• Archives of Plastic Surgery
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• v.42 no.4
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• pp.407-410
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• 2015

The aim of this study is to review the protective effect of a bicycle helmet on each facial location systematically. PubMed was searched for articles published before December 12, 2014. The data were summarized, and the odds ratio (OR) between the locations of facial injury was calculated. A statistical analysis was performed with Review Manager (The Nordic Cochrane Centre). Bicycle helmets protect the upper and middle face from serious facial injury but do not protect the lower face. Non-wearers had significantly increased risks of upper facial injury (OR, 2.07; P<0.001) and of middle facial injury (OR, 1.97; P<0.001) as compared to helmet users. In the case of lower facial injury, however, only a slightly increased risk (OR, 1.42; 95% confidence interval (CI), 0.67-3.00, P=0.36) was observed. The abovementioned results can be attributed to the fact that a helmet covers the head and forehead but cannot cover the lower face. However, helmets having a chin cap might decrease the risk of lower facial injury.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.219-243
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• 1989

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. 55 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 chincap 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 genial angle was reduced. 5. After removal of the chin-cap, forward displacement of the mandible took place.

• The korean journal of orthodontics
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• v.24 no.4 s.47
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• pp.799-817
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• 1994

The purpose of this study was to evaluate the initial skeletal pattern and growth change of whom had responsed well to chincap therapy. 93 patients seleted for this study were in mixed dentition and treated with chincap for more than 2 years. And 54 subjects were selected from these total samples and classified into two groups by the improvement of four measurements : ANB difference, APDI, Wits appraisal, and AF-BF. One was good response group which consisted of 26 children and the other was poor response group with 19 patients. Various measures of the craniofacial structure in the initial lateral cephalograms and the annual increments were calculated and analyzed by comparing two groups with t-test. The results were as follows : 1. Good response group had more horizontal growth pattern in initial stage of treatment than poor response group, and the contributing factors of this result were anterior posterior facial height ratio, gonial angle, lower genial angle and SN-mandibular plane angle. 2. The maxilla was positioned more anteriorly in good response group. 3. The amounts of vertical growth of maxilla was smaller but the horizontal growth of maxilla was larger in good response group. 4. The mandible rotated more infero-posteriorly in good response group. 5. The good response group had more vertical growth pattern of mandibular condyle.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.1
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• pp.49-62
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• 1993

This study intends to find out the correspondence of the costumes of the terracotta warriors at the tomb of Qin Shi Huang to the dress of nomadic people. The Chinese took the dress of nomadic people into their costumes so that they might practise shooting arrows from horse back in the Age Of Wars. The terracotta warriors at the tomb of Qin Sin Huang provide us with substantial evidence that Qin Dynasty inherited the system of wearing the dress of nomadic people from Zhao. Figures of calvarys wear the jackets of nomadic people, but figures of other warriors wear Han jackets. This means that the aim of taking the dress of nomadic people is to be convenient in practising shooting arrows from horse back. Nomadic people adjusted their jackets to left, because they road on a horse from left for being the tunga only on the left. But calvarys adjusted their jackets to right. In those days, China didn't have a tunga. So there was no necessity for riding from left. And Chinese were accustomed to adjusted their jackets to right. This is the reason why calvarys adjusted their jackets to right, though they wear the dress of nomadic people. Soldiers wear trousers. Some have puttee, some have their leg bounds. All the soldiers tightened their coats or jackets with belts which were inhereted from nomadic people. They wear either shoes or short boots. The figures are classified according to rank, espicially in their hats and armours. General wears a cap adorned with pheasant' feathers, officer wears an unadorned cap, and men are hatless or in turbans. Calvary's headgear looks like a p'ing-chin-tse which was correspondence to the headgear of nomadic people. Soldiers wear armours according to duty, and armours are differentiated by rank. From the state of terracotta warriors, I think that the warriors were made from BC 246 to BC 210 which is equal to the date of making the tomb of Qin Shi Huang. Then the date of making the terracotta warriors was between 60 and 100 years since the king Wu Ling of the state of Zhao took the dress of nomadic people.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.539-544
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• 1998

Thermoformed appliance, which has been recently introduced for dental usage, is an appliance made of thermoformed sheets and formed with positive or negative pressure under heat. Thermoplastic material is a kind of plastics and can be repeatedly softened by heat. It is classified into hard elastic foil, hard/soft compound foil and soft elastic foil, including BIOPLAST, BIOCRYL, IMPRELON, etc. It has been developed in 1969 and is available in various thickness, shape and color. There are two types of Vacuum former for thermoplastic materials; the pressure type and suction type. The former is much better than the latter for fabrication of various appliances due to its higher pressure. The authors have applied these appliances to some cases - chin cap, active retainer, individual Fluoride tray, mouth protector, bracket transfer mask, bruxism splint(night guard), Essix appliance - by pressure type Vacuum former($Biostar^{(R)}$). The thermoplastic appliances have numerous advantages such as simple procedure, short working time, clean and transparent product, less objectionable taste. But its outstanding advantage would be its excellent biocompatibility bacause it has no monomer and hence no tissue irritation. Although there is some limitations in its usage, it can be used widely for various purposes especaily for pediatric dentistry.

• Current Applied Physics
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• v.18 no.12
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• pp.1564-1570
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• 2018

Charge transport dynamics in ZnO based inverted organic solar cell (IOSC) has been characterized with transient photocurrent spectroscopy and localised photocurrent mapping-atomic force microscopy. The value of maximum exciton generation rate was found to vary from $2.6{\times}10^{27}m^{-3}s^{-1}$ ($J_{sat}=79.7A\;m^{-2}$) to $2.9{\times}10^{27}m^{-3}s^{-1}$ ($J_{sat}=90.8A\;m^{-2}$) for devices with power conversion efficiency ranging from 2.03 to 2.51%. These results suggest that nanorods served as an excellent electron transporting layer that provides efficient charge transport and enhances IOSC device performance. The photovoltaic performance of OSCs with various growth times of ZnO nanorods have been analysed for a comparison between AM1.5G spectrum and local solar spectrum. The simulated PCE of all devices operating under local spectrum exhibited extensive improvement with the gain of 13.3-3.7% in which the ZnO nanorods grown at 15 min possess the highest PCE under local solar with the value of 2.82%.

• The korean journal of orthodontics
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• v.33 no.1 s.96
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• pp.63-72
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• 2003

Over the Past decades, the number of Patients seeking orthodontic treatment has increased markedly with socioeconomic development and change of recognition on appearance. The purpose of this study was to provide an epidemiologic data base related to the orthodontic treatment need. We could take an adequate information regarding the characteristics of orthodontic patients, and the changing trends about treatment mordality. Distrubution and treands were Investigated in 676 patients who had been examined and diagnosed at Department of orthodontics, Dental Hospital, Seoul National University from January to June in 1992 and 2002. 1. Sex distribution of patients changed from 1:2.1 to 1:1.5 (male female). 2. In 2002, are distribution had shown $7\~12$ year-old group being the largest$(32.0\%)$ and percentage of $19\~24,\;13\~18,\;over\;25,\;4\~6,\;0\~3$ year-old group were $24.0\%,\;21.6\%,\;14.2\%,\;5.8\%,\;2.4\%$ respctively. Compared with data in 1992, the number of adult patients highly increased. 3. With regard to Angle classification, each percentage of Class I, Class II div 1, Class II div 2, and Class III malocclusion were $25.0\%,\;20.9\%,\;3.4\%,\;and\;48.1\%$ respectively in 2002. 4. Geographic distribution showed that most of the patients visited $(37.0\%)$ lived in northeast of Seoul in 2002. 5. Mandibular prognathism showed the highest percentage in chief complaints. The percentages of crowding and facial asymmetry were $14.2\%\;and\;11.8\%$ in 2002. Patients with facial asymmetry increased significantly. 6. Percentages of patients treated with fixed appliance and orthognathic surgery were $38.0\%\;and\;25.0\%$ in 2002. Patients needed to observe the growth pattern comprised $13.0\%$ with increasing trends. The use of chin cap reduced and the percentage of ortognathic surgery and growth observation increased significantly.

• The korean journal of orthodontics
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• v.25 no.1 s.48
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• pp.1-12
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• 1995

The purpose of this study was to predict the respose to the chincap therapy from the initial cephalometric measurements and to obtain the indication of chincap therapy. 40 patients selected for this study were classified into two groups by the occlusal stability after completion of permanent dentition and the improvement of facial profile, after chincap therapy. One was good response group which consisted of 25 children and the other was poor response group with 15 patients. Various measurements of the craniofacial structure in the initial lateral cephalogram were calculated and analyzed by t-test and discriminant analysis. The results were as follows: 1. Good response group had more horizontal growth pattern in initial stage of treatment, and the contributing measurements were $Bj\ddot{o}rk$ sum anterior-posterior facial height ratio, genial angle, lower genial angle and occlusal plane to AB plane angle. 2. The critical points and predictive values of the influential skeletal measurements were calculated. 3. The discriminant function was obtained from three major influential measurements; $Bj\ddot{o}rk$ sum, genial angle and occlusal plane to hn plane angle, and this function could discreminate correctly in $85\%$ of this samples.