• Title/Summary/Keyword: Operational Mode

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Optimum amount of additive mass in scaling of operational mode shapes

  • Khatibi, M.M.;Ashory, M.R.;Albooyeh, A.R.
    • Structural Engineering and Mechanics
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    • v.39 no.5
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    • pp.733-750
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    • 2011
  • Recently, identification of modal parameters using the response only data has attracted considerable attention particularly where the classic modal testing methods is difficult to conduct. One drawback of the response only data, also known as Operational Modal Analysis (OMA), is that only the unscaled mode shapes can be obtained which restricts the applications of OMA. The Mass change method is a usual way to scale the operational mode shapes. In this article a new method is proposed to optimize the additive mass for scaling of the unscaled mode shapes from OMA for which a priori knowledge of the Finite Element model of structure is required. It is shown that the total error of the scaled mode shapes is minimized using the proposed method. The method is validated using a numerical case study of a beam. Moreover, the experimental results of a clamped-clamped beam demonstrate the applicability of the method.

The Effects of Institutions on Foreign Subsidiary's Operational Mode of Korean Firms (진출국 제도가 해외 자회사 운영 방식 선택에 미치는 영향에 관한 연구)

  • Lee, Eung Sok
    • International Area Studies Review
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    • v.22 no.1
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    • pp.61-78
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    • 2018
  • Foreign subsidiary operation modes can be broadly divided into horizontal subsidiaries and vertical subsidiaries. According to institutional theory, foreign subsidiary operation mode differs depending on the host country institution. This study examines the effects of formal and informal institution on the foreign subsidiary operational mode of Korean firms. As a result of the empirical analysis, the higher the cultural distance and the lower political risks, the more favored the vertical foreign operation mode than the horizontal foreign operation mode. On the other hand, the higher the economic freedom and the lower corruption, the more favored the horizontal foreign operation mode than the vertical foreign operation mode.

Pilot Plant Study on Biological Nutrient Removal of Wastewater

  • Ahn, Sang-Jin;Kim, Geon-Heung;Ahn, Bok-Kyoun
    • Korean Journal of Hydrosciences
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    • v.1
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    • pp.99-106
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    • 1990
  • An extensive biological nutrient removal pilot plant study of anoxic/anaerobic/ aerobic treatment process was conducted to eastblish an optimum operational mode using primary dffluent. Two operational modes, (1) Qr/Q was 3.0 and maintaining EMLSS of 3100 mg/L in which the best operational results were obtained from previous bench scale study using synthetic wastewater (2) Qr/Q was 0.5 and EMLSS of 2200 mg/L which was compatible with the main plant, were Compared and evaluated for removal of nitrogen and/or phosphorous under field conditions. The nitrogen removal increased with increasing recycle ratios, but the phosphorous removal revealed more consistent results with 83percent removal efficiency in the second mode compared with 80 percent in the first mode. Above all, the two modes equally showed good BOD and nitrogen removals by nitrification-denitrification processes. It was also observed that no scum formed in the pilot plant and the sludge exhibited excellent settling characteristic all the time. The modified biological nutrient removal train can be adopted to the main plant without any major changes of their operational modes.

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A Study on Target Operational Availability Setting for Warship based on OMS/MP and Similar Warship RAM Analysis (함정 OMS/MP 및 유사체계 RAM분석 활용 기반 목표운용가용도 설정 연구)

  • Ha, Sungchul;Kim, Kyoungyong
    • Journal of the Korea Institute of Military Science and Technology
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    • v.15 no.5
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    • pp.651-659
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    • 2012
  • Target operational availability setting is the first step to setting up a goal which a weapon system development project have to achieve and doing RAM analysis during whole life of a weapon system. It is important as a key factor to doing RAM analysis in the early phase of weapon system development. This paper present a methodology to set a target operational availability for, especially, a warship when it develop. This methodology uses Operational Mode Summary/Mission Profile(OMS/MP) of the developing warship and RAM analysis results of similar warships to calculate wartime and peacetime target operational availability. It will be used in early phase of not only warship development but also army or aircraft weapon systems when these develop.

Investigating Buck DC-DC Converter Operation in Different Operational Modes and Obtaining the Minimum Output Voltage Ripple Considering Filter Size

  • Babaei, Ebrahim;Mahmoodieh, Mir Esmaeel Seyed;Sabah, Mehran
    • Journal of Power Electronics
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    • v.11 no.6
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    • pp.793-800
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    • 2011
  • This paper investigates the operational modes of buck dc-dc converters and their energy transmission methods. The operational modes of such converters are classified in two types, discontinuous conduction mode (DCM) and continuous conduction mode (CCM). In this paper, the critical inductance relation of DCM and CCM is determined. The equations of the output voltage ripple (OVR) for each mode are obtained for a specific input voltage and load resistance range. The maximum output voltage ripple (MOVR) is also obtained for each mode. The filter size is decreased and the minimum required inductance value is calculated to guarantee the minimization of the MOVR. The experimental and simulation results in PSCAD/EMTDC prove the correctness of the presented theoretical concepts.

Operational Mode Analysis of Cooler Driver Electronics in Satellite and System Safety Margin

  • Kim, Kyudong
    • Journal of Aerospace System Engineering
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    • v.14 no.6
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    • pp.79-84
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    • 2020
  • Cooler driver electronics (CDE) for maintaining low temperature of the satellite payload IR sensor consists of a compressor that has a pulsation current load condition when it is operated. This pulsation current produces large voltage fluctuation, which affects both load and regulated bus stability. Thus, CDE power conditioning system consists of a primary bus, infrared power distribution unit for battery charging and protection, reverse current protection diode, and battery, which is used as a buffer. In this study, the operational mode analysis is performed by each part with equivalent impedance modeling verified through system level simulation. From this mode analysis, the safety margin for state of charge and open circuit voltage of the battery is determined for satisfying the minimum operational voltage of the CDE load.

Design of Operational Test Equipments for VDL Mode 2 System Validation (VDL Mode 2 시스템 검증을 위한 운용시험장비 설계)

  • Bae, Joong-won;Kim, Tae-sik;Lee, Hae-chang
    • Journal of Aerospace System Engineering
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    • v.2 no.3
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    • pp.33-39
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    • 2008
  • VDL Mode 2 is one of air-to-ground VHF digital data link technologies. The VDL Mode 2 system is designed to be an air-to-ground subnetwork of the Aeronautical Telecommunication Network (ATN) using the AM(R)S band and it is organized according to the Open System Interconnection (OSI) model (defined by ISO). It can be used in ATS Applications especially for ATC communication such as CPDLC and ADS as well. And It is expected VDL Mode 2 replaces ACARS(Aircraft Communications Addressing and Reporting System) which has broadly been used for over 20 years. This paper presents the result of design of operational test equipments for the validation of VDL Mode 2 system under development in KARI.

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KOMPSAT-2 AOCS Control Mode & Power Safe Mode Design

  • Rhee, Seung-Wu;Kim, Hak-Jung;Lee, Joo-Jin
    • International Journal of Aeronautical and Space Sciences
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    • v.6 no.1
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    • pp.77-88
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    • 2005
  • KOMPSAT-2 is the second Korean earth observation satellite after KOMPSAT-l: the 1 meter GSD cartographic capability and planning to launch at the end of 2005 by ROKOT launch vehicle. The dedicated AOCS operational modes are designed for KOMPSAT-2 based on KOMPSAT-l experience All of AOCS operational modes requires gyro information. To compensate this drawback, Power Safe Mode is designed and implemented. Successfully AOCS on-board software is developed and extensively verified through a nonlinear simulation process. The simulation results of Power Safe Mode and Science Fine Submode are provided to demonstrate its functionality as well as its performance.

Effects of intermittent effluent recycling on the performance of UASB process (간헐적인 유출수 반송이 UASB 반응조 운전효율에 미치는 영향)

  • 이헌모;양병수
    • Journal of Environmental Science International
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    • v.2 no.4
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    • pp.317-324
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    • 1993
  • Effluent recycling effect on UASB reactor performances is known as an important operational factor. In the present study, the possibility of intermittent recycle in UASB process for saving the power consumption was examined at different organic loading and various operational modes in recycle time period. The organic removal efficiencies of the reactors operated with the intermittent effluent recycle were considerably higher compared to those without the effluent recycle. In the intermittent recycle mode, the organic removal efficiencies slightly decreased as the non-recycle time period in the operational mode increased. Proper ratio of recycle and non-recycle time period in the mode seemed to be required to prevent the produced biogas from accumulation in the sludge bed, which caused dead zone in the reactor and sludge loss when the gas was escaped from the bed at the certain pressure.

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Enhanced least square complex frequency method for operational modal analysis of noisy data

  • Akrami, V.;Zamani, S. Majid
    • Earthquakes and Structures
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    • v.15 no.3
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    • pp.263-273
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    • 2018
  • Operational modal analysis is being widely used in aerospace, mechanical and civil engineering. Common research fields include optimal design and rehabilitation under dynamic loads, structural health monitoring, modification and control of dynamic response and analytical model updating. In many practical cases, influence of noise contamination in the recorded data makes it difficult to identify the modal parameters accurately. In this paper, an improved frequency domain method called Enhanced Least Square Complex Frequency (eLSCF) is developed to extract modal parameters from noisy recorded data. The proposed method makes the use of pre-defined approximate mode shape vectors to refine the cross-power spectral density matrix and extract fundamental frequency for the mode of interest. The efficiency of the proposed method is illustrated using an example five story shear frame loaded by random excitation and different noise signals.