• 인지과학
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• 제18권3호
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• pp.223-244
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• 2007

이차원 공간에서 운동 자극의 진행 방향으로 위치 오류가 발생되는 명멸 지체효과(Flash lag effect: FLE)와 깊이 방향의 위치 오류가 발생하는 Pulfrich 효과는 각각 독립적으로 연구되어 왔지만 현상적 이론적 유사점이 많다. 본 연구에서는 두 현상의 오류의 크기를 직접적으로 비교하여 두 현상이 동일한 기제에 의해 발생되었을 가능성을 살펴보았다. 보다 구체적으로 각 눈에 제시된 운동 자극의 FLE의 크기가 다를 때 이 차이가 양안시차로 작용하여 Pulfrich 효과의 깊이로 산출될 수 있는 지를 알아보았다. 각 눈에 제시되는 두 운동 자극의 밝기 비율을 네 수준(1:2, 1:3.3, 1:5, 1:10)으로 나눈 다음 이들 자극으로부터 발생되는 Pulfrich 효과의 깊이를 측정하였고, 동일한 실험 상황하에서 Pulfrich 효과의 깊이 측정에 사용되었던 다섯 수준의 자기 자극(1, 2, 3.3, 5, 10)의 FLE 크기를 각각 측정하였다. 본 연구에 포함된 밝기 차 조건하에서 Pulfrich 깊이는 밝기 비율이 커질수록 증가하는 데 반해, FLE의 크기는 큰 차이를 보이지 않았다. 또한 FLE의 차가 양안 시차로 작용한다면 그로부터 예상할 수 있는 Pulfrich 깊이와 실제 측정된 Pulfrich 효과의 깊이는 다른 것으로 나타났다. 이러한 결과는 두 현상이 동일한 기제에 의해서 발생되는 것이 아님을 시사한다.

• Bulletin of the Korean Chemical Society
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• 제16권4호
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• pp.363-369
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• 1995

Hydroiminoacylations of allyl and homoallyl alcohol and their derivatives with benzaldimine by Wilkinson's complex have been studied. All these terminal alkene derivatives except allyl alcohol were hydroacylated according to anti-Markownikoff's rule to give the corresponding linear alkyl compounds without showing oxygen directing effect, even though hydroiminoacylation of 3-acetoxy-1,5-hexadiene showed strong allyloxy directing effect over homoallyloxy directing effect in a 92:8 ratio. Solvolysis of 4-acetoxy-1-phenylbutan-1-one, previously prepared by hydroiminoacylation, in ethanol led to etherification giving 4-ethoxy-1-phenylbutan-1-one through neighbouring group participation, while that of 5-acetoxy-1-phenylpentan-1-one led to common transesterification giving 5-hydroxy-1-phenylpentan-1-one. Application of branched alkanols such as isopropanol and t-butanolin solvolysis of 4-acetoxy-1-phenylbutan-1-one underwent competition between etherification and transesterification.

• 한국조사연구학회지:조사연구
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• 제4권2호
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• pp.47-62
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• 2003

노동부에서 시행하는 $\ll$노동력수요동향조사$\gg$와 $\ll$임금구조기본통계조사$\gg$를 기초로 새로운 조사표와 조사방법의 도입으로 인한 영향을 분석하고 평가하는 간편한 통계적 방법을 제안한다. 두 조사 모두 매우 유사한 표집틀(sampling frame)과 표집법을 공유하고 있기 때문에 두 조사 중 어느 하나를 기준으로 다른 하나의 변동성을 측정할 수 있다. 여기서 제시하는 영향 평가는 연도별로 동일 범주에 속하는 두 독립적인 추계치들의 비를 기초로 진행되며 또한 새로운 조사의 도입 시점을 기준으로 전과 후로 분할된 비 데이터(ratio data)의 변동성을 통계적으로 비교하는 형식을 갖는다.

• 동력기계공학회지
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• 제9권2호
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• pp.14-18
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• 2005

In this study, the spray characteristics of blended fuels with biodiesel were investigated. The experiments were performed for the effect of mixing ratio and injection pressures on the spray behavior. Conventional diesel fuel and biodiesel fuel and blended fuels were used as test fuels. Through the spray visualization system, composed of a Halogen lamp and High speed camera. The process of spray injection was visualized. Fuel containing biodiesel has different spray pattern on account of the high viscosity and large surface tension. Through this experimental result, we found that, after solenoid driving pulse generates, the increase of injection pressure enables delay time to get shorter, but the increase of mixing ratio makes delay time lengthen.

• 소음진동
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• 제7권6호
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• pp.985-991
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• 1997

Combustion instability is a common phenomenon in a ducted flame burner and is known as accompanying low frequency oscillation. This is due to the interaction between unsteady heat release rate and sound pressure field, that is, thermoacoustic feedback. In Rayleigh criterion, combustion instability is triggered when the heat addition is in phase with acoustic oscillation. A Rijke type burner with a pre-mixed flame is built for investigating the effect of Reynolds number and equivalence ratio on thermoacoustic oscillation. The results suggest that the frequency of max, oscillation is dependent on Reynolds number and equivalence ratio whereas its magnitude is not a strong function of these two parameters.

• Genomics & Informatics
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• 제10권2호
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• pp.117-122
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• 2012

A sample size with sufficient statistical power is critical to the success of genetic association studies to detect causal genes of human complex diseases. Genome-wide association studies require much larger sample sizes to achieve an adequate statistical power. We estimated the statistical power with increasing numbers of markers analyzed and compared the sample sizes that were required in case-control studies and case-parent studies. We computed the effective sample size and statistical power using Genetic Power Calculator. An analysis using a larger number of markers requires a larger sample size. Testing a single-nucleotide polymorphism (SNP) marker requires 248 cases, while testing 500,000 SNPs and 1 million markers requires 1,206 cases and 1,255 cases, respectively, under the assumption of an odds ratio of 2, 5% disease prevalence, 5% minor allele frequency, complete linkage disequilibrium (LD), 1:1 case/control ratio, and a 5% error rate in an allelic test. Under a dominant model, a smaller sample size is required to achieve 80% power than other genetic models. We found that a much lower sample size was required with a strong effect size, common SNP, and increased LD. In addition, studying a common disease in a case-control study of a 1:4 case-control ratio is one way to achieve higher statistical power. We also found that case-parent studies require more samples than case-control studies. Although we have not covered all plausible cases in study design, the estimates of sample size and statistical power computed under various assumptions in this study may be useful to determine the sample size in designing a population-based genetic association study.

• Journal of Ginseng Research
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• 제15권2호
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• pp.144-151
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• 1991

This study was conducted to elucidate the effects of light intensity using polyethylene (p.E) net shading on the specific gravity, red ginseng quality, sugar and saponin contents of ginseng root. The specific gravity significantly increased in the ginseng roots grown under the P.E net shading as compared with that of common straw shading. The red ginseng quality under the P.E net shading was improved in order of 10, 5, 15, 20, 30% of light intensity and the inside cavity and inside white part decreased remarkably as compared with those of common straw shading. The ginseng roots grown under the P.E net shading at 10% and 15% light intensity showed a significant increase in the total sugar content but a significant decrease in the reducing sugar content at 15% light intensity as compared with those of common straw shading. The amount of total saponin of ginseng roots was increased under the P.E net shading at high light intensity as compared with that of common straw shading and the ginseng roots grown under the P.E net shading at 10% light intensity showed an increase in the diol group saponin but the ratio of PT/PD was decreased. Extract contents of ginseng root under the P.E net shading was higher than those of common straw shading and the roots grown under the P.E net shading at 15% and 20% light intensity resulted in a remarkable increase in extract contents.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.151-158
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• 2007

The static and dynamic behaviour of VGT and EGR systems has a significant impact on overall engine performance, fuel economy and exhaust emissions. This is because they define the state and composition of the air charge entering the engine. This work focused on the effect of the aperture ratio of VGT and EGR on the emission and flow characteristics under partial loads conditions. The investigation carried out using 2 liter PCCI 4 cylinder diesel engine with VGT and EGR. The result of this study shows that smoke increases with increasing EGR rate and NOx decreases with increasing EGR rate. It was also found that the residual gas contents greatly impact on soot emission under partial load condition. Finally, it can be concluded that VGT and EGR aperture ratio can greatly impact not only on soot and NOx but also air charging.

• 대한기계학회논문집B
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• 제26권1호
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• pp.133-140
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• 2002

This article presents an application of a large-scale structural mixing model(Broadwell et at. 1984) to the blowout of turbulent reacting cross flow jets. Experimental observations, therefore, aim to identify the existence of large-scale vortical structure exerting an important effect upon the flame stabilization. In the analysis of common stability curve, it is seen that the phenomenon of blowout are only related to the mixing time scale of the two flows. The most notable observation is that the blowout distance is traced at a fixed positions according to the velocity ratio at all times. Measurements of the lower blowout limits in the liftable flame are qualitatively in agreement with the blowout parameter $\xi$, proposed by Broadwell et al. Good agrement between the results calculated by a modified blowout parameter $\xi$'and the present experimental results confirms the important effect of large-scale structure in the stabilization feature of blowout.

• Earthquakes and Structures
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• 제7권5호
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• pp.667-689
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• 2014

Structural walls (also known as shear walls) are one of the common lateral load resisting elements in reinforced concrete (RC) buildings in seismic regions. The performance of RC structural walls in recent earthquakes has exposed some problems with the existing design of RC structural walls. The main issues lie around the buckling of bars, out-of plane deformation of the wall (especially the zone deteriorated in compression), reinforcement getting snapped beneath a solitary thin crack etc. This study compares performance of a typical wall designed by different standards. For this purpose, a case study RC shear wall is taken from the Hotel Grand Chancellor in Christchurch which was designed according to the 1982 version of the New Zealand concrete structures standard (NZS3101:1982). The wall is redesigned in this study to comply with the detailing requirements of three standards; ACI-318-11, NZS3101:2006 and Eurocode 8 in such a way that they provide the same flexural and shear capacity. Based on section analysis and pushover analysis, nonlinear responses of the walls are compared in terms of their lateral load capacity and curvature as well as displacement ductilities, and the effect of the code limitations on nonlinear responses of the different walls are evaluated. A parametric study is also carried out to further investigate the effect of confinement length and axial load ratio on the lateral response of shear walls.