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        검색결과 114

        41.
        2017.05 구독 인증기관·개인회원 무료
        본 연구에서는 다공성 PAN(Polyacrylonitrile) 중공사 분리막을 지지체로 이용하여 계면중합반응을 통해 나노여과막을 제조하였다. 지지체로는 PAN을 사용하였으며 수용상으로는 피페라진으로 중공사 분리막 내부에 코팅한 후 유기상인 TMC와 반응하여 계면중합이 일어나도록 진행하였다. 지지체로 사용된 UF 중공사 분리막은 분획분자량 10,000, 30,000, 100,000Da를 각각 사용하였으며 피페라진(Piperazine) 농도를 0.1%, 02%, 0.3%, TMC(Trimesoyl Chloride)의 농도를 0.05%, 0.1%, 0.2%로 변화시켜 제조 하여 5bar에서의 수투과도(LMH)와 MgSO4 2000ppm, Na2SO4 2000ppm, NaCl 500ppm 수용액으로부터 염배제율(Rejection, %)을 확인하였다.
        42.
        2017.05 구독 인증기관·개인회원 무료
        본 연구에서는 Hummer`s method를 개선하여 GO를 합성하였다. 전기방사법으로 GO + PAN 나노섬유 복합체 막을 제조하였으며, 표면특성· 인장강도· Flux 및 단백질 제거에 관한 실험을 진행하였다. 또한 GO+계면활성제, rGO로 PAN 나노섬유 복합체 막을 제작하였으며, 물리적 강도 측정 및 염 제거 실험에 활용하였다. GO나 rGO를 함유한 PAN 복합체 분리막의 경우 기계적 특성뿐만 아니라 단백질 및 염 제거에 효과적인 특성을 보여주었다. 이러한 결과를 바탕으로 폐수 속의 유기물질 제거에 효과적인 분리막 연구 기초자료로 활용될 수 있을 것으로 기대된다.
        43.
        2017.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        만성 췌장염은 췌장에 꾸준히 진행되는 염증과 섬유화를 특징으로 하는 질환으로 주요 임상특징은 복통, 흡수불량, 영양실조, 당뇨병 및 췌장 석회화이다. 이전에는 급성 췌장염과 만성 췌장염이 분리되어 있는 별개의 질병으로 생각하였으나 현재는 급성 췌장염과 만성 췌장염은 같은 질병의 연속선상 에 있는 것으로 여겨지고 있다. 그 근거로는 급성 췌장염과 만성 췌장염의 발병원인이 상당부분 비슷하며 급성 췌장염이 만성 췌장염으로 진행할 수 있기 때문이다. 최근의 연구에 의하면 급성 췌장염의 첫 번째 발생 환자의 10%에서 만성 췌장염이 발생하였고, 재발성 급성 췌장염 환자의 36%에서 만성 췌장염으로 진행하였으며 진행하는 위험인자는 흡연, 음주 그리고 남자 성별이었다. 만성 췌장염의 만성적인 심한 통증은 삶의 질을 떨어뜨리고 사회활동을 제한하는데 주요 기전은 1) 췌관이나 췌실질의 압력증가로 인한 허혈과 2) 말초 및 중추의 통각수용신경의 민 감화이다. 만성 췌장염의 통증은 간헐적인 양상과 연속적인 양상이 있으며 연속적인 양상의 통증이 삶의 질을 더 떨어뜨리는 것으로 보고되었다. 만성 췌장염의 복통은 만성 췌장염의 유병기간이 증가하면서 췌장이 "burn out"되어서 통증이 없어진다는 보고도 있지만 유병기간이 길어져도 통증이 남아 있다는 보고도 있어서 추가적인 연구가 필요하다. 지방변은 췌장의 외분비기능이 10% 이하로 남아 있을 때 발생하게 되므로 많이 진행된 만성 췌장염에서 관찰되는데 외분비기능부 전은 만성 췌장염 환자의 50-80%에서 나타날 수 있는 것으로 알려져 있다. 만성 췌장염에서 췌장의 내분비 조직의 파괴는 상대적으로 늦게 나타나는 것으로 알려져 있지만 오랜 기간 추적하였을 때 만성 췌장염 환자의 40-80%에서 당뇨병이 발 생한다. 만성 췌장염과 연관된 당뇨병은 3c형 당뇨병으로 분 류되며 췌장의 폴리펩티드 반응이 없는 것이 특징이다. 만성 췌장염 환자에서 당뇨병을 조기진단하기 위해서 해마다 공복 혈당과 당화혈색소를 측정하도록 권유한다. 가성낭종은 만성 췌장염 환자의 25% 정도에서 발생하며 가장 흔한 증상은 복통이며 가성동맥류와 같은 합병증이 발생할 수 있다. 가성동 맥류가 발견이 되면 출혈발생 여부와 관계없이 치료해야 한다. 담관 협착도 만성췌장염 환자의 10% 정도에서 발생하여서 간기능검사 이상, 황달, 담관염을 발생시킬 수 있다.
        4,000원
        44.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A most important progress in civilization was the introduction of mass production. One of main methods for mass production is die-casting molds. Due to the high velocity of the liquid metal, aluminum die-casting is so complex where flow momentum is critical matter in the mold filling process. Actually in complex parts, it is almost impossible to calculate the exact mold filling performance with using experimental knowledge. To manufacture the lightweight automobile bodies, aluminum die-castings play a definitive role in the automotive part industry. Due to this condition in the design procedure, the simulation is becoming more important. Simulation can make a casting system optimal and also elevate the casting quality with less experiment. The most advantage of using simulation programs is the time and cost saving of the casting layout design. For a die casting mold, generally, the casting layout design should be considered based on the relation among injection system, casting condition, gate system, and cooling system. Also, the extent or the location of product defects was differentiated according to the various relations of the above conditions. In this research, in order to optimize the casting layout design of an automotive Oil Pan_BR2E, Computer Aided Engineering (CAE) simulation was performed with three layout designs by using the simulation software (AnyCasting). The simulation results were analyzed and compared carefully in order to apply them into the production die-casting mold. During the filling process with three models, internal porosities caused by air entrapments were predicted and also compared with the modification of the gate system and overflows. With the solidification analysis, internal porosities occurring during the solidification process were predicted and also compared with the modified gate system.
        4,000원
        45.
        2016.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Excessive salt intake in body induces health risks resulting in high blood pressure or heart diseases. Therefore, the low salt concentration and salt-tasted food is needed by means of the modification of the manufacturing process. The purpose of this study is to study the effect of inhomogeneous salt localization in bread to enhance the saltiness of encapsulated salt. 0, 0.5, 1.0, 1.5, and 2.0% of liposome encapsulated salt (LS) was added into the baking of white pan bread. The final salt concentration was adjusted to 2.0% by addition of salt. After baking the bread, moisture content, loaf volume, fermentation rate, color, texture analysis, salt release rate, and sensory test were measured. From this study, moisture content had no significant difference in control and treatments (p>0.05), except for 2.0% LS. The lightness in all treatments was higher than the control’s (p<0.05), whereas there was no significant difference in hardness (p>0.05). From the sensory test, the bread added 2.0% LS showed the highest value from the salty taste. Moreover, it is related to the highest release rate of salt represented at 2.0% LS. In conclusion, the salty intensity of bread can be enhanced by the salt localization using the encapsulation of salt.
        4,000원
        46.
        2016.10 구독 인증기관·개인회원 무료
        Excessive salt intake in body induces health risks resulting high blood pressure or heart diseases. Therefore, the low salt concentration and sale tasted food is needed by means of the modification of manufacturing process. The purpose of this study was to study the effect of inhomogeneous salt localization in bread to enhance the saltiness encapsulated salt. The 0, 0.5, 1, 1.5, and 2.0% of liposome encapsulated salt (LS) was added into the baking of white pan bread. The final salt concentration was adjusted at 2% by addition of salt. After baking the bread, the moisture content, loaf volume, fermentation rate, color, texture analysis, salt release rate and sensory test were measured. From this study, moisture content has no significant difference between control and treatments (p>0.05), except for 2.0% LS. Lightness of all treatments was higher than control (p<0.05), whereas, there were no significant difference in hardness (p>0.05). From the sensory test, the bread added 2.0% LS was showed the highest value from the salty taste. Moreover, it is related to the highest release rate of salt was represented at 2.0% LS. In conclusion, the salty intensity of bread can be enhanced by the salt localization using encapsulation of salt.
        47.
        2016.10 구독 인증기관·개인회원 무료
        This study was conducted to investigate the quality characteristics of the bread containing a honeyed red ginseng by-product (HRG). HRG was added to bread dough at various concentration ranging from 10-30%, after which physicochemical properties of dough and bread containing HRG were determined. The pH, loaf volume, specific loaf volume, volume and baking loss decreased with increasing amount of HRG in bread, whereas loaf weight and hardness were increased. In particular, hardness appeared to be 2.18 times higher in the control without HRG compared to the bread containing 30% HRG. For color, increasing the amount of HRG reduced a and b values, whereas L value was increased. In sensory evaluation, the highest overall preference score was observed in containing 20% HRG, whereas the lowest score was observed in bread with 10% HRG. From a honeyed red ginseng by-product bread with good acceptability has an optimum HRG concentration of 20%.
        48.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Well-dispersed Ag3VO4 nanoparticles @polyacrylonitrile (PAN) nanofibers were synthesized by an easily controlled, template-free method as a photo-catalyst for the degradation of methylene blue. Their structural, optical, and photocatalytic properties have been studied by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy equipped with rapid energy dispersive analysis of X-ray, photoluminescence, and ultraviolet–visible spectroscopy. The characterization procedures revealed that the obtained material is PAN nanofibers decorated by Ag3VO4 nanoparticles. Photocatalytic degradation of methylene blue investigated in an aqueous solution under irradiation showed 99% degradation of the dye within 75 min. Finally, the antibacterial performance of Ag3VO4 nanoparticles @PAN composite nanofibers was experimentally verified by the destruction of Escherichia coli. These results suggest that the developed inexpensive and functional nanomaterials can serve as a non-precious catalyst for environmental applications.
        4,000원
        49.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated properties of bread utilizing extracts of ginseng powder. Ginseng powder bread was baked. Addition of 1~3% of ginseng powder extract to wheat flour was carried out. Rheological properties, dough pH, dough volume, bread volume, water absorption capacity, baking loss, bread color, bread texture, and sensory evaluation were tested to examine properties of bread baked with extracts of ginseng powder. The results are as follows. The dough pH decreased gradually with increasing ginseng powder extract concentration. The bread volume, baking loss, and bread weight increased with increasing use of ginseng powder extract, and springiness and cohesiveness increased as red ginseng powder additive concentration increased. Lightness of the L decreased while a and b increased. In the sensory evaluation, ginseng powder with 1% ginseng powder extract was evaluated as the best for taste, texture, flavor, and overall acceptability.
        4,000원
        50.
        2016.05 구독 인증기관·개인회원 무료
        본 연구에서는, 산화그래핀과 은나노물질의 복합체인 Ag/GO를 합성하고 이를 PAN 고분자용액에 도입하여 전기방사함으로써 나노섬유형태의 분리막을 제조하였다. Ultraviolet-visible spectra분석을 통해 합성조건을 최적화하였으며, SEM, TEM, Raman 분석을 진행하여 구조 및 형태를 확인하였다. 그램음성균 (Salmonella, E. coli.)과 그램양성균(B. cereus, St. aureus)에 대한 항균성 실험결과 제조된 복합나노섬유의 항균효과를 확인할 수 있었다. 또한, 복합체의 도입 에 따라 약 100%이상의 높은 수투과도 값과 막오염 저감효과를 확인할 수 있었다. 따라서 본 연구에서 제조된 나노섬유 분리막은 수처리용 분리막으로 충분히 활용할 수 있을 것으로 판단된다.
        51.
        2016.05 구독 인증기관·개인회원 무료
        본 연구는 Hummer’s method를 이용하여 Graphene oxide (GO)를 합성하였으며, poly acrylonitrile (PAN)과 복합화하여 나노섬유 막을 제조하였다. 접촉각 측정, SEM, FT-IR, 인장강도, DI water를 이용한 flux 실험 및 BSA rejection 실험을 실시하여 막의 특성 분석을 진행하였다. PAN/GO 0.3 나노섬유의 경우, rejection 값이 59%로 PAN/GO 복합 나노섬유 막들 중 상대적으로 우수하였다. PAN/GO 복합 나노섬유 막을 수 처리 분야에 이용하여 얻은 자료는, 폐수 속의 유기물질 함량 감소 연구에 대한 기초자료로 활용될 수 있을 것으로 기대된다.
        52.
        2016.05 구독 인증기관·개인회원 무료
        Membrane application for CO2 capture is competing with other methods such as amine absorption or absorbent, by reasons of low energy and cost effect. Though membrane separation is promising technology, there exists critical challenge: ‘the upper bound.’ Most of researches have focused on improving gas transport properties of selective layer, but we recognized the importance of membrane support layer shich highly affects affinity with coating layer. Here we adjusted several fabrication conditions for highly porous PAN membrane by NIPS method; concentration, temperature, and additive. In this study, experimental results regarding porosity and pore size, are compared to theoretical dusty-gas model. Moreover, we prepared composite membrane and compared fabricated membrane with commercial one in terms of gas permeance and selectivity.
        53.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A powder injection molding process is developed and optimized for piezoelectric PAN-PZT ceramics. Torque rheometer experiments are conducted to determine the optimal solids loading, and the rheological property of the feedstock is evaluated using a capillary rheometer. Appropriate debinding conditions are chosen using a thermal gravity analyzer, and the debound specimens are sintered using sintering conditions determined in a preliminary investigation. Piezoelectric performance measures, including the piezoelectric charge constant and dielectric constant, are measured to verify the developed process. The average values of the measured piezoelectric charge constant and dielectric constant are 455 pC/N and 1904, respectively. Powder injection molded piezoelectric ceramics produced by the optimized process show adequate piezoelectric performance compared to press-sintered piezoelectric ceramics.
        4,000원
        54.
        2015.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Six hulless barley (Hordeum Vulgare L.) cultivar, including 3 normal, 2 waxy, and 1 colored-waxy, was used to substitute 20% of wheat flour for pan-bread making. Replacing 20% barley flour significantly increased β-glucan content, which ranged in 0.98-1.36% for normal, 1.65-1.67% for waxy, and 1.50% for colored-waxy barley, which are all higher than wheat flour (0.14%). Pasting viscosity of barley flour blends varied by barley type and cultivar, presenting that barley cv. Dapung (DP) had the highest peak viscosity of 170.1 RVU, whereas the lowest value was 80.2 RVU in “Jasujeongchal (JSJC)”. Substitution of barley flour decreased the Hm and H'm value during dough fermentation and estimated a reduction of bread qualities compared to wheat bread. Bread loaf volume varied by barley type and cultivar, showing a slight decrease in loaf volume, but increase in crumb firmness compared to wheat bread. Among barley cultivars, DP barley showed high bread loaf volume (691.7 cm 3 /g) with lower firmness (11.8 N). In contrast, bread made from JSJC barley flour had the lowest bread-making qualities probably due to bran layer inclusion. It appeared that barley type influenced more than barley cultivars although the mean values of all quality parameters slightly varied by barley cultivar. Results indicated that the inclusion of barley flour for bread-making could provide an elevated intake of β-glucan, which had health benefits by increasing dietary fiber content.
        4,000원
        56.
        2015.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to study the impact of atmosphere during electron beam irradiation (EBI) of polyacrylonitrile (PAN) precursor fibers, the latter were stabilized by EBI in both air and oxygen atmospheres. Gel-fraction determination indicated that EBI-stabilization under an oxygen atmosphere leads to an enhanced cyclization in the PAN fibers. In the Fourier-transform infrared spectroscopy analysis, the PAN fibers stabilized by EBI under an oxygen atmosphere exhibited a greater decrease in the peak intensity at 2244 cm-1 (C≡N vibration) and a greater increase in the peak intensity at 1628 cm-1 (C=N absorption) than the corresponding PAN fibers stabilized under an air atmosphere. From the X-ray diffraction analysis it was found that oxygen uptake in PAN fibers leads to an increase in the amorphous region, produced by cyclization.
        3,000원
        57.
        2015.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study fabricated low thermal conductive polyacrylonitrile (PAN)-based carbon fibers containing cellulose particles while maintaining their mechanical properties. The high thermal conductivity of carbon fibers limits their application as a high temperature insulator in various systems such as an insulator for propulsion parts in aerospace or missile systems. By controlling process parameters such as the heat treatment temperature of the cellulose particles and the amount of cellulose added, the thermal and mechanical properties of the PANbased carbon fibers were investigated. The results show that it is possible to manufacture composite carbon fibers with low thermal conductivity. That is, thermal conductivities were reduced by the cellulose particles in the PAN based carbon fibers while at the same time, the tensile strength loss was minimized, and the tensile modulus increased.
        4,000원
        58.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to develop food for the elderly, which are well-shaped and easy to chew and swallow. The amounts of water and gelatin were adjusted to facilitate breaking down of the food with the tongue. In the aging society, it is necessary to support the development of a variety of products that can ease the intake functions of swallowing and chewing, while complementing with the essential nutrients supplements; such products can be actively commercialized in the elderly industry. Various types of food, for elderly with difficulties in chewing and swallowing, were used for sensory assessment. Sensory panel consisted of 10 dietitians (10 women) in nursing care facilities. The sensory optimal composite recipes were determined by central composite design (CCD). The sensory measurements were significantly different in the appearance (p<0.01), saltiness (p<0.01) and overall quality (p<0.01). The optimum formulation of pan fried flat fish, calculated by numerical and graphical method, was 8.54 g of salt and 6.34 g of olive oil. Moisture content, hardness, and adhesiveness of pan fried flat fish were 84.77%, 250, and -1.20, respectively. The result showed that easily chewable and swallowable pan fried flat fish for the elderly will have sufficient competitiveness, considering its safety, taste, and preference. This study may provide the basic materials for the development of easily chewable and swallowable foods for elderly.
        4,000원
        59.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        고농도의 초산수용액을 분리⋅농축하기 위해 polyacrylonitrile (PAN) 중공사 복합막을 제조한 후 투과증발 분리실험을 통해 제조된 복합막의 분리성능을 확인하였다. 제조된 중공사 복합막의 코팅여부를 알아보고자 SEM 사진을 측정하였으며 코팅두께가 3.85 µm로 균일하게 코팅된 것을 확인할 수 있었다. 또한 막의 투과성능평가 실험을 수행한 결과 가교제의 농도와 가교온도가 증가함에 따라 투과도는 감소하고 선택도는 증가하는 경향을 나타내었고, 대표적인 결과로 가교제인 glutaraldehyde 농도 13 wt%, 가교온도 140°C에서 투과도 250 g/m2⋅hr, 선택도 13의 결과를 얻을 수 있었으며, 또 다른 가교제로서 poly (acrylic acid) 농도 9 wt%, 가교온도 140°C일 때 투과도 330 g/m2⋅hr, 선택도 9의 값을 얻을 수 있었다.
        4,000원
        60.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는, 산화그래핀(GO) 및 산화철이 기능화된 산화그래핀(M-GO)을 용매인 dimethylformamide (DMF)에초음파분쇄법을 이용하여 완전히 분산시킨 후, 기질고분자인 polyacrylonitrile (PAN)에 첨가하여 전기방사함으로써, 나노섬유 형태의 복합분리막을 제조하였다. 제조된 나노섬유 분리막은 적층수를 변화시켜 기공크기를 조절하였다. Scanning Electron Microscope (SEM) 분석 결과로부터 약 500 nm 크기의 고른 직경분포를 가진 나노섬유 복합분리막이 제조되었음을 확인하였다. 또한, Raman spectroscopy 분석과 Energy Dispersive x-ray Spectroscopy (EDS) 분석 결과로부터 GO 및 M-GO가 분리막 내에 분산되어 있음을 확인하였다. 최종 나노섬유 복합분리막은 상용막(0.27 µm, 55%)과 유사한 기공특성(0.21~0.24 µm,40%)을 보여주었으며, 수투과도 측정결과 PAN 막에 비해 약 200% 향상된 성능을 보여주었다. 이러한 결과로부터, 전기방사법으로 제조된 나노섬유 복합분리막은 수처리용 분리막으로서 충분한 활용가능성이 있다고 판단된다.
        4,000원
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