• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.224-224
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• 2003

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2000년도 정기총회 및 봄 학술발표회
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• pp.126-127
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• 2000

Fe(III) 응집제는 pH 5～9범위에서 Al(III)계 응집제보다 보다 우수한 응집효과를 보였으며 또한 pH의 영향을 거의 받지 않는 것으로 나타났다. 잔류 Fe의 경우 응집제 주입농도와 pH 증가에 영향을 거의 받지 않고 저농도의 잔류 Fe농도를 나타낸 반면, Al(III) 응집제는 잔류 Al의 급격한 증가를 나타내었다.

• 한국분말재료학회지
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• 제23권5호
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• pp.397-401
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• 2016

A lean alloy is defined as a low alloy steel with a minimum amount of the alloying element that maintains the characteristics of the sintered alloy. It is well known that the addition of elements such as Cr, P, Si, or Mn improves the mechanical characteristics of the alloy, but decreases the sinterability. The mother alloy is used to avoid an oxidation reaction with the alloying elements of Cr, P, Si or Mn. The purpose of this study is to determine the change in the mechanical properties of Fe-P-Mo and Fe-P-Mn alloys as a result of the addition of Si. In this article, the Fe-P-Mo and Fe-P-Mn alloys to which Si is added are compacted at $7.0g/cm^3$ and then sintered in $H_2-N_2$ at $1120^{\circ}C$. The P around the macropores and large grains reduces due to the formation of $SiO_2$ as the Si content increases. This is caused by the increase in strength owing to reducing intergranular fracture by suppressing the reaction with oxygen.

• 자원환경지질
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• 제36권1호
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• pp.39-48
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• 2003

본 연구에서는 황철석과 흑운모를 이용한 회분식반응조실험(batch reactor experiment)을 통하여 수용성 Cr(Ⅵ)의 제거 및 반응속도를 살펴보았으며 이에 따른 산화환원 반응기작을 고찰하였다. 황철석 실험군이 흑운모실험 군에 비해 산화환원반응속도가 100배정도 빨랐으며, pH 3의 실험군이 pH 4 실험군에 비해 Cr(III)으로의 환원반응속도가 빠르게 나타났다. 황철석 실험군에서 Cr(Ⅵ) 초기농도치 90%이상이 제거되는데 걸리는 시간은 pH가 4일때 4시간, pH가 3일 때 40분 이내였다. 반면에, 흑운모 실험군의 경우 pH가 3인 조건에서도 Cr(Ⅵ) 초기농도의 90%이상이 제거되는데 400시간 이상이 걸렸다. 모든 조건에서 Cr(III)치 농도는 초기에 증가하는 경향을 보이다가 일정시간이 지나면 안정한 농도로 고정되었다. 산성의 반응용액에서 Cr(Ⅵ)의 환원반응속도는 이 두 광물이 포함하고 있는 2가 철의 해리속도와 관련이 있음을 의미한다. pH 4의 조건인 실험군에서는 용액 내 Cr(Ⅵ)이 Cr(III)으로 환원되고 Fe(II)가 Fe(III)로 산화된 후, (Cr, Fe)(OH)$_3$$_{ (s)}$와 같은 침전물을 생성하여 상대적으로 용액내 Cr(III)과 Fe(III)농도가 낮은 것으로 여겨진다. pH 3의 실험군을 화학양론적 고찰하였으며, 흑운모의 실험에서는 수용성 Fe(II)의 감소된 양과 Cr(Ⅵ)의 환원된 양의 이론적인 몰비가 [3Fe(II) : 1Cr(Ⅵ)]임에도 그 몰 비가 약 1:1로서 1 mole의 Cr(Ⅵ)을 환원시키는데 Fe(II)이 적게 소비되었으며, 이는 광물에서 해리되는 Fe(II)에 의한 Cr(Ⅵ)의 환원뿐만 아니라 흑운모 구조 내 Fe(II)이 용액 내 Fe(III) 이온을 Fe(II) 이온으로 환원시키는 불균질산화환원반응이 발생하고 이 반응으로 생성된 Fe(II) 이온이 다시 Cr(Ⅵ)의 환원반응에 기여하였기 때문이다. 그러나 황철석 실험의 경우, 그 몰비가 약 2.90:1 로서 3에 가까우며, 이는 황철석의 빠른 산화를 통하여 급속한 Fe(II) 이온이 공급됨으로서 Cr(Ⅵ)의 환원반응이 이론적 화학양론의 반응 몰비에 부합한 결과를 보인 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.367-370
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• 2000

In this study, thin films of 70/30 and 80/20 mol% P(VDF-TrFE) copolymers were fabricated by physical vapor deposition method. In order to determine the optimum deposition condition, the copolymer thin films were fabricated in the heating temperature of 260$^{\circ}C$, 280$^{\circ}C$, and 300$^{\circ}C$. The deposition rate was measured in a real time by thickness monitor. The surface image of prepared thin films was analyzed by using AFM. From the results of TG-DTA,70/30 and 80/20 mol% P(VDF-TrFE) copolymers were observed the Curie transition point below the melting point. As the results of AFM and FT-IR analysis, we determined that the optimum deposition temperature was 300$^{\circ}C$.

• 한국결정성장학회지
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• 제19권5호
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• pp.268-276
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• 2009

In this study, activated carbon (AC) was treated with ferric ion by a sol-gel method. The compound (Fe-AC) was employed for the preparation of Fe-activated carbon/$TiO_2$, (Fe-AC/$TiO_2$) composites. The prepared Fe-AC/$TiO_2$ composites were characterized with surface properties, structural crystallinity, elemental identification and photocatalytic activity. The SEM results showed that ferric compounds and titanium dioxide were fixed onto the AC surfaces. The XRD results showed that Fe-AC/$TiO_2$ composites mostly contained anatase phase. EDX showed the presence of C, O, and Ti with Fe peaks in all samples. Its photocatalytic degradation effect was evaluated with the degradation behavior of the methylene blue (MB) solution. MB degradation could be attributed to the synergetic effects of adsorption, photo-degradation of $TiO_2$ and photo-Fenton of Fe component. The degradation rate for this photocatalysis was evaluated as a function of the concentration of the dye, the amount of $TiO_2$ and the pH. Photocataytic activity is good at activity pH.

• 한국재료학회지
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• 제21권11호
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• pp.587-591
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• 2011

The effect of the precipitator (NaOH, $NH_4OH$) and the amount of the precipitator (150, 200, 250, 300 ml) on the formation of $Fe_3(PO_4)_2$, which is the precursor used for cathode material $LiFePO_4$ in Li-ion rechargeable batteries was investigated by the co-precipitation method. A pure precursor of olivine $LiFePO_4$ was successfully prepared with coprecipitation from an aqueous solution containing trivalent iron ions. The acid solution was prepared by mixing 150 ml $FeSO_4$(1M) and 100 ml $H_3PO_4$(1M). The concentration of the NaOH and $NH_4OH$ solution was 1 M. The reaction temperature (25$^{\circ}C$) and reaction time (30 min) were fixed. Nitrogen gas (500 ml/min) was flowed during the reaction to prevent oxidation of $Fe^{2+}$. Single phase $Fe_3(PO_4)_2$ was formed when 150, 200, 250 and 300 ml NaOH solutions were added and 150, 200 ml $NH_4OH$ solutions were added. However, $Fe_3(PO_4)_2$ and $NH_4FePO_4$ were formed when 250 and 300 ml $NH_4OH$ was added. The morphology of the $Fe_3(PO_4)_2$ changed according to the pH. Plate-like lenticular shaped $Fe_3(PO_4)_2$ formed in the acidic solution below pH 5 and plate-like rhombus shaped $Fe_3(PO_4)_2$ formed around pH 9. For the $NH_4OH$, the pH value after 30 min reaction was higher with the same amount of additions of NaOH and $NH_4OH$. It is believed that the formation mechanism of $Fe_3(PO_4)_2$ is quite different between NaOH and $NH_4OH$. Further investigation on this mechanism is needed. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the pH value was measured by pH-Meter.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2008년도 추계학술발표논문집
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• pp.459-462
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• 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.

• 한국환경보건학회지
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• 제12권1호
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• pp.1-14
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• 1986

This investigation was carried out on the study of Ferrite formation by aerial oxidation of Fe $(OH)_2$ suspension of aqueous solution containing heavy metal ions. In this study the optimum reactionary condition of the Ferrite formation in Batch reactor wa studied by aerial oxidation which are subjected to various reaction time and temperature, under the different kinds of R(2NaOH/$FeSO_4$) Values, pH, Air flow rate, and $Fe^2+/M^2+$ mole ratio. The optimum condition for the Ferrite formation in Batch reactor was such that residence Time was 90 min., Temperature $65{\circ}$C, pH 11.0, Air flow rate 2.0l/min and $Fe^{2+}/M^{2+}$ mole ratio 4.0, which was observed by X-Ray diffraction analysis. The relation R-value, pH and ORP affecting the formation of Ferrite is that the jump step in pH 11.0, when a amount of NaOH is added, is steady state to the formation of Ferrite. Effect of R-value of $FeSO_4$ and $FeCl_2$ on the formation of Ferrite in different from each other the optimum condition of the in different from each other the optimum condition of the $FeCl_2$ is R-value 0.7, pH 11.0 and the $FeSO_4$ R-value 1.2, pH 11.0.

• 한국분말재료학회지
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• 제24권5호
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• pp.400-405
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• 2017

The addition of a large amount of alloying elements reduces the compactibility and increases the compacting pressure, thereby shortening the life of the compacting die and increasing the process cost of commercial PM steel. In this study, the characteristic changes of Fe-Mo-P, Fe-Mn-P, and Fe-Mo-Mn-P alloys are investigated according to the Si contents to replace the expensive elements, such as Ni. All compacts with different Si contents are fabricated with the same green densities of 7.0 and $7.2g/cm^3$. The transverse rupture strength (TRS) and sintered density are measured using the specimens obtained through the sintering process. The sintered density tends to decrease, whereas the TRS increases as the Si content increases. The TRS of the sintered specimen compacted with $7.2g/cm^3$ is twice as high as that compacted with $7.0g/cm^3$.