• Structural Engineering and Mechanics
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• 제87권2호
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• pp.165-172
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• 2023

This paper presents a novel method for modeling elastic wave propagation in long beams. The proposed method derives a solution for the transient transverse displacement of the beam's neutral axis without assuming the separation of variables (SV). By mapping the governing equation from the space domain to the frequency domain using Fourier transformation (FT), the transverse displacement function is determined as a convolution integral of external loading functions and a combination of trigonometric and Fresnel functions. This method determines the beam's response to general loading conditions as a linear combination of the analytical response of a beam subjected to an abrupt localized loading. The proposed solution method is verified through finite element analysis (FEA) and wave propagation patterns are derived for tone burst loading with specific frequency contents. The results demonstrate that the proposed solution method accurately models wave dispersion, reduces computational cost, and yields accurate results even for high-frequency loading.

• Imaging Science in Dentistry
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• 제34권1호
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• pp.7-12
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• 2004

Purpose: To investigate the anatomical structure of the incisive canal radiographically by a cone beam computed tomography. Materials and Methods: 38 persons (male 26, female 12) were chosen to take images of maxillary anterior region in dental CT mode using a cone beam computed tomography. The tube voltage were 65, 67, and 70kVp, the tube current was 7 mA, and the exposure time was 13.3 seconds. The FH plane of each person was parallel to the floor. The images were analysed on the CRT display. Results: The mean length of incisive canal was 15.87 mm±2.92. The mean diameter at the side of palate and nasal fossa were 3.49 mm±0.76 and 3.89 mm± 1.06, respectively. In the cross-sectional shape of incisive canal, 50% were round, 34.2% were ovoid, and 15.8% were lobulated. 87% of incisive canal at the side of nasal fossa have one canal, 10.4% have two canals, and 2.6% have three canals, but these canals were merged into one canal in the middle portion of palate. The mean angles of the long axis of incisive canal and central incisor to the FH plane were 110.3°±6.96 and 117.45°±7.41, respectively. The angles of the long axis of incisive canal and central incisor to the FH plane were least correlated (r= 0.258). Conclusion : This experiment suggests that a cone beam computed radiography will be helpful in surgery or implantation on the maxillary incisive area.

• 한국실내디자인학회논문집
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• 제22권6호
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• pp.151-161
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• 2013

This study which analyzed 4th century Constantinus basilica church architecture is on how the Roman basilica architecture became to christianized and christian architecture became romanized. Basilica architecture of Rome which has strong public characteristic had approach from various direction, especially it has formed inter communicable open space to center forum. Even though, the early christian church has became to bigger size on the process of domus ecclesia centered growth, but it has formed essencially unhierarchy community of home based, it also seemed to have loose religious community below hundred. The result of analyzing 22 of 4 century basilica churches had been shown that more than 60% of them were built on historical place such as tomb of martyr, nearly 70% of them were long axis type, the size of church showed up $3,200m^2$ of average total area. In conclusion, this study concluded the result of christianized showed closeness pursue holiness by separation from the secular world, and long axis it was revealed as mass for the procession ceremony of catholic church. The result of romanized occurred from the process that the basilica church abandoned the unhierarchy, small sizing, worship simplicity of early domus ecclesia characteristics and accept hierarchy, big sizing, worship formalism and complexity of Roman empire system in the roman basilica churches. Through this study it could be grasp that the romanized of early christianity bring not only the change of church architecture but also degeneration of christian itself.

• 대한기계학회논문집A
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• 제39권12호
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• pp.1297-1303
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• 2015

장축의 내부 크롬도금은 크롬산 용액에 황산을 촉매로 경질의 후막 도금층을 형성시키는 기술로서 산업뿐만 아니라 군사적 목적으로도 널리 사용되고 있다. 대구경의 포신내부에 경질크롬도금을 처리하면 강성과 내마성을 증대시켜 고압의 폭발력에 견딜 수 있다. 탄자의 높은 운동에너지와 탄 폭발로 생긴 고압력에 의해 포신 내부의 크롬도금층이 탈락되는 문제가 있어 도금 공정 전반에 걸친 검토가 이루어졌다. 크롬도금은 탈지, 수세, 전해연마, 에칭, 도금, 수세 및 수소취성제거 등 여러 공정으로 이루어진다. 크롬도금 탈락은 도금의 밀착성과 연관이 있으며, 그 중에 전해연마액의 Fe 농도가 도금 밀착성에 영향을 미치는 것으로 나타났다. 도금부위의 요철상태를 SEM으로 조사하여 도금탈락을 방지할 수 있는 최적의 Fe 농도를 설정하고, 밀착성 시험 등으로 그 효과를 입증하였다.

• 치과방사선
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• 제17권1호
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• pp.151-162
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• 1987

The author obtained the computed tomograms around the condylar head from 10 normal subjects and 5 patients having clicking condylar head from 10 normal subjects and 5 patients having clicking sound or limitation of mouth opening by using a Hitachi-W 500. And then. the author had the axial analysis of condyle position and sagittal analysis of that after sagittal reformation on centric occlusion and 18㎜ interincisal opening. Transcranial view and submentovertex view were taken and compared with computed tomographic view. The obtained results were as follows: 1. Median angle of long axis of condylar head was 17 degrees on centric occlusion and the angles of long axis of both condylar heads were reduced symmetrically on 18㎜ interincisal opening in normal group. however. in the patient group, the affected side of condyle heads showed greater change in the angle on 18㎜ interincisal opening. 2. In the patient group, the condyle head of affected side was located superiorly to that of normal side on centric occlusion and the discrepancy of condular positional height was increased after 18㎜ interincisal opening. 3. The distances from medial pole of condylar head to triangular fossa of temporal bone were same on both right and left side in normal group, however, in the patient group, the distance of affected side was wider than that of opposite side on centric occusion and became narrower than the opposite side on 18㎜ interincisal opening. 4. The distances of posterior joint space were same on both right and left side. The distance t lateral pole 1/3 of condyle head was similar to that on transcranial view on centric occlusion in normal group. 5. The distances of posterior joint space were narrower in patient group than in normal group. 6. Conclusively, the affected condylar head of patient showed postero-latero-superior displacement on centric occlusion and larger range of rotational movement on 18㎜ interincisal opening.

• Archives of Plastic Surgery
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• 제32권4호
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• pp.521-528
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• 2005

The purpose of this research is to find out the degree of cartilage regeneration by inserting the atelo-collagen scaffold obtained from dermis of a calf on cartilage defect site. Dissection underneath the perichondrium by the periosteal elevator on both side of ears of six New Zealand white rabbits were made to expose the cartilage, leaving pairs of circular holes 3, 6, 9 mm width with punches. One hole was left for a control, and on the other hole atelo-collagen scaffold of the same size was transplanted. In postoperative 1, 2, 4 weeks, the tissues were dyed. The length of long axis of neocartilage was measured through an optical microscope with a 0.1 mm graduation at original magnification, ${\times}40$. In the first and second week, both group showed no sign of cartilage regeneration. In the fourth week, regeneration on marginal portions was observed on all groups and the average values of length of long axis of neocartilage according to defect size were as follows: In the cases with 3mm defect, it was $0.85{\pm}0.30mm$ in the control group, and $1.85{\pm}0.38mm$ in the graft group; in the cases with 6 mm defect, $1.33{\pm}0.58mm$ in the control group, and $2.25{\pm}0.46mm$ in the graft group; and in the cases with 9 mm defect, $2.33{\pm}0.77mm$ in the control group, and $4.47{\pm}1.39mm$ in the graft group. This means that the collagen scaffold has an influence on the regeneration of neocartilage. But the relative ratio of the length of neocartilage to cartilage defect size was not significant in the statistics.

• 대한치과교정학회지
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• 제45권4호
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• pp.180-189
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• 2015

Objective: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. Methods: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. Results: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. Conclusions: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

• 대한족부족관절학회지
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• 제10권2호
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• pp.242-246
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• 2006

Purpose: Frequency of sesamoid bone on hallucal interphalangeal joint has been described to be low probability in orthopaedic and anatomical literature. We have, however, experienced two cases of interphalangeal joint dislocation giving difficulty to usual manipulative reduction because of presence of sesamoid bone recently. In order to ascertain existence of sesamoid bone on interphalangeal joint of hallux in Korean adults, radiological study have been performed with feet of patients Materials and Methods: Between May 2003 and October 2006, 974 patients with 1098 radiographs of feet which were reached skeletal maturity over 18-year-old were examined. Unilateral or bilateral anteroposterior, lateral and oblique radiographs were observed by one same person and presence was recorded if there was sesamoid in films. Distance of long and short axes were measured in lateral view and cases of two sesamoids in interphalangeal joint were recorded. Statistical differences between left and right side or between men and women were evaluated by chi-square test. Results: Frequency of sesamoid was 980 cases (89.3%) and no occurrence in 118 cases (10.7%). Two sesamoids were observed in 3 cases. Average distance of long axis was 4.9 mm (range, 0.5-11.4) and average distance of short axis was 3.5 mm (range, 0.3-9.3). Unilateral sesamoid was observed in 7 patients (5.6%), bilateral absence was 7 patients (5.6%) and bilateral sesamoids in 110 patients (88.8%) out of 124 patients who took bilateral feet radiographs. Men has less frequency than women significantly (p=0.014) while there was no significant difference in frequency according to side(p>0.05). Conclusion: Sesamoid bone was seen in 980 feet (89.3%) out of 1098 normal Korean radiological studies of feet. We report 3 cases of two seamoids which was extremely rarely reported in literature. Korean frequency is similar with Japanese, but much higher than Caucasians and black Africans.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.177-178
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• 2006

Many authors issued the feature-preserving averaging technique according to positioning and scaling process using landmarks, which represent the geometric characteristics of three dimensional surface models. Such a technique should be done by manual procedure, choosing and marking the landmarks on each bone surface before averaging process. In this study, we produced another averaging technique without having to use such manual procedure, and made averaging models from three dimensional surface data that were reconstructed from computerized tomography images of Digital Korean Project. The bone models were subjected to orthogonal coordinator system. These models were transformed to coincide mass center and to align principal axis. Then, bone models were scaled according to average length data of sample bone models on all axis(x, y, z). After establishing voxellar hexahedron space which contain all sample bone models, we counted the number of overlapping for each voxel. We generated the three dimensional average surface by displaying the yokels that have more overlapping number than boundary number. The boundary number was decided when the average volume of each bone equal to the volume of bone that would be averaged. Using this technique, we can make a feature-preserving averaging volume of bones.

• 치과방사선
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• 제14권1호
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• pp.135-140
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• 1984

In spite of many projections of TMJ, there are rarely satisfactory projections of TMJ. The author traced and measured the P-A cephalograms, which number is 70 in each male and female, them finding the following results. 1. The long axis of the condyle is 19.80㎜ on the right, and 19.89㎜ on the left in male, and that of 18.65㎜ on the right and 18.10㎜ on the left in female. 2. The intercondylar distance is 119.02㎜ in male, and 108.20㎜ in female, resulting that the intercondylar distance in male is much longer than that in female. 3. The right and left deviation of the midline passing through the center of the intercondylar distance and prosthion is +0.37㎜ in male, +0.64㎜ in female, and its range is from -4.6 to +5.7㎜ in male, and from -3.2 to +6.1㎜ in female, resulting that prosthion nearly coincides with midline. 4. The angle of the intercondylar distance and the long axis (vertical angle) is +5.48' in male, and +6.02' in female, resulting that there is a little difference between male and female and the angle of the right is greater than that of the left in both male and female. 5. The typology of the condyle in sum of male and female is; Right: A type 55 (39.3%), B type 66 (47.1%), C type, 12 (8.6%), D type, 7 (5.0%), E type, 0 (0%) Left: A type, 60 (42.9%), B type, 58 (41.4%), C type, 14 (10.0%), D type, 8 (5.7%), E type, 0 (0%) 6. The distribution of the typology between the right and the left is; AA 26 (18.6%), AB 50 (35.7%), AC 10 (7.1%), AD 3 (2.1%) BB 26 (18.6%), BC 13 (9.3%), BD 9 (6.4%), CC 0 (0%), CD 3 (2.1%)