• 반도체디스플레이기술학회지
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• 제22권3호
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• pp.67-72
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• 2023

In this paper, a dye-sensitized solar cell (DSSC), one of the representative third-generation solar cells with eco-friendly materials and processes compared to other solar cells, was modeled using MATLAB/Simulink. The simulation was conducted by designating values of series resistance, parallel resistance, light absorption coefficient, and thin film electrode thickness, which are directly related to the efficiency of dye-sensitized solar cells, as arbitrary experimental values. In order to analyze the performance of dye-sensitized solar cells, the optimal value among each parameter experimental value related to efficiency was found using formulas for fill factor (FF) and conversion efficiency.

• 청정기술
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• 제25권4호
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• pp.289-295
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• 2019

비닐, 플라스틱의 사용이 전 세계에서 지속적으로 증가하고 있으나, 세계 각국의 폐비닐 또는 폐플라스틱의 처리를 위한 수입이 금지됨에 따라 자국 내의 친환경적 처리 또는 이용이 요구되고 있다. 폐비닐, 폐플라스틱의 친환경적인 처리에 대한 수요가 점차 증가하고 있으나, 폐비닐에 묻어 있는 이물질로 인하여 환경친화적인 재활용 방법이 제한되고 있다. 또한 기존의 매립, 소각 방법은 2차 오염의 발생과 처리 비용의 증가를 야기시키고 있다. 따라서 폐비닐에 포함되어 있는 타재질 및 이물질의 선별 제거는 폐비닐의 고부가가치 재활용을 가능케 할 수 있다. 특히 파쇄/선별이 단일 기기에서 동시에 이루어지는 신공정은 자원 재활용을 극대화시킨다. 본 연구는 파쇄/선별 융합 공정을 통해 이루어지는 폐비닐의 분리, 열적 재활용, 물질 재활용의 기술경제성을 평가하였다. 특히 국내 환경 정책에 따른 다양한 지원금들의 변화가 미치는 영향을 고찰하였다. 재활용 인센티브의 가격과 소각에 참여하는 폐비닐의 수율에 따라서 순현재가치와 내부수익률이 크게 변동되었다.

• 한국환경과학회지
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• 제29권10호
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• pp.997-1002
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• 2020

In this study, we investigated the effects of the eco-friendly chemical bio-sulfur, on the citrus melanose-causing pathogen, Diaporthe citri, and on the pest, Panonychus citri. In an open field experiment with a plot-scale application of the chemicals: Mancozeb, lime sulfur, lime sulfur + machine oil, and bio-sulfur, the control group showed 70.6% disease severity compared with 10.3% for the Mancozeb-treated group. Among the eco-friendly treatments, disease severity was the lowest for the group treated with lime sulfur + machine oil (32.2%) and was 53.9%, 58.8%, and 58.1% following treatment with lime sulfur, and bio-sulfur diluted 500 and 1000 times, respectively. The proportion of diseased fruit showed similar results, suggesting that bio-sulfur is an effective alternative to lime sulfur. Three days after treatment acaricidal effects on P. citri showed a 197.6% control survival rate whereas the machine oil, and bio-sulfur diluted 500 and 1000 times treatments showed rates of 2.9%, 5.8%, and 9.0%, respectively. After three days, the control value for bio-sulfur diluted 1000 times was 73.2% compared with the values for the machine oil (96.4%) and bio-sulfur diluted 500 times (94.6%) treatments. Therefore, we suggest that additional research is needed on the combined application of bio-sulfur and oils to enhance the additive control effect on citrus melanose and Panonychus citri.

• 한국의류학회지
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• 제33권11호
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• pp.1696-1706
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• 2009

Nonwoven fabrics have been widely used in various fields that include household, industrial, agricultural, medical goods, especially in the automobile industry. In this study, eco-friendly fiber materials were developed and investigated as a substitute material for polyester fibers in nonwovens. To make plant fiber bundles, stems of Indian mallow (IM), and Kuzu vine (KV) were retted; in addition, the non-cellulose component was partially removed. Plant fiber bundles and polyester fibers (P) were blended and needle punched to produce nonwovens. Five kinds of nonwovens were manufactured: P100 (Polyester 100%), IM10 (IM 10% and Polyester 90%), IM20 (IM 20% and Polyester 80%), KV10 (KV 10% and Polyester 90%), and KV20 (KV 20% and Polyester 80%). The color values, surface appearance, tensile strength, elongation, tear strength, abrasion strength, flexstiffness, moisture regain, water or oil absorbency, and static electricity of manufactured nonwovens are investigated. As the blended ratios of IM or KV increased, the brightness of nonwovens decreased compared to that of polyester 100%. Tensile strength, tear strength, abrasion strength, and flexstiffness of IM10 as well as KV10 were higher than those of P100, IM20, and KV20, resulting from the influence of the structure and properties of nonwoven fibers. Moisture regain and water or oil absorbency increased, while static electricity decreased in proportion to the amount of plant fibers. IM or KV and polyester blended nonwovens showed improved properties over P100 that could be substituted for P100 as a novel material for textiles.

• 한국염색가공학회지
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• 제29권3호
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• pp.115-121
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• 2017

Demands for nylon suede as an artificial leather are increasing due to its functionality and aesthetics. To achieve high value added nylon suede based on green technology, this study was carried out in order to obtain useful data for the nylon suede fabrics with eco-friendly dyeing process by a pad-steam method instead of a dip dyeing process using sulphur black dye to reduce the industrial waste of water. The dyeability of the nylon suede was investigated according to reducing temperatures, dye concentrations, and reducing agent's concentrations. Throughout the results of the CIE $L^*a^*b^*$ and Munsell values, the optimized dyeing conditions of the nylon suede using sulphur black dye are $70^{\circ}C$ of dyeing temperature, 30% o.w.f. of dye concentration, and $9g/{\ell}$ of reduction agent concentration, respectively. Furthermore washing colorfastness, light colorfastness and perspiration colorfastness were achieved in the range of 4-5 grades.

• Journal of Electrochemical Science and Technology
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• 제10권3호
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• pp.302-312
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• 2019

The voltage produced from the salinity gradient in reverse electrodialysis (RED) increases proportionally with the number of cell pairs of alternating cation and anion exchange membranes. Large-scale RED systems consisting of hundreds of cell pairs exhibit high voltage of more than 10 V, which is sufficient to utilize water electrolysis as the electrode reaction even though there is no specific strategy for minimizing the overpotential of water electrolysis. Moreover, hydrogen gas can be simultaneously obtained as surplus energy from the electrochemical reduction of water at the cathode if the RED system is equipped with proper venting and collecting facilities. Therefore, RED-driven water electrolysis system can be a promising solution not only for sustainable electric power but also for eco-friendly hydrogen production with high purity without $CO_2$ emission. The RED system in this study includes a high membrane voltage from more than 50 cells, neutral-pH water as the electrolyte, and an artificial NaCl solution as the feed water, which are more universal, economical, and eco-friendly conditions than previous studies on RED with hydrogen production. We measure the amount of hydrogen produced at maximum power of the RED system using a batch-type electrode chamber with a gas bag and evaluate the interrelation between the electric power and hydrogen energy with varied cell pairs. A hydrogen production rate of $1.1{\times}10^{-4}mol\;cm^{-2}h^{-1}$ is obtained, which is larger than previously reported values for RED system with simultaneous hydrogen production.

• 한국환경농학회지
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• 제40권1호
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• pp.60-66
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• 2021

BACKGROUND: The concern over heavy metal(loid)s in arable land and agricultural products increases for public health in recent years. This study aims to identify transition characteristics of heavy metal(loid)s and to assess dietary risk in barley grown at the major producing districts in Korea. METHODS AND RESULTS: The soil and barley samples were collected from 38 locations around the major producing districts at Jeollabuk-do in Korea for the propose of examining the concentrations of heavy metal(loid)s. The 34 barley samples were separately purchased on the market for the same survey. The average concentration and range of arsenic (As), cadmium (Cd) and lead (Pb) in barley grown at the major producing districts in Korea were 0.037 (0.016-0.094), 0.028 (0.004-0.083) and 0.137 (0.107-0.212) mg kg-1, respectively. Currently, the maximum allowable level for barley Pb is set at 0.2 mg kg-1 in Korea, and the monitoring results suggested that some samples exceeded the maximum allowable level and required appropriate farming management. Bio-concentration factor values by heavy metal(loid)s in barley were high at Cd, copper (Cu) and zinc (Zn), similar to other crops, while As and Pb were low, indicating low transferability. CONCLUSION: Human exposure to As, Cd and Pb through dietary intake of barley might not cause adverse health effects due to relatively low concentrations, although the Pb in some barley was detected higher than the maximum allowable level. Further study on uptake and accumulation mechanism of Pb by barley might be required to assess the human health risk associated with soil contamination.

• Advances in nano research
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• 제15권4호
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• pp.315-328
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• 2023

The main goal of the present study was to assess the effects of eggshell powder (ESP) and halloysite nanotubes (HNTs) on the mechanical properties of abaca fiber (AF)-reinforced natural composites. For this purpose, a limited number of indentation tests were first performed on the AF/polypropylene (PP) composites for different HNT and ESP loadings (0 wt.% ~ 6 wt.%), load amplitudes (150, 200, and 250 N), and two types of indenters (Vickers or conical). The Young's modulus, hardness and plasticity index of each specimen were calculated using the indentation test results and Oliver-Pharr method. The accuracy of the experimental results was confirmed by comparing the values of the Young's modulus obtained from the indentation test with the results of the conventional tensile test. Then, a feed-forward shallow artificial neural network (ANN) with high efficiency was trained based on the obtained experimental data. The trained ANN could properly predict the variations of the mentioned mechanical properties of AF/PP composites incorporated with different HNT and ESP loadings. Furthermore, the trained ANN demonstrated that HNTs increase the elastic modulus and hardness of the composite, while the incorporation of ESP reduces these properties. For instance, the Young's modulus of composites incorporated with 3 wt.% of ESP decreased by 30.7% compared with the pure composite, while increasing the weight fraction of ESP up to 6% decreased the Young's modulus by 34.8%. Moreover, the trained ANN indicated that HNTs have a more significant effect on reducing the plasticity index than ESP.

• 한국환경복원기술학회지
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• 제13권1호
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• pp.57-68
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• 2010

The purpose of this study is to analyze the characteristics of environment-friendliness of waterproof materials based on comprehensive experiments on waterproofness in terms of coefficients of permeability, harmfulness of waterproof materials and fish toxicity of Oryzias latipes mortality to verify eco-toxicity of each method of construction and waterproof material, which are to be applied by taking eco-toxicity into account when building ecological flows in upper areas on natural and artificial grounds. As a result, the following conclusions have been reached in this study: 1. In regard of the harmfulness analyzed, each material showed a different result of analytical value in each lab tank. Compared to input water, pH, COD, SS, T-P, and T-N values increased a little, but DO value decreased. The value of turbidity analyzed independent of the water quality standard of aquatic ecosystem set forth by the Ministry of Environment increased a little compared to the value in input water. 2. In the experiment of fish toxicity, compacted quicklime, cement fluid waterproof material, cement mortar waterproof material and bentonite powder were found to have 100% of fish mortality, respectively, and membrane waterproof material showed 83.3% of mortality, indicating strong fish toxicity. Improved asphalt sheet (63.3%) and synthetic rubber sheet (53.3%) were analyzed to have medium fish toxicity, while bentonite sheet (6.7%), Hwang-toh (6.7%) and clay (3.3%) showed relatively lower mortality and fish toxicity. 3. Regarding the analysis on waterproofness in terms of the coefficient of permeability of each waterproof material, improved asphalt sheet, synthetic rubber sheet, membrane waterproof material, cement fluid and mortar waterproof material and bentonite sheet were found impervious in case no leakage takes place in construction. Bentonite powder was found practically impervious based on the analytical results from the experiment done in compliance with weight ratios. So were the clay and Hwang-toh from the experimental results. To sum up such results as found in the experiment mentioned so far, the values of harmfulness and waterproofness analyzed were different in each lab tank, but there was absolutely little correlation with the mortality gained from the experiment on fish toxicity. In the experiment of fish toxicity, environment-friendly waterproof materials were analyzed, and it was found that clay, Hwang-toh and bentonite sheet are highly environment-friendly. In contrast, synthetic rubber and improved asphalt sheets were found to have medium-level environment-friendliness. Also, membrane water-proof materials, compacted quicklime, cement fluid and mortar waterproof material and bentonite powder were analyzed to have low environment-friendliness.

• Journal of Biosystems Engineering
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• 제38권3호
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• pp.180-184
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• 2013

Purpose: This study explored the factors influencing heating value in the process of torrefaction of water hyacinth. Methods: Torrefaction was applied with three temperature settings (200, 300, $400^{\circ}C$) and three time settings (1, 2, 3 h) using small electric heaters (11.3L of holding volume). This study investigated the heating values with the washing process and process factors influenced the torrefaction. In addition, this study compared the heating values in washed and unwashed samples and suggested the optimal conditions for increasing heating value. Results: Torrefaction increased the heating value by 8.18 ~ 30.04%. Comparing heating values of each condition, the optimal temperature for torrefaction was $300^{\circ}C$ and holding time was 1 hour. The washing process increased the heating value by 19 ~ 27%. The heating value of the sample treated at $300^{\circ}C$ for three hours was 4310.80 kcal/kg, which was greater than the first class wood pellet of 4300 kcal/kg. Conclusions: This study proved that the torrefaction and washing process increased the heating value of water hyacinth. Therefore, water hyacinth is expected to be an eco-friendly biomass which substitutes for wood pellet.