• 보존과학연구
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• s.25
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• pp.5-29
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• 2004

This research carried out ancient technique and composition of the relics recovered from the octagonal nine-storied pagoda of Woljeongsa temple using the scientific methods and obtained the following results. Firstly, The silver sarira inner case is consists of Ag, its materials comes out near 98wt%and comparing with the relics of Hwangnamdaechong, the contents of Ag and Ni are almost same with it. Secondly, The bronze sarira outer case, its contents of Cu is almost same with pure copper of which average is 99.7wt%. So, it should be named the copper sarira outer caserather than the bronze sarira outer case that has been called. Thirdly, The bronze mirror, though the contents of tin and lead are less than other contents which have been studied, they tend to have white color so they need to be made a close study. Especially, Because cultural property of nondestructive surface analytic method is not analyzed by the analysis of cross section and the moisten analysis, it may be occurred analytical errors by other factors.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.1
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• pp.1-12
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• 1996

The fully developed tubulent momentum and heat transfer induced by the square- ribbed roughness elements on both the inner and outer wall surfaces in the concentric annuli are studied analytically based on a modified turbulence model. Heat transfer coefficients for two conditions, i.e, a) inner wall heated as constant heat flux and outer wall insulated b) inner wall insulated and outer wall heated as constant heat flux, are investigated. The analytical results of the fluid flow are verified by experiment. The experiment is done with a pitot tube and a X-type hot wire anemometer to measure the time mean velocity profiles, zero shear stress positions, maximum velocity profiles and friction factors, and etc. The resulting momentum and heat transfer are discussed in terms of various parameters, such as the radius ratio, the relative roughness, the roughness density, Nusselt number and Prandtl number.

• Publications of The Korean Astronomical Society
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• v.20 no.1 s.24
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• pp.37-42
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• 2005

The problem for the collapse of isothermal and rotational self-gravitational viscous disk is considered. We derive self-similar solutions for the cases in the inner and outer regions of the self-gravitational viscous disk. We show that surface density depends on ${\sigma}_0/r$ in the outer region of the disk using a slow accretion approximation. The ratio of a modified viscous parameter in the outer region of the disk to that in the inner region is 0.042. We resorted to numerical solutions of governing equations of the self-gravitational disk to find out profiles of ${\sigma}$, u and ${\upsilon}$ in terms of x. Their profiles were rapidly changed around the innermost region of the self-gravitational disk. It indicates that a new object was formed in the most inner region of the disk.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.10
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• pp.780-787
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• 2014

This paper experimentally deals with the vibration characteristics of flat ring transducers used for ultrasonic sensors and actuators. Radial vibration mode, which is the fundamental mode of a thin piezoelectric transducer, was measured by a laser in-plane vibrometer. An impedance analyzer was used to measure natural frequencies. The results measured by experiments verified theoretical predictions. The vibration characteristics of ring transducers were identified according to the outer diameter size. The shape of the fundamental mode is almost uniform but slightly decreases from the inner to the outer circumferential surfaces. The natural frequency of the fundamental mode decreases as the outer diameter increases. It appears that the ring type transducer is suitable to excite uniformly distributed vibration on a flat surface.

• Ocean and Polar Research
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• v.25 no.4
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• pp.447-457
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• 2003

In order to understand the distribution of changes of geochemical characteristics in surface sediments according to various environmental changes around the artificial Lake Shihwa, surface sediments were sampled at $13{\sim}15$ sites form 1997 to 1999 and analyzed by C/S analyzer, ICP/MS and AAS. The average $S/C_{org}$ ratio was 0.35 in the surface sediments, which is similar to 0.36, the characteristic ratio of marine sediments. Heavy metal contents and enrichment factors in the surface sediments tended to be decreasing from the head to the mouth of the Lake Shihwa. With the deposition of fine-grained sediments in the central part of lake, anoxic water column induced the sulfides compounds with Cu, Cd and Zn. Metals such as Al, Fe, Cr, Co, Ni, Cu, Zn and Cd except for Mn and Pb showed relatively high correlation coefficients among them. The contents of Cr, Co, Ni, Cu, Zn and Cd in the surface sediments of the lake were two to five times higher than those in the lake before dike construction and also in outer part of the dike. These are mainly due to the Input of untreated industrial and municipal waste-waters into the lake, and the accumulation of heavy metals by limitation of physical mixing. Although metal contents of the surface sediments at the sites near the water-gate due to outer seawater inflow tended to be lower than those during the desalination, heavy metals were deposited in areas around the new industrial complex in the evidence of spatial distribution of heavy metals in the sediments. This is mainly due to the input of untreated waste-waters from tributaries.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.6
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• pp.566-574
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• 2006

Purpose : This study was performed to provide an anatomical information of the mandibular ramus for the successful inferior alveolar nerve block. Three dimensional images were reconstructed from the computerized tomography (CT) and the anatomical evaluation of the mandibular ramus was done. Materials and methods : Sixty-four patients who had been taken the facial CT scans from 2000, Jan to 2003, June was selected. The patients who had the anterior or posterior teeth misssing, edentulous ridge, and jaw fracture were excepted. In the occulusal plane, the lingual surface angle (LSA) between the mid-sagittal plane and the mandibular molar lingual surface from the 2nd premolar to the 2nd molar, the inner ramal surface angle (IRSA), the maximum inner ramal surface angle (MxIRSA), and the outer ramal surface angle (ORSA) to the-mid sagittal plane were measured. The inner ramal surface angle in the ligular tip level (IRSA-L) and the outer ramal surface angle in the ligular tip level (ORSA-L), the ramal length (RL), and the anterior ramal length (ARL) were also measured in the lingular tip level. Results : In the lingular tip level, the mean IRSA-L and ORSA-L were $28.6{\pm}6.3^{\circ}$ and $17.9{\pm}4.9^{\circ}$ respectively. The larger was the IRSA, the larger was the ORSA. In the lingular tip level, the mean ramal length was 35.8${\pm}$3.4 mm. The larger was the IRSA-L, the shorter was the ramal length. On the lingular tip level, the mean anterior ramal length from anterior ramus to lingular tip was 19.6${\pm}$3.3 mm. when the ramal length was longer, the anterior ramal length was also longer. On the lingular tip level, there was positive correlation vetween the IRSA and the ORSA, negative correlation between the IRSA and the ramal length, and positive correlation between the ramal length and the lingular tip level to the anterior ramus. There was no statistical meaning of data between sex and age. Conclusion : In the clinical view of the results so far achieved, if the direction of needle is closer to posterior it is able to contact bone on lingular tip when the internal surface of ramus is wided outer.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.630-635
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• 2016

In the prior work, we studied a ballast water treatment apparatus, which is secondary pollution free by using physical treatment of shear stress. The principle of this apparatus is smashing various microorganisms by shear stress generated between stationary outer cylinder and revolving inner cylinder. Because of various magnitude of shear stress according to the inner cylinder surface type and revolution speed, an appropriate surface type and optimum revolution speed should be studied by consecutive experiment to determine the reference data for commercial apparatus. Through a comparative study of disk type and cylinder type of ballast water treatment apparatus, cylinder type is turned out to be superb to disk type. In this study, we studied to determine the superior collaboration of cylinder type, groove type and knurling type of inner cylinder to non patterned outer cylinder, and to optimize the revolution speed and flow rate according to the gap between inner cylinder and outer cylinder. As a result, we could get perfect sterilization effect at groove type under the conditions of 250 mL/min of flow rate at 8,000 rpm and 500 mL/min of flow rate at 10,000 rpm respectively.

• Korean Journal of Plant Tissue Culture
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• v.25 no.6
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• pp.495-500
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• 1998

Ultrastructural changes of the isolated and cultured protoplasts from ginseng (Panax ginseng C. A. Meyer) callus were studies with electron microscopy. In the 3-day-cultured protoplasts, the cell organelles such as rough endoplasmic reticulum, ribosome, Golgi complex, mitochondria, proplastid increased in number and observed microtubules. Many vesicles derived from the Golgi complex were evenly distributed in the cytoplasm. Some of such vesicles protruded the outer surface of the plasmalemma, and formed the protuberances. Vacuole derived from endoplasmic reticulum included Golgi vesicles by the invagination of vacuoles. These vacuoles migrated toward the plasmalemma by a fusion process (exocytosis), after fusing the plasmalemma the cell wall materials released from the outer surface of the plasmalemma, and lastly deposited on the plasmalemma. Proplastids containing many starch grains, and microtubules parallel to the plasmalemma were observed near the plasmalemma. Connected fibrils which were observed on the outer surface of the 3-day-cultured protoplast were interpreted as the component of cellulose.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.58.3-58.3
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• 2017

In a ${\Lambda}CDM$ universe, galaxies are believed to evolve by mergers and accretions. The debris resulting from such processes remains as diffuse, low-surface brightness structures, such as outer disks, stellar halos, and faint companions. These structures will give us fruitful insight into the recent mass assembly history of galaxies, but it is challenging to observe them due to their low surface brightness. In order to explore the structural properties of outskirts of nearby galaxies, we conduct deep wide-field imaging survey with KMTNet. Here we present a progress report of data reduction for the images of NGC 1291, a lenticular barred galaxy with outer rings. To achieve accurate flat fielding, we use dark sky flat and remove the sky gradient of each exposure with a polynomial fit. As a result, we are able to reach 1 sigma depth of ${\mu}_R{\sim}29.6\;mag\;arcsec^{-2}$. We expect to investigate the surface brightness profile of NGC 1291 in 1-D profile, and color-gradient in the outer part of the galaxy using the B- and R-band images.

• Restorative Dentistry and Endodontics
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• v.43 no.3
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• pp.33.1-33.8
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• 2018

Objectives: This study aimed to investigate the prevalence of a separate distolingual root and to measure the thickness of the buccal cortical bone in mandibular first molars in Koreans using cone-beam computed tomography (CBCT) images. Materials and Methods: High-quality CBCT data from 432 patients were analyzed in this study. The prevalence of a separate distolingual root of the mandibular first molar was investigated. The distance from the distobuccal and distolingual root apices to the outer surface of the buccal cortical bone was measured. We also evaluated the thickness of the buccal cortical bone. Results: The prevalence of a separate distolingual root (2 separate distal roots with 1 canal in each root; 2R2C) was 23.26%. In mandibular first molars with 2R2C, the distance from the distobuccal root apex to the outer surface of the buccal cortical bone was 5.51 mm. Furthermore, the distance from the distolingual root apex to the outer surface of the buccal cortical bone was 12.09 mm. In mandibular first molars with 2R2C morphology, the thickness of the buccal cortical bone at the distobuccal root apex of the mandibular first molar was 3.30 mm. The buccal cortical bone at the distobuccal root apex was significantly thicker in the right side (3.38 mm) than the left side (3.09 mm) (p < 0.05). Conclusions: A separate distolingual root is not rare in mandibular first molars in the Korean population. Anatomic and morphologic knowledge of the mandibular first molar can be useful in treatment planning, including surgical endodontic treatment.