• Journal of the Korean Chemical Society
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• v.63 no.6
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• pp.435-439
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• 2019

An efficient one pot multicomponent synthesis of pyrimidinone derivatives of Biginelli type is described. 4-amino-6-aryl-pyrimidine-5-carbonitrile molecules were synthesized efficiently via three-component Biginelli-type condensation of aldehyde, malononitrile, and semicarbazone as urea substituent in the presence of a catalytic amount of PEG-400 as green medium under microwave irradiation. The reactions proceeded efficiently in the presence of microwave radiation to afford the desired products in good to excellent yields. Products have been confirmed by IR, and NMR spectral analysis. All the molecules were tested for their antimicrobial activity against E. coli, S. aureus, P. aeruginosa and C. tropicalis. Some of the compounds have shown moderate to good inhibition efficiency against both gram-positive and gram-negative bacteria. The potent activity was observed against the fungal species with minimum inhibition concentration 12.5 ㎍/mL.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.501-505
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• 2007

현재 기술 동향에 따라, 언제 어디서나 통신 및 컴퓨팅이 가능한 유비쿼터스 컴퓨팅 시스템(Ubiquitous Computing System)을 위해 사용자 및 주변 환경의 상황을 인식하는 기술(Context-Aware Computing System)이 필수적인 요소로 부각되고 있다. 하지만, Context-Aware Computing System을 구현하기 위해서 사용자 및 주변 환경으로부터 입력되는 불확실하거나 모호한 상황정보에 대한 표현과 추론에 대한 연구는 부족한 실정이다. 이를 해결하기 위해 Rule-based System을 기반으로 CRS와 DOS의 개념을 도입하여 상황인식 기술을 SoC로 구현할 수 있도록 새로운 Architecture를 제안한다. 마지막으로는 CRS와 DOS가 Network Topolgy에 적용된 RODMRP(Resilient Ontology-based Dynamic Multicast Routing Protocol)의 예를 통해 그 효용성을 입증하고, Ubiquitous Computing System에서 활용 가능한 방법 등을 제시한다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.1
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• pp.26-33
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• 2014

This study addresses the control problem of an unmanned aerial vehicle (UAV) during the transition period when the flying mode changes from hovering to translational motion in the horizontal plane. First, we introduce a compensation algorithm that improves height stabilization and reduces altitude drop. The main principle is to incorporate pitch and roll measurements into the feedforward term of the altitude controller to provide a larger thrust force. To further improve altitude control, we propose the fuzzy logic controller that improves system behavior. Simulation results presented in the paper highlight the effectiveness of the proposed controllers.

• Journal of The Korean Association For Science Education
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• v.16 no.4
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• pp.461-469
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• 1996

The purpose of this study was to assess the attitudes of secondary school students in Korea toward science-technology related issues. A questionnaire was designed in which students were confronted with personal, global, and philosophical levels of arguments, which were composed of three against and three in favor of each eight issues, i.e., use of antibiotics, family planning, transplant of organs, genetic engineering, use of microorganisms. exploitation of the sea, land reclamation from the sea, and nature reserves. Student was requested to rate each argument independently and to vote for or against each issue. It was shown that most of students voted in favor of using technologies except land reclamation from the sea, and that students having more learning experiences on each topic vote more favorably. It is thought that our science education might be effective in increasing awareness and appreciation of benifits of technology, but it is not as effective in developing ambivalence attitudes.

• Annual Conference of KIPS
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• 2018.05a
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• pp.300-303
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• 2018

최근, 불균일 기억 장치 접근 (NUMA) 구조가 부각됨에 따라 NUMA 구조 기반의 관계 연산 기법들이 제안되고 있다. 본 논문에서는 NUMA 구조 기반의 효율적인 해시 조인 기법을 제안한다. NUMA 구조에서 조인 속성 값의 분포가 편중된 릴레이션들 간의 조인은 NUMA 노드들 간의 부하 불균형과 과도한 원격 메모리 접근을 발생시킬 수 있다. 제안 기법에서는 근사 히스토그램을 이용하여 조인 속성 값의 분포를 파악하고, 이를 기반으로 원격 메모리 접근을 줄이는 전달 방안을 제안한다. 실험에서는 입력 릴레이션들에 대해 조인 속성 값의 분포를 변화시키면서 제안 기법에 대한 성능을 평가한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.506-509
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• 2009

This paper studies about reducing the complexity of ML detection in MIMO/V-blast system, based on MMSE and ZF linear detectors. Beforehand, the receiver detects the signal using the linear detector such as ZF or MMSE. Moreover, the next step is to assess whether the signal is reliable or not by verifying the reliability condition, if the latter is reliable then it is the output if not it has to be detected by the advanced detector until the reliability condition is verified.

• Annual Conference of KIPS
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• 2013.05a
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• pp.289-292
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• 2013

본 논문은 SVM(Support Vector Machine) 학습알고리즘을 이용하여 자동차 썬루프 장치의 볼트 유무를 검사하는 자동차 부품 검사 장비에 관한 것이다. 자동화 시스템은 높은 정밀도와 생산성을 위한 빠른 처리 속도를 요구한다. 이를 위해 본 논문에서는 선형 SVM 학습알고리즘을 활용하여 자동차 썬루프 장치의 볼트 유무를 검사하는 알고리즘을 개발하였다. SVM 알고리즘은 분류를 위한 알고리즘이지만 ROI(Region-Of-Interest) 내의 모든 윈도우에 대한 분류를 수행하여 검출기 역할을 할 수 있도록 한다. 볼트가 있는 경우와 볼트가 없는 경우가 아닌 네거티브 샘플을 확보하기 위해 검출 대상 물체 주변에서 다양한 네거티브 샘플들을 추출한다. 그 결과 물체가 예상 위치에서 다소 빗나가는 경우에도 볼트 유무를 판별할 수 있을 뿐 아니라 볼트의 위치까지 검출할 수 있고, 처리 속도에서 자동화 시스템이 요구하는 수준에 도달함을 실험 결과를 통해 검증한다.

• Research in Mathematical Education
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• v.16 no.1
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• pp.51-66
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• 2012

This study investigated the impact of entry level of mathematics subject knowledge on student teachers' mathematics pedagogical content knowledge development and performance in mathematics teaching practice. The sample consisted of 24 mathematics student teachers, 12 of whom passed A-Level mathematics and 12 of whom only passed O-level mathematics. They were all studying in a 4-year bachelor of education (Honours/Primary) programme; they were either majoring or minoring in mathematics. Results showed that student teachers' entry-level mathematics subject knowledge is not related to their mathematics pedagogical content knowledge development or their mathematics teaching performance. These findings may lead society to consider whether student teachers who have passed O-level mathematics are already eligible to be trained as professional primary mathematics teachers. As a consequence, this study raises the issues of how to develop student teachers' mathematics pedagogical content knowledge and whether we need to restructure our bachelor of education (Primary) programmes' curriculum in teacher professionalism.

• Journal of Practical Engineering Education
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• v.8 no.2
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• pp.75-81
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• 2016

This research proposes to design a flipped classroom with strategic questioning to enhance engineering student's creative problem-solving competency on the basis of the subject knowledge. By applying the designed flipped classroom to both of college and dual system engineering courses during one semester, this study explores to find the meaning and effects of the flipped learning method. The case study analyzed the influences of the flipped learning with the use of strategic questioning on student's problem-solving performance, and also investigated student satisfaction and evaluation of the learning in order to draw out the factors to consider further in the instructional design.

• Research in Mathematical Education
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• v.18 no.3
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• pp.171-185
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• 2014

Mathematically deductive reasoning skill is one of the major learning objectives stated in senior secondary curriculum (CDC & HKEAA, 2007, page 15). Ironically, student performance during routine assessments on geometric reasoning, such as proving geometric propositions and justifying geometric properties, is far below teacher expectations. One might argue that this is caused by teachers' lack of relevant subject content knowledge. However, recent research findings have revealed that teachers' knowledge of teaching (e.g., Ball et al., 2009) and their deductive reasoning skills also play a crucial role in student learning. Prior to a comprehensive investigation on teacher competency, we use a case study to investigate teachers' knowledge competency on how to teach their students to mathematically argue that, for example, two triangles are congruent. Deductive reasoning skill is essential to geometry. The initial findings indicate that both subject and pedagogical content knowledge are essential for effectively teaching this challenging topic. We conclude our study by suggesting a method that teachers can use to further improve their teaching effectiveness.