• Imaging Science in Dentistry
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• 제38권2호
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• pp.95-101
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• 2008

Purpose: To assess the positional relationship between the maxillary sinus floor and the apex of the maxillary first molar using cone beam computed tomograph (CBCT). Materials and Methods: CBCTs from 127 subjects were analysed. A total of 134 maxillary first molars were classified according to their vertical and horizontal positional relationship to the maxillary sinus floor and measured according to the distance between the maxillary sinus floor and the maxillary first molar. Results: Type III (The root projected laterally on the sinus cavity but its apex is outside the sinus boundaries) was dominated between 10 and 19 years and type I (The root apex was not in contact with the cortical borders of the sinus) was dominated (P<0.05) between 20 and 72 years on the vertical relationship between the maxillary sinus floor and the apex of the maxillary first molar. The maxillary sinus floor was located more at the apex (78.2%) than at the furcation (21.3%) for the palatal root. The distance from the root apex to the maxillary sinus floor confined to type I was increased according to the ages (P<0.05). Type M (The maxillary sinus floor was located between the buccal and the palatal root) was most common (72.4%) on the horizontal relationship between the maxillary sinus floor and the apex of the maxillary first molar. Conclusion: CBCT can provide highly qualified images for the maxillary sinus floor and the root apex of the maxillary first molar.

• 대한소아치과학회지
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• 제31권1호
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• pp.92-97
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• 2004

청소년기에는 두개악안면부위의 외상성 손상이 흔하다. 그러나 상아질, 백악질, 치수를 포함하는 치아파절로 정의 되는 치근파절을 비교적 드물다. 성장기 아동에 있어서 외상으로 인한 손상은 심리적인 위축감, 안모에 대한 열등감 등의 정서적인 문제와 치조골과 안모의 성장이나 치간 간격의 유지에 영향을 미치는 등의 지장을 초래하기 때문에 보존적인 치료가 요구된다. 첫 번째 증례는 9세의 남아로 상악 우측 중절치의 치수노출을 동반한 치관 파절과 치근단부위에 치근의 수평 파절이 관찰되어 치관부 파절편 치수만 제거하고 수산화칼슘을 이용하여 충전하였다. 6개월 후 방사선 사진에서 dentinal bridge의 형성을 확인할 수 있었고 치근단부는 병적 소견 없이 정상적으로 발육되고 있었다. 1년 3개월 후 방사선 사진에서 치근단부의 형성이 완료된 것을 확인하여 gutta percha를 이용하여 영구 충전을 시행하였다. 두 번째 증례는 7세의 여아로 상악 우측 중절치의 치수 노출을 동반한 치근의 수직 파절이 관찰되어 인위적 발거 후 레진 시멘트를 이용하여 파절편 부착 후 재식하였다. 술 후 8개월 동안의 관찰결과 특이한 임상적 증상은 나타나지 않았다. 이상의 증례에서 치근 파절이 발생한 치아에서 보존적 치료를 시행하였고 이에 양호한 결과를 얻었기에 보고하는 바이다.

• 대한소아치과학회지
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• 제43권2호
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• pp.200-206
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• 2016

상아질, 백악질, 치수를 포함하는 파절로 정의되는 치근파절은 영구치에서 발생하는 외상 중 0.5-7%를 차지하며, 대부분 11-20세군의 상악 전치부에 호발한다. 영구치 치근파절의 처치는 기본적으로 변위된 치관부 파절편을 정복시키고 고정하는 것이다. 60-80%는 치수생활력이 유지되나 치수괴사나 염증성 치근흡수의 징후가 나타난다면 근관치료를 시행하게 되며 대부분에서 치근부 파절편의 치수생활력은 유지되기 때문에 근관치료는 치관부 파절편에 한하여 수행한다. 그러나 치관부 파절편에서 적절한 apical stop을 얻는 것은 어렵다. 의도적 재식술이란 통제된 환경에서 의도적으로 치아를 발거한 후 구강 외에서 치근단 치료를 시행하고 재식립하는 방법으로 완벽한 근관치료와 수복을 목표로 한다. 통상적인 근관치료가 실패한 경우, 기존의 수복물이 존재하거나 석회화된 근관으로 인해 재근관치료가 어려운 경우, 공간적으로 접근이 불가능하여 치근단 수술을 시행하지 못하는 증례에서 의도적 재식술이 계획될 수 있다. 본 증례에서는 이전의 외상으로 인해 석회화된 근관을 보이는 상악 중절치에서 발생한 수평 치근파절을 치료하기 위해 의도적 재식술을 이용하였고 임상적, 기능적으로 만족할만한 결과를 얻었기에 이를 보고하는 바이다.

• 대한치과교정학회지
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• 제24권3호
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• pp.649-658
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• 1994

The purpose of this study was to evaluate the association between incisor root resolution and sex, age, extraction, the magnitude and direction of tooth movement. The sample consisted of 189 randomly selected orthodontic patients, receiving standard edgewise orthodontic treatment in three private orthodontic onces at San Francisco. Pre-treatment and post-treatment periapicals and cephalometric radiographs were digitized. Measurements and superimpositions were made utilizing a computerized cephalometric analysis program. The variables were statistically analyzed. The results were as follows: 1. Mean apical root resorption values were $0.77{\pm}2.08mm$ for upper right central incisor, $0.88{\pm}2.11mm$ for upper left central incisor, $-0.05{\pm}2.09mm$ for lower right central incisor and $0.11{\pm}1.85mm$ for lower left central incisor. Apical root resorption of upper incisor was greater than lowers. 2. No correlation was found between sex and apical root resorption. 3. Apical root resorptions in adolescents were smaller than those in adults. 4. Apical root resorption was not affected by extraction. 5. Apical root resorption values of upper incisor were correlated to the horizontal and vertical movement of apex; Apical root resorption values of lower incisor were correlated to the vertical movement of apex.

• Wind and Structures
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• 제16권3호
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• pp.241-248
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• 2013

The wind turbine blade is a very important part of the rotor. Extraction of energy from wind depends on the design of blade. In this work, the analysis is done on a blade of length 38.95 m which is designed for V82-1.65 MW horizontal axis wind turbine (supplied by Vestas). The airfoil taken for the blade is NACA 634-221 which is same from root to tip. The analysis of designed blade is done in flap-wise loading. Two shapes of the spar are taken, one of them is of square shape and the other one is combination of square and cross shape. The blade and spar are of the same composite material. The Finite element analysis of designed blade is done in ANSYS. This work is focused on the two segments of blade, root segment and transition segment. Result obtained from ANSYS is compared with the experimental work.

• 대한물리치료과학회지
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• 제30권3호
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• pp.14-22
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• 2023

Background: This study was to investigate the relationship between scapular downward rotation ratio (SDRR), lower trapezius (LT) muscle, and rounded shoulder angle (RSA) on each side in subjects with scapular downward rotation syndrome (SDRS). Design: Cross-sectional Study Methods: Fifteen subjects have participated in this study. The RSA and SDRR were assessed using a tape measure in standing posture. The RSA was computed by the angle made by two lines: one was the distance between the root of the scapula and the acromion, and the other was the distance between the acromion and the horizontal line in the root of the scapula. The SDRR was computed by two horizontal lines: one was the distance between the mid-line and root of the scapula, and the other was the distance between the mid-line and inferior angle of the scapula. LT muscle strength was performed in a prone position by the hand-held dynamometer. Results: There was a positive correlation between SDRR and LT strength in the less affected sides (r=.59; p=.02), however, there was no correlation between RSA and LT strength in the more affected sides (p>.05).

• 한국조경학회지
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• 제31권6호
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• pp.77-84
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• 2004

This study was carried out to analyze the vertical and horizontal distribution of fine root biomass of Pinus thunbergii transplanted in reclaimed land from the sea near Gwangyang Bay. The fine-root biomass according to 6 planting ground types were as follows: 98.5 g DM/$m^2$ for P2, 51.1 g DM/$m^2$ for P6, 47.8 g DM$m^2$ for P5, 44.6 g DM/$m^2$ for P3, 38.2 g DM/$m^2$ for P4, 31.8 g DM/$m^2$ for Pl, respectively. The vertical distribution of fine root biomass decreased at descending soil depths of the 6 mounding types. Fine root biomass was 31∼55% in the topsoil of 20cm depth. Fine root biomass that were related to the Spatial distance from the nearest tree were unevenly distributed horizontally in 6 stands. distribution patterns of fine root biomass were closely related to soil hardness and alkalic cation (Ca++, Mg++, Na+, K+) concentrations. Therefore, in order to have good condition for the growth of landscaping plants, we suggest that there is a need for the construction of planting grounds as well as a need for soil improvement in bad soil environments.

• Journal of Welding and Joining
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• 제21권3호
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• pp.40-45
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• 2003

The high-speed rotating arc process forms a flat bead surface with decreased penetration depth because the molten droplets are deflected by centrifugal force. Therefore the rotating arc welding for horizontal fillet welding increases the leg length with the increase of rotation frequency and prevents the deflection of weld bead and overlap. In this study, the relationship between the welding parameters and the weld bead shape - leg length and undercut - are investigated experimentally. Consequently, the weld quality could be improved by rotating arc welding, and sound weld bead was achieved when applied to horizontal fillet welding with 4mm gap by avoiding the undercut which is inevitable for the conventional GMA welding methods.

• 대한기계학회논문집A
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• 제41권4호
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• pp.321-327
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• 2017

본 연구에서는 수평 자세에서의 TIG 용접 시 반응표면법(RSM)을 이용하여, 최적의 이면비드 형상을 구하는 연구를 진행하였다. 입력변수로는 베이스 전류, 피크 전류, 용접속도를 선정하였고, 이면비드 폭을 용접품질에 관한 출력변수로 하여 목표값을 5.4 mm로 설정하였다. Box-Behnken 실험계획법에 따라 실험을 진행하였고, 비드 폭에 관한 2차 회귀모형을 구한 후, F-테스트를 이용하여 회귀모델을 검정하였다. 그리고 망목특성의 호감도 함수를 사용하여 이면비드 형상을 평가함으로써 최적화를 수행하였다. 이렇게 도출된 최적의 용접조건은 코드화된 값으로 베이스 전류; 0.9204, 피크 전류; 0.8676, 용접속도; 0.3776이었다. 검증실험 결과 목표값에 근접한 5.38 mm의 이면비드 폭을 얻을 수 있었다.

• Structural Engineering and Mechanics
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• 제30권4호
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• pp.427-444
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• 2008

A mathematical model for the nonlinear dynamics of a rotating beam with flexible root attached to a rotating hub with elastic foundation is developed. The model is developed based on the large planar and flexural deformation theory and the potential energy method to account for axial shortening due to bending deformation. In addition the exact nonlinear curvature is used in the system potential energy. The Lagrangian dynamics and the assumed mode method is used to derive the nonlinear coupled equations of motion hub rotation, beam tip deflection and hub horizontal and vertical displacements. The derived nonlinear model is simulated numerically and the results are presented and discussed for the effect of root flexibility, hub stiffness, torque type, torque period and excitation frequency and amplitude on the dynamic behavior of the rotating beam-hub and on its stability.