• 한국전자통신학회논문지
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• 제8권9호
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• pp.1325-1332
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• 2013

비디오 코딩에서 GOP의 첫 번째 프레임인 I 프레임은 많은 비트를 발생시키는 인트라 모드로 압축되고 다음 프레임의 인터 모드 압축에 사용되기 때문에 I 프레임을 위한 초기 QP 값은 I 프레임뿐만 아니라 이후 프레임에도 영향을 주게 된다. 이전 연구에서 정확한 초기 QP 계산을 위해 I 프레임의 압축 후 비트량을 분석하였고, GOP의 PSNR을 최대로 하는 I 프레임의 비트량이 GOP에 상관없이 일정한 값을 가짐을 보였다. 본 논문에서는 기존 방법을 이용하여 최적의 I 프레임 비트량을 계산한 후 이 값을 이용하여 초기 QP를 계산할 수 있는 R-Q 모델을 제안한다. 제안하는 모델은 간단하면서도 적응적으로 모델 파라미터를 수정하기 때문에 실시간 응용에 적합하다. 실험 결과는 제안하는 모델이 초기 QP 계산에 필요한 트래픽 특성을 잘 반영하고 있으며 또한 실시간으로 모델 파라미터를 구하는 방법도 효과적으로 작동함을 보여준다.

• Structural Engineering and Mechanics
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• 제71권5호
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• pp.553-562
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• 2019

This paper presents the results of a study into the dynamic behaviour of a support structure of a mobile elevating work platform. The vibrations of the mechanical system of the observed structure are examined analytically, numerically, and experimentally. Within the analytical examination, a simple mathematical model is developed to describe free and forced vibrations. The dynamic analysis of the mechanical system is conducted using a discrete dynamic model with a reduced number of vibrational degrees of freedom. On the basis of the expression for the system energy, and by applying Lagrange's equations of the second kind, differential equations are derived for system vibrations, frequencies are determined, and the laws of forced platform vibration are established. At the same time, a nonlinear FEM model is developed and the laws of free and forced vibration are determined. The experimental and numerical part of the study deal with the examination of the real structure in extreme conditions, taking into account: the lowest eigenfrequency, forced actions that could endanger the general stability, the maximal amplitudes, and the acceleration of the work platform. The obtained analytical and numerical results are compared with the experiments. The experimental verification points to the adverse behaviour of the platform in excitation cases - swaying. In such a situation, even a relatively small physical force can lead to unacceptably high amplitudes of displacement and acceleration - exceeding the usual work values.

• Smart Structures and Systems
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• 제8권2호
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• pp.205-217
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• 2011

This article describes the research work involving the implementation of an Active Bracing System aimed at the modification of the initial dynamics of a laboratorial building structure to a new desired dynamics. By means of an adequate control force it is possible to assign an entirely new dynamics to a system by moving its natural frequencies and damping ratios to different values with the purpose of achieving a better overall structural response to external loads. In Civil Engineering applications, the most common procedures for controlling vibrations in structures include changing natural frequencies in order to avoid resonance phenomena and increasing the damping ratios of the critical vibration modes. In this study, the actual implementation of an active system is demonstrated, which is able to perform such modifications in a wide frequency range; to this end, a plane frame physical model with 4 degrees-of-freedom is used. The Active Bracing System developed is actuated by a linear motor controlled by an algorithm based on pole assignment strategy. The efficiency of this control system is verified experimentally by analyzing the control effect obtained with the modification of the initial dynamic parameters of the plane frame and observing the subsequent structural response.

• 웰빙융합연구
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• 제2권1호
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• pp.35-39
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• 2019

This paper presents two social and academic studies on the boundary between cultural production and consumption. The first line of the study on cultural omnivore analyzes the choice of heterogeneous audiences in the face of various cultural offerings. The second line is a study of market categories, which analyzes the responses of peer audiences to objects with different levels of category code compliance. As such, this paper developed a heterogeneous audience model to evaluate objects of different types. This allows us to consider two dimensions of cultural preference: diversity and orientation of selection. To this end, this paper proposes a new analytical frame work to map consumption behavior on these two dimensions. The results suggest that one type of target that values diversity and transformation is particularly resistant to those that span boundaries. We test this argument in the analysis of two large data sets on film and restaurant reviews. Overall, our findings can extend beyond cultural consumption. Outline variability of contextual individuals or individuals in the same situation can cross cultural boundaries even if they are not intentionally pursuing such hybridism.

• 대한치과의사협회지
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• 제22권7호통권182호
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• pp.621-633
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• 1984

Kinesiograph로부터 얻어지는 자료의 선형범위를 확장하고자 하는 연구가 비철, 비자석성의 기구를 사용하여 수행되었다. 자석을 5mm의 일정한 간격으로 자석감지장치가 달린 구조물에 팽팽하게 세평면(frontal, horizontal, sogittal plam)을 통해 3cm×4cm×5cm의 입체공간내에서 693개의 움직여서 만들어지는 자료점으로 항렬 (matrix)을 얻었다. 각각의 자료점에 있어서 Kinesiograph로부터 얻어진 관찰된 값과 움직인 실제값이 상관지어졌다. 따라서 관찰된 값의 세 상관계수를 알게되면 실제값인 세 계수를 얻을수 있게 됐다. 이 업무를 수행하기 위해서 컴퓨터 프로그램이 Fortran을 이용해서 특별히 쓰여졌다. 각 자료점이 5mm 서로 떨어져 있으므로 연구된 입체공간에는 각각 8개의 자료점을 가진 480개의 입방체가 존재한다. 따라서 각각 자료점간에 더 작은 간극을 마련할 수 있다면 보다 더 정밀한 계측이 가능 할 것이다. 결론으로 컴퓨터의 도움으로 기능적 하악운동의 전체범위에 걸친 절대계측들 가능케 하는 이론적 모형이 제시되었다.

• Steel and Composite Structures
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• 제29권4호
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• pp.483-491
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• 2018

Timoshenko beam model is widely exploited in the literature to examine the mechanical behavior of stubby beam-like components. Timoshenko beam theory is well-known to require the shear correction factor in order to recognize the nonuniform shear distribution at a section. While a variety of shear correction factors are appeared in the literature so far, there is still no consensus on the most appropriate form of the shear correction factor. The Saint-Venant's flexure problem is first revisited in the frame work of the classical theory of elasticity and a highly accurate approximate closed-form solution is presented employing the extended Kantorovich method. The resulted approximate solution for the elasticity field is then employed to introduce two shear correction factors consistent with the Cowper's and energy approaches. The mathematical form of the proposed shear correction factors are then simplified and compared with the results available in the literature over an extended range of Poisson's and aspect ratios. The proposed shear correction factors do not exhibit implausible issue of negative values and do not result in numerical instabilities too. Based on the comprehensive discussion on the shear correction factors, a piecewise definition of shear correction factor is introduced for rectangular cross-sections having excellent agreement with the numerical results in the literature for both shallow and deep cross-sections.

• 컴퓨터교육학회논문지
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• 제18권1호
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• pp.13-20
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• 2015

현재 컴퓨터공학 교육에 참여하고 있는 여학생들의 전공과 일에 대한 가치관을 조사하고 전공 만족도와 유지율을 증진시킬 수 있는 교육 및 평가 과정 개발을 위한 새로운 방안이 필요한 시점이다. 우리 사회에서 컴퓨터공학 기술 분야의 젠더 다양성을 높이고 여성과 컴퓨터공학 기술 분야의 새로운 관계를 모색하는 데 기여하기 위하여 컴퓨터공학 전공 학생들을 대상으로 정량적 및 정성적 조사를 실시한 결과 여학생의 경우 컴퓨터공학 교육 과정을 접하면서 흥미가 감소되고 멘토가 부족하며 자아 존중감이 저하되는 현상이 나타났고 전공과 직업 선택의 연계 과정이 불일치할 수 있어 여성의 이공계 탈출 현상을 초래할 수 있음이 드러났다. 연구 결과 컴퓨터공학 전공 여학생에게 적합한 ICT교육 방법은 지역적, 역사적, 사회적 맥락에 맞게 재설계되어야 하며 컴퓨터공학 전공 여학생들이 갖고 있는 불안감이나 약한 조직 소속감에서 드러나는 특성을 우선적으로 분석하고 이에 맞는 교수법을 제안해야 할 것으로 보인다.

• 마케팅과학연구
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• 제18권4호
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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.