• Journal of fish pathology
• /
• v.25 no.2
• /
• pp.123-126
• /
• 2012

Exfoliation of fouling abalone, Haliotis discus hannai from shelters by commercial oxytetracycline (OTC) was observed in culture farms. In the present study, different components of OTC for exfoliation of abalone were investigated to understand how to work. Abalone were detached from shelter in 14,000 ppm of commercial OTC (main ingredients of OTC: OTC-hydrogen chloride (HCl), 50%; glucose, 49%; blue pigment, <1%), but not below 8,000 ppm. A 95% of exfoliation rate was observed in OTC-HCl (7,000 ppm, pH 2.8) but no exfoliation in OTC-HCl (7,000 ppm, pH 5.0), glucose (7,000 ppm) or blue pigment (140 ppm). Moreover 100% exfoliation rate was observed in HCl-seawater of pH 2.8. These results indicate that HCl is the component resulting in exfoliation of the fouling abalone. Abalone was detached in HCl solution (pH 2.5-3.2) within 2 min. However, a lower pH and longer treatment resulted in delayed recovery of the detached abalone. Thus, exfoliation of fouling abalone can be achieved by a low pH treatment with cautious handling.

• Korean Chemical Engineering Research
• /
• v.52 no.5
• /
• pp.688-693
• /
• 2014

For investigating NO reduction activity of an catalytic filter, the catalytic performance was measured under the presence of $SO_2$ and $H_2O$, respectively or simultaneously in the simulation gas composed of NO, $NH_3$, and air. The catalytic filter was prepared by coating $V_2O_5-WO_3/TiO_2$ catalyst on the pore surface of SiC filter element of which the superior performance for the particulate removal was well known. At the temperature below $260^{\circ}C$, the catalytic activities were enormously decreased under the presence of $SO_2$ and $H_2O$, respectively or simultaneously, compared with those under the cases of the absence of $SO_2$ and $H_2O$. However, the presence of $SO_2$ promoted the performance of the catalytic filter above $320^{\circ}C$ with showing the NO conversion better than 99.8% for the NO inlet concentration of 500 ppm and at the face velocity of 2 cm/s. In particular, the presence of water showed high NO conversion higher than 99% up to high temperature of $380^{\circ}C$. This effect of water was explained by the reason that it retarded the ammonia oxidation which is the main step into the formation of $N_2O$. The initial NO reduction activity of the catalytic filter maintained for the duration of 100 hours in the presence of $SO_2$ and $H_2O$. Therefore, it was concluded that the catalytic filter was promisingly useful for the industrial NOx reduction catalyst in order to treat the particulate and NO simultaneously.

• Journal of the Korean Magnetics Society
• /
• v.10 no.5
• /
• pp.196-202
• /
• 2000

Top synthetic spin valves with structure Ta/NiFe/CoFe/Cu/CoFe(P1)/Ru/CoFe(P2)/FeMn/Ta on Si(100) substrate with natural oxide were prepared by dc magnetron sputtering system, and investigated on the magnetoresistance properties and effective exchange bias field. As the thickness of FeMn increased above 150 $\AA$, MR ratio was decreased due to the current shunting effect. As the thickness of free layer decreased below 40$\AA$, MR ratio was reduced rapidly. In case of 40 $\AA$ thick of free layer, spin valve film with a structure Si(100)/Ta(50 $\AA$)/NiFe(27 $\AA$)/CoFe(13 $\AA$)/Cu(26 $\AA$)/CoFe(30 $\AA$)/Ru(7 $\AA$)/CoFe(15 $\AA$)/FeMn(100 $\AA$)/Ta(50 $\AA$) exhibited maximum MR ratio of 7.5 % and an effective exchange bias field of 600 Oe, respectively. Thickness difference dependence in this synthetic spin valve structure on effective exchange field was investigated and interpreted by the analytical method. It should be noted that thickness increase of CoFe(P 1) and decrease of CoFe(P2) in synthetic antiferromagnet leaded to the decrease in effective exchange bias field by experimentally and analytically.

• Computers and Concrete
• /
• v.9 no.6
• /
• pp.427-437
• /
• 2012

This article presents the effect of replacement fly ash (FA) with diatomite (DE) on the properties of geopolymer mortars. DE was used to partially replace FA at the levels of 0, 60, 80 and 100% by weight of binder. Sodium silicate ($Na_2SiO_3$) and sodium hydroxide (NaOH) solutions were used as the liquid portion in the mixture in order to activate the geopolymerization. The NaOH concentrations of 15M, $Na_2SiO_3$/NaOH ratios of 1.5 by weight, and the alkaline liquid/binder (LB) ratios by weight of 0.40, 0.50, 0.60 and 0.70 were used. The curing at temperature of $75^{\circ}C$ for 24 h was used to accelerate the geopolymerization. The flows of all fresh geopolymer mortars were tested. The compressive strengths and the stress-strain characteristics of the mortar at the age of 7 days, and the unit weights were also tested. The results revealed that the use of DE to replace part of FA as source material in making geopolymer mortars resulted in the increased in the workability, and strain capacity of mortar specimens and in the reductions in the unit weights and compressive strengths. The strain capacity of the mortar increased from 0.0028 to 0.0150 with the increase in the DE replacement levels from 0 to 100%. The mixes with 15M NaOH, $Na_2SiO_3$/NaOH of 1.5, LB ratio of 0.50, and using $75^{\circ}C$ curing temperature showed 7 days compressive strengths 22.0-81.0 MPa which are in the range of normal to high strength mortars.

• Journal of the Microelectronics and Packaging Society
• /
• v.21 no.2
• /
• pp.65-70
• /
• 2014

Warpage of top packages to form thin package-on-packages was measured with progress of their process steps such as PCB substrate itself, chip bonding, and epoxy molding. The $100{\mu}m$-thick PCB substrate exhibited a warpage of $136{\sim}214{\mu}m$. The specimen formed by mounting a $40{\mu}m$-thick Si chip to such a PCB using a die attach film exhibited the warpage of $89{\sim}194{\mu}m$, which was similar to that of the PCB itself. On the other hand, the specimen fabricated by flip chip bonding of a $40{\mu}m$-thick chip to such a PCB possessed the warpage of $-199{\sim}691{\mu}m$, which was significantly different from the warpage of the PCB. After epoxy molding, the specimens processed by die attach bonding and flip chip bonding exhibited warpages of $-79{\sim}202{\mu}m$ and $-117{\sim}159{\mu}m$, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.340.2-340.2
• /
• 2014

최근 비정질 산화물 반도체는 가시광 영역에서의 투명도와 낮은 공정 온도, 그리고 높은 Field-effect mobility로 인해 Thin film transistors의 Active channel layer의 재료로 각광 받고 있다. ZnO, IZO, IGO, ITGO등의 많은 산화물 반도체들이 TFT의 채널층으로의 적용을 위해 활발히 연구되고 있으며, 특히 비정질 IGZO는 비정질임에도 불구하고 Mobility가 $10cm^2/Vs$ 정도로 기존의 a-Si:H 보다 높은 Mobility 특성을 나타내고 있어 대화면 디스플레이와 고속 구동을 위한 LCD에 적용 할 수 있으며 또한 낮은 공정 온도로 인해 플렉서블 디스플레이에 응용될 수 있다는 장점이 있다. 우리는 RF magnetron sputtering법으로 증착한 비정질 IGZO TFT(Thin Film Transistors)의 전기적 특성과 IGZO 박막의 특성에 미치는 RF power의 영향을 연구하였다. 제작한 TFTs의 Active channel layer는 산소분압 1%, Room temperature에서 RF power별(50~150 W)로 Si wafer 기판 위에 30nm로 증착 하였고 100 nm의 $SiO_2$가 절연체로 사용되었다. 또한 박막 특성을 분석하기 위해 같은 Chamber 분위기에서 100 nm로 IGZO 박막을 증착하였다. 비정질 IGZO 박막의 X-ray reflectivity(XRR)을 분석한 결과 RF Power가 50 W에서 150 W로 증가 할수록 박막의 Roughness는 22.7 (${\AA}$)에서 6.5 (${\AA}$)로 감소하고 Density는 5.9 ($g/cm^3$)에서 6.1 ($g/cm^3$)까지 증가하는 경향을 보였다. 또한 제작한 IGZO TFTs는 증착 RF Power가 증가함에 따라 Threshold voltage (VTH)가 0.3~4(V)로 증가하는 경향을 나타내고 Filed-effect mobility도 6.2~19 ($cm^2/Vs$)까지 증가하는 경향을 보인다. 또한 on/off ratio는 모두 > $10^6$의 값을 나타내며 subthreshold slope (SS)는 0.3~0.8 (V/decade)의 값을 나타낸다.

• Journal of Korean Ophthalmic Optics Society
• /
• v.1 no.2
• /
• pp.49-55
• /
• 1996

Hydrogenated amorphous carbon(a-C:H) films were fabricated by the low-frequency (60Hz) glow discharge of the mixture of methane and hydrogen, and their electrical properties were investigated. We observed that a-C:H films show the persistent photoconductivity(PPC) by illumination of heat-filtered while light for a few seconds. The PPC was about 10 times larger than the annealed dark conductivity. The samples clearly showed metastable characteristics. With increasing illumination times from 1 to 100 min, the annealing activation energy of the PPC was about 0.39eV. The annealing temperature at which the PPC disappeared increasing from $100^{\circ}C$ to $130^{\circ}C$. Illumination longer than 80 min leads to the formation of ${\pi}$ defects and to the decrease of PPC. From these results, we tentatively propose that the states in the ${\pi}$ band act as deep trap centers generating the metastabilities.

• Journal of the Korean Ceramic Society
• /
• v.30 no.1
• /
• pp.17-24
• /
• 1993

Sol-gel spin-coating technique was used to produce Nb2O5 thin films on silicon substrates from Nb(OC2H5)5 precursor. The films were heat-treated at temperatures between $600^{\circ}C$ and 100$0^{\circ}C$ in oxygen atmosphere and their crystalline phases, chemical states, and dielectric characteristics were investigated by X-ray diffractometry (XRD), Auger electron spectroscopy (AES), and C-V measurements, respectively. After 1 hour heat-treatment at 80$0^{\circ}C$, T-type Nb2O5 was formed, and its chemical composition was homogeneous with no appreciable SiO2 oxide at interfaces between the films and substrates. The films heat-treated at temperatures between $600^{\circ}C$ and 80$0^{\circ}C$ exhibit dielectric constant of less than 20 while the films heat treated at 100$0^{\circ}C$ show dielectric constant of 28.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.9
• /
• pp.1602-1608
• /
• 2007

The composites were fabricated, respectively, using 61[vol.%] SiC-39[vol.%] $TiB_2$ and using 61[vol.%] SiC-39[vol.%] $ZrB_2$ powders with the liquid forming additives of 12[wt%] $Al_2O_3+Y_2O_3$ by hot pressing annealing at $1650[^{\circ}C]$ for 4 hours. Reactions between SiC and transition metal $TiB_2$, $ZrB_2$ were not observed in this microstructure. The result of phase analysis of composites by XRD revealed SiC(6H, 3C), $TiB_2$, $ZrB_2$ and $YAG(Al_5Y_3O_{12})$ crystal phase on the Liquid-Phase-Sintered(LPS) $SiC-TiB_2$, and $SiC-ZrB_2$ composite. $\beta\rightarrow\alpha-SiC$ phase transformation was occurred on the $SiC-TiB_2$ and $SiC-ZrB_2$ composite. The relative density, the flexural strength and Young's modulus showed the highest value of 98.57[%], 249.42[MPa] and 91.64[GPa] in $SiC-ZrB_2$ composite at room temperature respectively. The electrical resistivity showed the lowest value of $7.96{\times}10^{-4}[\Omega{\cdot}cm]$ for $SiC-ZrB_2$ composite at $25[^{\circ}C]$. The electrical resistivity of the $SiC-TiB_2$ and $SiC-ZrB_2$ composite was all positive temperature coefficient resistance (PTCR) in the temperature ranges from $25[^{\circ}C]$ to $700[^{\circ}C]$. The resistance temperature coefficient of composite showed the lowest value of $1.319\times10^{-3}/[^{\circ}C]$ for $SiC-ZrB_2$ composite in the temperature ranges from $100[^{\circ}C]$ to $300[^{\circ}C]$ Compositional design and optimization of processing parameters are key factors for controlling and improving the properties of SiC-based electroconductive ceramic composites.

• Korean Journal of Materials Research
• /
• v.11 no.12
• /
• pp.1014-1019
• /
• 2001

The diamond thin film was deposited on Si(100) substrate from$CH_3OH/H_2O$mixtured gas using a hot filament chemical vapor deposition(HFCVD) method. The deposition condition for samples has been varried with the$CH_3OH/H_2O$composition. Scanning electron microscopy(SEM) and Raman spectroscopy has been employed for the sample analysis. The diamond sample has been obtained below 20Pa with$CH_3OH/H_2O$mixtured gas. The crystallinity of diamond film improved as the composition $CH_3OH$decreases from 60Vol% to 52Vol%, and the sample structure changed from the cauliflower to the diamond structure. But the sample structure was becomes cauliflower at 50Vol% of in$CH_3OH$ in the $CH_3OH/H_2O$. It was shown that the$CH_3OH$ has threshold composition.