• The Journal of the Korean dental association
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• v.53 no.12
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• pp.967-974
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• 2015

Purpose: This study was performed to investigate the characteristics of mandibular incisive canal (MIC) in Korean population. Materials and methods: A total of 97 subjects (60 males and 37 females) who underwent cone-beam computed tomography were included in the study. The anatomic features of MIC was assessed according to gender. Length, diameter and distance to inferior, lingual and buccal border were measured at the origin and the terminal. Also the distribution of MIC at each tooth position was evaluated. Results: Of 97 patients included, 75(77.3%) presented bilateral MIC and 13(13.4%) presented unilateral MIC. Of 194 hamimandibles, MIC was detected in 102(85%) sites in male and 61(82.4%) sites in female. Gender and side showed no statistically significant differences in detectability. The length, diameter and distance to adjacent structures were bigger in male than in female except the distance to lingual border. MIC travelled anteriorly in a slightly downward and lingual direction and usually terminated between the first premolar and the canine. On cross-sectional view, MIC showed individually scattered distribution both buccolingually and superoinferiorly. Conclusion: MIC is well detected with cone-beam computed tomography. Considered that the length and the location of MIC has large variations between individuals, its localization using cone-beam CT is highly recommended before performing surgical procedures such as implant placement and bone harvesting.

• Korean Journal of Radiology
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• v.2 no.1
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• pp.42-51
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• 2001

Because the tongue is superficially located and the initial manifestation of most diseases occurring there is mucosal change, lingual lesionscan be easily accessed and diagnosed without imaging analysis. Some lingual neoplasms, however, may manifest as a submucosal bulge and be located in a deep portion of the tongue, such as its base; their true characteristics and extent may be recognized only on cross-sectional images such as those obtained by CT or MRI. Some uncommon tongue neoplasms may have characteristic radiologic features, thus permitting quite specific radiologic diagnosis. Lipomas typically manifest at both CT and MR imaging as homogeneous nonenhancing lesions. Relative to subcutaneous fat they are isoattenuating on CT images, and all MR sequences show them as isointense. Due to the paramagnetic properties of melanin, metastases from melanotic melanoma usually demonstrate high signal intensity on T1-weighted MR images and low signal intensity on T2-weighted images. Although the radiologic findings for other submucosal neoplasms are nonspecific, CT and MR imaging can play an important role in the diagnostic work-up of these unusual tumors. Delineation of the extent of the tumor, and recognition and understanding of the spectrum of imaging and the pathologic features of these lesions, often help narrow the differential diagnosis.

• Journal of the Korean Society for Library and Information Science
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• v.43 no.1
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• pp.313-332
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• 2009

Cross-language text categorization(CLTC) can classify documents automatically using training set from other language. In this study, collections appropriated for CLTC were extracted from KTSET. Classification performance of various CLTC methods were compared by SVM classifier using machine translation. Results showed that the classification performance in the order of poly-lingual training method, training-set translation and test-set translation. However, training-set translation could be regarded as the most useful method among CLTC, because it was efficient for machine translation and easily adapted to general environment. On the other hand, low performance was shown to be due to the feature reduction or features with no subject characteristics, which occurred in the process of machine translation of CLTC.

• Imaging Science in Dentistry
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• v.37 no.3
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• pp.133-138
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• 2007

Purpose: The purpose of this study was to evaluate the morphologic features of posterior edentulous mandible for Korean patients using cross-sectional CT images. Materials and Methods: Computed tomographic cross-sectional views taken in 2004 and 2005 at Seoul National University Dental Hospital were analyzed by an oral and maxillofacial radiologist. Four indices were measured to meet the purpose of this study: 1) the horizontal distance between the alveolar crest and mandibular canal (Type), 2) the angle of the mandibular long axis (Angle), 3) the bucco-lingual location of mandibular canal, and 4) the depth of the submandibular fossa. The averages and standard deviations of the measurements were compared according to the location (the first and second molar area) and sex of the patients. Results: Statistically significant difference was found in Type, Angle, and submandibular fossa depth between the first and second molar area (p<0.05). However, there was no significant difference between men and women in any of the measured indices. Most of the mandibular canals were located in lingual side of posterior mandible. Conclusion: More care should be taken when an implant is installed on the mandibular second molar area.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.3
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• pp.215-222
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• 2014

Purpose: The aim of this study was to investigate differences between the morphology of the mandibular symphysis and four facial skeletal types. Materials and Methods: 40 cone-beam computed tomographies were selected and classified in to 4 groups according to their vertical and anterior-posterior skeletal patterns. The bone volume ($mm^3$) of the symphysis, the cross sectional area corresponding to the 4 mandibular incisors' axis: the cross sectional area of total bone ($mm^2$), the area of the cancellous bone ($mm^2$) and the thickness (mm) of labial and lingual alveolar bone at 2 mm, 3 mm under the cemento-enamel junction (CEJ) were measured. General linear model (GLM), Kruskal-Wallis test and Tukey honestly significant difference (HSD) test were subsequently used for statistical analysis. Results: The lingual cortical bone thickness of the lateral incisors at 2, 3 mm under CEJ was greater in the Class I low angle group than the other 3 groups (P < 0.05). There were no statistically significant differences in the volume of the mandibular incisor bony support, cross-sectional area of total bone and cancellous bone at the mandibular incisor' axis. Conclusion: Patients in Class I, low angle group have a thicker lingual mandibular symphysis than Class I, high angle patients.

• Imaging Science in Dentistry
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• v.33 no.1
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• pp.43-49
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• 2003

Purpose : To evaluate the differences in bone height, bone width, and visibility of posterior spiral tomographic images according to various exposure directions, image layer thickness, and inclination of the mandibular inferior border. Materials and Methods: Six partially and completely edentulous dry mandibles were radiographed using Scanora spiral tomography. Spiral tomography was performed at different exposure directions (dentotangential and maxillotangential projection), image layer thicknesses (2 mm, 4 mm and 8 mm), and at various inclinations to the mandibular border (+ 100, 00 and -10°). The bone height and width was measured using selected tomographic images. The visibility of mandibular canal, crestal bone, and buccal and lingual surfaces were graded as 0, 1, or 2. Results : The bone width at the maxillo-tangential projection was wider than at the dento-tangential projection (p < 0.05). The visibility of buccal and lingual surface at the maxillo-tangential projection was higher than at the dento-tangential projection (p<0.05). Thinner image layer thicknesses resulted in greater visibility of buccal and lingual surfaces (p < 0.05). Bone height was greatest in the -10° group, and at the same time the bone width of the same group was the narrowest (p < 0.05). The visibility of alveolar crest and buccal surface of the + 10° group was the highest, while the visibility of the mandibular canal was greatest in the 00 group. Conclusion: When spiral tomography is performed at the mandibular posterior portion for visualization prior to implant surgery, it is important that the inferior border of mandible be positioned as parallel as possible to the floor. A greater improvement of visibility can be achieved by maintaining a thin image layer thickness when performing spiral tomography.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.361-362
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• 2022

As the importance of maritime communication in a cross-cultural onboard working environment grows, the importance of developing systematic supporting aids both for learning and teaching maritime English has been emphasized. Given that English communication proficiency is one of the most critical factors in determining a seafarer's competency, a systemic supporting system for enhancing maritime English communication capabilities is essential not only for them to professionally carry out and conduct assigned duties onboard, but also for them to navigate success in their lives through increased labour mobility both at sea and onshore. The APEC Seafarers Excellence Network initiates the production of Maritime English Communication Packages for seafarers in APEC regions, under the leadership of the Republic of Korea. This paper introduces the design of APEC SEN Maritime English Communication Packages, which include textbooks, audio-lingual materials, online/mobile life-long learning platform and testing aids, ultimately for upand re-skilling of seafarers to increase their employability, mobility and preparedness for the future shipping industry where globalisation is expected to further accelerate.

• Journal of Periodontal and Implant Science
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• v.41 no.3
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• pp.131-134
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• 2011

Purpose: To test the plaque-removal efficacy of a single-tufted toothbrush on the posterior molars compared with a flat-trimmed toothbrush. Methods: Forty-nine subjects were selected. Professional instruction and written brushing instructions were given. After thorough supra-gingival scaling and polishing, all subjects were asked to abstain from oral hygiene procedures for 24 hours prior to the first experiment. The subjects were randomized to a treatment sequence. The modified Quigley and Hein plaque index was recorded pre- and post-tooth brushing, at 6 surfaces of the posterior molars. After a wash-out period, all the remaining plaque was removed professionally. Twenty-four hours of brushing abstinence was again performed. The plaque index was recorded pre- and post-tooth brushing after the subjects were given the second toothbrush in the cross-over sequence. Results: The percentage reductions in plaque scores achieved with the single-tufted brushes were significantly higher than those of the flat-trimmed brush at the maxillary buccal interproximal, marginal and mandibular lingual interproximal site. The other locations showed no significant difference. Conclusions: The results of the present study implied that the single-tufted brush could be an effective tool for the removal of plaque at some, but not all, sites of the posterior molars.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.161-165
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• 2015

Three-dimensional (3D) reconstruction of cone-beam computed tomography (CBCT) scans appears to be a valuable method for assessing pulp canal configuration. The aim of this report is to describe endodontic treatment of a mandibular second premolar with aberrant pulp canal morphology detected by CBCT and confirmed by 3D modeling. An accessory canal was suspected during endodontic treatment of the mandibular left second premolar in a 21 year old woman with a chief complaint of pulsating pain. Axial cross-sectional CBCT scans revealed that the pulp canal divided into mesiobuccal, lingual, and buccal canals in the middle third and ended as four separate foramina. 3D modeling confirmed the anomalous configuration of the fused root with a deep lingual groove. Endodontic treatment of the tooth was completed in two appointments. The root canals were obturated using lateral compaction of gutta-percha and root canal sealer. The tooth remained asymptomatic and did not develop periapical pathology until 12 months postoperatively. CBCT and 3D modeling enable preoperative evaluation of aberrant root canal systems and facilitate endodontic treatment.

• Korean Journal of Radiology
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• v.2 no.1
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• pp.37-41
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• 2001

Because the tongue is superficially located and the intial manifestation of most diseases occurring there is mucosal change, lingual these lesions can be easily accessed and diagnosed without imaging analysis. Most congenital lesions of the tongue, however, can manifest as a submucosal bulge and be located in a deep portion of that organ such as its base; their true characteristics and extent may be recognized only on cross-sectional images such as those obtained by CT or MRI. In addition, because it is usually difficult to differentiate congenital lesions from other submucosal neoplasms on the basis of imaging findings alone, clinical history and physical examination should always be taken into consideration when interpretating CT and MR images of the tongue. Although the radiologic findings for congenital lesions are nonspecific, CT and MR imaging can play an important role in the diagnostic work-up of these unusual lesions. Delineation of the extent of the tumor, and recognition and understanding of the spectrum of imaging and the pathologic features of these lesions, often help narrow the differential diagnosis.