• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2067-2072
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• 2013

Hydrogen ($H_2$) treatment using a two-step $TiO_2$ nanotube (TONT) film was performed under various annealing temperatures from $350^{\circ}C$ to $550^{\circ}C$ and significantly influenced the extent of hydrogen treatment in the film. Compared with pure TONT films, the hydrogen-treated TONT (H:TONT) film showed substantial improvement of material features from structural, optical and electronic aspects. In particular, the extent of enhancement was remarkable with increasing annealing temperature. Light absorption by the H:TONT film extended toward the visible region, which was attributable to the formation of sub-band-gap states between the conduction and valence bands, resulting from oxygen vacancies due to the $H_2$ treatment. This increased donor concentration about 1.5 times higher and improved electrical conductivity of the TONT films. Based on these analyses and results, photoelectrochemical (PEC) performance was evaluated and showed that the H:TONT film prepared at $550^{\circ}C$ exhibited optimal PEC performance. Approximately twice higher photocurrent density of 0.967 $mA/cm^2$ at 0.32 V vs. NHE was achieved for the H:TONT film ($550^{\circ}C$) versus 0.43 $mA/cm^2$ for the pure TONT film. Moreover, the solar-to-hydrogen efficiency (STH, ${\eta}$) of the H:TONT film was 0.95%, whereas a 0.52% STH efficiency was acquired for the TONT film. These results demonstrate that hydrogen treatment of TONT film is a simple and effective tool to enhance PEC performance with modifying the properties of the original material.

• 마이크로전자및패키징학회지
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• 제8권2호
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• pp.25-29
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• 2001

본 연구에서는 mesocarbon microbeads(MCMB)카본에 에폭시 수지(resin)를 코팅시킴으로 서 카본전극 표면개질에 따른 전지 성능의 개선효과에 관하여 고찰하였다. 에폭시 수지에 의한 카본의 표면코팅은 MCMB 분말을 에폭시 수지가 용해된 THF(tetrahydrofuran)용액에 넣어 혼합함으로서 표면에 에폭시 수지가 코팅 되도록 하였다. 이렇게 에폭시 수지가 코팅된 MCMB를 $1000^{\circ}C$이상의 온도로 열처리하여 고분해능 투과전자현미경으로 관찰한 결과, 코팅층은 비정질 카본 구조를 지님을 알 수 있었다. 또한, 에폭시 수지에 의하여 코팅된 MCMB는 코팅되지 않은 MCMB보다 더 높은 BET비 표면적을 나타내었으며, 더 우수한 충방전 용량과 싸이클 특성을 나타내었다. 카본표면에 코팅된 에폭시 수지가 얇은 비정질 막으로 표면에 존재함으로서 전해질과 카본결정과의 반응을 억제시키는 방지막 역할을 하기 때문에 전지특성이 개선된 것으로 해석된다.

• Geomechanics and Engineering
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• 제33권1호
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• pp.29-40
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• 2023

Xanthan gum and starch compound biopolymer (XS), an environmentally friendly soil-binding material produced from natural resources, has been suggested as a slope protection material to enhance soil strength and erosion resistance. Insufficient wet strength and the consequent durability concerns remain, despite XS biopolymer-soil treatment showing high strength and erosion resistance in the dried state, even with a small dosage of soil mass. These concerns need to be solved to improve the field applicability and post-stability of this treatment. This study explored the utilization of an alkaline-based cation crosslinking method using calcium hydroxide and sodium hydroxide to induce non-thermal gelation, resulting in the enhancement of the wet strength and durability of biopolymer-treated soil. Laboratory experiments were conducted to assess the unconfined compressive strength and cyclic wetting-drying durability performance of the treated soil using a selected recipe based on a preliminary gel formation test. The results demonstrated that the uniformity of the gel structure and gelling time varied depending on the ratio of crosslinkers to biopolymer; consequently, the strength of the soil was affected. Subsequently, site soil treated with the recipe, which showed the best performance in indoor assessment, was implemented on the field slope at the bridge abutment via compaction and pressurized spraying methods to assess feasibility in field implementation. Moreover, the variation in surface soil hardness was monitored periodically for one year. Both slopes implemented by the two construction methods showed sufficient stability against detachment and scouring, with a higher soil hardness index than the natural slope for a year.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.276-276
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• 2012

The interface morphology of organic active layers is known to play a crucial role in the performance of organic photovoltaic (OPV) cells. Especially, a controlled nanostructure with a large contact area between electron donor (D) and acceptor (A) layers is necessary to improve the power conversion efficiency (PCE) of the cells since the short exciton diffusion lengths in organic semiconductors limit the charge (hole and electron) separation before excitons recombination. In this work, we developed simple solvent treating methods to fabricate a nanostructured DA interface and applied them to enhance the PCE of ZnPc/C60 based small molecule OPV cells. Interestingly, it was observed that the solvent treatment on the donor layer prior to the deposition of the acceptor layer resulted in a significant decrease in PCE, which was due to an existence of undesirable voids at the DA interface. Instead, the solvent vapor treatment after the DA bilayer formation led to densely packed and well dispersed DA contacts. Consequently, 3-fold enhancement of PCE as compared to the untreated bilayer cell was accomplished.

• Journal of Welding and Joining
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• 제35권3호
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• pp.15-20
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• 2017

In this paper, two types of assemblies using CNT-filled SACAs (with 0.03 wt% CNTs and without CNT) were prepared to investigate the influence of carbon nanotubes (CNTs) on the reliability properties of solderable anisotropic conductive adhesives (SACAs) with a low-melting-point alloy (LMPA). Two types of reliability test including thermal shock (TS: -55 to $125^{\circ}C$, 1000 cycles) and high-temperature and high-humidity (HTHH: $85^{\circ}C$, 85% RH, 1000 h) tests were conducted. The SACA assemblies with and without CNTs showed stable electrical reliability properties due to the formation of wide and stable metallurgical interconnection between corresponding metallizations by the molten LMPA fillers. Although the mechanical pull strength of CNT-filled SACA assemblies was decreased after thermal aging (because of the excessive layer growth and planarization of the IMCs), the CNT-filled SACA with 0.03wt% CNTs showed enhanced mechanical reliability properties compared with the SACA assemblies no CNTs. This enhancement in mechanical performance was due to the reinforcement effect of the CNTs. These results demonstrate that CNTs within the CNT-filled SACAs can improve the reliability properties of CNT-filled SACAs joints due to their superior physical properties.

• 한국전기전자재료학회논문지
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• 제33권6호
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• pp.495-499
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• 2020

Power factor improvement at high temperatures has been a major research topic for the development of skutterudite thermoelectric materials. Here, we attempted to optimize the process parameters for manufacturing skutterudite materials, especially for p-type systems. We focused on the effect of aging time variation to maximize the high-temperature performance of the Ce-filled Fe³CoSb¹² skutterudite system. The optimized aging time was concluded to be a key parameter for the formation of single-phase nanostructures in this p-type skutterudite system. The optimized condition was effective in reducing the bipolar effect at high temperature ranges by increasing the carrier concentration in the p-type system. To confirm the conclusions, the electrical conductivity, Seebeck coefficient, and power factor were measured. The results matched well with the microstructure and with those of an XRD analysis performed for the system.

• Membrane and Water Treatment
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• 제10권6호
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• pp.451-460
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• 2019

Thin film composite membranes incorporated with nano-sized hydrophilic zeolite -A were successfully prepared via interfacial polymerization (IP) on porous blend PES/PAN support for water desalination. The thin film nanocomposite membranes were characterized by SEM, contact angle and performance test with 7000 ppm NaCl solution at 7bar. The results showed that the optimum zeolite loading amount was determined to be 0.1wt% with permeate flux 29LMH.NaCl rejection was improved from 69% to 92% compared to the pristine polyamide membrane where the modified PA surface was more selective than that of the pristine PA. In addition, there was no significant change in the permeate flux of the thin film nanocomposite membrane compared with that of the pristine PA in spite of the formation of the dense polyamide layer. The stability of the polyamide layer was investigated for 15 days and the optimized membrane presented the highest durability and stability.

• Journal of Microbiology and Biotechnology
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• 제34권8호
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• pp.1711-1717
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• 2024

This study evaluates the efficacy of a decellularized intestine tissue-derived extracellular matrix (Intestine ECM) as a scaffold for culturing colorectal cancer (CRC) organoids and establishing cell-derived xenograft (CDX) models, comparing its performance to traditional Matrigel. Intestine ECM demonstrates comparable support for organoid formation and cellular function, highlighting its potential as a more physiologically relevant and reproducible platform. Our findings suggest that Intestine ECM enhances the mimetic environment for colon epithelium, supporting comparable growth and improved differentiation compared to Matrigel. Moreover, when used as a delivery carrier, Intestine ECM significantly increases the growth rate of CDX models using patient-derived primary colorectal cancer cells. This enhancement demonstrates Intestine ECM's role not only as a scaffold but also as a vital component of the tumor microenvironment, facilitating more robust tumorigenesis. These findings advocate for the broader application of Intestine ECM in cancer model systems, potentially leading to more accurate preclinical evaluations and the development of targeted cancer therapies.

• Nuclear Engineering and Technology
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• 제26권4호
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• pp.484-492
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• 1994

Nb$_2$O$_{5}$가 첨가된 $UO_2$ 소결체의 미세조직을 수소와 이산화탄소 분위기에서 연구하였다. Pellet을 1$700^{\circ}C$ 수소분위기 그리고 130$0^{\circ}C$ 이산화탄소 분위기에서 1-41 시간 동안 소결하였다. Nb$_2$O$_{5}$를 첨가하면 큰 기공들이 형성되고, 이 기공들은 수소분위기에서는 어느정도 수축하지만 이산화탄소 분위기에서는 거의 소멸하지 않는다. 작은 기공들은 수소분위기에서는 거의 전부 소멸되며 이산화탄소 분위기에서는 거의 소멸하지 않는다. 그리고 결정립의 크기도 수소분위기에서 훨씬 증대한다. 따라서 Nb$_2$O$_{5}$ 첨가에 의한 우라늄 확산은 수소분위기에서 훨씬 증가하는 것으로 생각된다. 수소 분위기에서 소결한 Nb$_2$O$_{5}$ 첨가 $UO_2$ pellet의 미세조직을 노내성능의 관점에서 평가하였다. 우라늄 확산의 증가를 설명하기 위해서 Nb$_2$O$_{5}$ 첨가에 의해서 형성 가능한 결함들을 고찰하였다.함들을 고찰하였다.

• 한국재료학회지
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• 제24권1호
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• pp.37-42
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• 2014

Well-distributed ruthenium (Ru) nanoparticles decorated on porous carbon nanofibers (CNFs) were synthesized using an electrospinning method and a reduction method for use in high-performance elctrochemical capacitors. The formation mechanisms including structural, morphological, and chemical bonding properties are demonstrated by means of field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). To investigate the optimum amount of the Ru nanoparticles decorated on the porous CNFs, we controlled three different weight ratios (0 wt%, 20 wt%, and 40 wt%) of the Ru nanoparticles on the porous CNFs. For the case of 20 wt% Ru nanoparticles decorated on the porous CNFs, TEM results indicate that the Ru nanoparticles with ~2-4 nm size are uniformly distributed on the porous CNFs. In addition, 40 wt% Ru nanoparticles decorated on the porous CNFs exhibit agglomerated Ru nanoparticles, which causes low performance of electrodes in electrochemical capacitors. Thus, proper distribution of 20 wt% Ru nanoparticles decorated on the porous CNFs presents superior specific capacitance (~280.5 F/g at 10 mV/s) as compared to the 40 wt% Ru nanoparticles decorated on the porous CNFs and the only porous CNFs. This enhancement can be attributed to the synergistic effects of well-distributed Ru nanoparticles and porous CNF supports having high surface area.