• Journal of the Korean earth science society
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• v.24 no.6
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• pp.495-507
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• 2003

The purpose of this study was three-folded to suggest the Simplifying Conditions Method (SCM) as a means of task analysis and sequencing of instructional content, to develop teaching-learning materials by analyzing part of the geological time scale of the earth science and finally to analyze the effectiveness of this method. SCM began by simplifying a complex task into the basic components by eliminating various complexities, which produced a simple representative of the entire task. The next step was to relax conditions on the basic version one by one, thereby gradually introducing progressively more complex tasks to the students. This sequential strategy enabled students to understand the task holistically and to acquire authentic skills from very onset of the course. Moreover, Early mastery of skills enhances the effectiveness and efficiency of instruction. The result of this study revealed that instruction through SCM was more effective in developing students' self-directed learning characteristics and academic achievement than instruction through sequential task analysis methodology.

• Journal of the Korean earth science society
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• v.25 no.3
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• pp.176-184
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• 2004

The concept of 'the lunar and planetary phases' is very difficult to understand and students may have various misconceptions on this concept. A module drawing the lunar and planetary phases was developed with the application of the simplifying conditions method. The effects of instruction using the module drawing the lunar and planetary phases on the conceptual change and the achievement was investigated in the consideration of learners' characteristics (spatial perception ability, science inquiry ability, required pre-requested learning ability). Findings were as follows: 1) This module was effective for learners' conceptual change and achievement, 2) This module had a positive influence for development the learners' characteristics and conceptual change with the middle level of science inquiry ability, the middle and low level of required pre-requisite learning ability, and middle level of the spatial perception ability.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.835-840
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• 2023

Compared to 3D FEM, 2D FEM can be analyzed by simplifying the model and conditions. However, with respect to coil conditions, in many cases, direction of coils(upward, downward, entrance, exit, etc.) are sequentially configured and set up the FEM analysis conditions. This paper shows simplification of coil conditions and reduction of analysis time by applying the equivalent winding method composed of one FEM coil even if it has multiple slots, and shows consistency of results by applying it to a winding type magnetic gear.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.274-280
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• 2004

This paper presents the analysis fur the radial vibration characteristics of cylindrical piezoelectric transducers. Taking into account the piezoelectric anisotropy, the differential equations of piezoelectric radial motion have been derived in terms of radial displacement and electric potential. Applying mechanical and electric boundary conditions has yielded a characteristic equation for radial vibration. Numerical analysis also has been carried out by using the finite element method. Theoretical calculations of the fundamental natural frequency have been compared with the experimental observations for transducers of several sizes. Comparison with the previous report of theoretical analysis simplifying the piezoelectric anisotropy into isotropy concludes that isotropic analysis is a reasonable process to predict the vibration characteristics of piezoelectric transducers.

• YAKHAK HOEJI
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• v.58 no.3
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• pp.190-199
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• 2014

The Korean Pharmaceutical Codex (KPC) analytical method of ambroxol hydrochloride and clenbuterol hydrochloride formulation is complicated and needed to carry out multiple processes during the test. To improve the low efficiency of analytical procedure that makes pharmaceutical laboratory consume much time and high cost to conduct the test of this formulation, this study was performed for simplifying the pretreatment process and optimizing conditions of the HPLC assay. The analytical procedure using HPLC was developed to establish analytical specification for ambroxol hydrochloride and clenbuterol hydrochloride formulations. The newly developed analytical method has good linearity ($R^2$ >0.999), specificity, precision (RSD<1.0%) and the recovery ranges of 98.50~101.84% for ambroxol, 98.29~101.35% for clenbuterol syrup and 98.66~101.71% for clenbuterol tablets. The LOQs were 0.204 ${\mu}g/ml$ for ambroxol, 0.021 ${\mu}g/ml$ for clenbuterol syrup and 0.073 ${\mu}g/ml$ for clenbuterol tablets. The new method was performed with commercially available samples to confirm analytical conditions and validated to be suitable for saving time and cost to control the quality of routine manufactured products. This analytical method will be used for revising the monograph of ambroxol hydrochloride and clenbuterol hydrochloride formulation in next supplement of KPC.

• Structural Engineering and Mechanics
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• v.65 no.4
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• pp.453-464
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• 2018

In this paper, an efficient higher-order shear deformation theory is presented to analyze thermomechanical bending of temperature-dependent functionally graded (FG) plates resting on an elastic foundation. Further simplifying supposition are made to the conventional HSDT so that the number of unknowns is reduced, significantly facilitating engineering analysis. These theory account for hyperbolic distributions of the transverse shear strains and satisfy the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. Power law material properties and linear steady-state thermal loads are assumed to be graded along the thickness. Nonlinear thermal conditions are imposed at the upper and lower surface for simply supported FG plates. Equations of motion are derived from the principle of virtual displacements. Analytical solutions for the thermomechanical bending analysis are obtained based on Fourier series that satisfy the boundary conditions (Navier's method). Non-dimensional results are compared for temperature-dependent FG plates and validated with those of other shear deformation theories. Numerical investigation is conducted to show the effect of material composition, plate geometry, and temperature field on the thermomechanical bending characteristics. It can be concluded that the present theory is not only accurate but also simple in predicting the thermomechanical bending responses of temperature-dependent FG plates.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.78-86
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• 1998

This paper presents a numerical method of the minimum-time trajectory planning for a robot manipulator amid obstacles. Each joint displacement is represented by the linear combination of the finite-term quintic B-splines which are the known functions of the path parameter. The time is represented by the linear function of the same path parameter. Since the geometric path is not fixed and the time is linear to the path parameter, the coefficients of the splines and the time-scale factor span a finite-dimensional vector space, a point in which uniquely represents the manipulator motion. The displacement, the velocity and the acceleration conditions at the starting and the goal positions are transformed into the linear equality constraints on the coefficients of the splines, which reduce the dimension of the vector space. The optimization is performed in the reduced vector space using nonlinear programming. The total moving time is the main performance index which should be minimized. The constraints on the actuator forces and that of the obstacle-avoidance, together with sufficiently large weighting coefficients, are included in the augmented performance index. In the numerical implementation, the minimum-time motion is obtained for a planar 3-1ink manipulator amid several rectangular obstacles without simplifying any dynamic or geometric models.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.11
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• pp.1228-1235
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• 2012

A refrigerator has many components which are made from diverse materials such as metal, polymer, plastic, and rubber. So, it generally requires much time and efforts to build up an analysis model in finite element analysis. In this work, to reduce the computational time and efforts a simplified modeling method was proposed for the analysis of a refrigerator. Occasionally, a stick-slip noise occurs in a refrigerator due to relative slip between shelf and inner-case. When we solve the problem by a FE analysis, we should model the structures with detail for considering the contact conditions; by this reason, too many efforts are consumed in the conventional analysis method. Through this work, we shows the concept of simplifying approach and a good agreement with the results of a real model analysis. And also, the evaluation of the proposed method and the application of contact analysis using the simplified model are discussed.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.19-30
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• 2000

The major design parameters of the anchored sheet-pile wall include the determination of required penetration depth, the force acting on the anchor, and the maximum bending moment in the piling. Blum solved the fixed earth supported wall using the equivalent beam method, assuming that the wall can be separated into upper and lower parts of the point of contraflexure. Design charts help designer by simplifying the design procedure. But they have some difficulties under some Geotechnical and geometrical conditions. For example, the conventional design charts can compute design parameters only when the ground water table exists above the dredge line. In this paper, the design charts which can be used for the ground water table existing under the dredge line are presented. And simplified formulae are developed by regression analysis. It is found that simplified formulae are not only very useful for the practice of design but also they can evaluate the result of numerical methods or design charts.

• Composites Research
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• v.34 no.4
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• pp.233-240
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• 2021

VaRI(Vacuum assisted Resin Infusion) process, which is cost effective and suitable for manufacturing large-sized composites, is an OoA(Out-of Autoclave) process. For rapid resin infusion in the VaRI process, a DM(distribution media) is placed on top of the fabric. The resin is rapidly supplied in plane direction of the fiber along the DM, and then the supplied resin is impregnated in the out-of-plane direction of fiber. It is difficult to predict the flow of resin because the flow of in-plane direction and the out-of-plane direction occur together, and a 3D numerical analysis program is used to simulate the resin infusion process. However, in order to analyze in 3D, many elements are required in the out-of-plane direction of fabric. And the product size is larger, the longer the analysis time needs. Therefore, in this study, a method was suggested to reduce the time required for flow analysis by simplifying the 3D flow analysis to 2D flow analysis. The usefulness was verified by comparing the 3D flow analysis with the simplified 2D flow analysis at the same conditions. The filling time error was about 7% and the reduction of flow analysis time was about 95%. In addition, by utilizing the constant difference in the flow front between the top, middle, and bottom of the fabric of the 3D analysis, the flow front of the top, middle, and bottom of the fabric can be also predicted in the 2D flow analysis.