• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.439-445
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• 2006

Analysis problems of tunnels whose geometrical dimensions are very small compared with surrounding media can be treated as infinite region problems. In such cases, even if finite element models can be applied, excessive number of elements is required to obtain satisfactory accuracy. However, inaccurate results may be produced due to assumed artificial boundary conditions. To solve these problems, a hybrid model, which models the region of interest with finite elements and the surrounding infinite media with infinite elements, is introduced for the analysis of infinite region. Three-dimensional isoparametric infinite elements with various decay characteristics are formulated in this paper and the corresponding parameters are presented by means of parametric studies. Three-dimensional tunnel analysis performed on a representative example verifies the applicability of hybrid model using infinite elements.

• 한국벤처창업학회:학술대회논문집
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• 2023.11a
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• pp.97-100
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• 2023

스타트업은 우리 경제의 성장 동력으로 자리매김하고 있으며, 다양한 분야에서 스타트업이 탄생해 일부는 스케일업(scale-up)하여 유니콘 기업으로 발전하는 반면 일부는 데스밸리(Death Valley)를 넘지 못하고 실패한다. 스타트업이 창업 이후 성공적인 사업화를 통해 지속적인 성장을 이룰 수 있도록 공공과 민간부문에서 다양한 노력을 펼쳐 나가고 있으며, 창업자 보육에 필요한 서비스를 종합적으로 제공하는 액셀러레이터가 스타트업 육성 모델로 주목받고 있다. 액셀러레이터에 대한 관심이 증가하는 것에 비례하여 액셀러레이팅 프로그램의 효과에 대한 연구도 최근 활발하게 이루어지고 있으며, 많은 연구에서 액셀러레이팅이 기업성과에 미치는 긍정적인 효과가 검증되고 있다. 액셀러레이팅 프로그램의 운용 주체와 내용이 다양하여 프로그램 효과 분석도 다각적인 시각에서 이루어질 필요가 있으며, 본 연구에서는 동일한 프로그램에 참여하였음에도 불구하고 기업성과에 차이가 발생하는 것이 참여자의 특성에 기인하는지를 분석하고자 한다. 이를 위해 액셀러레이팅 프로그램에 참여하는 스타트업 CEO의 특성에 초점을 맞춘 연구모형을 설정하였다. 액셀러레이팅 프로그램에 대한 만족도를 독립변수로, 기업성과인 재무적성과와 비재무적성과를 종속변수로 설정하고, 자기효능감, 낙관주의, 희망, 회복탄력성인 긍정심리자본을 매개변수로 설정하여 CEO의 긍정심리자본 정도에 따라 액셀러레이팅 프로그램의 효과에 차이가 있는지 실증적 분석을 통해 검증하고자 한다. 연구 대상은 중소기업 지원 정책금융기관인 신용보증기금과 중소기업은행의 액셀러레이팅 프로그램인 스타트업 네스트(Start-up NEST)와 IBK창공에 참여한 경험이 있는 스타트업 CEO를 대상으로 하였다.

• Journal of KSNVE
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• v.8 no.5
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• pp.964-973
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• 1998

In this paper we propose a levitation and imbalance compensation controller design methodology of magnetic bearing system. In order to achieve levitation and elimination of unbalance vibartion in some operation speed we use the discrete-time Q-parameterization control. When rotor speed p = 0 there are no rotor unbalance, with frequency equals to the rotational speed. So in order to make levitatiom we choose the Q-parameterization controller free parameter Q such that the controller has poles on the unit circle at z = 1. However, when rotor speed p $\neq$ 0 there exist sinusoidal disturbance forces, with frequency equals to the rotational speed. So in order to achieve asymptotic rejection of these disturbance forces, the Q-parameterization controller free parameter Q is chosen such that the controller has poles on the unit circle at z = $exp^{ipTs}$ for a certain speed of rotation p ( $T_s$ is the sampling period). First, we introduce the experimental setup employed in this research. Second, we give a mathematical model for the magnetic bearing in difference equation form. Third, we explain the proposed discrete-time Q-parameterization controller design methodology. The controller free parameter Q is assumed to be a proper stable transfer function. Fourth, we show that the controller free parameter which satisfies the design objectives can be obtained by simply solving a set of linear equations rather than solving a complicated optimization problem. Finally, several simulation and experimental results are obtained to evaluate the proposed controller. The results obtained show the effectiveness of the proposed controller in eliminating the unbalance vibrations at the design speed of rotation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.569-579
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• 2017

The purpose of this study was to test the mediation effects of adolescents' ego-resilience on the relation between neglect, abuse and life satisfaction. The 6-year longitudinal data from the Korean Children & Youth Panel Survey (KCYPS) were collected from 1st grade middle school students. The data were analyzed by structural equation modeling and Sobel testing.The results of this study were as follows. First, the results revealed that the path from neglect and abuse to life satisfaction was partially mediated by family relations. The relations between trauma(neglect) and ego-resilience are negative(${\beta}=-.258$, p<.001). The relations between ego-resilience and life satisfaction are positive(${\beta}=.843$, p<.001). Second, the verification of the mediation effect of ego-resilience showed that ego-resilience was a full mediator between trauma(neglect) and life satisfaction for 1st grade middle school students(Z=-.169, t(CR)=-.012 (p<.05). Based on these results, the practical implications were discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.651-659
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• 2017

Although the need for education on sexually-transmitted-infections (STIs) for adolescents has been increasing, a limited number of adolescents receive STI education. Importantly, the exposure of youth to an STI during their adolescence period can seriously affect their genital health. Smartphones are an innovative medium that can be used to change individual behaviors, especially useful when used to educate adolescents. Therefore, we developed a customized smartphone application for Korean adolescents. The application was based on Dick and Carey's instructional system design model. In this paper, we describe the process for development of the smartphone application, and the strategies we applied to attract adolescents to use the smartphone application. Six experts verified the educational content of the application. The application's easygoing words were chosen to help adolescents understand the topic. Strategies such as cartoon clips, secret chat rooms, buttons changing color from blue to grey, questions and answers, and a repeated-learning function were used to attract Korean adolescents to the application. The smartphone application developed in this study could be used in schools, youth centers, and hospital centers to improve STI knowledge, STI prevention, and STI coping skills.

• Science of Emotion and Sensibility
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• v.26 no.1
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• pp.17-32
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• 2023

This study aims to study the impact of pet attachment on subjective well-being, focusing on individuals who live with pets. In addition, it is to recognize that their basic psychological requirement mediates between pet attachment and subjective well-being. For this purpose, a survey was performed on 358 adults living with pets nationwide. The final data of 319 people were evaluated after excluding invalid information. Dependent on the theoretical approach of the attachment theory, the human-pet relationship was examined by dividing it into two orthogonal dimensions pet attachment prevention and pet attachment anxiety(Zilcha-Mano et al., 2011). The mediating effects were investigated as an in-depth mechanism that mediates between pet attachment and subjective well-being, the mediating effects were examined, in terms of the three basic psychological needs of Self-Determination Theory, which are autonomy, competence, and relatedness. As an outcome, first, pet attachment prevention and pet attachment anxiety both revealed a negative correlation with subjective well-being. Second, basic psychological needs, which are autonomy, competence, and relatedness, are mediated between pet attachment and subjective well-being. Autonomy, competence, and relatedness fully mediated the relationship between pet attachment avoidance and subjective well-being. Meanwhile, in the case of pet attachment anxiety, only autonomy among basic psychological needs is fully mediated between pet attachment anxiety and subjective well-being in the case of pet attachment avoidance. This means that pet attachment prevention or pet attachment anxiety correlates with subjective well-being by satisfying basic psychological needs instead of directly affecting personal well-being. Regarding the pet effect, it is meaningful to find an in-depth mechanism that the human-pet relationship has for an adaptive and positive impact on humans.

• Journal of KIISE:Software and Applications
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• v.30 no.3_4
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• pp.326-338
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• 2003

The objective of a neural network design and model selection is to construct an optimal network with a good generalization performance. However, training data include noises, and the number of training data is not sufficient, which results in the difference between the true probability distribution and the empirical one. The difference makes the teaming parameters to over-fit only to training data and to deviate from the true distribution of data, which is called the overfitting phenomenon. The overfilled neural network shows good approximations for the training data, but gives bad predictions to untrained new data. As the complexity of the neural network increases, this overfitting phenomenon also becomes more severe. In this paper, by taking statistical viewpoint, we proposed an integrative process for neural network design and model selection method in order to improve generalization performance. At first, by using the natural gradient learning with adaptive regularization, we try to obtain optimal parameters that are not overfilled to training data with fast convergence. By adopting the natural pruning to the obtained optimal parameters, we generate several candidates of network model with different sizes. Finally, we select an optimal model among candidate models based on the Bayesian Information Criteria. Through the computer simulation on benchmark problems, we confirm the generalization and structure optimization performance of the proposed integrative process of teaming and model selection.

• Journal of KIISE:Software and Applications
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• v.35 no.2
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• pp.118-127
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• 2008

In this paper, we propose a method for construction of robust 3D statistical shape model in the mandible CT datasets. Our method consists of following four steps. First, we decompose a 3D input shape Into patches. Second, to generate a corresponding shape of a floating shape, all shapes in the training set are parameterized onto a disk similar to the patch topology. Third, we generate the corresponding shape by one-to-one mapping between the reference and the floating shapes. We solve the problem failed to generate the corresponding points near the patch boundary Finally, the corresponding shapes are aligned with the reference shape. Then statistical shape model is generated by principle component analysis. To evaluate the accuracy of our 3D statistical shape model of the mandible, we perform visual inspection and similarity measure using average distance difference between the floating and the corresponding shapes. In addition, we measure the compactness of statistical shape model using the modes of variation. Experimental results show that our 3D statistical shape model generated by the mandible CT datasets with various characteristics has a high similarity between the floating and corresponding shapes and is represented by the small number of modes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.247-252
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• 2008

Recently, the virtual construction system in which project participants efficiently share and control the information throughout the life-cycle of construction project using 3D object models is being developed all over the world. In this paper, a design of interface between 3D object model of structures and structural analysis system that is essential for the analysis and design of civil structures in the virtual space is treated. The relation parametric modeling technique that is needed to make the 3D object models and the construction method of product breakdown structure(PBS) that considers the several parameters for the structural analysis are presented. PBS is built so that it is possible to extract needed attribute information from 3D object model and to apply it to the structural analysis. Design methodology for interface program is proposed that several numerical values determined by the cooperative work same as structural analysis are delivered to 3D object models without additional work. An interface program between 3D object models and structural analysis system developed based on the proposed method would be effectively used to develop virtual construction system.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.4
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• pp.97-105
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• 2001

Rubber bearings may exhibit a significant cold temperature effect and some velocity dependency(strain rate effect). Both of these attributes which affect non-linear behavior must be accounted for when accurately modeling the bearings behavior, therefore, an analytical models is proposed to consider the effects of the cold temperature and strain rate on both rubber and lead. From the results of an experimental investigation where the frozen bearings were tested under lateral cyclic loading with constant axial load, a non-linear system identification with least squares procedure was applied to determine the material properties of rubber and lead. It is demonstrated that the proposed analytical model is able to simulate the reversed cyclic loading behavior of elastometric and lead-rubber bearings.