• 한국자동차공학회논문집
• /
• 제7권7호
• /
• pp.1-14
• /
• 1999

In the present study, the flame factor which primarily influence the simulation accuracy of the combustion process in a gasoline engine was modeled as a nonlinear function of turbulent intensity to laminar flame speed ratio. Multi-length-scale production rate model for turbulent kinetic energy equation was introduced to consider the different length scales of the swirling and tumbling motions in cylinder on the production rte of turbulent kinetic energy. By7 introducing the multi-length-scale production rate model for the turbulent kinetic energy equation, the predictions of turbulent burning velocity , cylinder pressure, mass burning rate and engine performance of a gasoline engine can much be improved.

• 한국문헌정보학회지
• /
• 제13권
• /
• pp.95-119
• /
• 1986

The objective of this study is to search for a theoretical and practical solution to the question of what is the most effective and qualitative method of information service for the college and university libraries in Korea. Assuming the maximum service or total service theory in information services, therefore, it appears natural that the subject specialist who is highly knowledgeable in his subject is indispensable in raising the quality of information librarians. The procedure of this research was as follows: There was no college and university library employing any full-time subject spceialist in Korea. This research, however, was proceeded on the assumption that subject specialists are already employed in all of the college and university libraries after the subject specialist system is established. The least qualification of subject specialist is limited, based on the criteria given by the foreign literature, to those who have master's degree in Library Science and bachelor's degree in any other subject area, those who have bacholor's degree in Library Science and master's degree in any other subject area, or those who have both bacholor's and master's degrees in Library Science with minor in any subject field . To prove the research hypothesis that the subject specialist will perform his role more efficiently than the generalist in effectively providing information service based on both accuracy and speed, this research as an obtrusive testing method analyzed the effectiveness by presenting information questions to the generalists and subject specialists who are information librarians in college and university libraries. For this study 20 librarians working at 12 university libraries were tested for performance levels of information services. The result showed $59.75\%$ an absolute performance rate and $75.20\%$ an adjust performance rate. Compared to Thomas Childer's 1970 study in which he used the unobtrusive testing method, these results were $5\%$ higher in the absolute performance rate and $11.36\%$ higher in the adjust performance rate. In comparing the generalist with the subject specialist in efficiency of information service, while the absolute performance rate was $57.08\%$ and the adjust performance rate was $73.08\%$ in the case of the generalist, the absolute rate was $63.75\%$ and the adjust rate was $78.38\%$ in the case of specialist, therefore, the efficiency of the subject specialist was $6.67\%$ higher in the absolute performance rate and $5.30\%$ higher in the adjust performance rate than that of generalist. But the factor of speediness was excluded from the analysis because of the difference between the time the interviewers recorded and the time the interviewee recorded. On the basis of the result of this research, it should be desirable to educate subject specialists and employ them as information librarians and for them to function as efficient subject specialists in order to improve the effectiveness of information services, the nucleus of the raison d'etre of college and university libraries.

• 대한기계학회논문집B
• /
• 제20권4호
• /
• pp.1491-1500
• /
• 1996

Unstable performance deterioration was found on the performance curve of a small propeller fan with a back plate. To investigate this phenomenon and the effects of the back-plate on the performance of the fan, performance tests and flow measurement using 3-hole pitot tube were carried out. Measurements showed that when the flow rate is small, the radial flow dominates, and when the flow rate is large, the axial flow dominates. Performance characteristic of the propeller fan changes from radial to axial type as the flow rate increases. Unstable performance changes are the result of type change of the flow through the fan.

• 한국분무공학회지
• /
• 제19권2호
• /
• pp.64-68
• /
• 2014

A driving vehicle performance which is driven by FTP-75 mode was simulated by computer. Throttle valve position, engine speed, air mass flow rate, fuel consumption et al. were computer simulated. A set of engine part load performance data, automatic transmission shift map and vehicle specifications were used for the computer simulation. Throttle valve position, engine speed, air mass flow rate et al. measured for evaluating the computer simulation results by driving the vehicle with FTP-75 mode on a chassis dynamometer. GT-Power$^{(R)}$ software was used for the computer simulation of the driving vehicle performance. Experimental fuel consumption rate was measured by using an ECU HILS fuel injection system. The experimental data and simulation results were compared. The computer simulation of the driving vehicle performance predicts the measured data well comparatively.

• 산업경영시스템학회지
• /
• 제34권3호
• /
• pp.115-122
• /
• 2011

The critical role played by manufacturing performance measurement systems in achieving competitive success is increasingly recognized. Developing an integrated performance measurement model is significant for strategic management. This study consist of several principal steps. Performance criteria from the literature and an questionnaire were utilized prior to building the performance model. The AHP(Analytic Hierarchy Process) is utilized to evaluate the weight of each criterion when generating the performance measurement model for Korea automobile parts manufacturing company. AHP analysis showed clear difference in the priority between 5 criteria and 24 sub-criteria in terms of manufacturing performance of Korean automobile parts manufacturing company. The result of priority evaluation in the 5 criteria of 2nd level was ranked quality, cost, delivery, employee, flexibility. And the critical sub-criteria in the 24 sub-criteria of 3rd level was ranked claim rate, process defect rate, outsourcing parts defect rate, ability to quality management innovation, claim cost, etc.

• 한국환경보건학회지
• /
• 제32권2호
• /
• pp.179-185
• /
• 2006

Effect of organic loading rate on UASB performance was evaluated under the renditions of some surface area/reactor volume ratio and different reactor diameter. At the low leading rate of 0.4 kg $COD/m^3{\cdot}d$, reactor performance was not affected by reactor diameter. At the organic loading rate of 6 kg $COD/m^3{\cdot}d$, however, volatile acid accumulation and low COD removal efficiency is observed in reactor having 6.4 cm diameter, while volatile acid is not accumulated at all and high COD removal efficiency is observed in reactor having 3 cm diameter. Such a difference of reactor performance depending on reactor diameter can be explained that sludge bed can be fluidized by evolved gas bubble in narrow reactor, while sludge bed ran not be fluidized by evolved gas bubble only in wide reactor. At a high organic loading rate of 20 kg $COD/m^3{\cdot}d$, it can be judged that there is no relation between reactor configuration and reactor performance because all reactors showed very low COD removal efficiencies regardless of reactor diameter. Narrow and tall type reactor is favorable condition for making sludge bed fluidization at a constant surface area/reactor volume ratio. Thus, it can be judged that reactor configuration and sludge bed fluidization have great influence to reactor performance.

• 디지털융복합연구
• /
• 제18권3호
• /
• pp.275-285
• /
• 2020

본 연구는 임상간호사들의 벨트형 손소독제 활용에 대한 손소독 수행정도와 수행률, 손소독제 사용 만족도에 대한 효과를 파악하고자 수행된 연구이다. 연구수행을 위해 단일군 전후 유사실험 설계를 이용하였으며, 벨트형 손소독제 활용에 대한 효과평가는 손소독 수행 정도, 손소독 수행률, 손소독제 사용에 대한 만족도로 자가보고형 설문지를 이용하여 측정하였다. 연구 대상자는 일 지역의 종합병원 병동의 임상간호사 50명을 대상으로 하였으며, 수집된 자료는 SPSS 23.0 프로그램을 이용하여 분석하였다. 연구결과, 벨트형 손소독제 사용 후의 손소독 수행 정도, 손소독 수행률, 손소독제 사용 만족도가 유의하게 높은 것으로 나타났다. 본 연구를 통해 벨트형 손소독제는 손소독 수행정도와 손소독 수행률을 향상시킬 수 있는 효과적인 방법임을 확인하였다. 따라서 임상실무에서 벨트형 손소독제를 활용한다면, 손소독 수행 정도와 수행률 향상에 기여할 수 있을 것이다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 하계종합학술대회 논문집(1)
• /
• pp.55-58
• /
• 2004

This this paper, we propose vertical Bell laboratories layered space time (V-BLAST) system based on variable rate Low-Density Parity Check (LDPC) codes to improve performance of receiver when QR decomposition interference suppression combined with interference cancellation is used over independent Rayleigh fading channel. The different rate LDPC codes can be made by puncturing some rows of a given parity check matrix. This allows to implement a single encoder and decoder for different rate LDPC codes. The performance can be improved by assigning stronger LDPC codes in lower layer than upper layer because the poor SNR of first detected data streams makes error propagation. Keeping the same overall code rates, the V-BLAST system with different rate LDPC codes has the better performance (in terms of Bit Error Rate) than with constant rate LDPC code in fast fading channel.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 1997년도 학술대회
• /
• pp.181-186
• /
• 1997

Transcoding is the key technique to further reduce the bit-rate of a previously compressed video. The performance of the transcoding is evaluated by the two factors, the accuracy on the target bit-rate and the complexity of the implementation. In this paper, were propose a new rate control algorithm which has very accurate bit-rate control performance and much smaller computational complexity. For the accuracy problem, we empirically observe the relationship between the quantization step size and generated bits in requantization process and then find that the relationship can be characterized as the new piece-wise linear model. For the complexity problem, we reduce the role of feedback rate control. The simulation results show that the proposed method gives the better performance in the accuracy with the same picture quality than conventional rat control algorithm.

• 정보처리학회논문지C
• /
• 제9C권3호
• /
• pp.399-406
• /
• 2002

본 논문에서는 고정 전송율 서비스 및 가변 전송율 서비스 호들이 동적으로 네트워크에 들어와서 데이터를 전송하고, 데이터를 모두 전송하면 네트워크에서 사라지는 동적인 다중 서비스 네트워크에서, 고정 전송율 및 가변 전송율 서비스의 요구 성능을 만족하기 위한 네트워크 스위치(링크)의 성능 분석 및 설계 방법을 제안한다. 먼저 동적인 다중 서비스 네트워크의 링크를 Harkov 체인을 이용해 모델하고, QBD (Quasi-Birth-Death) 프로세스와 행렬 방정식을 이용해 가변 전송율 서비스의 호들에 할당될 전송율의 성능을 구한다. 즉, 가변 전송율 서비스의 평균 호수를 추정하고 이를 바탕으로, 호당 평균 전송율 및 평균 전송 지연 시간을 구한다. 고정 전송율 서비스의 성능은 고정 전송율 서비스 호들의 차단 확률(blocking probability)로 구해진다. 이렇게 해서 구해진 고정 전송율 및 가변 전송율 서비스의 성능을 이용해서, 고정 전송율 및 가변 전송율 서비스 호들의 요구 성능(전송율, 전송 지연 시간, 호의 차단 확률 등)을 만족하기 위한 네트워크 링크의 용량을 설계하는 방법을 제안한다. 이러한 방법을 데이터 및 음성(비디오)을 동시에 지원하는 네트워크 스위치의 성능 분석 및 용량 설계에 이용할 수 있다.