• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.47-50
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• 2007

[ $ZnCr_2O_4$ ] shows geometrically frustrated magnet. Recently, $CoCr_2O_4$ has been investigated for multiferroic property and dielectric anomalies by spin-current model. Polycrystalline $CoCr_2O_4$ and $CoCrFeO_4$ compounds was prepared by wet-chemical process. Crystallographic and magnetic properties of $CoCr_2O_4$ and $CoCrFeO_4$ were investigate by using the x-ray diffractometer(XRD), vibrating sample magnetometer(VSM), superconducting quantum interference device magnetometer(SQUID), and $M\"{o}ssbauer$ spectroscopy. The crystal structure was found to be single-phase cubic spinel with space group of Fd3m. The lattice constants of $CoCr_2O_4$ and $CoCrFeO_4$ $a_0$ were determined to be 8.340 and 8.377 ${\AA}$, respectively. The ferrimagnetic transition temperature for the both samples were observed at 97 K and 320 K. The $M\"{o}ssbauer$ absorption spectra at 4.2 K show that the well developed two sextets are superposed with small difference of hyperfine field($H_{hf1}=507\;and\;H_{hf2}=492\;kOe$). Isomer shift values($\delta$) of the two sextets are found to be 0.33 and 0.34 mm/s relative to the Fe metal, respectively, which are consistent with the high spin $Fe^{3+}$ charge state.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.205-211
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• 1992

The $2{\nu}_{C=0}$ + amide III combination band spectrum of acetamide (AA) was obtained in very dilute solutions of AA+lanthanide shift reagents (LSR) in carbon tetrachloride over the range of $15^{\circ}$ to $45^{\circ}C$. It was found that only 1 : 1 AA-LSR complex is formed by the interaction between carbonyl oxygen of AA and central metal ion(Ln(Ⅲ)) in LSR. The thermodynamic parameters for Ln(III)${\cdot}$O=C bond were determined by computer analysis of concentration and temperature dependent spectra. ${\Delta}H^{\circ}$ for the coordination of AA to Eu$(dpm)_3$, Yb$(dpm)_3$, and Pr$(dpm)_3$ have been found to be -39.1, -28.4, and -25.5 kJ/mol, respectively. It has shown that this type of ion-dipole interaction is more than twice stronger compared to the dipole-dipole interaction in the amide linkage, and largely depending on the steric hindrence effect by the bulky dpm groups around central metal ion (Ln(III)) rather than the ionic potential effect of central metal ion itself.

• The Korean Journal of Pesticide Science
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• v.7 no.2
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• pp.108-116
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• 2003

A series of new quinclorac family, herbicidal 3-phenyl-5-(3,7-dichloro-8-quinolinyl)-1,2,4-oxadiazole derivatives as substrate were synthesized and their growth inhibition activity $(pI_{50})$ against root and shoot of rice plant (Oryza sativa L.) and barnyard grass (Echinochloa crus-galli) were determined. And then comparative molecular field analysis (CoMFA) and molecular holographic quantitative structure- activity relationship (HQSAR) were compared in terms of their potential for predictiability. The statistical results were suggested that HQSAR based model had better predictability than CoMFA model. The selective factors to remove barnyard grass take electron withdrawing groups which can be created positive charge and steric bulky on the phenyl ring. Results revealed that the unknown 2,6-dichloro-substituent, U5 and 2,4,6-trichloro-substituent, U6(${\Delta}pI_{50}$=CoMFA: 1.18 & HQSAR: 1.82) were predicted as compound with higher activity and selectivity.

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1155-1161
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• 2001

Yittrium Iron Garnet(YIG) has been used as an important material in the circulator/isolator which is used in RF communication system, mobile phone, adn satellite broadcasting, etc. In this study, we investigated the microstructural and magnetic properties of YIG ferrites with the sintering temperature and additives. We fabricated the YIG ferrites substituted with Ca, In, V by the traditional ceramic sintering method at 1250$\^{C}$, 1275$\^{C}$, 1300$\^{C}$ and 1325$\^{C}$. Powders were granulated by using a spray dryer. Crystallographic and microstructural properties were measured by using XRD and SEM. Magnetic properties were measured by using a VSM for saturation magnetization (4$\pi$M$\_$s/) and FMR (Ferromagnetic Resonance) experiment for ferromagnetic resonance line width (△H). The YIG ferrite, Y$\_$1.6/Ca$\_$1.4/Fe$_4$V$\_$0.7/In$\_$0.3/O$\_$12/, sintered at 1300$\^{C}$, showed higher saturation magnetization and lower ferromagnetic resonance line width than any other sintering temperatures.

• Journal of the Korean Magnetics Society
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• v.16 no.2
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• pp.144-148
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• 2006

$CoGa_{0.1}Fe_{1.9}O_4$ nanoparticles have been prepared by a sol-gel method. The structural and magnetic properties have been investigated by XRD, SEM, VSM and $M\ddot{o}ssbauer$ spectroscopy. $CoGa_{0.1}Fe_{1.9}O_4$ powder that was annealed at $250^{\circ}C$ has spinel structure and behaved superparamagnetically. The estimated size of superparammagnetic $CoGa_{0.1}Fe_{1.9}O_4$ nanoparticle is around 10 nm. The hyperfine fields at 4.2 K f3r the A and B patterns were found to be 518 and 486 kOe, respectively. The blocking temperature $(T_B)$ of superparammagnetic $CoGa_{0.1}Fe_{1.9}O_4$ nanoparticle is about 250 K. The magnetic anisotropy constant of $CoGa_{0.1}Fe_{1.9}O_4$ nanoparticle was calculated to be $3.0X10^5\;ergs/cm^3$. $CoGa_{0.1}Fe_{1.9}O_4$ nanoparticle was annealed at $250^{\circ}C$ will be used to candidate for biomedicine applications as magnetic carriers.

• Journal of Korea Port Economic Association
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• v.32 no.2
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• pp.73-90
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• 2016

In Climate change is a global issue that requires global responses. As a key factor in climate change, greenhouse gas (GHG) emissions have attracted increasing attention the international community. One of the crucial global efforts to alleviate climate change is the establishment of an international climate change regime, comprising rules, norms, principles, procedures that are applicable to a wide range of activities. The International Maritime Organization (IMO) received a mandate from the Kyoto Protocol to regulate shipping GHG emissions. However, the IMO Convention and the UN Convention on the Law of the Sea also provide regulations on regarding GHG emissions. To execute its mandate, the IMO has developed various regulatory initiatives. In addition, the Chinese government has declared new regulations which designate parts of its coastal waters as emission control areas (ECA). Owing to the growing recognition of the benefits of ECA, ships, including ocean-going vessels that operate in areas near the Pearl River Delta, Yangtze River Delta, and the Bohai Sea will be obliged to use fuel containing less than 0.5% sulfur. China's shipping industry is playing a growing role in the international shipping market, and its response to these initiatives will have a substantial effect on the future application of these regulations. This study analyzed the GHG mandates of the IMO and the Chinese government, and then examines the main outcomes that have been achieved.

• Restorative Dentistry and Endodontics
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• v.31 no.4
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• pp.269-281
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• 2006

This study evaluated the effectiveness and safety of an experimental bleaching strip (Medison dental whitening strip. Samsung medical Co., Anyang, Korea) containing 2.9% hydrogen peroxide. Twenty-three volunteers used the bleaching strips for one and a half hour daily for 2 weeks. As control group. the same strips in which hydrogen peroxide was not included were used by 24 volunteers with the same protocol. The shade change (${\Delta}E^{*}$, color difference) of twelve anterior teeth was measured using Shade Vision (X-Rite Inc., S.W. Grandville, MI, USA). Chroma Meter (Minolta Co., Ltd. Osaka. Japan) and Vitapan classical shade guide (Vita Zahnfabrik, Germany). The shade change of overall teeth in the experimental group was significantly greater than that in the control group (p < 0.05) and was easily perceivable. The change resulted from the increase of lightness (CIE $L^{*}$ value) and the decrease of redness (CIE $a^{*}$ value) and yellowness (CIE $b^{*}$ value). The shade change of individual tooth was greatest in canine. and smallest in central incisor. The safety of the bleaching strip was also confirmed.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.46-46
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• 2000

과학기술 및 산업의 발달로 인하여 실험 중 또는 공정 상에서 in situ, 실시간으로 측정하고 분석하며 이를 되먹임하는 품질제어의 중요성이 대두되고 있다. 반도체 공정 또는 박막제조 공정 중에서 박막의 두께, 굴절율, 물질의 조성비 등을 알아내는 것이 긴요한 과제로 대두되고 있으며, 이를 위하여 공정중인 제품의 품질을 실시간으로 평가하는 장비가 요구되고 있는 것이다. 나아가 공정중의 예상하지 못한 시료의 특성변화를 그대로 감지하여 적절히 보정해 주는 되먹임 기법은 높은 수율을 보장하는 첨단기법이라 할 수 있다. 이러한요구에 부응할 수 있는 본 제품(Elli-situ 2000)은 박막의 두께 표면변화를 sub 의 정밀도를 가지고 in situ, 실시간으로 정밀 측정할 수 있는 첨단 계측장비로서 빛의 편광상태 변화를 측정하기 때문에 공정 중의 시료에 영향을 주지 않는 비간섭 특성과 비접촉 특성의 장점 뿐만 아니라 공기중에서는 물론 진공이나 액체 등의 매질에서도 사용될 수 있어서 매질에 대한 제약이 거의 없다는 장점도 가지고 있다. 편광상태의 제어 및 측정을 필요한 광학장비의 경우, 제작이 까다롭기 때문에 대부분 가격이 높은 편이고 사용방법이나 측정 데이터에 대한 해석이 어렵다는 단점이 있으나, Elli-situ 2000의 경우 상용화된 외국제품(국내제품은 없슴)과 비교하여 성능 및 가격경쟁력에 있어서도 우위에 있으며 간단, 명료한 장비조작 및 컴퓨터를 사용한 구동의 전자동화를 이룸으로써 초보자도 쉽게 측정하고 데이터를 처리할 수 있도록 하였다. 또한 취부대의 경우, 진공포트 플랜지의 표준규격(2-3" Del-Seal 플랜지 규격)에 맞춤으로써 기존의 진공챔버에 부착하여 진공에 전혀 영향을 주지 않는 상태에서 시료의 변화를 in situ, 실시간으로 정밀 측정할 수 있도록 하였다. 하였다.O 박막은 산소 가스압력과 기판온도, 인가 전류를 변화시켜가며 증착하였으며 이에 따른 박막의 결정성 변화를 알아보았다. 기판온도를 실온에서 점차 증가시켜나가면 $\Delta$$\theta$50은 급격히 감소하며 30$0^{\circ}C$에서는 결정성이 우수한 막을 얻을 수 있었다. 또한 산소 가스 압력이 0.5~1mTorr에서 $\Delta$$\theta$50은 양호한 값을 나타내었지만 그 이상에서는 c-축 배향성이 나빠짐을 확인하였다. 따라서 대향타겟식스퍼터 장치를 이용하여 ZnO 박막을 증착시 가스압력 0.5~1mTorr, 기판온도 20$0^{\circ}C$이상의 막 제작조건에서 결정성이 우수하게 나타나는 것을 확인할 수 있었다. gluten이 단단해졌음을 알수 있었다. 유화제 stearly 칼슘, 혹은 hemicellulase를 amarans 10% 대체한 밀가루에 첨가하면 확연히 비용적을 증대시킬 수 있다는 사실을 알 수 있었다. quinoa는 명아주과 Chenopodium에 속하고 페루, 볼리비아 등의 고산지에서 재배 되어지는 것을 시료로 사용하였다. quinoa 분말은 중량의 5-20%을 quinoa를 대체하고 더욱이 분말중량에 대하여 0-200ppm의 lipase를 lipid(밀가루의 2-3배)에 대하여 품질개량제로서 이용했다. 그 결과 quinoa 대량 7.5%에서 비용적, gas cell이 가장 긍정적 결과를 산출했고 반죽의 조직구조가 강화되었다. 또 quinoa 대체에 의해 전분-지질 복합제의 흡열량이 증대된 것으로부터 전분-지질복합제의 형성 촉진이 시사되었다.이것으로 인하여 호화억제에 의한 노화 방지효과가 기대되었지만 실제로 빵의 노화는 현저히 진행되었다. 이것은

• Korean Journal of Materials Research
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• v.2 no.5
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• pp.353-359
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• 1992

Thermal oxidation and plasma enhanced chemical vapor deposition of tantalum oxide thin films on p-type (100) Si substrates were studied to examine the dielectric nature of T$a_2O_5$ as a Al/T$a_2O_5$/p-Si capacitor. Microstructure and dielectric properties of the capacitors were investigated by XRD, AES, high frequency C-V analyzer, I-V meter and TEM. XRD analysis showed that the structure of T$a_2O_5$ films were amorphous, but the films were crystallized to hexagonal $\delta$-T$a_2O_5$ by 65$0^{\circ}C$ thermal oxidation treatment. It was found that the stoichiometry of the films was more or less close to 2 : 5. Leakage current density and relative dielectric constant of thermal oxidation T$a_2O_5$ film at 60$0^{\circ}C$ was 5.0${ imes}10^{-6}$/A/c$m^2 and 31.5, respectively. In the case of PECVD T$a_2O_5$film deposited at 0.47W/c$m^2 they were 2.5${ imes}10^{-5}$/A/$ extrm{cm}^2$ and 24.0, respectively. The morphology of the films and interfaces were investigated by TEM.

• Economic and Environmental Geology
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• v.22 no.1
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• pp.1-16
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• 1989

Electrum-galena-sphalerite mineralization of the Yangpyeong-Weonju Au-Ag area was deposited in three stages of quartz and calcite veins which fill fault breccia zones. Fluid inclusion and stable isotope data show that ore mineralization was deposited at temperatures between $260^{\circ}C$ and $180^{\circ}C$ from fluids with salinities between 8.9 and 2.9 equivalent weight percent NaCl. Evidence of boiling indicates pressures of <50 bars, corresponding to depths of 220 to 550 m, respectively, assuming lithostatic and hydrostatic loads. Au-Ag deposition was likely a result of bolling coupled with cooling. Within stages I and II there is an apparent increase in ${\delta}^{34}S$ values of $H_2S$ with paragenetic time ; early -1.4~2.7‰ to later 6.6-9.2‰. The progressively heavier $H_2S$ values can be generated through isotopic re-equilibration in the ore fluid following removal of $H_2S$ by boiling or precipitation of sulfides. Measured and calculated hydrogen and oxygen isotope values of ore-forming fluids suggest meteoric water dominance, approaching unexchanged meteoric water values. Comparison of these values with those of other Korean Au-Ag deposits reveals a relationship between depth and degree of water-rock interaction. All investigated Korean Jurassic and Cretaceous gold-silver-bearing deposits have fluids which are dominantly evolved, meteoric water, but on1y deeper systems (${\geq}1.25km$) are exclusively gold-rich.