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Electromagnetic Field Interference on Transmission Lines due to On-Board Antenna
Lee, Heekwon,Ryu, Soojung,Lee, Seungbae,Kim, SoYoung,Nah, Wansoo Hindawi Limited 2015 International journal of antennas and propagation Vol.2015 No.-
<P>As the available space in the board of a mobile device becomes smaller and more compact, circuit elements and transmission lines are arranged in very close proximity, especially from the antennas which are usually installed on the same board. Due to the various on-board antennas which are designed in small space, the transmission lines on the board are electromagnetically interfered, resulting in the performance degradation of the circuit. So the engineers and circuit designers should find the least interfered place for the transmission lines and components to minimize the electromagnetic interferences. This paper discusses and presents a methodology to find the least sensitive position in the induced current distribution as well as in the noise power delivered from the antenna. For this purpose some vertical, horizontal, and bent transmission lines with antenna on the same board are designed and fabricated with and without common ground, and the transferred powers to the transmission lines were measured and were also simulated using a full-wave simulator. The results predicted by the EM simulation model were successfully confirmed through the measurement of<I>S</I>-parameters in the experimental setup, which shows the validness of the suggested analysis method.</P>
Heekwon Ahn,Seunghun Lee,Eunjong Kim,Jaehee Lee,Yongjoo Sung 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.2
The effect of thermal pretreatment conditions on hydrolysis characteristics of dairy manure and sawdust mixtures has been evaluated. Thermal pretreatment temperature varied between 35 and 120°Cand the period of the treatment changed between 30 and 1440min (24h). As thermal pretreatment temperature and duration increased, organic material solublization rates were improved. Maximum solubilizations of chemical oxygen demand (SCOD), carbohydrates, and volatile fatty acids(VFAs) were observed when dairy manure treated for one day at 120°C. Although one day treatment duration at 120°Cshowed the highest SCOD, soluble carbohydrates, and VFAs concentration, its hydrolysis rate was only about 12%. The results reveal that the thermal pretreatment conditions tried in this study are not enough to solubilize the organic matter contained in dairy manure and sawdust mixtures. In order to maximize hydrolysis performance, the further research needs to determine the factors influences on organic material solubilization in addition to thermal pretreatment temperature and duration.
Lee, Jaehee,Lee, Seunghun,Kim, Eunjong,Jo, Hyunsoo,Ahn, Heekwon 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.2
The performance of chamber and bag digesters for solid state anaerobic digestion (SS-AD) of separated solid fraction of swine manure was investigated using lab-scale digester (4,460 mL total volume and 1,800 mL of effective volume) operating at $37^{\circ}C$ for 63 days. The performance of two different digester types was evaluated in terms of the kinetic constants of methane production obtained from the Gompertz and Gaussian equations. Methane production potential of chamber and bag digester was 202 and $218N{\cdot}mL$ $CH_4/g$ VS. Time to produce 95% methane production potential (T95) and calculated effective anaerobic digestion time were 55.5 days and 41.8 days for chamber digester and 52.8 days and 43.5 days for bag digester, respectively. Our results reveal that the performance was not significantly different between chamber and bag digester.
Lee, Seung-Hun,Jo, Hyeon-Soo,Lee, Myung-Gyu,Yabe, Mitsuyasu,Ahn, Heekwon FACULTY OF AGRIC PUBLICATIONS-KYUSHU UNIV 2017 Journal of the Faculty of Agriculture, Kyushu Univ Vol.62 No.1
<P>This study was conducted to determine the optimal substrate/inoculum (S/I) ratio for solid state anaerobic digestion (SS AD) of beef manure and sawdust bedding mixtures. The organic material removal and methane yield performance were evaluated at five different S/I levels (1, 2, 4, 50, and beef manure alone on a VS basis) for 49 days at 37 degrees C. Results showed that biodegradable volatile solids (BVS) reduction of beef manure alone test unit was 76% which was not significantly different from the rest of all inoculated test units. The methane production potential of all five test units showed similar levels (135 to 154 mL/g VS), regardless of S/I ratio. Although it showed similar methane production potential, the beef manure alone and S/I ratio 50 test units showed the highest methane yields of 7.3 and 7.2 based on the volume of methane produced per volume of digester, respectively. In addition, when considering utilization efficiency of the available digester volume, the beef manure alone treatment was 15% higher than that of the S/I ratio 50 treatment. These results reveal that the beef manure and sawdust bedding mixture does not require inoculation to improve SS AD performance.</P>
Ahn, Heekwon,Lee, Seunghun,Kim, Eunjong,Lee, Jaehee,Sung, Yongjoo 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.2
The effect of thermal pretreatment conditions on hydrolysis characteristics of dairy manure and sawdust mixtures has been evaluated. Thermal pretreatment temperature varied between 35 and $120^{\circ}C$ and the period of the treatment changed between 30 and 1440min (24h). As thermal pretreatment temperature and duration increased, organic material solublization rates were improved. Maximum solubilizations of chemical oxygen demand (SCOD), carbohydrates, and volatile fatty acids(VFAs) were observed when dairy manure treated for one day at $120^{\circ}C$. Although one day treatment duration at $120^{\circ}C$ showed the highest SCOD, soluble carbohydrates, and VFAs concentration, its hydrolysis rate was only about 12%. The results reveal that the thermal pretreatment conditions tried in this study are not enough to solubilize the organic matter contained in dairy manure and sawdust mixtures. In order to maximize hydrolysis performance, the further research needs to determine the factors influences on organic material solubilization in addition to thermal pretreatment temperature and duration.
Jaehee Lee,Seunghun Lee,Eunjong Kim,Hyunsoo Jo,Heekwon Ahn 한국토양비료학회 2015 한국토양비료학회지 Vol.48 No.2
The performance of chamber and bag digesters for solid state anaerobic digestion (SS-AD) of separated solid fraction of swine manure was investigated using lab-scale digester (4,460 mL total volume and 1,800 mL of effective volume) operating at 37°C for 63 days. The performance of two different digester types was evaluated in terms of the kinetic constants of methane production obtained from the Gompertz and Gaussian equations. Methane production potential of chamber and bag digester was 202 and 218 N·mL CH4/ g VS. Time to produce 95% methane production potential (T95) and calculated effective anaerobic digestion time were 55.5 days and 41.8 days for chamber digester and 52.8 days and 43.5 days for bag digester, respectively. Our results reveal that the performance was not significantly different between chamber and bag digester.
Pilot Scale Solid State Anaerobic Co-digestion of Dairy Manure and Milking Parlor Wastewater
Seunghun Lee,Eunjong Kim,Myeongseong Lee,Jisoo Wi,Heekwon Ahn 한국토양비료학회 2020 한국토양비료학회지 Vol.53 No.2
A pilot scale solid-state anaerobic co-digestion study was conducted to elucidate the feasibility of anaerobic digestion as an effective treatment method for dairy manure (DM) and milking parlor wastewater (MPW), and it focusing mainly on the stability of anaerobic digestion process and methane production potential. Dairy manure and milking parlor wastewater were co-digested (1/0.48, w/w) in 11m3 volume reactor for 63days at the mesophilic condition (36°C). In addition, pH, volatile fatty acids and ammonia were periodically analyzed to monitor anaerobic digestion inhibitions. The results showed that the co-digestion of DM and MPW was successfully performed without any inhibition caused by ammonia and volatile fatty acids accumulation. The potential methane production (P) from a modified Gompertz model was about 130.5 mL g-VS<SUP>-1</SUP>, and approximately 80% of the methane production was obtained during the 40 days digestion test and the lag phase was 14 days. The pilot scale SSAD (solid-state anaerobic digestion) system showed about 1.3-fold higher methane production than lab-scale system. The results of solid-state anaerobic co-digestion of bedded pack barn dairy manure and milking parlor wastewater using pilot-scale anaerobic digester can be used as a reference for the design of farm-scale anaerobic digester.
이승훈 ( Seunghun Lee ),김은종 ( Eunjong Kim ),이명성 ( Myeongseong Lee ),김대훈 ( Daehun Kim ),위지수 ( Jisoo Wi ),신진호 ( Jinho Shin ),노희철 ( Heecheol Roh ),안희권 ( Heekwon Ahn ) 한국농업기계학회 2019 한국농업기계학회 학술발표논문집 Vol.24 No.1
본 연구는 톱밥깔짚 우사에서 사육되는 착유우의 분뇨 발생량 평가 및 적정 깔짚(톱밥) 교체시점을 구명하기 위한 목적으로 수행되었다. 가축분뇨 자원화 표준설계도를 참고해 깔짚 두께를 10cm로 조성한 후 평균체중 약 605 kg 착유우 총 6마리를 210 ㎡ 면적 우방에서 62일간(1월~3월) 사육하였다. 일일 두당 평균 9.8 kg 배합사료와 평균 23.3 kg 조사료를 급여(DMI 30.1 kg)하였으며, 물은 자동급수장치를 통해 자율적으로 음수할 수 있도록 하였다. 시료는 균일성 확보를 위해 우방 내 다지점에서 골고루 섞어준 후 채취하였으며, 2주 간격으로 분뇨 Map을 작성하여 우방 내 젖소의 배설습성 또한 분석하였다. 실험 종료 후 분뇨와 깔짚 혼합물의 무게는 스키드로더와 로드셀을 사용하여 측정하였다. 젖소분뇨와 톱밥 혼합물의 발생량은 두당 일일 44.0 kg 발생되었으며, 톱밥깔짚을 제외한 순수 분뇨는 일일 두당 32.3 kg 발생되었다. 본 연구 결과는 2008년도에 제시된 착유우 분뇨 발생원단위(76.3±6.0 kg)에 비해 약 42% 적은 수준을 보였다. 이는 기존 고시된 젖소분뇨 발생원단위는 대사틀을 이용하여 분뇨가 장시간 상온과 대기에 노출됨에 따라 발생하는 수분증발과 유기물분해 같은 환경적 요인이 배제되었기 때문이라고 사료된다. 실험 14일 후, 사료조와 급수조 주변의 경우 분뇨와 깔짚 혼합물의 함수율이 70%이상 도달하였으며, 57일 경과 후에는 함수율 70% 이상인 분뇨와 톱밥 혼합물이 우방 면적의 절반을 차지하였다.