• Journal of Wetlands Research
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• v.21 no.spc
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• pp.80-89
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• 2019

The purpose of this study is to analyze the relationship between SPI (Standardized Precipitation Index) meteorological drought and RDI (Reservoir Drought Index) agricultural drought for Geum river basin. Drought Indices was calculated by collecting data of precipitation and agricultural reservoir water storage rate from 2014 to 2016. To evaluated the correlation between meteorological and agricultural drought, the Pearson correlation and the Receiver Operation Characteristic (ROC) analysis were conducted to evaluate the correlation between meteorological and agricultural droughts. The SPI-6 and RDI showed the highest relationship with Pearson coefficient 0.606 and ROC hit rates 0.722 respectively, and the spatial occurrence patterns of drought using overlapped SPI-6 and RDI, the big differences between the 2 indices were occurred in the upstream areas of Miho stream and Nonsan stream from August to October 2015. The analysis using reservoirs specifications for areas where reservoir droughts occurred was conducted, and the areas showing severe drought of RDI were the reservoir areas having relatively small value of basin magnifying power (BMP). This means that a reservoir has the reaction capability for agricultural drought mainly depending on the reservoir BMP.

• The Journal of the Korea Contents Association
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• v.18 no.5
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• pp.456-463
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• 2018

Increases in disasters and damage caused by the disasters in modern society, have a negative impact on local economy. In particular, a local economic downturn leads to a deterioration in quality of life of local residents and causes mental and material damage. Therefore, in order to achieve stable and sustainable local economic development, it is necessary to strengthen the resilience of the local economy. This study aims to estimate indicators of local economic resilience of Jindo County after the Sewol Ferry disaster, analyze a trend of the economic level after the disaster through time series data and suggest improvement plans of the local crisis management and restoration policy that considers future economic resilience. Results of this study showed that a decrease in the number of tourists and of workers in related industries hit tourism industry, causing a loss to the local economy and that an increase in a drinking rate of and stress awareness rate of local residents was a stress factor due to disaster impacts. These findings provides policy implications that it is necessary to make efforts for improving the depressed local image by utilizing local resources in the area, to build a sustainable long-term economic recovery policy and to provide psychological treatment and the relevant government and local government's support for relieving the stress of local residents due to the disaster impacts.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.69-78
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• 2007

Constructed wetlands and other aquatic systems have been successfully used for waste and wastewater treatment in either temperate or tropical regions. To treat waste or wastewater in a sustainable manner, the integrated eco-engineering designs are explained in this paper with 2 case studies: (i) a combination of vertical-flow constructed wetland (CW) with plant irrigation systemfor fecal sludge management and (ii) integrated CW units with landscaping at full-scale application for domestic wastewater treatment. The pilot-scale study of fecal sludge management employed 3 vertical-flow CW units, each with a dimension of $5{\times}5{\times}0.65m$ (width ${\times}$ length ${\times}$ media depth) and planted with cattails (Typha augustifolia). At the solid loading rate of 250 kg total solids (TS)/$m^2.yr$ and a 6-day percolate impoundment, the CW system could achieve chemical oxygen demand (COD), TS and total Kjeldahl nitrogen (TKN) removal efficiencies in the range of 80 - 96%. The accumulated sludge layers of about 80 - 90 cm was found at the CW bed surface after operating the CW units for 7 years, but no clogging problem has been observed. The CW percolate was applied to 16 irrigation Sunflower plant (Helianthus annuus) plots, each with a dimension of $4.5{\times}4.5m$ ($width{\times}length$). In the study, the CW percolate were fed to the treatment plots at the application rate of 7.5 mm/day but the percolate was mixed with tap water at different ratio of 20%, 80% and 100%. Based on a 1-year data of 3-crop plantation were experimented, the contents of Zn, Mn and Cu in soil of the experimental plots were found to increase with increasing in CW percolate ratios. The highest plant biomass yield and oil content of 1,000 kg/ha and 35%, respectively, were obtained from the plots fed with 20% or 50% of the CW percolate, whereas no accumulation of heavy metals in the plant tissues (i.e. leaves, stems and flowers) of the sunflower is found. In addition to the pilot-scale and field experiments, a case study of the integrated CW systems for wastewater treatment at Phi Phi Island (a Tsunami-hit area), Krabi province, Thailand is illustrated. The $5,200-m^2$ CW systems on Phi Phi Island are not only for treatment of $400m^3/day$ wastewater from hotels, households or other domestic activities, but also incorporating public consultation in the design processes, resulting in introducing the aesthetic landscaping as well as reusing of the treated effluent for irrigating green areas on the Island.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.147-153
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• 2011

In this paper, we present a new video management technique using forward timeline to efficiently store and delete the videos on a local server. The proposed method is based on capturing the changing preference of the videos according to recentness, frequency, and playback length of the requested videos. For this purpose, we utilize the forward timeline which represents the time area within a number of predefined intervals. The local server periodically measures time popularity and request segment of all videos. Based on the measured data, time popularity and request segment, the local server calculates the mean time popularity and mean request segment of a video using forward timeline. Using mean time popularity and mean request segment of video, we estimate the ranking and allocated storage space of a video. The ranking represents the priority of deletion when the storage area of local server is running out of space and the allocated storage space means the maximum size of storage space to be allocated to a video. In addition, we propose an efficient storage space partitioning technique in order to stably store videos and present a time based free-up storage space technique using the expected variation of video data in order for avoiding the overflow on a local server in advance. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, our video management technique for local server provides the lowest user start-up latency and the highest bandwidth saving significantly.

• Atmosphere
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• v.31 no.5
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• pp.577-592
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• 2021

This study evaluates the predictability of the number of days of heat and cold damages by growth stages of rice in South Korea using the hindcast data (1986~2020) produced by Pusan National University Coupled General Circulation Model-Weather Research and Forecasting (PNU CGCM-WRF) model chain. The predictability is accessed in terms of Root Mean Square Error (RMSE), Normalized Standardized Deviations (NSD), Hit Rate (HR) and Heidke Skill Score (HSS). For the purpose, the model predictability to produce the daily maximum and minimum temperatures, which are the variables used to define heat and cold damages for rice, are evaluated first. The result shows that most of the predictions starting the initial conditions from January to May (01RUN to 05RUN) have reasonable predictability, although it varies to some extent depending on the month at which integration starts. In particular, the ensemble average of 01RUN to 05RUN with equal weighting (ENS) has more reasonable predictability (RMSE is in the range of 1.2~2.6℃ and NSD is about 1.0) than individual RUNs. Accordingly, the regional patterns and characteristics of the predicted damages for rice due to excessive high- and low-temperatures are well captured by the model chain when compared with observation, particularly in regions where the damages occur frequently, in spite that hindcasted data somewhat overestimate the damages in terms of number of occurrence days. In ENS, the HR and HSS for heat (cold) damages in rice is in the ranges of 0.44~0.84 and 0.05~0.13 (0.58~0.81 and -0.01~0.10) by growth stage. Overall, it is concluded that the PNU CGCM-WRF chain of 01RUN~05RUN and ENS has reasonable capability to predict the heat and cold damages for rice in South Korea.

• Radiation Oncology Journal
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• v.16 no.4
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• pp.505-515
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• 1998

Purpose : This study is intended to understand the sensitometric characteristics and the emulsion properties of the commercially available CEA TVS film in comparison with the Kodak X-Omat V film. Materials and Methods : For this purpose, we have formulated an analytic expression of the characteristic curves for x-ray film exposed to mixed radiation of electrons, photons, and visible light. This mathematical expression was developed based on reaction-rate and target-hit theories. Unlike previous expressions. it relates optical density to emulsion properties such as grain size and silver bromide content We have also developed a quantity which characterizes the film response to visible light relative to that to photons and electrons. This quantity could be expressed as a function of grain area. Thus, we have developed mathematical expressions and quantities with which the emulsion properties of the films can be revealed based on the sensitometric characteristics. Demonstrating the use of this analytical study, we exposed CEA and Kodak verification films to the mixed radiation of electrons, photons, and visible light, and interpreted the experimental results accordingly. Results : We have demonstrated that: (1) the saturation density increases as the silver bromide content increases, (2) the time required to reach the threshold dose (to which the film begins to respond) when films are exposed to visible light decreases as the grain size increases, and (3) the CEA film contains more silver bromide. whereas the Kodak film contains larger grains. These findings were supported by the data provided by the manufacturers afterward. Conclusion : This study presented an analytical and experimental basis for understanding the response of X-ray film with respect to the emulsion properties.

• The KIPS Transactions:PartD
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• v.10D no.7
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• pp.1067-1076
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• 2003

Database sharing system (DSS) refers to a system for high performance transaction processing. In DSS, the processing nodes are locally coupled via a high speed network and share a common database at the disk level. Each node has a local memory and a separate copy of operating system. To reduce the number of disk accesses, the node caches database pages in its local memory buffer. In this paper, we propose a dynamic transaction routing algorithm to balance the load of each node in the DSS. The proposed algorithm is novel in the sense that it can support node-specific locality of reference by utilizing the primary copy authority assigned to each node; hence, it can achieve better cache hit ratios and thus fewer disk I/Os. Furthermore, the proposed algorithm avoids a specific node being overloaded by considering the current workload of each node. To evaluate the performance of the proposed algorithm, we develop a simulation model of the DSS, and then analyze the simulation results. The results show that the proposed algorithm outperforms the existing algorithms in the transaction processing rate. Especially the proposed algorithm shows better performance when the number of concurrently executed transactions is high and the data page access patterns of the transactions are not equally distributed.

• Management & Information Systems Review
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• v.32 no.4
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• pp.53-79
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• 2013

Social enterprises can be identified roughly as social purpose-oriented business ventures. They often fill the gaps left by governmental and commercial ventures in providing for certain vulnerable sectors of society. Though social enterprises often adopt market mechanisms in their organizational structures, their emphasis on particular social outcomes means that they intentionally pursue double/triple-bottom lines, thus distinguishing them from many traditional for-profit businesses. Among the Korean laborers, women have been hardest hit by the global economic crisis. As the movements have substantially been taken to strengthen women's economic activities in the recent years, many policies are formulated with these trends, connecting women's employment with social enterprises. This study focused on analyzing social enterprises to be friendly and to provide decent work to women. Data were collected from 491 social enterprises and 830 workers. The main results are as follows. First, the women's employment in social enterprises has accounted for a relatively high rate and the women's wage also is similar to men's one. Second, as for work conditions and types, most women have preferred irregular and non-managerial work. Thus, social enterprises have showed a positive response for the women's job opportunities, while social enterprises have had a negative one for enhancing the women's status at the labor market. In conclusion, social enterprises should institutionalize how to provide more stable working condition to women and to improve their's capacity.

• Atmosphere
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• v.29 no.5
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• pp.671-687
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• 2019

This study evaluates the long-term seasonal predictability of summer (June, July and August) heatwaves over South Korea using 30-year (1989~2018) Hindcast data of the Pusan National University Coupled General Circulation Model (PNU CGCM)-Weather Research and Forecasting (WRF) chain. Heatwave indices such as Number of Heatwave days (HWD), Heatwave Intensity (HWI) and Heatwave Warning (HWW) are used to explore the long-term seasonal predictability of heatwaves. The prediction skills for HWD, HWI, and HWW are evaluated in terms of the Temporal Correlation Coefficient (TCC), Root Mean Square Error (RMSE) and Skill Scores such as Heidke Skill Score (HSS) and Hit Rate (HR). The spatial distributions of daily maximum temperature simulated by WRF are similar overall to those simulated by NCEP-R2 and PNU CGCM. The WRF tends to underestimate the daily maximum temperature than observation because the lateral boundary condition of WRF is PNU CGCM. According to TCC, RMSE and Skill Score, the predictability of daily maximum temperature is higher in the predictions that start from the February and April initial condition. However, the PNU CGCM-WRF chain tends to overestimate HWD, HWI and HWW compared to observations. The TCCs for heatwave indices range from 0.02 to 0.31. The RMSE, HR and HSS values are in the range of 7.73 to 8.73, 0.01 to 0.09 and 0.34 to 0.39, respectively. In general, the prediction skill of the PNU CGCM-WRF chain for heatwave indices is highest in the predictions that start from the February and April initial condition and is lower in the predictions that start from January and March. According to TCC, RMSE and Skill Score, the predictability is more influenced by lead time than by the effects of topography and/or terrain feature because both HSS and HR varies in different leads over the whole region of South Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.485-493
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• 2008

The Artificial Neural Network (ANN) model was suggested for predicting probability of precipitation (PoP) using RDAPS NWP model, observation at AWS and upper-air sounding station. The prediction work was implemented for flood season and the data period is the July, August of 2001 and June of 2002. Neural network input variables (predictors) were composed of geopotential height 500/750/1000 hPa, atmospheric thickness 500-1000 hPa, X & Y-component of wind at 500 hPa, X & Y-component of wind at 750 hPa, wind speed at surface, temperature at 500/750 hPa/surface, mean sea level pressure, 3-hr accumulated precipitation, occurrence of observed precipitation, precipitation accumulated in 6 & 12 hrs previous to RDAPS run, precipitation occurrence in 6 & 12 hrs previous to RDAPS run, relative humidity measured 0 & 12 hrs before RDAPS run, precipitable water measured 0 & 12 hrs before RDAPS run, precipitable water difference in 12 hrs previous to RDAPS run. The suggested ANN has a 3-layer perceptron (multi layer perceptron; MLP) and back-propagation learning algorithm. The result shows that there were 6.8% increase in Hit rate (H), especially 99.2% and 148.1% increase in Threat Score (TS) and Probability of Detection (POD). It illustrates that the suggested ANN model can be a useful tool for predicting rainfall event prediction. The Kuipers Skill Score (KSS) was increased 92.8%, which the ANN model improves the rainfall occurrence prediction over RDAPS.