• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.61-72
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• 2011

In order to assess hydrologic and nonpoint source pollutant behaviors in a watershed with Soil and Water Assessment Tool (SWAT) model, the accuracy evaluation of SWAT model should be conducted prior to the application of it to a watershed. When calibrating and validating hydrological components of SWAT model, the Nash-Sutcliffe efficiency coefficient (EI) has been widely used. However, the EI value has been known as it is affected sensitively by big numbers among the range of numbers. In this study, a Web-based flow clustering EI estimation system using K-means clustering algorithm was developed and used for SWAT hydrology evaluation. Even though the EI of total streamflow was high, the EI values of hydrologic components (i.e., direct runoff and baseflow) were not high. Also when the EI values of flow group I and II (i.e., low and high value group) clustered from direct runoff and baseflow were computed, respectively, the EI values of them were much lower with negative EI values for some flow group comparison. The SWAT auto-calibration tool estimated values also showed negative EI values for most flow group I and II of direct runoff and baseflow although EI value of total streamflow was high. The result obtained in this study indicates that the SWAT hydrology component should be calibrated until all four positive EI values for each flow group of direct runoff and baseflow are obtained for better accuracy both in direct runoff and baseflow.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.254-258
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• 2005

The purpose of this study is to characterize the indoor-outdoor relationship of airborne pollutants and recognize probable sources in inside and outside individual apartments in Seoul metropolitan. Simultaneous air monitoring in inside and outside of the 16 Korean Apartments classified into 2groups: less than 1 year old and more than 4 years old from October, 2004 to February, 2005were sampled f3r airborne pollutants(volatile organic compounds, formaldehyde, respiratory particles, carbon dioxide and bacteria) using the Korean Indoor Air Quality Official Method. The concentrations of $CO_2$, TVOCs, HCHO, bacteria and PM10 in the less than 1 year old apartments were determined to be $773.6{\pm}422.3ppm$, $4,393.8{\pm}2,758.2{\mu}g/m^3$, $98.0{\pm}56.4{\mu}g/m^3$, $254.0{\pm}186.3CFU/m^3$ and $31.7{\pm}14.8{\mu}g/m^3$, respectively, Also, the concentrations of those in the more than 4 years old apartments were determined to be $798.9{\pm}266.5ppm$, $792.7{\pm}398.3{\mu}g/m^3$, $70.0{\pm}30.7{\mu}g/m^3$, $245.6{\pm}122.0CFU/m^3$, $49.7f28.7{\pm}g/m^3$, respectively. The average ratios of the indoor and outdoor concentrations of $CO_2$, TVOCs, HCHO, bacteria and PM10 were 2.2, 3.6, 3.1, 3.9 and 1.4, respectively. These results of this analysis is suggested that $CO_2$, TVOCs, HCHO, bacteria and PM10 in indoor air are both emitted from source within the apartment environment and partly come from outdoor air. With the above considerations in mind, it is suggested that the research for source contribution of indoor air pollutants should be expanded and the detailed interpretation of the results on these needed further study(using principal component analysis(PCA).

• Journal of Korean Society of Environmental Engineers
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• v.33 no.8
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• pp.572-577
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• 2011

The unit load has simply been used to estimate total pollutant loading from non-point sources, however, it does not count on the variable pollutant loading according to land use characteristics and rainfall intensity. Since pollutant emission from the watershed is strongly dependent on the rainfall intensity, it is necessary to find out the relationship between pollutant loading and rainfall intensity. The objective of this study is to develop simple and easy method to compute non-point source pollution loads with consideration of rainfall intensity. Two non-point source removal facility at Gyeongan-dong (Gwangju-si) and Mohyeon-myeon (Yongin-si), Gyeonggi-do was selected to monitor total rainfall, rainfall intensity, runoff characteristics and water quality from June to November, 2010. Most of Event Mean Concentrations (EMC) of measured water quality data were higher in Gyeongan which has urban land use than in Mohyeon which has rural land use. For the case of TP (Total Phosphorus), Mohyeon has higher values by the influence of larger chemical uses such as fertilizer. The relationship between non-point source pollution load and rainfall intensity is perfectly well explained by cubic regression with 0.33~0.81 coefficients of determination($R^2$). It is expected that the pollution loading function based on the long-term monitoring would be very useful with good accuracy in computing non-point source pollution load, where a rainfall intensity is highly variable.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.1
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• pp.12-17
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• 2007

This study was conducted to evaluate the characteristics of nonpoint source pollutants discharge from a small rural watershed. A typical rural area in Gongju City, Korea, was selected as the research site. Water quality and quantity in streams and rainfall samples were analyzed periodically from May to October 2005. Pollutant loads were estimated from a nonpoint source pollution model (AvSWAT, Arcview Soil and Water Assessment Tool). During the rainy season, from June 26 to 30 September 2005 and the dry season, before 26 June and after 30 September 2005, biological oxygen demands and chemical oxygen demands accounted for 91.3% and 93.7% of annual load, respectively, while total-N and total-P were 97.1% and 91.1% of annual load, respectively. The observed stream flow was $66.5m^3sec^{-1}$, while simulation stream flow was $66.2m^3sec^{-1}$. That can be assumed that simulation can be used to estimate the stream flow without practical measurement. However, the runoff trend following the occurrence of a storm event was not recorded properly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3B
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• pp.193-201
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• 2012

In the last decade, heavy rainfall induced debris flow events have been remarkably occurred in Korea. Consequently, debris flow is becoming one of the most dangerous natural phenomena in mountainous area. Understanding and correct predicting of the runout distance of debris flow is an essential prerequisite for developing debris flow hazard map and prevention technology. Based on the simple and widely used sled model, in this study, we analyse the net efficiency of debris flows which is a dimensionless constant (=1/R) and defined by the ratio of the horizontal runout distance L from the debris flow source to deposit and the vertical elevation H of the source above the deposit. The analysis of field data observed in total 238 debris flow events occurred from 2002 to 2011 reveals that the representative value of the net efficiency of debris flows in Korea is 4.3. The data observed in Gangwon province where is the most debris flow-prone area in Korea shows that debris flows in Inje area have the runout distance longer than those in Pyongchang and Gangneung. Overall features of the net efficiency of debris flows observed in the central Korea are similar to those in the southern Korea. The estimation based on aerial photographs and available depositional conditions appears to overestimate the net efficiency compared to estimation based on the field observations, which indicates that appropriate depositional conditions need to be developed for debris flows in Korea.

• Journal of Nutrition and Health
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• v.47 no.6
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• pp.435-442
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• 2014

Purpose: The objective of this study was to develop a fatty acid database (DB) for estimation of intake levels of fatty acids in the Korean population, using data from the Korea National Health and Nutrition Survey (KNHANES). Methods: Analytical values of fatty acids in foods were collected from food composition tables of national institutions (National Fisheries Research & Development Institute, Rural Development Administration), Japan Ministry of Education, Culture, Sports, Science and Technology, US Department of Agriculture, and journal articles that previously reported analytical fatty acid content of some Korean foods. The coverage of fatty acids was C14:0, C16:0, C18:0, C18:1, C18:2 n-6, C18:3 n-3, C20:5 n-3 (EPA), C22:6 n-3 (DHA), SFA, MUFA, and PUFA (n-3, n-6, n-9). The fatty acids DB covered a total of 5,144 food items used in the KNHANES nutrition survey. The food items were preferentially filled with analytical values of the collected data source. An analytical value for each food item was selected based on the priority criteria and the quality evaluation of data sources. Missing values were replaced with calculated or imputed values using the analytical values of similar food items from the data source. Results: A total of 1,545 analytical values, 2,589 calculated values, and 1,010 imputed values were included in the fatty acid DB. The developed fatty acid DB was applied to 2,112 food items available for 2011 KNHANES data. Mean intake levels of total fatty acids and saturated fatty acids were 40.3 g/day and 13.2 g/day, respectively. The estimation of total fatty acid intake was 84.3% (men 83.2%, women 86.0%) of daily total fat intake. Conclusion: This newly developed fatty acid DB would be helpful in determining the association of fatty acids intake and related health concerns in the Korean population.

• Environmental and Resource Economics Review
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• v.24 no.4
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• pp.747-761
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• 2015

This paper investigates the impact of an increase in unit price of solid waste collection on demand for alternative solid waste disposal types. I control for other variables affecting the demand and employ both community and time fixed effects models in the estimation of each reduced-form demand functions. Estimation results show that an increase in unit price reduces the demand for garbage bag collection services of non-food solid wastes while it increases the demand for food wastes and source-separated recyclables. These results imply that reduction in the demand for non-food solid wastes collection is mainly achieved by increasing the amount of recyclables and food wastes collected. However, it appears that an increase in unit price increases the total amount of solid wastes generated. This suggests that price incentive effects are offset by the decrease in source-reduction efforts because of feedback effects resulting from the increase in recycling, food waste separation, and illegal disposal of wastes.

• Korean Journal of Environmental Agriculture
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• v.20 no.3
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• pp.192-200
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• 2001

The event-based agricultural non-point source(AGNPS) pollution model was applied to estimate the loads of nitrogen and phosphorus in a stream draining small agricultural watersheds. Calibration and verification of the model were performed using observed data collected from rainfall events in the Imgo watersheds during 1997-1998. Parameter calibrations were made for the runoff curve number. The peak flow volumes in the watersheds were well reproduced by the modified model. Average deviation between observed and simulated values was 10%, and this match was confirmed by the coefficient of efficiency value of 0.97. The deviations tended to increase as the peak flows increased. The simulated total N concentrations in the stream water were fairly close to the measured values, and the coefficient of efficiency in the estimation was 0.93. However, there were relatively large variations between calculated and observed values of total P concentration, and the coefficient of efficiency in the estimation was 0.74. Any inaccuracies that arise in estimating runoff flow and nutrient loading can not be explained exactly and further adjustment and refinements may be needed for application of AGNPS in agricultural watersheds. With this restrictions in mind, it can be concluded that AGNPS can provide realistic estimates of nonpoint source nutrient yields.

• Journal of Broadcast Engineering
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• v.23 no.4
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• pp.519-525
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• 2018

This paper deals with noise suppression of multi-channel data captured by microphone array using multi-channel Wiener filter. Multi-channel Wiener filter does not rely on information about the direction of the target speech and can be partitioned into an MVDR (Minimum Variance Distortionless Response) spatial filter and a single channel spectral filter. The acoustic transfer function between the single speech source and microphones can be estimated by subspace decomposition of multi-channel Wiener filter. The errors are incurred in the estimation of the acoustic transfer function due to the errors in the estimation of correlation matrices, which in turn results in speech distortion in the MVDR filter. To alleviate the speech distortion in the MVDR filter, diagonal loading is applied. In the experiments, database with seven microphones was used and MFCC distance was measured to demonstrate the effectiveness of the diagonal loading.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.57-65
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• 2001

The speed control without a speed sensor is expected strongly to progress reliability, simplicity and cost performance of Induction Motor(I.M) systems. Also, it contributes to expansion of I.M systems into various industrial application fields. This paper investigates a novel speed sensorless control method of I.M considering the secondary resistance identification based on the transientless torque control technique. Especially, this paper aimed at the identification of the secondary resistance simultaneously with speed estimation superposing of sinusoidal flux wave to a constant flux value. Furthermore, the secondary flux with some frequency is controlled independently on torque control. The proposed speed estimation method is derived from a motor circuit equation theoretically and also it can be conducted easily by detecting primary motor currents and primary voltage commands at every sampling time. Some numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter are performed to verify the proposed method.