• School Mathematics
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• v.4 no.1
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• pp.49-62
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• 2002

developed by solving practical problems and gradually formalized and abstracted. But school mathematics seemed to stress the formalized and abstracted mathematics. The same is the case with calculus. In particular, it appeared extremely in teaching of calculus. It caused hindrance of learning and indeed, many students had difficulties in teaming of calculus. Therefore this study investigates the various approaches of calculus teaching and the history of calculus which include approaches by Archimedes, Galileo, Newton, Leibniz and Weierstrass etc. This may offer the implication for calculus teaching and we can find the alternative on the method of calculus teaching in historico-genetic principle. Finally we suggest the direction of calculus teaching from this perspective in tile concrete.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.9-11
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• 1995

In this paper, tile squirrel case induction motors required multi-objective function are designed. As the objective function of the optimization program, we select the linear combination of loss and mass of motors by using weighting factors. Optimization process is performed by using the evolution strategy (ES). ES is the algorithm that can find the global minimum. To verify validity of the proposed method, a sample design is tried.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1686-1699
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• 1993

In this paper, the thermal buckling of thick composite angle-ply laminates subject to uniform temperature distribution is studied. For the plates of 4-edges simply supported condition and those of 4-edges clamped condition, the critical buckling temperatue is derived, using tile finite element method based on the shear deformation theory. The effects of lamination angle, layer number, laminate thickness, plate aspect ratio and boundary constraints upon the critical buckling temperature are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1317-1323
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• 2003

In this paper, In-air and in-water vibration characteristics of Rotary Specimen Rack(RSR) are estimated through 3D finite element analysis by using ANSYS software. Added mass is calculated by using Blevins' equation. To confirm the accuracy of the results presented in this study, obtained results are compared to those of using a theoretical equation. It is confirmed that in-water natural frequencies of the RSR are lower than in-air ones due to tile added mass effect of the fluid. Also, good agreement is founded between natural frequency ratios obtained by a theoretical equation and those of using ANSYS.

• Journal of Power Electronics
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• v.2 no.3
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• pp.212-219
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• 2002

A novel mode of parallel operation of a modular 3-phase AC-DC flyback converter for power factor correction along with tight regulation was recently analyzed and presented. The advantage of the proposed converter does not require expensive high voltage and high current devices that are normally needed in popular boost type 3-phase converter. In this paper tile detailed small signal analysis of the modular 3-phase AC-DC flyback converter is provided for control purpose and also experimental results are included to confirm the validity of the analysis.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.542-545
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• 2002

This paper deals with the optimization inverter design and minimization Conduced EMI noise by customizing IPM(Intelligent Power Module). Generally, In case of IPM, we realized that the trade-off relation between switching loss and spike voltage. Higher gate resistor causes tile lower spike voltage and the higher turn-off switching loss. But we know that the life cycle of inverter and the susceptibility of noise, so we optimized the gate resistor. Proposed method is that optimized the gate resistor suitable for the inverter and motor. The simulation and experimental results show that the spike voltage and Conduced EMI noise can be reduced without the additional circuit.

• Journal of the Korean Professional Engineers Association
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• v.39 no.1
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• pp.54-57
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• 2006

The snow brings affluence if it is dealt with appropriately. but causes huge damages if it is dealt with improperly when it snows heavily. Following with the development of road transportation, tile snow causes damages by becoming a serious obstacle for traffic, increasing traffic accidents, causing damages to the road, and requiring a lot of snow removal expense. As farming in the winter becomes flourishing, damages to agricultural facilities and farm produces caused by the snow become bigger and bigger. Now in our country, heavy snow or heavy rain is likely to fall at anywhere and at any time without restricted to a particular area. Safety first is one way of practicing human respect. Disasters will disappear from our neighborhood if we adopt prevention measures and follow them thoroughly. And also this is the shortcut to achieve a welfare society.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.599-603
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• 2005

Chemical constituents of fruit peels of Fortunella japonica Swingle were investigated, and ten compounds were purified and isolated through various chromatographic procedures. Through NMR analysis, isolated compounds were identified as ${\alpha}$-tocopherol (1), lupenone (2), ${\beta}$-amyrin (3), ${\alpha}$-amyrin (4), ${\beta}$-sitosterol (5), ${\beta}$-sitosteryl 3-O-glucopyranoside (6), kaempferide 3-O-rhanmopyranoside (7), 3',5'-di-C-${\beta}$-glucopyranosylphloretin (8), acacetin 7-O-neohesperidoside (9), and acacetin 8-C-neohesperidoside (10). Compounds 1-7 were identified for the first time by our group from fruit peels of F. japonica.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.66-72
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• 2006

Marine diesel engine production and refinements sought a continuous increase on mean effective pressure and thermal efficiency. These results in increased maximum combustion pressure within the cylinder and vibratory torque in crankshaft. As such, crankshaft should be designed and compacted within its fatigue strength. In this paper, the 8H25/33P($3,155ps{\times}900rpm$) engine for ship propulsion was selected as a case study, and tile strength analysis of its crankshaft is carried out by. simplified method recommended by IACS M53 and a detailed method with the crankshaft assumed as a continuous beam and bearing supported in its flexibility. The results of these two methods are compared with each other.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2009.04a
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• pp.87-89
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• 2009

A digital map is provided with 2 dimensions of tile based, a user is hard for decision-marking directly. In this study, we analyzed the present situation and characteristics of a digital map about a developed nation such as United States, England, Canada. As a result, American National Map and British Master Map are keeping continuity and up-to-date, included UFID, ISO, OGC referred to an international standard, and a digital map was made.