• Title/Summary/Keyword: High step-up

Search Result 699, Processing Time 0.03 seconds

Effects of Processing Time and Temperature on the Surface Properties of AISI 316L Stainless steel During Low Temperature Plasma Nitriding After Low Temperature Plasma Carburizing (AISI 316L stainless steel에 저온 플라즈마 침탄처리 후 질화처리 시 처리시간과 온도가 표면특성에 미치는 영향)

  • Lee, Insup
    • Korean Journal of Metals and Materials
    • /
    • v.46 no.6
    • /
    • pp.357-362
    • /
    • 2008
  • The 2-step low temperature plasma processes (the combined carburizing and post-nitriding) were carried out for improving both the surface hardness and corrosion resistance of AISI 316L stainless steel. The effects of processing time and temperature on the surface properties during nitriding step were investigated. The expanded austenite (${\gamma}_N$) was formed on all of the treated surface. The thickness of ${\gamma}_N$ was increased up to about $20{\mu}m$ and the thickness of entire hardened layer was determined to be about $40{\mu}m$. The surface hardness reached up to $1,200HV_{0.1}$ which is about 5 times higher than that of untreated sample ($250HV_{0.1}$). The thickness of ${\gamma}_N$ and concentration of N on the surface were increased with increasing processing time and temperature. The corrosion resistance in 2-step low temperature plasma processed austenitic stainless steels was enhanced more than that in the untreated austenitic stainless steels due to a high concentration of N on the surface.

Modular Line-connected Photovoltaic PCS (모듈형 계통연계 태양광 PCS)

  • Seo, Hyun-Woo;Kwon, Jung-Min;Kim, Eung-Ho;Kwon, Bong-Hwan
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.13 no.2
    • /
    • pp.119-127
    • /
    • 2008
  • In this paper, the modular line-connected photovoltaic PCS (photovoltaic power conditioning system) is proposed. A step-up DC-DC converter using a active-clamp circuit and a dual series-resonant rectifier is proposed to achieve a high efficiency and a high input-output voltage ratio efficiently. An IncCond (incremental conductance) MPPT (maximum power point tracking) algorithm that improves MPPT characteristic is used. The PV module current is estimated without using a DC current sensor. By control a inverter using a linearized output current controller, a unity power factor is achieved. All algorithms and controllers are implemented on a single-chip microcontroller and the superiority of the proposed DC-DC converter and controllers is proved by experiments.

A Study on the Piezoelectric Transformer for High Power (고출력 압전 변압기에 관한 연구)

  • Lee, Jong-Pil;Kim, Weon-Jong;Shin, Hyun-Tak;Shin, Jong-Yeol;Lee, Soo-Won;Lee, Chung-Ho;Hong, Jin-Woong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2004.04b
    • /
    • pp.195-198
    • /
    • 2004
  • In this paper, the disk-type piezoelectric transformer for the high power was investigated with the variation of road resistance. The diameter and thickness of a disk-type piezoelectric transformer was 50mm and 4.5mm, respectively. The piezoelectric transformer was composed to PZT-PMN-PSN. The ratio of driving electrode and generating electrode ranges from 1.4:1 to 3:1. The poling direction of driving part and generating part are the same. A voltage step-up ratio increased with increasing the load resistance, $R_L$, so it reached 60 times under no road resistance. also, the maximum efficiency of 97% was obtained.

  • PDF

Electrical Characteristics of the High Power Piezoelectric transformer Using PSN-PZT system ceramics (PSN-PZT계 세라믹스를 이용한 고출력 압전 트랜스포머의 전기적 특성)

  • 이용우;류주현;윤광희;정회승;서성재;김종선
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.13 no.4
    • /
    • pp.286-293
    • /
    • 2000
  • In this paper we investigated the structural dielectric and piezoelectric properties of 0.03Pb(Sb$\_$1/2//Nb$\_$1/2/)-0.97Pb(Zr$\_$0.495//Ti$\_$0.505/)O$_3$+0.5 wt% excess PbO + wt% MnO(X=0, 0.1, 0.3, 0.5, 0.7) ceramics to develop the high-power piezoelectric transformer. The piezoelectric transformers with dimension of 27.5$\times$27.5$\times$2.5[mm$^3$]were fabricated and their electrical properties were measured. Maxima of piezoelectric properties such as electro-mechanical coupling factor of 0.534 and mechanical quality factor of 1487 were obtained for the PSN-PZT with 0.3wt% MnO. voltage step-up ratios of piezoelectric transformers at 500[Ω]and no load were 0.78, 12.82, respectively. The maximum efficiency of piezoelectric transformer was 98.6% at 800[Ω]. While the 14W fluorescent lamp were driven by the piezoelectric transformer for more than 20[min], increment of temperature in the piezoelectric transformer was 7[$\^{C}$].

  • PDF

Evaluation of Creep-Fatigue Damage of KALIMER Reactor Internals Using the Elastic Analysis Method in RCC-MR

  • Koo, Gyeong-Hoi;Bong Yoo
    • Nuclear Engineering and Technology
    • /
    • v.33 no.6
    • /
    • pp.566-584
    • /
    • 2001
  • In this paper, the progressive deformation and the creep-fatigue damage for the conceptually designed reactor internals of KALIMER(Korea Advanced Liquid MEtal Reactor) are carried out by using the elastic analysis method in the RCC-MR code for normal operating conditions including the thermal load, seismic load (OBE) and dead weight. The maximum operating temperature of this reactor is 53$0^{\circ}C$ and the total service lifetime is 30 years. Thus, the time- dependent creep and stress-rupture effects become quite important in the structural design. The effects of the thermal induced membrane stress on the creep-fatigue damage are investigated with the risk of the elastic follow-up. To calculate the thermal stress, detailed thermal analyses considering conduction, convection and radiation heat transfer mechanisms are carried out with the ANSYS program. Using the results of the elastic analysis, the progressive deformation and creep-fatigue damages are calculated step by step using the RCC-MR in detail. This paper ill be a very useful guide for an actual application of the high temperature structural design of the nuclear power plant accounting for the time-dependent creep and stress-rupture effects.

  • PDF

Development of roll - up ventilation system for pipe- constructed plastic film greenhouse (파이프 비닐온실용 권취식 창개폐기의 개발)

  • 이기명;박규식;김유일;김태홍
    • Journal of Bio-Environment Control
    • /
    • v.4 no.2
    • /
    • pp.232-239
    • /
    • 1995
  • This study was carried out to get required torque data needed to design and develop a roll-up ventilation system in a pipe-constructed plastic film green-house. The results obtained from this study are as follows : 1. The required torques of a roll-up ventilation system in greenhouse are the functions of its length. The torques should multiplied by the conversion coefficients (2.0 in ceiling vent, 1.8 in side vent) in case of application. 2. In constructing pipe-constructed plastic film greenhouse, a shaft pipe is the largest essential element in roll - up shaft weight constitution which have an effect on the required torques. Therefore, the pipe should be light using nonferrous materials like aluminum alloy. 3. A planetary reduction ventilator of differential ring gear type is suitable for a roll-up ventilation system, because it can make high efficient reduction just using the first step shift.

  • PDF

MATHEMATICAL UNDERSTANDING OF CONSCIOUSNESS AND UNCONCIOUSNESS

  • LEE, NAMI;KIM, EUN YOUNG;SHIN, CHANGSOO
    • Journal of the Korean Society for Industrial and Applied Mathematics
    • /
    • v.21 no.2
    • /
    • pp.75-79
    • /
    • 2017
  • This paper approaches the subject of consciousness and unconsciousness from a mathematical point of view. It sets up a hypothesis that when unconscious state becomes conscious state, high density energy is released. We argue that the process of transformation of unconsciousness into consciousness can be expressed using the infinite recursive Heaviside step function. We claim that differentiation of the potential of unconsciousness with respect to time is the process of being conscious in a world where only time exists, since the thinking process never have any concrete space. We try to attribute our unconsciousness to a special solution of the multi-dimensional advection partial differential equation which can be represented by the finite recursive Heaviside step function. Mathematical language explains how the infinitive neural process is perceived and understood by consciousness in a definitive time.

The Effect of Piezoelectric Properties on the Output Properties of Step-down Multilayer Piezoelectric Transformer (압전특성이 강압용 적층 압전변압기의 출력특성에 미치는 영향)

  • Kim, Kook-Jin;Yoo, Ju-Hyun;Paik, Dong-Soo;Yoon, Hyun-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2006.11a
    • /
    • pp.225-227
    • /
    • 2006
  • Multilayer step down piezoelectric transformers were manufactured using PZN-PMN-PZT and PMN-PNN-PZT ceramics respectively. Sintering temperature of the ceramics was $940^{\circ}C$. And then. their electrical properties were investigated according to the variations of frequency and load resistance. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum values in the vicinity of 69 and 71kHz, respectively. At the load resistance of $100{\Omega}$, the piezoelectric transformers showed the temperature rises of about 21 and $18^{\circ}C$ at the output power of 15W and 18W, respectively. At the transformer with high effective electromechanical coupling factor($k_{eff}$), lower temperature increase was appeared.

  • PDF

Electrical Properties of High Power Step Down Multilayer Piezoelectric Transformer using Low Temperature Sintering PMN-PNN-PZT Ceramics (저온소결 PMN-PNN-PZT 세라믹스를 이용한 고출력 강압용 적층 압전변압기의 전기적 특성)

  • Yoo, Ju-Hyun;Kim, Kook-Jin;Paik, Dong-Soo;Yoon, Hyun-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.20 no.4
    • /
    • pp.332-336
    • /
    • 2007
  • In this study, multilayer piezoelectric transformer was manufactured using the PMN-PNN-PZT ceramic and then the electrical characteristics were investigated according to the variations of frequency and load resistance. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum value at the vicinity of 75 kHz and increased according to the increase of load resistance. When the output impedance coincided with the load resistance, the multilayer piezoelectric transformer showed the temperature rise of less than $20^{\circ}C$ at the output power of 20 W. As the results, the multilayer piezoelectric transformer manufactured at low co-firing temperature of $940^{\circ}C$ using PMN-PNN-PZT ceramics could be stably driven as the step-down transformers.

A successful province of agriculturalwater-saving: Gansu

  • Bin, Jiang
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2016.05a
    • /
    • pp.194-194
    • /
    • 2016
  • Gansu, located in the northwestern region, is a typical agricultural province of arid, semiarid in China. The shortage of water resources is the biggest obstacle of Gansu Province's development, and the dry farming water-saving is the eternal theme of Gansu agricultural sustainable development. In recent years, intensify reform in Gansu, has walked out a successful way in the agricultural water-saving. Using the integrated river basin governance as opportunity, the total water-using quantity was regarded as rigidity to retrain, distributed to counties (districts), irrigated areas, towns, associations, groups step by step. Agricultural water price was substantially increased, with the surface water price from about $0.1RMB/m^3$ to more than $0.2 RMB/m^3$, and the ground water from zero to more than $0.1RMB/m^3$. Simultaneously, the difference water prices and over-quota water progression price markup were carried out. The transaction of water rights was encouraged to impel the peasant to establish the consciousness of saving-water. The regulatory documents were formulated to standardize the scope, condition, mode, program etc. of agriculture water-rights transaction, to guarantees the transaction of water rights is carries out in order. The pattern of farming was optimized and adjusted, reducing the high water-consumption crop, increasing economic crops with high benefit and low water-consumption, developing industrialized agricultures such as green house. The relative engineering and measuring facility were comprehensively improved, with the anti-seepage of canal system and the enforcement of dynamo-electric well, developing high-efficient water-saving irrigation and overall metering facilities. The water fine-grained management has realized, and obvious water-saving effect has obtained: water-using rate in the irrigation area by river water has brought up to 0.57 from 0.52, and by well water up to 0.84 from 0.76. Although the water price has increased, the proportion that the water rate expenditure accounted for the cost lasts decline, and the farmers' income has gone up. The peasants express, the used water is few, and it is few to till land, but the income is many, and life is better.

  • PDF