• Journal of the Korean institute of surface engineering
• /
• v.54 no.4
• /
• pp.200-208
• /
• 2021

This paper investigated generation behavior of micro-arcs and growth behavior of PEO films on the AA7050 disc specimen in 0.1 M NaAlO₂ solution under the application of 1200 Hz anodic pulse current. Morphologies, thickness and surface roughness of PEO films were examined at the edge part and central part separately. Micro-arcs were generated first at the edge part and then moved towards the central part with PEO treatment time, indicating lateral growth of PEO films. The lateral growth resulted in uniform PEO thickness of about 5 ㎛ and surface roughness of about 0.5 ㎛. Moving of the arcs from the edge towards the central part appeared only one time and large size arcs were generated at the edge before completing the central part with small size micro-arcs. This suggests that vertical growth starts before completing the lateral growth. Large size arcs generated at the edge resulted in the formation of relatively large size pores within the PEO films on the AA7050 disc specimen.

• Journal of the Korean Vacuum Society
• /
• v.4 no.S2
• /
• pp.131-138
• /
• 1995

The broad beam ion sources of hot filament plasma type have widely used for modifications of materials and thin films, and the new type intensive current broad beam metal ion source including reactive gaseous ion beams is needed for preparing the hard coating films such as DLC, $\beta-C_3N_4$ Carbides, Nitrides, Borides etc. Now a electorn beam evaporation(EBE) broad beam metal ion source has been developed for this purpose in our lab. CN film has been formed by the EBE ion source. Study of the CN film shows that it has high hardness(HK=5800kgf/$\textrm {mm}^2$)and good adhesion. This method can widely changes the ratio of C/N atom's concentrations from 0.14 to 0.6 and has high coating rate. The low energy pocket ion source which was specially designed for surface texturing of medical silicon rubber was also developed. It has high efficiency and large uniform working zone. Both nature texturing and mesh masked texturing of silicon rubbers were performed. The biocompatibility was tested by culture of monocytes, and the results showed improved biocompatibility for the treated silicon rubbers. In addition, the TiB2 film synthesized by IBED is being studied recently in our lab. In this paper, the results which include the hardness, thickness of the films and the AES, XRD analysis as well as the tests of the oxidation of high temperature and erosion will be presented.

• Korean Journal of Plant Resources
• /
• v.36 no.3
• /
• pp.198-206
• /
• 2023

The effectiveness of the extracts of Alnus japonica and Portulaca oleracea, which are effective in improving alcohol-induced liver damage, was confirmed using acute and chronic alcoholic liver injury animal models. In the acute alcoholic liver injury model, dieting Alnus japonica and Portulaca oleracea complex (ALPOC) at a dose of 50 mg/kg showed no significant change in liver or body weight, while measured plasma ALT activity to be deficient (28.12 U/ml) compared to the alcohol intake group (42.5 U/ml), and confirmed that restored it to an average level. It showed an improvement of 34.9% compared to the alcohol intake group. AST activity confirmed that it showed a very effective liver protection activity by showing a gain of 12.6%. The chronic alcoholic liver damage animal model demonstrated that ALT showed an improvement effect of 25%, and AST showed an effect similar to that of the positive control group, Hovenia extract. In addition, through H&E staining analysis, observed that the ALPOC improved the necrosis and bleeding of the liver. And the ALPOC group showed intense antioxidant activity of 127% or more compared to the alcohol intake group, and this was confirmed to have a very high activity, which is more than 20% higher than that of the hovenia fruit extract.

• Journal of the Semiconductor & Display Technology
• /
• v.6 no.3
• /
• pp.19-23
• /
• 2007

The NiSi is very promising candidate for the metallization in 45 nm CMOS process such as FUSI(fully silicided) gate and source/drain contact because it exhibits non-size dependent resistance, low silicon consumption and mid-gap workfunction. Ni film was first deposited by using ALD (atomic layer deposition) technique with Bis-Ni precursor and $H_2$ reactant gas at $220^{\circ}C$ with deposition rate of $1.25\;{\AA}/cycle$. The as-deposited Ni film exhibited a sheet resistance of $5\;{\Omega}/{\square}$. RTP (repaid thermal process) was then performed by varying temperature from $400^{\circ}C$ to $900^{\circ}C$ in $N_2$ ambient for the formation of NiSi. The process temperature window for the formation of low-resistance NiSi was estimated from $600^{\circ}C$ to $800^{\circ}C$ and from $700^{\circ}C$ to $800^{\circ}C$ with and without Ti capping layer. The respective sheet resistance of the films was changed to $2.5\;{\Omega}/{\square}$ and $3\;{\Omega}/{\square}$ after silicidation. This is because Ti capping layer increases reaction between Ni and Si and suppresses the oxidation and impurity incorporation into Ni film during silicidation process. The NiSi films were treated by additional thermal stress in a resistively heated furnace for test of thermal stability, showing that the film heat-treated at $800^{\circ}C$ was more stable than that at $700^{\circ}C$ due to better crystallinity.

• Journal of the Korean institute of surface engineering
• /
• v.34 no.2
• /
• pp.105-114
• /
• 2001

$Al_2$$O_3$ coatings were deposited on M2 high speed steels by the plasma enhanced chemical vapor deposition (PECVD) process, using a gas mixture of AlC1$_3$, $H_2$, $CO_2$ and Ar $Al_2$$O_3$ coatings had interference color and showed amorphous phase. $A1_2$X$A1_3$/($Ti_{0.5}$ /$Al_{0.5}$ )N double layer coatings were produced in the sequence of substrate $NH_3$ plasma pretreatment, ($Ti_{0.5}$$Al_{0.5}$)N depoition process, $Al_2$$O_3$ deposition process. $Al_2$ $O_3$/( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings showed NaCl structure in ( $Ti_{0.5}$A $l_{0.5}$)N layer and amorphous phase in A1$_2$ $O_3$ layer. It was shown that $Al_2$ $O_3$ columns continuously grew onto ( $Ti_{0.5}$A $l_{0.5}$)N columns. ( $Ti_{0.5}$A $l_{0.5}$)N single coating and $Al_2$ $O_3$/( $Ti_{0.5}$A $l_{0.5}$)N double layer coating were oxidized at $700^{\circ}C$, 80$0^{\circ}C$, 90$0^{\circ}C$ for 1hr, 3hr in atmosphere. At 80$0^{\circ}C$, single layer coatings were oxidized, which were examined substrate oxide particle. But $Al_2$ $O_3$/ ( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings maintained the asdeposited state. Therefore, $Al_2$ $O_3$/ ( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings have moreexcellent oxidation resistance than ( $Ti_{0.5}$A $l_{0.5}$)N single layer coatings.X> 0.5/)N single layer coatings.s.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.155.2-155.2
• /
• 2013

Strain-relaxed SiGe layer on Si substrate has numerous potential applications for electronic and opto- electronic devices. SiGe layer must have a high degree of strain relaxation and a low dislocation density. Conventionally, strain-relaxed SiGe on Si has been manufactured using compositionally graded buffers, in which very thick SiGe buffers of several micrometers are grown on a Si substrate with Ge composition increasing from the Si substrate to the surface. In this study, a new plasma process, i.e., the combination of PIII&D and HiPIMS, was adopted to implant Ge ions into Si wafer for direct formation of SiGe layer on Si substrate. Due to the high peak power density applied the Ge sputtering target during HiPIMS operation, a large fraction of sputtered Ge atoms is ionized. If the negative high voltage pulse applied to the sample stage in PIII&D system is synchronized with the pulsed Ge plasma, the ion implantation of Ge ions can be successfully accomplished. The PIII&D system for Ge ion implantation on Si (100) substrate was equipped with 3'-magnetron sputtering guns with Ge and Si target, which were operated with a HiPIMS pulsed-DC power supply. The sample stage with Si substrate was pulse-biased using a separate hard-tube pulser. During the implantation operation, HiPIMS pulse and substrate's negative bias pulse were synchronized at the same frequency of 50 Hz. The pulse voltage applied to the Ge sputtering target was -1200 V and the pulse width was 80 usec. While operating the Ge sputtering gun in HiPIMS mode, a pulse bias of -50 kV was applied to the Si substrate. The pulse width was 50 usec with a 30 usec delay time with respect to the HiPIMS pulse. Ge ion implantation process was performed for 30 min. to achieve approximately 20 % of Ge concentration in Si substrate. Right after Ge ion implantation, ~50 nm thick Si capping layer was deposited to prevent oxidation during subsequent RTA process at $1000^{\circ}C$ in N2 environment. The Ge-implanted Si samples were analyzed using Auger electron spectroscopy, High-resolution X-ray diffractometer, Raman spectroscopy, and Transmission electron microscopy to investigate the depth distribution, the degree of strain relaxation, and the crystalline structure, respectively. The analysis results showed that a strain-relaxed SiGe layer of ~100 nm thickness could be effectively formed on Si substrate by direct Ge ion implantation using the newly-developed PIII&D process for non-gaseous elements.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.4
• /
• pp.394-401
• /
• 2005

A nonthermal plasma-assisted fuel reformer was developed and the effects of operating variables on the performance of this reformer were studied. The $H_2$-rich reformed gas from the reformer was injected into a diesel engine under an idle condition and the effects of the amount of injected gas on the NO and soot reduction were investigated. It was found that with increasing electric power consumption, the degree of facility of ignition of the reforming reaction in the reformer could be enhanced. The performance of the reformer including $H_2$ concentration, $H_2$ recovery, and energy conversion was affected only by the O/C mole ratio. This was because the equilibrium reaction temperature was governed by the O/C mole ratio. With increasing O/C mole ratio, the $H_2$ recovery and energy conversion passed through the maximum values of 33.4% and 66%, respectively, at an O/C mole ratio between 1.2 and 1.5. The reason why the $H_2$ recovery and energy conversion increased with increasing O/C mole ratio when the O/C mole ratio was lower than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction occurred more enough with increasing O/C mole ratio in this low O/C mole ratio range and accordingly the reaction temperature increased. Whereas the reason why the $H_2$ recovery and energy conversion decreased with increasing O/C mole ratio when the O/C mole ratio was higher than $1.2{\sim}1.5$ appeared to be that the complete oxidation reaction was further advanced and the $H_2$ recovery and energy conversion decreased. As the weight ratio of reformed diesel to total diesel which entered the diesel engine was increased to $18.2{\sim}23.5%$, NO and soot reduction efficiencies increased and reached as values high as 68.5% and 23.5%, respectively.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.44 no.7
• /
• pp.953-960
• /
• 2015

This study evaluated the effects of Rubus coreanus Miq. oil on the plasma lipid profile of high fat diet (HFD)-induced obese mice. Animals were randomly divided into 4 groups (n=10). After completion of the 5-week experimental period, we measured bodyweight gain, food intake, adipose tissue mass, and plasma lipid profile. We also analyzed the activities of carnitine and superoxide dismutase (SOD) involved in ${\beta}$-oxidation and antioxidation, respectively. Our results show that HFD-induced weight gain in animals in the R. coreanus Miq. oil diet group (RCO) and corn oil diet group (CO) was significantly lower compared to animals in the HFD group; RCO supplementation had a more noticeable effect than CO. Visceral and back fat weights were lower in the RCO and CO groups while plasma HDL cholesterol (HDL-C) and HDL-C per total cholesterol [HDL-C/TC (%)] ratio were significantly higher in the RCO group. The contents of acid-soluble acylcarnitine and total carnitine as well as SOD activation were significantly higher in the RCO group, but no significant difference was observed between the RCO and CO groups. In conclusion, RCO effectively averted elevation of total body weight and fat weight in HFD-induced obese mice and promoted increased HDL-C. Therefore, R. coreanus Miq. oil might play an anti-obesity role in obese people and could be used as an effective oil supplement.

• The Journal of Engineering Geology
• /
• v.33 no.1
• /
• pp.85-103
• /
• 2023

The in-situ remediation of a solidified stratum containing a large amount of fine-texture material like clay or organic matter in contaminated soil faces limitations such as increased remediation cost resulting from decreased purification efficiency. Even if the soil conditions are good, remediation generally requires a long time to complete because of non-uniform soil properties and low permeability. This study assessed the remediation effect and evaluated the field applicability of a methodology that combines pneumatic fracturing, vacuum extraction, and plasma blasting (the PPV method) to improve the limitations facing existing underground remediation methods. For comparison, underground remediation was performed over 80 days using the experimental PPV method and chemical oxidation (the control method). The control group showed no decrease in the degree of contamination due to the poor delivery of the soil remediation agent, whereas the PPV method clearly reduced the degree of contamination during the remediation period. Remediation effect, as assessed by the reduction of the highest TPH (Total Petroleum Hydrocarbons) concentration by distance from the injection well, was uncleared in the control group, whereas the PPV method showed a remediation effect of 62.6% within a 1 m radius of the injection well radius, 90.1% within 1.1~2.0 m, and 92.1% within 2.1~3.0 m. When evaluating the remediation efficiency by considering the average rate of TPH concentration reduction by distance from the injection well, the control group was not clear; in contrast, the PPV method showed 53.6% remediation effect within 1 m of the injection well, 82.4% within 1.1~2.0 m, and 68.7% within 2.1~3.0 m. Both ways of considering purification efficiency (based on changes in TPH maximum and average contamination concentration) found the PPV method to increase the remediation effect by 149.0~184.8% compared with the control group; its average increase in remediation effect was ~167%. The time taken to reduce contamination by 80% of the initial concentration was evaluated by deriving a correlation equation through analysis of the TPH concentration: the PPV method could reduce the purification time by 184.4% compared with chemical oxidation. However, the present evaluation of a single site cannot be equally applied to all strata, so additional research is necessary to explore more clearly the proposed method's effect.

• The Journal of Engineering Geology
• /
• v.33 no.3
• /
• pp.371-388
• /
• 2023

A stratum with a complex composition and a distributed low-permeability soil layer is difficult to remediate quickly because the soil remediation does not proceed easily. For efficient purification, the permeability should be improved and the soil remediation agent (H₂O₂) should be injected into the contaminated section to make sufficient contact with the TPH (Total petroleum hydrocarbons). This study analyzed a method for crack formation and effective delivery of the soil remediation agent based on pneumatic fracturing, plasma blasting, and vacuum suction (the PPV method) and compared its improvement effect relative to chemical oxidation. A demonstration test confirmed the effective delivery of the soil remediation agent to a site contaminated with TPH. The injection amount and injection time were monitored to calculate the delivery characteristics and the range of influence, and electrical resistivity surveying qualitatively confirmed changes in the underground environment. Permeability tests also evaluated and compared the permeability changes for each method. The amount of soil remediation agent injected was increased by about 4.74 to 7.48 times in the experimental group (PPV method) compared with the control group (chemical oxidation); the PPV method allowed injection rates per unit time (L/min) about 5.00 to 7.54 times quicker than the control method. Electrical resistivity measurements assessed that in the PPV method, the diffusion of H₂O₂2 and other fluids to the surface soil layer reduced the low resistivity change ratio: the horizontal change ratio between the injection well and the extraction well decreased the resistivity by about 1.12 to 2.38 times. Quantitative evaluation of hydraulic conductivity at the end of the test found that the control group had 21.1% of the original hydraulic conductivity and the experimental group retained 81.3% of the initial value, close to the initial permeability coefficient. Calculated radii of influence based on the survey results showed that the results of the PPV method were improved by 220% on average compared with those of the control group.