• Journal of the Korean Wood Science and Technology
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• v.46 no.2
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• pp.125-131
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• 2018

This study was conducted to understand and to compare the qualitative aspects of anatomical characteristics in compression wood (CW), lateral wood (LW), and opposite wood (OW) in a stem of Ginkgo biloba. The qualitative analysis was examined by optical microscopy and scanning electron microscopy. CW in Ginkgo biloba disks were dark brown in color, and the OW and LW were light brown in color. CW and OW showed abrupt transitions from earlywood to latewood, while LW showed a gradual transition. Cross sections of CW presented circular tracheids with angular outlines, many intercellular spaces, and varying sizes of lumens. Cross sections of LW and OW showed rectangular tracheids, fewer intercellular spaces, and varying sizes of lumens. In radial sections, CW showed an irregular arrangement of tracheids in earlywood, while LW and OW showed comparatively regular arrangements. Slit-like bordered pits on the tracheid cell wall, piceoid pits in the crossfield, and a few spiral checks were present in CW. LW and OW showed bordered pits with slightly oval-shaped apertures, as well as cuppresoid pits in the crossfields. Rays were primarily uniseriate, with few biseriate rays in the tangential sections of CW, LW, and OW. The tips of the tracheids were branched in CW but had a normal appearance in LW and OW.

• Korean Journal of Ichthyology
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• v.28 no.4
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• pp.223-228
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• 2016

The anatomy and histology of the olfactory organ in Oryzias sinensis was researched using a stereo microscope and light microscope. In the gross structure, the paired olfactory organs on the dorsal part of the head consist of two nostrils (a circular anterior nostril and a slit posterior nostril in a distance), a single olfactory chamber and a single accessory nasal sac. In the histological study, the epithelium of the olfactory chamber is classified into both sensory and non-sensory regions. The sensory epithelium consists of olfactory receptor neurons, supporting cells, basal cells and vesicles, and is islet in distributional pattern. The non-sensory epithelium is composed of stratified epithelial cells and two types of mucous cells (acidic and neutral cells). The epithelium of the accessory nasal sac has swollen stratified epithelial cells, mucous cells with a rich glycoprotein. Such an olfactory anatomy and histology of O. sinensis may reflect its habitat surrounding stagnant and polluted water.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.83-90
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• 2001

The Talbot effect for periodic objects with the spatial period p illuminated by expanded coherent light is analyzed by Fresnel diffraction theory, and the Talbot distance (Zr) at which we can observe 1: 1 imaging without any lenses can be defined. We confmned experimentally the Talbot imaging of line, circular, X -type and '||'&'||'copy;-type 2 dimensional alTay gratings at ZT. At the same time, we observed phase reversed Talbot imaging at Zr/2 and Talbot subimage with p/2 at Zr/4 and 3Zr/4. The visibility of Talbot images as a function of the number of slits of the input grating was measured by the FFf (Fast Fourier Transform) results of these images. As a result stationary maximum visibility of V = 0.25 was obtained from grating numbers with more than 15 slit pairs.

• Korean Journal of Veterinary Research
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• v.37 no.4
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• pp.693-706
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• 1997

The present study was designed to investigate the morphological developments of the stomach in the prenatal and postnatal rats. The gastric fundus of 16- to 22-day-old fetuses, neonates, 7-day-old, 14-day-old, 21-day-old, and adult rats were observed by light and scanning electron microscopy. Light microscopic studies. 1. In the 16-day-old fetuses, the walls of the gastric fundus were differentiated into epithelium, lamina propria, muscle layer, and serosa. The lamina propria was composed of mesenchymal connective tissue cells with sparse nucleus and their fibers. 2. In the 17-day-old fetuses, the muscular layer were differentiated into the circular and longitudinal muscle layers. 3. The epithelium on the fundus of stomach was stratified columnar cells at 16-, 17- and 18-day-old fetuses, but partly converted into simple columnar epithelium at 19-day-old fetuses. 4. The mucous cells were positive by PAS reaction at the 19-day-old fetuses and then these developed rapidly within 1 or 2 days before birth. 5. In the 20-day -old fetuses, the parietal cells were distinguished from other type cells and these cells were chiefly crowded in the middle parts of the gastric glands after 7-day-old. Scanning electron microscopic studies. 6. The surface of gastric mucosa was covered with forms of the various protrusions by forming villi at the last few days before birth and these protrusion forms were fused and folded each other. 7. The mucosal surface was closely packed by polygonal mucous cells. The openings of gastric glands were seen as slit-like round invagination and were more numerous and increased gradually in depth after the postnatal life. The above findings indicate that prominent changes occurred in the pattern of cellular proliferation in the stomach fundus at the end of gestation. The gastric epithelium had well-defined glands composed of parietal, chief and mucous cells just before the birth. The stomach fundus, therefore, were developed morphologically as those of normal adult at fourteen days after birth.

• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.305-318
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• 2002

We have constructed two flight models of airglow photometer system (AGP) to be onboard Korea Sounding Rocket-III (KSR-III) for detection of MUV dayglow above the Korean peninsular. The AGP system is designed to detect dayglow emissions of OI 2972${\AA}$, $N_2$ VK(0,6) 2780${\AA}$, $N_2$ 2PG 3150${\AA}$ and background 3070${\AA}$ toward the horizon at altitudes between 100 km and 300 km. The AGP system consists of a photometer body, a baffle an electronic control unit and a battery unit. The MUV dayglow emissions enter through a narrow band interference filter and focusing lens of the photometer, which contains an ultraviolet sensitive photomultiplier tube. The photometer is equipped with an in-flight calibration light source on a circular plane that will rotate at the rocket's apogee. A bane tube is installed at the entry of the photometer in order to block strong scattering lights from the lower atmosphere. We have carried out laboratory measurements of sensitivity and in-flight calibration light source for the AGP flight models. Although absolute sensitivities of the AGP flight models could not be determined in the country, relative sensitivities among channels are well measured so that observation data during rocket flight in the future can be analyzed with confidence.

• Radiation Oncology Journal
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• v.19 no.1
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• pp.74-80
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• 2001

Purpose : Irradiation cones by using backscatter electrons are made for the treatment of superficial small lesions of skin, oral cavity, and rectum where a significant dose gradient and maximum surface dose is desired. Methods and Materials : Backscatter electrons are produced from the primary electron beams from the linear accelerators. The design consists of a cylindrical cone that has a thick circular plate of high atomic number medium (Pb or Cu) attached to the distal end, and the plate can be adjusted the reflected angle. Primary electrons strike the metal plate perpendicularly and produce backscatter electrons that reflect through the lateral hole for treatment. Using film and a parallel plate ion chamber, backscatter electron dose characteristics are measured. Results : The depth dose characteristic of the backscatter electron is very similar to that of the hard x-ray beam that is commonly used for the intracavitary and superficial lesions. The basckscatter electron energy is nearly constant and effectively about 1.5 MeV from the clinical megavoltage beams. The backscatter electron dose rate of $35\~85\;cGy/min$ could be achieved from modern accelerators without any modification. and the depth in water of $50\%$ depth dose from backscatter electron located at 6mm for $45^{\circ}$ angled lead scatter. The beam flatness is dependent on the slit size and the depth of treatment, but is satisfactory to treat small lesions. Conclusions : The measured data for backscatter electron energy, depth dose flatness dose rate and absolute dose indicates that the backscatter electrons are suitable for clinical use.