• 대한산업공학회지
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• 제34권1호
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• pp.23-31
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• 2008

This paper presents accelerated degradation test plans considering adoption of tightened critical values. Under arandom coefficient degradation rate and log-linear acceleration models, the asymptotic variance of an estimatorfor a lifetime quantile at the use condition as the optimization criterion is derived where the degradation ratefollows a lognormal and Reciprocal Weibull distributions, respectively and then the low stress level andproportions ofunits allocated to each stress level are determined. We also show that the developed test plans canbe applied to the multiplicative model with measurement error.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.39-44
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• 2012

This paper deals with the characteristic analysis of small power brushless DC (BLDC) motor considering the rotor magnet overhang flux. In the driving characteristics analysis using 2D FEA (Finite Element Analysis), the rotor magnet overhang effect can't be considered and it should be neglected. To consider rotor magnet overhang effect, 3D FEA should be required. But 3D FEA requires very long calculation time even though the high specification computer is used. In this paper, the 3D electromagnetic model of BLDC motor is approximated as the 2D electromagnetic model considering overhang effect. In this paper, the concept of overhang coefficient is applied, and the coefficient according to load torque variance is deduced.

• 아동학회지
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• 제6권1호
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• pp.41-59
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• 1985

The present research investigated the validity and reliability of the Verbal and Figural tests of the Torrance Tests of Creative Thinking(TTCT). Its potential as a basis of normative data, and differences in children's sex and grade in school were also examined. The subjects of this study were 360 children (180 boys, 180 girls) enrolled in two public elementary schools grades 1-6. Pearson's product-moment coefficient and two-way analysis of variance were used for analyzing data collected from these tests. The present research showed a coefficient of concurrent validity of the TTCT-Verbal test of .40. The coefficient of equivalence from reliability between the TTCT-Verbal test and TTCT-Figural test was .65 (p<.01). Regarding the coefficient of interscorer reliability, the total score of the TTCT-Verbal test was .86 and that of the TTCT-Figural test was .95. The coefficient of intrascorer reliability on the total score of the TTCT-Verbal test was .93 and that of the TTCT-Figural test was .96. Generally, score reliability was .86 to .96 in total score but there were great differences in the reliability of sub-factor scores. There were no significant differences between boys and girls in the distribution of scores on the TTCT-Verbal test and the TTCT-Figural test. There were significant differences between grades (p<.01) on the distribution of total scores and subfactor scores of the TTCT-Verbal Test.

• 한국소음진동공학회논문집
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• 제27권2호
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• pp.243-250
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• 2017

In this study, single number rating methods of sound absorption coefficients are discussed. After that the sound absorption performance of noise barriers which are classified by Korea Standard are analyzed according to several standards. The existing rating methods such as NRC (noise reduction coefficient), SAA (sound absorption average) or ${\alpha}_w$ (weighted sound absorption coefficient) from ASTM C423, KS F 3505 and ISO 11654 are introduced. The sound absorption performance of noise barrier is evaluated to compare NRC and ${\alpha}_w$ value. When the value is over 0.6 there are large variance between NRC and ${\alpha}_w$ value. As results, it is needed to unify single number rating methods of sound absorption coefficients for Korean standards on sound absorbing materials.

• Journal of Ginseng Research
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• 제42권2호
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• pp.158-164
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• 2018

Background: The study was carried out to assess the genetic variability present in ashwagandha and to examine the nature of associations of various traits to the root yield of the plant. Methods: Fifty-three diverse genetic stocks of ashwagandha (Withania somnifera) were evaluated for 14 quantitative characteristics. Analysis of variance, correlation, and path coefficient analysis were performed using the mean data of 2 years. Results: Analysis of variance revealed that the genotypes differed significantly for all characteristics studied. High heritability in conjunction with high genetic advance was observed for fresh root weight, 12 deoxywithastramonolide in roots, and plant height, which indicated that selection could be effective for these traits. Dry root weight has a tight linkage with plant height and fresh root weight. Further, in path coefficient analysis, fresh root weight, total alkaloid (%) in leaves, and 12 deoxywithastramonolide (%) in roots had the highest positive direct effect on dry root weight. Conclusion: Therefore, these characteristics can be exploited to improve dry root weight in ashwagandha genotypes and there is also scope for the selection of promising and specific chemotypes (based on the alkaloid content) from the present germplasm.

• 한국지능시스템학회논문지
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• 제14권5호
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• pp.617-622
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• 2004

본 논문에서는 컬러영상에서 Pulse-Coupled Neural Network를 이용한 얼굴 추출 알고리즘의 성능을 향상시키는 방법에 대하여 논의하였다. 색상정보를 이용한 얼굴 추출 알고리즘은 얼굴의 기울어진 정도나 크기 등에 영향을 받지 않으므로, 형태정보를 이용한 얼굴 추출 알고리즘에 비해 비교우위를 가진다. 그러나, 조명의 변화가 심하거나 피부색과 유사한 배경이 포함되어 있을 경우 적절한 성능을 내기 어렵다. 이러한 문제점들을 해결하기 위해 본 논문에서는 실험을 통해 피부색의 평균과 분산 값을 미리 구한 후, 전처리 과정을 거쳐 피부색의 평균값을 갖는 픽셀이 255값을 갖고, 나머지 픽셀 값들이 255를 중심으로 정규분포를 이루도록 하였다. 이러한 전처리 과정을 통해 Pulse-Coupled Neural Network의 linking coefficient를 보다 쉽게 결정하도록 하였다.

• 대한토목학회논문집
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• 제28권2D호
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• pp.155-162
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• 2008

본 연구에서는 전체 시간대별 교통량을 관측하지 못하여 설계시간교통량을 구할 수 없는 지점에 대하여 설계시간계수를 추정하는 방법에 대하여 분석하였다. 수시조사는 연 1~5회 조사되며, 이러한 지점에서는 설계시간교통량을 구할 수 없어 설계시간계수를 구할 수 없다. 분석을 위하여 2006년 일반국도 상시조사 지점의 시간대별 교통량을 이용하여 분석하였다. 설계시간계수를 추정하기 위하여 시간대별 교통량의 변동을 반영하는 시간대별 교통량의 변동계수(Coefficient of Variance), 시간대별 교통량의 표준편차, 첨두시간교통량(peak hour volume)과 도로의 특성을 파악할 수 있는 중차량비율, 주야율, AADT와 중방향계수 등의 변수를 독립변수로 하여 각 변수들과 설계시간계수와의 상관분석 및 회귀분석을 이용하여 설계시간교통량을 추정하였다. 산점도를 통하여 독립변수와 종속변수의 관계를 분석한 결과 대부분의 변수들이 곡선의 형태를 띠는 것으로 나타나 선형회귀분석보다 곡선회귀분석이 더 적합한 것으로 나타났다. 곡선회귀분석으로 분석한 결과 AADT를 독립변수로 하여 분석한 대수모형이 결정계수가 가장 높은 것으로 나타났다.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1185-1194
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• 2000

The characteristics of intake port flow and engine performance with swirl ratio variance in a turbocharged D.I. diesel engine were studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. Through these experiments it can be expected to satisfy performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer, NOx and smoke were measured by gas analyzer and smoke meter. The results of steady flow test are as follows; as the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. Also we realized that there is a trade-off that the increase of swirl ratio decreases mean flow coefficient and increases the Gulf factor. And the optimum parameters to meet performance and emission through engine test are as follows; the swirl ratio 2.43, injection timing BTDC 13oCA and compression ratio 15.5.

• 한국음향학회지
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• 제19권7호
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• pp.34-41
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• 2000

본 논문에서는 장거리 통신시스템의 적응 반향제거 기에서 퍼지제어 시스템에 기초한 새로운 동시통화 검출방법을 제안하였다. 이 방법에서, 동시통화 검출을 위한 퍼지추론의 두 입력 변수는 근단 신호와 실제 반향 신호가 더해진 소요 신호와 에러 신호 사이의 상호상관계수와 소요 신호와 추정된 신호 사이의 상호상관계수를 사용하였다. 퍼지 제어기에서 사다리꼴 소속함수로 퍼지화하고 if-then 추론규칙을 이용하여 max-min 합성하였으며, 합성된 결과를 무게중심법에 의하여 디퍼지화한 값으로 동시통화와 반향경로 변화 그리고 동시통화시 반향경로 변화를 검출하도록 하였다. 퍼지 동시통화 검출기는 기존의 알고리듬보다 동시통화와 반향경로 변화를 추정할 수 있었으며 동시통화시에 반향경로 변화에도 좋은 성능을 보였다.

• Child Health Nursing Research
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• 제9권3호
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• pp.323-331
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• 2003

Purpose: The purpose of this study is to analyze the factors affecting Deviant Behaviors of Korean High school Students. Method: Data was collected from October 8 to 31, 2002. The subjects for this study were 697 Korean High school Students(boys 347, girls 350), recruited from two High School located in Seoul. Data collection was conducted through the use of 6 Questionnaire that modified by the investigator. The data was analyzed by the SPSS win 10.0 program using Descriptive statistics, Pearson Correlation coefficient and stepwise multiple regression. Result: 1) The mean of total item score the Deviant Behaviors scales was 1.59, which was slightly low. 2) There was a significant correlation between Deviant Behaviors, Type A Personality, Aggression, Impulsivity, Stress and Social Support(γ= .11 ～ .65, p<.001), but It was no significant correlation Type A Personality and Stress(γ= -.01). 3) Stepwise multiple regression analysis showed that (1) Impulsivity, Social Support and Type A Personality were the predictors of Deviant Behaviors and account for 18.6％ of the variance in Deviant Behaviors. (2) Impulsivity account for 3.6％ of the variance in Deviant Behaviors in Subjects with a lower degree of score the Deviant Behaviors. Impulsivity and Social Support account for 23.2％ of the variance in Deviant Behaviors in subjects with higher degree of score the Deviant Behaviors. (3) Impulsivity account for 18.3％ of the variance in Deviant Behaviors in High school girls (n=350). Impulsivity and Social Support account for 20.1％ of the variance in Deviant Behaviors in High school boys (n=347). Conclusion: Impulsivity and Social Support account for Deviant Behaviors of High school Students. Therefore it is necessary to develop nursing intervention to reduce the level of Impulsivity, to increase the Social Support in order to decrease the Deviant Behaviors.