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A Study on the Optimum Design of Multiple Screw Type Dryer for Treatment of Sewage Sludge (하수슬러지 처리를 위한 다축 스크류 난류 접촉식 건조기의 최적 설계 연구)

  • Na, En-Soo;Shin, Sung-Soo;Shin, Mi-Soo;Jang, Dong-Soon
    • Journal of Korean Society of Environmental Engineers
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    • v.34 no.4
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    • pp.223-231
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    • 2012
  • The purpose of this study is to investigate basically the mechanism of heat transfer by the resolution of complex fluid flow inside a sophisticated designed screw dryer for the treatment of sewage sludge by using numerical analysis and experimental study. By doing this, the result was quite helpful to obtain the design criteria for enhancing drying efficiency, thereby achieving the optimal design of a multiple screw type dryer for treating inorganic and organic sludge wastes. One notable design feature of the dryer was to bypass a certain of fraction of the hot combustion gases into the bottom of the screw cylinder, by the fluid flow induction, across the delicately designed holes on the screw surface to agitate internally the sticky sludges. This offers many benefits not only in the enhancement of thermal efficiency even for the high viscosity material but also greater flexibility in the application of system design and operation. However, one careful precaution was made in operation in that when distributing the hot flue gas over the lump of sludge for internal agitation not to make any pore blocking and to avoid too much pressure drop caused by inertial resistance across the lump of sludge. The optimal retention time for rotating the screw at 1 rpm in order to treat 200 kg/hr of sewage sludge was determined empirically about 100 minutes. The corresponding optimal heat source was found to be 150,000 kcal/hr. A series of numerical calculation is performed to resolve flow characteristics in order to assist in the system design as function of important system and operational variables. The numerical calculation is successfully evaluated against experimental temperature profile and flow field characteristics. In general, the calculation results are physically reasonable and consistent in parametric study. In further studies, more quantitative data analyses such as pressure drop across the type and loading of drying sludge will be made for the system evaluation in experiment and calculation.

Emergy Evaluation Overview of the Natural Environment and Economy of the Han River basin in Korea (한강유역의 자연환경과 사회경제활동에 대한 에머지 평가 - 한강유역 및 한강하구 관리를 위한 정책제언 -)

  • Kang, Dae-Seok
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.10 no.3
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    • pp.138-147
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    • 2007
  • An emergy concept was used to evaluate the environment and economy of the Han River basin in Korea and to suggest policy perspectives far the sustainable utilization of its environment and associated estuarine ecosystem. The economy of the basin used $5.19{\times}10^{23}\;sej/yr$ of emergy in 2005. The economy of the Han River basin was heavily dependent on outside energy sources from foreign countries and other parts of Korea, with internal sources, renewable and nonrenewable, contributing only 15.6% to the total emergy use. The basin's trade balance in terms of emergy showed trade surplus, whereas there was a deficit in monetary terms. The population of the Han River basin was far greater than the carrying capacity calculated using the emergy flow, with renewable carrying capacity only at 1.8% of the basin's population and developed carrying capacity at 14.3%. The economy of the basin imposed a substantial stress on its environment, with an environmental loading ratio of 54.8. Overall, the economy of the Han River basin was not sustainable with an emergy sustainability of 0.02. These are reflected in lower quality of living expressed in the emergy term than the national average. Deconcentration of population and economic activities is needed to reduce environmental stress on the environment of the basin and its valuable estuarine ecosystem. Policies to restore ecosystem productivity of the basin are also needed to ensure the sustainability of the basin's economic activities and the sustainable utilization of the Han River estuary. In this regard, it is urgently needed for the Korean government to implement sustainable management measures for the Han River estuary, a well-preserved, productive natural estuarine ecosystem in Korea.

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Studies on the Mechanism of Contraction by Substance P in Rabbit Ileum (Substance P에 의한 가토 회장평활근의 수축기전에 대한 연구)

  • Jo, Se-Hun;Jung, Jin-Sup;Lee, Sang-Ho
    • The Korean Journal of Physiology
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    • v.18 no.2
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    • pp.151-162
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    • 1984
  • The mechanism of the contractile response of longitudial muscle of rabbit ileum to substance P (SP) has been investigated. The contractions in rabbit ileum under various conditions were recorded isometrically The following results were obtained. 1) The contractions by SP increased according to concentrations. SP·induced contraction was not sustained but faded rapidly at $10^{-7}M$. The response to the commutative addition of SP was decreased in comparison to the response to separate administration of each concentration . 2) The response to $10^{-8}M$ SP after 5 min application cf $10^{-7}M$ SP was increased with increasing the time interval between the administration of $10^{-7}$ and $10^{-8}M$ SP. 3) The treatment of rabbit ileum by $10^{-7}M$ SP for 5 min didn't decrease the response to $10^{-6}M$ acetylcholine. 4) $10^{-6}M$ atropine had no effect of the contractile response to $10^{-7}M$ SP. The response to $10^{-7}M$ SP was normal or subnormal in the presence of 3 mM tetraethylammonium(TEA). 5) 100k solution, $10^{-4}M$ ouabain, and Na-free solution inhibited the response to $10^{-8}M$ SP and 3 mM TEA completely, and to $10^{-7}M$ SP incompletely. 3 mM TEA induced a considerable contraction in K-free solution, but $10^{-8}M$ SP didn't induce the contraction. $10^{-6}M$ norepinephrine decreased the contractile responses to SP and TEA. 6) The contractile response to $10^{-7}M$ SP was dependent on the extracellular $Ca^{2+}$ concentrations to 1.8 mM. 7) The contractile response to $10^{-7}M$ SP remained 15% of the maximal response after bathing the ileum in a Ca-free solution for 2.5 min. 8) The responsiveness to SP was completely lost within 10 min of bathing in Ca-free solution, but was restored by the exposure to $Ca^{2+}$. The restorative effect of $Ca^{2+}$ depended on the concentration of $Ca^{2+}$, and on time for which the tissue exposed to this $Ca^{2+}$ concentration. These results suggest that there are two mechanisms of the action by which the low concentrations of substance P causes the contraction of intestinal smooth muscle: the reduction of K conductance and a mechanism dependent on the extracellular $Ca^{2+}$, and that high concentration of SP may elicit a contraction by releasing $Ca^{2+}$ from an intracellular store, which is not as sensitive to removal of extracellular $Ca^{2+}$ or as easily accessible to EGTA as the extracellular space of the muscle. The location of this store is not known; it may be associated with the internal side of the cell membrane.

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Self-Regulatory Mode Effects on Emotion and Customer's Response in Failed Services - Focusing on the moderate effect of attribution processing - (고객의 자기조절성향이 서비스 실패에 따른 부정적 감정과 고객반응에 미치는 영향 - 귀인과정에 따른 조정적 역할을 중심으로 -)

  • Sung, Hyung-Suk;Han, Sang-Lin
    • Asia Marketing Journal
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    • v.12 no.2
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    • pp.83-110
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    • 2010
  • Dissatisfied customers may express their dissatisfaction behaviorally. These behavioral responses may impact the firms' profitability. How do we model the impact of self regulatory orientation on emotions and subsequent customer behaviors? Obviously, the positive and negative emotions experienced in these situations will influence the overall degree of satisfaction or dissatisfaction with the service(Zeelenberg and Pieters 1999). Most likely, these specific emotions will also partly determine the subsequent behavior in relation to the service and service provider, such as the likelihood of complaining, the degree to which customers will switch or repurchase, and the extent of word of mouth communication they will engage in(Zeelenberg and Pieters 2004). This study investigates the antecedents, consequences of negative consumption emotion and the moderate effect of attribution processing in an integrated model(self regulatory mode → specific emotions → behavioral responses). We focused on the fact that regret and disappointment have effects on consumer behavior. Especially, There are essentially two approaches in this research: the valence based approach and the specific emotions approach. The authors indicate theoretically and show empirically that it matters to distinguish these approaches in services research. and The present studies examined the influence of two regulatory mode concerns(Locomotion orientation and Assessment orientation) with making comparisons on experiencing post decisional regret and disappointment(Pierro, Kruglanski, and Higgins 2006; Pierro et al. 2008). When contemplating a decision with a negative outcome, it was predicted that high (vs low) locomotion would induce more disappointment than regret, whereas high (vs low) assessment would induce more regret than disappointment. The validity of the measurement scales was also confirmed by evaluations provided by the participating respondents and an independent advisory panel; samples provided recommendations throughout the primary, exploratory phases of the study. The resulting goodness of fit statistics were RMR or RMSEA of 0.05, GFI and AGFI greater than 0.9, and a chi-square with a 175.11. The indicators of the each constructs were very good measures of variables and had high convergent validity as evidenced by the reliability with a more than 0.9. Some items were deleted leaving those that reflected the cognitive dimension of importance rather than the dimension. The indicators were very good measures and had convergent validity as evidenced by the reliability of 0.9. These results for all constructs indicate the measurement fits the sample data well and is adequate for use. The scale for each factor was set by fixing the factor loading to one of its indicator variables and then applying the maximum likelihood estimation method. The results of the analysis showed that directions of the effects in the model are ultimately supported by the theory underpinning the causal linkages of the model. This research proposed 6 hypotheses on 6 latent variables and tested through structural equation modeling. 6 alternative measurements were compared through statistical significance test of the paths of research model and the overall fitting level of structural equation model and the result was successful. Also, Locomotion orientation more positively influences disappointment when internal attribution is high than low and Assessment orientation more positively influences regret when external attribution is high than low. In sum, The results of our studies suggest that assessment and locomotion concerns, both as chronic individual predispositions and as situationally induced states, influence the amount of people's experienced regret and disappointment. These findings contribute to our understanding of regulatory mode, regret, and disappointment. In previous studies of regulatory mode, relatively little attention has been paid to the post actional evaluative phase of self regulation. The present findings indicate that assessment concerns and locomotion concerns are clearly distinct in this phase, with individuals higher in assessment delving more into possible alternatives to past actions and individuals higher in locomotion engaging less in such reflective thought. What this suggests is that, separate from decreasing the amount of counterfactual thinking per se, individuals with locomotion concerns want to move on, to get on with it. Regret is about the past and not the future. Thus, individuals with locomotion concerns are less likely to experience regret. The results supported our predictions. We discuss the implications of these findings for the nature of regret and disappointment from the perspective of their relation to regulatory mode. Also, self regulatory mode and the specific emotions(disappointment and regret) were assessed and their influence on customers' behavioral responses(inaction, word of mouth) was examined, using a sample of 275 customers. It was found that emotions have a direct impact on behavior over and above the effects of negative emotions and customer behavior. Hence, We argue against incorporating emotions such as regret and disappointment into a specific response measure and in favor of a specific emotions approach on self regulation. Implications for services marketing practice and theory are discussed.

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