• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.59-65
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• 2003

The changes of beach profile with a natural longshore bar and beach profile with a fixed artificial bar are studied, respectively, using a numerical model. The quasi three dimensional wave-current-sediment transport model is applied with an addition of boundary condition for sediment transport on the artificial structure under water. The study shows that the natural bar adapts itself to the change of coastal physical environment by adjusting its location but the fixed artificial bar causes the formation of a second natural bar seaward of the fixed bar and scouring at the rear of the fixed bar. This study can be applied to work on the change of beach profile with submerged breakwaters.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.182-187
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• 2010

In the various fields of Civil Engineering, shear modulus is very important input parameters to design many constructions and to analyze ground behaviors. In general, a shear wave velocity profile is decided by various experiments before constructing a structure and, analysis and design are carried out by using decided shear wave velocity profile of the site. However, if civil structures are started to construct, the shear wave velocity will be increased more than before constructions because of confining pressure increase by the load of structure. The evaluation of the change in shear wave velocity profile is used very importantly when maintaining, managing, reinforcing and regenerating existing structures. In this study, a non-destructively geotechnical investigation method by using the HWAW method is applied to an evaluation of change in properties of the site according to construction. Generally, the space for experiments is narrow when underground of existing or on-going structures is evaluate, so a prompt non-destructive experiment is required. This prompt non-destructive experiment would be performed by various in-situ seismic methods. However, most of in-situ seismic methods need more space for experiments, so it is difficult to be applied. The HWAW method using the Harmonic wavelet transforms, which is based on time-frequency analysis, determines shear wave velocity profile. It consists of a source as well as short receiver spacing that is 1~3m, and is able to determine a shear wave velocity profile from surface to deep depth by one test on a space. As the HWAW method uses only the signal portion of the maximum local signal/noise ratio to determine a profile, it provides reliability shear modulus profile such as under construction or noisy situation by minimizing effects of noise from diverse vibration on a construction site or urban area. To estimate the applicability of the proposed method, field tests were performed in the change of geotechnical properties according to constructing a minimized modeling bent. Through this study, the change of geotechnical properties of the site was effectively evaluated according to construction of a structure.

• Journal of Korea Water Resources Association
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• v.39 no.9 s.170
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• pp.737-744
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• 2006

The velocity of the inner region of turbulent flow on a smooth bed has complex profile which can not be described with a simple formula. Though there have been a couple of formulas describing the profile, most of them have very complex forms, i.e., with many terms, with integration form, or with implicit forms. It means that it is hard to use them or it is difficult to estimate their parameters. A new single formula that describes the velocity profile of the inner region of the turbulent flow on a smooth bed was proposed. This formula has a form of the traditional log-law multiplied by a damping function. Introducing only one additional parameter, it can describe the whole inner range nicely. It approximates the law-of-the-wall in the vicinity of the bed and approaches to the log-law in the overlap region. The added parameter, damping factor, can be estimated very easily. It is not sensitive to the Reynolds number change and the velocity profile calculated by the formula does not change much due to the change of the parameter.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.3
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• pp.104-110
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• 2006

It is a study on the design of a cam profile for diesel engine SOHC. It is used a reverse engineering method without the usual copy processing. It draws up the contour data from an actual cam and processes by CNC. The profile of the cam is reappeared to be up to operational specifications that are the opening and shutting time, lift, speed and acceleration of the inhalation and escape valves. While the cam operating, the noise and vibration are occurred by the sudden change of speed. The new design of cam profile is suitable fur the valve operations to be smooth. We propose the design method of a cam profile far the reappearance of an actual cam. It is proved to be the propriety about the design of the cam profile through the processing, measurement, and comparison of the cam profile.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.8 no.4
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• pp.270-275
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• 2008

Under ubiquitous environment, recommendation system is using the collaborative filtering methods by quantifying context information, but insufficient context information can cause inaccurate recommendation result. In order to solve such problems, the researcher used context information and user's profile. But service history information in users' profiles can have the problems of being influenced by change of the user's taste or fashion as time passes by. In addition, context information and user's profile can't be properly inter-locked according to situation, which can cause inaccurate predictability. In this paper, in case a user's taste or fashion is changed as time passes by, the researcher didn't apply bundled-up value to the user's profile but applied different weight according to change of time. And the researcher could solve the problem that context information and a user's profile can't be properly inter-locked according to situation by applying different weight to the result gained by means of collaborative filtering and then by unifying it. In such ways, the researcher could improve predictability.

• Journal of the Korean earth science society
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• v.23 no.3
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• pp.242-258
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• 2002

This study investigated preservice teachers' understandings of the ontology and epistemology underlying constructivist notions of teaming. Throughout this study, the epistemological, ontological, and pedagogical characteristics for each teacher's developing views of learning were identified through four in-depth interviews. Data from interviews were used to create three profiles containing ontological beliefs, epistemological commitments and pedagogical beliefs. This study has demonstrated that the notion of a constructivist profile change has significant potential for informing the analysis and description of preservice teachers' beliefs changes. Major findings include: constructivist profile changes overtime, diversification of profile components over time, features of the teachers' pedagogical belief profile changes, and teachers' unawareness of their profiles. However, changes in ontological beliefs and epistemological commitments were not easy, nor were they easily internalized for these teachers. The implications of this research are that preservice teachers should be aware of coexisting different categories of their learning-to-teach profiles, and that teacher educators should provide these preservice teachers with instruction designed to change preservice teachers' profiles towards increasing constructivist views of teaching and learning and restricting other undesirable categories.

• Journal of The Geomorphological Association of Korea
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• v.26 no.4
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• pp.21-31
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• 2019

Timing of terrace formation is a key information for understanding the evolution of fluvial systems. In particular, dating strath terrace (i.e. timing of terrace abandonment) is more difficult than depositional terrace that is conventionally constrained by radiocarbon, OSL and other dating methods targeting samples within terrace deposit. Surface exposure dating utilizing cosmogenic ¹⁰Be provides more reliability because it can be applied directly to the surface of a fluvial terrace. Thus, this method has been increasingly used for alluvial deposits. As well as other geomorphic surfaces over the last decades. Some inherent conditions, however, such as post-depositional ¹⁰Be concentration (i.e. inheritance), surface erosion rate, and density change challenge the application of cosmogenic ¹⁰Be to depositional terrace surface against simple bedrock surface. Here we present the first application of ¹⁰Be depth profile dating to a thin-gravel covered strath terrace in Korea. Monte Carlo simulation (MCS) helped us in better constraining the timing of abandonment of the strath terrace, since which its surface stochastically denuded with time, causing unexpected change of ¹⁰Be production with depth. The age of the strath terrace estimated by MCS was 109 ka, ~4% older than the one (104 ka) calculated by simple depth profile dating, which yielded the best-fit surface erosion rate of 2.1 mm/ka. Our study demonstrates that the application of ¹⁰Be depth profile dating of strath terrace using MCS is more robust and reliable because it considers post-depositional change of initial conditions such as erosion rate.

• Design & Manufacturing
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• v.17 no.4
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• pp.63-71
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• 2023

In order to increase the extrusion production speed of aluminum, extrusion die cooling technology using liquid nitrogen has recently attracted a lot of attention. Increasing the extrusion speed increases the temperature of the bearing area of extrusion dies and the extrusion profile, which may cause defects on the surface of extruded profile. Extrusion die cooling technology is to directly inject liquid nitrogen through a cooling channel formed between the die and the backer inside the die-set. The liquid nitrogen removes heat from the die-set, and gaseous nitrogen at the exit of the channel, covers the extrusion profile of an inert atmosphere reducing the oxidation and the profile temperature. The aim of this study is to evaluate the cooling capacity by applying die cooling to extrusion of Al-Mn-based aluminum alloy flat tubes, and to investigate the effects of die cooling on the change in extrusion characteristics of flat tubes. Cooling capacity was confirmed by observing the temperature change of the extrusion profile depending on whether or not die cooling is applied. To observe changes in material characteristics due to die cooling, surface observation is conducted and microstructure and precipitate analysis are performed by FE-SEM on the surface and longitudinal cross section of the extruded flat tubes.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1092-1099
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• 2011

This paper is concerned with the ATO speed profile generation method in the moving block system. The ATO speed profile is calculated using the acceleration limit and the jerk limit to improve ride comfort. In addition, the speed limit and stop distance provided from ATP profile should be considered to ensure safety. In the moving block system, the speed limit and the stop position are frequently changed in real-time. Therefore, the ATO speed profile should be regenerated immediately according to change of the speed limit and the stop position, within the acceleration limit and the jerk limit. In this paper, the ATO speed profile generation method is proposed, which considers not only frequent changes of the speed limit and the stop position but also acceleration limit and jerk limit. Futhermore the simulation result is presented to verify usefulness of this method.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.4
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• pp.270-276
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• 2012

With the increase in amount of data and information available on the web, there have been high demands on personalized information retrieval services to provide context-aware services for the web users. This paper proposes a novel dynamic multi-agent context-awareness user profile construction method based on ontology to incorporate concepts and properties to model the user profile. This method comprehensively considers the frequency and the specific of the concept in one document and its corresponding domain ontology to construct the user profile, based on which, a fuzzy c-means clustering method is adopted to cluster the user's interest domain, and a dynamic update policy is adopted to continuously consider the change of the users' interest. The simulation result shows that along with the gradual perfection of the our user profile, our proposed system is better than traditional semantic based retrieval system in terms of the Recall Ratio and Precision Ratio.