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        검색결과 40

        1.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, two alignment methods were used to create a Fringe-Field Switching (FFS) mode liquid crystal device using an organic thin film (polyimide: PI) as an alignment layer. In addition, the electro-optical (EO) characteristics of the liquid crystal device manufactured in this way were investigated to evaluate the feasibility of mass production application of the technology. In general, the photo-alignment method using unpolarized ultraviolet rays can obtain a relatively low pretilt angle, so a liquid crystal device in FFS mode, which is a driving mode of the liquid crystal device that reflects the characteristics of liquid crystal alignment, was manufactured, and the liquid crystal has a high reactivity with the alignment film. Considering this, nematic liquid crystal (NLC) was used. In addition, in order to improve the misalignment, it was observed whether more stable orientation occurred by irradiating ultraviolet rays for an additional 1 to 3 hours in the aligned state. As a result of the experiment, it was found that NLC alignment occurs through a photodecomposition reaction caused by unpolarized UV irradiation oblique to the PI surface. In addition to the existing orientation method, UV irradiation was used to achieve a more stable orientation state and stable V-T curve and response characteristics. With liquid crystal alignment completed, more stable orientation characteristics and EO characteristics at the mass production level were obtained through additional UV irradiation for 3 hours. This method can further stabilize the orientation stability caused by existing UV irradiation through an additional process.
        4,000원
        2.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In order to respond to environmental pollution, developed countries, including Korea, have begun to conduct research to utilize hydrogen energy. For mass transfer of hydrogen energy, storage as liquid hydrogen is advantageous, and in this case, the volume can be reduced to 1/800. As such, the transportation technology of liquefied hydrogen for ships is expected to be needed in the near future, but there is no commercialized method yet. This study is a study on the technology to test the performance of the components constituting the membrane type storage container in a cryogenic environment as a preparation for the above. It is a study to find a way to respond by analyzing in advance the problems that may occur during the shear test of adhesives. Through this study, the limitations of ISO4587 were analyzed, and in order to cope with this, the specimen was supplemented so that fracture occurred in the adhesive, not the adhesive gripper, by using stainless steel, a low-temperature steel, to reinforce the thickness. Based on this, shear evaluation was performed under conditions lowered to minus 243℃, and it was confirmed that the breaking strength was higher at cryogenic temperatures.
        4,000원
        3.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A laboratory-scale experiment was conducted to evaluate the effect of supplementing commonly used effective microorganisms on the chemical properties of swine liquid manure. Effective microorganisms used in this study were Bacillus subtilis (1.3×109 colony-forming unit (CFU)/ml), Enterococcus faecium (1.9×1010 CFU/ml), Aspergillus oryzae (2.0×109 CFU/ml), Saccharomyces cerevisiae (6.4×109 CFU/ml), Rhodobacter sphaeroides (1.2×108 CFU/ml), and Streptomyces griseus (6.2×108 CFU/ml). Swine liquid manure collected and decanted from a swine farm was used in this study. Treatments included control (distilled water supplementation), Treatment 1 (T1) (mixed microbes, 109 CFU/ml), and Treatment 2 (T2) (mixed microbes, 107 CFU/ml). Microbial mix was supplemented every 3.5 days and aerated six times (15 min each) a day to facilitate compositing. Ten ml of sample was collected at 2-, 4-, 6-, and 7-week intervals for the measurement of pH, ammonia-N, volatile fatty acid (VFA), total nitrogen, total phosphorus, and total potassium. At seven weeks, samples were further collected to analyze biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Ammonia-N was significantly (p<0.05) decreased in T1 and T2 by 36% and 30%, respectively, compared with control (23%). VFAs including butyrate, iso-butyrate, valerate, iso-valerate, and caproate were not detected in T1 from the four-week aerated sample. The BOD and COD were significantly (p<0.05) decreased in T1 by 96% and 58%, respectively. In conclusion, ammonia-N, VFA, BOD, and COD, known as odor indicators, were decreased in T1 and T2 compared with control, suggesting that effective microorganisms are useful for compositing swine liquid manure
        4,000원
        4.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Although aronia (Aronia melanocarpa (Michx.) Elliott) contains higher levels of polyphenols and more antioxidant activity than other berries, it is a berry that is difficult to eat raw due to its strong astringent taste and lack of sweetness. Therefore, in this study, we investigated the effect of tannin reduction of aronia by bioconversion method using mushroom mycelia cultures. Aronia and liquid cultures of Lentinula edodes and Phellinus linteus mycelia were mixed and then treated for 48 hours at 60°C. Tannin content, total polyphenol, total flavonoid and antioxidant activities (DPPH, ABTS radical-scavenging activities and FRAP activities) were investigated. The tannin content decreased from 64.2 mg ECE/g to 57.9 mg ECE/g (9.8% reduction) when treated with liquid culture of L. edodes and from 77.3 mg ECE/g to 47.9 mg ECE/g (38.1% reduction) from treatment with a liquid culture of P. linteus. Therefore treatment with mushroom mycelia culture solution may improve the palatability of aronia reducing the astringent taste.
        4,000원
        5.
        2020.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this work, the electrical explosion of wire in liquid and subsequent spark plasma sintering (SPS) was introduced for the fabrication of Ni-graphite nanocomposites. The fabricated composite exhibited good enhancements in mechanical properties, such as yield strength and hardness, but reduced the ductility in comparison with that of nickel. The as-synthesized Ni-graphite (5 vol.% graphite) nanocomposite exhibited a compressive yield strength of 275 MPa (about 1.6 times of SPS-processed monolithic nickel ~170 MPa) and elongation to failure ~22%. The hardness of Nigraphite composite had a value of 135.46 HV, which is about 1.3 times higher than that of pure SPS-processed Ni (105.675 HV). In terms of processing, this work demonstrated that this processing route is a novel, simple, and low-cost method for the synthesis of nickel-graphite composites.
        4,200원
        6.
        2019.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Pb(Zr,Ti)O3 (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. (K,Na)NbO3 (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, (Na,K)NbO3-Ba(Cu,Nb)O3 (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKNBCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan δ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and 20 μC/cm2.
        4,000원
        7.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we studied the alignment characteristics of liquid crystal on polyimide substrate when irradiated with ion beam in oblique direction on uniformly coated polyimide substrate. The inclined irradiation angle of the ion beam was set to 30 degree, 45 degree and 60 degree and the characteristics were observed for 1 minute and 2 minutes at an ion beam irradiation intensity of 600 to 3,000 eV for each angle. The Alignment of the liquid crystals were observed using a polarized microscope after preparing antiparallel specimens. The pretilt angle of the liquid crystal using the crystal rotation method was measured, and the applicability to actual products was evaluated. Experimental results showed that uniformly aligned liquid crystals could be obtained in samples irradiated at 1 and 2 minutes with an ion beam intensity of 1200 eV or higher when irradiated with 30 degree and 45 degree tilted ion beams. And, at 60 tilted degree, It shows that uniformly aligned liquid crystals could be obtained in samples irradiated at 1 and 2 minutes with an ion beam intensity of 2400 eV or higher. The pretilt angle of the liquid crystal showed the best characteristics when irradiated with ion beam inclined at 45 degrees, and it was confirmed that the pretilt angle was 0.2 to 1.3 degrees, which is usable for horizontally oriented LCD.
        4,000원
        8.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the physical and sensorial properties of the meat analog were studied for the purpose of improving sensory preference and mimicking animal meat. The meat analog was made with different types of liquid materials such as oil, water, lecithin, polysorbate 80, or the emulsion of these components. At the aspect of density, the sample mixed with oil was higher than the sample mixed with water. Cooking loss value was higher at the sample with water than the sample with oil and this was the result opposite to the liquid holding capacity analysis. Also, texture profile analysis result showed that the samples with medium chain triglycerides (MCT) oil only showed the highest values in all attributes except for adhesiveness. Principal component analysis was carried out to analyze sensorial properties and it showed that the overall acceptance was high when the juiciness and softness increased. This result was highly related with the addition of emulsion. Therefore, emulsion technology can be a good candidate for improving the quality of meat analog and for mimicking the taste of animal meat.
        4,000원
        9.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        액상 바이오연료를 생산할 수 있는 하수슬러지는 자국의 에너지 안보와 지속가능한 생산이 가능하고 경제적인 원료로 여겨지고 있다. 열화학적 기술은 하수슬러지를 에너지화, 연료화할 수 있는 가장 효과적인 방법이다. 일반적으로 하수슬러지는 수분 함량이 80% 이상으로 높은 금속 함량과 14 ~ 20 MJ/kg의 발열량을 갖고 있다. 본 논문에서는 하수슬러지를 활용한 액상 바이오연료를 생산하는 열분해 반응, 전이에스테르화 반응, 초임계 반응 기술에 대해 살펴보고자 한다. 또한, 하수슬러지 유래 액상 바이오연료의 연료적 특성과 액상 바이오연료와 관련한 국내 법에 대해 검토하였다.
        5,500원
        10.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fe3O4/Fe/graphene nanocomposite powder is synthesized by electrical wire explosion of Fe wire and dispersed graphene in deionized water at room temperature. The structural and electrochemical characteristics of the powder are characterized by the field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, field-emission transmission electron microscopy, cyclic voltammetry, and galvanometric discharge-charge method. For comparison, Fe3O4/Fe nanocomposites are fabricated under the same conditions. The Fe3O4/Fe nanocomposite particles, around 15-30 nm in size, are highly encapsulated in a graphene matrix. The Fe3O4/Fe/graphene nanocomposite powder exhibits a high initial charge specific capacity of 878 mA/g and a high capacity retention of 91% (798 mA/g) after 50 cycles. The good electrochemical performance of the Fe3O4/Fe/graphene nanocomposite powder is clearly established by comparison of the results with those obtained for Fe3O4/Fe nanocomposite powder and is attributed to alleviation of volume change, good distribution of electrode active materials, and improved electrical conductivity upon the addition of graphene.
        4,000원
        11.
        2017.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Liquid storage tank is one of the major infrastructures and generally used to store gases, drinking and utilizing water, dangerous fluids, fire water and so on. According to the recent reports and experiences, the tank structures are damaged in many earthquakes due to their low energy dissipating capacity. Therefore, many researchers have been tried to know the dynamic properties of the tanks including liquids. However, vary limited experimental studies are carried out using relatively small tank models. In this study, a series of shaking table tests are performed with maximum 2 m cubic rectangular liquid storage tanks made of steel to measure the natural frequency and estimate damping coefficient of impulsive and convective mode of the tanks. Especially, the damping values under different shapes and excitation methods are estimated by logarithmic decrement method and half power band-pass method and compared with current design code and standards such as ASCE 7, Eurocode 8 and NZS. Test results show that the impulsive mode damping is around 2% which is proposed by general standards and codes but the impulsive mode damping is 0.13% average that is slightly lower than the code recommendation.
        4,000원
        12.
        2017.04 구독 인증기관·개인회원 무료
        The effects of high hydrostatic pressure (HHP) or concentration treatment or sodium hydrogen carbonate addition on microbial and quality properties of cold drip liquid coffee were investigated during storage at room temperature. Cold drip liquid coffee was determined to pH, acidity, general bacteria, and Y&M (Yeast and Molds) according to HHP treatment or adding 0.2% sodium hydrogen carbonate for 40 days storage at 20°C. Also, an equivalent mixture of concentrated coffee and cold drip liquid coffee or liquid coffee with 0.2% sodium hydrogen carbonate was used for determining the sensory evaluation, due-trio and preference test. The cold drip liquid coffee with 0.2% sodium hydrogen carbonate had higher pH and lower titratable acidity than the control during 40 days storage at 20°C. Total viable cell and Y&M counts of cold drip liquid coffee added with 0.2% sodium hydrogen carbonate or treated by HHP at 300 MPa for 25 min were lower than the control during storage at 20°C. The result of the due-trio and preference tests shows that there was no significant difference between cold drip liquid coffee added to 0.2% sodium hydrogen carbonate and the control or between the equivalent mixture of concentrated coffee with cold drip liquid coffee and the control. As a results, Cold drip liquid coffee treated by HHP, concentrated by evaporation, and added to sodium hydrogen carbonate has a potential to extend a shelf life at ambient temperature storage.
        13.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to examine the effect of nutrients balanced fertilizers applications, swine liquid manure(SLM) with synthetic chemical fertilizer on growth and yield of Chinese chive(Allium tuberosum Rottler) and soil properties in green house cultivation during 2015 growing season. There are 4 treatment plots; swine liquid manure(SLM), nutrients balanced fertilizers(mixture of chemical fertilizer with swine liquid manure(SLM+CF), nutrient balanced and pH adjustment (SLM+CF+pH) and the conventional chemical fertilizer(control). The phosphorous acid is added to adjust pH in animal liquid manure. The yield of Chinese chive in plot of swine liquid manure(SLM) was decreased by 4% compared with plot of conventional chemical fertilizer(control). There was no significant differences of growth and yield of Chinese chive between SLM+CF and control. The yield of SLM+CF+pH plot was highest yield as 8,235 kg 10a-1 among 4 treatments and was increased than that of swine liquid manure plot(7,489 kg 10a-1). EC and available P2O5 were decreased by SLM+CF+pH treatment. Combined application of SCM and CF fertilizer can be a useful tool, particularly for the fertigation culture of Chinese chive in greenhouse. In conclusion, the present study demonstrates that the combined application of liquid swine manure and chemical nutrients was responsible for improving yield of Chinese chive and soil properties.
        4,000원
        14.
        2016.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tin is one of the most promising anode materials for next-generation lithium-ion batteries with a high energy density. However, the commercialization of tin-based anodes is still hindered due to the large volume change (over 260%) upon lithiation/delithiation cycling. To solve the problem, many efforts have been focused on enhancing structural stability of tin particles in electrodes. In this work, we synthesize tin nano-powders with an amorphous carbon layer on the surface and surroundings of the powder by electrical wire explosion in alcohol-based liquid media at room temperature. The morphology and microstructures of the powders are characterized by scanning electron microscopy, Xray diffraction, Raman spectroscopy, and transmission electron microscopy. The electrochemical properties of the powder for use as an anode material for lithium-ion battery are evaluated by cyclic voltammetry and a galvanometric dischargecharge method. It is shown that the carbon-coated tin nano-powders prepared in hexanol media exhibit a high initial charge specific capacity of 902 mAh/g and a high capacity retention of 89% after 50 cycles.
        4,000원
        15.
        2015.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The porous Mg3Sb2 based compounds with 60~70% of relative density were prepared by powder compaction at room temperature and reactive liquid phase sintering at 1023 K for 4hrs. The stoichiometric Mg3Sb2 compounds were synthesized from elemental Sb and Mg powder in the mixing range of 61~63 at% Mg. The increased scattering effect due to the micro-pores reduced the mobility of the charge carrier and the phonon, which caused the electrical conductivity and the thermal conductivity to decrease, respectively. But the scattering effect was greater for the electrical conductivity than for the thermal conductivity. Excess Mg alloyed in the Mg3Sb2 compounds decreased the electrical conductivity, but had no effect on the thermal conductivity. On the other hand, the large increase of the Seebeck coefficient was the result of a decrease in the charge carrier density due to the excess Mg. Dimensionless figure of merit of the porous Mg3Sb2 compound reached a maximum value of 0.28 at 61 at% Mg. The obtained value was similar to that of Mg3Sb2 compounds having little pores.
        4,000원
        16.
        2014.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A spherical Sr4Al14O25:Eu2+ phosphor for use in white-light-emitting diodes was synthesized using a liquid-state reaction with two precipitation stages. For the formation of phosphor from a precursor, the calcination temperature was 1,100˚C. The particle morphology of the phosphor was changed by controlling the processing conditions. The synthesized phosphor particles were spherical with a narrow size-distribution and had mono-dispersity. Upon excitation at 395 nm, the phosphor exhibited an emission band centered at 497 nm, corresponding to the 4f65d→4f7 electronic transitions of Eu2+. The critical quenching-concentration of Eu2+ in the synthesized Sr4Al14O25:Eu2+ phosphor was 5 mol%. A phosphor-converted LED was fabricated by the combination of the optimized spherical phosphor and a near-UV 390 nm LED chip. When this pc-LED was operated under various forward-bias currents at room temperature, the pc-LED exhibited a bright blue-green emission band, and high color-stability against changes in input power. Accordingly, the prepared spherical phosphor appears to be an excellent candidate for white LED applications.
        4,000원
        17.
        2014.07 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study reports on the influenceof N-butyl-N-methylpyrrolidinium tetrafluoroborat (PYR14BF4) ionic liquid additive on the conducting and interfacial properties of organic solvent based electrolytes against a carbon electrode. We used the mixture of ethylene carbonate/dimethoxyethane (1:1) as an organic solvent electrolyte and tetraethylammo-nium tetrafluoroborate(TEABF4) as a common salt. Using the PYR14BF ionic liquid as additive produced higher ionic conductivity in the electrolyte and lower interface resis-tance between carbon and electrolyte, resulting in improved capacitance. The chemical and electrochemical stability of the electrolyte was measured by ionic conductivity me-ter and linear sweep voltammetry. The electrochemical analysis between electrolyte and carbon electrode was examined by cyclic voltammetry and electrochemical impedance spectroscopy.
        4,000원
        18.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ultra-thin liquid films on solid substrates in contact with the saturated vapor are studied by using molecular dynamics simulation. The properties of evaporation and condensation of the films of various adsorptive strengths and thicknesses are obtained during the quasi-steady film evolution. Net condensations occur when the ultra-thin films on the high energy surface come into contact with the saturated vapor phase because the normal film pressure stays lower than the saturated vapor pressure. The net condensation rate is higher for the material combination of higher adsorptive strength. It becomes more so when the film thickness is of a lesser size. On the other hand, that of lower adsorptive strength has lower net condensation rate and depends less on the film thickness. Therefore, the size effect of the condensation phenomenon is more significant for the system of a higher adsorptive strength. This properties come from the state of ultra-thin film, which can be quantified by using disjoining pressure in the quasi-steady processes. These results have implications in practical problems concerning the moving contact line when the precursor film formation is critica
        4,000원
        19.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 유기액비 재료가 유기액비 제조시 화학적 특성 변화에 미치는 영향을 구명코자 충청북도농업기술원 플라스틱하우스에서 수행하였다. 계분, 대두박, 쌀겨 등 3처리를 하였다. 본 시험에서 얻어진 결과를 다음과 같이 요약할 수 있다. 액비 원료의 총 질소 함량은 대두박이 55 mg·kg−1으로 가장많았으며, 인산과 칼륨 함량은 계분에서 가장 많았다. 계분의pH는 중성에 가까웠으며, 대두박과 쌀겨는 강산성을 띠었다. 계분 액비의 EC는 발효기간이 증가할수록 증가하였고, 대두박과 쌀겨 액비는 발효기간 중 증가하다가 감소, 증가하는 경향이었다. 계분 액비의 황화수소 발생량은 발효 후 2주차에는3,200 mg·L−1이었으나, 발효 12주차에는 1,600 mg·L−1으로 감소하였고, 대두박과 쌀겨 액비는 발효 과정중 황화수소 가스가 발생하지 않았거나 거의 발생하지 않았다. 질소와 칼슘 함량은 계분 액비와 대두박 액비에서 가장 많았다. 인산, 마그네슘의 함량은 쌀겨 액비에서 각각 5.6 g·kg−1, 1.5 g·kg−1으로 가장 높았다. 칼륨은 처리에 따라 4.3-4.4g·kg-1으로 차이가 없었다.
        4,000원
        20.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper presents a novel single-step method to prepare the Ag nanometallic particle dispersed fluid (nanofluid) by electrical explosion of wire in liquid, deionized water (DI water). X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) were used to investigate the characteristics of the Ag nanofluids. Zeta potential was also used to measure the dispersion properties of the as-prepared Ag nanofluid. Pure Ag phase was detected in the nanofluids using water. FE-SEM analysis shows that the size of the particles formed in DI water was about 88 nm and Zeta potential value was about -43.68 without any physical and chemical treatments. Thermal conductivity of the as-prepared Ag particle dispersed nanofluid shows much higher value than that of pure DI water.
        4,000원
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