• 한국운동역학회지
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• 제18권4호
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• pp.49-57
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• 2008

이 연구는 고령자를 대상으로 탄성저항운동을 수행하였을 경우 운동 전 후로 보행 시 지면반력 신호 크기와 이들의 variability에 어떠한 영향을 미치는 가를 구명하고자 하였다. 이를 위하여 여성 고령자 12명을 대상으로 12주간 탄성저항운동을 실시하였으며, 운동 전 후로 보행 시 3방향 지면반력 신호의 주파수 크기와 variability 값을 산출하였다. FFT(fast Fourier transform)를 이용하여 주파수 분석을 하였으며, PSD(power spectral density)를 계산하였다. 총 대상자들의 변이 계수(SD/Mean*100)을 이용하여 집단 간 variability를 계산하였다. 그 결과 다음과 같은 결론을 얻었다. 지면반력 신호의 주파수 크기는 좌우 방향에서 운동 전보다 운동 후에 작은 값을 보였으며, 통계적으로도 유의한 차이(p<.05)가 나타났다. 지면반력 신호의 variability에서는 좌우 방향에서 운동 전보다 운동 후에 큰 값이 나타났으며, 통계적으로도 유의한 차이(p<.05)가 나타났다.

• 대한약학회:학술대회논문집
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• 대한약학회 2001년도 Proceedings of the Pharmaceutical Society of Korea
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• pp.187.3-188
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• 2001

• 한국재료학회:학술대회논문집
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• 한국재료학회 2000년도 추계학술발표강연 및 논문개요집
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• pp.96-96
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• 2000

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.192-192
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• 2011

Hyperthermal ion scattering experiments were conducted with low kinetic energy (<35 eV) cesium ion beams to analyze the UV-photolyzed water-ice films. Neutral molecules (X) on the surface were detected as cesium-molecule ion clusters ($CsX^+$) which were formed through a Reactive Ion Scattering (RIS) process. Ionic species on the surface were desorbed from the surface via a low energy sputtering (LES) process, and were analyzed [1]. Using these methods, the thermal stability of hydronium ion ($H_3O^+$) that was produced by UV light was examined. As the thermal stability of $H_3O^+$ is related with the reaction, $H_3O^+$ + OH + $e^-$ (or $OH^-$) ${\rightarrow}$ $2H_2O$, which is similar or same with the reverse reaction of the auto-ionization of water, the result from this work would be helpful to understand the auto-ionization of $H_2O$ in water-ice that has not been well-understood yet. However, as $H_3O^+$ was not detected through a LES method, the titration experiment of $H_3O^+$ with methylamine ($CH_3NH_2$, MA), MA + $H_3O^+\;{\rightarrow}\;MAH^+$ + $H_2O$, was conducted. In this case, the presence of $MAH^+$ indicates that of $H_3O^+$ in the ice. Thus the pristine ice was photolyzed with UV light for a few minutes and this photolyzed ice was remained at the certain temperature for minutes without UV light. Then MA was adsorbed on that surface so that the population of $H_3O^+$ was found. From the calibration experiments, the relation of $MAH^+$ and $H_3O^+$ was found, so that the thermal stability of $H_3O^+$ can be investigated [2].

• 대한스포츠의학회지
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• 제36권4호
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• pp.207-213
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• 2018

Purpose : The aim of this study was to investigate the effects of foot position on dynamic stability in female with genu varum. M ethods: Eight females with genu varum participated in this study and performed the four squat exercise methods that foot position ($-45^{\circ}$, $0^{\circ}$, $+45^{\circ}$) and $0^{\circ}$ squat with band. Center of pressure (COP; anterior-posterior, medial-lateral, traveled distance, ellipse area) and ground reaction force as dynamic stability were measured using footscan system. Multivariate analysis of variance and one-way repeated analysis of variance measurement with Tukey honestly significant difference were used to identify significant differences of foot angle ($-45^{\circ}$, $0^{\circ}$, $+45^{\circ}$) and $0^{\circ}$ squat with band method. Results: In anterior-posterior COP displacement, $-45^{\circ}$ foot angle and $0^{\circ}$ squat with band were significantly showed lower than $+45^{\circ}$ foot angle squat (p=0.006). Also, in COP traveled distance, $0^{\circ}$ squat was significantly showed lower than $+45^{\circ}$ foot angle (p=0.019). During the descending phase, ground reaction force significantly showed in -45 foot angle was lower than other exercise methods. Conclusion: The $0^{\circ}$ squat with band exercise showed higher dynamic stability and $+45^{\circ}$ foot angle squat exercise showed lower dynamic stability in female with genu varum.

• 한국세라믹학회지
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• 제42권9호
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• pp.637-644
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• 2005

In order to find a proper buffering material which can prohibit an unwanted interfacial reaction between anode and electrolyte of LSGM-based SOFC, we examined a gadolinium doped ceria and scandium doped zirconia as a candidate. For this examination, we investigated the microstructural and phase stability of the interface under different buffering layer conditions. According to the investigation, ceria based material induced a serious La diffusion out of the LSGM electrolyte resulted in the formation of very resistive $LaSrGa_3O_7$ phase at the interface. On the other hand zirconia based material was directly reacted with LSGM electrolyte and thus produced very resistive reaction products such as $La_2Zr_2O_7,\;Sr_2ZrO_4,\;LaSrGaO_4\;and\;LaSrGa_3O_7$. From this study we found that an improper buffering material induced the higher internal cell resistance rather than an interfacial stability.

• 공업화학
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• 제31권3호
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• pp.328-333
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• 2020

본 연구에서는 PFO와 Coal-tar의 구조와 열 중합 거동 분석을 통해 PFO와 Coal-tar으로 구성된 혼합 원료의 피치 합성 간 제조 특성을 확인하였다. 원소분석과 FT-IR 분석을 통해, PFO와 Coal-tar 각각 0.355, 0.818로 방향족화도 수치를 확인하였다. 또한, PFO와 Coal-tar의 열중량 분석을 통해 질량 감소곡선의 차이를 확인하였으며, 이러한 현상은 방향족 화도와 관능기 함량에 따른 구조적 안정성에 기인한 것으로 판단된다. 피치 제조 특성은 PFO를 원료로 사용한 피치가 혼합원료로부터 제조된 피치보다 평균적으로 낮은 수율과 높은 연화점을 보임을 확인하였다. 특히 유사한 연화점을 가지는 P360 (138.5 ℃)과 B420 (141.4 ℃)을 비교하였을 때, 두 피치의 탄화수율은 각각 29.89, 49.03 wt%로 Coal-tar가 혼합된 경우 약 20 wt% 향상됨을 확인하였다. 이러한 결과는 다량의 알킬기를 포함하여 높은 피치 중합 반응성을 가지는 PFO와 높은 열적 안정성을 가지는 Coal-tar의 혼합에 기인한 것으로 판단된다.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.697-700
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• 2008

본 연구에서는 개미산 연료전지의 연료극에서 Pt 촉매의 안정성과 활성을 높이기 위해 Bi를 UPD법을 이용하여 Pt 촉매 위에 증착시켰다. 증착된 Bi의 활용도를 높이기 위해 다층 전극구조를 적용하였으며, 전자탐침미세분석(EPMA) 결과에서 Bi가 장기성능 실험동안 촉매층에 안정적으로 존재하는 것을 확인할 수 있었다. 연료전지 성능실험에서는 Pt black 촉매 위에 Bi를 UPD한 다층 구조의 전극이 PtRu black 촉매보다 전류밀도 $150mA/cm^2$에서 약 200 mV정도 높은 성능을 나타냈다. Pt black을 40% Pt/C로 대체했을 경우 역시 높은 성능과 장기 안정성을 보였다.

• Food Science and Biotechnology
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• 제16권1호
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• pp.127-132
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• 2007

[ ${\alpha},\;{\alpha}$ ]-Trehalose was efficiently modified by a transgalactosylation reaction of Escherichia coli ${\beta}-galactosidase$ using lactose as a donor to yield two galactosyl trehalose trisaccharides. The reaction products of trehalose by the enzyme were observed by thin layer chromatography (TLC) and high performance anion exchange chromatography (HPAEC) and were purified by BioGel P2 gel permeation chromatography and recycling preparative HPLC. Liquid chromatography-mass spectrometry (LC-MS) and ^{13}C$ nuclear magnetic resonance (NMR) analyses revealed that the structures of the main products were $6^2-{\beta}-D-galactosyl$ trehalose (1) and $4^2-{\beta}-D-galactosyl$ trehalose (2). A reaction of 30%(w/v) trehalose and 15%(w/v) lactose at pH 7.5 and $45^{\circ}C$ resulted in a total yield of approximately 27-30% based on the amount of trehalose used. The galactosyl trehalose products were not hydrolyzed by trehalose. In addition the mixture of transfer products (9:1 ratio of 1 to 2) showed higher thermal stability than glucose, lactose, and maltose, but less than trehalose, against heat treatment over $100^{\circ}C$ at pH 4 and 7. It also exhibited better thermal stability than sucrose at pH 4 alone.

• Journal of Microbiology and Biotechnology
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• 제31권3호
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• pp.419-428
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• 2021

To efficiently recycle GH78 thermostable rhamnosidase (TpeRha) and easily separate it from the reaction mixture and furtherly improve the enzyme properties, the magnetic particle Fe3O4-SiO2-NH2-Cellu-ZIF8 (FSNcZ8) was prepared by modifying Fe3O4-NH2 with tetraethyl silicate (TEOS), microcrystalline cellulose and zinc nitrate hexahydrate. FSNcZ8 displayed better magnetic stability and higher-temperature stability than unmodified Fe3O4-NH2 (FN), and it was used to adsorb and immobilize TpeRha from Thermotoga petrophilea 13995. As for properties, FSNcZ8-TpeRha showed optimal reaction temperature and pH of 90℃ and 5.0, while its highest activity approached 714 U/g. In addition, FSNcZ8-TpeRha had better higher-temperature stability than FN. After incubation at 80℃ for 3 h, the residual enzyme activities of FSNcZ8-TpeRha, FN-TpeRha and free enzyme were 93.5%, 63.32%, and 62.77%, respectively. The organic solvent tolerance and the monosaccharides tolerance of FSNcZ8-TpeRha, compared with free TpeRha, were greatly improved. Using naringin (1 mmol/l) as the substrate, the optimal conversion conditions were as follows: FSNcZ8-TpeRha concentration was 6 U/ml; induction temperature was 80℃; the pH was 5.5; induction time was 30 min, and the yield of products was the same as free enzyme. After repeating the reaction 10 times, the conversion of naringin remained above 80%, showing great improvement of the catalytic efficiency and repeated utilization of the immobilized α-L-rhamnosidase.