• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.168-168
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• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.

• Journal of Nutrition and Health
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• v.26 no.5
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• pp.566-577
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• 1993

The study was to compare the effect of dietary fatty acids on fatty acid profile in tissue and the status of tocopherol and lipid peroxidation, and superoxide dismutase and glutathione peroxidase activities at two fat levels. Male Sprague Dawley rats weighing average 350g(17 weeks) were fed either low fat(LF, 4.3% w/w, 10% kcal) or high fat(HF, 20.8%, w/w, 40% kcal)diet for 6 weeks. The fats used were beef tallow as a source of saturated fatty acid, corn oil for n-6 linoleic acid, perilla oil for n-3 $\alpha$-linolenic acid and fish oil for n-3 eiocosapentatenoic acid(EPA) and n-3 docosahexaenoic acid(DHA). Palsma tocopherol was significantly reduced by fish oil compared to beef tallow at body fat level. However, there was no significant effect on the levels of plasma MDA, RBC MDA and tocopherol, and RBC hempolysis by the type and amount of dietary fat. The peroxidizibility index of fatty acid profile in plasma and liver was increased and liver MDA level was significantly increased by fish oil when dietary fat level was increased. The activities of SOD and GSHPx tended to be increased by perilla oil and fish oil at both fat oil significantly reduced the incorpration of c20:4 and increased the incorporation of c20:5 into liver compared to corn oil. The incorporation of n-3 fatty acids into tissue by perilla oil rich in $\alpha$-linolenic acid was significantly higher tan corn oil and its effect was improved with higher amount of perilla oil in diet by high fat diet. Overall, the lipid peroxidation of tissue could be prevented by tocopherol supplementation when dietary fat level was low in diet. However, at high fat diet, tocopherol supplementation might not be enough to prevent the lipid peroxidation in tissue since the potential for lipid peroxidation was tended to be increased with higher incorporation of higher unsaturated n-3 fatty acids into tissue. Therefore, it could not be recommended to consume large amount of fish oil even with excess amount of tocopherol supplemented to the high fat diet.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.5
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• pp.651-654
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• 2001

A study was made of the efficiency of ammonia N retention by Jowar kadbi (sorghum straw), initially 6.41% crude protein (CP), treated with 4% urea solution. After 30 days the CP in straw that was unchaffed and had been left uncovered was 10.02, and in chaffed straw that had been covered with a polythene sheet was 10.9%. The two treated straws were each fed to six crossbred (HF$\times$Deoni) calves, initially $12{\pm}2$ months old and $86.7{\pm}3.2kg$ bodyweight. They were also given two isocaloric (70% TDN) and isonitrogenous (20% CP) concentrate mixtures differing in calculated Rumen Degradable to Undegradable Dietary Protein ratio (RDP:UDP). Those fed the unchaffed uncovered treated straw (treatment C) received 65 RDP:35UDP and the other group (T1) received concentrate with a 55:45 ratio. The T1 group had the higher DM intake (p<0.01) in total (306 vs 268 kg), per day (4.1 vs 3.6 kg) and per unit bodyweight. Digestibility of DM, OM, CP and NDF, but not ADF, was higher in T1 and that group had the higher daily gain (517 vs 333 g) and higher total gain (38.8 vs 25.0 kg) over the 75 d of the feeding trial. It is concluded that chaffing and covering of Jowar kadbi treated with urea, not likely to be adopted by farmers because of financial constraints, does not confer important benefits. A concentrate supplement (estimated 45% of the CP as UDP) to calves given the treated straw has a beneficial effect on their growth and development.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.733-740
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• 2011

Multiple regression analysis was used for the calculation of pKa values of 15 substituted benzaldoximes by using various types of descriptors as parameters. These descriptors are based on quantum mechanical treatments. They were derived by employing semi-empirical calculation represented by the PM3 model and an Abinitio method expressed by Hartree-Fock(HF) model performed at the 6-311 G(d, p) level of theory. The parameters tested for their ability to represent the variations observed in the experimental pKa(s) are atomic and structural properties including Muliken charges on the atoms of hydroxyl group and C=N bond, the angle $C_6-C_1-C_7$, and length of O-H bond. Molecular properties are also used like energies of HOMO and LUMO, hardness(${\eta}$), chemical potential(${\mu}$), total energy(TE), dipole of molecule(DM), and electrophilicity index(W). The relation between pKa values and each of these parameters of the studied compounds is investigated. Depending on these relations, two sets of parameters were constructed for comparison between the PM3 and HF methods. The results obtained favor the Abinitio method for such applications although both models proved to have high predictive power and have sufficient reliability to describe the effect of substituents on pKa values of benzaldoxime compounds under consideration which is clear from the values of correlation coefficient $R^2$ obtained and the consistency between the experimental and the calculated values.

• Applied Chemistry for Engineering
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• v.27 no.4
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• pp.449-454
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• 2016

In this study, highly monodispersed porous carbon microcapsules with a hollow core were synthesized using polystyrene (PS) beads as a hard template. The surface of PS was first modified with polyvinylpyrollidone (PVP) for the easy attachment of inorganic silica sol. After coating the surface of PVP modified PS microspheres with SBA-16 sol, the carbon microcapsules with a hollow macroporous core were fabricated through reverse replication method by filling carbon sources in the mesopores of silica mold. The hollow carbons having a mesoporous shell structure and narrow particle size distribution could be obtained after the carbonization of carbon source and the dissolution of silica mold by HF solution. The mesoporous characteristics and electrochemical properties of hollow carbon microcapsules were characterized by XRD, SEM, TEM, $N_2$ adsorption/desorption analysis and cyclic voltammetry. They showed the high electric conductivity and capability for use as efficient electro-materials such as a supercapacitor.

• Macromolecular Research
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• v.8 no.5
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• pp.238-242
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• 2000

The new trisiloxane-bridged heterometallic dinuclear metallocenes, hexamethyltrisiloxanediyl(cyclopentadienyltitanium trichloride) (cyclopentadienylindenyl zirconium dichloride) , $C_3ITi-Cp(CH_3)_2Si-O-Si(CH_3)_2-O-Si(CH_3)_2-Cp-ZrIndCI_2$ (1) and hexamethyltrisiloxanediyl (cyclopentadienylindenylhafnium dichloride) (cyclopentadienylindenyl zirconium dichloride), $C_2IndHf-Cp(CH_3)_2Si-O-Si(CH_3)_2-Cp-ZrIndCl_2$ 2) connecting two dissimilar metallocenes were synthesized and used for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) cocatalyst. The catalytic activity of heterometallic dinuclear metallocenes, 1 and 2 was lower than that of corresponding mononuclear metal-locene as well as two physically mixed catalysts, $CpTiCl_2/Cp_2ZrCl_2 and Cp_2HfCl_2/Cp_2ZrCl_2$. On the tither hand, MWD of PE obtained with 1 and 2 was remarkably broader ($M_w/M_n$) became up to 9.4) than those of PEs prepared with the corresponding mononuclear metallocenes and mixed catalysts. With analysis by GPC and CFC, it was found that PE produced by the heterometallic dinuclear metallocenes exhibited the definite bimodal GPC curves that should cause the broadening of MWD.

• Restorative Dentistry and Endodontics
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• v.41 no.2
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• pp.106-113
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• 2016

Objectives: This study evaluated the effects of different surface conditioning methods on the bond strength of orthodontic brackets to glazed full-zirconia surfaces. Materials and Methods: Glazed zirconia (except for the control, Zirkonzahn Prettau) disc surfaces were pre-treated: PO (control), polishing; BR, bur roughening; PP, cleaning with a prophy cup and pumice; HF, hydrofluoric acid etching; AA, air abrasion with aluminum oxide; CJ, CoJet-Sand. The surfaces were examined using profilometry, scanning electron microscopy, and electron dispersive spectroscopy. A zirconia primer (Z-Prime Plus, Z) or a silane primer (Monobond-S, S) was then applied to the surfaces, yielding 7 groups (PO-Z, BR-Z, PP-S, HF-S, AA-S, AA-Z, and CJ-S). Metal bracket-bonded specimens were stored in water for 24 hr at $37^{\circ}C$, and thermocycled for 1,000 cycles. Their bond strengths were measured using the wire loop method (n = 10). Results: Except for BR, the surface pre-treatments failed to expose the zirconia substructure. A significant difference in bond strengths was found between AA-Z ($4.60{\pm}1.08MPa$) and all other groups ($13.38{\pm}2.57-15.78{\pm}2.39MPa$, p < 0.05). For AA-Z, most of the adhesive remained on the bracket. Conclusions: For bracket bonding to glazed zirconia, a simple application of silane to the cleaned surface is recommended. A zirconia primer should be used only when the zirconia substructure is definitely exposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.19-19
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• 2007

Excimer laser annealing (ELA) 방법을 이용하여 결정화하고 게이트 절연체로써 high-k 물질을 가지는 다결정 실리콘박막 트랜지스터의 전기적 특성을 평가하였다. 다결정 실리콘 박막 트랜지스터는 비결정질 실리콘 박막 트랜지스터 보다 높은 전계 효과 이동도와 운전 용이한 장점을 가진다. 기존의 결정화 방법으로는 다결정 실리콘 박막 트랜지스터의 높은 열 공급을 피할 수 없기 때문에, 매몰 산화막 위의 비결정질 박막은 저온에서 다결정 실리콘 결정화를 위해 KrF excimer laser (248nm)를 이용하여 가열 냉각 공정을 했다. 게다가 케이트 절연체로써 atomic layer deposition (ALD) 방법에 의해 저온에서 20 nm의 고 유전율을 가지는 $HfO_2$ 박막을 증착하였다. 알루미늄은 n-MOS 박막 트랜지스터의 게이트 전극으로 사용되었다. 금속 케이트 전극을 사용하여 게이트 공핍 효과와 관계되는 케이트 절연막 두께의 증가를 예방할 수 있고, 게이트 저항의 감소에 의해 소자 속도를 증가 시킬 수 있다. 추가적으로, 비결정질 실리콘 박막의 결정화 기술로써 사용된 ELA 방법은 SPC (solid phase crystallization) 방법과 SLS (sequential lateral solidification) 방법에 의해 비교되었다. 결과적으로, ELA 방법에 의해 결정화된 다결정 실리콘 박막의 결정도와 표면 거칠기는 SPC와 SLS 방법에 비해 개선되었다. 또한, 우리는 ELA 결정화 방법에 의한 다결정 실리콘 박막 트랜지스터로부터 우수한 소자 특성을 얻었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.206-206
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• 2010

정보화 기술이 급속히 발전함에 따라서 보다 많은 양의 data를 전송, 처리, 저장 하게 되면서 이를 처리 할 수 있는 대용량, 고속, 비휘발성의 차세대 메모리의 개발이 요구 되고 있다. 이 중 저항 변화 메모리(ReRAM)는 일반적으로 전이금속산화물을 이용한 MIM 구조로서 적당한 전기 신호를 가하면 저항이 높아서 전도되지 않는 상태(Off state)에서 저항이 낮아져 전도가 가능한 상태(On state)로 바뀌는 메모리 특성을 가진다. ReRAM은 비휘발성 메모리이며 종래의 비휘발성 기억소자인 Flash memory 보다 access time이 $10^5$배 이상 빠르며, 2~5V 이하의 낮은 전압에서 동작이 가능하다. 또한 구조가 간단하여 공정상의 결함을 현저히 줄일 수 있다는 점 등 많은 장점들이 있어서 Flash memory를 대체할 수 있는 유력한 후보로 여겨지고 있다. 저항 변화의 특징을 잘 나타내는 물질에는 $TiO_2$, $Al_2O_3$, $NiO_2$, $HfO_2$, $ZrO_2$등의 많은 전이금속산화물들이 있다. 본 연구에서는 Reactive DC-magnetron Sputtering 방법과 DC-magnetron sputter를 이용하여 Ti를 증착한 후 Oxidation 방법으로 각각 증착한 $TiO_2$박막을 사용하여 저항변화특성을 관찰하였다. $TiO_2$상부에 Atomic Layer Deposition (ALD)를 이용하여 $HfO_2$ 박막을 증착하여 표면처리를 하고, 또한 $TiO_2$에 다른 전이 금속박막 층을 추가 증착하여 저항변화 특성에 접합한 조건을 찾는 연구를 진행하였다. 하부 전극과 상부 전극 물질로는 Si 100 wafer 위에 Pt 또는 TiN을 사용하였다. 저항변화 특성을 평가하기 위해 Agilent E5270B를 이용하여 current-voltage (I-V)를 측정하였다. X-ray Diffraction (XRD)를 이용하여 증착 된 전기금속 박막 물질의 결정성을 관찰했으며, Atomic Force Microscopy (AFM)을 이용하여 증착 된 샘플의 표면을 관찰했다. SEM과 TEM을 통해서는 sample의 미세구조를 확인 하였다.

• Korean Journal of Medicinal Crop Science
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• v.25 no.6
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• pp.375-380
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• 2017

Background: The objective of this study were to determine the antibacterial activity and antibiotic activity-enhancing effect of 70% ethanol extract of the root of Rumex japonicus Houtt. and its fractions when used in combination with gentamicin against aerobic skin flora. Methods and Results: The antibacterial activity and antibiotic (gentamicin) activity enhancing effect against aerobic skin flora were determined using the disc diffusion assay. Chloroform fraction (CF) and ethyl acetate fraction (EF) showed higher activities against Staphylococcus aureus and Staphylococcus epidermidis than those shown by other fractions. Regarding the antibiotic (gentamicin) activity-enhancing effect against aerobic skin flora, the n-hexane fraction (HF) and CF showed strong activity. The combination of HF and CF with gentamicin was evaluated using the broth dilution assay to determine the inhibitory effect on the growth of aerobic skin flora. The combination of CF with gentamicin exhibited the highest inhibitory effect on the growth of S. aureus and S. epdermidis. MTT assay performed to determine the viability of L929 cells revealed that EF treatment resulted in viability of 33.96 - 116.76% at the tested concentration. The combination of 70% ethanol extract and its other fractions with gentamicin showed low cell toxicity. Conclusions: Appropriate use of antimicrobial agents is important prior to the development of new antibiotics. The 70% ethanol extract of the root of R. japonicus Houtt. and its fractions showed significant synergism with gentamicin when used in combination against S. aureus and S. epdermidis. Thus, R. japonicus Houtt. could be used as a functional materials in antimicrobial-related fields.