• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1722-1729
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• 2006

Predicting the mechanical properties of the 3-D scaffold using finite element method (FEM) simulation is important to the practical application of tissue engineering. However, the porous structure of the scaffold complicates computer simulations, and calculating scaffold models at the pore level is time-consuming. In some cases, the demands of the procedure are too high for a computer to run the standard code. To address this problem, the representative volume element (RVE) theory was introduced, but studies on RVE modeling applied to the 3-D scaffold model have not been focused. In this paper, we propose an improved FEM-based RVE modeling strategy to better predict the mechanical properties of the scaffold prior to fabrication. To improve the precision of RVE modeling, we evaluated various RVE models of newly designed 3-D scaffolds using FEM simulation. The scaffolds were then constructed using microstereolithography technology, and their mechanical properties were measured for comparison.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.4-5
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• 2020

Pipe support is a representative structure that supports slab formwork, and it is a representative temporary equipment that has been systematically managed since the 1990s when the domestic temporary equipment performance test system was introduced. Nevertheless, it is also a reality that many of the products in circulation are used products that are reused and do not meet the performance of the initial manufacturing stage. However, if only new products are insisted, it could lead to delays in the process due to an increase in construction costs and difficulties in timely delivery. On the contrary, it is not acceptable for the safety of the construction site to use products of low quality without verification procedures or standards. Therefore, this study attempts to grasp the management system such as safety certification for temporary equipment and the actual condition of quality control to maintain performance, and propose improvement plans.

• Journal of Korea Multimedia Society
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• v.23 no.7
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• pp.803-811
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• 2020

This paper proposes an image classification algorithm that transforms the number of convolution layers in the residual block of ResNet, CNN's representative method. The proposed method modified the structure of 34/50 layer of ResNet structure. First, we analyzed the performance of small and many convolution layers for the structure consisting of only shortcut and 3 × 3 convolution layers for 34 and 50 layers. And then the performance was analyzed in the case of small and many cases of convolutional layers for the bottleneck structure of 50 layers. By applying the results, the best classification method in the residual block was applied to construct a 34-layer simple structure and a 50-layer bottleneck image classification model. To evaluate the performance of the proposed image classification model, the results were analyzed by applying to the cifar10 dataset. The proposed 34-layer simple structure and 50-layer bottleneck showed improved performance over the ResNet-110 and Densnet-40 models.

• Computational Structural Engineering : An International Journal
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• v.2 no.1
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• pp.33-42
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• 2002

A computationally efficient stiffness design method for building structures is proposed in which dynamic soil-structure interaction based on the wave-propagation theory is taken into account. A sway-rocking shear building model with appropriate ground impedances derived from the cone models due to Meek and Wolf (1994) is used as a simplified design model. Two representative models, i.e. a structure on a homogeneous half-space ground and a structure on a soil layer on rigid rock, are considered. Super-structure stiffness satisfying a desired stiffness performance condition are determined via an inverse problem formulation for a prescribed ground-surface response spectrum. It is shown through a simple yet reasonably accurate model that the ground conditions, e.g. homogeneous half-space or soil layer on rigid rock (frequency-dependence of impedance functions), ground properties (shear wave velocity), depth of surface ground, have extensive influence on the super-structure design.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.146-152
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• 2019

A design system was developed for the doubler plate of a ship structure simultaneously subjected to in-plane loads and lateral pressure based on general dimensions and those of a representative ship structure. An equivalent design equation that considers various structural design parameters was derived by introducing the equivalent plate thickness theory, and the design of the doubler plate reinforcement of the ship structure was developed. A hybrid structural design system was established for a doubler plate simultaneously subjected to in-plane loads and lateral pressure consisting of two modules: an optimized design module and a double plate strength & design review module. The practical application of this design system was illustrated to show its usability. It was found that the design safety of the doubler plate was ensured, and this system could be used as an initial design guide to review the double plate reinforcement for a dent or corrosion of the ship plate members. Using the developed design system would make it possible to obtain a more reasonable doubler plate structure that considers the rational reinforcement of plate members of ship structures. In addition, a more reliable structural analysis using a strength evaluation process can be performed to verify the efficiency of the optimum structural design for the doubler plate structure.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.6
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• pp.17-25
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• 2003

The physical components of a river, such as water surface width/river width ratio, water level, and flow velocity vary according to different flowrates. Moreover, the riverside landscapes are greatly affected by the change of physical components of the stream or river. This paper provides an analysis of the influence of changing physical components of a river on the riverside landscape using a survey-based quantification method. The questionnaire was developed based on current literature, and was submitted to 326 people who each visited a representative station along the riverside.This survey was implemented three times at each representative station during periods of different flowrates. The results of this analysis and survey have Produced an understanding of the relationship between the variation of physical components and riverside landscapes. Survey results about the flow comparison are summarized as follows. Viewing riverside landscapes, most respondents are sensitive to the change of the flow velocity and prefer high water levels to low water levels. As a whole, respondents prefer abundant stream flows and moderate flow velocity in which they can perceive the flow of water. The minimum instream flows for riverside landscapes is estimated at each representative station by using a survey-based quantification method, and the estimated results of some representative stations were greater than the mean monthly flow at each station. The result of this analysis shows that establishing minimum instream flows for riverside landscapes is not only a technical problem, but also a legal problem. Therefore, in the to establish the instream flows in a river, the estimated results have to be considered as a relative standard. Regarding the survey results, respondents' satisfaction level didn't show any clear inclination according to the variation of various hydraulic properties. In determining the minimum instream flow using such an inquiry method, the structure of riverside scenery may vary according to the change of seasons or months. Therefore, to determine a consistent general inclination about the flow rate, it is necessary to have more detailed flow rates for each season or month combined with more inquiries.

• Korean Journal of Legislative Studies
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• v.25 no.3
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• pp.5-31
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• 2019

In the process of changing the Korean electoral system, various terms such as representation, majority, minority, plurality, and proportionality are not used correctly, making normative judgment on its desirable electoral system difficult. This paper clarifies the concepts and terminology related to the electoral system in order to enable proper normative discussion. First, the misuse of the names of the electoral system is reviewed. This includes the majority representative system versus the minority representative system, the single-member constituency versus the multi-member constituency, the absolute majority system versus the relative majority system, and the majority representative system versus the proportional representative system. Next, the principles of representation, proportionality, democracy, direct ballot, and equal ballot are discussed to evaluate the decisions made by the Constitutional Court of Korea. In the current electoral system of the National Assembly, the equivalence between its constituency member and its proportional representation member is very low in terms of proportionality between votes received and seats allotted. Finally, the coherence between proportional representation and other political institutions is examined. Strengthening the proportionality of parliamentary elections alone does not necessarily increase the proportionality of the entire power structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.3
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• pp.159-165
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• 2021

This study introduces a topology optimization method for the simultaneous design of macro-scale structural configuration and unit structure variation to ensure effective heat conduction. Shape changes in the unit structure depending on its location within the macro-scale structure result in micro- as well as macro-scale design and enable better performance than using isotropic unit structures. They result in functionally graded composite structures combining both configurations. The representative volume element (RVE) method is applied to obtain various thermal conductivity properties of the multi-material based unit structure according to its shape change. Based on the RVE analysis results, the material properties of the unit structure having a certain shape can be derived using machine learning. Macro-scale topology optimization is performed using the traditional solid isotropic material with penalization method, while the unit structures composing the macro-structure can have various shapes to improve the heat conduction performance according to the simultaneous optimization process. Numerical examples of the thermal compliance minimization issue are provided to verify the effectiveness of the proposed method.

• Environmental Analysis Health and Toxicology
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• v.30 no.sup
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• pp.7.1-7.10
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• 2015

Objectives For successful adoption of legislation controlling registration and assessment of chemical substances, it is important to obtain sufficient toxicological experimental evidence and other related information. It is also essential to obtain a sufficient number of predicted risk and toxicity results. Particularly, methods used in predicting toxicities of chemical substances during acquisition of required data, ultimately become an economic method for future dealings with new substances. Although the need for such methods is gradually increasing, the-required information about reliability and applicability range has not been systematically provided. Methods There are various representative environmental and human toxicity models based on quantitative structure-activity relationships (QSAR). Here, we secured the 10 representative QSAR-based prediction models and its information that can make predictions about substances that are expected to be regulated. We used models that predict and confirm usability of the information expected to be collected and submitted according to the legislation. After collecting and evaluating each predictive model and relevant data, we prepared methods quantifying the scientific validity and reliability, which are essential conditions for using predictive models. Results We calculated predicted values for the models. Furthermore, we deduced and compared adequacies of the models using the Alternative non-testing method assessed for Registration, Evaluation, Authorization, and Restriction of Chemicals Substances scoring system, and deduced the applicability domains for each model. Additionally, we calculated and compared inclusion rates of substances expected to be regulated, to confirm the applicability. Conclusions We evaluated and compared the data, adequacy, and applicability of our selected QSAR-based toxicity prediction models, and included them in a database. Based on this data, we aimed to construct a system that can be used with predicted toxicity results. Furthermore, by presenting the suitability of individual predicted results, we aimed to provide a foundation that could be used in actual assessments and regulations.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.896-902
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• 2004

The purpose of the study of multi-robot system is to realize multi-robot system easy for the control of robot system in case robot is adapted in the complicated environment of task structure. The purpose of the study of multi-robot system is to realize multi-robot system easy for the control of robot system in case robot is adapted in the complicated environment of task structure. To make real time control possible by making effective use of recognized information in this dynamic environment, suitable distribution of tasks should be made in consideration of function and role of each performing robots. In this paper, IHMA (Intelligent Hybrid Modular Architecture) of Intelligent combined control architecture which utilizes the merits of deliberative and reactive controllers will be suggested and its efficiency will be evaluated through the adaptation of control architecture to representative multi-robot system.