• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.525-530
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• 2005

Maxillary median diastema is the term used when there is spacing between maxillary central incisors. The space between maxillary central incisors are often observed during ugly duckling stage. In most of the cases, as maxillary permanent canines erupt, it gradually disappears. Maxillary median diastema needs to be treated when there is up to 2mm of space between the incisors even after eruption of permanent canines or when there is 3mm of space, at least, before the eruption of the canines. Particulary, for the latter case, orthodontic treatment is recommended because not only the esthetic point of view but also to regain the eruption space for maxillary lateral incisors and canines. The appliance used for orthodontic treatment are removable appliances, using finger spring and etc, and fixed appliances, using rubber elastics and coil spring. If rubber band alone was used to treat median diastema without any other appliance such as band, tube or bracket, it will gradually move downward along the root surface. Then it will destroy the peridontal ligament and causes tooth mobility, extrusion, and avulsion. This report presents cases of damaged tooth due to improper use of rubber band when treating maxillary median diastema.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.130-135
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• 2010

Ectopic eruption is caused by an abnormal direction of eruptive path, most common in maxillary first molar, mandibular lateral incisor, and maxillary canine, and sometimes mandibular first molar. Ectopic eruption of first molar leads to abnormal root resorption of second deciduous molar, which, if left untreated, could cause premature loss of second deciduous molar; mesial tilting and rotation of first permanent molar; lack of space for eruption of second premolar; and occlusal problems. Therefore early treatment is advised when diagnosed as ectopic eruption. Treatment of ectopic eruption in the first permanent molar involves providing proper guidance for the direction of eruption using interproximal wedging and distal tipping methods while preserving second deciduous molar. This case report shows satisfactory results of the ectopic eruption of mandibular first molars in young patients who were treated with Humphrey appliance and Halterman appliance.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.102-108
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• 2010

Impaction is the cessation of eruption process caused by physical obstacles on the eruption pathway, abnormal tooth position, or lack or space. It often occurs in association with supernumerary teeth, odontogenic tumor, or cystic lesions, and ameloblastic fibroma is one of the odontogenic tumors that can cause impaction of teeth. In many cases, ameloblastic fibroma occurs in association with one or more unerupted teeth. The proper management of ameloblastic fibroma is determined between conservative resection or more aggressive block resection, based size and morphologic features of the lesion and age of the patient. This is a case of a 8 year and 6 month old boy whose lower left permanent molar showed eruption disturbance. The impacted tooth was successfully repositioned favorably through surgical exposure and orthodontic traction using a modified halterman appliance. Long term follow-up, longer than 10 years, is planned considering relatively high recurrence rate and possibility of malignant transformation of ameloblastic fibroma, which cause impaction of the lower left permanent molar in this case.

• Journal of the Korean Geographical Society
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• v.51 no.2
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• pp.283-303
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• 2016

The concept of a risk society, which was originally suggested by German sociologist Ulrich Beck, is insufficient to reveal how a certain risk materially and discursively unfolds on the ground and how its various dynamics are recognised by diverse actors because of the concept's spatial insensitivity. As an alternative approach, this paper introduces the concept of the riskscape, which was suggested by German geographer Detlef $M{\ddot{u}}ller$-Mahn, and analyses this concept in the context of the East Asian developmental state. It is meaningful that the East Asian developmental state thesis has strongly promoted the role of the state in stimulating national economic development in underdeveloped countries. However, it should also be noted that an active state role in encouraging modernisation and economic growth within a very short time produces consequences of what Beck calls 'manufactured risks', such as nuclear power plants. Therefore, it is essential to analyse the state in comprehending modernisation and the risk society in East Asia. More specifically, using the case of the location policy for nuclear power facilities, this article reveals how dominant social forces acting in and through the state constructed a national riskscape that minimises the gravity of local risks while prioritising the economic value of the national economy over local risks to produce rapid modernisation. Additionally, it is argued that a dominant national riskscape may become weak from competing with different riskscapes that are constructed based on contingency factors (e.g., political democratisation or a natural disaster). Based on these analyses, the article emphasises that interdisciplinary research using the concept of the riskscape is required to better explain the risks in East Asia.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.18-25
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• 2013

It may occur health hazards or death by suffocation or acute poisoning in case of oxygen deficiency in ambient or exposure to harmful gas. As a part of accident prevention, we studied the change of activity and lethal dose by changing the concentration of several hazardous gas with inhalation exposure chamber and laboratory animals. We investigated the lethality and motility change during either the 4 hrs whole body exposure to oxygen, nitrogen, toluene, $H_2S$, CO and 48 recovery. As results, it is estimated that 5% oxygen concentration as lethal concentration and 5.5% as $LC_{50}$ (rat, 4 hrs) with statistics for dose-response. The results of lethality in oxygen deficient condition (approximately 6%), the lethalities were 40%, 20% with 20 ppm $H_2S$, 600 ppm CO respectively, and was not increased the lethality with 8% CO. Thus, it was confirmed that the $H_2S$, CO had influence to lethal dose, while toluene had low fluence.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.93-101
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• 2017

The shortage of parking lots in aged apartment complexes built from the 1980s to the mid 1990s is serious. When we look at the case of parking lot expansion in the aged apartment complexes, the method of extending the underground parking lot vertically occupies the majority. It is very important to secure the structural safety of the foundations when the existing buildings are enlarged. In the case of underground vertical work, the work space should be narrow, so that a method with excellent safety, environmental and construction properties should be applied. Urban construction is also required to use construction methods and equipment with low noise and vibration. This study analyzed the factors influencing the selection of the foundation reinforcement method for the expansion of the underground parking lot and Weights of influence factors were calculated. The purpose of this study was to analyze the applicability of the foundation reinforcement method. Factors influencing the applicability of the foundation reinforcement method were derived through expert interviews and The AHP technique was used to calculate the weight of the influencing factors. It was evaluated by experts on the applicability of the foundation reinforcement method. It conducted a case study on two types of underground parking lot expansion type and compared the applicability of the foundation reinforcement method.

• Journal of Information Management
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• v.39 no.2
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• pp.131-161
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• 2008

Recently electronic journal articles prevail throughout researchers because of the development of internet and electronic publishing technology. It is caused by limited collection development budget, lack of physical storage space for printed journals in libraries, and the user convenience of web services. But from the view of ownership, electronic journals can be unfavorable to information users or libraries who cannot have the permanent right to access all the subscribed journals. Actually the libraries only have right to access journals for subscription periods in using electronic journals. So the users and libraries are willing to purchase printed journals in spite of high cost. As an basis for collaborative collection development and sharing preservation of Korean libraries for the foreign journals, the data analysis is carried out for the journals collection in terms of regional distribution, overlapping status, and journal subject. And the considerables are discussed for collaborative strategic collection development, which means the reduction of overlapped subscription and maximization of utilization in a national standpoint.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.443-449
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• 2017

The imbalance of air supply and the exhaust on subway platforms has led to the installation of platform screen doors in underground subway stations. This imbalance causes the accumulation of pollutants on the platform and loss of comfort due to the lack of ventilation. In this study, a floor exhaust system was optimized using computational fluid dynamics (CFD) and an optimization program. The optimized floor exhaust system was manufactured and tested experimentally to evaluate the particle collection efficiency. CFX 17.0 and HEEDS were used to analyze the flow field and optimize the principal dimensions of the exhaust system. As a result of the three-step optimization, the optimized floor exhaust system had a total height of 1.78 m, pressure drop of 430 Pa, and particle collection capability of 61%. A fine dust particle collection experiment was conducted using a floor exhaust system that was manufactured at full scale based on the optimized design. The experiment indicated about 65% particle collection efficiency. Therefore, the optimized design can be applied to subway platforms to draw in exhaust air and remove particulate matter at the same time.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.4
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• pp.35-44
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• 2016

Two primary tools to study park use are surveys and direct observation. Existing methods, however, are limited in terms of considerable costs in both time and money and the personal bias of respondents or observers. These limitations result in a lack of efficient, reliable, and affordable tools to investigate park use. This study explores the reliability and usability of unmanned aerial vehicles(UAVs) to explore park use in urban parks in Busan metropolitan city. By comparing with a systematic observation tool, SOPARC(System for Observing Play and Recreation in Communities), this study finds that the number of park users observed by two different techniques are highly correlated and not significantly different with each other. In addition, both methods show a high level of test-retest reliability. Comparing to existing methods, the UAV-using observation tool could cover larger target areas and is suitable to count park users in a more reliable and efficient way and map their use patterns, although it is weak in collecting detailed user information and surveying under poor conditions such as rain. Thus, the UAV method could complement direct observation. This study suggests practical implications of a UAV method to study park use.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.529-538
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• 2015

This paper was intended to empirically identify problems with recreational sea fishing park facilities installed to help reinvigorate local economy of fishing villages in order to mitigate shortage of fishing facilities amid an increase in sea fishers and spur evolution of sea fishing into a marine leisure activity, on which basis this researcher presented direction for facility planning which is deemed necessary to map out the plan for sea fishing parks, along with measures designed to improve sea fishing park facilities. To analyze the problems related to sea fishing park facilities, we conducted a survey on facility operations involving 9 sea fishing parks and 2 sea ranches and had an investigative interview with facility manager. Moreover, a survey was conducted of fishers in 25 sea fishing places, including sea fishing park, fishing experience village, etc., in order to investigate their demand for facilities. The results of survey suggested that there was a significant demand for expansion of amenities such as safety facilities, toilets, lounge facilities, etc., which can accommodate the increase in the number of people fishing with family. Furthermore, the results showed that there was a huge demand for introduction of facilities aiding leisure activities in addition to facilities for fishing activities including education facilities such as fishing site at the corner exclusive for beginners, experiential facilities, camping site, seaside park, promenade, etc. Thus, sea fishing park should be the complex leisure space with a focus on fishing activities and requires facility configuration and facility planning suited to activity requirements within fishing park.