• Horticultural Science & Technology
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• v.34 no.2
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• pp.228-235
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• 2016

This study was conducted to determine the yield of cherry tomato (Solanum lycopersicum Mill.) grown at three planting times during the uncultivated period of strawberry. Cherry tomato was planted under condition filled with strawberry dedicated culture medium on a two-story bed with April 20, April 30, and May 10 at 2015. Fruit harvest was completed on July 31. The supply concentration of nutrient solution at the time of transplanting was started as EC $1.2dS{\cdot}m^{-1}$ and it was gradually increased to EC $2.5dS{\cdot}m^{-1}$ after blooming of the first flower cluster. Netherlands PBG solution was supplied for one minute six times per day. The heights of cherry tomato plants planted at earlier were significantly greater than those of tomato plants planted later. The heights of cherry tomato plants grown at the bottom of the bed were greater than those grown in the upper bed. The yield of cherry tomatoes planted on April 20 at the bottom of the bed was greatest with an average of 2,954 g of tomatoes per plant. There were no significant differences in the average weight and sugar content of fruit according to planting times and bed position. The yield of cherry tomato plants planted on April 20 was 18% and 34% higher than that of plants planted on April 30 and May 10. We confirmed to increase the yield of the cherry tomato when early plants planted on two-story bed. These results indicate that farmers can choose the best period of producing cherry tomato during the un-cultivated period of strawberry under two-story bed conditions.

• Journal of radiological science and technology
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• v.30 no.2
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• pp.167-175
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• 2007

There are some positive effects by the introduction of PACS(Picture Archiving Communication System). This study is to analyze the mutual relation between before and after of the introduction of PACS in terms of the environment effect. It is supposed to cause the reduction of developing and fixing wastewater according to the increase in the rate of a non-film. This study will also show the amount of wastewater. Target places were the department of image medicine(diagnostic radiation) of the general hospitals in Seoul and Gyeonggi-Do, which are equiped with full PACS. The authors examined questionnaires on the number of projection, the number of indirect projection, the amount of the film used, the number of radiation image CD loan, the amount of the developing and fixing solution used, the change of the amount of fixing wastewater. According to the analysis, we analyzed the change of the amount of developing and fixing solution per a film and the change of the amount of developing and fixing wastewater which is supposed to be reduced proportionally by the introduction of PACS. We got conclusion as below after analyzing 8 hospitals except the largest and the least amount of examination, film used, developing and fixing solution and the amount of developing and fixing wastewater in order to decrease the deviation from 10 general hospitals located in Seoul and Gyeonggi-Do. We compared data one year before adopting PACS Versus 3 years after adopting PACS. 1. The frequences of examination increased to 7,357.7 cases per month but the amount of film used decreased to 90%, from 42,774.4 to 4,181.88 after adopting the PACS. 2. 3 years after adopting PACS, monthly average amount of developing solution used decreased to 92% and the monthly average amount of fixing solution decreased to 86%. 3. Monthly average amount of developing solution used per film increased to 1.49 times and fixing solution increased as much as three times. 4. Monthly average wastewater for developing decreased to 88% and wastewater for fixing decreased up to 87%. 5. Monthly average wastewater for developing per film increased to 3.77 times and wastewater for fixing increased to 3.85 times. Although the amount of film used and the amount of developing and fixing wastewater affected by the reduction of the developing and fixing solution became less on the whole by introduction of PACS, they did not decrease proportionally. Moreover the amount of the developing and fixing solution used and the amount of developing and fixing wastewater per a film increased. That means the expectation for an environmental improvement differs from the actual condition.

• Korean Journal of Remote Sensing
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• v.28 no.1
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• pp.69-77
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• 2012

Surface insolation is one of the major indicators for climate research over the Earth system. For the climate research, long-term data and wide range of spatial coverage from the data observed by two or more of satellites of the same orbit are needed. It is important to improve the continuity and consistency of the derived products, such as surface insolation, from different satellites. In this study, surface insolations based on Geostationary Operational Environmental Satellite (GOES-9) and Multi-functional Transport Satellites (MTSAT-1R) were compared during overlap period using physical model of insolation to find ways to improve the consistency and continuity between two satellites through comparison of each channel data and ground observation data. The thermal infrared brightness temperature of two satellites show a relatively good agreement between two satellites : rootmean square error (RMSE)=5.595 Kelvin; Bias=2.065 Kelvin. Whereas, visible channels shown a quite different values, but it distributed similar tendency. And the surface insolations from two satellites are different from the ground observation data. To improve the quality of retrieved insolations, we have reproduced surface insolation of each satellite through adjustment of the Cloud Factor, and the Cloud Factor for GOES-9 satellite is modified based on the analysis result of difference channel data. As a result, the insolations estimated from GOES-9 for cloudy conditions show good agreement with MTSAT-1R and ground observation : RMSE=$83.439W\;m^{-2}$ Bias=$27.296W\;m^{-2}$. The result improved accuracy confirms that the modification of Cloud Factor for GOES-9 can improve the continuity and consistency of the insolations derived from two or more satellites.

• Journal of Intelligence and Information Systems
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• v.21 no.2
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• pp.19-47
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• 2015

In this era of knowledge economy, a variety of virtual communities are proliferating for the purpose of knowledge creation and utilization. Since the voluntary contributions of members are the essential source of knowledge, member turnover can have significant implications on the survival and success of virtual communities. However, there is a dearth of research on the effect of membership turnover and even the method of measurement for membership turnover is left unclear in virtual communities. In a traditional context, membership turnover is calculated as the ratio of the number of departing members to the average number of members for a given time period. In virtual communities, while the influx of newcomers can be clearly measured, the magnitude of departure is elusive since explicit withdrawals are seldom executed. In addition, there doesn't exist a common way to determine the average number of community members who return and contribute intermittently at will. This study initially examines the limitations in applying the concept of traditional turnover to virtual communities, and proposes five membership fluidity measures based on a preliminary analysis of editing behaviors of 2,978 featured articles in English Wikipedia. Subsequently, this work investigates the relationships between three selected membership fluidity measures and group collaboration performance, reflecting a moderating effect dependent on work characteristic. We obtained the following results: First, membership turnover relates to collaboration efficiency in a right-shortened U-shaped manner, with a moderating effect from work characteristic; given the same turnover rate, the promotion likelihood for a more professional task is lower than that for a less professional task, and the likelihood difference diminishes as the turnover rate increases. Second, contribution period relates to collaboration efficiency in a left-shortened U-shaped manner, with a moderating effect from work characteristic; the marginal performance change per unit change of contribution period is greater for a less professional task. Third, the number of new participants per month relates to collaboration efficiency in a left-shortened reversed U-shaped manner, for which the moderating effect from work characteristic appears to be insignificant.

• Korean journal of communication and information
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• v.81
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• pp.153-186
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• 2017

The purpose of this study was to identify the characteristics of village community media in Jeju by looking at the value that it's participants have experienced in the production process. Therefore, this study focused on the creation and production process of village community media, the specific value reflected in this process as well as how to activate and operate it sustainably through in-depth interviews with 12 media participants in Jeju community. As a result of the analysis, firstly, we were able to see that the migrants who are not the indigenous became the center of village community media creation in Jeju and they felt very personal 'fun', 'enthusiasm' and 'satisfaction'. It was also completely open to access and participate in village community media and its contents were filled with stories of everyday life of village residents and hidden stories of old people in the village that were not recorded. The characteristic of the production process of village community media was the horizontal communication and it reflected well the opinions of individual media participants even if it had a joint meeting. Second, as a result of examining the values applied to the production process by village community media participants, they regarded the connection of communication by voluntary participation and restoration of communities through activation of communication in functionalism as an important value. Finally, as a result of examining the challenges and development plans for sustainable management of community media in Jeju, it was required the active participation of village residents, ensuring space for village community media, providing insufficient broadcasting equipment, and the budget support from local governments, etc. It was once again confirmed that the provision of a support system for the stable activities of local governments is an urgent task for sustainable village community media.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.4
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• pp.116-130
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• 2019

In South Korea, forest fire occurrences are increasing in size and duration due to various factors such as the increase in fuel materials and frequent drying conditions in forests. Therefore, it is necessary to minimize the damage caused by forest fires by appropriately providing the probability of forest fire risk. The purpose of this study is to improve the Daily Weather Index(DWI) provided by the current forest fire forecasting system in South Korea. A new Fire Risk Index(FRI) is proposed in this study, which is provided in a 5km grid through the synergistic use of numerical weather forecast data, satellite-based drought indices, and forest fire-prone areas. The FRI is calculated based on the product of the Fine Fuel Moisture Code(FFMC) optimized for Korea, an integrated drought index, and spatio-temporal weighting approaches. In order to improve the temporal accuracy of forest fire risk, monthly weights were applied based on the forest fire occurrences by month. Similarly, spatial weights were applied using the forest fire density information to improve the spatial accuracy of forest fire risk. In the time series analysis of the number of monthly forest fires and the FRI, the relationship between the two were well simulated. In addition, it was possible to provide more spatially detailed information on forest fire risk when using FRI in the 5km grid than DWI based on administrative units. The research findings from this study can help make appropriate decisions before and after forest fire occurrences.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.3
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• pp.116-128
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• 2017

In this study, the original scenery of Baegun-dong Garden in Gangjin was compared with that of the reconstructed site to suggest directions for restoration in the future. The diachronic prototype scenery of the Baegun-dong Garden was derived by integrating the elements of the original and contemporary prototype sceneries from the old poetry series. The old poetry series is comprised of "Baegun-dong 8Yeong(詠)" by Lee Damro(李聃老), "Baegun-dong 10Su(首)" by Song Ikhwi(宋翼輝), "Baegun-dong 12Gyeong (景)" by Jeong Yakyong(丁若鏞), and "Baegun-dong 14Gyeong" by Lee Siheon (李時憲). Guidance for directions for future restoration was suggested through a comparative analysis between the diachronic prototype scenery of Baegun-dong Garden and the current scenery of the restored site. The research result is as follows. First, the prototype scenery of Baegun-dong Garden was a harmonic view composed of the camellia forest road, 'Baegun-dong' the letter carved on a rock, a cliff 'Changhabyeok(蒼霞壁)' the red letter written by Jeong Yakyong, paulownia trees, waterfalls and a maple forest. Outside the Byeolseo(別墅), there were a red plum blossom forest, a pine forest, and a bamboo forest, as well as the view of Okpanbong(玉版峯) from Jeongseondae(停仙臺). In the yard, there were Chwimiseonbang(翠微禪房), Jug-gak(竹閣), Pyeongsang(榻), a lotus Bangji(方池), Gogsugeo(曲水渠) and Hwagye(花階). Cranes were even raised in the yard. Second, comparing the diachronic prototype scenery of Baegun-dong Garden with its restored site, following a restoration guide is suggested. There should be more water flow in Baegun-dong Valley and Jug-gak should be restored. 'Changhabyeok' the red letter should be carved on the stone wall. Trees should be controlled for a better view of Okpanbong from Jeongseondae. More trees and plants, such as red plum blossom, pine tree, paulownia trees, azaleas(映山紅), chrysanthemum, orchid, daffodil, and lotus should be planted in the yard. A system of integrated guide boards is also required for effective information transmission for visitors.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.32-44
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• 2001

The purpose of this study was to investigate the effects of Er : YAG laser on cutting efficacy and temperature changes of dentin. We used the dentin specimens of human premolars and molars which contain the physiologic saline and maintain the pulpal pressure in dentinal tubules. Each specimen was exposed to Er : YAG laser with non-contact handpiece type delivery system under different treatment condition of irradiation energy, pulse repetition rate, and exposure time. Two procedures were conducted by the presence of water flow during lasing. The specimens were grouped by thickness of dentin. We investigated the cavity pattern, volume, and temperature change of dentin specimen to determine the cutting efficacy and temperature rise of Er : YAG laser, and obtained following results. 1. Cutting volume of dentin was increased by increasing the irradiation energy, pulse repetition rate, and exposure time(P<0.05). 2. Margins of abulated cavities were sharp and clean and floors of cavities were conical in shape and showing smooth surfaces. Upper diameter of abulated cavities were increasing as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased. A few cracks were observed on abulated surfaces under treatment condition of laser parameter with 150mJ, 5Hz, and 5sec. 3. Temperature was increased as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased, and temperature rise was decreased as dentin thickness was increased(P<0.05). 4. Temperature rise was decreased under water flow compared with no water flow during laser exposure(P<0.05). From these results, we think that the method of using a Er:YAG laser would be effective and safe in cutting dentin for clinical application.

• Research in Plant Disease
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• v.22 no.4
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• pp.264-268
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• 2016

The nursery test against rice blast in Korea from 2014 to 2015 was analyzed. The average of disease severity of leaf blast in 12 sites showed $3.7{\pm}2.1$ in 2014 and $4.4{\pm}2.1$ in 2015. Disease severity of leaf blast in Icheon and Cheolwon was increased ranging from $2.8{\pm}2.2$ in 2014 to $6.3{\pm}1.8$ in 2015. Using a designation system, a total of 588 isolates collected those years were categorized into 34 races in 2014 and 51 races in 2015 based on the reaction pattern of Korean differential varieties. The blast isolates of 2015 were more diverse than those in 2014. The ratios of KI race to KJ race were 54:46 in 2014 and 70:30 in 2015; however, the predominant race population was KJ-301 as 16%, and KI-101 as 15% in 2014 and 2015, respectively. These results indicate that the distribution of the blast races is getting more diverse in Korea, therefore, this research would provide the possibility to predict race distribution and change to prevent the outbreak of rice blast and will also serve as a useful information for breeding of resistant rice cultivar against blast.

• Korean Security Journal
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• no.26
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• pp.29-58
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• 2011

Since 11 September 2001, warnings of risk in the nexus of terrorism and nuclear weapons and materials which poses one of the gravest threats to the international community have continued. The purpose of this study is to analyze the aim, principles, characteristics, activities, impediments to progress and developmental recommendation of the Global Initiative to Combat Nuclear Terrorism(GICNT). In addition, it suggests implications of the GICNT for the ROK policy. International community will need a comprehensive strategy with four key elements to accomplish the GICNT: (1) securing and reducing nuclear stockpiles around the world, (2) countering terrorist nuclear plots, (3) preventing and deterring state transfers of nuclear weapons or materials to terrorists, (4) interdicting nuclear smuggling. Moreover, other steps should be taken to build the needed sense of urgency, including: (1) analysis and assessment through joint threat briefing for real nuclear threat possibility, (2) nuclear terrorism exercises, (3) fast-paced nuclear security reviews, (4) realistic testing of nuclear security performance to defeat insider or outsider threats, (5) preparing shared database of threats and incidents. As for the ROK, main concerns are transfer of North Korea's nuclear weapons, materials and technology to international terror groups and attacks on nuclear facilities and uses of nuclear devices. As the 5th nuclear country, the ROK has strengthened systems of physical protection and nuclear counterterrorism based on the international conventions. In order to comprehensive and effective prevention of nuclear terrorism, the ROK has to strengthen nuclear detection instruments and mobile radiation monitoring system in airports, ports, road networks, and national critical infrastructures. Furthermore, it has to draw up effective crisis management manual and prepare nuclear counterterrorism exercises and operational postures. The fundamental key to the prevention, detection and response to nuclear terrorism which leads to catastrophic impacts is to establish not only domestic law, institution and systems, but also strengthen international cooperation.