• Clean Technology
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• v.16 no.3
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• pp.172-181
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• 2010

Hydrofluoroethers (HFEs) with fluoride molecules in their structure which are evaluated as the third generation replacement alternatives to chlorofluorocarbons (CFCs) are known to be excellent for removal of nanoparticles and fluoride-type soils due to their low surface tension and high wetting index. In addition, HFEs have good physical properties with no flash point and excellent drying characteristics. But, HFEs also have shortcomings in that they are not effective for removal of organic soils due to their poor solubility in soil. In this study, $C_5$ HFE-based cleaning agents were formulated through addition of solvents such as isopropyl alcohol (IPA), ethyleneglycol monoether (EG), propyleneglycol monoethylether (PM) to HFE-7100 [$CF_3CF_2CF_2CF_2OCH_3$] or HFE-mec-f [$CF_3CHF=CF_2OCH_2CF_3$] with its maximum amount, respectively, in order to have no flash point for the safety in the working environment. These solvents are known to be excellent for dissolving organics in soil. Their physical properties and cleaning abilities for fluxes, water-insoluble cutting oils, and fluoride-type oils were evaluated and compared with those of other cleaning agents with single components. The experimental results show that the HFE-based formulated cleaning agents have various good physical properties which are almost similar to those of a single type of HFE cleaner. They show excellent cleaning ability for fluxes, water-insoluble cutting oils, and fluoride-type oils. These results indicate that the HFE-based formulated cleaning agents can be applicable to various industrial cleaning fields because of their good physical properties and cleaning abilities for various soils.

• Clean Technology
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• v.19 no.2
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• pp.184-188
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• 2013

To increase flash point which is related to flammability, seven unprecedented new cleaning agents containing fluoride atoms have been invented. These newly synthesized cleaning agents's physical properties which were conducted by Korea Institute of Petroleum Management by using a standard method showed excellent values. Particularly, flash point of newly synthetic cleaning agents is more higher than that of fluoride free compound. A specimen for cleaning ability was prepared by cutting in $60mm{\times}40mm$ size of stainless steel plate. The surface of the above specimens was applied with four kinds of contaminants, such as paraffin based drawing oil, flux abietic acid, water-insoluble cutting oil, and lubricating oil. Contaminated specimens were immersed in new compounds (1-7) for 1 to 5 minutes to dissolve oil in the cleaning agent. Although the data indicate that all compounds (1-7) exhibit lower cleaning ability toward cutting oil, it is observed that in the case of the present study more than 80% of pollutants on the surface were almost removed within 5 minutes.

• Clean Technology
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• v.15 no.3
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• pp.186-193
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• 2009

The characteristics of product materials obtained from thermal degradation of low-qualify pyrolytic oil were investigated in this study. The reactants were produced by pyrolysis of mixed plastic waste with film type in a commercial rotary kiln reaction system. The properties of reactants were measured by elemental analysis, calorimetry analysis and SIMDIST analyst. The result of degradation experiments with different reaction temperature programs was discussed through product yields, cumulative yields and production rates of oil products. The multi-step reaction temperature program resulted in higher yields of product oils and lower yields of residues than one-step reaction temperature program. The product characteristics such as production yield and the rate of oil products etc. were influenced by reaction temperature program in the continuous thermal degradation.

• Clean Technology
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• v.15 no.2
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• pp.109-115
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• 2009

The low temperature pyrolysis of polyethylene (PE), polypropylene (PP) and polyethylene-polypropylene (PE-PP) mixture in a batch reactor at the atmospheric pressure and $450^{\circ}C$ was carried out to investigate the synergy effect of PE-PP mixture. The pyrolysis time was from 20 to 80 mins. The products formed during pyrolysis were classified into gas, gasoline, kerosene, gas oil and heavy oil according to the petroleum product quality standard of Korea Institute of Petroleum Quality. The analysis of the product oils by GC/MS showed that no new component was detected and no synergy effect was made by mixing of PE and PP. Conversions and yields of PE-PP mixtures were linearly dependent on the mixing ratio of samples.

• Clean Technology
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• v.16 no.1
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• pp.26-32
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• 2010

The low temperature pyrolysis of polypropylene (PP), polystyrene (PS) and polypropylene-polystyrene (PP-PS) mixture in a batch reactor at the atmospheric pressure and $450^{\circ}C$ was conducted to investigate the synergy effect of PP-PS mixture on the yield of pyrolytic oil. The pyrolysis time was varied from 20 to 80 mins. The products formed during pyrolysis were classified into gas, gasoline, kerosene, gas oil and heavy oil according to the petroleum product quality standard of Ministry of Knowledge Economy. The analysis of the product oils by GC/MS(Gas chromatography/Mass spectrometry) showed that new components were not detected by mixing of PP and PS. There was no synergy effect according to the mixing of PP and PS. Conversions and yields of PP-PS mixtures were linearly dependent on the mixing ratio of samples except for heavy oil yields. Heavy oil yields showed almost constant regardless of the mixing ratio.

• Clean Technology
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• v.28 no.2
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• pp.174-181
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• 2022

Biomass is a sustainable alternative resource for production of liquid fuels and organic compounds that are currently produced from fossil fuels including petroleum, natural gas, and coal. Because the use of fossil fuels can increase the production of greenhouse gases, the use of carbon-neutral biomass can contribute to the reduction of global warming. Although biological and chemical processes have been proposed to produce petroleum-replacing chemicals and fuels from biomass feedstocks, it is difficult to replace completely fossil fuels because of the high oxygen content of biomass. Production of petroleum-like fuels and chemicals from biomass requires the removal of oxygen atoms or conversion of the oxygen functionalities present in biomass derivatives, which can be achieved by catalytic hydrodeoxygenation. Hydrodeoxygenation has been used to convert raw biomass-derived materials, such as biomass pyrolysis oils and lignocellulose-derived chemicals and lipids, into deoxygenated fuels and chemicals. Multifunctional catalysts composed of noble metals and transition metals supported on high surface area metal oxides and carbons, usually selected as supports of heterogeneous catalysts, have been used as efficient hydrodeoxygenation catalysts. In this review, the catalysts proposed in the literature are surveyed and hydrodeoxygenation reaction systems using these catalysts are discussed. Based on the hydrodeoxygenation methods reported in the literature, an insight for feasible hydrodeoxygenation process development is also presented.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.462-465
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• 2007

석탄가스화 수소생산 기술 분야는 석탄 등의 화석연료를 이용하여 고온, 고압하에서 반응가스(산소, 수증기, 수소)와의 화학적 반응을 통해 생산된 연소성 가스 ($H_2$, CO, $CO_2$ 등)를 전환반응(WGS) 및 분리반응을 거쳐 효율적으로 청정하게 수소를 생산해 내는 기술이다. 전력산업에서 석탄가스화 수소생산은 그 사용 방법(연료전지, 수소 터빈, 분산 이용 등)에 따라 발전시스템의 고효율화를 지향하고, zero-emission을 실현하는 첨단 발전 시스템의 종합 구현을 목표로 하고 있으며, 더불어, 도래하는 수소 경제로의 전이에 대비에 석탄을 이용한 중앙(Central) 수소생산 시스템을 구현하여 이송 및 전환을 통한 지역적 분산 이용을 가능케 하는 종합적인 인프라를 구축하는 기술이다. 본 기술에는 석탄가스화 기술, 수성가스 전환기술, 수소/$CO_2$ 분리기술, 이송용 연료 전환기술 등이 포함된다. 석탄가스화 수소생산 기술은 급등하는 오일 가격과 이의 수입사용 증가에 대응하기 위한 에너지 안보 대책 마련 및 효율 극대화의 필요성과 더불어, 전력산업에서 화력 발전시스템의 궁극적 실현 목표인 고효율, 초청정의 전력생산 시스템의 구현을 가능케 하여, 향후 화석 연료를 이용한 미래 발전 기술을 선도 할 것으로 기대된다. 더불어, 수소 경제로의 전환 시 수소 수요의 급팽창에 대비한 경제적인 대규모 수소생산 기술의 개발이 필요하며, 이에 기술 실현성이 가장 높은 석탄가스화 수소생산 기술의 개발 구현이 요구된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.170-170
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• 2011

최근 진공기술은 세계적으로 유럽, 미국 및 일본을 주축으로 개발되어 보급되고 있다. 국내에서는 초기 기술 단계인 수봉식펌프, 유회전펌프, 유확산펌프가 개발되어 있으나 일반 산업용으로만 사용되고 있으며 반도체용으로는 전혀 적용되지 못하고 있는 실정이다. 특히 고청정공간을 필요로 하는 환경인 고집적 반도체 공정 등에는 사용할 수 없다. 본 연구에서 개발하고자 하는 터보형 드라이펌프는 시스템 내에 전혀 오일을 사용하지 않고 저소음 및 고효율, 저진동, 넓은 사용압력범위 등의 이점 때문에 현재 반도체 공정용 펌프로서 크게 각광을 받고 있다. 그러나 수요가 점차 증가함에도 불구하고 아직까지 우리나라는 전량 수입에 의존하고 있다. 이에 본 연구에서는 반도체 공정에 적합한 배기속도와 압축비를 가지는 에너지 절약형의 반도체 공정용 대유량 터보형 드라이펌프를 개발하여 국산화를 도모하고자 한다. 또한 단순히 외국 제품의 복사품을 제작하는 것이 아닌 체계적인 자료 확보를 통한 설계기술의 정립과 제품개발을 목적으로 하고 있다. 향후 전 세계적으로 최고 수준의 반도체 제조기술을 보유하고 있는 국내에서 국산화 및 상용화에 성공한다면 세계의 드라이 진공펌프 시장에도 충분히 우리의 기술력을 입증할 수 있으며, 결과적으로 상용화까지 이루어지리라 기대한다.

• Clean Technology
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• v.25 no.4
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• pp.283-288
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• 2019

Monodisperse microparticles has been particularly enabling for various applications in the encapsulation and delivery of pharmaceutical agents. The microfluidic devices are attractive candidates to produce highly uniform droplets that serve as templates to form monodisperse microparticles. The microfluidic devices that have micro-scale channel allow precise control of the balance between surface tension and viscous forces in two-phase flows. One of its essential abilities is to generate highly monodisperse droplets. In this paper, a microfluidic approach for preparing monodisperse polycaprolactone (PCL) microparticles is presented. The microfluidic devices that have a flow-focusing generator are manufactured by soft-lithography using polydimethylsiloxane (PDMS). The crucial factors in the droplet generation are the controllability of size and monodispersity of the microdroplets. For this, the volumetric flow rates of the dispersed phase of oil solution and the continuous phase of water to generate monodisperse droplets are optimized. As a result, the optimal flow condition for droplet dripping region that is able to generate uniform droplet is found. Furthermore, the droplets containing PCL polymer by solvent evaporation after collection of droplet from device is solidified to generate the microparticle. The particle size can be controlled by tuning the flow rate and the size of the microchannel. The monodispersity of the PCL particles is measured by a coefficient of variation (CV) below 5%.

• Clean Technology
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• v.17 no.2
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• pp.117-123
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• 2011

In this study, evaluation tests for cleaning performance of various cleaning agents and selection of optimal ultrasonic cleaning parameters were executed to develop an efficient cleaning process in remanufacturing of laser copy machine. Cleaning performance tests were executed with 8 cleaning agents (A~H) to remove the contaminants of oil-ink, toner particles, and shoe polish. Physical properties and foamability tests were also applied. For 3 types of contaminants, cleaning agent G showed superior cleaning performance compared to agent A which has being used at a remanufacturing of laser copy machine in Korea. With cleaning agents selected in pre-tests, ultrasonic cleaning tests were executed to remove real contaminants on the parts of used digital laser copy machine parts. Cleaning agent G at 28 kHz ultrasonic frequency showed faster cleaning performance compared to agent A and other frequencies. The productivity and economic efficiency in remanufacturing of laser copy machine are expected to increase by adapting agent G and 28 kHz frequency at ultrasonic cleaning process.