• Journal of the Mineralogical Society of Korea
• /
• v.26 no.1
• /
• pp.35-44
• /
• 2013

Synthetic carbon-coated olivine-like structured lithium iron phosphate ($Li^+Fe^{2+}(PO_4)^{3-}/C$) powder composites were compressed up to 35.0 GPa in the symmetrical diamond anvil cell at room temperature. Bulk modulus of $LiFePO_4/C$ was determined to be $130.1{\pm}10.3$ GPa. New peak appears at the d-spacing of 3.386 ${\AA}$ above 18 GPa, and another new one at 2.854 ${\AA}$ around 35 GPa. The crystallographic symmetry of the sample (i.e. orthorhombic) is apparently retained up to 35 GPa as no clear evidence for the phase transition into spinel structure has been observed. The pressure-induced volume change in the M1 site ($Li^+O_6$) is more significant than those in M2($Fe^{2+}O_6$) and $PO_4$ tetrahedral sites.

• Korean Journal of Materials Research
• /
• v.3 no.4
• /
• pp.372-380
• /
• 1993

In order to improve the oxidative resistance of carbon/carbon composites, aluminium-isopropoxide and aluminium-tri-sec-butoxide sol were coated on the surface of 2D--carbon/carbon composiles and the effects uf coating were investigated. The effects of oxidative resistance were dominant in the case of catalyst/alkoxide mole ratio, 0.07, and $H_2O$/alkoxide mole ratio, 100. Through the dynamic TGA analysis with the heating rate of 20%/min, oxidative initiation tempera~ ture was enhanced about $80^{\circ}C$. The oxidative resistance effects of alkoxide sol were improved according to the times of coating. Also the 20% weight loss time of coated samples by TGA analysis was 20% better than that of un~ coated samples. The thickness of 1^{st} coated layer was about 3${\mu}$m and that of $2^{nd}$ and $3^{nd}$ coated layers was about respectively 4~5${\mu}$m and the weight loss were increased with the increasing of thermal shock test times.

• Polymer(Korea)
• /
• v.34 no.6
• /
• pp.547-552
• /
• 2010

Biodegradable polymers have gained enormous attentions in the pharmaceutical and biomedical applications, especially in drug delivery. In this work, we report the synthesis and characteristics of high molecular weight polyoxalate with ~75000 Da. Hydrolytic degradation kinetics and degradation products were characterized by nuclear magnetic resonance and gel permeation chromatography. Polyoxalate is a semicrystalline and thermally stable polymer with a glass transition temperature of ${\sim}35^{\circ}C$, which is suitable for drug delivery applications. The hydrophobic nature of polyoxalate allows it to be formulated into nanoparticles and encapsulate drugs using a conventional oil-in-water emulsion/solvent displacement method. Polyoxalate nanoparticles also exhibited excellent cytotoxicity profiles. It can be suggested that polyoxalate has great potential for numerous biomedical and pharmaceutical applications.

• Food Science and Preservation
• /
• v.15 no.6
• /
• pp.878-883
• /
• 2008

Prunus mume was extracted using various solvents including ethyl ether, ethyl acetate and n-butanol. The extracts were fractionated by column chromatography. Antimicrobial compounds (A, B and C) in fractions showing antimicrobial activity were purified by Sephadex LH 20 column chromatography, and identified by $^{1}H$- and $^{13}C$-NMR analysis as isoeugenol, nomilin and $\beta$-sitosterol, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.10
• /
• pp.2358-2364
• /
• 2010

Recently, In the wireless sensor network, a study which guarantees integrity of not only data gathered from sensor node but also energy consumption of it is now going on. However, the existing study cannot guarantee data integrity and overhead of cluster head which merges data from sensor node. This paper proposes multi-path hash chain technique which guarantees integrity of merged data and reduces overhead of cluster head when cluster head merges with data transmitted from sensor node. The proposed technique forms multi-hash chain dividing main-path and assistance-path to guarantee data integrity of cluster head, when merges data. The assistance-path, which is used when main-path is not, supports integrity of sensor node while minimizing overhead of cluster head when sensor node is authenticate.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.6
• /
• pp.1424-1430
• /
• 2013

This paper presents design procedure of the magnetic bearings used for high-speed electric machines and flywheel energy storage systems. Magnetic bearing can be categorized by inner-rotor type and outer-rotor type according to the position of the rotary disc. These two types are applicable based on application environments such as application space, required attraction force, and controllability. Magnetic bearing is generally designed based on the ratio (geometrical coefficient or geometrical efficiency) of pole width to rotor journal radius but proper ratio is only decided by the analysis. This is the difficulty of the magnetic bearing design. In this paper, proper design technology of the inner-rotor type and outer-rotor-type eight pole magnetic bearings is introduced and compared with the FEM analysis results, which verifies the proposed design procedure is suitable to be applied to the design of the magnetic bearings for the industrial applications and flywheel energy storage system.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.5
• /
• pp.507-515
• /
• 2015

This study was conducted to develop and verify a torque application device for use in a mechanical power-circulation test rig for 5.5 MW wind turbine gearboxes. The design and analysis of the torque application device was conducted. In addition, the torsional stiffness of the test rig was calculated using the rotational angle measurements for each of the components. The calculated stiffness of the test rig was $231.13kN{\cdot}m/rad$ for a clockwise torque application. The rated torque can be applied when the stiffness of the gearbox is greater than $1,064,400kN{\cdot}m/rad$ for a clockwise torque application. Because of the limited rotational angle of the test rig, the potential application of the rated torque is determined according to the torsional stiffness of the test gearbox.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.7
• /
• pp.771-777
• /
• 2014

Injection-compression molding was used for film insert molding of an automotive door grip using films with three-dimensional embossed patterns. A vacuum mold was fabricated for vacuum-assisted thermoforming of the film, and an injection-compression mold was developed for film insert molding. Three pressure transducers were installed inside the mold cavity to measure cavity pressures. Injection-compression molding experiments under various compression strokes and toggle speeds were performed to investigate their effects on the cavity pressure and heights of the embossed patterns. The compression stroke of 0.9mm and low toggle speed resulted in a higher degree of conservation of embossed patterns. Additionally, the processing conditions for the maximum heights of embossed patterns were almost similar to those for minimum integral value of cavity pressures. The injection-compression molding process presents the opportunity to impart a soft-touch feeling of plastic parts printed with embossed patterns.

• Journal of Preventive Medicine and Public Health
• /
• v.31 no.4 s.63
• /
• pp.844-856
• /
• 1998

Globally, cancer research has been considered one of the most important field of biomedical researches. Recently, in Korea, there are increasing concerns about cancer research and the development of national cancer control programme. For the efficient investment in cancer research at the national level, strategic approach is needed based on the nationwide information about current status of research. However even the basic data on cancer research have not been systematically collected, and are not available when necessary. The aim of this study is to assess current status of cancer research. For this purpose, this study applied two round Delphi method in which fifteen experts in cancer research fields participated. They rated each items on the initial list at the first round, and modified their responses at the second round. Panels responded that pathogenesis of cancer, research & development of cancer drug, and oncogene, etc. are the most urgent and important research Holds. They assessed national level of cancer research as being 49.6% of the world highest level. Coefficient of variation tended to be lowered with the iteration. Predictive stability was evaluated to be lower in items of urgency than in items of importance and research level. Although this study shares the same limitations in the selection of the experts with many other Delphi studies, it provides a primary data that would be required to plan the national strategy of the cancer research.

• The Journal of Internal Korean Medicine
• /
• v.33 no.1
• /
• pp.102-110
• /
• 2012

Multiple system atrophy (MSA) is a sporadic progressive neurodegenerative disorder characterized clinically by various combinations of parkinsonian, autonomic, cerebellar, or pyramidal signs and pathologically by cell loss, gliosis, and ${\alpha}$-synuclein-positive glial cytoplasmic inclusions in several brain and spinal cord structures. This is a clinical report about a 69-year-old female who had MSA treated by oriental medical treatment and evaluated by Unified Multiple System Atrophy Rating Scale (UMSARS). The patient was treated with herb medicine Chungsimyeonj-aeumgami(淸心蓮子飮加味), acupuncture, moxibustion and cupping. After treatment, the patient's symptoms improved meaningfully and the score decreased in UMSARS Part I, II. This suggests that oriental medical treatment could be effective to improve MSA patients' symptoms. It is necessary to have more observations and many cases of patients with MSA.