• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.101-109
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• 2005

The purpose of this study is to investigate the performance of outdoor heat exchanger for heat pump using carbon dioxide. Two types of fin and tube heat exchangers (2 rows for type A and 3 rows for B) are tested. Both heat exchangers have counter-cross flow and 1-circuit arrangement. Test results such as heat transfer rate, pressure drop characteristics and temperature distribution in the heat exchanger are shown with respect to mass flow rate of refrigerant and frontal air velocity For cooling mode, the minimum temperature difference between air and refrigerant of type B is smaller than that of type A by $1^{circ}C$, but the pressure loss of air side is much higher for type B by $29\%$. It is found that a large temperature gradient of carbon dioxide during gas cooling Process Promotes thermal conduction through tube wall and fins which results in degradation of heat transfer performance. For heating mode operation, type B heat exchanger shows higher heat transfer performance compared to type A. However, because pressure loss of refrigerant side of type B is much greater than that of type A, the refrigerant outlet pressure of type B becomes lower than that of type A.

• Journal of Ginseng Research
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• v.20 no.4
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• pp.389-415
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• 1996

Panax ginseng C.A. Meyer(Araliaceae) has been traditionally used as an expensive and precious medicine in oriental countries for more than 5, 000 years. Ginseng saponin isolated from the root of Panax ginseng have been regarded as the main effective components responsible for the pharmacological and biological activities. Such as antiaging effects. antidiabetic effects anticancer effects. Protection against physical and chemical stress. Analgesic and antipyretic effects. Effects on the central nervous system, tranquilizing action and others. Thirty kinds of ginsenosides have been so far isolated from ginseng saponin and their chemical structures have been elucidated since 1960's. Among which protopanaxadiol type is 19 kinds. protopanaxatriol type. 10 kinds and oleanane type, one. Since ginsenosides are generally labile under acidic conditions ordinary acid hydrolysis is always accompanied by many side reactions, such as epimerization. hydroxylation and cyclization of side chain of the sapogenins Especially. it is well known that C-20 glycosyl linkage of ginsenoside was hydrolysed on heating with acetic acid to give an equilibrated mixture of 20(S) and 20(R) epimers. And also, the chemical transformations of the secondary metabolites have appeared during the steaming process to prepare red ginseng. Indicating demalonylation of malonyl ginsenosides, elimination of glycosyl residue at C-20 and isomerization of hydroxyl configuration at C-20. But these studies have not provided a comprehensive picture in explaning how these ginsenosides showed val'iotas pharmacological activities of ginseng. Though some of them have been involved in the mechanism of pharmacological actions. Recently, non-saponin components have received a great deal of attention for their antioxidant, anticancer antidiabetic, immunomodulating. anticomplementary activities and so on. To meet the demand for such wide applications, studies on the non-saponin components play an important role in providing a good evidence of pharmacological and biol ogical activities. Among the non-saponin constituents of Korean ginseng, polyacetylenes, phenols. Sesquiterpenes, alkaloids. polysaccharides oligosaccharides, oligopeptides and aminoglycosides together with ginsenosides of terrestrial part are mainly described.

• Clean Technology
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• v.11 no.4
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• pp.205-211
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• 2005

There have been many technologies and materials proposed for realizing microlens array, and plastic injection is recognized as the most promising one because of several merits such as optical properties, impact resistance, formability, lightening and environmental adaptability. Since PR reflow for injection template fabrication enables the lens shape control easier, and the sample technology more effective for mass production, it lowers the cost, enhances integration, and reduces process steps, which leads to be environmentally benign. However injection of polymers may face the difficulty of formability depending on their properties. In order to overcome the difficulty, fast heating/cooling technology was introduced in this study, and microlenses were fabricated and evaluated. template obtained by PR reflow method was heated and cooled fast during injection to fabricate microlens array. PC and PMMA polymer materials were compared, and it was realized that PMMA showed much better formability due to its lower melting temperature. Injection parameters of pressures and velocities were driven out for injection optimization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.666-668
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• 2015

Recent domestic IoT (Internet Of Things) technologies and research is being actively conducted, it actually provides power control, heating control such services in the home or office. Depending on the interest of the IoT so as to provide convenient services to users also increased their users are increasingly questioning or wondering about the operation of IoT system. The system representing an easy to understand the operation of the IoT system is required in order to meet the requirements of those users. For this purpose this paper, Swing utilization by user, sensor, SNS (Social Network Service) when an event occurs, such as the relationship between devices bearing the collaboration process can be monitored with a simulation program was designed and implemented.

• Korean Journal of Materials Research
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• v.14 no.4
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• pp.293-299
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• 2004

Transition metal ions doped $TiO_2$ nanostructured powders were prepared with simply heating aqueous $TiOCl_2$ solutions, contained various metal ions (Ni, Al, Fe, Zr, and Nb) of 1.47 mol% added as metal-chlorides, at $100^{\circ}C$ for 4 hrs by homogeneous precipitation process under suppressing conditions of water vaporization. The characterizations for prepared $TiO_2$ powders were carried out to observe doping of metal ions, their concentrations and microstructures using XRD, UV-VIS (DRS), XPS, SEM, TEM and ICP. Also, photo-oxidative abilities were evaluated by decomposition of 4-chlorophenol (4CP) under ultraviolet light irradiations. No secondary oxide phases were formed in all the $VTiO_2$ powders, showing doping with various transition metal ions. When adding ions ($Ni^{2+}$ or$ Al^{3+ }$ and $Zr^{4+}$ ) having valance states or ionic radii greatly different from those of $Ti^{4+}$ , the $TiO_2$ powders of mixed anatase and rutile phases were formed, whereas in the case of additions of $^Fe{3+ }$ and $Nb^{ 5+}$ as well as no addition of metal ion the powders with pure rutile phase alone were formed. Among the prepared $TiO_2$ powders, Ni$^{2+}$ doped $TiO_2$ powders, containing a small amount of anatase phase, showed excellent photo-oxidative ability in 4CP decomposition because of relative decreases in electron-hole recombination and poisoning of $TiO_2$ surface during the photoreaction.n.

• Polymer(Korea)
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• v.32 no.1
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• pp.77-84
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• 2008

The thermal properties, morphology, mechanical properties and gas permeability of the blends of poly (amic acid) (PAA) and poly (o-hydroxyamides) (PHAs) having pendant group was investigated. The 5% weight loss and major weight loss of the b)ends occurred in the ranges of $348{\sim}407^{\circ}C$ and $589{\sim}615^{\circ}C$ upon a heating process. After a thermical annealing, the tensile strength and initial modulus of blends increased $3.7{\sim}52.9%$ and $34.4{\sim}70%$ from the value of pure PAA, respectively. Especially the tensile strength and modulus of the PAA/MP-PHA=9/1 showed the highest values (97.5 MPa and 2.67 GPa, respectively), which were 53 and 70% higher than those of pure PAA. The fine PHA domains were found to be uniformly dispersed. The interfacial adhesion between PAA and PHA was identified to be good. The gas permeabilities of PAA/M-PHA blend increased with M-PHA contents.

• Solar Energy
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• v.15 no.3
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• pp.15-27
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• 1995

This study presents experimental and numerical results of the temperature characteristics, the heat transfer phenomema, and the heat storage quantity during the heat storage process with sodium phyrophosphate decahydrate($Na_4P_2O_7{\cdot}10H_2O$)-Phase Change Material(PCM) in a latent heat storage tank(cubic type). It was proved that heat transfer by conduction was dominant because PCM($Na_4P_2O_7{\cdot}10H_2O$) during heating processes was gel phase, not liquid phase The gap ratio(rate of air content) of PCM became smaller, the thermal capacity of PCM became larger, therefore the temperature distribution of PCM slowly increased than that of large gap ratio. There was maximum 15% difference between measured temperatures and calculated temperatures.

• Journal of Magnetics
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• v.21 no.1
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• pp.35-39
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• 2016

$Cr_{100-x}Ti_x$ amorphous texture-inducing layers (TIL) were investigated to realize highly (002) oriented $L1_0$ FePt-C granular films through hetero-epitaxial growth on the (002) textured bcc-$Cr_{80}Mn_{20}$ seed layer (bcc-SL). As-deposited TILs showed the amorphous phase in Ti content of $30{\leq}x(at%){\leq}75$. Particularly, films with $40{\leq}x{\leq}60$ kept the amorphous phase against the heat treatment over $600^{\circ}C$. It was found that preference of the crystallographic texture for bcc-SLs is directly affected by the structural phase of TILs. (002) crystallographic texture was realized in bcc-SLs deposited on the amorphous TILs ($40{\leq}x{\leq}70$), whereas (110) texture was formed in bcc-SLs overlying on crystalline TILs (x < 30 and x > 70). Correlation between the angular distribution of (002) crystal orientation of bcc-SL evaluated by full width at half maximum of (002) diffraction (FWHM) and a grain diameter of bcc-SL indicated that while the development of the lateral growth for bcc-SL grain reduces FWHM, crystallization of amorphous TILs hinders FWHM. $L1_0$ FePt-C granular films were fabricated under the substrate heating process over $600^{\circ}C$ with having different FWHM of bcc-SL. Hysteresis loops showed that squareness ($M_r/M_s$) of the films increased from 0.87 to 0.95 when FWHM of bcc-SL decreased from $13.7^{\circ}$ to $3.8^{\circ}$. It is suggested that the reduction of (002) FWHM affects to the overlying MgO film as well as FePt-C granular film by means of the hetero-epitaxial growth.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.478-488
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• 1999

The contents of histidine dipeptides, a metabolic products of muscle protein, were investigated to compare muscle composition among the 9 domestic animals including cattle. In major domestic animals, analyzed the effects of age, part and sex of the animals on their muscle composition. Large amounts of carnosine($68.63{\pm}17.41{\mu}mol/g$) were detected in cattle and it was higher than other animals. Whereas the content of anserine showed high level in order of turkey, chickens and duck. The ratio of carnosine and anserine(C/A ratio) was different depending on the animal species. Statistical data indicated that difference among species was significant(p < 0.05). The contents of histidine dipeptides in heated muscle by boiling for 40 minutes at $110^{\circ}C$ was similar to thoes of raw muscle. C/A ratio in heated muscle was not different from that of raw muscle, indicating that no change has been made after heating process. The contents of carnosine and anserine were different according to the parts of their muscle. Especially chuck of the mammalian showed extremely low level of histidine dipeptides compared with other parts, while C/A ratio maintained certain level regardless of age, part, sex. Therefore, based on the content of histidine dipeptides, could be found the difference of muscle composition among the species. Also C/A ratio of horse, pig, cattle, duck, sheep and turkey were characteristic respectively.

• Journal of the Korean Wood Science and Technology
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• v.29 no.4
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• pp.79-88
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• 2001

Lectin was isolated from shiitake mushroom (Lentinula edodes) with 0.15 M NaCl solution, and purified by the following procedures : precipitation by ammonium sulfate, anion exchange column chromatography on DEAE Sephadex A-50 and hydroxyapatite column chromatography. The fresh pileus part of the mushroom contained more than two times of lectin compared to the stipe part, and lectins and its activity were reduced by heating. The extraction yield of crude lectin was 46.03%, 28% yield after purification on on DEAE Sephadex A-50 column chromatography. Some amino acids, aspartic acid, serine, alanine and histidine, were increased by purification process. Relatively low molecular weight parts of lectin had the agglutinating activity for rabbit blood, and its molecular weight was about 23 kDa The molecular weights of purified lectins, LA-a and LB-b, by the hydroxyapatite column chromatography were 24 kDa and 23 kDa, respectively.