• 한국통신학회논문지
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• 제15권5호
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• pp.364-373
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• 1990

디지틀 필터를 전용 하드웨어나 범용 계산기에 의해서 實現할 때 有限 語長 實現에 기인해서 量子化 誤差(演算, 誤差, 係數 量子化 誤差)가 필연적으로 발생하며, 또한 이러한 量子化 誤差의 最小化를 위한 等價 變換 行列이 연구되었다. 본 논문에서는 演算 誤差 最小 實現과 係數 量子化 誤差 最小 實現과의 상호 등가 변환할 수 있는 等價 變換行列을 유도하고 유도된 等價 變換 行列의 유효성을 나타내기 위해서 演算 誤差 最小型 2차 디지틀 필터로부터 係數 量子化 誤差 最小型 2차 디지틀 필터를 설계하고 시뮬레이션하였다.

• 한국표면공학회지
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• 제29권6호
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• pp.788-796
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• 1996

$TiO_2$ films prepared by RF magnetron sputtering, electron beam evaporation, ion assisted deposition (IAD) and sol-gel method are prepared on c-Si substrate and vitreous silica substrate respectively. From the transmission spectra of $TiO_2$ films on vitreous silica substrate in the spectral region from 190 nm to 900 nm, k($\lambda$) of $TiO_2$ is obtained. Using k($\lambda$) in the interband transition region the coefficients of the quantum mechanical dispersion relation of an amorphous $TiO_2$ and hence n($\lambda$) including the optically opaque region of above fundamental transition energy are obtained. The spectroscopic ellipsometry spectra of $TiO_2$ films in the spectral region of 1.5-5.0eV are model analyzed to get the film packing density variation versus i) substrate material, ii) film thickness and iii) film growth technique. The complex refractive index change of these $TiO_2$ films versus water condensation is also studied. Film micro-structures by SE modelling results are compared with those by atomic force microscopy images and X-ray diffraction data.

• The Plant Pathology Journal
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• 제20권2호
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• pp.85-91
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• 2004

A disease causing severe leaf spots in pepper plants has been observed in northern Gyeongbuk and Gangwon provinces in Korea since 1994. The current study diagnosed the disease as gray leaf spot caused by Stemphylium solani Weber and S. lycopersici (Enjoji) Yamamoto, both of which are pathogenic in pepper and tomato plants. Although the disease has been found in almost all areas where peppers are grown, it is more severe in mountain terrains where the nights are cool. Both species of pathogenic fungi were found to sporu-late profusely on V-8 juice agar in plastic or Pyrex glass Petri dishes, although not in domestically-produced glass Petri dishes, when cultured at $20^{\circ}C$ under irradi-ation from a daylight fluorescent lamp with a 12-hour light and dark alternation. The domestically-produced glass Petri dishes, which are made of window glass, were found to block near ultraviolet wavelengths, around and below 300 nm, which explained why the fungi did not sporulate. However, sporulation decreased at above $25^{\circ}C$ and most isolates failed to sporulate above $27^{\circ}C$. The worst level of disease was obtained when the inoculated plants were incubated with a $15^{\circ}C$ night and $20^{\circ}C$ day temperature regime relative to 4 night/day temperature combinations (15/20, 20/25, 25/30, and 30/35$^{\circ}C$).

• 소성∙가공
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• 제8권5호
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• pp.471-481
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• 1999

The properties of deformed products are generally dependent upon the distribution of microstureture. It is, therefore, necessary to make the distribution of microstureture uniform in order to achieve the best balance of properties in the final product. This is often a demanding task, even for conventional materials. It is become essential to achieving mechanical integrity and a desired combination of microstructure and properties. The objective mechanical integrity and a desired combination of microsttucture and properties. The objective of this study is to design the optimal die profile which can yield more uniform microstructure in hot extruded product. The microstructure evolution, such as dynamic and static recrystallization as well as grain growth, is investigated using the program com-bined with yada and Senuma's empirical equations and rigid-thermoviscoplastic finite element method. The die profile of hot extrusion is represented by Bezier-curve to define all available profile. In order to obtain the optimal die profile which yields uniform microstructure in the product the FPS(Flexible Polyhedron Search) method is applied to the present study. To validate the result of present study the experimental hot extrusion is performed and the result is compared with that of simulation.

• Parasites, Hosts and Diseases
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• 제33권1호
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• pp.65-68
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• 1995

1992년 2월과 7월에 멕시코 티후아나에서 중남미와 멕시코에서 온 이민촌 거주자들의 대변검사를 포르말린 에틸아세테이트 집란법으로 일회 검사하였다. 모두 92명의 피검자중 충란 또는 포낭 양성율은 53.3%. 누적 양성율은 71 7%이었고. 대장아메바(19.3%), 람블편모충(9.8%). 이질아 메바(7.6%)와 유무구조충(6.5%)이 가장 흔히 발견되는 장내 기생충이었다 이 지역에는 오염되지 않은 식수 공급과 적절한 치료가 필요하다.

• 한국분말재료학회지
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• 제13권2호
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• pp.112-118
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• 2006

[ $R_{1/3}Sr_{2/3}FeO_{3}$ ](R=Pr, Nd, and Sm) was synthesized and their magnetic properties and charge ordering(CO) transition related with lattice dynamics and oxygen vacancy were systematically investigated. The charge disproportion ation(CD) in $R_{1/3}Sr_{2/3}FeO_{3}$(R=Pr,Nd) was in which two kins of iron with valence state $Fe^{3+}$ and $Fe^{5+}$ were found with ratio of 2:1. In this charge ordering state a sequence of $Fe^{3+}Fe^{3+}Fe^{5+}Fe^{3+}Fe^{3+}Fe^{5+}$ exists aligned along the [111] direction of the pseudocubic perovskite structure. The charge ordering exist in distorted structure involving $t_{pd}$ hybridization. The disordering phases coexist in distorted structure as temprature in creases that is controlled amount of oxygen vacancy. The magnetic hyperfine fields indicate charge tranfering temperature as it dissapeared drastically.

• 대한의용생체공학회:의공학회지
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• 제21권2호
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• pp.181-187
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• 2000

동맥의 일부분이 팽창하는 동맥류는 파열로 인한 높은 사망률을 야기한다. 동맥류의 발생 및 파열에는 혈관벽의 구조적 약화와 혈류에 의한 응력이 중요한 역할을 하며, 혈류에 의해 혈관벽에 가해지는 전단응력은 간접적으로 혈관벽 구조를 변화시키고, 직접적으로 혈관벽에 응력을 가하므로 동맥류 파열에 영향을 미치는 중요한 혈류역학적 인자이다. 동맥류가 자주 발생하는 복부대동맥류 모델을 제작하여 정상류와 맥동류 유동에서 광색성 염료를 이용한 유동가시화 방법으로 벽 전단변형률을 측정하였다. 벽전단변형률은 동맥류 내부에서 감소하여 음의 값을 가지며, 동맥류 최대확장부 후부에서 다시 증가하여 확장부가 끝나는 위치에서 동맥 벽에 비해 약 1.5배 정도의 큰 전단변형률 값을 가졌다. 동맥류 최대확장부 후부에서는 벽전단변형률의 방향의 바뀌며, 위치에 따른 전단변형률의 변화가 크게 나타났다. 맥동류 유동에서는 동맥류의 위치에 따라 시간에 따른 벽전단형률 파형이 측정되었다. 동맥류 내부에서는 전단변형률의 크기가 작고 그 방향이 시간에 따라 변화가 심하였으므로 혈관벽의 구조변화가 발생하기 쉬운 지역으로 지목된다. 동맥류 최대 확장부 후부는 위치 및 시간에 따른 전단변형률의 변화가 심하며, 혈관벽 응력이 최대값을 갖는 지역이므로 동맥류의 파열이 발생하기 쉬운 지역으로 예측된다.

• 한국시뮬레이션학회논문지
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• 제15권4호
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• pp.1-10
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• 2006

컴퓨터 바이러스의 모델링 및 시뮬레이션에 관한 연구는 주로 네트워크 취약성 분석에 초점이 맞추어져 있었다. 그러나 컴퓨터 바이러스는 생물학적인 관점에서 분석되어 질 수 있다고 생각하여, 인공생명 기술을 이용하여 컴퓨터 바이러스를 분석하였다. 이 연구를 통해 컴퓨터 바이러스로 인해 네트워크에 미칠 영향과 행동 메커니즘을 이해할 수 있을 것이다. 본 논문에서는 인공생명을 이용한 컴퓨터 바이러스의 모델링 및 시뮬레이션 방법론을 제안한다. 이를 통해 컴퓨터 바이러스 백신의 연구에도 영향을 줄 수 있다.

• Nuclear Engineering and Technology
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• 제52권11호
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• pp.2431-2441
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• 2020

Currently, the pin-by-pin homogenized solvers are a very active research field as they can, unlike the nodal codes, directly predict the local power, while requiring significantly less computational resources than the heterogeneous transport codes. This paper presents a recently developed pin-by-pin diffusion/SP3 solver Tortin, its spatial discretization method and the reflector treatment. Regarding the spatial discretization, it was observed that the finite difference method applied on pin-cell size mesh does not properly capture the big flux change between MOX and uranium fuel, while the nodal expansion method is more accurate but too slow. If the finite difference method is used with a finer mesh in the outer two pin rows of the fuel assembly, it increases the required computation time by only 50%, but decreases the pin power errors below 1% with respect to lattice code reference solutions. The paper further describes the coupling of Tortin with a microscopic depletion solver. Several verification tests show that the SP3 pin-by-pin solver can reproduce the heterogeneous transport solvers results with very good accuracy, even for fuel cycle depletion of very heterogeneous core employing MOX fuel or inserted control rods, while being two orders of magnitude faster.

• 한국임상수의학회지
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• 제17권2호
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• pp.316-320
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• 2000

The present study conducted to evaluate the isolation frequency of Salmonella sap., Escherichia O157:H7 and Listeria monocytogenes in fecal samples collected form 33 dairy cow feedlots in West Gyeong-nam province from tan. 179\ulcorner to Feb. 1999. Salmonella spp. were isolated from 8.7% of fecal samples and 57.5% of dairy cow feedlots participaiting in this study had at least one positive fecal 7ample. The isolation rates of Salmonella spp. in each herd size were 42.9% in ln less than 125 heads, 63.6% in 25% to 50 heads and 75% in more than 50 heads. Of the positive sample, the most common serogroup recovered was Bl(31.5%), followed by C1 and D(22.9%), C2(16.2%), A(4.2%) and E(2.1%), in order. However, E. coli O157:H7 and Listeria monocytogenes were net detected in the fecal samples collected from all feedlots.