• The korean journal of orthodontics
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• v.41 no.5
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• pp.324-336
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• 2011

Objective: The aim of this study was to conduct three-dimensional finite element analysis of individual tooth displacement and stress distribution when a posterior retraction force of 200 g was applied at different positions of the retraction hook on the transpalatal arch (TPA) of a molar, and over different lengths of the lever arm on the maxillary anterior teeth in lingual orthodontics. Methods: A three-dimensional finite element model, including the entire upper dentition, periodontal ligaments, and alveolar bones, was constructed on the basis of a sample (Nissan Dental Product, Kyoto, Japan) survey of Asian adults. Individual movement of the incisal edge and root apex was estimated along the x-, y-, and z-coordinates to analyze tooth displacement and von Mises stress distribution. Results: When the length of the lever arm was 15 mm and 20 mm, the incisal edge and root apex of the anterior teeth was displaced lingually, with a maximum lingual displacement at the lever arm length of 20 mm. When the posterior retraction hook was on the root apex, the molars showed distal displacement. When the length of the lever arm was 20 mm, anterior extrusion was reduced and the crown of the canine displaced toward the buccal side, in which case, the retraction hook was on the edge, rather than at the center, of the TPA. Conclusions: The results of the analysis showed that when 6 anterior teeth were retracted posteriorly, lateral displacement of the canine and lingual displacement of the incisal edge and root apex of the anterior teeth occur without the extrusion of the anterior segment when the length of the lever arm is longer, and the posterior retraction hook is in the midpalatal area.

• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.423-431
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• 2000

Bone remodeling is a complex process regulated by various mediators. Cytokines are known to be associated with the mechanically induced response in orthodontic tooth movement. In particular, IL-$1\beta$ stimulates bone resorption and induces osteoclast proliferation. The purpose of this study was to identify and quantify IL-$1\beta$ in human gingival crevicular fluid(GCF), and to investigate the changes in its level during orthodontic tooth movement. Twelve patients(mean age of 19.2 years) were used as the subjects. An upper canine of each patient haying treatment lot distal movements served as the experimental tooth, whereas the contralateral was used as the control. The GCF of compression and tension side of the experimental teeth and the GCF of mesial side of control teeth was taken from the each subject immediately before activation, and at 1, 24, and 168 hr after initiation tooth movement. IL-$1\beta$ amount was detected by ELISA. The concentration of IL-$1\beta$ was higher in experimental group than in the control group after treatment. Its level was elevated after initiation of tooth movement and it was the highest level at 24 hr in compression side of experimental group. But there was no significant change in control group. The results indicate that the change in IL-$1\beta$ level in GCF is associated with orthodontic tooth movement.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.13 no.1
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• pp.117-127
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• 1991

When open reduction of maxilla fractures is postponed due to concurrent life-threatening injuries, delayed union may result with malunion or nonunion. If delayed malunion is occurred, significant facial deformity may result, including a dished-out face, irregular retromaxillism with Angle's class III malocclusion, open anterior bite, nasal collapse, telecanthus and malar flattening. The treatment planning for this problem includes cephalometric evaluation anterior and lateral tomograms, dental casts, orthodontic planning, dental planning and use of impression tray to rupture the fibrous tissue casts, orthodontic planning, dental planning and use of impression tray to rupture the fibrous tissue attachment at the fracture site. In this paper, one case presented a 58-year-old female patient with maxilla retrusion after comminuted fracture, who was treated with orthodontic methods of maxillary protraction headgear and Plaster headcap, whereas the other two cases were about male patients who were treated principally with surgically open reduction or Le Fort I-controlled transverse osteotomy with iliac bone graft.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.2
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• pp.139-145
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• 2017

Recently, gusts, typhoon and tsunamis have been occurring more frequently around the world. In such an emergency situation, a moored vessel can be used to predict and analyze other vessel behavior, but if the mooring system is destroyed, marine casualties can occur. Therefore, it is necessary to determine quantitatively whether a vessel should be kept in the harbour or evacuate. In this study, moored ship safety in an exclusive wharf according to swell effects on motion and mooring load have been investigated using numerical simulations. The maximum tension exerted on mooring lines exceeded the Safety Working Load for intervals 12 and 15 seconds. The maximum bollard force also exceeded 35 tons (allowable force) in all evaluation cases. The surge motion criteria result for safe working conditions exceeded 3 meters more than the wave period 12 seconds with a wind speed of 25 knots. As a result, a risk rating matrix (risk category- very high risk, high risk and moderate risk) was developed with reference to major external forces such as wind force, wave height and wave periods to provide criteria for determining the control of capabilities of mooring systems to prevent accidents.

• Journal of Oral Medicine and Pain
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• v.32 no.3
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• pp.283-292
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• 2007

In several treatment modalities for snoring and obstructive sleep apnea (OSA), oral appliances mainly including mandibular advancement appliance (MAA) and tongue retaining device (TRD) are recognized as a non-invasive, reversible alternative with favorable results. Tongue bulb is a major component of TRD which prevents the tongue from approaching the posterior wall of the pharynx and can be combined with MAA. Determination of tongue bulb size for the patient is important for therapeutic effect, but frequently needs time-consuming work. For effective fabrication and standardization of tongue bulbs, this study aimed to categorize tongue bulb size for healthy young men and to examine its relation with maximum retention force and with physical parameters including tongue-related variables. 36 non-snoring, asymptomatic young men with normal occlusion were voluntarily participated in this study (mean age: $24.47{\pm}2.58$ years). Experimental procedures consisted of prefabrication of tongue bulb set (20 types with a width of 27-36mm and thickness of 8 and 10 mm), determination of tongue bulb size and the maximum retention force for each subject, and measurement of physical parameters including body mass index (BMI), neck circumference and width, thickness and length of tongue. This study showed that there was significant difference of retention force among the bulb size-related groups both in upright and supine position (p<0.05) and that retention force increased with bulb size. Correlation of tongue bulb size with physical parameters was not clearly verified and there was no significant difference in retention force between upright and supine positions. Based on our results, it can be suggested that retention force relates with tongue bulb size, ultimately with tongue volume. A further study needs to be performed in the patients with snoring and OSA.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.261-268
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• 2014

The route of Korea and China situates stable shipping market by the agreement on maritime transport between two countries. Epecially, the Car-ferry shipping market between Korea and China is growing up the world's largest markets in this situation. But, the rapid growth of markets have the possibility of imbalance between supply and demand. In addition that heavy competition can be arisen. The aim of this study is to analyze the ways to reinforce competitiveness of Car-ferry shipping companies(CFSCs) between Korea and China routes through suggesting importance weights of service factors. Firstly, evaluating service factors of CFSCs between Korea and China routes are selected by reviewing literatures and Delphi method. Secondly, importance weights of service factors are calculated using Fuzzy method. As a result, Shipper and CFSCs between Korea and China routes select 'agility of loading and unloading', 'agility of customs', and 'punctuality of transportation' as the most important factors. On the other hand, the two groups are shown the perception gaps on the factors such as 'reasonable shipping cost', 'voyage speed', 'multimodal transportation', and 'professionality of manpower'. The implication of this study is that Government of Korea and China Have to cooperate agreement for mutual drive towed trailer and customs to speedy transportation.

• Journal of KIISE:Software and Applications
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• v.37 no.12
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• pp.909-918
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• 2010

To analyze the national competitiveness of Korea leads to the conclusion that global high-tech enterprises have been playing leading and pulling roles in making Korea in line with advanced countries even though the country is lacking in various natural resources. The characteristics of these companies above are as follows; Firstly, these enterprises continue to accumulate core technologies and know-how with highly competent human resources and well-organized management. Secondly, they are well structured and equipped with information technology infrastructures which are, for example, ERP, SCM, CRM, and PLM. Among them PLM is considered to be the principal core information technology infra in manufacturing industry. The urgent task of manufacturing industry recently is to develop new products to accept various needs of consumers, and to launch the products in time to market, which requires the manufactures to be equipped with product development infra and system to upgrade product fulfillment and mass production system in a short period. The introduction of PLM System is a solution of core strategy as a manufacturer for collaboration, global development, reengineering of manufacturing system, the innovation and efficiency of manufacturing process, and product quality improvement. The purpose of this study is to analyze the success factors of introducing PLM System and its practicing effectiveness. And the results of empirical study are as follows; (1) Technical success factors positively impact system quality and user satisfaction, (2) Organizational success factors positively impact system quality, but does not impact user satisfaction, (3) Environmental success factors positively impact system quality and user satisfaction, (4) System quality positively impacts user satisfaction, (5) User satisfaction positively impacts the effectiveness of implementing PLM systems, but system quality does not impact it.