• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.394-396
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• 2007

Radio occultation (RO) technique has been used in planetary science since 1960s. When signal goes through atmosphere, it is refracted due to the gradient of atmospheric refractivity. In 1995, the first low earth orbit (LEO) satellite, MicroLab-1, was launched to conduct RO mission. It receives the signal from global positioning system (GPS) satellites. After MicroLab-1, other RO missions, such as CHAMP, SAC-C, and GRACE, are executed in several years later. In 2006, Taiwan launched six LEO satellites for RO mission. The mission name is Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC). Under some abnormal situations, multipath and strong fluctuation in phase and amplitude of the signal appear in moist troposphere. Therefore, open loop (OL) technique has been applied to replace traditional phase lock loop (PLL) technique. In this paper, we will summarize the retrieval processing procedure and discuss the advantages and disadvantages of OL technique.

• Wind and Structures
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• 제30권1호
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• pp.37-54
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• 2020

To investigate the motion-induced aeroelastic effects (or aerodynamic feedback effects) on a square cylinder in uniform flow, a series of wind tunnel tests involving the pressure measurement of a rigid model (RM) and simultaneous measurement of the pressure and vibration of an aeroelastic model (AM) have been systematically carried out. More specifically, the aerodynamic feedback effects on the structural responses, on the mean and root-mean-square wind pressures, on the power spectra and coherence functions of wind pressures at selected locations, and on the aerodynamic forces were investigated. The results indicated the vibration in the lock-in range made the shedding vortex more coherent and better organized, and hence presented unfavorable wind-induced effects on the structure. Whereas the vibration in the non-lock-in range generally showed insignificant effects on the flow structures surrounding the square cylinder.

• 한국해양공학회지
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• 제7권1호
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• pp.114-123
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• 1993

In is well known that a cyclic Karman vortex street is thrown out periodically from cylinder whose axis is vertical to the bulk flow. When the cylinder is vibrating in the frequency close to that of Karman vortex street, the vortex shedding frequency is locked onto that of cylinder. While there are many experimental studies for this phenomenon compared with analytical studies by numerical calculation, are very limited. In this study, a new algorithm for moving boundary is proposed and a simulator is develoed, which can deal with this phenomenon with experimental studies.

• 한국세라믹학회지
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• 제56권3호
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• pp.277-283
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• 2019

We have examined minimization of the number of impurity particles by replacing the load-lock chamber materials of the chemical vapor deposition equipment through optimization of the pumping method in the deposition chamber. In order to reduce the number of impurity particles in the chamber, the load-lock spacer material was changed from monomer casting nylon to Torlon. Furthermore, we controlled the pumping speed and number of pumping ports, which resulted in a reduction in the impurity particle generation from 2.67% to 0.52%. This study revealed that the selection of the material for the parts of a chemical vapor deposition chamber can minimize particle generation, thereby presenting a method of optimization method of the chemical vapor deposition chamber.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.548-553
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• 2011

The lock-in thermography was employed to evaluate the defects in railway bogies. Prior to the actual application on railway bogies, in order to assess the detectability of known flaws, the calibration reference panel was prepared with various dimensions of artificial flaws. The panel was composed of polymer matrix composites, which were the same material with actual bogies. Through lock-in thermography evaluation, the optimal frequency of heat source was determined for the best flaw detection. Based on the defects information, the actual defect assessments on railway bogie were conducted with different types of railway bogies, which were used for the current operation. In summary, it was found that the novel infrared thermography technique could be an effective way for the inspection and the detection of surface defects on bogies since the infrared thermography method provided rapid and non-contact investigation of railway bogies.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.368-370
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• 2005

Superconducting fault current limiter (SFCL) provides the effect such as enhancement in power system reliability due to limiting fault current in a few miliseconds. The flux-lock type SFCL among various type SFCLs consists of two coils wound on the same iron core and a component using the YBCO thin film. In the SFCL, operation characteristics can be controlled by adjusting the inductances and the winding directions of the coils. In this paper, we investigated the various fault current limiting characteristics according to the voltage level. To analyze the current limiting performance, we compared operational characteristics on the subtractive polarity winding direction on in case of open-loop iron core.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.166.1-166
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• 2001

Anti-lock Braking System(ABS) is a device which prevents the wheels form locked up under emergency braking of a vehicle. So it helps the vehicle to maintain the steerability and shortens the braking distance by maintaining optimal frictional force during braking since the tire road slip is controlled in acceptable range. Recently, ABS is accepted as a standard equipment in vehicles, especially in commercial vehicles(bus and trucks). Commercial vehicles don´t use hydraulic lines but use pneumatic lines for braking system mostly. In this paper, ECU(Electronic Control Unit) for the anti-lock braking system of a commercial vehicle which is equipped with a full-air brake system and its control algorithms are presented. In this algorithm wheel speed acceleration flags and wheel slip flags are defined ...

• 한국정보처리학회논문지
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• 제7권4호
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• pp.1227-1235
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• 2000

In this paper, we propose new concepts that the distributed counter value with the distributed EC system identify each user who users the distributed system. The web user should register his/her own user ID in the cyber shopping mall system. Instead of registration, this paper proposes the proprietary mechanism that is distributing counter. The counter assigns the distinguished number to each client. The distributed lock algorithm is used for mutual assignment of the counter to each client. The proposed algorithm is the best solution in the distributed environment system such as cyber shopping mall. If a user should register his/her own ID in every EC system, he/she may not try to use these uncomfortable systems. The mutual counter is used to identify each client. All of these features are designed and implemented on Windows NT web server. Also these features were experiments with 5 clients for 300 times. According to the experiments, clients have their own mutual counter value. The proposed algorithm will be more efficient in internet application environment. Moreover, it will improve the number of internet users.

• World Technopolis Review
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• 제3권2호
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• pp.66-77
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• 2014

This paper aims at exploring a conceptual framework of analyzing the evolutionary processes of regional economies by reconciling the notion of regional resilience and the concepts prevailing in the disciplines of evolutionary economics and geography. The resilience framework appears to offer a promising outlet with which combination of the seemingly contradictory conceptions is made possible. It can address why some regions manage to adapt to external shocks, renew themselves, or lock out themselves, while others are more locked in decline. In addition, it can also explain how the spatial organization of economic production, distribution, and consumption is transformed over time. Then, regional economic resilience, together with its accompanying vehicle of panarchy, emerges as a workable framework of explaining regional differentiation in regional economic performance and trajectories. Despite the risk of being a fuzzy concept, the resilience conception can be properly operationalized to provide policy principles of regional economic innovation adjusted to region-specific contexts.

• 한국군사과학기술학회지
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• 제17권4호
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• pp.537-543
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• 2014

RLG(Ring Laser Gyroscope) is a main device of LINS(Laser Inertial Navigation System). RLG has the lock-in region in which there is no output signal. To alleviate the lock-in problem, a mechanical oscillation, the dither motion, is applied on RLG. A LPF(Low Pass Filter) is usually used on the output of RLG and accelerometer to remove the noise that is made by the dither motion. When the LINS is induced the disturbance during the initial alignment, it takes more time on alignment due to the use of the LPF and a fixed gain controller. In this paper, an initial alignment using UKF(Unscented Kalman Filter) is designed and analysed. Analysis include comparison between conventional initial alignment loop using fixed gain type controller and proposed initial alignment using UKF. Moreover, Disturbance inducing test results are demonstrated.