• Journal of Korean society of Dental Hygiene
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• v.2 no.1
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• pp.1-19
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• 2002

This study has been conducted with continuous dental sanitary education for primary school pupils for five years from 1997 through 2001, based on data obtained from a 97' survey on primary school pupils' recognition on dental hygiene education and their permanent dental health capacity. Following results were drawn through comparative analysis of data obtained during the survey period. Approx 70.77% of the examinees have experienced decay missing feeling (DMF) in the year 2001, suggesting a good effectiveness of dental hygiene education compared with 92.1 % of DMF rate in 1997. It has been found that pupils' knowledge and recognition on dental hygiene and management, etc were improved, as well as their eating habits and consciousness were changed. Comparative analysis of annual DMF showed that DMF rate, DMFT index, and DT rate were found to decrease every year, suggesting a improved dental health capacity. Grade level analysis revealed that DMFT index and DT rate were found to decrease every year during the survey period, suggesting pupils' dental management and consciousness were improved and changed. It has been found that DMF rate more significantly increased in a higher grade in 2001 than 1997. There was no difference in DMF rate between grades of primary school in 1997. However, in the year 2001 increment of approx 10% of DMF rate were observed in a higher grade.

• The Journal of Korea Robotics Society
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• v.15 no.2
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• pp.147-159
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• 2020

Over the last years, a number of different path following methods for the autonomous parking system have been proposed for tracking planned paths. However, it is difficult to find a study comparing path following methods for a short path length with large curvature such as a parking path. In this paper, we conduct a comparative study of the path following methods for perpendicular parking. By using Monte-Carlo simulation, we determine the optimal parameters of each controller and analyze the performance of the path following. In addition, we consider the path following error occurred at the switching point where forward and reverse paths are switched. To address this error, we conduct the comparative study of the path following methods with the one thousand switching points generated by the Monte-Carlo method. The performance of each controller is analyzed using the V-rep simulator. With the simulation results, this paper provides a deep discussion about the effectiveness and limitations of each algorithm.

• The Journal of Korea Robotics Society
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• v.12 no.1
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• pp.42-54
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• 2017

Using an inverse of the geometric Jacobian matrix is one of the most popular ways to control robot manipulators, because the Jacobian matrix contains the relationship between joint space velocities and operational space velocities. However, the control algorithm based on Jacobian matrix has algorithmic singularities: The robot manipulator becomes unstable when the Jacobian matrix loses rank. To solve this problem, various methods such as damped and filtered inverse have been proposed, but comparative studies to evaluate the performance of these algorithms are insufficient. Thus, this paper deals with a comparative analysis of six representative singularity avoidance algorithms: Damped Pseudo Inverse, Error Damped Pseudo Inverse, Scaled Jacobian Transpose, Selectively Damped Inverse, Filtered Inverse, and Task Transition Method. Especially, these algorithms are verified through computer simulations with a virtual model of a humanoid robot, THORMANG, in order to evaluate tracking error, computational time, and multiple task performance. With the experimental results, this paper contains a deep discussion about the effectiveness and limitations of each algorithm.

• Journal of information and communication convergence engineering
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• v.2 no.4
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• pp.247-250
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• 2004

Currently, advanced countries such as European countries and Japan invest lots of efforts to develop improvement of electric power production and supply, environmental countermeasure, and renewable energy development. Accordingly, Korea has been putting efforts to all kinds of electric related technical development based on the mid-long term plan. Further, it is necessary to increase effectiveness of R&D investment by propelling joint research activities with advanced countries for development of important technologies. Based on this background, this study tries to find thought-provoking suggestions of energy projects, programs and policies. For a comparative analysis, Japan which is similar to Korea in terms of market size and policies, and EU where joint research has been actively carried out among nations are analyzed and compared to policies and joint R&D activities of Korea.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.279-287
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• 2003

This paper deals with a comparative study on coupling of Element-free Galerkin(EFG) method and Infinite Element(IE) by IE's shape function. In this study, mapped infinite elements(mapped IE) and decay function infinite elements(decay IE) are coupled with the EFG method. A coupling procedure of EFG-Mapped IE is much easier to be integrated than a coupled EFG-Decay IE. A coupled EFG-IE method used well-defined functions to preserve the continuity and linear consistency on the interface of the EFG region and IE region. Several benchmark problems are solved to verify the effectiveness and accuracy of the coupling algorithms by IE's shape function. The numerical results show that the developed algorithms work well for the elastic problems with infinite boundaries.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.125-128
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• 2010

A large quantity of purified water sludge is generated in modern cities around the world. Dewatering is essential to reduce the volumes transported off-site for disposal. Traditionally employed methods such as solar drying methods are time-consuming. There are urgent demands for developing alternatives to dewater the sludge in a less time-consuming manner. In this paper, siphon method is proposed to dewater the high-water-content sludge with plastic drainage plate installed horizontally. A group of comparative tests are conducted to preliminarily investigate the dewatering behavior of the purified water sludge with siphon and solar drying methods, respectively. On the basis of the test results, the availability and effectiveness of the new method is verified. It may provide an innovative solution to treat the purified water sludge more effectively.

• Earthquakes and Structures
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• v.10 no.3
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• pp.613-628
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• 2016

The effectiveness of the use of modern repair schemes for the seismic retrofit of existing RC structures were assessed on a comparative experimental study of carbon fiber-reinforced polymer (CFRP) strips and sheets for the repair of reinforced concrete members of RC frames, damaged because of cyclic loading. Two virgin, single - story, one - bay, 1/3 - scale frame specimens were tested under cyclic horizontal loading, up to a drift level of 4%. Then, virgin specimens, B and F, respectively, were repaired and retested in the same way. One, specimen RB, was repaired with epoxy injections and CFRP strips and one, specimen RF, was repaired with epoxy injections and CFRP sheets. The two specimens are used to examine the differences between the structural behavior of frames repaired using CFRP strips and frames repaired using CFRP sheets. Both qualitative and quantitative conclusions, based on the observed maximum loads, loading and reloading stiffness, hysteretic energy absorption and failure mechanisms are presented and compared. The repaired frames recovered their strength, stiffness and energy dissipated reasonably. The use of CFRP sheets was found more effective than CFRP strips, due to the proper anchorage.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.211-215
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• 2023

In this paper, the stability and effectiveness of the force control with a 6-axis compliance device are verified by performing comparative experiments with a commercial F/T sensor. The position/force control algorithm based on the Cartesian stiffness of a compliance device is briefly introduced and the design result of a 6-axis compliance device with F/T sensing is presented. The comparative experiments show that the force control using a compliance device is much more stable than that with rigid F/T sensor due to the enough compliance of a compliance device larger than robot positional resolution.

• Korea Trade Review
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• v.45 no.4
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• pp.171-194
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• 2020

Although there is a lot of literature on the effectiveness of regional trade agreements(RTAs), it is usually analyzed only using trade-related theories and data. However, this paper has a differentiation in that we examine the linkage between international trade and financial markets through the stock markets reactions when the trade agreements related news arrived. Specifically, using an event study, we look into the Korea-US free trade agreement(KORUS FTA) which is the most commercially significant FTA in almost two decades for both the countries. Korean stock market generally responded more sensitively to FTA news than the US stock market, especially in 'Auto & Parts', 'Electrical Equipment' and 'Chemicals' industries. And the investors' perception toward the effect of KORUS FTA on Korean industries changed from negative to positive as negotiations proceed. Korea has a comparative advantage in the production of labor-intensive goods relative to US, but the economies of scale hypothesis does not hold.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.11
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• pp.2903-2923
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• 2023

Knowledge recommendation is a type of recommendation system that recommends knowledge content to users in order to satisfy their needs. Although using graph neural networks to extract data features is an effective method for solving the recommendation problem, there is information loss when modeling real-world problems because an edge in a graph structure can only be associated with two nodes. Because one super-edge in the hypergraph structure can be connected with several nodes and the effectiveness of knowledge graph for knowledge expression, a dual-channel hypergraph convolutional neural network model (DCHC) based on hypergraph structure and knowledge graph is proposed. The model divides user data and knowledge data into user subhypergraph and knowledge subhypergraph, respectively, and extracts user data features by dual-channel hypergraph convolution and knowledge data features by combining with knowledge graph technology, and finally generates recommendation results based on the obtained user embedding and knowledge embedding. The performance of DCHC model is higher than the comparative model under AUC and F1 evaluation indicators, comparative experiments with the baseline also demonstrate the validity of DCHC model.