• Korean Journal of Materials Research
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• v.10 no.3
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• pp.212-217
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• 2000

Dielectric thin films for TFT(thin film transistor)s, such as silicon nitride$(Si_3N_4)$ and silicon oxide$(SiO_2)$, are usually deposited at $200~300^{\circ}C$. In this study, authors have tried to form dielectric films not by deposition but by oxidation with ECR(Electron Cyclotron Resonance) oxygen plasma, to improve the interface properties was not intensionally heated during oxidation. THe oxidation was performed consecutively without breaking vacuum after the deposition of a-Si: H films on the substrate to prevent the introduction of impurities. In this study, especially pulse mode of microwave power has been firstly tried during FCR oxygen plasma formation. Compared with the case of the continuous wave mode, the oxidation with the pulsed ECR results in higher quality silicon oxide$SiO_X$ films in terms of stoichiometry of bonding, dielectric constants and surface roughness. Especially the surface roughness of the pulsed ECR oxide films dramatically decreased to one-third of that of the continuous wave mode cases.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.2
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• pp.223-230
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• 2015

This study was conducted to investigate the effects of dietary coconut oil as a medium-chain fatty acid (MCFA) source on performance, carcass composition and serum lipids in male broilers. A total of 540, one-day-old, male Arbor Acres broilers were randomly allotted to 1 of 5 treatments with each treatment being applied to 6 replicates of 18 chicks. The basal diet (i.e., R0) was based on corn and soybean meal and was supplemented with 1.5% soybean oil during the starter phase (d 0 to 21) and 3.0% soybean oil during the grower phase (d 22 to 42). Four experimental diets were formulated by replacing 25%, 50%, 75%, or 100% of the soybean oil with coconut oil (i.e., R25, R50, R75, and R100). Soybean oil and coconut oil were used as sources of long-chain fatty acid and MCFA, respectively. The feeding trial showed that dietary coconut oil had no effect on weight gain, feed intake or feed conversion. On d 42, serum levels of total cholesterol, low-density lipoprotein cholesterol, and low-density lipoprotein/high-density lipoprotein cholesterol were linearly decreased as the coconut oil level increased (p<0.01). Lipoprotein lipase, hepatic lipase, and total lipase activities were linearly increased as the coconut oil level increased (p<0.01). Abdominal fat weight/eviscerated weight (p = 0.05), intermuscular fat width (p<0.01) and subcutaneous fat thickness (p<0.01) showed a significant quadratic relationship, with the lowest value at R75. These results indicated that replacement of 75% of the soybean oil in diets with coconut oil is the optimum level to reduce fat deposition and favorably affect lipid profiles without impairing performance in broilers.

• Journal of the Korean Vacuum Society
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• v.5 no.3
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• pp.239-244
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• 1996

We firstly report that formation of $SiO_2$ layer on Si surface can be effectively prevented by flowing the $Si_2H_6$ gas during the heating-up procedure for amorphous Si depositions. In this way, amorphously deposited Si layer onto crystalline Si substrates can be grown epitaxially during the post-deposition heat treatments. The suppression of surface $SiO_2$ can be explained in terms of adsorption of SiHx adspecies, instead of oxygen from residual gases in the reactors, to Si surfaces after desorption of hydrogen from H-passivated Si surfaces. Employing $Si_2H_6$ flowing and soild phase epitaxial growth, high-quality epitaxial Si layer can be obtained at low temperatures below $600^{\circ}C$ without conventional high temperature cleaning procedures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1713-1721
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• 1994

Intermetallic-matrix composites(IMCs) have the potential of combing matrix properties of oxidation resistance and high temperature stability with reinforcement properties of high specific strength and modulus. One of the major limiting factors for successful applications of these composite at high temperatures is the formation of interfacial reactions between matrix and ceramic reinforcement during composite process and during service. The purpose of the present investigation is to develop a better understanding of the nature of creep fracture mechanisms in a $Ni_{3}Al$ composite reinforced with both $TiB_{2}$ and SiC particulates. Emphasis is placed in the roles of the products of the reactions in determining the creep lifetime of the composite. In the present study, creep rupture specimens were tested under constant ranging from 180 to 350 MPa in vacuum at $760^{\cric}C$. The experimental data reveal that the stress exponent for power law creep for the composite is 3.5, a value close to that for unreinforced $Ni_{3}Al$. The microstructural observations reveal that most of the cavities lie on the grain boundaries of the $Ni_{3}Al$ matrix as opposed to the large $TiB_{2}/Ni_{3}Al$ interfaces, suggesting that cavities nucleate at fine carbides that lie in the $Ni_{3}Al$ grain boundaries as a result of the decomposition of the $SiC_{p}$. This observation accounts for the longer rupture times for the monolicthic $Ni_{3}Al$ as compared to those for the $Ni_{3}Al/SiC_{p}/TiB_{2} IMC$. Finally, it is suggested that creep deformation in matrix appears to dominate the rupture process for monolithic $Ni_{3}Al$, whereas growth and coalescence of cavities appears to dominate the rupture process for the composite.

• Economic and Environmental Geology
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• v.27 no.4
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• pp.335-343
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• 1994

The Eonyang amethyst deposits are composed of vug quartz emplaced in the Eonyang granites of Mesozoic Cretaceous age. The Eonyang granites are composed of biotite granite, porphyritic biotite granite, aplite and miarolitic granite. The petrochemical data of the Eonyang granites show the trend of subalkaline magma, calc-alkaline magma, I-type granitoid and magnetite series. The vug quartz show the characteristic growth zoning (white quartz-smoky quartz-amethyst) from wall side. Generally fluid inclusions in the vug quartz can be divided into four main types based on compositions (I-type: gas inclusion, II-type: liquid inclusion, III-type: polyphase inclusion, IV-type: liquid $CO_2$-bearing inclusion). Solid phase of polyphase inclusions are halite(NaCl), sylvite(KCl), hematite ($Fe_2O_3$) and unknown anisotropic solid. Homogenization temperatures inferred from the fluid inclusion study ranges from $440^{\circ}C$ to $485^{\circ}C$ in white quartz, from $227^{\circ}C$ to $384^{\circ}C$ in smoky quartz, from $133^{\circ}C$ to $186^{\circ}C$ in amethyst, respectively. Salinities of fluid inclusions in each mineralization stages ranges from 40 wt.% to 58 wt.% in white and smoky quartz, from 1.0 wt.% to 8.7 wt.% in amethyst respectively. A consideration of the pressure regime during vug quartz deposition based on the boiling evidence suggests lithostatic pressure of less than 72 bars. This range of pressure indicate that vug quartz lay at depth of 750 m below the surface at the during mineralization.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.852-857
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• 1996

Crystallization characteristics of titanium oxide thin film during post-annealing of reactive sputter deposition were studied. Amorphous phases of as-deposited films were crystallized into rutile after annealing at $900^{\circ}C$ and anatase at $500^{\circ}C$, respectively when $O_2$ concentration during sputtering was more than 15%. However, rutile was the only phase obtainable after annealing if %$O_2$ was less than 10%. For these films, Magneli phase($Ti_nO_{2n-1}$) were crystallized below $500^{\circ}C$ at first place due to slow oxidation of nonstoichiometric films but $500^{\circ}{\sim}600^{\circ}C$ anatase with nonstoichiometry was crystallized for a short period. It was, therefore, concluded that crystal growth can proceed without phase transition if stoichiometric phase is formed at the first stage of crystallization, and that rutile, the most stable phase, was resulted from any oxygen deficient nonstoichiometric films.

• Journal of the Korea Safety Management & Science
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• v.25 no.1
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• pp.7-14
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• 2023

We attempted to provide an overview of the laws and current state of the 3D printing industry in South Korea and around the world, using the annual industry surveys and the Wohler report. Additionally, we reviewed articles relating to the potential exposure to hazards associated with 3D printing using metal materials. In South Korea, there were 406 3D printing-related businesses, employing 2,365 workers, and the market size was estimated at 455.9 billion won in 2021. Globally, the average growth rate of the 3D printing industry market over the past 10 years was 27.4%, and the market size was estimated at $11.8 billion in 2019. The United States had the highest cumulative installation ratio of industrial 3D printers, followed by China, Japan, Germany, and South Korea. A total of 6,168 patents related to 3D printing were registered in the US between 2010 and 2019. Harmful factors during metal 3D printing was mainly evaluated in the powder bed fusion and direct energy deposition printing types, and there is a case of material extrusion type with metal additive filaments. The number, mass, size distribution, and chemical composition of particles were mainly evaluated. Particle concentration increases during the opening of the chamber or post-processing. However, operating the 3D printer in a ventilated chamber can reduce particle concentration to the background level. In order to have a safe and healthy environment for 3D printing, it is necessary to accumulate and apply knowledge through various studies.

• Korean Journal of Organic Agriculture
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• v.18 no.3
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• pp.347-361
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• 2010

This study was carried out to investigate the effects of wormwood (Artemisia sp.) addition on the growth performance, nutrients utilization and abdominal fat deposition of broiler chickens. Two hundred twenty five and two-day old Arboracre strain male commercial broiler chicks were distributed to 5 treatments with wormwood supplementation levels; C(O%), $T_1$ (1%), $T_2$ (3%), $T_3$ (5%), and $T_4$ (10%) and with 3 replications each with 5 birds for five weeks. Body weight gain during the experiment was improved in $T_1$ (1723.0g) compared with that of $T_3$ (1557.7g) and $T_4$ (1450.7g) (P<0.05). Feed intake was significantly (P<0.05) increased as the levels of wormwood addition increased (C: 2653.8g, T1: 2852.0, $T_2$: 2900.3, $T_3$: 2900.7g, T4: 2954.7g). Feed conversion rate (feed/gain) was significantly (P<0.05) increased as the levels of wormwood addition increased (C: 1.55, $T_1$: 1.66, $T_2$: 1.70, $T_3$: 1.86, $T_4$: 2.04). The days reaching to 2.0kg of body weight were expected to be 43.2 days in control, whereas those of group T1 were reduced to 42.6 days by 0.6 day from control. Nutrient utilization and abdominal fat deposition in the experiment were significantly decreased (P<0.05) and small intestine contents in the broilers was significantly increased (P<0.05) as the levels of wormwood addition increased. Therefore, although there was no significant improvement for the performance of broiler chickens with the dietary supplementation of wormwood meal, less than 1% addition of wormwood to broiler diets might have beneficial for human health by reducing the abdominal fat deposition of the broiler chicknens.

• Korean Journal of Materials Research
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• v.33 no.4
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• pp.142-150
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• 2023

AZO/Cu/AZO thin films were deposited on glass by RF magnetron sputtering. The specimens showed the preferred orientation of (0002) AZO and (111) Cu. The Cu crystal sizes increased from about 3.7 nm to about 8.5 nm with increasing Cu thickness, and from about 6.3 nm to about 9.5 nm with increasing heat treatment temperatures. The sizes of AZO crystals were almost independent of the Cu thickness, and increased slightly with heat treatment temperature. The residual stress of AZO after heat treatment also increased compressively from -4.6 GPa to -5.6 GPa with increasing heat treatment temperature. The increase in crystal size resulted from grain growth, and the increase in stress resulted from the decrease in defects that accompanied grain growth, and the thermal stress during cooling from heat treatment temperature to room temperature. From the PL spectra, the decrease in defects during heat treatment resulted in the increased intensity. The electrical resistivities of the 4 nm Cu film were 5.9×10^-4 Ω·cm and about 1.0×10^-4 Ω·cm for thicker Cu films. The resistivity decreased as the temperature of heat treatment increased. As the Cu thickness increased, an increase in carrier concentration resulted, as the fraction of AZO/Cu/AZO metal film increased. And the increase in carrier concentration with increasing heat treatment temperature might result from the diffusion of Cu ions into AZO. Transmittance decreased with increasing Cu thicknesses, and reached a maximum near the 500 nm wavelength after being heat treated at 200 ℃.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.699-704
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• 2018

One-dimensional nanostructures have attracted increasing attention because of their unique electronic, optical, optoelectrical, and electrochemical properties on account of their large surface-to-volume ratio and quantum confinement effect. Vertically grown nanowires have a large surface-to-volume ratio. The vapor-liquid-solid (VLS) process has attracted considerable attention for its self-alignment capability during the growth of nanostructures. In this study, vertically aligned silicon oxide nano-pillars were grown on Si\$SiO_2$(300 nm)\Pt substrates using two-zone thermal chemical vapor deposition system via the VLS process. The morphology and crystallographic properties of the grown silicon oxide nano-pillars were investigated by field emission scanning electron microscopy and transmission electron microscopy. The diameter and length of the grown silicon oxide nano-pillars were found to be dependent on the catalyst films. The body of the silicon oxide nano-pillars exhibited an amorphous phase, which is consisted with Si and O. The head of the silicon oxide nano-pillars was a crystalline phase, which is consisted with Si, O, Pt, and Ti. The vertical alignment of the silicon oxide nano-pillars was attributed to the preferred crystalline orientation of the catalyst Pt/Ti alloy. The vertically aligned silicon oxide nano-pillars are expected to be applied as a functional nano-material.