• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.2
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• pp.140-147
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• 1987

In this paper, seven-order elliptic low-pass passive network is synthesized by using doublyterminated ladder network is directly transformed into the active network which has the advantage of low sensitivity and can be realized conveniently. The circuit simulation results of passive network and active network synthesized with FDNR and Leap-frog technique are compared, and it is proved that the two rest work has the same characteristics.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.1
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• pp.1-7
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• 2002

The purpose of this work is to develop High-Frequency Active Filter and super-miniaturation technology(SMD Type) of Filter which are essential for the key R/F Microwave components in the Mobile telecommunication system. The cut-off frequency of high frequency active filter for multimedia is 2.5 MHz, the gain is 0.5dB at 100 kHz, the passband ripple is 1.2 dB max at 100 kHz~2.0 kHz, GDT is 60 nsec at 100 kHz-2.0 MHz, the attenuation is 40 dB min at 3.75 MHz.

• Korean Journal of Construction Engineering and Management
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• v.17 no.3
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• pp.3-12
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• 2016

Recently, construction industry shows active expansion in overseas construction market. But the active work limited in construction work, on the other hand, design-drawing work is evaluated shortage of competitive power. So this study aim to improve the competitive of 'domestic design-drawing work'thorough objective evaluation. Objective evaluation is consist of 'design attribution'. Design attribution is based on the execution drawing and complement by existing reasearch, expert interview. And then, list up the 'design attribution' evaluation list to carry out a survey targeting hands-on worker. Survey is consist of 'Likert 5-point scale, FMEA method'. As a result, construction company and design company show different opinions in both relative position evaluation and importance evaluation.

• Earthquakes and Structures
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• v.17 no.2
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• pp.143-162
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• 2019

Motivated by a simpler and more compact hybrid active tuned mass damper (ATMD) system with wide frequency spacing (i.e., high robustness) but not reducing the effectiveness using the least number of ATMD units, the active tuned tandem mass dampers (ATTMD) have been proposed to attenuate undesirable oscillations of structures under the ground acceleration. Likewise, it is expected that the frequency spacing of the ATTMD is comparable to that of the active multiple tuned mass dampers (AMTMD) or the multiple tuned mass dampers (MTMD). In accordance with the mode generalised system in the specific vibration mode being controlled (simply referred herein to as the structure), the closed-form expression of the dimensionless displacement variances has been derived for the structure with the attached ATTMD. The criterion for the optimum searching may then be determined as minimization of the dimensionless displacement variances. Employing the gradient-based optimization technique, the effects of varying key parameters on the performance of the ATTMD have been scrutinized in order to probe into its superiority. Meanwhile, for the purpose of a systematic comparison, the optimum results of two active tuned mass dampers (two ATMDs), two tuned mass dampers (two TMDs) without the linking damper, and the TTMD are included into consideration. Subsequent to work in the frequency domain, a real-time Simulink implementation of dynamic analysis of the structure with the ATTMD under earthquakes is carried out to verify the findings of effectiveness and stroke in the frequency domain. Results clearly show that the findings in the time domain support the ones in the frequency domain. The whole work demonstrates that ATTMD outperforms two ATMDs, two TMDs, and TTMD. Thereinto, a wide frequency spacing feature of the ATTMD is its highlight, thus deeming it a high robustness control device. Furthermore, the ATTMD system only needs the linking dashpot, thus embodying its simplicity.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.3
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• pp.201-209
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• 2017

Objectives: This study was conducted to assess the association between level of physical activity and depressive symptoms among Korean male workers. Methods: A self-administered questionnaire was distributed and anthropometric measurements were conducted with 1,379 male workers during a general health check. From this data, we identified the general characteristics, levels of physical activity(IPAQ), and depressive symptoms(CES-D) of the study population. We conducted univariate logistic regression to verify the variables that affect depressive symptoms and multivariate logistic regression to calculate odds ratios. Results: Among the 1,379 male workers, 43.4% were in the insufficiently active group(IPAQ category 1) and 22.8% were in the depressive symptom group($CES-D{\geq}16$). The odds ratio(OR) for depressive symptoms was statistically higher in the insufficiently active group, workers aged over 30, the shift work group, and the unmarried group. Adjusted for those variables, the ORs for depressive symptoms were found to be 1.45(95% CI=1.25-2.11), 1.15(OR=1.15, 95% CI=1.08-1.99) and 1.75(95% CI=1.48-2.02), for the insufficiently active group, workers aged over 30, and the shift work group, respectively. Conclusions: We found physical inactivity, age, marital status, and shift work to be associated with depressive symptoms among male workers. This study supports the suggestion that physical activity can be helpful to reduce depressive symptoms among workers.

• Management & Information Systems Review
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• v.13
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• pp.141-162
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• 2003

This article discusses the issues of the estimated size and characteristics of irregular employment work force in Korea after IMF economic crisis in 1997. The issues of the estimated size of irregular employment work force originated from different concepts and its operationalizations among the labor economists, despite their utilization of the same labor force data, 'Economically Active Population Survey(EAPA)' collected from Korea National Statistical Office(KNSO). And the issues contribute toward the understandings of the irregular employment and the limits of the EAPA, despite its various usefulness. This article also describes the summary characteristics of irregular employment work force from both sides of labor supply and its demand. The major characteristics of irregular employment work force on the labor supply side appears in the concentration of social minorities, i.e. woman, the aged, lower educated and skilled populations. On the labor demand of irregular employment work force, the majority of it concentrated on the establishments under 10 employees, and probably the important incentives for irregular employment work force of the firms is labor cost efficiency. Finally, this article propose an alternative against the discrimination between the regular and irregular work force.

• Smart Structures and Systems
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• v.16 no.6
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• pp.1147-1167
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• 2015

Wireless smart sensors, which have become popular for monitoring applications, are an attractive option for implementing structural control systems, due to their onboard sensing, processing, and communication capabilities. However, wireless smart sensors pose inherent challenges for control, including delays from communication, acquisition hardware, and processing time. Previous research in wireless control, which focused on semi-active systems, has found that sampling rate along with time delays can significantly impact control performance. However, because semi-active systems are guaranteed stable, these issues are typically neglected in the control design. This work achieves active control with smart sensors in an experimental setting. Because active systems are not inherently stable, all the elements of the control loop must be addressed, including data acquisition hardware, processing performance, and control design at slow sampling rates. The sensing hardware is shown to have a significant impact on the control design and performance. Ultimately, the smart sensor active control system achieves comparable performance to the traditional tethered system.

• Smart Structures and Systems
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• v.13 no.3
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• pp.435-451
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• 2014

In this paper, we investigate the vibration control of multimodal structures and present an efficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of the optimal law such that the controller follows this latter only if there is sufficient energy which will be extracted directly from the system vibrations itself. The control algorithm is presented and validated for a cantilever beam structure subjected to external perturbations. Comparisons between the proposed law performances and those obtained by independent modal space control (IMSC) and semi-active control schemes are offered.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.4
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• pp.500-507
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• 2009

This paper presents a novel method which can detect a target in IR image for active protection system. The target in IR image for the active protection system is small, moreover it moves with enormous speed. The proposed algorithm is comprised of robust clutter rejection methods and target optimized detection algorithms for small target, and an advanced method of selecting a final target position in target area, it can work in some milliseconds. The proposed algorithm provides the active protective system with more correct positions than those of radar, so that helps the active protection system can defense all threats with the utmost precision.

• Journal of KSNVE
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• v.6 no.6
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• pp.851-856
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• 1996

The active noise cancellation system showing the effective convergence and stability has been studied by simplifying the controller structures using the weighting factors of control error path to the multi-channel filtered-x LMS algorithm which needs a lot of calculations and the performance has been verified experimentally. Besides, to implement the system performance in a vehicle cabin, experimental work for selecting the suitable numbers and positions of the microphones and speakers was accomplished. Effectively combining a TMS 320C 31 main processor conducting real number calculations and having various functions with other components, the purpose-built system board for active noise cancellation has been designed and with this board, car active noise cancellation system showing maximum stable 10dB noise reduction has been obtained at the car idling conditions above 3000rpm range.