• Proceedings of the KSME Conference
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• 2003.11a
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• pp.798-803
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• 2003

The objective of the present study is to investigate the changes in the acoustic source characteristics and far-field noise propagation in an incompressible round jet at Re=10000 for single-frequency excitations using large eddy simulation and Lighthill acoustic analogy. We apply excitations at a frequency corresponding to the jet-column mode ($St_{D}=0.85$) or maximum growth rate in the shear layer ( $St_{\theta}=0.017$ ). The acoustic source derived from the Lighthill acoustic analogy is the second spatial derivative of the Reynolds stresses. In the case of $St_{D}=0.85$, vortex ring and large scale structures are dominant sources, whereas in the case of $St_{\theta}=0.017$, the main sources are located at an upstream position along the shear layer than in the uncontrolled case. Also, the far-field noise propagates along the axial direction due to excitation.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.113-117
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• 1997

In this paper we detected the thrombosis formation by spectral analysis and neural network. Using microphone and amplifier, we measured the sound from the mechanical valve which is attached to the pneumatic ventricular assist device. The sound was sampled by A/D converter and the periodogram is the main algorithm or obtaining spectrum. We made the valvular thrombosis models using pellethane and silicon and they are thrombosis model on the disk, around the sewing ring and fibrous tissue growth across the orifice of valve. The spectrum of normal and 5 kinds of thrombotic valve were obtained and primary and secondary peak appeared in each spectrum waveform. So to distinguish the secondary peak of normal and thrombotic valve quantatively, 3 layer back propagation neural network.

• Journal of the Korean Wood Science and Technology
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• v.2 no.2
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• pp.4-4
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• 1974

In this paper, the microscopic structure of wood was investigated for following species in Malaysia.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.31-34
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• 2003

The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by chemical and mechanical polishing(CMP) process. The sapphire crystalline wafers were characterized by double crystal X-ray diffraction. The sample quality of sapphire crystalline wafer at surfaces has a full width at half maximum 89 arcses. The surfaces of sapphire wafers were mechanically affected by residual stress and surface default. Sapphire wafers's waveness has higher abrasion rate in the edge of the wafer than its center due to Newton's Ring interference.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3317-3321
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• 2013

A series of new 3-alkylamino-6-allylthio-pyridazine derivatives was synthesized through allythiolation and amino-de-halogenation and were expected to have anti-proliferative activity. 6-Allylthio-3-chloropyridazine was prepared from the reaction of 3,6-dichloropyridazine with allylmercaptan and sodium hydroxide. The alkylamines such as methylamine and the dialkylamines such as dimethylamine were introduced into the 3-position of the pyridazine ring. These new compounds showed anti-proliferative activities against MCF-7 human breast cancer cells in CCK-8 assays. These compounds are thus promising candidates for chemotherapy of breast cancer. Two compounds, 14 and 15, showed higher potencies for inhibiting growth of breast cancer cells than did 5FU. This suggests the potential anti-proliferative activity of these compounds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.1
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• pp.85-91
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• 2004

The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by chemical and mechanical polishing process. The sapphire crystalline wafers were characterized by double crystal X-ray diffraction. The sample quality of sapphire crystalline wafer at surfaces has a full width at half maximum of 89 arcsec. The surfaces of sapphire wafer were mechanically affected by residual stress during the polishing process. The wave pattern of optical interference of sapphire wafer implies higher abrasion rate in the edge of the wafer than its center from the Newton's ring.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1319-1320
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• 2006

Several practical applications of melt-textured bulk superconductors require the complex-shaped products such as curved, ring-shaped, and drilled blocks rather than simple shaped pellets. However, melt-textured bulk superconductors are often damaged when they are cut, grinded, or drilled. With the aim of reducing such damages, we have investigated the preparation of the complex-shaped bulk superconductors by previously machining binder-added precursors and pre-sintered precursors. We could produce various complex-shaped bulk superconductors without cracking from these machined precursors

• The Korean Journal of Quaternary Research
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• v.6 no.1
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• pp.21-32
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• 1992

The paleoclimate of the Chungbu Mountainous Region, Mts. Seorak and Sobaek, was estimated by means of dendroclimatic methodology, The annual growth value of tree-rings is deeply interrelated with the mean temperature of April-May and July-August. The mean temperature of April-May of the reconstruction period(1635-1911), observation period(1912-1989), and the whole period(1635-1989) is 13.58$^{\circ}C$, 13.69$^{\circ}C$, and 13.6$0^{\circ}C$, respectively. That of July-August is $24.50^{\circ}C$, $24.62^{\circ}C$, and $24.58^{\circ}C$ respectively. The reconstructed mean temperature data for April-May and for July-August reveal 13.2 and 12.9 year cycles.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.959-965
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• 2005

Investigation of structure-activity relationships of novel quinazolines has identified 7,8-dihydro-[1,4]dioxino-[2,3-g]quinazolines as a potent inhibitor of EGFR. These compounds have a benzodioxane framwork, which was prepared by regioselective O-alkylation of ethyl 3,4-dihydroxy benzoate by epoxide ring opening. Compounds 3f and 3k were more potent than ZD-1839 in EGF enzyme and EGFR autophosporylation inhibition assays.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.83-91
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• 2009

To develop new anticancer agents, 3-allylthio-6-aminopyridazine derivatives were synthesized from maleic anhydrides or phthalic anhydrides by formation of a pyridazine nucleus, dichlorination, allylthiolation and amination. The pyridazine nuclei were obtained by condensing a hydrazine monohydrate with maleic anhydride. An allylthio group as a pharmacologically active group was introduced into one side of a pyridazine ring. Arylalkylamines with benzene or pyridine moieties or heterocycloalkylamines with heterocycle moieties such as morpholine, piperidine, or pyrrolidine were also introduced into the para-position of allylthio pyridazine. These new compounds showed antiproliferative activities against SK-Hep-1 human liver cancer cells in MTT assays. These compounds are thus promising candidates for chemotherapy of hepatocellular carcinomas. Two compounds, 20c and 22a, showed higher potencies for inhibiting growth of hepatocellular carcinoma cells than did K6 ($ID_50$=1.08 mM). This suggests the potential anticancer activity of these two compounds.