• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1829-1834
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• 2001

The choking of dual subsonic streams flowing through a convergent duct in contact has been investigated experimentally and theoretically. The experiment was conducted by using blow-down wind tunnel. The condition, when the dual stream flow chocking (compound choking) occurs at the nozzle exit, was explained by one-dimensional analysis of compound sound wave propagation. The experimental results for the condition of compound choking were compared with the prediction from theoretical analysis, and the schlieren optical method using the spark light source has been used to visualize the flowfield.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.478-485
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• 2002

The shape memory alloys (SMAs) are often used in smart materials and structures as the active components. Their ability to provide a high recovery force and a large displacement has been used in many applications. In this paper the radial displacement of an externally pressurized elliptic composite cylinder where SMA liner or strips actuators are bonded on its inner or outer surface is investigated numerically. The elliptic composite cylinders consisting of an inlet duct system with SMAs are designed and analyzed to determine the feasibility of such a system for the removal of stiffeners from an externally pressurized duct of an aircraft inlet. The deformations caused by prestrained SMAs placed on either surface of an elliptic composite cylinder are studied when activated. The externally pressurized elliptic composite cylinders with the SMA actuators were analyzed using the 3-D finite element method incorporated with 3-D SMA behaviors. The results show that the role of stiffeners may be switched by the activated light SMA actuators.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.5
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• pp.379-389
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• 2005

Obstructive adenitis of the salivary gland following salivary stone or infectious disease of the gland and surrounding tissues is a common disease. It is often difficult to decide whether to perform total excision of the gland or to consider conservative treatment. The present study was designed to investigate histological, histochemical changes of submandibular gland after ligating the excretory duct for identifying the results of gland duct obstruction. A group of 40 rat of Sprague-Dawley weighing about $200{\sim}220gm$ were used in the present study. 30 rats had ligation of the main excretory ducts of submandibular glands just at the exit from the glands. For controls, 10 rats had a sham operation without duct ligation. They were inducted into euthanagia state by intracardial Ketamine injection in 1, 2, 3, 5, 7, 14, 21, 28, 35 and 42 days after the ligation. In each ligation period, 3 animals were used for ligation and one animal was for control. The submandibular glands were dissected out at sacrifice and stained with H&E, PAS, mucicarmine stain and histological examination were carried out under the light microscope. After examination and comparison of all specimens, the results were as follows: 1. In the features of H&E stain, acini disappeared by degrees after the ligation of the excretary duct and interstitial cells were displaced into fibrous connective tissue. Salivary gland had been atrophied with enlarging ducts and proliferating ductal cells. 2. Through total experimental period, a lot of vessels were observed and the atrophy of serous gland was severer than that of mucous gland. 3. The deep portion of submandibular glands showed severe degeneration rather than superficial portion of them after the ligation. 4. The changes which had enlarged ducts and proliferating ductal cells were observed in entire gland and more prominent in serous gland than mucous gland after the ligation. 5. Although PAS and mucicarmine reactions were decreased gradually after the ligation with the lapse of time, since 2 to 3 weeks they were strong positive reactions on entire gland, especially on duct-like structure. So, we can suggest that salivary gland will be atrophied but, survived acini will be redistributed around the ducts.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.2
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• pp.81-93
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• 2006

Obstructive sialadenitis is one of common disease in salivary gland, and most common histologic features are loss of acinar cell and ductal dilatation associated with fibrosis, and infiltration of inflammatory cells. Although many experimental studies has been accomplished for the salivary acinar cell change in obstructive salivary gland disease, studies for myoepithelial cell were deficient. This study is designed for salivary gland tissue change, especially myoepithelial cell when nonspecific chronic sialadenitis or salivary duct injury by duct obstruction or cut can be occurred that is common encounted clinically. After ligation and cutting of submandibular gland of rabbit, groups of aminmal were sacrificed at 1, 2, 4 weeks postoperatively, submandibular gland were removed. The histopathologic evaluation was done with light microscopy. And, with immunohistochemical staining with ${\alpha}$-smooth muscle actin, characteristics of myoepithelial cell were examined. With transmission electron microscopy, ultrastructure of myoepithelial cell were examined for distribution and ultrastructure of myoepithelial cell. The results were obtained as follows: 1. In the histopathologic evaluation, ligation and cutting group of 1 week, linkage of myoepithelial cell associated with acinar atrophy and degeneration were disappeared in both group. 2. More prominent squamous metaplasia was seen in acinar cells of ligation group of 2 weeks experimental rabbit than cutting group. 3. Acinar cells are nearly disappeared in both ligation and cutting group of 4 weeks, and myoepithelial cell also disappeared associated with acinar cell atrophy, and duct-like structure composed by squamous cells by squamous metaplasia in acinar cells were distributed. 4. In immunohistochemical study, both ligation and cutting group ${\alpha}$-SMA distribution were diminished at 1 week experimental rabbits, but myoepithelial cell was more diminished in ligation group than cutting group, which were distributed around cells of squamous metaplasia. 5. Nuclear condensation, chromosome margination, and cytoplasmic vaculoation were appeared in myoepithelial cell of both cutting and ligation group after 1 week with transmission electron microscopy. But degenerative substance were seen in cytoplasm of myoepithelial cell of ligation group of 4 weeks. From the results obtained in this study, atrophy and degeneration of myoepithelial cell was more prominent in duct ligation group than duct cutting group, and myoepithelial cells were seen around cells squamous metaplasia of acinar cell.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.175-179
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• 2007

This experimental demonstration has successfully shown that it is possible to use direct sunlight for the illumination of deeper building zones using the material for light path system(light duct). Three kinds of reflectors which were 95% Silver vaporizing fixed, 85% Anodized and 85% Hot melted applied to evaluate and compare their performances each others. Also, these three kind of reflectors were compared in view point of economics. The most high performance was obtained in 95% Silver vaporizing fixed reflector hater than another reflectors of 85% Anodized reflector and 85% Hot melted reflector even though more high production cost in 95% Silver vaporizing fixed reflector. The rest two reflectors of 85% Anodized and 85% Hot melted $10{sim}15%$ less performance than 95% Silver vaporizing fixed reflector but their production cost were low than the production cost of 95% Silver vaporizing fixed reflector which identified very weak and light yellow color in the light.

• Applied Microscopy
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• v.18 no.2
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• pp.77-90
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• 1988

The ultrastructure of the excretory duct of the large ampullate gland in the orb web spider, Nephila clavain L. Koch are studied with light and electron microscopes. The excretory ducts of the large ampullate glands connected with the large spinning tubes(spigots) on the anterior spinnerets are basically composed of three superposed types of the layers which are inner cuticles, monolayered epithelial cells and peripheral connective cells. According to the morphological characteristics of the cuticles and internal textures of the epithelial cells, the long excretory ducts are subdivided into three(distal, middle and proximal) portions. Especially, at the distal portion of the ducts near the spinning tubes, the electron lucent subcuticles which had the functions of water removal and orientation of silk fibers are well distributed, whereas at the middle and proximal portions these layers disappeared and instead of these, endocuticles are developed. The endocuticle contains two types of bands, which are electron dense and electron lucent. And along the length of the cuticular stem in the excretory duct, these two alternating bands are twisted spirally. In the cytoplasm of the columnar epithelial cells of the distal portion, rough endoplasmic reticula and Golgj complexes, related to the production of the cuticular materials are well developed. Between the adjacent epithelial cells, specialized septate junctions and desmosomes are formed along the plasma membranes. At the proximal portion of the duct, densely accumulated secretory materials appeared, and these are released to the inner canal by the apocrine secretion.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.17 no.1
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• pp.123-135
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• 1987

The author observed the effects of retrograde infusion of water soluble contrast media (Tele- brix 30) on the rabbit submandibular glands and compared the effects of different degrees of filling. 26 rabbits were divided into 2 groups of 12 each as experimentals and I group of 2 as normal controls. One experimental group was filled with 0.2㎖ and the other with 0.4㎖. Right submandibular gland of each rabbit was infused with contrast media and left one with physiologic saline as a experimental control, at a constant rate of 0.12㎖/min. using an infusion pump via the main excretory duct. Immediately after the infusion of contrast media, oblique lateral radiographs of the glands were made with occlusal film in order to confirm the glandular filling. The rabbits were sacrificed after varying periods (1, 8, 24 hours and 3, 6, 10 days) and the tissues were prepared for light and electron microscopic examination. The results were as follows: 1. In glands filled with 0.2㎖ contrast media, the initial changes were a few vacuole formation in the acini and slight dilation of the intralobular duct. The moderately severe changes such as vacuole formation in the acini, the abnormal substructure within the secretory granule, dilation of acinar and intercalated duct lumen, scalloping of striated duct lumen and inflammatory cell infiltrate were observed at 3 days. The general appearance was successively recovered, so the tissue had a normal appearance at 10 days. 2. In glands filled with 0.4㎖ contrast media, the most prominent alterations such as severe acinar atrophy, decreased number of secretory granules, proliferation of connective tissue stroma and pronounced inflammatory cell infiltrates appeared at 6 days. Although the general appearance returned to be almost normal at 10 days, acinar cells showed some atrophy and decreased secretory granules. 3. In glands subjected to 0.4㎖ infusion, the alterations were more severe and the recovery was slower than those seen in the glands to 0.2㎖ infusion.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.89-95
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• 2013

A DBLP(Double blind light pipe) daylight system can be installed at a building exterior wall or roof to replace artificial light during the day time. This system was consisted of a double blind light collector, a mirror duct type light transformer and a prism light pipe distributor. The double blinds were used to track the sun's altitude and azimuth movements to collect the sunlight throughout the day. The sunlight collected by the light collector was reflected on the first mirror and the second mirror and sent to the light pipe through the light transformer. The transformer was designed to deliver the sunlight into the light pipe efficiently. The light distributor plays a role in diffusing the sunlight coming in through the light collector to be used for indoor lighting. In this paper, a DBLP system has been designed, installed and tested at a KIER daylighting twin test cell. The DBLP daylighting system was applied to the experimental test cell which has an indoor area of 2.0 m wide ${\times}$ 2.4 m height ${\times}$ 3.8 m length. The experiment was conducted from January 30 to February 27, 2012, under clear skies and partially cloudy skies. Data was collected from 10:00 am to 16:00 pm every 2 minute and the average was calculated for every 30 minute of the data collection to obtain the system efficiency. The results indicated that the DBLP system efficiency was evaluated as 11.67%. The DBLP system indoor illumination energy reduction was predicted as 0.822 kWh/day. This could replace 4 sets of a 32W fluorescent lamp operating 6.4 hours per a day.

• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.806-816
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• 2022

Purpose: In this study, the luminance measurement analysis results of the smoke generation state are considered for visual signal display light color for real-time escape guidance in the underground common area. Method: We will analyze the scattering characteristics of light in the atmosphere and optical technology based on the visibility theory, and try to classify the elemental technology as a guidance function through a prototype of a visual signal display device for evacuation guidance. Result: In the experiment conducted under the smoke-generating condition, the results were derived with low luminance ratio and good visibility in the order of red, green, and yellow. However, this result is different from general lighting in which color rendering is considered, and is limited to signals for signals and detection. Conclusion: A conclusions were drawn by reflecting both the luminance measurement results in the smoke generation situation and the preference survey results conducted in previous studies for the light color of the visual signal for signal and detection. When events such as smoke occur, it is better to use the escape guidance visual signal in red or green.

• Applied Microscopy
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• v.17 no.2
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• pp.72-84
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• 1987

Histochemical and ultrastructural properties on the cutaneous mucous glands of the water toad, Bufo stejnegeri Schmidt, are studied with light and electron microscopes. Mucous glands of the water toad are simple alveolar glands which are composed of gland cavity in dermis and gland duct in epidermis. Each gland cavity of the mucous glands is consisted of outmost myoepithelial cells, glandular epithelial cells and inner cavity. Gland cavities of the mucous glands are composed of four kinds of glandular epithelial cells which are the dark cell, the light cell, the mucous containing cell and the small cell. Secretory materials which are certified as acid mucopolysaccharides by the histochemical reactions are synthesized through the Golgi complexes of the mucous containing cells.