• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.20 no.3
• /
• pp.207-213
• /
• 1998

Purpose : This study attempted to relate the incidence of fractures at the mandibular angle with the presence and state of eruption of lower third molars, and to find out the real risk factors for angle fractures in the states of lower third molars. Materials and Methods : Medical records and radiographs of 395 patients with mandibular fractures were retrospectively reviewed. The presence and states of third molars were assessed for each patients and related to the occurrence of angle and other mandibular fractures. Results : Of 395 patients with mandibular fractures, 142 had angle fractures. The incidence of angle fractures was found to be significantly greater when partial erupted lower third molars were present and it had a definite role for risk factors for angle fractures. But there were no clear relationship between the incidence of angle fracrtures and states of without, fully erupted lower third molars. Furthermore, the states of patial and unerupted lower third molar had an effect on bony segment displacement. Conclusions : This study provides clinical evidence to suggest that patial erupted third molar teeth weaken the mandibular angle both quantitatively and qualitatively.

• Archives of Plastic Surgery
• /
• v.36 no.3
• /
• pp.322-326
• /
• 2009

Purpose: Severe type of inverted nipple (cannot be pulled out above the areola plane by manipulation, grade III) usually cannot be corrected by a relatively simple purse - string suture technique. Most patients want to avoid visible scars. To treat the severe case and avoid visible stigma, we introduce this invisible dermal flap method. Methods: This new surgical procedure makes bilateral incisions on the sidewall of nipple and dissections vertically to free the ducts from the contracted tissues. After dissection, the tunnel is formed. We insert "dermal flaps" into the tunnel underneath nipple base. Then through - and - through sutures are performed vertically (6 o'clock and 12 o'clock positions) and the purse - string suture is added with 4 - 0 nylon. Results: We had treated 35 primary inverted nipples (grade III) in 27 patients and 13 recurrent nipples in 7 cases. The results were excellent in 45 nipples (93.7%). All but 3 recurred cases was fully or very satisfied with the results. Conclusion: This technique is effective for the correction of severe inverted nipples and recurrent cases. We can avoid the visible scars on the areola surface.

• Korean Institute of Interior Design Journal
• /
• v.13 no.4
• /
• pp.110-117
• /
• 2004

Recently the hospitals or clinics tend to get out of the functional and technological aspect so as to gradually emphasize service for patients. While qualitative rather than quantitative alteration is noticeable, the scale of clinics is getting larger. Especially, the opulence resulted from economic, social and cultural development has enabled more people to visit dermatology or plastic surgery besides treatment for disease. Responding to this tendency, dermatology is focusing on skin beauty, plastic operation, controlling obesity, etc. for women rather than ordinary treatment. Thus, dermatology is in need of space for skin control as well as ordinary treatment, which raises the immediate necessity of new plan for space and interior environment. In order to meet such necessity of dermatology, it is required to fully study and consider the plan for interior space. First, the purpose, scope and method of research will be defined in the introduction. Second, the concept of clinic as well at the characteristic of dermatology will be studied by theoretical investigation. Third, the general concept of dermatology will be analyzed by examining the characteristic of each room in dermatology, the moving line of nurses and patients, the color of dermatology and the design factor of finishing materials through general investigation on dermatology. Fourth, in order to look into the general case of dermatology, the object of examination will be selected for examination through literature and visiting. After examining data, the result will be analyzed and evaluated to prepare the ground for interior plan of dermatology.

• Journal of Powder Materials
• /
• v.15 no.1
• /
• pp.31-36
• /
• 2008

In this study, the bottom-up powder metallurgy and the top-down severe plastic deformation (SPD) techniques for manufacturing bulk nanomaterials were combined in order to achieve both full density and grain refinement without grain growth of rapidly solidified Al-20 wt% Si alloy powders during consolidation processing. Continuous equal channel multi-angular processing (C-ECMAP) was proposed to improve low productivity of conventional ECAP, one of the most promising method in SPD. As a powder consolidation method, C-ECMAP was employed. A wide range of experimental studies were carried out for characterizing mechanical properties and microstructures of the ECMAP processed materials. It was found that effective properties of high strength and full density maintaining nanoscale microstructure are achieved. The proposed SPD processing of powder materials can be a good method to achieve fully density and nanostructured materials.

• Journal of the Korean Wood Science and Technology
• /
• v.22 no.1
• /
• pp.85-90
• /
• 1994

The flow properties of binder latices for paper coating were investigated, together with dynamic viscoelastic properties of latex films and electron micrographs of latices, under various conditions. The amphoteric latex, binder pigment latex and anionic latex were used in this work. The amphoteric latex has both anionic and cationic functional group on its surface. The binder-pigment with a core-shell structure has dual functions : plastic pigment and binder. The low shear viscosity of binder latices and clay slurry were measured with Brookfield vis cometer. At low-shear rates. the viscosity decreased with increasing particle size of latex. On the amphoteric latex surface, the carboxyl groups are assumed to be fully dissociated over the region of pH 9~12, but the density of negative groups seems to be increased because of the gradual decrease in the degree of dissociation of amino groups. Since the apparent particle size of latex increases with surface charge, the electroviscous effect can be observed. On the anionic latex surface, the charge density is assumed to be nearly constant above pH 8. However, below pH 8 the coagulation of particles could be observed probably because of the decrease in the charge density.

• Tribology and Lubricants
• /
• v.19 no.4
• /
• pp.230-236
• /
• 2003

In applications such as MEMS and NEMS devices, the adhesion force and contact load may be of the same order of magnitude and the static friction coefficient can be very large. Such large coefficient may result in unacceptable and possibly catastrophic adhesion, stiction, friction and wear. To obtain the static friction coefficient of contacting real surfaces without the assumption of an empirical coefficient value, numerical simulations of the contact load, tangential force, and adhesion force are preformed. The surfaces in dry contact are statistically modeled by a collection of spherical asperities with Gaussian height distribution. The asperity micro-contact model utilized in calculation (the ZMC model), considers the transition from elastic deformation to fully plastic flow of the contacting asperity. The force approach of the modified DMT model using the Lennard-Jones attractive potential is applied to characterize the intermolecular forces. The effect of the surface topography on the static friction coefficient is investigated for cases rough, intermediate, smooth, and very smooth, respectively. Results of the static friction coefficient versus the external force are presented for a wide range of plasticity index and surface energy, respectively. Compared with those obtained by the GW and CEB models, the ZMC model is more complete in calculating the static friction coefficient of rough surfaces.

• Transactions of Materials Processing
• /
• v.22 no.3
• /
• pp.123-132
• /
• 2013

Hot stamping, which is the hot pressing of special steel sheet using a cold die, can combine ease of shaping with high strength mechanical properties due to the hardening effect of rapid quenching. In this paper, a thermo-mechanical analysis of hot stamping using the finite element method in conjunction with phase transformations was performed in order to investigate the plastic deformation behavior, temperature history, and mechanical properties of the stamped car part. We also conducted a fully coupled thermo-mechanical analysis during the stamping and rapid quenching process to obtain the mechanical properties with the consideration of the effects of plastic deformation and phase transformation on the temperature histories at each point in the part. The finite element analysis could provide key information concerning the temperature histories and the sheet mechanical properties when the phase transformation is properly considered. Such an analysis can also be used to determine the effect of cyclic cooling on the tooling.

• Journal of Yeungnam Medical Science
• /
• v.11 no.1
• /
• pp.30-34
• /
• 1994

Local anesthetics produce pain during infiltration into skin. The relationship between local anesthetic-induced pain and pH of the local anesthetic solution has not been fully investigated. Commercial preparation of local anesthetics are prepared as acidic solutions of the salts to promote solubility and stability. And the acidity of local anesthetic solition may be related with the pain during infiltration of the solutione. So, we tried to neutralize the lidocaine hydrochloride solution which is one of the most frequently used local anesthetic agent. Sodium bicarbonate was used for neutralization. Sodium bicarbonate was mixed with lidocaine hydrochloride until the resulting pH of the solution become 7.4 which is identical to the acidity of body fluid. To identify the effect of neutralized lidocaine solution, we had a course of double blind test to 6 volunteers. Both forearm of each volunteer were injected with neutralized lidocaine and plain one, and the degree of pain was estimated by each volunteers. According to subjective description by the volinteers, everyone felt neutralized lidocaine injection site was less painful than plain lidocaine. We concluded that we could reduce pain from infiltration of lidocaine hydrochloride by neutralization of the anesthetic solution with sodium bicarbonate.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1563-1565
• /
• 2008

Hydrophobic plastic plates employing nano surface features are injection molded using thermoplastic materials. A variotherm molding process is devised for filling the nano pores and releasing the molded nano features from the master. The size of the molded nano surface features are about 100nm in diameter and 200nm in height. The size of the molded plate is about 30mm x 30mm and the thickness is 1mm. As molding materials, Polypropylene, PMMA, COC and PC are employed, which are all typical commodity thermoplastic materials. The mold temperature(stamper temperature) is investigated as a major processing parameter for molding high aspect ratio nano surface features. Almost fully molded nano features are fabricated above a certain level of mold temperature depends on the employing material. The contact angles on the injection molded plates are measured to estimate the hydrophobicity and found to have higher contact angle up to 180% compared to the blank plate with no surface features.

• Journal of Powder Materials
• /
• v.18 no.5
• /
• pp.411-416
• /
• 2011

In this study, powder metallurgy and severe plastic deformation by high-pressure torsion (HPT) approaches were combined to achieve both full density and grain refinement at the same time. Water-atomized pure iron powders were consolidated to disc-shaped samples at room temperature using HPT of 10 GPa up to 3 turns. The resulting microstructural size decreases with increasing strain and reaches a steady-state with nanocrystalline (down to ~250 nm in average grain size) structure. The water-atomized iron powders were deformed plastically as well as fully densified, as high as 99% of relative density by high pressure, resulting in effective grain size refinements and enhanced microhardness values.