• Research in Mathematical Education
• /
• v.7 no.4
• /
• pp.211-222
• /
• 2003

Recursive thinking is iterative, self-referential, and building on itself continuously. Moreover, it is becoming a more prominent feature of the mathematical scope because of the availability of computers and languages like Logo, Excel, and Pascal that support recursion. This study investigates the way to create students' recursive thinking in mathematics classroom and to use various methods to solve problems using a spreadsheet, the Excel program where technology could be accessible.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.477-479
• /
• 2015

By probing nuclear regions and the overall properties of AGN hosts as a function of their environments, we aim to observationally examine how AGN activities are related to their surroundings. We have selected a representative sample of AGN hosts in the Virgo cluster. The selected galaxies are located in a range of density regions showing various morphologies in 1.4 GHz continuum emission. High-resolution observations with the Korean VLBI Network (KVN) allow us to access the inner region of the AGN without suffering from dust extinction and synchrotron self-absorption. Since a number of our targets are too weak to be detected at K-band (22 GHz) within their coherence time, we applied phase referencing to calibrate fast atmospheric phase fluctuations.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.2
• /
• pp.513-522
• /
• 2021

The current research aims to explore which type of identity-based message can be more persuasive for Chinese consumers to form positive restaurant brand attitude based on their cultural orientation, and to examine the roles of brand objective relevance and psychological power state in the persuasive process. The study employs a 2(identity expression focus: warmth vs. competence) × 2(message description manner: identity-defining vs. identity-referencing) × 2(experienced power state: high vs. low) between-subjects design, and conducts an online survey where 240 Chinese participants in total has responded to the questionnaires. SPSS and AMOS programs have been used to examine the hypotheses. The findings suggest that, first, the warmth-focused messages (identity-defining messages) more positively affected Chinese consumers' object relevance than the competence-focused messages (identity-referencing messages); Second, high power-experienced Chinese consumers rather than low power consumers tend to perceive more object relevance at the warmth self-defining messages; Third, brand object relevance revealed a mediation effect in the process of the warmth-focused messages (identity-defining messages) affecting brand attitude. This research offers new insight into the relationships between consumers' cultural orientation, understandings of power, and identity-based consumer behavior, suggesting marketers should take those social influences and consumer diversities into account when developing the message to persuade consumers.

• The Journal of Society for e-Business Studies
• /
• v.17 no.3
• /
• pp.85-103
• /
• 2012

This study focused on user evaluation for personalized recommender systems with the integrated view of performance of the system and user attitude of recommender systems. Since users' evaluations of recommender systems can be affected by recommendation outcomes and presentation methods, both system performances based on outcomes and user attitudes formed by the presentation methods should be considered when explaining users' evaluations. However, an integrated view of system performance and user attitudes has not been applied to explain users' evaluation of recommender systems. Thus, the goal of this study is to explain users' evaluations of recommender systems under the integrated view of predictive features and explanation features at the same time. Our findings suggest that social presence, both accuracy and noveltyhave impacts onuser satisfaction for recommender systems. Especially, predictive features including accuracy and novelty affected user satisfaction. Novelty as well as accuracy is one of the significant factors for user satisfaction while recommender systems provided usual items users have experienced when systems provide serendipitous items. Likewise, explanation features with social presence and self-reference were important for user evaluation of personalized recommender systems. For explanation features, while social presence appears as one of important factors to user satisfaction of evaluating personalized recommendations, self-reference has no significant effect on user's satisfaction for recommender systems when compared to the result of social presence. Self-referencing messages did not affect user satisfaction but the levels of self-referencing are different between low and high groups in the experiment.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.40 no.1
• /
• pp.124-129
• /
• 2003

A novel watermark registration method based on Radon transform for self-referencing watermark is presented. The novel method was successful in registering the watermark of the image that has undergone affine transformations and severe lossy compression, whereas the conventional method based on peak detection failed to register the watermark.

• Proceedings of the Optical Society of Korea Conference
• /
• 2007.07a
• /
• pp.111-112
• /
• 2007

The spatial coherence function of laser beam was measured by using a Sagnac interferometer and self referencing technique. For laser beam passing through a narrow slit, absolute value of measured spatial coherence function becomes more symmetric as the slit size is reduced. For diverging beams, the spatial coherence function shows fast oscillations in its real and imaginary parts. We explain this by using a Gaussian Schell-model. One can use this measurement method to study and characterize the property of light field coming out of small sample.

• Journal of the Optical Society of Korea
• /
• v.3 no.2
• /
• pp.64-68
• /
• 1999

The performance of a fiber Bragg grating strain sensor constructed with 3$\times$3 coupler is investigated. A 3$\times$3 coupler Mach-Zehnder (M/Z) interferometer is used as wavelength discriminator, interrogating strain-induced Bragg wavelength shifts. Two quadrature-phase-shifted intensities are synthesized from the as-coupled interferometer outputs, and digital arctangent demodulation and phase unwrapping algorithm are applied to extract the phase information proportional to strain. Due to the linear relation between the input strain and the output of quadrature signal processing, signal-fading problems eliminated. In the experiment, a fiber grating that was surface adhered on an aluminum beam was strained in different ways, and the photodetector signals were transferred and processed in a computer-controlled processing unit. A phase recovery fo 7.8$\pi$ pk-pk excursion, which corresponds to ~650$\mu$strain pk-pk of applied strain, was demonstrated. The sensor system was stable over the environmental intensi쇼 perturbations because of the self-referencing effect in the demodulation process.

• Proceedings of the Optical Society of Korea Conference
• /
• 2008.07a
• /
• pp.187-189
• /
• 2008

The spatial coherence function of multy-mode beam was measured by using a Sagnac interferometer and self referencing technique. For leaner polarization laser beam passing through a multy-mode fiber, its change value of spatial mode and polarization from stress of faber and input coupling angle. And each spatial mode have each polarizations, when we simulation Wigner distribution function and Spatial Correlation function of spatial multi-mode beam by using Hermit Gaussian modes leaner sum. We measured spatial coherence function of using by multy-mode fiber. One can use this measurement method to study and characterize the property of multy-mode light field coming out of GRIN multy-mode fiber.

• Journal of the Optical Society of Korea
• /
• v.11 no.2
• /
• pp.71-75
• /
• 2007

The spatial coherence function of a laser beam was measured by using a Sagnac interferometer and self referencing technique. For a laser beam passing through a narrow slit, the absolute value of the measured spatial coherence function becomes more symmetric as the slit size is reduced. For diverging beams, the spatial coherence function shows fast oscillations in its real and imaginary parts. We explain this by using a Gaussian Schell-model. One can use this measurement method to study and characterize the property of the light field coming out of a small sample.

• Journal of the Optical Society of Korea
• /
• v.7 no.3
• /
• pp.131-134
• /
• 2003

We demonstrated an optical frequency synthesizer based on a femtosecond (fs) mode-locked Ti:sapphire (Ti:s) laser by simultaneously stabilizing the carrier-offset frequency, $f_{ceo}$, and repetition rate, $f_{ rep}$, referenced to the Cs atomic frequency standard. By using two wide-band digital phase-detectors we realized a phase-coherent link between $f_{rep} and f_{ceo} with the relation f_{ceo} = f_{AOM} 5/6f_{rep} ≡ 0, where f_{AOM} = 5/6f_{rep}$ is the phase-locked driving frequency of an acousto-optic modulator (AOM) in a self-referencing interferometer and $f_{rep}$ = 100 MHz. As a result, we could stabilize all components of the fs laser comb at once with an equal frequency separation $f_{rep}$ = 100 MHz with $f_{ceo}$ = 0. In our optical frequency synthesizer, the frequency of the nth component ($f_{n}$) is given exactly by the simple relation $f_n = nf_{rep}$, enabling us to use the fs laser comb as a frequency ruler in the optical frequency metrology.