• Title, Summary, Keyword: w-operation

Search Result 2,292, Processing Time 0.043 seconds

The Analysis of Operation Effect for 3kW Utility interactive PV System (30kW 주택보급계통연계형 태양광발전시스템 운용효율 분석)

  • Park, J.M.;Kim, K.B.;Lim, H.W.;Kim, D.H.;Baek, H.N.;Cho, G.B.
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.231-233
    • /
    • 2003
  • This paper presents experimental operation with utility interactive 3kW photovoltaic generation system. The status of Photovoltaic generation system components and inter-connection and safety equipment will be summarized. This paper discusses property operation state which 3kW utility interactive photovoltaic generation system was analysed from January 2001 to December 2002.

  • PDF

τw-LOEWY MODULES AND THEIR APPLICATIONS

  • Kim, Hwankoo;Lim, Jung Wook;Zhou, Dechuan
    • Bulletin of the Korean Mathematical Society
    • /
    • v.56 no.6
    • /
    • pp.1617-1642
    • /
    • 2019
  • In this paper, we study a theory for the structure of ${\tau}_w$-Loewy series of modules over commutative rings, where ${\tau}_w$ is the hereditary torsion theory induced by the so-called w-operation, and explore the relationship between ${\tau}_w$-Loewy modules and w-Artinian modules.

ANALYSIS ON THE AVAILABILITY OF COMS GS

  • Park, Durk-Jong;Lim, Hyun-Su;Ahn, Sang-Il
    • Proceedings of the KSRS Conference
    • /
    • v.1
    • /
    • pp.212-215
    • /
    • 2006
  • This paper describes several reliability models to estimate COMS ground segment availability and shows assessed availability according to GS function. Due to a back-up concept among three ground center, SOC will have all H/W and S/W module to be installed in MSC and KOSC site. Therefore, all configurations and availability parameters for H/W and S/W modules in MSC and KOSC are assumed as equal with those in SOC, if related modules have same function. Prior to access availability over COMS GS function, Availability related to fundamental configuration such as series, parallel, partial operation, and module combined H/W and S/W is described. Consequently, all functions are expected to operate with more than 99% of availability.

  • PDF

Self-sustainable Operation of a 1kW class SOFC System (1kW급 고체산화물 연료전지 발전시스템 자열운전)

  • Lee, Tae-Hee;Choi, Jin-Hyeok;Park, Tae-Sung;Yoo, Young-Sung
    • 한국신재생에너지학회:학술대회논문집
    • /
    • /
    • pp.57-60
    • /
    • 2008
  • KEPRI has studied planar type SOFC stacks using anode-supported single cells and kW class co-generation systems for residential power generation. A 1kW class SOFC system consisted of a hot box part, a cold BOP part and a water reservoir. A hot box part contains a SOFC stack made up of 48 single cells and ferritic stainless steel interconnectors, a fuel reformer, a catalytic combustor and heat exchangers. Thermal management and insulation system were especially designed for self-sustainable operation. A cold BOP part was composed of blowers, pumps, a water trap and system control units. When a 1kW class SOFC system was operated at $750^{\circ}C$ with hydrogen after pre-treatment process, the stack power was 1.2kW at 30 A and 1.6kW at 50A. Turning off an electric furnace, the SOFC system was operated using hydrogen and city gas without any external heat source. Under self-sustainable operation conditions, the stack power was about 1.3kW with hydrogen and 1.2kW with city gas respectively. The system also recuperated heat of about 1.1kW by making hot water.

  • PDF

*-NOETHERIAN DOMAINS AND THE RING D[X]N*, II

  • Chang, Gyu-Whan
    • Journal of the Korean Mathematical Society
    • /
    • v.48 no.1
    • /
    • pp.49-61
    • /
    • 2011
  • Let D be an integral domain with quotient field K, X be a nonempty set of indeterminates over D, * be a star operation on D, $N_*$={f $\in$ D[X]|c(f)$^*$= D}, $*_w$ be the star operation on D defined by $I^{*_w}$ = ID[X]${_N}_*$ $\cap$ K, and [*] be the star operation on D[X] canonically associated to * as in Theorem 2.1. Let $A^g$ (resp., $A^{[*]g}$, $A^{[*]g}$) be the global (resp.,*-global, [*]-global) transform of a ring A. We show that D is a $*_w$-Noetherian domain if and only if D[X] is a [*]-Noetherian domain. We prove that $D^{*g}$[X]${_N}_*$ = (D[X]${_N}_*$)$^g$ = (D[X])$^{[*]g}$; hence if D is a $*_w$-Noetherian domain, then each ring between D[X]${_N}_*$ and $D^{*g}$[X]${_N}_*$ is a Noetherian domain. Let $\tilde{D}$ = $\cap${$D_P$|P $\in$ $*_w$-Max(D) and htP $\geq$2}. We show that $D\;\subseteq\;\tilde{D}\;\subseteq\;D^{*g}$ and study some properties of $\tilde{D}$ and $D^{*g}$.

Constitution and Operation of the 25 kW Molten Carbonate Fuel Cell Power Generation System for Power Utility (25 kW급 전력사업용 MCFC 발전시스템 구성 및 운전평가)

  • Lim, Hee-Chun;Ahn, Kyo-Sang
    • Proceedings of the KIEE Conference
    • /
    • /
    • pp.687-689
    • /
    • 2000
  • Molten Carbonate Fuel Cell (MCFC) with high electrical efficiency and low environmental effect has been developed for the commercial application of power generation fields. Recently we have built a 25 kW molten carbonate fuel cell power generation system and tested it. The MCFC system is composed of diverse peripheral units such as reformer, pre-heater, water purifier. electrical loader, gas supplier, and recycling systems. The stack itself was made of 40 cells of $6.000 cm^2$ area each. The stack showed an output of 28.6 kW power and a reliable performance at atmospheric operation. while in pressurized operation the stack showed an output 25.6 kW lower than the atmospheric operation. The reason of lower performance of pressurized operation was caused from a gas cross over shown in few cells in the stack.

  • PDF

Analysis of Power Requirement of Agricultural Tractor by Major Field Operation (농업용 트랙터의 주요 농작업 소요동력 분석)

  • Kim, Yong-Joo;Chung, Sun-Ok;Park, Seung-Jae;Choi, Chang-Hyun
    • Journal of Biosystems Engineering
    • /
    • v.36 no.2
    • /
    • pp.79-88
    • /
    • 2011
  • The purpose of this study was to analyze power requirement of an agricultural tractor by major field operations. First a survey was conducted to obtain annual usage ratio of agricultural tractor by field operation. Plowing, rotary tillage, and loader operations were selected as major field operations of agricultural tractor. Second, a power measurement system was constructed with strain-gauge sensors to measure torque of four driving axles and a PTO axle, speed sensors to measure rotational speed of the driving axles and an engine shaft, pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to calculate power requirement. Third, the major field operations were experimented under fields with different soil conditions following planned operation paths. Power requirement was analyzed during the total operation period consisted of actual operation period (plowing, rotary tillage, and loader operations) and period before and after the actual operation (3-point hitch operating, forward and reverse driving, braking, and steering). Power requirement of tractor major components such as driving axle part, PTO part, main hydraulic part, and auxiliary hydraulic part were measured and calculated to determine usage ratio of agricultural tractor power. Results of averaged power requirement for actual field operation and total operation were 23.1 and 17.5 kW, 24.6 and 19.1 kW, and 14.9 and 8.9 kW, respectively, for plowing, rotary tillage, and loader operations. The results showed that rotary tillage required the greatest power among the operations. Averaged power requirement of driving axles, PTO axle, main hydraulic part, and auxiliary part during the actual field operation were 8.1, 7.8, 3.4, and 1.5 kW, respectively, and the total requirement power was about 70 % (20.8 kW) of the rated power. Averaged power requirement of driving axles, PTO axle, main hydraulic, and auxiliary hydraulic for the total operation period were 6.5, 6.0, 2.1, 0.9 kW, respectively, and total requirement power was about 52 % (15.5 kW) of the rated power. Driving axles required the greatest amount of power among the components.

Development of an 80[kW] IPMSM Drive System for an Electric Vehicle (전기자동차용 80[kW] IPMSM 구동 시스템 개발)

  • Kim, Sang-Hoon;Park, Nae-Chun
    • Journal of Industrial Technology
    • /
    • v.33 no.A
    • /
    • pp.61-66
    • /
    • 2013
  • This paper is about the development of 80[kW] IPMSM(Interior Permanent Magnet Synchronous Motor) drive system for an electric vehicle. MTPA(Maximum Torque per Ampere) operation and flux-weakening operation for the optimal torque control of the IPMSM are presented. In this system, the torque control of the IPMSM is achieved by using the look-up table, which gives d- and q-aixs current references for the given torque command in the MTPA operation and flux-weakening operation regions. This look-up table is made by current injection tests, and from which the motor parameters are also estimated. The proposed system is verified by the experiment on the electric vehicle drive system, which consists of an 80[kW] IPMSM and an IGBT inverter.

  • PDF

Development of 6kW ZVS Boost Converter by 4-Parallel Operation (4-병렬 제어 기법을 적용한 6kW 영전압 스위칭 승압형 컨버터 개발)

  • Rho, Min-Sik
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.58 no.1
    • /
    • pp.86-92
    • /
    • 2009
  • This paper presents development of 6kw ZVS(Zero Voltage Switching) boost converter by 4-parallel operation. To realize a high capacity converter with 6 kw, 4-parallel operation of 1.5kW unit module is proposed in this paper. To meet high ratio input to output voltage, isolated type booster converter is designed. To achieve ZVS operation of 4-switches of full bridge and protect a voltage overshoot caused by switch turn-off, simple active-clamp circuit is applied to the primary side. For parallel operation of 4-modules, master-slave control method is proposed to achieve input current sharing of 4-unit converter modules accurately. For performance tests, simulation is carried out. Also, load and experimental tests of the developed booster converter, 230Vdc/6kW, are carried out under various conditions. For field tests, the developed converter is applied for boosting a battery power to high DC_link voltage for a VSI inverter which starts a micro-turbine(MT) installed in vehicle and it's performance is verified through high speed motoring a MT up to tens of thousands of rpm.

Section Voltage Calculation while a Loop Operation by Tie-Switch Close in a Distribution Management System (배전운영 시스템에서 상시개방 연계 스위치 투입에 의한 루프 운전 중 구간전압 계산 방법)

  • Seo, Jeong-Soo;Lim, Il-Hyung;Park, Jong-Ho;Shin, Yonh-Hak;Choi, Myeon-Song
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.65 no.3
    • /
    • pp.397-403
    • /
    • 2016
  • Generally, an electrical distribution configuration is a radial system with one-way current in a distribution management system (DMS). All feeders in a DMS have tie-switches to make radial system. Sometimes, DMS should change a tie-switch for operation. In that case, the tie-switch has to be closed first; then a switch is opened as another tie-switch in order to prevent blackout for customers. At the moment when the tie-switch is closed, distribution system is operated in a loop state, not radial. Before the loop operation, DMS operator has to check any expected events for stable distribution system operation; and the most important event is a mis-operation of a protection relay. In addition, DMS operator should check voltage profile violation but a calculation method of section voltages had not been used. Thus, this paper proposes a calculation method of section voltages at a loop operation in a DMS. The proposed calculation algorithm is verified by Matlap Simulink.