• Journal of Korean Neurosurgical Society
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• v.30 no.2
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• pp.186-193
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• 2001

Objectives : Trigeminal neuralgia and hemifacial spasm are caused by vascular compression of the REZ(root entry or exit zone) of the 5th and the 7th cranial nerve. Preoperative detection of neurovascular compression is essential for accurate diagnosis, appropriate treatment, and the good operative results. Three dimensional Fourier Transformation-Constructive Interference in Steady State(3DFT-CISS) images are known to give good contrast between CSF, nerve, and vessels. We applied a 3DFT-CISS imaging technique for the preoperative evaluation of patients with these diseases and estimated the diagnostic accuracy and usefulness of this study. Methods : A series of 71 patients with trigeminal neuralgia and hemifacial spasm were treated by microvascular decompression. Among them 34 patients with trigeminal neuralgia and 24 patients with hemifacial spasm had preoperative CISS images. We compared the radiologic finding with the operative finding, and analysed the diagnostic usefulness of 3DFT-CISS imaging. Results : The sensitivity of CISS images of detecting the neurovascular compression was 90.3% in trigeminal neuralgia and 100% in hemifacial spasm. There were one false-positive and three false-negative cases in trigeminal neuralgia, and one false-positive case in hemifacial spasm. The accuracy in diagnosing the causative vessel was 73.5% in trigeminal neuralgia and 83.3% in hemifacial spasm. Conclusion : CISS image is very useful diagnostic tool for preoperative evaluation of neurovascular compression in patients with trigeminal neuralgia and hemifacial spasm. No additional neuroradiologic examination other than CISS image and MRA is needed for preoperative evaluation of patients with trigeminal neuralgia and hemifacial spasm.

• Journal of radiological science and technology
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• v.47 no.3
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• pp.183-195
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• 2024

Additional functional upgrades to the large-area compton camera (LACC) measurement device that can provide characteristics evaluation information (nuclear species and radioactivity) and two-dimensional or three-dimensional distribution imaging information of radioactive materials existing in surface or internal of concrete structures are required in terms of work stability and efficiency in order to apply to actual decommissioning sites such as nuclear power plants or medical cyclotron facilities by using this measurement device. To this purpose, the technology that allows radiation workers to intuitively and visually check the distribution of radioactive materials in advance by matching the two-dimensional distribution imaging information of radioactive materials obtained through the LACC measurement device and visual imaging of the measurement zone (10 m × 5 m) was developed. In addition, the separate system that can automatically adjust the position (height) in units of the measurement area size (0.7 m × 0.3 m × 0.8 m) of the LACC measurement device was developed and the integrated management system for characteristics evaluation information and two-dimensional or three-dimensional distribution imaging information obtained per unit of measurement for radioactive materials was developed. These functional upgrades related to LACC measurement device can improve work efficiency and safety when measuring radioactivity of concrete structures and enable the establishment of appropriate decommissioning strategies using radioactivity measurement information for decommissioning nuclear power plants or medical cyclotron facilities.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.335-346
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• 2001

The purpose of this study was to investigate the ideal clinical torque(In the SWA rectangular wire, the torque by the angle between the plane part and twisted part to move the tooth) of the orthodontic rectangular wire which produce the proper labiolingual movement of the single tooth during finishing stage of the orthodontic treatment. The clinical torque is the sum of the play and the active torque which generates the moment at the bracket. The play is calculated by the formula and the active torque is calculated by the computer aided three-dimensional finite element method. The finite element model was consist of the three brackets which formed a row and 3 kinds of orthodontic rectangular wire(stainless steel, TMA, NiTi) which inserted in brackets. Both sides of the model were twisted and the moment generated in the center bracket was calculated. The sizes of seven wires which were used commonly were .016'X.022', .017'X.022', .017'X.025', .018'X.025', .019'X.025', .020'X.025', .021'X.025'. In 018' bracket, 016'X.022', .017'X.022', .017'X.025' wires were inserted and in 022' bracket, all the sizes of wires except .016'X.022' were inserted and tested. The following conclusions could be drawn from this study. 1. The moments generated on the same size of the wires by the same active torque were equal regardless of the bracket slot size. 2. The moments were increased with the size of the wires. The moment generated on the .021'X.025' wire was about 1.75 times as large as that on the .016'X.022' wire regardless of the material. 3. The moments were increased in the order of the NiTi, TMA stainless steel. The moment of the TMA wire was 0.35 times as small as that of the stainless steel wire and the moment of the NiTi was0.16 times as small as that of the stainless steel wire. 4. The moment was decreased as the interbracket distance was increased. 5. To get a desired moment with the specific size and material of the wire on the specific bracket slot, the formula and the results were displayed.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.101-106
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• 2000

Purpose : This study was peformed to evaluate the effectiveness and tolerance of craniospinal irradiation for patients with modulloblastoma and to define the optimal radiotherapeutic regimen. Materials and Methods : We retrospectively analyzed the records of 43 patients with modulloblastoma who were treated with external beam craniospinal radiotherapy at our institution between May, 1984 and April, 1998. Median follow up period was 47 months with range of 18 to U months. Twenty seven patients were male and sixteen patients were female, a male to female ratio of 1.7:1. Surgery consisted of biopsy alone in 5 patients, subtotal excision in 24 patients, and gross total excision in 14 patients. All of the patients were treated with craniospinal irradiation. All of the patients except four received at least 5,000 cGy to the posterior fossa and forty patients received more than 3,000 cGy to the spinal cord. Results : The overall survival rates at 5 and 7 years for entire group of patients were 57$\%$ and 56$\%$, respectively. Corresponding disease free survival rates were 60$\%$ and 51$\%$, respectively, The rates of disease control in the posterior fossa were 77$\%$ and 67$\%$ at 5 and 7 years. Gross total excision and subtotal excision resulted in 5 year overall survival rates of 76$\%$ and 66$\%$, respectively, In contrast, those patients who had biopsy alone had a 5 year survival rate of only 40$\%$. Posterior fossa was a component of failure in 11 of the 18 recurrences. Seven recurrences were isolated to the posterior fossa. Four patients had neuraxis recurrences, three had distant metastasis alone and four had multiple sites of failure, all involving the primary site. Conclusion : Craniospinal irradiation for patients with moduiloblastoma is an effective adjuvant treatment without significant treatment related toxicitles. There is room for Improvement in terms of posterior fossa control, especially in biopsy alone patients. The advances in radiotherapy including hypefractionation, stereotactic radiosurgery and 3D conformal radiotherapy would be evolved to improve the tumor control rate at primary site.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.174-181
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• 2003

Purpose: The target volume for the three field technique in breast cancer include the breast tangential and supraclavicular areas. The techniques rotating the gantry and couch angles, to match these two areas, will geometrically produce mismatching of the posterior edge between the medial and lateral tangential beams. This mismatch was confirmed by film dosimetry and three-dimensional computer planning. The correction methods of this mismatching were studied in this article. Materials and Methods: After the supraclavicular field was simulated using a half beam block and the medial and lateral tangential fields, by the rotation of the couch and gantry, we compared the following two methods to correct the mismatch. The first method was the rotation of coillmator until a line drawn on the posterior edge of tangential beams before the rotation of couch aligned the line drawn on the posterior edge after the rotation. The second method was the rotation of collimator according to the formula developed by the author as follows; Co=$2sin^{-1}${$sin\{theta}\{cdot}sin(C/2)$} (Co: collimator angle, $\theta$: angle between tangential beam and table, C: couch angle) Results: The film dosimetry showed the mismatching of posterior edges of the medial and lateral tangential fields prior to the rotation of collimator, while the posterior edges matched well after the rotation of collimator according to the formula. The three-dimensional computer plan also showed that the posterior edges matched well after the rotation of collimator accordingly. The DVH of the ipsilateral lung with the proper rotation of collimator angle was better than that without the rotation of collimator angle. Conclusion: The mismatching of the posterior edges of the medial and lateral tangential fields can be recognized on the three fileld technique in breast irradiation when the gantry and couch are simultaneously rotated and can be corrected with the proper rotation of the collimator angle. The radiation dose to the ipsilateral lung could be lowered with this technique.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.135-142
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• 2003

Purpose: The purpose of this study was to investigate the positional change of the uterus during radiotherapy. Materials and Methods: Between 1997 and 2001, 47 patients received definitive radiotherapy for cervical cancer at the Samsung Medical Center. For each patient, two MRI scans were taken; one before and the other 3$\~$4 weeks after the radiotherapy treatment. In T2 weighted MRI images, the positional change of the uterine was quantified by measuring six quantities; the distance from the cervix os to the isthmus of the uterus (Dcx), the maximum length from the isthmus of the uterus to the uterine fundus (Dco), the maximum vertical distance of the uterine body (Dco-per), the angle between the vertical line and the cervical canal in the sagittal images (Acx), the angle of the uterine corpus from the vertical line in the sagittal plan (Aco-ap), and the relative angle of the uterine corpus from a fixed anatomical landmark in the axial images (Aco-axi). Results: The mean Dcx values, before and during the treatment, were 36.7 and 27.8 mm, respectively. The Dco deviated by more than 10 mm in 14 cases (29.8$\%$). The change in the Acx ranged from 0.1 to 67.8$^{\circ}$ (mean 13.2$^{\circ}$). The Aco-ap changed by a maximum of 84.8$^{\circ}$ (mean 16.9$^{\circ}$). The differences in the Dcx plus the Dco in the smaller (<4 cm) and larger ($geq$4 cm) tumors were 5.3 and 19.4 mm, respectively. With patients less than 60 years old, or with a tumor size larger than 4 cm, the difference in the Acx was statistically significant. Conclusion: The positional changes of the uterus, during radiation treatment, should be considered in the 3DCRT or IMRT treatment planning, particularly in patients under 60 years of age or in those with a tumor size greater than 4 cm in maximum diameter.

• Korean Journal of Cognitive Science
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• v.34 no.3
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• pp.181-196
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• 2023

Size, velocity, and time equivalence are mechanisms that allow us to perceive objects in three-dimensional space consistently, despite errors on the two-dimensional retinal image. These mechanisms work on common cues, suggesting that the perception of motion distance, motion speed, and motion time may share common processing. This can lead to the hypothesis that, despite the spatial nature of visual stimuli distorting temporal perception, the perception of motion speed and the perception of motion duration will tend to oppose each other, as observed for objects moving in the environment. To test this hypothesis, the present study measured perceived speed using Müller-Lyer illusion stimulus to determine the relationship between the time-perception consequences of motion stimuli observed in previous studies and the speed perception measured in the present study. Experiment 1 manipulated the perceived motion trajectory while controlling for the retinal motion trajectory, and Experiment 2 manipulated the retinal motion trajectory while controlling for the perceived motion trajectory. The result is that the speed of the inward stimulus, which is perceived to be shorter, is estimated to be higher than that of the outward stimulus, which is perceived to be longer than the actual distance traveled. Taken together with previous time perception findings, namely that time perception is expanded for outward stimuli and contracted for inward stimuli, this suggests that when the perceived trajectory of a stimulus manipulated by the Müller-Lyer illusion is controlled for, perceived speed decreases with increasing duration and increases with decreasing duration when the perceived distance of the stimulus is constant. This relationship suggests that the relationship between time and speed perceived by spatial cues corresponds to the properties of objects moving in the environment, i.e, an increase in time decreases speed and a decrease in time increases speed when distance remains the same.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.359-371
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• 2008

Purpose: The purpose of this study was to investigate the stress distribution in mandibular implant overdentures with telescopic crowns compared to bar attachment. Material and methods: Three-dimensional finite element models consisting of the mandibular bone, 4 implants, and primary bar-splinted superstructure or secondary splinted superstructure with telescopic crowns were created. Vertical and oblique loads were directed onto the occlusal areas of the superstructures to simulate the maximal intercuspal contacts and working contacts such as group function occlusion. Maximum stress and stress distribution were analysed in mandibular bone, implant abutments, and superstructures. Results: 1. In comparison of von Mises stress on mandibular bone, telescopic overdenture had a little lower stress values in vertical load and working side load except oblique load. In the mandible, the telescopic overdenture distributed more uniform stress than the bar overdenture. 2. In comparison of von Mises stress on implant abutments, telescopic overdenture had much lower stress values in all load conditions. In implant abutments, the telescopic overdenture distributed stress similar to the bar overdenture. Stress was concentrated on the distal surfaces of the posterior implant abutments in both mandibular overdentures. 3. In comparison of von Mises stress on superstructures, the telescopic overdenture had much more stress values in all load conditions. However, the telescopic overdenture distributed more uniform stress on superstructure than the bar overdenture. In the bar overdenture, stress was concentrated on each cental area of bar structures and connected area between implant abutments and bar structures. Conclusion: In the results of this study, the telescopic overdenture had lower stress values than the bar overdenture in mandibular bone and implant abutments, but more stress values in superstructures. However, if optimal material was selected in making superstructures, the telescopic overdenture was compared to the bar overdenture in stress distribution.

• The korean journal of orthodontics
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• v.29 no.2 s.73
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• pp.197-207
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• 1999

Although there is a severe underlying skeletal deformity, the dentition has often maintained some occlusal contact and interdigitation by the teeth compensating in their positions for the skeletal problem, and these dental compensations are manifested in all three planes of space. The purposes of present investigation were 1) to study the pattern of dentoalveolar compensation of hyperdivergent skeletal pattern , and 2) to compare the dentoalveolar compensations of hyperdivergent skeletal pattern in children with adults. The samples selected for this study were consisted of 60 subjects in normal group, 60 subjects in hyperdivergent group. Each was divided into two subgroups by age ; child groups($8\~12yr$ old) and adult groups(17yr old over). The findings of this study were as follows; 1. In child, hyperdivergent subjects had smaller posterior lower facial height(p<0.01) and slightly longer anterior lower facial height than normal ones. In adults, they still expressed smaller posterior lower facial height and much longer anterior lower facial height than normal ones(p<0.01). 2. Hyperdivergent subjects had larger amount of upper and lower incisor relative eruption to their basal bone length than normal ones(p<0.05). In adult, relative eruption of upper incisor was increasing(p<0.05), although relative eruption of lower incisor remained the same as the child. 3. In child, there was no difference between hyperdivergent group and nomal one in the upper and lower molar relative eruption to their basal bone length. In adult, hyperdivergent group had target amount of upper molar relative eruption than normal ones(p<0.01), but relative eruption of lower molar was similar to normal ones. 4. Hyperdivergent group had larger angle between lower occlusal plane and mandibular plane than normal group(p<0.01). Upper occlusal plane of adult groups rotated more antero-superiorly than child groups, and adult hyperdivergent group had sleeper upper occlusal plane than normal group(p<0.05).

• The korean journal of orthodontics
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• v.35 no.1 s.108
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• pp.60-68
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• 2005

The evaluation of malocclusion has to be done quantitatively and qualitatively. This will be lead toward an analysis of malocclusion severity as well as treatment difficulty. The method of proper evaluation of malocclusion severity and treatment difficulty is necessary to assess treatment effect and efficiency for the orthodontists and to establish fundamentals for planning and executing the health-related policies in private and public institutions. The purposes of this study as the first part of the objective and quantitative analysis of malocclusion were 1) to measure treatment difficulty based on the opinions of several orthodontists. and 2) to investigate the relationships between objective malocclusion severity and subjective treatment difficulty 100 pairs of dental casts that had various types and severity of malocclusion were selected from the orthodontic departments of Kyurghee University and Samsung Medical Center The objective malocclusion severity was measured with the PAR (Peer Assessment Rating) index and the subjective treatment difficulty was evaluated by 8 experienced orthodontists. The relationships between objective malocclusion severity and subjective treatment difficulty were statistically evaluated. There were significant relationships between objective malocclusion severity and subjective treatment difficulty especially in the measurements of the upper anterior alignment, the buccal occlusion. the overjet, the overbite and the midline discrepancy en the malocclusion components. The results of this study can provide the background knowledge to develop a new occlusal index. which contains both the malocclusion severity and treatment difficulty for Korean orthodontists.