• Korean journal of applied entomology
• /
• v.50 no.3
• /
• pp.235-245
• /
• 2011

Temperature-related parameters of Panonychus citri (McGregor) (Acarina: Tetranychidae) development were estimated and a stage-structured matrix model was developed. The lower threshold temperatures were estimated as $8.4^{\circ}C$ for eggs, $9.9^{\circ}C$ for larvae, $9.2^{\circ}C$ for protonymphs, and $10.9^{\circ}C$ for deutonymphs. Thermal constants were 113.6, 29.1, 29.8, and 33.4 degree days for eggs, larvae, protonymphs, and deutonymphs, respectively. Non-linear development models were established for each stage of P. citri. In addition, temperature-dependent total fecundity, age-specific oviposition rate, and age-specific survival rate models were developed for the construction of an oviposition model. P. citri age was categorized into five stages to construct a matrix model: eggs, larvae, protonymphs, deutonymphs and adults. For the elements in the projection matrix, transition probabilities from an age class to the next age class or the probabilities of remaining in an age class were obtained from development rate function of each stage (age classes). Also, the fecundity coefficients of adult population were expressed as the products of adult longevity completion rate (1/longevity) by temperature-dependent total fecundity. To evaluate the predictability of the matrix model, model outputs were compared with actual field data in a cool early season and hot mid to late season in 2004. The model outputs closely matched the actual field patterns within 30 d after the model was run in both the early and mid to late seasons. Therefore, the developed matrix model can be used to estimate the population density of P. citri for a period of 30 d in citrus orchards.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.3B
• /
• pp.169-174
• /
• 2012

For efficient water management in the Ara River during the flood season, applicability of flood simulation model in the ungaged Gulpo watershed has been tested. In the Gulpo River watershed, fundamental hydrologic data such as water level and flowrates are very limited and selection of the reliable hydrologic parameters are very important for model application. This study tested reliability of parameters estimated using the empirical equation based on the HEC-HMS runoff simulation. Also coupled with HEC-RAS hydraulic routing model, simulated flowrates from HEC-HMS has been compared with the observed water levels collected at the upstream and downstream of the Gyulhyun Weir station during the flood event in 2010. Based on this information, stage-discharge curve has been developed and its reliability has been tested for flood event in 2011.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.20 no.3
• /
• pp.247-254
• /
• 2008

The double-peak normal distribution function (DPDF) suggested by Cho et al.(2004) has the problems that the extremely high and low tidal elevations are frequently generated in the Monte-Carlo simulation processes because the upper and lower limits of the DPDF are unbounded in spite of the excellent goodness-offit results. In this study, the modified DPDF is suggested by introducing the upper and lower value parameters and re-scale parameters in order to remove these problems. These new parameters of the DPDF are optimally estimated by the non-linear optimization problem solver using the Levenberg-Marquardt scheme. This modified DPDF can remove completely the unrealistically generated tidal levations and give a slightly better fit than the existing DRDF. Based on the DPDF's characteristic power, the over- and under estimation problems of the design factors are also automatically intercepted, too.

• Journal of Korea Water Resources Association
• /
• v.38 no.7 s.156
• /
• pp.555-564
• /
• 2005

In this study, a simple rainfall-runoff model was proposed by using the hydraulic routing model that requires relatively few parameters. The parameters of this model were estimated by the watershed characteristics data, and were applied to the Soyang watershed and Ui stream watershed by using the kinematic wave for overland flow and dynamic wave routing for channel routing. In order to demonstrate validity, the proposed approach was compared to the HEC-1 model for the Soyang watershed. As the results of modeling have shown, the hydraulic model shows reasonable results similar to that of the HEC-1 model. This model also represents good results for the Ui stream watershed. Hence, even if this model is a simple rainfall-runoff model using general methodology, it is competitive to the natural watershed. However, it is still difficult to estimate the roughness coefficient and the catchment width, and therefore this model is in need of such supplements.

• Journal of Korean Society for Geospatial Information Science
• /
• v.15 no.2 s.40
• /
• pp.33-42
• /
• 2007

A physical-based aggregation method was suggested to estimate surface roughness, which adequately represents the spatial heterogeneity of vegetation factors, from land cover property obtained from the remote sensing data. For the sensitivity analysis of surface roughness, the peak flow, peak time, and total volume were simulated by the NWS-PC. Effects of surface roughness estimated by three different integration methods (predominant, arithmetic mean, and aggregation approach) on the conceptual rainfall-runoff model parameters was analyzed. In the preliminary sensitivity test to surface roughness, the peak time had 10% variation and total volume had 2% variation. The peak time increased with surface roughness. A physical-based aggregation method was better than the existing method in the Soyanggang Dam basin for the results of STDEV, RMSE, NSE, and PME, but difference between them were small. The parameters related on the total baseflow were changed significantly with change of the surface roughness.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.3
• /
• pp.470-475
• /
• 2012

In Q-algorithm of EPCglobal Class-1 Gen-2 RFID system, the initial value of $Q_{fp}$, which is the slot-count parameter, is not defined in the standard. And the values of weight C, which is the parameter for incrementing or decrementing the slot-count size, are not determined. Therefore, if the number of tags is small and we let the initial $Q_{fp}$ be large, the number of empty slot will be large. On the other hand, if we let the initial $Q_{fp}$ be small in spite of many tags, almost all the slots will be collided. Also, if the reader selects an inappropriate weight, there are a lot of empty or collided slots. As a result, the performance will be declined because the frame size does not converge to the optimal point quickly during the query round. In this paper, we propose a scheme to allocate the optimal initial $Q_{fp}$ through the tag number estimation and select the weight based on the slot-count size of current query round.

• Journal of Korea Water Resources Association
• /
• v.41 no.6
• /
• pp.565-574
• /
• 2008

Fire-enhanced soil hydrophobicity often increases runoff and erosion in the mountain hillslope following severe wildfires. Estimation techniques for WEPP's parameters were studied in burnt mountain slopes. In burnt mountain slopes, the model over-predicted runoff in the small runoff and under-predicted runoff in the great runoff, and in the lower sediment runoff it had a tendency to over-predict soil loss. The effective hydraulic conductivity was most sensitive in the WEPP's runoff and its sediment runoff was mainly effected by the effective hydraulic conductivity, initial saturation, rill erodibility, and interrill erodibility. To improve the applicability of the WEPP, the adjustment coefficient of effective hydraulic conductivity was defined for runoff and the adjustment coefficient of rill erodibility and interrill erodibility was presented for sediment runoff. The adjustment coefficient of effective hydraulic conductivity in wildfire mountain slopes increased with maximum rainfall intensity of single storm and the vegetation height index. The adjustment coefficients of rill erodibility depended on soil components of size distribution curve and total rainfall depths in single storm. The adjustment coefficients of interrill erodibility decreased with increases of maximum rainfall intensity and vegetation height index. These results may be used in the application of WEPP model for wildfire mountain slopes.

• Journal of Korea Water Resources Association
• /
• v.33 no.1
• /
• pp.87-98
• /
• 2000

The objective of this study is to test the flood forecasting capability of TOPMODEL on a single watershed in Korea. The selected study area is the Soyang River basin with outlet at Soyang Dam site. The three daily hydrographs and the three hourly flood events during 1990~1996 are selected for model calibrations and performance tests. The model parameters are estimated on 1990 daily event by manual fitting technique and the effects of topographic index distribution to river flow simulations are investigated on the study area. The model performance on correlation coefficient between the observed and the simulated flows for the verification periods are above 0.77 on the 95-, 96-daily events, while above 0.87 for 90-, 95-, 96-hourly events. By the consideration of flood flow characteristics in Korea, the physical interpretation of the model concept, and the model performance, it can be concluded that the TOPMODEL is feasible as a flood forecasting model in Korea. Korea.

• Journal of Korea Water Resources Association
• /
• v.33 no.1
• /
• pp.123-132
• /
• 2000

In the study the instantaneous unit hydrographs (IUHs) based on the linear Nash (1957) and the nonlinear Diskin (1964) models are derived and compared for the Soyang river basin. Total 14 rainfall runoff events are used for the study and the model parameters are estimated by minimizing the sum of square error considering runoff hydrograph ordinates as relative weights. The representative IUHs for both models are decided to show an average shape of derived IUHs. In the application of the representative IUHs of Nash and Diskin, Diskin model shows better performances in reproducing the observed outflows, especially the peak flow. In the comparison of two Diskin models little difference could be found between the IUHs with the same or different number of two characteristic reservoirs.rvoirs.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.4C
• /
• pp.476-483
• /
• 2009

Tracking and detecting targets by the microwave seeker is affected by the clutter reflecting from the earth's surface. In order to detect retreating targets in look-down scenario, which appear in the sidelobe clutter (SLC) region, in the microwave seeker of high pulse repetition frequency (HPRF) mode, it is necessary to understand statistical characteristics of the surface SLC. Statistical analysis of SLC has been conducted for several kinds of the surface using data obtained by the captive flight test of the microwave seeker in the HPRF mode. The probability density function (PDF) fitting is conducted for several kinds and conditions of the surface. PDFs and PDF parameters, which best describe statistical distribution of the SLC power, are estimated. By using the estimated PDFs and PDF parameters, analyses for setting the target-detection thresholds, which give a desired level of target-detection false alarm probability, are made. These analysis materials for statistical characteristics of SLC power and the target-detection threshold can be used in various fields, such as development of a target-detection method, the constant false alarm rate processing.