• Title/Summary/Keyword: Class flow

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Effect of air inflow on the performance of a 50kW-class cross-flow turbine (50kW급 횡류수차 내 공기 유입이 성능에 미치는 영향)

  • Kim, Jun-Ho
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.4
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    • pp.418-423
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    • 2014
  • Small hydropower has been considered as a solution to resolve the problem of exhaustion of fossil fuel and industrial pollution. In this study, we developed and tested a Cross-Flow Turbine with two guide vanes to optimize the small hydropower for the site condition with large fluctuation of head and flow rate. Furthermore, in the condition of constant inlet head, CFD analysis was carried out to analyze the effect of air suction and valve position on the performance characteristics. The results showed that the air suction can minimize the hydraulic loss caused by the Recirculation flow in the runner passage and flow impact on main shaft so that it can increase the turbine efficiency and output power.

Numerical Analysis in a 1 kWe SOFC Stack for the Flow Phenomena (1 kWe 급 고체산화물 연료전지 스택에서의 유동 해석)

  • KUNWOO YI;YOUNG JIN KIM;HAOYUAN YIN;HYEON JIN KIM;KYONG SIK YUN;JI HAENG YU
    • Journal of Hydrogen and New Energy
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    • v.34 no.2
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    • pp.196-204
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    • 2023
  • This study performed the numerical analysis of the internal flow phenomena of 1 kWe-class solid oxide fuel cell (SOFC) stacks with internal manifold type and planar cells using commercial computational fluid dynamics (CFD) software, Star-CCM+. In particular, the locations where the turbulent phenomena occur inside the SOFC stack were investigated. In addition, the laminar flow model and the standard k-ε turbulent model were used to calculate the SOFC stack, separately. And, the calculation results of both laminar and turbulent models were compared. The calculation results showed that turbulent phenomena occurred mainly in the cathode flow. Especially, the turbulent phenomena were found in the cathode inlet/outlet region, and local turbulence occurred in the end plate near the inlet pipe.

GIS-based Analysis of Debris-flow Characteristics in Gangwon-do (GIS를 이용한 강원지역 토석류 특성분석)

  • Ko, Suk Min;Lee, Seung Woo;Yune, Chan Young;Kim, Gi Hong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.31 no.1
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    • pp.57-67
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    • 2013
  • In Korea, there are debris-flow disasters induced by typhoon and localized torrential rainfall annually. There are particularly extensive debris-flow disasters in Gangwon-do because of its geomorphological characteristics; the extensive coverage of mountainous region, steep slope, and shallow soil. In this paper, we constructed a GIS database about topological characteristics of debris-flow basin in Gangwon-do by years of field survey. Also, we conducted frequency analysis based on this database with the digital forest type map and the digital soil map. We analyzed frequencies of debris-flow by simple count for topological characteristics, whereas we analyzed by considering an area ratio based on GIS for physiognomic and geologic characteristics. We used slope, aspect, width, depth and destruction shapes for analysis about topological characteristics of debris-flow basin. Also we used attributes of forest physiognomy, diameter, age, and density about physiognomic characteristics, and i n terms of geologic characteristics, we used attributes of drainage class, effective soil depth, subsoil properties, subsoil grave content, erosion class, parent material of soil, and topsoil properties. In consequence, we figured out topographic, forest physiognomic, and geologic characteristics of debris-flow basin. This result is applicable to establish a rational disaster prevention policy as a fundamental information.

The Development of Feed-Water Flow Controller of Boiler Feed-Water Pump in 500MW Class Coal-Fired Power Plant (500MW급 석탄화력발전소 보일러 급수펌프 유량 제어기 개발)

  • Lim, Geon-Pyo;Choi, In-Kyu;Park, Doo-Yong;Jeong, Tae-Won;Kim, Gun-Jung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.9
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    • pp.1663-1672
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    • 2010
  • The boiler feed-water pump controllers which can be applied to 500MW class coal fired power plants was developed. The validity of the developed controllers was shown via the applied test result in a power plant. It is expected that the developed controllers are used to retrofit the existing controllers that have surpassed their expected service life and have limited spare parts, and contributes to the stable operation of plants. Based on the collected data and analysis, new control schemes were developed and implemented during the overhaul period in the new control systems. During normal operation, feed water could be supplied to the boiler with the capability of the 1600t/h flow without any problems in automatic mode of controllers. In this study, the feed-water pump controllers were developed successfully. In addition, it is expected that the developed controllers can make the plant operation more stable and can be applied to a lot of power plants.

Hydraulic Tests of Fuel Pump for 75-ton class Liquid Rocket Engines (75톤급 로켓엔진용 연료펌프의 수력성능시험)

  • Kim, Dae-Jin;Hong, Soon-Sam;Choi, Chang-Ho;Noh, Jun-Gu;Kim, Jin-Han
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2009.11a
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    • pp.78-81
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    • 2009
  • A series of hydraulic tests of a fuel pump are performed using water at a room temperature. The pump is under development for 75-ton class liquid rocket engines of the open-loop gas generator type. According to the test results, the fuel pump satisfies its design requirement and its head and efficiency at the design flowrate are higher than the expected value by the computational analysis. Also, it is found that the pressure at the rear bearing outlet is higher than expected because the inlet of bypass pipe line is narrow. Furthermore, the flowrate of the secondary flow is estimated using the pressure difference of the elbow of the bypass pipe line.

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An Object-Oriented Process Modeling for the Development of the Integrated Logistics Support (민간부문에서의 ILS 개발에 관한 연구 - 객체지향 물류 프로세스 모델링의 응용을 중심으로)

  • 고일상;김재전
    • The Journal of Society for e-Business Studies
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    • v.3 no.2
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    • pp.179-202
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    • 1998
  • This study reviews the concept of Integrated Logistic Support(ILS), ILS standards, ILS elements, and the processes of developing ILS elements and Logistics Support Analysis(LSA). It also examines the potentials of applying ILS development process to building CALS systems in commercial sectors in order to accomplish business process innovation and achieve life-cycle cost savings in product and equipment management. In order to utilize the ILS approach for commercial industries, we need customizing the process of Logistics Support Analysis defined in MIL-STD-1388-lA. The success of ILS implementation depends on the determination of the range of ILS elements in relation with the application environment, and the appropriate development of those elements. During the development process, in order to analyze and design logistics flow processes and supporting activities, we suggest the object-oriented logistics process modeling approach with basic concepts and constructs embedded in objects. Several diagrams including Class Diagram, Class-Instance Diagram, and Integrated Instance Diagram, are provided. Simple Steps to follow are suggested for the analysis and design of inter-organizational logistics flow and support processes. The outcomes of the study are expected to contribute to stimulating the utilization of ILS concepts and development process during building commercial CALS systems.

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Aerodynamic Design and Analysis of a Centrifugal Compressor in a 40kW Class Turbogenerator Gas Turbine (40kW급 터보제너레이터용 원심압축기의 공력설계 및 유동해석)

  • Oh, J.S.;Yoon, E.S.;Cho, S.Y.;Oh, K.S.
    • 유체기계공업학회:학술대회논문집
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    • 1998.02a
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    • pp.128-135
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    • 1998
  • Procedures and results of aerodynamic design of a centrifugal compressor are presented for development of a 40kW class turbogenerator gas turbine. Specification of higher level of total pressure ratio of 4 and total efficiency of $80\%$ requires advanced methods of design and analysis. In the meanline design/analysis, a method with conventional loss modeling and a method with the two-zone model are alternately used for more reliable prediction. In the impeller blade generation, a series of Bezier curve are combined to produce meridional contours and distributions of blade camber angle and blade thickness. Intermediate profiles of blades are repeatedly produced and changed to be finally fixed through quasi-three dimensional Euler flow analysis. Three dimensional compressible turbulent flow analysis is then performed for the impeller to be confirmed in the final step of design. Satisfactory results in the aerodynamic performance are obtained, which assures that there is no need of aerodynamic re-design.

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Analysis of Operating Characteristics of 200kW Class Micro Gas Turbine (200kW 급 마이크로 가스터빈의 운전특성 분석)

  • Kim, Jeong Ho;Kang, Do Won;Kim, Tong Seop
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.11
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    • pp.1015-1022
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    • 2013
  • This study simulates the operation of a 200 kW class micro gas turbine that is currently under development. The performance and operating characteristics depending on the load control scheme (constant turbine inlet temperature versus constant turbine exit temperature) and ambient condition were investigated using detailed component performance data. The sensitivities of operating parameters, such as the compressor surge margin and flow path temperatures, according to unit fuel flow change were predicted for a wide load range. The sensitivity analysis showed that the steady state calculation provided useful information about the maximum surge margin reduction during load change.

Viscous Flow Calculation around a 30 FT-class Sailing Yacht Hull (30ft급 요트 선체 주위의 점성유동 해석)

  • Chi, Hye-Ryoun;Kim, Wu-Joan;Park, Jong-Hwan
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.3 s.153
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    • pp.248-257
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    • 2007
  • Turbulent flows around a sailing yacht hull were calculated using CFD technique. Grid system was generated by using Gridgen package and Fluent package was used to calculate flows around a 30ft-class yacht hull designed by MOERI. The drafts at starboard and port sides of a yacht. when the hull was heeled, were determined by adjusting the same displacement in the generated grid system. Pressure distribution on the sailing yacht hull was obtained and the changes of drag and side force by heel and leeway variation were shown. The flow calculations have been carried out both with and without free surface, and keel and rudder were included for both cases. It was found that the calculated results with free surface gives better agreement with experiments than those without free surface, although there are still a room for the improvement in correct prediction of forces.

Effects of Learning Activities on Application of Learning Portfolio in Nursing Management Course (간호관리학 교과에서 학습포트폴리오를 활용한 학습활동의 효과)

  • Choi, So Eun;Kim, Eun A
    • Journal of Korean Academy of Nursing
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    • v.46 no.1
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    • pp.90-99
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    • 2016
  • Purpose: This study was conducted to examine effects of a learning portfolio by identifying the learning of nursing students taking a learning portfolio-utilized nursing management class. Methods: A non-equivalent control group pretest-posttest design was used. Participants were 83 senior students taking the nursing management course in one of the Departments of Nursing at 2 Universities. Experimental group (n=42) received a learning portfolio-utilized nursing management class 15 times over 15 weeks (3 hours weekly). Self-directed learning abilities, approaches to learning and learning flow of the participants were examined with self-report structured questionnaires. Data were collected between September 2 and December 16, 2014, and were analyzed using chi-square test, Fisher's exact test, independent t-test and ANCOVA with SPSS/PC version 21.0. Results: After the intervention the experimental group showed significant increases in self-directed learning abilities, deep approaches to learning and learning flow compared to the control group. However, no significant difference was found between groups for surface approaches to learning. Conclusion: Learning activities using the learning portfolios could be effective in cultivating the learning competency for growth of knowledge, technology and professionalism by increasing personal concentration and organization ability of the nursing students so that they can react to the rapidly changing environment.