• Journal of Intelligence and Information Systems
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• v.29 no.1
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• pp.233-247
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• 2023

Recently, research on detecting objects in hidden spaces beyond the direct line-of-sight of observers has received attention. Most studies use optical equipment that utilizes the directional of light, but sound that has both diffraction and directional is also suitable for non-line-of-sight(NLOS) research. In this paper, we propose a novel method of detecting objects in non-line-of-sight (NLOS) areas using acoustic signals in the audible frequency range. We developed a deep learning model that extracts information from the NLOS area by inputting only acoustic signals and predicts the properties and location of hidden objects. Additionally, for the training and evaluation of the deep learning model, we collected data by varying the signal transmission and reception location for a total of 11 objects. We show that the deep learning model demonstrates outstanding performance in detecting objects in the NLOS area using acoustic signals. We observed that the performance decreases as the distance between the signal collection location and the reflecting wall, and the performance improves through the combination of signals collected from multiple locations. Finally, we propose the optimal conditions for detecting objects in the NLOS area using acoustic signals.

• Journal of The Korean Association For Science Education
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• v.43 no.3
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• pp.253-263
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• 2023

This study explored the discrepancy between the text of a teacher's guide about straight and reflective light and the content knowledge of pre-service elementary teachers. A total of 455 questions and 543 answers generated by 279 pre-service elementary teachers after reading a 'Shadow and Mirror' unit in the teacher's guide were analyzed. The questions were classified according to the types of concepts and discrepancies, and the answers were analyzed for accuracy. The results of analyzing the concepts of questions revealed that the pre-service elementary teachers were most curious about the shadow in the straight concept, the mirror image in the reflection concept, and the light source in other concepts. The questions with a low correct answer rate due to incorrect- or non-answers, such as those concerning the superposition principle of light by reflection, the principle of experimental tools, and images by lenses, were only partially or not included in the teacher's guide. When the questions were classified according to the type of discrepancy, the frequency of questions due to knowledge deficit was higher than that due to knowledge clash. This demonstrates that the concepts that teachers need to know must be supplemented with the contents of the teacher's guide. Discrepancies due to knowledge clashes are often caused by conflicts between what is experienced in everyday life and what is presented in textbooks. Therefore, it is necessary to reduce the discrepancy between the texts of the teacher's guide and the knowledge of pre-service elementary teachers by including the differences between the actual context of everyday life and the context of the textbook in the teacher's guide.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.120-120
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• 2009

스테인리스강은 내식성이 우수하여 열교환기, 화학플랜트 등 부식환경의 구조물 혹은 파이프에 널리 사용되고 있다. 스테인리스 파이프 제조에 사용되는 용접방법은 주로 GTA 용접이 적용되고 있는데, 이 방법은 용접부 품질은 우수하지만 용접 생산성이 늦은 단점이 있다. 또한 이상스테인리스 등과 같은 특수한 용도의 스테인리스 강은 기존의 용접으로는 용접부 성능 확보가 어렵다. 레이저는 고밀도로 집속되고 직진성이 우수한 일종의 빛으로 용접/절단 등 금속 혹은 비금속의 가공에 널리 사용되고 있다. 레이저 용접의 장점은 비접촉으로 용접이 가능하고, 용접 속도가 매우 빠르고, 용접이 가능한 소재의 종류 혹은 두께의 제약이 적고, 용접부가 작아 변형이 적다는 것이다. 이러한 장점으로 인하여 자동차산업에 적용이 급격히 증가하였으며, 최근에는 다양한 분야에 적용이 추진되고 있다. 본 발표에서는 스테인리스강의 파이프 제조 공정에 레이저용접을 적용하기 위한 기초 연구를 수행하였다. 사용된 소재는 오스테나이트계 및 이상스테인리스강이었으며, 용입특성, 용접부 기계적 특성 등을 알아 보았으며, 열처리에 따른 특성 변화를 평가하였다.

• Journal of Gifted/Talented Education
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• v.22 no.1
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• pp.117-139
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• 2012

This study compared the cognitive conflict on peer instruction concerning the level of difficulty in question, between middle school science gifted students and non-gifted students. For the study, 35 the 7th grade science-gifted students in the organization affiliated with Science Education Institute for the Gifted in Seoul and Gyeong-gi province, and 14 the 8th grade science-gifted students, and 71 the 8th grade students. They performed peer instruction on propagation of straight light and composition of light and then, discussed three concept problems. After discussing the students took paper pencil test about changing levels of cognitive conflict. Regardless of the level of difficulty in question, the science-gifted students showed meaningful decreased figures on cognitive re-evaluation factors after peer-discussion. They trusted their peers, so during discussion, they explained their concepts. Furthermore discussion process enabled them to do reflective thinking. consequently, discord of students dropped, and total figures of cognitive conflict also declined. Science-gifted students have a tendency to worry lower than general students, though they felt anxiety as difficulty of the problems after peer-discussion. Through peer-discussion, science-gifted students presented statically decreased anxiety factors. By means of analyzed results of changing cognitive conflict of science-gifted students, developing and adapting strategies of cognitive conflict considering learner characteristics of science-gifted students is needed.

• Journal of Science Education
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• v.36 no.1
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• pp.84-93
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• 2012

We have studied possibilities of Peer Instruction(PI) to train in-service science teachers in elementary and middle schools through both degree of conceptual changes and investigating responses to questionaries. 169 teachers were attended and the subject for training was about light propagation to teach scientific conception about a pin hole camera. 6 conceptests were developed. Degree of conceptual changes was analyzed from results obtained from 24 elementary and 32 middle school teachers among them. On the other hand, answers to questionaries were obtained from 135. Relatively high gain near to about 0.7 in conceptual changes was obtained even though their initial levels were quite low. Interesting point is that elementary teachers have higher initial level and larger gain than middle school teachers. Teachers have very much enjoyed and showed strong support to PI for helping conceptual change, and willing to use PI to their own class. Also they conceived dealing concept in teacher training is very important and evaluated PI very positively for teacher training.

• Journal of The Korean Association For Science Education
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• v.33 no.2
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• pp.229-248
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• 2013

The purpose of this study is to develop sequential concept tests (ConcepTest) for teachers' conceptual change on the straight propagation of light through in-service training of science teachers by peer instruction. We revised the ConcepTests for attaining the goal concept by implementing similar training courses for teachers three times and analyzing the results using both Hake gain and verbal protocol. The final form helped most teachers to reach the goal concept. While teachers are solving a given concept problem test, they had shown not only significant cognitive conflict to select one among candidate answers, but also used the concept obtained through the previous problem. The sequential ConcepTests developed in this study can be useful for training elementary and secondary teachers or pre-service teacher education.