• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.657-662
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• 2018

In this study, the effect of $Pt/TiO_2$ catalysts on the CO oxidation reaction at room temperature was investigated using various $TiO_2$ supports with different physical properties to compare and evaluate $Pt/TiO_2$ catalysts. Physicochemical properties of the catalyst were alanyzed using XPS, CO-chemisorption, BET, and CO-TPD. As a result, when the active particle diameter was smaller, while the metal dispersion and surface area were larger, the CO room temperature oxidation reaction was better. These physical properties increased the number of active sites, causing the target material to increase the adsorption amount of CO. In addition, when the $O_2$-consumption increased, the CO-room temperature oxidation reaction activity increased due to the excellent oxygen-transferring ability.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.2
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• pp.180-187
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• 2021

This study was conducted to investigate the reproductive characteristics of the Neon damselfish Pomacentrus coelestis in Chuuk lagoon (7°27' N, 151°53' E), Micronesia, Equatorial Pacific Ocean. The specimens used in this study were collected from August 2009 to September 2010 from around the coral reef area at a depth of 3-10 m in the northwest coast of Weno Island. Overall, 228 individuals were collected over 14 months from this area, of which 115 were females and 108 were males. Among 108 males, 30 were found to be hermaphrodites and the sex of 5 individuals could not be determined. The overall sex ratio was approximately 1.06:1 (female:male), and the ratio of sexually active individuals was 0.79:1. The gonadosomatic index (GSI) fluctuated and showed the highest value of 8.43±1.21 in December 2009 and the lowest value of 3.36±0.71 in September 2009 in sexually active females. Males showed the highest GSI value of 2.64±0.93 in June 2010 and the lowest value of 0.35±0.06 in July 2010. Based on the fluctuation of GSI, the trends in the appearance of monthly sexually active individuals, and biopsy of the gonads, P. coelestis was found to be a hermaphrodite species of protogynous type and is considered to be reproductively active throughout the year.

• Journal of the Korea Society of Computer and Information
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• v.18 no.4
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• pp.45-55
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• 2013

In this study, we propose a tongue diagnosis system which detects the tongue from face image and divides the tongue area into six areas, and finally generates tongue fur ratio of each area. To detect the tongue area from face image, we use ASM as one of the active shape models. Detected tongue area is divided into six areas and the distribution of tongue coating of six areas is examined by SVM. For SVM, we use a 3-dimensional vector calculated by PCA from a 12-dimensional vector consisting of RGB, HSV, Lab, and Luv. As a result, we stably detected the tongue area using ASM. Furthermore, we recognized that PCA and SVM helped to raise the ratio of tongue coating detection.

• Smart Structures and Systems
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• v.29 no.3
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• pp.499-512
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• 2022

This work proposes a novel contactless vibration damping and thermal isolation tripod platform based on Superconducting Magnetic Levitation (SML). This prototype is suitable for cryogenic environments, where classical passive, semi active and active vibration isolation techniques may present tribological problems due to the low temperatures and/or cannot guarantee an enough thermal isolation. The levitating platform consists of a Superconducting Magnetic Levitation (SML) with inherent passive static stabilization. In addition, the use of Operational Modal Analysis (OMA) technique is proposed to characterize the transmissibility function from the baseplate to the platform. The OMA is based on the Stochastic Subspace Identification (SSI) by using the Expectation Maximization (EM) algorithm. This paper contributes to the use of SSI-EM for SML applications by proposing a step-by-step experimental methodology to process the measured data, which are obtained with different unknown excitations: ambient excitation and impulse excitation. Thus, the performance of SSI-EM for SML applications can be improved, providing a good estimation of the natural frequency and damping ratio without any controlled excitation, which is the main obstacle to use an experimental modal analysis in cryogenic environments. The dynamic response of the 510 g levitating platform has been characterized by means of OMA in a cryogenic, 77 K, and high vacuum, 1E-5 mbar, environment. The measured vertical and radial stiffness are 9872.4 N/m and 21329 N/m, respectively, whilst the measured vertical and radial damping values are 0.5278 Nm/s and 0.8938 Nm/s. The first natural frequency in vertical direction has been identified to be 27.39 Hz, whilst a value of 40.26 Hz was identified for the radial direction. The determined damping values for both modes are 0.46% and 0.53%, respectively.

• ETRI Journal
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• v.27 no.2
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• pp.166-171
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• 2005

In this paper, a synthesis technique for nonuniform filtering structures to be employed in active integrated antenna layouts is presented. The idea is to suppress the higher harmonic contribution due to the presence of nonlinear components through a nonuniform transmission line properly designed via Orlov's synthesis formula. The theory presented is applied here to synthesize an amplifier-based active antenna layout for wireless local area network (WLAN) purposes working at 2.4 GHz. The numerical results presented show the capabilities of the proposed approach.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.42-46
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• 2003

In this paper, an MMIC broadband amplifier for wireless communication systems has been developed by using an active feedback method. This active feedback operates at much higher frequencies than a method by a spiral inductor feedback and its size is independent of the inductance value. The MMIC broadband amplifier was designed using a $0.5{\;}{\mutextrm{m}}$ MESFET library. The fabricated chip area was $1.4{\;}mm{\;}{\times}{\;}1.4{\;}mm. Measurement showed a gain of 18 dB with a gain flatness of ${\pm}3$ dB in a 1.5 GHz~3.5 GHz band. The maximum output power and the minimum noise figure were 14 dBm and 2.5 dB in the same band, respectively.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.197-201
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• 2000

In this paper, a MMIC(Monolithic Microwave Integrated Circuit) broadband drive amplifier for wireless communication system has designed using active feedback method. The MMIC brodband amplifier was designed using 0.5$\mu\textrm{m}$ MESFET of ETRI library. Simulation results show that gain is 22 dB, and gain flatness ${\pm}$1 dB. Maximum output power 15 dBm and noise figure 2.5 dB in bandwidth 500 MHz ～3.0 GHz. The MMIC Broadband amplifer's chip area is 14mm${\times}$1.4mm.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.241-246
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• 1996

An analytical model to calculate rate of vapor generation due to heterogeneous wall nucleation in flashing flow is developed. In the present model, an important parameter of the vapor generation term, i.e. nucleation site density is calculated by integrating its probability distribution function with respect to active cavity radius. The limits of integration are minimum and maximum active cavity radii, and these are formulated using an active cavity model for nucleate boiling. This formulation, therefore. can statistically account for the effect of surface specific thermo-physical and geometric conditions on the vapor generation rate and flashing inception. For verifying the adequacy of the present model, steady state two-fluid and the bubble transport equations are solved with applicable constitutive equations. The applicable region of the bubble transport equation is also extended to churn-turbulent flow regime to predict interfacial area concentration at high void fraction. Predicted results in terms of axial pressure and void fraction profiles along the channels are compared with experimental data of Super Moby Dick and BNL Reasonable agreements have been achieved and this shows the applicability of the present model to flashing flow analysis.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.111-111
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• 2000

The research of network system, being used to reduce automotive wiring harness, is reaching to the development of by-wire system. It is by-wire system that apply IVN(In-Vehicle-Network) to steering, braking system, and it has the advantage of mass-decreasing, easy to diagnose fault and so on. But until now, many developed device can't satisfied with reliability that system have ever had. So redundancy of each network module, i.e., It is only way to make backup module. This paper researches development of network module and redundancy management of backup module when error occurred for implementation of brake-by-wire system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.625-629
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• 2014

In this paper, a tile projector for the active control of low-frequency underwater echoes is studied using finite element method. Compared to the existing underwater actuators used for echo reduction, the tile projector is better suited for covering a wide area such as the hull of a submarine. In order to actively match the acoustic impedance at the water-object interface, the projector is driven to radiate a pressure wave that is the inverted replica of the echo at the interface. Finite element simulations demonstrate significant echo reductions due to the active impedance matching by the tile projector.