• Journal of Korean Society of Forest Science
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• v.42 no.1
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• pp.67-73
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• 1979

In order to observe the anatomical phenomena of root formation in the hypocotyl cuttings of maples, the hypocotyls of Acer palmatum. Acer micro-sieboldianum, and Acer saccharinum were used as the materials. The rooted portions were sectioned by a microtom and doubly stained by safranin and fast green. The results obtained are summarized as follows; 1. A cross section structure of hypocotyl cuttings of Acer sp. is consist of epidermis, cortex, vascular bundle and pith from the outside. The vascular bundle makes circular shape forming polyarch in A. saccharinum and tetrarch in both A. palmatum and A. micro-sieboldianum. 2. An adventitious root of A. saccharinum originated in phloem parenchyma, while that of A. palmatum and A. micro-sieboldianum originated in interfascicular parenchyma related with phloem cells. 3. The hypocotyl cuttings of Acer sp. is commonly composed of parenchyma tissue having vigorous differentiation capability. Therefore, the originated root grow easily through the cortex and epidermis breaking their tissues.

• The Korean Journal of Malacology
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• v.15 no.1
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• pp.1-11
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• 1999

An immunohisochemical study on the cerebral ganglion of the African giant snail, Achatina fulica. was conducted by applying the AB/AY staining and the avidin-bovine-peroxidase complex staining methods. The followings are the results obtained throughout the study. The cerebral ganglion of Achatina fulica is an ellipsoidal body of 2 x 1 mm in size, which is connected by the cerebral commissure of 1 mm in diameter. The cross-section through the cerebral ganglion, shaped like a butterfly, is divided into the medio-dorsal parts, the latero-dorsal parts, the caudo-dorsal parts, and the lateral lobes. In the medio-dorsal and latero-dorsal parts, the LG cells and the DG cells are found mixed, although the LG cells are dominant. In lateral lobe, however, the Y cells are quite dominant, while the LG cells and the DG cells are seldom found. The LG cells are 20-70 $\mu\textrm{m}$ in sizes and circular or ellipsoidal in shapes. They are stained light green with the AB/AY. 1 - 3 nucleoli are found in karyolymph, where granular chromantins are evenly distributed. In cytoplasm, it is found that the secretory granules are evenly developed.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.50-57
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• 2017

In this study, the experiment for determining shock loss at the branch is conducted for the design of network double-deck road tunnel ventilation. The shock loss coefficient that determines the quantity of shock loss has been considered only regarding the constant aspect ratio of circular or rectangular section. However the suggestion of shock loss coefficient is needed since the aspect ratio of double-deck road tunnel for small vehicle is considered around 1:3 with the low height in Korea. The experiment model was made with the scale of around 1:23 applying Reynolds similarity law, so that the shock loss coefficient on the branch of the large aspect ratio was measured. The result of the study showed that shock loss coefficients of both split branch and straight branch were measured two to three times higher than those calculated from the theoretical equation or design values of previous studies. Therefore the study resulted the effect of large aspect ratio on shock loss coefficient was huge, and it is expected that precise design value can be suggested for the design of network double-deck tunnel ventilation.

• Korean Journal of Ichthyology
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• v.28 no.1
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• pp.19-27
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• 2016

The RLG (relative length of gut) is 1.52 (n=12) in the sablefish, Anoplopoma fimbria. The digestive tract has five or six pyloric caeca in the posterior region of stomach. Morphology of mucosal fold is unbranched type in the esophagus and stomach, but branched type in the intestine. The histological structure of digestive tract can be divided into mucosal layer, submucosal layer, muscular layer and serous membrane in the cross section. In the esophagus, mucosal epithelial layer is a simple, and consists of ciliated columnar epithelia and mucous cells. In the stomach, gastric gland of mucosal epithelial layer is a tubular, and is composed of chief cell, parietal cell and mucin secreting cell, which is columnar and contained secretory granules of red and blue colors in the AB-PAS (pH 2.5) reaction. In the intestine, mucosal epithelial layer is a simple, and consists of ciliated columnar epithelia and goblet cells. The submucosal layer is composed mainly of collagen fibers, and well developed in the esophagus. And the muscular layer of digestive tract is divided into longitudinal and circular muscle layer, and well developed in the stomach. The liver is composed of numerous lobular structure and bile canaliculi. Stainability of hepatocyte cytoplasm was eosinophilic, and nucleus and nucleolus showed basophilic in the H-E stain. The pancreatic tissue was scattered in the fatty tissue near the digestive tract, and acinar gland consisting of numerous exocrine cells. And cytoplasmic stainability of exocrine cell was basophilic, and contained numerous zymogen granules of eosinophilic in the H-E stain.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.109-117
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• 2015

Aircraft needs an inlet duct to supply the airflow to engine face. A fighter aircraft that requires low radar observability has to hide the engine face in the fuselage to reduce the Radar Cross Section(RCS). Therefore, the flow path of the inlet duct is changed into S-shape. The performance of the aircraft engine is known to be influenced by the shape and the centerline curvature of the S-Duct. In this study, CFD analysis of the RAE M 2129 S-Duct has been performed to investigate the influence of aspect ratio of inlet geometry. The performance of the S-Duct is evaluated in terms of the distortion coefficient. To simulate the flow under adverse pressure gradient better, $k-{\omega}SST$ turbulence model is employed. The computational results are validated with the ARA experimental data. The secondary flow and the flow separation are observed for all computational cases, while the semi-circular geometry has been found to produce the best results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.917-923
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the KHST test train. The object of this study was 3 kind of cars; trailer car(TT2), motorized car(TM1) and power car(TP1) and the predicted noise was calculated for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from each manufactures. Some of noise sources which were not available in project team, were chosen by experiences of ODS. Internal noise level of each car were predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated of each section of car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is floor in terms or structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TM1 are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TM1 are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.1
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• pp.9-18
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• 2013

Two-phase vapor-liquid flows exist in many shell and tube heat exchangers such as condensers, evaporators, and nuclear steam generators. To understand the fluid dynamic forces acting on a structure subjected to a two-phase flow, it is essential to obtain detailed information about the characteristics of a two-phase flow. The characteristics of a two-phase flow and the flow parameters were introduced, and then, an experiment was performed to evaluate the pressure loss in the tube bundles and the fluid-dynamic force acting on the cylinder owing to the pressure distribution. A two-phase flow was pre-mixed at the entrance of the test section, and the experiments were undertaken using a normal triangular array of cylinders subjected to a two-phase cross-flow. The pressure loss along the flow direction in the tube bundles was measured to calculate the two-phase friction multiplier, and the multiplier was compared with the analytical value. Furthermore, the circular distributions of the pressure on the cylinders were measured. Based on the distribution and the fundamental theory of two-phase flow, the effects of the void fraction and mass flux per unit area on the pressure coefficient and the drag coefficient were evaluated. The drag coefficient was calculated by integrating the measured pressure on the tube by a numerical method. It was found that for low mass fluxes, the measured two-phase friction multipliers agree well with the analytical results, and good agreement for the effect of the void fraction on the drag coefficients, as calculated by the measured pressure distributions, is shown qualitatively, as compared to the existing experimental results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.1006-1014
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• 2000

Hemisphere type Luneberg lens antenna with a reflector(frequency : 9.375 GHz, -3 dB beam width 6$^{\circ}$, diameter 30.3 cm(about 10 A), which is miniaturized and lightweightized by attaching a reflector on a section of half the Luneberg lens antenna, is designed and fabricated on the basis of Luneberg lens antenna from which easy beam pointing is acquired only by movement of 1st radiator. Measurement shows -3dB beamwidth is 6.1$^{\circ}$ in case of E-plane and 5.5$^{\circ}$ in case of H-plane. These are good agreements with expected value. Gain of this antenna is 26dBi(Aperture efficiency for uniform distribution : $\pi$ = 44.97%) which is greater than that of 1st radiator(Rectangular microstrip antenna) by 20.4 dB. And, after calculating the approximated pattern of the 1st radiator, far-field pattern, whose source is the second aperture source farmed from the approximated pattern of the 1st radiator is computed. Comparing this far-field pattern with the expected pattern, a (relatively) good agreement is observed. Circular polarization Luneberg lens antenna is also manufactured by making 1st radiator so that it has the characteristics of LHCP and RHCP radiation. The results are as followings : -3 dB beamwidth 5.8$^{\circ}$ , side lobe level -15.3 dB, isolation between LHCP and RHCP radiation 2543, axial ratio 2 dB bandwidth about 1.4 GHz(14.9%).

• Journal of Veterinary Clinics
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• v.26 no.6
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• pp.586-590
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• 2009

Horsehair worms (Chordodes koreensis) develop as parasites in the bodies of grasshoppers, crickets, cockroaches, and some beetles. Chordodes koreensis is an accidental parasite of humans, livestock, or pets and poses no public health threat. The male of Chordodes koreensis in the later larval stage from canine vomitus was investigated by the scanning and transmission electron microscopy. In cross sections, the body wall is composed of four components namely epicuticle, cuticle, epidermis, and muscle layers. The parenchymal tissue fills the rest of the body and surrounds the visceral organs such as intestine, and ventral nerve cord but testes were not found. The epicuticle is a thin superficial layer whose surface shows rows of polygonal elevations called areoles. The cuticle has 17 layers of collagenous fibers spirally wound about the long axis of the worm. The section through the cuticle reveals the layers of large fibers cut obliquely lengthwise, alternating with layers of fibers sectioned obliquely crosswise. The layers of large fiber formed a double helix about longitudinal axis of the worm. The epidermis is a single layer. The muscles were interrupted by the nervous lamella in the only midventral portion. The medulla of muscle plate is composed of lightly stained cytoplasm, mitochondria, weakly developed endoplasmic reticulum, and glycogen granules. Between the medulla of a cell and the plasmalemma lies a broad cortical zone of myofilaments. The circular muscles are absent. The characteristic feature of the cytoplasm is that there was no content in peripheral mesenchyme, but was an abundance of large clear vacuoles which give the cytosome a foamy appearance. The nucleus of mesenchyme is not easily identified in our specimens.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.2
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• pp.171-183
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• 2020

The purpose of this study is to analyze in advance the problems and improvements that may occur during the construction of intermediate slabs and the loading of intermediate slabs through the preliminary structural safety evaluation of intermediate slabs for Test bed structures in deep depth tunnels. The Test bed construction can verify and confirm the results of the design and construction technology development of large depth double deck tunnel through the process, and can also be used as a learning site for engineers and the general public to speed up the time of underground space development. There will be an opportunity to do this. In particular, the design load of middle slab built inside the circular deep-depth double-sided tunnel cross-section varies depending on the construction method and the construction equipment load used. Class 3 truck load of KL-510 assumed to be common load to upper and middle slab during loading and installation is loaded on upper and lower slab with different working position for each load combination Analyzed.