• 한국방재학회 논문집
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• 제3권4호
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• pp.119-129
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• 2003

콘크리트와 철은 건설에서 필수적인 구조 재료이다. 그러나, 철과 달리 콘크리트는 하나의 재료가 아니라 많은 물질들로 구성된 복합재료이며, 구성 재료, 현장 환경, 그리고 기술자의 숙련도 등에 의해 많은 영향을 받는다. 그리고 유동성과 공기량 등 즉시 알 수 있는 물성도 있지만 강도나 내구성 같이 시간이 지나야 알 수 있는 특성도 존재하므로 콘크리트의 배합은 전문가의 경험에 많이 의존해 왔다. 하지만, 콘크리트도 고성능화 되는 시점에서 첨가 재료도 늘어나고 기존의 자료도 부족하기 때문에 새로운 기법이 필요한 때이다. 신경망은 복잡한 비선형 문제를 처리하는 인간의 두뇌를 모방한 모델로 패턴 인식 및 분류, 예측 등의 분야에서 많이 사용되고 있다 여기서는 그 중에서 역전파 알고리즘과 광선형 기저 함수망 모형이 사용되었다. 여덟가지 재료(물, 시멘트, 잔골재, 굵은 골재, 플라이 애쉬, 실리카 흄, 유동화제, 그리고 공기연행제)가 배합에 사용되었으며, 압축강도와 슬럼프, 공기량을 물성으로 사용하였다. 결과적으로 신경망은 고성능 콘크리트치 배합 및 물성 예측 등 활용에 유용하게 사용될 수 있음을 알 수 있었다.

• 한국멀티미디어학회논문지
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• 제16권12호
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• pp.1454-1464
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• 2013

본 논문에서는 수술 중 촬영된 2D XA(X-ray Angiogram) 영상에 수술 전 촬영된 3D CTA (Computed Tomography Angiography) 영상 정보를 융합 가시화하기 위한 고속의 강체 정합 기법을 제안한다. 본 논문에서는 두 혈관 사이의 특징점 정보를 이용하여 예측 투영 위치 지점을 추정하는 삼각 측정을 통한 추정치 예측 기법을 제안하여 빠르고 견고한 초기 정합이 가능하다. 이에 더하여 주축을 생성하여 정렬시킨 후 경계 상자를 이용하여 혈관의 형태를 비교하는 방법으로 더욱 정확한 초기 정합이 가능하다. 다음으로 정밀정합은 선택적 거리 측정을 통하여 각 영상에서의 혈관들의 거리 차이가 최소인 위치로 영상을 정합한다. 실험으로 5명의 환자 데이터에 대하여 영상정합을 하였고, 기존 기법과 수행 속도와 정확성, 견고성 측면에서 비교 평가하였다. 실험 결과 제안 기법은 기존 기법에 비하여 최적의 위치로 빠르고 견고하게 정합되었다.

• 한국토양비료학회지
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• 제49권2호
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• pp.157-167
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• 2016

The interspecific estimation for tolerance capacities of upland crop species to excessive soil water stress in paddy field is significant in agricultural practices. Most of upland crops can be damaged by either excessive soil water or capillary rise of the water table during rainy season in paddy fields. The major objective of this study was to evaluate water stress of upland crops under different drainage classes in converted paddy field. This experiment was carried out in poorly drained soil (PDS) and imperfectly drained soil (IDS) of alluvial sloping area located at Toero-ri, Bubuk-myeon, Miryang-si, Gyeongsangnam-do. The soil was Gagog series, which was a member of the fine silty, mixed, nonacid, mesic family of Aeric Endoaquepts (Low Humic-Gley soils). Two drainage methods, namely under Open ditch drainage methods (ODM) and, Closed pipe drainage methods (PDM) were installed within 1-m position at the lower edge of the upper paddy fields. The results showed that sum of excess water days ($SWD_{30}$), which was used to represent the moisture stress index, was 42 days (the lowest) in the PDM compared with 110 days in the ODM. Most of upland crops were more susceptible to excessive soil water during panicle initial stage on more PDS than on IDS. Yield of upland crops in the PDM was continuously increased by the rate of 15.1% on sorghum, 15.4% foxtail millet, 53.6% proso millet, 49.6% soybean and 47.9% adzuki bean as compared in the ODM. The capacity for tolerance by excessive soil water based on yield of each upland crop in the poorly drained sloping paddy fields was the order of sorghum, soybean, foxtail millet, proso millet and adzuki bean. Therefore, Sorghum is relatively tolerant to excessive soil water conditions and, may be grown successfully in converted paddy field.

• 한국주조공학회지
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• 제17권2호
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• pp.158-163
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• 1997

Properties of $Al_{86}Ni_6Ce_4Mg_4$ alloy powder produced by helium gas atomization process were investigated by using DSC, XRD, SEM and TEM. The powders below 32 ${\mu}m$ in diameter were identified as an amorphous phase mixed with a ${\alpha}-Al$ phase. $Al_{86}Ni_6Ce_4Mg_4$ bulk alloy was manufactured by hot extruding the alloy powders at various temperatures, and the estimation of its mechanical properties was carried out subsequently. As a result, the bulk alloy extruded at the temperature below $450^{\circ}C$ exhibited the microstructure in which the near-spherical shape of some powders below 20 ${\mu}m$ were nearly unchanged and fine voids between matrix and powders were formed during extrusion process. On the other hand, the tensile strength and elongation at room temperature for $Al_{86}Ni_6Ce_4Mg_4$ bulk alloy extruded at $450^{\circ}C$ were 750 MPa and 7.5%, respectively.

• Journal of the Optical Society of Korea
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• 제20권4호
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• pp.515-523
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• 2016

Spectral reflectance is sparse in space, and while the traditional spectral-reconstruction algorithm does not make full use of this characteristic sparseness, the compressive sensing algorithm can make full use of it. In this paper, on the basis of analyzing compressive sensing based on the orthogonal matching pursuit algorithm, a new algorithm based on the Dice matching criterion is proposed. The Dice similarity coefficient is introduced, to calculate the correlation coefficient of the atoms and the residual error, and is used to select the atoms from a library. The accuracy of Spectral reconstruction based on the pseudo-inverse method, Wiener estimation method, OMP algorithm, and DOMP algorithm is compared by simulation on the MATLAB platform and experimental testing. The result is that spectral-reconstruction accuracy based on the DOMP algorithm is higher than for the other three methods. The root-mean-square error and color difference decreases with an increasing number of principal components. The reconstruction error decreases as the number of iterations increases. Spectral reconstruction based on the DOMP algorithm can improve the accuracy of color-information replication effectively, and high-accuracy color-information reproduction can be realized.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_2호
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• pp.55-63
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• 2001

This work employs two models to quantify the size-segregated dry deposition fluxes of particle-bound N $O_3$$^{[-10]}$ , N $H_4$$^{+}$, and S $O_4$$^{2-}$ along the coastal area of Jeju Island based on the chemical composition data of aerosol collected during the springtime of 1995. The two approaches produced fairly comparable results, despite the feature differences between the two models. The modelling results obtained indicated that the mean dry deposition velocity was around 0.4 cm $s^{-1}$ for N $O_3$$^{[-10]}$ , 0.2 cm $s^{-1}$ for N $H_4$$^{+}$, and 0.3 cm $s^{-1}$ for S $O_4$$^{2-}$, and the dry deposition flux varied between 371~1368 $\mu\textrm{g}$ $m^{-2}$ da $y^{-1}$ for nitrate, 28~625 $\mu\textrm{g}$ $m^{-2}$ da $y^{-1}$ for ammonium, and 957~6088 $\mu\textrm{g}$ $m^{-2}$ da $y^{-1}$ for sulfate. Although difficulties in collecting giant and/or fine particles limited the understanding of the mass size distribution of particles and thus the ability to refine estimates of the dry deposition flux for the particulate matter, both models were still able to offer sufficient realism to explain the features of the available data collected from the coastal area of Jeju Island.and.

• 대한가정학회지
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• 제39권10호
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• pp.97-109
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• 2001

It is thought that a composition of trousers is related to fabrics with single breadth. Therefore, trousers are designed with pattern using this fabrics with single breadth. However, in the old pattern of trousers, the breadth of 33cm-35cm was not considered in designing patterns. In this context, deciding which pattern design is better is not easy as there are a variety of estimation methods. So in this study, standardization of drafting is pursued by an objective pattern design. For this, a base angle of the trouser closely relating to a form and function was measured and using the height and the base angle, a trouser pattern design was tried. For a measurement of the base angle, 5 subject were selected. They are 25-29 year-old male graduates with fine physical standard. The base angle was measured with symphysis pubis point as a standard when subjects sat with their legs crossed, when they stood with their legs open (not forced artificially) and when they laid down with their legs open. The distance between a knee inside joint and knees was measured three times and the resultant value was used for the pattern design. For a design of trousers, the height was applied and the base angle was fixed. As a pattern drawing, using the height, a base angle and circumference of the hip, a trouser was designed. The production method for the pattern design is as follow: (1) The length formula, is height + $\frac{height}{2}$ (2) The hip girth formula is $\frac{hipgirth}{2}$ - $\frac{hipgirth}{20}$(3) A crotch angle is fixed at $72^{\circ}$. (4) The ratio of outer leg length to leg width is 5 : 8. (5) The component ratio of the upper outer leg length to the pant length is 5 : 8. (6) The ratio of the division point of front right inner leg length and left inner width to upper outer leg length is 5 : 8.

• 한국물환경학회지
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• 제33권6호
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• pp.626-639
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• 2017

Based on an ecological monitoring in a Korean stream (Gapyeong), Habitat Suitability Index (HSI) of nine fish species was developed for three physical habitat factors : current velocity, water depth and substrate. The species were chosen based on their abundance and frequency in the fish community of the Gapyeong stream. The Weibull model was used as the probability density function to analyze the distribution and number of each fish species according to the three identified physical factors, which showed good results. This HSI equation has advantages because it statistically expresses habitat preferences of fish species simply and clearly. From that, we can quantitatively deduce the central tendency and variation of environmental factors for fish distribution. The selected fish species showed different preferences for each habitat factor respectively. Although there are some exceptions, the distribution and abundance of individual species of nektonic fish (Zacco koreanus, Zacco platypus, Microphysogobio longidorsalis and Pungtungia herzi) were positively skewed to deep water and fine substrate while riffle-benthic fish (Koreocobitis rotundicaudata and Coreoleuciscus splendidus) were normally distributed at the shallow and coarse substrate zone. It seems that the species showing the positively skewed distribution to the current, Z. koreanus, Z. platypus, M. longidorsalis and P. herzi have adapted themselves to the fast current and have expanded their niche.

• 상하수도학회지
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• 제18권2호
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• pp.201-207
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• 2004

Dissolved air flotation (DAF) is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. Most of particle-bubble collision occurs in the DAF contact zone. This initial contact considered by the researchers to play a important role for DAF performance. It is hard to make up conceptual model through simple mass balance for estimating collision efficiency in the contact zone because coupled behavior of the solid-liquid-gas phase in DAF system is 90 complicate. In this study, 2-phase(gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. For the modeling of turbulent 2-phase flow in the reactor, the standard $k-{\varepsilon}$ mode I(liquid phase) and zero-equation(gas phase) were used in CFD code because it is widely accepted and the coefficients for the model are well established. Particle-bubble collision efficiency was calculated using predicted turbulent energy dissipation rate and gas volume fraction. As the result of this study, the authors concluded that bubble size and recycle ratio play important role for flow pattern change in the reactor. Predicted collision efficiency using CFD showed good agreement with measured removal efficiency in the contact zone. Also, simulation results indicated that collision efficiency at 15% recycle ratio is higher than that of 10% and showed increasing tendency of the collision efficiency according to the decrease of the bubble size.

• 대한전자공학회논문지SP
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• 제42권4호
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• pp.21-30
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• 2005

본 논문에서는 B-snake 차선 모델을 이용한 차선 검출 및 추적에 관한 알고리즘을 제안한다. 제안된 이론의 특성은 첫째, 다른 알고리즘에 비해 직선, 굴곡이 있는 도로와 같은 보다 넓은 범위의 차선 구조의 표현이 가능하며, 또한 평면 도로의 평행 특성을 이용하여 그림자, 잡음 등에 강하고, 둘째, 잡음에 강한 CHEVP(Canny/Hough Estimation Vanish Point) 알고리즘을 사용하여 차선 위치의 초기값을 제공한다. 셋째, GYP(Gradient Vector Flow)와 최소 평균 제곱 에러를 이용하여 B-Snake 차선 모델에서 발생하는 외부의 힘을 줄여 차선 검출의 에러를 줄이고 차선 추적을 효과적으로 수행한다. 측정 실험 결과 도로영상을 날씨 별로 맑은 날, 흐린 날 그리고 비오는 날로 구분하여 본 알고리즘을 수행하였으며 95$\%$ 이상의 차선 검출률을 보였다.