검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 58

        1.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        MMBR system has been suggested as a promising system to resolve harvesting problems induced from low settling efficiency of microalgae. And recently, a lot of research on reducing fouling at the MMBR system has investigated focused on EPS in many cases. EPS of microalgae mainly consists of polysaccharides and protein components, and is produced through photosynthesis and nitrogen-carbon metabolic pathways. Especially, P-EPS is one of major compounds which occur membrane fouling phenomenon, as its hydrophobic protein components cause floc formation and cake layer accumulation. And it is already known that almost every microalgae can metabolize P-EPS or Chl-a when nitrogen sources as a substrate is insufficient or exhausted situation. With the above backgrounds, uptake rates of P-EPS or Chl-a by Scenedesmus quadricauda according to the type of carbon source and nitrogen concentration were evaluated in order to verify correlation between carbon source vs P-EPS production, and indeed Scenedesmus quadricauda uses P-EPS or Chl-a when the amounts of nitrogen sourc es in the feed is not satisfied. As a result, it was shown that P-EPS and Chl-a production were increased proportional to nitrogen concentration under organic carbon condition. And especially, the amo unts of P-EPS and Chl-a in the cell were diminished with the nitrogen source becomes insufficient or exhausted. Because P-EPS accelerates fouling at the MMBR system, P-EPS degradation by Scenedesmus quadricauda in order to get nitrogen source may contribute to reducing fouling. About a affects of N-consumed Chl-a to the MMBR fouling, more survey is needed. On the contrary, considering the purpose of MMBR system of this study, i.e. harvesting useful high value microalgae efficiently feeding adequate industrial process wastewater, it seems like difficult to maintain satisfied metabolic activity and to harvest with high yield rate using nitrogen-poor MMBR feed.
        4,200원
        2.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In general, trans-membrane pressure (TMP), flux, filtration resistance are used as indicators to evaluate the degree of fouling in MBR. However, they have limitations in determining the level of EPS generation, which is known as an important factor of fouling. Therefore, a new evaluation method is required to monitor the amount of EPS generation. In this study, the applicability of capillary suction time (CST), which is used to measure the dewaterability of sludge, was evaluated as an indirect fouling evaluation index. Statistical analysis was performed to evaluate the effect of EPS on CST, and to determine whether EPS has high similarity with representative fouling evaluation indicators and CST, and quantitatively compared them. As a result, the correlation coefficient between CST and bEPS was 0.7988, which was higher than the correlation coefficient between filtration resistance and bEPS. Since bEPS is a major factor inducing fouling by affecting the formation of the cake layer, it was evaluated that CST, which has a high correlation with bEPS, is suitable to represent EPS. In addition, it was evaluated that the correlation coefficient between filtration resistance and CST was high as 0.7187, which could be used as a fouling evaluation index.
        4,000원
        3.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In MBR, extracellular polymeric substance (EPS) is known as an important factor of fouling; soluble EPS (sEPS) affects internal contamination of membrane, and bound EPS (bEPS) affects the formation of the cake layer. The production of EPS changes according to the composition of influent, which affects fouling characteristics. Therefore, in this study, the effects of the F/M ratio on the sEPS concentration, bEPS content, and fouling were evaluated. The effects of F/M ratio on the amount and composition of EPS were confirmed by setting conditions that were very low or higher than the general F/M ratio of MBR, and the fouling occurrence characteristics were evaluated by filtration resistance distribution. As a result, it was found that the sEPS increased significantly with the increase of the F/M ratio. When the substrate was depleted, bEPS content decreased because bEPS was hydrolyzed into BAP and seemed to be used as a substrate. In contrast, when the substrate is sufficient, UAP (utilization-associated products) was rapidly generated in proportion with the consumption of the substrate. UAP has a relatively higher Protein/Carbohydrate ratio (P/C ratio) than BAP, and this means, it has a higher adhesive force to the membrane surface. As a result, UAP seems like causing fouling rather than BAP (biomass-associated products). Therefore, Rf (Resistance of internal contamination) increased rapidly with the increase of UAP, and Rc (Resistance of cake layer) increased with the accumulation of bEPS in proportion, and as a result, the fouling interval was shortened. According to this study, a high F/M ratio leads to an increment in UAP generation and accumulation of bEPS, and by these UAP and bEPS, membrane fouling is promoted.
        4,000원
        4.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Biological phosphorus removal is accomplished by exposing PAO(phosphorus accumulating organisms) to anaerobic-aerobic conversion conditions. In the anaerobic condition, PAO synthesize PHB(polyhydroxybutyrate) and simultaneously hydrolysis of poly-p resulting phosphorus(Pi) release. In aerobic condition, PAO uptake phosphorus(Pi) more than they have released. In this study, cyanobacteria Synechococcus sp., which is known to be able to synthesize PHB like PAO, was exposed to anaerobic-aerobic conversion. If Synechococcus sp. can remove excess phosphorus by the same mechanism as PAO, synergistic effects can occur through photosynthesis. Moreover, Synechococcus sp. is known to be capable of synthesizing PHB using inorganic carbon as well as organic carbon, so even if the available capacity of organic carbon decreases, it was expected to show stable phosphorus removal efficiency. In 6 hours of anaerobic condition, phosphorus release occurred in both inorganic and organic carbon conditions but SPRR(specific phosphorus release rate) of both conditions was 10 mg-P/g-MLSS/day, which was significantly lower than that of PAO. When converting to aerobic conditions, SPUR(specific phosphorus uptake rate) was about 9 mg-P/g-MLSS/day in both conditions, showing a higher uptake rate than the control condition showing SPUR of 6.4 mg-P/g-MLSS/day. But there was no difference in terms of the total amount of removal. According to this study, at least, it seems to be inappropriate to apply Synechococcus sp. to luxury uptake process for phosphorus removal.
        4,000원
        5.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the effect of perceived risk, community usage motive, and price sensitivity of customers who purchase children’s wear directly from overseas on customer satisfaction. Specifically, this study is aimed at verifying the moderating effect of price sensitivity when perceived risk and community usage motive significantly influence customer satisfaction. A survey was conducted among consumers who experienced directly purchasing children’s wear from overseas and engaging in communities. A total of 415 questionnaires were distributed, which 41 responses were insincere and excluded; thus, 374 responses were analyzed. Results of this study are as follows. First, the analysis on how perceived risk and community usage motive influence customer satisfaction reveals the significant influence of economic and social psychological risk on customer satisfaction. Moreover, informational, recreational, and social emotional usage motive have a significant influence on customer satisfaction. Second, the effect of perceived risk and community usage motive on customer satisfaction based on different levels of price sensitivity was verified. As a result, delivery and economic risks affect customer satisfaction for consumers with high price sensitivity. Moreover, recreational usage motive has a significant influence on customer satisfaction for high price sensitive consumers. In conclusion, perceived risk negatively impacts customer satisfaction. Therefore, it is essential to provide a system that can reduce the perceived risk of consumers who purchase children’s wear directly from overseas.
        4,000원
        6.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates the effects of the type of advertisement, brand extension, and consumer innovativeness on the credibility of fashion advertisements. The factorial design is constructed as a 2(type of fashion advertisement: general vs. cross-media) × 2(consumer innovativeness: high vs. low) × 2(the type of fashion brand extension: similar vs. dissimilar) three-way mixed design in which consumer innovativeness is the between-subjects variable. Subjects of this study included 210 men and women in their 20s and 30s who resid in Seoul and had SNS experiences. Frequency analysis, credibility analysis, three-way ANOVA, and simple interaction analysis were conducted using the SPSS 20.0 statistics package. The results are as follows: First, the type of fashion advertisement had a significant effect on advertising credibility. Cross-media advertisements had a more positive effect than general advertisements on all of the dependent variables. Also, the type of brand extension and consumer innovativeness showed significant effect on advertising credibility and the interaction effect between the type of fashion advertisement and consumer innovativeness was significant. Lastly, the effect of different types of brand extensions on advertising credibility showed a significant difference according to consumer innovativeness. Thus, a marketing strategy using cross-media advertising is proven to be effective in gaining consumer trust for a fashion brand.
        4,500원
        7.
        2018.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, effects of nutrient and inorganic carbon on single cell emergence during the cultivation of microalgae were observed using colonial green algae, Pediastrum duplex. The concentration of inorganic carbon had significant effect on single cell emergence and its growth, but nitrogen and phosphorus concentration showed minor effects. According to P. duplex cultivation experiment, single cell started to be emerged around 500~750 mg-C/L of inorganic carbon concentration and it was bloomed dramatically at the higher values. And growth of P. duplex was started to be surpressed at the single cell formation concentration. From the results, it could be said that when we operate the microalgae systems for cultivation/harvesting or wastewater treatment, in order to avoid single cell formation, inorganic carbon should be maintained to the proper level
        4,000원
        8.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to investigate growth rate and nutrient consumption of Chlorella vulgaris according to different light irradiation interval. Applied light irradiation intervals were 12 hr, 4 hr, 1 hr, and 1 min. The light source was flexible LED(Blue:Red=1:1), light intensity was 200 PPFD and Light/Dark cycle was 1:1. As a result, growth rate and nutrient removal efficiencies showed no significant differences depending on the light irradiation interval. Considering the reproduction characteristics of applied microalgae cultures of this study, this is thought to be one of the possible reasons of above results. Because Chlorella vulgaris performs an asexual reproduction and it is known that there is no significant relationship between light irradiation interval and growth rate, including nutrient consumption in case of asexual reproduction.
        4,000원
        9.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Acetate, propionate, butyrate are the major soluble volatile fatty acids metabolites of fermented food waste leachates. This work investigate the effects of volatile fatty acid on the growth rate and NH4-N, PO4-P removal efficiency of mixotrophic microalgae Chlorella vulgaris to treat digested food waste leachates. The results showed that acetate, propionate and butyrate were efficiently utilized by Chlorella vulgaris and microalgae growth was higher than control condition. Similar trends were observed upon NH4-N and PO4-P consumption. Volatile fatty acids promoted Chlorella vulgaris growth, and nutrient removal efficiencies were highest when acetate was used, and butyrate and propionate showed second and third. From this work it could be said that using mixotrophic microalgae, in this work Chlorella vulgaris, fermented food waste leachates can be treated with high efficiencies.
        4,000원
        10.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the effect of high concentration of free ammonia on microalgal growth and substrate removal by applying real wastewater nitrogen ratio. To test of this, the conditions of free ammonia 1, 3, 6, 9, 12, 15 mg-N/L are compared. After 3 days of incubation, algal growth of Chlorella vulgaris and carbon removal rate are respectively lower in the reactors of FA 12, 15 mg-N/L compared to the others. This indicates that the high concentration of free ammonia, in this case, above 12 mg-N/L, has negative effect on algal growth and metabolic activity. Also, high concentration of free ammonia causes the proton imbalance, ammonium accumulation in algae and has toxicity for these reasons. So, we have to consider free ammonia in applying the microalgae to wastewater treatment system by the way of diluting wastewater or controlling pH and temperature.
        4,000원
        11.
        2015.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Although microalgae are considered as a promising feedstock for biofuels, cost-efficient harvesting of microalgae needs to be significantly improved. In this study, the use of electro coagulation as a more rapid flocculation method for harvesting a freshwater (Scenedesmus dimorphus) microalgae species was evaluated. The results showed that, electro coagulation was shown to be more efficient using an aluminum anode than using an iron anode. And optimum conditions of electro coagulation for harvesting Scenedesmus dimorphus were found. The optimum stirring speed was 100 rpm and optimum pH was 5. Furthermore, the current density which the fastest and highest recovery efficiency is achieved at 30 A/m2, while the highest energy efficiency was achieved at 10 A/m2. A the rapid and high recovery efficiency indicate that electro coagulation is a particularly attractive technology for harvesting microalgae.
        4,000원
        12.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the effects of the light conditions on the productivity of scenedesmus dimorphus in the continuous mass cultivation system. To compare the algal productivity according to the light conditions, S. dimorphus was cultivated continuously under the wide range of light intensity(200-600 PPFD) and various light wavelength(white light and red-blue mixed light). After 100 days of cultivation under the different light intensity, the productivity of S. dimorphus increased as light intensity decreased. So, the productivity was maximized as 100 mg/L/d when light intensity was 200 PPFD. In case of light wavelength, the productivity of S. dimorphus was enhanced about 20% with the white light compared to that of the red-blue mixed light. Consequently, the optimal light conditions for the continuous mass cultivation of S. dimorphus were 200 PPFD as light intensity and white light as light wavelength.
        4,000원
        13.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to identify the effects of fashion brand extensions types, preannouncing and consumers' regulatory focus on preference towards extension products. To that end, the study used a 2 (fashion brand extension types: similar vs. non-similar) × 2 (preannouncing: near preannouncing vs. far preannouncing) × 2 (regulatory focus: promotion focus vs. prevention focus) three mixed elements. The subjects of the study were 280 men and women in their 20~40s living in Seoul and Chungnam province and total of 229 data were analyzed. Data were analysed with SPSS 19.0 program and three-way ANOVA, simple interaction effects and simple main effects analysis were conducted. The results of this study are as follows: First there were significant differences in preference based on fashion brand extension types and preannouncing. Second, there were significant interaction effects in preference between extension types of fashion brand and regulatory focus. But there was no difference in preference toward extension products according to types of preannouncing and regulatory focus. Lastly, fashion brand extension types, preannouncing and regulatory focus showed significant interaction effects on preference. Thus even in cases of non-similar brand extensions which carry more risk of failing, the appropriate marketing communication strategies such as preannouncing will result in brand preference. Also marketing activities should be comprehensive and strategical based on consumers’ tendencies in order to derive positive evaluations.
        4,800원
        14.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the effect of a co-culture of Scenedesmus dimorphus and nitrifiers using artificial wastewater on the removal of ammonium, nitrate and phosphate in the advanced treatment. To test the synergistic effect of the co-culture, we compared the co-culture treatment with the cultures using S. dimorphus-only and nitrifiers-only treatment as controls. After 6 days of incubation, nitrate was removed only in the co-culture treatment and total amount of N removal was 1.3 times and 1.6 times higher in the co-culture treatment compared to those in the S. dimorphus- and nitrifiers-only treatments, respectively. In case of total amount of P, co-culture treatment removed 1.2 times and 12 times more P than the S. dimorphus -and nitrifiers-only conditions, respectively. This indicates that the co-culture improved removal rates for ammonium, nitrate, and phosphate. This further implies that there was no need for denitrification of nitrate and luxury uptake of P processes because nitrate and phosphate can be removed from the uptake by S. dimorphus. In addition, co-culture condition maintained high DO above 7 mg/L without artificial aeration, which is enough for nitrification, implying that co-culture has a potential to decrease or remove aeration cost in the wastewater treatment plants.
        4,000원
        15.
        2014.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        VFAs like acetate are the major soluble metabolites of food waste leachates after digested. Therefore this study investigates the effect of acetate on growth rate and nutrient removal efficiency of Chlorella vulgaris to treat digested food waste leachates. The initial acetate concentration varied from 0 to 20 mM. As a result, Chlorella vulgaris growth rate was increased as high as the concentrations ranged from 0 to 20 mM. The same trend was observed with NH4-N and PO4-P consumption. The highest growth rate and the highest NH4-N, PO4-P removal rate were observed at acetate concentration of 20 mM. The microalgae growth rate and NH4-N, PO4-P removal rates were 1.5, 1.8, 2.3 times higher than the condition without acetate.
        4,000원
        16.
        2014.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates the effect of sodium bicarbonate (NaHCO3) on growth of S. dimorphus. NaHCO3 concentration was varied from 0 to 2 g-C/L. As a result, the increase in concentration of NaHCO3 up to 1.5 g-C/L increased dry weight of algae. The highest specific growth rate of S. dimorphus was 0.36 day-1 which was obtained at concentration of 0.5 g-C/L NaHCO3. pH showed a large variation range at the concentrations lower than 0.5 g-C/L NaHCO3 whereas inorganic carbon, nitrate and phosphorus removal rates were almost same at the concentrations higher than 0.5 g-C/L NaHCO3 (0.75, 1, 1.25, 1.5, 2 g-C/L NaHCO3). Their average inorganic carbon, nitrate and phosphorus removal rate were 70 mg-C/L/d, 11.3 mg-N/L/d, and 1.6 mg-P/L/d, respectively. Thus, NaHCO3 didn’t effect on inorganic carbon, nitrate and phosphorus removal rate of S. dimorphus.
        4,000원
        17.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Microalgae is known as one alternative energy source of the fossil fuel with the small size of 5 ~ 50 µm and negative charge. Currently, the cost of microalgae recovery process take a large part, about 20 - 30% of total operating cost. Thus, the microalgae recovery method with low cost is needed. In this study, the optimum current for Scenedesmus dimorphus recovery process using electrocoagulation techniques was investigated. Under the electrical current, Al metal in anode electrode is oxidized to oxidation state of Al3+. In the cathode electrode, the water electrolysis generated OH- which combine with Al3+ to produce Al(OH)3. This hydroxide acts as a coagulant to harvest microalgae.Before applying in 1.5 L capacity electrocoagulation reactor, Scenedesmus dimorphus was cultured in 20 L cylindrical reactor to concentration of 1 OD.The microalgae recovery efficiency of electrocoagulation reactor was evaluated under different current conditions from 0.1 ~ 0.3 A. The results show that, the fastest and highest recovery efficiency were achieved at the current or 0.3 A, which the highest energy efficiency was achieved at 0.15 A.
        4,000원
        18.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study looked into the scarcity effect based on the consumers' self-regulatory modes and determined the effect that such a regulatory mode and that quantity-scarcity messages would have on evaluations of fashion products. To that end, the study used a 2 (regulatory mode: assessment mode/locomotion mode)×2 (message type: quantity-scarcity message/non-scarcity message) between-subjects factorial design in which buying impulsiveness was presented as a mediator variable that showed differences in product evaluations depending on the message type and on the presence of a self-regulatory mode. The results of this study showed that locomotion-oriented consumers evaluated products more positively compared to assessment-oriented consumers when the quantity-scarcity message was presented. When a non-scarcity message was presented, no significant difference was observed in product evaluations based on the consumers' self-regulatory modes. In addition, buying impulsiveness in consumers served a mediator role in the evaluations of fashion products. The results of this study imply that a clear understanding of consumers is a prerequisite for maximizing the scarcity effect and that companies need to differentiate in terms of the way they use scarcity messages based on consumers' self-regulatory modes.
        4,500원
        19.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research used an experimental design in an effort to assess the influence of brand gender and salespeople on the attitudes toward brands according to the males' gender identity traits. The study used a three-way split-plot experimental design, and data were analyzed by t-tests, and ANOVA. The subject of this research was men in their 20s and 30s, and a total of 178 people were selected through convenience- sampling. The findings are as follows: first, masculine male consumers preferred masculinity fashion brands; however, androgynous consumers preferred brands that reflect androgyny. Second, there were no differences in brand attitude according to the gender of the salesperson for the masculinity group, but the androgynous group estimated the brands as better when the salesperson was female. Third, there were no differences in the brand attitudes among consumers according to gender of the salesperson for the Galaxy; however, for Solid Homme, brand preference was stronger when the salesperson was a woman. Fourth, the influence of brand gender and salesperson gender on brand attitudes differed according to the gender of the consumer. Therefore, apparel companies must clearly understand the characteristics of consumer gender identity and execute proper marketing strategies in order to induce stronger positive attitudes toward their brands. Moreover, apparel companies should perceive that brand gender and the gender of the salesperson can consequently encourage brand preferences.
        4,500원
        20.
        2014.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study focuses on verifying the effects of service education and empowerment on job satisfaction, job performance, and customer orientation. 290 salespeople working for fashion companies participated by completing a survey. The collected data was then analyzed with SPSS 16.0 and AMOS 7.0. Structural equation modeling was used to examine the goodness of fit. Looking at the results of this study, the service education of salespersons in fashion companies was shown to affect their level of satisfaction with their compensation, whereas empowerment affected their psychological satisfaction. These findings indicate that the service training and empowerment as experienced by salespersons working for fashion companies affect their customer orientation and job performance. Specifically, psychological satisfaction as part of the overall level of job satisfaction was found directly to affect their customer orientation, whereas their satisfaction with their compensation did not affect their customer orientation. Customer-orientation as influenced by service education and empowerment was revealed to have direct effect on job performance. The results of this study indicate that the service education of salesperson working for fashion companies and their level of empowerment create job satisfaction and customer orientation in these individuals. This study will be a valuable source of information for those who create salesperson empowerment programs and salesperson management strategies for fashion companies. Such programs and management strategies can facilitate efficient job performance by salespersons working for fashion companies and increase their level of job satisfaction.
        4,600원
        1 2 3