• Title, Summary, Keyword: Method

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The Effect of Science Creative Problem Solving Ability and Science Process Skills Using Free Inquiry Method (자유탐구 기법을 활용한 수업이 과학 창의적 문제해결력 및 과학적 탐구능력에 미치는 효과)

  • Lee, Yong-Seob;Kim, Soon-Shik;Lee, Sang-Gyun
    • Journal of the Korean Society of Earth Science Education
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    • v.4 no.2
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    • pp.116-125
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    • 2011
  • The purpose of this study is to make a Result analysis on the Free Inquiry Method of Elementary school student. Also, this study investigates how free inquiry activities effect the science creative problem solving ability and science process skills of Elementary school student. For this study 150, third year, elementary School students from Busan City were selected. The Inquiry examined the effectiveness of each of the following free inquiry methods: the Program Based Learning method, the Project method, the Independent Investigation Method, the Small Group Inquiry Method, and the Science Notebooks Method. The students were divided into groups in which they incorporated the respective methods into their practice. Test showed the following results: First, the Science Notebooks Method activities proved to be much more effective than the Program Based Learning method, the Project method, the Independent Investigation Method, the Small Group Inquiry Method, and the Science Notebooks Method in terms of developing on science creative problem solving ability. Second, the Project method activities proved to be much more effective than the Program Based Learning method, the Independent Investigation Method, the Small Group Inquiry Method, the Science Notebooks Method in terms of developing on science process skills.

A Fair Investigation on Safety Factor of Slope by Model Tests (모형실험에 의한 사면 안전율의 적정성 연구)

  • Kim, Yong-Sik;Park, Choon-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1313-1323
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    • 2008
  • The purpose of this study is to understand behaviors of slopes and determine soil parameters of slopes through the triaxial compression test and the direct shear test. Following results were obtained by comparing and analyzing model tests and analysis programs of slope stability. The safety factors of the Bishop's simple method, the Morgenstern Price method, the Spencer method and the GLE method were similar to each other but safety factors of the Fellenius method and the Janbu method were different from the formers. It was found that the Bishop's simple method, the Morgenstern Price method, the Spencer method and the GLE method could be used for design but attention should be paid to the Fellenius method and the Janbu method since they underestimated safety factor.

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Field Validation of a Sampling and Analytical Method Developed for Preventing Airborne Hexavalent Chromium Collected on PVC Filter from Reduction (PVC 여과지에서의 환원 방지를 위해 개발된 공기중 6가 크롬 측정방법의 현장 평가)

  • 신용철;백남원
    • Journal of Environmental Health Sciences
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    • v.28 no.2
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    • pp.109-116
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    • 2002
  • The purpose of this study was to evaluate a new sampling and analytical method for the determination of airborne hexavalent chromium, Cr(Ⅵ), in a field plating operation. The procedures of this new method (Shin & Paik's Method) are as the following: Airborne hexavalent chromium is collected on polyvinyl chloride (PVC) filter according to the National Institute iota Occupational Safety and Health (NIOSH) Method 7600, and the filler sample is placed in a screw-capped vial and soaked with 2% NaOH/3% Na₂CO₃ solution immediately after sampling. The Cr(Ⅵ) sample is analyzed by ion chromatography/visible spectrophotometry (IC/VS) according to the U.S. Environmental Protection Agency (EPA) Method 218.6. The airborne Cr(Ⅵ) concentrations measured by this method were compared with those determined by three reference methods: One (NIOSH/EPA Method) consisted of sampling airborne Cr(Ⅵ) on PVC filters and storing the sample filters in strew-capped vials according to the NIOSH method, and analyzing Cr(Ⅵ) in samples using IC/VS according to the EPA method. The second method (Impinger Method/NaHCO₃) consisted of absorbing airborne Cr(Ⅵ) into 0.02 M NaHCO₃ solution in midget impinger, and analyzing the Cr(Ⅵ) in samples using IC/VS. The third method was the OSHA Method ID-215. Using these four different methods, lour replicates of air samples were collected at an electroplating process and analyzed simultaneously. Two-way ANOVA and paired t-test were used to test difference among values determined by the methods. There was no significant difference and a strong correlation (r²:0.99) between Cr(Ⅵ) concentrations measured by the Shin & Paik's Method and an impinger method (p>0.05). However, Cr(Ⅵ) concentrations determined by Shin & Paik's Method were significant1y different from those by the NIOSH/EPA Method (p<0.05) or the OSHA method (p<0.05). The Cr(Ⅵ) concentrations of Shin & Paik's Method were significantly higher than those of the NIOSH/EPA Method or the OSHA method. This result indicated that the Shin & Paik's Method may prevent Cr(Ⅵ) losses caused by reduction and give more reliable results of airborne Cr(Ⅵ) concentrations in work environments.

A Study on Numerical Optimization Method for Aerodynamic Design (공력설계를 위한 수치최적설계기법의 연구)

  • Jin, Xue-Song;Choi, Jae-Ho;Kim, Kwang-Yong
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.1
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    • pp.29-34
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    • 1999
  • To develop the efficient numerical optimization method for the design of an airfoil, an evaluation of various methods coupled with two-dimensional Naviev-Stokes analysis is presented. Simplex method and Hook-Jeeves method we used as direct search methods, and steepest descent method, conjugate gradient method and DFP method are used as indirect search methods and are tested to determine the search direction. To determine the moving distance, the golden section method and cubic interpolation method are tested. The finite volume method is used to discretize two-dimensional Navier-Stokes equations, and SIMPLEC algorithm is used for a velocity-pressure correction method. For the optimal design of two-dimensional airfoil, maximum thickness, maximum ordinate of camber line and chordwise position of maximum ordinate are chosen as design variables, and the ratio of drag coefficient to lift coefficient is selected as an objective function. From the results, it is found that conjugate gradient method and cubic interpolation method are the most efficient for the determination of search direction and the moving distance, respectively.

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A STUDY ON THE CHOICE OF THERMAL MODELS IN THE COMPUTATION OF NATURAL CONVECTION WITH THE LATTICE BOLTZMANN METHOD (Lattice Boltzmann 방법을 사용한 자연대류 해석에서 열모델의 선택에 관한 연구)

  • Choi, Seok-Ki;Kim, Seong-O
    • Journal of computational fluids engineering
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    • v.16 no.4
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    • pp.7-13
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    • 2011
  • A comparative analysis of thermal models in the lattice Boltzmann method(LBM) for the simulation of laminar natural convection in a square cavity is presented. A HYBRID method, in which the thermal equation is solved by the Navier-Stokes equation method while the mass and momentum conservation are resolved by the lattice Boltzmann method, is introduced and its merits are explained. All the governing equations are discretized on a cell-centered, non-uniform grid using the finite-volume method. The convection terms are treated by a second-order central-difference scheme with a deferred correction method to ensure stability of the solutions. The HYBRID method and the double-population method are applied to the simulation of natural convection in a square cavity and the predicted results are compared with the benchmark solutions given in the literatures. The predicted results are also compared with those by the conventional Navier-Stokes equation method. In general, the present HYBRID method is as accurate as the Navier-Stokes equation method and the double-population method. The HYBRID method shows better convergence and stability than the double-population method. These observations indicate that this HYBRID method is an efficient and economic method for the simulation of incompressible fluid flow and heat transfer problem with the LBM.

Application of the Photoelastic Experimental Hybrid Method with New Numerical Method to the High Stress Distribution (고응력 분포에 새로운 광탄성실험 하이브릿법 적용)

  • Hawong, Jai-Sug;Tche, Konstantin;Lee, Dong-Hun;Lee, Dong-Ha
    • Proceedings of the KSME Conference
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    • pp.73-78
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    • 2004
  • In this research, the photoelastic experimental hybrid method with Hook-Jeeves numerical method has been developed: This method is more precise and stable than the photoelastic experimental hybrid method with Newton-Rapson numerical method with Gaussian elimination method. Using the photoelastic experimental hybrid method with Hook-Jeeves numerical method, we can separate stress components from isochromatics only and stress intensity factors and stress concentration factors can be determined. The photoelastic experimental hybrid method with Hook-Jeeves had better be used in the full field experiment than the photoelastic experimental hybrid method with Newton-Rapson with Gaussian elimination method.

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Comprision Study of Measure Method on Leveling (수준측량 측정방법의 비교연구)

  • Hwang, Jin-Sung
    • Journal of the Korean Society of Industry Convergence
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    • v.16 no.1
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    • pp.9-13
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    • 2013
  • This paper measured some condition about differential height of two points for the comparison of measure by direct method and Geodimeter and trigonometric Leveling method. The research was compared relationship between the volue to get from three measure method and five measured man. The significance of between three measure method and five measured man has been investigated by analysis of two-way ANOVA. The result indicate that between five measured man show insignficance, and between the direct method and Geodeter method show signficance and between the direct method and trigonometric Leveling method show signficance but between the Geodeter method and trigonometric Leveling method, two method show insignficant. Therefore, when using Geodemeter leveling method and trigonometric Leveling method, you must keep particular attention when former two Leveling method about instrumental error, natural error, and personal error, two Leveling method using low precision leveling.

A study of Improvement on Washing and Rinsing Efficiency - Effect of the dissolution of detergent on washing and rinsing efficiency - (세탁 및 헹굼성능 향상 방안 연구 - 세제의 용해가 세탁 및 헹굼 성능에 미치는 영향 -)

  • 이옥기;표상연
    • Journal of the Korean Society of Clothing and Textiles
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    • v.18 no.1
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    • pp.23-30
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    • 1994
  • The objective of this study was to analyze the effect of the dissolution of detergent on washing and rinsing efficiency, and the possibility of saving detergent in washing. Washing and rinsing efficiency were reviewed in three different ways : A method was to input dissolved detergent by the use of rapid detergent dissolution instrument, B method was to input dissolved detergent beforehand, and C method was to input undissolved detergent. The results were as follows 1. A method > B method > C method was shown in detergency with washing time and three method's gaps were reduced because detergent dissolution effect was reduced by mechanical action in proportion of washing time. Especially, according to detergency of A method of 0.07% and C method of 0.1% was appeared approximately, saving detergent was expected by rapid dissolution of detergent. 2. A method > B method > C method was shown in detergency with washing temperature. As the washing temperature rose, the detergent reached chemically more activated state and become easily soluble. It resulted for the detergent to penetrate and adhere to laundry easily. 3. A method > B method > C method was shown in detergency with detergent concentration and C method was more sensitive than A, B method against change of detergent cocentration. Rapid detergent dissolution made it possible not only to enhance the washing efficiency but also to save the detergent because detergency of A method in low concentration is higher than that of C method. 4. A method $\geq$ B method > C method was shown in rinsing ratio with detergent input method. It indicated input dissolved detergent was advantageous in rinsing. 5. The result of anion surfactant concentration test of each process with detergent input method was shown like that A method In B method > C method in washing and reverse result was shown in rinsing. The anion surfactant concentration of C method was low during washing but high during rinsing. This was identical with previous results which shown the washing and rinsing efficiency improved with dissolved detergent usasge. 6. C method > B method > A method was shown in the degree of remaining detergent after rinsing. There was no remaining detergent after second rinsing in A and B method, but in C method four rinsings were required for the same result. Consequently, in A and B methods, less water and electricity were used, and less abrasion of cloth.

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Comparison of Improved Explicit Method and Predictor Correct α-Method (개선된 명시적 방법과 예측수정 α-Method방법의 비교)

  • Kwon, Min-Ho;Jung, Woo-Young
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.3 no.4
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    • pp.1-9
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    • 2012
  • Dynamic application lower mode response is of interest, however the higher modes of spatially discretized equations generally do not represent the real behavior. Some implicit algorithms, therefore, are introduced to filter out the high-frequency modes. The objective of this study is to introduce the P-method and PC ${\alpha}$-method to compare that with dissipation method and Newmark method through the stability analysis and numerical example. PC ${\alpha}$-method gives more accuracy than other methods because it based on the ${\alpha}$-method inherits the superior properties of the implicit ${\alpha}$-method. In finite element analysis, the PC ${\alpha}$-method is more useful than other methods because it is the explicit scheme and it achieve the second order accuracy and numerical damping simultaneously.

A Study on the Generation of Initial Shape for the Initiation of Optimal Blank Design Sequence (최적블랭크 설계를 위한 초기형상 생성에 관한 연구)

  • 심현보;장상득;박종규
    • Transactions of Materials Processing
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    • v.13 no.1
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    • pp.90-101
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    • 2004
  • An inverse mosaic method has been proposed to generate an initial blank shape from the final product shape. Differently from the geometric mapping method, the method can handle triangular patches. However, the generated blank shape is strongly dependent on the order of determination of nodes. In order to compensate the dependency error smoothing technique has been also developed. Although the accuracy has been improved greatly compared with the geometrical mapping method, the method has limitation, due to the no incorporation of plasticity theory. Even though the accuracy of the radius vector method is already proved. the method requires initial guess to start the method. In order to compromise the limitation of the present method and the radius vector method, the method has been connected to the radius vector method. The efficiency of the present optimal blank design method has been verified with some chosen examples.