• Journal of Applied Biological Chemistry
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• v.43 no.3
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• pp.156-160
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• 2000

The possible mechanism of the DNA strand breaking activity of the hot-water extract of Fructus Chaenomelis (dried fruit of Chaenomeles sinensis) in a closed circular duplex replica form DNA (RFI DNA) was studied through agarose gel electrophresis under various conditions. Induction of DNA strand scission by the hot-water extract of C. sinensis occurred in dose and time-dependent manners. $Cu^{2+}$ was indispensable for the induction of DNA strand breakage. Exogeneous chelating agents inhibited the DNA breaking activity, conforming the catalytic action of $Cu^{2+}$ on generation of free radicals responsible for oxidative damage. Antioxidant enzymes and some radical scavengers were used to investigate the major radical species triggering the DNA strand scission, demonstrating that a highest inhibitory activity was found in the presence of catalase, while less in the presence of tiron (a scavenger for superoxide radical), 2-aminoethyl-isothiuroniumbromide-HBr, cysteamine (scavengers for hydroxyl radical), and 1,4-diazabicyclo [2,2,2] octane (a scavenger for singlet oxygen) in decreasing order. The findings implied that oxygen radical species generated in presence of transition divalent cation during the oxidation of some compounds contained in the hot-water extract of C. sinensis is mainly responsible for inducing genotoxicity.

• Journal of the Korean Chemical Society
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• v.18 no.1
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• pp.25-30
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• 1974

The crystal and molecular structure of monoethanolamine hydrobromide, HOCH2CH2NH2 HBr, has been determined by X-ray diffraction methods. The crystals are triclinic, space group Pi and unit cell contains two formula units and has dimensions a = 4.54, b = 7.45, c = 7.76${\AA}$ and ${\alpha}$ = 102.5, ${\beta}$=93.6, ${\gamma}=78.7^{\circ}$. The present structure determination confirmed that the structure of monoethanolamine hydrobromide is isomorphous with that of monoethanolamine hydrochloride.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.713-717
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• 2004

In this study, the etched trench properties including cross-sectional profile, surface roughness, and crystalline defects were investigated depending on the various silicon etching and additive gases, For the case of HBr$He-O_2SiF_4$ trench etching gas mixtures, the excellent trench profile and minimum defects in the silicon trench were achieved. Due to the residual oxide film grown by the additive oxygen gas, which acts as a protective layer during trench etching, the undercut and defects generation in the trench were suppressed. To improve the electrical characteristics of trench gate, the hydrogen annealing process after trench etching was also adopted. Through the hydrogen annealing, the trench corners might be rounded by the silicon atomic migration at the trench corners having high potential. The rounded trench corner can afford to reduce the gate electric field and grow a uniform gate oxide. As a result, dielectric strength and TDDB characteristics of the hydrogen annealed trench gate oxide were remarkably increased compared to the non-hydrogen annealed one.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.127-128
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• 2007

고밀도 트렌치 게이트 전력소자 제조를 위해 HBr. He-$O_2$, $SiF_4$, $CF_4$ 등의 식각 가스를 이용하여 형성한, 트렌치 표면 거칠기 및 손상을 최소화 하여 고밀도 트렌치 게이트 전력소자를 제조하였다. 트렌치 형상 각도가 약 900일 경우 항복전압은 약 29 V인 반면, 트렌치 각도가 $88^{\circ}$일 경우 항복전압이 37V로 트렌치 형상에 따라 약 25%의 항복전압이 높아졌음을 알 수 있었다. n-채널 트렌치 게이트 전력소자의 전압-전류 측정 결과 트렌치 게이트 수가 45.000개일 때 게이트에 10 V를 인가했을 때 전류는 약 46 A로 측정되어 고밀도 트렌치 게이트 전력소자의 특성이 좋음을 알 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.177.1-177.1
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• 2015

플라즈마 건식 식각공정은 반도체 공정에 있어 증착 및 세정 공정과 함께 중요한 공정중 하나이다. 기존 연구에서는 높은 식각 속도, 종횡비, 대면적에 대한 균일도 증가를 위하여 플라즈마 이온 밀도의 증가와 전자 온도를 감소시키기 위한 노력을 하고 있으며 플라즈마 식각분석 연구에서는 분광학 분석 기법을 활용하여 플라즈마에 의하여 활성화된 식각 가스와 박막 표면의 반응 메커니즘 연구가 진행 중에 있다. 그러나 지금까지의 플라즈마 식각연구에서는 플라즈마 식각 공정에서 발생되는 박막의 damage에 대한 연구는 전무하다. 본 연구에서는 플라즈마 식각과정에서 발생되는 박막 표면의 damage 연구를 위하여 Nano-indenter에 의한 분석 기법을 제시하였다. Nano-indentation 기법은 박막 표면을 indenter tip으로 직접 인가하여 박막 표면의 기계적 특성을 분석하고 이를 통하여 플라즈마에 의한 박막 표면의 물성 변화를 정량적으로 측정한다. 실험에서 플라즈마 소스는 Adaptively Coupled Plasma (ACP)를 사용하였고 식각 가스로는 HBr 가스를 주로 사용하였으며, 플라즈마 소스 파워는 1000 W로 고정 하였다. 연구 결과에 의하면 식각공정 챔버 내 압력이 5, 10, 15 및 20 mTorr로 증가함에 따라 TEOS SiO2 박막의 강도가 7.76, 8.55, 8.88 및 6.29 GPa로 변화되는 것을 측정하였고 bias power에 따라서도 다르게 측정됨을 확인하였다. 이 결과를 통하여 Nano-indentation 분석 기법을 활용하여 TEOS SiO2 박막의 식각공정의 변화에 따른 강도변화를 측정함으로써 플라즈마에 의한 박막 표면의 damage를 정량적으로 측정 가능함을 확인하였다.

• Steel and Composite Structures
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• v.36 no.2
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• pp.213-228
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• 2020

Shape Memory Alloys (SMAs) are new materials used in various fields of science and engineering, one of which is civil engineering. Owing to their distinguished capabilities such as super elasticity, energy dissipation, and tolerating cyclic deformations, these materials have been of interest to engineers. On the other hand, the connections of a steel structure are of paramount importance because of their vulnerabilities during an earthquake. Therefore, it is indispensable to find approaches to augment the efficiency and safety of the connection. This research investigates the behavior of steel connections with extended end plates equipped hybridly with 8 rows of high strength bolts as well as Nitinol superelastic SMA bolts. The connections are studied using component method in dual form. In this method, the components affecting the connections behavior, such as beam flange, beam web, column web, extended end plate, and bolts are considered as parallel and series springs according to the Euro-Code3. Then, the nonlinear force- displacement response of the connection is presented in the form of moment-rotation curve. The results obtained from this survey demonstrate that the connection has ductility, in addition to its high strength, due to high ductility of SMA bolts.

• Mass Spectrometry Letters
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• v.4 no.4
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• pp.87-90
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• 2013

Isotope amount ratios of lead in a bronze sample have been successfully determined using multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Matrix separation conditions were tested and optimized using ion exchange chromatography with anion-exchange resin, AG1-X8, and sequential elution of the 0.5 M HBr and 7 M $HNO_3$ to separate lead from very high contents of copper and tin in bronze matrix. Mercury was also removed efficiently in the optimized separation condition. The instrumental isotope fractionation of lead in the MC-ICP-MS measurement was corrected by the external standard sample bracketing method using an external standard, NIST SRM 981 lead common isotope ratio standard followed by correction of procedure blank to obtain reliable isotope ratios of lead. The isotope ratios, $^{206}Pb/^{204}Pb$, $^{207}Pb/^{204}Pb$, $^{208}Pb/^{204}Pb$, and $^{208}Pb/^{206}Pb$, of lead were determined as $18.0802{\pm}0.0114$, $15.5799{\pm}0.0099$, $38.0853{\pm}0.0241$, and $2.1065{\pm}0.0004$, respectively, and the determined isotope ratios showed good agreement with the reference values of an international comparison for the same sample within the stated uncertainties

• Macromolecular Research
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• v.13 no.3
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• pp.257-264
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• 2005

Polyurethanes containing z-Iysine segments in the main chain (PULL) were synthesized from 4,4'-diphe-nylmethyl diisocyanate, poly(tetramethylene glycol), and z-Iysine oligomer as a chain extender. The PULL film was treated first with a $10\%$ HBr-acetic acid solution and subsequently with a saturated sodium bicarbonate aqueous solution to produce a primary amine group on the surface (PULL-N). Lactobionic acid (LA)-immobilized PULL (PULL-L) was prepared by the coupling reaction of the PULL surface amine groups and the LA carboxylic acid groups. The surface-modified PULLs were then characterized by attenuated total reflection-Fourier transform infra-red spectroscopy, electron spectroscopy for chemical analysis, atomic force microscopy, and contact angle goniometry. In the hepatocytes adhesion experiment, the cells poorly adhered to the PULL surface, although they adhered moderately well to the PULL-N surface. On the other hand, the cells adhered well to the PULL-L surface, suggesting the good affinity of the surface $\beta$-galactose moieties for hepatocytes. When hepatocytes were cultured in the presence of epidermal growth factor for 48 h, the cells rapidly aggregated on the PULL-L surface, whereas they aggregated only slowly on the other surfaces. The PULL prepared in this study has the potential to be used as a coating material for the enhancement of hepatocyte adhesion.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.10a
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• pp.56-56
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• 1999

For advanced TFT-LCD manufacturing processes, dry etching of thin-film layers(a-Si, $SiN_x$, SID & gate electrodes, ITO etc.) is increasingly preferred instead of conventional wet etching processes. To dry etch Al gate electrode which is advantageous for reducing propagation delay time of scan signals, high etch rate, slope angle control, and etch uniformity are required. For the Al gate electrode, some metals such as Ti and Nd are added in Al to prevent hillocks during post-annealing processes in addition to gaining low-resistivity($<10u{\Omega}{\cdot}cm$), high performance to heat tolerance and corrosion tolerance of Al thin films. In the case of AI-Nd alloy films, however, low etch rate and poor selectivity over photoresist are remained as a problem. In this study, to enhance the etch rates together with etch uniformity of AI-Nd alloys, magnetized inductively coupled plasma(MICP) have been used instead of conventional ICP and the effects of various magnets and processes conditions have been studied. MICP was consisted of fourteen pairs of permanent magnets arranged along the inside of chamber wall and also a Helmholtz type axial electromagnets was located outside the chamber. Gas combinations of $Cl_2,{\;}BCl_3$, and HBr were used with pressures between 5mTorr and 30mTorr, rf-bias voltages from -50Vto -200V, and inductive powers from 400W to 800W. In the case of $Cl_2/BCl_3$ plasma chemistry, the etch rate of AI-Nd films and etch selectivity over photoresist increased with $BCl_3$ rich etch chemistries for both with and without the magnets. The highest etch rate of $1,000{\AA}/min$, however, could be obtained with the magnets(both the multi-dipole magnets and the electromagnets). Under an optimized electromagnetic strength, etch uniformity of less than 5% also could be obtained under the above conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.287-287
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• 2011

ITRS(international technology roadmap for semiconductors)에 따르면 MOS (metal-oxide-semiconductor)의 CD(critical dimension)가 45 nm node이하로 줄어들면서 poly-Si/SiO2를 대체할 수 있는 poly-Si/metal gate/high-k dielectric이 대두되고 있다. 일반적으로 metal gate를 식각시 정확한 CD를 형성시키기 위해서 plasma를 이용한 RIE(reactive ion etching)를 사용하고 있지만 PIDs(plasma induced damages)의 하나인 PICD(plasma induced charging damage)의 발생이 문제가 되고 있다. PICD의 원인으로 plasma의 non-uniform으로 locally imbalanced한 ion과 electron이 PICC(plasma induced charging current)를 gate oxide에 발생시켜 gate oxide의 interface에 trap을 형성시키므로 그 결과 소자 특성 저하가 보고되고 있다. 그러므로 본 연구에서는 이에 차세대 MOS의 metal gate의 식각공정에 HDP(high density plasma)의 ICP(inductively coupled plasma) source를 이용한 중성빔 시스템을 사용하여 PICD를 줄일 수 있는 새로운 식각 공정에 대한 연구를 하였다. 식각공정조건으로 gas는 HBr 12 sccm (80%)와 Cl2 3 sccm (20%)와 power는 300 w를 사용하였고 200 eV의 에너지로 식각공정시 TEM(transmission electron microscopy)으로 TiN의 anisotropic한 형상을 볼 수 있었고 100 eV 이하의 에너지로 식각공정시 하부층인 HfO2와 높은 etch selectivity로 etch stop을 시킬 수 있었다. 실제 공정을 MOS의 metal gate에 적용시켜 metal gate/high-k dielectric CMOSFETs의 NCSU(North Carolina State University) CVC model로 effective electric field electron mobility를 구한 결과 electorn mobility의 증가를 볼 수 있었고 또한 mos parameter인 transconductance (Gm)의 증가를 볼 수 있었다. 그 원인으로 CP(Charge pumping) 1MHz로 gate oxide의 inteface의 분석 결과 이러한 결과가 gate oxide의 interface trap양의 감소로 개선으로 기인함을 확인할 수 있었다.