• 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.

• 국제초고층학회논문집
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• 제4권2호
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• pp.117-125
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• 2015

A vertical city with multifunctional land use turns out to be the most viable solution for an urban condition characterized by increasing density due to population expansion, topographical limitation of buildable land, economic development and the pursuit for collective sustainable living, such as in Hong Kong. This paper presents initial research results from a study on the chronological and typological evolution of tall buildings in the city, from the climate-responsive verandah typology to the mixed-use hyper-commercial podium and residential tower typologies that predominate today, to the ultimate formation of a vertical city. Case studies and surveys have focused on the development of this building typology throughout the decades since the 1920s, substantiating a discussion on the subjective and objective factors contributing to a genesis of the vertical city phenomenon in Hong Kong. The discussion will engage, under the notion of the vertical city, on how residents and visitors adapt to the growing density of the city, and how they accustom themselves to the changing urban morphology over time. Advantages such as high efficiency, spaces savings, time convenience, etc.; and disadvantages such as deficiency in livability, incompatibility of uses, environmental health deficiencies, etc.; serve as a reference for other cities in need of high-density planning due to population and economic growth.

• Clinical and Experimental Reproductive Medicine
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• 제31권2호
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• pp.105-110
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• 2004

Objectives: Despite severe oligospermia, males with Y chromosome microdeletion can achieve conception through ICSI (Intracytoplasmic Sperm Injection). However, ICSI may not only result in the transmission of microdeletions but also the expansion of deletion to the offspring. The purpose of this study was to screen vertical transmission, expansion of microdeletions and de novo deletion in male fetuses conceived by ICSI. Materials and Methods: A total of 32 ICSI treated patients with their 33 (a case of twin) male fetuses conceived by ICSI were used to make this study group. Sequence-tagged sites (STSs)-based PCR analyses were performed on genomic DNA isolated from peripheral blood of fathers and from the amniocytes of male fetuses. Ten primer pairs namely, sY134, sY138, MK5, sY152, sY147, sY254, sY255, SPGY1, sY269 and sY158 were used. The samples with deletions were verified at least three times. Results: We detected a frequency of 12.5% (4 of the 32 patients) of microdeletions in ICSI patients. In 4 patients with detected deletions, two patients have proven deletions on single STS marker and their male fetuses have the identical deletion in this region. Another two patients have two and three deletions, but their male fetuses have more than 3 deletions which include deletions to their father's. Meanwhile, seven male fetuses, whose fathers were analyzed to have all 10 STS markers present, have deletions present in at least one or more of the markers. Conclusions: Although the majority of deletions on the Y chromosome are believed to arise de novo, in some cases a deletion has been transmitted from the fertile father to the infertile patient. In other cases the deletion was transmitted through ICSI treatment, it is likely that one sperm cell is injected through the oocyte's cytoplasm and fertilization can be obtained from spermatozoa. Our tests for deletion were determined by PCR and our results show that the ICSI treatment may lead to vertical transmission, expansion and de novo Y chromosome microdeletions in male fetuses. Because the sample group was relatively small, one should be cautious in analyzing these data. However, it is important to counsel infertile couples contemplating ICSI if the male carries Y chromosomal microdeletions.

• 대한생식의학회:학술대회논문집
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• 대한불임학회 2003년도 제45차 추계학술대회
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• pp.81.2-82
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• 2003

• 대한치과교정학회지
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• 제48권2호
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• pp.98-106
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• 2018

Objective: This study aimed to explore the usefulness of adjunctive buccal and palatal corticotomy for adult maxillary expansion in an animal model using cone-beam computed tomography (CBCT). Methods: Twelve adult sheep were randomly divided into two groups (each n = 6): a control group, where no treatment was administered, and a treatment group, where buccal and palatal corticotomy-assisted maxillary expansion was performed. CBCT scans were taken before (T1) and after (T2) treatment. Differences in all transverse dental and alveolar dimensions, alveolar width at crest level, hard palate level, horizontal bone loss, interdental cusp width and inter-root apex were assessed using Wilcoxon signed-rank and Mann-Whitney U-tests. Kruskal-Wallis tests and pairwise comparisons were used to detect the significance of differences among the inter-premolar and inter-molar widths. Results: CBCT data revealed significant changes in all transverse dental and alveolar dimensions. The mean interpremolar alveolar width showed an increase of 2.29 to 3.62 mm at the hard palate level, 3.89 to 4.38 mm at the alveolar crest level, and 9.17 to 10.42 mm at the buccal cusp level. Dental changes in the vertical dimension were not significant. Conclusions: Our findings based on an adult animal model suggest that adjunctive buccal and palatal corticotomy can allow for both skeletal and dental expansion, with the amount of dental expansion exceeding that of skeletal expansion at alveolar crest and hard palate levels by two and three folds, respectively. Therefore, this treatment modality is potential to enhance the outcomes of maxillary expansion in adults.

• 한국음향학회지
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• 제41권4호
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• pp.389-396
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• 2022

본 논문은 냉장고 수축팽창 소음의 원인 및 메커니즘을 파악하고 소음 감소 방법을 제안한다. 냉장고에서 발생하는 수축팽창 소음은 주로 내부부품 사이의 접촉면에서 발생하는 스틱슬립 현상에 의한 것이다. 스틱슬립 현상을 일으키는 요인을 규명하기 위해 마찰실험이 수행되었다. 또한 내부부품의 진동레벨을 측정하여 수축팽창 소음의 특성 및 위치를 규명하였다. 실험 결과를 바탕으로 요인별 소음 특성을 검증하는 실험이 진행되었다. 이를 통해 마찰실험과 냉장고 수축팽창 소음 발생 위치와 빈도가 동일한 것을 확인하였다. 하중적재로 수직력이 증가하면 진동레벨도 증가하였다. 또한 표면거칠기를 증가하였을 때 수축팽창 소음이 저감되는 것으로 확인되었다. 따라서, 마찰실험 결과와 동일하게 접촉면의 표면거칠기를 증가하는 것이 수축팽창 소음저감 방법이라는 결론을 도출하였다.

• 대한치과교정학회지
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• 제52권2호
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• pp.131-141
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• 2022

Objective: The purpose of this study was to compare the differences in dentoskeletal and soft tissue changes following conventional tooth-borne rapid maxillary expansion (RME) between adolescents and adults. Methods: Dentoskeletal and soft tissue variables of 17 adolescents and 17 adults were analyzed on posteroanterior and lateral cephalograms and frontal photographs at pretreatment (T1) and after conventional RME using tooth-borne expanders (T2). Changes in variables within each group between T1 and T2 were analyzed using Wilcoxon signed-rank test. Mann-Whitney U test was used to determine the differences in the pretreatment age, expansion and post-expansion durations, and dentoskeletal and soft tissue changes after RME between the groups. Spearman's correlation between pretreatment age and transverse dentoskeletal changes in the adolescent group was calculated. Results: Despite similar amounts of expansion at the crown level in both groups, the adult group underwent less skeletal expansion with less intermolar root expansion after RME than the adolescent group. The skeletal vertical dimension increased significantly in both groups without significant intergroup difference. The anteroposterior position of the maxilla was maintained in both groups, while a greater backward displacement of the mandible was evident in the adult group than that in the adolescent group after RME. The soft tissue alar width increased in both groups without a significant intergroup difference. In the adolescent group, pretreatment age was not significantly correlated with transverse dentoskeletal changes. Conclusions: Conventional RME may induce similar soft tissue changes but different dentoskeletal changes between adolescents and adults.

• 대한기계학회논문집
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• 제16권1호
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• pp.142-155
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• 1992

본 연구에서는 실제 빙축열 시스템의 해석을 위한 기초 모델로서 수직원관 주 위의 응고과정에 대하여 밀도차와 자연대류 효과 및 최대 밀도점을 나타내는 밀도-온 도 관계식을 도입한 수치해석과 실험을 통하여 여러가지 매개변수들이 상변화에 미치 는 영향을 알아 보았다.

• 한국지구과학회지
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• 제32권5호
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• pp.453-460
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• 2011

By performing a statistical change-point analysis of activities of the tropical cyclones (TCs) that have affected Korea (K-TCs), it was found that there was a significant change between 1983 and 1984. During the period of 1984-2004 (P2), more TCs migrated toward the west, recurved in the southwest, and affected Korea, compared to the period of 1965-1983 (P1). These changes for P2 were related to the southwestward expansion of the subtropical western North Pacific high (SWNPH) and simultaneously elongation of its elliptical shape toward Korea. Because of these changes, the central pressure and lifetime of K-TC during P2 were deeper and longer, respectively, than figures for P1. This stronger K-TC intensity for P2 was related to the more southwestward genesis due to the southwestward expansion of the SWNPH. The weaker vertical wind shear environment during P2 was more favorable for K-TC to maintain a strong intensity in the mid-latitudes of East Asia.

• 음성과학
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• 제11권4호
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• pp.199-206
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• 2004

This paper attempts to provide a substantial explanation of different prosodic implementations on segments in English and Spanish, arguing that the phonetic modification invoked by prosody may effectively reflect phonological structure. In English, a high front vowel in accented syllables is acoustically realized as higher F1 and F2 frequencies than in unaccented syllables, due to its more peripheral and sonorous articulation (Harrington et al. 1999). In this paper, an acoustic experiment was conducted to see if such a manner of segmental modification invoked by prosody in English extends to other languages such as Spanish. Results show that relatively more prominent syllables entail higher F1 values as a result of their more sonorous articulation in Spanish, but either front or back vowel does not show a higher F2 or a lower F2 frequency. This is interpreted as an indication that a prosodically prominent syllable entails its vocalic enhancement in both horizontal and vertical dimensions of articulation in English. In Spanish, however, only the vertical dimensional articulation is maximized, resulting in a higher F1. I suggest that this difference may be attributed to the different phonological structures of vowels in English and Spanish, and that sonority expansion alone would be sufficient in the articulation of prosodic prominence as long as the phonological distinction of vowels is well retained.