• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.550-557
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• 2013

A glucose hydrothermal method is described for preparing hollow carbon spheres (HCS), which have a regular morphology and a high Brunauer-Emmett-Teller surface area of 28.6 m2/g. Scanning electron microscopy shows that they have thin shells and diameter between 2 and 8 ${\mu}m$. The HCSs were modified for the enhanced room temperature hydrogen storage by employing Ni nanoparticles on their surface. The Ni-decorated HCSs were characterized by X-ray diffraction, transmission electron microscopy coupled with an energy dispersive spectroscope, and an inductively coupled plasma spectrometer, indicating that fine and well-distributed Ni nanoparticles can be accomplished on the HCSs. The hydrogen uptake capacity in HCSs with and without Ni loading was evaluated using a high-pressure microbalance at room temperature under a hydrogen pressure upto 9 MPa. As much as 1.23wt.% of hydrogen can be stored when uniformly distributed Ni nanoparticles are formed on the HCSs, while the hydrogen uptake capacity of as-received HCSs was 0.41 wt.%. For Ni nanoparticle-loaded HCSs, hydrogen molecules could be easily dissociated into atomic hydrogen and then chemically adsorbed by the sorbents, leading to an enhanced capacity for storing hydrogen.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.218-222
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• 2002

In the recognition of the gases using the quartz crystal microbalance (QCM) coated with the PEG film materials, it is important to obtain the recognition ability of gases, and the stability of PEG film coated above the QCM. Especially, the thickness of PEG film coated above the QCM is decreased according with the using circumstance and time of QCM gas sensor. Therefore, the sensing characteristics of PEG film is changed with these. In this paper, we coated the PEG materials varing with the blended amount of PVC(Poly Vinyl Chloride) and chloroform above QCM to obtain the sensitive and the stability of PEG film. We measured the degradation characteristics of QCM gas sensor in the ethyle acetate 50[%] concentration to show the properties of stability.

• 한국전기화학회:학술대회논문집
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• 2002.11a
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• pp.57-65
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• 2002

The presence of tetragonal phase at the surface of $LiMn_2O_4$ pinicle due to a Jahn-Teller offset was previously reported to be one of the causes for capacity fading observed during cycling of $Li//Li_xMn_2O_4$ in 4V range. Further, it is reported that a Jahn-Teller effect in 4V range may be suppressed by substitution of Mn ions with Li ions or other transition metal ions. However, the direct evidence of the suppression of a Jahn-Teller effect in 4V range by substitution of Mn ions with other metal ions has not been reported. The dissolution and formation of surface film at the surface of $LiMn_2O_4$ electrodes also reportedly affect the capacity fading or rate capability. This study reports on the evidence of the onset and suppression of a Jahn-Teller effect in 4V range and the dissolution and formation of surface film at the surface of $LiMn_2O_4$ thin film electrodes using in situ bending beam method (BBM) in situ electrochemical quartz crystal microbalance (EQCM).

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.80-80
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• 2018

실리콘 관통전극 (Through Silicon Via, TSV)는 메모리 칩을 적층하여 고밀도의 집적회로를 구현하는 기술로, 기존의 와이어 본딩 (Wire bonding) 기술보다 낮은 소비전력과 빠른 속도가 특징인 3차원 집적기술 중 하나이다. TSV는 일반적으로 도금 공정을 통하여 충전되는데, 고종횡비의 TSV에 결함 없이 구리를 충전하기 위해서 3종의 유기첨가제(억제제, 가속제, 평탄제)가 도금액에 첨가되어야 한다. 이러한 첨가제 중 결함 발생유무에 가장 큰 영향을 주는 첨가제는 평탄제이기 때문에, 본 연구에서는 이미다졸(imidazole) 계열, 이민(imine) 계열, 디아조늄(diazonium) 계열 및 피롤리돈(pyrrolidone) 계열과 같은 평탄제(leveler)의 작용기에 따라 TSV 충전 성능을 조사하였다. TSV 충전 시 관능기의 거동을 규명하기 위해 QCM (quartz crystal microbalance) 및 EQCM (electrochemical QCM)을 사용하여 흡착 정도를 측정하였다. 실험 결과, 디아조늄 계열의 평탄제는 TSV를 결함 없이 충전하였지만 다른 작용기를 갖는 평탄제는 TSV 내 결함이 발생하였다. QCM 분석에서 디아조늄 계열의 평탄제는 낮은 흡착률을 보이지만 EQCM 분석에서는 높은 흡착률을 나타내었다. 즉, 디아조늄 계열의 평탄제는 전기 도금 동안 전류밀도가 집중되는 TSV의 상부 모서리에서 국부적인 흡착을 선호하며 이로 인하여 무결함 충전이 달성된다고 추론할 수 있다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.403-406
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• 2002

Molecular self-assembled of surfactant viologen are of recent interest because they can from functional electroeds as well as micellar assemblies. which can be profitably utilized for display devices. photoelectrochemical studies and electrocatalysis as electron acceptor or electron mediator[1-3]. Fromherz et al studied the se1f-assembly of thiol and disulfide derivatives of viologens bearing long n-alkyl chains on Au electrode surface[4]. In this study, the electrochemical behavior of self-assembled viologen monolayer has been investigated with QCM, which has been known as nano-gram order mass detector. The self-assembly process of viologen was monitored using resonant frequency$({\Delta}F)$ and resonant resistance(R). The redox process of viologen was observed with resonant frequency$({\Delta}F)$.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1321-1326
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• 2008

A study on the heat and mass transfer for the drying time in spray freezing drying process was experimentally presented in this paper. A spray freezing dryer for the production of an inhalable powder medicine is developed and an albumin solution as protein specimen is adopted. The freeze-drying for the albumin solution is tested in three different height of the particles piled up in a tray such as 2 mm, 5 mm, 7 mm, and the drying time is estimated as 10 h, 15 h, 22 h. From this results, the correlation is suggested and the drying time with various height of the particles piled up in a tray can be estimated. The assessment on the drying time is conducted thought a microbalance and the rate of water content is measured. The results based on temperature and weight are compared. The difference of the results happens due to the heat transfer from the lateral side of the vial. It is thought that the better estimation in drying time can be predicted by considering the heat transfer effect.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1364-1366
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• 1994

In this paper, the monolayers of the polymers which polyion-complexed with PAA at the air-water interrace can be transferred on to solid substrates such as porous fluorocarbon membranes filter and quartz crystal microbalance. The properties of the monolayers and the LB films investigated by ${\pi}-A$ isotherms, FT-IR, DSC, deposition ratio, QCM, and SEM will be discussed. In addition, it was attempted to investigated the surface characterics of polymer/metal compound LB films in the air/water interface.

• Journal of Microbiology and Biotechnology
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• v.22 no.6
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• pp.849-855
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• 2012

Plant growth-promoting rhizobacteria (PGPR) pseudomonads have a large number of lipopolysaccharides on the cell surface, which induces immune responses. Cd-resistant PGPR prevalent at the Cd-affected sites under biophytostabilization was monitored. Transmissiom electron microscopy was used to the study the behavior of tolerance of PGPR to cadmium level and its effect on pseudomonad strains (Z9, S2, KNP2, CRPF, and NBRI). An immunosensor was developed by immobilizing antibody (anti-Z9 or anti-S2) against selected PGPR on a piezoelectric quartz crystal microbalance (QCM). Immunosensors were found to supplement the inherent specificity of antigen-antibody reactions with the high sensitivity of a physical transducer. On comparison of the efficiency of detection with ELISA, the spectrophotometric technique, the developed immunosensor was found to be more sensitive, fast, and reliable even after regeneration for several times. Thus, the immunosensor may be used for future detection of PGPR strains after automation of the screening process.

• Journal of the Korean institute of surface engineering
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• v.37 no.4
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• pp.220-225
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• 2004

A new ion beam extraction system is designed using a simple ion mass filter and a micro mass balance and a QMS based detecting system. A quadrupole Mass Filter is used for selective ion beam formation from inductively coupled high density plasma sources with appropriate electrostatic lens and final analyzing QMS. Also a quartz crystal microbalance is set between a QMF and a QMS to measure the etching and polymerization rate of the mass selected ion beam. An inductively coupled plasma was used as a ion/radical source which had an electron temperature of 4-8 eV and electron density of $4${\times}$10^{11}$＃/㎤. A computer interfaced system through 12bit AD-DA board can control the pass ion mass of the qmf by setting RF/DC voltage ratio applied to the quadrupoles so that time modulation of pass ion's mass is possible. So the direct measurements of ion - surface chemistry can be possible in a resolution of $1\AA$/sec based on the qcm's sensitivity. A full set of driving software and hardware setting is successfully carried out to get fundamental plasma information of the ICP source and analysed $Ar^{+}$ beam was detected at the $2^{nd}$ QMS.

• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.55-59
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• 1998

The water absorption in protective coatings, which may greatly influence the durability of these coatings, was studied using quartz crystal microbalance and electrochemical impedance technique. The water absorption in protective coatings and the change of coating capacitance with concentration of electrolyte were measured. The water absorption in coatings seems to be driven by osmotic pressure, and larger amount of water was absorbed in thinner coatings at initial stage of absorption. The amount of water absorbed in coatings changed with the type and crosslinking density of resin used in coating formulation. When water absorption and desorption of coating occured by exposing the coatings to electrolyte solutions of different concentration, increase in impedance caused by desorption of water was found to be higher in the case of thinner film.