• Journal of Powder Materials
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• v.21 no.4
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• pp.294-300
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• 2014

The connecting rod is one of the most important parts in automotive engines, transforming the reciprocal motion of a piston generated by internal combustion into the rotational motion of a crankshaft. Recent advances in high performance automobile engines demand corresponding technological breakthroughs in the materials for engine parts. In the present research, the powder metallurgy (P/M) process was used to replace conventional quenching and/or tempering processes for mass production and ultimately for more cost-efficient manufacturing of high strength connecting rods. The development of P/M alloy powder was undertaken not only to achieve the improvement in mechanical properties, but also to enhance the machinability of the P/M processed connecting rods. Specifically $MoS_2$ powders were added as lubricants to non-normalizing Fe-Cr-Mn-V-C alloy powder to improve the post-sintering machinability. The effects of $MoS_2$ addition on the microstructure, mechanical properties, and machining characteristics were investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.282.1-282.1
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• 2016

The remarkable physical properties of two-dimensional (2D) semiconducting materials such as molybdenum disulfide ($MoS_2$) and tungsten disulfide ($WS_2$) etc. have attracted considerable attentions for future high-performance electronic and optoelectronic devices. The ongoing studies of $MoS_2$ based nonvolatile memories have been demonstrated by worldwide researchers. The opening hysteresis in transfer characteristics have been revealed by different charge confining layer, for instance, few-layer graphene, $MoS_2$, metallic nanocrystal, hafnium oxide, and guanine. However, limited works built their nonvolatile memories using entirely of assembled 2D crystals. This is important in aspect view of large-scale manufacture and vertical integration for future memory device engineering. We report $WS_2$ based nonvolatile memories utilizing functional van der Waals heterostructure in which multi-layered graphene is encapsulated between $SiO_2$ and hexagonal boron nitride (hBN). We experimentally observed that, large memory window (20 V) allows to reveal high on-/off-state ratio (>$10^3$). Moreover, the devices manifest perfect retention of 13% charge loss after 10 years due to large graphene/hBN barrier height. Interestingly, the performance of our memories is drastically better than ever published work related to $MoS_2$ and black phosphorus flash memory technology.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.4
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• pp.378-384
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• 1997

The ruminal solubility of copper (Cu), manganese (Mn), molybdenum (Mo), and zinc (Zn) in eight Philippine forages was studied. These forages were: 1) grasses: paragrass (Brachiaria mutica (Forsk.) Stapf), stargrass (Cynodon plectostachyum Pilger), and napiergrass (Pennisetum purpureum Schumach.); 2) creeping legumes: calopogonium or calopo (Calopogonium muconoides Desv.) and centrocema (Centrocema pubescens Benth.); 3) tree lequmes: gliricidia or kakawate (Gliricidia sepium (Jacq.) Walp.), leucaena or ipil-ipil (Leucaena leucocephala (Lam.) de Wit.), and sesbania or katuray (Sesbania grandiflora (L.) Poir). Nylon bags with samples were incubated for 0, 3, 6, 12, 24, 48 and 72h in three rumen cannulated sheep fed with timothy hay (Phleum pratense L.) at 2% body weight/d. The 0-h bags were washed with deionized water. There were species differences (p < 0.05) on the different solubilities of trace elements. At O-h incubation, the trend of solubility was Mo (54%) > Zn (43%) > Cu (38.7%) > Mn (29.5%). At 3-h incubation, all the elements except Mn had an average solubility above 50%. Combining particulate passage rate (1.9%/h) and various trace elements disappearance rates, the effective ruminal solubilization (ERS) of trace elements were computed. The ERS across species ranged from 44.6 to 89.9% for Cu, 29.9 to 84% for Mn, 66 to 95.1% for Mo, and 30.1 to 82.3% for Zn resulting to a trend of Mo > Zn > Cu > Mn.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.715-720
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• 2006

Metalhydrides such as $Cp(CO)_{2}(L)MH$ (L = t-butylisocyanide and 2,6-dimethylphenylisocyanide M = Mo and W) have been synthesized and used for ionic hydrogenation of the carbonyl groups in the presence of triflic acid. When these complexes have also used as catalyst precursors for hydrogenation of 3-pentanone under mild conditions ($23^{\circ}C,\;<4.1\;atm H_{2}$). The turnover rates were very slow, with the fastest initial rate of about 2 turnovers per 1 day for the [$Cp(CO)_{2}(ArNC)Mo][BA_{r}^{F}_{4}$] system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.63-66
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• 2002

Bi-layer Mo films were deposited on sodalime glass substrates using DC magnetron sputtering. As the gas pressure and power density, the resistivity varied from $1.5{\times}10^{-5}$ to $4.97{\times}10^{-4}{\Omega}{\cdot}cm$. Furthermore, stress direction yielded compressive-to-tensile transition stress curves. The microstructure of the compressive stress films which had poor adhesion consists of tightly packed columns, but of the tensile-stressed films had less dense structure. Under all gas pressure conditions, Mo films exhibited distinctly increasing optical reflection with decreasing gas pressure. The expansion of (110) peak width with the gas pressure meant the worse crystalline growth. Also, The highest efficiency was 15.2% on 0.2 $cm^2$. The fill factor, open circuit voltage and short circuit current were 63 %, 570 m V and 42.6 $mA/cm^2$ respectively.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.477-477
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• 1989

The rates of the reaction of $[MoO_2(S_2CNEt_2)_2]$ with triphenylphosphine in 1,2-dichloroethane have been determined by the spectrophotometric method. The increase in the initial absorbance has been interpreted as a result of the production of $[Mo_2O_3(S_2CNEt_2)_4]$ and the decrease in absorbance then corresponds to the reduction of $[M_2O_3(S_2CNEt_2)_4]$. The data suggest mechanisms involving the enzymatic reaction in the first stage and the decay of intermediate, ${\mu}$-oxo molybdenum (V) dimer in the second stage.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1161-1162
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• 2006

In order to overcome the recrystallization embrittlement and irradiation embrittlement of Mo, which are major problems for its fusion applications, internally nitrided Mo alloys were prepared by a novel multi-step internal nitriding. Neutron irradiation was performed in the Japan Material Testing Reactor (JMTR). After irradiation, nitrided Mo alloys exhibited $\iota$ ower ductile-brittle transition temperature than irradiated TZM. These results suggested that multi-step internal nitriding was effective to the improvement in the embrittlement by irradiation. Transmission electron microscope observation revealed that TiN particles precipitated by nitriding acted as a sink for irradiation-induced defects.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.443-448
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• 1996

In order to plasma-sulfnitride by combining ion-nitriding of a steel and sputtering of MoS$_2$, chromium-molybdenum steel was plasma-sulfritrided using hollow cathode discharge with parallel electrodes which are a main of the steel and a subsidiary cathode of $MoS_2$. The treatment was carried out at 823K for 10.8ks under 665Pa in a 30% $N_2$-70% $H_2$ gas atmosphere. Plasma-sulfnitriding layers formed of the steel were characterized with EDX, XRD, micrographic structure observation and hardness measurement. A compound layer of 8-15$\mu\textrm{m}$ and nitrogen diffusion layer of about 400$\mu\textrm{m}$ were formed on the surface of plasma-sulfnitrided steel. The compound layer consisted of FeS containing Mo and iron nitrides. The nitrides of $\varepsilon$-$Fe_2_3N$ and $\gamma$'-$Fe_4N$ formed under the FeS. The thickness of compound layer and surface hardness were different with the gaps between main and subsidiary cathodes even in the same sulfnitriding temperature. The surface hardnesses after plasma-sulfnitriding were distributed from 640 to 830Hv. The surface hardness was higher in the plasma-sulfnitriding than the usual sulfnitriding in molten salt. This may be due to Mo in sulfnitriding layer.

• Korean Journal of Metals and Materials
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• v.49 no.11
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• pp.868-873
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• 2011

In this study, the fabrication of ultra fine grained Mo bulk was conducted. $MoO_3$ nanopowders were prepared by a high energy ball-milling process and then reduced at the temperature of $800^{\circ}C$ without holding time in $H_2$ atmosphere. The particle size of Mo nanopowder was ~150 nm and grain size was ~40 nm. The two-step process was employed for the sintering of Mo nanopowder to obtain fine grain size. The densification over 90% could be obtained by the two-step sintering with a grain size of less than 660 nm. For higher density, modified two-step sintering was designed. 95% of theoretical density with the grain size of 730 nm was obtained by the modified two-step sintering.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.222.2-222.2
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• 2016

트랜지스터 응용 등에 관한 연구가 활발해 지면서 에너지 밴드갭이 0 eV에 가까운 그래핀 이외의 밴드 갭 조절이 가능한 MoS2 (molybdenum disulfide), BN (boron nitride), Bi2Te3 (bismuth telluride), WS2 (tungsten disulfide) 등과 같은 이차원 Transition Metal DiChalcogenides (TMDC) 물질이 반도체 물질로 각광받고 있다. 특히 MoS2의 경우 단결정 덩어리 상태에서는 약 1.3 eV의 밴드갭을 가지나 두께가 줄어들어 두 층일 경우에는 약 1.65 eV, 단일층이 되면 약 1.9 eV의 밴드갭을 가져 박막 층수에 따라 에너지 밴드갭 조절이 가능한 것으로 알려져있다. 하지만 두께 조절이 가능하면서 대면적, 고품질을 가지는 MoS2 박막 합성은 아직 제한적이라 할 수 있으며 새로운 방법 및 물질에 대한 연구가 지속적으로 이루어 지고 있다. 따라서 본 연구에서는 다양한 층수를 지니는 MoS2 합성을 위해 나노 두께의 MoS2 박막을 CF4 plasma 를 이용하여 layer etching 진행하고 CF4 plasma 100초 etching 진행한 2 layer 두께의 MoS2를 기준으로 H2S plasma를 이용하여 treatment 진행하였다. 물리적, 화학적 분석은 Raman spectroscopy, XPS(X-ray Photoelectron Spectroscopy), AFM (Atomic Force Microscopy) 등을 이용해 진행하였고 이를 통해 MoS2 layer 감소 및 damage recovery 등을 확인하였다.