• 제어로봇시스템학회논문지
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• 제13권7호
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• pp.711-717
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• 2007

Location information will become increasingly important for future Pervasive Computing applications. Location tracking system of a moving device can be classified into two types of architectures: an active mobile architecture and a passive mobile architecture. In the former, a mobile device actively transmits signals for estimating distances to listeners. In the latter, a mobile device listens signals from beacons passively. Although the passive architecture such as Cricket location system is inexpensive, easy to set up, and safe, it is less precise than the active one. In this paper, we present a passive location system using Cricket Mote sensors which use RF and ultrasonic signals to estimate distances. In order to improve accuracy of the passive system, the transmission speed of ultrasound was compensated according to air temperature at the moment. Upper and lower bounds of a distance estimation were set up through measuring minimum and maximum distances that ultrasonic signal can reach to. Distance estimations beyond the upper and the lower bounds were filtered off as errors in our scheme. With collecting distance estimation data at various locations and comparing each distance estimation with real distance respectively, we proposed an equation to compensate the deviation at each point. Equations for proposed algorithm were derived to calculate relative coordinates of a moving device. At indoor and outdoor tests, average location error and average location tracking period were 3.5 cm and 0.5 second, respectively, which outperformed Cricket location system of MIT.

• Journal of Periodontal and Implant Science
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• 제36권4호
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• pp.901-911
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• 2006

Maxillary palatal mucosa is the most frequently used donor site of the soft tissue for periodontal plastic surgery. In our study, thickness of the palatal mucosa between the mesial side of the maxillary first premolars and the distal side of the maxillary first molars was measured with a periodontal probe and an ultrasonic device in 30 young Korean adults. Using the data, the possibility of the clinical application of ultrasonic devices was evaluated. The results of this study were as follow; 1. The thickness of the palatal mucosa of the maxillary premolars is the thickest and that of the mid-palatal portion of the maxillary first molar is the thinnest. 2. The thickness of the palatal mucosal tissue increases from the gingival margin to the mid-palatal suture. 3. The measurements of the periodontal probe and the ultrasonic device revealed the strong positive correlations.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.414-417
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• 2001

Recently, developments of device using characteristics of ceramics as a new technical material is in progress. While doing so, Ultrasonic motor which is a part of research & development of piezo-actuator by piezo-effects is being used in the various applications. So, we fabricated a flat-type $L_{1}-B_{8}$ mode Ultrasonic motor and measured the operation characteristics of its. The size of USM is 80*20*1.5[$mm^{3}$](length*width*thickness) and is constructed with stator by piezo-ceramics and stainless elastic body and rotator by bearings. As results of experiments, the fastest speed of revolution(v), the maximum torque(T) and the efficiency( $\eta$ ) were 37.5[cm/sec], 5.0[ $mN{\cdot}m$ ] and 1.17[%] respectively when 27.9[kHz], 150[gf], 50[V] were applied. So, we think this $flat-type_{1}-B_{8}$ mode Ultrasonic motor is able to be used for applications in forwarding device of a paper or electric card and so on.

• 한국소음진동공학회논문집
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• 제22권9호
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• pp.845-852
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• 2012

Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention from not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation on the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100 mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6 % at 2 m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfering distance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.771-776
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• 2012

Recently, wireless power transfer technology is ready to be commercialized in consumer electronics. It draws attention of not only experts but also public because of its convenience and huge market. However, previous technologies such as magnetic resonance and induction coupling have limited applications because of its short transfer distance compared to device size and magnetic intensity limitation for the safety of body exposure. As an alternative, ultrasonic wireless power transfer technology is proposed. The ultrasonic wireless power transfer system is composed of transmitter which converts electrical energy to ultrasonic energy and receiver which converts the ultrasonic energy to the electrical energy again. This paper is focused on the development of high energy conversion efficiency of ultrasonic transmitter. Optimal transfer frequency is calculated based on the acoustic radiation and damping effect. The transmitter is designed through numerical analysis, and is manufactured to match the optimal transfer frequency with the size of 100mm diameter, 12.2 mm thickness plate. The energy conversion efficiency of about 13.6% at 2m distance is obtained, experimentally. This result is quite high considered with the device size and the power transfer distance.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.87-95
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• 2005

In this study, we performed RTD measurement at the die exit of co-rotating twin-screw extruder using a non-destructive ultrasonic device. The ultrasonic device was attached at slit die and was composed of a steel buffer rod and 10 MHz longitudinal piezoelectric ultrasonic transducer. This in-line ultrasonic monitoring method is based on the ultrasonic response of $CaCO_3$ filled in polymer. The RTD is evaluated by variation of ultrasonic attenuation with time caused by change of the tracer concentration during extrusion. The ultrasonic tracer, pellet type of compounded $CaCO_3$ in polymer was used in this study. The effects of tracer concentration on RTD and flow patterns were studied. Evaluation for the residence functions at different screw speeds, feeding rates and screw configurations were also carried out.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.741-743
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• 2000

In this paper the relationship between the pressing force applied to rotors and the characteristics of ultrasonic motor are discussed. The characteristics of ultrasonic motor using a piezoelectric vibrator were systematically studied. And these were applied to the construction of a card forwarding device. The principle of ultrasonic motor is to use an elliptical motion generated on the side of the vibrator, and the elliptical motion of the ultrasonic motor was obtained by complex oscillation of $L_1-B_4$ mode. As the experimental results. the forwarding speed of the card increased linearly as the pressing force applied to rotors increased. The forwarding speed of the card was 16.0 cm/s when the pressing force applied to rotors was 1 N. The forwarding force of the card increased linearly as the pressing force applied to rotors increased. The forwarding force of the card was 398 mN when the pressing force applied to rotors was 1 N. Therefore, this ultrasonic motor can be expected to be used for card-forwarding device and so on.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.30-37
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• 2008

An object transport system is driven by a conveyor belt system or a magnetic levitation system. It is an indispensable device in many fields and especially it is very important in the factory automation. However, the conventional transport system can damage precision optical components by the contact force and destroy the inner structure of semiconductor by the magnetic field. The new transport system for transporting without damage is required. The ultrasonic transport system is a device that transports objects on the elastic body using ultrasonic wave. In this paper, an object transport system using the ultrasonic wave is developed for transporting precision elements without damage. Traveling waves are generated by the ultrasonic wave generator fixed in both ends of the beam. The traveling wave of the ultrasonic transport system is theoretically analyzed. Transport direction of the object is examined according to phase difference and frequency. The theoretical results are verified by experiments.

• Journal of Periodontal and Implant Science
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• 제28권4호
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• pp.823-828
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• 1998

A primary goal of periodontal therapy is the creation of root surfaces that are free of plaque and calculus. It is not yet to be determined whether it is desirable to have a smooth root surface after treatment. It is also not clear what degree of roughness result from different instruments. In the present study various instruments for root surface debridement were evaluated. 20 extracted teeth were utilized, and the teeth were treated with one of the following instrument: Gracey curette, Perio Clean, and piezo ultrasonic device(Setlec, P Max) with general scaler tip, curette-like tip, and diamond tip. 3 dimensional planimetric device(Accura) was used to evaluate the average surface roughness. It was demonstrated hand and power-driven instruments did not have a significant difference in roughness of the root surface following instrumentation. And ultrasonic scaler tip tended to make a most smooth surface than other instruments. The possible reasons of the result were discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1458-1462
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• 2003

High temperature and high pressure heavy water flows through the pipes in atomic power plants. The curved parts of pipes are critical parts in that they change the direction of steam flow, and these parts are especially affected by severe wear. Therefore, most pipes in atomic power plants are tested by non-destructive examination by workers who use ultrasonic sensors to measure the wall thickness of pipes. But not only are these pipes located in a very dangerous environment, but the space is also very limited. For the safety of workers, it is necessary to design a device that uses a mobile robot that can inspect curved pipes. This paper presents the design and construction of a small device that can generate the necessary contact forces between ultrasonic sensors and pipe walls in a limited space. And a mobile robot is used in place ortho worker for successful non-destructive examination.