• 한국대기환경학회지
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• 제20권5호
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• pp.655-662
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• 2004

An adsorption process to recover the pure $CH_4\;and\;CO_2$ from its mixture was examined. In this study, activated carbon fibers were used as a selective adsorbent. The activated carbon fibers has 78~94% micropore volume and 10.5~20.3${\AA}$ narrow pore size, and showed high adsorption rate and the good selectivity for $CO_2$ under the ambient pressure. The ACF with high surface area showed short mass transfer zone and long breakthrough time and, its adsorption capacity depended on the microporosity. Compared with single component adsorption, the amount adsorbed $CO_2$ on ACF increased by the roll-up of $CH_4$ in mixed gases. The adsorption selectivity increased as now rate and $CO_2$ concentration of mixed gases increased, showing 5.2 selectivity for 75% $CO_2$ concentration.

• Bulletin of the Korean Chemical Society
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• 제20권1호
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• pp.69-75
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• 1999

The silica-pillared H-kenyaites were prepared by interlarmellar base-catalyzed reaction of tetraethylorthosilicate [TEOS, Si(OC2H5)4] intercalated into the interlayer of H-kenyaite. The intercalation of TEOS was conducted by the octylamine preswelling process, resulting in a dramatic increase in gallery height to 24.7 Å. The interlamellar hydrolysis of octylamine-TEOS/H-kenyaite paste were conducted between 10 min and 40 min in 0.00%, 0.05% and 0.10% NH3-water solution respectively, and resulting in siloxane-pillared H-kenyajte with gallery height of 28.2-31.8 Å. The calcination of samples at 538 ℃ resulted in silica-pillared H-kenyaites with a large surface areas between 411 m2/g and 885 m2/g, depending on the aging time and NH3 concentration. Samples with optimum specific surface areas and well ordered-basal spacing were obtained by reaction between 10 min and 40 min in pure water and 0.05% NH3-water solution. Mesoporous samples with narrow pore size distribution were also prepared by reaction for 10-40 min in 0.05% NH3 solution. Rapid interlamellar reaction of TEOS in pure water showed that intercalated octylamine itself could act as a base catalyst during interlamellar polycondensation of TEOS.

• 멤브레인
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• 제27권2호
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• pp.167-181
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• 2017

그래핀 기반 소재는 높은 가공성과 초박성으로 인하여 분리막 소재로서 각광받고 있다. 본 연구에서는, 스핀 코팅법을 이용하여 제조된 산화그래핀 분리막의 기체 투과 거동을 평가하였다. 산화그래핀 분리막의 구조는 산화그래핀의 크기와 산화그래핀 용액의 pH 조절을 통하여 조절될 수 있다. 산화그래핀의 크기가 작을수록 굴곡률이 작아짐에 따라 분리막의 기체 투과도 및 선택도가 증가하는 경향을 보인다. 또한 산화그래핀에서의 기체 투과 거동은 적층된 산화그래핀 사이의 채널크기에 따라 영향을 받는다. 특히 산화그래핀 분리막의 좁은 기공과 이산화탄소 선택적인 산화그래핀 자체의 특성으로 인하여 산화그래핀 분리막은 이산화탄소에 대한 높은 투과도 및 선택성을 가지며, 이는 이산화탄소 포집에 적합한 특성을 가진다. 이러한 산화그래핀 분리막의 특이한 기체 투과 거동은 흡착-촉진 확산 거동(표면 확산 기작)으로 설명될 수 있다. 본 연구를 통하여 이산화탄소 선택성 분리막 소재 설계와 슬릿 형태의 기공과 적층 구조를 가진 분리막을 통한 기체 투과 거동 연구가 활발히 이루어질 것으로 기대한다.

• 공업화학
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• 제29권6호
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• pp.759-764
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• 2018

내재적 미세 다공성 고분자(polymer of intrinsic microporosity, PIM-1)를 사용하여 빈용매 유도 상전이법으로부터 3차원 다공성 구조를 가지는 필름을 형성하고, 이를 탄화하여 3차원 다공성 탄소(cNPIM)를 제조하였다. 전자주사현미경 분석을 통해 상전이 공정을 적용한 탄소소재가 마이크로, 메조, 매크로 기공을 모두 가지면서 서로 연결된 계층적 3차원 다공구조를 나타냄을 확인하였다. 특히 상전이 공정의 용매의 함량비를 조절함으로써 기공구조를 제어할 수 있었으며, 결과적으로 평균 0.75 nm의 기공 크기와 $2101.1m^2/g$의 높은 비표면적을 가지면서 약 30%의 메조, 마크로 기공구조를 겸비한 최적화된 다공성 탄소 전극을 제조할 수 있었다. 제조된 3차원 다공성 탄소소재를 전기이중층 캐퍼시터용 전극물질로 사용하여 수계전해질에서 측정한 결과, 높은 비표면적을 가지는 탄소 소재 내의 비약적 이온 이동속도 향상 효과로 높은 비축전용량(304.8 F/g@10 mV/s)과 우수한 충 방전 속도(77% 용량유지율@100 mV/s)를 나타내었다.

• 한국지반공학회논문집
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• 제28권2호
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• pp.33-42
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• 2012

본 연구에서는 토립자의 입경과 입도분포가 불포화토의 흙-수분특성에 미치는 영향을 검토하고자 하였다. 이를 위해 축이동기법이 적용된 시험장치를 이용하여 현장에서 채취한 새만금실트에 대해 함수특성시험을 실시하였다. 비교를 위해 주문진 표준사에 대해서도 시험을 실시하였다. 시험으로부터 측정된 모관흡수력과 체적함수비를 토대로 van Genuchten 모델에 대한 흙-함수특성곡선을 추정하였다. 추정된 함수특성곡선의 비교분석결과 포화체적함수비, 잔류체적함수비 그리고 공기함입치 모두 모래보다 실트에서 더 높게 나타났으며, van Genuchten 모델의 계수 ${\alpha}$, $n$, $m$ 모두 실트보다 모래에서 더 크게 나타났다. 이는 불포화토의 흙-함수특성곡선은 흙의 구조적 특성(간극크기, 형태, 분포)과 밀접한 관계를 가지며 상대적으로 입경이 크고 입도분포가 불량한(다시 말해, 간극크기가 크고 간극분포가 균등한) 조립토일수록 포화체적함수비, 잔류체적함수비, 그리고 공기함입치가 작고, 모관흡수력 변화에 따른 체적함수비의 변화율이 크며, 따라서 전이 영역의 범위가 좁게 나타나는 경향이 있다는 것을 보여준다.

• Current Photovoltaic Research
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• 제8권1호
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• pp.27-32
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• 2020

CuS thin films were deposited on glass substrates at room temperature by RF magnetron sputtering. The structural and optical properties of CuS thin films grown by varying RF-power from 40 W to 100 W were studied. From the XRD analysis, we confirmed hexagonal crystal structures grown in the preferred orientation of the (110) plane in all CuS thin films, and the intensity of the main diffraction peak increased in proportion to the increase of RF-power. In the case of CuS thin film deposited at 40W, small-sized particles formed a thin and dense surface morphology with narrow pore spacing, relatively. As the power increased, the grain size and grain boundary spacing increased sequentially. The peaks for the binding energy of Cu 2p_3/2 and Cu 2p_1/2 were determined at 932.1 eV and 952.0 eV, respectively. The difference in binding energy for the Cu²⁺ states was the same at 19.9 eV regardless of process parameters. The transmittance and band gap energy in the visible region tended to decrease with increasing sputtering powers.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.167-169
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• 2009

We have carried out quantitative structure and property analysis of the nanoporous structures of low dielectric constant (low-k) carbon-doped silicon oxide (SiCOH) films, which were deposited with plasma enhanced chemical vapor deposition (PECVD) using vinyltrimethylsilane (VTMS), divinyldimethylsilane (DVDMS), and tetravinylsilane (TVS) as precursor and oxygen as an oxidant gas. We found that the SiCOH film using VTMS only showed well defined spherical nanopores within the film after thermal annealing at $450^{\circ}C$ for 4 h. The average pore radius of the generated nanopores within VTMS SiCOH film was 1.21 nm with narrow size distribution of 0.2. It was noted that thermally labile $C_{x}H_{y}$ phase and Si-$CH_3$ was removed to make nanopore within the film by thermal annealing. Consequently, this induced that decrease of average electron density from 387 to $321\;nm^{-3}$ with increasing annealing temperature up to $450^{\circ}C$ and taking a longer annealing time up to 4 h. However, the other SiCOH films showed featureless scattering profiles irrespective of annealing conditions and the decreases of electron density were smaller than VTMS SiCOH film. Because, with more vinyl groups are introduced in original precursor molecule, films contain more organic phase with less volatile characteristic due to the crosslinking of vinyl groups. Collectively, the presenting findings show that the organosilane containing vinyl group was quite effective to deposit SiCOH/$C_{x}H_{y}$ dual phase films, and post annealing has an important role on generation of pores with the SiCOH film.

• 한국분말재료학회지
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• 제8권3호
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• pp.163-167
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• 2001

A bulk porous $CaZrO_3/MgO$ composite with plantinum nano-dispersion was synthesized in air atmosphere through the combination of several in situ reactions, including the pyrolysis of $PtO_2$. A mixture of $CaMg(CO_3)_2$(dolomite), $ZrO_2$, $PtO_2$ and LiF (0.5 wt%, as an additive) was cold isostatically pressed at 200 MPa and sintered at $1100^{\circ}C$ for 2 h. The porous $CaZrO_3/MgO/Pt$ composite ($CaZrO_3/MgO$ : Pt=99 : 1 in volume) had a uniformly open-porous structure (porosity: 56%) with three-dimensional (3-D) network and a narrow pore-size distribution, similarly to the porous $CaZrO_3/MgO$ composites reported before. Catalytic Properties (viz., NO direct decomposition and NO reduction by $C_2H_4$) of the $CaZrO_3/MgO/Pt$ composite were investigated up to $900^{\circ}C$. In the absence of oxygen, the NO conversion rate reached ~52% for the direct decomposition and ~100% for the reduction by $C_2H_4$, respectively. The results suggest the possibility of the porous composite as a multifunctional filter, i.e., simultaneous hot gas-filtering and $de-NO_x$ in one component.

• 한국재료학회지
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• 제10권12호
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• pp.845-852
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• 2000

국내산 kaolinite를 소성한 다음 실리카를 선택적으로 추출하여 중기공성 ${\gamma}-Al_2O_3$를 제조하였다. $1000^{\circ}C$에서 24시간 소성된 kaolinite는 소량의 무정형 실리카와 ${\gamma}-Al_2O_3$으로 이루어진 스피넬 상의 미세구조로 전이되었음을 확인하였다. 다공성 ${\gamma}-Al_2O_3$는 $25~90^{\circ}C$의 반응온도, 0.5~4h의 추출시간 및 1~8M의 KOH 농도범위에서 무정형 실리카를 선택적으로 용해하여 제조할 수 있었다. $90^{\circ}C$, 1시간 및 4M의 KOH 농도조건에서 얻어진 ${\gamma}-Al_2O_3$는 약 $40~80{\AA}$ 정도의 매우 좁은 하나의 기공크기 분포를 가지고 있었으며, mesopore의 기공이 많이 생성되었다. 비표면적은 $250\textrm{m}^2/g$이고, 총 기공부피는 $0.654\textrm{cm}^3/g$로 나타났다.

• 전기화학회지
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• 제7권3호
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• pp.131-137
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• 2004

Sol-gel method which provides better electrochemical and physiochemical properties compared to the solid-state method was used to synthesize the material of $LiFe_yMn_{2-y}O_4$. Fe was substituted to increase the structural stability so that the effects of the substitution amount and sintering temperature were analyzed. XRD was used for the structural analysis of produced material, which in turn, showed the same cubic spinel structure as $LiMn_2O_4$ despite the substitution of $Fe^{3+}$. During the synthesis of $LiFe_yMn_{2-y}O_4$, as the sintering temperature and the doping amount of Fe(y=0.05, 0.1, 0.2)were increased, grain growth proceeded which in turn, showed a high crystalline and a large grain size, certain morphology with narrow specific surface area and large pore volume distribution was observed. In order to examine the ability for the practical use of the battery, charge-discharge tests were undertaken. When the substitution amount of $Fe^{3+}\;into\;LiMn_2O_4$ increased, the initial discharge capacity showed a tendency to decrease within the region of $3.0\~4.2V$ but when charge-discharge processes were repeated, other capacity maintenance properties turned out to be outstanding. In addition, when the sintering temperature was $800\~850^{\circ}C$, the initial capacity was small but showed very stable cycle performance. According to EVS(electrochemical voltage spectroscopy) test, $LiFe_yMn_{2-y}O_4(y=0,\;0.05,\;0.1,\;0.2)$ showed two plateau region and the typical peaks of manganese spinel structure when the substitution amount of $Fe^{3+}$ increased, the peak value at about 4.15V during the charge-discharge process showed a tendency to decrease. From the previous results, the local distortion due to the biphase within the region near 4.15V during the lithium extraction gave a phase transition to a more suitable single phase. When the transition was derived, the discharge capacity decreased. However the cycle performance showed an outstanding result.