• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.341-345
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• 2009

Continuous dry anaerobic digestion of organic solid wastes (30% TS, Total Solids) comprised of food waste and paper was performed under mesophilic condition. During the operation, hydraulic retention time (HRT) was decreased as follows: 150 d, 100 d, 60 d, and 40 d, which corresponded to the solid loading rate of 2.0, 3.0, 5.0, and 7.5 kg TS/$m^3$/d, respectively. Volumetric biogas production rate ($m^3$/$m^3$/d) increased as HRT decreased, and the highest biogas production rate of 3.49${\pm}$0.31 $m^3$/$m^3$/d was achieved at 40 d of HRT. At this HRT, high volatile solids (VS) reduction of 76% was maintained, and methane production yield of 0.25 $m^3$/kg $TS_{added}$ was achieved, indicating 67.4% conversion of organic solid waste to bioenergy. The highest biogas production yield of 0.52 $m^3$/kg $TS_{added}$ was achieved at 100 d of HRT, but it did not change much with respect to HRT. For the ease feed pumping, some amount of digester sludge was recycled and mixed with fresh feed to decrease the solid content. Recirculation volume of 5Q was found to be the optimal in this experimental condition. Specific methanogenic activity (SMA) of microorganisms at mesophilic-dry condition was 2.66, 1.94, and 1.20 mL $CH_4$/g VS/d using acetate, butyrate, and propionate as a substrate, respectively.

• Herbal Formula Science
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• v.14 no.2
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• pp.21-32
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• 2006

The purpose of this study was to investigate the effect of Imyosan on apoptosis in human colorectal cancer HCT116 cells. Phellodendron amurense Rupr. and Atratylodes lancea D.C. compose Imyosan. First of all, to study the cytotoxic effect of methanol extract of Imyosan (IMS-MeOH) on HCT116 cells, the cells were treated with various concentrations of IMS-MeOH and then cell viability was determined by XTT reduction method. IMS-MeOH reduced viability of HCT116 cells in a dose and time-dependent manner. To confirm the induction of apoptosis, the c1eavage of poly ADP-ribose polymerase (PARP), a substrate for caspase-3 and a typical sign of apoptosis, and the activation of caspase-3, procaspase-8 and procaspase-9 were examined by western blot analysis. IMS-MeOH decreased procaspase-3, procaspase-8 and procaspase-9 levels in a dose-dependent manner and induced the clevage of PARP. IMS-MeOH triggered the mitochondrial apoptotic signaling by increasing the release of cytochrome c from mitochondria to cytosol. Furthermore, IMS-MeOH also downregulated the anti-apoptotic Bcl-2 and upregulated the pro-apoptotic-Bax. Therefore, these results suggest that IMS-MeOH induced HCT1l6 cell death through the mitochondrial pathway. To explore whether the activities of caspases was required for induction of apoptosis by IMS-MeOH, caspase-3, -8, -9 activity measured by using substrates, respectively. IMS-MeOH increased caspase-3, -8, -9 activity. Co-treatment with inhibitors of caspase-3, -8, -9 and IMS-MeOH significantly blocked IMS-MeOH-triggered apoptosis in HCT1l6 cells. These results suggest that IMS-MeOH induces caspases-mediated apoptosis.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.1 s.38
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• pp.23-29
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• 2006

Ultrasonic soldering of Si-wafer to FR-4 PCB at ambient temperature was investigated. The UBM of Si-substrate was Cu/ Ni/ Al from top to bottom with thickness of $0.4{\mu}m,\;0.4{\mu}m$, and $0.3{\mu}m$ respectively. The pad on FR-4 PCB comprised of Au/ Ni/ Cu from top to bottom with thickness of $0.05{\mu}m,\;5{\mu}m$, and $18{\mu}m$ respectively. Sn-3.5wt%Ag foil rolled to $100{\mu}m$ was used for solder. The ultrasonic soldering time was varied from 0.5 s to 3.0 s and the ultrasonic power was 1,400 W. The experimental results show that a reliable bond by ultrasonic soldering at ambient temperature was obtained. The shear strength increased with soldering time up to a maximum of 65 N at 2.5 s. The strength decreased to 34 N at 3.0 s because cracks were generated along the intermetallic compound between Si-wafer and Sn-3.5wt%Ag solder. The Intermetallic compound produced by ultrasonic soldering between the Si-wafer and the solder was $(Cu,Ni)_{6}Sn_{5}$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.12
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• pp.1008-1015
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• 2002

The fabricated La-modified lead titanate (PLT) thin film without poling treatment was investigated for modulation frequency dependence of pyroelectric properties by the dynamic method. $Pb_{l-x}La_{x}Ti_{l-x/4}O_3$(x=0.1) (PLT(10)) thin film haying 10 mol% La content was deposited on a Pt/$TiO_{x}$/$SiO_2$/Si substrate by sol-gel method. The PLT(10) thin film exhibits a relatively excellent dielectric property. The pyroelectric coefficient (p) of the PLT(10) thin film is 6.6 x $10^{-9}C$$textrm{cm}^2$$.$K without frequency dependence. The figure of merits for the voltage responsivity and specific detectivity are 1.03 x $10^{-11}C$.cm/J and 1.46 x $10^{-10}C$.cm/J, respectively The PLT(10) thin film has voltage responsivity (RV) of 5.IS V/W at 8 Hz. Noise equivalent power (NEP) and specific detectivity ($D^{*}$) of the PLT(10) thin film are 9.93 x $10^{-8}$W/$Hz^{1/2}$ and 1.81 x $10^{6}$cm.$Hz^{1/2}$/W at the same frequency of 100 Hz,, respectively The results means that PLT thin film having 10 mol% La content is suitable for the sensing materials of pyroelectric IR sensors.

• Research in Plant Disease
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• v.12 no.3
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• pp.189-196
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• 2006

Crown gall on lower stem of weeping fig(Ficus benjamina Roxb.) was first observed at Daejon in 2003. Tumors were about 15 cm in size and semi-round with rough surface texture of dark brown color. Two virulent isolates among ten bacteria isolated from the tumor tissues were characterized. Their colonies were convex, glistening, circular with an entire edge, and white or tannish cream in color on potato dextrose agar supplemented with 0.5% $CaCO_3$. They were rod shape with peritrichous flagellae, gram-negative, aerobic growth, oxidase-positive, and grew on D1M agar. The isolates were identified as Agrobacterium larrymoorei and A. tumefaciens based on biochemical and physiological characteristics, fatty acid profiles and substrate utilization patterns. Seedlings of some host plants excepting grapevine produced typical galls two to three weeks after inoculation with cell suspensions of the virulent strains. This is the first report on crown gall of weeping fig in Korea.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.83-83
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• 1995

The increase of population and industrial activities had brought into eutrophication in the Nakdong river. A remarkable acceleration of eutrophication brought about serious problems for water supply. Therefore, for the purpose of conservation of water quality in the Nakdong river it is necessary to control nutrients. MBOD method was use to evaluate algal growth limiting factor and algal growth potential in the Nakdong river from June to August 1994. The modified biochemical oxygen demand(MBOD) depends on the amount of available inorganic nutrient and organic substrate during 5 day incubation in the dark at 20$^{circ}C$. The MBOD assay depends on inorganic nutrients such as P and N as well as reduced carbon and called the MBOD, the MBOD-P, and the MBOD-N, respectively. The results of bioassay by MBOD(Modified BOD) method showed that the MBOD, MBOD-P and MBOD-N value were found to be in the ranges of 3.8∼96.0 mg$O_2$/l, 5.6∼94.0 mg$O_2$/l and 42.0∼220 mg$O_2$/l, respectively. And the the bioassay value was found to be the highest in Koryong area and the lowest in Waekwan area throughout the Nakdong river. The variations of MBOD-P and MBOD-N value showed similar tendencies to the variations of phosphorus and nitrogen value, respectively. By MBOD method, the relationships of MBOD, MBOD-P and MBOD-N value were MBOD ≒ MBOD-P 《 MBOD-N. The MBOD value was nearly equal to the MBOD-P value, and the MBOD-N value was 3 to 20 times more than the MBOD-P value, approximately. Therefore, in the Nakdong river, phosphorus was the limiting factor for algal growth during summer season. The algal growth potential as the concentration of chlorophyll-a in the summer was maximum 5 times more than standing crop as it.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.211-212
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• 2010

GaN 기반의 상부발광형 LED는 동작되는 동안 생기는 전기적 단락, 그리고 칩 위의 p-형 전극과 n-형 전극 사이에 생기는 누설전류 및 신뢰성 확보를 위하여 칩 표면에 passivation 층을 형성하게 된다. SiO2, Si3N4와 같은 passivation layers는 일반적으로 PECVD (Plasma Enhanced Chemical Vapor Deposition)공정을 이용한다, 하지만 이는 공정 특성상 plasma로 인한 damage가 유발되기 때문에 표면 누설 전류가 증가 한다. 이로 인해 forward voltage와 reverse leakage current의 특성이 저하된다. 본 실험에서는 원자층 단위의 박막 증착으로 인해 PECVD보다 단차 피복성이 매우 우수한 PEALD(Plasma Enhanced Atomic Layer Deposition)공정을 이용하여 Al2O3 passivation layer를 증착한 후, 표면 누설전류와 빛의 출력 특성에 대해서 조사해 보았다. PSS (patterned sapphire substrate) 위에 성장된 LED 에피구조를 사용하였고, TCP(Trancformer Copled Plasma)장비를 사용하여 에칭 공정을 진행하였다. 이때 투명전극을 증착하기 위해 e-beam evaporator를 사용하여 Ni/Au를 각각 $50\;{\AA}$씩 증착한 후 오믹 특성을 향상시키기 위하여 $500^{\circ}C$에서 열처리를 해주었다. 그리고 Ti/Au($300/4000{\AA}$) 메탈을 사용하여 p-전극과 n-전극을 형성하였다. Passivation을 하지 않은 경우에는 reverse leakage current가 -5V 에서 $-1.9{\times}10-8$ A 로 측정되었고, SiO2와 Si3N4을 passivation으로 이용한 경우에는 각각 $8.7{\times}10-9$과 $-2.2{\times}10-9$로 측정되었다. Fig. 1 에서 보면 알 수 있듯이 5 nm의 Al2O3 film을 passivation layer로 이용할 경우 passivation을 하지 않은 경우를 제외한 다른 passivation 경우보다 reverse leakage current가 약 2 order ($-3.46{\times}10-11$ A) 정도 낮게 측정되었다. 그 이유는 CVD 공정보다 짧은 ALD의 공정시간과 더 낮은 RF Power로 인해 plasma damage를 덜 입게 되어 나타난 것으로 생각된다. Fig. 2 에서는 Al2O3로 passivation을 한 소자의 forward voltage가 SiO2와 Si3N4로 passivation을 한 소자보다 각각 0.07 V와 0.25 V씩 낮아지는 것을 확인할 수 있었다. 또한 Fig. 3 에서는 Al2O3로 passivation을 한 소자의 output power가 SiO2와 Si3N4로 passivation을 한 소자보다 각각 2.7%와 24.6%씩 증가한 것을 볼 수 있다. Output power가 증가된 원인으로는 향상된 forward voltage 및 reverse에서의 leakage 특성과 공기보다 높은 Al2O3의 굴절률이 광출력 효율을 증가시켰기 때문인 것으로 판단된다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.249-258
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• 2006

In this letter, we propose a novel printed helix antenna for RFID reader in UHF band. The printed strip line of the antenna is first wound up outside a polygonal shaped layer and then the winding continues on an inner layer to control the overall gain and the radiation pattern. In addition, the winding pitch angles on each layer have either negative or positive values resulting in the broad CP bandwidth. The detail structure of the antenna was optimized using Pareto genetic algorithm(GA), so as to obtain excellent performances for RFID reader antennas. The optimized two-layered polygonal helix was fabricated on the cardboard of a flexible substrate and the performances were measured and compared with the simulations. The fabricated antenna was made up of copper tape which can adhere to a flexible cardboard and had 21.4 % matching bandwidth, 31.9 % CP bandwidth, readable range of $5.5m^2$ with kr=3.2. Also based on the current distribution of the strip line of the antenna and sensitivity of the antenna bents points, we confirmed that the antenna has the quarter-wave transformer near the feed for the broad matching bandwidth and radiates the traveling wave for the broad CP bandwidth using the bent strip line.

• Korean Journal of Materials Research
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• v.13 no.8
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• pp.497-502
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• 2003

Crystallographic characteristics and interfacial structures of $Al_2$$O_3$and $ZrO_2$dielectric films prepared by atomic layer chemical vapor deposition (ALCVD) were investigated at atomic scale by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS)/electron energy-loss spectroscopy (EELS) coupled with a field-emission transmission electron microscope. The results obtained from cross-sectional and plan-view specimens showed that the $Al_2$$O_3$film was crystallized by annealing at a high temperature and its crystal system might be evaluated as either cubic or tetragonal phase. Whereas the $ZrO_2$film crystallized during deposition at a low temperature of ∼$300^{\circ}C$ was composed of both tetragonal and monoclinic phase. The interfacial thickness in both films was increased with the increased annealing temperature. Further, the interfacial structures of X$ZrO_2$$O_3$and $ZrO_2$films were discussed through analyses of EDS elemental maps and EELS spectra obtained from the annealed films, respectively.

• Journal of Mushroom
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• v.9 no.4
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• pp.145-154
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• 2011

Shiitake mushroom (Lentinula edodes) is usually cultivated on the oak log. Log cultivation of this mushroom is getting difficult to get oak logs and has a weak point of its long cultivation period. Recently sawdust cultivation is getting increase. It is important to make mycelia browning on the substrate surface. This browned surface in sawdust cultivation plays an important role like as artificial bark of the oak log, which protects the other pests and suppresses water evaporation in the substrate. The period for mycelia browning is so long that the sawdust cultivation of Shiitake mushroom can not spread well into the mushroom farms. The development of methods for the rapid mycelia browning is quite required. In this article we would like to find cultural characteristics of collected strains and to see the correlation with mycelial browning. Mycelial growth in the media was different according to kinds of media and strains. The optimal temperature on mycelial growth was $20-25^{\circ}C$. Browning patterns of mycelium under 200 Lux seemed to be used for a key to differentiate the strains for sawdust cultivation. Browning period was 30-40 days in the agar media and 70-100 days in the sawdust bag cultivation. When we considered the productivity and the other characteristics, ASI 3046 is the best for the bag cultivation. Significance between mycelial growth and browning was not accepted, but that of mycelial growth between on PDA and sawdust was accepted. Browning period on the PDA and sawdust showed a strong relationships. These results suggested that the browning habits could not be depend on the difference of media, but on their own properties. To select the strain showed fast browning can be done by using agar media for saving time.