마이크로파 전력전송 기술과 무선 구동 EAPap 작동기

양상열 인하대학교 대학원 2012 국내박사

The power issue for smart actuators and devices is very important. Conventional power supply methods do not reach the required specifications of smart material actuators and devices. However, this has not been well investigated yet. To solve the power issue, this thesis investigates the microwave power transmission (MPT) technology and its demonstration for smart material actuators and wireless powered high altitude airship (HAA). In MPT technology, rectifying antenna, so called rectenna, is the most important component. Rectenna is composed of microstrip antenna and rectification circuit, Schottky diode. Dipole and patch rectennas design and characterization are involved in this thesis. Dipole rectennas were designed based on the microwave engineering theory, and computer simulation was conducted depending on the dipole width and gap distance between dipole arms by using Ansoft HFSS for antenna simulation and Designer for rectifier circuit. Designed rectennas were manufactured on a flexible circuit membrane (FCM), a cellulose film and a cellulose-polypyrrole-ionic liquid (CPIL) membrane by an etching process, a screen printing process and a lift off process, respectively. Schottky barrier diodes were soldered on the middle of dipole arms. To confirm reliability of simulated result, antenna characterization was completed using network analyzer (NA) and spectrum analyzer (SA). The antenna simulation resulted in that resonance frequency of a dipole antenna, with dipole gap size of 0.6 mm and dipole width of 0.8 mm, is 8.65 GHz and return loss (RL) is -26.3 dB. And using NA, the resonance frequency and RL of the dipole antenna were measured to be 8.4 GHz and -21.1 dB, respectively. Based on the MPT test results, wirelessly-driven EAPap actuator and microwave powered HAA were demonstrated to prove a possibility of MPT. Several configurations of rectenna arrays were designed and tested to meet the power requirement for the application devices. All of microwave test were performed in the microwave anechoic chamber. The maximum converted power output of a S2-P2 flexible dipole rectenna array was about 3.1 V with 10.6 mA (32.9 mW) at 9.7 GHz. S3-P3 was 4.7 V with 17 mA (80 mW) at 9.7 GHz, and S2-P45 was 4 V, 185 mA (0.74 W) at 10.3 GHz. From the test results, S3-P2 dipole rectenna array was applied to the flower actuator, S3-P3 dipole rectenna array for the dragonfly actuator, and S2-P45 dipole rectenna array for the HAA. Using these rectenna arrays, flower actuator, dragonfly actuator and microwave powered HAA were successfully demonstrated. Microwave power transmission technology is proven to be useful for wireless smart material actuators and devices. 지능재료를 이용한 작동기나 응용장치를 개발함에 있어서 에너지를 공급하는 문제는 쉽게 해결하기 어렵다. 전통적인 에너지 공급 방법이나 시스템으로는 재능재료를 이용한 장치들의 요구 조건을 부합시키기에 제약이 있기 때문이다. 이 문제를 해결하기 위하여 본 논문에서는 지능재료 작동기와 무선전력 구동 High Altitude Airship (HAA) 를 위한 마이크로파 무선전력전송기술에 대한 연구를 수행하였다. 마이크로파 무선전력전송기술에서는 렉테나 (rectenna)라 불리는 정류 안테나가 가장 중요한 요소인데, 렉테나는 마이크로파를 송수신하는 안테나와 정류회로가 결합되어 마이크로파를 직류로 정류하여 전원을 공급해 주는 요소이다. 본 논문에서는 다이폴과 패치 렉테나의 설계, 컴퓨터 시뮬레이션을 이용한 해석과 실험적 평가를 통하여 해석 결과를 검증하였다. 렉테나는 마이크로웨이브 공학의 이론에 기반하여 설계하였고 비교 평가를 위하여 컴퓨터 시뮬레이션이 수행되었다. 설계된 안테나는 다이폴의 폭과 다이폴 간의 간격의 차이에 따라 컴퓨터 시뮬레이션을 수행하였고, 소프트웨어는 안테나 해석에 Ansoft사의 HFSS, 정류회로의 해석에 동사의 Designer를 이용하였다. 설계된 렉테나는 Flexible Circuit Membrane (FCM), 셀룰로오스 필름과 Cellulose-Polypyrrole-Ionic Liquid (CPIL) 필름에 각각 에칭 기법, 스크린 인쇄기법, 리프트-오프(lift-off) 기법을 이용하여 제작하였다. 렉테나의 정류회로의 중요 요소인 쇼트키 다이오드 (Schottky diode)는 제작된 안테나의 중앙에 부착하였다. 컴퓨터 시뮬레이션 결과의 신빙성을 확인하기 위하여 제작된 렉테나를 마이크로파 무향실에 설치하고 네트워크 분석기와 스펙트럼 분석기를 이용하여 안테나 특성평가를 수행하였다. 그 결과 다이폴 간의 간격 0.6 mm, 다이폴의 폭 0.8 mm 인 안테나의 경우 시뮬레이션에서 공진 주파수는 8.65 GHz, 반사손실 -26.3 dB 였고, 네트워크 분석기에 의한 실험에서는 8.4 Ghz, 반사손실 -21.1 dB 으로 해석값과 유사한 경향을 보였다. 이 성능평가를 기반으로 마이크로파 무선전력전송 기술의 가능성을 보여주기 위하여 무선구동 Electro-Active Paper (EAPap) 작동기와 마이크로파로 구동되는 HAA 의 작동실험을 시연하였다. 작동기의 구동에 필요한 전력을 공급하기 위해 다양한 형태의 배열 안테나가 설계 되었고 마이크로파 무선전력전송에 대한 성능평가가 수행되었다. 모든 마이크로파 실험은 마이크로파 무향챔버 안에서 진행했다. S2-P2 유연 다이폴 렉테나 배열의 경우 3.1 V, 10.6 mA (32.9 mW), S3-P3는 4.7 V, 17 mA (80 mW) 의 값이 9.7 GHz 에서 각각 측정되었다. 그리고 S2-P45는 4V, 185 mA (0.74 W) 가 10.3 GHz 에서 측정되었다. S3-P2 다이폴 배열은 flower actuator 에 적용되었고, S3-P3 다이폴 배열은 dragonfly actuator에 적용되었다. 또한 S2-P45 다이폴 렉테나 배열은 HAA 의 요구 성능에 맞게 설계되었다. 각각의 배열 다이폴 렉테나는 무선구동 flower actuator, dragonfly actuator 와 마이크로파로 구동되는 HAA 동작에 대한 시연을 하였다. 본 연구를 통하여 마이크로파 전력 전송기술이 지능재료 작동기와 응용장치들에 적용할 수 있음을 보여 주었다.

Microwave로 가열한 분쇄 돈육 패티의 지방 및 수분 첨가수준에 따른 품질특성과의 상관관계에 관한 연구

최지훈 건국대학교 대학원 2005 국내석사

한글초록:본 연구는 microwave로 가열한 분쇄 돈육 패티의 지방 및 수분 첨가 수준(0%, 5%, 10%, 15%, 20%, 25%)에 따른 품질특성 변화를 살펴보고 이들과의 상관관계를 조사하였다. 패티의 중심온도가 75℃가 되도록 가열하였고 가열속도, 전체 가열감량, 가열드립감량, 증발감량, 전단력, 직경 및 두께 감소율을 조사하였다. 그 결과를 요약하면 다음과 같다. 1. 지방 첨가수준에 따른 분쇄 돈육패티의 품질특성과의 상관관계1) 지방 첨가수준과 가열속도와의 상관관계는 고도의 유의성을 보였지만(p<0.001), 두 항목 간에는 낮은 상관계수(r=0.40)를 보였으며 낮은 적합성(R2=0.4142)을 보였다.2) 지방 첨가수준과 전체 가열감량 사이에는 매우 높은 상관도와 유의성을 보였고(r=0.89, p<0.001), 매우 높은 적합도(R2=0.9104)를 보였다.3) 지방 첨가수준에 따른 가열드립감량은 고도의 유의성이 있는 정(+)의 상관도를 보였으며(r=0.92, p<0.001), 매우 높은 적합도(R2=0.8986)를 보였다. 증발감량 간에는 높은 유의성을 보였으나, 낮은 부(-)의 상관도를 보였고(r=-0.38, p<0.001), 낮은 적합도(R2=0.3269)를 보였다.4) 지방 첨가수준과 전단력과의 상관관계는 고도의 유의성을 보였으며 매우 높은 부(-)의 상관도를 보였고(r=-0.86, p<0.001), 매우 높은 적합도(R2=0.954)를 보였다.5) 지방 첨가수준과 직경 감소율과의 상관관계를 본 결과, 매우 낮은 상관도를 보였으며 유의성이 나타나지 않았고(r=0.13, p>0.05), 낮은 적합도(R2=0.1371)를 보였다. 지방 첨가수준과 두께 감소율과의 상관관계는 매우 낮은 상관도를 보였으며 유의성이 나타나지 않았고(r=-0.01, p>0.05), 낮은 적합도(R2=0.242)를 보였다.2. 수분 첨가수준에 따른 분쇄 돈육 패티의 품질특성과의 상관관계1) 수분 첨가수준과 가열속도와의 상관관계는 고도의 유의성을 보였으며, 높은 상관관계를 보였고(r=0.69, p<0.001), 낮은 적합도(R2=0.4848)를 보였다.2) 수분 첨가수준과 전체 가열감량과의 상관관계는 매우 높은 유의성을 보였고(p<0.001), 고도의 상관도를 보였으며(r=0.95), 두 항목 간에 적합도는 매우 높았다(R2=0.9146).3) 수분 첨가수준과 가열드립감량과의 상관관계는 매우 높은 정(+)의 상관관계를 나타내었고(r=0.94, p<0.001), 매우 높은 적합도(R2=0.9151)를 보였다. 증발감량 간에는 고도의 유의성을 보였으며 부(-)의 상관관계를 보였지만(r=-0.62, p<0.001), 낮은 적합도를 보였다(R2=0.3913).4) 수분 첨가수준과 전단력과의 상관관계는 고도의 유의성을 보였지만 낮은 부(-)의 상관도를 보였고((r=-0.39, p<0.001), 매우 높은 적합도를 보였다(R2=0.157).5) 수분 첨가수준과 직경 감소율과의 상관관계는 높은 상관도를 보였지만(r=0.63, p<0.001), 낮은 적합도(R2=0.4113)를 보였다. 수분 첨가수준과 두께 감소율과의 상관관계는 직경 감소율보다 더 높은 상관도를 보였으며(r=0.89, p<0.001), 상당히 높은 적합도(R2=0.8379)를 보였다 영문초록: This study was carried out to elucidate the relationship between different levels of fat or water (0%, 5%, 10%, 15%, 20% and 25%) and quality characteristics(cooking rate, total cooking loss, cooking drip loss, evaporation loss, shear force and reduction in diameter and thickness) of ground pork patties cooked to reach 75℃ of internal temperature by microwave. The results obtained were summarized as follows;1. The relationship between fat level and quality characteristics of ground pork patties cooked by microwaveThe correlation coefficient between fat level and cooking rate of ground pork patties cooked by microwave was highly significant, but was low(r=0.40, p<0.001). The relationship between two measurements was a low determination coefficient(R2=0.4142). The relationship between fat level and total cooking loss of ground pork patties cooked by microwave had highly significant coefficient(r=0.89, p<0.001). The correlation coefficient between fat level and cooking drip loss of ground pork patties cooked by microwave was 0.92, which was highly significant(p<0.001). But the correlation coefficient between fat level and evaporation loss had a lower negative value(r=-0.38, p<0.001). There was very significant relationship between fat level and shear force of ground pork patties cooked by microwave(r=-0.86, p<0.001). There were no strong relationships between fat level and reduction in diameter(r=0.13, p>0.05) or thickness(r=-0.01, p>0.05) of ground pork patties cooked by microwave.2. The relationship between water level and quality characteristics of ground pork patties cooked by microwaveThe correlation coefficient between water level and cooking rate of ground pork patties cooked by microwave was highly significant, and was high(r=0.69, p<0.001). The relationship between water level and total cooking loss of ground pork patties cooked by microwave had highly significant coefficient(r=0.95, p<0.001), and a low determination coefficient between two measurements was very high(R2=0.9146). The correlation coefficient between fat level and cooking drip loss of ground pork patties cooked by microwave was 0.94, which was highly significant(p<0.001). The correlation coefficient(r=-0.38) between fat level and evaporation loss had a negative value(p<0.001). Although significant correlation on the relationship between water level and shear force was found(p<0.001), a correlation coefficient was low negative(r=-0.39). There was very significant relationship between water level and reduction in diameter(r=0.63, p<0.001) or thickness (r=0.89, p<0.001) of ground pork patties cooked by microwave

Microwave 가열에 의한 식빵 발효의 최적화에 관한 연구

박상준 경희대학교 대학원 2009 국내박사

ABSTRACT A Study on Optimizing Bread Fermentation through Microwave Heating Park, Sang Jun Adviser : Prof. Lee, Kwang Suck Dept. of Culinary Science and Food Service Management Graduate School, Kyung Hee University In order to streamline bread making process that is time-consuming in regard to the characteristics of process, this study focused on microwave irradiation to dough and raising its temperature to monitor potential variations of dough properties and bread quality, and also examined optimum irradiation time, mixture ratio and dough-mixing method to deduce effective ways for streamlining bread making process. To meet the above purposes, this study measured the content of crude ash, moisture and wet gluten in wheat flour available in domestic market, and every bread was prepared by AACC method and straight dough-mixing method (used commonly in domestic bakeries) depending on variable time of microwave irradiation. Microwave was directly irradiated to every dough to heat up its temperature for analysis on dough properties and bread quality, which was followed by deducing optimum time of microwave irradiation. Based on the optimum time of microwave irradiation, this study sought to compare and analyze the quality of three bread sample groups, i.e. straight dough group (control), emergency dough group (EM) and microwave irradiation group (MWH). In order to determine potential effects of mixture materials on microwave absorption, this study sought to compare and analyze quality of bread samples that were prepared with variable mixture of salt and fat. In each step of experiment, dough temperature, pH, fermentation rate, specific volume, oven spring and water activity were measured, and crumbScan, texture analyzer and sensory evaluation were performed to compare and analyze quality of bread. Experiment 1: According to comparison and analysis on dough properties depending on the time of microwave irradiation, it was found that MWH 2 dough (as irradiated every 80 seconds) showed the most ideal dough temperature. According to comparison and analysis on quality of bread samples, it was found that MWH 2 showed the highest specific volume and oven spring of all and the lowest hardness (i.e. the highest softness). Moreover, MWH 2 scored the highest points in overall preference under sensory characteristics. As a result, it found that 80-second heating of 700g bread dough, when exposed to microwave irradiation, contributed to the highest quality of bread. Experiment 2: For comparison and analysis on bread quality depending on dough-mixing methods, this study sought to compare and analyze the quality of three major bread sample groups, i.e. MWH 80 (a sample scoring the highest points in specific volume, texture and sensory test in the above quality analysis under certain time of microwave irradiation), emergency dough group (EM) and straight dough group without microwave irradiation (control). As a result, it was found that EM had higher specific volume and oven spring than control, but had highest hardness of all under texture test. According to the sensory acceptance, it was found that EM tended to smell much of yeast and sourish, and scored the lowest points in overall acceptance. On the other hand, it was found that MWH 80 had the highest softness under texture test, scored the highest points in overall acceptance under sensory characteristics, and there were significant differences among samples on statistical basis. Experiment 3: According to comparison and analysis on dough properties and bread quality depending on mixture materials, it was found that Salt 2 (dough with salt added relatively much) had the highest dough temperature of all, and Salt 1 had the highest fermentation rate and specific volume but the lowest hardness (i.e. highest softness). According to sensory characteristics, it was found that Salt 1.5 scored highest points in sweet taste, aftertaste, and overall acceptance, but there were significant differences among bread samples. Likewise, it was found that Fat 6 (dough with fat added relatively much) had the highest dough temperature, and had the highest fermentation rate and specific volume of all. According to texture analysis, it was found that Fat 0 had the highest hardness of all. And according to sensory characteristics, it was found that Fat 3 scored the highest points in overall acceptance. Summing up, it is concluded that it takes 80 seconds to efficiently irradiate microwave; microwave heating method is superior to emergency dough method in the aspect of dough properties and bread quality; and the optimum mixture ratio of salt and fat for microwave-irradiated bread is 1.5% salt and 3% fat.

Microwave 및 인산염계 방염제로 복합처리한 고내구성 구조용 목재 개발을 위한 실험적 연구

박철우 동명대학교 2009 국내석사

본 연구에서는 일반 구조용 목재(S.P.F)의 방염처리를 위해서 건조시간을 단축시켜 방염성능 및 내구성능의 향상을 도모하고자 Microwave로 목재를 건조시켜 인산염계 방염제에 시간별로 침지시킨 후 2차로 Microwave 가열을 한 다음 38㎜의 두께에서 10㎜를 압축 시켜 구조용 S.P.F 그룹의 방염 후 처리물품 시험 및 내구성 시험(경도시험, 못뽑기 저항시험, 압축 시험)을 실시한 결과 다음과 같은 결론을 얻었다. Microwave 1차 가열 후 방염성능은 인산염계 방염제에 30분간 침지된 시험편이 가장 우수한 것으로 나타났으며 2차 가열시 약간의 방염제 손실이 나타났으나 인산염계 방염제의 구성 비율 중 가장 큰 수분의 증발이 대부분일 것으로 사료되며 방염성능을 유지할 수 있는 순수 약제만이 압축된 목재와 함께 고밀화 되어 방염성능 향상에 기여한 것으로 판단된다. 또한 내구성 시험 결과 경도는 Plain에 비하여 방사단면은 62%, 접선단면은 60%, 횡단면은 23% 이상의 성능향상을 나타내었으며, 못뽑기 저항은 2배 정도의 저항성능 향상을 나타내었다. 섬유방향 압축 시험에서 강도는 4배, 비례한도 응력은 2.5배, 탄성계수는 3.5배 이상의 높은 성능 향상을 나타내었다. 이와 같은 내구성능의 향상은 고온으로 가열하여 목재의 섬유조직이 연해지면 수분의 기화가 쉽게 이루어지는데 이 상태에서 압축을 하게 되면 부피에 대한 목재 실질적인 양이 많아져서 내구성이 증가하게 된 것으로 판단된다. 이상 실험의 결과와 같이 Microwave로 단시간에 구조용 목재를 균일 건조함으로써 건조결함 및 뒤틀림 등의 품질 저하를 최소화 시키며 기존의 방염제보다 친환경적인 인산염계 방염제로 대체하여 천연질감 및 느낌을 그대로 살리면서 방염성능을 향상시킴은 물론, 압축을 통한 고내구성의 구조용 목재를 생산하게 된다면 유지관리에 대한 경제성, 환경친화적인 제품으로써의 이미지, 내구연한이 큰 목조주택의 건설 등 그 효율성 등에서 상당한 효과를 이룰 것으로 예상된다. A concern over a research and development for an improvement in flame resistant efficiency & duration rises higher and higher in proportion to an increase in wood use, followed by a launch of wood product with high efficiency, but most structural woods among them are used for construction without the addition of the flame retardant substituting flame-resistive plasterboard, the method which should be reduced for a cutoff of economic loss. To decrease such situation, wood seasoning time for flame resistant should be shortened along with strengthening them very high level and the structural woods should be colorless. scentless flame-resistive state for the use. Accordingly. this study will carry a work that letting the phosphate flame resistant agent to permeate evenly into the empty space in where the free water and bound water, which are in the cell & lumen internal wood, are evaporated in the microwave within a short time, and compress them to a certain thickness for duration improvement, for the deduction of a basic data for the development of high durability flame resistive and environment friendly structural wood without deforming against a shortened wood seasoning time, weather change and effect of natural environment and harmless to human body For the basic data deduction, a practical operation was carried out for an increase in flame resistant & duration efficiencies under the condition of shortened seasoning time in processing flame resistant such as seasoning the ordinary structural woods(S.P.F)in the microwave and dipping them in the phosphate flame retardant, and heated them secondly in the microwave followed by compressing them from 38㎜ to 10㎜ in thickness and put them into flame resistant process and then went through the test for the goods subject to the process & duration(test for hardness, extraction resistance of nails, compression), and got the results as follows. 1. The proper heating hour in the microwave for mixed S.P.F wood reached to the target percentage (4~5%)of water content when they went through the order of artificial seasoning (K.D.:Kiln Dry, under 19% of water content percentage), being processed by 290×190㎜, the first heating of the test piece for 7minutes at 5㎾, and the result of second heating for 9minutes at 3kw after dipping them in the phosphate flame retardant showed that all the test pieces satisfied the optimum water content percentage of external structural wood, the range of 12~14%, and the test pieces were free from shrinking, swelling, surface fracturing after a repetition of water suck up and drain under the natural state after compression being restored to their faultless original condition. 2. Regarding the flame resistant efficiency of mixed S.P.F woods after flame resistant process and compressed, the test pieces which was put in the phosphate flame retardant for 30 minutes showed the best condition, and its improvement seemed to be caused by an increase in flame resistant agent's permeation during the dipping times prolonged after seasoned evenly with microwave, and in loss of some flame resistant agent at the time of second heating, it seemed to be the evaporation of the water which takes the largest percentage among the flame resistant agent components ending up a densification of only pure agent by which flame resistant efficiency can maintain contributing to the rise of flame resistant efficiency with compressed woods. 3. The test results of the mixed S.P.F woods which went through flame resistant and compression process showed the rise in hardness by 62 % for radial section, 23 % for cross section compared with Plain, and extraction resistance of nails showed its increased efficiency about twofold. In respect to grain direction, they showed the rise of quadruple for hardness, 2.5 times for proportional limit stress, 3.5 times for elastic modulus. Such duration efficiency increase seemed to have caused by those steps such as heating the woods with high temperature to soften the fibrous tissue which makes water to evaporate very rapidly and that's the very state that the substantial quantity of woods to the volume caused by a compression resulting in a rise in duration. Provided that seasoning the structural woods evenly in a short time in the microwave minimizing a deterioration such as seasoning defects, warp letting natural touch & feel out by substituting environment friendly phosphate flame retardant for ordinary one for the production of structural woods with increased flame resistant efficiency and high duration by compression, a considerable effect would occur in maintenance related economic efficiency, in image as the environment friendly products, and in cost cut off for flame resistant & fireproof process, and a better efficiency & economic increase would be expected as the structural woods by layering a data based on this study of various tests, that is, long term duration & tension, impact, warp, compressibility.

Microwave를 이용한 흡착제의 유기용제 탈착특성 연구

송병식 全北大學校 大學院 2004 국내석사

In the absorption method, the separation and desorption technology via microwave is emerging as a process to remove and collect volatile organic chemicals, and great interests are concentrated on it, recently. Characteristics of desorption and impact of microwave upon absorbents according to power were studied. A commercial activated carbon, a natural zeolite, a synthetic zeolite, and a manufactured sintering absorbent consisted of zeolite and alumina were selected as absorbents. After solvents, such as TCE, benzene, were absorbed into and on to the absorbents, the absorbents were stored in the a quartz tube which was set up at the center of the 1Kw microwave chamber. The desorption efficiencies of the solvents from the absorbents were measured as changing microwave power from 200W-600W. The deformation of the absorbent according to microwave power was also examined. As an important result of this research, the manufactured sintering absorbent had relatively high desorption efficiency among the absorbents. The solvents were desorbed in a relatively short time compared to the other absorbents with 600W microwave power, and there was no any deformation on the surface of the manufactured sintering absorbent due to the microwave power. The other absorbents had a local heating point or a deformation on the surfaces with the 600W microwave power. The natural zeolite was not heated up to an ignition temperature under the power, however it was sintered and its surface color was changed after complete desorption. The commercial activated carbon had a relatively high dielectric constant, it was rapidly heated up and burned under the microwave power. Therefore it was not acceptable as a desorber when a microwave power was

Microwave 공정에 의한 hardmetal powders의 소결

송강석 京畿大學校 大學院 2002 국내석사

절삭공구 및 금형 재료인 WC-Co 초경함금 분말을 2.45GHz의 multi-mode microwave를 이용하여 Ar 분위기에서 hybrid heating 방법에 의해 소결하였다. WC의 입자 크기는 0.2㎛와 0.4㎛를 사용하였으며 Co의 함량을 6wt%와 10wt%로 각각 합성하여 소결 하였으며 Co의 함량을 6wt%와 10wt%로 각각 합성하여 소결 하였고, 소결온도는 1250℃∼1350℃의 온도 범위에서 10분과 30분 동안 유지하였다. 마이크로웨이브를 통해 hardmetal을 소결시에는 micro-plasma를 발생하여 시편의 밀도가 89%∼99%의 균일하지 못한 밀도분포를 발생한다. 따라서, lubricant인 paraffin을 2wt% 함유하여 micro-plasma의 발생을 억제시켰고, 96%∼97%범위의 균일한 밀도분포를 얻을 수 있었다. 마이크로웨이브로 소결된 시편의 물성은 기존의 전기로에서 소결된 시편의 물성에 상응하는 경도 및 강도를 얻을 수 있었다. 1350℃에서 30min 유지하여 WC의 입자 크기가 작은 0.2㎛이고 6wt% Co를 함유한 경우 밀도와 경도가 99%와 20GPa로 높은 값을 가졌고 강도는 8.1MPam^(1/2)이었으며, 10wt% Co를 함유한 경우 밀도는 96%이고, 경도는 18GPa이었으며 강도는 9.1MPa^(1/2)였다. Co의 액상량의 증가로 밀도와 경도는 감소하였지만 파괴강도는 증가하였다. VC와 Cr_(3)C_(2)의 첨가제를 첨가하여 정상적인 입자성장과 비정상적인 입자성장을 억제시킬 수 있었고, 첨가제 없이는 비정상적인 입자 성장을 억제시킬 수 있었다. WC-6wt% Co에 0.5%VC를 첨가하여 1350℃에서 10분유지 시켜 소결하였을 경우 보다 WC-6wt%Co에 0.5%Cr_(3)C_(2)를 첨가하여 같은 조건으로 소결한 경우가 밀도와 경도는 낮지만 강도는 7.9MPam^(1/2)에서 8.2MPam^(1/2)로 증가하였다. WC-Co hardmetal powder was sintered in a cylindrical cavity operating by a 2.45GHz multimode microwave applicator in Ar atmosphere. Specimens were sintered by hybrid-heating system that was heated by SiC susceptor in an insulation box. The WC particle size was 0.2㎛ and 0.4㎛ and Co content was 6wt% and 10wt% respectively. Specimens were sintered at 1250℃, 1300℃ and 1350℃ and soaking time was 10min and 30min at the maximum temperature respectively. WC-Co powders with 2wt% paraffin inhibited the micro-plasma and showed more uniform microstructure than those without paraffin. WC-6wt%Co(0.2/㎛) specimen sintered at 1350℃ for 30min by microwave showed relative density, hardness and toughness of 99%, 20Gpa and 8.1MPam1/2 respectively and of 96%, 18Pa and 9.1MPam1/2 for (0.2㎛)WC-10wt%Co under the same condition. Density and hardness were reduced with the increase of Co content, but toughness was increased. WC-Co specimens sintered by microwave inhibit the abnormal grain growth without additives and mechanical properties of specimens sintered with grain growth inhibitors, such as VC or Cr3C2, were less than the values without additives in microwave sintering process. As a conclusion of this study, sintering of WC-Co powder by microwave lowered the sintering temperature around 100℃ and finished in less than a half time than by the conventional sintering method with a vacuum electric furnace. Microwave-sintered WC-6wt%Co(0.2㎛) specimen sintered at 1350℃ for 30min by microwave showed the best mechanical properties. Sintering is enhanced in a microwave field and these results could be explained as "microwave effect".

Microwave를 통해 形成된 MWCNT 缺陷 위의 白金 나노 粒子 담지 擧動

이용인 성균관대학교 일반대학원 2010 국내석사

환경 친화적인 에너지 기술이 각광 받으면서, 연료전지는 차세대 전원으로써 많은 그룹에서 연구가 진행되고 있다. 연료전지의 효율은 support의 전기적 특성, 촉매의 종류 및 크기 등에 의해 결정되는데, carbon nanotube (CNT)는 넓은 비표면적, 우수한 전기전도도, 내산성 등의 특징을 갖고 있기 때문에 연료전지의 support로써 주목 받고 있다. 본 연구에서는 multiwalled carbon nanotubes (MWCNTs)의 표면에 microwave treatment를 이용하여 인위적으로 defects을 발생시킨 뒤, defects 정도에 따른 platinum nanoparticles (Pt NPs)의 담지 거동에 관해 연구를 진행 하였다. 1500°C에서 2 시간 열처리 해준 MWCNTs를 사용하였으며, HNO3와 산화제를 첨가한 solution을 이용하여 1분 ~ 4분간 microwave treatment 해 줌으로써 MWCNTs의 표면에 defects을 인위적으로 발생시켰다. Pt precursor로써 PtH2Cl6&#8226;6H2O를 이용하여 MWCNTs에 Pt NPs을 담지 시켰다. 먼저, TGA 분석을 통해 목표한 담지량 Pt 40 wt.%를 확인하였다. Pt NPs 담지 후 pure Pt와 탄소 만이 검출되는 것을 확인할 수 있는데, 이는 electrochemical potential 차이로 인해 Pt2+가 pure Pt로 자발적으로 환원이 되기 때문이다. [1] Raman spectroscopy를 이용하여 defects의 양을 측정해 본 결과, microwave treatment 시간이 증가할수록 defects의 양이 증가함을 확인하였고, MWCNTs에 Pt NPs을 담지 한 후에는 defects의 양이 줄어드는 것을 확인하였다. 이 사실은 Pt NPs의 담지 거동이 MWCNTs의 defects 양과 밀접한 관련이 있음을 암시하고 있으며, TEM 고분해능 이미지를 통하여 Pt NPs이 defect sites에 담지 되는 것임을 확인할 수 있었다. Pt NPs이 MWCNTs의 defect sites에서 담지가 되는 이유는 Pt NPs이 다른 곳보다 defect sites에 위치할 경우 더 강한 adsorption energy를 갖기 때문이다. [2] 이러한 이유 때문에 defect site는 Pt NP의 nucleation site 역할을 하게 되고, 결과적으로 별도의 분산제 없이 고른 분포의 Pt NPs을 얻을 수 있게 된다. 수율이 낮아서 실험에서 제외한 4분 시편을 제외하면, 3분 microwave treatment 한 시편이 1 ~ 5 nm의 가장 작은 Pt NPs이 담지가 되었으며, 가장 균일한 분포를 가지고 있는 것을 TEM 이미지를 통해서 확인하였다. 마지막으로 cyclic voltammetry를 이용하여 methanol oxidation 거동을 확인한 결과, 3분 시편의 경우에 가장 높은 If/Ib 값(1.21)이 측정되었으며, 이는 우수한 methanol oxidation 거동을 나타낼 수 있음을 의미한다. [3, 4] 이처럼 최적화된 microwave treatment를 이용한다면, 비교적 단순한 공정을 통해 신뢰성 높은 Pt/MWCNT composites을 제작할 수 있으며, 연료전지, 수소 저장체 등의 응용분야에 적용할 때 성능향상에 도움이 될 것이라 예상된다. As an eco-friendly energy technology, fuel cell has been suggested for a promising power source. The essential components of efficient fuel cell are determined by a kind of catalysts and its size with mono-dispersion on various supporting materials, which rely on the loading method. Carbon nanotubes (CNTs) have received great attention for their application as catalyst support due to their interesting properties such as large surface area, electronic conductivity and resistibility to acid/base media. We developed a simple and efficient method to load Pt nanoparticles (NPs) uniformly on defects generated in multiwalled CNTs (MWCNTs) without using reduction agents or organic reagents. Defects on the surfaces of MWCNTs were artificially generated by microwave treatment at various exposure times. After defects generation process, we loaded Pt NPs on MWCNTs by using PtH2Cl6&#8226;6H2O, as a precursor. Nucleation of Pt NPs occurs on the defect sites spontaneously due to an innate electropotential difference. Because of the correlation between defects and Pt NPs, we were able to control the size of Pt NPs by changing defect size, quantity and distribution, which was confirmed by Raman spectroscopy and TEM. After microwave treatment for 3 min, more uniform and smaller Pt NPs were observed. Also, the defects via microwave treatment make adhesion of Pt NPs stronger, which can be helpful to improve the reliability for applications. Finally, the methanol oxidation behavior of MWCNTs with Pt NPs was examined by cyclic voltammetry (CV).

Microwave 및 세정산발효를 이용한 유기성 슬러지의 감량화 및 자원화

이원식 경북대학교 대학원 2006 국내석사

This work elucidates the effects of pretreatment of the organic sludge from wastewater treatment plant by microwave irradiation on elutriated acid fermentation. Finally, ultimate aim of this work is to study application abilities of sludge minimization and reuse. These experiments typically fell into two process; pretreatment as microwave irradiation and elutriated acid fermentation for hydrolysis and acidification as main treatment of primary sludge. The results of maximum solubilization rate of primary 1,2 and secondary sludge were 0.2, 0.12 and 0.07 gSCODprod./gICODin and the optimum irradiation time of microwave on 2,450 MHz and 900 W were 5 min. for primary sludge and 7min. for secondary sludge. From batch tests on elutriated acid fermentation that was used the pretreated primary sludge as microwave, the optimum pH and HRT(hydraulic retention times) were 7 and 5 days at 35℃ condition, meaning that the result of this condition is higher than others on SCOD(soluble chemical oxygen demand) and VFAs(volatile fatty acids) production. Based on the results of the batch tests, bench scale elutriated acid fermentation which was used the pretreated primary sludge as microwave was performed at pH 7 and 35℃. On stable results from bench test, SCOD production was 0.12~0.13 gSCOD/gVSfed., VS(volatile solid) reduction in pretreatment as microwave and in connected process as acid fermentation were approximately 15 and 56%, volume reduction were approximately 12 and 59%.

Microwave-Assisted Catalytic Thermochemical Conversion of Organic Solid Wastes for Biofuels Production

Liu, Shiyu ProQuest Dissertations & Theses University of Minn 2019 해외박사(DDOD)

Organic solid wastes (e.g. agricultural residues, industrial residues, municipal solid waste, and others) as a renewable and abundant energy resource have received a tremendous amount of interest from all over the world to be used as a feedstock for the production of biofuels and chemicals. Using microwave-assisted thermochemical conversion technology, organic solid waste resources with low energy density can be converted into clean and high energy density biofuel including bio-oil, combustible gases, and other high-quality fuel products. In this dissertation, co-pyrolysis of corn stover and scum was studied with an aim to improve the bio-oil quality. In addition, sequential two-step catalytic fast microwave-assisted pyrolysis of biomass on a packed-bed HZSM-5 catalyst was investigated to determine the optimal catalytic upgrading temperature and catalyst stability. Furthermore, a benchtop continuous fast microwave pyrolysis system was designed and fabricated. Sewage sludge was used as the feedstock in the testing of the continuous microwave-assisted pyrolysis system. The potential energy recovery from each product was investigated. Moreover, a continuous microwave-assisted pyrolytic gasification mini-plant (6kg/h) was designed, developed, and fabricated. Performance of the continuous microwave-assisted pyrolytic gasification mini-plant was investigated. The main achievements of this research are as follows:In Chapter 3, co-pyrolysis of corn stover and scum was investigated to improve the bio-oil quality. Experiments were conducted based on the batch microwave-assisted pyrolysis reactor. Scum was used as a hydrogen-donor to increase the effective hydrogen index (H/Ceff). A significant synergistic effect between corn stover and scum was achieved to maximize the production of bio-oil and aromatic hydrocarbons when the H/Ceff value exceeded 1. CaO and HZSM-5 were used as the catalysts to improve the bio-oil quality. The addition of CaO catalyst increased both the bio-oil yields and aromatic yields. The possible reaction mechanism can be surmised as follows: when pyrolysis vapor passed through the mesoporous CaO catalyst, the heavy compounds such as large phenols and anhydrosugars were cracked into light compounds, followed by conversion of the light compounds into hydrocarbons over the microporous HZSM-5 catalyst. The optimal co-pyrolysis temperature, CaO to HZSM-5 ratio, and corn stover to scum ratio were 550 째C, 1:4, and 1:2, respectively.In Chapter 4, sequential two-step catalytic fast microwave-assisted pyrolysis of biomass was developed to find out the optimal catalytic upgrading temperature and the stability of catalyst. A newly developed sequential two-step catalytic fast microwave-assisted pyrolysis of biomass through a packed-bed HZSM-5 catalyst for high quality bio-oil production was developed and investigated. Through the sequential two-step fMAP set up, the pyrolysis and catalytic cracking and upgrading processes can be flexibly and independently controlled, and the catalyst recovery and regeneration process is simplified. In addition, the catalyst bed temperature and catalyst loading significantly affected the product distribution. The optimal pyrolysis and catalyst bed temperature were 550 째C and 425 째C, respectively. The highest bio-oil yield (33.38 wt. %) and maximum proportion of aromatic compounds (26.20 %) were achieved. Furthermore, increasing the catalyst loading reduced the bio-oil yield but improved the bio-oil quality. Moreover, X-ray Diffraction (XRD) analysis was conducted on the fresh, spent and regenerated HZSM-5 catalyst samples, and the catalyst characterization indicated a good stability of HZSM-5 catalyst during the upgrading process.In Chapter 5, a continuous fast microwave pyrolysis system was developed based on Chapter 4 and was used for sewage sludge utilization. A benchtop continuous fMAP system for ex-situ catalytic upgrading of the pyrolytic vapors was designed, fabricated and tested. After examining the effects of pyrolysis temperature on the physical, chemical, and energetic properties of the products, it is concluded that the optimal pyrolysis temperature for maximum overall energy recovery is 500 째C, at which the total Qrecovery is 18.42 MJ/kg with energy values of bio-oil, gas and biochar are 7.16 MJ/kg, 8.69 MJ/kg and 2.57 MJ/kg, respectively. In addition, SEM micrographs of sewage sludge and biochar samples showed that the raw sewage sludge had relatively smooth surface while the biochar had rough surface and porous structure. The formation of the pores of biochar may be due to the evaporation of water and emission of volatile matter during the pyrolysis process. Furthermore, high HHV of bio-oil (20.61 MJ/kg) and gas (22.5 MJ/Nm3) imply that sewage sludge can be used as a promising biomass resource in the future.In Chapter 6, a continuous microwave-assisted pyrolytic gasification mini-plant was designed and developed based on Chapter 3, 4, 5 and performance of the system was investigated using pinewood pellets as the feedstock. The product distribution and energy balance were investigated. Produced gases were analyzed by Micro-GC and tar was analyzed using GC/MS. The LHV of produced gases from wood pellets pyrolytic gasification can reach 14.18 MJ/Nm3.In summary, the research work presented in this dissertation aims to provide scientific reference and technical support for the research and further development of microwave-assisted catalytic thermochemical conversion technology for organic solid waste processing. Using microwave-assisted thermochemical conversion technology, organic solid waste resources with low energy density can be converted into clean and high energy density biofuel including bio-oil, combustible gases, biochar and other high-quality fuel products. Microwave-assisted catalytic thermochemical conversion of organic solid waste is a promising technology for valuable biofuels production.

Atmospheric Microwave Discharge for Portable and Ozone-Free Air Plasma

원임희 포항공과대학교 일반대학원 2015 국내박사

In this dissertation, researches on development of microwave air plasma devices are reported. Simulation and experiment for investigating characteristics of atmospheric pressure microwave plasma have been conducted to find its efficacy and safety. Through these researches, microwave plasma system is suggested for developing ozone free air plasma device. To find the characteristics of atmospheric pressure microwave plasmas for their kinetics and RONS production efficacy, One-dimensional Particle-in-Cell Monte Carlo Collision simulations have been conducted. Profitable property changes happened after 300 MHz for atmospheric pressure argon plasma at microsize. Breakdown voltages decreased rapidly and it means that microwave plasmas (>0.3 GHz) can be free from electric shock or arc. As the driving frequency increases, most of power dissipations were observed for electrons. Effective electron temperature and the proportion of high energetic electrons responsible for bond-breaking energy of OH (~2 eV) and O (4.8 eV) near electrode increase significantly. Electron densities and temperatures obtained from particle simulations can be provided to zero-dimensional global simulation as larger electron temperature can be thought as microwave plasmas case. Comparing before and after 0.3 GHz phase properties, two major reactive species, OH and O which is useful for biomedical applications, were expected to be generated more than lower frequency plasmas. For investigating the driving frequency effects in experiments, the properties and effectiveness for biocompatibility of microwave-powered and low-frequency (LF) argon plasmas were compared. The optical emission observation of these two plasmas showed that more useful reactive species were generated by microwave plasma than by LF plasma with the intensities being higher by factors of about 9, 6, and 3 for OH (309 nm), O (777 nm), and O (844 nm), respectively. For effectiveness for biocompatibility, surface hydrophilic modification experiments were also conducted. A SUS304 steel plate became hydrophilic after 5 s of microwave plasma treatment. This is more than ten times faster than in the case of LF plasma treatment, an action related to the generation of reactive species as measured by optical emission spectroscopy. Observations of surface morphology by SEM and chemical composition by XPS indicate that microwave plasma does not induce physical damages and the modification is mainly due to change of chemical composition by plasma generated RONS. High-energy electrons were considered a major factor for microwave plasma characteristics. To overcome limitations of gas-based plasmas and conventional air plasmas, a 1.29-GHz microwave excited atmospheric pressure ambient air plasma jet has been developed as a portable plasma device. The compact air plasma system has no ozone, electric shock, and temperature problems. A 10 mm stable air plasma jet was generated with a pin-to-hole structure coaxial line resonator. Ozone problem, most significant issue of air plasma, was also solved by high temperature at local generating spot of microwave air plasma. Appropriate ambient air flow was supplied to reduce the plasma gas temperature up to 36°C at treating point. Excited NO lines in the ultraviolet region between 200 and 300 nm were observed. Oxygen related plasma species at 777.4 and 844.6 nm, which have potential in several physical and biological phenomena, were also observed. The ozone-free nonthermal portable air plasma system is expected to be useful in biomedical area for its components investigated by optical emission analysis.