• Journal of the Korea Academia-Industrial cooperation Society
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• 제14권2호
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• pp.542-547
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• 2013

In this study, mechanical property on the composite material of aluminum foam core is investigated by simulation analysis. Impact energies such as 50J, 70J, and 100J are applied to the specimen model. The maximum load occurs at 3.4ms for 50J, 3.2ms for 70J, and 3.2ms for 100J respectively. The striker penetrates the upper face sheet, causing the core to be damaged at 50J test but the lower face sheet remains intact with no damage. It results in occurring with the energy of 52 J. At 70J test, it penetrates the upper face sheet and penetrated the core. And the striker causes the lower face sheet with damage. And it results in occurring with the energy of 65 J. Finally at 100J test, the striker penetrated both the upper face sheet and core and even the lower face sheet. The load becomes maximum at the time when striker penetrates through the upper plate and it rapidly reduced. And then the load increases rapidly when reaching the lower face sheet. And it decreases again. It results in occurring with the energy of 95 J.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권2호
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• pp.149-157
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• 2009

Purpose: This study was to evaluate the validity of superimposition range at facial images constructed with 3-dimensional (3D) surface laser scanning system. Materials and methods: For the present study, thirty adults, who had no severe skeletal discrepancy, were selected and scanned twice by a 3D laser scanner (VIVID 910, Minolta, Tokyo, Japan) with 12 markers placed on the face. Then, two 3D facial images (T1-baseline, T2-30 minutes later) were reconstructed respectably and superimposed in several manners with $RapidForm^{TM}2006$ (Inus, Seoul, Korea) software program. The distances between markers at the same place of face were measured in superimposed 3D facial images and measurement were done all the 12 makers respectably. Results: The average linear distances between the markers at the same place in the superimposed image constructed by upper 2/3 of the face was $0.92{\pm}0.23\;mm$, in the superimposed image constructed by upper 1/2 of the face was $0.98{\pm}0.26\;mm$, in the superimposed image constructed by upper 1/3 of the face and nose area was $0.99{\pm}0.24\;mm$, in the superimposed image constructed by upper 1/3 of the face was $1.41{\pm}0.48\;mm$, and in the superimposed image constructed by whole face was $0.83{\pm}0.13\;mm$. There were no statistically significant differences in the liner distances of the makers placed on the area included in superimposition range used for partial registration methods but there were significant differences in the linear distances of the markers placed on the areas not included in superimposition range between whole registration method and partial registration methods used in this study. Conclusion: The results of the present study suggest that the validity of superimposition is decreased as superimposition range is reduced in the superimposition of 3D images constructed with 3D laser scanner for the same subject.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권3호
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• pp.288-297
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• 2005

Rehabilitation of the paralyzed face as a result of trauma or surgery remains a daunting task. Complete restoration of emotionally driven symmetric facial motion is still unobtainable, but current techniques have enhanced our ability to improve this emotionally traumatic deficit. Problems of mass movement and synkinesis still plague even the best reconstructions. The reconstructive techniques used still represent a compromise between obtainable symmetry and motion at the expense of donor site deficits, but current techniques continue to refine and limit this morbidity. In chronically paralyzed face, direct nerve anastomosis, nerve graft, or microvascular-muscle graft is not always possible. In this case, regional muscle transposition is tried to reanimate the eyelid and lower face. Regional muscle includes maseeter muscle, temporalis muscle and anterior belly of the digastric muscle. Temporalis muscle is preferred because it is long, flat, pliable and wide-motion of excursion. In order to reanimate the upper and lower eyelid, Upper eyelid Gold weight implantion and lower eyelid shortening and tightening is mainly used recently, because this method is very simple, easy and reliable.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• 제25권2호
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• pp.459-470
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• 1995

The purpose of this study was to determine whether any difference existed in craniofacial morphology between cleft children and normal subjects. Thirty three measurements of the various regions of cranium and face were obtained from lateral cephalometric radiograms in 40 cleft children(27 males, 13 females) and 40 normal subjects(23 males, 17 females) in our dental hospital from Jan. 1988 to Dec. 1995.The measurements were compared with those in control subjects who had no history of craniofacial abnormalities. The obtained results were as follows: 1. In the cranium, the cleft children had singificantly shorter posterior cranial base length(S-Ba) and total antero-posterior cranial base length(N-Ba) (P<0.05). 2. In the upper face, the cleft children had significantly shorter upper anterior facial height(N-ANS) and upper posterior facial height(Ptm'-SNL) (P<0.05). 3. In the lower face, the cleft children had significantly shorter antero-posterior mandibular length(Pog-Ar) and antero-posterior mandibular body length(Pog-Go) (P<0.05). 4. In the facial profile, the cleft children had significantly shorter total facial height(N-Me} and posterior facial height(S-Go) (P<0.05).

• Geomechanics and Engineering
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• 제36권5호
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• pp.427-440
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• 2024

This study concentrates on the 301 comprehensive caving working face, notable for its considerable mining height. The roof model is established by integrating prior geological data and the latest borehole rock stratum's physical and mechanical parameters. This comprehensive approach enables the determination of lithology, thickness, and mechanical properties of the roof within 50 m of the primary mining coal seam. Utilizing the transfer rock beam theory and incorporating mining pressure monitoring data, the study delves into the geometric parameters of the direct roof, basic roof movement, and roof pressure during the initial mining process of the 301 comprehensive caving working face. The direct roof of the mining working face is stratified into upper and lower sections. The lower direct roof consists of 6.0 m thick coarse sandstone, while the upper direct roof comprises 9.2 m coarse sandstone, 2.6 m sandy mudstone, and 2.8 m medium sandstone. The basic roof stratum, totaling 22.1 m in thickness, includes layers such as silty sand, medium sandstone, sandy mudstone, and coal. The first pressure step of the basic roof is 61.6 m, with theoretical research indicating a maximum roof pressure of 1.62 MPa during periodic pressure. Extensive simulations and analyses of roof subsidence and advanced abutment pressure under varying working face lengths. Optimal roof control effect is observed when the mining face length falls within the range of 140 m-155 m. This study holds significance as it optimizes the working face length in thick coal seams, enhancing safety and efficiency in coal mining operations.

• International Journal of Advanced Culture Technology
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• 제11권2호
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• pp.210-220
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• 2023

We analyzed and compared factors such as changes in the degree of difficulty of concepts presented in Chemistry I textbook, changes in class types (non-face-to-face, face-to-face), etc. on academic achievement by level (upper, middle, and lower). Students from A high school in Gyeongsangnam-do were selected for the subjects of the study. As a result of analyzing the change in the degree of difficulty of concepts, the total score of chemistry I combined by non-face-to-face and face-to-face classes during the second semester was lower than that of the first semester. As a result of analyzing the impact of factors such as changes in conceptual difficulty, changes in class types, etc. on academic achievement by level, students' grades at the 'lower level' by non-face-to-face classes were lower than those by face-to-face classes. In particular, at the lower level of the second semester, there was a large difference in grades between non-face-to-face and face-to-face classes. In the results of these studies, it was found that instructors' active feedback is important to identify difficulties in understanding learning contents for students with low levels of academic achievement and improve them at the same time.

• The korean journal of orthodontics
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• 제23권4호
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• pp.565-606
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• 1993

The purpose of this study was to evaluate the change of before and after treatment of anterior openbite malocclusions treated by Multiloop Edgewise Archwire technique. The openbite sample consisted of 4 male and 12 female adults, treated with nonextraction or third molar extraction. The normal sample consisted of 58 subjects, which have pleasing facial profile and normal occlusion and no experience of orthodontic or prosthodontic treatment. The 58 subjects of normal sample were subdivided by cephalemetric vertical relationship of face. The 40 subjects, cephalometric vertical relationship of face was in normal range, classified as Normal Sample group 1. The 18 subjects, increased cephalometric vertical relationship of face, classified as Normal Sample group 2. The computerized cephalometric analysis was accomplished with 50 reference points for 22 skeletal measurements, 46 dentoalveolar measurements, 8 soft tissue measurements. Statistical analysis of the data was carried out with paired t-test, Student's t-test, and DUNCAN test using SAS(PC version), The results were as follows : 1. There were no statistically significant differences in skeletal measurement between before and after treatment. The major changes were in dentoalveolar region. 2. After treatment, the long axis of maxillary and mandibular posterior teeth were distally tipped-back, and uprighted to bisected occlusal plane. The interincisal angle was increased. 3. There were no statistically significant increase in the upper posterior dental height and statistically significant decrease in the lower posterior dental height. The upper anterior dental height was increased, but there was no statistically significant increase in the absolute upper anterior dental hight. The lower anterior dental height was increased. 4. After treatment, the maxillary occlusal plane to palatal plane angle and the mandibular occlusal plane to mandibular plane angle were statistically significant increased. Then, there were no statistically significant difference between after treatment group and normal sample group 2. 5. After treatment, the percentage of upper lip length to upper anterior dental height was decreased. Then, There were no statistically significant difference between after treatment group and normal sample group 2.

• The korean journal of orthodontics
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• 제26권5호
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• pp.547-556
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• 1996

The purpose of this study was to evaluate the skeletal, dental and soft tissue profile changes following the face mask therapy in growing skeletal class III malocclusion patients. The fifteen patients with the good results were selected among the patients who visited the Department of Orthodontics in Seoul National University Hospital. The mean age was 10.63(range 7.25-13.25) years and the mean treatment duration was 9.84(range 2.00-27.00) months. Lateral cephalograms were taken just before and after face mask application. After tracing the cephalograms, thirty five items(twety angular and fifteen linear) were measured. The differences before and after the face mask therapy were compared statistically by the paired t-test(p<0.05). The results were as follows : SNA and Co-A(effective maxillary length) increased significantly after using the face mask(p<0.001), which reflects the orthopedic changes of maxilla. SNB and Co-Gn(effective mandibular length) also showed an increase(p<0.01), which may be a result of the strong growth trends of the samples. FMA, SN-GoGn and Y-axis angle increased significantly(p<0.01), which means the backward and downward rotation of the mandible. This positional change seemed to have compensated an increase of effective mandibular length. There was no statistically significant difference in angulation of upper and lower incisors between pre-treatment and post-treatment(p>0.05). In soft tissue profile, the upper lip was positioned anteriorly(p<0.01) after treatment and approximated to the normal standards.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2020-2023
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• 2003

In this paper, our proposed system uses the regional Gabor wavelet and Neural Network to implement face recognition similar to human face recognition system, because the Gator wavelet expresses visual recognition system of human mathematically and the regional Neural Network is robust to white noise and partial illumination. This system consists of two stages of building database and recognizing face. One is composed by using the supervised learning of Neural Network. At this time, the Neural Network is applied to the upper and the lower part of face images respectively. The Backpropagation algorithm is used to learn Neural Network. Another consists of calibration of slope of face image, measurement of illumination variant using deviation with average face image and similarity comparison using Euclidean distance measure.

• Journal of the Korean Society of Costume
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• 제20권
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• pp.17-31
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• 1993

The purpose of this study is to inquire into the influence of appearance cues on the intellectual impression formations, whether there are differen-ces in the impression formation between the case which the appearance is partially percepted and the case wholely percepted. The study consists of the experiment of the factorial design with 5 independent variables of Face (intellectual and social), Hair Style (intellec-tual and social), Clothing Style (intellectual and social), Textile Pattern(single, color, dot, and stri-pe), and Presentation Level of stimuli (upper-half and full-length). The outcomes of study are as follows : 1) The intellectual impression formation was influenced by face, clothing style, and textile pat-tern, but clothing style and textile pattern were more influential than face. When the models with intellectual face wore in intellectual clothing style, they gave more additional intellectual impression. And when intellectual clothing was in single color, it conveyed more intellectual impression. Hair style had no main effect but it influenced on the impression formation through interaction with other variables. 2) There were differences in the formation of the intellectual impressions between the case the appearance was partially percepted and the case wholely percepted. The case of full-lenth pressen-tation was more influential than that of upper-half presentation.