• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.396-396
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• 2013

The resistive random access memory (ReRAM) has several advantages to apply next generation non-volatile memory device, because of fast switching time, long retentions, and large memory windows. The high mobility of monolayered graphene showed several possibilities for scale down and electrical property enhancement of memory device. In this study, the monolayered graphene grown by chemical vapor deposition was transferred to $SiO_2$ (100 nm)/Si substrate and glass by using PMMA coating method. For formation of metal-oxide nanoparticles, we used a chemical reaction between metal films and polyamic acid layer. The 50-nm thick BPDA-PDA polyamic acid layer was coated on the graphene layer. Through soft baking at $125^{\circ}C$ or 30 min, solvent in polyimide layer was removed. Then, 5-nm-thick indium layer was deposited by using thermal evaporator at room temperature. And then, the second polyimide layer was coated on the indium thin film. After remove solvent and open bottom graphene layer, the samples were annealed at $400^{\circ}C$ or 1 hr by using furnace in $N_2$ ambient. The average diameter and density of nanoparticle were depending on annealing temperature and times. During annealing process, the metal and oxygen ions combined to create $In_2O_3$ nanoparticle in the polyimide layer. The electrical properties of $In_2O_3$ nanoparticle ReRAM such as current-voltage curve, operation speed and retention discussed for applictions of transparent and flexible hybrid ReRAM device.

• 산업기술연구
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• 제23권A호
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• pp.199-206
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• 2003

The charcoal-encapsulated methyl silica microcapsules were prepared by a O/W microemulsion sol-gel method, and the adsorption properties on aquatic humic acid were investigated. The capsules prepared were spherical, $100{\sim}1000{\mu}m$ in size. The size distribution was controllable by adjusting the size of charcoal powder, charcoal/methyl silica ratio, and agitating speed in O/W sol-gel process. Adsorption efficiency of charcoal for aquatic humic acid was decreased after encapsulation by methyl silica shell. The decreased adsorption efficiency can be dependent on the decrease of the BET surface area and pore volume after encapsulation. Diffusion properties of humic acid through the capsule shell also played an important role on adsorption efficiency. Therefore, the reasonable target pollutants for the capsules can be VOC or odor molecules which can overcome diffusion barrier through shell of capsules in air condition. Functionalization methods for the charcoal-encapsulated $CH_3(SiO)_n$ microcapsules by incorporation of $TiO_3$ as a phtocatalytic function and by incorporation of inorganic pigment as a color function were also investigated. $TiO_2$ coating properties were controllable by adjusting pH, temperature, and the concentration of $TiOSO_4$. In XRD measurement, the crystal form of the coated $TiO_2$ was anatase. For the colorization of the capsules, inorganic pigments were more efficient than organic dyes, and various color was introduced to the capsules using inorganic pigments.

• 청정기술
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• 제14권1호
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• pp.35-39
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• 2008

본 연구에서는 용매에 따른 고분자의 용해도 차이를 이용하여 슬라이드글라스 표면위에 초소수성 고분자막을 성공적으로 제조하였다. 폴리스타이렌 (PS)을 tetrahydrofuran (THF)에 녹인 후 다시 에탄올(EtOH)을 첨가하여 두 용매의 용해도 차이로 표면에 초소수성 성질을 갖게 제조하였다. 한편, EtOH 첨가, 코팅방법, 용액혼합 시간과 속도 및 다른 알콜들이 형성된 표면의 소수성에 미치는 영향들을 각각 조사하였다. 접촉 각 측정기를 사용하여 측정한 결과 $150^{\circ}$ 이상의 물 접촉각을 확인하였고, 광학현미경(optical microscopy)과 주사전자현미경(scanning electron microscope, SEM)으로 관찰한 표면 구조는 $5\;{\mu}m$ 이하의 입자들로 구성된 미세다공성 구조임이 확인되었다.

• 자원리싸이클링
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• 제19권1호
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• pp.27-32
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• 2010

리튬이온전지의 양극 전자전도도를 향상시키기 위하여 탄소제를 첨가할 때 기존의 혼합법과는 다르게 abrasive milling에 의하여 $LiCoO_2$ 양극 활물질에 흑연을 균일하게 분산시켜서 충방전시 용량감소를 줄이고자 하였다. 밀링 조건은 300 rpm, 10min으로 하였으며, 흑연 농도는 전기 전도성 향상과 용량의 관계를 고려해 볼 때, 1 wt% 경우가 가장 우수한 전극특성을 보여주었다. Abrasion법은 기존 혼합법에 비하여 10% 이상 capacity retention의 향상을 가져올 수 있었으며, 비가역적인 용량에 있어서도 초기 방전 용량의 효율도 높아 비가역 용량이 감소되는 효과를 얻을 수 있었다. 이는 첨가한 흑연이 균일하게 혼합되고 일부는 $LiCoO_2$ 표면에 코팅되어 전자전도도를 향상시키고 산화물인 활물질의 용해를 억제하기 때문으로 생각된다.

• 센서학회지
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• 제2권1호
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• pp.35-40
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• 1993

$Si_{3}N_{4}$ 박막의 코팅된 pH-ISFET의 게이트 부위 위에 lipase 효소를 고정화하여 FET(field effect transistor) 형지질(lipid) 센서를 제조하였다. 효소 고정화막 형성 물질로는 수용성 고분자인 polyvinyl alcohol(PVA)에 감광성기인 1-methyl-4-(formylstyryl) pyridinium methosulfate(SbQ)를 결합시킨 PVA-SbQ를 사용하였다. PVA-SbQ 수용액 (SbQ 1mole %, 10 wt%) $200{\mu}L$, bovine serum albumin (BSA) 7.5 mg, lipase 10 mg으로 구성 된 현탁액을 사용한 사진식각(photolithographic) 공정의 최적 조건은 피막의 상온 진공 건조 시간 45분, spin coater의 회전수 $5,000{\sim}6,000$ rpm, UV 노광시간 $20{\sim}30$초, 증류수 현상 시간 $30{\sim}40$초로 나타났다. 이렇게 구성된 지질 센서는 triacetin을 지질 시료로 하였을 때 $10{\sim}100$ mM의 농도 범위에서 직선성의 검정선을 나타내었다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.274-281
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• 2018

Experimental studies of the hydrodynamic performance of the draft tube conical spout-fluid bed (DCSF) were conducted using pharmaceutical pellets. The experiments were carried out in a DCSF consisted of two sections: (a) a conical section with the cross section of $120mm{\times}250mm$ and the height of 270 mm, (b) a cylindrical section with the diameter of 250 mm and the height of 600 mm. The flow characteristics of solids were investigated with a high speed camera and a pezoresistive absolute pressure transducer simultaneously. These characteristics revealed different flow regimes in the DCSF: packed bed at low gas velocities, fluidized bed in draft tube at higher gas velocities until minimum spouting, and spouted bed. The stable spouting was identified by the presence of two dominant frequencies of the power spectrum density of pressure fluctuation signature: (i) the frequency band 6-9 Hz and (ii) the frequency band 12-15 Hz. The pressure drops across the draft tube as well as the annulus measured in order to better recognize the flow structure in the DCSF. It was observed that the pressure drop across the draft tube, the pressure drop across the annulus, and the minimum spouting velocity increase with the increase in the height of draft tube and distance of the entrainment zone, but with the decrease in the distributor hole pitch. Finally, this study provided novel insight into the hydrodynamic of DCSF, particularly minimum spouting and stable spouting in the DCSF which contains valuable information for process design and scale-up of spouted bed equipment.

• 한국건설순환자원학회논문집
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• 제9권2호
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• pp.127-134
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• 2021

PMHS와 PVA를 혼합한 소수성 유액을 시멘트 모르타르에 혼입하여 수화생성물과 미세구조의 변화를 관찰하고, 압축강도와 휨강도를 실험적으로 평가하고자 하였다. 소수성 유액은 메타카올린과 PVA 섬유를 추가하고 교반속도와 순서를 조정하여 쉘형태의 유액을 제조하였으며, 모르타르배합시 혼입하여 내부 공극의 충진과 수화생성물의 변화를 도모하고자 하였다. 소수성 유액이 혼입된 모르타르는 미세공극이 충진되고 수화생성물표면이 유액에 의해 도막이 생성되는 것이 관찰되었다. OPC와 비교하여 유액이 혼입된 모르타르의 전체 기공면적과 기공률이 감소하는 것으로 분석되었으며, 일부 변수에서 기공지름의 중간값의 감소가 나타났다. 유액을 1% 혼입한 경우에 압축강도의 증가가 나타났으며, 2% 혼입시에는 강도의 감소가 발생하였다.

• 한국환경과학회지
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• 제32권6호
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• pp.403-417
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• 2023

In this study, we investigated the characteristics of Volatile Organic Compounds(VOCs) emission from painting and printing facilities in the Pyeongdong industrial complex in Gwangju. In addition, the objective was to understand the distribution characteristics of VOCs in the ambient air in industrial complexes affected by painting and printing facilities. The painting facility mainly emitted toluene, acetone, butyl acetate, 4-methyl-2-pentanone, ethyl acetate, 1-butanol, methyl ethyl ketone, m,p-xylene, o-xylene, 4-ethyltoluene, ethylbenzene, 3-ethyltoluene, and 1,2,4-trimethylbenzene. The main emission components in printing facilities were methyl ketone, ethyl acetate, acetone, 2-propanol, toluene, heptane, and butyl acetate. Ethyl acetate, toluene, 2-butanone, acetone, butyl acetate, 2-propanol, xylenes, and 4-methyl-2-pentanone were detected in the ambient air of the Pyeongdong industrial complex, consistent with the VOCs emitted by painting and printing facilities. The average concentration of seasonal TVOCs followed an order of winter > fall > spring > summer, whereas the concentrations of daytime and nighttime TVOCs were generally higher at night than those during the day, and the wind speed was greater during the day than it was at night. Based on a factor analysis of VOCs in the ambient air of Pyeongdong industrial complex, it is considered that organic solvents used in coating, printing, and electronics manufacturing facilities, as well as diesel vehicle emissions played a major role.

• 한국재료학회지
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• 제21권5호
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• pp.255-262
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• 2011

This paper has relatively high technical standard and experimental skill. The fabrication of TCO film with high transparency, low resistance and low chromaticity require exact control of several competing factors. This paper has resolved these problems reasonably well, thus recommended for publication. Indium tin oxide(ITO) thin films were by D.C. magnetron roll-to-roll sputter system utilizing ITO and $SiO_2$ targets of ITO and $SiO_2$. In this experiment, the effect of D.C. power, winding speed, and oxygen flow rate on electrical and optical properties of ITO thin films were investigated from the view point of sheet resistance, transmittance, and chromaticity($b^*$). The deposition of $SiO_2$ was performed with RF power of 400W, Ar gas of 50 sccm and the deposition of ITO, DC power of 600W, Ar gas of 50 sccm, $O^2$ gas of 0.2 sccm, and winding speed of 0.56m/min. High quality ITO thin films without $SiO_2$ layer had chromaticity of 2.87, sheet resistivity of 400 ohm/square, and transmittance of 88% and $SiO_2$-doped ITO Thin film with chromaticity of 2.01, sheet resistivity of 709 ohm/square, and transmittance of more than 90% were obtained. As a result, $SiO_2$ was coated on PET before deposition of ITO, their chromaticity($b^*$) and transmittance were better than previous results of ITO films. These results show that coating of $SiO_2$ induced arising chromaticity($b^*$) and transmittance. If the thickness of $SiO_2$ is controlled, sheet resistance value of ITO film will be expected to be better for touch screen. A four point probe and spectrophotometer are used to investigate the properties of ITO thin films.

• Journal of Advanced Marine Engineering and Technology
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• 제38권7호
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• pp.877-882
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• 2014

국제해사기구 해양환경보호위원회에서 그린하우스가스(GHG)의 주범인 CO2 배출량 감축을 위해 선박에서 대기로 방출하는 CO2의 양을 지수화 하고자 활발한 논의가 진행되고 있다. 이에 따라 에너지 효율 개선을 위해서 선체의 설계변경, 마찰저항을 줄이기 위한 도료개발, 엔진의 열효율을 개선하기 위한 첨가제 개발, 연료를 절감하기 위하여 저속운전 등 다양한 방법들이 적용되고 있다. 선박의 주 기관에서는 전 부하영역에서 효율을 높이기 위하여 전자엔진이 사용되고 있으나, 선박용 발전기 엔진은 여전히 캠으로 연료분사와 흡 배기 밸브를 구동하는 기계식 작동엔진이 대부분이다. 또한 선박용 발전기 엔진은 선박의 과부하 방지 시스템 내에서 운전되므로 대부분의 운전은 80% 이하의 부분부하 영역에서 사용되고 있다. 따라서 100%부하에 세팅된 발전기 엔진은 부분부하에서 효율적인 운전을 위해서는 연료분사시기 재조정이 필요하다. 본 연구는 현재 운항중인 선박발전용 디젤엔진의 운용특성을 파악하여 부분부하에서 연료분사시기 재조정을 통하여 연료소비량 개선에 관한 결과를 보고 하고자 한다.