• Journal of Biosystems Engineering
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• 제29권1호
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• pp.21-28
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• 2004

Spraying is one of the most efficient methods for pesticide and insecticide control. Generally, orchard sprayers(aircarrier sprayer) are used for such applications. However, when an orchard sprayer is used, only 20% of total amount of spray deposits on the target. The rest of spray are not only wasted but are also potential sources of environmental pollution. The research far the development of electrostatic spraying system for orchard sprayer was conducted to develop the new pesticide application technology for the reduction of environmental pollution and f3r the production of safe agricultural products. The spray characteristics for nozzles with the different charging methods were tested and the effect of electrostatic charge was analyzed, in the laboratory experiments. The results of this study indicate that the capacitive type of electrostatic spraying nozzle exhibits a large current deposition of water sprays on the sample target. The covering area ratio by conventional spraying system was 10.2%, while that of electrostatic sprays with pulse induction charging method gave the increased covering area ratio by 4.3 times.

• 조명전기설비학회논문지
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• 제25권5호
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• pp.54-60
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• 2011

This paper presents characteristics of frequency-dependent grounding impedance and transient grounding impedance for the carbon compound grounding electrode used in the installation of computerized electronic equipment and lightning protection system. The frequency-dependent grounding impedances were measured by applying sinusoidal currents in the frequency range from 100 [Hz] to 10[MHz], and the transient grounding impedances were examined by subjecting the impulse current with the front-time between 1~80[${\mu}s$]. As a result, the ground resistance of the carbon compound grounding electrode is less than that of another type grounding electrodes. The transient grounding impedance is relatively low and the conventional grounding impedance is rather lower than the ground resistance. The frequency-dependent grounding impedance of the carbon compound grounding electrode is capacitive and the grounding impedance is decreased with increasing the frequency of injected currents. Therefore in the case that the carbon compound grounding electrode is jointly used with large-scaled grounding electrodes, it is possible to reduce the high frequency grounding impedance of the integrated grounding electrode system.

• 전기학회논문지
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• 제65권7호
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• pp.1257-1262
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• 2016

The purpose of this study is to evaluate whether to take a medicine based on a measuring data using textile proximity sensor. We developed a proximity sensor of ring type using conductive textile, and acquired a data in accordance with the quantity of each pills. To evaluate our approach, we designed an experimental protocol that is counting pills subtracting the one which contains range of 0 T(Tablet, 4,100mg) from 20 T. And, The experiments were performed a nine times in the same way. In order to remove a noise and smoothen data, data preprocessing were performed using resampling method and moving average filter which has ten points. Then, we calculated a linear trend line equation, and analyzed a correlation between pill quantity and trend line equation. As a results, correlation coefficient was shown at 0.833 through using a Spearman's correlation method and we could be determined that data was continuos decreases when take a medicine.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.289-289
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• 2010

정상 세포로부터 암과 같은 종양세포를 제거하는 방법으로 암세포가 사멸되는 임계온도 보다 높게 악성조직에 열을 가하는 방법이 연구되어지고 있다 [1]. 전류가 흐를 수 있는 4개의 전기탐침을 종양조직에 삽입하여 국부적으로 열을 발생시키는 발열요법으로 암을 치료하는 연구가 고려되고 있다. 발열요법은 1960년대에 시작하여 우리나라에서는 1985년 연세 암센터에서 capacitive type의 RF heating 또는 전자파에 의한 국소가온법과 방사선치료와 병용으로 이용되고 있다. 주로 이용되는 방법은 Radio frequency heating, Microwave heating, ultrasound heating을 들수 있다. 라디오주파수는 보통 300 MHz 이하의 주파수를 가리킨다. 본 연구에서는 교류파 대신에 직류전원에 의해 열을 발생하는 경우에 관한 연구이다. 전극에 의해 형성되는 전기장에 대한 방정식은 전도매질에서의 DC 응용모드이고, 조직 내에서의 직류 전류에 의해 발생되는 온도 분포를 모델링하는 bioheat 방정식과 연계된 문제이다. 전기장에 의해 발생되는 열의 근원은 resistive heat 또는 Joule 열이다. 본 연구에서는 교류 전류에 의한 RF heating 대신 단순한 모델의 경우로 직류 전류에 의한 열 발생에 관한 이론적 연구를 수행하였다. 종양 조직 내에 삽입된 전극에 22V를 인가하면 60초 이내에 $80^{\circ}C$까지 급속히 증가 된 후, 서서히 $90^{\circ}C$에 까지 도달한다. 4 개의 전극에 대칭적인 전위가 인가 된 경우 $50^{\circ}C$ 이상의 온도 분포를 암 조직의 모양과 유사하게 분포하게 하여 효과적인 치료를 수행 할 수 있는 조건을 제시한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1184-1187
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• 2003

Electrochemical capacitors are becoming attractive energy storage systems particularly for applications involving high power requirements such as hybrid systems consisting of batteries and electrochemical capacitors for electric vehicle propulsion. A new type electric double layer capacitor (EDLC) was constructed by using carbon nanofibers (CNFs) and DAAQ(1,5-diaminoanthraquinone) electrode. Carbonaceous materials are found in variety forms such as graphite, diamond, carbon fibers etc. While all the carbon nanofibers include impurities such as amorphous carbon, nanoparticles, catalytic metals and incompletely grown carbons. We have eliminated of Ni particles and some carbonaceous particles in nitric acid. Nitric acid treated CNFs could be covered with very thin DAAQ oligomer from the results of CV and TG analyses and SEM images. DAAQ oligomer film exhibited a specific capacity as 45-50 Ah/kg in 4M $H_2SO_4$. We established Process Parameters of the technique for the formation of nano-structured materials. Furthermore, improved the capacitive properties of the nano structured CNFs electrodes using controlled solution chemistry. As a result, CNFs coated by DAAQ composite electrode showed relatively good electrochemical behaviors in acidic electrolyte system with respect to specific capacity and scan rate dependency.

• Smart Structures and Systems
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• 제7권5호
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• pp.365-378
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• 2011

Piezo-based active structural health monitoring (SHM) requires amplifiers specifically designed for capacitive loads. Moreover, with the increase in number of applications of wireless SHM systems, energy efficiency and cost reduction for this type of amplifiers is becoming a requirement. General lab grade amplifiers are big and costly, and not built for outdoor environments. Although some piezoceramic power amplifiers are available in the market, none of them are specifically targeting the wireless constraints and low power requirements. In this paper, a piezoceramic transducer amplifier for wireless active SHM systems has been designed. Power requirements are met by two digital On/Off switches that set the amplifier in a standby state when not in use. It provides a stable ${\pm}180$ Volts output with a bandwidth of 7k Hz using a single 12 V battery. Additionally, both voltage and current outputs are provided for feedback control, impedance check, or actuator damage verification. Vibration control tests of an aluminum beam were conducted in the University of Houston lab, while wireless active SHM tests of a wind turbine blade were performed in the Harbin Institute of Technology wind tunnel. The results showed that the developed amplifier provided equivalent results to commercial solutions in suppressing structural vibrations, and that it allows researchers to perform active wireless SHM on moving objects with no power wires from the grid.

• 한국산학기술학회논문지
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• 제20권6호
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• pp.604-609
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• 2019

본 논문에서는 열경화성 폴리이미드를 정전용량형 습도센서의 감습재료로 사용하여 공정이 간단한 IDT(Interdigitated) 전극을 갖는 정전용량형 습도센서를 제작하고 특성을 측정 및 분석하였다. 먼저 일정한 용량값을 얻기 위하여 용량형 센서의 전극 수, 전극의 두께와 간격 및 폴리이미드 감습막의 두께 등을 최적화하여 마스크 설계 및 제작을 했으며, 실리콘 기판 상에 반도체 공정 장비를 이용하여 정전용량형 습도센서를 제작하였다. 제작된 센서의 면적은 $1.56{\times}1.66mm^2$ 이며, 전극의 넓이와 전극간 폭은 동일하게 각각 $3{\mu}m$, 센서의 감도를 위해 전극 수를 166개, 전극의 길이는 1.294mm로 제작하였다. 그런 다음 센서 특성을 측정하기 위해 PCB상에 패키징 하였다. $25^{\circ}C$ 챔버 환경에 센서를 삽입하고 LCR Meter에 연결하여 1V, 20kHz를 인가한 상태에서 20%RH에서 90%RH까지 습도변화에 대한 용량값 변화를 측정하였다. 제작된 정전용량형 습도센서의 측정 결과 감도는 26fF/%RH, 선형 특성 < ${\pm}2%RH$ 그리고 히스테리시스는 < ${\pm}2.5%RH$를 얻을 수 있었다.

• 대한전기학회논문지:전력기술부문A
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• 제52권7호
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• pp.393-400
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• 2003

This paper discusses how to implement and verify a software model of the digital relay that can be added to real time digital simulator(RTDS) model library and is then subjected to the same outputs as the actual relay. The software model is stand-alone and can be used with real relays. It is also possible to conduct interactive real-time tests when the system effects of the relay action need to be investigated. The characteristics of mho type and the quadrilateral type, which is commonly used in recently developed relays, are modeled in this paper. Single circuit line and double circuit line system are used for model verification. The transmission lines are each 100 km in length and are modeled as distributed parameter lines but not frequency dependent. The transmission lines in the single circuit system are modeled as ideally transposed line. The mutual coupling data with the parallel line was taken account in the transmission lines for the double circuit system. The main CTs and PTs are included and operated in their linear region during the tests. For the purpose of testing the relay model accuracy the faults have been applied at various points on the protected line. Its accuracy is assessed against theoretical values.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.89-97
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• 2007

This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed half-bridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC buslines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the frequency range of 60 kHz under the principle of soft switching. The performance evaluations of the experimental setup are illustrated practically. The effectiveness of this new converter topology is proved for such low voltage and large current DC-DC power supplies as DC bus feeding from a practical point of view.

• 한국가스학회지
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• 제2권3호
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• pp.60-69
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• 1998

저온 플라즈마를 이용한 메탄 직접 전환반응은 진공에서 메탄만을 원료로 마이크로웨이브나 라디오 주파수(R.F)등의 에너지를 가하여 플라즈마 상태로 반응시켜 에틸렌, 에탄, 아세틸렌 등의 C2 화합물을 생성하는 방법이다. 이러한 직접적인 메탄 전환의 장점은 산소를 가하지 않으므로 산소에 의한 부생성물이 없는 점과 저온 플라즈마를 이용하므로 저에너지 공정이라는 것을 들 수 있다. 본 연구에서는 마이크로웨이브와 라디오 주파수(R.F)를 이용하여 저온 플라즈마 반응으로 메탄 전환반응을 수행하였고 일반적인 플라즈마 반응에 사용되는 관형반응기 외에도 독자적인 시리즈 반응기를 설계하여 성능실험을 수행하였다. 또한 플라즈마와 촉매를 이용한 반응실험을 수행 촉매의 영향을 확인하였다. 저온 플라즈마를 이용한 메탄 전환 반응의 특성을 분석한 자료는 공정의 실용화를 위한 반응기 설계 및 반응속도를 분석하기 위한 기초자료로 기대된다.