• Title/Summary/Keyword: state variables equation

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Mediating effect of perceived stigma against epilepsy on quality of life among parents with epileptic child (간질아동 부모의 삶의 질에 대한 지각된 낙인의 매개효과)

  • Kim, Nho Eun;Cho, Sung Min;Kim, Dong Wook
    • Clinical and Experimental Pediatrics
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    • v.52 no.9
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    • pp.1005-1014
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    • 2009
  • Purpose:Epilepsy of child may cause high level of psychosocial difficulties for parents including stigmatization and stress and therefore worsen their quality of life (QOL). The purpose of this study was to evaluate the mediating effect of perceived stigma against epilepsy on QOL among parents with epileptic child. Methods:Two hundred and sixty parents of epileptic child recruited from five separated university hospital child neurology clinics specializing in epilepsy completed a demographic questionnaire, a medical questionnaire, a perceived stigma questionnaire and the Ro's Quality of Life Inventory, a popular tool for evaluating QOL of adults in Korea which is composed of 6 domains and 47 questions. Data was analyzed with SPSS 14.0 program using frequency analysis and descriptive analysis and with AMOS 7.0 program using Structural Equation Model (SEM) analysis. Results:The level of parents' QOL was relatively fair. SEM analysis on the quality of life level of parents showed that all variables (especially having religion, the monthly income, employment state, age of child, the leisure time, the perceived stigma level against epilepsy, and seizure frequency) directly affect the quality of life level of parents and that disease-related variables also affect the quality of life level of parents indirectly through the mediating factor (the perceived stigma), where the indirect effect is large with the existence of combined disabilities. The total effect on the quality of life level of parents is large with the existence of combined disabilities, the perceived stigma level, the leisure time, having religion, and the monthly income. Conclusion:The results of this study indicated that many factors including parents' perceived stigma may affect the quality of life of parents with epileptic children directly, and that some disease-related factors may affect indirectly through a mediating factor, the perceived stigma. Multidisciplinary collaboration would be imperative for their welfare.

A Simulation Study on SCR(Steam Carbon Dioxide Reforming) Process Optimization for Fischer-Tropsch Synthesis (Fischer-Tropsch 합성용 SCR(Steam Carbon Dioxide Reforming) 공정 최적화 연구)

  • Kim, Yong Heon;Koo, Kee Young;Song, In Kyu
    • Korean Chemical Engineering Research
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    • v.47 no.6
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    • pp.700-704
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    • 2009
  • A simulation study on SCR(steam carbon dioxide reforming) in gas-to-liquid(natural gas to Fischer-Tropsch synthetic fuel) process was carried out in order to find optimum reaction conditions for SCR experiment. Optimum operating conditions for SCR process were determined by changing reaction variables such as temperature and $CH_4/steam/CO_2$ feed ratio. Simulation was carried out by Aspen Plus. During the simulation, overall process was assumed to proceed under steady-state conditions. It was also assumed that physical properties of reaction medium were governed by RKS(Redlich-Kwong-Soave) equation. Optimum simulation variables such as temperature and feed ratio were determined by considering $H_2/CO$ ratio for FTS(Fischer-Tropsch synthesis), $CH_4$ conversion, and $CO_2$ conversion. Simulation results showed that optimum reaction temperature and $CH_4/steam/CO_2$ feed ratio in SCR process were $850^{\circ}C$ and 1.0/1.6/0.7, respectively. Under optimum temperature of $850^{\circ}C$, $CH_4$ conversion and $CO_2$ conversion were found to be 99% and 49%, respectively.

A Study on Shape Optimization of Distributed Actuators using Time Domain Finite Element Method (시간유한요소법을 이용한 분포형 구동기의 형상최적화에 관한 연구)

  • Suk, Jin-Young;Kim, You-Dan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.9
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    • pp.56-65
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    • 2005
  • A dynamic analysis method that freezes a time domain by discretization and solves the spatial propagation equation has a unique feature that provides a degree of freedom on spatial domain compared with the space discretization or space-time discretization finite element method. Using this feature, the time finite element analysis can be effectively applied to optimize the spatial characteristics of distributed type actuators. In this research, the time domain finite element method was used to discretize the model. A state variable vector was used in the discretization to include arbitrary initial conditions. A performance index was proposed on spatial domain to consider both potential and vibrational energy, so that the resulting shape of the distributed actuator was optimized for dynamic control of the structure. It is assumed that the structure satisfies the final rest condition using the realizable control scheme although the initial disturbance can affect the system response. Both equations on states and costates were derived based on the selected performance index and structural model. Ricatti matrix differential equations on state and costate variables were derived by the reconfiguration of the sub-matrices and application of time/space boundary conditions, and finally optimal actuator distribution was obtained. Numerical simulation results validated the proposed actuator shape optimization scheme.

Numerical Analysis of Dynamic Response of Floating Offshore Wind Turbine to the Underwater Explosion using the PML Non-reflecting Technique (PML 무반사 기법을 이용한 부유식 해상풍력발전기의 수중폭발에 따른 동응답 수치해석)

  • Cho, Jin-Rae;Jeon, Soo-Hong;Jeong, Weui-Bong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.6
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    • pp.521-527
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    • 2016
  • This paper is concerned with the numerical analysis of dynamic response of floating offshore wind turbine subject to underwater explosion using an effective non-reflecting technique. An infinite sea water domain was truncated into a finite domain, and the non-reflecting technique called the perfectly matched layer(PML) was applied to the boundary of truncated finite domain to absorb the inherent reflection of out-going impact wave at the boundary. The generalized transport equations that govern the inviscid compressible water flow was split into three PML equations by introducing the direction-wise absorption coefficients and state variables. The fluid-structure interaction problem that is composed of the wind turbine and the sea water flow was solved by the iterative coupled Eulerian FVM and Largangian FEM. And, the explosion-induced hydrodynamic pressure was calculated by JWL(Jones-Wilkins-Lee) equation of state. Through the numerical experiment, the hydrodynamic pressure and the structural dynamic response were investigated. It has been confirmed that the case using PML technique provides more reliable numerical results than the case without using PML technique.

Factors Influencing the Preference for German farm Tourism: A Path Model Approach

  • Sidali, Katia Laura;Spiller, A.
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.4
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    • pp.33-59
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    • 2008
  • This paper aims to analyse the preference for German farm tourism among the German population. For this reason, we conducted an empirical study in Germany during summer 2007 and we applieda structural equation model based on partial leasts quares(PLS) to analyse the data. In the following chapters we will introduce the literature review and our conceptual frame work. We will then outline the procedures we adopted and the results of the empirical analysis. In the final part so me conclusions will be presented and a discussion will follow in order to draw the future directions of our research. According to our hypotheses, the possibility that agri-tourism enters in the evoked set of an individual is higher: H1: The higher the information degree about it. H2: The lower the influence of the social stimuli. H3: The higher the physical exposure to it (experience). H4: The higher the wellness image of agri-tourism. H5: The higher the traditional image of agri-tourism. H6: The higher the exciting image of agri-tourism. H7: The higher the perceived value for money. Our further hypotheses affirm that the possibility that agri-tourism enters in the evoked set of an individual is higher: H8: The lower the perceived risk. H9: The higher the motive to enjoy a holiday in the nature. H10: The higher the motive to enjoy a sport holiday. H11: The lower the motive to have an organized holiday. H12: The lower the motive to have a holiday abroad. H13: The lower the motive of action and night life. H14: The higher the motive to spend a holiday with the family. H15: The lower the motive to spend a city holiday. Finally, our model has some socio-demographics data. As we mentioned before, German agri-tourism has traditionally been the travel destination of large-size families, with low-to-middle income. For that reason, our final hypothesises are the following: the possibility that agri-tourism enters in the evoked-set of an individual is higher: H16: The higher the number of family members. H17: The lower the family income. Since in this study we use a path model with a PLS approach, we are able to state some interrelations among the exogenous latent variables: H18: The motive of sport holiday has a positive influence towards nature motives. H19: The physical exposition to agri-tourism has a positive influence toward information. H20: The motive of family holiday has a negative influence toward the motive of action and night life. H21: Social stimuli have a positive influence towards individuals risk perceptions. H22: Social stimuli have negative influence towards experience. Data for this study were gathered via administrated questionnaires during the summer 2007 within the frame of an academic "marketing research" course. The corresponding t-values are assessed using the bootstrapping method with 500 re-samples. In our model 61% of the degree of appreciation of German agri-tourism (evoked set) is explained by five independent variables: value for money ($0.335^{{\ast}{\ast}{\ast}}$) (H7) experience ($0.267^{{\ast}{\ast}}$) (H3), exciting image ($0.204^{\ast}$) (H6) organisation ($-0.162^{\ast}$) (H11) and holiday abroad ($-0.156^{\ast}$) (H12). The variance explained ($R^2$) for the other endogenous variables are the following: nature 24.3%, information 14.1%, action holiday 13.8%, risk perception 5.8% and experience 2.4%. An overview can be inferred from table 5. The results also allow us to test each of the proposed hypotheses. With exception of organization and abroad, none of the others travel style factors (H9 to H15) seem to have any significant impact towards evoked set which leads to the rejection of the respective hypotheses. As expected, social stimuli have a significant influence on individuals' risk perception (H21 accepted), however neither the former nor the latter have a valuable impact on evoked set (rejection of H2 and H8). Besides, since the influence of social stimuli towards experience is not significant, also H22 has to be rejected. Experience influences information (H19 accepted) but the latter does not affect significantly the evoked set (H1 rejected). Both H4 as well as H5, referring respectively to the perceived images of German agri-tourism as a wellness destination and the traditional image of the German farm tourism have to be rejected. Finally, none of the demographic data included in the model explains significantly the variance of the factor evoked set. Therefore neither H16 nor H17 has been accepted. As far as the interrelation between sport and nature (H18) and family and action (H20) are concerned, the stated relationship among these variables has been statistically confirmed. Our path model based on partial least squares shows the factors influencing the preference for farm tourism in Germany. Among others value for money and experience are the most significant ones. Practical implications are discussed.

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The Effect of Benevolence and Communication on Commitment and Switching Intentions : The Automobile Parts Buyer's Perspective (자동차 부품 제조업체와 공급업체 간의 선의와 의사소통이 몰입과 교체의도에 미치는 영향: 구매자의 관점을 중심으로)

  • Kim, Hong-Keun;Lee, Phil-Soo;Kim, Min-Seong;Lee, Yong-Ki
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.9 no.6
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    • pp.129-144
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    • 2014
  • This study is to examine the effect of mutualistic benevolence, altruistic benevolence, and communication on affective commitment, calculative commitment, and switching intentions and investigate how two commitment dimensions play mediating roles between two benevolence constructs and communication, and switching intentions. For these purposes the author developed a structural model which consists of several constructs. In this model, benevolence factor that consists of mutualistic benevolence and altruistic benevolence, and communication were proposed to affect two commitment constructs and result in, increase switching intentions. Thus, two commitment constructs(e.g., affective and calculative commitment) were proposed as core mediating variables between mutualistic benevolence, altruistic benevolence, and communication, and switching intentions. The data were collected from 210 automobile parts buyers and were analyzed using frequency, reliability, and confirmatory factor analysis and SEM (structural equation model) with SPSS/WIN 20.0 and AMOS 20.0. The data were analyzed with structural equation modeling with AMOS 20.0 and SPSS Win/PC 20.0. The result of the overall model analysis appeared as follows: ${\chi}2=224.885$, d.f=123(${\chi}2/df=1.828$), p=0.000, GFI=.898, AGFI=.859, IFI=.967, NFI=.930, TLI=.958, RMSEA=.063, CFI=.966. Since the result of the overall model analysis demonstrated a good fit, we could further analyze our data. The findings can be summarized as follows: According to structural equation modeling analysis, firstly, mutualistic benevolence has direct effects on calculate commitment and affective commitment. Secondly, altruistic benevolence has a positively direct effect on calculate commitment. Thirdly, communication has a statistically direct effect on affective commitment. Fourthly, calculative commitment has direct effects on affective commitment and switching intentions. Lastly, affective commitment has a direct effect on switching intentions.

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Golfers' Intention to Adopt UV Specialized Clothing as Innovation: Based on Rogers Theory (골퍼의 자외선 차단의복의 수용 의도: Rogers의 혁신확산이론을 중심으로)

  • Sung Heewon;Slocum Ann C.
    • Journal of the Korean Society of Clothing and Textiles
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    • v.28 no.12 s.138
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    • pp.1554-1561
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    • 2004
  • In the U.S., outdoor enthusiasts such as golfers have been focused on skin cancer prevention practices since their outdoor activities lead to extensive sun exposure during peak sun hours. The purposes of this study were to investigate golfers current sun protection behaviors and five attributes and their impacts on the intention to adopt UV specialized clothing based on Rogers' theory. UV specialized clothing as a preventive innovation is related to sun protection behaviors. However, there has been little effort to explain the intention to adopt a preventive innovation regarding health-related practices. With a convenience sampling method, a total of 158 useful questionnaires were collected. Ninety one percent were male golfers, and their age ranged from 16 to 80 years old(mean age=30 years). About $25\%$ reported to practice sun protection behaviors. About $70\%$ disagreed on the relative advantage, compatibility, observability, and triability of UV specialized shirts and reported the low intention to purchase it. Current sun protection behaviors and five attribute variables were entered in the multiple regression equation to explain the dependent variable of intention to adopt the innovation. Triability was the best predictor of the intention to adopt UV specialized shirts, followed by current sun protection behaviors, compatibility, and relative advantage. With four predictors, $45\%$ of the variance of intention to adopt was explained. The present study provides how the golfers current sun protection behaviors play important roles in explaining the intention to adopt the preventive innovation. Physical and functional features of UV specialized clothing were also significantly associated with their intentions to adopt it.