• Title/Summary/Keyword: open-ended probe

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An Investigation of Elementary School Teachers' Epistemological Beliefs about Science on the Bases of Their Strategies for Coping with Critical Incidents (위기 상황에의 대처 전략을 통한 초등교사들의 과학에 대한 인식론적 신념 연구)

  • Han, Su-Jin;Lee, In-Hye;Kang, Suk-Jin;Noh, Tae-Hee
    • Journal of Korean Elementary Science Education
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    • v.30 no.1
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    • pp.61-70
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    • 2011
  • In this study, we examined the types and the characteristics of elementary school teachers' strategies for coping with critical incidents in science classes. Teachers' epistemological beliefs about science were then investigated on the bases of the types of their coping strategies. The teachers (N=107) in 23 elementary schools were asked to respond to an open-ended question about the critical incidents they had experienced in science classes and how to cope with them. Seven types of coping strategies were identified as follows: avoiding, reinterpretation, adjusting, prevaricating, justifying, exploring, and explaining. Among them, adjusting and justifying were the major strategies. In order to classify teachers' epistemological beliefs about science, their coping strategies were grouped into four categories such as transferring facts, constructing facts, transferring meanings, and constructing meanings. The results indicated that most teachers still possessed traditional epistemological beliefs about science. The potential of critical incidents as a probe for revealing teachers' epistemological beliefs about science is discussed.

Conversion of Permittivity of PCB Substrate Using Moment Method (모멘트 방법을 사용한 PCB 기판의 유전율 환산)

  • Jung Ji-Hyun;Jo Yu-Sun;Kim Se-Yun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.2 s.93
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    • pp.222-227
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    • 2005
  • The permittivity profile of PCB substrate in a wide bandwidth is obtained by applying the moment method to the reflection coefficients measured by an open-ended coaxial probe. In this paper, the relation between a reflection coefficients and the corresponding permittivity is expressed into an integral form and the reflection coefficient of PCB substrates with different thickness are calculated using the dispersive FDTD method. The simulation results assure the validity of our conversion procedure within $2.015\%$ error.

An automated measurement system for the microwave surface resistance of high-T$_c$ superconductor films

  • Lee, J.H.;Lim, J.;Lee, Jung-Hun;Lee, Sang-Young
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.173-178
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    • 2000
  • A prototype for a highly sensitive, automated measurement system for the microwave surface resistance of high-T$_c$ superconductor films was set up, and tested by measuring the microwave surface resistances of high-T$_c$ YBa$_2$Cu$_3$O$_{7-{\delta}}$(YBCO) films at the frequency of about 19.6 GHz and the temperature of 30 K ${\sim}$ 90 K. An open-ended TE$_{011}$ mode sapphire-loaded cylindrical cavity resonator was used as the measurement probe, where YBCO films were used as the endplates of the cylindrical cavity. The characteristics of the measurement system include functions to display the unloaded ${\varrho}$ and the resonant frequency of the TE$_{011}$ mode resonator as well as the microwave surface resistance of the YBCO films, all simultaneously as a function of temperature. Applicability of the measurement system for investigating the homogeneity in the microwave properties of large high-T$_c$ superconductor films is discussed.

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An Automated Measurement System for the Microwave Surface Resistance of High-$T_c$ Superconductor Films

  • Lee, J.H.;Lim, J.;Lee, Jung-Hun;Lee, Sang-Young
    • Progress in Superconductivity
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    • v.2 no.1
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    • pp.27-32
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    • 2000
  • A prototype for a highly sensitive, automated measurement system for the microwave surface resistance of high-$T_c$ superconductor films was set up, and tested by measuring the microwave surface resistances of high-$T_c$ $YBa_2Cu_3O_{7-\delta}$ (YBCO) films at the frequency of about 19.6 GHz and the temperature of 30 K $\sim$ 90 K. An open-ended $TE_{011}$ mode sapphire-loaded cylindrical cavity resonator was used as the measurement probe, where YBCO films were used as the endplates of the cylindrical cavity. The characteristics of the measurement system include functions to display the unloaded Q and the resonant frequency of the $TE_{011}$ mode resonator as well as the microwave surface resistance of the YBCO films, all simultaneously as a function of temperature. Applicability of the measurement system for investigating the homogeneity in the microwave properties of large high-$T_c$ superconductor films is discussed.

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Revalidation of the Complex Trial Protocol using participant-oriented countermeasures (설문 기반 대응방안을 사용한 복합시행 프로토콜의 재평가)

  • Kim, Hyemin;Song, Inuk;Chang, Eunhee;Kim, Hyun Taek
    • Korean Journal of Forensic Psychology
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    • v.11 no.1
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    • pp.89-115
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    • 2020
  • Traditional deception detection methods had examined the difference of one's autonomic physiological responses through asking crime-related and crime-unrelated questions. There has been a continuing controversy regarding the accuracy and validity of the test, and thus, many researchers were motivated to explore and develop alternative efficient methods of detection in which one of them is known as P300-based Complex Trial Protocol (CTP). The P300-based CTP detects deception through comparing the P300 amplitudes between probe and irrelevant stimuli and is known as a counterstrategy of countermeasures. However, many previous studies have used countermeasures created from Rosenfeld et al.'s work (2008). The present study initially conducted a survey asking open-ended questions about the countermeasure use to acquire participant-oriented countermeasures for the main experiment. Then, the study aimed to evaluate whether the CTP can accurately detect deception even in the use of survey-based countermeasures. We firstly selected a set of participant-oriented countermeasures through survey questions. Then, a total of 50 participants were divided into three groups (innocent, guilty, and countermeasures) and performed the CTP. Those assigned to the countermeasures group covertly performed mental countermeasures during the CTP. The results of P300 amplitude analysis revealed that the guilty group's P300 amplitude of probe stimuli was significantly larger than that of irrelevant stimuli. Countermeasures group also had a significantly larger P300 amplitude for probe stimuli compared to irrelevant stimuli, even in the use of countermeasures. The results of bootstrapped amplitude difference (BAD) showed a detection accuracy rate of 81.25%, 82.35%, 82.35% for the innocent, guilty, and countermeasures groups, respectively. These findings demonstrate that the CTP can obtain a high detection rate in participant-oriented countermeasures and suggest the potential use of the CTP in the field.

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Relationships between dielectric properties and characteristics of impregnated and activated samples of potassium carbonate-and sodium hydroxide-modified palm kernel shell for microwave- assisted activation

  • Alias, Norulaina;Zaini, Muhammad Abbas Ahmad;Kamaruddin, Mohd Johari
    • Carbon letters
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    • v.24
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    • pp.62-72
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    • 2017
  • The aim of this work was to evaluate the dielectric properties of impregnated and activated palm kernel shells (PKSs) samples using two activating agents, potassium carbonate ($K_2CO_3$) and sodium hydroxide (NaOH), at three impregnation ratios. The materials were characterized by moisture content, carbon content, ash content, thermal profile and functional groups. The dielectric properties were examined using an open-ended coaxial probe method at various microwave frequencies (1-6 GHz) and temperatures (25, 35, and $45^{\circ}C$). The results show that the dielectric properties varied with frequency, temperature, moisture content, carbon content and mass ratio of the ionic solids. PKSK1.75 (PKS impregnated with $K_2CO_3$ at a mass ratio of 1.75) and PKSN1.5 (PKS impregnated with NaOH at a mass ratio of 1.5) exhibited a high loss tangent ($tan{\delta}$) indicating the effectiveness of these materials to be heated by microwaves. $K_2CO_3$ and NaOH can act as a microwave absorber to enhance the efficiency of microwave heating for low loss PKSs. Materials with a high moisture content exhibit a high loss tangent but low penetration depth. The interplay of multiple operating frequencies is suggested to promote better microwave heating by considering the changes in the materials characteristics.

Noninvasive Method to Distinguish between Glucose and Sodium Chloride Solution Using Complementary Split-Ring Resonator (Complementary Split Ring Resonator(CSRR)를 이용한 포도당과 염화나트륨 수용액의 비침습적 구별)

  • Jang, Chorom;Park, Jin-Kwan;Yun, Gi-Ho;Yook, Jong-Gwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.4
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    • pp.247-255
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    • 2018
  • In this work, glucose solution and sodium chloride solution were distinguished noninvasively using a microwave complementary split-ring resonator (CSRR). Based on the electrical properties of the two solutions measured using a open-ended coaxial probe, a CSRR was designed and fabricated for operation at a specific frequency that facilitates differentiating the two solutions. Furthermore, a polydimethylsiloxane mold was fabricated to concentrate the solution at a region where the electric field of the resonator was strongest, and a laminating film was used to prevent contact between the solution and resonator. Experiments were performed by dropping $50{\mu}L$ of the solution in steps of 100 mg/dL up to a maximum human blood glucose level of 400 mg/dL. Our experiments confirmed that the transmission coefficients ($S_{21}$) of glucose solution and sodium chloride solution exhibit variations of -0.06 dB and 0.14 dB, respectively, per 100 mg/dL concentration change at the resonance frequency. Thus, the opposite trends in the variation of $S_{21}$ with change in the concentration of the two solutions can be used to distinguish between them.

An Investigation into the Secondary Science Teachers' Perception on Scientific Models and Modeling (과학적 모델과 모델링에 대한 중등 과학 교사의 인식 탐색)

  • Cho, Eunjin;Kim, Chan-jong;Choe, Seung-urn
    • Journal of The Korean Association For Science Education
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    • v.37 no.5
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    • pp.859-877
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    • 2017
  • The purpose of this study is to probe secondary science teachers' perception on scientific models and modeling. A total of 50 experienced science teachers were surveyed with 10 open-ended questions about several aspects of models and modeling: definition, examples, purpose, multiplicity, changeability, design/construction, evaluation and beliefs in the use of models and modeling as a teaching tool. The analysis of the data shows the following results: 1) understanding of models and modeling held by a majority of experienced secondary science teachers was far from that of experts as they concentrated on a model's superficial, representative, and visual functions, 2) when it comes to their view toward the use of a model, a model does not remain in the stage of 'doing science' but in the stage of being a subsidiary teaching tool for the teacher's explaining and the students' understanding of scientific concepts, 3) the subjects they majored in made meaningful differences in their contextual understanding of models and modeling, 4) though most of the teachers acknowledged the importance of teaching about models and modeling, even a lot of them showed a negative position toward the opinion that they are willing to apply modeling to their classes. Implications of the results were discussed in terms of intervention in order to enhance secondary science teachers' understanding and pedagogical content knowledge of models and modeling.