• Korean Journal of Heritage: History & Science
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• v.56 no.1
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• pp.118-130
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• 2023

Decay or large cavities inside trees are the main causes of trees overturning and broken branches, and structurally weakened trees are more vulnerable to strong winds and heavy snowfall. Recently, as strong winds and typhoons increase due to climate change, the damage to human life and property due to trees overturning continues to increase, and cultural assets are in a similar situation. In particular, old big trees are structurally vulnerable to external shocks such as strong winds and heavy snowfall. This study was aimed at providing a scientific basis for preventive protection measures by conducting a structural stability diagnosis of seven retusa fringe trees designated as natural monuments. For the structural stability diagnosis, tree risk assessment and internal tree defect measurements were performed. As a result of the tree risk assessment, the Retusa Fringe Trees in Sinjeon-ri, Yangsan and Gwangyangeupsu had the highest risk of broken branches due to weak branch attachment strength. As a result of the diagnosis of internal defects of cross sections of measured trees, there were suspected cavities or severe decay in all except two trees of the population of Retusa Fringe Trees in Pyeongji-ri. Natural disasters due to climate change are increasing, and the scale is getting larger, so it is very important to preemptively manage large old trees through scientific structural safety diagnosis to manage trees that are vulnerable to environmental changes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.83-90
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• 2009

This study describes the characteristics of distribution of lift-force acting under pier deck through physical experiment. The shape of peak wave pressure was sharp when compressed air existed but was not sharp without that. Values of lift-force was different between edge point and center point in the same block. Distribution of lift-force was expressed differently owing to dimensionless of deck length (l/L), wave steepness (H/L), clearance height per wave height (D/H). The dimensionless factor of D/H affected on the lift-force the clearance between still water surface and decks. This decided the maximum of lift-force. In the case of the same values of D/H, the lift-force are changed by the wave steepness (H/L). Because (D/H) become smaller as the wave steepness (H/L) is increased the height of decks must be decided with the condition which don't have the clearance with $D_{max}$ for the stable design of deck of pier. Effect of reducing lift force was greater in the on-shore than the off-shore according to compressed air existence. This researches points out that design of deck should retain compressed air in order to reduce wave lift force.

• 한국노년학
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• v.31 no.1
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• pp.143-155
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• 2011

Disabled elderly faced with disability and the aged problems at the same time. So, this research creates two research questions and examines. First research question is how nine dimensions of daily life satisfaction according to gender difference. Second research question is how the factor of daily life satisfaction by gender difference. The data is sixty-five disabled elderly, 386 among Panel Survey of Employment for the Disabled(PSED, 2008). The methods of analysis for identifying research questions is t-test and multiple linear regression. The result of analysis on first research question, the gender difference six dimensions among nine dimensions of daily life satisfaction come out statistically significant. And The result of analysis on second research question, come out statistically significant, too. Socioeconomic status: the lower class, physical condition: bad health, chronic disease is or not, family and other people's social supports, disability: serious turn out to be factors in common. It has been suggested social policies from the results of studies that the provision of health support policy and program, enlarge assistance on daily life, support system on serious disabled elderly. On the other hand, analysis showed that distinctive factors between disabled elderly man and woman was age and education level. In other words, disabled elderly woman come out into the open that the more grow old, the less daily life satisfaction low, while disabled elderly man appeared higher daily life satisfaction in case of junior and senior high school graduate than uneducated.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.416-424
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• 2023

Concrete emits a large amount of carbon dioxide throughout its life cycle, and due to the societal demand for carbon dioxide reduction, research on storing carbon dioxide in concrete in the form of minerals is ongoing. In this study, cyanobacteria, which absorb carbon dioxide through photosynthesis and fix it as calcium carbonate, were applied to a porous concrete substrate, and the changes in the properties of the concrete substrate due to their special environmental curing condition were analyzed. The results showed that the calcium carbonate precipitation by the microorganisms was concentrated in the light-exposed surface area, and most of the precipitation occurred in the cement paste part, not in the aggregate. This microbially induced calcium carbonate precipitation enhanced the mechanical performance of the paste and improved the overall compressive strength as the curing age progressed. In addition, the increase in microbial biofilm and calcium carbonate improved the pore structure, which influenced the reduction in water permeability.

• Korean Journal of Culture and Social Issue
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• v.16 no.1
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• pp.1-18
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• 2010

This study examines the characteristics of traffic accidents involving elderly pedestrians by analyzing relevant data vis-à-vis fatal pedestrian accidents and proposes solutions to reduce such accidents. We analyzed 3,853 cases of fatal accidents involving elderly pedestrians and 1,786 cases involving younger pedestrian (these cases reflect accidents that occurred from 2005 to 2008). The results show that accidents involving the elderly occur more frequently in rural areas than urban areas, especially in autumn; this condition applies even in situations where the elderly exhibit compensation behaviors such as walking on safer roads. We found that elderly pedestrians exhibit a defective behavior in crossing roads, especially in complicated road conditions where intersections and turning/reversing vehicles represent a menacing threat. These characteristics could be explained by the degenerated physical/mental ability of the elderly and by psychological factors such as reduced level of self-confidence.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.1
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• pp.177-189
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• 2022

This study proposes policy recommendations for the Korea New Exchange ("KONEX"), which is a financial platform for SMEs and startups that relied on indirect and policy financing in the past. SMEs and venture firms with limited human and physical listing resources can grow through market incubation, and venture capitalists expect an early exit or return on investment. However, the lack of liquidity and sluggish trading volume have weakened the function of the market. Despite prior policy efforts, the number of newly listed companies has decreased while listing demand for KOSDAQ and K-OTC has increased. This study aims to suggest short- and long-term improvements in regulations and throughout the KONEX firms' listing life cycle. First, the minimum deposit requirement on individual investors should be abolished to increase the number of investors. Second, information disclosure should be conducted by firms so that the nominated advisor can focus on discovering and supporting new listed companies. Third, in order to increase trading volume, the 5% dispersion rule should be changed to 25% dispersion incentive principle. Fourth, a new track without profit condition in expedited transfer listing should be introduced because the KOSDAQ relaxes the profit realization requirements for listing. Lastly, transfer listing without additional review for firms that fulfill ownership dispersion, information disclosure, and investor protection will strengthen the incubating role of the KONEX.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.325-332
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• 2008

To characterize the initiation, propagation and termination of Cochlodinium polykrikoides blooms in the southeast coastal waters of Korea, 2007, we have analyzed the data set of phytoplankton composition, physical and chemical water properties, and meterological data. The development of C. polykrikoides bloom in 2007 can be summarized in three steps. The first stage from middle of July to end of August was characterized by an unusually persistent and strong southerly wind. C. polykrikoides blooms established already by the strong wind in the middle of south coastal waters were advected intermittently into the study area. Accordingly, highly variable cell densities of C. polykrikoides were observed. At the second stage a favorable growing conditions for C. polykrikoides was developed, which was directed by changes in wind direction from south to northeast and thus enhanced transportation of offshore waters into inshore (August 8 to 30). C. polykrikoides bloom occurred through typical mechanism and showed high cell density. The last stage was represented by disappearance of C. polykrikoides. Typoon 'Nari' carrying heavy rain brought an unfavorable habitat to C. polykrikoides. Low saline condition formed in coastal water due to typoon effects continuously drove the dominant species to diatoms and flagellates which were prevailing over C. polykrikoides in this circumstances(from the middle of September). These stepwise processes could be the causative mechanism of the extraordinarily persistent C. polykrikoides bloom observed in southeast coastal water of Korea, 2007.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.370-379
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• 2007

Short-term variations of phytoplankton community structure in the southeast coastal waters of Korea from July to September in 2006 were investigated with data set of phytoplankton, chemical and physical water properties, and meterological data. A total of 11 sampling sites of 4 different depths (surface, 5 m, 10 m, and bottom) were visited on July 11-14, July 24-26, August 7-10, August 21-24 and September 5-8. We identified 151 species in 63 genera of phytoplankton in which diatoms were the most diverse group composed of 92 species in 37 genera. Dinoflagellates were the second diverse group of 52 species in 22 genera. The other groups include 7 species in 4 genera including Raphidophytes, and Euglenophyta. After rainy season, excessive nutrients from adjacent streams to the stratified water column proliferates Chaetoceros group in July. But biomass of phytoplankton and nutrient concentrations were decreased during the period of a drought in August. However, Chaetoceros was the most dominant genera in all depths of the first, second, third and fifth cruises, except the 4th cruise on August 21-24 when dominant group were dinoflagellates including Gymnodinium spp. and Cochlodinium polykrikoides. The characteristic of phytoplankton community and environment condition during summer 2006 can be summarized as: 1) low concentration of nutrients caused by a long lasting drought in August 2) no summer outbreak of C. polykrikoides because the strength of offshore waters was weak than other years, and 3) Chaetoceros spp. was the dominant species despite short period appearance of dinoflagellates.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.1
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• pp.76-81
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• 2024

Recently, agricultural methods are changing from experience-based agriculture to data-based agriculture. Changes in agricultural production due to the 4th Industrial Revolution are largely occurring in three areas: smart sensing and monitoring, smart analysis and planning, and smart control. In order to realize open-field smart agriculture, information on the physical and chemical properties of soil is essential. Conventional physicochemical measurements are conducted in a laboratory after collecting samples, which consumes a lot of cost, labor, and time, so they are quickly measured in the field. Measurement technology that can do this is urgently needed. In addition, a soil analysis system that can be carried and moved by the measurer and used in Korea's rice fields, fields, and facility houses is needed. To solve this problem, our goal is to develop and commercialize software that can collect soil samples and analyze the information. In this study, basic soil composition measurement was conducted using soil composition measurement sensors consisting of hardness measurement and electrode sensors. Through future research, we plan to develop a system that applies soil sampling using a CCD camera, ultrasonic sensor, and sampler. Therefore, we implemented a sensor and soil analysis UI that can measure and analyze the soil condition in real time, such as hardness measurement display using a load cell and moisture, PH, and EC measurement display using conductivity.

• Korean Journal of Organic Agriculture
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• v.32 no.1
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• pp.75-90
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• 2024

Biochar is a solid substance with a high carbon content, as it is made out of biomass pyrolyzed under the condition of limited oxygen. This product has attracted attention as an environment-friendly soil amendment because it contributes to carbon neutrally and has improvement effects on the soil environment. This study conducted an experiment to evaluate soil physiochemical properties and microbial community changes in a melon greenhouse according to the applied amount of biochar to investigate the growth characteristics and yields of melons accordingly. In soil physical properties, an increase in the applied amount of biochar resulted in a decrease in bulk density and an increase in porosity of the soil, improving air permeability. In soil chemical properties, an increase in the applied amount of biochar led to a increasing of pH, organic matter and available phosphate content. In the growth characteristics of melons, there was a growing tendency of plant height, leaf length and leaf width according to the increasing application of biochar until 10,000 kg/ha. Moreover, melon yields also increased as the amount of biochar, 13~16% higher in 10,000 kg/ha biochar application than no treatment. Compared differences among microbial communities in the soil according to the application of biochar and found that plant beneficial bacteria dominated in biochar treatments. This study demonstrated the potential of biochar as an effective soil amendment in melon greenhouse by showing improvements in soil physicochemical properties and microbial communities.