• The korean journal of orthodontics
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• v.42 no.5
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• pp.255-262
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• 2012

Objective: We aimed to compare the retention characteristics of Essix and Hawley retainers. Methods: Adolescents undergoing fixed appliance treatment at 2 centers were recruited for this study. Twenty-two patients (16 women and 6 men) wore Essix retainers (Essix group) while 20 (14 women and 6 men) wore Hawley retainers (Hawley group). The mean retention time was 1 year, and the mean follow-up recall time for both groups was 2 years. Two qualified dental examiners evaluated the blind patient data. Maxillary and mandibular dental casts and lateral cephalograms were analyzed at 4 stages: pretreatment (T1), post-treatment (T2), post-retention (T3), and follow-up (T4). Results: The results revealed that Essix appliances were more efficient in retaining the anterior teeth in the mandible during a 1-year retention period. The irregularity index increased in both arches in both groups after a 2-year post-retention period. The mandibular arch lengths increased during treatment and tended to return to their original value after retention in both groups; however, these changes were statistically significant only in the Hawley group. Cephalometric variables did not show any significant differences. Conclusions: The retention characteristics of both Essix and Hawley retainers are similar.

• The korean journal of orthodontics
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• v.47 no.2
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• pp.142-147
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• 2017

The purpose of this study was to investigate immediate changes in the mandibular dentition after maxillary molar distalization using headgear in non-growing patients. Sixteen patients (mean age, $18.9{\pm}2.0$ years) with Class II molar relationship and crowding were included in the present study. To correct the molar relationship, headgear was used for maxillary molar distalization. Cone-beam computed tomography-generated half-cephalograms (CG Cephs) and dental casts were used to evaluate dental changes for each subject before and immediately after molar distalization using headgear. The mean duration that subjects wore the headgear was 6.3 months. CG Cephs showed that the first maxillary molars were distalized $4.2{\pm}1.6\;mm$ with $9.7^{\circ}{\pm}6.1^{\circ}$ of distal angulation. The intercanine, interpremolar, and intermolar widths of the mandible increased after maxillary molar distalization. The present study's results suggest that maxillary molar distalization using headgear induces a spontaneous response in the untreated mandibular dentition of non-growing patients.

• The korean journal of orthodontics
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• v.8 no.1
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• pp.7-17
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• 1978

The purpose of this study was to investigate the interrelationship of the maxillary interincisal diastema, spacing and crowing to the type of superior labial frenum and the type of intermaxillary suture by analyzing histories, intraoral radiographs, orthopantomographs, intraoral slide films, and dental casts. The data for this study were compiled from 500 outpatients of the Department of Orthodontics, Infirmary of Dental College, Seoul National University. The following conculusions were obtained: 1. The occurrence of maxillary interincisal diastema in the permanent dentition decreased rapidly compared with that in the mixed dentition. And there was no sex difference in the occurrence of diastema in the both dentitions. 2. Frenum attachment remained relatively constant between the two dentitions but assumed a higher level in the permanent dentition than in the mixed dentition. 3. Except suture type D which was not yet fused completely, there was no significant difference in the distribution of suture type between the mixed dentition and the permanent dentition. 4. Frenum and suture type were highly related; frenum types 5 and 6 were associated with suture types III and V. 5. In the permanent dentition, frenum type 5 and 6 and suture types III and IV occurred more frequently in the spacing group than in the normal or crowding group. 6. The relationship between the diastema and frenum types 5 and 6 and sture types III and IV showed a strong correlation.

• The Korean Journal of Ecology
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• v.13 no.4
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• pp.285-295
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• 1990

Floristic composition and soil properties were analyzed in red pine($Pinus densiflora$) communities in the limestone areas. Tanyang, Ch ungbuk Province in Korea. The tree layer was composed of $Juniperus rigida, Quercus dentata, Q. mongolica$ and others as well as $P. densiflora$, all of which also appeared in soils of grinite origin The shrub layer was dominated by $Q. dentata, Lespedeza cyrtobotrya, Securinega suffruticosa, Abelia coreana$ and $Uimus davidiana$ for $suberosa$. Among these $A. coreana$ and $U. davidiana$ for $suberosa$ belonged to calcicole plant. The herb layer dominated by $Carex lanceolata$. Soil pH ranged 7.9-8.3. Total nitrogen and available phosphorus content of the soil were lower than those of noncalcareous soils. However, exchangeable calcium and magnesium content were 10 times and 2~3 times greater than those of noncalcreous soils, respectively. The difference of soil texture between top soil(loam soil) and subsoil(sand soil), and higher soil organic matter content than noncalcareous red pine forest soils seemed related to the casts forming activities of earthworms.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.293-298
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• 2012

The purpose of this study is performance validation of district heating apartments about heating energy consumption and analysis of energy consumption by unit characteristics. The heating energy consumption of the existing apartments was analyzed and the analyzed results will be used for energy saving technology development and policy making. The heating energy consumption data about total 78 apartment complexes, 56,910 units in Gangnam-Gu, Seoul, Korea were investigated from October, 2010 to April 2011. The analysis results are as follows; The mean heating energy consumption is 98[kWh/m2]. The energy consumption of Apgujung-Dong, Daechi-Dong is higher than that of mean valuse. The energy consumption deviation by deterioration, unit area, core type and regional group is very high. Specially, building deterioration casts a long shadow.

• Journal of Chest Surgery
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• v.30 no.4
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• pp.437-440
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• 1997

A case of inflammatory pseudotumor of the entire lung In a 61-ycar-old man is prcscntcd. The respiratory symptoms developed 2 months ago and progressed rapidly and the diagnosis of chronic pneumonia with ateletectasis of the entire lung, destroyed lung by tuberculosis and sepsis hAd to be ruled out The operative finding was different from our expectation. This case suggests that the Inflammatory pseudotumor can manifest as a whole lung-involving ass. Inflammatory pseudotumor is a nonneoplastic reactive pulmonary mass lesion that resembles tumor but shows little or no growth. Thc inflammatory pseudotufor usually present as a solitary round lung mass but in this casts progressed rapidly and destroyed the whole lung, which is rare. The patient was discharged with no problem and with outpatient followup.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.324-328
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• 2002

Semi-Solid Diecasters usually carry out the Semi-Solid diecasting experiments before producing new casts. At the Semi-Solid diecasting stages, the runner-gate part has been always repeatedly corrected, which leads to a tedious processing time and increased processing cost. A large amount of experience is essential in manual assessment and if the design is defective, much time and a great deal of efforts will be wasted in the modification of the die. In this study, design system has been developed based on design database. In addition, gate experiment for gating system design has been carried out to append the database. It is possible for engineers to make efficient gating system design of Semi-Solid diecasting and it will result in the reduction of expenses and time to be required. The detailed contents of the research are described in the followings. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FVM softwares, MAGMAsoft, to form a useful package.

• Korean Journal of Veterinary Pathology
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• v.2 no.2
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• pp.147-151
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• 1998

A five-month old female Great Dane with a history of depression and convulsion was submitted to the Pathology and Diagnosis Reference Division of National Veterinary Research and Quarantine service. The dog had ingested concentrated antifreeze and died 12 days after the sudden onset of clinical signs. Main gross lesion was limited to swollen kidneys with diffusely fine granularity on the cut surface. Principle microscopic lesions were focused on the kidneys including dilated Bowman's space, thickened glomerular basement membrane, many light yellowish crystals, and proteinaceous casts in some tubules. Some neutrophils and lymphocytes were focally infiltrated in interstitium of the cortex and medulla. Crystals were angular or quite irregular in shape and arranged in sheave or rosette form. Under polarized light, the crystals were birefringent, which is typical of calcium oxalate crystals. Crystals were more concentrated in the cortex than in the medulla. A few crystals were also observed in the small blood vessels of the brain. Based upon the history of ingestion of antifreeze and the identification of calcium oxalate crystals in the tissue sections of the kidney and brain, this case was diagnosed as ethylene glycol toxicosis in a dog.

• Journal of Korea Foundry Society
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• v.13 no.5
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• pp.450-461
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• 1993

AC4C alloy casts in the metallic mold, zircon sand mold, silica sand mold and shell mold with the pouring temperatures of 680, 710 and $740^{\circ}C$ have been investigated. The tensile strength, elongation and hardness of AC4C alloy castings have been influenced by the kind of molds used. The mechanical properties in zircon sand mold castings were greater than those in other sand mold castings, but were inferior to the properties in metallic mold castings. Eutectic Si particle size and DAS were increased in the order of metallic mold, ziron sand mold, silica sand mold and shell mold. Also, they were increased with the increase of pouring temperatures. DAS, eutectic Si particle size and grain size decreased with the increase of mechanical properties as the cooling rate increased. The eutectic Si particle size and DAS of AC4C alloy castings after T6 treatment were decreased in as-cast. The variation of eutectic Si particle size has been effected on the tensile strength, elongation and fractured surface.

• The korean journal of orthodontics
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• v.45 no.6
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• pp.275-281
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• 2015

Objective: To assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models. Methods: Cone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by Student's t-test. Results: The mean discrepancies in maxillary and mandibular crown positions were $0.376{\pm}0.041mm$ and $0.398{\pm}0.037mm$, respectively. Maxillary and mandibular root positions differed by $2.062{\pm}0.128mm$ and $1.941{\pm}0.154mm$, respectively. Conclusions: Crowns but not roots of anterior teeth can be moved to designated positions using clear aligners, because these appliances cause tooth movement by tilting motion.