• Journal of the Korea Computer Graphics Society
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• v.17 no.3
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• pp.21-31
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• 2011

This paper presents a practical method to estimate the directions of light sources in real environment, using a mirror sphere placed on a set of known natural features in augmented reality. For the stable result of static lighting, we take the multiple images around the sphere and estimate the principal light directions of the vector clusters for each light source in realtime. We also estimate the moving illuminant for changes of the scene illumination, and augment the virtual objects onto the real image with the proper highlighting and shadows. The proposed method of this paper can be applied to augmented reality visualization without any previous information respecting the environmental illuminations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.995-998
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• 2005

This paper proposes a new SoC (System-on-Chip)-based automatic compensation circuit (ACC) for 5GHz low noise amplifier (LNA). This circuit is extremely useful for today's RF IC (Radio Frequency Integrated Circuit) devices in a complete RF transceiver environment. The circuit contains RF BIST (Built-ln Self-Test) circuit, Capacitor Mirror Banks (CMB) and digital processing unit (DPU). The ACC automatically adjusts performance of 5GHz LNA by the processor in the SoC transceiver when the LNA goes out of the normal range of operation.

• Journal of Surface Science and Engineering
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• v.46 no.5
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• pp.197-207
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• 2013

In the midst of increasing importance of modern cultural assets, especially, most modern bronze objects are exposed to outdoor environment, and as the objects are corroded steadily due to environmental factors the objects lost their original colors on the surface. We performed artificial patinas on the bronze sample per each color of red, black and green and checked cuprite and tenorite which are detected from actual bronze corrosion by analyzing the components. In addition, we applied the existing corrosion removal methods of grinder and sand blaster on a similar sample of bronze mirror per injection pressure and performed comparative analysis on the result with Nd:YAG laser. As a result of Nd:YAG laser cleaning artificial patina from bronze samples, all of the patinas were removed by laser wavelength 1064 nm better than 532 nm. Upon applying to a similar sample of bronze mirror, the artificial patina could be selectively removed from substrates without surface damage when Nd:YAG laser was conducted other than the existing removal method, and so it showed the possibility of application.

• The Journal of Korean Medicine
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• v.43 no.4
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• pp.74-88
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• 2022

Objectives: The purpose of this study is to design Korean-themed online public education content in Korean medicine using rapid prototyping instructional systems design (RPISD). This study presents cases of developing and converting face-to-face general education programs designed to increase the interest in and understanding of Korean medicine for the public into online programs within a short timeframe. Methods: This qualitative study is design and development research, which used the RPISD model to analyze the available resources utilized in the rapid development of public educational content and propose systematization and optimization measures by analyzing the needs of clients, learners, and the environment. The <Treasured Mirror of Eastern Medicine(DUBG)Open Course> was developed according to the model procedure, which involved needs analysis, development of course materials and manuscript, and storyboard creation and its filming and editing. Usability tests were conducted at all stages, and the opinions of clients, instructors, experts, and instructional designers were accommodated and reflected at each stage. Results: Using the rapid prototyping model, <Treasured Mirror of Eastern Medicine(DUBG)Open Course> was organized into five classes of 20 minutes each. Each class was developed in Korean and included English, Chinese, and Japanese subtitles in addition to Korean under the cooperative instructional design among clients, subject-matter experts, instructional designer and learners. Conclusion: The cooperative instructional design of stakeholders is significant in developing Korean medicine public education content online through extensive interaction and feedback from stakeholders in the early stage of educational content development.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.2
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• pp.59-66
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• 2005

Accuracy of current measurement in fiber optic current sensor(FOCS), especially, unidirectional polarimetric fiber optic current sensor(PFOCS) is affected by the environment perturbations such as acoustic vibrations changes to the sensing fiber, and intrinsic perturbations such as the bending fiber that the sensing fiber wound around a current carrying wire. The perturbations affect the birefringence properties of sensing fiber in sensor head and cause false current readings. Thus, using compensation technique, reciprocal PFOCS, for unidirectional PFOCS the perturbations are suppressed. In this paper, we carried out the numerical analysis of performance in reciprocal PFOCS including the degree of polarization error, and false current of environmental and intrinsic perturbations on the sensing fiber. Also, we compared the effect of mirror with the faraday rotation mirror(FRM) in reciprocal PFOCS configuration. And the different optical source's wavelengths, 633nm and 1300nm is used. In the results, at 633nm, using mirror and FRM, the degree of polarization error is calculated to $2.3\%$ and $0.0196\%$, respectively. At $1300{\cal}nm$ using mirror and FRM the degree of polarization error is calculated to $9.97\%$ and $0.0196\%$, respectively. Also, compared with false current, the results is calculated to $9.82{\times}10^{-9}A$ and $1.4{\times}10^{-17}A$, respectively, and show that the reciprocal PFOCS is more robust configuration than unidiretionnal PFOCS for environmental and intrinsic perturbations.

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.167-174
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• 2016

Underwater communication is difficult to increase the communication capacity because the carrier frequency is lower than that of radio communications on land. This is limited to the bandwidth of the signal under the influence of the characteristics of an ocean medium. As the high transmission speed and large transmission capacity have become necessary in the limited frequency range, the studies on MIMO (Multiple Input Multiple Output) communication have been actively carried out. The performance of the MIMO communication is lower than that of the SIMO (Single Input Multiple Output) communication because cross-talk occurs due to multiusers along with inter symbol interference resulting from the channel characteristics such as delay spread and doppler spread. Although the adaptive equalizer considering multi-channels is used to mitigate the influence of the cross-talk, the algorithm is normally complicated. In this paper, time reversal mirror technique with the characteristic of a self-equalization will be applied to simplify the compensation algorithm and relieve the cross-talk in order to improve the communication performance when the signal transmitted from two channels is received over interference on one channel in the same time. In addition, the performance of the MIMO communication based on the time reversal mirror is verified using data from the SAVEX15(Shallow-water Acoustic Variability Experiment 2015) conducted at the northern area of East China Sea in May 2015.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.408-409
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• 2006

The polycrystalline 3C-SiC thin films heteroepitaxially grown by LPCVD method using single precursor 1. 3-disilabutane at $850^{\circ}C$. The crystallinity of the 3C-SiC thin film. was analyzed by XPS. Residual strain was investigated by Raman scattering. The surface morphology and voids between SiC and $SiO_2$ were measured by SEM. The grown poly 3C-SiC thin film is very good crystalline quality, surface like mirror, and low defect and strain. Therefore, the polycrystalline 3C-SiC is suitable for harsh environment MEMS applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.191-194
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• 2002

In optical pick-up, optical components such as objective lens, collimator, mirror, laser diode and photo diode are mounted on the pick-up base. These components must keep their original position during operation for proper transmittance of information from laser diode to optical disk and back to photo diode. However, micro thermal deformation of pick-up base which is induced by thermal environment during operation can deteriorate the performance of optical pick-up. Therefore, it is important to measure and analyze the thermal deformation behavior of pick-up base under thermal environment. In the present study, a measurement system using holographic interferometry was designed to measure micro thermal deformation of pick up base. The measurement system was verified by using the deformation of cantilever with prescribed motion actuated by PZT with 1 nm resolution. Interferometric measurement was compared quantitatively with that induced by PZT actuator. Finally, micro thermal deformation of pick-up base under actual thermal environment was measured using the present holographic interferometry and the results were analysed.

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.484-493
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• 2001

As real-time database systems are extended to the distributed computing environment, the need to apply the existing real-time concurrency control schemes to the distributed computing environment has been made. In this paper we propose an efficient concurrency control scheme for distributed real-time database system. Our proposed scheme guarantees a transaction to commit at its maximum, reduces the restart of a transaction that is on the prepared commit phase, and minimizes the time of the lock holding. This is because it raises the priority of the transaction that is on the prepared commit phase in the distributed real-time computing environment. In addition, it reduces the waiting time of a transaction that owns borrowed data and improves the performance of the system, as a result of lending the data that the transaction with the raised priority holds. We compare the proposed scheme with DO2PL_PA(Distributed Optimistic Two-Phase Locking) and MIRROR(Managing Isolation in Replicated Real-time Object Repositories) protocol in terms of the arrival rate of transactions, the size of transactions, the write probability of transactions, and the replication degree of data in a firm-deadline real-time database system based on two-phase commit protocol. It is shown through the performance evaluation that our scheme outperforms the existing schemes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.952-958
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• 2011

On-board IR calibration device has been developed for calibration of spaceborne image sensor. It is composed of a blackbody to provide two different radiance temperatures, tilt mirror with a function of stow and deploy to view the blackbody during the calibration and on-board calibration control unit to control the function of the blackbody and tilt mirror. In this paper, to guarantee the structural safety of the unit, the structural and thermal analysis including a thermo-elastic analysis for verifying structural safety on the soldered part of chips have been performed. In addition, safety margin of the chips on the PCB obtained from the conventional analytical method has been compared to the results from the FEM analysis.