• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.114-119
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• 2000

To estimate Agricultural water demand, many factors such as weather, type of crop, soil, cultivation method, crop coefficient and cultivation area, etc. must be considered. But it is not easy to estimate water demand in consideration of these many factors, which are variable according to a period and regional environment. So, this study provides estimation system for agricultural water demand(ESAD) in order to estimate water demand easily and accurately, calculates the present and future agricultural water demand and arranges all factors needed for water demand estimation. This study calibrates the application of estimation system for agricultural water demand with the data observed in the other Studies and analyzes agricultural water demand nationwide.

• The Journal of Fisheries Business Administration
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• v.47 no.2
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• pp.1-14
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• 2016

This study applied the Stochastic Frontier Analysis to estimate which independent variable affects to efficiency of aquaculture household. This study used wage and facility scale as input variables, sales volume as an output variable to estimate efficiency. Also, the study used region, species, water quality to estimate technical inefficiency factors of the model. The data used for this study were obtained by the operating costs survey using 1:1 interview method. The study selected translog production model with technical inefficiency term estimated as half-normal distribution. In addition, the study used pearson and spearman correlation coefficient among efficiency estimating models. Also, the study analysed differences among estimated efficiencies through t-test, and showed us 0.1793 in species, 0.4677 between Geojae and Masan.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.3
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• pp.145-153
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• 2015

This study aims to accurately estimate population distribution more specifically than administrative unites using a RK (Regression-Kriging) model. The RK model is the areal interpolation technique that involves linear regression and the Kriging model. In order to estimate a population’s distribution using a sample region, four different models were used, namely; a regression model, RK model, OK (Ordinary Kriging) model and CK (Co-Kriging) model. The results were then compared with each other. Evaluation of the accuracy and validity of evaluation analysis results were the basis RMSE (Root Mean Square Error), MAE (Mean Absolute Error), G statistic and correlation coefficient (ρ). In the sample regions, every statistic value of the RK model showed better results than other models. The results of this comparative study will be useful to estimate a population distribution of the metropolitan areas with high population density

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.166-172
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• 1996

The thermal-hydraulic effects of removing the RCC guide thimble plugs are evaluated for Westinghouse type PWR plants as a part of feasibility study: core outlet loss coefficient, thimble bypass flow, and best estimate flow. It is resulted that the best estimate thimble bypass flow increases about by 2% and the best estimate flow increase approximately by 1.2%. The resulting DNBR penalties can be covered within the current DNBR margin. Accident analyses are also investigated and the dropped rod transient is shown to be limiting and relatively sensitive to bypass flow variation.

• Journal of Korea Water Resources Association
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• v.54 no.12
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• pp.1223-1232
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• 2021

In this study, a new analysis method by using a "Discharge Gini Coefficient" is presented to determine the degree of inequality in daily discharge throughout the year. The Discharge Gini Coefficient can be calculated using the area relationship with the cumulative percentage of the daily mode discharge in the ascending order according to the cumulative percentage of the date of occurrence of the daily discharge throughout the year. The Discharge Gini Coefficient is presented as a value between 0 and 1, and the degree of inequality can be divided into 5 levels. The Discharge Gini Coefficient can be used to estimate the discharge stability of the downstream point relative to the upstream point. In addition, it is possible to quantify the influence of each reference discharge on the total inequality. The applicability of the Discharge Gini Coefficient was reviewed using long-term daily discharge data at eight points upstream and downstream of the four major rivers in Korea. The Discharge Gini Coefficient can also be used to analyze the discharge control effect in the downstream by the upstream dam.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.809-810
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• 2007

• Journal of computational fluids engineering
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• v.20 no.2
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• pp.81-87
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• 2015

For Underwater vehicles, Unwanted roll excursions are inevitable as they are caused by induced propeller torque, disturbances, and banking motion during turns. To estimate the manoeuvring performance of underwater vehicle, it is necessary to obtain the roll coefficient of body. This paper was covered estimation of roll coefficient of underwater vehicle using STAR-CCM+, commercial CFD(Computational Fluid Dynamics) code. The RANS equations for incompressible fluid flows was solved numerically by using a finite volume method. An MRF(Moving Reference Frame) Method was Also adopted for rotations of body. For the validation, the flow around a DARPA SUBOFF bare hull model was simulated and good agreement with experiments was obtained. And Pure roll coefficients were calculated and campared with the experimental data which were presented by Seoul National University. Finally, an underwater vehicle model with propeller was simulated and analyzed for estimation of roll coefficient variation caused by induced propeller torque.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.536-538
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• 2009

In recent day, many people are interested in wind resource for generation of electric power. Especially, it is made assessment the possibility of generation of electric power by wind resource originated from running cars and buses in downtown or highway. Moreover bus, driven in the exclusive lane, is focused on possibility of generation electric power on highway because median strip makes fast flow way between bus body and median strip and a pattern will appear in the flow way like drag coefficient. But nobody can guess whether the induced flow will increase or decrease and estimate amount of change of drag coefficient. Solving drag coefficient of bus running highway is the point of this paper. To solve this problem, we use the CFD method. The model is a bus simplified without mirror and gates. In order to assess result, the flow analysis surrounding the bus on the flat road where median strip is not installed has been compared with road with median strip. Solving condition is that the driving highway and median strip are running with 100km/h (27.8m/s).

• Asian Journal of Atmospheric Environment
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• v.9 no.1
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• pp.86-90
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• 2015

Temperature was considered to estimate the minimum detectable absorption coefficient of aerosol particles from photothermal spectroscopy. Light energy absorbed by subsequent emission from the aerosol results in the heating of the aerosol sample and consequently causes a temperature change as well as changes in thermodynamic parameters of the sample. This thermal effect is the basis of photothermal spectroscopy. Photothermal spectroscopy has several types of techniques depending on how the photothermal effects are detected. Photothermal interferometry traces the photothermal effect, refractive index, using an interferometer. Photoacoustic spectroscopy detects the photothermal effect, sound wave, using a microphone. In this study, it is suggested that the detection limit for photothermal spectroscopy can be influenced by the introduction of a slip correction factor when the light absorption is determined in a high temperature environment. The minimum detectable absorption coefficient depends on the density, the specific heat and the temperature, which are thermodynamic properties. Without considering the slip correction, when the temperature of the environment is 400 K, the minimum detectable absorption coefficient for photothermal interferometry increases approximately 0.3% compared to the case of 300 K. The minimum detectable absorption coefficient for photoacoustic spectroscopy decreases only 0.2% compared to the case of 300 K. Photothermal interferometry differs only 0.5% point from photoacoustic spectroscopy. Thus, it is believed that photothermal interferometry is reliably comparable to photoacoustic spectroscopy under 400 K.

• The Journal of Korea Robotics Society
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• v.10 no.4
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• pp.200-212
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• 2015

In classical dynamics, the coefficient of restitution is one of variables to estimate the amount of impulse. In general, we have considered the coefficient of restitution as a constant value. However, coefficient of restitution (COR) is the function of contact material and colliding velocity. Furthermore, COR is also a function of contact area. Thus, without considering the variable characteristic of COR, the actual motion of an object just after impact is not the same as we expect. A general COR model is proposed in this work and its effectiveness is verified through a cart impact experiment and its result is applied to simulation of a ball impact problem. A three-degree-of-freedom manipulator is employed as a test-bed.