• 대한치과교정학회지
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• 제29권3호
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• pp.375-381
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• 1999

본 연구는 상악궁이 양측성으로 협소하여 구치부 교차 교합을 보이는 환자 30 명에서 정중구개봉합 급속 확장술을 시행한 후, 정모두부방사선 규격 사진을 이용하여 상악골 기저부의 횡적 확장 여부를 확인하고, 그 양을 정량적으로 계측하여 상하악골 횡적 부조화의 개선 정도를 평가하여 다음과 같은 결과를 얻었다. 1. 정중구개봉합 급속 확장술을 시행한 경우 남녀 모두 각각 상악골 기저부의 유의성 있는 증가를 보였다. (P<0.001) 2. 정중구개봉합 급속 확장술을 시행한 후 확장량에 있어서 남녀간 유의성 있는 차이를 보이지 않았다. 3. 정중구개봉합 급속 확장술을 시행한 경우 사춘기 이전과 사춘기 이후 모두 각각 상악골 기저부의 유의성 있는 증가를 보였다. (P<0.001) 4. 정중구개봉합 급속 확장술을 시행한 후 확장량에 있어서 사춘기 이전과 이후 간에 유의성 있는 차이를 보이지 않았다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제37권
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• pp.11.1-11.5
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• 2015

Rapid palatal expansion(RPE) with the tooth-born appliance is not sufficient to apply to the patients with periodontal problem or insufficient tooth anchorage, and it leads to tipping of the anchorage teeth and increasing teeth mobility and root resorption. To avoid these disadvantages, we present the case using palatal screws and custommade palatal expander. A 23-year-old patient underwent surgically assisted rapid maxillary expansion with the Hyrax expansion using 4 tent screws. The study models were used to measure the pre-/-post surgical width of the anterior and posterior dental arches with a digital sliding caliper. In the result, the custom-made palatal expander with 4 tent screws is suitable for delivering a force to the mid-palatal suture expansion. And it is low cost, small sized and simply applied. The results indicated that maxillary expansion with the custom-made palatal anchorage device is predictable and stable technique without significant complications in patients.

• 대한치과교정학회지
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• 제21권2호
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• pp.447-455
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• 1991

This research was carried out in order to study the effects of Rapid Maxillary Expansion on maxilla and it's surrounding skeletal structures. The sample for this study consists of 14 patients who were in retention period after rapid maxillary expansion. Following results were obtained after performing comparative analysis of cephalograms taken before and after rapid maxillary expansion. 1. In almost every cases, inferior displacement of palatal planes with concurrent changes in their inclination were observed. 2. Changes in the inclination of palatal plane can be categorized into inferiorty inclined group, superiorly inclined group and constant group in relation to the states before rapid masillary expansion. 3. Decrease in < Se-FMN/PMV and increase in < Se-FMN-A were evident in the superiorly inclined group and vice versa for the inferiorly inclined group.

• 대한치과교정학회지
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• 제52권3호
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• pp.182-200
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• 2022

Objective: This study aims to examine the effectiveness of miniscrew assisted rapid palatal expansion (MARPE) treatment in late adolescents and adult patients using cone-beam computed tomography (CBCT). Methods: Literature search was conducted in five electronic databases (PubMed, Embase, Scopus, Web of Science, and Cochrane Library) based on the PICOS keyword design focusing on MARPE. Out of the 18 CBCT screened outcomes, only nine parameters were sufficient for the quantitative meta-analysis. The parameters were classified into three main groups: 1) skeletal changes, 2) alveolar change, and 3) dental changes. Heterogeneity test, estimation of pooled means, publication bias, sensitivity analysis and risk of bias assessment were also performed. Results: Upon database searching, only 14 full-text articles were qualified from the 364 obtained results. Heterogeneity test indicated the use of the random-effects model. The pooled mean estimate were as follows: 1) Skeletal expansion: zygomatic width, 2.39 mm; nasal width, 2.68 mm; jugular width, 3.12 mm; and midpalatal suture at the posterior nasal spine and anterior nasal spine, 3.34 mm and 4.56 mm, respectively; 2) Alveolar molar width expansion, 4.80 mm; and 3) Dental expansion: inter-canine width, 3.96 mm; inter-premolar width, 4.99 mm and inter-molar width, 5.99 mm. The percentage of expansion demonstrated a skeletal expansion (PNS) of 55.76%, alveolar molar width expansion of 24.37% and dental expansion of 19.87%. Conclusions: In the coronal view, the skeletal and dental expansion created by MARPE was of the pyramidal pattern. MARPE could successfully expand the constricted maxilla in late adolescents and adult patients.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.45-51
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• 2000

Investigators who study on combustion in the cylinders of reciprocating piston type internal combustion engines have been encountered embarrassments due to the difficulties of adjusting specific parameter without interfacing other parameters such as cylinder wall temperature composition of gas in the cylinder existence of cylinder lubricant etc. Rapid compression-expansion machine the position and speed of piston of which are able to be controlled by means of a system controlled electrically and speed of piston of which are able to be controlled by means of a system controlled electrically and actuated hydraulically could be utilized as one of the most preferable countermeasures against those difficulties. Several units of rapid compression-expansion machines were developed but the speed up of frequency of piston movement still is the problem to be improved to cope with actual speed of internal combustion engines. Authors designed and manufactured a new rapid compression-expansion machine electrically controlled hydraulically actuated and computer programed and then examined the performance of one. Results of a set of experiments revealed acquirements of certain improvement of frequency of piston movement preserving the stability of system response and reproducing accurate compression ratio of cylinder those are the key function for the in-cylinder combustion experiments of internal combustion engines.

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.69-75
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• 2000

Investigators who study on combustion in the cylinders of reciprocating piston type internal combustion engines have been encountered embarrassments due to the difficulties of adjusting specific parameter without interfacing other parameters such as cylinder wall temperature, composition of gas in the cylinder, existence of cylinder lubricant etc. Rapid compression expansion machine, the position and speed of piston of which are able to be controlled by means of a system controlled electrically, and actuated hydraulically could be utilized as one of the most preferable countermeasures against those difficulties. Several units of rapid compression expansion machines were developed but the speed up of frequency of piston movement still is the problem to be improved to copy with actual speed of internal combustion engines. Authors designed and manufactured a new rapid compression-expansion machine electrically controlled, hydraulically actuated, and computer programed and then examined the performance of one. Results of a set of experiments revealed acquirements of certain improvement on frequency of piston movement preserving the stability of system response and reproducing accurate compression ratio of cylinder, those are the key function for the in-cylinder combustion experiments on internal combustion engines.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.83-90
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• 2004

A flywheel-driven rapid compression and expansion machine is developed and utilized for experimental study of homogeneous charge compression ignition combustion. Compression ignition of homogeneous charge in IC engines offers possibilities of realizing ultra-lean engine operation with greatly reduced NOx and particulate formation. Fundamental investigations are carried out in order to better understand this ideal engine combustion mechanism. Perfectly premixed propane-air mixtures of various equivalence ratio are compression-ignited in the rapid compression and expansion machine, and the characteristics of the auto-ignition and the following combustion process are analyzed.

• KDI Journal of Economic Policy
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• 제39권2호
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• pp.1-23
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• 2017

Korea's rapid export expansion suddenly began in the early 1960s and boosted the economy. This paper's investigation finds that it began in 1961, as new export items appeared, export of which increased incomparably faster than that of the current export items at the time. How and why of this highly unusual phenomenon can best be explained by a major reform of foreign exchange system in February 1961. This goes against the widely held view that the switch in development policy from import substitution to export promotion in the mid-1960s was the reason for Korea's export success. Rather, the evidence indicates that the rapid export expansion led to the policy switch. The government's export promotion since the policy switch helped the rapid export expansion continue into the 1970s, despite the protectionist import policy.

• 대한치과교정학회지
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• 제31권6호
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• pp.611-618
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• 2001

중등도 내지는 심한 총생과 회전이 있는 12.5세 여자 환자의 증례에 대한 보고이다. 발치를 하지 않고, 상하악 치열궁의 확장에 의해 치료하였다. 구치부의 반대교합이 없었지만, 상악의 경우 급속구개확장을 시행하였다. 양악의 총생과 치아 회전이 해소되었으며, 교합기능과 안모 심미의 개선을 이루었으며, 적절한 수평 및 수직 피개교합을 이룩하였다. 최근에 많이 사용되는 구치부 반대교합이 없는 경우에서의 급속구개확장은, 진단학적 기반 및 적응증에 관한 재평가가 필요하다고 생각된다.

• 대한치과교정학회지
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• 제49권3호
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• pp.150-160
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• 2019

Objective: This study aimed to analyze the effect of changing various parameters of the bone-borne rapid palatal expander (RPE) using the finite element method (FEM). Methods: In eight experimental groups, we investigated the effect of the number, position, and length of miniscrews; positional changes of the expander; and changes in the hook length on maxillary expansion. In finite element analysis, we compared the magnitude and distribution of stress, and the displacement changes following expansion of the bone-borne RPE. Results: When we compared the number and position of miniscrews, placing miniscrews in the anterior and posterior sides was advantageous for maxillary expansion in terms of stress distribution and displacement changes. Miniscrew length did not significantly affect stress distribution and displacement changes. Furthermore, anteroposterior displacement of the expander did not significantly affect transverse maxillary expansion but had various effects on vertical changes of the maxilla. The maxilla rotated clockwise when the miniscrews were placed in the anterior region. The hook length of the expander did not show consistent results in terms of changes in stress distribution and magnitude or in displacement changes. Conclusions: The findings of this study suggest that changes in the location and length of the miniscrews and displacement of the bone-borne RPE could affect the pattern of the maxillary expansion, depending on the combination of these factors.