• Title/Summary/Keyword: Operation level

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Redundancy Module Operation Analysis of MMC using Scaled Hardware Model (축소모형을 이용한 MMC의 Redundancy Module 동작분석)

  • Yoo, Seung-Hwan;Shin, Eun-Suk;Choi, Jong-Yun;Han, Byung-Moon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.8
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    • pp.1046-1054
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    • 2014
  • In this paper, a hardware prototype for the 10kVA 11-level MMC was built and various experimental works were conducted to verify the operation algorithms of MMC. The hardware prototype was designed using computer simulation with PSCAD/EMTDC software. After manufactured in the lab, the hardware prototype was tested to verify the modulation algorithms to form the output voltage, the balancing algorithm to equalize the sub-module capacitor voltage, and the redundancy operation algorithm to improve the system reliability. The developed hardware prototype can be utilized for analyzing the basic operation and performance improvement of MMC according to the modulation and redundancy operation scheme. It also can be utilize to analyze the basic operational characteristics of HVDC system based on MMC.

A study of the relationship between the subjective symptoms of VDT syndrome and occupational factors in VDT operators (VDT작업자의 작업조건과 다발하는 자각증상과의 관련성에 관한 연구)

  • Kim Kap-Sung;Lee Seung-Deok
    • Journal of Acupuncture Research
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    • v.18 no.6
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    • pp.70-83
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    • 2001
  • Objective : In order to investigate symptoms prevalence related to visual display terminal(VDT) syndrome, and to evaluate the variables affecting the development of the VDT syndrome. Methods : a questionnaire survey was conducted on 127(81 men and 46 women) VDT operators who had been studied in Soongsil University graduated school in Seoul. Result : As a result of analysis with data collected by questionnaire, l. Variables affecting the level of general symptoms were sex, the total time of VDT operation per day, type of typewriting, location of keyboard, illumination, VDT working duration, the time of VDT operation without rest. 2. Variables affecting the level of eye symptoms were sex, the total time of VDT operation per day, type of typewriting, VDT working duration, illumination, method of eye-resting. 3. Variables affecting the level of musculoskeletal symptoms were sex, the total time of VDT operation per day, the time of VDT operation without rest, illumination. Conculsions : In order to protect workers from VDT syndrome, it is urgently required to implement standard management recommendations including restriction of VDT working hours and allowance of more sufficient resting time for VDT workers.

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Large Step Optimization Approach to Flexible Job Shop Scheduling with Multi-level Product Structures (다단계 제품 구조를 고려한 유연 잡샵 일정계획의 Large Step Optimization 적용 연구)

  • Jang, Yang-Ja;Kim, Kidong;Park, Jinwoo
    • Proceedings of the Korea Inteligent Information System Society Conference
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    • 2002.05a
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    • pp.429-434
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    • 2002
  • For companies assembling end products from sub assemblies or components, MRP (Material Requirement Planning) logic is frequently used to synchronize and pace the production activities for the required parts. However, in MRP, the planning of operational-level activities is left to short term scheduling. So, we need a good scheduling algorithm to generate feasible schedules taking into account shop floor characteristics and multi-level job structures used in MRP. In this paper, we present a GA (Genetic Algorithm) solution for this complex scheduling problem based on a new gene to reflect the machine assignment, operation sequences and the levels of the operations relative to final operation. The relative operation level is the control parameter that paces the completion timing of the components belonging to the same branch in the multi-level job hierarchy. In order to revise the fixed relative level which solutions are confined to, we apply large step transition in the first step and GA in the second step. We compare the genetic algorithm and 2-phase optimization with several dispatching rules in terms of tardiness for about forty modified standard job-shop problem instances.

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Floating Power Supply Based on Bootstrap Operation for Three-Level Neutral-Point-Clamped Voltage-Source Inverter

  • Nguyen, Qui Tu Vo;Lee, Dong-Choon
    • Proceedings of the KIPE Conference
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    • 2011.11a
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    • pp.3-4
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    • 2011
  • This paper presents a survey of floating power supply based on bootstrap operation for three-level voltage-source inverters. The floating power supply for upper switches is achieved by the bootstrap capacitor charged during on-time of the switch underneath. Hence, a large number of bulky isolated DC/DC power supplies for each gate driver are reduced. The Pspice simulation results show the behavior of bootstrap devices and the performance of bootstrap capacitor voltage.

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Excitation Voltage Control of SRM with Multi-Level Inverter (멀티레벨 인버터를 이용한 SRM의 여자전압제어)

  • Kang Yu-Jung;Lee Sang-Hun;Park Sung-Jun;Ahn Jin-Woo
    • Proceedings of the KIPE Conference
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    • 2001.12a
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    • pp.29-32
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    • 2001
  • The application of SRM(Switched Reluctance Motor) is dramatically increasing due to a simple mechanical structure, high efficiency and a good high speed characteristics. To control high conduction ratio in motor operation and regenerative voltage in the generator operation multi-level voltage control is effective. This paper proposes multi-level inverter to have a maximum conduction ratio of SRM. The proposed method is verified by experiments.

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A New Topology of Four-Level Hybrid Half-Bridge Flying-Capacitor Inverter (4-레벨 하이브리드 하프 브리지 플라잉 캐패시터 인버터의 새로운 토폴로지)

  • Pribadi, Jonathan;Lee, Dong-Choon
    • Proceedings of the KIPE Conference
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    • 2019.07a
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    • pp.315-316
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    • 2019
  • This paper proposes the operation scheme and control method for a four-level hybrid half-bridge flying-capacitor inverter (4L-HHBFCI). With in-phase disposition level-shifted modulation (IPD), the flying capacitor voltage ripple is less than 1% of the reference value, while the line-to-line voltage total harmonic distortion is 23.27% at unity modulation index. The performance and effectiveness of the proposed inverter operation have been verified by simulation results.

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Influence of Autologous and Homologous Blood Transfusion on Interleukins and Tumor Necrosis Factor-α in Peri-operative Patients with Esophageal Cancer

  • Xing, Yue-Li;Wang, Yan-Chun
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.18
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    • pp.7831-7834
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    • 2014
  • Objective: To explore the influence of different ways of blood transfusion on the expression levels of interleukins (IL) and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) inperi-operative patients with esophageal cancer. Materials and Methods: A total of 80 patients with esophageal cancer who underwent radical operations were selected as study patients and randomly divided into an observation group (treated with autologous blood transfusion) and control group (with homologous blood transfusion). Changes of intra-operative indexes and peri-operative blood indexes, from hemoglobin (Hb) and hematocrit value (Hct), to levels of inflammatory factors like interleukins-6 (IL-6), IL-8, IL-10 and tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) were compared. Results: Operations for patients in both groups were successfully conducted, and no significant differences in mean surgical duration and intra-operative hemorrhage volume, fluid infusion volume and blood transfusion volume were detected (p>0.05). Compared with values before surgery, Hb and Hct levels decreased significantly while white blood cell count (WBC) increased 1, 5 and 7 d after operation (p<0.05, p<0.01). In addition, WBC was apparently higher in observation group than in control group 5 and 7 d after operation (p<0.01). Compared with before surgery, in the observation group, levels of IL-6, IL-8 and IL-10 had no significant differences after operation (P>0.05), but TNF-${\alpha}$ level increased y (p<0.01), whereas in control group, IL-6 level had no significant difference (p>0.05), IL-8 level decreased obviously (p<0.05), IL-10 level increased markedly first and then decreased gradually as time passed but its level remained elevated (p<0.01), and TNF-${\alpha}$ level increased first and then decreased, and there was no significant difference 7 d after operation (p>0.05). Conclusions: Decreased IL-8 and increased IL-10 levels are two important reasons for immunosuppression after homologous blood transfusion, whereas autologous blood transfusion can alleviate this while increasing the TNF-${\alpha}$ level, which also has potential to improve anti-tumor immunity in the human body.

Conceptual Design of Navigation Safety Module for S2 Service Operation of the Korean e-Navigation System

  • Yoo, Yun-Ja;Kim, Tae-Goun;Song, Chae-Uk;Hu, Shouhu;Moon, Serng-Bae
    • Journal of Navigation and Port Research
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    • v.41 no.5
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    • pp.277-286
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    • 2017
  • IMO introduced e-Navigation concept to improve the efficiency of ship operation, port operation, and ship navigation technology. IMO proposed sixteen MSPs (Maritime Service Portfolio) applicable to the ships and onshore in case of e-Navigation implementation. In order to meet the demands of the international society, the system implementation work for the Korean e-Navigation has been specified. The Korean e-Navigation system has five service categories: the S2 service category, which is a ship anomaly monitoring service, is a service that classifies emergency levels according to the degree of abnormal condition when a ship has an abnormality in ship operation, and provides guidance for emergency situations. The navigation safety module is a sub-module of the S2 service that determines the emergency level in case of navigation equipment malfunctioning, engine or steering gear failure during navigation. It provides emergency response guidance based on emergency level to the abnormal ship. If an abnormal condition occurs during the ship operation, first, the ship shall determine the emergency level, according to the degree of abnormality of the ship. Second, an emergency response guidance is generated based on the determined emergency level, and the guidance is transmitted to the ship, which helps the navigators prevent accidents and not to spread. In this study, the operational concept for the implementation of the Korean e-Navigation system is designed and the concept is focused on the navigation safety module of S2 service.

THE BASIC DESIGN AND ANALYSIS OF UNMANNED VEHICLE FOR TH TELE-OPERATION CONTROL (원격주행을 위한 무인 자동차에 관한 기본설계와 성능분석에 관한 연구)

  • 심재흥;윤득선;김민석;김정하
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.139-139
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    • 2000
  • The subject of this paper is the tole operation for unmanned vehicle. The aim is studied in context of motor control system and algorithms for the mid to low level control of tele operation unmanned vehicle described. Modern, vehicle related researches have been implemented about control, chassis, body and safe쇼 but now is to driving comfort, I.T.S. and human factor, etc. As a result of this fact, unmanned vehicle is main research topic over the world but it is still very expensive and unreasonable. A hierarchical approach is studied in context of motor control system and algorithms for the mid to low level control of tele operation unmanned vehicle described. The real time control and monitoring of longitudinal, lateral, Pitching motion is to be solved by system integration and optimization technique. We show the experimental result about fixed brake range test and acceleration test. And all system is to integrated for driving simulator and unmanned vehicle.

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Dynamics Modeling and Operation Simulation for the Simulation of Abrupt Faults in the Boiler Drum Level Control System of a Fossile Power Plant (돌발성 이벤트 형태의 고장 시뮬레이션을 위한 화력발전소 보일러 드럼 수위 제어 계통의 다이나믹스 모델링 및 운전 시뮬레이션)

  • Kim, Jeong-Geun;Kim, Jae-Hwa;Jang, Tae-Gyu
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.51 no.2
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    • pp.59-68
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    • 2002
  • This Paper presents the dynmics modeling and the operation simulation of the 500 MW drum-type boiler and its control system hosted in the Boryung Power Plant unit #1 and #2. The fidelity of the modeling and the operation simulation is well verified by their agreement with the actual data obtained form the plant operation. As a plant signal generator for the various operation patterns and fault situations, the simulation environment will be utilized to develope the fault detecting signal processing algorithms.