1.A roentgenocephalometric study on the effects of the chincap in the skeletal Class III malocclusion.
Chi Il HWANG ; Cheong Hoon SUHR
Korean Journal of Orthodontics 1989;19(1):219-243
The purpose of this study was to evaluate the effects of the chincap therapy on the craniofacial structure in persons with skeletal Class III malocclusion. The patients selected for this study were treated with extra-oral chincap therapy only. Both control and treatment samples were obtained from Seoul National University Hospital where these longitudinal data were gathered. 35 treated patients and 14 control patients were studied. The mean ages at the 1st evaluation was 8 years 3 months in the treatment sample and 9 years 4 months in the control sample. The duration of chin cap therapy was variable but averaged 2 years of treatment. Post-treatment observation procedeeded for 1 year 2 months. Active treatment and post treatment effects were evaluated. The results were as follows: 1. Neither significant restraint nor acceleration of growth was found in the cranial base and maxilla during treatment. 2. A distal rotation of the mandibular complex was seen. 3. Some amount of restraint of growth was found in mandibular body length, ramus height, mandibular length during treatment. 4. The gonial angle was reduced. 5. After removal of the chin-cap, forward displacement of the mandible took place.
Acceleration
;
Chin
;
Humans
;
Malocclusion*
;
Mandible
;
Maxilla
;
Seoul
;
Skull Base
2.Three-dimensional finite element analysis on reciprocal action by torque application in maxillary archwire.
Chee Il HWANG ; Cheong Hoon SUHR
Korean Journal of Orthodontics 1994;24(2):479-508
This study was designed to investigate the reciprocal movement which was derived form application of active torque in ideal arch wire by computer-aided three-dimensional finite element analysis of maxillary teeth and surrounding periodontal ligament composed of 2617 elements and 3725 nodes. Ideal arch wire model was also made using the beam elements and the contact between the wire and the bracket slot was made using the gap element. In this study non-linear elastic behaviors of contact between the wire and the bracket slot were considered on. We put the active torque between the lateral and central incisor and between the second premolar and the first molar with/without cinch-back. The results were expressed by quantitative and visible ways. The findings of this study were as follows: 1. Reciprocal actions to active torque were complex system consisting of a combination of counter-torque, bucco-lingual linear displacement and tipping, rotation of the teeth, occluso-gingival linear displacement. 2. When active anterior crown labial torque was applied, crown labial tippings of the lateral were the greatest, and those of the central incisor was the next. Crown lingual tippings of the canine and the first premolar, mesial rotations and extrusion of the lateral and distal rotations and intrusion of the canine occurred. When anterior torque with the cinch-back was applied, amount of crown labial tippings of the lateral and central incisor were reduced. Amount of crown lingual tipping of the canine and the first premolar were increased. Mesial tippings and mesial rotations of the second molar occurred. 3. When active posterior crown lingual torque was applied, crown lingual tippings of the first molar were the greatest, and crown labial tippings of the second premolar and the first premolar were the next, the crown lingual tipping of the second molar were a little. Mesial rotations of the second premolar occurred but those of the first premolar didn't occurred.
Bicuspid
;
Crowns
;
Finite Element Analysis*
;
Incisor
;
Molar
;
Periodontal Ligament
;
Tooth
;
Torque*
3.Sister Chromatid Exchanges in Workers Occupationally Exposed to Ethylene Oxide.
Soung Hoon CHANG ; Won Jin LEE ; Cheong Sik KIM ; Cheong Hyun HWANG ; Jong Tae PARK ; Dae Seong KIM ; Young Whan KIM
Korean Journal of Occupational and Environmental Medicine 1998;10(4):428-437
Operators of hospital sterilizers who use ethylene oxide (EtO) were studied to determine the exposure of EtO level and the frequency of sister chromatid exchanges (SCEs) from June 12 to July 20, 1997. To evaluate SCEs in the peripheral blood cells, we selected 22 workers at the central supply room of 4 university hospitals and 22 unexposed workers at the same hospitals according to match sex, age, and smoking habit and also did questionnaires. The mean air concentrations (8-hr TWA) of EtO at 4 university hospitals were less than 1 ppm. The SCE frequencies in exposed workers to EtO and controls were normally distributed. The SCE frequencies in exposed workers to EtO and controls were 6.42+/-.63, 5.86+/-.69, respectively and their differences were statistically significant (p=0.0093). But there were no statistically significant differences in smoking, alcohol intake, coffee drinking. Especially smokers who exposed to EtO were increased SCE statistically significant than the exposed group who did not smoke.
Blood Cells
;
Coffee
;
Drinking
;
Ethylene Oxide*
;
Hospitals, University
;
Humans
;
Occupations*
;
Questionnaires
;
Siblings*
;
Sister Chromatid Exchange*
;
Smoke
;
Smoking
4.Lipid Peroxidation and Antioxidants in Workers Exposed to Lead.
Won Jin LEE ; Cheon Hyun HWANG ; Cheong Sik KIM ; Soung Hoon CHANG ; Yang Ho KIM ; Hae Joon KIM
Korean Journal of Preventive Medicine 1998;31(3):449-459
This study was started to find out if plasma malondialdehyde(MDA), alpha-tocopherol and erythrocyte superoxide dismutase(SOD) activity could be markers of biological activity resulting from exposed to lead in workers. Blood samples were randomly obtained from lead -exposed workers(n=29), CO2 welders(n=60) and office workers(n=60). We used whole blood to analyse blood lead with atomic absorption spectrophotometer. Superoxide dismutase activity in erythrocyte was measured with spetrophotometer. MDA and alpha-tocopherol in plasma were measured with high performance liquid chromatography. Lead-exposed workers was significantly high in blood lead concentration(29.37 ng/dl) compared with welders(6.42 ng/dl) and office workers(5.01 ng/dl). The level of plasma MDA was significantly higher in the lead-exposed workers(1.87 nmol/g cholesterol) than the welders(1.41 nmol/g cholesterol) and office workers(1.41 nmol/g cholesterol). Erythrocyte SOD activity in lead-exposed workers(56.80 U/g Hb) was significantly increased than those of welders(37.63 U/g Hb) and office workers(20.47 U/g Hb). The plasma alpha-tocopherol level of lead-exposed workers(4.93 ng/g cholesterol) was statistically different from welders(4.25 ng/g cholesterol) and office workers(4.28 ng/g cholesterol). Neither age nor smoking was related to SOD or MDA level. Blood lead was significantly correlated with erythrocyte SOD activity(r=0.405), plasma MDA(r=0.296) and alpha-tocopherol(r=0.207). Plasma MDA was also significantly correlated with SOD (r=0.217). In multiple regression analysis, the change of MDA and SOD activity level related to the blood lead concentration. These results suggested that the increase of plasma MDA and erythrocyte SOD activity in lead-exposed workers had a close relationship with the oxidative stress induced by lead.
Absorption
;
alpha-Tocopherol
;
Antioxidants*
;
Chromatography, Liquid
;
Erythrocytes
;
Lipid Peroxidation*
;
Oxidative Stress
;
Plasma
;
Smoke
;
Smoking
;
Superoxide Dismutase
;
Superoxides
5.A Case Report of Cholangiocarcinoma Arising from a Biliary Adenofibroma:Radiologic Findings and Review of Literature
Hyun-Ji LIM ; Mi-Suk PARK ; Young Nyun PARK ; Sun Il KIM ; Yeo-Eun KIM ; Cheong Hoon HWANG
Journal of the Korean Radiological Society 2021;82(3):721-728
Biliary adenofibromas are rare biliary epithelial tumors that are classified as benign. Nevertheless, some cases have been reported to show malignant transformations. The radiologic findings of biliary adenofibromas and their malignant transformation are not well-established because of their rarity. We present a case of a cholangiocarcinoma arising from a biliary adenofibroma assessed using ultrasonography, CT, and MRI. The differential diagnoses include other hepatic tumors.
6.A Case Report of Cholangiocarcinoma Arising from a Biliary Adenofibroma:Radiologic Findings and Review of Literature
Hyun-Ji LIM ; Mi-Suk PARK ; Young Nyun PARK ; Sun Il KIM ; Yeo-Eun KIM ; Cheong Hoon HWANG
Journal of the Korean Radiological Society 2021;82(3):721-728
Biliary adenofibromas are rare biliary epithelial tumors that are classified as benign. Nevertheless, some cases have been reported to show malignant transformations. The radiologic findings of biliary adenofibromas and their malignant transformation are not well-established because of their rarity. We present a case of a cholangiocarcinoma arising from a biliary adenofibroma assessed using ultrasonography, CT, and MRI. The differential diagnoses include other hepatic tumors.
7.Comparative Analysis between Rheumatic and Non-rheumatic Disease Patients after Posterolateral Fusion of the Lumbar Spine: Spinal Fusion in Rheumatic Disease Patients.
Ye Soo PARK ; Kyu Tae HWANG ; Tae Soo PARK ; Cheong Hyeok CHOI ; Il Hoon SUNG ; Jae Lim CHO
The Journal of the Korean Rheumatism Association 2004;11(4):372-378
OBJECTIVE: To evaluate the clinical and radiological results and to compare the results of posterolateral lumbar fusion in rheumatic and non-rheumatic disease. METHODS: A retrospective review of results was carried out in 20 patients who had posterolateral lumbar fusion with rheumatic disease from Jul. 1996 to Aug. 2002. And same cases of non-rheumatic disease were compared. The diagnosis of rheumatic disease was confirmed by the ARA revised criteria. Bony union was evaluated by Lenke's criteria and the clinical results by Katz's satisfaction degree. Statistical analysis was performed by paired T-test and ANOVA test. RESULTS: In rheumatic disease group, there were 7 males and 13 females. Mean age was 56.6 (20~68) years and mean fused segments were 2.7 (1~7). Mean follow-up period was 41 months (12~80) after surgery. In non-rheumatic group, there was 6 males and 14 females. Mean age was 57.1 (35~71) years and mean fusion segments were 2.9 (1~4), Mean follow-up period was 40.2 (12~88) months. In age and fusion segments between two group, there was no statistical difference. In rheumatic disease group, the diagnosis were rheumatoid arthritis in 18 patients, ankylosing spondylitis in 1, and systemic lupus erythematosus in 1 patient. The other operations for combined disease were 8 total knee arthroplasty and 3 total hip arthroplasty. There were no statistical differences in operation time (p=0.527), perioperative bleeding (p=0.653) and postoperative (p=0.830) bleeding between two group. In radiological bony union, all patients of two groups showed A and B grade by Lenke's criteria. Bony union was complete at 5.5 (5~8), 5.1 (4~7) months after surgery. There was no significant difference in clinical satisfaction (p=0.756). CONCLUSION: There were no significant differences in clinical and radiological results between the rheumatic and non-rheumatic patients with disease of the lumbar spine.
Arthritis, Rheumatoid
;
Arthroplasty
;
Arthroplasty, Replacement, Hip
;
Diagnosis
;
Female
;
Follow-Up Studies
;
Hemorrhage
;
Humans
;
Knee
;
Lupus Erythematosus, Systemic
;
Male
;
Retrospective Studies
;
Rheumatic Diseases*
;
Spinal Fusion*
;
Spine*
;
Spondylitis, Ankylosing
8.Acute Pancreatitis Due to a Duodenal Ulcer.
Sung Ik PYEON ; Jong Ho HWANG ; Yong Tae KIM ; Ban Seok LEE ; Sang Ho LEE ; Jae Nam LEE ; Jae Hoon CHEONG ; Kong Jin OH
Clinical Endoscopy 2014;47(6):579-583
Duodenal ulcers and acute pancreatitis are two of the most commonly encountered gastrointestinal diseases among the general population. However, duodenal ulcer-induced pancreatitis is very rarely reported worldwide. This report elaborates on a distinct medical treatment that contributes to partial or complete treatment of acute pancreatitis induced by a duodenal ulcer scar.
Cicatrix
;
Duodenal Ulcer*
;
Duodenum
;
Gastrointestinal Diseases
;
Pancreatitis*
;
Stents
;
Ulcer
9.Implementation and Evaluation of the Electron Arc Plan on a Commercial Treatment Planning System with a Pencil Beam Algorithm.
Sei Kwon KANG ; Soah PARK ; Taejin HWANG ; Kwang Ho CHEONG ; Me Yeon LEE ; Kyoung Ju KIM ; Do Hoon OH ; Hoonsik BAE
Korean Journal of Medical Physics 2010;21(3):304-310
Less execution of the electron arc treatment could in large part be attributed to the lack of an adequate planning system. Unlike most linear accelerators providing the electron arc mode, no commercial planning systems for the electron arc plan are available at this time. In this work, with the expectation that an easily accessible planning system could promote electron arc therapy, a commercial planning system was commissioned and evaluated for the electron arc plan. For the electron arc plan with use of a Varian 21-EX, Pinnacle3 (ver. 7.4f), with an electron pencil beam algorithm, was commissioned in which the arc consisted of multiple static fields with a fixed beam opening. Film dosimetry and point measurements were executed for the evaluation of the computation. Beam modeling was not satisfactory with the calculation of lateral profiles. Contrary to good agreement within 1% of the calculated and measured depth profiles, the calculated lateral profiles showed underestimation compared with measurements, such that the distance-to-agreement (DTA) was 5.1 mm at a 50% dose level for 6 MeV and 6.7 mm for 12 MeV with similar results for the measured depths. Point and film measurements for the humanoid phantom revealed that the delivered dose was more than the calculation by approximately 10%. The electron arc plan, based on the pencil beam algorithm, provides qualitative information for the dose distribution. Dose verification before the treatment should be mandatory.
Electrons
;
Film Dosimetry
;
Particle Accelerators
10.Dose Verification Study of Brachytherapy Plans Using Monte Carlo Methods and CT Images.
Kwang Ho CHEONG ; Me Yeon LEE ; Sei Kwon KANG ; Hoonsik BAE ; Soah PARK ; Kyoung Joo KIM ; Tae Jin HWANG ; Do Hoon OH
Korean Journal of Medical Physics 2010;21(3):253-260
Most brachytherapy treatment planning systems employ a dosimetry formalism based on the AAPM TG-43 report which does not appropriately consider tissue heterogeneity. In this study we aimed to set up a simple Monte Carlo-based intracavitary high-dose-rate brachytherapy (IC-HDRB) plan verification platform, focusing particularly on the robustness of the direct Monte Carlo dose calculation using material and density information derived from CT images. CT images of slab phantoms and a uterine cervical cancer patient were used for brachytherapy plans based on the Plato (Nucletron, Netherlands) brachytherapy planning system. Monte Carlo simulations were implemented using the parameters from the Plato system and compared with the EBT film dosimetry and conventional dose computations. EGSnrc based DOSXYZnrc code was used for Monte Carlo simulations. Each (192)Ir source of the afterloader was approximately modeled as a parallel-piped shape inside the converted CT data set whose voxel size was 2x2x2 mm3. Bracytherapy dose calculations based on the TG-43 showed good agreement with the Monte Carlo results in a homogeneous media whose density was close to water, but there were significant errors in high-density materials. For a patient case, A and B point dose differences were less than 3%, while the mean dose discrepancy was as much as 5%. Conventional dose computation methods might underdose the targets by not accounting for the effects of high-density materials. The proposed platform was shown to be feasible and to have good dose calculation accuracy. One should be careful when confirming the plan using a conventional brachytherapy dose computation method, and moreover, an independent dose verification system as developed in this study might be helpful.
Accounting
;
Brachytherapy
;
Film Dosimetry
;
Humans
;
Monte Carlo Method
;
Organoplatinum Compounds
;
Population Characteristics
;
Uterine Cervical Neoplasms
;
Water