• Journal of Elementary Mathematics Education in Korea
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• v.13 no.1
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• pp.115-140
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• 2009

Freudenthal has advocated the mathematisation theory. Mathematisation is an activity which endow the reality with order, through organizing phenomena. According to mathematisation theory, the departure of children's learning of mathematics is not ready-made formal mathematics, but reality which contains mathematical germination. In the first place, children mathematise reality through informal method, secondly this resulting reality is mathematised by new tool. Through survey, it turns out that area unit of Korea's seventh elementary mathematics textbook is not correspond to mathematisation theory. In that textbook, the area formular is hastily presented without sufficient real context, and the relational understanding of area concept is overwhelmed by the practice of the area formular. In this thesis, first of all, I will reconstruct area unit of seventh elementary textbook according to Freudenthal's mathematisation theory. Next, I will perform teaching experiment which is ruled by new lesson design. Lastly, I analysed the effects of teaching experiment. Through this study, I obtained the following results and suggestions. First, the mathematisation was effective on the understanding of area concept. Secondly, in both experimental and comparative class, rich-insight children more successfully achieved than poor-insight ones in the task which asked testee comparison of area from a view of number of unit square. This result show the importance of insight in mathematics education. Thirdly, in the task which asked testee computing area of figures given on lattice, experimental class handled more diverse informal strategy than comparative class. Fourthly, both experimental and comparative class showed low achievement in the task which asked testee computing area of figures by the use of Cavalieri's principle. Fifthly, Experiment class successfully achieved in the area computing task which resulting value was fraction or decimal fraction. Presently, Korea's seventh elementary mathematics textbook is excluding the area computing task which resulting value is fraction or decimal fraction. By the aid of this research, I suggest that we might progressively consider the introduction that case. Sixthly, both experimental and comparative class easily understood the relation between area and perimeter of plane figures. This result show that area and perimeter concept are integratively lessoned.

• Magazine of the Korean Society of Agricultural Engineers
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• v.8 no.2
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• pp.1124-1140
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• 1966

'This hydraulic experiment have been practised Juk an Reservoir spillway and discharge 'channel which the province Kyong Buk was constructed and designed U. hook, for seizing all state of hydraulic. As result of the experimellt planning and making the model test, it has gained the necessary data at the amendment, projection of the most rational and economical result. 1. Project (1) Experiment project....1/30 of the discharge (2) project flood....0.01945 $m^3$/sec (rapidly) 2. Design Experiment It were sighted the water level for the nine point (L. & R. sides of No. O, L. & R. of No.1, L. side of NO.2, NO.3, No. 4 and NO.5), but it appeared each other that the lowest water level was 0.63 m at spillway (No.5) and the highest water level 0.735m less than planning water level O.75 m at No. 0. It was regarded as the phenomena appearing the difference from the calculation of the rational formular and coefficient of discharge. 3. Experiment examine E. ${\circled1}$ As a table (2) it had not a difference in comparision with design and was some lower value than design experiment's. E ..${\circled2}$) !twas same table (3) in a consequence of Experiment contracted Rocky cutting. E.${\circled3}$. ${\circled4}$ It was done amend.ment Experiment by elevating G.H. in only control point, but was not sure result as a table (2)(3)(4), and so it was changed largely in ${\circled5}$ Experiment. E. ${\circled5}$ Increasing water level was understanded to be proportion to $V^2$ in consideration of centrifugal force in the curve part and showed velocity contracting in curve the effect order's being regular in consequence of 1/6 sloped extending G.H. attached from 5 No. 0 to 1. 50 m, to S No. 0+5m. (S; discharge channel number).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.459-467
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• 2014

ILM(Incremental Launching Method) bridges pass both the middle of spans and supports during launching. The launching noses are used to minimize the maximum positive moments and negative moments of the superstructure occurring during launching for ILM bridges. In this study, the simplified analysis formula considering diaphragm to calculate the bending moment that occurs during launching is induced and analyzes the optimum design conditions considering diaphragm. The accuracy of the proposed simplified analysis formular compared to the MIDAS Civil has an error of less than 5%. There is a difference up to 13% in the moment between the cases when the diaphragm is considered and is not. In addition, the criteria for deciding the unit weight of equivalent cross section and average stiffness value of equivalent cross section that can be applied to the simplified analysis formula is proposed. In this study, an effective way to optimize the launching nose is proposed that the optimum design is taken in the condition of minimizing the negative moment because of the mechanic characteristic of ILM bridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.2
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• pp.277-287
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• 2017

This paper describes the specifications on balanced steel ratio and maximum reinforcement for the design of RC flexural members by the Korean Highway Bridge Design Code based on limit states design. The Korean Highway Bridge Design Code (Limit States Design) is not provide for the balanced steel ratio specification for the calculation of required steel area of RC flexural members design. The maximum steel area limited the depth of the neutral axis at the ultimate limit states after redistribution of the moment, and also recommended the maximum steel area should not exceed 4 percent of the cross sectional area. However, from the maximum neutral axis depth provisions should increase the cross section is calculated to be less the maximum reinforcement area, and according to the 4% of the cross sectional area of the concrete, the tensile strain of the reinforcement is calculated to be greater than double the yielding strain, so can not guarantee a ductile behavior. This study developed a balanced reinforcement ratio that is basis for the required reinforcement calculation for tension-controlled RC flexural members design in the ultimate limit states verification provisons and material properties and applied the ultimate strain of the concrete compressive strength with a simple formular to be applied to design practice induced. And assumed the minimum allowable tensile strain of reinforcement double the yielding strain, and applying correction coefficient up to the ratio of maximum neutral axis depth, proposed maximum steel ratio that can be applied irrespective of the reinforcement yield strength and concrete compressive strength.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1349-1360
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• 2013

The post-tensioned anchorage zones of normal concrete have larger cross sections because of congested reinforcements to resist high bearing and bursting stresses. The high compressive and tensile strength of newly developed UHPC (Ultra High Performance Concrete) may reduce the cross sectional dimensions and simplify the reinforcement details, if used for post-tensioned members. The Finite Element Analysis was performed to evaluate the mechanical behavior of post-tensioned anchorage zones using UHPC without anchorage plates and confining reinforcements. The results show that the maximum bursting stresses are less than the values given in current design code without failure due to vertical cracks. The location of maximum bursting stresses were at 0.2 times of width of the models. The bursting force from FEA is less than that is obtained using simplified formular in Korean Bridge Design Code.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.3
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• pp.305-313
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• 2000

The calculation of earthwork plays a major role in plan or design of many civil engineering projects, and thus it has become very important to advanced the accuracy of earthwork calculation. Current methods used for estimating the volume of pit excavation assumes that the ground profile between the grid points is linear(trapezoidal rule), or nonlinear(simpson's formulas). Generally speaking. the nonlinear profile formulas provide better accuracy than the linear profile formulas. However, all the formulas mentioned have a common drawback to ground profile, such as sharp corners or the grid points of any two straight lines. In this paper, mathematical model for a searching examination the drawbacks of the current methods is presented. Also, the presented formular, the spot height method, and chamber formulas, chen and lin method are compared with the volumes of the pits in these examples. As a result of this study, algorithm of a proposal area formula by spline method should provide a better accuracy than the spot height method, chamber formulas, chen and lin method. The mathematical model mentioned make an offer maximum accuracy in estimating the volume of a pit excavation.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.3
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• pp.236-247
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• 2015

In this paper, the experimental equipments for ventilated supercavitation in cavitation tunnel is constructed and the basic data of ventilated supercavitation regard to the entrainment coefficient and Froude number is fulfilled. The experiments are conducted for the disk cavitator with injecting air and the pressure inside cavity and the shape of cavity are measured. As the entrainment coefficient increases while the Froude number is kept constant, the ventilated cavitation number decreases to a minimum value which decreases no more even with increasing the air entrainment. The minimum value of ventilated cavitation number, caused by the blockage effect, decreases according to increasing the diameter ratio of test section to cavitator. The cavity length is rapidly enlarged near the minimum cavitation number. In low Froude numbers, the cavity tail is floating up due to buoyancy and the air inside the cavity is evacuated from its rear end with twin-vortex hollow tubes. However, in high Froude numbers, the buoyancy effect is almost negligible and there is no more twin-vortex tubes so that the cavity shape becomes close to axisymmetric. In order to measure the cavity length and width, the two methods, which are to be based on the cavity shapes and the maximum width of cavity, are applied. As the entrainment coefficient increases after the ventilated cavitation number gets down to the minimum cavitation number, the cavity length still increases gradually. These phenomenon can be confirmed by the measurement using the method based on the cavity shapes. On the other hand, when the method based on the maximum width of cavity is used, the length and width of the cavity agree well with a semi-empirical formular of natural cavity. So the method based on the maximum width of cavity can be a valid method for cavitator design.

• Journal of IKEEE
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• v.20 no.3
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• pp.209-219
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• 2016

SVM is a machine learning method used for image processing. It is well known for its high classification performance. We have to perform multiple MAC operations in order to use SVM for image classification. However, if the resolution of the target image or the number of classification cases increases, the execution time of SVM also increases, which makes it difficult to be performed in real-time applications. In this paper, we propose an hardware architecture which enables real-time applications using SVM classification. We used parallel architecture to simultaneously calculate MAC operations, and also designed the system for several feature extractors for compatibility. RBF kernel was used for hardware implemenation, and the exponent calculation formular included in the kernel was modified to enable fixed point modelling. Experimental results for the system, when implemented in Xilinx ZC-706 evaluation board, show that it can process 60.46 fps for $1360{\times}800$ resolution at 100MHz clock frequency.

• Korean Journal of Oriental Medicine
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• v.17 no.3
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• pp.77-85
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• 2011

Objectives : The purpose of this study was to develop a simulator which can analyze the anti-inflammatory effects of medical herbs based on e-cell concerning p38 MAPK signal pathway. Methods : We collected data concerning medical herbs with anti-inflammatory effects and the active compounds to provide as a fundamental databse and to validate the newly developed algorithm. At this time, we used the target database as pubmed and gathered the data by data mining tool, pathway studio. Also we have developed the web-based search system for confirming database related to anti-inflammation. We researched the mechanism of actions of proteins in p38 MAPK signal pathway when active compound has been inserted into the network. We reduced total network into TAK-MKK3-p38 and made the two types of mathematical model about active compounds' interaction. Results & Conclusion : We constructed the database which have 69 cases of medical herbs, 71 cases of active compounds, about 8,000 cases of URL(Uniform Resource Locator) related to papers and reports. We designed the ordinary differential equations for response of TAK, MKK3, p38 in e-cell's cytosol and nucleus. We used this formular as measure whether an active compound of medicinal plants which is inputted by an user would have an anti-inflammation effects. We developed the visualization program which could show the change of concentration over time.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.81-93
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• 2018

The Kajiyama formula, which is an empirical formula based on the maximum flood data at Korean watersheds, has been widely used for the design of hydraulic structures and management of watersheds. However, this formula was developed based on meteorological data and flow measured during early 1900s so that it could not consider the recently changed rainfall pattern due to climate changes. Moreover, the formula does not provide the monthly coefficients for 5 months including July and August (flood season), which causes the uncertainty to accurately interpret runoff characteristics at a watershed. Thus, the objective of this study is to enhance the monthly coefficients based on the recent meteorological data and flow data expanding the range of rainfall classification. The simulated runoff using the enhanced monthly coefficients showed better performance compared to that using the original coefficients. In addition, we evaluated the applicability of the enhanced monthly coefficient for future runoff prediction. Based on the results of this study, we found that the Kajiyame formula with the enhanced coefficients could be applied for the future prediction. Hence, the Kajiyama formula with enhanced monthly coefficient can be useful to support the policy and plan related to management of watersheds in Korea.