• 한국자동차공학회논문집
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• 제9권1호
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• pp.45-56
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• 2001

A constant volume combustion chamber is employed to investigate the initial flame kernel development and flame propagation of gasoline-air mixtures with various ignition systems, ignition energy and spark plug electrodes. To do this research, four ignition systems are designed and manufactured, and the ignition energy is controlled by varying the dwell time. Several kinds of spark plugs are also made to analyze the effects of electrodes on flame kernel development. The velocity of flame propagation is measured by the laser deflection method. The output laser beam from He-Ne laser is divided into three parallel beams by a beam splitter. The splitted beams pass through the combustion chamber. They are deflected when contacted with flame front, and the voltage signals from photodiodes change due to deflection. The results show that higher ignition energy raises the flame propagation speed especially under the fuel lean operation. The wider electrode gap, smaller electrode diameter and sharper electrode tip make the speed of the initial flame propagation faster. The speed of the initial flame propagation is affected by electrode material as well. Electrode material with lower melting temperature help the initial flame propagation.

• 항공우주시스템공학회지
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• 제13권2호
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• pp.19-25
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• 2019

구조물의 충격 위치 검출을 위해 본 연구그룹에서는 압전 페인트 센서를 연구하고 있다. 압전 페인트는 고주파 신호 및 충격에 민감한 특성으로 인하여 충격 감지에 사용할 수 있다. 또한, 압전 페인트 센서는 세라믹 센서가 적용될 수 없는 곡선 또는 복잡한 구조에 코팅될 수 있으며 외부 전원을 필요로 하지 않는다. 충격을 검출하기 위해 모자이크 패턴 전극을 시험편 위에 코팅하였고, 충격 신호는 충격이 발생한 전극부에서 얻을 수 있었다. 보다 더 정확한 충격 위치 검출을 위해서는 전극을 더 많은 부분으로 나누어 해당 전극부로부터 충격 데이터 수집이 필요하다. 본 연구에서는, 데이터 수집을 위하여 가볍고 저렴한 간단한 멀티채널 데이터 수집 시스템을 개발하였다. ARM Cortex-M3의 UART 통신을 이용하여 총 4채널의 데이터를 수집하였다.

• 한국표면공학회지
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• 제55권1호
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• pp.32-37
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• 2022

In a carbon-zero social atmospher, research is underway to reduce the use of fossil fuels. Interest in cleaner energy sources and their storage system is growing, and among them, research on effective energy storage is being actively conducted. Energy storage system(ESS) can be divided into secondary batteries, fuel cells, and capacitors, and the superiority of energy density of secondary batteries has a dominent influence on the ESS market. However, as problems with secondary batteries, charge/discharge speed, safety, and deterioration of electrodes are being highlighted. In this study, an electrode for supercapacitor with superior charge/discharge speed and specific capacitance is manufactured. The manufactured spinel nickel cobalt electrodes had specific capacitances of 1018.8 F/g, 690.8 F/g, and 475.1 F/g at 1 A/g in 1 M KOH electrolyte, and shows a performance retention rate of 77.48%, 63.30%, and 58.16% after 2000cycles at 7 A/g.

• 한국입자에어로졸학회지
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• 제14권4호
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• pp.171-180
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• 2018

To optimize the shape of the electrostatic precipitator for the removal of particulate matter in subway environments, the wind-tunnel experiments were carried out to characterize collection efficiency and ozone emission rate. As a standardized parameter, power consumption divided by the square of flow velocity, was increased, the $PM_{10}$ collection efficiency increased. If the standardized parameter is higher than 1.0 due to high power consumption or low flow velocity, increase in thickness of electrodes from 1 to 2 mm, or increase in distance of collection plates from 5 to 10 cm did not change the $PM_{10}$ collection efficiency much. Increase in thickness of high-voltage electrodes, however, can cause decrease in $PM_{10}$ collection efficiency by 28% for low power consumption and high flow velocity. The ozone emission rate decreased as distance of collection plates became wider, because the ozone emission rate per unit channel was constant, and the number of collection channels decreased as the distance of collection plates increased. When the distance of collection plates was narrow, the ozone emission rate increased with the increase of the thickness of electrodes, but the difference was negligible when the distance of collection plates was wide. It was found that the electrostatic precipitator having a thin high-voltage electrodes and a narrow distance of collection plates is advantageous. However, to increase the thickness of high-voltage electrodes, or to increase the distance of collection plates is needed, it is necessary to increase the applied voltage or reduce the flow rate to compensate reduction of the collection efficiency.

• 한국운동역학회지
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• 제30권1호
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• pp.103-109
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• 2020

Objective: The purpose of this study is to compare the muscle activity by electrode location in the biceps brachii during the arm curl isometric exercise and to provide the basic data needed to develop the proper electrode location of the biceps brachii based on the study results comparing the muscle activity by the angle of the elbow joint. Method: 17 adult males (Age: 21.50±4.63 yrs, height: 175.29±5.97 cm, weight: 63.79±15.31 kg, upper-arm length: 30.10±1.22 cm) participated in the study. In the arm curls isometric exercise, the experiment was divided into 1st and 2nd steps to compare muscle activity according to electrode location in the biceps brachii and muscle activity according to elbow angle change. In the first experiment, the surface electrode was attached at one-third point on the line from medial acromion to cubital fossa, according to the measurement method indicated by SENIAM. The elbow angle was set to 90°. In the second experiment, according to the proposed method of this study, the electrodes were separated at one finger's width in the left and right direction at one-third point on the line from medial acromion to cubital fossa, attached at the long head and short head. From the long head electrode, in about a width of two fingers in proximal direction, a total of three electrodes were attached at the myotendinal junction of the long head. The elbow angles were set as 70°, 90°, and 110°, and the isometric exercise (100% MVC) for 5 seconds was maintained with keeping the forearm and the rope to be 90° for the first and second experiments. Results: During the arm curl isometric exercise, there was no significant difference in SH and SENIAM proposition location proposed by this researcher. LH was shown to be lower than the muscle activity of the location proposed by SENIAM and there were significant (p<.01) differences. MJ appeared lower than the muscle activity of the location proposed by SENIAM and there were significant (p<.001) differences. The muscle activity by the elbow joint angle of SH in the biceps brachii was shown in large order of 70°<90°<110°, but there was no significant difference. The muscle activity by the elbow joint angle of LH was shown in large order of 90°<70°<110°, but there was no significant difference. The muscle activity by the elbow joint angle of MJ was shown in large order of 110°<90°<70°, but there was no significant difference. Conclusion: During the arm curl isometric exercise of the biceps brachii, it is judged appropriate to attach surface electrodes to the location proposed by SENIAM.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1232-1235
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• 2004

The purpose of this study is to design electrical stimulation system for pharyngeal dysfunction(dysphagia) in stroke patients. Pharyngeal muscle group activity is important, because contracting muscles provide the driving force at the initiation of the swallow and generate the pressure gradients necessary for bolus movement into the esophagus. Although we have many treatment methods for dysphagia, electrical stimulation system will be useful for stroke patients having dysphagia. Electrical stimulation can be divided into the body stimulation and electrodes. The body stimulation is divided again into frequency counter, time control and current measurement part. These parts are to control the current intensity, frequency and stimulating time. And they can be variable according to the patient's clinical assessment. The electrode plays a role to deliver the current from the system to the muscle. Also the position of the electrode can be variable according to the treatment method. We performed the clinical experiment with the stroke patient who has swallowing disorder. The videofluoroscopy was used for the observation. From the result of clinical experiment based on electrical stimulation, we expected that the dysfunction(in pharynx) level of the patient can be improved. However we could not have enough effectiveness of the treatment because of the number of patients, patient's adaptation and treatment period. We will design the optimized electrical stimulation system based on enough clinical experiment in the future.

• 센서학회지
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• 제13권6호
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• pp.417-423
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• 2004

In order to obtain wide-beam characteristics and variable resonant frequency of a ultrasonic transducer for the array source, an electrode of transverse mode piezoelectric vibrator is divided, and an electronic inductance is connected to the divided electrodes. The electronic inductance is made by GIC (General Impedance Converter) circuit. Because the GIC circuit is made of OP-Amps and other passive elements, the value of the inductance can be selected easily. As the results, the electronic inductance is variable in the range from 0.2 mH to 1.2 mH. Using the inductance, the resonance frequency of the transducer can be changed in the range from 73 kHz to 86 kHz. In the directivity of the transducer, it is confirmed that the beam width of the transducer is wider than $80^{\circ}$ at -3 dB in water.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.393-396
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• 1996

This paper studies electrostatically suspended induction motors (ESIM). The ESIM possesses the rotating ability of an ordinary electrostatic induction motor, in addition to providing contactless support by electrostatic suspension. To accomplish these two functions, a feedback control strategy and the operating principle of an ordinary electrostatic induction motor are used. The stator possesses electrodes which exert the electrostatic forces to the rotor and are divided into a part responsible for suspension and one for rotation. Two rotor types are utilized: a polished glass disk without any surface treatment, and a polished glass disk covered with a thin layer of conductive material (ITO layer) on only one side. In this paper, the principle of the ESIM is described, followed by stator electrode design, experimental apparatus, control strategy for stable suspension. Experimental results show that the glass disk has been rotated with a speed of approximately 70 rpm while being suspended stably at a gap length of 0.3 mm.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.198-201
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• 2004

We have developed a multi-domain vertically aligned liquid crystal display (MVA-LCD) that produces natural gray-scale images even at high viewing angles. We divided each pixel into two areas and set different threshold voltages for each sub-area. A transparent electrode in a sub-area is not connected directly to the source electrodes but via the capacitance of the SiN layer. In particular, light-orange skin color appears very natural, even at a high inclination angle. The contrast ratio is over 500 in the normal direction and over 10 from any viewing angle.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.478-480
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• 2002

Heating by RF wave is divided into dielectric heating and induction heating. Dielectric heating and induction heating from outside the body have the compensatory heating pattern. While surface fat layer is heated by dielectric heating, it is not heated by induction heating. While the peripheral part at the middle of the electrodes is not heated by dielectric heating, it is heated by induction heating. By the simultaneous application both modalities, heating pattern seems to be more uniform and improved. Computer simulation of Finite Element Method (FEM) using ANSYS was conducted to dielectric heating with the results of above-mentioned feature. Theoretical considerations by the uniform RF magnetic field in a cylinder and textbooks support the feature of the above-mentioned heating pattern of induction heating. Further computer simulation of FEM using ANSYS will be conducted to simultaneous application of dielectric heating and induction heating to verify and will be reported.