• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.71-80
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• 2013

According to design specifications for structural safety, a bridge in initial design step has been modelled to have larger self-weight, external loads and less stiffness than those of real one in service. Thereby measured buffeting responses of existing bridge show different distributions from those of the design model in design step. In order to obtain accurate buffeting responses of the in-site bridge, the analysis model needs to be modified by considering the measured natural frequencies. Until now, a Manual Tuning Method (MTM) has been widely used to obtain the Measurement-based Model(MBM) that has equal natural frequencies to the real bridge. However, since state variables can be selected randomly and its result is not apt to converge exact rapidly, MTM takes a lot of effort and elapsed time. This study presents Buffeting Response Correction Method (BRCM) to obtain more exact buffeting response above MTM. The BRCM is based on the idea the commonly used frequency domain buffeting analysis does not need all structural properties except mode shapes, natural frequencies and damping ratio. BRCM is used to improve each modal buffeting responses of the design model by substituting measured natural frequencies. The measured natural frequencies are determined from acceleration time-history in ordinary vibration of the real bridge. As illustrated examples, simple beam is applied to compare the results of BRCM with those of a assumed MBM by numerical simulation. Buffeting responses of BRCM are shown to be appropriate for those of in-site bridge and the difference is less than 3% between the responses of BRCM and MTM. Therefore, BRCM can calculate easily and conveniently the buffeting responses and improve effectively maintenance and management of in-site bridge than MTM.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.697-707
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• 2015

This paper covered the design and implementation of the demodulation receiver in the ADS-B 1090ES system, which is one of the CNS/ATM's surveillance systems. This researched demodulation performed at the level required by RTCA DO-268B and EUROCAE ED-129. The single signal process method, which applies a baseline multi-sample technique among multi-amplitude sample demodulations, was suggested to improve the quality of the receiver signal, the dynamic range and so on. The suggested multi-signal level tuning method has enhanced the single-signal process method, reducing the unstable reception ratio by the transmit output level difference and manufacturing receiver hardware. The result was that the receiver suggested by the method had 0~87dBm in dynamic range and -90dBm in MTL. This shows a better performance by -3dBm less than the international standard in ADS-B 1090ES ground receiver equipment. The systems which use a similar modulation method, will be considered to be widely applied.

• Journal of Energy Engineering
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• v.13 no.2
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• pp.144-151
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• 2004

Stabilization and reduction of combustion noise and NOx emission from dry low NOx combustor of GE MS7001F gas turbine were achieved. Dry low NOx gas turbines that adopt the lean premixed combustion technology frequently generate the flame instability and high NOx emissions if not adequately tuned. Dynamic pressure oscillation during the combustion mode transfer increased as ambient temperature decreased with frequency of 80㎐ and magnitude of 4-9 psi. Effects of both combustor tuning for uniform fuel flow with burner nozzles and fuel pre-filling into transfer fuel valves on stabilisation of the dry low NOx combustor were very significant. Dynamic pressure oscillation during the combustion mode change was decreased up to 2.5 psi. Also, NOx emission from GE7F DLN-1 combustor can be maintained as low as 35-43ppm (15% O$_2$) in base load operation of 150 MW.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.65-73
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• 2007

This paper presents a low power CMOS continuous-time $\Sigma\Delta$ (sigma-delta) modulator for UMTS receivers. The loop filter of the continuous-time $\Sigma\Delta$ modulator consists of an active-RC filter which performs high linearity characteristics and has a simple tuning circuit for low power operating system The architecture of this modulator is the $3^{rd}-order$ 4-bit single loop configuration with a 24 of OSR (Oversampling Ratio) to increase the power efficiency. The modulator includes a half delay feedback path to compensate the excess loop delay. The experimental results of the modulator are 71dB, 65dB and 74dB of the peak SNR, peak SMR and dynamic range, respectively. The continuous-time $\Sigma\Delta$ modulator is fabricated in a 0.18-um 1P4M CMOS standard process and dissipates 15mW for a single supply voltage of 1.8V.

• Journal of Fashion Business
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• v.17 no.6
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• pp.28-43
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• 2013

Recent trends toward the collaborations among various sectors of academia and research areas have brought interests and significances in new activities especially in the fashion and textile areas. One of the collaboration examples is the recent research projects on 3D virtual clothing systems based on the 3D CAD software. The 3D virtual clothing systems provide simulated apparels with high degrees of fidelity in terms of color, texture, and structural details. However, since real fabrics exhibit strong nonlinearity, anisotropy, viscoelasticity, and hysteresis, the 3D virtual clothing systems need fine tuning parameters for the simulation process. In this study, characteristics of silk fabrics, which are woven by using degummed silk and raw silk yarns, are being analyzed and compared. Anisotropic properties may be measured as warp and filling direction properties separately in woven fabrics, such as warp tensile stress or filling bending rigidity. Hysteretic properties may be measured as bending hysteresis or shear hysteresis by using KES measurements. These data provide deformation-force relationships of the fabric specimen. Three-dimensional effects obtained when using these characteristic fabrics are also analyzed. The methods to control the three-dimensional appearance of the sewn fabric specimens when utilizing a programmable microprocessor-based motor device, as prepared in this study, are presented. Based on the physical and mechanical properties measured when using the KES equipment, the property parameters are being into a 3-dimensional virtual digital clothing system, in order to generate a virtual clothing product based on the measured silk fabric properties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.282-286
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• 2000

In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.11
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• pp.1074-1081
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• 2007

This paper presents a method for real-time face detection and tracking which combined Adaboost and Camshift algorithm. Adaboost algorithm is a method which selects an important feature called weak classifier among many possible image features by tuning weight of each feature from learning candidates. Even though excellent performance extracting the object, computing time of the algorithm is very high with window size of multi-scale to search image region. So direct application of the method is not easy for real-time tasks such as multi-task OS, robot, and mobile environment. But CAMshift method is an improvement of Mean-shift algorithm for the video streaming environment and track the interesting object at high speed based on hue value of the target region. The detection efficiency of the method is not good for environment of dynamic illumination. We propose a combined method of Adaboost and CAMshift to improve the computing speed with good face detection performance. The method was proved for real image sequences including single and more faces.

• Smart Structures and Systems
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• v.16 no.5
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• pp.937-960
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• 2015

Tuned mass dampers (TMDs) have been a prevalent vibration control device for suppressing excessive vibration because of environmental loadings in contemporary tall buildings since the mid-1970s. A TMD must be tuned to the natural frequency of the primary structure to be effective. In practice, a TMD may be assembled in situ, simultaneously with the building construction. In such a situation, the respective dynamic properties of the TMD device and building cannot be identified to determine the tuning status of the TMD. For this purpose, a methodology was developed to obtain the parameters of the TMD and primary building on the basis of the eigenparameters of any two complex modes of the combined building-TMD system. The theory was derived in state-space to characterize the nonclassical damping feature of the system, and combined with a system identification technique to obtain the system eigenparameters using the acceleration measurements. The proposed procedure was first demonstrated using a numerical verification and then applied to real, experimental data of a large-scale building-TMD system. The results showed that the procedure is capable of identifying the respective parameters of the TMD and primary structure and is applicable in real implementations by using only the acceleration response measurements of the TMD and its located floor.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.439-442
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• 2003

In order to solve the difficulties of parameter settings in SA algorithm, an improved practical SA algorithm is proposed by employing the threading techniques, appropriate software structures, and dynamic adjustments of temperature parameters. Threads provide a mechanism to realize a parallel processing under a disperse environment by controlling the flux of internal information of an application. Thread services divide a process by multiple processes leading to parallel processing of information to access common data. Therefore, efficient search is achieved by multiple search processes, different initial conditions, and automatic temperature adjustments. The proposed are methods are evaluated, for three types of Traveling Salesman Problem (TSP) (random-tour, fractal-tour, and TSPLIB test data)are used for the performance evaluation. The experimental results show that the computational time is 5％ decreased comparing to conventional SA algorithm, furthermore there is no need for manual parameter settings. These results also demonstrate that the proposed method is applicable to real-world vehicle routing problems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1092-1098
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• 2002

This paper discusses the composition of the theory of reinforcement teaming, which is applied in real-time teaming, and evolutionary strategy, which proves its the superiority in the finding of the optimal solution at the off-line teaming method. The individuals are reduced in order to team the evolutionary strategy in real-time, and new method that guarantee the convergence of evolutionary mutations are proposed. It is possible to control the control object varied as time changes. As the state value of the control object is generated, applied evolutionary strategy each sampling time because of the teaming process of an estimation, selection, mutation in real-time. These algorithms can be applied, the people who do not have knowledge about the technical tuning of dynamic systems could design the controller or problems in which the characteristics of the system dynamics are slightly varied as time changes. In the future, studies are needed on the proof of the theory through experiments and the characteristic considerations of the robustness against the outside disturbances.