• 한국자동차공학회논문집
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• 제9권5호
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• pp.75-81
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• 2001

This paper presents the atomization characteristics of single hole injector in the direct injection type diesel engine. The spray characteristics of fuel injector such as the droplet size and velocity were measured by phase Doppler particle analyzer. In this paper, the atomization characteristics of fuel spray are investigated for the experimental analysis of the measuring data by the results of mean diameter and mean velocity of droplet. The effect of fuel injection pressure on the droplet size shows that the higher injection pressure results in the decrease of mean droplet diameter in the fuel spray. The minimum size of fuel spray droplet appears on the location of 40mm axial distance from nozzle exit of diesel injector. Based on the experimental results, the correlation between the droplet diameter and mean velocity of the diesel spray due to the change of axial and radial distance from the nozzle tip were investigated.

• 한국가스학회지
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• 제7권4호
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• pp.20-23
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• 2003

공정설비의 신뢰도분석은 자주 Weibull 분포에 기초를 둔 모델을 사용한다. 여기에 사용되는 매개변수들은 조업조건의 함수로서 실험에 의해 값이 결정되며 이를 토대로 신뢰도, 평균수명 및 표준편차를 계산한다 이때 기존 방법은 조업조건이 일정하다고 가정하고 이 매개변수들을 상수로 취급한다. 본 논문에서는 척도모수가 시간의 함수일 때 적용할 수 있는 신뢰도함수 및 이를 토대로 한 분석기법을 제안한다. 냉각팬에 대한 사례연구 결과 평균조업조건을 적용한 기존 방법과 큰 차이를 보였다. 제안된 방법은 다른 공정설비들에도 적용 가능하며 조업조건변화가 설비신뢰도에 미치는 영향을 효과적으로 고려할 수 있을 것으로 기대된다.

• Journal of the Korean Data and Information Science Society
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• 제21권3호
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• pp.447-459
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• 2010

본 연구는 메타분석에서 헤지의 표준화된 평균차를 이용하여 당뇨에 걸린 쥐들에게 프로폴리스를 투여하여 체중, 혈당량, 콜레스테롤, 트리글리세리드의 평균비교를 통해 프로폴리스의 항-당뇨 효과에 대해 알아보았다. 고정효과모형을 적용시킨 결과 혈당량의 감소, 콜레스테롤 농도의 감소, 트리글리세리드 농도의 감소에 대해 유의한 효과를 보였고, 동질성 검정을 통해 동질성을 만족하지 않은 모든 변수에 대해 랜덤효과모형을 적용시킨 결과 혈당량의 감소와 트리글리세리드 농도의 감소에 대해 유의한 효과를 나타냈다. 또한 프로폴리스의 투여기간과 투여량에 대해 메타회귀분석을 실시한 결과, 투여기간이 체중, 혈당량, 콜레스테롤에 유의한 변수로 나타났다.

• 수산해양교육연구
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• 제24권5호
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• pp.616-626
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• 2012

The purpose of this study is to verify career maturity, achievement goal, learning attitude and academic achievement relation with subjects-related career education of middle school students. To achieve these aims, this study used SELS(Seoul education longitudinal study) of Seoul Education Research & Information Institute. Also, analysis as well as descriptive statistics calculation on average, deviation, skewness and kurtosis of variable factor and calculated characteristic item and degree of reliability(Cronbach ${\alpha}$). For goodness of fit test, this study used TLI(Tucker-Lewis index) and RMSEA(Root mean square error of approximation). To achieve the ultimate objects, this study used LMA(latent mean analysis) for analysis of difference career maturity, achievement goal, learning attitude and academic achievement relation with subjects-related career education in middle school students. The results are as follows. First, experience relation with subjects-related career education were influenced on career maturity with career cognition. Second, experience relation with subjects-related career education were influenced on achievement goal, learning attitude, and larger than career maturity and academic achievement. Third, experience relation with subjects-related career education were influenced on middle school students more than inexperienced relation with subjects-related career education.

• Wind and Structures
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• 제28권6호
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• pp.381-388
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• 2019

This paper described the application of Geospatial Analysis in determining mean wind speed, $V_h$ for wind load calculation imposed to electrical transmission tower structural design. The basic wind speed data on available station obtained from Malaysian Meteorology Department is adjusted by considering terrain and ground roughness factor. The correlation between basic wind speed, terrain factor and ground roughness stated in EN-50341-1 is used to obtain the $V_h$ for overhead transmission line elements 50 m above ground. Terrain factor, $k_r$ and ground roughness, $z_0$ in this study are presented by land use types of study area. Wind load is then calculated by using equation stated in design code EN-50341-1 by using the adjusted mean wind speed. Scatter plots of $V_h$ for different $k_r$and $z_0$ are presented in this paper to see the effect of these parameters to the value of $V_h$. Geospatial analysis is used to represent the model of $V_h$. This model can be used to determine possible area that will subject to wind load which severe to the stability of transmission tower and transmission line.

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1812-1819
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• 2003

This paper presents the effect of injection pressure on the atomization characteristics of high-pressure injector in a direct injection gasoline engine both experimentally and numerically. The atomization characteristics such as mean droplet size, mean velocity, and velocity distribution were measured by phase Doppler particle analyzer. The spray development, spray penetration, and global spray structure were visualized using a laser sheet method. In order to investigate the atomization process in more detail, the calculations with the LISA-DDB hybrid model were performed. The results provide the effect of injection pressure on the macroscopic and microscopic behaviors such as spray development, spray penetration, mean droplet size, and mean velocity distribution. It is revealed that the accuracy of prediction is promoted by using the LISA-DDB hybrid breakup model, comparing to the original LISA model or TAB model alone. And the characteristics of the primary and secondary breakups have been investigated by numerical approach.

• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.220-228
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• 1996

This paper presents a extended stochastic Petri net (ESPN) model for CTN(Circulated Token with No duration) service in the data link layer of IEC/ISA fieldbus. It is assumed that a station on the fieldbus has a specified minimum token holding time, a finite capacity buffer, and one transmitter queue with the highest priority. The mean transmission (or service) time at a station and the mean token rotation time for the symmetric fieldbus system atr derived using the presented SPN model and the moment generating function. These performance measures are represented in terms of the minimum token holding time, the number of stations, the arrival rate of messages, and the mean length of messages. The presented performance measure are validated by computer simulations.

• 말소리와 음성과학
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• 제3권1호
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• pp.145-151
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• 2011

In view of the hypothesis that the effects of Parkinson's disease on voice production can be detected before pharmacological intervention, the prosodic features of patients with idiopathic Parkinson's disease (IPD) and a healthy aging group were diagnostically analyzed with the long term object of establishing, for clinical purposes, early disease-progression biomarkers. Twenty patients (male 8; female 12) with IPD (prior to pharmacological intervention) and a healthy control group of 22 (male 10; female 12) were selected. Ten sentences were recorded with a head-worn microphone. One sentence was chosen for the analysis of this paper. Relevant parameters, i.e. 3-dimensional model (F0, intensity, duration) and pitch and intensity related slopes (maxEnergy, maxF0, meanAbS, semiT, meanEnergy, meanF0), were analyzed by two-group discriminant analysis. The stepwise estimation method of discriminant analysis was performed by gender. The discriminant functions predicted 83.9% of the male test data correctly while the prediction rate was 93.1% for the female group. The results showed that meanF0_slope and semiT_slope were more important parameters than the others for the male group. For the female group, the meanEnergy_slope and maxEnergy_slope were the important ones. These findings indicate that significant parameters are different for the male and female group. Gender lifestyle may be responsible for this difference. Dysprosodic features of IPD show not simultaneously but progressively in terms of F0, intensity and duration.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 추계학술발표대회
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• pp.1413-1415
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• 2015

본 논문에서 우리는 의상영역의 유사성을 검사 시 색상분석에 있어 정확도를 향상시키기 위해 Bilateral 필터와 Mean-Shift 알고리즘을 적용하였다. 본 연구의 평가부분에서 필터를 적용한 영상이 의상영역의 구김이나 빛에 의한 영향이 필터를 적용하지 않은 영상보다 적다는 것을 실험을 통해 증명한다.

• 한국도로학회논문집
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• 제7권4호
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• pp.211-219
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• 2005

교통사고 분석구간 선정은 유사한 사고유형을 하나의 동일집단으로 처리함으로써 분석의 효율성을 높이고, 효과적인 개선 사업을 위해 그 순위를 결정하는데 필요한 작업이다. 기존에는 도로이정에 기초하여 균등하게 분할하는 방법을 주로 사용하여 왔는데 사고간의 유사성을 전혀 고려하지 못하는 단점이 있다. 따라서 최근 도로이정보다는 사고간의 유사성을 고려하여 구간을 선정하는 방식인 Slider length 적용기법이 사용되고 있다. 본 연구에서는 Slider length 적용기법의 한 방법론으로써, 군집분석에 사용되는 비계층적 분류기법인 K-평균법을 사용하여 가장 인근거리에 발생된 사고들이 최대한 하나의 집단으로 분류될 수 있는 기법을 제시하고자 한다. 또한 이의 검증을 위해 경부고속도로 부산방향으로 총연장 25.6km구간에 대하여 균일간격에 의한 분할방식과 K-평균법을 이용한 분할방식에 대해 상호 비교를 통해 그 효율성을 검토하였으며, K-평균법이 사고의 유사성이나 인접성을 감안하여 효율적으로 분석구간 선정에 적용될 수 있음을 검증하였다.