS and deduce the packet loss rate (PLR) for individual flows. The new admission control policy makes admission decision for a new incoming flow to ensure that the PLR requirements of all flows (including the new flow) are satisfied. The numerical results based on ns-2 simulations demonstrate the effectiveness of the new joint packet scheduling/admission control framework.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.109-112
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• 2000

The EPRCA(Enhanced Proportional Rate Control Algorithm) is one of the explicit rate control algorithm recommended by the ATM forum. EPRCA algorithm is using only two threshold to buffer change is not considered for calculating ER value. In this paper to cover the shortage, two more variables are added for considering increase of buffer quantity. So calculating proper ER would avoid before getting into the congestion situation. To analysis the affect, EPRCA and proposed algorithm are compared through simulation by analysis of change of buffer length and ACR change

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.1
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• pp.89-94
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• 2001

There are many queueing systems where customers wait for service up to a certain amount of time and leave the system if they are not served during that time. This paper considers a finite capacity multi-server queueing system with Poisson input and Erlang service time, where a customer becomes a lost customer when his service has not begun within an exponential patient time after his arrival. Performance measures such as average queue length, the average number of customers in service, and the proportion of lost customers can be obtained exactly through the proposed numerical solution procedure.

• Health Policy and Management
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• v.5 no.2
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• pp.104-126
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• 1995

This study was carried out to assess the utilization of urban health center and its related factors among the urban residents. The survey was carried out for 2,394 households in Taegu and Kyongju by the structured questionnaire from 28 March to 4 April and from 2 July to 9 July, 1994. Well trained interviewers visited 2,630 households in Taegu and Kyongju, and interviewed with housewives. Of the target households, 91.0%(2,394 households) were responded through three-time visiting. The major results were summarized as follows : The fourth and fifth decad utilized the health center more frequently than any other age groups.. The lower income group showed higher rate of health center utilization than those in higher income group in Taegu City. The mean length of residence among residents of Kyongju City is longer than those of Taegu City, and the longer length of residence, the higher rate of the health center utilization. Those who are living together with neonate and infant or elderly people showed higher rate of health center utilization than those who are living without neonate and infant or elderly people in both Taegu and Kyongju. The most common reason for visiting the health center was 'low cost'. The major reasons for not visiting the health center were 'not regular customer', 'poor health center facility', and 'low quality of care'. Vaccination, communicable disease control, outpatient care, public hygiene, maternal and child health program were well recognized as health center activities. In logistic regression for the utilization of health center, the significant independent variables were length of residence and recognize the site of health center in both Taegu and Kyongju. The improvement of quality of health service, physical environment of health center and public relations on health center's activities shoulod be considered for reactivation and reingorcement of health center functions.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.181-185
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• 2008

Recently, location based service(LBS) expended based on personal specialized service, however since commercialized GPS based emergency rescue service comes with shadow zone for GPS signal such as inside building, the accuracy and reliability are not guaranteed. Therefore to improve such problem, we propose an active location detecting algorithm using RFID-TAG and Yagiantenna. To track the location of RFID-TAG where signal is generated, location tracking device in which Yagi-Antenna is installed moves around. Since directed wave and reflected wave co-exist during signal reception, final signal generated location is searched by setting up multiple of locations where signal can be generated on the map and moving location tracking device along minimum length of path. The algorithm proposed in this paper was verified of its technical validity through simulator.

• Journal of Science Education
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• v.44 no.1
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• pp.1-14
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• 2020

In this study, we analyzed the written and drawn explanations of thirty elementary school pre-service teachers in order to examine their perception on the seasonal length of day and night. The main findings are as follows: First, pre-service teachers used the most common term in the description of the texts, such as meridian altitude, axis of rotation, and revolution, and there were more misconceptions in the drawn explanation than in the written explanation. Second, by analyzing the pre-service teachers' perceptions by combining written and drawn explanations, it is possible to detect scientific errors that the distance between the Earth and the Sun is closer when the axis of rotation is tilted in relation to the revolution and seasonal changes due to changes in the orbital radius of the Earth. In addition, there have been types of explanations such as seasonally changing meridian altitudes related to the rotation of the Earth but no change in the location of the Sun. Based on the results of the analysis, we discussed the lack of experience in constructing an explanatory system of specific phenomena using scientific knowledge, lack of observational experiences about natural phenomena, and lack of exposure to other explanatory systems that cause cognitive conflicts. We hope that it will be concrete and practical help to improve the understanding of pre-service teachers in the science domain of primary teacher training program.

• Health Policy and Management
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• v.23 no.2
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• pp.145-151
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• 2013

Background: The objective of this study was to explore patient family's evaluation of emergency department (ED) service satisfaction and to compare these with ED staff perception of patient family's evaluation. Methods: Based on two surveys of the National Emergency Medical Center: the 2008 National Survey for Recognition and Satisfaction towards Emergency Medical Services and the 2008 Opinion Survey of Emergency Medical Service Providers, satisfaction gaps among physicians, nurses, and patient family were evaluated by Kruskal-Wallis tests and Wilcoxon-Mann-Whitney tests. Furthermore, the factors associated with satisfaction of emergency medical service were identified by ordinal logistic regression models. Results: There were statistically significant gaps among physicians, nurses, and patient family in overall satisfaction with ED visit, length of stay in ED, enough explanation, physicians/nurses kindness, and ED facilities. Age and income in the patient family model, the number of beds in hospital, job satisfaction and year of service in the physicians model, and the number of beds in hospital, job satisfaction and the number of patients per duty hour in the nurses model were statistically significant factors associated with evaluation/ perception of ED service satisfaction. Conclusion: Patient satisfaction is an important indicator of the quality of care and service delivery in the ED. To improve and understand satisfaction in ED service, a dyadic view of the evaluation of service quality and satisfaction-that is, from the perspectives of both the patient and the emergency medical service providers-should be concerned.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.1
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• pp.89-99
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• 2020

In this paper, we consider a dyadic server control policy that combines workload control and single vacation. Customer arrives at the system with Bernoulli process, waits until his or her turn, and then receives service on FCFS(First come first served) discipline. If there is no customer to serve in the system, the idle single server spends a vacation of discrete random variable V. If the total service times of the waiting customers at the end of vacation exceeds predetermined workload threshold D, the server starts service immediately, and if the total workload of the system at the end of the vacation is less than or equal to D, the server stands by until the workload exceeds threshold and becomes busy. For the discrete-time Geo/G/1 queueing system operated under this dyadic server control policy, an idle period is analyzed and the steady-state queue length distribution is derived in a form of generating function.

• Women's Health Nursing
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• v.17 no.1
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• pp.21-30
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• 2011

Purpose: This study was done to investigate the types of breastfeeding visits by mothers twenty-four months after birth and to identify the factors that increased breast feeding rates. Methods: The subjects of this study totaled seven hundred and seventy-four mothers with infants aged 2 years or less who had visited national medical institutions including Sanhujori service facilities, breastfeeding care service facilities, and community health centers. Data was collected from June 22 to July 31, 2009. Data was analyzed using descriptive statistics, $x^2$ test, ANOVA with a post hoc Scheffe test, and multiple logistic regression. Results: Major findings of this study were significant differences of planned length of breastfeeding and breastfeeding self-efficacy in relation to the differing types of breast feeding community visits by mothers. In multivariate logistic regression, baby's age, exclusive breastfeeding at hospital, utilization of breastfeeding care service facility, planned length of breastfeeding, and breastfeeding self-efficacy were independent predictors of the feeding type. Conclusion: In order to increase breastfeeding rates, programs provided by public health care services and medical facilities should start education on breast feeding in the hospital before mothers are discharged and then continue through the use of Sanhujori service facilities and workplace at 3 month and 6 month postpartum.

• The KIPS Transactions:PartC
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• v.18C no.6
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• pp.433-440
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• 2011

In this paper, we propose a new scheduling method that can guarantee reliable jitter by minimizing the queue length variation in the streaming service provisioning such as IPTV and VoD. The amount of traffic to be delivered within a certain time is very fluid because MPEG-4 and H.264 encoders use VBR(Variable Bit Rate) for delivering video streaming traffic. This VBR characteristic increases the end-to-end propagation delay variation when existing scheduling methods are used for delivering video frames. Therefore, we propose the new scheduling method that can minimize change rate of queue length by adaptively controling service rate taking into account the size of bulk incoming packets and arrival rate for bulk streaming traffic. Video frames can be more reliably transmitted through the minimization of the queue length variation using the proposed method. We use the queueing model and also carry out OPNET simulation to validate the proposed method.