• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.222-231
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• 2001

The material properties of $SnO_2$ were investigated as a function of the amount of $Fe_2O_3$, the partial pressure of oxygen, the concentration of CO gas, and temperature. $Fe_2O_3$-doped $SnO_2$ thick films were prepared by the screen printing technique on alumina substrate. The specimens sintered at $700^{\circ}C$ for 6 hours showed little difference of the grain size and narrow distribution with the content of $Fe_2O_3$. The electrical conductance of undoped $SnO_2$ is high at low firing temperature and at low partial pressure of oxygen. The electrical conductance of $Fe_2O_3-$-doped $SnO_2$ is increased with measurement temperature, but decreased with the content of $Fe_2O_3$. The dependence of oxygen partial pressure is decreased with dopant addition. The highest sensitivity and the good properties of response speed and repeatability for CO gas were observed on the specimen with 0.1 mol% $Fe_2O_3$ at $350^{\circ}C$.

• Korean Journal of Animal Reproduction
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• v.24 no.3
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• pp.255-262
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• 2000

The aim of this work was to study the effects of ascorbic acid (Asc) and/or ferrous sulfate (Fe$^{2+}$) and spernatozoa preincubation on the in vitro fertilization in porcine. Porcine follicular oocytes matured in culture were inseminated with frozen-thawed boar spermatozoa preincubated for 0, 1, 2, 3, 4 and 5h. The penetration rates (37~51%) were not significantly different between durations of spermatozoa preincubation in medium with 0.1 mM Asc. The addition of 1.0 mM Fe$^{2+}$ during spermatozoa preincubation were not significantly affecting the penetration rates (41~56%). When spermatozoa were preincubated with Asc and Fe$^{2+}$, the penetration rates had a tendency to increase with time of spermatozoa preincubation, and were significantly (P<0.05) higher in spermatozoa preincubated with that than without Asc and Fe$^{2+}$ for 5 h. On the other hand, when spermatozoa were preincubated in fertilization medium without Asc and/or Fe$^{2+}$, the penetration rates were significantly (P<0.05) higher in medium with Fe$^{2+}$ than with Asc or Asc and Fe$^{2+}$ for in vitro fertilization. The rate of polyspermy in penetrated oocytes in medium with Asc and Fe$^{2+}$ decreased with the period of spermatozoa preincubation. Despite different culture conditions for spermatozoa preincubation, no differences were observed in polyspermy rates in the presence of Asc and/or Fe$^{2+}$ These results indicate the advantage of preincubating spermatozoa with Asc and Fe$^{2+}$ and an addition of Fe$^{2+}$ during in vitro fertilization with spermatozoa preincubated maintain penetration potential without increased polyspermy rates on in vitro fertilization in porcine oocytes.on in porcine oocytes.

• Journal of the Korean Magnetics Society
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• v.12 no.3
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• pp.88-93
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• 2002

Rapidly solidified NdFeB powders were mixed with fine powders of pure metal elements before CA-press employed to obtain a fully dense isotropic precursor. Subsequently, the precursor was deformed by CA-deformation to obtain an anisotropic magnet. The CA-deformed anisotropic NdFeB magnets with 0.3 wt.% Zn or Sn exhibited the coercivities about 80% higher (11.4. and 11.2 kOe, respectively) than that (6.4 kOe) of the additive-free magnet.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1806-1808
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• 2000

MHz영역에서 사용 가능한 Fe계 연자성 재료를 초미세 결정립으로 제조하기 위해 $Fe_{93}Zr_{3}B_4$ 박막을 기본조성으로 하여 Fe와 비고용이며 약반자성인 Ag 원소를 0, 3, 4, 5, 6, 10 at.% 첨가시킨 $Fe_{93-x}Zr_{3}B_{4}Ag_{x}$ 박막을 DC 마그네트론 스퍼터링법으로 제조하였다. 그리고, 300-600$^{\circ}C$ 온도 범위에서 1시간동안 열처리한 후 강제공냉법으로 냉각한 후 XRD를 이용하여 열처리 온도 및 Ag 첨가량에 따른 결정상 동정을 조사하였다. Ag가 첨가되지 않은 $Fe_{93}Zr_{3}B_4$ 박막의 경우 $\alpha$-Fe의 (110) 피크만 관찰되었다. Ag가 첨가된 경우에는, Ag의 양이 증가함에 따라 $\alpha$-Fe 결정상의 형성이 억제되고, 비정질형태의 broad한 ${\alpha}-Fe_{(110)}$ 피크와 Ag피크가 관찰되었다. Ag가 첨가된 As-deposited 시편을 열처리 할 경우 박막의 비정질화로 주 peak인 $\alpha$-Fe 피크의 강도가 현저히 낮아지고 상대적으로 Ag peak가 두드러졌다. Ag의 양이 3a/o인 경우는 열처리온도 400$^{\circ}C$이상에서 박막의 결정화로 $\alpha$-Fe Peak가 나타나고 상대적으로 Ag 구성원소의 피크의 강도는 현저하게 낮아졌다 또한. Ag의 양 증가할수록 As-deposited 박막 내에 Ag 구성원소외 피크의 강도는 증가하여 $\alpha$-Fe와 Ag가 서로 비고용 상태로 서로 혼재되어 있었다.

• Economic and Environmental Geology
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• v.46 no.1
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• pp.29-37
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• 2013

In order to apply the silver cementation method using Fe powder from pregnant thiourea leaching solution. Parameters such as the amount of Fe powder addition, agitation speed, and temperature were investigated. The silver cementation rate was increased by the increasing of Fe powder addition, agitation speed, and temperature. The highest silver cementation rate was found when the addition of Fe powder was 50 g/L at the agitation speed of 500 rpm. The silver cementation rate increase with increasing temperature according to the Arrhenius equation and obeys $1^{st}$ order kinetics. The activation energy from the kinetics data was found to be between 13.73 KJ/mol and 17.02 KJ/mol. In the XRD analysis, goethite was detected in the precipitate of the thiourea leach solution. This indicates that an oxidation-reduction reaction had occurred in the thiourea solution due to the addition of the Fe powder.

• Journal of the Korean Magnetics Society
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• v.8 no.3
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• pp.138-143
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• 1998

We have investigated the magnetic properties of FeBN and FeSiN films deposited by RF magnetron reactive sputtering system. It was investigated that the compositions of B, Si and N were the main factors influencing the soft magnetic properties and film resistivity. The addition of small amount of N significantly improve the soft magnetic properties and electrical resistivity. The FeBN and FeSiN films were showed good soft magnetic properties which were Hc<1 Oe, Bs:19~19 kG and $\mu$'>1000 values. The composition of films were $Fe_{75}(BN)_{25},\;Fe_{78}(SiN)_{22}$ and resistivity was 100~120 $\mu$$\Omega$-cm. but, futher increase in B, Si and N concentration degraded the soft magnetic properties due to formation of nitride such as $Fe_4N$ compound.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.252-258
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• 1998

A feeding experiment was conducted to investigate the effects of deletion of P, Ca, Zn, Mg, Fe, K, Mn, or Se from mineral premix in the diets containing $40\%$ fish meal on growth performance of juvenile Korean rockfish. Three replicate groups of the fish initially averaging 5.4 g were fed the experimental diets deleted one ot each mineral (P, Ca, Zn, Mg, Fe, K, Mn, Se or all) in the mineral premix for 9 weeks. A basal diet with fish meal ($40\%$), meat meal ($9\%$), soybean meal ($5\%$), corngluten meal ($3\%$), and leather meal ($3\%$) as protein sources were included. Weight gain in fish fed diets deleted Ca, Zn, K, or Se was lower than that of control diet ( P<0.05). Daily feed intake, condition factor, hepatosomatic index and liver chemical composition were not affected by dietary mineral premixes (P>0.05). Apparent skeletal deformities were not observed in the diets deleted each mineral, The data obtained in this study indicate that each of the Ca, Zn, K, or Se should be added in the diet contained $40\%$ fish meal for normal growth of Korean rockfish.

• Korean Journal of Poultry Science
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• v.33 no.2
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• pp.113-119
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• 2006

This study was carried out to investigate the effects of dietary Saccharomyces cerevisiae (wild yeast mutant) and Saccharomyces cerevisiae hFeHLC (ferritin containing yeast) and chelated Fe on growth performance and body composition of broiler chicks. A total of 252 (1-day old) 'Ross' broiler chicks were allotted to seven dietary treatments: I) control without iron supplementation, 2) 0.1% wild yeast mutant (YM03), 3) 1.0% wild yeast mutant, 4) 0.1% ferritin containing yeast (YF04), 5) 1.0% ferritin containing yeast, 6) 0.01% chelated Fe and 7) 0.1% chelated Fe. The highest weight gain obtained from broilers fed 0.01% chelated Fe was 2,121g, the lowest weight gain obtained from broilers fed control diet was 2.087g. The growth performance results were not significantly different in weight gain, feed intake and feed conversion ratio of broilers diets containing wild yeast, ferritin containing yeast and chelated Fe supplementation and control diets (P>0.05). The lowest iron content in meat was for control 30.51 mg/dL and the highest Fe content was for 0.1% ferritin containing yeast 41.58 mg/dL, but these were not significantly different (P>0.05).

• Electrical & Electronic Materials
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• v.5 no.4
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• pp.406-410
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• 1992

본 논문에서는 MgFe$_{2}$O$_{4}$ 세라믹스의 구조적 특성을 개선하기 위하여 TiO$_{2}$를 0-10[wt%] 첨가하여 세라믹스를 만들고 TiO$_{2}$가 습도센서용 MgFe$_{2}$O$_{4}$ 세라믹스의 구조적 특성에 미치는 영향을 조사하였다. 각 시편은 TiO$_{2}$가 첨가되는 양이 증대함에 따라 NgTi$_{2}$O$_{5}$의 이상이 나타났다. TiO$_{2}$의 첨가량이 6[wt%]일 때 까지는 시편의 밀도가 증가하여 기공율의 저하를 가져왔고 기공의 크기가 최소가 되는 조성은 5[wt%]의 TiO$_{2}$가 첨가되었을 때이며 이때의 평균 기공의 크기는 1615[.angs.]이었다. 따라서 5[wt%]의 TiO$_{2}$를 첨가했을 때가 기공의 크기 조절에 최적이라고 생각되며 센서용 기판으로 응용하기 적합하다고 생각된다.

• Korean Journal of Materials Research
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• v.8 no.2
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• pp.141-146
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• 1998

Ball mill을 이용하여 Ar 분위기에서 기계적 합금법으로 $Fe_{ 5}$$Si_{x}$ $B_{5-x}$ 분말을 제조하고, 제조된 분말을 연속 진공 열처리 시킨 후 Si첨가에 따른 결정구조 및 자기적성질을 조사하였다. 250시간 볼밀처리한 Fe$_{5}$ $B_{5}$ 합금에서 전체적으로 비정질 구조가 형성되었으나 일부분에 결정질이 존재하고 있었으며, $800^{\circ}C$에서 2시간 열처리하면 FeB와 $Fe_{2}$B 상이 혼재된 구조를 얻었다. 250시간 볼밀처리한 $Fe_{5}$ $Si_{2}$$B_{3}$합금에서 전체적으로 비정질 구조를 얻을 수 있었고, 이 시료를 2시간, $800^{\circ}C$로 열처리 하였을 때 $Fe_{2}$B상은 사라지고, 대부분 FeB의 균질한 상을 나타내었다. $Fe_{5}$ $B_{5}$ /조성에서는 분말 입자크기가 약 $1\mu\textrm{m}$이었으나, Si이 첨가되면 분말 입자크기가 약 $10\mu\textrm{m}$로 커졌다. Si의 첨가에 의해서 비정질상의 형성을 촉진시켜 단일 FeB상의 합성시간을 단축시킬 수 있었다.