• The korean journal of orthodontics
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• v.38 no.1
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• pp.13-30
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• 2008

Objective: The objective of this study was to evaluate the displacement pattern and the stress distribution of the finite element model 3-D visualization during symphyseal widening according to the osteotomy position, osteotomy type, and distraction device. Methods: The kinds of distraction devices used were tooth-borne type, hybrid type, bone-borne type and tooth-borne type $30^{\circ}$ angulated, and the kinds of osteotomy design were vertical osteotomy line between the central incisors and step osteotomy line through the symphysis. Results: All reference points of the mandible including the condyles were displaced laterally irrespective of the osteotomy position, osteotomy method and distraction device. The anteroposterior or vertical displacements showed small differences between the groups. The widening pattern of the osteotomy line in the tooth-borne type of device was v shaped, and that of bone-borne type was a reverse v shape. However, the pattern in the hybrid type was parallel. The lateral displacement of the mandibular angle by the bone-borne device was more remarkable than the other types of devices. The displacement by the $30^{\circ}$ angulated tooth-borne type was different between the left and right sides in both the transverse and anteroposterior aspects. Conclusion: The design of the distraction devices and osteotomy line can influence the displacement pattern and the stress distribution during mandibular symphyseal distraction osteogenesis procedures.

• Journal of Oral Medicine and Pain
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• v.37 no.2
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• pp.125-133
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• 2012

TMJ Osteoarthritis is a degenerative disease caused by overload on joint tissue, and often accompany with local tenderness on the joint, crepitus by mandibular movement, restriction of mandibular movement, and anterior openbite. In general, panoramic radiography, TMJ panoramic radiography, and transcranial radiography are conducted to diagnose osteoarthritis after clinical examination, however, these radiographic evaluations are limited in detecting minute bony changes of early pathologic lesion. The aim of this pilot study was to evaluate the limitation and usefulness of several TMJ imaging techniques, so we compare the findings from clinical examination, plain film radiographs, tomograph, and bone scan from 81 patients with temporomandibular joint disorder. The proportion of patients showing same findings in plain film radiographs, TMJ tomograph, and bone scan was high, however, it is desirable that clinician should conduct phased imaging examinations according to the clinical findings due to the possibilities of false negative findings in diagnosis of osteoarthritis.

• Imaging Science in Dentistry
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• v.33 no.2
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• pp.79-83
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• 2003

Purpose : To assess the relationship between the direction of the indicating rod of the radiographic stent for ideal prosthetic design and the actual possible path of implant fixture placement when residual ridge resorption is considered. Materials and Methods: The study materials consisted of 326 implant sites (male 214 cases and female 112 cases) from a total of 106 patients (male 65 patients and female 41 patients) who desired implant prostheses. Computed tomography of patients were taken and reformatted using ToothPix/sup (R)/ software. Bony defects, bony sclerosis, the change of the direction of indicating rod, and root proximity of the adjacent teeth were examined on the CT-derived images. Results: The rate of the irregular crestal cortex was relatively high on premolar and molar area of maxilla. Mandibular molar area showed relatively high rate of focal sclerosis on the area of implant fixture insertion. The position of the indicating rods were relatively acceptable on the molar areas of both jaws. However, the position of the indicating rods should be shifted to buccal side with lingual rotation of the apical end on maxillary anterior teeth and premolar area. Conclusion: Clinically determined rod direction and position of the indicating rod for implant placement was not always acceptable for insertion according to the reformatted CT images. The pre-operative treatment plan for implant should be determined carefully, considering the state of the alveolar bone using the reformatted CT images.

• Imaging Science in Dentistry
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• v.33 no.2
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• pp.97-105
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• 2003

Purpose : To evaluate the effect of all-trans-retinoic acid (ATRA) on the radiosensitivity of normal human oral keratinocyte (NHOK). Materials and methods: Relative cell survival fraction including SF2 (survival fraction at 2 Gy) was calculated on the basis of colony formation assay. Data were fitted to the linear-quadratic model to establish the survival curve and calculate α and β values. Using flow cytometry at 1, 2, 3, 4, and 5 days after exposure to 2 and 10 Gy irradiation, cell cycle arrest and apoptosis were analysed. To understand the molecular mechanism of the radiosensitization of ATRA on NHOK, proteins related with apoptosis and cell cycle arrest were investigated by Western blot analysis. Results: Treatment with ATRA resulted in a significant decrease of SF2 value for NHOK from 0.63 to 0.27, and increased α and β value, indicating that ATRA increased radiosensitivity of NHOK. ATRA increased LDH significantly, but increasing irradiation dose decreased LDH, suggesting that the radiosensitizing effect of ATRA is not directly related with increasing cell necrosis by ATRA. ATRA did not induce appotosis but increased G2 arrest after 10 Gy irradiation, implying that the increased radiosensitivity of NHOK may be due to a decrease in mitosis casued by increasing G2 arrest. ATRA inhibited the reduction of p53 at 3 days after l0Gy irradiation and increased p21 at 1 day after 10 Gy irradiation. Further study is required to determine the precise relationship between this effect and the radiosensitizing effect of A TRA. Conclusion: These results suggested that ATRA increase radiosensitivity by inhibiting mitosis caused by increasing G2 arrest.

• Particle and aerosol research
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• v.16 no.1
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• pp.19-30
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• 2020

The organic carbon in the ambient particulate matter (PM) is divided into primary organic carbon (POC) and secondary organic carbon (SOC) by their formation way. To regulate PM effectively, the estimation of the amount of POC and SOC separately is one of important consideration. Since SOC cannot be measured directly, previous studies have evaluated determination of SOC by the EC tracer method. The EC tracer method is a method of estimating the SOC value from calculating the POC by determining (OC/EC)pri which is the ratio of the measured values of OC and EC from the primary combustion source. In this study, three different ways were applied to OC and EC concentrations in PM_2.5 measured at Seoul for determining (OC/EC)pri: 1) the minimum value of OC/EC ratio during the measurement period; 2) regression analysis of OC vs. EC to select the lower 5-20% OC/EC ratio; 3) determining the OC/EC ratio which has lowest correlation coefficient value (R²) between EC and SOC which is reported as minimum R squared method (MRS). Each (OC/EC)pri ratio of three ways are 0.35, 1.22, and 1.77, respectively from the 1 hourly data. We compared the (OC/EC)pri ratio from 1hourly data with 24 hourly data and revealed that (OC/EC)pri estimated from 24 hourly data had twice larger than 1hourly data due to the low time resolution of sampling. We finally confirmed that the most appropriate value of (OC/EC)pri is that calculated by a regression analysis of 1 hourly data and estimated SOC amounts at PM_2.5 of the Seoul atmosphere.

• Journal of Korean Society of Forest Science
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• v.102 no.2
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• pp.189-197
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• 2013

The Cancun Agreements under the United Nations Framework Convention on Climate Change require developing countries aiming to undertake REDD+ activities to develop a national strategy or action plan, addressing the drivers of deforestation and forest degradation, a measurement, reporting and verifying (MRV) system including forest monitoring system, and safeguards to ensure equity and co-benefits for local communities and indigenous peoples, and biodiversity. The Government of Indonesia and the Government of Norway established REDD+ cooperation through signing a 'Letter of Intent' in May, 2010. Indonesia agreed on 'a two year suspension on all new concessions for conversion of peat and natural forest'. In turn, Norway agreed to support Indonesia's REDD+ implementation efforts up to one billion United States dollars. Indonesia's REDD+ national strategy (June, 2012) accepted most of the requests included in the 'Letter of Intent'. The REDD+ national strategy, however, does not reflect requests of the Cancun Agreements which noted identification of the drivers of deforestation and forest degradation and guarantee of real greenhouse gas emissions reductions. Indonesia lays emphasis on Norwegian requests which includes expected financial support rather than the Cancun Agreements which have a weak legally-binding requirements.

• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.5-14
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• 2009

This study is to analyze numerically the spatial behaviors of the solute transport in a spatially correlated variable-aperture fracture under the effective normal stress conditions. Numerical results show that the solute transport in a fracture is strongly affected by the spatial correlation length of apertures and applied effective normal stress. According to increasing spatial correlation length, the mean residence time of solute is decreased and the tortuosity and Peclet number (is a dimensionless number relating the rate of advection of a flow to its rate of diffusion) is also decreased. These results mean that the geometry of the aperture distribution is favorable to the solute transport as the spatial correlation length is increased. However, according to the applied effective normal stress is increased, the mean residence time and tortuosity have a tendency to increase but the Peclet number is decreased. The main reason that the Peclet number is decreased, is that the solute is displaced by one or two channels with relatively higher local flow rate due to the increment of contact areas by increasing effective normal stress. Moreover, based on numerical results of the solute transport in this study, the exponential-type correlation formulae between the mean residence time and the effective normal stress are proposed.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.139-145
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• 2006

Ranula is a mucocele which occurs at the mouth floor and is mostly related to sublingual gland. In other words ranula is definded as a pseudocyst which occurs as the secretion duct of sublingual gland is destructed there as the saliva from the secretion duct flows out and retention in the soft tissue. The cause of ranula is destruction or obstruction of the duct. The clinical findings of ranula is a painless, unilateral bluish transparent swelling around the frenum and shows fluctuation when palpated. Histological finding represent a formation of cavity inside the connective tissue, but a pseudo-cyst can be seen which the wall of the cyst is composed of granulation tissue rather than epithelial cells. The first treatment of ranula can be considered as marsupialization. which induces the inner wall of the Ranula to be a part of oral mucosa. This case report shows a treatment of marsupialization with gauze packing in a young patient representing a clinical finding of characteristic ranula.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.164-171
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• 2015

This study was aimed to retrospectively evaluate the clinical findings and treatments of odontomas in the Korean demographic group. The subject of the present study included 75 odontomas in 74 patients who received treatment from Chonbuk National University Dental Hospital between April 2005 and March 2014. The average age of the subjects were 10.3 years old (range 3 - 23 years old). 42 (56.8%) males and 32 (43.2%) females were in the present study. It was found that compound odontomas were about 4 times more common than complex odontomas. Odontomas equally occurred in both maxillary and mandible. The impaction of permanent teeth (73.3%) was the most common complication of odontomas on adjacent teeth. Most odontomas (96.0%) were surgically removed either to induce spontaneous eruption or to guide orthodontically to occlusion. When the impacted tooth could not be naturally or forcefully erupted to occlusion, it was extracted. Early detection and treatment of odontomas would increase the possible preservation of the impacted tooth by eliminating the source of disturbance. Therefore, this study recommends that periodic radiographic examination from birth until the eruption of the permanent third molar to prevent possible hindrance to the teeth eruption.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.2
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• pp.158-163
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• 2015

General anesthesia (GA) for dental care in handicapped patients is necessary to facilitate the provision of safe, efficient, and effective quality treatment. The aims of this study were to determine the anesthetic characteristics of handicapped patients in need of dental treatment in these day care units, and to establish for plan to provide better services. 325 patients who had outpatient general anesthesia from January 2005 to March 2014 were assessed for this study. Patients' distribution and treatment patterns were examined. The proportion of male patients (202, 62.2%) was higher than female patients (123, 37.8%) and the largest group of patients were 5 to 10 years old (85, 26.2%). The reasons for general anesthesia included mental and physical disabilities (207, 63.7%), behavior management (84, 25.8%), parent needs (14, 4.3%), and so on. Restorative treatment was the most common procedure with the average of 4.2 teeth treated per one patient and 43 (13.2%) patients underwent general anesthesia for dental treatment more than once. To expand and improve access to the dental care of the disabled, improvement of the health care system, enhancement of their training for dental care by professionals, and enlarging caregivers'understanding of the importance of oral care in the early stages are required.