• 한국정보과학회논문지:소프트웨어및응용
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• 제34권9호
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• pp.857-868
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• 2007

좋은 분류기 앙상블은 분류기간에 상호 보완성을 갖추어 높은 인식 성능을 보여야 하며, 크기가 작아 계산 효율이 좋아야 한다. 이 논문은 이러한 목적을 달성하기 위한 거친-섬세한 (coarse-to-fine)단계를 밟는 분류기 앙상블 선택 방법을 제안한다. 이 방법이 성공하기 위해서는 초기 분류기 풀 (pool)이 충분히 다양해야 한다. 이 논문에서는 여러 개의 서로 다른 분류 알고리즘과 아주 많은 수의 특징 부분집합을 결합하여 충분히 큰 분류기 풀을 생성한다. 거친 선택 단계에서는 분류기 풀의 크기를 적절하게 줄이는 것이 목적이다. 분류기 군집화 알고리즘을 사용하여 다양성을 최소로 희생하는 조건하에 분류기 풀의 크기를 줄인다. 섬세한 선택에서는 유전 알고리즘을 이용하여 최적의 앙상블을 찾는다. 또한 탐색 성능이 개선된 혼합 유전 알고리즘을 제안한다. 널리 사용되는 필기 숫자 데이타베이스를 이용하여 기존의 단일 단계 방법과 제안한 두 단계 방법의 성능을 비교한 결과 제안한 알고리즘이 우수함을 입증하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.21.2-274
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• 1999

This study aims to examine the influence of the unit powder content of concrete and the fine aggregate ration of high flowing concrete after the improvement of grain shape of the coarse aggregate. According to the experimental results, flowbility and compating of concrete presents the best states in the S/a which has the smallest void ratio. The coarse aggregate after improvement of grain shape has been changed from 0.68 circular ratio of disc shape to 0.73 circular shape. It lead to be down 6% of fine aggregate ratio (from 47% to 41%), which is satisfactory to compacting. Also, the improvement of grain shape of the coarse aggregate lead the lowest unit powder content to be down 60kg/㎥ from (530kg/㎥ to 470kg/㎥). And about 11% unit water content can be reduced as unit powder conent is down.

• 한국의류학회지
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• 제21권8호
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• pp.1315-1322
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• 1997

Ramie is one of the traditional fabrics in Korea, and very comfortable fabric for summer clothes because it has a high moisture-absorbing and transporting property. Futhermore ramie is very popular and Koreans prefer its handle for summer clothes. The kansan ramie has better quality as fibers and can be weaved as fine fabrics which are famous as kansan Fine ramie. Even though the good quality of kansan ramie has known widely, very few research work have been carried out on kansan ramie in the field of textile science. In this study, the analysis of the physical and chemical characteristics of Hansan ramie was conducted by using two different kinds of Hansan ramie: Hansan Fine ramie and kansan Coarse ramie. In addition, the same experiment was held on the one kind of chinese ramie to be compared with those of Hansan ramie. The following results were obtained from this experimental study. By the analysis of chemical composition of ramie, the similar chemical composition (a -cellulose: 83∼85%, pectin substances: 2.81∼ 3.01%) were found from all of the ramie fabrics used in this study. It has shown that Hansan coarse ramie has the highest toughness value and wrinkle recovery angle among the samples used in this study. From the result of KES-F system, it was found that Hansan Coarse ramie which is composed with the thicker yarns has the highest value on the bending properties, 2HG and surface properties. The primary hand value was also calculated by KN-203 LDY and value of Koshi was shown as the order of kansan coarse ramie> Chinese ramie> kansan fine ramie, and Hansan fine ramie had shown the highest Numeri and Fukurami value among the 3 samples used in this study.

• 한국식품과학회지
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• 제28권3호
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• pp.506-513
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• 1996

초미세분쇄한 대두피 분말을 공기분급휠속도 (ACWS, air classifying wheel speed) 10,000 rpm, 12,000 rpm 및 20,000 rpm에서 공기분급하였을 경우 회분, 단백질 및 지방은 조분획으로, 탄수화물은 미분획으로 각각 농축되었다. 식이섬유는 조분획으로 농축되었고, ACWS가 감소함에 따라 그 함량이 증가하였다. 분획별 입자크기는 ACWS가 감소함에 따라 증가하였는데 그 범위는 미분획은 $3.1{\mu}m\;to\;5.5{\mu}m$였고, 조분획은 $9.9{\mu}m\;to\;20.0{\mu}m$였으며, 그 형태는 분획에 관계없이 대부분 모서리가 있는 타원형이었다. 전반적으로 낮은 ACWS에서 높은 점도를 보였고, 보수력, 보유력 및 유화력의 경우 조분획과 미분획에 유의적인 차이가 있으나 ACWS에 따라서는 차이가 없었다. 식품응용실험 결과 대두피 분말을 10, 20, 30% 각각 대체시켜 튀김옷으로 활용하였을 때, 기름 흡수량이 대조구에 비하여 감소하였으며, 케익과 쿠키의 제조에 있어서 밀가루를 대두피 분말로 10% 수준까지 성공적으로 대체할 수 있었다.

• 대한원격탐사학회지
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• 제33권1호
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• pp.25-35
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• 2017

Spatial downscaling with fine resolution auxiliary variables has been widely applied to predict precipitation at fine resolution from coarse resolution satellite-based precipitation products. The spatial downscaling framework is usually based on the decomposition of precipitation values into trend and residual components. The fine resolution auxiliary variables contribute to the estimation of the trend components. The main focus of this study is on quantitative analysis of impacts of trend component estimates on predictive performance in spatial downscaling. Two regression models were considered to estimate the trend components: multiple linear regression (MLR) and geographically weighted regression (GWR). After estimating the trend components using the two models,residual components were predicted at fine resolution grids using area-to-point kriging. Finally, the sum of the trend and residual components were considered as downscaling results. From the downscaling experiments with time-series Tropical Rainfall Measuring Mission (TRMM) 3B43 precipitation data, MLR-based downscaling showed the similar or even better predictive performance, compared with GWR-based downscaling with very high explanatory power. Despite very high explanatory power of GWR, the relationships quantified from TRMM precipitation data with errors and the auxiliary variables at coarse resolution may exaggerate the errors in the trend components at fine resolution. As a result, the errors attached to the trend estimates greatly affected the predictive performance. These results indicate that any regression model with high explanatory power does not always improve predictive performance due to intrinsic errors of the input coarse resolution data. Thus, it is suggested that the explanatory power of trend estimation models alone cannot be always used for the selection of an optimal model in spatial downscaling with fine resolution auxiliary variables.

• 전기전자학회논문지
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• 제23권2호
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• pp.557-570
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• 2019

In this study, a novel hierarchical approach is investigated to extract coronary vessel from X-ray angiogram. First, we propose to combine Decimation-free Directional Filter Bank (DDFB) and Homographic Filtering (HF) in order to enhance X-ray coronary angiographic image for segmentation purposes. Because the blood vessel ensures that blood flows in only one direction on vessel branch, the DDFB filter is suitable to be used to enhance the vessels at different orientations and radius. In the combination with HF filter, our method can simultaneously normalize the brightness across the image and increases contrast. Next, a coarse-to-fine strategy for iterative segmentation based on Otsu algorithm is applied to extract the main coronary vessels in different sizes. Furthermore, we also propose a new approach to segment very small vessels. Specifically, based on information of the main extracted vessels, we introduce a new method to extract junctions on the vascular tree and level of nodes on the tree. Then, the window based segmentation is applied to locate and extract the small vessels. Experimental results on our coronary X-ray angiography dataset demonstrate that the proposed approach can outperform standard method and attain the accuracy of 71.34%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1883-1886
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• 2005

In this paper, a decoupled dual servo (DDS) stage for ultra-precision scanning system with large working range is introduced. In general, dual servo systems consist of a fine stage for short range and a coarse stage for long range. The proposed DDS also consists of a $XY\theta$ fine stage for handling and carrying workpieces and one axis coarse stage. Its coarse stage consists of air bearing guide system and a coreless linear motor with force ripple. The fine has four voice coil motors(VCM) as its actuator. According to a VCM's nature, there are no mechanical connections between coils and magnetic circuits. Moreover, VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about $25mm^2$. To break that hurdle, the coarse stage with linear motors is used to move the fine about 500mm. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. With MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. And for their movements without any frictions, guide systems of the DDS are composed of air bearings. To get precisely their positions, a linear scale with 5nm resolution are used for the coarse stage's motion and three plane mirror laser interferometers with 5nm for the fine's $XY\theta$ motions. With them, on scanning the two stages have same trajectories. The control algorithm is named Parallel method. The embodied ultra-precision scanning system has sub 100nm following error and in-positioning stability.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.79-84
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• 2003

The main objective of this study was to investigate the chemical characteristics of post-harvest biomass burning aerosols from field burning of barley straw in late spring and rice straw in late fall in rural area in Korea. 12-hr integrated intensive sampling of $PM_{10}$ and $PM_{2.5}$ biomass burning aerosols had been conducted continuously at Gwangju, Korea 4-15 June 2001 and 8 October-14 November 2002. The fine and coarse particles of biomass burning aerosols were collected for mass, ionic, elemental, and carbonaceous species analysis. Average fine and coarse mass concentrations of biomass burning aerosols were measured to be 129.6, 24.2 ${{\mu}gm}^{-3}$ in June 2001 and 47.1, 33.2 ${{\mu}gm}^{-3}$ in October to November 2002, respectively. Exceptionally high level of $PM_{2.5}$ concentration up to 157.8 ${{\mu}gm}^{-3}$ well above 24-hour standard was observed during the biomass burning event days under stagnant atmosphere condition. During biomass burning periods dominant ionic species were $Cl^{-}$, ${NO_3}^{-}$, ${SO_4}^{2-}$, and ${NH_4}^{+}$ in fine and coarse mode. In the fine mode $Cl^{-}$ and ${KCl}^{+}$ were unusually rich due to the high content of the semiarid vegetation. High OC values and OC/EC ratios were also measured during the biomass burning periods. Increased amount of fine aerosols with high enrichment, which were originated from biomass burning of post-harvest agricultural waste, resulted in extremely severe particulate air pollution and visibility degradation in the region. Particulate matters from open field burning of agricultural wastes cause great adverse impact on local air quality and regional climate.

• 한국지반공학회논문집
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• 제33권12호
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• pp.7-20
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• 2017

본 연구에서는 전단특성 및 유변학적 정수를 모두 산정할 수 있는 직접전단실험 장비를 이용하여 조립토와 세립토에 대하여 전단강도 및 유변학적 특성에 대한 입도분포의 영향을 조사하고자 하였다. 최대입경 0.075mm의 세립토와 최대입경이 0.425mm이고, 세립분 함량이 17%인 조립토를 건조상태와 액성한계상태로 조성하여, 산사태 분류기준에 따라 재활성 산사태(reactivated landslide) 혹은 붕괴직후 토석류 속도에 해당하는 전단속도에 대하여 전단강도를 산정하였다. 또한, 유변학적 특성 평가를 위해 액성한계상태로 조성된 조립토와 세립토에 대하여 서로 다른 세 가지의 전단변형률속도로 반복적으로 전단하며 잔류전단강도를 측정하였다. 측정된 잔류전단강도와 전단변형률속도와의 관계를 통해 빙햄모델의 소성 점도와 항복응력을 산정하였다. 건조 및 액성한계상태에서 조성된 시료에 대하여 첨두전단강도에서 산정한 점착력의 경우, 세립토에서 조립토보다 더 크게 산정되었으며, 내부마찰각은 조립토에서 더 크게 산정되었다. 유변학 정수의 경우, 소성 점도와 항복응력이 조립토보다 세립토에서 더 큰 것으로 나타났다. 본 연구는 재활성 산사태 혹은 붕괴직후 토석류의 거동예측에 효과적으로 활용될 것으로 기대된다.

• 전자공학회논문지B
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• 제33B권10호
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• pp.80-89
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• 1996

This paper proposes a new COA (center of area) defuzzifier that is working in the accurate and fast manner. The proposed COA defuzzifier involves both membership values and the spans of membership functions in clauclating a crisp value. In additon, it avoid division by replacing the COA calculation with the searching of the momentum equilibrium point. The moment equilibrium point is searched in the coarse-to-fine manner such that the moment computing points during the coarse searching are moved in the interval of fuzzy terms until they are reached at two adjacent fuzzy terms searching method accerlates the finding of the moment equilibrium point by O(M) mazimally when compared iwth the equal interval searching method of ruitz. In order to verify the accuracy of the proposed COA defuzzifier, the crisp values obtained form the proposed coarse-to-fine searching are compared with the precise crisp values from the arithmetic calculation. Application to the truck backer-upper control problem of the proposed COA defuzzifier is presented. The control performance is compared with that of the conventional COA defuzzifier in tems of the average tracing distance.