• Title/Summary/Keyword: calculation program

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Calculation of Transverse Vibration of Ship`s Propulsion Shaftings by the Finite Element Method (有限要素法에 의한 推進軸系의 광振動計算에 관한 硏究)

  • Jeon, Hio-Jung;Kim, Hi-Cheol
    • Journal of Advanced Marine Engineering and Technology
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    • v.3 no.1
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    • pp.2-18
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    • 1979
  • Due to increasing ship dimensions and installed propulsive power, resonance frequencies of the propeller shaft system tend to decrease and they can appear in some cases within the operating range of the shaft revolution. For calculation of transverse shaft vibrations, various methods have been proposed but as they are mainly for approximate calculation, no contented results are obtained. For fairly accurate estimation of resonance frequencies in the design stage, one can use transfer matrix method of the finite element method and former is rather prefered in ordinary cases. In this study, the finite element method which is utilized for calculation of the propulsion shaft alignment, is introduced to derive the vibration equation of the ship's propulsion shaftings. The digital computer program is developed to solve the above equation, and the details of preparing the input data are described. The method presented in the underlying report was applied to the shafting of ship which has a lignumvitae bearing to verify its reliability and the results of calculation and those of the measurements on rotating shaft show a good agreement. Calculating methods of exciting of forces and damping forces are also discussed for future work.

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Using Evolution Program to Develop Effective Search Method for Alternative Routes (진화 프로그램을 이용한 효율적인 대체경로 탐색방법 연구)

  • CHOI, Gyoo Seok;SEO, Ki Sung;PARK, Jong Jin
    • Journal of Korean Society of Transportation
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    • v.20 no.2
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    • pp.71-79
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    • 2002
  • This paper presents an effective alternative K-paths calculation method based on a Evolution Program (EP). We developed efficient genetic operators for path calculation. A major problem of the existing approach(similarities among the paths) can be resolved using EP's. The performance of the suggested method is evaluated and compared with the k-th shortest path for the virtual road network model by computer simulation. The results of computational experiments of the suggested method are found to be satisfactory in terms of the dispersion of alternatives.

Flaws in Excel when performing Base Conversion of Decimals (Excel을 활용한 소수의 진법변환 계산에서의 오류)

  • Kim, Tae Soo
    • KIISE Transactions on Computing Practices
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    • v.22 no.11
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    • pp.559-566
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    • 2016
  • Excel is a commercially available computer program that is used worldwide. Excel is widely utilized; it is helpful in household ledgers, corporate tax calculations, management of academic grades or reports, etc. However from the beginning, inaccuracies and errors in calculations have constantly been identified, so the program is updated regularly. Decimal-to-binary conversion is a simple and repetitive task. So, use of a computer program to do this calculation is suitable. Errors in decimal-to-binary conversion are surprising and are not easily understood. Therefore, it is important to identify the flaws in Excel, which unfortunately still exist today. It is necessary to determine the cause of this type of error, and I hope for a fix to be implemented quickly.

A Study on the Improvement of Subsidy Program for CHP Plant Connected with Capital Region District Heating System (수도권 지역난방연계 열병합발전소의 기반기금 지원과 개선방안)

  • 김창수;이창호
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.53 no.2
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    • pp.97-103
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    • 2004
  • CHP system supplies electricity and heating together with high efficiency. Current utility's CHP system uses electric power by itself and sells thermal energy to KDHC(Korea District Heating Corporation). CHP's operation cost except sales revenue of heating was covered by the sale revenue of electricity. Thus Electric generation cost in district Heating CHP system has close relationship with the level of heating price. However, after the restructuring of electricity industry, the operation cost could not be covered by sales revenue of heating and electricity. This loss was compensated by energy subsidy program in the electric power industry infrastructure fund. This paper suggests reasonable evaluation and improvement methods of the loss calculation of CHP system utilizing the infrastructure fund efficiency In terms of the direction of support by the fund, it provides the methods to prevent inefficient operation through setting up the upper limit of subsidy and to improve the loss calculation. Moreover, it suggest fixed rate support by heating supply level and reducing subsidy gradually for an efficient operation of CHP system.

A study on the calculation of synthesized torsional vibration for the marine diesel engine shafting by the mechanical impedance method (기계적 임피던스법에 의한 박용디젤기관 추진축계의 합성비틀림진동 계산에 관한 연구)

  • 박용남;전효중
    • Journal of Advanced Marine Engineering and Technology
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    • v.10 no.2
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    • pp.146-155
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    • 1986
  • Until recently, the calculation of torsional vibration for the marine diesel engine shafting has been performed only for vibratory stresses of resonant points and vibratory stresses for other engine speeds are determined by the estimation. With the advent of energy-saving engines which have a long stroke and a small number of cylinders, the first major critical torsional vibration of the propulsion shaft appears ordinarily near the MCR speed of engine and the flank of its vibratory stress exceeds now and then the limit stress defined by the rules of Classification Society. In order to know the above condition in the design stage of propulsion shafting, it is necessary to calculate the forced torsional vibration with the damping of propulsion shafting for all orders and to synthesize its calculated results according to their phase angles. In this study, the forced torsional vibrations with the damping of propulsion shafting are calculated for several orders by mechanical impedance method, and their results are synthesized. A computer program for above calculations are developed and some test-runs of the developed program are performed for propulsion shaftings of actual ships. The results of calculations are compared with measured values and also with those of the modal analysis method. They show fairly good agreements and the developed program is checked up on its reliability.

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The LAE Burn Strategy Planning for Geostationary Satellite (정지궤도 위성의 LAE Burn Strategy Planning)

  • Kim, Bang-Yeop;Lee, Ho-Hyoung
    • Aerospace Engineering and Technology
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    • v.6 no.2
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    • pp.96-103
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    • 2007
  • A program for LAE (liquid Apogee Engine) firing strategy calculation was developed. This program can be used as the first stage of transfer orbit analysis, which process receives input parameters as like initial orbit elements, ground TT&C stations positions, satellite performances and makes firing user-selectable strategies. The developed program is dedicated to GEO satellites which using LAE generally and it can calculate six back-up strategies and deals situation its maximum firing number is six. The MS-EXCEL software was used for the input and output process. And the numerical calculation part was embodied with MATLAB functions.

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Development of Educational Web-Based Power Flow Program (교육용 웹 기반 전력조류계산 프로그램 개발)

  • Yang, Kwang-Min;Lee, Ki-Song;Lee, Jeong-Kyu;Park, Jong-Bae;Shin, Joong-Rhin
    • Proceedings of the KIEE Conference
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    • 2003.11a
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    • pp.432-434
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    • 2003
  • This paper developed the web based power flow program for education. Since a lot of users can connect and implement the web based program, the only one computer can get much evaluation burden not to compute. Using the XML technology, which supports the distributed computing technology, we have developed the web-based power flow software and system that are distributed the above calculation burden to three computers: web server, database server, application server. Also, this software was developed to get the difference of number of iteration and evaluation speed as veil as the results of state variables for each node according to the each calculation method for power flow using the chart. Therefore, users can get the physical concept of power flow in addition to the difference among the evaluation methods for power flow. We have performed the case studies with IEEE 14 bus system using the developed software.

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A Study on a Dynamics Simulation Program Development for Floating Wind Turbines (부유식 풍력발전 시스템 동역학 해석 프로그램 개발 연구)

  • Rim, Chae-Whan;Song, Jin-Seop;Chung, Tae-Young;Moon, Seok-Jun;Go, Jin-Yong;Lee, Sung-Kyun;Bae, Dae-Sung;Bae, Dong-Hee
    • Journal of Wind Energy
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    • v.2 no.2
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    • pp.30-37
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    • 2011
  • A floating wind turbine dynamic simulation program, WindHydro, is newly developed taking into account wind inflow and incident wave. WindHydro consists of 5 modules, HDFloat for hydrodynamics, HDProp for hydrodynamic property calculation, HDMoor for mooring dynamics, AeroDyn for aerodynamics, DAFUL for multi-body dynamics with nonlinear elasticity, and interface program that connects each calculation module. A turbulent wind and regular wave load case is simulated for the 5-MW OC3-Hywind with a spar bouy platform and catenary mooring lines. The results are compared with the results of the FAST(developed by NREL). As a result, the overall system responses from WindHydro and FAST agree well although some differences in the generator responses are observed.