• Water for future
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• v.15 no.2
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• pp.33-39
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• 1982

For the determination of a reservoir capacity Rippl's mass-curve method has long been used with the past river flow data assuming the same flow records will be repeated in the future. In this study the synthetic generation methods of thomas-Fiering type and harmonic analysis were used to synthetically generate 50 years of monthly river inflows to three single-purpose reservoris(Chuncheon, Chungpyong, Hwacheon) and three multi-purpose reservoirs(Soyany, Andon, Daichung). The generated sequences of monthly flows were analyzed based on the range concept, and hence the so-determined ranges for single-prupose and multi-purpose rewervoirs were correlated with the number of monthly flow subseries, resulting an empirical equation of the Feller's type. (1) Single-purpose reservoir $$R_n=2.8357 I\sqrt{n}$$ (2) Multi-purpose reservoir $$R_n=2.5145 I\sqrt{n}$$ where, $R_n$:Range(㎥/S-M) n:periodic(12 months, ……120 months) I:Input mean(㎥/S-M) In Korea, the monthly inflow data generation will be fit to the Thomas-Fiering type, and this paper shows that the periodic range is easily calculated without the Rippl's mass-curve method as shown above formula.

• Journal of the Korean Association of Geographic Information Studies
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• v.1 no.1
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• pp.99-108
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• 1998

In order to represent the surface characteristics in local meteorological model, soil type, vegetation index, surface roughness length, surface albedo and leaf area index should be prescribed on the surface process parameterization. In this study, the $1^{\circ}/1^{\circ}leaf$ area index, surface roughness length, and snow free surface albedo and fine mesh NDVI with seasonal variation derived from the satellite observation were applied to the land surface process parameterization. From comparison between with and without satellite data in the interactions between biosphere and atmosphere, land and atmosphere, the sensitivity of the simulated heat, energy and water vapor fluxes, ground temperature, wind, canopy water content, specific humidity, and precipitation fields were investigated.

• Korean Journal of Food Science and Technology
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• v.17 no.6
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• pp.460-468
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• 1985

Changes in intrumental and sensory Theological parameters of chewing gum during storage were stuided. Texture changes are influenced to the great extent by moisture content of stored chewing gum and D.E. of cornsyrup, meanwhile content of cornsyrup, process condition and storage temperature had a little effect on texture change. Highly significant correlation was observed between logarithmic instrumental texture parameters of deformation, bending and puncture test and logarithmic moisture content. And also good correlations were observed between each sensory and instrumental texture parameters. The optimum texture values were estimated by regression analysis.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.29-36
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• 1984

Flow behaviors of rice starch-water systems containing 3-9% (w/v) of native and gelatinized starch solutions were studied with the capillary tube rheometer in the temperature range of $30-80^{\circ}C$. Flow behaviors of rice starch-water systems showed non-Newtonion behavior which could be expressed as ${\gamma}{\;}=\;{\psi}(^{\tau}g_c-{\tau}_yg_c)^N$. Flow parameters ${\psi}$, N and $^{\tau}_y$ were determined for native and gelatinized solutions. These parameters indicated that native rice starch solution shows a dilatancy and the gelatinized solution ranges from pseudoplastic to mixed type flow behavior with increasing concentrations. The value of flow behavior index for gelatinized solutions was about 1.2 in all samples but for native solutions, the values were 0.87-0.90. The values of yield stress, which were negligible below 5%, were increased with the increase in concentration from 5 to 9%. The value of consistency index was exponentially dependent on concentration and temperature. The values of activation energy for native and gelatinized solutions were 0.13-2.71 and 5.39-9.57 kcal/g mole, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.655-655
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• 2013

그래핀은 높은 전자 이동도, 열전도도, 기계적 강도, 유연성 등의 고유한 특성으로 다양한 분야에 응용하기 위한 연구가 수행되고 있으며, 특히 전자 소자에의 적용에 관한 연구가 활발히 이루어지고 있다. 전자 소자에 적용하기 위해서는 성장 및 물성에 관한 규명, 응용 소자에 따른 특성 평가가 필요하다. 이러한 소자 특성은 그래핀 물성에 의한 영향이 기본적이지만 에칭, 전사 등의 공정 중 발생하는 오염, 표면 특성, 잔여물 등에 의한 물성 변화 또한 분석 및 제어에 관한 연구가 필요하다. 열화학증착법(thermal chemical vapor deposition)을 이용한 그래핀 합성은 구리 기판을 사용하며, 합성된 그래핀의 에칭, 박리 및 전사 공정이 있다. 이러한 공정 중 발생하는 오염 입자가 그래핀 표면에 흡착되거나, 제거되지 않은 PMMA 잔여물이 그래핀의 특성에 영향을 미치게 된다. 따라서 본 연구에서는 $CO_2$ 클러스터의 표면 충돌을 이용하여 이러한 오염 물질 및 잔여물을 제거하고 그래핀 표면을 평탄화하는 것에 관한 연구를 수행하였다. 가스 클러스터란 작동기체의 분자가 수십에서 수백 개 뭉쳐 있는 형태를 뜻하며 이렇게 형성된 클러스터는 수 nm 크기를 형성하게 된다. 그리고 짧은 시간의 응축에 의해 수십 nm 크기 까지 성장 하게 된다. 클러스터를 이용한 표면 처리는 충돌에 의한 제거에 기반 한다. 따라서 생성 및 가속되는 클러스터로부터 대상으로 전달되는 운동량의 정도가 세정 특성에 영향을 미치며 이는 생성되는 클러스터의 크기에 종속적이다. 생성 클러스터의 크기 분포는 분사거리, 유량, 분사 각도, 노즐 냉각 온도 등의 변수에 관한 함수이다. 본 연구에서는 이러한 변수들을 제어하여 클러스터를 이용한 그래핀 표면 처리 실험을 수행하였다. 평가는 클러스터 표면 처리 전과 후의 특성 비교에 기반 하였으며, 광학 현미경을 이용한 표면 형상 측정, 라만분광 분석, AFM을 이용한 표면 조도 측정, 그래핀 면저항 측정 결과를 비교하였다. 평가 결과를 통하여 표면 처리를 하지 않은 그래핀에 비하여 면저항과 표면 조도가 낮아지는 것을 확인 할 수 있었다. 또한 클러스터 세정은 300 mm 웨이퍼 크기 이상의 대면적을 짧은 시간에 건식으로 세정할 수 있다는 장점이 있어 향후 최적화를 통해 그래핀 양산 시 특성 향상을 위한 후처리 방법으로 사용될 수 있음을 확인하였다.

• KSBB Journal
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• v.17 no.1
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• pp.88-92
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• 2002

The election profiles with different flow rates of motile phase were experimentally measured to investigate the effects on HETP in capillary gas chromatography. Based on the correlation coefficient ($r^2$), the first and second moments as well as HETP were determined from the elution cuties, and the parameters used in empirical equations were estimated. The empirical equations were expressed in terms of mobile phase velocity, and the theoretical Golay equation was considered. The samples were d-limonene and perillyl alcohol, potential anticancer agent mainly was contained in the peel of orange. From the experimental results, HETP of the samples were increased with mobile phase velocities. The correlation coefficient of d-limonene was in the range between 0.8265 and 0.8465, while that of perillyl alcohol was between 0.9353 and 0.9374. The total HETP was composed of $H_{g}$, $H_{l}$ and Hc, and Hg had the greatest effect on HETP, but HI showed a negligible effect. In terms of HETP, the optimum velocity of mobile phase was present.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.691-698
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• 2017

In this study, the injector transfer function (ITF) of a gas-gas coaxial jet-swirl injector is measured by applying excitation to jet or swirl flow using a loudspeaker. As a result of measuring the ITF according to the variation of feed system length, the ITF peak occurs at the resonance frequency of the space where the perturbed flow passes. When applying the excitation to the jet flow, as the jet flow increases up to 56 slpm, the magnitude of ITF decreases, and ITF increases thereafter. Therefore the larger the velocity difference between the jet and the swirl flow, the larger the ITF. In the case of the swirl excitation, the ITF decreases as the jet flow increases because of the decrease of the energy with respect to the constant flow at the downstream. This difference is caused by the location of the hot wire anemometer on the downstream of the injector center axis.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.8-18
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• 2002

In this paper, wave energy absorption of OWC(oscillating water column) device is analyzed. The analytic model consists of a partially immersed circular vertical cylinder open at its end and an air turbine connected with the air chamber. The boundary value problem is decomposed into scattering problem related to scattering by an incident wave in the absence of a pressure variation and radiation problem describing the flow due to an oscillating pressure in the absence of an incident wave. By invoking the continuity of an air flow inside the chamber, the oscillating pressure in a chamber is derived. With oscillating pressure, the mean power absorbed by OWC device and the capture width are obtained. In numerical calculation, the induced volume flux across the internal free surface of the chamber in the scattering and radiation problem and the maximum capture width are compared with various design parameters such as radius and submergence depth of chamber and wave conditions. The maximum capture width obtained by choosing the optimal value of turbine constant occurs at the first resonant mode (Helmholtz mode) among the natural frequencies of a circular cylinder chamber.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.1
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• pp.15-22
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• 2000

There are lots of industrial machines of which functions are achieved by operation of multi-phase fluids. Some of them take advantage of the characteristics of counter-current two-phase flow The maximum flow rates of gas and liquid phases which flow in opposite-directions (counter-current flow) are limited by a phenomenon known as a Counter-Current Flow Limitation (CCFL or Flooding) The mass and momentum conservation equations for each Phase were established to build a first-order hyperbolic partial derivative equations system. A new CCFL model is developed based on the characteristic equation of the hyperbolic PDE system. The present model has its applicationto the case in which a non-uniform flow is developed around a square or sharp-edged entrance of liquid phase. The model is able to he used to Predict the operating-limit of components in which mass and heat transfer are taking place between liquid and gas phases.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.1013-1018
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• 2007

In general, there are many sensors for fuel injection control such as an air flow sensor, an air intake temperature sensor, a cooling water temperature sensor, a throttle position sensor, and a motor position sensor. In this paper, we proposed a method for controlling the amount of fuel consumption in cars using fuzzy control technique by temperature change of an air intake temperature sensor and air-fuel ratio, the ratio of air and fuel mixture. In the proposed method, the amount of fuel injection is controlled by fuzzy membership functions and fuzzy inference rules established for air-fuel ratio, air intake temperature, and final fuel compensation, after computing air-fuel values using each amount of air intake and each amount of fuel injection. We verified that the proposed method is more efficient than conventional methods in fuel injection control from the results of the simulation program.