• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.194-198
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• 2001

In order to look for polymeric materials applicable to the oxygen electrode membranes of biosensors, polyurethanes (PUs) were synthesized from poly(butylene succinate) diol (Mn 1150), poly(ethylene glycol) (Mn 200), and 4,4'-methylenebis(cyclohexyl isocyanate). The PUs (Mn 15000-100000) underwent the crystallization and melting transitions in the temperature range of 20-30 $^{\circ}C$ and 90-110 $^{\circ}C$, respectively. The oxygen permeability for the PU membranes prepared by the solution casting method could not be measured since oxygen simply leaked through the membranes with an audible noise. However, when the PUs were blended with carboxylated poly(vinyl chloride) (CPVC), the permeability could be measured. The oxygen permeability coefficient (Po2) of the PU/CPVC $(96}4)$ membranes (6.4 Barrer) was high enough for the application as the electrode membranes. The Po2 decreased dramatically when the CPVC content increased from 4 to 5 wt%, but decreased very slowly and approached to that of CPVC (~0.26 Barrer) when the CPVC content increased further. The scanning electron micrographs of the membranes revealed that the PU membranes were composed of large crystal grains with many pores, but the size of the PU crystal grains and pores decreased progressively with increasing the CPVC content.

• 열처리공학회지
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• 제8권4호
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• pp.266-278
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• 1995

The high strain-rate dynamic plastic behavior of Fe-X%Mn alloys was investigated. The strain rate did not have an effect when tested under quasi-static strain rates($2{\times}10^{-3}/sec$ and $2{\times}10^{-1}/sec$). However, the true stress increased at all strain levels when the strain rate increased to $6{\times}10^3/sec$. Based on the experimental results, an constitution equation to calculate the dynamic strength for strain rates over $10^4/sec$ was determined. The Fe-5%Mn alloy containing athermal ${\alpha}^{\prime}$ martensite initially did not show work hardening. The work hardening increased with Mn content showing a maximum at 20% Mn. The high work hardening of Fe-20%Mn and Fe-30%Mn alloys appears to be closely related not only to the initial amounts of ${\varepsilon}$ martensite but to the strain induced transformation (${\gamma}{\rightarrow}{\varepsilon}$ and ${\varepsilon}{\rightarrow}{\alpha}^{\prime}$) occurring during each stages of deformation.

• Corrosion Science and Technology
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• 제13권3호
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• pp.102-106
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• 2014

Nickel electrodeposition from sulfamate bath has several benefits such as low internal stress, high current density and good ductility. In nickel deposited layers, sulfur induces high temperature embrittlement, as Ni-S compound has a low melting temperature. To overcome high temperature embrittlement problem, adding manganese is one of the good methods. Manganese makes Mn-S compound having a high melting temperature above $1500^{\circ}C$. In this work, the mechanical properties of Ni-Mn deposited layers were investigated by using various process variables such as concentration of Mn$(NH_2SO_3)_2$, current density, and bath temperature. As the Mn content of electrodeposited layers was increased, internal stress and hardness were increased. By increasing current density, internal stress increased, but hardness decreased. With increasing the bath temperature from 55 to $70^{\circ}C$, internal stress of Ni deposit layers decreased, but hardness didn't change by bath temperature. It was likely that eutectoid manganese led to lattice deformation, and the lattice deformation increased hardness and internal stress in Ni-Mn layers. Increasing current density and decreasing bath temperature would increase a mount of $H_2$ absorption, which was a cause for the rise of internal stress.

• 한국자기학회지
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• 제5권5호
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• pp.552-555
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• 1995

The magnetic properties of Mg-Mn ferrites were investigated in the composition range of $Mg_{a}Mn_{b}Fe_{c}O_{4\pm\delta}$ (a+b+c=3) with the addition of $Al_{2}O_{3}$. In $MgO-MnO-Fe_{2}O_{3}$ ternary system, the spinel single phase existed within the composition range of MgO-50 mol%, MnO-70 mol% and $Fe_{2}O_{3}-60\;mol%$. The saturation magnetic flux density increased with the increase of $Fe_{2}O_{3}$ content and showed the maximum at the stoichiometric composition of $(Mg,Mn)Fe_{2}O_{4}$. In $Mg_{x}Mn_{1-x}Fe_{2}O_{4}(x=0.2~0.8)$ system, the saturation magnetic flux density showed the maximum at $Mg_{0.2}Mn_{0.8}Fe_{2}O_{4}$. The addition of $Al_{2}O_{3}$ resulted in the decrease of saturation magnetic flux density but increased the electrical resistivity.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.385-388
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• 2009

Dry-sliding-wear behavior of Fe-18Cr-l0Mn steel with various carbon and nitrogen contents was characterized, and the effect of carbon and nitrogen contents on the wear was investigated. Dry sliding wear tests of the steel were carried out at room temperature against an AISI 52100 bearing steel ball using a pin-on-disk wear tester. Applied wear loads were varied from 10 N to 100 N, and the sliding distance was fixed as 720 m. Worn surfaces and the wear debris of the steel were examined using an SEM to find out the wear mechanism. It was found that the Fe-18Cr-10Mn with both carbon and nitrogen exhibited superior wear resistance to the steel with only nitrogen. The wear resistance of the Fe-18Cr-10Mn-xC-yN alloy increased with the increase of the carbon content. The excellent wear resistance of the Fe-18Cr-10Mn-xC-yN alloy was explained by the increased strain-hardening capability with the interstitial atoms.

• 한국작물학회지
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• 제54권2호
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• pp.225-230
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• 2009

본 연구는 생식생장기의 습해에 의한 콩 수량과 질소 및 여러 가지 양분흡수에 미치는 영향을 알고자 지하수위를 0 cm, 10 cm 및 40 cm로 달리하여 조사하였다. 지하수위가 높음에 따라 생육과 수량은 감소되었으며 다원콩의 감소정도가 풍산나물콩보다 더 크게 나타났다. 질소흡수량은 지하수위가 높을수록 감소되었으며 수량과의 상관관계는 $R^2=0.872$로 고도로 유의한 정의상관을 보였다. K함량은 지하수위 높이에 큰 차이를 보이지 않았으며(뿌리 제외), Ca함량은 감소(잎, 줄기) 또는 증가(뿌리)하였지만 Mn과 Fe 함량은 지하수위가 높을수록 급격히 증가하였으며 다원콩이 풍산나물콩보다 높은 함량을 보였다.

• 전기화학회지
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• 제10권4호
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• pp.239-244
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• 2007

산소자리에 치환된 불소가 $Li_{1-x}FeO_2Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8) 양극 활물질에 미치는 영향을 고찰하기 위해 다양한 양의 불소를 치환시킨 $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.05{\le}y{\le}0.15$) 양극 활물질을 고상법을 이용하여 합성하였다. 불소 미치환 시료 및 치환양이 0.05와 0.1의 시료의 경우, $1-1.5\;{\mu}m$ 크기의 막대 형상 분말 형태에 50-100 nm정도의 작은 구형 입자들이 주위에 분포되어 있는 형태이었다. 반면, 불소 치환양이 0.15인 시료의 경우, 그 모양이 구형으로 변화되어지며 입자가 급격하게 성장하였다. 합성된 시료를 이용하여 제작된 셀들의 충 방전 수행 결과, $Li/Li_{1-x}FeO_{1.9}F_{0.1}-Li_xMnO_2$ 셀이 163 mAh/g의 가장 높은 초기용량을 보였으며 50 싸이클 후에도 95%의 높은 가역 특성을 보였다. 특히, 활물질내의 불소 치환양이 증가할수록 초기 방전용량도 같이 증가하였으나, 불소이온의 치환양이 일정량을 (y>0.1) 넘는 경우에는 산소 자리에 불소이온이 완전하게 치환되지 못하고 불순물로 존재함으로써 전지의 가역특성을 현저하게 저하시키는 요인으로 작용함을 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1083-1086
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• 2004

We applied the spray pyrolysis technique to prepare Mn-doped $BaMgAl_{10}O_{17}$ (BAM) particles with high photoluminescence, which could be used in the plasma display device as a green phosphor. Several preparation conditions were investigated in order to tail the vacuum ultraviolet (VUV) characteristics. Some portions of barium were replaced with strontium to improve the luminescent intensity of BAM:Mn particles under VUV excitation. The content of Mn and Sr was optimized to obtain high luminescent efficiency under VUV excitation. Finally, the optimized BAM:Mn green particles showed higher photoluminescence intensity than that of commercial $Zn_2SiO_4$ and comparable with commercial barium-aluminate phosphor.

• 한국분말재료학회지
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• 제10권2호
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• pp.129-135
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• 2003

Nanocrystalline powders of $MnFeP_{1-x}As_x$(x=0.45-0.6) have been synthesized by mechanochemical reaction at room temperature using high-energy ball milling from mixtures of Mn, Fe, P, and As Powders. It has been found that a mechanically induced self-propagating reaction (MSR) occurs within 2 hours of milling and it produces very fine polycrystalline powder having a hexagonal $Fe_2P$ structure. Further milling up to 24 hours did not change the crystalline and average particle sizes or the phase composition of the milling product. When x is 0.65, no reaction among the reactants has been observed even after 24 hours of milling. As the P content decreases in $MnFeP_{1-x}As_x$, the incubation time for the MSR has increased and the lattice constants in both a and c axes have changed.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.581-584
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• 2008

$BaMgP_2O_7$:Eu,Mn phosphors for white emission were synthesized and their luminescent properties were investigated under UV excitation. The phosphor emits two colors: a blue band by $Eu^{2+}$ and a red band by $Mn^{2+}$. Due to the efficient energy transfer from $Eu^{2+}$ to $Mn^{2+}$, the red emission positioned at 615 nm is greatly enhanced with increasing $Mn^{2+}$ content up to 17.5 mol%.