• Title/Summary/Keyword: Mode of Operation

Search Result 2,505, Processing Time 0.027 seconds

A Study about Applicability of Treatment for Backwash Water Using Tubular Membrane System with Dead-End Operation Mode (역세 배출수 처리를 위한 관형막의 전량여과 운전 적용에 대한 연구)

  • Eom, Jung Yeol;Kim, Kwan Yeop;Kim, Young Hoon;Song, June Sup;Kim, Hyung Soo;Han, Myung Ae;Yang, Hyung Seok
    • Journal of Korean Society of Water and Wastewater
    • /
    • v.22 no.4
    • /
    • pp.437-444
    • /
    • 2008
  • Many other countries have investigated the new backwash water treatment process to save the existing water resource. There are various methods for reusing backwash water, but the membrane system has received the most interest for its efficiency. The objective of this study was to certify the application of membrane filtration system for the backwash water treatment. The experiment equipment was composed of Lab scale tubular membrane filtration system. Generally, cross-flow operation mode is used in the tubular membrane system but cross-flow operation mode demands high electric cost mainly for the pump energy. So to cut off electric cost, dead-end operation mode was used in this experiment. Filtration and bleed operation cycle was used in this membrane system. Backwash water was concentrated during the filtration process and when backwash water reached our target suspended solid concentration, it was discharged from this system. For efficient operation of filtration and bleed, mathematical matrix was drawn up and with this matrix we could simulate various sets of filtration and bleed time.

A Study on Bundang-line Urban Transit Operation Mode and Operation Algorithm Analysis of an ATC System (분당선 도시철도 운전모드와 ATC 시스템 동작알고리즘에 관한 연구)

  • Kim Jong-ki;Lee Key-soe
    • Proceedings of the KSR Conference
    • /
    • 2004.06a
    • /
    • pp.1247-1252
    • /
    • 2004
  • ATC(Automatic Train Control) system employed in Bundang urban transit is operated in accordance with automatic blocking equipment. Using AF(Audio Frequency) track circuits installed at a block section, the block signal is automatically controlled and the safety of train operation is supported. In this paper, we investigate the operation mode of bundang urban transit and analyze the operation algorithm of ATC on-board system.

  • PDF

A Study on Failure Mode and Effect Analysis (FMEA) for Preoperative Risk Prevention (오류유형 영향분석(FMEA)을 적용한 수술준비 위험예방활동의 효과)

  • Kim, Chang Hee;Lee, Mi Hyang
    • Journal of Korean Academy of Nursing Administration
    • /
    • v.22 no.5
    • /
    • pp.415-423
    • /
    • 2016
  • Purpose: The purpose of this research was to provide patients with safe preoperative preparatory procedures by removing any risk factors from the preparatory procedures by using failure mode and effects analysis, which is a prospective risk-managing tool. Methods: This was a research design in which before and after conditions of a single group were studied, Failure mode and effects analysis were applied for the preparatory procedures done before operations. Results: The preparation omission rate before the operation decreased from 2.70% to 0.04%, and operation cancellation rate decreased from 0.48% to 0.08%. Conclusion: Failure mode and effects analysis which remove any risk factors for patients in advance of the operation is effective in preventing any negligent accidents.

Idle Mode for Deep Power Save in IEEE 802.11 WLANs

  • Jin, Sung-Geun;Han, Kwang-Hun;Choi, Sung-Hyun
    • Journal of Communications and Networks
    • /
    • v.12 no.5
    • /
    • pp.480-491
    • /
    • 2010
  • Along with the wide acceptance of IEEE 802.11 wireless local area network (WLAN), new applications such as Internet protocol (IP) telephony over WLAN are fast emerging today. For battery-powered IP phone devices, the life time extension is a key concern for the market acceptance while today's 802.11 is not optimized for snch an operation. In this paper, we propose a novel idle mode operation, which comprises paging, idle handoff, and delayed handoff. Under the idle mode operation, a mobile host(MH) without any active session does not need to perform handoff within a predefined paging area (PA). Only when it enters a new PA, an idle handoff is performed. The proposed idle mode allows an MH without traffic to extend its life time. We develop a new analytical model in order to comparatively evaluate our proposed scheme. The numerical resnlts demonstrate that the proposed scheme outperforms the existing schemes with respect to power consumption.

Analysis, Design, and Implementation of a Single-Phase Power-Factor Corrected AC-DC Zeta Converter with High Frequency Isolation

  • Singh, Bhim;Agrawal, Mahima;Dwivedi, Sanjeet
    • Journal of Electrical Engineering and Technology
    • /
    • v.3 no.2
    • /
    • pp.243-253
    • /
    • 2008
  • This paper deals with the analysis, design, and implementation of a single phase AC-DC Zeta converter with high frequency transformer isolation and power factor correction(PFC) in two modes of operation, discontinuous current mode of operation(DCM), and continuous current mode of operation(CCM). A Digital Signal Processor(DSP) based implementation is carried out for validation of the Zeta converter developed design in discontinuous mode of operation. A comparison of both modes of operation is presented for a 1kW power rating from the point of view of steady state and dynamic behavior, power quality, simplicity, control technique, device rating, and converter size. The experimental results of a developed prototype of Zeta converter are presented for validation of the developed design. It is observed that CCM is most suitable for higher power applications where it requires some complex control and sensing of the additional variables.

3-Level T-type Inverter Operation Method Using Level Change

  • Kim, Tae-Hun;Lee, Woo-Cheol
    • Journal of Electrical Engineering and Technology
    • /
    • v.13 no.1
    • /
    • pp.263-269
    • /
    • 2018
  • In this study, a selective inverter operation between a 2-level voltage source converter (VSC) and a 3-level T-type VSC (3LT VSC) is proposed to improve the efficiency of a 3LT VSC. The 3LT VSC topology, except for its neutral-point switches, has similar operations as that of the 2-level VSC. If an operation mode is changed according to efficiency, the efficiency can be improved because efficiencies of each methods are depending on current and MI (Modulation Index). The proposed method calculates the power losses of the two topologies and operates as the having lower losses. To calculate the losses, the switching and conduction losses based on the operation mode of each topology were analyzed. The controller determined the operation mode of the 2- or 3-level VSC based on the power loss calculated during every cycle. The validity of the proposed control scheme was investigated through simulation and experiments. The waveform and average efficiency of each method were compared.

Seamless Mode Transfer of Indirect Current Controlled Parallel Grid-Connected Inverters (간접전류제어방식 병렬형 계통연계 인버터의 무순단 모드절환)

  • Song, Injong;Choi, Junsoo;Lim, Kyungbae;Choi, Jaeho
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.24 no.5
    • /
    • pp.334-341
    • /
    • 2019
  • This study proposes the control strategy for the seamless mode transfer of indirect current controlled parallel grid-connected inverters. Under the abnormal grid condition, the grid-connected inverter can convert the operation mode from grid-connected to stand-alone mode to supply power to the local load. For a seamless mode transfer, the time delay problems caused by the accumulated control variable error must be solved, and the indirect current control method has been applied as one of the solutions. In this study, the design of control parameters for the proportional-resonant-based triple-loop indirect current controller and the control strategy for the seamless mode transfer of parallel grid-connected inverters are described and analyzed. The validity of the proposed mode transfer method is verified by the PSiM simulation results.

A Basic Study on Mode of Operation for Maritime Autonomous Surface Ship

  • Jeong-Min, Kim;Hye Ri, Park
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • 2023.05a
    • /
    • pp.162-163
    • /
    • 2023
  • As the development of the 4th industiral revolution in the maritime industry has progressed, the technical development of autonomous ships, and the development of international regulations have been accelerated. In particular, the IMO Maritime Safety Committee(MSC) has established a road-map for the development of the non-mandatory goal-based MASS instrument(MASS Code) and started developing a non-mandatory MASS Code at MSC 105th meeting. Many countries are actively participating in the Correspondence Group on the development of MASS Code, and the development of detailed requirements for MASS functions in the MASS Code is underway. Especially, the concept of "Mode of Operation" for MASS functions was mentioned in the Correspondence Group for the first time, and it is expected that discussions on these modes will be conducted from the IMO MASS JWG meeting to held in April 2023. The concept of "Mode of Operation" will be useful in explaining MASS and MASS functions and will be discussed in the future for the development of MASS Code. This paper reviews the contents of the IMCA M 220 document, which provides guidelines on operating modes, to conduct research on the benchmark for setting the operating modes of MASS.

  • PDF

Modification to Traffic Indication Method for IEEE 802.16 Sleep Mode Operation (IEEE 802.16 시스템의 슬립모드 동작을 위한 트래픽 인디케이션 방식의 개선)

  • Kim, Beom-Joon
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.8 no.6
    • /
    • pp.823-829
    • /
    • 2013
  • IEEE 802.16 standard specifies the broadband wireless access (BWA) system including sleep mode to minimize the power consumption by a mobile station (MS). This paper outlines the overall operation of sleep mode and proposes a method to improve the power saving efficiency of the IEEE 802.16 sleep mode. The proposed method not only decreases the number of bytes that a MS in sleep mode needs to receive during listening interval but allows to indicate a control-specific operation such as periodic ranging.

Start-up Strategy for the Successful Operation of Continuous Fermentative Hydrogen Production (연속 혐기성 수소발효 공정에서 성공적인 start-up 방법)

  • Lee, Chang-Kyu
    • Journal of Hydrogen and New Energy
    • /
    • v.24 no.2
    • /
    • pp.99-106
    • /
    • 2013
  • The variations of performance and metabolites at an early stage were investigated for the successful start-up technology in continuous fermentative hydrogen production. Unsuccessful start-up was observed when the operation mode was changed from batch to continuous mode after the yield was reached to 0.5 mol $H_2$/mol $hexose_{added}$ by batch mode. $H_2$ production continued till 12 hours accompanied by butyrate production, but did not last with propionate production increase. It was suspected that the failure was due to the regrowth of propionic acid bacteria during batch mode which were inhibited by heat-shock but not completely killed. Thus, successful start-up was tried by early switchover from batch to continuous operation; continuous operation was started after the $H_2$ yield was reached to 0.2 mol $H_2$/mol $hexose_{added}$ by batch mode. Although $H_2$ production rate decreased at an early stage, stable $H_2$ yield of 0.8 mol $H_2$/mol $hexose_{added}$ was achieved after 10 days by lowering down propionate production. And it was also concluded that the reason for $H_2$ production decrease at an early stage was due to alcohol production by self detoxification mechanism against VFAs accumulation.