• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.77-85
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• 2004

To evaluate the effect of plasma cleaning on the soldering reliability the plasma cleaning using Ar-10vol%$H_2$ gas was applied on a UBM(Under Bump Metallization). The UBM consisted of Au/ Cu/ Ni/ Al layers which were deposited on a Si-wafer with 20 nm/ 4 $\mu\textrm{m}$/ 4 $\mu\textrm{m}$/ 0.4 $\mu\textrm{m}$ thickness respectively. Sn-3.5%Ag, Sn-3.5%Ag-0.7%Cu and Sn-37%Pb solder balls sized of 500 $\mu\textrm{m}$ in diameter were used. Solder balls on the UBM were plasma reflowed under Ar-10%$H_2$ plasma (with or without plasma cleaning). They were compared with air reflowed solder balls with flux. The spreading ratios of plasma reflowed solder with plasma cleaning was 20-40% higher than that of plasma reflowed solder without plasma cleaning. The shear strength of plasma reflowed solder with plasma cleaning was about 58-65MPa. It showed 60-80% higher than that of plasma reflowed solder without plasma cleaning and 15-35% higher than that of air reflowed solder. Thus it was believed that plasma cleaning for the UBM using Ar-10vol%$H_2$ gas was considerably effective for the improvement of the strength of solder ball.

• The Korean Journal of Malacology
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• v.27 no.1
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• pp.15-27
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• 2011

This study was performed to observe ultrastructure of the gill and to ascertain the effect of salinity on histopathological and ultrastructural changes in the gill of the Japanese clam, Corbicula japonica. Experimental period was 7 days. Experimental groups consisted of control, 5, 10, 20 psu. $LC_{50}$ (96 h.) by the probit was 19.55 psu. Mortality was significantly different from the control (p < 0.05). Inner demibranch of the gill of C. japonica was wider 1.37 times than outer demibranch (p < 0.001). The filament zone on the plica can be distinguished by the six epithelial celll cell; frontal ciliated epithelium ($7{\mu}m$), latero-frontal ciliated epithelium ($5{\mu}m$), postlatero-frontal epithelim ($3{\times}8{\mu}m$), and lateral ciliated epithelium ($5{\mu}m$) in the frontal zone, endothelial cellin the intermediate zone, and abfrontal cell in the abfrontal zone. It had one type of secretory cell that was filled with fibrous substances of low electron density. The gill of C. japonica exposed to 5 psu for 7 days was observed partially disappearance of the cilia, and glycogen granule in the filament. In the 10 psu, gill appeared partially modification of epithelial cell and destruction of the glycocalyx. Gill exposed to 20 psu was extended nuclus of the ciliated epithelial cell, destruction of the organelles, and observed glycogen granules infiltration and numerous vacuoles. Moreover, more than 50% filaments were observed that come out chitinous rod from disappearance of epithelial cell in the filament. Therefore, the destruction of the cilia and epithelial cell induce physiological activity and it may be leading directly to death.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.953-958
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• 2014

The use of functionally graded materials (FGMs) may enhance thermal conductivity without reducing the desired strength in many applications such as injection molds embedding conformal cooling channels and cutting tools with heat sinks (or cooling devices). As a fundamental study for cutting tools having FGM heat sinks between M2 tool steel and Cu, six FGM specimens (M2 and Cu powders were premixed such that the relative compositions of M2 and Cu were 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 wt%) were fabricated by powder metallurgy in this study. The cross sections of these specimens were observed by optical microscopy, and then the material properties (such as thermal conductivity, specific heat, and coefficient of thermal expansion) related to heat transfer were measured and analyzed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.22-29
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• 2007

A 2.5Gb/s 2:1 multiplexer(MUX) IC using $0.18{\mu}m$ CMOS was designed and fabricated. Inductive peaking technology was used to improve the performance. On-chip micro spiral inductor was designed to maximize the inductive peaking effect without increasing the chip area much. The designed 4.7 nH micro-spiral inductor was $20\times20{\mu}m2$ in size. 2:1 MUX with and without micro spiral inductors were compared. The rise and fall time was improved more than 23% and 3% respectively using the micro spiral inductors for 1.25Gb/s signal. For 2.5 Gb/s signal, fall and rise time was improved 5.3% and 3.5% respectively. It consumed 61mW and voltage output swing was 1$180mV_{p-p}$ at 2.5Gb/s.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1450-1456
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• 2015

The received signal strengths according to the propagation distance between a transmitting shore station with a 53 m antenna hight and a receiving ship station with about 6m antenna hight from 700 m upto about 20 km are measured at ship's moving velocity of $5{\pm}1m/s$ using a single carrier signal at 150.0625MHz. In this paper, the path loss exponents at the propagation distance from 700 m to 20km are estimated via minimum-mean-square-error method using the measurements of the received signal strength, and the mean of the estimated path loss exponent become 3.79. The estimated propagation path loss exponents is similar to that calculated based on the field-strength values from 2 km to 20 km in Annex 2 of ITU-R P.1546-4, which is measuring results at maritime VHF at 100 MHz carrier frequency. Therefore, the estimated propagation path loss exponent shall be used as the expected path loss exponents for summer in costal area of South Sea of Korea.

• Korean journal of applied entomology
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• v.43 no.4 s.137
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• pp.329-332
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• 2004

This experiment was conducted to investigate pathogenicity of Spodoptera exigua nucleopolyhedrovirus (SeNPV) with different temperatures for mass production. In laboratory condition, $LC_{50}$ values of SeNPV were $9.797{\times}10^{3}PIBs/mL$ at $20^{\circ}C$ and $3.351{\times}10^{2}PIBs/mL$ at $32^{\circ}C$ in 2nd instar larvae. $LC_{50}$ of the other larval stage were similar to that of 2nd instar. $LT_{50}$ values of SeNPV was 9.0 days in $1.0{\times}10^{3}PIBs/mL$ but 6.9 to 3.5 days in $1.0{\times}10^{4-6}PIBs/mL$ against 3rd instar of Spodoptera exigua. $LT_{50}$ Values of $1.0{\times}10^{4}PIBs/mL$ were 5.7, 5.5 and 4.9 days in 24, 28 and $32^{\circ}C$, respectively. As a results, $LT_{50}$ was shortened with increase of temperatures up to $32^{\circ}C$ and also dependent on viral concentration and larval instars.

• Korean Journal of Plant Resources
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• v.24 no.4
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• pp.461-471
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• 2011

This study was carried out to establish an in vitro culture method of callus having a high antioxidant activity from Ginkgo biloba L. Leaf explants were cultured on Murashige and Skoog's medium supplemented with various growth regulators. The explants were incubated in the dark or 3,000 lux cool-white light. Methanol extracts from incubated callus were evaluated for scavenging activity of the free radicals using DPPH. The best callus growth rate was achieved in MS medium combined with 10 ${\mu}M$ NAA and 5 ${\mu}M$ kinetin in the light condition. Total antioxidant activity of cell aggregates in suspension culture [MS medium supplemented with 10 ${\mu}M$ NAA in the light] was up to 80% of ascorbic acid. By means of HPLC analysis, quantification of the quercetin dehydrate and keamperol profiles from suspension callus was compared. Contents of quercetin dehydrate and keamperol from leaf extracts were 0.07 and 2.24 ${\mu}g/20{\mu}l$, and those from callus 0.56 and 0.18 ${\mu}g/20{\mu}l$, respectively.

• Korean Journal of Metals and Materials
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• v.49 no.5
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• pp.411-418
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• 2011

The current study investigates the electroplating characteristics of Sn-Cu eutectic micro-bumps electroplated on a Si chip for flip chip application. Under bump metallization (UBM) layers consisting of Cr, Cu, Ni and Au sequentially from bottom to top with the aim of achieving Sn-Cu bumps $10\times10\times6$ ${\mu}m$ in size, with 20${\mu}m$ pitch. In order to determine optimal plating parameters, the polarization curve, current density and plating time were analyzed. Experimental results showed the equilibrium potential from the Sn-Cu polarization curve is -0.465 V, which is attained when Sn-Cu electro-deposition occurred. The thickness of the electroplated bumps increased with rising current density and plating time up to 20 mA/$cm^2$ and 30 min respectively. The near eutectic composition of the Sn-0.72wt%Cu bump was obtained by plating at 10 mA/$cm^2$ for 20 min, and the bump size at these conditions was $10\times10\times6$ ${\mu}m$. The shear strength of the eutectic Sn-Cu bump was 9.0 gf when the shearing tip height was 50% of the bump height.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.297-297
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• 1994

It has been known that adrenal corticosteroids influence the expression of adrenomedullary catecholamine-synthetizing enzymes and also suppress the emission of axonal-like processes in cultured chromaffin cells. In the present study, it was attempted ta investigate the effect of 17${\alpha}$-estradiol on catecholamine(CA) secretion evoked by acetylcholine(ACh), DMPP, McN-A-343, excess K$\^$+/ and Bay-K-8644 from the isolated perfused rat adrenal gland. The perfusion of 17${\alpha}$-estradiol (10$\^$-6/ 10$\^$-4/M) me an adrenal vein for 20min produced relatively dose-dependent inhibition in CA secretion evoked by ACh (5.5 ${\times}$ 10$\^$-3/M), DMPP (10$\^$-4/M for 2min), McN-A-343 (10$\^$-4/M for 4min) and Bay-K-8644 (10$\^$-5/M for 4min), while did not affect the CA secretory effect of high K$\^$+/(5.6 x 10$\^$-2/M). Also, in the presence of 17${\beta}$-estradiol, CA secretion of ACh, DMPP and McN-A-343 without any effect on excess K$\^$+/-evoked CA secretion. However, in adrenal glands preloaded with 17${\alpha}$-estradiol (10$\^$-5/M) plus tamoxifen (10$\^$-5/M), which is known to be a selective antagonist of estrogen receptors (for 20min), CA secretory responses evoked by ACh, DMPP and McN-A-343 were considerably recovered as compared to that of 17${\alpha}$-estradiol only, but excess K$\^$+/-induced CA secretion was not affected.

• Journal of Ginseng Research
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• v.27 no.3
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• pp.129-134
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• 2003

When ginsenoside $R_{*}$b1/ and $R_{b2}$ were anaerobically incubated with human fecal microflora, these ginsenosides were metabolized to compound K (IH-901). When ginsenoside $R_{g3}$ was anaerobically incubated with human fecal microflora, the ginsenoside $R_{g3}$ was metabolized it to ginsenoside $R_{h2}$. Among ginsenosides, IH-901 and 20(S)-ginsenoside $R_{h2}$ exhibited the most potent cyotoxicity against tumor cells: 50% cytotoxic concentrations of IH-901 in the media with and without fetal bovine serum (FBS) were 27.1-31.6 $\mu$M and 0.1-0.61 $\mu$M, and those of 20(S)-ginsenoside $R_{h2}$ were 37.5->50 and 0.7-7.1 $\mu$M, respectively. The cytotoxic potency of ginsenosides was IH-901>20(S)-ginsenoside R $h_{h2}$》20(S)-ginsenoside $R_{g3}$>ginsenoside $R_{b1}$(equation omitted) $R_{b2}$.EX>$R_{b2}$./.