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Powre-MOSFET를 이용한 저·고 주파수 싸이크로 컨버터에 관한 연구
심재명,김영춘,조문택 한밭대학교 산업과학기술연구소 1993 논문집 Vol.1 No.-
The high frequency output from the general power converter causes harmonics, thereby raising various problems. The most common way to reduce harmonics used to PWM methods which may have some difficulties in heightening the output frequency. Under such a circumstance, this paper suggests a switching pattern of transfer function defining the switching turn-on time and the algorithm of transfer function which can create step square-waves in output one period, thus making it possible to continually transfer to the rage of 5〔Hz〕∼1.5〔Hz〕as well to reduce the harmonics.
Periodic PM Policy for Repairable System with RCW or NCW
Jung, Gi-Mum,Kim, Dae-Kyung,Park, Dong-Ho The Korean Reliability Society 2002 International Journal of Reliability and Applicati Vol.3 No.3
This paper suggests the optimal periodic preventive maintenance policies after the combination warranty is expired. After the combination warranty is expired, a repairable system undergoes PM periodically and is minimally repaired at each failure. And also the system is replaced by a new system at the N th PM. In this case, we derive the mathematical formula for the expected cost rate per unit time. The optimal number and period for the periodic PM that minimize the expected cost rate per unit time are obtained. Some numerical examples are presented for illustrate purpose.
문두열(Du-Yeoul Mum) 한국해양공학회 1995 韓國海洋工學會誌 Vol.9 No.2
The purpose of paper is to calculate the excavation volume of unequal interval grid using nonlinear boundary in eathwork volume determination for reclamation of the foreshore.<br/> A congruence area formula by first and third equation is compared with trapezoidal simpson formulas to earthwork volume.<br/> And nonlinear spot level method of unequal interval grid is compared with linear and nonlinear sport level method of equal interval grid excavation volume.<br/> As a result algorithm of derived area and volume formula should provide a better accuracy than linear and nonlinear spot level currently in use.<br/> Practical application of each method to the excavation volume is illustrated by digital elevation model of aerial photogrammetry and model test of aquarium.
Bioinsecticidal potential of culture extract from Serratia sp. EML-SE1 against diamondback moth
Hyung Uk Jeong,Hye Yeon Mum,Hyung Keun Oh,Seung Bum Kim,Hyang Burm Lee,Iksoo Kim 한국응용곤충학회 2009 한국응용곤충학회 학술대회논문집 Vol.2009 No.10
Diamondback moth (Plutella xylostella L.) belonging to genus Lepidoptera is a notorious pest of cruciferous crops worldwide. We evaluated the bioinsecticidal activity of the liquid cultures (LB and NB) of a bacterial strain, Serratia sp. EML-SE1, isolated from a diseased diamondback moth. The pathogenicity of a bacterial strain to diamondback moth was confirmed by the following procedures: treatment of liquid culture on cabbage leaves, ingestion of inoculated cabbage and mortality response. For the test, twenty 3rd instar larvae of diamondback moth were placed on the Chinese cabbage leaf in a round plastic cage (Ø 10 × 6 cm) and sprayed with the liquid cultures. After 72 hours, insecticidal activity of LB and NB cultures of Serratia sp. against P. xylostella larvae showed 91.7% and 88.3%, respectively. In addition, the bioinsecticidal activity on potted cabbage with 14 leaves in a growth cage (165 × 83 × 124 cm) also was similar to that of plastic cage experiment. Summarized, the Serratia sp. EML-SE1 may be a potent candidate as a bioinsecticidal agent to control diamondbac kmoth.