• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.5
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• pp.320-333
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• 2019

In this study, a physics-based 3D morphology model for the estimation of an erosion rate of nourished beach is newly proposed. As a hydrodynamic module, IHFOAM toolbox having its roots on the OpenFoam is used. On the other hand, the morphology model comprised a transport equation for suspended sediment, and Exner type equation derived from the viewpoint of sediment budget with the bed load being taken to accounted. In doing so, the incipient motion of sediment is determined based on the Shields Diagram, while the bottom suspended sediment concentration, the bed load transport rate is figured out using the bottom shearing stress directly calculated from the numerically simulated flow field rather than the conventional quadratic law and frictional coefficient. In order to verify the proposed morphology model, we numerically simulate the nonlinear shoaling, breaking over the uniform beach of 1/m slope, and its ensuing morphology change. Numerical results show that the partially skewed, and asymmetric bottom shearing stresses can be successfully simulated. It was shown that sediments suspended and eroded at the foreshore by wave breaking are gradually drifted toward a shore and accumulated in the process of up-rush, which eventually leads to the formation of swash bar. It is also worth mentioning that the breaker bar formed by the sediments dragged by the back-wash flow which commences at the pinnacle of up-rush as the back-wash flow gets weakened due to the increased depth was successfully duplicated in the numerical simulation.

• Science of Emotion and Sensibility
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• v.6 no.1
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• pp.55-62
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• 2003

This study was an exploratory approach to the cognitive model of textile designers on the stage of motif development in textile design process. Prior to the main research, several previous studies adopting methods of video/audio protocol analysis were reviewed. On the basis of the review, the categories of design action were derived as an analysis frame by application of top-down access method, meanwhile the sub-groups of each category of design action were identified through a bottom-up access method. To summarize the research result, total three categories of textile design action appeared based on the theory of ‘Human processor’ model : ‘motor action’, ‘perceptual action’ and 'cognitive action'. In next, a new coding scheme suitably explaining these three categories of fertile design action was developed. Finally, a cognitive model of textile designer on the stage of motif development, employing the new coding scheme, was suggested in this study.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.935-942
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• 2009

During period of the rainy season of spring tide Aug. 2005, the suspended sediment transport rate from Seomjin River increased ten times as high as neap tide of low river discharge. During ebb tide of high terrestrial input, the grain size of suspended particles of both surface and bottom layer of the water column, showed a uni-modal distribution with a dominant peak at coarse fraction, which suggests a characteristic development of floc-sized particles of low mean effective density. On the contrary, the particles supplied toward upstream of Seomjin river from Gwangyang Bay during flood tide showed a bi-modal distribution with a secondary peak at finer fraction, possibly due to the resuspension and the deflocculation associated with the increased shear velocity at near bottom. Break-up of large flocs is also suggested by the increased mean effective density. However, settling velocity was lower during flood tide because of smaller grain size. Thus, net deposition of suspended sediment is expected at within Gwangyang Bay instead of upstream of Seomjin River, even though suspended sediment transport rate at near bottom water was three times higher than that at surface water during flood tide.

• International Journal of Highway Engineering
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• v.20 no.4
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• pp.21-26
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• 2018

PURPOSES : The objective of this study is to evaluate the application of soil stabilization method for soft shoulder construction in the iRoad Project of Sri Lanka. METHODS : Firstly, the quantitative analysis of soil strength improvement due to soil stabilization was done for soil samples collected from iRoad construction sites. Two types of soils were selected from iRoad Project sites and prepared for soil stabilization testing by the Road Development Authority. Secondly, the appropriate stabilizer was selected at given soil type based on test results. Two different stabilizers, ST-1 and ST-2, produced in Korea were used for estimating soil strength improvements. Finally, the optimum stabilizer content was determined for improving shoulder performance. The uniaxial compressive strength (UCS) test was conducted to evaluate the strength of stabilized soil samples in accordance with ASTM D 1633. The use of bottom ash as a stabilizer produced from power plant in Sri Lanka was also reviewed in this task. RESULTS : It is found from the UCS testing that a 3% use of soil stabilizer can improve the strength up to 2~5 times in stabilized soft shoulder soils with respect to unstabilized soils. It is also observed from UCS testing that the ST-1 shows high strength improvement in 3% of stabilizer content but the strength improvement rate with increase of stabilizer content is relatively low compared with ST-2. The ST-2 shows a low UCS value at 3% of content but the UCS values increase significantly with increase of stabilizer content. When using the ST-2 as stabilizing agent, the 5% is recommended as minimum content based on UCS testing results. Based on the testing results for bottom ash replacement, the stabilized sample with bottom ash shows the low strength value. CONCLUSIONS : This paper is intended to check the feasibility for use the soil stabilization technique for shoulder construction in Sri Lanka. The use of soil stabilizer enables to improve the durability and strength in soft shoulder materials. When applying the bottom ash as a soil stabilizer, various testings should be conducted to satisfy the specification criteria.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.707-712
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• 1998

This paper presents several softcomputing techniques such as neural networks, fuzzy logic and genetic algorithms : Neural networks as brain metaphor provide fundamental structure, fuzzy logic gives a possibility to utilize top-down knowledge from designer, and genetic algorithms as evolution metaphor determine several system parameters with the process of bottom up development. With these techniques, we develop a pattern recognizer which consists of multiple neural networks aggregated by fuzzy integral in which genetic algorithms determine the fuzzy density values. The experimental results with the problem of recognizing totally unconstrained handwritten numeral show that the performance of the proposed method is superior to that of conventional methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.173-178
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• 2001

The cost on transmission and election of precast concrete members largely depends on the weight of them. In this study, the weight of prestressed precast beam could be reduced by control the section and prestressing force to meet the required strength on the basis of the optimum process. The top and bottom concrete stress of the section considered is required to check according to each construction step for this process. The original rectangular beam weight could be reduced up to 50~39% due to the development of a U-beams from the optimum process.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.704-709
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• 1990

This study presents the structure and the gate control algorithm of KAMOBOT (KAIST Mobile Robot). The mobile robot has a six-legged, cylindrical configuration, each leg of which is equiped with a wheel at the bottom. The robot can go up and down stairs, go over obstacles, move along curvilinear paths and rotate around it's geometric center. Such maneuverability can be achieved by using only three electric motors.

• Vacuum Magazine
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• v.3 no.3
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• pp.4-9
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• 2016

Nanowires have excellent properties such as high crystallinity, good mechanical properties, quantum confinement effect and high chemical activity, and thus are promising building blocks for many applications. Here we firstly review the fabrication of nanowires by top-down and bottom-up process. We then review nanowires as building blocks for bio applications including bio sensing, cell signaling and cell stimulating. It shows that nanowires are promising for the development of advanced bio technologies that can address ultrahigh sensitivity, and long term cell signaling and stimulating without cell damages.

• Journal of Korean Society of Rural Planning
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• v.14 no.2
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• pp.1-12
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• 2008

The purpose of this study is to examine the aspects and the characteristics of conflict among people in agricultural villages shown in the course of conducting a rural community development project, and to suggest a theoretical basis for the solution of the conflict. various theories on rural community development projects and conflict, and relevant sociopsychological theories were perused to lay a theoretical foundation for the study, and 5 actual cases of conflicts in agricultural experience villages were analyzed in the light of the grounded theory which is one of suitable methods of qualitative research. And comparative and comprehensive analysis of conflicts of different farm villages was done. Based on the result of analysis of conflict among residents on agricultural experience village, this paper suggests some ways for solution of the conflict.

• Journal of the Korean Society of Systems Engineering
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• v.9 no.2
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• pp.69-82
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• 2013

US DoD operated JCIDS(Joint Capability Integration and Development System) for top down requirement generation. Although the JCIDS can be a good practice for the countries which are trying to shift from bottom up to top down requirement generation, it contains many processes related with review and approval. In this study we structured a joint capability integration and development process from the JCIDS eliminating the organization dependent review or approval process so that it can be applied to any organization with some modification. Furthermore we implemented the process in the computer aided systems engineering tool, Cradle, for convenient use of the process. The result of this study can provide a basic process for top down capability development, and an efficient why of doing each element of the process using CASE tool.