• 한국산학기술학회논문지
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• 제10권7호
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• pp.1473-1479
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• 2009

본 연구는 저비용 고효율의 일체형 곡물 건조/저장 시스템 개발을 위하여 추진되었다. 저장시스템의 용량과 규격, 배출기구의 설치 조건 및 공전, 자전 등의 운전 조건 그리고 대상 곡물의 비중 등의 다양한 조건에서 정해진 배출속도를 충족시키며 곡물의 선입-선출이 보장되는 균일하강 배출기구를 설계하고자 하였다. 곡물 배출 과정에 대한 육안 관찰이 가능한 장치를 제작하여 기존의 균일 단면형 배출기구에서의 곡물의 배출 거동을 관찰하여 기존 기구의 제한점을 검토하였다. 수학적 해석을 통해 주어진 배출 속도를 비롯한 다양한 조건과 곡물의 균일 하강의 조건을 만족시키는 가변 단면형 배출기구의 단면형상을 설계할 수 있는 일반화된 공식을 유도하였으며, 이를 적용하여 제작된 시작품의 운전을 통해 계산값과의 비교 검증의 연구 과정을 수행하였다. 이를 통해 주어진 다양한 조건을 만족하는 나선형의 가변 단면형 균일하강 배출기구의 단면 형상 설계를 위한 일반화된 수학적 모델을 개발하였다.

• Structural Engineering and Mechanics
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• 제84권3호
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• pp.295-310
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• 2022

This paper proposes a modified bar simulation method for analyzing the shear lag effect of variable sectional box girder with multiple cells. This theoretical method formulates the equivalent area of stiffening bars and the allocation proportion of shear flows in webs, and re-derives the governing differential equations of bar simulation method. The feasibility of the proposed method is verified by the model test and finite element (FE) analysis of a simply supported multi-cell box girder with constant depth. Subsequently, parametric analysis is conducted to explore the mechanism of shear lag effect of varied sectional cantilever box girder with multiple cells. Results show that the shear lag behavior of variable box-section cantilever box girder is weaker than that of box girder with constant section. It is recommended to make the gradient of shear flow in the web with respect to span length vary as smoothly as possible for eliminating the shear lag effect of box girder. An effective countermeasure for diminishing shear lag effect is to increase the number of box chambers or change the variation manner of bridge depth. The shear lag effect of varied sectional cantilever box girder will get more server when the length of central flanges is shorter than 0.26 or longer than 0.36 times of total width of top flange, as well as the cantilever length exceeds 0.29 times of total length of box's flange. Therefore, the distance between central webs can adjust the shear lag effect of box girder. Especially, the width ratio of cantilever plate with respect to total length of top flange is proposed to be no more 1/3.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.34-41
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• 1999

This paper is focused on numerical analysis for perforated plate with irregular section based on Kirchhoff's fundamental equations of a circular plate. The dimensions of analysis model are as following; 1) radius:100cm, 2) hole in center:20cm, 3)thickness: l0cm and variable and have a simple support in boundary. The theoretical results are compared with data obtained by the F.2.M analysis. Both data have good agreement with each other.

• Journal of applied mathematics & informatics
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• 제41권5호
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• pp.1071-1084
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• 2023

We consider inviscid, incompressible homogeneous shear flows of variable cross section known as extended Rayleigh problem. For this extended Rayleigh problem, we derived instability region which intersect with semi-circle instability region under some condition. Also we derived condition for stability, upper bound for amplification factor and growth rate of an unstable mode.

• International Journal of Aeronautical and Space Sciences
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• 제14권4호
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• pp.310-323
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• 2013

In this paper, the aeroelastic static response of flexible wings with arbitrary cross-section geometry via a coupled CUF-XFLR5 approach is presented. Refined structural one-dimensional (1D) models, with a variable order of expansion for the displacement field, are developed on the basis of the Carrera Unified Formulation (CUF), taking into account cross-sectional deformability. A three-dimensional (3D) Panel Method is employed for the aerodynamic analysis, providing more accuracy with respect to the Vortex Lattice Method (VLM). A straight wing with an airfoil cross-section is modeled as a clamped beam, by means of the finite element method (FEM). Numerical results present the variation of wing aerodynamic parameters, and the equilibrium aeroelastic response is evaluated in terms of displacements and in-plane cross-section deformation. Aeroelastic coupled analyses are based on an iterative procedure, as well as a linear coupling approach for different free stream velocities. A convergent trend of displacements and aerodynamic coefficients is achieved as the structural model accuracy increases. Comparisons with 3D finite element solutions prove that an accurate description of the in-plane cross-section deformation is provided by the proposed 1D CUF model, through a significant reduction in computational cost.

• Journal of Preventive Medicine and Public Health
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• 제25권3호
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• pp.312-329
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• 1992

The purpose of this study is to estimate cesarean section rate in Korea and analyze the socioeconomic variables and health resources which affect regional variation in the rate. Samples were drawn from the record of vaginal and cesarean section deliveries based upon insurance claim bills which have been submitted to the National Federation of Medical Insurance for the first three months, January through March, 1991. The results are obtained as follows : It was found that. cesarean section rate was increasing rapidly up to 23.1% in 1991. Cesarean section per 10 thousand insured people was 4.8 and the number of cesarean section per 10 thousand insured eligible($15{\sim}49$ years old) female was 7.6. The fee for normal delivery was 109,489 won and that for cesarean section was 390,024 won. The average days of hospitalization in normal delivery was 2.3 days, and those in cesarean section was 7.6 days. On the average cesarean section has a longer of stay as much as by 4.3 days and cost 3.6 times more than normal deliveries. Cesarean section rates vary among medical facilities 19.8% at clinics 37.6% in small-scale hospitals, and 29.1% in general hospitals. The regional variation of cesarean section rates was also fairly prominent. The South Cheju Gun has the highest rate of cesarean section, 56.2%. Meanwhile no cesarean section cases has been reported in Sunchang Gun during the period of this study. The variation is noted among provinces. The rate for Cheju province has been 3.4 times higher than that for Chunnam. The number of cesarean section per 10 thousand insured people vary greatly among regions, too. This study has found that there exists significant regional variations among various geographic units in terms of average length of stay, average cost, number of obsretricians and number of beds. Multiple regression analysis was done to identify factors explaining the regional variance of various cesarean section rates : In the urban areas, no significant explaining variables were noted except the number of beds for the dependent variable of cesarean section cases per 10 thousand insured eligible females. The smaller the number of bed, the more cases of cesarean section was noted for an urban area. The is mostly because the rate of cesarean section is higher in medium-size hospitals than in large general hospitals. In the rural areas, the factor of education has been found significant for all three deplendent variables. The higher the educational level, the rate of cesarean section is most likely to rise. An income variable measured by the amount of monthly insurance contribution has been identified a powerful predictor in explaining the valiance of cesarean section rates. The same has been noted for the number of obstetricians. Similar findings are observed for the country as a whole. The income level has veen found as the most powerful explaining factor in the regional variance of cesarean section rates. In general the rate is higher in the urban areas, and lower in the area with more small hospitals. As this is the initial attempt to identify the factors relevant to the regional difference in the rates of cesarean section, more elaborated study is urgently required.

• 한국도로학회논문집
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• 제17권5호
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• pp.115-122
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• 2015

PURPOSES: Recently, many local governments have applied chicanes for traffic calming to ensure environment-friendly comfortable and safe roads. However, the geometry of a chicane is designed for speed reduction using a curved portion. This study aims to improve the road geometry conditions of chicanes for reducing carbon emissions and maintaining appropriate driving speeds by considering the relationship between road geometry and carbon emissions. METHODS: This study was conducted as follows. First, carbon emissions corresponding to changing acceleration of vehicles were studied. Second, vehicle acceleration caused by the relationship between the curve radius and the straight length was studied. Accordingly, desirable conditions of curve radius and length of the straight section for reducing carbon emissions were proposed. RESULTS: The existing literature on chicanes present the minimum value of stagger length and path angle in the primary variable condition. This study suggests the maximum values of the curve radius and length of straight section in the primary variable condition. Therefore, if a vehicle's speed at a chicane is 30 km/h, this study suggests a curve radius of up to 24 m. In addition, if the vehicle's speed is 24 km/h, this study suggests a length of straight section of up to 6.6 m. These are the geometric conditions for considering the control of acceleration to the vehicle's maximum speed. CONCLUSIONS: This paper proposes an application of geometric conditions to reduce carbon emissions and maintain appropriate speeds of vehicles through a combination of curve radius and length of straight section.

• 한국음향학회지
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• 제19권3호
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• pp.51-56
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• 2000

본 논문은 음성인식을 이용한 실시간 윈도우 자동 제어 시스템에 관한 연구이다. 사용된 음성 모델은 수행 속도를 높이기 위해 제안된 가변 DMS 모델을 이용하였으며, 인식 알고리즘으로 이를 이용한 One-Stage DP 알고리즘을 사용한다. 인식 대상단어는 윈도우에서 자주 사용되는 66개의 윈도우 제어 명령어들로 구성한다. 본 연구에서 온라인으로 음성을 처리하기 위해 음성 검출 알고리즘을 구현하였으며, 기존 DMS(Dynamic Multi Section)모델 생성시 고정적으로 적용하던 섹션의 수를 입력 신호의 지속 시간을 고려하여 가변적으로 적용한 가변 DMS 모델을 제안하였다. 또한 윈도우에서 사용자 작업에 의해 현재 상태에 인식 대상으로 불필요한 인식 대상단어가 발생하게 되는데 이를 효율적으로 처리하기 위해 사용 모델을 재구성하여 사용하도록 제안하였으며, 인간의 청각적 특성을 고려하여 음성신호에서 개인의 특성은 제외하고 음성 자체의 특징만을 추출하여 특징 벡터를 생성하는 인지 선형 예측(Perceptual Linear Predictive)분석 방법을 이용하였다. 시스템 성능 평가 결과 가변 동적 다중 섹션 모델(Variable DMS model)과 기존의 DMS 모델은 인식률 면에서는 거의 동일하지만 인식 수행 속도는 제안된 모델의 계산량이 기존 모델보다 작기 때문에 향상되었고, 다중 화자 독립 인식률은 99.08%, 다중 화자 종속 인식률은 99.39%의 인식률을 나타내었으며, 실제 노이즈가 있는 환경에서 화자독립실험의 경우 96.25%의 인식률을 보여 주었다.

• 한국자동차공학회논문집
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• 제22권2호
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• pp.190-196
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• 2014

Exhaust system by reinforcement of environment regulation came to the foe study necessity. And Exhaust system has necessary to increase the engine performance and silence. From this cause, Automobile has significantly considered production expense. this study makes process for checking the characteristics about Exhaust variable valve within muffler. Variable valve might reduce the baffle within muffler, It was possible to remove the front muffler. Therefor, To miniaturize a size of muffler might be increased by performance through cost-cutting effect and controling of back pressure. Because the Study on Variable valve installed within muffler, to measure the real data was hardly resulted one of the assignments. From manufactured conduct device, might measure data one of piece which was up-graded of problem. Considering to these point, stressed pressure distribution has analyzed on cross section, floating characteristics about velocity distribution around variable valve using analysis as computational fluid dynamics of Ansys with completed measurement data.

• International Journal of Industrial Entomology and Biomaterials
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• 제43권2호
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• pp.37-44
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• 2021

Mulberry silkworm is classified into uni, bi and multivoltine based on the frequency of diapause incidence. The variation in the incidence of diapause in bivoltine silkworm provides a unique opportunity to study the process of evolution of adaptive plasticity towards seasonal variations. The diapause expression in bivoltine silkworm is highly variable and is determined by environmental factors experienced by the maternal generation. Diapause in natural populations is functionally associated with the overwintering mechanism that facilitates survival in harsh winter conditions. In contrast, under standard commercial rearing conditions, the domesticated bivoltine silkworm is known to enter diapause in every generation. This paper presents a short review of the literature dealing with the role of temperature, photoperiod, diapause hormone and its receptor in diapause induction. Also, we briefly review the incidence of non-diapause eggs in bivoltine silkworm under controlled conditions.