• Membrane Journal
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• v.15 no.3
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• pp.247-254
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• 2005

Chitosan film has potential applications in agriculture, food, and pharmacy. However, films made only from chitosan lack gas barrier and have poor mechanical properties. For enhanced gas barrier and mechanical properties, chitosan/clay nanocomposites have been prepared with montmorillonite (MMT) which is a layered structure of clays and chitosan. The cationic biopolymer, chitosan is intercalated into $Na^+-montmorillonite$ through cationic exchange and hydrogen bonding process. Diluted acetic acid is used as solvent f3r dissolving and dispersing chitosan. Chitosan was intercalated or exfoliated in MMT and it was confirmed by X-ray diffraction method. D-spacing of the characteristic peak from MMT plate in chitosan/clay nanocomposites was moved and diminished. The thermal stability and the mechanical properties of the nanocomposites are measured by TGA and Universal Testing Machine. Gas permeability through the chitosan/clay nanocomposites films decreased due to increased tortuosity made by intercalation of clay in chitosan.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.388-393
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• 2013

The study was focused to evaluate the possibility for combination membrane of bacterial cellulose (BC) and graphene with high electrical properties. BC with natural polymer matrix was known to have strong physical strength. For the combination of graphene with BC, the surface of graphene was modified with oxygen plasma by changing strength and time of radio waves in room temperature. Water contact angle of modified graphene grew smaller from $130^{\circ}$ to $12^{\circ}$. XPS analysis showed that oxygen content after treatment increased from 2.99 to 10.98%. Damage degree of graphene was examined from $I_D/I_G$ ratio of Raman analysis. $I_D/I_G$ ratio of non-treated graphene (NTG) was 0.11, and 0.36 to 0.43 in plasma treated graphene (PTG), increasing structural defects of PTG. XRD analysis of PTG membrane with BC was $2{\theta}$ same to BC only, indicating chemically combined membrane. In FT-IR analysis, 1,000 to 1,300 $cm^{-1}$ (C=O) peak indicating oxygen radicals in PTG membrane had formed was larger than NTG membrane. The results suggest that BC as an alternation of plastic material for graphene combination has a possibility in some degree on the part like transparent conductive films.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.51-58
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• 2014

Genetic diversity and genetic structures were estimated in seven natural populations of Phellodendron amurense Rupr in South Korea using ISSR markers. The average of polymorphic loci per primer and the proportion of polymorphic loci per population were 4.5 and 78.8% respectively with total 27 polymorphic loci from 6 ISSR primers. The Shannon's diversity index(I) was 0.421 and the expected heterozygosity($H_e$) was 0.285, which was similar to the heterozygosity (hs =0.287) inferred by Bayesian method. In AMOVA, 7.6% of total genetic variation in the populations was resulted from the genetic difference among populations and the other 92.4% was resulted from the difference among individuals within populations. Genetic differentiation(${\theta}^{II}$) and inbreeding coefficient(f) for total population were estimated to be 0.066 and 0.479 by Bayesian method respectively. In Bayesian clustering analysis, seven populations were assigned into three groups. This result was similar to the results of genetic relationships by UPGMA and PCA. The first group included Hwachoen, Gapyeong, Bongpyeong and Yongpyeong population, and the second included two populations in Sancheong region. Muju population was discretely assigned into the third group in spite of the geographically short distance from the Sancheong region. There was no significant correlation between genetic relationship and geographic distribution among populations in Mantel's test. For conservation of the phellodendron trees, it would be effective to consider the findings resulted from this study with ecological traits and life histories of this species.

• Applied Biological Chemistry
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• v.26 no.2
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• pp.137-142
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• 1983

Starch granules of sweet potatoes, the Suwon 147 and the Chunmi were observed by photomicroscope and scanning electron microscope were round and polygonal. Granule sizes of the Suwon 147 and the Chunmi were $14{\sim}30{\mu}m,\;16{\sim}34{\mu}m$, respectively. X-ray diffraction pattern of starch granules resulted weak crystallinity at $2{\theta}$ 14.8, 17.2, 22.5. Starch granules were of the Ca crystalline type. The blue values of the Suwon 147 and the Chunmi were determined to be 0.342 and 0.279, amylose contents 27.6% and 23.6%, and water binding capacity 178.7% and 185.5%. Swelling of the starches negligible until $50^{\circ}C$ thereafter it increased rapidly. Swelling power of the Suwon 147 was more slightly than that of the Chunmi. Optical transmittance of 0.2% starch suspensions was increased rapidly from $65^{\circ}C$ and the gelatinization at $65{\sim}80^{\circ}C$ was of sing1e stage. Amylogram patterns of 4% starch solutions were similar to no peak viscosity. Viscosity of the Suwon 147 was increased, but that of the Chunmi was decreased at $92.5^{\circ}C$.

• Restorative Dentistry and Endodontics
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• v.33 no.5
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• pp.457-462
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• 2008

"Residual stress" can be developed during polymerization of the dental composite and it can be remained after this process was completed. The total amount of the force which applied to the composite restoration can be calculated by the sum of external and internal force. For the complete understanding of the restoration failure behavior. these two factors should be considered. In this experiment. I compared the residual stress of the recently developed nanofilled dental composite by ring slitting methods. The composites used in this study can be categorized in two groups. one is microhybrid type-Z250, as control group, and nanofilled type-Grandio, Filtek Supreme. Ceram-X, as experimental ones. Composite ring was made and marked two reference points on the surface. Then measure the change of the distance between these two points before and after ring slitting. From the distance change, average circumferential residual stress $({\sigma}{\theta})$ was calculated. In 10 minutes and 1 hour measurement groups, Filtek Supreme showed higher residual stress than Z250 and Ceram-X. In 24 hour group, Filtek showed higher stress than the other groups. Following the result of this experiment, nanofilled composite showed similar or higher residual stress than Z250, and when comparing the Z250 and Filtek Supreme, which have quite similar matrix components. Filtek Supreme groups showed higher residual stress.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.46-46
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• 2000

과학기술 및 산업의 발달로 인하여 실험 중 또는 공정 상에서 in situ, 실시간으로 측정하고 분석하며 이를 되먹임하는 품질제어의 중요성이 대두되고 있다. 반도체 공정 또는 박막제조 공정 중에서 박막의 두께, 굴절율, 물질의 조성비 등을 알아내는 것이 긴요한 과제로 대두되고 있으며, 이를 위하여 공정중인 제품의 품질을 실시간으로 평가하는 장비가 요구되고 있는 것이다. 나아가 공정중의 예상하지 못한 시료의 특성변화를 그대로 감지하여 적절히 보정해 주는 되먹임 기법은 높은 수율을 보장하는 첨단기법이라 할 수 있다. 이러한요구에 부응할 수 있는 본 제품(Elli-situ 2000)은 박막의 두께 표면변화를 sub 의 정밀도를 가지고 in situ, 실시간으로 정밀 측정할 수 있는 첨단 계측장비로서 빛의 편광상태 변화를 측정하기 때문에 공정 중의 시료에 영향을 주지 않는 비간섭 특성과 비접촉 특성의 장점 뿐만 아니라 공기중에서는 물론 진공이나 액체 등의 매질에서도 사용될 수 있어서 매질에 대한 제약이 거의 없다는 장점도 가지고 있다. 편광상태의 제어 및 측정을 필요한 광학장비의 경우, 제작이 까다롭기 때문에 대부분 가격이 높은 편이고 사용방법이나 측정 데이터에 대한 해석이 어렵다는 단점이 있으나, Elli-situ 2000의 경우 상용화된 외국제품(국내제품은 없슴)과 비교하여 성능 및 가격경쟁력에 있어서도 우위에 있으며 간단, 명료한 장비조작 및 컴퓨터를 사용한 구동의 전자동화를 이룸으로써 초보자도 쉽게 측정하고 데이터를 처리할 수 있도록 하였다. 또한 취부대의 경우, 진공포트 플랜지의 표준규격(2-3" Del-Seal 플랜지 규격)에 맞춤으로써 기존의 진공챔버에 부착하여 진공에 전혀 영향을 주지 않는 상태에서 시료의 변화를 in situ, 실시간으로 정밀 측정할 수 있도록 하였다. 하였다.O 박막은 산소 가스압력과 기판온도, 인가 전류를 변화시켜가며 증착하였으며 이에 따른 박막의 결정성 변화를 알아보았다. 기판온도를 실온에서 점차 증가시켜나가면 $\Delta$$\theta$50은 급격히 감소하며 30$0^{\circ}C$에서는 결정성이 우수한 막을 얻을 수 있었다. 또한 산소 가스 압력이 0.5~1mTorr에서 $\Delta$$\theta$50은 양호한 값을 나타내었지만 그 이상에서는 c-축 배향성이 나빠짐을 확인하였다. 따라서 대향타겟식스퍼터 장치를 이용하여 ZnO 박막을 증착시 가스압력 0.5~1mTorr, 기판온도 20$0^{\circ}C$이상의 막 제작조건에서 결정성이 우수하게 나타나는 것을 확인할 수 있었다. gluten이 단단해졌음을 알수 있었다. 유화제 stearly 칼슘, 혹은 hemicellulase를 amarans 10% 대체한 밀가루에 첨가하면 확연히 비용적을 증대시킬 수 있다는 사실을 알 수 있었다. quinoa는 명아주과 Chenopodium에 속하고 페루, 볼리비아 등의 고산지에서 재배 되어지는 것을 시료로 사용하였다. quinoa 분말은 중량의 5-20%을 quinoa를 대체하고 더욱이 분말중량에 대하여 0-200ppm의 lipase를 lipid(밀가루의 2-3배)에 대하여 품질개량제로서 이용했다. 그 결과 quinoa 대량 7.5%에서 비용적, gas cell이 가장 긍정적 결과를 산출했고 반죽의 조직구조가 강화되었다. 또 quinoa 대체에 의해 전분-지질 복합제의 흡열량이 증대된 것으로부터 전분-지질복합제의 형성 촉진이 시사되었다.이것으로 인하여 호화억제에 의한 노화 방지효과가 기대되었지만 실제로 빵의 노화는 현저히 진행되었다. 이것은

• Korean Journal of Acupuncture
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• v.30 no.2
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• pp.135-142
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• 2013

Objectives : This study aimed to investigate the general effects of low-frequency electrical stimulation of the ankle joint acupuncture points(BL62 and KI6) on the brain waves of elderly women as a pilot study to figure out the possibility of candidate non-invasive and non-chemical stimulation method for the enhancing the brain function. Methods : A randomized, controlled, double-blinded clinical trial was performed in 31 healthy women(mean age, 54.5 years) within a treatment duration of 12 sessions. In the experimental group, low-frequency electrical stimulation was applied using the maximum range of the individual insensible strength(mean current, $0.04{\mu}A$). The control group received sham stimulation. The background electroencephalographic activity was measured before and after the12 sessions. Results : After 12 sessions of stimulation, the relative power of the alpha wave increased(32 of 32 channels: significant difference in 11 channels, p<0.05); the theta(30 of 32 channels: significant difference in 10 channels, p<0.05), beta(31 of 32 channels), and gamma(30 of 32 channels: significant difference in 7 channels, p<0.05) powers were also decreased compared with the sham group. Conclusions : Electrical stimulation on the ankle joint acupuncture points(BL62 and KI6) seemed to stabilize the elderly women brain by inducing the alpha power and reducing beta, theta, and gamma powers. These results provide insight into the action mechanism of the stimulation and can assist the future developement of a non-invasive and non-chemical treatment technique for stressor related cognitive problems.

• Economic and Environmental Geology
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• v.51 no.6
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• pp.531-542
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• 2018

Batch sorption experiments were performed to remove the uranium (U) in groundwater by using the bamboo charcoal. For 2 kinds of commercialized bamboo charcoals in Korea, the U removal efficiency at various initial U concentrations in water were investigated and the optimal sorption conditions to apply the bamboo charcoal were determined by the batch experiments with replicate at different pH, temperature, and reaction time conditions. From results of adsorption batch experiments, the U removal efficiency of the bamboo charcoal ranged from 70 % to 97 % and the U removal efficiency for the genuine groundwater of which U concentration was 0.14 mg/L was 84 %. The high U removal efficiency of the bamboo charcoal maintained in a relatively wide range of temperatures ($10{\sim}20^{\circ}C$) and pHs (5 ~ 9), supporting that the usage of the bamboo charcoal is available for U contaminated groundwater without additional treatment process in field. Two typical sorption isotherms were plotted by using the experimental results and the bamboo charcoal for U complied with the Langmuir adsorption property. The maximum adsorption concentration ($q_m:mg/g$) of A type and C type bamboo charcoal in the Langmuir isotherm model were 200.0 mg/g and 16.9 mg/g, respectively. When 2 g of bamboo charcoal was added into 100 mL of U contaminated groundwater (0.04 ~ 10.8 mg/L of initial U concentration), the separation factor ($R_L$) and the surface coverage (${\theta}$) maintained lower than 1, suggesting that the U contaminated groundwater can be cleaned up with a small amount of the bamboo charcoal.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.72-81
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• 2019

Bisphenol A (BPA), a representative endocrine disrupting chemicals, has adverse effects on growth, development and reproduction in aquatic organisms. The object of this study was to investigate the modulation of antioxidant enzyme-coding genes using quantitative real time RT-PCR (qRT-PCR), enzyme activity and total protein content, to understand oxidative stress responses after exposure to BPA for 48 h in brackish water flea Diaphanosoma celebensis. The BPA ($3mg\;L^{-1}$) significantly upregulated the expression of Cu/Zn-SOD, Mn-SOD, and catalase (CAT) mRNA. Three GST isoforms (GST-kappa, GST-mu, and GST-theta) mRNA levels significantly increased at the rate of $0.12mg\;L^{-1}$ of BPA. In particular, GST-mu showed the highest expression level, indicating its key role in antioxidant response to BPA. SOD activity was induced with a concentration-dependent manner, and total protein contents was reduced. These findings indicate that BPA can induce oxidative stress in this species, and these antioxidants may be involved in cellular protection against BPA exposure. This study will provide a better understanding of molecular mode of action of BPA toxicity in aquatic organisms.

• Journal of IKEEE
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• v.23 no.2
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• pp.727-734
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• 2019

This paper confirms whether the movement or specific operation of the muscles in the process of transferring a person from the brain can find a signal showing an essential feature of a certain part of the brain. As a rule, the occurrence of EEG(Electroencephalogram) changes when a signal is received from a specific action or from an induced action. These signals are very vague and difficult to distinguish from the naked eye. Therefore, it is necessary to define a signal for analysis before classification. The EEG form can be divided into the alpha, beta, delta, theta and gamma regions in the frequency ranges. The specific size of these signals does not reflect the exact behavior or intention, since the band or energy difference of the activated frequencies varies depending on the EEG measurement domain. However, if different actions are performed in a specific method, it is possible to classify the movement based on EEG activity and to determine the EEG tendency affecting the movement. Therefore, in this article, we first study the EEG expression pattern based on the activation of the left and right biceps EMG, and then we determine whether there is a significant difference between the EEG due to the activation of the left and right muscles through EEG. If we can find the EEG classification criteria in accordance with the EMG activation, it can help to understand the form of the transmitted signal in the process of transmitting signals from the brain to each muscle. In addition, we can use a lot of unknown EEG information through more complex types of brain signal generation in the future.