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Kwak Yun-Gi,Jeong Yeonho,Lee Byoung-Hee 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1
To improve the fight time of an unmanned aerial vehicle (UAV), research on the hybridization of a lithium-ion polymer (LiPo) battery and a fuel cell (FC) is being conducted. In addition, as the feld of use of UAVs expands, the use of high-power converters is required to withstand larger payloads. It means using high-voltage gain converters is essential for efcient motor driving. Therefore, we derive circuit structures that can obtain high-voltage gain from FC through port confguration of a three-switch converter for low-weight and high-power density characteristics. The UAV systems will be designed under 600 and 150 W inputs from hybrid sources and 750 W output conditions, which is calculated to drive the motor of a hexa-copter weighing about 10 kg is calculated. In addition, based on the required power of the three possible circuits, the driving time of UAVs according to the amount of hydrogen energy will be calculated. Finally, this paper presents the guideline for selecting the circuit structure according to the priority between improving the driving time and achieving higher power density.
Effect of Various Essential Oils in Mono Gastric Animal
Kwak, Woo Gi. Yun, Won. Lee, Ji Hwan. Lee, Chang Hee. Oh, Seo Yong. Oh, Han Jin. Liu, Shudong. Cho, Jin Ho 忠北大學校 農業科學硏究所 2017 農業科學硏究 Vol.33 No.1
From last decades, essential oils have been widely utilized as additives for animal feed as well as humans. Essential oil as an additive has a good effect. In addition, it has attracted attention as an effective additive for antibiotic use and reduction odor emissions in the problems of animal industry. Essential oils are aromatic oils extracted by herbs and plant leaves, petals, stems, husks, roots and are secondary products of plants that display color and odor as hormone components of plants. Essential oils are 100% pure natural ingredients and do not have a harmful effect on body. Most of essential oils are Generally Recognized As Safe (GRAS) and are approved by the US Food and Drug Administration (FDA). In this study, we compared nutrient digestibility, growth rate, blood profiles and odor reduction effects among the essential oils. The purpose of this review is to validate and compare several previously proven effects. Furthermore, it is to summarize and define that the effects of essential oils as animal additives.
Causes and Prevention Method of Gastric Ulcer in Pigs
Lee, Ji-Hwan. Yun, Won. Kwak, Woo-Gi. Lee, Chang-Hee. Oh, Han-Jin. Liu, Shu-Dong. Kim, Doo-Wan. Cho, Jin-Ho 忠北大學校 農業科學硏究所 2017 農業科學硏究 Vol.33 No.1
It is important and is studying the occurrence date of gastric ulcers in pigs in several Western countries. Gastric ulcers were founded in almost all pigs with only a difference in progress, and usually were occurred on the par esophagea in pigs. Also, it is generally difficult to detect until biological signs and symptoms appear. Many studies have shown that gastric ulcers have a wide variety of causes. Gastric ulcers were influenced by particle size in diets. If the particle size in diets is less than 400 microns, gastric ulcers easily occur. In nutritional aspects, gastric ulcers were influenced by fiber, vitamin E, zinc and melatonin. Many studies showed that when the fiber, zinc, melatonin and vitamin E were added in diet, gastric ulcers in pigs decrease. In feeding management, the elements such as straw and feed restriction affected the gastric ulcers of pigs. All these factors connected with a stress in pigs, and stress results in productions of large amounts of excess acid. Because of excessively producing a gastric acid, gastric ulcers occur. However, many people in Korea are interested in the gastric ulcers of pigs. Therefore, further studies on gastric ulcers of pigs should be conducted and researcher in Korea should try to prevent them in livestock industry.
Feeding Value of Whole Crop Cereal Silage for Pigs
Chang-Hee Lee, Won Yun, Ji-Hwan Lee, Woo-Gi Kwak, Seo-Young Oh, Shu-Dong Liu,Seong-Jeong Park, and Jin-Ho Cho 忠北大學校 農業科學硏究所 2016 農業科學硏究 Vol.32 No.2
Feed cost is one of the most important parts of the pig production industry. Whole crop cereal is cheaper price than corn which is contained in a lot of formula feed. In order to increase the nutritional value, whole crop cereals are usually made into silage. The silage method can have an effect of lengthening the storage period, and reduce the difficult to digest dietary fiber through lactic acid fermentation. Fermented whole crop cereal could have an advantage of productivity and healthy in pigs. As results, fermented whole crop cereal could potentially replace as a part of concentrated feed for pigs.
A 4.8-MJ Pulsed-Power System for Electromagnetic Launcher Experiment
Yun Sik Jin,Young Bae Kim,Jong Soo Kim,Chuhyun Cho,Kyung-Seung Yang,Seong-Ho Kim,Byungha Lee,Sanghyuk An,Young-Hyun Lee,Seok Han Yoon,In Su Koo,Yong Gi Baik,Dae-Hwan Kwak Institute of Electrical and Electronics Engineers 2015 IEEE transactions on plasma science Vol. No.
<P>A 4.8-MJ capacitive pulsed-power system (PPS) was designed and fabricated for electromagnetic launcher (EML) experiment. The PPS consists of eight 600-kJ segments, which can be operated independently. In each segment, six 100-kJ capacitor bank modules, a charging power supply, a dump and charge panel, and control circuit were integrated. The capacitor bank modules in the segment are charged at the same voltage up to 10 kV, but the trigger time of each module can be set up differently. The overall PPS system is controlled by a control program, which sets charging voltage and trigger time of each module and monitors the states of system component. All the control signals are transmitted through fiber optic communication. The 48 unit modules are connected in parallel to EML with high-voltage coaxial cables. A current amplitude of more than 1 MA and a pulsewidth of several milliseconds were achieved by the PPS. The PPS has been applied to several tens of firing experiments of EML successfully. The design, fabrication, and the test results of the 4.8-MJ PPS were described in this paper.</P>