Jung-Soo Lee

Risk assessment of wind disturbance in Japanese mountain forests.

Abstract: Wind damage of coniferous plantation forests containing hinoki (Chamaecyparis obtusa) and natural broad-leaved forests was studied in the Japanese mountains. Wind conditions determined using an air flow simulation model and historical wind disturbance records were integrated within a Geographic Information System (GIS). Based on the data set, the relationships between wind disturbance, wind speed, and stand height in plantation and natural forests were analyzed. A logistic analysis technique was applied to assess the probability of wind disturbance in stands that remained intact or were damaged as a result of the Isewan Typhoon. The results indicate that higher wind speeds and greater stand heights increase the probability of wind disturbance in both plantation and natural forests. Cross tabulation of the observed disturbance percentages in relation to wind speed and stand height in coniferous plantation forests and natural broad-leaved forests revealed that the former are more likely to be disturbed by strong winds than the latter. The logistic regression model enabled us to predict the likelihood of wind disturbance at our study site. Our results confirmed that it is possible, using wind condition prediction software, to analyze wind disturbance in mountain forests with complex terrain and steep slopes. Nomenclature: Murata et al., 2004.

Spatial Analysis Modeling for the Development of Evaluating Model for Hospital Location

This study purposed to develop GIS model for evaluating hospital location in a metropolitan city. Secondly, the suitability score of hospital was compared with the number of outpatient/inpatients of hospitals. This study used administrative data collected from the annual report of the 5 ward offices from Daejeon in Korea in 2004. 7 Acute care hospitals operated in Daejeon in 2004 were selected for the analysis. The suitability of hospitals in a metropolitan city was evaluated by the economic factors which were assumed to influence the health care demand. Each criterion was measured from each Dong. Correlation coefficients between the suitability score of hospital and the number of patients were varied depending on the buffering size. The relationship showed positive relationship with the number of inpatient (0.15) and outpatients (0.10) on the 0.5km buffering size. However, the correlation coefficients were changed to a negative direction or decreased when the buffering size was increased to 1.0km, 1.5km, and 2.0km.

Economic analysis of a small-sized combined heat and power plant using forest biomass in the Republic of Korea

ABSTRACT Economic analysis was conducted on the feasibility of operating a small-sized (500kW/hour) gasification power plant producing heat and electricity in a rural town surrounded by forests in the Republic of Korea. Cost factors that were considered over the plants 20-year life included wood procurement, a wood grab loader, a chipper, a chip dryer, a gasifier, a generator, land and building, wages, and office management. All the cost factors were calculated based on the 2016 market values for logs, information from machine manufacturers, and a literature review. Revenues were estimated from selling heat and electricity using the 2016 average prices that were sourced from Korea District Heating Corporation and Korea Power Exchange, respectively. Using a spreadsheet program, cash flows for costs and revenues were arranged to calculate net present value, internal rate of return, and payback period of the plant. Also, sensitivity analyses were performed on the cost of wood procurement and revenues from selling heat and electricity, which were the most significant factors affecting the economic feasibility. The results, as reinforced by the sensitivity analysis, suggest an investment in the small-sized gasification power plant may be attractive from a financial standpoint, especially if the owners are in a position to get additional revenue from heat sales and to take advantage of Renewable Energy Credits.

Construction of a REDD Monitoring System Using GIS and RS Techniques

This study aimed to construct a MRV system for the REDD regions. The system was based on the GIS and Remote Sensing techniques, and it developed a method which could detect the land cover change area as well as evaluate its accuracy. GIS, the Remote Sensing technique and the statistical modelling technique were merged, and then we monitored areas of deforestation among the REDD regions. This study compared deforestation from administrative information (GIS deforestation1) with deforestation (RS deforestation) extracted from satellite imagery by vegetation indices (NDVI, NBR, NDWI). The highest extraction accuracy that applies filtering to NDVI with a threshold of 1.5 showed reliable accuracy 35.47% with a k-value of 0.20. However, one of the reasons for the accuracy error was due to the difference between land-use change and land-cover change. The actual rate of land-cover change deforestation was 32% on the administrative information. The other reason was a 7.52% error extraction of the forest management...

Does performing high- or low-risk coronary artery bypass graft surgery bias the assessment of risk-adjusted mortality rates of hospitals?

The purpose of this study was to analyze whether nonemergency, isolated coronary artery bypass graft (CABG) surgery for high- or low-risk patients biases the assessment of the risk-adjusted mortality rates of hospitals. This study used 2002 National Health Insurance claims data for tertiary hospitals in Korea. The study sample consisted of 1,959 patients from 23 tertiary hospitals. The risk-adjustment model used the patients` biological, admission, and comorbidity data identified in the claims. The subjects were classified into high- and low-risk groups based on predicted surgical risk. The crude mortality rates and risk-adjusted mortality rates for low-risk, high-risk, and all patients in a hospital were compared based on the rank and the four intervals defined by quartile. Also, the crude mortality rates of the three groups were compared with their 95% confidence intervals of predicted mortality rates. The C-statistic (0.83) and Hosmer-Lemeshow test (