• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.215-226
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• 2016

Modeling, control and implementation of a real redundant robot with five Degrees Freedom (DOF) of the SCARA (Selective Compliant Assembly Robot Arm) manipulator type is presented. Through geometric methods and structural and functional considerations, the inverse kinematics for redundant robot can be obtained. By means of a modification of the classical sliding mode control law through a hyperbolic function, we get a new algorithm which enables reducing the chattering effect of the real actuators, which together with the learning and adaptive controllers, is applied to the model and to the real robot. A simulation environment including the actuator dynamics is elaborated. A 5 DOF robot, a communication interface and a signal conditioning circuit are designed and implemented for feedback. Three control laws are executed in: a simulation structure (together with the dynamic model of the SCARA type redundant manipulator and the actuator dynamics) and a real redundant manipulator of the SCARA type carried out using MatLab/Simulink programming tools. The results, obtained through simulation and implementation, were represented by comparative curves and RMS indices of the joint errors, and they showed that the redundant manipulator, both in the simulation and the implementation, followed the test trajectory with less pronounced maximum errors using the adaptive controller than the other controllers, with more homogeneous motions of the manipulator.

• 한국대기환경학회지
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• 제9권3호
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• pp.207-215
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• 1993

In order to statistically predict $O_3$ levels in Seoul, the study used the TMS (telemeted air monitoring system) data from the Department of Environment, which have monitored at 20 sites in 1989 and 1990. Each data in each site was characterized by 6 major criteria pollutants ($SO_2, TSP, CO, NO_2, THC, and O_3$) and 2 meteorological parameters, such as wind speed and wind direction. To select proper variables and to determine each pollutant's behavior, univariate statistical analyses were extensively studied in the beginning, and then various applied statistical techniques like cluster analysis, regression analysis, and expert system have been intensively examined. For the initial study of high level $O_3$ prediction, the raw data set in each site was separated into 2 group based on 60 ppb $O_3$ level. A hierarchical cluster analysis was applied to classify the group based on 60 ppb $O_3$ into small calsses. Each class in each site has its own pattern. Next, multiple regression for each class was repeatedly applied to determine an $O_3$ prediction submodel and to determine outliers in each class based on a certain level of standardized redisual. Thus, a prediction submodel for each homogeneous class could be obtained. The study was extended to model $O_3$ prediction for both on-time basis and 1-hr after basis. Finally, an expect system was used to build a unified classification rule based on examples of the homogenous classes for all of sites. Thus, a concept of high level $O_3$ prediction model was developed for one of $O_3$ alert systems.

• 한국양식학회:학술대회논문집
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• 한국양식학회 2004년도 수산관련학회 공동학술대회 발표요지집
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• pp.169-171
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• 2004

Interannual and decadal scale body size of Pacific saury, catch and catch per unit effort were examined to investigate the environmental effects on the stock structure and abundance in the Tsushima Warm Current region. Interannual changes in thermal conditions are responsible for the different occurrence (catch) rates of sized group of the fish. Changes in body size due to environmental variables lead the stock to be homogeneous during the period of high abundance, while one of the reminder cohorts supports the stock during the period of low level of abundance. Migration circuits of two cohorts of saury stock are hypothesized on the basis of short life span and spatio-temporal changes in stock structure in normal environmental conditions. Changes in upper ocean structure and production cycles by the decadal scale climate changes lead changes in stock structure and recruitment, resulting in the fluctuation of saury abundance. Hypothesized mechanism of the effects of climate changes on the stock structure and abundance is illustrated on the basis of changes in thermal regime and production cycle.

• 한국학교수학회논문집
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• 제2권1호
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• pp.157-166
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• 1999

Compared with other subjects, mathematics has great differences in achieve-ment. In hope of solving this problems, most schools try the level-movement learning. Although they say it may have some effect because of its homogeneous group, the level groups still have differences in achievement in their students abilities. So, this study aims to present an appropriate tasks for the advanced, intermediate and beginner groups and to help self-directed learning by selecting an appropriate tasks for the students' own level. To achieve thiese goals, a great deal of level tasks were developed and given to the students. After lettins them an select appropriate tasks for their own level and perform self-directed learning, the tasks were measured carefully for their interest, attitude and achievement in learning. Consequently, we tried a new method to improve uniformity and to turn teacher-centered learning into student-centered learning. The following is the conclusion to this study. First, self-directed learning based on the selection of level tasks has meaningful effects on learning achievement in mathematics, especially for the beginner group. Second, though the above method did not improve an interest for mathematics, but was very effective in the improvement of learning attitudes.

• 디지털콘텐츠학회 논문지
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• 제5권4호
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• pp.283-288
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• 2004

본 논문은 가상대학 학사지원을 위한 지능형 메신저 기술에 관한 연구이다. 지능형 메신저는 학교 내에 구축된 교내 망을 이용하여 구축된 인트라넷 환경에서 사용된다. 본 논문에서는 지능형 메신저를 통해 학생과 교수간의 보다 효과적인 커뮤니케이션을 구현하기 위한 기술들을 제안한다. 인트라넷 기반 메신저는 같은 네트워크 혹은 소속된 그룹의 구성원들 간의 간단한 메시지 전송과 멀티미디어 채팅서비스를 지원하며 학사 데이터베이스의 정보를 이용해 각 사용자성향에 맞는 정보를 제공하며 자신이 속한 구성원에 대한 그룹 관리 기능을 통해 효과적으로 그룹을 관리 할 수 있도록 한다. 본 논문에서 제안된 지능형 메신저의 구현을 위해 JMF(Java Media Frame work), RMI(Remote Method Invocation), XML등의 기술을 제안했으며 이를 통해 효과적인 커뮤니티를 구축하고자 한다.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.23-31
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• 2020

This paper investigates the impact of monetary policy independence shock on bond yield by allowing for heterogeneous coefficients in the model based on panel data for 19 developing countries using quarterly data from 1991 to 2016. First, we estimate the model using conventional panel VAR estimation with the assumption of homogeneous coefficients across countries. Second, by performing Chow and Roy-Zellner tests to check the homogeneity assumption, we find that the assumption does not hold in the model. Third, we apply a mean-group estimation for panel VAR as a solution for heterogeneity panel model. The results reveal that central bank independence is effective in reducing bond yield with the maximum at period 6 after the shock. Shock one standard deviation bond yield has a negative effect on consumption and investment. We determine that central bank independence has a contradictory effect on real activity; a negative effect on consumption but a positive influence on investment for the first two years after the shock. Additionally, we split our sample into three groups to make the subgroups pool. Our empirical result shows that monetary policy independence shock reduces bond yield. Meanwhile, the response of economic activity to bond yield varies for all three groups.

• 대한치과기공학회지
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• 제33권1호
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• pp.47-54
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• 2011

Purpose: To investigate shear bonding strength between dental zirconia ceramics with different surface treatment and metal bracket. Methods: Zirconia ceramics(LAVA, 3M ESPE, USA) were divided to 4 groups according to their surface treatment; no surface treatment(G1), sand blasting(G2), silane coating(G3), and sand blasting+silane coating(G4). Specimens were bonded to metal bracket using resin bond($Transbond^{TM}XT$, 3M Unitek, USA). Shear bond strength was measured using universal test machine(3366 INSTRON. U.S.A) with cross head speed of 1 mm/min. Microstructural investigation for fracture surface was performed after shear test. Results: Shear bonding strengths of single surface treatment groups (G2 and G3) were higher than no treatment group(G1). Combined Treatment Group (G4) showed the highest shear bond strength of 9.15MPa. Microstructural observation shows that higher shear bonding strength was obtained when debonding was occurred at metal bracket/resin interface rather than zirconia ceramic/resin interface. Conclusion: Surface treatment of zirconia is necessary to obtain higher bonding strength. Combined treatment can be more effective when surface the surfaces are kept clean and homogeneous.

• 한국컴퓨터정보학회논문지
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• 제23권10호
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• pp.11-21
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• 2018

In this paper we propose a novel log template discovery algorithm which achieves high quality of discovered log templates through iterative log filtering technique. Log templates are the static string pattern of logs that are used to produce actual logs by inserting variable values during runtime. Identifying individual logs into their template category correctly enables us to conduct automated analysis using state-of-the-art machine learning techniques. Our technique looks at the group of logs column-wise and filters the logs that have the value of the highest proportion. We repeat this process per each column until we are left with highly homogeneous set of logs that most likely belong to the same log template category. Then, we determine which column is the static part and which is the variable part by vertically comparing all the logs in the group. This process repeats until we have discovered all the templates from given logs. Also, during this process we discover the custom patterns such as ID formats that are unique to the application. This information helps us quickly identify such strings in the logs as variable parts thereby further increasing the accuracy of the discovered log templates. Existing solutions suffer from log templates being too general or too specific because of the inability to detect custom patterns. Through extensive evaluations we have learned that our proposed method achieves 2 to 20 times better accuracy.

• 한국간호교육학회지
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• 제12권2호
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• pp.257-264
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• 2006

Purpose: The purpose of this study is to identify the effects of visual health promotion program for preschool children. Method: The experimental group participating in the visual health promotion program was 32 preschool children and the control group consisted of 34 preschool children by homogeneous age. The visual health promotion program was based on articles related to childern's visual health promotion and previous education program. Data were collected with 3 questionnaires that modified by the investigator. The data was analyzed by the SPSS win 10.0 program using descriptive statistics, $x^2$ test, t-test. Result: The level of knowledge about visual health promotion of preschool children who participated in the visual health promotion program was significantly higher than preschool children who did not participate(t=.02, P<.001). The level of behavior about visual health promotion of preschool children who participated in the visual health promotion program was significantly higher than preschool children who did not participate(t=.31, P<.001). Conclusion: The visual health promotion program developed in this study is an effective strategy for nursing intervention by increasing knowledge and behavior about visual health promotion of preschool children.

• 한국군사과학기술학회지
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• 제15권4호
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• pp.502-506
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• 2012

In order to find the structural characteristics of the thin films of group II-VI semiconductor compounds compared with those of powder materials, films were made of 4 powders of ZnS, CdS, CdSe, and CdTe(Aldrich), each with 99.99 % purity. For the ZnS/CdS multi-layers, the ZnS layer was coated over the CdS layer on an $AlO_x$ membrane, which served as a protective layer within a vacuum at the average speed of 1 ${\AA}$/sec. After studying the structures of the group II-VI semiconductor thin films by using X-ray spectroscopy, we found that the ZnS, ZnS/CdS, CdS, and CdSe films were hexagonal and exhibited some degree of preferred orientation. Also, the particles of the thin films of II-VI semiconductor compounds proved to be more homogeneous in size compared to those of the powder materials. These results were further verified through scanning electron microscopy(SEM), EDX analysis, and powder and thin film X-ray diffraction.