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        검색결과 811

        601.
        2020.11 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This empirical research aims to modeling and improving the forecasting accuracy of the volatility pattern by employing the Saudi Arabia stock market (Tadawul)by studying daily closed price index data from October 2011 to December 2019 with a number of observations being 2048. In order to achieve significant results, this study employs many mathematical functions which are non-linear spectral model Maximum overlapping Discrete Wavelet Transform (MODWT) based on the best localized function (Bl14), autoregressive integrated moving average (ARIMA) model and generalized autoregressive conditional heteroskedasticity (GARCH) models. Therefore, the major findings of this study show that all the previous events during the mentioned period of time will be explained and a new forecasting model will be suggested by combining the best MODWT function (Bl14 function) and the fitted GARCH model. Therefore, the results show that the ability of MODWT in decomposition the stock market data, highlighting the significant events which have the most highly volatile data and improving the forecasting accuracy will be showed based on some mathematical criteria such as Mean Absolute Percentage Error (MAPE), Mean Absolute Scaled Error (MASE), Root Means Squared Error (RMSE), Akaike information criterion. These results will be implemented using MATLAB software and R- software.
        602.
        2020.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The study investigates developing an Islamic student financing securitization model based on sukuk structures. This study employs sample of descriptive, analytical, and comparative analyses utilized to discuss a novel framework of Islamic securitization through the different structures of sukuk wakalah derived from asset securitization. The result served to investigate the use of Islamic student financing securitization in a Shariah-compliant manner, which would be implementable in Malaysia. It emphasized the sukuk structures based on the wakeel principle, which indicated a situation where a wakeel or representative appointment was made to manage a project on the behalf of the sukuk holder. The findings of this study supported the economic benefits obtained in the form of lower overall financing costs through the use of securitization for student financing in higher education. This paper offers important implications specifically for the creation of sukuk structures and issuing a highly graded and marketable sukuk, which are compliant towards global Shariah principles. The paper fills the gap perceived within the existing literature of Islamic finance by showing Islamic securitization via sukuk as a viable source of funds potential utilizable in stabilizing the securities market. It can also pose as a solution for securing a sustainable funding.
        603.
        2020.10 KCI 등재 서비스 종료(열람 제한)
        This study aims to analyze the causality of placeness cognition which includes the place satisfaction, place attachment, place function, and behavioral intention of those who visit Suseong amusement park. A questionnaire survey was administered to 255 individuals who visited in Suseong amusement park. To conduct the analysis, six hypotheses were formulated and tested. While two hypotheses were statistically rejected, four hypotheses were accepted. First, place satisfaction was found to have a positive effect on place function (β=.577, p<0.001). Second, place attachment had a positive effect on behavioral intention (β=.450, p<0.001). Third, place function had a positive effect on behavioral intention (β=.247, p<0.05). Fourth, place function was found to have a positive effect on place attachment (β=.637, p<0.001). Unlike most existing research which has indicated that place satisfaction has a direct effect on behavioral intention this study suggests a that double mediating effect through place function and place attachment between place satisfaction and behavioral intention. In addition to increasing satisfaction through the environment of the Suseong Amusement Park, it is also necessary to improve the function of the place to ensure repeated visits from visitors.
        604.
        2019.12 KCI 등재 서비스 종료(열람 제한)
        This paper presents the kinematic modeling of the human forearm rotation constructed with a spatial four-bar linkage. Especially, a circumduction of the distal ulna is modeled for a minimal displacement of the position of the hand during the forearm rotation from the supination to the pronation. To establish its model, four joint types of the four-bar linkage are, firstly, assigned with the reasonable grounds, and then the spatial linkage having the URUU (Universal-Revolute-Universal-Universal) joint type is proposed. Kinematic analysis is conducted to show the behavior of the distal radio-ulna as well as to evaluate the angular displacements of all the joints. From the simulation result, it is, finally, revealed that the URUU spatial linkage can be substituted for the URUR (Universal-Revolute-Universal-Revolute) spatial linkage by a kinematic constraint.
        605.
        2019.09 KCI 등재 서비스 종료(열람 제한)
        This paper presents a rope modeling and verification for the robotic platform of the wall cleaning robot (ROPE RIDE). ROPE RIDE has the characteristics of climbing up and down using a rope fixed on the roof like traditional workers. In order to perform a stable operation with a wall cleaning robot, it is necessary to estimate the position of the robot in a vertical direction. However, due to the high coefficient of extension and nonlinearity of the climbing rope, it is difficult to predict the behavior of the rope. Thus, in this paper, the mathematical modeling of the rope was carried out through the preliminary experiment. Extensive experiments using different types of rope were used to determine the parameters of the constitutive equation of climbing ropes. The validity of the determined parameters of various ropes was verified through the experiment results.
        606.
        2019.08 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The paper aims to measure stock price volatility on Ho Chi Minh stock exchange (HSX). We apply symmetric models (GARCH, GARCH-M) and asymmetry (EGARCH and TGARCH) to measure stock price volatility on HSX. We used time series data including the daily closed price of VN-Index during 1/03/2001–1/03/2019 with 4375 observations. The results show that GARCH (1,1) and EGARCH (1,1) models are the most suitable models to measure both symmetry and asymmetry volatility level of VN-Index. The study also provides evidence for the existence of asymmetric effects (leverage) through the parameters of TGARCH model (1,1), showing that positive shocks have a significant effect on the conditional variance (volatility). This result implies that the volatility of stock returns has a big impact on future market movements under the impact of shocks, while asymmetric volatility increase market risk, thus increase the attractiveness of the stock market. The research results are useful reference information to help investors in forecasting the expected profit rate of the HSX, and also the risks along with market fluctuations in order to take appropriate adjust to the portfolios. From this study’s results, we can see risk prediction models such as GARCH can be better used in risk forecasting especially.
        607.
        2019.06 KCI 등재 서비스 종료(열람 제한)
        Though the importance of spectral characteristics of Korean vowels in the hVd syllable has been recognized in the literature, it has never been studied whether static spectral measurements at a (steady-state) central section are enough to characterize Korean vowels in spontaneous speech, or dynamic spectral measurements across the temporal dimension can better characterize vowels. Despite ample reported evidence of the perceptual influence of non-spectral cues on spectral properties of vowels in the literature, no reports have yet been released on the difference in the degree of the perceptual influence of non-spectral cues (e.g., place and manner of the preceding or following phones, F0, speaking rate, prosody, and gender) on spectral properties of vowels. Through Neural Network pattern recognition modeling in a supervised mode, it was found that dynamic spectral models with non-spectral cues better explain vowel perception than static spectral models and furthermore, flanking phone identities, and manner and place of flanking phones are perceptually the most influential while duration, F0 and speaking rate are perceptually far less contributive than argued in the literature.
        608.
        2019.05 KCI 등재 서비스 종료(열람 제한)
        Purpose - This study provides appropriate procedures for EFA to help researchers conduct empirical studies by using PLS-SEM. Research design, data, and methodology - This study addresses the absolute and relative sample size criteria, sampling adequacy, factor extraction models, factor rotation methods, the criterion for the number of factors to retain, interpretation of results, and reporting information. Results - The factor analysis procedure for PLS-SEM consists of the following five stages. First, it is important to look at whether both the Bartlett test of sphericity and the KMO MSA meet the qualitative criteria. Second, PAF is a better choice of methodology. Third, an oblique technique is a suitable method for PLS-SEM. Fourth, a combined approach is strongly recommended to factor retention. PA should be used at the onset. Next, it is recommended using the K1 criterion. In addition, it is necessary to extract factors that increase the total variance explanatory power through the PVA-FS. Finally, it is appropriate to select an item with a factor loading into 0.5 or higher and a communality of 0.5. Conclusions - It is expected that the accurate factor analysis processed for PLS-SEM as previously presented will help us extract more precise factors of the structural model.
        609.
        2019.04 KCI 등재 서비스 종료(열람 제한)
        흉부 CT스캔에서 공기, 지방, 근육, Background의 HU, 잡음 그리고 신호 대 잡음비의 변화를 측정해 영상 화질에 미치는 지멘스 ADMIRE(Advanced Modeled Iterative Reconstruction)의 영향을 조사했다. 실험 결과에 따르면 ADMIRE Strength가 커질수록 잡음은 감소하고 신호는 증가하여, 결론적으로 신호 대 잡음비는 증가하는 것으로 나타났다. ADMIRE는 기존 영상 재구성 알고리즘인 FBP와 비교하여 잡음을 28~61%까 지 줄일 수 있으며, 신호 대 잡음비는 16~100%까지 향상시킨다.
        610.
        2019.04 서비스 종료(열람 제한)
        Bridge maintenance should be performed on the basis of the shape and specifications data of the bridge in operation, but the paper and computerized drawings of 2D and 3D models are used in the field. Therefore, it is very difficult if not impossible to modify the specifications that change with the inspection cycle. Recently, advanced optical technology have enabled the acquisition of 3D digital data (LiDAR) scanned actual structure, overcoming the limitations that may arise from the maintenance of existing drawing bases. This paper will introduce bridge that utilizes digital pseudo-reality(DPR)based bridge maintenance system using 3D digital data obtained by scanning a bridge currently in operation.
        611.
        2019.03 KCI 등재 서비스 종료(열람 제한)
        Traditionally the steady-state central section of the vowel length has been assumed to characterize the vowel quality. However, since Peterson and Barney (1952), this position has been challenged especially for American English monophthongal vowels. In this paper, introduced are low-ordered 12 mel-scale frequency cepstral coefficients (MFCC), which can characterize the shape of the oral cavity filter for monophthongal vowel production in the mel-scale domain. Four pattern recognition classification models are fitted to the measurements of spectral and cepstral parameters at multiple sections of the vowel duration along with F0, Gender and Duration for the AE vowel signals in the hVd syllable in Hillenbrand et al. (1995). It turns out that pattern recognition classifiers with the cepstral properties outperform those with spectral properties, reaching the perception level of American English listeners’.
        612.
        2018.11 KCI 등재 서비스 종료(열람 제한)
        교량 구조물 거동의 건전성 평가는 하중재하-처짐의 정적특성과 충격계수와 고유진동수 등의 동적특성으로 평가하는 것이 일반적이며, 이를 수치해석적 방법으로 비교 분석하는 것이 합리적인 방법이라 할 수 있다. 사용하중에 대한 거동은 탄성영역에서 이루어지므로 실물 구조체와 수치해석의 결과는 일체성을 보이지만, 동적특성의 경우 특히, 진동학적 분석에 있어서는 구조물의 기하형상과 사용재료의 이질성 에 기인하여 실물 구조체의 결과와 다소 차이를 보인다. 이러한 오차를 수렴시키기 위하여 본 연구는 실물 모형체의 실험결과를 바탕으로 다양한 수치해석적 모델을 제시하고 그 예민도를 분석함으로써, 교량 구조물 평가를 위한 실용적인 모델링 기법을 도출하여 안정적인 예비 해석 결과를 제공하는데 그 목적이 있다. 프리스트레스트 콘크리트 구조물의 긴장재를 환산단면으로 치환한 모델을 기반으로 긴장재의 탄성적 특성을 반영한 모델과 수정된 탄성계수를 적용한 모델의 고유진동수가 실물 모형체의 그것과 가장 유사한 결과를 얻을 수 있었다.
        613.
        2018.08 KCI 등재 서비스 종료(열람 제한)
        In this study, to investigate an optimal configuration method for the modeling system, we performed an optimization experiment by controlling the types of compilers and libraries, and the number of CPU cores because it was important to provide reliable model data very quickly for the national air quality forecast. We were made up the optimization experiment of twelve according to compilers (PGI and Intel), MPIs (mvapich-2.0, mvapich-2.2, and mpich-3.2) and NetCDF (NetCDF-3.6.3 and NetCDF-4.1.3) and performed wall clock time measurement for the WRF and CMAQ models based on the built computing resources. In the result of the experiment according to the compiler and library type, the performance of the WRF (30 min 30 s) and CMAQ (47 min 22 s) was best when the combination of Intel complier, mavapich-2.0, and NetCDF-3.6.3 was applied. Additionally, in a result of optimization by the number of CPU cores, the WRF model was best performed with 140 cores (five calculation servers), and the CMAQ model with 120 cores ( five calculation servers). While the WRF model demonstrated obvious differences depending on the number of CPU cores rather than the types of compilers and libraries, CMAQ model demonstrated the biggest differences on the combination of compilers and libraries.
        614.
        2018.04 KCI 등재 서비스 종료(열람 제한)
        다문화교육이 정책적으로 강조되면서 교사의 다문화교육 역량을 어떻게 신장시킬 것인가에 대한 논의가 지속적으로 이어지고 있다. 관련 논의 중 본 연구는 교사들이 다문화가정 학생을 어려움 없이 지도할 수 있다고 생각하는 긍정적 인식에 영향을 미치는 요인들이 무엇인지 교사효능감의 이론 틀을 적용하여 분석하였다. 특히 교사효능감을 형성하는 주요 요인 중 교사의 성취 및 대리 경험, 학교 환경 등을 고려하여 다문화가정 학생 지도에 대한 교사의 긍정적 인식이 어떤 요인들에 의해 제고될 수 있는지 살펴보고자 했다. 이러한 문제의식을 바탕으로 2016 다문화사회 관련 의식 조사 중 교사 데이터를 활용하여 179개교의 3,970명의 교사를 대상으로 다층모형을 통해 분석을 시행하였다. 그 결과, 교사의 성취 경험이라고 할 수 있는 다문화가정 학생 담임 경험은 정적인 효과가 있었지만 다문화교육 관련 강의 수강이나 현직연수 프로그램 이수는 유의미한 효과가 나타나지 않았다. 교사의 대리 경험으로서 가정한 동료 교사들의 다문화사회에 대한 긍정적 인식 수준은 정적인 효과가 있었으며 학교 간 효과의 차이가 존재함을 확인하였다. 한편 학교의 다문화교육 관련 정책 수행과 학교 문화는 유의미한 효과가 나타나지 않았다. 이러한 결과를 바탕으로 다문 화 관련 교사교육과 학교 정책에 대한 시사점을 도출하였다.
        615.
        2018.04 서비스 종료(열람 제한)
        In this study, we propose a structural modeling method to analyze the seismic behavior characteristics of arched stone bridge. For this purpose, we select the representative model of arched stone bridge, and various arch types are set in consideration of the width and height. Accordingly, this study applies the discrete element method for the modelling of discontinuum structure to analyze the seismic behavior characteristics according to the various arched types.
        616.
        2018.01 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 다중 기후모델에 의한 미래 기후자료를 기반으로 SWAT-K 유역모형을 적용하여, 제주도 지역의 미래 기후변화에 따른 수자원 영향을 평가하였다. 기후모델에 따른 미래 전망자료의 불확실성을 고려하여 9개의 GCM 모델의 기후자료를 미래기간(2010~2099년)에 대한 SWAT-K 모형의 기상자료로 적용하였다. 과거(1992~2013년) 및 미래기간에 대한 연도별 수문변화를 분석한 결과 강수량, 유출량, 증발산량, 함양량 모두 증가하는 추세로 나타났다. 과거기간에 비해 유출량의 변화가 가장 크게 나타났으며(최대 50% 증가), 증발산량은 상대적으로 작게 나타났다(최대 11% 증가). 월별로는 8월과 9월의 강수량 증가에 따라 유출량과 함양량도 크게 증가하는 반면, 동일기간에 대한 증발산량은 감소하는 것으로 분석되었다. 1월과 12월은 반대의 경향이 나타났다. 미래의 물수지 변화를 분석한 결과 강수량 대비 유출량, 증발산량, 함양량의 비율은 변화가 크지 않으나, 과거와 비교했을 때 RCP 8.5 시나리오에서 유출량 비율은 최대 4.3% 증가하는 반면, 증발산량 비율은 최대 3.5% 감소하는 것으로 나타났다. 기존의 타 연구와 본 연구에서 도출한 결과를 종합해 볼 때, 현재 제시되고 있는 기후변화 시나리오 가정 하에서는 미래로 갈수록 점차 강수량과 유출량이 증가할 것이고 특히 여름철 강수량 및 유출량의 증가가 예상된다. 이로 인해 제주도 지역의 함양량도 함께 증가할 것으로 판단할 수 있다. 다만, 본 연구는 장기적인 측면에서 자연적인 기후변화로 인한 영향을 분석한 것이며, 추가적으로 단기적인 수재해 대응을 위한 홍수와 가뭄관리, 인위적인 용수수급 관리 등에 대한 종합적인 분석을 통해 제주도 수자원의 지속가능한 이용을 위한 대응방안이 필요하다고 판단된다.
        617.
        2017.11 KCI 등재 서비스 종료(열람 제한)
        In order to increase the therapeutic effect of radiation, there has been an increase in the use of conventional photon therapy. The intensive care unit should pay more attention to the radiation safety evaluation due to the higher energy and the larger facility compared to the existing Photon treatment. These radiation safety evaluations are mainly performed by using Monte Carlo simulation, and the first thing to be done is geometric modeling. The Heavy-ion treatment facility uses synchrotron as the accelerating device, which is difficult to precisely model geometrically and is mostly modeled briefly. This study investigated the effect of simplification and precise implementation of Dipole magnet among the components of synchrotron acceleration device on the radiation safety evaluation. The results show that the simplified geometric model is overestimated with the precisely implemented geometric model. Therefore, it is considered that the radiological safety evaluation results in more reliable results of the precise geometric modeling.
        618.
        2017.10 KCI 등재 서비스 종료(열람 제한)
        Solid waste management is currently a topic of concern, particularly in the protection of humans and the environment from toxic pollutants and hazardous materials. The importance of solid waste management is recognized at international, national, and community levels. Different agendas have been prioritized and assigned to improve quality of life, productivity, and health, and reduce the burden of pollution. Suitable management of solid waste requires appropriate technology that is affordable, socially accepted, and environmentally friendly. The use of a smart management system involving system dynamics can save energy, money, and labor. System dynamics is a computer-based approach that aids in predicting the behavioral patterns of variables, and correlating dependent and independent variables. The inclusion of system dynamics-based models in solid waste management has recently become more common. In this review, we used system dynamics to determine methods to disentangle solid waste management systems and analyzed different studies on solid waste management using system dynamics in different countries in detail. We also discussed the various software packages that are available for system dynamics and their usefulness for waste management. This review may help in understanding current solid waste management practices using system dynamics.
        619.
        2017.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This study was conducted to develop a predictive model for the growth of Escherichia coli strain RC-4-D isolated from red kohlrabi sprout seeds. We collected E. coli kinetic growth data during red kohlrabi seed sprouting under isothermal conditions (10, 15, 20, 25, and 30°C). Baranyi model was used as a primary order model for growth data. The maximum growth rate (μmax) and lag-phase duration (LPD) for each temperature (except for 10°C LPD) were determined. Three kinds of secondary models (suboptimal Ratkowsky square-root, Huang model, and Arrhenius-type model) were compared to elucidate the influence of temperature on E. coli growth rate. The model performance measures for three secondary models showed that the suboptimal Huang square-root model was more suitable in the accuracy (1.223) and the suboptimal Ratkowsky square-root model was less in the bias (0.999), respectively. Among three secondary order model used in this study, the suboptimal Ratkowsky square-root model showed best fit for the secondary model for describing the effect of temperature. This model can be utilized to predict E. coli behavior in red kohlrabi sprout production and to conduct microbial risk assessments.