• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.32-33
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• 2006

Processing and properties of high power piezoelectric transformer (PT) fabricated by PIM with nano-sized piezoelectric powders are demonstrated. The high power characteristics of a PMed dome-shaped PT were examined by the lighting test for a 55watt PL lamp. The 55watt PL lamp was successfully driven by the PIMed PT with sustaining efficiency higher than 98%. The transformer with ring/dot area ratio of 2.1 exhibited the maximum properties in terms of output power, efficiency and temperature stability.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.537-543
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• 2014

RLG(Ring Laser Gyroscope) is a main device of LINS(Laser Inertial Navigation System). RLG has the lock-in region in which there is no output signal. To alleviate the lock-in problem, a mechanical oscillation, the dither motion, is applied on RLG. A LPF(Low Pass Filter) is usually used on the output of RLG and accelerometer to remove the noise that is made by the dither motion. When the LINS is induced the disturbance during the initial alignment, it takes more time on alignment due to the use of the LPF and a fixed gain controller. In this paper, an initial alignment using UKF(Unscented Kalman Filter) is designed and analysed. Analysis include comparison between conventional initial alignment loop using fixed gain type controller and proposed initial alignment using UKF. Moreover, Disturbance inducing test results are demonstrated.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.31-32
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• 2006

Pohang accelerator Laboratory is from 1994 analyzed electric power amount used for about 10 years. It is one of equipment that consume electric power of greate electric power to single test equipment. Accelerator Laboratory institute investigates the consumption rate of energy that is spent to each building could divide by linear accelerator and save ring and analyzed about the equipment utilization rate and average electric power. Countermeasure that this treatise can forecast power loss of electric power by equipment through analysis of electric power amount used and heighten the utilization rate of equipment wishes to do comparative analysis.

• Natural Product Sciences
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• v.13 no.4
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• pp.355-358
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• 2007

Further bioactivity-directed fractionation of the ethanol extract of the seeds of Annona cherimolia has led to the isolation of two mono-tetrahydrofuran acetogenins, xylomaticin (1) and gonionenin (2). The structures of these compounds were characterized on the basis of chemical and spectroscopic data. Compounds 1 and 2 have a relative stereochemistry relationship of threo/trans/threo across the mono-tetrahydrofuran ring with its two flanking hydroxyls. Compounds 1 and 2 are known, but are first isolated from this plant. In brine shrimp lethality test (BST), 1 and 2 exhibited cytotoxic activity.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.360-366
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• 2001

This paper show the designing, manufacturing and performance test procedure of a high speed, fixed ratio planetary roller type traction drive as a speed reducer. The arrangement and size design for sun roller, planetary rollers and ring roller are carried out and a proper pre-load mechanism are adopted. To improve transmitting power capacity and endurance limit, nitro-carburized bearing steel and a synthetic traction oil are used. The manufactured and assembled traction drive operated successfully under unloaded conditions. Further tests for various load and speed conditions are executing now to improve the performance of the traction drive.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.215-218
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• 2005

For the production of cold forged parts with near-net-shape attributes, the quality of the tool system is responsible for an essential portion of costs fer the finished components. Therefore, a tool lift is one of the important issues on cold forging industry. There are many complicated variables related with tool life, such as material, heat-treatment, coating, lubricant, process design. In this study, heat-treatment of tool material and lubricant are investigated to improve the tool life. Deep cryogenic treatment of tool steel is very efficient to improve the wear resistance due to the fine carbide. And, friction factor of lubricants for cold forging are measured by the ring compression test. Zinc-Phosphate and $MoS_2$ lubricant is effective to sustain the friction factor under 0.1.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.249-255
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• 2000

The design and test of an magnetostrictive linear motor(MLM) that operates based on self-moving cell concept is presented. The moving cell is composed of Terfenol-D linear actuator and a ring structure, and a cell train is constructed by connecting two cells in series. Since this motor uses the stroke of Terfenol-D actuators and friction force of the cells, it can essentially produce long stroke and large force. The overall performance of the MLM was measured in terms of speed and force. The pushing force is directly related with the friction force. This work is a proof-of-concept stage and investigation is necessary for realistic application.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.254-262
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• 2008

Several decades have passed since tiltrotor technology became a hot issue of debates between aircraft majors, policy maker and mass-media. Although most of those subjects have been officially probed or answered in objective way, biased articles or argues related with the adequacy of this technology still prevail in the way of tilt-rotor development programs, which are totally irrelevant and out-dated. This paper aims to help understanding on those issues in technically balanced manner and the cases of flight test mishaps.

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.184-188
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• 1999

A series of 4-amino Capsaincin anallogs 15, 17 and 19 were prepared to investigate the bioisosteric effect of 4-amino group, and all these compounds exhibited moderate or weak potency from their analgesic test. From our previous results and others, 4-hydroxyl group as well as 3-methoxy substituent could be crucial for high analgesic activity. This biological results also shows that the activity is sensitive to alkyl chain length in hydrophobic region and the phenylacetic amides 19 are more active than the corresponding urea derivatives 17.

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.75-79
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• 1991

A series of compounds, N-(2-substituted-1-carboxy)vinylazetidinones were successfully synthesized in order to test the hypothesis that biological activities of ${\beta}$-lactam antibiotics could be attributed to the smooth flow of electrons after a nucleophilic attack at the carbonyl carbon in the ${\beta}$-lactam ring. After introduction of aminothiazolylacetamido group at 3-position of the azetidinones, their biological activities were evaluated. Their low activities led to the conclusion that the smooth electron flow in ${\beta}$-lactams in not the sufficient source for the biological activities.