• 한국유체기계학회 논문집
• /
• 제16권3호
• /
• pp.10-17
• /
• 2013

The organic Rankine cycle has been widely used to convert the renewable energy such as the solar energy, the geothermal energy, or the waste energy etc., to the electric power. Some previous studies focused to find what kind of refrigerant would be a best working fluid for the organic Rankine cycle. In this study, R245fa was chosen to the working fluid, and the cycle analysis was conducted for the output power of 30kW or less. In addition, properties (temperature, pressure, entropy, and enthalpy etc.) of the working fluid on the cycle were predicted when the turbine output power was controlled by adjusting the mass flowrate. The configuration of the turbine was a radial-type and the supersonic nozzles were applied as the stator. So, the turbine was operated in partial admission. The turbine efficiency and the optimum velocity ratio were considered in the cycle analysis for the low partial admission rate. The computed results show that the system efficiency is affected by the partial admission rate more than the temperature of the evaporator.

• Journal of Information Processing Systems
• /
• 제2권2호
• /
• pp.107-113
• /
• 2006

It is essential to guarantee a handoff dropping probability below a predetermined threshold for wireless mobile networks. Previous studies have proposed admission control policies for integrated voice/data traffic in wireless mobile networks. However, since QoS has been considered only in terms of CDP (Call Dropping Probability), the result has been a serious CBP (Call Blocking Probability) unfairness problem between voice and data traffic. In this paper, we suggest a new admission control policy that treats integrated voice and data traffic fairly while maintaining the CDP constraint. For underprivileged data traffic, which requires more bandwidth units than voice traffic, the packet is placed in a queue when there are no available resources in the base station, instead of being immediately rejected. Furthermore, we have adapted the biased coin method concept to adjust unfairness in terms of CBP. We analyzed the system model of a cell using both a two-dimensional continuous-time Markov chain and the Gauss-Seidel method. Numerical results demonstrate that our CAC (Call Admission Control) scheme successfully achieves CBP fairness for voice and data traffic.

• 인터넷정보학회논문지
• /
• 제17권3호
• /
• pp.87-93
• /
• 2016

현대 지식정보사회에서 정보통신기술은 개인, 사회 및 국가적 차원에서 매우 중요하다. 특히 국가적 차원에서 있어서 정보통신기술관련산업은 매우 중요한 비중을 차지하고 있으며, 다른 산업과는 달리 다양한 기반시설을 필요로 하지 않으며 소수의 인재들에 의하여 단기간에 부흥할 수 있는 장점이 있다. 이러한 관점에서 정보영재 발굴과 교육은 국가의 미래에 있어서 매우 중요한 과제가 되어가고 있다. 과거의 영재교육의 선발은 주로 지필고사를 통해 실시되었으나, 사교육 등 다양한 폐해로 인해 2013년 이후로 관찰추천제 방식이 전면적으로 실시되었다. 본 연구의 목적은 정보영재아동의 관찰추천제 입학제도의 타당성을 분석하는 것이다. 이러한 연구목적을 위해 서울시의 한 대학부설 과학영재교육원에 재학한 정보영재아동들을 대상으로 입학성적과 수료성적의 상관관계 분석을 통해서 관찰추천제의 타당성을 분석하였다. 통계처리결과 정보영재아동은 입학성적과 수료성적의 상관관계를 보였다. 즉 정보영재아동의 경우 입학성적이 좋으면 수료성적이 좋음을 보였다. 본 연구결과는 향후 영재교육에 있어서 관찰추천제의 유용성을 판단하는 데 귀중한 자료가 될 것으로 기대한다.

• 한국보건간호학회지
• /
• 제16권1호
• /
• pp.201-212
• /
• 2002

This study was designed to identify the risk factors of unplanned readmission in a university hospital. The six-month discharge information from January to June, 2000 in a tertiary university hospital was used as a source of data through the medical record and hospital information system. To increase the effect of comparison. the data were collected by sampling 192 couples (384 patients) of unplanned readmission group through the matching by its disease groups, sex, and age. The accuracy of prediction for unplanned readmission was analyzed by constructing the predicted model of unplanned readmission through the logistic regression. The study results are as follows. The conditional logistic regression analysis was performed with nine variables at the significance level 0.05 through univariate analysis including residence, days after discharge, initial admission route, previous admission, transfer to special care unite, hospital stay days, medical care expenses, special cares, and laboratory and imaging services. As a result, the closer the patients live in Seoul and Gyeong-in area (Odds ratio=2.529, p=0.003), the shorter the days after discharge was (Odds ratio=0.600, p=0.000), and the more frequent admission rate was (Odds ratio=2.317, p=0.004), the more unplanned readmission was resulted. Also, the accuracy of prediction for data classification of this regression model showed $70.3\%$(032+83/306).

• Journal of Communications and Networks
• /
• 제15권1호
• /
• pp.15-24
• /
• 2013

Provisioning of quality of service (QoS) is a key issue in any multi-media system. However, in wireless systems, supporting QoS requirements of different traffic types is a more challenging problem due to the need to simultaneously minimize two performance metrics - the probability of dropping a handover call and the probability of blocking a new call. Since QoS requirements are not as stringent for non-real-time traffic, as opposed to real-time traffic, more calls can be accommodated by releasing some bandwidth from the already admitted non-real-time traffic calls. If the released bandwidth that is used to handle handover calls is larger than the released bandwidth that is used for new calls, then the resulting probability of dropping a handover call is smaller than the probability of blocking a new call. In this paper, we propose an efficient call admission control algorithm that relies on adaptive multi-level bandwidth-allocation scheme for non-realtime calls. The scheme allows reduction of the call dropping probability, along with an increase in the bandwidth utilization. The numerical results show that the proposed scheme is capable of attaining negligible handover call dropping probability without sacrificing bandwidth utilization.

• ETRI Journal
• /
• 제29권1호
• /
• pp.113-115
• /
• 2007

A dynamic tri-threshold call admission control scheme has been developed. This scheme supports voice, data, and multimedia services and it complies with the universal mobile telecommunications system. The performance of the proposed scheme is evaluated under varying handover rates. The QoS performance-including channel utilization, call dropping probability, and blocking probability-is investigated. The performance of the developed scheme is found to be encouraging.

• Journal of the Korean Data and Information Science Society
• /
• 제17권3호
• /
• pp.677-685
• /
• 2006

During the previous few years, local universities have experienced a rapid decrease in registration of new student for admission because of the problem of excessive concentration to Seoul metropolitan area and decrease in the number of population under school ages. Even though they are tring to survive from the difficulties by developing new strategies to increase the number of new students, it has no meaning if there is no standpoint of marketing. So, this study suggests that introduction of demander focused marketing concept actively is needed breaking the general and conservative method when the university devise entrance examination strategy. Also, using of positioning map is suggested and the examples are showed as finding differentiation factors with competitive university.

• 디지털융복합연구
• /
• 제14권4호
• /
• pp.437-448
• /
• 2016

본 연구는 대학에서 학생들에게 입학과 함께 전문지식과 덕성을 갖출 수 있도록 관리 지원하는 프로그램(K-Leader마일리지)을 통해 대학생의 핵심역량 데이터를 입학전형 유형별로 나누어 그 차이를 비교 분석하였다. 분석결과는 리더십과 인간관계 영역을 제외하고 나머지 영역은 상대적으로 활동인원이 많이 부족한 것으로 나타났다. 리더십과 인간관계는 수능위주(수능) > 학생부위주(교과), 학생부위주(종합) 학생부위주(교과) 수능위주(수능) > 수능위주(수능+학생부), 글로벌 영역은 수능위주(수능+학생부) 수능위주(수능) > 학생부위주(종합), 수능위주(수능+학생부) 수능위주(수능) > 학생부위주(교과), 진로 및 취업활동은 학생부위주(종합) 학생부위주(교과) > 수능위주(수능+학생부), 마일리지점수 합계는 수능위주(수능) > 학생부위주(교과) 수능위주(수능)의 결과로 나타났다. 이러한 결과로 볼 때, 리더십과 인간관계의 항목인 공동체 참여의 활동만으로 보면 기존 연구와 같이 학생부위주(종합)전형의 학생이 학교생활을 잘한다는 연구 결과와 같다. 그러나 본 논문에서의 K-Leader 마일리지 분석결과는 수능위주(수능)전형이 대학생활을 잘 한다는 결과를 얻을 수 있었다.

• 한국식품영양학회지
• /
• 제31권1호
• /
• pp.52-61
• /
• 2018

The purpose of this study is to examine the feeding and nutritional status of enteral tube-fed elderly patients. Subjects included 77 elderly hospitalized patients who had received enteral nutrition more than one week before admission. Medical records on admission and actual feeding volume were used to assess anthropometric, biochemical, and nutritional status. Most patients manifested disorders of the nervous system (93.5%) and the average duration of tube feeding was 13.9 months. The average feeding volume of formula was 1,107 mL per day and the mean ratios of calorie and protein (supplied vs. required) were 81.7% and 80.9%, respectively. At admission, 57.4% of the patients were malnourished according to the institutional criteria. Patients receiving less than 80% of the required calories were in worse nutritional status compared with those receiving more than 80% of the required calories. Body mass index, percent ideal body weight, serum albumin level and blood lipid levels (total cholesterol, HDL-cholesterol, triglyceride) were significantly lower in patients receiving less than 80% of the required calories. These results indicate the high prevalence of malnutrition and the need for increased attention and nutritional care of elderly patients undergoing long-term enteral nutrition.

• 임상간호연구
• /
• 제28권1호
• /
• pp.1-12
• /
• 2022

Purpose: The purpose of this study is to investigate the association between the nurse staffing level and the patient mortality using Korean National Health Insurance data. Methods: The data of 1,068,059 patients from 913 hospitals between 2015 and 2016 were analyzed. The nurse staffing level was categorized based on the bed-to-nurse ratio in general wards, intensive care units (ICUs), and hospitals overall. The x² test and generalized estimating equations (GEE) multilevel multivariate logistic regression analyses were used to explore in-hospital mortality and 30-day mortality after admission. Results: The in-hospital mortality rate was 2.9% and 30-day mortality after admission rate was 3.0%. Odd Ratios (ORs) for in-hospital mortality were statistically lower in general wards with a bed-to-nurse ratio of less than 3.5 compared to that with 6.0 or more (OR=0.72, 95% CI=0.63~0.84) and in ICUs with a bed-to-nurse ratio of less than 0.88 compared to that with 1.25 or more (OR=0.78, 95% CI=0.66~0.92). ORs for 30-day mortality after admission were statistically lower in general wards with a bed-to-nurse ratio of less than 3.5 compared to that with 6.0 or more (OR=0.83, 95% CI=0.73~0.94) and in ICUs with a bed-to-nurse ratio of less than 0.63 compared to that with 1.25 or more (OR=0.85, 95% CI=0.72~1.00). Conclusion: To reduce the patient mortality, it is necessary to ensure a sufficient number of nurses by improving the nursing fee system according to the nurse staffing level.