• 한국콘텐츠학회논문지
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• 제6권12호
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• pp.163-168
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• 2006

LCD의 배면광원으로 활용될 무수은 형광램프를 제작한 다음, 전기 광학적 특성을 평가하였다. PDP 형광체, nitro-cellulose 및 n-butyl acetate를 혼합하여 유리관 내부에 얼룩 없이 균일하게 코팅하였다. 또 $550^{\circ}C$에서 20 분 동안 소성하였고, 가스혼합장치를 이용하여 $10^{-6}$ torr까지 배기시킨 다음 방전가스를 주입하여 형광램프를 완성시켰다. 형광체 두께 및 유리관 직경 등을 변화시켜 제작, 평가한 결과 이들 변수들에 대하여 최적의 값을 찾아 낼 수 있었다. 또한 Ne+Xe 방전가스를 주입하여 제작된 형광램프에 75 kHz의 정현파 전압을 공급시킨 결과 휘도 $6,270cd/m^2$, 발광효율 13 lm/W를 얻었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.135-135
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• 2015

Tubes are of extreme importance in industries as for fluid channels or wave guides. Furthermore, some weapon systems such as cannons use the tubes as gun barrels. To increase the service life of such tubes, a protective coating must be applied to the tubes' inner surface. However, the coating methods applicable to the inner surface of the tubes are very limited due to the geometrical restriction. A small-diameter cylindrical magnetron sputtering gun can be used to deposit coating layers on the inner surface of the large-bore tubes. However, for small-bore tubes with the inner diameter of one inch (~25 mm), the magnetron sputtering method can hardly be accommodated due to the space limitation for permanent magnet assembly. In this study, a new approach to coat the inner surface of small-bore tubes with the inside diameter of one inch was developed. Instead of using permanent magnets for magnetron operation, an external electro-magnet assembly was adopted around the tube to confine the plasma and to sustain the discharge. The electro-magnet was operated in pulse mode to provide the strong axial magnetic field for the magnetron operation, which was synchronized with the negative high-voltage pulse applied to the water-cooled coaxial sputtering target installed inside the tube. By moving the electro-magnet assembly along the tube's axial direction, the inner surface of the tube could be uniformly coated. The inner-surface coating system in this study used the tube itself as the vacuum chamber. The SS-304 tube's inner diameter was 22 mm and the length was ~1 m. A water-cooled Cu tube (sputtering target) of the outer diameter of 12 mm was installed inside of the SS tube (substrate) at the axial position. The 50 mm-long electro-magnet assembly was fed by a current pulse of 250 A at the frequency and pulse width of 100 Hz and 100 usec, respectively. The calculated axial magnetic field strength at the center was ~0.6 Tesla. The central Cu tube was synchronously driven by a HiPIMS power supply at the same frequency of 100 Hz as the electro-magnet and the applied pulse voltage was -1200 V with a pulse width of 500 usec. At 150 mTorr of Ar pressure, the Cu deposition rate of ~10 nm/min could be obtained. In this talk, a new method to sputter coat the inner surface of small-bore tubes would be presented and discussed, which might have broad industrial and military application areas.

• 한국초전도저온공학회지:초전도와저온공학
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• 제6권2호
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• pp.42-46
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• 2004

금속 테이프 위에 초전도층을 박막형태로 증착시켜서 제조되는 고온초전도 선재인 coated conductor (CC)는 powder-in-tube 공정으로 제조되는 1세대 고온초전도 선재에 비해 액체 질소 온도에서 높은 임계 전류 밀도와 우수한 자장 특성을 가지면서 더 경제적으로 제조 가능하기 때문에 액체질소온도에서 작동 가능한 초전도전력기기 개발에 반드시 필요한 부분으로 인식되고 있다. 최근 국내외적으로 다양한 증착 방법을 사용하여 전력기기 응용이 가능한 장선의 CC 제조공정을 개발하려는 연구가 활발히 진행되고 있다. 특히 외국의 경우 이미 CC 선재의 상업화를 위해 기업체가 중심이 되어 집중적인 연구 개발이 이루어지고 있다.(중략)

• 대한설비공학회지:설비저널
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• 제28권5호
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• pp.389-395
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• 1999

냉동공조설비, 발전설비, 화학플랜트설비 등에 사용되는 응축기는 주로 증기가 관의 외부에서 응축을 하고 냉각수가 관 내부로 흐르는 쉘-튜브(shell and tube)형 태를 취하고 있다. 초기투자비용 및 운전비용을 줄이기 위해서는 응축기의 열교환 성능을 향상시키는 일이 필수적이며 이를 위해 코팅 표면(coated surfaces), 거친 표면(rough surfaces), 코일 튜브(coiled tubes), 선회 흐름장치(swirl flow), 전열면적을 넓힌 낮은 핀관과 3차원 형상을 갖는 열전달 촉진관의 사용이 제시되고 있다.

• 한국수소및신에너지학회논문집
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• 제17권1호
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• pp.82-89
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• 2006

The redox behaviors of anode-supported flat tube for solid oxide fuel cell has been studied. The mass change of the extruded NiO/YSZ anode flat tube during redox cycling was examined by thermogravimetric analysis(TGA). The result of TGA was shown a rapidly mass change in the range of $455\;-\;670^{\circ}C$ and the reoxidation of the NiO/YSZ anode was almost completed at $750^{\circ}C$. The starting temperature of reoxidation and the maximum temperature of oxidation rate decreased with increasing the reoxidation cycle, which is attributed to the increased porosity caused by volume change. Bending strengths of the NiO/YSZ anode after redox cycling were 96 - 80 MPa and the bending strength decreased slightly with increasing the redox cycle. On the other hand, the bending strength of the NiO/YSZ anode with electrolyte showed 130 MPa after first redox cycling but decreased rapidly with increasing the redox cycle. From the results of the bending test and the microstructure observation, we conclude that the crack initiation of the electrolyte-coated NiO/YSZ anode was induced easily at interface of electrolyte/anode tube and propagated cross the electrolyte.

• 한국가스학회지
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• 제2권4호
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• pp.67-72
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• 1998

Al-2wt.$\%$Zn 합금은 특히 해수에 대한 내식성이 우수하여 기화기 튜브의 회생양극재료로 사용되고 있다. 그러나 Al-2wt.$\%$Zn 용사코팅재는 모재금속과 코팅층사이의 결합강도부족, 해수의 낙하에너지에 의해 코팅층은 박리 된다. 이러한 용사코팅충의 문제점을 해결하고자 클래드재와 모재금속을 동시압출법을 통하여 클래드튜브 제조공정을 개발하였다. 클래드튜브의 내식성은 용사코팅튜브에 비하여 최소 2배 이상 향상되었다.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.3026-3034
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• 2021

Multi-target X-ray tube is a new type X-ray source, and can be applied in many fields such as sensitive X-ray fluorescence analysis and medical imaging. In this work, we report an electric field modulation multi-target X-ray tube, which contains four targets (Cr, Ni, Au, Mo) coated on a Beryllium (Be) window. A four-valve electric field deflector was developed to deflect the electron beam to bombard the corresponding targets. Particle dynamics analysis software was employed to simulate the particle tracking of electron beam. The results show that the 30 keV electron beam could get a 6.7 mm displacement on the target plane by 10⁵ V/m electric field. The focus areas are about 2 mm × 5 mm and 4 mm × 2.5 mm after deflection in two directions. Thermal behavior calculated by ANSYS shows that the designed target assembly could withstand a 10 W continuous power. The optimum target thicknesses and emission spectra were obtained by Geant4 when the thickness of Be window was 300 mm and the electron beam incident angle was 0.141 rad. The results indicate that this multi-target X-ray tube could provide different X-ray sources effectively.

• Nuclear Engineering and Technology
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• 제47권4호
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• pp.398-406
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• 2015

In this study, R-123 flow boiling experiments were carried out to investigate the effects of nanoparticle deposition on heater surfaces on flow critical heat flux (CHF) and boiling heat transfer. It is known that CHF enhancement by nanoparticles results from porous structures that are very similar to layers of Chalk River unidentified deposit formed on nuclear fuel rod surfaces during the reactor operation period. Although previous studies have investigated the surface effects through surface modifications, most studies are limited to pool boiling conditions, and therefore, the effects of porous surfaces on flow boiling heat transfer are still unclear. In addition, there have been only few reports on suppression of wetting for decoupled approaches of reasoning. In this study, bare and $Al_2O_3$ nanoparticle-coated surfaces were prepared for the study experiments. The CHF of each surface was measured with different mass fluxes of $1,600kg/m^2s$, $1,800kg/m^2s$, $2,100kg/m^2s$, $2,400kg/m^2s$, and $2,600kg/m^2s$. The nanoparticle-coated tube showed CHF enhancement up to 17% at a mass flux of $2,400kg/m^2s$ compared with the bare tube. The factors for CHF enhancement are related to the enhanced rewetting process derived from capillary action through porous structures built-up by nanoparticles while suppressing relative wettability effects between two sample surfaces as a highly wettable R-123 refrigerant was used as a working fluid.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.229-237
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• 2018

Medical silicone tubes are generally used as implants for the treatment of nasolacrimal duct stenosis. However, side effects such as allergic reactions and bacterial infections have been reported following the silicone tube insertion, which cause surgical failure. These drawbacks can be overcome by modifying the silicone tube surface using a functional coating. Here, we report a biocompatible and superhydrophilic surface coating based on a polysaccharide multilayer nanofilm, which can load and release antibacterial and anti-inflammatory agents. The nanofilm is composed of carboxymethylcellulose (CMC) and chitosan (CHI), and fabricated by layer-by-layer (LbL) assembly. The LbL-assembled CMC/CHI multilayer films exhibited superhydrophilic properties, owing to the rough and porous structure obtained by a crosslinking process. The surface coated with the superhydrophilic CMC/CHI multilayer film initially exhibited antibacterial activity by preventing the adhesion of bacteria, followed by further enhanced antibacterial effects upon releasing the loaded antibacterial agent. In addition, inflammatory cytokine assays demonstrated the ability of the coating to deliver anti-inflammatory agents. The versatile nanocoating endows the surface with anti-adhesion and drug-delivery capabilities, with potential applications in the biomedical field. Therefore, we attempted to coat the nanofilm on the surface of an ophthalmic silicone tube to produce a multifunctional tube suitable for patient-specific treatment.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.14-14
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• 2009

High frequency electromagnetic(EM) waves are increasingly being applied in industries because of saturationat lower frequency bands as a result of huge demand. However, electromagneticinterference (EMI) has become a serious problem, and as a result, highfrequency EM absorbers are now being extensively studied. Also, recentdevelopments in absorber technology have focused on producing absorbers thatare thin, flexible, and strong. Hence, one-dimension ferrous nano-materials area potential research field, because of their interesting electronic andmagnetic properties. Commercially, EM wave absorbing products are made ofcomposites, which blend the insulating polymer with magnetic fillers. Inparticular, the shape of the magnetic fillers, such flaky, acicular, or fibrousmagnetic metal particles, rather than spherical, is essential for synthesizingthin and lightweight EM wave absorbers with higher permeability. High aspectratio materials exhibit a higher permeability value and therefore betterabsorption of the EM wave, because of electromagnetic anisotropy. Nanowires areusually fabricated by drawing, template synthesis, phase separation, selfassembly, and electrospinning with a thermal treatment and reduction process.Producing nanowires by the electrospinning method involves a conventionalsol-gel process that is simple, unique, and cost-effective. In thispresentation, Magnetic nanowire and dielectric materials coated magneticnanowire with a high aspect ratio were successfully synthesized by theelectrospinning process with heat treatment and reduction. In addition toestimating the EM wave absorption ability of the synthesized magnetic anddielectric materials coated magnetic nanowire with a network analyzer, weinvestigated the possibility of using these nanowires as high-frequency EM waveabsorbers. Furthermore, a wide variety of topics will be discussed such as thetransparent conducting nanowire and semiconducting nanowire/tube with theelectrospinning process.