• ETRI Journal
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• v.36 no.2
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• pp.286-292
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• 2014

This paper presents a compact structure composed of an upper high-impedance transmission line, a middle extended parallel coupled line, and a pair of inter-coupled symmetrical stepped impedance stubs. Detailed investigation into this structure based on an equivalent circuit analysis reveals that this proposed structure exhibits a quasi-elliptic low-pass filtering response with three transmission zeros. Moreover, the positions of the three transmission zeros can be tuned and reallocated flexibly by choosing the proper circuit parameters. Finally, the design concept is validated through the design, fabrication, and measurement of two exemplary low-pass filters (LPFs) with one single unit and two cascaded asymmetric units. The measured results agree well with the simulated results. In addition, in the range of $1.42f_c$ to $7.03f_c$, the fabricated quasi-elliptic LPFs experimentally demonstrate a very wide upper-stopband of 20 dB using a compact size of only $0.0089{\lambda}_g{^2}$, where ${\lambda}_g$ is the guided wavelength of a $50{\Omega}$ transmission line at the central frequency.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.205-209
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• 2013

A conventional acoustic echo suppressor (AES) considering only room impulse response between a loudspeaker and a microphone eliminates acoustic echo from the microphone input. However, in a nonlinear acoustic echo environment, the conventional AES degraded because of a nonlinearity of the loudspeaker. In this paper, we adopt AES based on the frequency-domain second-order Volterra filter using Least Square method. For comparing performances, we conduct objective tests including Echo Return Loss Enhancement (ERLE) and Speech Attenuation (SA). The proposed algorithm shows better performance than the conventional in both linear and nonlinear acoustic echo environments.

• Composites Research
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• v.24 no.2
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• pp.14-21
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• 2011

In this paper, a dynamic model is proposed for multi-axis optical structure of an aircraft. Modal analysis, sine-wave analysis, and random vibration analysis are done using a multi-body dynamic program for the multi-axis optical structure. By applying Al 6061-T6 and two types of CFRP to the camera module, x, y, and z responses are found and compared according to each axis excitation. The results will be used for reducing the weight of the camera module.

• Journal of Mechanical Science and Technology
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• v.16 no.12
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• pp.1583-1593
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• 2002

This paper discusses the model validation and vibration suppression of an AMB flexible rotor via additional LQG controller. The main difficulty in the vibration suppression of the flexible rotor using AMB is to realize a controller that can minimize resonance without injuring the stabilized rigid modes. In order to solve this problem, simple scheme for system modeling and controller design are developed. Firstly, the AMB flexible rotor is stabilized with a PID controller, which leads to a new stable rotor-bearing system. Then, authors propose the model validation procedure using measured open-loop frequency responses to obtain an accurate model of the AMB flexible rotor system. After that, LQG controller with modal weighting is designed to suppress resonances of the stable rotor-bearing system. Due to the poor controllability and observability of flexible modes compared to rigid ones, balancing of two Gramians is prerequisite for the fair LQG controller design. Simulation with step disturbance and experimental results of unbalance response up to 10,000 rpm verified the effectiveness of the proposed scheme.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1897-1907
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• 1991

An analysis is presented for the primary resonance of a clamped-hinged beam, which occurs when the frequency of excitation is near one of the natural frequencies, .omega.$_{n}$. Three mode interactions, .omega.$_{2}$=3.omega.$_{1}$, and .omega.$_{3}$=.omega.$_{1}$+2.omega.$_{2}$, are considered and their influence on the response is studied. The case of two mode interaction, .omega.$_{2}$=3.omega.$_{1}$, is also considered in order to compare it with the case of three mode interactions. The straight beam experiencing mid-plane stretching is governed by a nonlinear partial differential equation. By using Galerkin's method the governing equation is reduced to a system of nonautonomous nonlinear ordinary differential equations. The method of multiple scales is applied to obtain steady-state responses of the system. Results of numerical investions show that there exists no significant difference between both modal interactions.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.62-67
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• 2007

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin (Au/Sn) eutectic solder bonding. The membrane chip has 2.5 mm${\times}$2.5 mm, $0.5{\mu}m$ thick low stress silicon nitride membrane, 2 mm${\times}$2 mm Au/Ni/Cr membrane electrode, and $3{\mu}m$ thick Au/Sn layer. The backplate chip has 2 mm${\times}$2 mm, $150{\mu}m$ thick single crystal silicon rigid backplate, 1.8 mm${\times}$1.8 mm backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50-60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is $39.8{\mu}V/Pa$ (-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

• Journal of Sensor Science and Technology
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• v.16 no.2
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• pp.132-141
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• 2007

The purpose this research is to develop QCM (quartz crystal microbalance) biosensor for the determination of haptoglobin. Haptoglobin is an acute-phase protein with a hemoglobin-binding activity and has a potential to be used as a biomarker for infection or cancer. Haptoglobin level in milk has been used for the diagnosis of cow mastitis. In this study, anti-bovine haptoglobin antibody or bovine hemoglobin was chemically immobilized on the surface of the QCM, and the resulting sensor chips were tested for their response to samples containing haptoglobin at different concentrations. Concentration dependent frequency change was observed with both of the sensor chips. Especially, the sensor chip containing anti-bovine haptoglobin antibody showed sufficient sensitivity in the concentrations typically observed in the cows with mastitis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.537-543
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• 2002

This paper examines a new in-process measurement system for the measurement of micro-defects on the surfaces of brittle materials by using the AFM (Atomic Force Microscopy). A new AFM scanning stage that can also perform nano-scale bending of the sample was developed by adding a bending unit to a commercially available AFM scanner. The bending unit consists of a PZT actuator and sample holder, and can perform static and cyclic three-point bending. The true bending displacement of the bending unit is approximately 1.8mm when 80 volts are applied to the PZT actuator. The frequency response of the bending unit and the stress on the sample were also analyzed, both theoretically and experimentally. Potential surface defects of the sample were successfully detected by this measurement system. It was confirmed that the number of micro-defects on a scratched surface increases when the surface is subjected to a cyclic bending load.

• Journal of Fashion Business
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• v.9 no.3
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• pp.88-98
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• 2005

This study focuses on the needs at both consumers and manufacturers. It aims to find ways for consumers to purchase outfits that would fit their particular body type and preferences at reasonable prices, choose raw materials and style at garments, and virtually try them on. In addition, the study is designed to help apparel manufacturers identity customers' changing needs, reduce inventories, manage information on customers' body type in a digitalized form, and eventually contribute to promoting electronic commerce. Based on nine basic patterns that tit each subject, 108 virtual garments are created by adjusting the size of the patterns (9 subjects $\times$ 4 body parts $\times$ 3 patterns = 108 outfits). In order to determine fitting preferences for each body part and find optimized conditions, cross-tabulation analysis including $X^2$ and frequency analysis were performed to measure the appearance rate. A style of virtual garment, which is minus 2cm from chest size was chosen as the most appropriate pattern to the baseline location of front the chest. For the waist parts, the C style as an appropriate virtual garment to front and back view. In the front, lateral and back view, a style was chosen in the response to the sleeve-bodice combinations, the ease amount of armhole area, the armhole depth and the loosening of tightening or armhole line.

• The Korean Journal of Food And Nutrition
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• v.21 no.1
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• pp.106-113
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• 2008

The purpose of this study was to compare the nutrient intakes and food lifestyles between double income families' children and full-time housewives' children. The subjects included 525 children ages 4 to 7 years old. The proportion of children receiving regular meals was 77.8%. One of the primary reasons for skipping breakfast was 'no appetite'(49.9%). In terms of food habit score 20.8% of the subjects belonged to the 'good' category and children from double income families had significantly higher scores than in full-time housewives' children(p<0.01). The first consideration for meal preparation was significantly different between the two types of families : for 44.3% of the children from it was double income families it was 'favorite', while for 42.8% of full-time housewives' children it was 'nutrition'(p<0.001). Mothers' attention to food for the health of their children was the primary reason in the response 'have regular meals each day'(90.6%). Vitamin C and fat intakes were significantly different between double income families' children and in full-time housewives' children(p<0.01, p<0.05). In conclusion, double income families' children have a lower frequency for eating breakfast and lower intakes of nutrients, such as Ca, P, K, vitamin A, vitamin $B_1$, $B_2$, and vitamin C than full-time housewives' ones.