• 한국산림과학회지
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• 제108권3호
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• pp.322-328
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• 2019

본 연구는 임도 유지관리 및 보수를 위한 기초자료를 제공하기 위하여 경상북도 영양군 임도를 대상으로 동평판재하시험(light drop weight test), 들밀도 시험 및 입도분석을 이용하여 개설시기 및 횡단위치별(성토부 차륜부(T0), 노면 중앙부(C), 절토부 차륜부(T1))에 따른 임도노반 지지력 분석을 실시하였다. 들밀도 및 입도분석결과, 들밀도는 2011년 개설임도가 $2.0694g/cm^3$으로 가장 높은 값을 나타냈으며, 2017년 개설임도가 $1.7443g/cm^3$으로 가장 낮은 값을 나타내었다. 입도분석은 2017년 개설임도에서 큰 골재의 비율이 가장 높게 나타났으며, 시기가 늦어질수록 큰 골재의 비율이 줄어드는 경향을 나타냈다. 동평판재하시험결과, 2011년 개설임도 $E_{vd}$가 평균 $35.9MN/m^2$, 2014년은 평균 $31.1MN/m^2$, 2016년은 평균 $26.7MN/m^2$, 2017년은 평균 $23.7MN/m^2$로 2011년 개설임도가 가장 높은 $E_{vd}$를 나타냈다. 또한 성토 차륜부는 평균 $21.2MN/m^2$, 절토 차륜부는 평균 $36.71MN/m^2$ 그리고 중앙부는 평균 $29.8MN/m^2$로 절토 차륜부가 가장 높은 $E_{vd}$를 나타냈다.

• Korean Chemical Engineering Research
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• 제51권4호
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• pp.460-464
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• 2013

본 연구에서는 $LiMn_2O_4$ 제조에서 Mn 원료로 사용되는 CMD를 seed 첨가법을 사용하여 제조하고자 하였으며, Seed의 열처리 온도가 CMD 합성에 미치는 영향을 고찰하고, 그로부터 제조되는 $LiMn_2O_4$의 전기화학적 특성을 평가하고자 하였다. 제조한 시료의 물성평가는 X-선 회절 분석법(XRD), 주사전자현미경(SEM)을 통하여 실시하였다. 그 결과, $MnCO_3$를 $300^{\circ}C$ 이상의 온도에서 열처리하여 seed로 사용할 경우 ${\gamma}-MnO_2$ 상의 CMD가 얻어졌으며, 그 CMD를 LMO 제조에 사용할 경우 전기화학적 특성이 비교적 우수한 LMO가 얻어졌다.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.73-78
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• 2006

In this paper, creep tests of Mg-Zn-Mn and Mg-Zn-Mn-Ca alloys, which were casted by mold with Mg-3%Zn-1%Mn and Mg-3%Zn-1%Mn-0.2%Ca, were done under the temperature range of 473-573K and the stress range of 23.42-78.00Mpa. The activation energies and the stress exponents were measured to investigate the creep plastic deformation of those alloys, and the rupture lifes of Mg-Zn-Mn alloy were also measured to investigate the fracture behavior. From the results, the activation energy of Mg-Zn-Mn and Mg-Zn-Mn-Ca alloys under the temperature range of 473-493K were measured as 149.87, 145.98KJ/mol, respectively, and the stress exponent were measured as 5.13, 6.06 respectively. Also the activation energies Mg-Zn-Mn and Mg-Zn-Mn-Ca alloys under the temperature range of 553-573K were obtained as 134.41, 129.22KJ/mol, respectively, and tress exponent were obtained as 3.48, 4.63, respectively. Finally stress dependence of rupture life and the activation energy of rupture life of Mg-Zn-Mn under the temperature range of 473-493K was measured as 8.05, 170.0(KJ/mol), respectively, which were a little higher than the results of steady state creep.

• 전기학회논문지
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• 제60권4호
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• pp.801-804
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• 2011

Electrical properties and microstructure were investigated on the effects of $MnO_2$ and the lead-free $(Na_{0.44}K_{0.52}Li_{0.04})(Nb_{0.83}Sb_{0.07}Ta_{0.1})O_3$ ceramics with the addition of $MnO_2$ were fabricated by a conventional mixed oxide method. A gradual change in the crystal and microstructure was observed with the increase of $MnO_2$ addition. For the NKN-LST-xmol%$MnO_2$ sintered at $1100^{\circ}C$, bulk density increased with the addition of $MnO_2$ and showed maximum value at addition 1.0mol% of $MnO_2$. Curie temperature of the NKN-LST ceramics slightly decreased with adding $MnO_2$. The dielectric constant, piezoelectric constant ($d_{33}$) and electromechanical coupling factor ($k_p$) increased below 0.25mol% of $MnO_2$ addition, which might be due to the increase in density. The high piezoelectric properties = 145 pC/N, electromechanical coupling factor = 0.421 and dielectric constant = 2883 were obtained for the NKN-LST-0.25mol%$MnO_2$ sintered at $1100^{\circ}C$ for 4h.

• 한국자기학회지
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• 제10권3호
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• pp.139-142
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• 2000

이중 perovskite구조를 가진 전이금속 산화물 L $a_2$MnFe $O_{6}$ 기본 전자구조를 범밀도 함수법을 기초로 한 국소밀도 근사를 이용한 FLAPW방법으로 계산하였다. 여러 자성 구조의 전에너지 계산은 이 물질이 강자성 구조가 반강자성 구조보다 안정됨을 보여 주었다. 각 전이금속의 이온 상태는 자성 구조에 따라 달라짐을 보였다(강자성 $_Mn^{4+}$ , F $e^{2+}$ 준강자성 $_Mn^{3+}$ , F $e^{3+}$ ). 이것은 전이금속 사이의 초교환작용 이론으로 잘 설명되었고 계산 결과는 최근의 실험과 일치 하였다.

• 한국환경과학회지
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• 제18권4호
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• pp.445-450
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• 2009

In this study, the fundamental experiments were performed for catalytic oxidation of NO (50 ppm) on $MnO_2$ in the presence of ozone. The experiments were carried out at various catalytic temperatures ($30-120^{\circ}C$) and ozone concentrations (50-150 ppm) to investigate the behavior of NO oxidation. The honeycomb type $MnO_2$ catalyst was rectangular with a cell density of 300 cells per square inch. Due to $O_3$ injection, NO reacted with $O_3$ to form $NO_2$, which was adsorbed at the $MnO_2$ surface. The excessive ozone was decomposed to $O^*$ onto the $MnO_2$ catalyst bed, and then that $O^*$ was reacted with $NO_2$ to form $NO_3^-$. It was found that the optimal $O_3$/NO ratio for catalytic oxidation of NO on $MnO_2$ was 2.0, and the NO removal efficiency on $MnO_2$ was 83% at $30^{\circ}C$. As a result, NO was converted mainly to $NO_3^-$.

• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.49-54
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• 2020

We studied the electronic and magnetic properties for the Mn-doped chalcopyrite (CH) AlAs, GaAs, and AlGaAs₂ semiconductor by using the first-principles calculations. The chalcopyrite AlGaP₂, AlGaAsP, and AlGaAs₂ compounds have a semiconductor characters with a small band-gap. The interaction between Mn-3d and As-4p states at the Fermi level dominate rather than the other states. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the Mn(3d)-As(4p) strong coupling, which is attributed by the partially filled As-4p bands. The holes are mediated with keeping their 3d-electrons, therefore the ferromagnetic state is stabilized by this double-exchange mechanism. We noted that the ferromagnetic state with high magnetic moment is originated from the hybridized As(4p)-Mn(3d)-As(4p) interaction mediated by the holes-carrier.

• Journal of Magnetics
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• 제11권1호
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• pp.12-15
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• 2006

Magnetic and electronic properties of reduced rutile titanium dioxide $(TiO_{2-\delta})$ thin films doped by Mn have been investigated. The present sol-gel-grown semiconducting $TiO_{2-\delta}:Mn$ films exhibit a ferromagnetic behavior at room temperature for a limited range of Mn content. The Mn-doped films have p-type electrical conductivity with the carrier concentration near $10^{19}\;cm^{-3}$. The observed room-temperature ferromagnetism is believed to be intrinsic but not related to free carriers such as holes. Oxygen vacancies are likely to contribute to the room-temperature ferromagnetism-trapped carriers in oxygen vacancies can mediate a ferromagnetic coupling between neighboring $Mn^{+3}$ ions. The energy band-gap change due to the Mn doping measured by spectroscopic ellipsometry exhibits a red-shift compared to that of the undoped sample at low Mn content. It is explainable in terms of strong spin-exchange interactions between Mn ion and the carrier.

• 한국물환경학회지
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• 제26권3호
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• pp.454-459
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• 2010

This study investigated the applicability of manganese coated media such as manganese coated sand (MCS), manganese coated sericite (MCSe) and manganese coated starfish material calcined at $550^{\circ}C$ (MCSf) to remove Mn(II) in synthetic wastewater. Manganese coated media prepared at different pH was applied in the treatment of soluble Mn(II) in batch and column experiments at various Mn(II) concentrations. The amount of Mn coated on three different media was approximately 800~1100 mg/kg. From the stability test, negligible dissolution of Mn was observed above pH 3.0. In batch test, more than 40% of Mn(II) was removed by all sand media at various manganese concentrations. In order to see the effect of additional oxidant for the removal of Mn(II), 4 mg/L of hypochlorite was added in Mn(II) solution during column experiment. Breakthrough of Mn(II) was greatly retarded in the presence of hypochlorite in all column reactors packed with different media. Among the manganese coated media, MCSf prepared at pH 4 indicated the highest removal capacity. The removal efficiency of Mn(II) was also increased in the multi-layer system (0.5 g of MCS, MCSe, and MCSf each).

• Journal of Magnetics
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• 제19권3호
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• pp.205-209
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• 2014

$MnBi_{1-x}Ti_x$ (x = 0, 0.4, 0.7, 1) alloys were prepared by arc-melting, followed by heat treatment. X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) were used to measure and investigate the phase structure and magnetic properties. The temperature dependent magnetization curves indicate that the phase transitions between LTP and HTP MnBi occur with heating or cooling in $MnBi_{1-x}Ti_x$ ($x{\leq}0.7$) samples. However, MnTi samples are in $Mn_2Ti$ single-phase, with very low magnetic properties. Furthermore, the coercivity exhibits a positive temperature coefficient. The results show that the optimal content of Ti for the coercivity of $MnBi_{1-x}Ti_x$ alloy is x = 0.4. For MnBi sample, the coercivity reaches a maximum value of 1.13 T at 550 K. However, the remanence and energy product show apparent decrease with the addition of Ti in $MnBi_{1-x}Ti_x$ alloys.