재활 및 복지

임도형(Dohyung Lim) 한국재활복지공학회 2016 한국재활복지공학회 학술대회논문집 Vol.2016 No.11

고령친화기기산업 및 주요 고령친화기기 개발 동향

임도형(Dohyung Lim) 한국재활복지공학회 2010 한국재활복지공학회 학술대회논문집 Vol.2010 No.11

고령친화산업의 현황 및 정책 방향에 대해 간략히 소개하고 한국생산기술연구원 실버기술개발단에서 현재 연구?개발하고 있는 주요 고령친화기기에 대하여 간략히 소개하고자 한다.

Phase transition of Fe₂O₃–NiO to NiFe₂O₄ in perovskite catalytic particles for enhanced methane chemical looping reforming-decomposition with CO₂ conversion

Lim, Hyun Suk,Kang, Dohyung,Lee, Jae W. Elsevier 2017 Applied Catalysis B Vol.202 No.-

<P><B>Abstract</B></P> <P>This work introduced a perovskite catalytic particle of Fe<SUB>2</SUB>O<SUB>3</SUB>–NiO/La<SUB>0.8</SUB>Sr<SUB>0.2</SUB>FeO<SUB>3</SUB> as an oxygen carrier and investigated its long-term activity and stability in a novel methane Chemical Looping Reforming-Decomposition (CLRD) process. Carbon dioxide (CO<SUB>2</SUB>) was injected for the oxidation of the reduced catalytic particle and its carbon deposit, resulting in the accelerated production of syngas. The catalytic particle showed over 97% of CH<SUB>4</SUB> conversion over 60min and the reduced catalytic particle was partially re-oxidized by both O<SUB>2</SUB> and CO<SUB>2</SUB> with the conversion of CO<SUB>2</SUB> into CO maintaining about 93% over 80min. The separate phases of Fe<SUB>2</SUB>O<SUB>3</SUB>/NiO were gradually merged to the single crystal phase of NiFe<SUB>2</SUB>O<SUB>4</SUB> during the calcination of the two metal oxides and the continuous redox reaction cycle. The increased crystallinity can lead to the improvement of both activity and stability due to the enhanced oxygen-carrying capacity. The structure of the catalytic particle was well preserved and its activity has been stable in the long-term CLRD cycle with the combination of CO<SUB>2</SUB> utilization.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Perovskite particle of Fe<SUB>2</SUB>O<SUB>3</SUB>–NiO/La<SUB>0.8</SUB>Sr<SUB>0.2</SUB>FeO<SUB>3</SUB> is proposed as an oxygen carrier. </LI> <LI> Transition of mixed Fe<SUB>2</SUB>O<SUB>3</SUB>–NiO oxides to single NiFe<SUB>2</SUB>O<SUB>4</SUB> enhances syngas yields. </LI> <LI> Reinforced carrier activity and stability over repeated cycles are firstly reported. </LI> <LI> Enabling a looping process of CH<SUB>4</SUB> reforming-decomposition with CO<SUB>2</SUB> conversion. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Calculation of the local electric field for an infinite array of conducting nanosized objects

Lim, Mikyoung,Kim, Dohyung,Kim, Sang Youl,Bouré,e, Jean-Eric The Institute of Physics 2007 JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL Vol.40 No.4

<P>The electric field for an infinite array of conducting nanosized objects in two-dimensional space has been calculated. The mirror symmetry for this physical problem has been introduced. By taking into account this symmetry, we transform the original problem into an infinite two-dimensional array of nanosized objects with the same solution. The electric field equation of the model has been successfully constructed using a single-layer potential of the periodic Green function. The electric field operator has been introduced. This mathematical approach yields a solution for determining the optimum structure of nanosized electronic devices such as carbon nanotube-based field emitters.</P>

Role of transition metal in perovskites for enhancing selectivity of methane to syngas

Lim, Hyun Suk,Lee, Minbeom,Kang, Dohyung,Lee, Jae W. Elsevier 2018 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.43 No.45

<P><B>Abstract</B></P> <P>This work investigates the role of transition metal at the B-site of ABO<SUB>3</SUB>–type perovskite that affects the lattice oxygen transfer for the partial oxidation of methane. Two types, LaBO<SUB>3</SUB> and La<SUB>0.6</SUB>Ca<SUB>0.4</SUB>BO<SUB>3</SUB> (B = Fe, Mn, Co), were synthesized and investigated under repeated redox cycles. The Fe-based perovskite had a high tendency of partial oxidation, while the Co-based perovskite mainly led to the full oxidation of methane. The Co-based perovskite was enriched with the surface oxygen component due to the enhanced oxygen transfer from the lattice to the surface vacant site. On the other hand, the Fe-based perovskite showed a relatively low lattice oxygen transfer to the surface oxygen vacancy although it had the highest lattice oxygen ratio among the different B-site perovskites. The selectivity and the production amount of the syngas were improved when the amount of the surface oxygen was controlled by adjusting the re-oxidation extent of the carriers during the oxidation step. Through these experiments, La<SUB>0.6</SUB>Ca<SUB>0.4</SUB>FeO<SUB>3</SUB>, which showed the highest syngas productivity with utilizing earth-abundant metals, was selected as an optimal oxygen carrier for methane reforming.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Lattice oxygen transfer to surface mainly determines the oxidation degree of CH<SUB>4</SUB>. </LI> <LI> Fe-based perovskites are suitable for the syngas production. </LI> <LI> Co-based perovskites prefer the full oxidation of CH<SUB>4</SUB>. </LI> <LI> La<SUB>0.6</SUB>Ca<SUB>0.4</SUB>FeO<SUB>3</SUB> shows the highest syngas productivity for 20 cycles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced catalytic activity of methane dry reforming by the confinement of Ni nanoparticles into mesoporous silica

Kang, Dohyung,Lim, Hyun Suk,Lee, Jae W. Pergamon Press 2017 International journal of hydrogen energy Vol.42 No.16

<P><B>Abstract</B></P> <P>Nickel nanoparticles were immobilized in mesoporous silica by a polyethyleneimine (PEI)-aided route and their catalytic performance was evaluated in dry reforming of methane. NH<SUB>2</SUB> terminal groups of PEI strongly interacted with surface silanol groups of mesoporous silica and then, Ni-chelating PEIs were highly dispersed inside its ordered channel. The steric hindrance of PEI with a long hydrocarbon chain also restricted the aggregation of Ni-PEI complexes anchored in the porous framework. The catalysts prepared by the PEI-aided route showed the stable activity at 750 °C for 40 h because Ni particles were confined inside the pore and therefore, cannot be sintered more than the pore diameter of their parent support. The carbon deposit is much smaller in the catalyst prepared by the PEI-aided route than the reference catalyst synthesized via a traditional impregnation method, suggesting that the sintering of Ni particles is a main contribution to the generation of graphitic carbon.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ni nanoparticles were confined in a mesoporous silica through PEI grafting. </LI> <LI> Interaction between PEI NH<SUB>2</SUB> and silica silanol groups caused an even dispersion of Ni. </LI> <LI> PEI steric hindrance prevented the aggregation of Ni nanoparticles. </LI> <LI> Pore-expanded mesoporous silica facilitated the incorporation of Ni nanoparticles. </LI> <LI> Carbon deposits were greatly reduced due to the pore confinement of Ni nanoparticles. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Syngas production on a Ni-enhanced Fe₂O₃/Al₂O₃ oxygen carrier via chemical looping partial oxidation with dry reforming of methane

Kang, Dohyung,Lim, Hyun Suk,Lee, Minbeom,Lee, Jae W. Elsevier 2018 APPLIED ENERGY Vol.211 No.-

<P><B>Abstract</B></P> <P>A novel chemical looping process was introduced by combining partial oxidation and dry reforming of methane on a cost-effective iron-based oxygen carrier to produce high-purity syngas with a H<SUB>2</SUB>/CO ratio of 2. The rationale for the proposed chemical looping process was substantiated with the thermodynamic data, which showed increased syngas purity and an H<SUB>2</SUB>/CO ratio close to 2 by introducing the CH<SUB>4</SUB>-CO<SUB>2</SUB> mixture feed. Compared with the general chemical looping process, the calculated carbon deposition with the CO<SUB>2</SUB> emission of the proposed process was dramatically decreased by using CO<SUB>2</SUB> as a co-feed with CH<SUB>4</SUB>. Due to the exothermic heat from the oxidation reaction of the oxygen carrier, the net heat duty of the novel chemical looping process was much lower than that of the dry reforming process. To validate the thermodynamic results, a Ni entrapped Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> oxygen carrier was synthesized by increasing the metal-support interaction through a sol-gel route. It is striking that the formation of Ni aluminate phase in the Ni-reinforced oxygen carrier facilitated dry reforming with partial oxidation while suppressing methane decomposition. By supplying a nonstoichiometric CH<SUB>4</SUB>-CO<SUB>2</SUB> mixture feed (CO<SUB>2</SUB>/CH<SUB>4</SUB> ratio = 0.38) to the 1 wt% Ni-entrapped Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> oxygen carrier at 900 °C, an H<SUB>2</SUB>/CO ratio of 2.09 and high CO selectivity of 96.76% were achieved with minimized carbon deposition. These results were close to the calculated equilibrium value while a Ni-impregnated Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> oxygen carrier showed an increased H<SUB>2</SUB>/CO ratio of 2.36 with severe carbon deposition by the promoted methane decomposition. In addition, the Ni-reinforced oxygen carrier also showed stable redox activity during successive reduction and oxidation cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CLPD was derived by merging dry reforming into chemical looping partial oxidation. </LI> <LI> Results of CLPD were calculated using the ASPEN Plus simulator. </LI> <LI> Syngas with a H<SUB>2</SUB>/CO ratio of 2 was produced through the CLPD process. </LI> <LI> Ni-enhanced Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> showed the enhanced CLPD activity without rare earth metals. </LI> <LI> Stabilized Ni in Al<SUB>2</SUB>O<SUB>3</SUB> promoted dry reforming with suppressed carbon deposition. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

전이성 골암으로 인한 골질 변화와 이로 인한 골절 위험성 분석

임도형,Lim, Dohyung 대한의용생체공학회 2012 의공학회지 Vol.33 No.4

While much has been learned about the mechanisms of metastatic spread of cancer to bone, there has been little headway in establishing guidelines for monitoring the alteration in bone quality and estimating fracture risk. The aims of this study are, therefore, 1) to evaluate bone quality induced by metastatic bone tumor by analyzing the characteristics on bone microarchitecture and degree of bone mineralization and 2) analyze fracture risk increased secondary to the bone quality changes by metastatic bone tumor through calculating mechanical rigidities based on in-vivo micro CT images. For this study, eighteen female SD rats (12 weeks old, approximate 250 g) were randomly allocated in Sham and Tumor groups. W256 (Walker carcinosarcoma 256 malignant breast cancer cell) was inoculated in the right femur (intraosseous injection) in Tumor group, while 0.9% NaCl (saline solution) was injected in Sham group. The right hind limbs of all rats were scanned by in-vivo micro-CT to acquire structural parameters and degree of bone mineralization at 0 week, 4 weeks, 8 weeks, and 12 weeks after surgery. At the same time, urine was collected by metabolic cages for a biochemical marker test in order to evaluate bone resorption. Then, bone metastasis had been directly identified by positron emission tomography. Finally, axial, bending and torsional rigidities had been calculated based on in-vivo micro CT images for predict fracture risk. The results of this study showed that metastatic bone tumor might induce significant decrease in bone quality and increase of fracture risk. This study may be helpful to monitoring a degree of bone metastasis and predicting fracture risk due to metastatic bone tumor. In addition, this noninvasive diagnostic methodology may be utilized for evaluating other bone metabolic diseases such as osteoporosis.

Chemical looping partial oxidation of methane with CO₂ utilization on the ceria-enhanced mesoporous Fe₂O₃ oxygen carrier

Kang, Dohyung,Lee, Minbeom,Lim, Hyun Suk,Lee, Jae W. Elsevier Ltd 2018 Fuel Vol.215 No.-

<P><B>Abstract</B></P> <P>The high-purity syngas production with a molar ratio of H<SUB>2</SUB> to CO equal to 2 was achieved through a chemical looping process with a CH<SUB>4</SUB>-CO<SUB>2</SUB> feed mixture on a ceria-enhanced mesoporous Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> oxygen carrier. The presence of CO<SUB>2</SUB> in the mixture feed enables the H<SUB>2</SUB>/CO ratio to be maintained as 2 desirable for the syngas-to-liquid hydrocarbon process by suppressing the methane decomposition even when the amount of reducible oxygen carrier was sufficiently small. By incorporating a small amount of CeO<SUB>2</SUB> (molar Ce/Fe ratio = 0.15) to the iron oxide mesoporous oxygen carrier by the sol-gel method, the syngas selectivity also increased although the amount of reducible oxygen was large enough to cause the total combustion. Due to the co-feeding of CO<SUB>2</SUB> with CH<SUB>4</SUB> and the textural property of the ceria-enhanced Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> mesoporous oxygen carrier, the enhanced redox activity for the chemical looping process was demonstrated under the CO<SUB>2</SUB>/CH<SUB>4</SUB> feed ratio of 0.28 with the redox performance of CH<SUB>4</SUB> conversion = 93.11%, CO selectivity = 93.23%, average carbon deposit = 0.048 mol<SUB>C</SUB>/mol<SUB>syngas</SUB>, and average H<SUB>2</SUB>/CO ratio = 2.04. The fluctuation of the H<SUB>2</SUB>/CO ratio with the reaction time was minimized by adjusting the real-time CO<SUB>2</SUB>/CH<SUB>4</SUB> feed ratio and then, the consistent syngas production was realized even in the fixed bed chemical looping process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ceria-induced mesoporous Fe<SUB>2</SUB>O<SUB>3</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB> (Ce/Fe = 0.15) showed the superior redox activity. </LI> <LI> The <I>meso</I>-porosity was derived from the merge of ceria into the Al<SUB>2</SUB>O<SUB>3</SUB> matrix. </LI> <LI> CO<SUB>2</SUB> was utilized as a co-feed with CH<SUB>4</SUB> in chemical looping process. </LI> <LI> Fluctuation of produced H<SUB>2</SUB>/CO ratio was minimized by adjusting CO<SUB>2</SUB>/CH<SUB>4</SUB> feed ratio. </LI> <LI> High-purity syngas with H<SUB>2</SUB>/CO ratio of 2 was produced via chemical looping process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Residue-Free Silver Nano Patterns Fabricated by Reverse Direct Imprinting

Kim, Dohyung,Gil, Youngin,Choi, Moon Suk,Lim, Donghwan,Yoo, Gwangwee,Park, Jin-Hong,Choi, Changhwan American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.12

<P>In this work, we fabricated residue-free nanoscale structures with silver nanoparticles (AgNPs) using reverse direct nanoimprinting lithography (NIL) without the need for additional reactive-ion etching (RIE). The nanohole and line patterns without polymer residues were achieved by modulating the baking temperature for solvent evaporation, the imprinting pressure, and the temperature of the thermal NIL. Moreover, with sintering at 180 degrees C for 30 minutes, the resistivity of the AgNP nanostructure was reduced to 4.88*10(-6) cm-Q, comparable to that of bulk Ag, attributable to a reduction in surface resistance without agglomeration and pattern shrinkage. Our results indicate that controlling NIL temperature, pressure, and sintering temperature are critical to attaining residue-free metal layers with acceptable resistivity that are adaptable for various nanostructures.</P>