• 한국화재소방학회논문지
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• 제30권2호
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• pp.62-67
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• 2016

본 연구에서는 워터 커튼용 노즐(Water curtian nozzle)의 액적 크기 분포(droplet size distribution)에 따라서 복사열을 감쇄하기 위한 광학 두께(optical depth)를 분석하였다. 액적 크기 분포를 측정하기 위해서 HELOS/VARIO 물 입자 측정 장치를 사용하였으며, Deirmenjian의 수정된 감마 분포 함수(modified gamma distribution function)를 적용하여 분사 특성을 정량화 하였다. 본 연구에서 사용한 워터 커튼용 노즐은 분포 상수(distribution constant) ${\alpha}=1$, ${\gamma}=5.2$의 값으로 나타났으며, 액적의 밀도 수(number density)를 고려한 분포 하중(droplet loading)과 액적 크기 분포 변화에 따라서 광학 두께에 관한 일반화된 관계식을 제시하였다. 본 연구 결과는 워터 커튼용 노즐의 설계 조건을 분석하기 위한 유용한 연구 자료가 될 것으로 사료된다.

• 생명과학회지
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• 제7권4호
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• pp.355-357
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• 1997

대립종자와 소립종자의 cross부터 F$_{2}$와 F$_{3}$ 세대에서의 종자크기에 대한 빈도분포의 다음과 같다. 두 세대에서 모본의 크기와 같은 progeny는 나타나지 않았으며 각 세대의 평균치는 양 모본의 평균치 보다 낮았다. 소립종자 크기에 비해 우성적인 유전양상을 나타 내었다.

• 한국지반공학회논문집
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• 제21권7호
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• pp.13-20
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• 2005

본 연구에서는 입도분포가 액상화 저항강도 및 동적물성치에 미치는 영향을 실험적으로 검증하였다. 우리나라 준설매립토의 입도분포 조사를 통해 준설매립토의 보편적인 평균입경 4가지와 균등계수 3가지를 선정하였고 평균입경과 균등계수를 각각 달리한 총 12종류의 대표적 준설매립토의 입도분포를 선정, 시료를 제작하였다. 제작된 시료를 이용하여 진동삼축시험을 수행하여 평균입경과 균등계수가 액상화 저항강도에 미치는 영향을 분석하였다. 또한 공진주시험을 수행하여 입도분포가 동적물성치에 미치는 영향도 분석하였다.

• 한국의류산업학회지
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• 제24권5호
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• pp.618-627
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• 2022

This is a basic study to recommend a legging sizing system suitable for middle-aged women. This study aims to explore and analyze the sizing system of branded leggings for middle-aged women. Therefore, 40 pairs of leggings from 20 brands preferred by middle-aged women were first selected to compare their sizing systems. Thus, it was found that the size distribution of legging brands varied significantly, and the number of sizes or the size deviation also varied depending on the brands or products. Second, the adult female age groups were classified as 18-24 years, 25-34 years, 35-44 years, and 45-59 years. Additionally, the distribution of the waist and hip circumferences by age group was compared with the size specifications of the leggings. Leggings with large differences between size specifications and body size distribution were identified in each age group. In the case of women aged 45 to 59, the size distribution suitability of branded leggings was found to be the lowest among the four age groups. Furthermore, it was also found that it is important to reflect the body size distribution, especially the waist circumference, to establish a legging sizing system suitable for women aged 45 to 59 years.

• 한국해양학회지
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• 제28권2호
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• pp.114-120
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• 1993

입도분포의 특징분석에 종래의 조직특성치 대신 수치해석적인 분해법의 적용을 시 도하였다. 그 결과 이 방법이 제주해협의 대륙붕 표층퇴적물과 같은 복모드형 입 도분포의 분석에 매우 유용함이 입증 되었다. 복모드형 입도분포 퇴적물은 제주해협 대륙붕에서는 86%의 높은 비율을 점한다. 종래의 입도특성치(평균, 표준편차, 왜도, 첨도)는 복모드형 입도분포에 대해서는 왜곡된 값을 보인다. 따라서 입도분포의 모드 에 대체로 대응되는 정규성분으로 분해해서 각 정규성분의 특성치를 해석함으로써 입 도특성치에서와 같은 특징의 누락이나 왜곡을 피할 수 있다. 제주해협 대륙붕의 167개 퇴적물 입도분포곡선을 비선형 최소자승법을 사용하여 정규성분으로 분해해서 총 387 개의 정규성분을 얻었다. 정규성분의 평균은 1-3 phi 8-9 phi에 집중되는 것이 많다. 이중 조립질 정규성분의 평균치는 복잡하고 특징적인 지리적 분포를 보인다. 이러한 분포는 퇴적물 총층후 분포와 매우 유사하며 해저면의 지질과 지형을 면밀하게 반영하 고 있다. 해저면을 형성하는 퇴적층은 플라이스토세 후기의 해침성 모래층이며 해저지 형은 플라이스토세말 빙하기 저해수면시기의 침식에 의해 형성된 것으로 보인다.

• 대한기계학회논문집B
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• 제21권3호
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• pp.380-391
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• 1997

A numerical study has been done on the evolution of particle size distribution in particle laden high temperature jet flows undergoing convection, diffusion, thermophoresis and coagulation. The dynamic behavior of these particles have been modelled by approximating the particle size distribution by a lognormal function throughout the process and the moments of the particle size distribution have been used to solve the general dynamic equation. The size distributions of spherical particles in the radial and axial direction have been obtained including the effect of buoyancy. Of particular interests are the variations of geometric mean diameter, number concentration and polydispersity. Results show that buoyancy significantly alters the size distribution in both axial and radial direction. One dimensional analysis for non-spherical particles has also been done and the results have been compared with the existing experimental data.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.554-554
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• 2012

Controlling the size distribution of gold nanoparticles (NPs) is of great importance due to the fact that their properties are strongly dependent upon the size distribution as well as the size itself. In the citrate reduction method for gold NP synthesis, the citrate works as (1) a reducing agent, (2) a surfactant, and also (3) a weak base: it raises the pH of the whole reaction mixture. Here, we have extensively studied the all three roles of the citrate, by adding other reagents separately (NaBH4, CTAB, and NaOH) for the independent control of the three roles of the citrate. Among the roles of the citrate, that as a weak base was found to be the most critical parameter affecting the size distribution of gold NPs and the size distribution became much more improved with the increase of the solution pH, while adding a supplementary surfactant or reducing agent resulted in the formation of less homogeneous NPs.

• 한국대기환경학회지
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• 제27권6호
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• pp.681-691
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• 2011

The size distributions of smoke particles from fire are prerequisite for the studies on fire detection and adverse health effects. Above the flame of the fire, coagulation dominates and the smoke particles grow from 1 to 50 nm up to 100 to 3,000 nm, sizes ranging from the free-molecular regime to the continuum regime. The characteristics of the agglomeration of the smoke particles are well known, independently for each of the free-molecular and continuum regimes. However, there are not many systematic studies in the entire regime by the complexity of the mechanisms. The purpose of this work is to find the characteristics of the development of the size distribution of smoke particles by agglomeration in the entire size range covering the free-molecular regime, via transition regime, to the near-continuum and continuum regime for each variation of parameters such as fractal dimension, primary particle size and dimensionless coagulation time. In this work, the dynamic equation for the discrete-size spectrum of the particles was solved using a nodal method based on the modification of a sectional method. In the calculation, the collision frequency function for the entire regime, which is derived by using the concept of collision volume and general enhancement function, was applied. The self-preserving size distribution for the entire regime is compared with the ones for the free-molecular or continuum regimes for each variation of the parameters.

• 대한기계학회논문집
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• 제11권3호
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• pp.479-487
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• 1987

본 연구에서는 액적들의 분포상태가 집단연소의 특성에 미치는 영향을 규명하 기 위하여 김의 비정상 집단연소모델에 비균일 액적크기분포와 수밀도분포를 고려한 비균일분포 집단연소모델을 구성하여 이론적으로 해석하였다.

• 한국의류산업학회지
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• 제26권1호
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• pp.44-54
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• 2024

In this study, the sizing systems of 40 unisex sweatshirt brands were analyzed to collect the size information needed to produce unisex clothing. Each size specification was compared with the body size distribution and percentiles of men and women aged 18 to 29. Depending on the brand, unisex sweatshirt sizes ranged from 1 to 8. Despite being unisex apparel, three brands offered only one or two sizes. Out of the brands surveyed, 50% were found to offer four or five sizes. Out of the 40 brands, 25 used letters such as "S," "M," and "L" to indicate the size designation. More than 92.5% of the brands included M and L, and the sizing system tended to focus on larger sizes such as XL and 2XL rather than smaller sizes such as XS and S. The size specifications of shoulder width, chest circumference, sleeve length, and total length were compared with the body size distribution and percentiles of men and women aged 18 to 29. The distribution of each size specification mostly appeared in a section larger than the men's body size. The size specifications of unisex sweatshirts were set close to or larger than men's sizes and hardly represented women's sizes. To increase consumer satisfaction with unisex clothing, establishing a size standard that could accurately reflect the body size distribution of men and women was found to be imperative. Such a size standard could also help each brand specify or diversify its target and differentiate itself with other brands.