• 한국분말재료학회지
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• 제26권4호
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• pp.340-344
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• 2019

Due to the rapid development of electricity, electronics, information communication, and biotechnology in recent years, studies are actively being conducted on nanopowders as it is required not only for high strengthening but also for high-function powder with electric, magnetic, and optical properties. Nonetheless, studies on nickel nanopowders are rare. In this study of the synthesis of nickel nanoparticles from $LiNiO_2$ (LNO), which is a cathode active material, we have synthesized the nanosized nickel powder by the liquid reduction process of $NiSO_4$ obtained through the leaching and purification of LNO. Moreover, we have studied the reduction reaction rate according to the temperature change of liquid phase reduction and the change of particle size as a function of NaOH addition amount using hydrazine monohydrate ($N_2H_4{\cdot}H_2O$) and NaOH.

• Reproductive and Developmental Biology
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• 제39권4호
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• pp.117-125
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• 2015

Iron is required for cell viability but is toxic in excess. While the iron-mediated malfunction of testicular cells is well appreciated, the underlying mechanism(s) of this effect and its relationship with fertility are poorly understood. Ferritin is a ubiquitous intracellular protein that controls iron storage, ferroxidase activity, immune response, and stress response in cells. Ferritin light chain protein (FTL) is the light subunit of the Ferritin. Previously, we had identified the FTL in bovine spermatozoa following capacitation. In present study, to investigate the role of Ferritin in sperm function, mice spermatozoa were incubated with multiple doses (1, 10 and $100{\mu}M$) of sodium nitroprusside (SNP), an iron donor. SNP was increased Ferritin levels in a dose-dependent manner. The Ferritin was detected on the acrosome in spermatozoa by immunocytochemistry. Short-term exposure of spermatozoa to SNP increased tyrosine phosphorylation and the acrosome reaction (AR). Finally, SNP affected a significant decrease in the rate of fertilization as well as blastocyst formation during early embryonic development. On the basis of these results, we propose that the effects of Ferritin on the AR may reduce overall sperm function leads to poor fertility in males and compromised embryonic development.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1996년도 제7회 학술강연회논문집
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• pp.137-144
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• 1996

내열 복합 재료에 사용되는 경화된 페놀 수지(DURITE SC-1008)의 열분해 상수를 알아보기 위하여 Henderson and Freidman 분석법을 이용하여 반응 속도 상수를 구하였다. 가열 속도는 5,10, $20^{\circ}C$/min으로 변화 시켰으며 각각의 중량 감소 곡선으로부터 속도 상수 값을 구하였다. 열분해 반응은 크게 두 구간으로 나누어 진행되었으며 이러한 반응을 모사하기 위하여 반응 구간에 따른 속도 상수 값을 구하였다. 또한 실험 상수 값의 정확성을 확인하기 위하여 이론 열중량 곡선식을 직접 유도하여 상수 값을 대입한 결과 그 차이는 상관 계수가 1.19로써 실제 실험 값과 이론식에서 얻어진 값이 거의 일치되었다 그러므로 열분해 반응을 모사하기 위해서는 변화된 가열 속도에 따라서 중량 감소량을 구한 후 열분해 반응 구간을 분리하여 반응 상수론 구하는 것이 필요하다.

• 한국세라믹학회지
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• 제28권6호
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• pp.429-436
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• 1991

Silicon carbide has been grown by a chemical vapor deposition (CVD) technique using CH3SiCl3 and H2 gaseous mixture onto a graphite substrate. Based on the thermodynamic equilibrium studies and the suggestion that the deposition rate of SiC is controlled by surface reaction theoretical kinetic equation for CVD of silicon carbide has been proposed. The proposed theoretical kinetic equation for CVD of silicon carbide agreed well with the experimental results for the variation of the deposition rate as a function of the partial pressure of reactant gases. The Vikers microhardness of the SiC layer was about 3000∼3400 kg/$\textrm{mm}^2$ at room temperature.

• 자원리싸이클링
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• 제10권1호
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• pp.42-48
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• 2001

The dissolution behavior of gold and silver from gold-silver alloys in aerated cyanide solutions has been investigated by an electrochemical means as well as a direct measurement of gold and silver ions reported in the bulk solution as a function of time using rotating disc electrodes. The variables studied included oxygen partial pressure, rotating speed of the disc, concentration of cyanide, temperature and composition of the allyos. The dissolution potential and the rate of dissolution were obtained in view of the anodic and cathodic current-potential relationships. The results were discussed in terms of the mixed potential theory. The results showed that the dissolution rate of gold and silver from the alloys was controlled partially by chemical reaction. but largely by transport of either oxygen or cyanide, depending on their relative concentration under the experimental conditions employed in this study.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.866-869
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• 2001

In this study, (Ba,Sr)TiO$_3$(BST) thin films were etched with a magnetically enhanced inductively coupled plasma(MEICP). Etching characteristics of BST thin films including etch rate and selectivity were evaluated as a function of the etching parameters such as gas mixing ratio, rf power, dc bias voltage and chamber pressure. The maximum etch rate of the BST films was 1700 $\AA$/min at Ar(90)/CF$_4$(10), 600 W/350 V and 5 mTorr. The selectivity of BST to PR was 0.6, 0.7, respectively. To analyze the composition of surface residue remaining after the etching, samples etched with different CF$_4$/Ar gas mixing ratio were investigated with X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). From the results of XPS and SIMS, there are chemical reaction between Ba, Sr, Ti and C, F radicals during the etching and remained on the surface.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.138-139
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• 2007

This research provides machine designers with some intuition to consider both, magnetic and heat transfer effects. A topological multi-objective function includes magnetic energy and heat inflow rate to the system, which equals to the total heat dissipation by conduction and convection. For the thermal field regarding the heat inflow, introduced as a reaction force, topology design sensitivity is derived by employing discrete equations. The adjoint variable method is used to avoid numerous sensitivity evaluations. As a numerical example, a C-core design excited by winding current demonstrates the strength of the multi-physical approach.

• Bulletin of the Korean Chemical Society
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• 제22권4호
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• pp.362-366
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• 2001

To show the effects of metallothionein (MT) on the activity of enzymes involved in the removal of reactive oxygen species, MT has been added to the assay systems of superoxide dismutase (SOD), catalase and peroxidase. We have used assay systems of SOD based on NADPH oxidation and nitrite formation from hydroxylammonium chloride as an assay of superoxide breakdown rate. The two assay systems showed different results at the high concentration of MT. MT showed the scavenging of superoxide in the SOD assay system in the presence and absence of SOD. MT added to the SOD assay system behaved as an activator of SOD, but apo-MT behaved as an inhibitor. When MT was added to the assay system in the presence of a fixed amount of SOD, the breakdown rate of superoxide increased. The effects of MT on the decomposition of hydrogen peroxide and the activity of catalase and peroxidase decomposing hydrogen peroxide were evaluated. MT decreased the activities of catalase and peroxidase. We have concluded that the function of MT as an antioxidant might effect the level of superoxide scavenging and not the level of hydrogen peroxide.

• 공업화학
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• 제5권6호
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• pp.1062-1067
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• 1994

Ethylacetoacetate로부터 2단계의 연속합성을 통하여 생성되는 5-methyl-4-imidazolecarboxylic acid ester의 합성반응 속도론과 중간 생성물인 ${\alpha}$, {\beta}$-dioxobutyric acid(일명 diketone)의 반응 안정성을 연구하였다. 반응속도 결정단계는 ${\alpha}$-acetyl-${\alpha}$-hydroxy iminoacetic acid(oxime)로부터 diketone으로 진행되는 과정으로서 반응속도에 영향을 미치는 주된 인자로는 Oxime, HCl의 농도와 반응온도임을 확인하였고 HCl 농도 4.6~8.0M 반응온도 $8.5{\sim}20^{\circ}C$의 변화에 따른 diketone의 최대 반응수율 변화는 50~74%이었다. Power-law 수식모델 및 회분식 반응기 empirical data로부터 diketone 생성반응 속도식을 구하였으며 이 식이 실험 Data와 잘 일치하고 있음을 보였다. 본 연구는 5-methyl-4-imidazolecarboxylic acid ester 연속반응 공정개발의 기초단계로서 반응속도론 연구를 통하여 합성 반응의 특성을 파악하는데 중요한 의의를 두고 있다.

• 한국환경과학회지
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• 제10권1호
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• pp.65-71
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• 2001

HRP(high rate pond) which had kept the manufactured clay of 3cm-thickness as benthic clay in reactor and the 6 flat-blade turbine as impeller for agitation was named HRASP(high rate algae stabilization pond). And the experiment for treatment of artificial synthesis wastewater containing COD :300mg/$\ell$, NH$_3$-N : 300mg/$\ell$, T-P : 9mg/$\ell$ as nutrients was been performed successfully. This reactor was been operated under conditions : 24hrs.-irradiation and water temperature, $25^{\circ}C$ and pH 7 and agitation velocity, 15, 30, 45rpm and the effect of agitation velocity on algal bioaccumulation of nutrients was been studied with view point of fluid dynamics. The next followings could be obtained as results. 1. The agitation with a turbine impeller blade in HRASP makes clay particle indicate superior suspension effect by means of forming of excellent curl/shear flow in reactor. 2. The excessive suspension of clay particle which is created at 45rpm as rotation velocity of impeller blade of turbine disturbs the light penetration and algal photosynthesis reaction. 3. Efficiencies for removal of nutrients come out as COD : 93.9%~94.3%, ($NH_3-N + NO_3-N$) : 81.9%~99.0%, T-P : 46.8%~53.6%. 4. Kuo values of $K_1$for algal growth come out seperately as 15rpm : $1.876{\times}10^{-2}, 30rpm : 4.618{\times}10^{-3}$. 5. Kuo values of $K_2$for removal of N, P come out seperately as 15rpm : $8.403{\times}10^{-1}$ and $1.397{\times}10^{-1}$, 30rpm : $4.823{\times}10^{-1} and 2.052{\times}10^{-1}$. 6. It can be guessed easily that the excessive agitation can inhibit the algal and bacterial symbiotic reaction if it is considered that micro organism\` sense to preservation of life is relied on natural function of metabolism. Therefore the studies for this matter should be followed continuously.