• 동력기계공학회지
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• 제22권1호
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• pp.18-24
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• 2018

This paper focuses on systematic design about the membership ranges of the main design factors such as control error, control error rate, and sampling time for the fuzzy logic control of the variable speed drive refrigeration cycle. The upper and the lowest limit of the membership ranges are set up from the data of static characteristics obtained by experiments. Three kinds of membership ranges on the control error and the control error rate are tested by experiments. Especially, an effect of sampling time on control performance is also investigated in the same way. Experimental data showed the control error rate and the sampling time strongly effected on the control performance of the refrigeration cycle with a variable speed drive.

• Journal of the Korean Data and Information Science Society
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• 제14권3호
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• pp.429-440
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• 2003

Variable sampling rate (VSR) control charts vary the sampling interval and/or the sample size according to value of the control statistic. It is known that $\bar{X}$ charts with VSR scheme lead to large improvements in performance over those with fixed sampling rate (FSR) scheme. In this paper, we studied $\bar{X}$ charts with several VSR schemes, and compared their statistical performance each other.

• 한국산업정보학회논문지
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• 제9권3호
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• pp.1-10
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• 2004

주문형 비디오 시스템에서 가변 비트율로 압축된 데이터들은 압축 대상이 되는 데이터의 내용 변화와 압축 기법의 특성으로 인해 단위 시간 당 처리해야 할 데이터 크기가 일정하지 않다. 그러나, 대부분의 주문형 비디오 서버들은 가변 비트율로 압축된 데이터를 실시간에 처리하기 위해 가변 데이터 크기의 최대값으로 시스템 자원을 예약하기 때문에 자원의 활용률이 떨어진다. 본 논문에서는 가변 비트율로 압축된 데이터를 예약할 때 선반입을 사용하여 서버의 사용자 수용 가능성을 극대화할 수 있음을 증명하고 이를 구현한 버퍼 관리 기법을 제안한다. 제안된 버퍼 관리 기법은 현실적으로 가능한 최대의 블록들을 사용 순서에 따라 버퍼에 반입한다 또한, 소비 시점이 먼 블록부터 반출하고 소비 시점이 가까운 블록부터 반입함으로써 비디오 서버의 자원 활용률을 최대화할 수 있다. 본 논문에서 제안한 버퍼 관리 기법의 효율성은 모의 실험을 통해 확인하였다.

• 한국연초학회지
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• 제24권2호
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• pp.107-112
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• 2002

There are many combination with the porosity of tipping paper and plug wrap for a design of ventilation rate of cigarette. This study was carried out to determine the effect of a design of permeability of tipping paper and inner or outer of plug wrap on the ventilation rate of cigarette with constant pressure drop in column part and filter part. Our results indicated that the higher the plugwrap porosity, the higher the ventilation rate and the less variable of cigarette in case of mono filter. But, in case of duel filter, the ventilation rate of cigarette was depended on the manufacturing method of filter plug, even though using the same porous plug wrap on inner and outer of filter. We also found that the porosity of outer plug wrap was more effect on the ventilation rate than the porosity of inner plug wrap. As the high porosity of inner plug wrap compared with the porosity of outer plug wrap, the less variable of ventilation rate of cigarette in any combination of the porosity of plug wrap. When we used the higher porous outer plug wrap than inner plug wrap, the ventilation rate of cigarette was high. Also, the higher the inner plug wrap porosity, the less variable of ventilation rate of cigarette.

• 대한음성학회지:말소리
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• 제65호
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• pp.81-91
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• 2008

In this paper, we propose a new variable bit-rate speech coder based on the waveform interpolation concept. After the coder extracted all parameters, the amounts of the distortions between the current and the predicted parameters which are estimated by extrapolation using past two parameters are measured for all parameters. A parameter would not be transmitted unless the distortion exceeds the preset threshold. At the decoder side, the non-transmitted parameter is reconstructed by extrapolation with past two parameters used to synthesize signals. In this way, we can reduce 26% of the total bit rate while retaining the speech quality degradation below 0.1 PESQ score.

• Journal of the Korean Data and Information Science Society
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• 제28권2호
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• pp.443-449
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• 2017

Estimation of population proportion like the distribution rate of LED TV and the prevalence of a disease are often estimated based on survey sample data. Population proportion is generally considered as a special form of population mean. In complex sampling like stratified multistage sampling with unequal probability sampling, the denominator of mean may be random variable and it is estimated like ratio estimator. In this research, we examined the estimation of distribution rate based on stratified multistage sampling, and determined some numerical outcomes using stratified random sample data with about 25% of missing observations. In the data used for this research, the survey weight was determined by deterministic way. So, the weights are not random variable, and the population distribution rate and its variance estimator can be estimated like population mean estimation. When the weights are not random variable, if one estimates the variance of proportion estimator using ratio method, then the variances may be inflated. Therefore, in estimating variance for population proportion, we need to examine the structure of data and survey design before making any decision for estimation methods.

• 한국유체기계학회 논문집
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• 제17권5호
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• pp.83-88
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• 2014

Pumps are widely used in industrial plants, energy systems, ships etc. Generally they consume nearly 20% each nation's total electrical energy. The objective of this study is to find performance evaluating method for variable-speed drive pump. In order to evaluate the variable-speed pump performance energy saving rate for the variable-speed pump is applied and compared with that of constant-speed pump.

• 한국분무공학회지
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• 제25권2호
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• pp.45-50
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• 2020

Recently, global warming and environmental pollution are becoming more important, and fuel economy is becoming important. Each automobile company is actively developing various new technologies to increase fuel efficiency. CVVD(Continuously Variable Valve Duration) system means a device that continuously changes the rotational speed of the camshaft to change the valve duration according to the state of the engine. In this paper, VVT(Variable Valve Timing) and CVVD were applied to a single-cylinder diesel engine, and the characteristics of intake and exhaust flow rate and in-cylinder pressure characteristics were analyzed by numerical analysis. In order to analyze the effect of CVVD on the actual engine operation, the study was performed by setting the valve control and injection pressure as variables in two sections of the engine operating region. As a result, In the case of applying CVVD, the positive overlap with the exhaust valve is maintained, thus it is possible to secure the flow smoothness of air and increase the volumetric efficiency by improving the flow rate. The section 2 condition showed the highest peak pressure, but the pressure rise rate was similar to that of the VVT 20 and CVCD 20 conditions up to 40 bar due to the occurrence of ignition delay.

• 대한전자공학회논문지SD
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• 제49권1호
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• pp.25-34
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• 2012

본 논문은 고속 WPAN 시스템에 대한 가변 길이 8-병렬 리드-솔로몬(RS) 복호기에 관한 일반적인 구조를 제안한다. 제안된 구조는 RS(255,239) 코드뿐만 아니라 다양한 단축화 RS 부호들을 지원 할 수 있다. 특히, 가변길이 구조는 다양한 단축화 RS 부호에 대해 가변적인 낮은 지연을 제공하며, 8-병렬 구조를 적용하여 높은 데이터 처리율을 제공한다. 제안된 RS 복호기는 90-$nm$ CMOS 표준 셀 기술을 사용하여 성능 분석을 수행하였고, 클록 주파수 300$MHz$에서 19-$Gbps$ 데이터 처리율을 제공한다.

• 디지털콘텐츠학회 논문지
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• 제13권1호
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• pp.111-118
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• 2012

버스트는 가변 비트율로 저장된 비디오 데이터를 전송하려는 경우 급격하게 높은 전송률이 요구되는 것으로 네트워크 자원의 비효율적인 사용의 원인이 될 수 있다. 스무딩은 이를 방지하기 위해 가변 비트율로 저장된 비디오 데이터를 고정 비트율로 변환하는 전송 계획을 세우는 기법으로, CBA, MCBA, MVBA 알고리즘들이 있다. 본 논문에서는 기존 CBA, MCBA, MVBA 알고리즘들의 버스트 감소 정도를 평가하기 위해, 가변 비트율로 저장된 비디오 소스와 스무딩 알고리즘에서의 전송 계획을 버스트에 영향을 미치는 요소들로 비교한다. 사용된 평가 요소는 최대 프레임 바이트 수, 최대 GOP 바이트 수, 프레임당 전송률 변화량, GOP당 전송률 변화량이다. 실험 결과, 실험에 사용된 모든 스무딩 알고리즘들의 버스트 관련 평가 요소들이 특정한 경우를 제외하고 원래 비디오 소스보다 낮았다.