• Journal of the Korean Magnetics Society
• /
• v.11 no.6
• /
• pp.256-261
• /
• 2001

These experiments were carried out to examine the effects of element substitution of Zn and La-Zn for Sr-ferrite. The calcined properties of Zn and La-Zn element substitution were examined, and also the sintered magnetic properties were compared with the stoichiometric condition. The magnetization properties of calcined SrM materials is as follows; M$\_$s/ : 61.06 emu/g. Also, the magnetization properties of calcined Zn$\_$0.3/-SrM materials is as follows; M$\_$s/ : 66.90 emu/g. The sintered magnetic properties of (La-Zn)$\_$0.3/-SrM composition is as follows; B$\_$r/ : 4.21 kG, BH$\_$max/: 4.19 MGOe.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.2
• /
• pp.126-132
• /
• 2018

For the first time, an innovative approach using P(VDF-TrFE) as a polymer electrolyte for high efficiency, all-solid-state supercapacitors is presented. The polymer electrolyte was successfully achieved by dissolving P(VDF-TrFE) copolymers in dimethylformamide (DMF). Thermal analysis and infrared spectroscopy revealed excellent thermal stability up to $400^{\circ}C$ and copolymer's interaction with DMF. Electrochemical capacitors fabricated using P(VDF-TrFE) in DMF and ZnO NWs demonstrated high capacitive performance. Furthermore, the gel electrolyte-based supercapacitors demonstrated excellent mechanical durability up to a bend angle of $120^{\circ}$. Novel P(VDF-TrFE) electrolytes could be a promising approach for applications in flexible, fabric-based, and high-efficiency energy devices.

• Journal of the Korean Magnetics Society
• /
• v.6 no.6
• /
• pp.382-387
• /
• 1996

The characteristics of the complex permeability of ${(Ni_{x}Cu_{0.2}Zn_{0.8-x}O)}_{1-w}{(Fe_{2}O_{3})}_{1+w}$ with various Ni and $Co_{3}O_{4}$ contents were investigated in this work. It is found that the NiCuZn ferrites with $x{\geq}0.6$ have a relatively small peak width of the imaginary part of permeability $\mu$". The resonance frequency is increased as Ni content becomes higher, where the loss is low. The $\mu$" value decreases with increasing FezO, deficiency, but the resonance frequency($f_{\mu"max}$) is only slightly affected by $Fe_{2}O_{3}$ deficiency. In case of $Co_{3}O_{4}$ addition to the NiCuZn ferrites, the $f_{\mu"max}$ increases since the initial permeability decreases with the amount of $Co_{3}O_{4}$. It is concluded that the Ni content in the NiCuZn ferrite is a dominant factor for the total loss of these spinel ferrites.

• Journal of the Korean Ceramic Society
• /
• v.13 no.4
• /
• pp.5-8
• /
• 1976

Both oriented and non-oriented ferroxplana $Co_{1-x}Zn_xZ(Ba_3Co_{2(1-x)}Zn_{2x} Fe_{24}O_{41})$ with x=0.00, 0.45 were prepared by conventional ceramic method. The magnetostrictions of thus prepared specimens were measured by use of the three terminal capacitor device at room temperature. The magnitude of measured values was approximately five times greater than that of ZnY ferroxplana. The easy-magnetization plane at room temperature of both CoZ and Co0.55 $Zn_{0.45}$Z was their basal plane. The magentostrictions in the basal plane and the other planes showed saturated values at magnetic field intensity of about 2Koe and 4Koe, respectively. The magnetostriction constants $K_1, \; K_2, \;K_3\; and\; K_4$ for CoZ were -2.4, -10.5, -5.9 and -45.2$\times10^{-6}$ , while those for $Co_{0.55}Zn_{0.45}Z$ were +0.1, -1.2, -6.3 and -39.0$\times$10^{-6}, , respectively.

• Journal of Environmental Health Sciences
• /
• v.20 no.1
• /
• pp.62-67
• /
• 1994

Introduction : Recently, water and environmental pollution becomes serious social problem and high technology makes this pollution accelerate. Hydrogen sulfide, the main subject of our research, is one of the most dangerous air pollutant like SO$_x$ and NO$_x$. The major contaminant in coal gasification is H$_2$S, which is very toxic, hazardous and extremely corrosive. Therefore, control of hydrogen sulfide to a safe level is essential. Although commercial desulfurization process called liquid scrubbing is effective for removal of H$_2$S, it has drawbacks, the loss of sensible heat of the gas and costly wastewater treatment. Many investigations are carried out about high-temperature removal ol H$_2$S in hot coal-derived gas using metal oxide or mixed metal qxide sorbents. It was reported that ZnO was very effective sorbent for H2S removal, but it has big flaw to vaporize elemental zinc above 600\ulcorner \ulcorner As alternative, metal oxides such as CaO, $Fe_2O_3$, TiO$_2$ and CuO were added to ZnO. Especially, different results are reported for $Fe_2O_3$ additive. Tamhankar et al. reported SiO$_2$ with 45 wt% $Fe_2O_3$ sorbent is favorable for removal of H$_2$S and regeneration.

• Journal of Environmental Health Sciences
• /
• v.12 no.1
• /
• pp.69-78
• /
• 1986

In order to determine the content levels of trace metals in cow's milk, 79 market milk samples were collected from markets in major cities of Korea from July to August, 1985 and analyzed for content levels of Cu, Fe, Zn, Mn, Pb, Cd. The Results were as follows Cu, average 43.5 $\mu$g/l range 14 ~ 172.7 $\mu$g/l Fe, average 398.4 $\mu$g/l range 35 ~ 1,873 $\mu$g/l Zn, average 2.917 mg/l range 1.233 ~ 7.46 mg/l Mn, average 26.74 $\mu$g/l range 7.6 ~ 102 $\mu$g/l Pb, average 33.9 $\mu$g/l range N.D. ~ 105 $\mu$g/l Cd, average 1.73 $\mu$g/l range N.D. ~ 5.4 $\mu$g/l

• Proceedings of the KAIS Fall Conference
• /
• 2008.11a
• /
• pp.459-462
• /
• 2008

본 논문에서는 $10K_2O$-30CaO-$60P_2O_5$ mol%를 기본조성으로 하여 Fe, Cu, Zn의 미량성분을 첨가하여 유리를 제조하고 용출 특성을 평가 하였다. 제조된 유리는 미량성분의 첨가량에 따라 유리의 투명도가 변하는 것이 관찰되었다. 용출특성은 측정 4시간 뒤 pH값 증가되는 것으로 16시간 후 pH가 증가하는 것으로 관찰되었다. 여기서 pH의 증가는 염기성산화물이 용출되는 것으로, 감소는 $P_2O_5$구조인 망목형성구조가 붕괴되어지면서 산성이온이 용출되어지는 것으로 판단되어진다. ICP관찰시에는 함량이 증가하면서 K, Ca, P이온의 용출량이 감소되었고, Zn, Cu, Fe이온의 용출량이 증가하는 경향이 관찰되었다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.04a
• /
• pp.385-388
• /
• 2003

폐광석에 함유되어 있는 총중금속함량을 측정하기 위한 전함량분석과 중금속을 다량 함유한 폐광석이 산성환경에 노출되어 있을 경우 중금속의 지화학적 거동을 파악하기 위해 산도를 변화시키면서 용출실험을 실시하였다. 전함량분석과 용출실험을 종합한 결과, 중금속 및 미량원소의 용출거동 특성을 크게 As-Co-Fe 형태와 Cu-Mn-Cd-Zn형태와 Pb로 구분할 수 있었다. As-Co-Fe의 용출특성은 약산성의 환경에서는 용출이 미약하나, 최종 pH 1.5이하의 강산성환경에서는 용출량이 급격하게 증가하며, Cu-Mn-Cd-Zn형태에서는 최초로 용해되는 pH가 5.0-3.0으로 As-Co-Fe 보다 다소 높았다. Pb는 다른 형태에 비해 상당히 적게 용출되었다 최종 용출된 함량과 관계없이 초기 용출이 발생하는 pH값을 기준으로 한 각 원소의 상대적인 이동성은 Mn =Zn>Cd=Cu>>Fe=Co>As>Pb 순서이며, 산성비는 Zn, Mn 및 Cu를 쉽게 용출시켜 이동도를 증가시킬 것으로 판단된다.

• Journal of the Korean Magnetics Society
• /
• v.5 no.5
• /
• pp.730-734
• /
• 1995

The variation of magnetic permeability and dielectric constant and their relationship with microwave absorbing properties are investigated in sintered Ni-Zn ferrite. Toroid specimens of ${(Ni_{0.5}Zn_{0.5}O)}_{1-y}{(Fe_{2}O_{3})}_{1+y}$ ferrites are prepared by conventional ceramic processing technique. The large change in magnetic permeability is observed by the variation of excess $Fe_{2}O_{3}$ in the Ni-Zn ferrites. The more the iron-excess from y=0.04 to y=0.12, the lower value of both $\mu_{r}'$ and $\mu_{r}"$ is observed. However dielectric permittivity increases with the increase of the increase of the excess $Fe_{2}O_{3}$. The control of permittivity is realized by nitrogen sintering atmosphere and excess $Fe_{2}O_{3}$ respectively.

• Journal of environmental and Sanitary engineering
• /
• v.23 no.1
• /
• pp.33-48
• /
• 2008

The purpose of this study was to characterize background mass concentration of $PM_{10},\;PM_{2.5}$ and metallic composition from June 2004 to June 2005 in comparison with Seoul and Asan city. The results were as follows: 1. Annual mean of $PM_{10}$ concentrations in Seoul and Asan were $56.95({\pm}25.63){\mu}g/m^3,\;57.02({\pm}27.22){\mu}g/m^3$ respectly. 2. Annual mean of $PM_{2.5}$ concentrations in Seoul and Asan were $46.97({\pm}40.36){\mu}g/m^3,\;42.16({\pm}21.79){\mu}g/m^3$ respectly. 3. The average $PM_{2.5}/PM_{10}$ ratio was 0.82 in Seoul and 0.74 in Asan city. 4. The concentration of $PM_{10},\;PM_{2.5}$ were the highest in spring and the lowest in summer. Asan was higher than Seoul in spring and summer. 5. The results showed that average $PM_{10}$ composition order as Si>Fe>Pb>Zn>Mn in Seoul and Si>Fe>Zn>Pb>Mn in Asan. The concentration of metals in $PM_{10}$ of Seoul that Cr, Cu, Fe, Mn were high in spring and Zn was low in Fall. Fe, Mn were high in spring of Asan. 6. The results showed that average $PM_{2.5}$ composition order as Si>Pb>Fe>Zn>Mn in Seoul and Si>Fe>Pb>Zn>Cr in Asan. The concentration of metals in $PM_{2.5}$ of Seoul that Cr was high in spring. 7. The result showed that relation between Cr and Cu, Cu and Fe, Fe and Mn, Mn and Zn, Zn and Si in Seoul, Cr and Zn, Cu and Pb, Zn and Pb, Pb and Mn in Asan. The result showed that $PM_{10}$ concentration exceeding $50{\mu}g/m^3$(US-EPA Standard) and $PM_{2.5}$ concentration exceeding $15{\mu}g/m^3$(US-EPA Standard). In urban area, the monitoring of $PM_{2.5}$ permits the anthropogenic sources and the interference of natural sources with respect to $PM_{10}$ measurements.