• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.81-88
• /
• 2005

In soft grounds with deep bearing stratum, the PHC piles are generally joined by welding or prefabricated method. However, the existing joining methods have some problems in a side view of workability, quality and cost etc. In this study, a new joining method of PHC piles, which removes the problems of the existing methods, is developed. Static and dynamic load tests in fields as well as laboratory tests such as tensile and bending tests are conducted to investigate the workability and structural safety of PHC piles joined by the new method. The test results show that tensile and bending resistances of the joint part are higher than those of PHC pile itself. PHC piles with 400mm diameter are joined by the new method within 4 minutes while 25 minutes for welding method. Bearing capacities of the PHC piles joined by the new method are nearly the same as those of jointed PHC piles by welding method.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.3
• /
• pp.450-466
• /
• 2017

This paper defines the modified effective membrane stiffness, bending stiffness considering the directionally dependent mechanical properties and mode shape function of a composite lattice rectangular plate, which is assumed to be a Kirchhoff-Love plate. It subsequently presents an approximate method of conducting a buckling analysis of the composite lattice rectangular plate with various boundary conditions under uniform compression using the Ritz method. This method considers the coupled buckling mode as well as the global and local buckling modes. The validity of the present method is verified by comparing the results of the finite element analysis. In addition, this paper performs a parametric analysis to investigate the effects of the design parameters on the critical load and buckling mode shape of the composite lattice rectangular plate based on the present method. The results allow a database to be obtained on the buckling characteristics of composite lattice rectangular plates. Consequently, it is concluded that the present method which facilitates the calculation of the critical load and buckling mode shape according to the design parameters as well as the parametric analysis are very useful not only because of their structural design but also because of the buckling analysis of composite lattice structures.

• The Journal of Korea Robotics Society
• /
• v.17 no.1
• /
• pp.1-7
• /
• 2022

Robots are widely used in industries and services. Traditional robots have been used to perform repetitive tasks in a fixed environment, and it is very difficult to solve a problem in which the physical interaction of the surrounding environment or other objects is complicated with the existing control method. Reinforcement learning has been actively studied as a method of machine learning to solve such problems, and provides answers to problems that robots have not solved in the conventional way. Studies on the learning of all physical robots are commonly affected by noise. Complex noises, such as control errors of robots, limitations in performance of measurement equipment, and complexity of physical interactions with surrounding environments and objects, can act as factors that degrade learning. A learning method that works well in a virtual environment may not very effective in a real robot. Therefore, this paper proposes a weighted sum method and a linear regression method as an effective and accurate learning method in a noisy environment. In addition, the bottle flipping was trained on a robot and compared with the existing learning method, the validity of the proposed method was verified.

• Journal of Korean Physical Therapy Science
• /
• v.5 no.3
• /
• pp.625-631
• /
• 1998

The Halliwick method was developed by Mr. James McMillan, a Canadian engineer of fluid mechanics. In 1949 he started to teach physically handicapped girls to swim at the "Halliwick school for crippled Girls" in London. The Halliwick method has four important basic units, as is shown in Fig 1. This constribution only deals with the structures or the practical part of the method. This part is also known as the 10-point programme. Before the characteristics of the 10 points are dealt with seperately, a few general remarks about these ponits have to be discussed. Of all things happening in the water, fun is the most important one. Swimming is fun! Swimming is taught in an order McMillan describes as: mental Adjustment(M.A), balance restoratiion(B.R.), inhibition(Inh.), and facilitation(Fac.). The 10 points of structure are linked to each other as well as to the learning process as is shown in Fig 3. The Halliwick method, which was devised by James McMillan, has proved to be a very successful way of establishing the basic principles as they have described in this article.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.20 no.44
• /
• pp.135-151
• /
• 1997

In this paper, we propose a simple and relatively efficient heuristic method to determine job sequencing in the flow-shop considering multiple criteria such as processing time, due date and cost. The proposed method is applicable to the flow- shop where the jobs are released simultaneously and their processing sequence is predetermined and not changed until the whole jobs are processed. To develop this method, we mixed and modified some well-known multi-attribute decision heuristics such as the simple linear weighting scheme, the lexicographic rule and the 'elimination by aspect' rule. Some computer simulations were conducted to test the efficiency of the proposed method and it has been compared with the SWPT (Shortest Working Processing Time) rule and EDD (Earliest Due Date) rule. The results show that our method is as effective as the traditional ones in terms of mean flow time, tardiness, makespan, cycle time, machine utilization, etc., and proved to be much simpler and more flexible to be used in real situations.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.15 no.5
• /
• pp.97-103
• /
• 2006

A meso-scale analysis method using the natural element method, which is a kind of meshless method, is proposed for the analysis of material damage of brittle microcracking solids such as ceramic materials, concrete and rocks. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The macro elastic moduli of anisotropic as well as isotropic solids containing a number of randomly distributed microcracks are calculated in order to demonstrate the validity of the proposed method.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.10 no.1
• /
• pp.51-55
• /
• 2014

Based on the results of Probabilistic Safety Assessment(PSA) for a Nuclear Power Plant (NPP), Common Cause Failure(CCF) events have been recognized as one of the main contributors to the risk. Also, the CCF data and estimation method used in domestic PSA models have been pointed out as an issue with respect to the quality. The existing method of MGL and non-staggered testing even widely used were considered conservative in estimating the safety and had a limited capability in uncertainty analyses. Therefore, this paper presents the CCF estimation using a new generic data source and Alpha factor method. The analyses showed that Alpha factor and staggered method are effective in estimating the CCF contribution and risk insights of reference plant. This method will be a common bases for the optimization of new design for the construction plants as well as for the updating of safety assessment on the operating nuclear power plants.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.11a
• /
• pp.681-688
• /
• 2000

This study presented the new method for evaluating the coefficient of consolidation by using inflection point method which was based on the fact that time factor, T corresponding to the inflection point of a semilogarithmic plot of a time curve is fixed and equals to T ＝ 0.405 at 70% consolidation. In the proposed method, the next load increment is applied as soon as the necessary time required to identify the inflection point. Thus, the coefficient of consolidation may be easily evaluated. The time required to complete the testing using this rapid consolidation method could be as low as 1.5-3 hours compared with 1 or 2 weeks in the case of the conventional consolidation test.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1998.10a
• /
• pp.298-305
• /
• 1998

The purpose of this study is to propose the method of determining the initial fabric membrane structures surface and membrane patterning procedures. Tension structure, such as, fabric membrane structures and cable-net, is stabilized by their initial prestress and boundary condition. The process to find initial structural overall shape of tension structures produced by initial prestress called Shape Finding or Shape Analysis. One of the most important factor for the design of membrane structures is to search initial smooth surface, because unlike steel or concrete building elements which resist loads in bending, all tension structure forces are carried within the surface by membrane stress or cable tension. To obtain initial surface of fabric membrane element in large deformation analysis, the membrane element is idealized as cable using a technique with Force-density method. and that result is compared with well-known nonlinear numerical method, such as Newton-raphson method and Dynamic relaxation method. The shape resulting from Force-density method has been dealt with as the initial membrane shape and used patterning procedures.

• Journal of Korean Institute of Industrial Engineers
• /
• v.37 no.3
• /
• pp.264-270
• /
• 2011

A new method for creating a logical data model is proposed. The logical data model developed by the method defines table, primary key, foreign key, and fields. The framework of the logical data model is constructed by modeling the relationships between events and their related entity types. The proposed method consists of a series of objective and quantitative decisions such as maximum cardinality of relationships and functional dependency between the primary key and attributes. Even beginners to database design can use the methology as long as they understand such basic concepts about relational databases as primary key, foreign key, relationship cardinality, parent-child relationship, and functional dependency. The simple and systematic approach minimizes decision errors made by a database designer. In practial database design the method creates a logical data model in Boyce-Codd normal form unless the user of the method makes a critical decision error, which is very unlikely.