• 대한기계학회논문집
• /
• 제13권2호
• /
• pp.307-315
• /
• 1989

본 연구에서는 단조과정을 거친후 노멀라이징(normalizing) 처리된 SF45A강종과 압연후 자연 냉각시킨 SM41B강종의 두 국산 강종에 대해 저사이클 피로시험을 행하여 저사이클 피로특성을 밝히고, 강재의 가공공정과 부하변형율변화에 따른 피로과정중의 연화 및 경화 거동을 관찰하였다. 그리고 저사이클 피로파면의 미시적 고찰을 통해서 부하변형율 크기에 따른 미시적 파면 양상의 변화를 밝혀 파괴 해석의 기초자료로 제공하였다.

• 한국세라믹학회지
• /
• 제53권3호
• /
• pp.376-380
• /
• 2016

A composite electrode made of iron oxide nanoparticles/multi-wall carbon nanotube (iNPs/M) delivers high specific capacity and cycle durability. At a rate of $200mAg^{-1}$, the electrode shows a high discharge capacity of ${\sim}664mAhg^{-1}$ after 100 cycles, which is ~ 70% of the theoretical capacity of $Fe_3O_4$. Carbon black, carbon nanotube, and graphene as anode materials have been explored to improve the electrical conductivity and cycle stability in Li ion batteries. Herein, iron oxide nanoparticles on acid treated MWCNTs as a conductive platform are combined to enhance the drawbacks of $Fe_3O_4$ such as low electrical conductivity and volume expansion during the alloying/dealloying process. Enhanced performance was achieved due to a synergistic effect between electrically 3D networks of conductive MWCNTs and the high Li ion storage ability of $Fe_3O_4$ nanoparticles (iNPs).

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제6권3호
• /
• pp.194-199
• /
• 2001

Chlorella kessleri cultivated in artificial wastewater using diurnal illumination of 12h light/12h dark (L/D) cycles. The inoculum density was 10(sup)5 cells/mL and the irradiance in light cycle was 45$\mu$mol㎡s(sup)-1 at the culture surface. As a control culture, another set of flasks was cultivated under continuous illumination. Regardless of the illumination scheme, the total organic carbon (TOC) and chemical oxygen demand (COD) was reduced below 20% of the initial concentration within a day. However, cell concentration under the L/D lighting scheme was lower tan that under the continuous illuminating scheme. Thus the specific removal rate of organic carbon under L/D cycles was higher than that under continuous illumination. This result suggested that C. kessleri grew chemoorganotrophically in the dark periods. After 3 days, nitrate was reduced to 136.5 and 154.1mg NO$_3$-N/L from 168.1mg NO$_3$-N/L under continuous illumination and under diurnal cycles, respectively. These results indicate nitrate removal efficiency under continuous light was better than that under diurnal cycles. High-density algal cultures using optimized photobioreactors with diurnal cycles will save energy and improve organic carbon sources removal.

• Journal of Plant Biotechnology
• /
• 제37권2호
• /
• pp.205-211
• /
• 2010

Yield productivity of staple crops must be increased at least 50% by 2050, in order to feed the world population which is expected to reach 90 billions. Photosynthetic carbon assimilation and carbohydrate metabolism leading to the production of starch would be the final frontier to quest for new sources of technology enabling such a drastic increase of crop productivity. In this review, attempts to genetically engineer plant photosynthetic carbon reduction cycle and metabolic pathways to increase starch production are introduced.

• 한국재료학회지
• /
• 제3권5호
• /
• pp.514-520
• /
• 1993

다구찌의 실험계획기법을 이용하여 탄소섬유/페놀수지의 결화싸이클을 연구하였다. 본 연구에서는 1인자 2수준과 7인자 3수준으로 구성된 $L_{18}(2^1 \times 3_7)$ 직교배열표를 사용하였고, 특성치로 굴곡강도와 기공률을 선정하여 실험하였다. 실험계획법의 압축성형 인자로는 8개의 성형인자(승온속도, 가압온도, 성형압력, 경화온도, 경화온도에서의 유지시간, 냉각속도 및 탈기포)가 고려되었으며, 이들 성형인자가 탄소섬유/페놀수지 복합재료의 물성에 미치는 영향을 고찰하였다. 분산분석법으로 실험결과를 분석한 결과, 탄소섬유/패놀수지 복합재료의 굴곡강도에 가장 큰 영향을 미치는 성형인자는 성형압력이고, 기공률에 가장 큰 영향을 미치는 성형인자는 경화온도임이 밝혀졌다.

• Corrosion Science and Technology
• /
• 제7권6호
• /
• pp.328-331
• /
• 2008

Corrosion behaviour of water intake gate steel structures with different protective measures was investigated. Five material alternatives were taken for investigation, including: imported and recycled stainless steel, carbon steel with hot zinc spraying, painting and composite coatings. Results of corrosion rate for carbon steel, SUS 304, hot zinc spray coats in three water systems of Mekong river basin (saline, blackish and fresh) were also presented. Corrosion rate of carbon steel decreased with decreasing salinity in the investigated water environments. Meanwhile, these values for zinc coated steel, behaved by another way. Environmental data for these systems were filed and discussed in relation with corrosion characteristics. Method of Life Cycle Assessment (LCA) was applied in materials selection for water intake gate construction. From point of Life Cycle Cost (LCA) the following ranking was obtained: Zinc sprayed steel < Recycled stainless steel < Composite coated steel < Painting steel < SUS 304 From investigated results, hot zinc spray coating has been applied as protective measure for steel structures of water intake systems in Mekong river basin.

• 한국디지털건축인테리어학회논문집
• /
• 제12권2호
• /
• pp.67-76
• /
• 2012

BIM and its quantity take-off widely apply to the construction projects and LCCO2 Assessment using the BIM's quantity take-off function can be tried recently. Because BIM modeling programs such as Revit and ArchiCAD do not provide adequate library for LCCO2 Assessment, quantity take-off data should be conversed and applied to Carbon Emission Coefficient using Excel program or manual work. Therefore, the purpose of this research is 1) to propose the Unit Conversion Systems for Carbon Emission Coefficient, 2) to provide basic library sets for BIM based LCCO2 Assessment method, and 3) to apply 11 material library sets on a apartment unit plan modeling to pursue the CO2 emission evaluation of the material production in the process of LCCO2 Assessment. Research results showed CO2 emission amount of 458.64kgCO2/m2 from the apartment unit plan modeling.

• Journal of Electrochemical Science and Technology
• /
• 제12권3호
• /
• pp.317-322
• /
• 2021

Silicon (Si) has been considered as a promising anode material because of its abundant reserves in nature, low lithium ion (Li⁺) intercalation/de-intercalation potential (below 0.5 V vs. Li/Li⁺) and high theoretical capacity of 4200 mA h/g. In this paper, we prepared a silicon-based (Si-based) anode material containing a small amount of silicon carbide by using magnesiothermic coreduction of silica and hexachlorobenzene. Because of good conductivity of silicon carbide, the cycle performance of the silicon-based anode materials containing few silicon carbide is greatly improved compared with pure silicon. The raw materials were formulated according to a silicon-carbon molar ratio of 10:0, 10:1, 10:2 and 10:3, and the obtained products were purified and tested for their electrochemical properties. After 1000 cycles, the specific capacities of the materials with silicon-carbon molar ratios of 10:0, 10:1, 10:2 and 10:3 were still up to 412.3 mA h/g, 970.3 mA h/g, 875.0 mA h/g and 788.6 mA h/g, respectively. Although most of the added carbon reacted with silicon to form silicon carbide, because of the good conductivity of silicon carbide, the cycle performance of silicon-based anode materials was significantly better than that of pure silicon.

• Journal of Electrochemical Science and Technology
• /
• 제14권3호
• /
• pp.222-230
• /
• 2023

Capacitive deionization of saline water is one of the most promising water purification technologies due to its high energy efficiency and cost-effectiveness. This study synthesizes porous carbon composites composed of reduced graphene oxide (rGO) and activated carbon (AC) with various rGO/AC ratios using a facile chemical method. Surface characterization of the rGO/AC composites shows a successful chemical reduction of GO to rGO and incorporation of AC into rGO. The optimized rGO/AC composite electrode exhibits a specific capacitance of ~243 F g^-1 in a 1 M NaCl solution. The galvanostatic charging-discharging test shows excellent reversible cycles, with a slight shortening in the cycle time from the ~260^th to the 530^th cycle. Various monovalent sodium salts (NaF, NaCl, NaBr, and NaI) and chloride salts (LiCl, NaCl, KCl, and CsCl) are deionized with the rGO/AC electrode pairs at a cell voltage of 1.3 V. Among them, NaI shows the highest specific adsorption capacity of ~22.2 mg g^-1. Detailed surface characterization and electrochemical analyses are conducted.

• 대한기계학회논문집B
• /
• 제26권12호
• /
• pp.1729-1737
• /
• 2002

A mathematical model for the prediction of carbon-dioxide absorption rate during the transient state of rotary type absorber is developed. The rotary type absorber operates using a fast rotating porous structure and clean water. The model for the transient state rotary type absorbers is based on the steady state model of packed tower absorber. The paper manipulates the operating data of an arbitrary quasi-steady state condition of rotary type absorber for the determination of the coefficients involved in the model developed. The prediction accuracy is evaluated from the measured data of rotary type absorber operated under fast transient state. The measured data include the mole fraction of carbon dioxide in mixed gas and the pressure of absorber. The relative error in carbon dioxide prediction is estimated to be 20% at maximum. The model is successfully applied for the prediction of the behavior of a closed cycle diesel engine.