• 멤브레인
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• 제22권2호
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• pp.142-154
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• 2012

DME 제조공정에서 발생하는 혼합가스 중 $CO_2$를 제거하기 위해서 $H_2$ 투과도보다 $CO_2$투과도가 우수한 고무상 고분자를 분리소재로 선정하여 복합막을 제조하고 $CO_2/H_2$의 분리성능을 검증하여 보았다. 지지체 중공사막 소재로 PEI를 이용하여 지지체 중공사막을 제조하였으며, 제조된 지지체 중공사막의 기체투과도를 각 가스별로 측정하여 PDMS의 경우는 $CO_2$ 투과도 300 GPU 이상, $CO_2/H_2$의 선택도가 4.3 이상, PEBAX를 사용한 경우 $CO_2$ 투과도 120 GPU 이상 $CO_2/H_2$의 선택도가 5 이상인 복합 중공사를 제조하였다.

• 한국세라믹학회지
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• 제46권1호
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• pp.74-80
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• 2009

Electrospinning process is the useful and unique method to produce nanofibers from metal precursor and polymer solution by controlled viscosity. In this study, the NiZn ferrite nanofibers were prepared by electrospinning with a aqueous metal salts/polymer solution that contained polyvinyl pyrrolidone and Fe (III) chloride, Ni (II) acetate tetrahydrate and zinc acetate dihydrate in N,N-dimethylformamide. The applied electric field and spurting rate for spinning conditions were 10 kV, 2 ml/h, respectively. The obtained fibers were treated at $250^{\circ}C$ for 1 h to remove the polymer. Finally, the NiZn ferrite fibers were calcined at $600^{\circ}C$ for 3 h and annealed at $900{\sim}1200^{\circ}C$ in air. By tuning the viscosity of batch solution before electrospinning, we were able to control the microstructure of NiZn ferrite fiber in the range of $150{\sim}500\;nm$ at 770 cP. The primary particle size in $600^{\circ}C$ calcined ferrite fiber was about 10 nm. The properties of those NiZn ferrite fibers were determined from X-ray diffraction analysis, electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, thermal analysis, and magnetic measurement.

• 전기화학회지
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• 제3권1호
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• pp.15-18
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• 2000

태양전지의 전극 기판으로 사용되는 전도성 투명 산화주석 박막의 제조 방법에 대하여 연구하였다. 졸겔법을 이용하여 산화 주석 박막을 제조하는 경우에 저가의 공정으로 대면적의 박막을 얻을 수 있는 장점이 있다. 본 연구에서는 공정 조건의 확립과 전구체의 설정에 중점을 두었다. 전구체 용액을 isopropyl 알코올에 tin isopropoxide를 용해한 용액을 사용하였으며 수화 반응을 억제하기 위하여 triethanolamine(TEA)을 첨가하였다. Corning유리 위에 spinning과 dipping방법을 이용하여 코팅을 하였으며 이후 열처리하여 최종 산화주석 박막을 제조하였다. 이렇게 제조된 박막은 가시광선 영역에서 $90\%$ 이상의 투과도를 보였으며 $0.01\Omega{\cdot}cm$ 이하의 비저항을 나타냈다

• 한국진공학회지
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• 제6권4호
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• pp.308-313
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• 1997

Capacitance Diaphragm Gauge(CDG)를 전달표준기로 사용하여 한국과 영국의 저진 공표준의 국제비교를 수행한 결과 양국 표준기에서 교정한 CDG의 압력비의 차이는 0.05% 이었다. 또한 두 개의 Spinning Rotor Gauge(SRG)를 이용하여 한국과 일본이 고진공표준의 국제비교를 수행한 결과 양국 표준기에서 교정한 SRG의 accommodation coefficient($sigma$)의 차이가 0.4% 이내이었다. CDG와 SRG를 이용한 한국과 영국의 저진공표준기 및 한국과 일 본의 고진공표준기의 국제비교 결과 CDG 및 SRG 자체의 고유오차범위 이내에서 결과가 일치함을 확인할 수 있었다.

• 대한기계학회논문집A
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• 제32권6호
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• pp.465-473
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• 2008

Type II compressed natural gas(CNG) storage vessels for automobiles have been acknowledged for their excellence and have recently become established in local regions. Their supply is not only to automakers in Korea such as Hyundai Motors but they are being increasingly exported. Although the available products have undergone safety evaluations and are certified by an authorized institution they are still short of the optimal design that is possible for such storage vessels. This research investigates the shape and thickness of the dome with the aim of optimizing the type II CNG storage vessels by using a finite element analysis technique. CNG storage vessels can be largely divided into 3 parts namely, the hear part, the cylinder part and the dome part. The head part is designed by means of a hot spinning process and this method is safer than that used in the design of the dome part even though its shape is similar. The thickness of the liners and reinforcing materials was optimized based on the requirements of the cylinder and dome parts. In addition, the shape of the dome, which is most suitable for Type II CNG storage vessels, is proposed by a process of review and analysis of various existing shape, and then conducting a structural stability evaluation to ensure the optimal design plan.

• 한국의류학회지
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• 제41권3호
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• pp.458-467
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• 2017

There is increased interest in clothes dryers and garments made of spandex-blend woven fabrics; however, there is limited information available for the laundering and drying these clothes. This study investigates the effects of washing and drying on shrinkage, skewness, and wrinkle for woven fabrics with and without spandex. When spandex with good elastic recovery was blended, the deformed shape from washing and drying improved skewness and wrinkle by easily returning to its original shape. However, these properties had a negative effect on shrinkage in terms of length and area change. When the influence of clothes maintenance was classified, the drying process had the biggest influence of 58%, followed by spinning-rinsingwashing. Tumble drying, in which the fabric is exposed to mechanical force and heat for a long period, had more negative effects on the dimensional stability than line drying. The spandex blend had the effect of preventing skewness and wrinkle in garments, but it was also shown to accelerate shrinkage by garment maintenance cycles. It was important to control drying in order to reduce shrinkage during the maintenance process; consequently, this had the greatest influence on the dimensional stability of fabrics. Therefore, line drying was more advantageous for spandex-blend fabrics than tumble drying in terms of management for shrinkage, skewness, and wrinkle.

• 환경위생공학
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• 제23권3호
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• pp.9-22
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• 2008

This study was conducted to develop a system that processes harmful gases and dust, which being generated in the production of micro-inorganic fabric. This can be obtained by melt spinning raw materials such as agalmatolite, fluorspar, limestone, silica under high temperature at $1500-1600^{\circ}C$ in a glass recuperator using a dry method by Cyclone Reactor or Envelope Type (ET) type Bag Filter. If the number of the members of Korea Glass Industry Association reaches up to 45, the damage of the harmful gas being generated in recuperator should not be small. In addition, research of existing facilities showed the most of harmful gas treatment facilities which adopt wet treatment or semi-dry treatment process. This was caused the problems for wastewater and the second pollutive materials. Moreover, in the dust collecting facility behind recuperator, it is also problematic that electric dust collector requires enormous initial investment. We have researched various methods to show both economic and efficient new processes for the preventive facilities of recuperator. As the result of the experiments, the removal efficiencies of HF and SOx were 99% and 87%, respectively. Although it was insignificant reaction, a pretty much interesting result that NOx showed an absorption reaction with $Ca(OH)_2$(removal efficiency was more than 25%) was obtained.

• 공업화학
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• 제17권3호
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• pp.331-334
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• 2006

본 연구에서는 포집부의 재질과 포집장치를 개선하여 배향성이 존재하는 극세섬유를 제조하였다. 방사용액은 polyamide-polyimide copolymer (PAI)를 사용하였다. 포집부의 재질을 변화하고 동일한 전압을 가하여 제조된 극세섬유의 형태를 비교하였다. 한편, 물 포집부와 회수장치로 구성된 장치를 통하여 극세섬유를 제조하고 SEM을 통하여 관찰하였다. 실험결과, 동일한 전압으로 제조된 섬유의 평균직경은 포집부의 재질과 회수방식에 영향을 받지 않았으나 포집부의 재질과 회수방법에 따라 섬유의 형태가 변화하는 것이 관찰되었다. 포집부에 누적시켜 제조된 극세섬유는 배향성이 존재하지 않는 그물형 구조인데 반하여, 별도의 회수장치를 통하여 연속적으로 회수된 극세섬유는 배향성이 존재함을 확인하였다. 이는 물 포집부가 섬유의 유도, 임시집적, 섬유와의 마찰 그리고 이동경로 역할을 하였고, 회수장치는 속도 조절을 통하여 물과 섬유간의 마찰을 제어함으로써 연속적인 회수가 가능한 것으로 판단된다.

• 전기학회논문지
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• 제66권11호
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• pp.1584-1590
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• 2017

This paper presents a implementation method of reliable speed limitation controller considering motor parameter variation in high speed operation. In spinning process of drum washing machine, speed increase has to be limited when unallowable imbalance mass is detected. Otherwise, severe noise and vibration can happen because noise and vibration are proportional to imbalance mass. To detect imbalance mass, d-axis current magnitude is used. However, we have to compensate for back-emf and power supply variation by means of detecting them because d-axis current is affected by both of them. On the other hand, we have to carefully estimate back-emf because back-emf is affected by stator resistance variation and inverter voltage error. Stator resistance variation can happen by manufacturing process for mass production or temperature variation in running. And there are inverter voltage errors between command voltage from micro-computer to inverter and real voltage from inverter to motor because of rising and falling time delay and turn-on resistance of power semiconductor switch. To solve this problem, we propose 2-step align current injection method which is to inject step-wise current right before starting. By this method, we can simply obtain stator resistance by ratio of voltage without inverter voltage error and current, and we can measure inverter voltage error. So we can obtain more exact model current, and then by simple calculation with compensation gain, we can estimate more accurate motor back-emf. We show that this method works well. It is verified through experiments.

• 폴리머
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• 제33권3호
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• pp.219-223
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• 2009

전기방사 공정을 이용하여 제조된 나노파이버는 나노 소자, 필터, 방호닦, 항균성 드레싱 및 약물전달 등 다양한 분야에서 이용되고 있다. 약물전달시스템(drug delivery system, DDS)은 기존 의약품의 부작용을 최소화하며 그 효능 및 효과를 극대화할 수 있어야 하고 필요한 양의 약물을 원하는 환부에 효율적으로 전달할 수 있어야 한다. 본 연구에서는 전기유체역학공정의 하나인 전기방사공정을 이용하여, poly($\varepsilon$-carprolactone)(PCL) poly(ethylene oxide(PEO)를 나노파이버 매트로 만들었으며, 고분자와 동시 방사된 Rhodamine B의 방출량을 측정하였다. PCL/Rhodamine B/PEO/PCL 나노파이버 매트는 전기방사 시간을 통한 두께 조절을 통하여 약물전달 거동이 조절될 수 있음을 확인하였으며, 실제 Peptide를 PEO와 동시 전기방사시켜 얻어진 나노파이버 peptide가 방출되는 거동을 확인하였다. PCL/Peptide/PEO/PCL시스템에서 방출된 peptide는 약물방출 시험 후에도 약물로서의 활성도를 잃지 않았으며, 이러한 나노파이버를 이용한 Peptide 방출메커니즘은 새로운 약물전달시스템으로 적용 및 응용될 수 있을 것으로 예상된다.