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Growth and Development of Seedling and Stem Cell under Microgravity Conditions

  • Zaidi, M.A.;Murase, H.
    • 한국농업기계학회:학술대회논문집
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    • 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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    • pp.600-606
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    • 2000
  • The effect of clinostatting and microgravity on plant cells and organs is considered for two types of gravistimulation: static and dynamic. The former is eliminated by both clinostatting and microgravity; the latter is eliminated by microgravity, but is inevitable during clinostatting, and may be perceived by cells if rotation is not fast enough. To test the effect of clinostatting on root cells and development, lettuce seedlings were germinated and grown for two weeks in a spacetron, keeping the centrifugation rate at zero. In the clinorotated plants, amyloplasts were distributed throughout the cells and were not sedimented as in the stationary control. Cells of seedlings grown in a spacetron have significantly different ultrastructures from those grown under control conditions of 1g.

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새로운 스위칭 평면을 갖는 슬라이딩 모드 속도 제어기 (Sliding Mode Speed Controller for the BLDC Motor having New Switching Surface)

  • 김세일;최중경;박승엽
    • 한국정보통신학회논문지
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    • 제4권3호
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    • pp.689-696
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    • 2000
  • 본 논문에서는 슬라이딩 모드 제어기의 채터링 현상을 제거하기 위한 개선된 방법을 제안한다. 기존 방법은 스위칭함수의 미분을 특정 상수 또는 스위칭함수의 비례항으로 수렴하도록 하여 과도상태의 채터링을 제거하였으나, 제안된 방법은 스위칭함수의 미분이 스위칭함수의 비례-적분 항에 수렴하도록 하여 과도상태 및 정상상태에서의 채터링 혈상을 제거한다. 제안된 방법과 기존 방법을 비교 검토하기 위해 브러시리스 직류전동기 속도제어기에 대하여 모의실험을 통해 그 유용성을 확인한다.

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경계점의 절대 오차 평균을 이용한 개선된 연속 제거 알고리즘 (An Advanced Successive Elimination Algorithm Using Mean Absolute Difference of Neighboring Search Points)

  • 정수목
    • 한국컴퓨터산업학회논문지
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    • 제5권7호
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    • pp.755-760
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    • 2004
  • 본 논문에서는 경계점의 절대 오차 평균을 이용한 개선된 연속제거알고리즘을 제안 하였다. 움직임추정에서 탐색점은 경계점의 절대오차 평균을 이용하여 많은 연산량을 필요로 하는 정합 평가 없이 제거될 수 있다. 적응적 MAD계산 알고리즘을 적용하여 신속하게 탐색점을 제거한다. 따라서 제안된 알고리즘에서는 정합평가 횟수가 감소하게 되고 탐색점제거가 신속하게 발생하여 연산량이 감소하게 된다. 제안된 알고리즘의 효율성을 실험결과로 증명하였다.

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송전선로 과부하를 해소하기 위한 민감도에 근거한 알고리즘 연구 (A study on an algorithm based on sensitivity method for alleviating overloads in power networks)

  • 이병하;백정명
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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    • pp.286-290
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    • 2007
  • In this paper, a new algorithm based on sensitivity method for alleviating overloads in power networks is presented to find the switching branches effectively. Preferentially the switching of shunt reactive devices such as shunt reactor and shunt capacitors is performed. If overloads are not eliminated, the ranking of switching branches is calculated according to the algorithm based on sensitivity method and the switching of the ranked branches is performed in the order of ranking until overloads are eliminated. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus test system.

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Asymmetrical Pulse-Width-Modulated Full-Bridge Secondary Dual Resonance DC-DC Converter

  • Chen, Zhangyong;Zhou, Qun;Xu, Jianping;Zhou, Xiang
    • Journal of Power Electronics
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    • 제14권6호
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    • pp.1224-1232
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    • 2014
  • A full-bridge secondary dual-resonant DC-DC converter using the asymmetrical pulse-width modulated (APWM) strategy is proposed in this paper. The proposed converter achieves zero-voltage switching for the power switches and zero-current switching for the rectifier diodes in the whole load range without the help of any auxiliary circuit. Given the use of the APWM strategy, a circulating current that exists in a traditional phase-shift full-bridge converter is eliminated. The voltage stress of secondary rectifier diodes in the proposed converter is also clamped to the output voltage. Thus, the existing voltage oscillation of diodes in traditional PSFB converters is eliminated. This paper presents the circuit configuration of the proposed converter and analyzes its operating principle. Experimental results of a 1 kW 385 V/48 V prototype are presented to verify the analysis results of the proposed converter.

단거리송전선에서 투입저항이 없는 차단기적용에 관한 연구 (The Study on Application of Circuit Breaker without Closing Resistor in Short Transmission Line)

  • 김정배;정영환;송원표
    • 대한전기학회논문지:전력기술부문A
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    • 제53권1호
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    • pp.31-37
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    • 2004
  • In this paper, the analysis result of the switching surge in substation including GIS(Gas Insulated Switchgear) has been described using the EMTP(Electro Magnetic Transient Program) program. After performing the modeling of the input data, we have reviewed the energization overvoltages of GCB(Gas Circuit Breaker) without closing resistor in 345kV network, according to the conditions of simultaneously operating switch and statistically operating switch. Firstly, it can be known that the energization overvoltage of single line is higher than that of parallel energized line. Secondly, the maximum energization overvoltage obtained in statistics switch is higher than one in simultaneous switch. From these results, it can be known that the phase-to-earth energization overvoltages of $\alpha$-$\beta$ section are less than 2.2 p.u when closing resistor is eliminated. Therefore, it is possible to consider the circuit breaker eliminated the closing resistor in $\alpha$-$\beta$ section.

Removal of OH Spectral Interferences from Aqueous Solvents in Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) with Ar Cryogenic Desolvation

  • Cho, Young-Min;Pak, Yong-Nam
    • Bulletin of the Korean Chemical Society
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    • 제26권9호
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    • pp.1415-1420
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    • 2005
  • The spectral interferences of OH from aqueous solvents in ICP-AES have been studied and eliminated using a cryogenic argon trap. The prominent lines of Bi I 306.772 nm, Al I 309.271 nm, and V II 310.230 nm, which are very seriously overlapped with the OH band, were examined. With an extended torch and high tangential flow of 20 L/min, water vapor from air entrainment was prevented. The combination of a condenser and argon cryogenic trap was able to eliminated most of water vapor carried by the argon sample gas. Removal of OH spectral interference could extend the linearity of the calibration curve 5-10 times on the lower concentration for ICP-AES. Interference Equivalent Concentration (IEC) has been reduced to 5.6, 5.9, and 12.4 times for Bi, Al and V, respectively.

상관행렬로부터 간섭신호 도달각을 추정하여 상호상관 성분을 제거하는 빔형성 방법 (Cross-Correlation Eliminated Beamforming Based on the DOA Estimation of Interference using Correlation Matrix)

  • 류길현;홍재근
    • 대한전자공학회논문지TC
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    • 제43권10호
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    • pp.18-26
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    • 2006
  • 목표신호와 간섭신호 사이에 상호 상관성분이 크게 존재할 경우에도 성능저하를 극복할 수 있는 새로운 빔형성 알고리듬을 제안한다. 제안하는 방식을 이용하여 상관행렬로부터 간섭신호의 도달각을 바로 구하고 입력신호의 상관행렬 내에 존재하는 상호상관 성분을 제거할 수 있음을 보였다. 제안한 방식을 적용하였을 경우에는 공간평균(Spatial Averaging)을 사용하는 것에 비해서 간섭신호의 크기를 줄이는 데 있어서 성능향상이 있음을 모의실험 결과를 통해서 보였다.

Reliability Improvement of Titania Ceramics with Surface Flaw Through High Voltage Screening

  • Tanaka, Tomohiro;Kishimoto, Akira
    • The Korean Journal of Ceramics
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    • 제5권4호
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    • pp.386-389
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    • 1999
  • Effect of high voltage screening was examined on mechanical strength of titania ceramics with two different surface roughness. Roughly finished sample showed degraded mechanical strength meaning that the introduced flaw played the role of starting point of mechanical fracture. On such sample, electrically weak parts were eliminated by applying a screening field. Mechanical strength measurement on survived parts revealed that after screening the Weibull plots bended to become a convex curve while plots at high strength region were almost the same. This result means that relatively low mechanical strength parts were eliminated by the electrical method. As a result the Weibull modulus calculated from all the data increased, demonstrating the effect of high voltage screening on titania ceramics containing fracture controlling surface flaws. Roles of the surface flaw such as a common weak spot for both failures are disscussed in relation to the electric field concentration similar to that of mechanical stress.

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미나리꽝을 이용한 영양물질제거에 관한 연구 (A Studies on Removal of Nutrient Material by Using Dropwort Field)

  • 이영신;김창회
    • 한국환경보건학회지
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    • 제29권3호
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    • pp.16-20
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    • 2003
  • Nitrogen(N) and phosphorus(P) in surface streams mainly lead to euthrophication. It aggravates water quality and consequently increases the purification costs. As a resolution of water contamination caused by household drainage through irrigation route by 70% of the 1,300 community residents in Eum-Am Myun, Seo-San city, was implemented biological self-purification method by growing Oenanthe Javanica along the polluted water tunnel. The contaminated water was efficiently purified after passing the dropwort field; DO conc. of effluent water was increased 8.3∼61.9% after through the drop wort field. HRT of experiment system was changed 0.05∼1.50/day. 50% of BOD was eliminated at the range above 12 mg/l of Influent BOD conc. Also, 50% of COD was eliminated at the range above 30 mg/l of Influent COD conc. Finnally, the influent T-N loading at range below 1.5 g/m$^3$/d reduced 50% of Influent T-N conc., and so did influent T-P loading at the range below 0.03 g/m$^3$/dwas reduced 50% of Influent T-P conc.