• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.1
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• pp.32-36
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• 2014

Preoperative surgical simulation in orthognathic surgery has progressed in recent years; the movement of the mandible can be anticipated through three-dimensional (3D) simulation surgery before the actual procedure. In this case report, the mandible was moved to the intended postoperative occlusion through preoperative surgical 3D simulation. Right-side condylar movement change was very slight in the surgical simulation, suggesting the possibility of mandibular surgery that included only left-side ramal osteotomy. This case report describes a patient with a mild asymmetric facial profile in which the mandibular menton had been deviated to the right and the lips canted down to the left. Before surgery, three-dimensional surgical simulation was used to evaluate and confirm a position for the condyle as well as the symmetrical postoperative state of the face. Facial asymmetry was resolved with minimal surgical treatment through unilateral intraoral vertical ramus osteotomy on the left side of the mandible. It would be a valuable complement for the reduction of the surgical treatment if one could decide with good predictability when an isolated intraoral vertical ramus osteotomy can be done without a compensatory osteotomy on the contralateral side.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.25-38
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• 2001

The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear, The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal fortes that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed 'Avchiai Expansion Effect' 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, hut for the outer-bow 25mm and 35mn shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

• Geomechanics and Engineering
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• v.14 no.5
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• pp.407-419
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• 2018

In order to investigate flow characteristics after water inrush from the working face in process of karst tunnel construction, numerical calculation for two class case studies of water inrush is carried out by using the FLUENT software on the background of Qiyueshan tunnel. For each class water inrush from the tunnel face, five cases under different water-inrush velocity are simulated and researched. Three probing lines are selected respectively in the left tunnel, cross passage, right tunnel and in the height direction of the tunnel centerline. The variation characteristics of velocity and pressure on each probing line under the five water-inrush velocities are analyzed. As for the selected four groups probing lines in the tunnels, the change rules of velocity and pressure on each group probing lines under the same water-inrush velocity are discussed. Finally, the water flow characteristics after inrush from the tunnel face are summarized by comparing the case studies. The results indicate that: (1) The velocity and pressure change greatly at the intersection area of the cross passage and the tunnels. (2) The velocity nearby the tunnel side wall is the minimum, while it is the maximum in the middle position. (3) The pressure value of every cross section in the tunnels is basically fixed. (4) As water-inrush velocity increases, the flow velocity and pressure in the tunnels also increase. The former is approximately proportional to their respective water-inrush velocity, while the latter is not. The research results provide a theoretical basis for making scientific and rational escape routes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2989-2994
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• 2000

A mechanical face seal is a tribo-element intended to control leakage of working fluid at the interface of a rotating shaft and its housing. Leakage of working fluid decreases drastically as the clearance between mating seal faces gets smaller. But the very small clearance may result in an increased reduction of seal life because of high wear and heat generation. Therefore, in the design of mechanical face seals a compromise between low leakage and acceptable seal life is important, ant it present a difficult and practical design problem. A fluid film or sealing dam geometry of the seal clearance affects seal lubrication performance very much, and thereby is optimization is one of the main design consideration. in this study the Reynolds equation for the sealing dam of mechanical face seals is numerically analyzed, using the Galerkin finite element method, which is readily applied to various seal geometries, to give lubrication performances, such as opening force, restoring moment, leakage, and axial and angular stiffness coefficients. Then, to improve the seal performance an optimization is performed, considering various design variables simultaneously. For the tested case the optimization ha successfully resulted in the optimal design values of outer and inner seal radii, coning, seal clearance, and balance radius while satisfying all the operation subjected constraints and design variable side-constraints, and improvements of axial and angular stiffness coefficients by 16.8% and 2.4% respectively and reduction of leakage by 38.4% have been achieved.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.1
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• pp.85-91
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• 2011

The technique, which is able to detect and recognize characters in videos such as a movie or TV drama, can be used for applications which are database management of a general user's facial images for the suppliers of PVR(personal video recorder), mobile phones, and multimedia, etc. In this paper, we propose a face detection algorithm. It searches the character through cast indexing when the scene is changed in video. It is consisted of three stages. The first step is the detection-step of the scene change after producing a paused image. The second step is the face detection-step using color information. The final step is the detection-step which detects its features by the facial boundary. According to the experimental result, it has detected faces in different conditions successfully and more advanced than the existing other one that are using only color information.

• Archives of Plastic Surgery
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• v.32 no.3
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• pp.281-286
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• 2005

The goal in facial paralysis treatment is to achieve the normal appearance of the face as well as to reconstruct the natural symmetrical smile. In cases of facial paralysis, a widely accepted procedure is the two stage method, which combines neurovascular free muscle transfer with cross face nerve grafting. Although the results are promising, the two operations of this method, which are about 1 year apart, impose an economic burden on the patients and require a lengthy period before results are obtained. In order to overcome these drawbacks, one stage method, using latissimus dorsi neurovascuular free muscle flap was introduced. Between January 2000 and January 2004, fifteen patients with long standing facial paralysis were treated in the Korea University Anam Hospital. The segmental latissimus dorsi with long nerve and pedicle was transferred to the paralyzed side of the face. The first postoperative movement of the transferred muscle was reported at 8.9 months, faster than that of the two stage method. During the next 24 months, a constant increase in the power of muscle contraction was observed. The fifteen cases were evaluated within an average of 31.7 months following the surgery and satisfactory results including muscle contraction were obtained in eleven of the cases but muscle contraction was not found in three cases.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1982.05a
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• pp.13.1-13
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• 1982

Cysticercosis is not likely to be the first diagnosis the otologist has in the head and neck area. The fact that this disease may present a diagnostic and therapeutic problem is illustrated by one case, appearing in the face of right side. The local finding of a soft nontender mass, the typical calcifications in the soft tissues visible on roentgenograms, and the histopathological findings are described and illustrated. Attention is drawn to the fact that cerebral cysticercosis, which is a very grave disease, may cause tinnitus, nystagmus, and hearing disturbances. Recently, the authors have experienced a case of cysticercosis on the face in a 24-year-old male patient. We present this case with a brief review of the literatures.

• Medical Lasers
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• v.8 no.1
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• pp.35-38
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• 2019

Thread-lifting is a minimally invasive procedure that shows good results and fewer complications as compared with those results and complications of standard surgery. Many procedures and techniques have been developed to create a younger appearance of facial/neck skin for aging people, and the demand for an improved aesthetic appearance is increasing. Since the incidence of side effects is much less than that of non-absorbable threads, which can lead to complications such as foreign body reactions, polydioxanone (PDO) threads are predominantly used for face lift procedures. A 66-year-old woman presented to our clinic with inflamed palpable masses. She had undergone a face lift with absorbable threads in our clinic 5 months previously. Excisional biopsy was performed with the patient under local anesthesia. During the operation, any threads were not detected and there was both fibrotic scar tissue and granulomatous tissue. For effectively promoting healing and managing the scars, treatment with LDM^®-MED was performed on the day after surgery. The treatment was performed according to the author's protocol. Although foreign body granuloma as a complication after using non-absorbable thread types have been previously reported, it is relatively rare to find this type of complication after using absorbable thread. In this report, we present a case in which a 66-year-old female with foreign body granuloma after undergoing a face lift using absorbable threads was treated with the application of dual-frequency ultrasound, which promoted wound healing.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.2
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• pp.132-140
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• 2010

Purpose: The aim of this study is to identify the usefulness of unilateral mandibular angle ostectomy, so-called "Lateral Angle Reduction", in asymmetric prognathism patients by the assessment of postoperative stability and esthetic results Patients and methods: For the retrospective study, 10 skeletal class III mandibular asymmetry patients who were performed SSRO and unilateral mandibular angle ostectomy, Lateral Angle Reduction, was selected. Lateral and posterioanterior cephalogram was taken before surgery (T0), 1day after surgery (T1) and 6month after surgery (T2). To know the esthetic results the facial width and lateral facial contour were examined on posterioanterior cephalogram and to know the postoperative stability B point and Incisor inferius was examined on lateral cephalogram. Statistical analysis was performed. Results: From T0 to T1, Intergonial width was significantly decreased, dominantly at shortened side but no significant changes at lengthened side. Those were well-maintained during 6 months. Lateral facial angle and Ramus angle was significantly decreased on only shortened side from T0 to T1. As a result, after surgery, there were no significant differences in all measurements between shortened side and lengthened side. Ramus deviation angle in shortened side and ramus angle in lengthened side which reflect the angulation of ramus on frontal plane didn't show significant changes after surgery and during postsurgical periods. Lower dental midline showed no statistical changes during postsurgical period. The relapse rate on B-point was 11.92%. Conclusion: Unilateral "Lateral angle reduction" in the asymmetric mandible is valuable to obtain the narrow lower face and symmetric facial contour with a good stability.

• Geomechanics and Engineering
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• v.22 no.6
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• pp.541-552
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• 2020

With the increasing tension of current coal resources and the increasing depth of coal mining, the gob-side entry retaining technology has become a preferred coal mining method in underground coal mines. Among them, the technology of the gob-side entry retaining with the high-water filling material can not only improve the recovery rate of coal resources, but also reduce the amount of roadway excavation. In this paper, based on the characteristics of the high-water filling material, the technological process of gob-side entry retaining with the high-water filling material is introduced. The early and late stress states of the filling body formed by the high-water filling materials are analyzed and studied. Taking the 8th floor No.3 working face of Xin'an coal mine as engineering background, the stress and displacement of surrounding rock of roadway with different filling body width are analyzed through the FLAC^3D numerical simulation software. As the filling body width increases, the supporting ability of the filling body increases and the deformation of the surrounding rock decreases. According to the theoretical calculation and numerical simulation of the filling body width, the filling body width is finally determined to be 3.5m. Through the field observation, the deformation of the surrounding rock of the roadway is within the reasonable range. It is concluded that the gob-side entry retaining with the high-water filling material can control the deformation of the surrounding rock, which provides a reference for gob-side entry retaining technology with similar geological conditions.