• Journal of Ocean Engineering and Technology
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• v.30 no.1
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• pp.25-31
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• 2016

In this study, hydrodynamic coefficients were obtained from a Rotating Arm (RA) test, which is one of the captive model tests used to provide accurate coefficients in the control motion equation of an underwater vehicle. The RA test was carried out at the RA facility of ADD (Agency for Defense Development), and the forces and moments acting on the underwater vehicle were measured using a six-axis waterproof gage. A multiple regression analysis was used in the analysis of the measured data. The experimental results were also verified by comparison with the theoretical values of the previous linear coefficients. In addition, the stability indices in the horizontal plane were calculated using the linear and nonlinear coefficients, and the dynamic stability of the underwater vehicle was estimated to have a good dynamic performance with a depth ratio of 6.0.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.343-348
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• 2018

This paper proposes a simple procedure for estimating the acoustical parameter values in an occupied classroom from measurements in the unoccupied classroom. The total sound absorption in an unoccupied classroom can be calculated from measured reverberation times in the room. The expected occupied absorption can be calculated using equation that was obtained in a previous study (Choi, 2016) by fitting a linear regression line to a plot of total occupied absorption versus the corresponding unoccupied total absorption values measured in 12 university classrooms. The ratios of occupied-to-unoccupied sound absorption are used to predict increments in the values of acoustical parameters when occupants are added to the rooms. Occupied values of acoustical parameters can be estimated from unoccupied values and the change in total room absorption due to adding occupants.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1043-1050
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• 2000

The nutritional value of commercial instant noodles produced in summer and winter seasons were investigated. Only the noodle itself was used for the analysis. The content of carbohydrate was calculated by difference. The calorie was estimated by using a conversion factor of 4.32 for protein, 9.21 for fat and 4.20 for carbohydrate. Bag-type instant noodles had higher moisture, but lower content of fat and calorie compared with bowl-type products. No seasonal variations on composition and calorie were found. The calorie was negatively correlated with moisture or carbohydrate content, and positively correlated with fat content. The calorie estimated from linear regression equation of calorie vs. moisture was similar to the value calculated using a conversion factor, which implies that the calorie of the instant noodle can be simply estimated from the moisture content. The intakes of calorie from fat accounted for 30.8% and 34.1% from bag-type and bowl-type noodles, respectively. The content of ash and fat, and calorie were significantly decreased upon cooking, which were more pronounced in the bowl-type products. At the same moisture contents the loss of calorie for bag-type products was 3.5% and for bowl-type ones was 7.7%.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.25-36
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• 1995

It is important to separate the compostables from waste for successful operation of composting plant, since various compositions are mixed in it. For the separation of compostables, it is necessary to estimate total amounts of compostables from several sources. Based on it, required capacity and number of composting plant as well as proper waste collection and transportation system can be determined. So, amounts of garbage, major target material for composting. were estimated in this study. In survey of unit garbage generation(UGG). different estimation results would be obtained depending on the basis of its measurement. However, previous researches did not consider it. In this paper, the correlations between area and the number of user of garbage source were analyzed to find the related equations which were apllyed to estimation of total generation. Obtained results are as the following. Relative variations of measured UGG based on area and custumer are 62.5 and 52.8, respectively. In linear regression, related equation between area and custumer was Y=0.244X+59.0 (X=area, Y=custumer). The correlation factor r is 0.904. Equation Y=616.5X/(X+1215.4) was also obtained from linear regression using Monod equation (r=0.720). From the first order equation and measured data of UGG based on custumer, amounts of garbage generation from restaurant in Seoul and the whole country were calculated to 2043.9 ton/d and 9014.0 ton/d, respectively. But, the values calculated from measured data of UGG based on area were as low as 821.3 ton/d Cin Seoul) and 3821.0 ton/d(in the whole country). Consequently, the measurement of unit garbage generation based on the number of custumer was more favorable to lessen the points of survey and to guarantee the representative values. Especially, it would fit well on restaurant having statistics of area.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.75-86
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• 1985

A beam with web opening may reduce the cost of steel and the height of multistory steel buildings. Bower's analysis based on the theory of elasticity and Vierendeel analysis had evaluated the normal stresses around the holes, but these analyses have difficulties for practical uses because of complexity and the limitation for their application. In this study, it is shown that the finite element method, using smaller number of isoparametric elements by taking only a part of the beam which includes the hole, can diminish defects of the above two methods and it may represent more satisfactorily the distribution of the local stress concentration around the hole than the other methods which employed linear elements such as in the analysis by Samuel or Redwood. This study presents the effects of moments, shears, and eccentricities of a hole on the distribution of the normal stresses calculated by using the proposed finite element method. Consequently, it is found that the variations of shear force and hole depth give significant effects on the normal stresses around a hole, while the variations of eccentricities of the hole provide a little effect on them. The regression coefficients resulted from the multiple linear regression may be used for estimating the normal stresses around any arbitrary hole in the web of a beam, since the normal stresses guessed by this regression coefficient equation match well the results by the finite element method except the case of large eccentricity.

• Analytical Science and Technology
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• v.34 no.6
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• pp.241-250
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• 2021

Calibration curves are essential in quantitative methods and for improving the accuracy of analyte measurements in biological samples. In this study, a statistical analysis model built in the R language (The R Foundation for Statistical Computing) was used to identify a set of weighting factors and regression models based on a stepwise selection criteria. An LC-MS/MS method was used to detect the presence of urinary methamphetamine, amphetamine, and 11-nor-9-carboxy-Δ⁹ -tetrahydrocannabinol in a sample set. Weighting factors for the calibration curves were derived by calculating the heteroscedasticity of the measurements, where the presence of heteroscedasticity was determined via variance tests. The optimal regression model and weighting factor were chosen according to the sum of the absolute percentage relative error. Subsequently, the order of the regression model was calculated using a partial variance test. The proposed statistical analysis tool facilitated selection of the optimal calibration model and detection of methamphetamine, amphetamine, and 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol in urine. Thus, this study for the selection of weighting and the use of a complex regression equation may provide insights for linear and quadratic regressions in analytical and bioanalytical measurements.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.4
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• pp.388-393
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• 2008

Earth observation satellite imagery having medium-resolution can provide the useful information very rapidly and cheaply. The objective of this study was to assess the feasibility for monitoring rice growth and yield using medium resolution satellite imagery at Seosan AB reclaimed area, Chung-nam province. Using the LANDSAT imagery at booting stage ($29^{th}$ July 2004), $NDVI_R$ had the most significant linear relationships with rice yield of Seosan AB reclaimed area with the correlation coefficient (r) as 0.68. Therefore, this relationship was established as rice yield equation as function of $NDVI_R$, where excluding the 10 small area having low number of pixel, the determination coefficient ($R^2$) of the linear regression between NDVIred and milled rice yield was improved to 0.66. In addition, raster masking method, which was easier and faster even if a little unaccurate than preexisting method, was established for extracting information paddy field zone. Adaptability of rice yield equation function of $NDVI_R$ on year and region was investigated using rice yield and $NDVI_R$ values, which were extracted with raster masking method, from 7 counties or cities, Kyeong-ki province in 2005. Relationship between observed and calculated rice yield showed 1:1 line indicating that the adaptability was admitted.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.260-260
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• 2016

Soil erosion is a very serious problem from agricultural as well as environmental point of view. Various computer models have been used to estimate soil erosion and assess erosion control practice. Universal Soil loss equation (USLE) is a popular model which has been used in many countries around the world. Erosivity (USLE R-factor) is one of the USLE input parameters to reflect impacts of rainfall in computing soil loss. Value of R factor depends upon Energy (E) and maximum rainfall intensity of specific period ($I30_{max}$) of that rainfall event and thus can be calculated using higher temporal resolution rainfall data such as 10 minute interval. But 10 minute interval rainfall data may not be available in every part of the world. In that case we can use hourly rainfall data to compute this R factor. Maximum 60 minute rainfall ($I60_{max}$) can be used instead of maximum 30 minute rainfall ($I30_{max}$) as suggested by USLE manual. But the value of Average annual R factor computed using hourly rainfall data needs some correction factor so that it can be used in USLE model. The objective of our study are to derive relation between averages annual R factor values using 10 minute interval and hourly rainfall data and to determine correction coefficient for R factor using hourly Rainfall data.75 weather stations of Korea were selected for our study. Ten minute interval rainfall data for these stations were obtained from Korea Meteorological Administration (KMA) and these data were changed to hourly rainfall data. R factor and $I60_{max}$ obtained from hourly rainfall data were compared with R factor and $I30_{max}$ obtained from 10 minute interval data. Linear relation between Average annual R factor obtained from 10 minute interval rainfall and from hourly data was derived with $R^2=0.69$. Correction coefficient was developed for the R factor calculated using hourly rainfall data.. Similarly, the relation was obtained between event wise $I30_{max}$ and $I60_{max}$ with higher $R^2$ value of 0.91. Thus $I30_{max}$ can be estimated from I60max with higher accuracy and thus the hourly rainfall data can be used to determine R factor more precisely by multiplying Energy of each rainfall event with this corrected $I60_{max}$.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.263-276
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• 2008

In diverse hydrogeologic fields, estimation of groundwater storage change is one of the most critical issues. Accurate estimation methods for determining groundwater storage change are required more and more. For Yeonyang area of Ulsan Megacity, groundwater storage change was estimated by using water balance method and hydrogeological analyses. The estimates of groundwater storage change was 240 mm corresponding to 18.7% of mean annual precipitation. Direct runoff was calculated as 137 mm (10.6% of mean annual precipitation) by using SCS-CN method. Evapotranspiration based on the Thornthwaite method was calculated as 776 mm (60.5% of mean annual precipitation). Hydraulic properties of the soil types do not show any distinct relation with hydraulic conductivity of the rocks. This fact suggests that hydraulic property on the surface is different from that of subsurface geology. According to multi-linear regression analysis between groundwater storage change and hydraulic parameters, a regression equation of groundwater storage change, which was explained by precipitation and evapotranspiration, was established.

• Journal of the Korean Society for Railway
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• v.17 no.3
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• pp.165-170
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• 2014

The resistance to motion of the Korean next-generation high-speed train (HEUM-430X) was assessed on the basis of 12 coasting test runs at coasting speeds up to approximately 380km/h. Two different methods, a linear regression method and a time-integral method, were employed to calculate decelerations from the time-velocity data and the time-distance data, respectively, and an equation of resistance to motion was devised from the deceleration data calculated at each time section. The effect of an improvement of the aerodynamic shape on the resistance to motion was investigated, with the results showing that the running resistance was reduced by about 15% due to these improvements. An increase of approximately 28% of the running resistance was also noted when running in a tunnel relative to running through an open field.