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포스터 발표 : 토양환경 분야 ; 골프장의 잔디 토양에서 코팅된 다양한 칼륨(K) 비료의 이동성 평가 (초)
권상문 ( Sang Moon Kwon ),김홍기 ( Hong Ki Kim ),김희정 ( Hee Jung Kim ),한석순 ( Seok Soon Han ),우선희 ( Sun Hee Woo ),이문순 ( Moon Soon Lee ),백기태,김인수 ( In Su Kim ),이상승 ( Sung Sung Lee ),정근욱 ( Keun Yook Chung ),Bong 한국환경농학회 2009 한국환경농학회 학술대회집 Vol.2009 No.2
권중학(Kwon, Joong-Hak),김광석(Kim, Kwang-Suk),방기창(Bang, Ki-Chang),황상문(Hwang, Sang-Moon) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.4
With the advent of mobile phone, digital multimedia broadcasting(DMB) service is to be realized for multimedia data communication. For an acoustic part, a smaller and lighter microspeaker is also soon to be realized as an MP3 song player and a speakerphone. Sound quality in the microspeaker is becoming more important in mobile phones. It is evaluated by total harmonic distortion(THD). THD is the proportion of higher order frequencies output response to sinusoidal input signal. It is affected by uneven magnetic distribution and nonlinear response of diaphragm. In this paper, harmonic distortion is analyzed by considering magnetic and mechanical coupling effects. Simulated results of THD are compared with experimental data. Results show that THD in lower frequency range is higher due to high displace on voice coil and high mechanical response of high order frequency.
권중학(Kwon, Joong-Hak),김광석(Kim, Kwang-Suk),이창민(Lee, Chang-Min),황상문(Hwang, Sang-Moon) 한국소음진동공학회 2009 한국소음진동공학회 논문집 Vol.19 No.8
The goal of this study is to examine the effect of the number of slots on the noise from BLDC motors. To this end, the number of poles was fixed to 4 and the number of the slots was set to 6 or 24 before noise was measured. Motors having different numbers of slots showed clear differences in noise. Cogging torque, torque ripple and normal local force were interpreted, analyzed and compared to determine the reason for the differences. To determine the cause of the noise, cogging torque, torque ripple and normal local force were calculated, which are representative noise sources of BLDC motors, and FFT was performed to analyze their frequency components(harmonics). The results show that torque ripple and normal local force were the dominant factors in the noise difference between the 6-slot and 24-pole motors. As the number of the slots increased, the number of harmonics decreased and their amplitude of harmonic were reduced, which was attributed as the reason for the noise differences.
이동통신 단말기용 통합 영구 자석 형태의 마이크로스피커 개발
황상문(Hwang, Sang-Moon),이홍주(Lee, Hong-Joo),권중학(Kwon, Joong-Hak),황건용(Hwang, Gun-Yong),양용창(Yang, Yong-Chang) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.2
In mobile phones of multimedia era, microspeakers of high qualify sound are essential parts to generate human voice in speaker phone and MP3 song player. In this paper, two types of microspeakers, outer permanent magnet (PM) and combined PM type, are analyzed using electromagnetic, mechanical and their coupling analysis. For performance comparison, voice coil diameter is chosen as a design parameter to change excitation position and magnet volume for both types. For combined PM type, sound pressure level (SPL) is improved due to increased PM volume compared to outer PM type. Also, with the decreased voice coil diameter for combined PM type, the 1st resonant mode of the diaphragm is more efficiently excited due to concentrative excitation, resulting in lower and broader frequency range. Therefore, it can be said that the combined PM type microspeakers are more advantageous for high performance microspeaker which are essential for multimedia era.
권상문,이예은,박영민,김덕원,박지수,오은지,유진,정근욱,Kwon, Sang-Moon,Lee, Ye-Eun,Park, Young-Min,Kim, Deok-Won,Park, Ji-Su,Oh, Eun-Ji,Yoo, Jin,Chung, Keun-Yook 한국환경과학회 2020 한국환경과학회지 Vol.29 No.3
This study was conducted to evaluate the effect of phosphorus acid (H<sub>3</sub>PO<sub>3</sub>) addition to the horticultural bed soil on the initial growth of red pepper (Capsicum annuum L. cv.), cucumber (Cucumis sativus L. cv.), and kimchi cabbage (Brassica campestris L. ssp. pekinensis (Lour.) Rupr. cv.). The stem heights of red pepper and cucumber were 46.1% and 23.0% greater in the 50 mg/L of phosphorus acid treatment than the untreated (control). Further, the stem diameter of pepper and cucumber were 48.7% and 23.0% greater in the 50 mg/L of phosphorus acid treatment than the control. In addition, the number of kimchi cabbage leaves was 47.5% greater in the 50 mg/L of phosphorus acid treatment than the control. The dry weights of red pepper, cucumber and kimchi cabbage were 72.9%, 16.5%, and 30.4% heavier in the 50 mg/L than the control, respectively. Cations (K, Ca, and Mg) and total phosphorus (T - P) were quantitatively analyzed for these three horticultural crops. The concentrations of K, Ca, and Mg, and T - P were higher in the 50 mg/L of phosphorus acid than the control, respectively. Based on the results obtained in this study, it appears that treatment of phosphorus acid in horticultural bed soil enhanced the growth of red pepper, cucumber and Kimchi cabbage.