• E2M - 전기 전자와 첨단 소재
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• 제9권2호
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• pp.188-195
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• 1996

The AlSi etching process using the MERIE type reactor carried out with different process parameters such as C1$_{2}$ and N$_{2}$ gas flow rate, RF power and chamber pressure. The etching characteristics were evaluated in terms of etch rate, selectivity, uniformity and etched profile. As the N2 gas flow rate is increased, the AlSi etch rate is decreased and uniformity has remained constant within .+-.5%. The etch rate is increased and uniformity is decreased, according to increment of the C1$_{2}$ gas flow rate, RF power and chamber pressure. Selective etching of TEOS with respect to AlSi is decreased as the RF power is increased while it is increased by increment of the C1$_{2}$ gas flow rate and chamber pressure, on the other hand, selective etching of photoresist with respect to AlSi is increased by increment of the C1$_{2}$ gas flow rate and chamber pressure, it is decreased as the N$_{2}$ gas flow rate is increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.501-506
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• 2001

The creep crack growth properties in 3.5NiCrMoV steel were investigated at $550^{\circ}C$ by using CT specimen under constant $C_t$ condition that was held during crack growth of 1mm distance. $C_t$ lely on load line displacement rate and $C^*$ usually increase with crack length though load is reduced in order to maintain constant $C_t$ value as crack growth. Fully coalesced area(FCA) ahead of crack tip tend to increase as $C_t$ increase to the critical value, and after that value FCA decrease. For the tertiary creep stage of crack growth test, the most of displacement is due to the steady state creep, except only small part due to the primary creep and other effects. Therefore, tests were mainly interrupted in the tertiary stage to obtain high value of $C_t$. At constant load and $C_t$ region, crack growth slope was 0.900 and 0.844 each, on the other hand $C^*$ slope was 0.480.

• Transactions on Electrical and Electronic Materials
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• 제11권2호
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• pp.61-64
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• 2010

In this paper, we investigate the quality difference of SiC crystals grown by a conventional physical vapor transport method using various SiC powders. While the growth rate was revealed to be dependent upon the particle size of the SiC powder, the growth rate of SiC bulk crystals grown using SiC powder with a smaller particle size (20 nm) was definitely higher than those using lager particle sizes with $0.1-0.2\;{\mu}m$ and $1-10\;{\mu}m$, respectively. All grown 2 inch SiC single crystals were proven to be the polytype of 6H-SiC and the carrier concentration levels of about $10^{17}\;cm^3$ were determined from Hall measurements. It was revealed that the particle size and process method of SiC powder played an important role in obtaining a good quality, high growth rate, and to reduce growth temperature.

• 한국축산시설환경학회지
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• 제1권1호
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• pp.65-75
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• 1995

This experiment was carried out to the effects of population density and C/N ratios of feed on the growth, reproductive effciency and cast producation of the earthworm(Eisenia foetida). The population densities of 50, 100, 150, 200 and 250 individuals of the earthworm fed with different C/N ratios of 25, 35, 45 and 55 cow manures were studied in rearing box($6,400cm^3$), and at the fertility stage during a period of 60 days. The results were summarized as follows; The survial rate(SR), increasing rate(IR), reproductive efficiency(RE) and cast production of the earthworms showed highest values in C/N ratio of 25. These results may indicate that C/N ratio of 25 is a very favourable feed for the growth of the earthworms. The survial rate(SR) indicated significant positive correlation with reproductive efficiency(RE) in different C/N ratios of feeds. The survial rate(SR) showed highest values in population densities of $50{\sim}100$ worms/$6,400cm^3(64.0{\sim}128.0cm^3/worm$). On the contrary, increasing rate(IR) tended to decreased with the increased population densities. The survival rate(SR) indicated significant negative correlation with reproductive efficiency(RE) in different population densities of the earthworms. The cast production estimated were $31.6mg{\sim}67.4mg/day/worm$ grown in optimum population densities($50{\sim}100\;worms/6,400cm^3$). The earthworm casting are an excellent soil conditioning material or organic fertilizer sources with a high chemical composition and their physical properties.

• Journal of the Korean Wood Science and Technology
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• 제25권4호
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• pp.99-107
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• 1997

This study was executed to test the possibility of replacement for domestic Japanese larch(Larix leptolepis) for hardwoods and to acquire the information about the effects of drying temperature on internal temperature, moisture content and drying defects. In high-temperature drying, internal temperature increased rapidly to boiling point, immediately after that point the internal temperature rising rate was reduced. In the case of drying at temperature of $125^{\circ}C$, internal temperature could reach at boiling point in a very short time. Moisture content in high-temperature drying showed constant drying rate period and first period of falling rate drying together in 4 hours since experiment begun. There was no strong correlation between initial moisture content and final moisture content. Average drying rate at $115^{\circ}C$, $120^{\circ}C$ and $125^{\circ}C$ was 1.42%/hr, 1.88%/hr and 2.02%/hr, respectively; the case of drying temperature of $125^{\circ}C$ showed most rapid drying rate. Drying rate of $125^{\circ}C$ was so rapid that it showed more severe shrinkage, bow, collapse, end check, and internal check development than in other drying conditions. The result of this study showed the strong possibility of high-temperature drying for Japanese larch, and to dry Japanese larch optimally, dry bulb temperature should not exceed $120^{\circ}C$.

• 대한기계학회논문집
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• 제6권4호
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• pp.377-383
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• 1982

Acoustic emission (AE) of a high strength steel (SCM-4) was measured under stress corrosion cracking(SCC) test at a constant displacement in 3.5% artificial NaCl solution of 18.deg.C, 45.deg.C and 60.deg.C, respectively. The results are as follows; During the SCC test, AE is detected and AE count rate is approximately proportional to the crack growth rate. Even though crack is not propagated macroscopically, AE is detected. The crack growth rate of SCC and the AE count rate are higher for the solution of higher temperature, 45.deg.C and 60.deg.C, than for the solution of lower temperature, 18.deg.C. In the early stage of SCC, AE total counts mostly depend on crack growth. In the later stage, however, AE mostly depends on the film fracture and the dissolution of anode.

• 한국전기전자재료학회논문지
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• 제14권2호
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• pp.117-122
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• 2001

In this paper, we report on photoelectrochemical etching process of 6H-SiC semiconductor wafer. The etching was performed in two-step process; anodization of SiC surface to form a deep porous layer and thermal oxidation followed by an HF dip. Etch rate of about 615${\AA}$/min was obtained during the anodization using a dilute HF(1.4wt% in H$_2$O) electrolyte with the etching potential of 3.0V. The etching rate was increased with the bias voltage. It was also found out that the adition of appropriate portion of H$_2$O$_2$ into the HF solution improves the etching rate. The etching process resulted in a higherly anisotropic etching characteristics and showed to have a potential for the fabrication of SiC devices with a novel design.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.92-95
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• 2008

We performed the theoretical calculation of CN Violet radiation using the code SPRADIAN07 to predict the Lee et al.'s experimental measurements and to reinvestigate $C_2$ dissociation rate. CN Violet radiations are calculated under the Boltzmann and non-Boltzmann distribution using two chemical reaction sets: Park-Losev-G\"{o}kcen-Tsang and Park-Losev-G\"{o}kcen-Tsang-Lee models. Our SPRADIAN07 calculations show improvement in prediction of absolute radiation intensity of CN Violet and its decay rate by Park-Losev-G\"{o}kcen-Tsang reaction set with $C_2$ dissociation rate coefficient of $k_f$ = 1.5${\times}$10$^{16}$ exp(-71,600/$T_x$) cm$^3$ mole$^{-1}$ s$^{-1}$.

• 한국패류학회지
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• 제30권2호
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• pp.101-106
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• 2014

인공종묘로 생산된 동죽, Mactra veneriformis의 크기, 수온, 염분 변화에 대한 여수율과 먹이섭이량의 차이를 조사하였다. 수온의 경우 소형, 대형그룹의 여수율은 $5^{\circ}C$에서 최소값을 보였으며 $20^{\circ}C$에서 가장 높은 값을 보였으나, $25^{\circ}C$에서 급격한 감소 경향을 보였다. 염분에 대한 소형그룹의 여수율은 26‰에서 가장 높은 값을 보였고 8‰에서 가장 낮은 값을 보였다. 대형그룹은 32‰에서 가장 높은 값을 보였고, 8‰에서 가장 낮은 값을 보였다. 본 연구를 통해 동죽의 최적 수온, 염분 환경은 $20^{\circ}C$, 27-32‰이며, $10^{\circ}C$ 이하 또는 $25^{\circ}C$ 이상의 수온과 20‰ 이하의 저염분에서 여수율이 낮아진다는 사실을 확인할 수 있었다.

• 한국양식학회지
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• 제19권1호
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• pp.52-56
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• 2006

This study was conducted to investigate the effects of three different concentrations (6%, 8% and 10% final volume) of dimethyl sulfoxide (DMSO) on cryopreserved sperm of grass carp (Ctenopharyngodon idellus). Grass carp sperm was suspended in Kurokura extender #2 and equilibrated at $4^{\circ}C$ for 10 min. French straws (0.25 ml) of sperm were frozen from $4^{\circ}C\;to\;-4^{\circ}C$ at a rate of $4^{\circ}C\;min^{-1}$ and then ken $-4^{\circ}C\;to\;-80^{\circ}C$ at a rate of $11^{\circ}C\;min^{-1}$. The straws were kept at $-80^{\circ}C$ for 10 min and finally stored in liquid nitrogen $(-196^{\circ}C)$. The cryopreserved sperm was thawed in a water bath at $40^{\circ}C$ for 30 sec and fertilization, hatching rate and larval malformation were compared with fresh sperm (control). The fertilization rate of post-thawed sperm was comparable (from 88.21% to 94.30%) to that of fresh sperm. However, hatching rate of all frozen sperm were significantly lower (P<0.05) than that of control. Additionally, the larval abnormality rate of frozen sperm was significantly higher than that of fresh sperm. The results indicate that DMSO could affect the quality of cryopreserved sperm of grass carp, and a freezing program and a proper extender composition should be further studied.