• Journal of Korean society of Dental Hygiene
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• v.13 no.6
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• pp.1079-1086
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• 2013

Objectives : It is considered that the education of cardiopulmonary resuscitation and the preparation for quick response to cardiac arrest are very important to dental hygiene students who get employed in dental clinics and hospitals after graduation. The purpose of the study is to investigate the perception, attitude and knowledge of cardiopulmonary resuscitation(CPR) in dental hygiene students and to provide basic data to educate CPR education program for the dental hygiene students. Methods : The study subjects were 260 students in the department of dental hygiene in J city health college. A self-reported questionnaire was conducted from May 1st to 31st 2013. A frequency analysis and x2-test was carried out to confirm the general characteristics of the 260 respondents. Results : The perception rate of the CPR was 55.8%(145 persons). There were positive correlations between perception and attitude of CPR (r=.202) and attitude and knowledge(r=.249). Conclusions : CPR performance is the vital to the cardiac arrest victim. So it is necessary to educate the dental hygiene students in case of emergency situation. It is necessary to educate CPR and basic life support (BLS) in dental hygiene students.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.21-24
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• 2010

We present a novel electrochemical method to fabricate a single Pd nanowire based on direct current assisted dielectropheresis (DEP) process between two predefined metal electrodes. The electrochemical methods was investigated as functions of frequency and voltage for optimal growth conditions of Pd nanowire. The synthesized Pd nanowire have a good resistance of $1\;k{\Omega}$, diameters of several hundred nanometers on average and lengths of $8\;{\mu}m$. Finally, the single Pd nanowire was capable of detecting hydrogen in the concentration range from 100 to 2500 ppm with high sensitivity and response time, thus demonstrating its suitability for use as a hydrogen sensor.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.374-380
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• 2005

Vibration sensors have a wide scope of applications in the field of monitoring systems that needs to perceive an undesirable physical vibration before a critical failure occurs in a system, and then costly unplanned repairs can be avoided. The conventional vibration sensors developed so far have many disadvantages, such as complex manufacturing process, bulkiness, high cost, less reliability and so on. This paper reports a simple-structured vibration sensor, which has been developed using a commercialized conductive ball and silicon bulk-micromachining technology. The sensor consists of a conductive ball placed in $600{\mu}m$-deep micromachined silicon groove, in which Au thin film has been patterned using a shadow mask technique. Prior to the formation of the Au thin film, the sharp convex corner was rounded for smooth meatl deposition on the non-planar surface at the edge of the groove. The measurement results of the fabricated vibration sensor demonstrate a stable response characteristic to low-frequency vibration range ($1{\sim}30{\;}Hz$).

• Journal of Sensor Science and Technology
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• v.25 no.2
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• pp.131-137
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• 2016

In this study, a multilevel visible light communication (VLC) system based on resistor ladder circuit is designed to transmit medical data. VLC technology is being considered as an alternative wireless communication due to various advantages such as ubiquity, license free operation, low energy consumption, and no radio frequency (RF) radiation characteristics. With VLC even in places where traditional RF communication (e.g., Wi-Fi) is forbidden, significant bio-medical signal including the electrocardiography (ECG) and photoplethysmography (PPG) data can be transmitted. More lives could be saved anywhere by this potential advantage of VLC with a fast emergency response time. A multilevel transmission scheme is adopted to improve the data capacity with keeping simplicity, where data transmission rate can increase by log2m times (m is the number of voltage levels) than that of conventional VLC transmission based on on/off keying. In order to generate multi-amplitudes, resistor ladder circuit, which is a basic principle of digital to analog convertor, is employed, and information is transferred through LED (Light-Emitting Diode) with different voltage level. In the receiver side, multilevel signal is detected by optical receiver including a photo diode. Then, the collected data are analyzed to serve the necessary medical care to the concerned patient.

• Journal of Sensor Science and Technology
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• v.27 no.4
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• pp.269-274
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• 2018

High-sensitivity signal-to-noise ratio (SNR) microphones are essentially required for a broad range of automatic speech recognition applications. Piezoelectric microphones have several advantages compared to conventional capacitor microphones including high stiffness and high SNR. In this study, we designed a new piezoelectric membrane structure by using the finite elements method (FEM) and an optimization technique to improve the sensitivity of the transducer, which has a high-quality AlN piezoelectric thin film. The simulation demonstrated that the sensitivity critically depends on the inner radius of the top electrode, the outer radius of the membrane, and the thickness of the piezoelectric film in the microphone. The optimized piezoelectric transducer structure showed a much higher sensitivity than that of the conventional piezoelectric transducer structure. This study provides a visible path to realize micro-scale high-sensitivity piezoelectric microphones that have a simple manufacturing process, wide range of frequency and low DC bias voltage.

• Journal of Fashion Business
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• v.10 no.4
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• pp.45-54
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• 2006

This study analyzed the purchasing behavior for underwear, with the subjects of pregnant women, and the trend of its fit preference and thereby looks into the practices of their clothing life to provide the basic data for the formation of maternity clothing industry, focusing on the underwear development in response to pregnant women's body type features. The conclusion were as follows: 1. The analysis of underwear wearing practices for the women in the pregnancy of eight months or longer and those after the delivery within one month showed that about 80-90% of them wore panties or brassieres and about 70% of them did not wear girdles, thus with a lower level for girdles than for panties or brassieres. 2. The surveys of the satisfaction and fit for two designs each with the high wearing frequency did not show any relatively significant difference in assessment by the design. The analysis of the satisfaction by the part with the maternity underwear indicated that in the case of panties the respondents were dissatisfied with the length as to be long, and also dissatisfied with waist circumference, abdomen circumference, private parts, and groin as to be small, reflecting that the circumference coverage of the panties in the market was not effectively managed.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1321-1325
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• 2013

In this paper, we proposed an air bearing stage with active magnetic preloads in vertical directions compensating motion errors and attenuating vibrations to improve dynamic characteristics. This preloaded design gives simpler configuration of the stage, and active control of preload can be used for compensating motion errors by feedforward method. To improve dynamic characteristics, vibration of the table is monitored by an accelerometer, and controlled by a DSP based digital controller with integrator and band pass filters for suppressing roll and pitch vibration modes. The modes were evaluated by measuring frequency response functions, and compared with compensated responses. This showed effective results for suppressing poorly damped regenerative vibration of air bearings.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.5
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• pp.385-393
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• 2004

This paper proposes a swing-arm type dual-stage actuator, which consists of a PZT actuator for fine motion and a VCM(voice coil motor) for coarse motion, for an SFF ODD(small form factor optical disk drive), in order to achieve fast access speed and precise track-following control. Over the past few decades there have been a lot of researches related to the VCM and dual-stage actuator. In this paper, we focus our attention on the design and control of the PZT actuator. Due to the dual cantilever structure. the PZT actuator can generate precise translational tracking motion at its tip to which an optical pickup is attached. and the effect of hysteric behavior of the PZT element is reduced. The dynamic model of the PZT actuator is derived by using the Hamilton's principle, and verified by comparing it with the experimental frequency response. The sliding mode control is designed in order to be robust against modeling uncertainties. Simulations and experimental results confirm the effectiveness of the suggested control scheme.

• Journal of KSNVE
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• v.9 no.3
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• pp.593-599
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• 1999

A rotordynamic analysis is performed with a motor-bull gear rotor system supported on two partial bearings, which is intended to drive a high-speed turbo-chiller compressor impeller shaft through its built-in pinion gear. The motor-bull gear rotor system has a rated speed of 3,600 rpm, and is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support partial bearings are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the motor-bull gear rotor-bearing system is carried out to evaluate its whirl natural frequencies and mode shapes and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regradless of operating conditions, i.e., loads and operating speeds.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.5
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• pp.416-423
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• 2004

In this paper, an experimental verification of system identification technique for constructing finite element model is conducted for a three-story test structure equipped with an active mass driver (AMD). Twenty Gaussian white noises were used as the input for AMD, and the corresponding accelerations of each floor are measured. Then, the complex frequency response function (FRF) for the input, the force induced by the AMD, was obtained and subsequently, the Markov parameters and system matrices were estimated. The magnitudes as well as phase of experimentally obtained FRFs match well with those of analytically obtained FRFs.