• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.957-965
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• 2011

The wakes of a cylindrical body have been investigated. The cylindrical body was attached with a thin film. The film is made of silicon with configurations of 50mm(W) ${\times}$ 150mm(L) ${\times}$ 0.3mm(T). The cylinder wakes have been measured with PIV experiments under the conditions with and without the thin film. The diameter of the installed cylinder body is 30mm and the Reynolds numbers are 2730, 6160 and 9750 with the diameter. The measurement system consists of an Ar-ion laser(6W), a high speed camera(1024 ${\times}$ 992 pixel, 500fps) and a host computer. FFT analyses have been carried out using the velocity vectors obtained by PIV measurements at the point X/D=1.52 and Z/D=0.52. For understanding the three-dimensional flow structures, a new Volumetric PTV(particle tracking velocimetry) has been constructed, in which the same four high-resolution cameras have been used. It has been verified that the flexible film suppresses or damps the vortices separated from the cylinder body, which makes the cylinder's wakes stable. With increase of Re numbers the intensity of the dominant frequency of the wakes become smaller.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.1
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• pp.11-17
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• 2002

This paper compares the difference between the village groves in the Jinan settlement region and the Hamyang settlment region in Honam and the Youngnam mountainous region. The results are as follows: Fifty-one village groves in the Jinan legion were found and 40 village groves were found in the Hamyang region. It was established that the village groves in the Jinan region of Honam province were conserved better than those of Hamyang region of Youngnam province. In the Jinan area, the village groves were principally found in the Jinan-eup and the Hamyang regions, primarily in Seosang-myun and Aneui-myun. So it was determined that the village groves were distributed inequitably in the two regions. In L / W ratio, the Jinan region is 3.6 and Hamyang region is 2.0 Jinan is 1.8 times greater than Hamyang. Therefore, it was concluded that Jinan is stronger than Hamyang in linear function of the village groves. Stone stooge for complementation function was found in 11 village groves in the Jinan region and 6 village groves in Hamyang. So the percentage of the remaining stone storage is 15-20 % of all village groves. Regarding grove makeup, the village gloves in Jinan region is deciduous forest principally. In contrast, the groves of Hamyang are principally coniferous forest. The dominant tree of the Jinan-gun region is Zelkova serrata, but in Hamyang it is Pinus densiflrora. By number, Hamyang region has two times the trees than Jinan region. In density of stand, the Hamyang region is 76.2% higher than Jinan region. In height and diameter of trees, the Jinan region is greater than the Hamyang region. It was identified that RSI of both region is 40%. So in density of trees, both region are sparse. This paper has a limit in ideiltiting the differences between Yolmg-nam ar\ulcorner Hnam village groves because comparative review only examined two regions.

• Progress in Superconductivity and Cryogenics
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• v.5 no.3
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• pp.6-10
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• 2003

Silver nano-powder was added to Ma $B_2$ to make (Ag)$_{(x)wt.%}$(Mg $B_2$)$_{(l00-x)wt.%}$ (A $g_{x}$-Mg $B_2$) (10 $\leq$ x $\leq$ 50) composite superconductors to investigate the effect of the Ag nano-powder on the vortex pinning. Pellets made out of the mixed powder were put inside stainless steel tubes, which were sintered at 85$0^{\circ}C$ in Ar atmosphere. No impurity phase was identified for as-rolled samples. However, both the Mg $B_2$ and the A $g_{x}$-Mg $B_2$ composite pellets, when sintered, contain small amount of Mg $B_4$ and MgAg impurity phases. From the magnetization study, it was found that the flux pinning was improved in the high magnetic field region (> 3 T) only when 10w/o Ag was added to Mg $B_2$. The "two step" structures in ZFC M(T) curve gradually increased as the amount of Ag added increased. Pinning centers can be created by adding a suitable amount of Ag nano-powder which is not too large to increase the decoupling between the Mg $B_2$ grains.crease the decoupling between the Mg $B_2$ grains.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.543-543
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• 2013

Thin-film transistors (TFTs) based on oxide semiconductors have been regarded as promising alternatives for conventional amorphous and polycrystalline silicon TFTs. Oxide TFTs have several advantages, such as low temperature processing, transparency and high field-effect mobility. Lots of oxide semiconductors for example ZnO, SnO2, In2O3, InZnO, ZnSnO, and InGaZnO etc. have been researched. Particularly, zinc-tin oxide (ZTO) is suitable for channel layer of oxide TFTs having a high mobility that Sn in ZTO can improve the carrier transport by overlapping orbital. However, some issues related to the ZTO TFT electrical performance still remain to be resolved, such as obtaining good electrical contact between source/drain (S/D) electrodes and active channel layer. In this study, the bottom-gate type ZTO TFTs with staggered structure were prepared. Thin films of ZTO (40 nm thick) were deposited by DC magnetron sputtering and performed at room temperature in an Ar atmosphere with an oxygen partial pressure of 10%. After annealing the thin films of ZTO at $400^{\circ}C$ or an hour, Cu, Mo, ITO and Ti electrodes were used for the S/D electrodes. Cu, Mo, ITO and Ti (200 nm thick) were also deposited by DC magnetron sputtering at room temperature. The channel layer and S/D electrodes were defined using a lift-off process which resulted in a fixed width W of 100 ${\mu}m$ and channel length L varied from 10 to 50 ${\mu}m$. The TFT source/drain series resistance, the intrinsic mobility (${\mu}i$), and intrinsic threshold voltage (Vi) were extracted by transmission line method (TLM) using a series of TFTs with different channel lengths. And the performances of ZTO TFTs were measured by using HP 4145B semiconductor analyzer. The results showed that the Cu S/D electrodes had a high intrinsic field effect mobility and a low effective contact resistance compared to other electrodes such as Mo, ITO and Ti.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.620-625
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• 2002

Considering the fuel consumption of car, a light structure of aluminum alloys is desired for car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. ill the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6N01 alloy welds. Aluminum alloy plate of 2.0mm in thickness with filler metal bar was welded by twin beam Nd:YAG laser facility (total power:5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 l/min was used. The defocusing distance is kept at 0 mm. At travel speeds of 3 to 9 m/min and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.

• Advances in Traditional Medicine
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• v.3 no.4
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• pp.191-195
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• 2003

Euphorbia hirta, locally called 'ara tanah' or 'susun nabi' in Malaysia is a small annual herb common to the tropical countries and belongs to the same family as the tic and tapioca. E. hirta has had a long history of usage in the treatment of various ailments. In this current study, in vitro sensitivity test of crude aqueous and ethanol extracts of leaves and barks of E. hirta was carried out against bacteria (Escherichia coli, Salmonella enteritidis, Staphylocccus aureus and Bacillus subtilis) and fungi (Microsporum canis, Aspergillus fumigatus, Candida albicans and Candida tropicalis) using the discs diffusion method. The extract-impregnated discs (20, 40 and $80\;{\mu}g/{\mu}l$), the E. hirta extracts inhibited the growth of all the bacteria tested. The growth of C. albicans was inhibited in a concentration dependent manner by the aqueous leaves and barks extracts. C. tropicalis was found to be sensitive to the aqueous leaves extracts. The results were compared to antibacterial drugs of chloramphenicol, ampicilin, penicillin G, and enrofloxacine; and to antifungal drug of ketoconazole, itraconazole and miconazole. In this current study, it can be concluded that this plant has antimicrobial activity that is as potent as the standard antimicrobial drugs against certain microorganisms.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.133-133
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• 1998

In the thin film alloy formation of the transition metals ion-beam-mixing technique forms a metastable structure which cannot be found in the arc-melted metal alloys. Sppecifically it is well known that the studies about the electronic structure of ion-beam-mixed alloys pprovide the useful information in understanding the metastable structures in the metal alloy. We studied the electronic change in the ion-beam-mixed ppt-Ct alloys by XppS and XANES. These analysis tools pprovide us information about the charge transfer in the valence band of intermetallic bonding. The multi-layered films were depposited on the SiO2 substrate by the sequential electron beam evapporation at a ppressure of less than 5$\times$10-7 Torr. These compprise of 4 ppairs of ppt and Cu layers where thicknesses of each layer were varied in order to change the alloy compposition. Ion-beam-mixing pprocess was carried out with 80 keV Ae+ ions with a dose of $1.5\times$ 1016 Ar+/cm2 at room tempperature. The core and valence level energy shift in these system were investigated by x-ray pphotoelectron sppectroscoppy(XppS) pphotoelectrons were excited by monochromatized Al K ａ(1486.6 eV) The ppass energy of the hemisppherical analyzer was 23.5 eV. Core-level binding energies were calibrated with the Fermi level edge. ppt L3-edge and Cu K-edge XANES sppectra were measured with the flourescence mode detector at the 3C1 beam line of the ppLS (ppohang light source). By using the change of White line(WL) area of the each metal sites and the core level shift we can obtain the information about the electrons pparticippating in the intermetallic bonding of the ion-beam-mixed alloys.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.9-17
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• 2002

A high-efficiency electronic ballast for HID lamps is presented. The ballast consists of a PFC and a resonant inverter. To reduce losses of the ballast, DC link voltage should be determined by taking into account the peak voltage of lamp and the maximum flux density should be kept 0.2[T] on all of inductors. AR inductor at bridge diode is employed in order to remove currant harmonics from PFC. An inductor is connected in series with an electrolytic capacitor at DC link to reject high-frequency current. The acoustic resonance is eliminated using the stead spectrum technique. The electronic ballast for 250[W] metal-halide discharge lamp is implemented and 96[%] efficiency, no acoustic resonance and low conducted EMI level are accomplished.

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1470-1475
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• 2009

The seed coat of the black soybean contains 3 main anthocyanins such as delphinidin-3-O-$\beta$-glucoside, cyanidin-3-O-$\beta$-glucoside, and petunidin-3-O-$\beta$-glucoside. As a part of our effort on discovering and breeding new black soybean cultivars which possesses specific anthocyanin component rich, we determined the anthocyanin profiles of the 2 cultivars recently developed soybean cv. Gaechuck #1 and cv. Gyeongsang #1, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and compared their content and identity with those of previously known 10 cultivar controls. The Cosmosil-$5C_{18}$-AR-II column were selected for the analysis because of the best peak separation. The column temperature was set up at $35^{\circ}C$. The mobile phase consisting of water containing 0.5%(v/v) formic acid and methanol gave good separation between the 3 anthocyanin analytes and internal standard (quercetin 3-O-$\beta$-rutinoside) and peaks with suppressed tail. The MS/MS spectra of each individual anthocyanin standard were detected in positive electron spray ionization (ESI) modes. It was disclosed that the anthocyanin contents of the soybean cv. Gaechuck#1 and cv. Gyeongsang#1 are roughly higher than those of the 10 controls.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.86.2-86.2
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• 2011

We investigate the evolution of coronal loop emission in the context of the coronal magnetic field topology. New modeling techniques allow us to investigate the magnetic field structure and energy release in active regions (ARs). Using these models and high-resolution multi-wavelength coronal observations from the Transition Region and Coronal Explorer and the X-ray Telescope on Hinode, we are able to establish a relationship between the light curves of coronal loops and their associated magnetic topologies for NOAA AR 10963. We examine loops that show both transient and steady emission, and we find that loops that show many transient brightenings are located in domains associated with a high number of separators. This topology provides an environment for continual impulsive heating events through magnetic reconnection at the separators. A loop with relatively constant X-ray and EUV emission, on the other hand, is located in domains that are not associated with separators. This result implies that larger-scale magnetic field reconnections are not involved in heating plasma in these regions, and the heating in these loops must come from another mechanism, such as smallscale reconnections (i.e., nanoflares) or wave heating. Additionally, we find that loops that undergo repeated transient brightenings are associated with separators that have enhanced free energy. In contrast, we find one case of an isolated transient brightening that seems to be associated with separators with a smaller free energy.