• Journal of Korean Society of Transportation
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• v.14 no.3
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• pp.27-44
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• 1996

The purpose of the thesis is providing a new formulation for the transit assignment problem. The existing models dealing with the transit assignment problem don't consider the congestion effects due to the insufficient capacity of transit vehicles. Besides, these models don't provide solutions satisfying the Wardrop's user equilibrium conditions. The congestion effects are considered to be concentrated at the transit stops. For the transit lines, the waiting times at the transit stops are dependent on the passenger flows. The new model suggests the route section cost function analogous to the link performance function of the auto assignment to reflect the congestion effects in congested transit network. With the asymmetric cost function, the variational inequality programming is used to obtain the solutions satisfying Wardrop's condition. The diagonalization algorithm is introduced to solve this model. Finally, the results are compared with those of EMME/2.

• The Mathematical Education
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• v.50 no.3
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• pp.355-365
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• 2011

The purpose of this study is to provide mathematical knowledge for supporting the didactical knowledge on circular measure and radian in the high school curriculum. We show that circular measure related to arcs can be mathematically justified as an angular measure and radian is a well defined concept to be able to reconcile the values of trigonometric functions and ones of circular functions, which are real variable functions. Radian has two-fold intrinsic attributes of angular measure and arc measure on the unit circle, in particular, the latter property plays a very important role in simplifying the trigonometric derivatives. To improve students's low academic achievement in trigonometry section, the useful advantage and the background over the introduction of radian should be preferentially taught and recognized to students. We suggest some teaching plans to practice in the class of elementary and middle school for enhancing teachers' and students' understanding of radian.

• Nutritional Sciences
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• v.5 no.4
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• pp.211-220
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• 2002

Vitamin C is an essential nutrient involved in many functions. Humans are unable to synthesize vitamin C de novo, because they lack the last enzyme in the biosynthetic pathway. Previous Recommended Dietary Allowances (RDAs) for vitamin C were based on prevention of deficiency with a margin of safety. However preventing deficiency may not be equivalent to ideal nutrient intake. Recommendation should be based on vitamin function in relation to concentration. For this goal, data set of the relationship between wide-range of vitamin C dose and resulting concentrations in plasma and tissues and characterization of functional outcomes in relation to these concentrations should be acquired. This article reviews the current knowledge in these areas and suggest how this knowledge may contribute toward establishing dietary guideline for ideal vitamin C intake.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.5
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• pp.19-26
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• 2010

This study was conducted to find out the reasonable optimum design method of agricultural reinforced concrete structures. Selected design variables are the dimension of concrete section, reinforced steel area, and objective function is formulated by cost function. To test the reliability, efficiency, possibility of application and reasonability of optimum design method, both continuous optimization method and mixed-discrete optimization method were applied to the design of reinforced concrete superstructure of aqueduct and application results were discussed. It is proved that mixed-discrete optimization method is more reliable, efficient and reasonable than continuous optimization method for the optimum design of reinforced concrete agricultural structures.

• Proceedings of the Korean Nutrition Society Conference
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• 2002.11b
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• pp.1157-1168
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• 2002

Vitamin C is an essential nutrient involved in many functions. Humans are unable to synthesize vitamin C de novo, because they lack the last enzyme in the biosynthetic pathway. Previous Recommended Dietary Allowances (RDAs) for vitamin C were based on prevention of deficiency with a margin of safety. However preventing deficiency may not be equivalent to ideal nutrient intake. Recommendation should be based on vitamin function in relation to concentration. For this goal, data set of the relationship between wide-range of vitamin C dose and resulting concentrations in plasma and tissues and characterization of functional outcomes in relation to these concentrations should be acquired. This article reviews the current knowledge in these areas and suggest how this knowledge may contribute toward establishing dietary guideline for ideal vitamin C intake.

• Proceedings of the Korean Nutrition Society Conference
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• 2002.11a
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• pp.54-70
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• 2002

Vitamin C is an essential nutrient involved in many functions. Humans are unable to synthesize vitamin C do novo, because they lack the last enzyme in the biosynthetic pathway. Previous Recommended Dietary Allowances (RDAs) for vitamin C were based on prevention of deficiency with a margin of safety. However preventing deficiency may not be equivalent to ideal nutrient intake. Recommendation should be based on vitamin function in relation to concentration. For this goal, data set of the relationship between wide-range of vitamin C dose and resulting concentrations in plasma and tissues and characterization of functional outcomes in relation to these concentrations should be acquired. This article reviews the current knowledge in these areas and suggest how this knowledge may contribute toward establishing dietary guideline for ideal vitamin C intake.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.10-13
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• 2008

This study suggests a virtual construction technology for railway project using virtual reality and attempts to develop a virtual construction system. For the study, the final system include the layout review function that can rearrange designed element for optimal placement and the earthwork simulation function that can visualize filling and cutting work using central line of earthwork section. Those functions can improve applicability of 3D and 4D object in the design and construction phases of railway project.

• Korean Journal of Computational Design and Engineering
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• v.6 no.3
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• pp.206-214
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• 2001

This paper describes the wire EDM (Electric Discharge Machining) CAM system considering a variable taper wire-cut and an unmanned wire EDM during the night. Wire EDM is applicable to all materials that are fairly good electrical conductors, including metals, alloys and most carbide. Thus it provides a relatively simple method for making holes of any desired cross section in materials that are too hard or brittle to be machined by most other methods. In this paper we classify variable taper wire-cut machining patterns and variable taper wire-cut geometries. Also we determine unmanned wire EDM patterns fur the productivity of wire EDM industry. Developed system consists of two modules: 1) Variable taper wire EDM module guarantees the length ratio machining function, the parametric ratio machining function and the marking function. 2) Unmanned wire EDM module guarantees the automatic wire EDM during the night. The proposed system has been tested in the fields and found to be a useful system.

• Computers and Concrete
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• v.3 no.5
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• pp.335-355
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• 2006

The application of radial basis function neural networks (RBFN) to predict the ultimate torsional strength of reinforced concrete (RC) beams is explored in this study. A database on torsional failure of RC beams with rectangular section subjected to pure torsion was retrieved from past experiments in the literature; several RBFN models are sequentially built, trained and tested. Then the ultimate torsional strength of each beam is determined from the developed RBFN models. In addition, the predictions of the RBFN models are also compared with those obtained using the ACI 318 Code equations. The study shows that the RBFN models give reasonable predictions of the ultimate torsional strength of RC beams. Moreover, the results also show that the RBFN models provide better accuracy than the existing ACI 318 equations for torsion, both in terms of root-mean-square error and coefficients of determination.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.2
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• pp.151-156
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• 2008

It is necessary to perform the research works on the general structural designs and optimum structural designs of double hull tankers and bulk carriers due to the newly built Common Structural Rules(CSR). In this study, an optimum structural design of a mid-ship part of double hull oil tanker was carried out by using the CSR. An optimum structural design program was developed by using the Pareto optimal based multi-objective function method. The hull weight and fabrication cost obtained by the single and multi-objective function methods were compared with existing ship by the consideration of CSR and material cost which is recently increasing.