Recently, research on cost reduction and efficiency improvement of crystalline silicon(c-Si) photovoltaic(PV) module has been conducted. In order to reduce costs, the thickness of solar cell wafers is becoming thinner. If the thickness of the wafer is reduced, cracking of wafer may occur in high temperature processes during the c-Si PV module manufacturing process. To solve this problem, a low temperature process has been proposed. Conductive paste(CP) is used for low temperature processing; it contains Sn57.6Bi0.4Ag component and can be electrically combined with solar cells and ribbons at a melting point of 150℃. Use of CP in the PV module manufacturing process can minimize cracks of solar cells. When CP is applied to solar cells, the output varies with the amount of CP, and so the optimum amount of CP must be found. In this paper, in order to find the optimal CP application amount, we manufactured several c-Si PV modules with different CP amounts. The amount control of CP is fixed at air pressure (500 kPa) and nozzle diameter 22G(outer diameter 0.72Ø, inner 0.42Ø) of dispenser; only speed is controlled. The c-Si PV module output is measured to analyze the difference according to the amount of CP and analyzed by optical microscope and Alpha-step. As the result, the optimum amount of CP is 0.452 ~ 0.544 g on solar cells.

와사비 페이스트의 저장성 향상을 위하여 구연산을 농도별로 첨가하고 저장기간에 따른 이화학적 및 미생물학적 특성, 가스발생량 및 ally isothiocyanate 함량 변화를 측정하였다. 와사비 페이스트의 pH는 구연산 첨가량에 따 라 감소하였으며, CA 0.4%처리구에서 4.34±0.01로 가장 낮게 나타났다. 저장기간 동안 와사비 페이스트의 pH는 4.01-5.19사이로 나타났다. 총산의 함량은 저장 7일까지 유의적인 차이가 나타나지 않았으며 저장 14일 이후 감소하였다. 와사비 페이스트의 가용성 고형분 함량은 구연산 첨가량에 따라 증가하였으며, 저장기간에 따른 유의적 차이를 보이지 않고 저장 28일 후 25.60-29.50 oBrix로 나타났다. 저장기간에 따른 와사비 페이스트의 L값은 감소하였으며, a값과 b값은 증가하는 경향을 나타내다. 일반세균 수는 저장기간이 경과함에 따라 감소하는 경향을 나타냈으며, 저장 초기에 2.56±0.09~4.87±0.17 log CFU/g에서 저 장 21일 후 CA 0.30%와 CA 0.40% 처리구에서 일반세균이 검출되지 않았다. 효모의 경우 일반세균의 경우와 마찬가지로 저장기간에 따라 감소하는 경향을 나타내었으며, CA 0.30%와 CA 0.40%의 경우 저장 초기부터 28일까지 검출되지 않았다. 이로써 와사비 페이스트에 구연산 0.30% 이상 첨가하면 미생물의 생장이 억제되는 것을 확인할 수 있었다. 가스발생량은 21일 저장 후 가스 발생량의 증가폭이 가장 크게 나타났으며, 저장 28일 후 19.55-19.80 mL/ tube로 나타났으며, 구연산 처리농도에 따른 유의성은 나타나지 않았다. Allyl isothiocyanate 함량은 구연산 처리 농도 와 저장기간에 따라 감소하였으며, CA 0.40% 처리구에서 저장 초기와 28일 후 각각 45.62±12.78 mg/100 g와 29.72±0.58 mg/100 g로 가장 낮게 측정되었다. 연구 결과 와사비 페이스트에 구연산 0.30%를 첨가하여 제조 시 저장성 향상 효과를 얻을 수 있으며, 이를 통하여 와사비 페이스트의 상온유통 시 유통기한 연장 효과를 얻을 수 있을 것으로 생각된다.

This study evaluates the quality properties of soy-paste soybean cultivar for fermented soybean products. The six soybean varieties that include Jinpung, Saedanbaek, Daepung 2, Pyeongwon, Cheonga and Saeolkong were used in the experiment. The range of water uptake ratio, hardness after soaking and hardness after steaming were 117.00~131.33%, 1.65~3.30 kg and 0.05~0.14 kg, respectively. The physicochemical analysis indicated the following: Moisture content, 63.27~68.72%; pH, 6.43~6.60; total acidity, 0.27~0.45%. Color values for L value (lightness), a value (redness), and b value (yellowness) ranged from 39.07~67.92, 7.64~11.79, and 7.48~20.67, respectively. The amylase and protease activities of the Saedanbaek samples were the highest among all cultivars. The amount of viscous substance in the fermented soybean products by cultivars ranged from 5.93 to 8.37%, and Saedanbaek was the highest. The total viable cells counts for soybean fermented products were 9.11~9.42 log CFU/g. The amino-type nitrogen contents of all samples were in the range of 401.07 to 524.47 mg% and Saedanbaek cultivars showed the highest content (524.47 mg%). Based on the results, Saedanbaek will be suitable as a soy-paste soybean cultivar and the quality standards for the fermentation process of the fermented soybean products.

This study investigates Ag coated Cu2O nanoparticles that are produced with a changing molar ratio of Ag and Cu2O. The results of XRD analysis reveal that each nanoparticle has a diffraction pattern peculiar to Ag and Cu2O determination, and SEM image analysis confirms that Ag is partially coated on the surface of Cu2O nanoparticles. The conductive paste with Ag coated Cu2O nanoparticles approaches the specific resistance of 6.4 Ω·cm for silver paste(SP) as (Ag) /(Cu2O) the molar ratio increases. The paste(containing 70 % content and average a 100 nm particle size for the silver nanoparticles) for commercial use for mounting with a fine line width of 100 μm or less has a surface resistance of 5 to 20 μΩ·cm, while in this research an Ag coated Cu2O paste has a larger surface resistance, which is disadvantageous. Its performance deteriorates as a material required for application of a fine line width electrode for a touch panel. A touch panel module that utilizes a nano imprinting technique of 10 μm or less is expected to be used as an electrode material for electric and electronic parts where large precision(mounting with fine line width) is not required.

PURPOSES : In this paper, the flow of cement paste layers that were contoured at different times were simulated by computational fluid dynamics in 2D axisymmetric conditions to evaluate the effect of yield stress on the flow of cement paste layers. METHODS: In the 2D domain, the cylindrical-shaped bottom layer was placed on even ground and allowed to flow by gravitational force for only 25 s. The exact same shape of cement paste, the top layer, was placed on top of the bottom layer, and both layers were allowed to flow for an additional 25 s. The shape and pressure of both layers were evaluated. RESULTS: The relationship between the yield stress and diameter of the layer was clearly observed from the numerical simulation results. It was also observed that the interface between the top and bottom layers was affected by the yield stress and fluidity of materials. The total pressure underneath the bottom layer can be a good indicator of whether the material is still flowing or not. CONCLUSIONS: The Navier-Stokes equation with Bingham model is an excellent model to simulate the flow of contoured layers, which can be used to explain the flow of materials in various areas such as wet-on-wet pavement construction, structural member precasting, and 3D printing construction.

In recent years, solar cells based on crystalline silicon(c-Si) have accounted for much of the photovoltaic industry. The recent studies have focused on fabricating c-Si solar modules with low cost and improved efficiency. Among many suggested methods, a photovoltaic module with a shingled structure that is connected to a small cut cell in series is a recent strong candidate for low-cost, high efficiency energy harvesting systems. The shingled structure increases the efficiency compared to the module with 6 inch full cells by minimizing optical and electrical losses. In this study, we propoese a new Conductive Paste (CP) to interconnect cells in a shingled module and compare it with the Electrical Conductive Adhesives (ECA) in the conventional module. Since the CP consists of a compound of tin and bismuth, the module is more economical than the module with ECA, which contains silver. Moreover, the melting point of CP is below 150 ℃, so the cells can be integrated with decreased thermal-mechanical stress. The output of the shingled PV module connected by CP is the same as that of the module with ECA. In addition, electroluminescence (EL) analysis indicates that the introduction of CP does not provoke additional cracks. Furthermore, the CP soldering connects cells without increasing ohmic losses. Thus, this study confirms that interconnection with CP can integrate cells with reduced cost in shingled c-Si PV modules.

We investigate the effect of the modification of cellulose acetate propionate as an organic vehicle for silver paste on solar cell efficiency. For the modification of cellulose acetate propionate, poly(ethylene glycol) is introduced to the hydroxyl groups of a cellulose acetate propionate backbone via esterification reaction. The chemical structure and composition of poly(ethylene glycol) functionalized cellulose acetate propionate is characterized by Attenuated total reflectance Fourier transform infrared, 1H nuclear magnetic resonance, differential scanning calorimetry and thermogravimetric analysis. Due to the effect of structural change for poly(ethylene glycol) functionalized cellulose acetate propionate on the viscosity of silver paste, the solar cell efficiency increases from 18.524% to 18.652 %. In addition, when ethylene carbonate, which has a structure similar to poly(ethylene glycol), is introduced to cellulose acetate propionate via ring opening polymerization, we find that the efficiency of the solar cell increases from 18.524% to 18.622%.

This study was conducted to investigate the quality of pumpkin paste added with different starches during storage at 4℃ for 8 days. Pumpkin paste was evaluated for pH, carotenoid, syneresis, color values, texture, and sensory characteristics. The properties of the pumpkin paste were studied on three different starches (CON: control, MCP: cow pea starch, MMB: mung bean starch, and MSP: sweet potato starch). The initial pH of the pumpkin paste with starches were 6.13~6.16. The pH of pumpkin paste increased as the starches added increased. The carotenoid content of CON was higher in the pumpkin paste processing. The change of syneresis significantly increased with the storage period, and the amount of change of MCP and MMB added with starch was smaller than CON without the added starch. The Hunter's L-values of the pumpkin paste increased, whereas the a- and b-value decreased as the amount of starches added increased. The results of the textural analysis showed that the hardness of MCP and MMB was different from that of other pumpkin paste, showing a lower value such as 38.26 g, 38.93 g, while CON and MSP was 40.43 g and 42.49 g, respectively. A sensory evaluation indicated that starches could enhance the overall texture characteristics of pumpkin paste. In terms of the overall acceptance of the pumpkin paste, the experimental group with MCP scored the best.

The objective of this study was to investigate the quality and sensory characteristics of yanggaeng prepared with different amounts of ginseng paste. Ginseng paste was incorporated with yanggaeng at a range of different levels of 5~15% based on the total weight of water. The pH and total acidity of yanggaeng were 6.35~6.49% and 0.03~0.07%, respectively. The sugar content of yanggaeng in the control was 25.0 °Brix and showed proportional increases up to 25.0~29.7 °Brix with increasing levels of ginseng paste. In terms of the texture profile analysis, the hardness and adhesiveness of yanggaeng decreased but the cohesiveness, gumminess, and chewiness increased compared to the control and ginseng paste added treatments. In color value determination, the L* and a* values decreased but the b* value increased with increasing levels of ginseng paste. The sensory evaluation indicated that the yanggaeng contained up to 15% ginseng paste and showed similar flavor, taste, texture, and overall acceptance in the control. These results suggest that ginseng paste is an ingredient that can enhance the quality and sensory potential of yanggaeng.

A metal mesh TCE film is fabricated using a series of processes such as UV imprinting of a transparent trench pattern (with a width of 2-5 μm) onto a PET film, filling it with silver paste, wiping of the surface, and heatcuring the silver paste. In this work nanosized (40-50 nm) silver particles are synthesized and mixed with submicron (250-300 nm)-sized silver particles to prepare silver paste for the fabrication of metal mesh-type TCE films. The filling of these silver pastes into the patterned trench layer is examined using a specially designed filling machine and the rheological testing of the silver pastes. The wiping of the trench layer surface to remove any residual silver paste or particles is tested with various mixture solvents, and ethyl cellosolve acetate (ECA):DI water = 90:10 wt% is found to give the best result. The silver paste with 40-50 nm Ag:250-300 nm Ag in a 10:90 wt% mixture gives the highest electrical conductance. The metal mesh TCE film obtained with this silver paste in an optimized process exhibits a light transmittance of 90.4% and haze at 1.2%, which is suitable for TSP application.

Solder paste is widely used as a conductive adhesive in the electronics industry. In this paper, nano and microsized mixed lead-free solder powder (Sn-Ag-Cu) is used to manufacture solder paste. The purpose of this paper is to improve the storage stability using different types of solvents that are used in fabricating the solder paste. If a solvent of sole acetate is used, the nano sized solder powder and organic acid react and form a Sn-Ag-Cu malonate. These formed malonates create fatty acid soaps. The fatty acid soaps absorb the solvents and while the viscosity of the solder paste rises, the storage stability and reliability decrease. When ethylene glycol, a dihydric alcohol, is used the fatty acid soaps and ethylene glycol react, preventing the further creation of the fatty acid soaps. The prevention of gelation results in an improvement in the solder paste storage ability.

PURPOSES : It is necessary to clarify the rheological properties of cement paste as a basic research in the development of mechanistic concrete mix design. The rheological properties of cement paste with different binder types, mix propositions, and with/without high range water reducers have been analyzed. METHODS: In this study, ordinary Portland cement, fly-ash, blast furnace slag, silica fume, and limestone powder were used as binders. The range of water-binder ratio was 0.3-0.5, and a total of 30 different mixes have been tested. The slump flow test, V-funnel test, and Dynamic Shear Rheometer (DSR) test were performed to analyze the rheological properties of cement paste. RESULTS : As a result of the slump flow test, it was found that the composition ratio of the binder contents greatly affected the paste flow when the high range water reducers were added. The results of V-funnel test showed that when the water-binder ratio was decreased without high range water reducers, the binder composition ratio had a large effect on the passing time of the V-funnel tester, but with high range water reducers the impact of the binder composition ratio was decreased. The slump flow and V-funnel have a certain relationship with the rheological factors (yield stress and plastic viscosity), but the correlation was not significant. Finally, we proposed the M-value considering the density and specific surface area of the binder. The correlation between rheological factors and M-value were better demonstrated than experimental values, but there is still a limit to predict the rheological factor in general mix design. CONCLUSIONS: In this study, the rheological properties of cement paste were analyzed. The binder type, composition ratio of binder, and with/without high range water reducers have combined to provide the complex effects on the rheological properties of cement paste. The correlation between the proposed M-value and rheological factor was found to be better than experimental results, but needs to be improved in the future.

We used an etching process to control the line-width of screen printed Ag paste patterns. Ag paste was printed on anodized Al substrate to produce a high power LED. In general, Ag paste spreads or diffuses on anodized Al substrate in the process of screen printing; therefore, the line-width of the printed Ag paste pattern increases in contrast with the ideal line-width of the pattern. Smudges of Ag paste on anodized Al substrate were removed by neutral etching process without surface damage of the anodized Al substrate. Accordingly, the line-width of the printed Ag paste pattern was controlled as close as possible to the ideal line-width. When the etched Ag paste pattern was used as a seed layer for electroless Ni plating, the line width of the plated Ni film was similar to the line-width of the etched Ag paste pattern. Finally, in pattern formation by Ag paste screen printing, we found that the accuracy of the line-width of the pattern can be effectively improved by using an etching process before electroless Ni plating.