• Korean Chemical Engineering Research
• /
• v.62 no.3
• /
• pp.225-232
• /
• 2024

The reduction of CO₂ emissions in the energy production sector, which accounts for 86.8% of total greenhouse gas emissions, is important to achieve carbon-neutrality. At present, 60% of total power generation in South Korea is coal and natural gas. Replacing fossil fuel with renewable energy such as wind and solar has disadvantages of unstable energy supply and high costs. Therefore, this study was conducted through the co-firing of natural gas, ammonia and hydrogen utilizing the natural gas combined cycle process. The results demonstrated reduction in CO₂ emissions and 34%~238% of the power production compared to using only natural gas. Case studies on mass fractions of natural gas, ammonia and hydrogen indicated that power production and NO_x emissions were inversely proportional to the ammonia ratio and directly proportional to the hydrogen ratio. This study provides guidelines for the use of various fuel mixtures and economic analysis in co-firing power generation.

• Journal of KIISE:Computer Systems and Theory
• /
• v.34 no.8
• /
• pp.367-376
• /
• 2007

In this paper, we introduce an application-specific and adaptive power management technique for portable systems that support dynamic voltage scaling (DVS). We exploit both the idle time of multitasking systems running soft real-time tasks as well as memory- or CPU-bound code regions. Detailed power and execution time profiles guide an adaptive power manager (APM) that is linked to the operating system. A post-pass optimizer marks candidate regions for DVS by inserting calls to the APM. At runtime, the APM monitors the CPU's performance counters to dynamically determine the affinity of the each marked region. for each region, the APM computes the optimal voltage and frequency setting in terms of energy consumption and switches the CPU to that setting during the execution of the region. Idle time is exploited by monitoring system idle time and switching to the energy-wise most economical setting without prolonging execution. We show that our method is most effective for periodic workloads such as video or audio decoding. We have implemented our method in a multitasking operating system (Microsoft Windows CE) running on an Intel XScale-processor. We achieved up to 9% of total system power savings over the standard power management policy that puts the CPU in a low Power mode during idle periods.

• Journal of Bio-Environment Control
• /
• v.21 no.3
• /
• pp.271-275
• /
• 2012

The average annual and winter ambient air temperatures in Korea have risen by $0.7^{\circ}C$ and $1.4^{\circ}C$, respectively, during the last 30 years. The continuous rise in temperature presents a challenge in growing certain horticultural crops. Chinese cabbage, one most important cool season crop, may well be used as a model to study the influence of climate change on plant growth, because it is more adversely affected by elevated temperatures than warm season crops. This study examined the influence of transplanting time, nitrogen fertilizer level and climate parameters, including air temperature and growing degree days (GDD), on the performance of a Chinese cabbage cultivar (Chunkwang) during the spring growing season to estimate crop yield under the unfavorable environmental conditions. The chinese cabbage plants were transplanted from Apr. 8 to May 13, 2011 when 3~4 leaves were occurred, at internals of 7 days and cultivated with 3 levels of nitrogen fertilization. The data from plants transplanted on Apr. 22 and 29, 2012 were used for the prediction of yield as affected by planting date and nitrogen fertilization for spring production. In our study, plant dry weight was higher when the seedlings were transplanted on 15th (168 g) than on 22nd (139 g) of April. There was no significant difference in the yield when plants were grown with different levels of nitrogen fertilizer. The values of correlation coefficient ($R^2$) between GDD and number of leaves, and between GDD and dry weight of the above-ground plant parts were 0.9818 and 0.9584, respectively. Nitrogen fertilizer did not provide a good correlation with the plant growth. Results of this study suggest that the GDD values can be used as a good indicator in predicting the top biomass yield of Chinese cabbage.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.42 no.4
• /
• pp.30-36
• /
• 2014

This study was conducted to determine the causes of unreasonable prices and small numbers of azalea cultivars by analyzing the price trends and the number of azalea cultivars announced over the last 25 years based on data from the Public Procurement Service(PPS), Korea Price Research Center and the Landscaping Tree Association(LTA)(hereinafter, officially announcing agencies and organizations) which are major references used when landscape planting is decided. The prices of azalea cultivars announced by the official announcing agencies and organizations have moved in similar patterns over the past 25 years because the prices of azalea cultivars announced by the LTA were referred to by other official announcing agencies and organizations when they officially announced the prices of azalea cultivars. The PPS set lower officially fixed prices of azalea cultivars compared to other official announcing agencies and organizations, and the reason for this is considered to be the intention of the PPS to suppress landscape tree price increases because of the government's policies to suppress price increases. The prices of azalea cultivars seem to change rapidly due to the imbalance between the demand and supply of azalea cultivars rather than the effects of consumer price fluctuation rates because the production periods of azalea cultivars are shorter when compared to other landscape trees. The prices of azalea cultivars from the official announcing agencies and organizations have been set higher than the prices in actual transactions. The reason for this is considered to be the intention of the official announcing agencies and organizations to allow landscaping companies to cover defect costs resulting from the practice of subcontracting planting work and secure profits of subcontractors for planting work. The official announcing agencies and organizations have simply announced prices of 5~8 main azalea cultivars that have been used in the past. The names of azalea cultivars being cultivated and criteria for classification have not been clear; thus, landscape designers have not written clear names of azalea cultivars to be cultivated on planting drawings as practice and landscapers planted those azalea cultivars which could be easily obtained. Therefore, it is assumed that there has been no demand for new azalea cultivars. Thus, the vicious circle in which the prices of only those azalea cultivars that were produced in the past have been announced is repeated.

• Journal of agricultural medicine and community health
• /
• v.39 no.3
• /
• pp.161-175
• /
• 2014

Objectives: This study investigates the prevalence of suicide ideation and its the related factors by gender among Korean adults. Methods: National cross-sectional data from the database of the first and second year of $5^{th}$ Korean National Health and Nutritional Examination Survey (KNHANES V-1, V-2) were used for this study. 13,165 adults (${\geq}20$ years) were included in this analysis. Results: The prevalence of suicide ideation was 9.8% for men, 18.9% for women. Renal failure, depression, melancholy, stress, perceived health status, and smoking were significant risk factors among both men and women for suicide ideation. Divorced, separated or widowed of marital status and severe physical activity were related factors of suicide ideation for men. Low educational attainment, and alcohol dependency were associated factors of suicide ideation for women. Conclusions: There was gender difference of prevalence and risk factors of suicide ideation. These gender differences should be considered for planning and implementing suicide prevention program.

• Journal of dental hygiene science
• /
• v.10 no.1
• /
• pp.39-44
• /
• 2010

The purpose of this study is to cover dental hygienists who work for metropolitan dental hospitals or clinics in Seoul city, Incheon city and Gyeonggi province from January to April 2009 and profile their awareness of Long-term Senior Care Insurance System (hereinafter called 'LSCI (System)', so that it may provide material reference data to contribute to expanding and establishing oral health medical services in the framework of LSCI System. As a result, this study could come to the following conclusions: 1. It was found that the highest priority of dental hygienists' visiting oral hygienic services under LSCI System was focused on 'caring and preventive treatment', and their secondary priority was focused upon 'oral health education.' 2. In response to a question item about whether dental hygienists need dentist's prescription in written before performing their visiting oral hygienic services, it was found that 38.2% dental hygienists answered 'Yes (necessary)' and 61.8% answered 'No (unnecessary).' 3. In response to a question item about whether dental hygienists may open up long-term senior care center, it was found that absolute majority of dental hygienists (93.4%) answered 'No' and only 6.6% dental hygienists answered 'Yes.' The standardized professional education are thought to be needed to be developed aiming at the success in oral-hygiene service within a LSCI, by strengthening professionalism in dental hygienists.

• Journal of Bio-Environment Control
• /
• v.22 no.4
• /
• pp.371-377
• /
• 2013

The government has been carrying out a project for supporting the rain shelter for hot pepper as part of measures stabilizing the demand and supply of hot pepper since 2012. However, the eaves height of single-span plastic greenhouses extensively used in farms is low, which are inappropriate for the rainproof cultivation of hot pepper. This study attempted to develop single-span plastic greenhouses which are structurally safe and have the dimensions suitable for the rainproof cultivation of hot pepper as well. The structure status of plastic greenhouses and restructuring wishes of 56 rainproof cultivation farms nationwide were investigated to set up the width and height of the plastic greenhouses. 53% of the plastic greenhouses currently in operation had a width of under 7 m and 64% of their eaves had a height of 1.5 m or less, which accounted for the highest rate. Mostly the width of 7.0 m was desired for the greenhouses and the height of 2.0 m for their eaves, so these values were chosen as the dimensions for the singlespan plastic greenhouses. After an analysis of their structural safety while changing the specifications of the rafter pipe in various ways, 5 kinds of models were suggested considering the frame ratio and installation costs. The 12-Pepper-1 model is a developed single-span plastic greenhouse for hot pepper in which a ${\emptyset}42.2{\times}2.1t$ rafter pipe is installed at an interval of 90cm and the models of 12-Pepper-2 through 5 are the other developed ones in which a ${\emptyset}31.8{\times}1.5t$ rafter pipe is installed at intervals of 60 cm, 70 cm, 80 cm and 90 cm, respectively. As a result of an analysis of economic feasibility of 12-Pepper-2 compared to 10-Single-3 in the notification of the Ministry for Food, Agriculture, Forestry and Fisheries, it turned out that there would be an increase in profits by about 1.2 million won based on one building of a greenhouse sized 672 $m^2$.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.14 no.4
• /
• pp.221-237
• /
• 2011

This study aims to investigate the environmental equity of the accessibility to urban neighborhood parks in the city of Daegu. The spatial distribution of urban neighborhood parks was explored by spatial statistics and the spatial accessibility to them was then evaluated by both minimum distance and coverage approaches. Descriptive and inferential statistics such as proximity ratio, Mann Whitney U test, and logistic regression were used for comparing the socioeconomic characteristics over different accessibilities to the neighborhood parks and then testing the distributional inequity hypothesis. The results from the minimum distance method indicated that Dalseo-gu had the best accessibility to the neighborhood parks while Dong-gu had the worst accessibility. It was apparent with the coverage method that Dalseo-gu had the best accessibility whereas Dong-gu and Nam-gu had the worst accessibility to the neighborhood parks at 500m and 1,000m buffer distances. There existed the spatial pattern of environmental inequity in old towns with respect to population density and the percentage of people under the age of 18. The spatial pattern of environmental inequity in new towns was explored on the basis of the percentage of people over the age of 65, the percentage of people below the poverty level, and the percentage of free of charge rental housing. These results were closely related to the development process of urban parks in Daegu stimulated by the quantitative urban park policy, urban development process, and residential location pattern such as permanent rental housing and free of charge rental housing. This study further extends the existing research topics of environmental justice related to the distributional inequity of environmental disamenities and hazards by focusing on environmental amenities such as urban neighborhood parks. The results from this study can be used in making the decisions for urban park management and setting up urban park policy with considering the social geography of Daegu.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.21 no.2
• /
• pp.1-23
• /
• 2018

This study aims to propose a way for evaluating thermal environment vulnerability associated with policy to improve thermal environment. For this purpose, a variety of indices concerning thermal vulnerability assessment and adaptation policies for climate change applied to 17 Korean cities were reviewed and examined. Finally, 15 indices associated with policies for improving thermal environment were selected. The selected indices for thermal vulnerability assessment were applied to Daegu Metropolitan City of South Korea as a case study. As results, 15 vulnerability maps based on the standardized indices were established, and a comprehensive map with four grades of thermal vulnerability were established for Daegu Metropolitan City. As results, the area with the highest rated area in the first-grade(most vulnerable to heat) was Dong-gu, followed by Dalseo-gu and Buk-gu, and the highest area ratio of the first-grade regions was Ansim-1-dong in Dong-gu. Based on the standardized indices, the causes of the thermal environment vulnerability of Ansim-1-dong were accounted for the number of basic livelihood security recipients, the number of cardiovascular disease deaths, heat index, and Earth's surface temperature. To improve the thermal environment vulnerability of Ansim-1-dong, active policy implementation is required in expansion and maintenance of heat wave shelters, establishment of database for the population with diseases susceptible to high temperature environments, expansion of shade areas and so on. This study shows the applicability of the vulnerability assessment method linked with the policies and is expected to contribute to the strategic and effective establishment of thermal environment policies in urban master district plans.

• Journal of the Korean Geosynthetics Society
• /
• v.14 no.4
• /
• pp.59-77
• /
• 2015

In order to meet the new requirements for landfill materials, this study planned a study to apply mixed soil of mixing bottom ash and coastal dredged soil to the dredged ground. Coal ash generated from thermal power plant is divided into fly ash and bottom ash. In the case of fly ash, many studies have been conducted because small particles causes permeability coefficient to be small during recycling so no problem has been raised in the environmental area but the utilization of bottom ash has been limited because environmental problems have been raised during recycling due to its larger particle size and greater permeability coefficient. According to recently published studies, however, the results of the study that conducted the water analysis of leachate generated in the ground improvement section using bottom ash showed that heavy metal contamination levels were found to be within the reference value and no significant environmental problems were found so utilization of bottom ash is evaluated to increase significantly in the future. This bottom ash has the particle size of sand and only transportation costs need to be considered when providing materials because the majority has been disposed and it is judged as the most suitable material in dredging landfill in the economic aspect because most thermal power plants are located in the coast and transportation costs can be reduced by ship. Also, research on mixed soil that can maximize the effect of the construction period and construction cost savings than dredged soil is determined as needed because the demand for coastal dredging reclamation is increasing such as Saemangeum project etc. Therefore, we studied self-weight consolidation characteristics depending on sample processing and mixing method of mixed soil by carrying out interior self-weight consolidation experiments on mixed soil of mixing bottom ash and Kaolinite according to the new development needs of recent coastal reclaimed ground and these result findings are expected to be used as basic data when applying the large coastal dredged ground in the future.