• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.87-98
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• 2005

When a tunnel is excavated below groundwater table, the groundwater flows into the excavated wall of tunnel and seepage forces are acting on the tunnel wall. The ground reaction curve is defined as the relationship between internal pressure and radial displacement of tunnel wall. Therefore, the ground reaction curve is significantly affected by seepage forces. In this study, the theoretical solutions of ground reaction curves were derived for both the dry condition and the seepage forces. The theoretical solutions derived were validated by numerical analysis. The ground reaction curves with the support characteristic curve were also analyzed in various conditions of groundwater table. Finally, the theoretical solutions of the ground reaction curve derived in this study can be utilized easily to determine the appropriate time of support systems, the stiffness of support system and so forth for the reasonable design.

• The Journal of Internal Korean Medicine
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• v.17 no.1
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• pp.210-217
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• 1996

Farfarae Flos, a traditional herb medicine, has been used in Korea and China for many centuries as a treatment for respiratory disease. The purpose of the present study was to determine the effect of Farfarae Flos on histamine-induced tracheal smooth muscle contraction in rats. Guinea pigs(500g, female) were killed by CO2 exposure and a segment (8-10mm) of the thoracic trachea from each guinea pig was cut into equal segments and mounted 'in pairs' in a tissue bath. Contractile force was measured with force displacement transducers under 0.5g loading tension. The dose of histamine which evoked 50% of maximal response (ED50) was obtained from cumulative dose response curves for histamine (10-7-10-4M). Contractions evoked by histamine(ED50) were inhibited significantly by Farfarae Flos. The mean percent inhibition was 8.7% after 1.5mg/ml Farfarae Flos, and 33.5% (p<0.05) after 5.0mg/ml Farfarae Flos. Propranolol (10-7M) slightly but significantly attenuated the inhibitory effects of Farfarae Flos. Following treatment with propranolol, the mean percent inhibition caused by 5.0mg/ml Farfarae Flos. Indomethacin and methylene blue (10-7M) did not significantly alter the inhibitory effect of Farfarae Flos. These results indicate that Farfarae Flos can relax histamine-induced contraction of guinea pig tracheal smooth muscle, and that this inhibition involves, in part, symphathetic nerve system.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.48-55
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• 2012

Pressure vessels in vehicle industries, power plants, and chemical industries are often affected by flaw and defect generated inside the pressure vessels due to production processes or being used. It is very important to detect such internal defects of pressure vessel because they sometimes bring out serious problems. In this paper, an optical defect detection method using digital shearography is used. This method has advantages that the inspection can be performed at a real time measurement and is less sensitive to environmental noise. Shearography is a laser-based technique for full-field, non-contacting measurement of surface deformation (displacement or strain). The ultimate goal of this paper is to detect flaws in pressure vessels and to measure the lengths of the flaws by using unwrapping, phase images which are only obtained by Phase map. Through this method, we could decrease post-processing (next processing). Real length of a pixel can be calculated by comparing minimum and maximum unwrapping images with shearing angle. Through measuring several specimen defects which have different lengths and depths of defect, it can be possible to interpret quantitatively by calculating gray level.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.5
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• pp.474-481
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• 2006

The endoscopic assisted approach for the treatment of condylar fracture is a less invasive alternative treatment modality and is considered to be able to overcome the limited access to the operation field to obtain an accurate reduction and fixation. Six patients with condylar neck and subcondylar fracture underwent the endoscopic assisted open reduction and internal fixation through the transoral approach at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. The endoscope was inserted through an intraoral incision and the reduction of fracture fragment was performed via a transbuccal approach with two transcutaneous stab incisions. Five patients showed anatomic reduction without any complications. One patient, whose fracture site was fixed with a single plate, showed displacement of fractured condylar segment during the follow up period. No patient had any facial nerve damage.

• Progress in Medical Physics
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• v.28 no.4
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• pp.164-170
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• 2017

One of the methods to consider the effect of respiratory motion of a tumor target in radiotherapy is to establish a treatment plan with the internal target volume (ITV) created based on an accurate analysis of the target motion displacement. When this method is applied to intensity modulated radiotherapy (IMRT), it is expected to yield a different treatment dose distribution under the motion condition according to the IMRT method. In this study, we prepared ITV-based IMRT plans with conventional IMRT using fixed gantry angle beams, RapidArc using volumetric modulated arc therapy, and tomotherapy using helical therapy. Then, the variation in dose distribution caused by the target motion was analyzed by the dose measurement in the actual motion condition. A delivery quality assurance plan was prepared for the established IMRT plan and the dose distribution in the actual motion condition was measured and analyzed using a two-dimensional diode detector placed on a moving phantom capable of simulating breathing movements. The dose measurement was performed considering only a uniform target shape and motion in the superior-inferior (SI) direction. In this condition, it was confirmed that the error of the dose distribution due to the target motion is minimum in tomotherapy. This is thought to be due to the characteristic of tomotherapy that treats the target sequentially by dividing it into several slices. When the target shape is uniform and the main target motion direction is SI, it is considered that tomotherapy for the ITV-based IMRT method has a characteristic which can reduce the dose difference compared with the plan dose under the target motion condition.

• The Journal of Internal Korean Medicine
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• v.16 no.1
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• pp.104-129
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• 1995

Sabaeksan and Sabaeksangagaryureuk, a traditional prescription, has been used in Korea for many centuries as a treatment for chronic respiratory disease. The purpose of the present study was to determine the effect of Sabaeksan and Sabaeksangagaryureuk on acetylcholine-induced tracheal smooth muscle contraction in guinea pigs and norepinephrine-induced vascular smooth muscle contraction in pigs. Guinea pig (500g, female) were killed by CO2 exposure and a segment (8-10mm) of the thoracic trachea from each guinea pig and renal artery from each pig were cut into equal segments and mounted 'in pairs' in a tissue bath. Contractile force was measured with force displacement transducers under 0.5g loading tension. The dose of acetylcholine (Ach) and norepinephrine (NE) which evoked 50% of maximal response ($ED_{50}$) was obtained from cumulative dose response curves for acetylcholine (10-7-10-4M) and norepinephrine (10-7-10-4M). Contractions of tracheal smooth muscle evoked by Ach ($ED_{50}$) were inhibited significantly by Sabaeksan and Sabaeksangagaryureuk. Propranolol (10-7M) slightly but significantly attenuated the inhibitory effects of Sabaeksan and Sabaeksangagaryureuk. Indomethacin and methylene blue (10-7M) did not significantly alter the inhibitory effect of Sabaeksan and Sabaeksanga-garyureuk. Contractions of vascular smooth muscle evoked by NE (NE50) were inhibited significantly by Sabaeksan and Sabaeksangagaryureuk. Propranolol (10-7M) slightly but significantly attenuated the inhibitory effects of Sabaeksan and Sabaeksangagaryureuk. Indomethacin and methylene blue (10-7M) did not significantly alter the inhibitory effect of Sabaeksan and Sabaeksangagaryureuk. These results indicate that Sabaeksan and Sabaeksangagaryureuk can relax acetylcholine-induced contraction of guinea pig tracheal smooth muscle, and norepinephrine-induced contraction of pig vascular smooth muscle that this inhibition involves, in part, the relation of adrenergic receptor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.615-618
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• 2004

The piezoelectricity and polarization of multilayer ceramic actuators, being designed to stack ceramic layer and electrode layer alternately, were investigated under a consideration of geometry, the thickness ratio of the ceramic layer to electrode layer The actuators were fabricated by tape-casting of $0.42PbTiO_3-0.38PbZrO_3-0.2Pb(Mn_{1/3}Nb_{2/3})O_3$ followed by laminating, burn-out and co-firing process. The actuators of $5\times5mm^2$ in area were formed in a way that $60{\sim}200{\mu}m$ thick ceramics were stacked 10 times alternately with $5{\mu}m$ thick electrode. Increase in polarization and electric field-displacement with increasing thickness ratio of the ceramic/electrode layer and thickness/cross section ratio were attributed to the change of $non-180^{\circ}/180^{\circ}$ domain ratio which was affected by the interlayer internal stress and Poisson ratio of ceramic layer. The piezoelectricity and actuation behaviors were found to be dependent upon the volume ratio (or thickness ratio) of ceramic layer relative to ceramic layer. Concerning with the existence of internal stress, the field-induced polarization and deformation were described in the multilayer actuator.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.44 no.3
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• pp.120-127
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• 2018

Objectives: The aim of this study was to reveal how collagenases (matrix metalloproteinase [MMP]-1, 8, 13) and tissue inhibitor of metalloproteinase 1 (TIMP-1) are expressed in immunohistochemistry of retrodiscal tissue in temporomandibular joint disorder patients. Materials and Methods: This study was conducted on 39 patients who underwent discoplasty or discectomy. Immunohistochemical staining was undertaken and expression levels of MMP-1, 8, 13, and TIMP-1 were evaluated. The status of internal derangement of disc, osteoarthritis, and joint effusion were analyzed using magnetic resonance imaging (MRI). Disc status observed during operation was also categorized. Results: The more severe disc derangement was observed on MRI, the more increased expression of MMPs and TIMP-1 appeared. Regarding MMP-13 expression, 86.7% of late-stage disc displacement patients showed grade II or III. Expression level of MMPs or TIMP was not statistically significant associated with joint effusion level. In perforation and/or adhesion groups, all patients showed grade II or III expression of MMP-13. Once perforation occurred, MMP-13 showed increased expression with statistical significance. Conclusion: MMP-1 and MMP-13 expression seem to be related to progression of osteoarthritis whereas MMP-8 does not seem to have a specific role with regard to temporomandibular joint disorders. TIMP-1 is considered to be partly related to internal derangement rather than osteoarthritis, but it is not significant.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.122-129
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• 2006

Shearography is one of optical methods that has been applied to nondestructive testing (NDT) and strain/stress analysis. The technique has the merit of the directly measuring relative displacement, which is insensitive to environmental vibration disturbance. Previous studies about the method have emphasized on extending its application to new fields and lack insufficient research on effective parameters for qualitative and quantitative evaluation of defects. In this paper, the influence of shearing amount on the detection of an internal defect is investigated. In experiment, slender defects along longitudinal direction of pipeline are artificially designed and detection results according to the change of shearing amount are analyzed. Based on the investigation, we propose the technique for the determination of defect size and accurate source location.

• Structural Engineering and Mechanics
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• v.66 no.2
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• pp.273-283
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• 2018

Currently, the dynamic amplification effect of suction is described using the wind vibration coefficient (WVC) of external loads. In other words, it is proposed that the fluctuating characteristics of suction are equivalent to external loads. This is, however, not generally valid. Meanwhile, the effects of the ventilation rate of louver on suction and its WV are considered. To systematically analyze the effects of the ventilation rate of louver on the multi-dimensional WVC of ultra-large cooling towers under suctions, the 210 m ultra-large cooling tower under construction was studied. First, simultaneous rigid pressure measurement wind tunnel tests were executed to obtain the time history of fluctuating wind loads on the external surface and the internal surface of the cooling tower at different ventilation rates (0%, 15%, 30%, and 100%). Based on that, the average values and distributions of fluctuating wind pressures on external and internal surfaces were obtained and compared with each other; a tower/pillar/circular foundation integrated simulation model was developed using the finite element method and complete transient time domain dynamics of external loads and four different suctions of this cooling tower were calculated. Moreover, 1D, 2D, and 3D distributions of WVCs under external loads and suctions at different ventilation rates were obtained and compared with each other. The WVCs of the cooling tower corresponding to four typical response targets (i.e., radial displacement, meridional force, Von Mises stress, and circumferential bending moment) were discussed. Value determination and 2D evaluation of the WVCs of external loads and suctions of this large cooling tower at different ventilation rates were proposed. This study provides references to precise prediction and value determination of WVC of ultra-large cooling towers.