• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2248-2250
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• 2004

본 논문에서는 유연한 단일링크 매니퓰레이터의 끝단 위치 추적제어를 위해 웨이블렛 신경망을 이용한 강인 적응제어기를 제안한다. 전체 제어기는 웨이블렛 신경망에 의해 추정된 피드백 선형화 제어기와 그 추정오차를 보상하기 위한 보상제어기로 구성된다. 시스템의 출력값은 최소위상을 보장하기 위하여 재정의하여 사용된다. 구성된 웨이블렛 신경망의 연결 가중치는 Lyapunov 안정도 이론에 기초해서 조절된다. 제안된 제어기의 성능 향상은 PD 제어기와 비교함으로써 입증된다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.5
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• pp.299-307
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• 2003

The local structure of CMAC neural networks (NN) results in better and faster controllers for nonlinear dynamical systems. In this paper, we propose a CMAC NN-based disturbance observer and its corresponding controller for a flexible joint robot. The CMAC NN-based disturbance observer compensates for the parametric uncertainties and the external disturbances throughout the entire mechanical system. Finally, a simulation result is given to demonstrate the effectiveness of proposed design method's robust tracking performance.

• Journal of the Korean Chemical Society
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• v.57 no.4
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• pp.499-506
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• 2013

In this study, clicker, also known as classroom response system, was applied to the chemistry method course at the university in Gyeongbuk, and preservice chemistry teachers' perceptions of clicker were surveyed. Before starting lecture, operation and class application of clickers were introduced to preservice teachers, and then 4-5 questions were presented to them in most classes during the term. After preservice teachers were asked to answer the questions, lecturer gave feedback based on the class answer distribution. Questions presented to preservice teachers were recall and/or understanding questions on learning contents, opinion questions, and questions about muddiest point. At the end of semester, preservice teachers were asked to rate their perception of clikers in terms of likert scale and essay type. They had positive perceptions of clicker use in aspects of cognitive effects, affective effects and media characteristics. They preferred conceptual understanding questions and monitoring questions among 8 clicker question types. Some cases using clickers in lecture and educational implications were also included.

• Journal of Korea Multimedia Society
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• v.5 no.5
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• pp.538-551
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• 2002

Even though the distance education via Web has a great advantage to overcome time and space, its problem that the management of trainees is not efficient compared with classroom and group education. This problem is a great obstacle to the objects and achievement standards of distance education, giving controversial arguments to the advocators of distance education. Distance educators need to monitor the trainees 'participation and responses continuously and offer appropriate feedback to the trainees. However, the existing distance education system only focuses on teaching and teaming activities, and as a result, the efficient management function of distance education is not available. Accordingly, the study attempts to find out the appropriate managing elements of distance teacher training in order to effectively achieve the goals of teacher training and the efficient management of distance education. Also, it proposes distance teacher training system that offers appropriate feedback to trainees, applying the derived elements of distance teacher training to the training processes. To verify the efficiency of the system, hypotheses on related items of distance teacher education and learning types are suggested, and the achievement of learning and its relations are investigated through questionnaire of learning types.

• Journal of Internet Computing and Services
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• v.15 no.5
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• pp.33-41
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• 2014

The purpose of this study is to provide statistical analysis based suggestions on effective methods to take advantage of social network service (SNS) for educational purposes based on investigations of undergraduate students with high utilization of SNS. To achieve this, we conducted an open questionnaire survey and qualitatively analyzed the data using NVivo 10 program. Additionally, to visualize the analysis by education subject of the SNS educational methods, we have divided the data into 3 categories of teacher, student and common area. As a result, our analysis showed that the exchange opinions and discussions, information sharing and learning of contents of questions and answers, surveys, intimacy formation, counseling etc. were of the common area. Furthermore, teacher area included the notice announcement, teaching materials sharing, real-time assessment (quiz), attendance check, assignment grading and feedback, etc. Finally the student area was of project activities (group/individual), prepare and review the shared data, video self learning, peer review and feedback of projects, lecture evaluation, etc.

• Journal of Engineering Education Research
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• v.8 no.4
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• pp.52-63
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• 2005

National competitiveness is related directly to the strength of educational competitiveness of universities. Seoul National University (SNU) has been taking efforts to improve its competitiveness in University education in variety of ways and the classroom assessment is one key example of those. The current classroom assessment system practiced at universities is being used to evaluate courses and professors in charge by the university administration or evaluation committee. The classroom assessment system is not intended to put students and professors as the subject of the evaluation. In this case, the evaluation is intended wrongfully to rank the courses and evaluate professors' achievement by assigning grades on the lectures. Instead, a proper classroom assessment system should be targeted to improve the quality of lectures by encouraging communication among professor and students in the classroom. In this study, it was intended to investigate a suitable classroom assessment system to enhance the effectiveness of education, not to rank the courses and evaluate professors' achievement. For this purpose, research has been carried out to investigate opinions of professors at SNU on the criteria of classroom assessment and to analyze the criteria of classroom assessment at other domestic universities in Korea. The inquiries for feedback on the lecture by the student in the class was analyzed. The current classroom assessment system at SNU was reviewed and an improvement plan was devised to evaluate liberal art courses of engineering and science schools at SNU. In this research, the problems in the classroom assessment system was reviewed and improvement points were searched to utilize the classroom assessment system more effectively for the improvement of lecture quality.

• Annual Conference on Human and Language Technology
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• 1999.10e
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• pp.7-12
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• 1999

정보 검색 시스템은 사용자 질의의 키워드들과 문서들의 유사성(similarity)을 기준으로 관련 문서들을 순서화하여 사용자에게 제공한다. 그렇지만 인터넷 검색에 사용되는 질의는 일반적으로 짧기 때문에 보다 유용한 질의를 만들고자 하는 노력이 지금까지 계속되고 있다. 그러나 키워드에 포함된 정보가 제한적이기 때문에 이에 대한 보완책으로 사용자의 적합성 피드백을 이용하는 방법을 널리 사용하고 있다. 본 논문에서는 일반적인 적합성 피드백의 가장 큰 단점인 빈번한 사용자 참여는 지양하고, 시스템에 기반한 적합성 피드백에서 배제한 사용자 참여를 유도하는 검색 문서의 분류 정보에 기반한 용어 클러스터 질의 확장 모델(Term Cluster Query Expansion Model)을 제안한다. 이 방법은 검색 시스템에 의해 검색된 상위 n개의 문서에 대하여 분류기를 이용하여 각각의 문서에 분류 정보를 부여하고, 문서에 부여된 분류 정보를 이용하여 분류 정보의 수(m)만큼으로 문서들을 그룹을 짓는다. 적합성 피드백 알고리즘을 이용하여 m개의 그룹으로부터 각각의 용어 클러스터(Term Cluster)를 생성한다. 이 클러스터가 사용자에게 문서 대신에 피드백의 자료로 제공된다. 실험 결과, 적합성 알고리즘 중 Rocchio방법을 이용할 때 초기 질의보다 나은 성능을 보였지만, 다른 연구에서 보여준 성능 향상은 나타내지 못했다. 그 이유는 분류기의 오류와 문서의 특성상 한 영역으로 규정짓기 어려운 문서가 존재하기 때문이다. 그러나 검색하고자 하는 사용자의 관심 분야나 찾고자 하는 성향이 다르더라도 시스템에 종속되지 않고 유연하게 대처하며 검색 성능(retrieval effectiveness)을 향상시킬 수 있다.사용되고 있어 적응에 문제점을 가지기도 하였다. 본 연구에서는 그 동안 계속되어 온 한글과 한잔의 사용에 관한 논쟁을 언어심리학적인 연구 방법을 통해 조사하였다. 즉, 글을 읽는 속도, 글의 의미를 얼마나 정확하게 이해했는지, 어느 것이 더 기억에 오래 남는지를 측정하여 어느 쪽의 입장이 옮은 지를 판단하는 것이다. 실험 결과는 문장을 읽는 시간에서는 한글 전용문인 경우에 월등히 빨랐다. 그러나. 내용에 대한 기억 검사에서는 국한 혼용 조건에서 더 우수하였다. 반면에, 이해력 검사에서는 천장 효과(Ceiling effect)로 두 조건간에 차이가 없었다. 따라서, 본 실험 결과에 따르면, 글의 읽기 속도가 중요한 문서에서는 한글 전용이 좋은 반면에 글의 내용 기억이 강조되는 경우에는 한자를 혼용하는 것이 더 효율적이다.이 높은 활성을 보였다. 7. 이상을 종합하여 볼 때 고구마 끝순에는 페놀화합물이 다량 함유되어 있어 높은 항산화 활성을 가지며, 아질산염소거능 및 ACE저해활성과 같은 생리적 효과도 높아 기능성 채소로 이용하기에 충분한 가치가 있다고 판단된다.등의 관련 질환의 예방, 치료용 의약품 개발과 기능성 식품에 효과적으로 이용될 수 있음을 시사한다.tall fescue 23%, Kentucky bluegrass 6%, perennial ryegrass 8%) 및 white clover 23%를 유지하였다. 이상의 결과를 종합할 때, 초종과 파종비율에 따른 혼파초지의 건물수량과 사료가치의 차이를 확인할 수 있었으며, 레드 클로버 + 혼파 초지가 건물수량과 사료가치를 높이는데 효과적이었다.\ell}$ 이었으며 , yeast extract 첨가(添加)하여 배양시(培養時)는 yeast extract

• Management & Information Systems Review
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• v.36 no.3
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• pp.17-35
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• 2017

This study investigates the determinants of strategic positional change. Specifically, the study suggests performance feedback affects to a firm's strategic repositioning. Performance feedback is a concept that a firm decides whether success or not by comparing its performance relative to its aspiration level. Prior studies successively discover diverse behaviors. The study suggests three unexplored relationships between performance gaps and strategic positioning. First, when a firm's performance is below relative to its aspiration level, that firm's strategic position will be deviate from the industry norm. Second, as the degree of industrial density increases, the tendency that a firm's strategic position becomes deviate from the industry norm decreases. Third, when the degree of reference group's performance decreases, the tendency that a firm's strategic position becomes deviate from the industry norm decreases. For empirical analysis, this study examines data of 538 firms that in North America crude petroleum and natural gas industry. The result reveals that the direction of a firm's strategic change is shaped when firms' performance is below relative to aspiration level. Also, this relationship is moderated as industrial density changes or when reference groups' performance decreases. This study contributes to the current literature by explaining how a firms' strategic position is decided. Also, this study reveals that reference groups' performance could affect to organizational choice.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.125-127
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• 2008

기존의 LED(Light Emitting Diode)를 이용한 LCD(Liquid Crystal Display) 백라이트 유닛은 LED에 과전류가 흐르면 소자의 파손이 발생하고 무부하시 불필요한 전력소모가 발생하는 경우가 있어 보호회로가 필요하였다. 그래서 본 논문은 보호회로를 이용한 LCD 백라이트 유닛용의 LED 구동회로를 제안한다. 제안된 보호회로는 2가지로 첫 번째 보호회로는 무부하시 소비전력을 줄이는 보호회로 이다. 시뮬레이션 결과 무부하시 피드백 제어부 IC(Integrated Circuit)의 전원전압 $V_{cc}$를 UVLO(Under Voltage Lock Out)전압 이하로 강하시켰다. 그래서 무부하시 소비되는 전력을 줄일 수 있었다. 두번째 보호회로는 과전류시 보호회로 이다. 시뮬레이션 결과 과전류시 SCR이 온 되어 피드백 제어부 IC의 전원전압 $V_{cc}$를 UVLO전압 이하로 강하시켰다. 따라서 과전류시 LED 동회로 소자의 파손을 방지할 수 있는 장점이 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.11
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• pp.1069-1076
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT(Quantitative Feedback Theory) is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. Tracking specification is satisfied with upper and lower bound tolerances on the steep response of the system to the reference signal. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.