• Journal of the Korean Orthopaedic Association
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• v.55 no.1
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• pp.62-70
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• 2020

Purpose: External tibia torsion and proximal tibial vara have been reported in severe varus deformed osteoarthritis, which is a tibio-femoral angle of more than 20°. The radiology measurements were compared with those of control group and the preoperative and follow-up radiology and clinical results were examined. Materials and Methods: From January 2007 to March 2016, 43 knees from 37 persons, who underwent total knee arthroplasty for a severe varus deformity of more than 20° on the tibio-femoral angle on the standing radiographs and had a follow-up period more than two years, were examined. The mean follow-up period was 45.7 months. The control group, who underwent conservative treatments, had Kellgren-Lawrence grade three osteoarthritis and a tibio-femoral angle of less than 3° varus. The external tibial torsion of enrolled patients and control group were estimated using the proximal tibio-fibular overlap length and the tibial torsion values on computed tomography. The proximal tibia vara was measured using the proximal tibial tilt angle. The preoperative and postoperative proximal tibio-fibular overlap length, tibial torsion value, proximal tibial tilt angle, and hospital for special surgery (HSS) score were evaluated. Results: The mean proximal tibio-fibular overlap length was 18.6 mm preoperatively and 11.2 mm (p=0.031) at the follow-up. The control group had a mean proximal tibio-fibular overlap length of 8.7 mm (p=0.024). The mean tibial torsion value was 13.8° preoperatively and 14.0° (p=0.489) at the follow-up. The control group had a mean tibial torsion value of 21.9° (p=0.012). The mean proximal tibial tilt angle was 12.2° preoperatively and 0° (p<0.01) at the follow-up. The control group had a mean proximal tilt angle of 1.2° (p<0.01). The preoperative tibiofemoral angle and mechanical axis deviation were corrected from preoperative 28.3° and medial 68.4 mm to postoperative 0.7° and medial 3.5 mm (p<0.01, p<0.01), respectively. The HSS scores increased from 34 points of preoperatively to 87 points at the last follow-up (p=0.028). Conclusion: Patients with advanced osteoarthritis with a severe varus deformity of more than 20° had significant increases in the external tibial torsion and varus of the proximal tibia. The tibial torsion value before and after surgery in the enrolled patients was not changed statistically, but good clinical results without complications were obtained.

• Tunnel and Underground Space
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• v.13 no.1
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• pp.33-43
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• 2003

Field investigations of the orientations of discontinuity planes inside the borehole for designing the underground rock structures have been depend solely on the borehole image-taking techniques. But, borehole image-taking has to be processed after the completion of drilling operation and also requires the handling of highly expensive apparatus so that practical application is very restricted. In this study Discontinuity Orientation Measurement (DOM) drilling system and discontinuity analysis model RoSA-DOM are developed to acquire the reliable information of rock structure by analyzing the characteristics of joint distribution. DOM drilling system retrieves the rock core on which the reference line of pre-fixed drilling orientation is engraved. Coordinates of three arbitrary points on the joint surface relative to the position of reference line are assessed to determine the orientation of joint plane. The position of joint plane is also allocated by calculating the location of core axis at which joint plane is intersected. Then, the formation of joint set is analyzed by utilizing the clustering algorithm. Total and set spacings are calculated by considering the borehole axis as the scanline. Engineering applicability of in-situ rock mass around the borehole is also estimated by calculating the total and regional RQDs along the borehole axis.

• The korean journal of orthodontics
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• v.28 no.2 s.67
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• pp.189-201
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• 1998

The purpose of this study was to evaluate the characteristics of craniofacial skeleton on orthognathic surgical cases with skeletal Class III malocclusion. For this study, 74 students at the dental college of Chosun University volunteered as a normal occlusion group. They had well-balanced faces and good occlusions with acceptable Class I molar relationship. They had not received orthodontic treatment and had no signs or symptoms of temporomandibular joint dysfunction. 45 malocclusion patients enrolled for orthognathic surgical treatment with skeletal Class III malocclusion at the Department of Orthodontics, College of Dentistry, Chosun University. On the basis of this study. the results of this study were as follows: 1. Skeletal Class III malocclusion was largely due to the overgrowth of mandible in man and the undergrowth of maxilla in woman. 2. The mandible was antero-inferiorly overgrown by large MP-HP angle and large genial angle in orthognathic surgical cases with skeletal Class III malocclusion. And also, upper incisors were severely labioversioned, but on the other hand lower incisors were linguoversioned. 3. In female, lower-third facial height was characteristically shortened in comparison with middle-third facial height and also, lower facial throat angle was small in male.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.373-384
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• 2003

The purpose of this study was to evaluate the eruption pattern of a cyst-associated mandibular premolar after marsupialization of a dentigerous cyst in children. The result from the twenty two pairs of normalized panoramic radiographs of twenty two patients who underwent neither extraction nor orthodontic traction of the cyst-associated mandibular after marsupialization were as follows. 1. The eruption speed of a cyst-associated premolar was 3.5 times faster than that of the normal contra-lateral premolar(p<0.05). The angulation change of test group was an average of $2.7^{\circ}$ per month. 2. In the change of the level of root formation, the group which had a little root maturity tended to be faster in the eruption speed(p>0.05) and the R1/4 group had a great change in the angulation change(p>0.05). 3. In the change to be with the cusp position index, the eruption speeds were increased to the 30% deviation groups. But, the eruption speed was decreased above that(p>0.05). 4. Group with cyst diminishment rate of more than $80mm^2$ per month showed the fastest eruption speed of all(p<0.05). 5. The mesial angulated teeth in the test group were decreased more rapidly than the distal angulated teeth in the eruption speed(p>0.05). But, increased in the angulation change(p<0.05). 6. There was a tendency of faster tooth eruption with less deviation of tooth axis. Group with tooth axis deviation of less than $15^{\circ}$ showed the fastest angulation change of all(p<0.05). 7. The eruption speed and the angulation change rapidly decreased during the first 6 months following marsupialization. Based on the results of this study, a cyst-associated mandibular premolar erupted more rapidly after marsupializaton. We thought so that it's prognosis was good if the tooth had a little root maturity, a little devitation and cyst lesion healed faster. We recommend that if there is enough space for eruption, orthodontic traction and surgical treatment of the cyst-associated tooth should be postponed 6 months after marsupialization.

• Journal of the Korean Orthopaedic Association
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• v.54 no.6
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• pp.547-556
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• 2019

Purpose: This study evaluated the results of surgical treatment for residual or recurrent deformity after the conservative treatment of idiopathic clubfoot. Materials and Methods: Fifty-one cases (32 patients), who were followed up to skeletal maturity, were reviewed retrospectively. The mean age at the last follow-up was 18.7 years. The surgical options included selective or comprehensive soft tissue release, tendon lengthening and transfer, and various types of osteotomy. The radiology measurements included the talocalcaneal angle and talo-first metatarsal angle in the anteroposterior (AP) view, and the talocalcaneal angle and calcaneal pitch in the lateral view. The radiology measurements were compared with the normal values for adults. The clinical evaluations were made using the ankle-hindfoot score and the midfoot score of the American Orthopaedic Foot and Ankle Society (AOFAS): excellent (>85), good (71-85), pair (56-70), and poor (<56). Results: At the last follow-up, the percentages of the 51 cases, whose parameter values fell within the normal ranges were as follows: in the AP view, 41.2% (talocalcaneal angle); and 90.2% (talo-first metatarsal angle). In the lateral view, the percentage was 84.3% (talocalcaneal angle). For the calcaneal pitch, the percentages were 61%. The mean AOFAS score was 88.1±10.7 on the ankle-hindfoot score and 86.7±11.5 on the midfoot score. Conclusion: The long-term outcome of patients with idiopathic clubfoot, who underwent surgical treatment after conservative treatment, was found to be 43%-90% of the normal range of radiographic indices. Clinically, the mean AOFAS scores were "excellent". Therefore, a satisfactory result can be obtained by analyzing the elements of deformity more accurately and then using the selective operation method, even if the non-surgical correction method fails.

• The korean journal of orthodontics
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• v.30 no.5 s.82
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• pp.535-542
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• 2000

The purpose of this study was to find the characteristics of the frontal natural head position(NHP) of patients with facial asymmetry, and to contribute to the diagnosis of facial asymmetry in the clinical examination of orthodontic patients. Twenty adult patients who had apparent facial asymmetry and no severe sagittal skeletal discrepancy were selected as the asymmetry group, and 21 young adults who had symmetric faces were selected as the symmetry group. Frontal cephalograms were obtained in the state of NHP using a pivot-mounted fluid level device. The degree of the menton deviation was defined as the angle between the line drawn through crista galli and anterior nasal spine and the line drawn through crista galli and menton. The following angles were measured and each of them was compared with the degree of the menton deviation one is the angle between the true vertical line and the supra-orbital line which is a tangent line to the extreme cranial point on the supra-orbital margin, and the other is the angle between the true vertical line and the cervical line drawn through the midpoint of atlas and the 4th cervical vertebra. Through the statistical analysis, following results were obtained. 1. The angle between the supra-orbital line and the true vertical line was much mote deviated from the right angle in the asymmetry group than in the symmetry group. 2. The angle between the cervical line and the true vertical line in the asymmetry group showed greater tendency than in the symmetry group, but the difference was not statistically significant. 3. In the asymmetry group, the degree of the menton deviation was positively correlated with the angle between the supraorbital line and the true vertical line. The above results suggest that racial asymmetry patients show the tendency to have the tilted NHP to compensate the deviation of menton position.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.8
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• pp.677-683
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• 2015

Hybrid rocket combustion displays low frequency instability(LFI, 10~30Hz) at a certain condition. Vortex shedding in the post-chamber is suspected to cause the occurrence of LFI. This study focused on the visualization of flow image using light emissions from high temperature combustion gas. Results shows that combustion pressure oscillates at a frequency of about 18 Hz, which is in phase with oscillations of light emission. Since LFI is not a property of thermo-acoustic instability, this result suggested there exists a physical coupling of pressure fluctuations with light emissions proportional to chemical reaction. Also POD analysis shows that dominant symmetric spatial modes in the stable combustion shift suddenly into asymmetric spatial pattern with the appearance of LFI. Especially, the appearance of mode 3 is a typical change of flow dynamics in unstable combustion representing a rotational fluid motions associated with vortex shedding.

• Journal of the Korean Orthopaedic Association
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• v.55 no.6
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• pp.495-502
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• 2020

Purpose: The aim of this study was to assess the effectiveness of domestically developed volar locking plate which has the concept of double-tiered subchondral support (DSS) in maintaining the reduction after distal radial fracture surgery. Materials and Methods: From July 2017 to December 2018, 54 patients were assessed. Plain radiographs were obtained immediately after surgery and at the last follow-up, and the radiographic parameters were measured in those images: radial length, radial inclination, volar tilt, ulnar variance, and distal dorsal cortical distance. The patients were subdivided into their age, type of fracture, and the position of the plate to evaluate the influence of each factors on the reduction maintenance. Results: Distal dorsal cortical distance in radiographs after the surgery was 5.91 mm (standard deviation, ±1.95 mm) on average. Significant differences in the radial length (p=0.038) and ulnar variance (p=0.001) were observed between immediately after surgery and at the last follow-up. When the parameters were evaluated by dividing the patients into subgroups according to the three specific factors, the ulnar variance showed a significant increase at the last follow-up when the patients were included 65-years-old or older. AO/OTA type C3 fracture, and Soong classification grade 0 plate position (p=0.007, p=0.012, p=0.046, respectively). Conclusion: Using the domestically developed DSS-type volar locking plate, significant reduction after distal radial fracture surgery could be maintained successfully. On the other hand, further study will be needed to determine about the reduction loss of the lunate facet identified in special cases that deal with fractures in elderly patients, unstable AO/OTA type C3 distal radial fractures, and Soong classification grade 0 plate position.

• Journal of Korean Society for Geospatial Information Science
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• v.25 no.1
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• pp.19-27
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• 2017

This research was aimed to analyze landslide susceptibility and compare the prediction accuracy using ensemble frequency ratio (FR) and logistic regression at the Inje area, Korea. The landslide locations were identified with the before and after aerial photographs of landslide occurrence that were randomly selected for training (70%) and validation (30%). The total twelve landslide-related factors were elevation, slope, aspect, distance to drainage, topographic wetness index, stream power index, soil texture, soil sickness, timber age, timber diameter, timber density, and timber type. The spatial relationship between landslide occurrence and landslide-related factors was analyzed using FR and ensemble model. The produced LSI maps were validated and compared using relative operating characteristics (ROC) curve. The prediction accuracy of produced ensemble LSI map was about 2% higher than FR LSI map. The LSI map produced in this research could be used to establish land use planning and mitigate the damages caused by disaster.

• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.113-127
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• 1999

The purpose of this study is to investigate the stability of counterclockwise rotation of mandible by sagittal split ramus osteotomy to correct the skeletal Class III malocclusion with anterior open bite. Twenty five skeletal Class III open bite patients(mean age 20.6 years) who were treated by the sagittal split ramus osteotonues with rigid fixation were examined in this study. Cephalometric radiographs were taken for each Patients Preoperative(T1), ewly Postoperative(T2), and late postoperative Period(T3). Mean postoperative period was 8.0 months. Cephalometric analysis was done and data from T1, T2, and T3 were analyzed statistically by Paired t-test and Pearson correlation analysis. The following results were obtained. 1. Mandibular plane angle decreased $2.9^{\circ}$ and mandibular occlusal plane angle related to SN Plane decreased $2.7^{\circ}$ after orthognathic surgery(T2). At 6 months after orthognathic surgery(T3), mandibular plane angle increased $1.0^{\circ}$, but mandibular occlusal plane angle did not changed. 2. The amount of horizontal relapse long time after orthognathic surgery(T3) was 1.6 mm at B point and it was $22\%$ of the total posterior movements. There was no vertical relapse in the anterior facial height. 3. The related factor with horizontal relapse at late postoperative period was mandibular plane angle(p<0.01). The related factors with decreasing posterior facial height were amount of mandibular setback(p<0.01), increasing of mandibular ramus height(p<0.01), and decrease of the mandibular plane angle during operation(p<0.01). 4. There was no relationship between the amount of changes in mandibular occlusal plan angle during operation and the amount of relapse after surgery.