• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.4
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• pp.61-71
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• 2001

In these days, surveying instruments are developing rapidly and the precision is improving continuously. The reappearance of three dimensional terrains of a great precision are possible and the calculation of the area or the volume has a high precision due to the development of the technique of the spatial information system using computer. But actually, in construction site they calculate two-dimensional area using the traditional method, plane table surveying, planimeter, and then get ground surface area through timing the slope correction factor. In this study, I show the defect and inefficiency of the calculation of the area by the traditional methods and survey the area with Electronic Distance Measuring equipment and GPS instrument. With these data, we made the three dimensional terrain model and calculated two-dimensional area and ground surface area. After that, I compared areas that calculated by algorithm method of irregular triangle and analysis of grid method with standardizing the area that calculated by the traditional method. Finally, I suggested more effective and precise method in calculating ground surface area.

• Journal of Korea Water Resources Association
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• v.53 no.1
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• pp.45-56
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• 2020

This study aims to quantify the uncertainty that can be induced by the objective function when calibrating SWAT parameters using SWAT-CUP. SWAT model was constructed to estimate runoff in Naesenong-cheon, which is the one of mid-watershed in Nakdong River basin, and then automatic calibration was performed using eight objective functions (R², bR², NS, MNS, KGE, PBIAS, RSR, and SSQR). The optimum parameter sets obtained from each objective function showed different ranges, and thus the corresponding hydrologic characteristics of simulated data were also derived differently. This is because each objective function is sensitive to specific hydrologic signatures and evaluates model performance in an unique way. In other words, one objective function might be sensitive to the residual of the extreme value, so that well produce the peak value, whereas ignores the average or low flow residuals. Therefore, the hydrological similarity between the simulated and measured values was evaluated in order to select the optimum objective function. The hydrologic signatures, which include not only the magnitude, but also the ratio of the inclining and declining time in hydrograph, were defined to consider the timing of the flow occurrence, the response of watershed, and the increasing and decreasing trend. The results of evaluation were quantified by scoring method, and hence the optimal objective functions for SWAT parameter calibration were determined as MNS (342.48) and SSQR (346.45) with the highest total scores.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.179-188
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• 2020

Weeding refers to the process of removing weeds around crop trees, which cause competition in nutrients, moisture, and light, and has a great effect on the early growth and survival of crop trees for establishing forest resources. This study was conducted to find out the timing and method of weeding that is the most suitable for the major afforestation species in national forests. We investigated (1) weeding time and frequency for each afforestation species and (2) the height of crop trees and the length of weeds. Up to 99% weeding operation was carried out until 5 years following afforestation. Pinus densiflora, Larix kaempferi, Chamaecyparis obtusa, Prunus sargentii, and Betula platyphylla plantations accounted for more than 70% of the total weeding sites. Once-a-year weeding process was conducted from late June to late July (67%), and twice-a-year weeding process was the highest in June-August by 31%. Most species were shorter than the weeds until the first and second year of planting, but the height of the crop trees was higher than that of the weeds by 48% in average from the third year. Therefore, from the third year of afforestation, except for some species, it is possible to reduce the cost of weeding operations while reducing nutrient competition by the weeds through the removal of weed sprouts, mainly woody weeds, rather than clear cutting. This study contributes to efficiently develop forest resource establishment while reducing operational costs through a detailed weeding schedule and species-specific method.

• The Journal of Engineering Geology
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• v.19 no.2
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• pp.139-144
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• 2009

The microseismic monitoring system with wide range of frequency has been operating in real time and it is remotely monitored at indoor and on-site for one year. This system was constructed and established in order to secure the safe and effective operation of the KAERI Underground Research Tunnel(KURT). For one year monitoring work, total 14 events were recorded in the vicinity of the KURT, and the majority of events are regarded as ultramicroseismic earthquake and artificial impacts around the tunnel. The major event is the magnitude 3.4 earthquake which was centered around Gongju city, Chungnam Province. It means that there is no significant evidence of high frequency microseismic event, which is associated with fracture initiation and/or propagation in the rock mass and shotcrete. Three components sensor was applied in order to analyze and define the direction of vibration as well as an epicenter of microseismic origin, and also properly designed and installed in a small borehole. This monitoring system is able to predict the location and timing of fracturing of rock mass and rock fall around an undreground openings as well as analysis on safety of various kinds of engineering structures such as nuclear facilities and other structures.

• The Journal of Korean Society for School & Community Health Education
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• v.8 no.2
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• pp.49-59
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• 2007

Objectives: This study was designed to understand the oral health fact of high school students, search for an education method and learning goal appropriate for the subjects, and utilize them as basic data to think of effective solutions for oral health care. Methods: The samples to achieve the purpose of this research are composed of 386 students in J industrial high school, OO city, Kyounggido, the number of male students 286, and female students 100. Data were statistically analyzed by frequency analysis, cross tabulation by using SPSS WIN Ver. 12.0. Results: First, The answers in terms of oral symptoms were in the order of 31.8% for gum hurt and bleeding, 31.4% for pain in teeth by drinking or eating hot and cold drinks or food, 27.1% for broken or cracked teeth, 25.7% for aching and throbbing teeth, 20.6% for unpleasant mouth smell, and 5.7% for pain of tongue and soft oral tissues. Second, In terms of behavior for oral health, 88.4% answered that they consume cariogenic snacks, while 29.2% of them, 2.5% of male and 6.3% of female enjoy consuming them but hardly brush their teeth after consumption. Third, In terms of timing for brushing teeth, the results show that 50.0% do so before breakfast, 47.9% after breakfast, 15.2% after lunch, 36.9% after dinner, 65.5% before going to sleep, and 3.5% after consuming snacks, whereas 64.2% answered that they are not aware of fluorine mouthwash. Fourth, In terms of oral health condition. proportion of children with one or more caries in permanent teeth was 71.0%, while 51.4% have $2{\sim}3$ cariogenic teeth, and 16.8% have more than 4 cariogenic teeth. Considering sex, female students have somewhat higher ratio showing 68.5% for male and 78.0% for female, but the ratio was 53.1% for male and 46.7% for female in case of $2{\sim}3$ cariogenic teeth, and 17.5% for male and 15.8% for female in case of more than 4 cariogenic teeth. 9.3% of students turned out to have decayed teeth. Fifth, In terms of oral hygiene condition, only 7.9% of them had excellent condition, and 38.4% need to improve. More specifically, 41.1% of male students and 30.6% of female students need to improve their oral hygiene condition. Conclusions: The study results suggest that School Dental health programs increase and need to be community-incorporated and comprehensive from elementary to high school.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.603-611
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• 2011

In order to enhance cutting efficiency of reed culms, we had assessed diverse methodology in cutting and applied better conditions among them into three vigorous eco-types of common reed. From the results, differences in a eco-type, a sampling area in reed population and substrata affected the shoot emergence slightly. On the other hand, differences in a type of burying culms and a burying part among whole culm affected shoot emergence strongly. Our results suggest that not only methodological condition but also appropriate kind of eco-types must be considered in using reed culms for better cutting. In addition that, sampling timing according to the geological and climatic condition of certain area should be considered for better cutting efficiency as well. We also recommend that the sampling area such as expanding area in a population, burying a middle part of the culm, substratum such as well-ventilated sand and vertical burying method for better cutting efficiency. Lastly, for more enhancement of cutting efficiency of reed culms, potential damages by blight and harmful insects such like aphids should be concerned very carefully.

• The Korean Journal of Financial Management
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• v.27 no.2
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• pp.1-33
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• 2010

This study explores if the higher initial returns and the poorer long-run performance observed in the IPOs markets are associated with the firms offered in the 'hot markets,' and then empirically examines the effect of optimistic investors' sentiment on this phenomenon, particularly in the aspects of both pricing mechanism and the opportunistic behavior of offering firms. We analyzed a total of 432 IPO firms for the years between 2001 and 2005. This analysis finds that the initial returns and long-run under-performances of 'IPOs in the hot market' are significantly higher than those of 'IPOs in the cold market.' This study also finds that the proxy variables for the optimistic investors' sentiment have a positive effect on the initial return and negative effect on the long-run performance. Finally, this research finds no difference of ownership structure, venture capital backed, and financial properties between hot market IPOs and cold market IPOs. R&D expenditure rate and financial qualities of IPOs are higher in the hot market than in the cold market. These results do not support the 'windows of opportunity' hypothesis that low quality firms take advantage of hot market condition for successful IPOs.

• Journal of Korean Neurosurgical Society
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• v.30 no.4
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• pp.472-478
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• 2001

Objectives : The authors present a retrospective analysis of 100 consecutive adult patients harboring craniopharyngiomas who underwent microsurgical resection between 1981 and 1999 to assess the long-term outcome of surgical treatment and to determine the most optimal management strategy. Methods : The extent of surgical removal was divided into four categories ; GTR(gross total removal), RSTR(radical subtotal removal), STR(subtotal removal),and PR(partial removal). The median follow-up period was 50 months(4-198). CT scan and/or MR imaging and hormonal status were evaluated to the last follow-up. Results : Visual disturbance was the most common presentation, which was improved in 42 cases and aggravated in 19 cases following the operation. Hypopituitarism was detected in 56 patients preoperatively, 82 during the immediate postoperative period, and 76 at the last follow-up. Improvement of pituitary function was not observed in any of these patients. Twenty of 100 patients showed recurrence at the mean of 27 months(3 to 196). The median progression-free survival(PFS) time of all patients was 145 months and 5-year PFS rate was 74%. Five-year PFS rate of GTR or RSTR group(71%) was significantly higher than that of STR or PR group(30%)(p=0.01). Postoperative radiation therapy significantly prolonged the PFS from 94 months in non-radiation group to 182 months(p=0.002). However, there was no statistical difference in number of patients who required hormonal replacement therapy between radiation and non-radiation group. Conclusion : Visual disturbance can be improved by early diagnosis and surgical decompression. GTR or RSTR in selected patients is considered a proper surgical strategy. Post-operative radiation therapy for residual tumors must be considered, although the ideal timing of radiation therapy is to be determined.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.545-551
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• 2010

The primary objective of this study was to determine the relationship between fruit quality characteristics and pithiness fruit occurrence for confirming occurrence factors of pithiness tissues in 'Niitaka' pears ($Pyrus$ $pyrifolia$ Nakai). Fruits were harvested 4 times in 1 week intervals from 160 days after full bloom (DAFB) to 181 DAFB. Harvested fruits were separated with the specific gravity by Archimedes laws. Also, with specific gravity level in pear fruit, sugar content, acidity, and texture profile analysis (TPA) were investigated. Final verifiability of pithiness fruit was approved by eye observation at 90 days after storage. Also, in ASS (Alcohol Soluble Solid) and AIS (Alcohol Insoluble Solid), calcium contents were investigated. Although the differences in sugar and organic acid content were not significant in fruits divided by gravity, flesh hardness was depressed in fruits that showed low gravity. These results were more conspicuous in late harvested fruits (at 174 and 181days after full bloom) which showed low gravity, representing less content of AIS content and calcium in ASS and AIS when compared with early harvest fruits. Fruits of lower gravity below 1.0 measured with dipping induced the progression of pithiness symptom up to 76%. Consequently, harvest timing is a more concise factor in pithiness fruit occurrence although those symptom also affected by storage condition. Furthermore, the cause of pithiness fruit occurrence by late harvest is due to the lower cell wall binding calcium.

• Journal of Conservation Science
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• v.33 no.6
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• pp.417-429
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• 2017

This study aimed at the identification of the black coating materials on the pottery surface and manufacturing technique of black burnished pottery excavated from the Pungnaptoseong, Seoul, which is estimated to be royal fortress of Beakje. According to observation of black coated surface and raw materials, potteries can be divided into two groups. The first group potteries have black inner and black surface with well-selected particles. Second group potteries are black in surface only with unevenly selected particles. Each group seems to represent different manufacturing technique in clay selection, color development timing and method. The black burnished pottery contains high values of CaO, $P_2O_5$, L.O.I. and lower content of $Fe_2O_3$ compared with gray pottery excavated from the same site, which indicates plant ashes were used for coloring the surface of pottery in black. According to the result of SEM-EDS mapping of black burnished pottery, carbon was concentrated on pottery surface, while iron was concentrated on the surface of the gray pottery. Based on XRD analysis, firing temperature of the black burnished potteries were fired low temperature range at 700 to $900^{\circ}C$, and that of the gray potteries ranged from $900^{\circ}C$ to $1000^{\circ}C$.