• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.618-622
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• 2004

The vibration test system of SITC(Satellite Integration and Test Center) at KARI(Korea Aerospace Research Institute) has been used successfully for the environmental tests of a majority of korean space programs, such as KOMPSAT, Koreasat KITSAT, STSAT and KSR program since 1996. To meet the recent needs of large size test facility available for the vibrational tests of the huge launch vehicles and tole-communication satellites which will be developed in the near future, KARI undertook to construct the large size multi-electromagnetic shaking system with 3 $\times$ 3m head expander system. The new system will consist of three electromagnetic shakers which has 160 kN thrust force individually, and be able te sustain up to 8 tons test load and 300 kNm overturing moment. And to avoid the tremendous cost and effort to furnish the seismic block with large size and weight, it will adopt a Lin-E-Air type configuration with which the seismic block is less severe than a Solid-Truninon type. In addition, to fulfill the strong requirement of high overturning moment the additional guidance system including a central bearing system on a central support and several pad bearings around the head expander body is now considered. This paper describes the configuration and the design parameters of the multi-shaking system which is under development by KARI's engineers.

• Tribology and Lubricants
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• v.31 no.4
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• pp.141-147
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• 2015

Gas foil thrust bearings (GFTBs) have attractive advantages over rolling element bearings and oil film thrust bearings, such as oil-free operation, high speed stability, and high-temperature operation. However, GFTBs have lower load carrying capacity than the other two types of bearings owing to the inherent low gas viscosity. The load carrying capacity of GFTBs depends mainly on the compliance of the foil structure and the formed hydrodynamic wedge, where the gas pressure field is generated between the top foil and the thrust runner. The load carrying capacity of the GFTBs is very important for the suitable design of oil-free turbomachinery with high performance. The aim of the present study is to identify the characteristics of the load carrying performance of GFTBs. A new test rig for the experimental measurements is designed to provide static loads up to 800 N using a pneumatic cylinder. The maximum operating speed of the driving motor is 30,000 rpm. A series of experimental tests—lift-off test, static load performance test, and maximum load capacity test—estimate the performance of a six-pad GFTB, in terms of the static load, driving torque, and temperature. The maximum load capacity is determined by increasing the static load until the driving torque rises suddenly with a sharp peak. The test results show that the torque and temperature increase linearly with the static load. The estimated maximum load capacity per unit area is approximately 80.5 kPa at a rotor speed of 25,000 rpm. The test results can be used as a design guideline for GFTBs for realizing oil-free turbomachinery.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.167-175
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• 2014

If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis.

• Journal of Physiology & Pathology in Korean Medicine
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• v.32 no.4
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• pp.261-270
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• 2018

The aim of this study was to evaluate the antitumor activities of Typhae pollen (TP) by confirming in vitro cytotoxicity and in vivo anti-tumor and immune-modulatory effect with anti-cachexia effect. The MTT assay is used in HepG2 cell to detect potential cytotoxic activities of aqueous extract of Typhae pollen (TPe). After HepG2 tumor cell implantation, eight mice per groups were assigned to six groups. Three different dosages of TPe (500, 250 and 125 mg/kg) were orally administered in the amount of $10m{\ell}/kg$ and sorafenib also administered 20mg/kg, every day for 35 days from 28 days after the tumor cell implantation. We observed the changes on body weights, tumor volume and weights, lymphatic organ, serum interferon $(IFN)-{\gamma}$ levels, splenocytes and peritoneal NK cell activity, splenic tumor necrosis factor $(TNF)-{\alpha}$, interleukin $(IL)-1{\beta}$, IL-10 contents. Periovarian fat weights, serum IL-6 levels, thicknesses of deposited periovarian adipose tissue and mean diameters were also detected to monitor the tumor-related anticachexic effects. In tumor masses, the immunoreactivities of cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase (cleaved PARP) - apoptotic marks, cyclooxygenase-2 (COX-2), inducible nitric oxide synthases (iNOS) and tumor necrosis factor $(TNF)-{\alpha}$ were additionally observed by immunohistochemistry. The results were compared with sorafenib. Decreases of COX-2 were demonstrated in sorafenib and TPe treated mice and also increases of iNOS in tumor masses were observed in TPe, not in sorafenib. TPe increased periovarian fat pad weights compared with tumor-bearing controls and sorafenib treated mice. TPe showed increases of splenic $TNF-{\alpha}$, IL-10 and $IL-1{\beta}$, serum $IFN-{\gamma}$ and NK cell activities corresponding to increases of spleen weights, lymph node weights and non-atrophic changes of lymph nodes. Our results show oral treatment of TPe 500, 250 and 125 mg/kg has potent in vitro and in vivo antitumor activities through modest cytotoxic effects, immunomodulatory effects and apoptotic activities in HepG2 tumor cells. In addition, TPe can prevent cancer related cachexia.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.479-483
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• 2003

Knowledge of N accumulation during the vegetative growth stage of rice (Oryza sativa L.) is useful for determining the need for topdressing fertilizer N at panicle initiation and booting stage. The chlorophyll content showing SPAD threshold values generated by a simple and portable diagnostic instrument, chlorophyll meter, enables implement the measures of greenness and/or relative chlorophyll contents of leaves. Two-year field experiment was conducted to evaluate the possible application of the chlorophyll meter for N diagnosis in transplanted paddy rice. The chlorophyll meter threshold values (SPAD reading) were taken from uppermost fully expanded leaves at 10days interval from 10 days after transplanting. SPAD readings and N contents of rice leaf blade were closely related at the maximum tillering stage. SPAD readings during growth period showed M-shaped distribution, sharply finished to drop at 20 days after heading date. As N fertilizer increased, the SPAD readings increased. The SPAD readings showed more critical and clear difference in immature paddy field than in ordinary paddy field, where the former soil showed higher response to N fertilizer topdressed. Based on the PAD readings for obtaining an optimum sink size bearing the maximum grain yield, N fertilizer to be dressed at the panicle initiation stage is to be adjusted within the SPA$\times$tillers value range 888 in ordinary paddy, and 800 in immature paddy vice. Among the cultivars tested, Huckhyangbyeo, Jinpumbyeo, Ansungbyeo, Sobibyeo, Manpungbyeo, Sangmibyeo, Jinbongbyeo, showed high SPAD values, whereas the cultivars, Nonghobyeo, Saechuchungbyeo, Hwabongbyeo, Mananbyeo, did low values and others intermediate SPAD threshhold values.

• Applied Microscopy
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• v.39 no.2
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• pp.149-156
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• 2009

Fine structure of the dry adhesion system in the tarsal appendages of the jumping spider Plexippus setipes (Araneae: Salticidae) with examined using field emission scanning electron microscope (FESEM). The jumping spiders have the distinctive attachment apparatus for adhesion on smooth dry surface without sticky fluids. They attach to rough substrates using tarsal claws, however attachment on smooth surfaces is achieved by means of a tuft-like hair called a scopula. All eight legs have the scopulae with a pair of claws on the tip of feet, and each scopula is composed of two groups of setae that are capable of dry adhesion on smooth surface. The apex of each seta is flattened pad bearing many specialized adhesive setules on one side. The cuticular sensillae are interspersed at the dorsal surface of the seta. It has been revealed by this research that the contact area of the setule is always a triangular shape, and these cuticular surfaces are connected by the elongated stalks from the underlying setae. Moreover, adhesion between the numerous setules and the setae was prevented by the microscopic hairs, since these were interspersed on the upper side of the setae.

• Journal of Veterinary Clinics
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• v.32 no.3
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• pp.268-271
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• 2015

About 2-year old northern goshawk (Accipiter gentilis) which is designated as natural monument (#323-1) in Republic of Korea was rescued by a local farmer and presented with a 2-weeks history of pain, swelling, stiffness and limping. On physical examination, plantar pododermatitis and digit IV weakness were observed. Radiographic findings also showed bone lyses with soft tissue swelling in the foot. A definite diagnosis was made as stage III bumble foot after multidisciplinary approach of the patient. Bacterial culture was performed, and concurrently antibiotic susceptibility testing is determined using wound site exudates specimen. Bacterial isolates were identified as Staphylococcus aureus, known normal skin flora. Treatment was initiated with surgical incision and necrotized tissues removal. Lavage-drainage and ball bandage were applied with topical mupirocin ointment application. Doughnut shaped pad was attached on bottom of the ball bandage to reduce weight bearing. After three weeks of intensive care, the wound site completely healed but digit IV weakness remained permanently. The goshawk returned to nature after eight weeks after treatment.