• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 추계 학술발표회 논문집
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• pp.191-194
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• 2002

매체 순환식 연소(Chemical-Looping Combustion, CLC)는 금속 산화물(산소공여매체, oxygen carrier)의 산소를 이용하여 화석연료를 산화(연료 연소 공정)시키고, 환원된 금속을 다시 산화(매체 산화 공정)시키는 간접적인 연소 공정의 하나이다. 이 방식은 온실효과의 주발생원인 $CO_2$를 원천적으로 회수할 수 있고, 또한 화염이 없는 상태에서 연소반응이 진행됨으로 thermal NOx의 발생을 미연에 방지할 수 있어 고효율의 환경친화적인 연소공정이다.(중략)

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.884-894
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• 2011

Effects of temperature, volatile content, particle diameter and solid input weight were investigated in the batch fluidized bed reactor using OCN703-1100 particle as oxygen carrier and Roto coal and char as fuels. Two solid fuels represented the best reactivity at different temperature, $900^{\circ}C$ for Roto coal and $950^{\circ}C$ for char, respectively. However, we selected $900^{\circ}C$ as the best operating temperature because the improvement of reactivity of char at $950^{\circ}C$ was negligible. Char represented better reactivity than Roto coal because char contains low volatile than Roto coal. For both solid fuels, reactivities were improved with increasing of the particle diameter. These results were explained by solid mixing tests in a transparent fluidized bed using two char particles having different particle size ranges and OCN703-1100 particle. The bigger particle showed better solid mixing with OCN703-1100 particle, and therefore, represented better reactivity. For both solid fuels, reactivities were improved with increasing of the solid input weight within the experimental conditions of this study because the weight of coarse particles increased with the solid input weight increased, and therefore, these coarse particles can mix well with the oxygen carrier.

• Korean Chemical Engineering Research
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• 제54권3호
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• pp.394-403
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• 2016

매체 순환식 수소제조공정은 직접 고순도의 수소를 생산하는 동시에 $CO_2$ 포집 비용을 최소화할 수 있는 고효율/친환경적인 공정이다. 본 공정은 레독스 반응을 통하여 산소를 전달하고 이때 철 산화물계 산소전달입자를 이용하게 된다. 구리 산화물이 첨가된 철-구리 산화물계 산소전달입자는 반응성 향상이 보고되어 왔으나 철 산화물과 구리 산화물 간 상호작용에 대한 이해가 부족한 실정이다. 본 연구에서는 여러 기기 분석법(SEM/EDX, XRD, BET, TPR, XPS, TGA)을 통하여 철-구리 산화물계 산소전달입자의 레독스 반응성 향상을 지배하는 주요인을 연구하였다. 첨가된 구리 산화물은 철 산화물 성장 억제제 역할 뿐만 아니라 화학적 환경 변화를 일으키는 화학적 촉매제(chemical promoter) 역할도 하는 것이 발견되었다. 철-구리 산화물계 산소전달입자의 우수한 환원 반응성은 구리 산화물의 도입으로 $Fe^{2+}$ 농도 증가 및 표면 특성 변화 때문이며, 우수한 물분해 특성은 산화 과정에서 일어나는 철 산화물의 응집을 구리 산화물이 억제시킨 것으로 판단되었다.

• 청정기술
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• 제30권2호
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• pp.71-93
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• 2024

최근, 무탄소 에너지원(특히, 선박 및 혼소 발전), 고효율 청정 수소 저장 및 매개체로써 암모니아가 다시 각광받고 있다. 암모니아는 화학공학에서 매우 중요한 공정 중 하나인 Haber-Bosch 공정을 통해 합성할 수 있지만, 이 공정은 에너지 소비량이 높고 탄소 배출량 역시 높아, 기존 공정을 통해 암모니아를 합성할 시 탄소 저감 효과가 미미하다. 이러한 기존 공정의 치명적인 단점을 해결하기 위해 최근, 높은 에너지 효율로 탄소 배출이 적게 암모니아를 합성할 수 있는 열화학적 합성 방법이 많이 개발되고 있다. 소재측면에서는 기존 공정보다 완화된 공정 조건에서도 충분히 높은 암모니아 합성 성능을 보일 수 있는 고성능 촉매 소재를 개발하는 연구가 진행되고 있으며, 공정측면에서는 매체 순환식(chemical-looping) 합성 방법, 플라즈마 합성방법, 기계화학적 합성 방식 등 다양하게 적용되고 있다. 이번 총설에서는 최근 청정수소 저장을 효과적으로 저장하기 위해 어떤 암모니아 합성 기술들이 개발되고 있는지 자세히 소개하고자 한다.

• 한국수소및신에너지학회논문집
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• 제23권1호
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• pp.83-92
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• 2012

Syngas combustion characteristics of mass produced oxygen carrier particle (OCN706-1100) were investigated in a pressurized fluidized bed reactor using simulated syngas and air as reactants for reduction and oxidation, respectively. The oxygen carrier showed high fuel conversion, high $CO_2$ selectivity, and low CO concentration at reduction conditions and no NO emission at oxidation conditions. Moreover, OCN706-1100 particle showed good regeneration ability during successive reduction-oxidation cyclic tests up to the 10th cycle. Fuel conversion and $CO_2$ selectivity decreased and CO emission increased as temperature increased. These results can be explained by trend of calculated equilibrium CO concentration with temperature. However, fuel conversion and $CO_2$ selectivity increased and CO emission decreased as pressure and gas residence time increased.

• 한국수소및신에너지학회논문집
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• 제23권2호
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• pp.173-182
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• 2012

Effects of temperature, pressure, and gas residence time on methane combustion characteristics of mass produced oxygen carrier particle (OCN706-1100) were investigated in a pressurized fluidized bed reactor using methane and air as reactants for reduction and oxidation, respectively. The oxygen carrier showed high fuel conversion, high $CO_2$ selectivity, and low CO concentration at reduction condition and very low NO emission at oxidation condition. Moreover OCN706-1100 particle showed good regeneration ability during successive reduction-oxidation cyclic tests up to the 10th cycle. Fuel conversion and $CO_2$ selectivity decreased and CO emission increased as temperature increased. These results can be explained by trend of calculated equilibrium CO concentration. However, $CO_2$ selectivity increased as pressure increased and fuel conversion increased as gas residence time increased.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.147-154
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• 2016

Co-nonsolvency is a puzzling phenomenon that a polymer swells in a good solvent individually, but it collapses in a mixture of good solvents. This structural transition with changing solvent environment has been drawing attention due to practical application for stimuli-responsive polymer. The aim of this work is to describe the physical origin of the co-nonsolvency. In this work, we present Monte Carlo simulations for polymer solutions by using simple and general model. We simulate linear and ring polymers to compare their co-nonsolvency behaviors. Calculating Flory exponents and bridging fractions gives a good description for polymer structures. While the polymer structure shows non-monotonous behavior with increasing the cosolvent fraction, the chemical potential decreases monotonously. This indicates that coil-to-globule transition of polymers is purely controlled by free energy and can be regarded as a thermodynamics transition. We also present that ring polymers have higher looping probability than linear polymers, thus the bridging fraction remains higher at high cosolvent fraction. Our study provides a new perspective to understand polymer structure when the polymer "dissolves well" in any solvent.

• 한국수소및신에너지학회논문집
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• 제27권4호
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• pp.412-420
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• 2016

Effect of $H_2S$ on reactivity of oxygen carrier was measured and discussed using fluidized bed reactor and SDN70 oxygen carrier. We could get 100% of fuel conversion and $CO_2$ selectivity even though $H_2S$ containing simulated syngas was used as fuel for reduction. Absorbed sulfur was released during oxidation and $N_2$ purge step after oxidation as $SO_2$ form. We could get 100% of fuel conversion and $CO_2$ selectivity during cyclic reduction-oxidation tests up to 10th cycle. However, only 6~7% of sulfur can be removed during oxidation and $N_2$ purge step and 93~94% of sulfur was accumulated in the oxygen carrier. Therefore we could conclude that total removal of sulfur was not possible. $SO_2$ emission during oxidation decreased as the number of cycle increased. Therefore we could expect that the reactivity of oxygen carrier will be decreased with time.

• 한국수소및신에너지학회논문집
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• 제25권1호
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• pp.87-96
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• 2014

Direct combustion characteristics of coal and oxygen carrier were measured in the thermogravimetric analyzer using four coals and two different oxygen carriers. The direct combustion efficiency decreased in order of Roto, Kideco, Sunhwa and Hyper coal for both oxygen carriers. Moreover, OCN703-1100 oxygen carrier showed better combustion efficiency than OCN706-1100 oxygen carrier for all four coals. The reduction characteristics of two oxygen carriers for $CH_4$, CO and $H_2$ gases were measured in the thermogravimetric analyzer to investigate why OCN703-1100 oxygen carrier showed better combustion efficiency than OCN706-1100 for all coals. The OCN703-1100 oxygen carrier represented higher reduction rate than OCN706-1100 for all reducing gases. Moreover, the total pore area and the porosity of OCN703-1100 were higher than those of OCN706-1100 oxygen carrier. The total volatile gas and volatile components of four coals were measured in a batch type fluidized bed reactor to investigate why the direct combustion efficiency decreased in order of Roto, Kideco, Sunhwa and Hyper coal for both oxygen carriers. The direct combustion efficiency was proportional to the total amount of ($CH_4+CO+H_2$) produced during devolatilization of coals.

• 한국의상디자인학회지
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• 제16권4호
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• pp.117-136
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• 2014

The purpose of this study is to present a classification system of the hand-made and machine-made lace according to the configuration method and re-make the category and definition of lace to consider the emergence and development of major laces techniques. The re-made category and definition of the lace is as follows. The lace usually consists of ground and motifs, however, the techniques of netting and sprang are suitable for making ground than motif, so I think it is appropriate to exclude them from the category of the lace. Many scholars are excluded openwork embroidery fabric from the category of the lace. But, an openwork embroidery fabric is the basis of a needle point lace called true lace and is consist of motif and ground. I think it is appropriate to include it in the category of the lace. I think it is also appropriate to include in the category of the lace that the eyelet embroidery fabric which mimics the openwork embroidery fabric in the machine. Lace is redefined that a fabric with openwork decoration consists of motif and ground, constructed by a variety of ways such as plaiting, twisting, looping, knotting of threads or embroidering by hand or machine. The classification of the lace is presented as follows. Hand-made lace is classified bobbin lace, needle point lace, embroidery lace, knotted lace, crochet lace, and knitting lace. Machine-made lace is classified raschel lace, leaver lace, torchon lace, and machine-made embroidery laces which include tool lace, eyelet embroidery lace, chemical lace, etc.