• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.2
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• pp.53-63
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• 2016

Monitoring of cyanobacteria bloom in reservoir systems is important for water managers responsible of water supply system. Cyanobacteria affect the taste and smell of water and pose considerable filtration problems at water use places. Harmful cyanobacteria bloom in reservoir have significant economic impacts. We develop a new method for estimating the cyanobacteria bloom using Landsat TM and ETM+ data. Developed model was calibrated and cross-validated with existing in situ measurements from Daecheong Reservoir's Water Quality Monitoring Program and Algae Alarm System. Measurements data of three stations taken from 2004 to 2012 were matched with radiometrically converted reflectance data from the Landsat TM and ETM+ sensor. Stepwise multiple linear regression was used to select wavelengths in the Landsat TM and ETM+ bands 1, 2 and 4 that were most significant for predicting cyanobacteria cell number and bio-volume. Based on statistical analysis, the linear models were that included visible band ratios slightly outperformed single band models. The final monitoring models captured the extents of cyanobacteria blooms throughout the 2004-2012 study period. The results serve as an added broad area monitoring tool for water resource managers and present new insight into the initiation and propagation of cyanobacteria blooms in Daecheong reservoir.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.97-104
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• 2005

Vision-based lane sensing systems require accurate and robust sensing performance in lane detection. Besides, there exists trade-off between the computational burden and processor cost, which should be considered for implementing the systems in passenger cars. In this paper, a stereo vision-based lane detection system is developed with considering sensor configuration aspects. An inverse perspective mapping method is formulated based on the relative correspondence between the left and right cameras so that the 3-dimensional road geometry can be reconstructed in a robust manner. A new monitoring model for estimating the road geometry parameters is constructed to reduce the number of the measured signals. The selection of the sensor configuration and specifications is investigated by utilizing the characteristics of standard highways. Based on the sensor configurations, it is shown that appropriate sensing region on the camera image coordinate can be determined. The proposed system is implemented on a passenger car and verified experimentally.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.295-308
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• 2015

We have experienced a substantial improvement in and cost-drop for genotyping that enables genetic epidemiological studies with large-scale genetic data. Genome-wide association studies have identified more than ten thousand causal variants. Many statistical methods based on linear mixed models have been developed for various goals such as estimating heritability and identifying disease susceptibility locus. Empirical results also repeatedly stress the importance of linear mixed models. Therefore, we review the statistical methods related with to linear mixed models and illustrate the meaning of their estimates.

• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.730-738
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• 2013

In recent years, low impact development (LID) has emerged as an effective approach to control stormwater in an urban area, and watershed and stormwater managers need modeling tools to evaluate alternative plans for controlling stormwater. This study illustrates how to design and evaluate the effect of non-point pollutant management using SUSTAIN which is developed by USEPA. SUSTAIN can provide evaluating, selecting, and placing LID facilities in an urban catchment based on user-defined cost-effectiveness criteria. Also, this paper suggests a minimal methodology for estimating model parameters for modeling an ungauged urban catchment to reflect the situation of typical Korean urban interested catchments which are usually ungauged. In addition, the optimal length of various LID facilities and the optimal number of units in our test catchment are estimated.

• Environmental and Resource Economics Review
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• v.13 no.2
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• pp.219-243
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• 2004

Generally, electricity market has monopoly market structure because of need of enormous investment for infrastructure. However, the introduction of competition in network industry as electricity is a tendency of the world with decreasing the effects of economy of scale due to the advancement of technology. Now, electricity industry restructuring is in progress but the competition in electricity retail market is not in force yet in Korea. Whether a effective competition exist or not is very important to policy decision maker who drive restructuring, but there are small numbers of quantitative researches on that. In this study, we estimated the effectiveness of competition in the electricity retail market through switching costs. If switching costs are high, consumers actually can be locked in incumbent firm in spite of introduction of competition. Therefore switching is a critical factor to determine effectiveness of competition and to estimate the size of switching costs quantitatively can proffer the information about whether the competition in the electricity retail market is effective or not in the future. We estimated switching costs using consumer' stated-preference data by conjoint analysis. In according to estimation results, the cost of switching process is not so high, but the relative brand loyalty of an incumbent company is significantly high. And the price is considered as the most important factor choosing an electric service commodity. Based on the empirical results, it is possible to analyze the relationship between suppliers' competitiveness resulted from management efficiency and customers' switching possibilities. The paper therefore provides guidance for suppliers in deciding to enter into retail competition and for policy makers in introducing retail competition. And it has a significance of estimating the switching costs directly.

• Journal of the Korean Society for Library and Information Science
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• v.56 no.3
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• pp.265-290
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• 2022

An economic evaluation was conducted using cost-benefit analysis for an integrated service platform of open access research articles. The data needed for benefit measurement were collected by conducting a series of surveys to service beneficiaries, including 1,313 academic researchers, 49 bio-industry researchers, and 102 researchers in various industries. Cost-benefit analysis and sensitivity analysis were conducted after estimating the total costs for system construction and operations, anticipated direct and indirect benefits. With respect to the cost-benefit analysis limited to direct benefits, the estimated benefit was KRW 82 billion, which is about 14 times of the total costs for eight years of the entire business period. With respect to the cost-benefit analysis for both direct and indirect benefits, BCR was estimated to be about 98.9 and NPV to be KRW 538.8 billion, indicating that economic feasibility of the project was sufficiently secured. The results of this analysis may help securing the investment to the integrated service platform for OA research products, and the benefit estimation model developed in this study would be utilized as an assessment tool during the rest of this project.

• Health Policy and Management
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• v.15 no.2
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• pp.16-36
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• 2005

Due to the existence of asymmetry of information between doctor and patient, it has been believed that doctor might affect patient's decision making process of purchasing medical care. Based on this notion, doctor's reimbursement method has been suggested as an effective policy device of improving efficiency of patient's medical care use by way of its affecting doctor's practice pattern. By using the Community Tracking Study (CTS) household and physician data set, which includes not only various information on patient's medical care use, but doctor's practice arrangements and sources of practice revenue, this paper investigates the effect of community doctor's characteristics of reimbursement method on community patient's medical care use under the control of patient's socio-demographic characteristics and community doctor's practice type. In the process of estimating econometric model, the endogeneity problem of individual health insurance purchase was corrected by using 2818. And due to the existence of sample selection problem, Heckman's two-step estimation method was used for strengthen the robustness of estimation which was adversely affected by sample selection problem The empirical results show that as the average value of community doctor's portion of practice revenue determined by prospective method out of total revenue increases, the community patient's total out-of-pocket medical cost decreases. This results suggest, as doctor's practice revenues are mainly determined by prospective method, such as capitation, doctors would be more conscious about practice cost, which might affect doctor's practice pattern and by which his/her patient's use of medical care would decrease.

• Korean Journal of Construction Engineering and Management
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• v.9 no.4
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• pp.182-192
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• 2008

The purpose of this research is to identify problems and solutions of domestic Life Cycle Cost analysis in BTL(Build-Transfer-Lease), a PFI(Private Finance Initiatives) project. It is expected BTL would be quite effective delivery method for public construction introducing the private's major capital investments and technologies, and obviously LCC analysis is becoming more important factor for success of BTL projects. Nevertheless, there are still some complicated issues in LCC analysis, a technique for selecting the optimal VE(Value Engineering) proposals and estimating OM&R (Operation, Maintenance, & Repair) cost of the buildings, and has been applied limitedly. This research mainly focuses on educational facility, as most frequently delivered by BTL currently, especially with two levels (Alternative LCC and Building LCC) , which is occupied main potion in BTL project. In addition, it identifies four main problems and suggests their solutions through case studies focusing six major factors (WBS, Repair Information, Life Cycle, Time value of money, Repair Information Database, LCC Model) from three projects. Advanced development of this research requires closer partnership between the private / public sectors, and their long term strategies.

• Health Policy and Management
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• v.32 no.3
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• pp.282-292
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• 2022

Background: Aging societies face social problems of increased medical expenses for older adults due to increased geriatric diseases. This study aims to analyze the relationship between the state change of multiple chronic conditions (MCC) and out-of-pocket medical expenses in the elderly aged 60 or older. Methods: The 2014-2018 Korean Longitudinal Study of Aging data were used for 2,202 elderly people. Four status change groups were established according to the change in the number of chronic diseases. The association between the change of MCC and the out-of-pocket medical cost was analyzed using the generalized estimating equation model analysis. Results: The average out-of-pocket total medical costs were 1,384,900 won for participants with MCC and 542,700 won for those without MCC, which was a statistically significant difference (p<0.0001). Compared to the reference group (simple chronic disease, SCD→SCD), the change in multiple chronic conditions significantly increased the total out-of-pocket medical expenses in MCC→MCC and SCD→MCC groups (MCC→MCC: 𝛽=0.8260, p<0.0001; SCD→MCC: 𝛽=0.6607, p<0.0001). Conclusion: In this study, it was confirmed that the prevalence of MCC increased with age, and the out-of-pocket medical cost increased in the case of MCC. Continuity of treatment can be achieved for patients with MCC, and the system and management of treatment for MCC are required to receive appropriate treatment.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.5 s.311
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• pp.52-61
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• 2006

Orthogonal wavelet tansform which is generally used in image and signal processing applications has limited performance because of lack of shift invariance and low directional selectivity. To overcome these demerits complex wavelet transform has been proposed. In this paper, we present an efficient image denoising method using dual-tree complex wavelet transform and Bernoulli-Gauss prior model. In estimating hyper-parameters for Bernoulli-Gaussian model, we present two simple and non-iterative methods. We use hypothesis-testing technique in order to estimate the mixing parameter, Bernoulli random variable. Based on the estimated mixing parameter, variance for clean signal is obtained by using maximum generalized marginal likelihood (MGML) estimator. We simulate our denoising method using dual-tree complex wavelet and compare our algorithm to well blown denoising schemes. Experimental results show that the proposed method can generate good denoising results for high frequency image with low computational cost.