• Journal of the Korean earth science society
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• v.32 no.6
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• pp.613-628
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• 2011

Restoration, prediction and noise analysis of geomagnetic data measured in the Korean Peninsula were performed. Restoration methods based on an optimized principal component analysis (PCA) and the geostatistical kriging approach were proposed, and its effectiveness was also interpreted. The PCA-based method seemed to be effective to restore the periodical signals and the geostatistical approach was stable to fill the gaps of measurements. To analyze the noise level for each observatory, the geomagnetic time-series was plotted by scattergram which reflects the spatial variation, using data observed during same period. The scattergram showed that the observation made at Cheongyang seemed to have better quality in spatial continuity and stability, and the restoration result was also better than that of Icheon site. For the restoration, both of the methods, geostatistical and optimizaed PCA, showed stable result when the missing of observation was within 20 points. However, in case of more missing observations than 20 points and prediction problem, the optimized PCA seemed to be closer to the real observation considering the frequency-domain characteristics. The prediction using the optimized PCA seems to be plausible for one day of period for interpretation.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.1
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• pp.80-89
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• 2001

The objective of this study was to introduce the current status and development strategy for the environmental restoration of stream side in Japan, and to consider the methodology which could be effectively applied to the environmental restoration of stream side in Korea. 1. We should establish a new paradigm of forest conservation and erosion control which can emphasize the restoration of the stream side ecosystem and reduce soil movement in the areas. Also, in the past, the objective of forest conservation and erosion control was to fix soil by constructing permanent structures. The direction of future forest conservation and erosion control needs to be new forest conservation and erosion control technology to prevent large scale soil movement but allow small scale soil movement to conserve sound ecosystem and biotic habitats. 2. In the past, the goal of forest conservation and erosion control planning was to fix the amount of soil movement by constructing permanent facilities. Forest conservation and erosion control planning in the future needs to change the techniques which could prevent soil movement from large scale of soil disasters, but allow soil movement effectively to a small and middle scale's soil movement. Also, it is considered to change erosion control dams from non passing type to passing type. 3. In the point of ecological conservation aspects, we should evaluate the effects of new forest conservation and erosion control methods which are emphasized on the restoration of the stream side ecosystem. Also, forest conservation and erosion control construction projects for restoring stream and river ecosystem should be planned for perfectly restorating their ecosystems by the way of sustainable maintenance and management. 4. The restoration direction of stream and river ecosystems needs to be restoring the diversity of small geographies such as waterway, shoal and puddles rather than flattening stream bed. And the restoration of the stream side ecosystem should provide continuity of the stream side environment which allows desirable biological habitats, and environmentally sound facilities to harmonize with the environment.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.216-221
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• 2000

Mucoceles and Ranulas are mucous retention phenomena, ie, they develop from the extravasation or retention of mucous after trauma to the sublingual gland or one of the minor salivary glands. Mucoceles are chronic in nature, and local surgical excision is necessary. To minimize the chance for recurrence, the underlying feeder glands should be removed in continuity with the mucocele. Ranula is a term used for mucoceles that occur in the floor of the mouth Treatment consists of marsupialization and/or removal of the feeding sublingual gland. Marsupialization entails removal of the roof of the intraoral lesion. However this procedure is often unsuccessful. Some prefer initially to excise the entire sublingual gland. This case report presents two cases. one case was developed on lower lip and treated by marsupialization. There was no recurrence during follow up period.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.8-14
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• 2019

A drop structure, one of the representative river-crossing structures, is constructed to stabilize a riverbed. On the other hand, the structure interrupts the continuity of the river and causes the destruction of the hydro-ecological environment. Therefore, laboratory experiments of a natural type of drop structure with low differences were performed, and the empirical formula of a local scour hole is proposed. Four experimental flow rates were tested for various types of the drop structure models with 28 test cases. Based on the scour test, it was confirmed that the maximum scour depth occurs rather than the result of applying the previously proposed scour depth formulae. Correlation analysis of the major factors of scour hole at the downstream of the drop structure revealed a strong correlation between the upstream flow characteristics, drop structure height, and total crossing length of the drop model. In addition, the depth and length estimation formula of the maximum scour hole were proposed using the dimensionless variables and validated. In the future, it is also expected that more accurate scour prediction and calculation can be derived by conducting experimental studies and numerical analysis considering the various bed materials and flow conditions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.194-204
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• 2007

A numerical analysis and hydraulic experiments were undertaken to investigate the head loss occurring when a flow passes through vertical perforated walls. The numerical analysis applied continuity, momentum and energy equations to the control volumes that were set near the perforated wall. Non-dimensional equations were then derived to calculate both upstream depth and head loss for the given values of downstream depth and velocity. The hydraulic experiments were performed with several single and triple perforated plates varying their opening ratios and intervals. The numerical results with the single plates were compared with the experimental results, and it was shown that the contraction coefficient of the vertical line jet formed after the perforated plates relies on downstream Froude number as well as opening ratio. Based on the experimental results, empirical formulas were formulated. Finally, the formulas were applied to the triple plates sequentially from downstream side to upstream side, and it was found that in general the predicted values nicely agreed with the experimental results.

• Journal of Korea Water Resources Association
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• v.43 no.2
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• pp.139-151
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• 2010

A quasi-two-dimensional unsteady flow model was developed for simulating the flow in a river system including artificial storage pockets with side weirs. It is a multiply-connected network which combines channels and storage pockets. The channel flow is described by the one-dimensional Saint Venant equations, and the weir overflow flow by the cell continuity and stage-discharge relations. The model was applied to the Imjin river system including six artificial storage pockets. Design flood peak reduction due to storage pockets is not sensitive to the side weir discharge coefficient. Storage pockets downstream are less effective than upstream ones in reducing peak stage as the backwater effect becomes more dominant. Simulated flood control effect is highly sensitive to the roughness coefficient. The uncertainty due to the roughness coefficient increases as the weir crest elevation gets higher. Because the best design alternative varies with the roughness coefficient, proper estimation of it is essential to the design of side weirs. Moreover, uncertainty of the estimation needs to be considered in the design process.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.257-264
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• 2017

The PC (Precast Concrete) construction method is a technique where concrete members that have been produced in a plant are constructed on site. Thus, continuity and secure integration of a structure that can be obtained by connecting rebars at splicing joint for PC members are the main areas of concern for this method. To evaluate the splicing and bonding performance according to application of a splice sleeve for connecting rebar in this research study, the diameter of rebar, development length, grouting strength etc. were set as variables. The performance and stiffness of splicing according to the development length of grout strength were measured and evaluated. In addition, by conducting comparative analysis on each of the variables, the factors that affected the splice sleeve for connecting rebar were discussed. The results confirmed that the strength and stiffness of the splice sleeve for connecting rebar were significantly affected by the development length while the increase in performance according to grout strength was not as significant.

• Journal of dental hygiene science
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• v.18 no.2
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• pp.113-123
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• 2018

The purpose of this study to review clinicians and educators on required communication education factors of dental hygienists using qualitative research by focus group interview. The participants were dentists, dental hygienists and professors. A questionnaire was developed on communication education to collect data. The collated data derived concepts related to communication education. After transferring the data, were analyzed by open coding and axial coding using computer-aided qualitative data analysis software. Focus group emphasized that higher education on communication should be preceded before they are put into the clinical field. However, the dental hygienist emphasized experiential education in the clinical field, the professor emphasized additional education for continuity of communication education even after graduation. Besides, focus group emphasized role play, and the professor required that the standardization of the dental communication training courses objectives and role play modules and the education environment infrastructure should be established to implement communication education efficiently. The categories of communication education stated in the focus group were time and method for the dental communication training courses, dental communication training courses standardization and educational environment, of evaluation of communication competency, of perception of the dental communication training courses. This study identified the communication education development to conform with the needs of the clinical field strengthen and cultivate communication competency dental hygienists based on factors of communication education emphasized in focus groups.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.685-688
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• 2016

SBAS(Satellite Based Augmentation System) broadcasts the correction message based on satellite communication to improve the positioning accuracy of GNSS user. For this reason, SBAS is actively being utilized on navigation part. To apply SBAS to navigation part, it should satisfy not only accuracy but also integrity, continuity, availability, coverage requirements and so on. Since SBAS reference station is the base infrastructure of SBAS, it is the main factor to determine the environment, position, and geometry of reference stations to achieve SBAS service performance. Therefore, a site environmental analysis should be performed prior to the selection of SBAS reference station. In this paper, it performs the environmental analysis of NDGPS(Nationwide Differential GPS) reference station sites on the premise that SBAS reference station will be co-operated in the same site of NDGPS operated by MOF(Ministry of Oceans and Fisheries). The environmental analysis is conducted as carrying out the visibility analysis of GPS satellite and interference analysis. This paper also presents the brief procedures and requirements for site survey of SBAS reference station.

• Korean journal of applied entomology
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• v.54 no.3
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• pp.233-245
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• 2015

The Baekdudaegan Mountain Range is home to a wide range of organisms inhabiting the Korean Peninsula. This study monitored butterfly communities of Guryongryeong (Myeonggye-ri) and Gojingkyeong (Seobyeok-ri) from April to September in 2013 to 2014, and the results were compared with previous data to determine changes in their distribution. We found 1,098 butterflies of 65 different species in Myeonggye-ri, and 1,161 butterflies of 63 different species in Seobyeok-ri. Comparing the two regions, 13 species appeared only in Seobyeok-ri and 15 species appeared only in Myeonggae-ri. When species were ranked according to number of individuals, the top species three species were as follows: Artogeia melete (127, 11.6%), A. napi (100, 9.1%), and Papilio maackii (90, 8.2%) in Myeonggye-ri; and Libythea celtis (146, 12.6%), A. napi (134, 11.5%), and Polygonia c-aureum (69, 5.9%) in Seobyeok-ri. The number of species with fewer than three individuals each was 24 in Myeonggye-ri and 23 in Seobyeok-ri, accounting for a high percentage among the total number of species. The similarities between the two regions were relatively high, and many of the butterflies are on the Red List of Korea. Compared with previous distribution data, there were no significant changes. This consistency indicates that the butterflies of the Baekdudaegan Mountain Range have been conserved well, and therefore the continuity in the Baekdudaegan Mountain Range is necessary to keep in the big picture.