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Perceptions and Use of Open Access Journals by Nigerian Postgraduate Students

  • Ayeni, Philips Oluwaseun
    • Journal of Information Science Theory and Practice
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    • v.5 no.1
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    • pp.26-46
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    • 2017
  • This article investigates perceptions and use of Open Access journals (OAJs) by master's degree students in two universities in the southwestern part of Nigeria. A descriptive survey design was used in the study and the study population was comprised of 7,423 master's degree students in the University of Ibadan and 1,867 from Obafemi Awolowo University. A multistage random sampling technique was used to select a sample size of 249 and the data collection instrument was a structured questionnaire. Data were analyzed using frequency counts, percentages, mean, standard deviation, correlation, and regression analyses. The findings revealed that OAJs were used for learning, dissertation writing, personal research, and development. OAJs were not frequently used because of download delays, unavailability of Internet facilities, and limited access to computers terminals, among other issues. OAJs were found to be of relative advantage, positively perceived, and found to be compatible with existing values and quality assurance in scholarly publications, hence their use for academic activities. The regression analyses showed that there was a significant positive relationship between positive perception, perception of relative advantage, perception of compatibility, perception complexity, and master's degree students' use of OAJs. Negative perception was found to have a significant negative correlation with the use of OAJs. This article recommends that quality assurance of OAJs should be ensured in order to boost users' positive perceptions to increase their patronage and usage of these scholarly outlets for various academic activities, which will in turn encourage research and development across the various institutions of higher learning in Nigeria.

Improving a Digital Redesign for Time-Varying Trackers (시변 추종제어기를 위한 디지털 재설계의 개선)

  • Song, Hyun-Seok;Lee, Ho-Jae;Kim, Do-Wan
    • Journal of Institute of Control, Robotics and Systems
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    • v.17 no.4
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    • pp.289-294
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    • 2011
  • Digital redesign is yet another efficient tool to convert a pre-designed analog controller into a sampled-data one to maintain the analog closed-loop performance in the sense of state matching. A rising difficulty in developing a digital redesign technique for trackers with time-varying references is the unavailability of a closed-form discrete-time model of a system, even if it is linear time-invariant. A way to resolve this is to approximate the time-varying reference as a piecewise constant one, which deteriorates the state matching performance. Another remedy may be to decrease a sampling period, which however could numerically destabilize the optimization-based digital redesign condition. In this paper, we develop a digital redesign condition for time-varying trackers by approximating the time-varying reference through a triangular hold and by introducing delta-operated discrete-time models. It is shown that the digitally redesigned sampled-data tracker recovers the performance of the pre-designed analog tracker under a fast sampling limit. Simulation results on the formation flying of satellites convincingly show the effectiveness of the development.

Development of Inconel for Marine Structural Steel by FCAW Process (해양 구조용 인코넬강의 FCAW 용접의 최적기술 개발)

  • PARK KEYUNG-DONG;JIN YOUNG-BEOM;AN DO-KEYUNG
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.11a
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    • pp.234-238
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    • 2004
  • Inconel 625 is useful in variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from $200^{\circ}C$ to aver $1090^{\circ}C$, in combination with good law- and high temperature mechanical strength. Rencently, this material is also used widely in offshore processing piping in order to extend the maintenance term and improve the quality of anti-corrosion. In general, high quality weldments for this material are readily produced by commonly used processes. Not all processes are applicable to this material group, Ni-alloys. Metallurgical characterictics or the unavailability of matching, position or suitable welding processes. Nowadays, the flux cored wire is developed and applied for the better productivity in several welding position including the vertical position. in this study, the weldability and weldment characteristics (mechanical properties) of inconel 625 are considered in FCAW(Flux Core Arc Welding) associated with the several shielding gases($80\%Ar\;+\;20\%CO_2,\;50\%Ar+50CO_2,\;100CO_2$) in viewpoint of welding productivity.

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Development of Fuzzy Controller for High Performance Solar tracking of PV System (PV 시스템의 고효율 태양 추적을 위한 퍼지제어기 개발)

  • Ko, Jae-Sub;Choi, Jung-Sik;Kim, Do-Yeon;Jung, Byung-Jun;Chung, Dong-Hwa
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.10a
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    • pp.315-318
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    • 2008
  • In this paper proposed the solar tracking system to use a fuzzy control order to increase an output of the PV(Photovoltaic) array. The solar tracking system operated two DC motors driving by signal of photo sensor. The control of dual axes is not an easy task due to nonlinear dynamics and unavailability of the parameters. Recently, artificial intelligent control of the fuzzy control, neural-network and genetic algorithm etc. have been studied. The fuzzy control made a nonlinear dynamics to well perform and had a robust and highly efficient characteristic about a parameter variable as well as a nonlinear characteristic. Hence the fuzzy control was used to perform the tracking system after comparing with error values of setting-up, nonlinear altitude and azimuth. In this paper designed a fuzzy controller for improving output of PV array and evaluated comparison with efficient of conventional PI controller. The data which were obtained by experiment were able to show a validity of the proposed controller.

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Measurement of a Diagnostic Coverage for a Digital Signal Processor Board Using an FMEDA (FMEDA를 활용한 디지털 신호처리기 보드의 진단 유효범위의 측정)

  • Keum, Jong-Yong;Suh, Yong-Suk;Lee, Jun-Koo;Park, Je-Yun
    • Journal of Applied Reliability
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    • v.8 no.2
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    • pp.101-111
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    • 2008
  • Good diagnostics improves both the safety and system unavailability of digital safety systems. The measure of a diagnostic capability is called the Coverage Factor. Because the Failure Modes, Effects and Diagnostic Analysis (FMEDA) provides information on the failure rates and failure mode distributions necessary to calculate a diagnostic coverage factor for a component, the FMEDA can be used as a useful tool to calculate it. Through performing FMEDA on a digital signal processor (DSP) board used in a digital safety system, it is shown that some components of the DSP board can be replaced or improved to satisfy the required diagnostic coverage. That is, the FMEDA can serve as a useful verification tool to design a diagnostic capability for the DSP board.

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A Study on Characteristics of Inconel 625 for Petroleum Application by FCAW Process ; Effect of Shield Gases Change Influence on a Mechanical Properties (석유시추용 인코넬 625강의 FCAW 용접에 관한 연구 ; 보호가스 변화가 기계적 성질에 미치는 영향)

  • PARK KEYUNG-DONG;JIN YOUNG-BEOM;PARK HYOUNG-DONG
    • Journal of Ocean Engineering and Technology
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    • v.18 no.6 s.61
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    • pp.96-100
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    • 2004
  • Inconel 625 is useful in a variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from $200^{\circ}C$ to over $1090^{\circ}C$, in combination with good low and high temperature mechanical strength. Rencently this material has also been widely used in offshore processing piping in order to extend the maintenance term and improve the quality of anti-corrosion. In general, high quality weldings for this material are readily produced by commonly used processes. How, not all processes are applicable to this material group of Ni-alloys. Metallurgical or the unavailability of matching, position or suitable welding processes produce a lower quality. Nowadays, the flux cored wire is developed and applied for increased productivity in several welding positions, including the vertical position. In this study, the weldability and weldment characteristics(mechanical properties) of inconel 625 are considered in FCAW(Flux Core Arc Welding) associated with the several shielding gases$(80\%Ar+20\%CO2,\;50\%Ar+50CO2,\;100CO2)$ in view of welding productivity.

Fire Simulations for the Abandonment Risk Assessment of Main Control Room Fire in Domestic Nuclear Power Plant (국내 원자력발전소의 주제어실 화재 피난 리스크 평가를 위한 화재 시뮬레이션)

  • Kang, Dae Il;Kim, Kilyoo;Jang, Seung-Cheol;Yoo, Seong Yeon
    • Journal of the Korean Society of Safety
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    • v.29 no.4
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    • pp.199-207
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    • 2014
  • In this paper, to systematically assess the abandonment risk of main control room (MCR) fire, fire simulations with Fire Dynamics Simulator were performed and abandonment probabilities were estimated for the MCR bench-board fire of domestic reference nuclear power plant. The fire simulation scenarios performed in this study included propagating and non-propagating fires of the MCR bench-board, and the availability and unavailability of heating, ventilation, and air conditioning system (HVACS). The following results were obtained. First, temperature was the major abandonment impact factor for the MCR bench-board fire if the HVACS was available and optical density was that if the HVACS was unavailable. Second, the fire scenario contributing the MCR bench-board fire abandonment risk was identified to be only the propagating fire. Third, it was confirmed that the abandonment probability of the MCR bench-board fire for domestic reference nuclear power plant could be reduced by using the fire modeling.

A Study on the Characteristics of Inconel 625 for Casing and Tubing by FCAW Process (석유시추용 인코넬 625강의 FCAW용접 특성에 관한 연구)

  • Park, Keyung-Dong;Jin, Yonug-Beom;Park, Hyoung-Dong
    • Journal of the Korean Society of Safety
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    • v.20 no.3 s.71
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    • pp.9-13
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    • 2005
  • Inconel 625 is useful in variety of industrial applications because of the resistance to attack on various corrosive media at temperature from $200^{\circ}C$ to over $1090^{\circ}C$, in combination with good low and high temperature mechanical strength. Recently, this material is also used widely in offshore processing piping in order to extend the maintenance term and improvement the quality of anti-corrosion. In general, high quality weldments for this material are readily produced by commonly used processes. Not all processes are applicable to this material group, Ni-alloys. Metallurgical characteristics or the unavailability of matching, position or suitable welding process. Nowadays, the flux cored wire is developed and applied for the better productivity in several welding position including the vertical position. In this study, the weldability and weldment characteristics(mechanical properties) of inconel 625 are considered in FCAW(Flux Cored Arc Welding) associated with the severial shielding gases($80%Ar+20%CO_2,\;50%Ar+50%CO_2,\;100%CO_2$) in viewpoint of welding productivity.

A Method for Improving Accuracy of Image Matching Algorithm for Car Navigation System

  • Kim, Jin-Deog;Moon, Hye-Young
    • Journal of information and communication convergence engineering
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    • v.9 no.4
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    • pp.447-451
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    • 2011
  • Recently, various in-vehicle networks have been developed respectively in order to accomplish their own purposes such as CAN and MOST. Especially, the MOST network is usually adapted to provide entertainment service. The car navigation system is also widely used for guiding driving paths to driver. The position for the navigation system is usually acquired by GPS technology. However, the GPS technique has two serious problems. The first is unavailability in urban canyons. The second is inherent positional error rate. The problems have been studied in many literatures. However, the second still leads to incorrect locational information in some area, especially parallel roads. This paper proposes a performance tuning method of image matching algorithm for the car navigation system. The method utilizes images obtained from in-vehicle MOST network and a real-time image matching algorithm which determines the direction of moving vehicle in parallel section of road. In order to accuracy improvement of image matching algorithm, three conditions are applied. The experimental tests show that the proposed system increases the accuracy.

Tracking System of Photovoltaic Generation Using DFC Controller (DFC 제어기를 이용한 태양광 발전의 추적시스템)

  • Jung, Byung-Jin;Choi, Jung-Sik;Ko, Jae-Sub;Kim, Do-Yeon;Jung, Dong-Hwa
    • Proceedings of the KIPE Conference
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    • 2008.10a
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    • pp.199-201
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    • 2008
  • In this paper proposed the solar tracking system to use direct fuzzy control order to increase an output of the PV (Photovoltaic) array. The solar tracking system operated two DC motors driving by signal of photo sensor. The control of dual axes is not an easy task due to nonlinear dynamics and unavailability of the parameters. Recently, artificial intelligent control of the fuzzy control, neural-network and genetic algorithm etc. have been studied. The fuzzy control made a nonlinear dynamics to well perform and had a robust and highly efficient characteristic about a parameter variable as well as a nonlinear characteristic. Hence the fuzzy control was used to perform the tracking system after comparing with error values of setting-up, nonlinear altitude and azimuth. In this paper designed a DFC(Direct Fuzzy Control)controller for improving output of PV array and evaluated comparison with efficient of conventional PI controller. The data which were obtained by experiment were able to show a validity of the proposed controller.

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