• 한국수자원학회논문집
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• 제46권4호
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• pp.361-372
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• 2013

본 연구에서는 1961~2010년 사이의 서울 지점 연 최대치 독립 호우사상들을 베타분포로 분석하여 서울지점의 대표 호우사상을 결정하였다. 구체적으로 살펴보면, 먼저, 첨두강우량을 기준으로 연최대치 호우사상들을 상위 50%와 하위 50%로 구분한다. 각각의 경우에 대해 첨두강우량의 평균을 지나는 베타분포를 유도한다. 마지막으로, 유도된 두 베타분포의 산술평균을 우량주상도로 나타내어 대표 호우사상을 결정한다. 이렇게 유도된 대표 호우사상은 실제 호우사상과 유사한 모양을 갖는 것으로 확인되었으며, 특히 Huff 분포에 비해 큰 첨두 강우량을 갖는 것으로 확인되었다. 여러 강우시간분포 모형들과 비교해 본 결과 Keifer & Chu 모형이 본 연구의 결과와 가장 유사한 것으로 나타났다.

• 한국축산식품학회지
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• 제28권4호
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• pp.431-436
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• 2008

The impact of storage on the neuroprotective effects against $A\beta$-induced cell death and physicochemical characteristics of milk fortified with BF-7 were investigated. The BF-7 milk exerted protection of neuronal cells SK-N-SH from amyloid beta ($A\beta$)-induced neuronal stress. Our results showed that incubation of the cell with pretreated BF-7 milk, significantly attenuated apoptotic stress by $A\beta$, considered in cell morphology and nucleus shape. The general compositions were maintained consistently in BF-7 fortified milk (BF-7 milk). The BF-7 did not make any disturbance on pH and titratable acidity. The color change was not detected, either. Also, any microorganism had not been detected with more than 7 days storage at $4^{\circ}C$. In sensory evaluation study. the average scores of each sensory attribute were quite similar with plain milk. In conclusion, our results strongly indicate that BF-7 characteristics are quite adequate to be included in milk and BF-7 milk is still working well on neuro-protection, result in enforcing our brain and delaying neurodegeneration.

• 한국농공학회지
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• 제21권4호
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• pp.108-117
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• 1979

In order to obtain the basic data for design of water structures which can be contributed to the planning of water use. Best fitted distribution function and the equations for the probable minimum flow were derived to the annual minimum flow of five subwatersheds along Geum River basin. The result were analyzed and summarized as follows. 1. Type III extremal distribution was considered as a best fit one among some other distributions such as exponential and two parameter lognormal distribution by $x^2$-goodness of fit test. 2. The minimum flow are analyzed by Type III extremal distribution which contains a shape parameter $\lambda$, a location parameter ${\beta}$ and a minimum drought $\gamma$. If a minimum drought $\gamma=0$, equations for the probable minimum flow, $D_T$, were derived as $D_T={\beta}e^{\lambda}1^{y'}$, with two parameters and as $D_T=\gamma+(\^{\beta}-\gamma)e^{{\lambda}y'}$ with three parameters in case of a minimum drought ${\gamma}>0$ respectively. 3. Probable minimum flow following the return periods for each stations were also obtained by above mentioned equations. Frequency curves for each station are drawn in the text. 4. Mathematical equation with three parameters is more suitable one than that of two parameters if much difference exist between the maximum and the minimum value among observed data.

• 대한기계학회논문집B
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• 제35권3호
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• pp.263-268
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• 2011

본 연구는 볼텍스 형태를 대신하는 원심형태의 비 막힘형 2엽 수중 슬러리 펌프 임펠러를 개발하기 위해 수행하였다. 이를 위해 먼저 펌프 설계에 있어 중요한 변수로 입구면 날개각(blade angle)과 날개 길이 각(blade length angle) $\alpha$를 선정하여 이들이 펌프의 효율에 미치는 영향을 살펴보기 위해 상용 코드인 ANSYS CFX and BladeGen을 사용하여 해석을 수행하였다. 그 결과 입구면 임펠러 날개 형상은 $\beta$값이 $30^{\circ}$ 로 일정한 값을 가질 때 가장 높은 효율을 가지게 됨을 알 수 있었으며, $\alpha$값은 효율에 비례하는 특징을 가짐을 관찰할 수 있었다.

• 제어로봇시스템학회논문지
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• 제20권8호
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• pp.854-867
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• 2014

This paper deals with the performance comparison of a PSO algorithm inspired in the process of simulating the behavior pattern of the organisms. The PSO algorithm finds the optimal solution (fitness value) of the objective function based on a stochastic process. Generally, the stochastic process, a random function, is used with the expression related to the velocity included in the PSO algorithm. In this case, the random function of the normal distribution (Gaussian) or uniform distribution are mainly used as the random function in a PSO algorithm. However, in this paper, because the probability distribution which is various with 2 shape parameters can be expressed, the performance comparison of a PSO algorithm using the beta probability distribution function, that is a random function which has a high degree of freedom, is introduced. For performance comparison, 3 functions (Rastrigin, Rosenbrock, Schwefel) were selected among the benchmark Set. And the convergence property was compared and analyzed using PSO-FIW to find the optimal solution.

• The Korean Journal of Ceramics
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• 제5권2호
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• pp.162-164
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• 1999

Microsotructure designed porous ceramics of calcium hydroxyapatite $(Ca_{10}(PO_4)_6(OH)_2)$ were prepared by hydrothermal method. The particle size, shape, and the micro-pore size of the porous hydroxyapatite ceramics could becontrolled. The hydroxyapatite was non-stoichiometric apatite with calcium deficient compositions (Ca/P ratio < 1.67). The composition of non-stoichiometric hydroxyapatite ceramics could be controlled from 1.50 to 1.63 in Ca/P ratio. The hydroxyapatite ceramics preparedc at $105^{\circ}C$ under the saturated vapor pressure for 20h were composed of rod-shaped crystals with about 10$\mu\textrm{m}$ in length with the mean aspect ratio of 40. The porous ceramics of calcium deficient hydroxyapatite had about 45% porosity with the inter-connecting pore structure. Porous hydroxyapatite ceramics prepared hydrothermally had the compressive strength of about 10 to 30 MPa. In addition, porous ceramics of $\beta$-tricalcium phosphate ($\beta-Ca_3(PO_4)_2$) were prepared from the calcium deficient hydroxyapatite.

• 한국전산유체공학회지
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• 제16권2호
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• pp.56-61
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• 2011

Numerical study is conducted to design the high temperature heat exchanger of Stirling engine by using the commercial CFD solver, FLUENT. The Fin-tube type of heat exchanger is designed as a reference model by considering the type of engine which is ${\beta}$-configuration. To find the optimal design of heat exchanger in heat transfer capacity numerical calculation is conducted by changing the shape, the number, and material of reference model in three-dimensional combustion field. Adjusted one-way constant velocity of working fluid that is helium is considered as the representative velocity of oscillating flow. The optimal design of heat exchanger considering the heat transfer capability is suggested by using the calculation results.

• 설비공학논문집
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• 제14권3호
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• pp.199-205
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• 2002

In this paper, the optimum shape and arrangement of ribs in the channel of a plate heat exchanger are studied. The following dimensionless geometric parameters of ribs are selected as design variables: rib height ($H_R$), angle of attack ($\beta$), rib pitch ($P_R$), rib distance (L) and aspect ratio of rib (AR). The optimization is performed by minimizing the objective function consisting of the Nusselt number and the friction factor. The optimal values of design variables are as follows: $H_R$=0.263, $\beta$=0.290, $P_R$=3.142, L: 3.954, AR=0.342. The pressure drop and the heat transfer of the optimum model, compared to those of the reference model, are increased by 15.1% and 41.6%, respectively.

• 한국분말재료학회지
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• 제5권1호
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• pp.22-27
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• 1998

The effect of the $\alpha$/$\beta$ phase fraction on the mechanical properties in silicon nitrides was investigated in part 1. In part II, we describe the role of microstructure on the mechanical properties and contact damage of silicon nitrides with coarse/equiaxed and coarse/elongated microstructures. Grain sizes and shapes were controlled by starting powder. Hertzian indentation using spherical indenter was also used to investigate contact damage behavior. Cone cracks from the spherical indentation were suppressed when the silicon nitride contains coarse and elongated grains. Coarse and elongated grains played an important role of cone crack suppression. The size of quasi-plastic zone does not depend on grain size or shape but depends on the fraction of $\alpha$/$\beta$ phase. A quasi-plastic zone was consisting of microcracks by shear stress during indentation.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.207-216
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• 2003

By using the electrochemical method, the relation between the deformation and the geometrical shape, and the effect of cold work on hydrogen absorption-desorption cycling in palladium were investigated, In order to study this problem, four kinds of the Pd specimens used were plates and bars as cold worked and annealed states. As results, it is found that the deformation of thickness direction in the palladium plates increased whereas other lateral directions decreased. But the palladium bars showed the same deformation ratio in all directions because of uniform distribution of the $\beta$ phase. Grains in the plate specimens were greatly deformed after hydrogenation cycling whereas grains in the bar specimens were pulverized. Also, deterioration of the hydrogen absorption rate of the bar specimen was larger than the plate specimen. And the effect of cold work on hydrogen absorption capacity was relatively small.