• Journal of computational fluids engineering
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• v.12 no.4
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• pp.68-73
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• 2007

Computational Fluid Dynamics (CFD) approach is now playing an important role in the engineering process in these days. Generating proper grid system in time for the region of interest is prerequisite for the efficient numerical calculation of flow physics using CFD approach. Grid generation is, however, usually considered as a major obstacle for a routine and successful application of numerical approaches in the engineering process. CFD approach based on the unstructured grid system is gaining popularity due to its simplicity and efficiency for generating grid system compared to the structured grid approaches, especially for complex geometries. In this paper an automated triangular surface grid generation using CAD(Computer Aided Design) surface data is proposed. According to the present method, the CAD surface data imported in the STL(Stereo-lithography) format is processed to identify feature edges defining the topology and geometry of the surface shape first. When the feature edges are identified, node points along the edges are distributed. The initial fronts which connect those feature edge nodes are constructed and then they are advanced along the CAD surface data inward until the surface is fully covered by triangular surface grid cells using Advancing Front Method. It is found that this approach can be implemented in an automated way successfully saving man-hours and reducing human-errors in generating triangular surface grid system.

• Advances in aircraft and spacecraft science
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• v.1 no.4
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• pp.427-441
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• 2014

Orbit-raising is an important step to place spacecraft from parking orbits into working orbits. Attitude control system design is crucial in the success of orbit-raising. Several text books have discussed this design and focused mainly on the traditional methods based on single-input single-output (SISO) transfer function models. These models are not good representations for many orbit-raising control systems which have multiple thrusters and each thruster has impact on the attitude defined by all outputs. Only one published article is known to use a more suitable multi-input multi-output (MIMO) Euler angle model in spacecraft orbit-raising attitude control system design. In this paper, a quaternion based MIMO model for the orbit-raising attitude control system design is proposed. The advantages of using quaternion based model for orbit-raising control system designs are (a) there is no need for mathematical transformations because the attitude measurements are normally given by quaternion, (b) quaternion based model does not depend on rotational sequences, which reduces the chance of human errors, and (c) the singular point of reduced quaternion model is the farthest from the operational point where linearization is performed. We will show that performance of quaternion model based design will be as good as the performance of Euler angle model based design for orbit-raising problem.

• Progress in Medical Physics
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• v.25 no.4
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• pp.281-287
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• 2014

The Winston Lutz test, which checks the accuracy of the isocenter for stereotactic radiosurgery (SRS), was performed with the commercial electronic portal imaging device (EPID). The usual Winston Lutz test with film was also performed for comparison with the test with EPID. The maximum difference in isocenter between the two methods was 0.32 mm. The Winston Lutz test using EPID is practical as it can reduce time and avoid human errors compared to the test with film.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.48-53
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• 2005

The world, coming into the 21st century, is preparing a new revolution called a knowledge-based society after the industrial society. The interest of the world is concentrated on information technology, nano-technology and biotechnology. In particular, the nano-technology of which study was originally started from an alternative for overcoming semiconductor micro-technology. It can be applied to most industry subject such as electronics, information and communication, machinery, chemistry, bioengineering, energy, etc. They are emerging into the technology that can change civilization of human beings. Specially, ultra precision machining is quickly applied to nano-technology in the field of machinery. Lately, with rapid development of electronics industry and optic industry, there are needs for super precision finishing of various core parts required in such related apparatuses. This paper handles stability of a super precision micro cutting machine that is a core unit of such a super precision finisher, and analyzes the results depending on the hinge type and material change, using FEM analysis. By reviewing the stability, it is possible to achieve the effect of basic data collection for unit control and to reduce trials and errors in unit design and manufacturing.

• Archives of Pharmacal Research
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• v.22 no.1
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• pp.1-8
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• 1999

Transforming growth factor-$\beta$ (TGF-$\beta$) is the prototypical multifunctional cytokine, participating in the regulation of vital cellular activities such as proliferation and differentiations as well as a number of basic physiological functions. The effects of TGF-$\beta$ are critically dependent on the expression and distribution of a family of TGF-$\beta$ receptors, the TGF-$\beta$ types I, II, and III. It is now known that a wide variety of human pathology can be caused by aberrant expression and function of these receptors. the coding sequence of the type II receptor (RII) appears to render it uniquely susceptible to DNA replication errors in the course of normal cell division. By virtue of its key role in the regulation of cell proliferation, TGF-$\beta$ RII should be considered as a tumor suppressor gene. High levels of mutation in the TGF-$\beta$ RII gene have been observed in a wide range of primarily epithelial malignancies, including colon and gastric cancer. It appears likely that mutation of the TGF-$\beta$ RII gene may be a very critical step in the pathway of carcinogenesis.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.153-168
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• 2013

Information security has been a major concern in organizations. The longstanding question of how to improve employees security behaviors and reduce human errors remains unanswered and requires further exploration in the information security domain. To do this, we propose a risk compensation theory-based model and examine the model. Research results shows that the relationships between information security countermeasures and information security compliance intention of employees are moderated by system vulnerability. However, the finding is contrary to the previously held risk compensation assumption and deserve further study. In addition, system quality does not play a moderator role in the relationship. Conclusions and implications are discussed.

• Korean Journal of Child Studies
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• v.36 no.5
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• pp.135-153
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• 2015

The purpose of this study was to investigate false belief understanding and justification reasoning according to information of reality amongst children aged 3, 4 and 5. Children aged 3 to 5 years (N = 176) participated in this study. Each child was interviewed individually and responded to questions designed to measure his/her false belief understanding. Every child responded to the false belief task under two different information conditions of reality(reality known vs reality unknown). For more specific analysis, children's reasoning responses were also recorded. The major findings of this study are as follows. Children could understand false belief more easily under reality unknown conditions. Specifically, the influences of information conditions were crucial to 3-year-olds but not to 4- and 5-year-olds. Although 3 year olds were able to avoid the systematical errors inherent in the false belief task, they still did not understand the false belief itself. This study provides specific aspects of false belief understanding and its relevance to general changes in cognitive development.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1382-1387
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• 1999

This paper presents an optimal fuzzy power system stabilizer to damp out low frequency oscillation. So far fuzzy controllers have been applied to power system stabilizing controllers due to its excellent properties on the nonlinear systems. But the design process of fuzzy logic power system stabilizer requires empirical and heuristic knowledge of human experts as well as many trial-and-errors in general. This paper presents and optimal design method of the fuzzy logic stabilizer using the genetic algorithm. Non-symmetric membership functions are optimally tuned over an evaluation function. The present inputs of fuzzy stabilizer are torque angle error and the change of torque angle error without loss of generality. The coding method used in this paper is concatenated binary mapping. Each linguistic fuzzy variable, defined as the peak of a membership function, is assigned by the mapping from a minimum value to a maximum value using eight bits. The tournament selection and the elitism are used to keep the worthy individuals in the next generation. The proposed system is applied to the one-machine infinite-bus model of a power system, and the results showed a promising possibility.

• Journal of Environmental Impact Assessment
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• v.19 no.2
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• pp.205-213
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• 2010

The purpose of this research is to analysis the application of the ISG(Index of Streetscape Greenness) in EIA through case study of Seoul. ISG is a new index which directly expresses human's perceptions of plants in a street and is defined as the area ratio of which leaves of plants occupy an eye-level view of a person standing on the center line of a street. In this research the 42 cases of 3 step reports such as plans, drafts, and final reports which had been passed through the EIA procedure of Seoul were analyzed. The results are as follows: In the drafts frequent mistakes or errors such as unsuitable picture composition, unsuitable sample points, inconsistency of the simulation result with the planting plan, and insufficient numbers of analysis were found, but almost of them were corrected in the final reports. In the most of final reports, the 30% of minimum requirement was satisfied. At all cases the changes of the ISG values were clearly positive. Finally the average current ISG was 19.6%, meanwhile the average proposed ISG was 35.4%. It was verified that the ISG is very practical index to promote green streetscape, but in order to guarantee an achievement a thorough investigation of reports are needed.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.4
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• pp.87-92
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• 2014

In spite of ICAO's effort to ensure the safety of flight operation by requiring crews, controllers, and other ground aviation staffs to use unified system for units, SI (System International of units), there are still many aircrafts designed, manufactured, and operated based on non-SI units, and many crew training in airline companies are also conducted based on non-SI. Due to this confusion of using different unit systems in international flight operation, many crew members and passengers are exposed to danger. International flights pilots may have confusion while flying different airspaces of different countries that use different unit systems, and this may cause human errors causing accidents and incidents. Due to these reasons, it is needed to establish the standards to reflect non-SI that many countries practically use to SI, which is international standard.