• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.977-983
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• 2003

Free vibration analysis of helical springs was performed by the use of the commercial finite element analysis program, ANSYS. The investigation of national frequency was focused on the effect of various parameters such as boundary conditions, spring indices, number of coil turns and helix angles which are considered to affect the free vibration of a spring. The finite element method was validated by comparison with the result of a previouosly published literature. The similarity of frequency trend was shown among three boundary conditions: clamped-clamped, free-free, simpliy supported-simply supported but there was no similarity in light of mode shapes among them. Several modes showed similar frequencies on and near the frequencies identified by the natural frequency formula of Wahl. Natural frequencies increased with spring indices and number of turns decreasing and with helix angles increasing. The results investigated by finiete element method were compared with the experemental result and theoretical result and showed a good agreement among them.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.215-226
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• 2007

To verify the performance of roadside barriers, occupant risk indices are calculated from acceleration and angular velocity data of vehicle crash tests. The occupant risk indices to be computed include THIV(Theoretical Head Impact Velocity), PHD(Post-impact Head Deceleration), ASI(Acceleration Severity Index), OIV(Occupant Impact Velocity) and ORA(Occupant Ridedown Acceleration). There is a confusion due to different values of occupant risk indices produced for the same test data because various computational procedures and data processing methods can be applied to compute them. To slove this problem the effects of various numerical procedures and data processing methods on occupant risk indices were investigated. If the sampling rate specified in the guidelines is used for full-scale vehicle crash tests, an interpolation of impact time and numerical integration methods do not result in an appreciable change of THIV and OIV. The way to determine 10msec moving average for PHD and zero offset of data processing should be specified in the guidelines because 10msec moving average and zero offset methods have a significant influence on occupant risk indices.

• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.159-173
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• 1998

Quality characteristics on the properties of process capability indices (PCIs) are often required to be normally distributed. But, if a characteristic is not normally distributed, serious errors can result from normal-based techniques. In this case, we may well consider the use of new PCIs specially designed to be robust for non-normality. In this paper, a newly proposed measure of process capability is introduced and compared with existing PCIs using the simulated non-normal data.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.541-543
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• 2000

This paper describes the unified reliability evaluation with partial loss of continuity for complex distribution system. To evaluate reliability considering line limitation of the system, PLOC technique is employed. And reliability indices calculation method is used. Finally, Analytic network process method is employed. As a result, calculating accurate reliability, finding weak points, and expansion scheduling of the system is possible.

• Geomechanics and Engineering
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• v.8 no.5
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• pp.631-647
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• 2015

Engineers may encounter unpredictable cavities, sinkholes and karst conduits while tunneling in karst area, and water inrush disaster frequently occurs and endanger the construction safety, resulting in huge casualties and economic loss. Therefore, an optimal classification method based on grey system theory (GST) is established and applied to accurately predict the occurrence probability of water inrush. Considering the weights of evaluation indices, an improved formula is applied to calculate the grey relational grade. Two evaluation indices systems are proposed for risk assessment of water inrush in design stage and construction stage, respectively, and the evaluation indices are quantitatively graded according to four risk grades. To verify the accuracy and feasibility of optimal classification method, comparisons of the evaluation results derived from the aforementioned method and attribute synthetic evaluation system are made. Furthermore, evaluation of engineering practice is carried through with the Xiakou Tunnel as a case study, and the evaluation result is generally in good agreement with the field-observed result. This risk assessment methodology provides a powerful tool with which engineers can systematically evaluate the risk of water inrush in karst tunnels.

• Architectural research
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• v.16 no.1
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• pp.1-8
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• 2014

Although Feng-Shui has been widely used in architecture and urban design and planning for thousands of years, it has not been properly studied as a scientific and thus rational approach. Feng-Shui has been recognized as an environment-friendly design and planning method in recent years due to its thoughtful consideration on the harmonious relationship between architecture and the natural environment. This study investigates its major principles and techniques that have been widely used in the design of houses through previous relevant researches. Then, the principles and techniques that are relevant to the residential uses are indexed for the quantification of Feng-Shui. Ten Feng-Shui indices are formulated and each index is quantified to make five points for a perfect match. These indices are then tested on three different types of house in Korea, namely traditional Korean houses, contemporary Korean style houses and contemporary architects' houses. The result shows that the first type of house records the highest Feng-Shui points and then the second and third types in that order. This result convinces us that the Feng-Shui indices can very effectively represent the degree of environmentally friendly design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.3
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• pp.119-128
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• 2002

This study discusses the issues related to the accuracy of deflection measurement and unstable energy in the testing of FRC. Some deflection methods may include large extraneous deformations. A faulty load-deflection curve will be obtained if an unstable deflection measuring system is used, and inaccurate toughness evaluation can result from this faulty curve. Some load-deflection curve of FRC may be attributed to unstable region of the load-deflection curve. If the unstable region is not correctly evaluated toughness indices from the curve would inappropriately represent true indices. In this paper, the discussion will focus on the effects of the deflection measuring system both on the measurement of the load-deflection response of FRC and the evaluation of FRC toughness and the effects of the unstable region and the management method of unstable region on toughness evaluation of FRC. It is observed that ASTM toughness indices which is based on measured deflection at first cracking is influenced significantly by extraneous deformation of deflection measurement. Extraneous deformation in deflection measurement, however result in negligible errors in toughness evaluation if JSCE and JCI definitions are used.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.1
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• pp.64-78
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• 1999

Recently, new concept and paradigm of 'Environmental Sustainability' is taking a growing interest in environmental planning and design. This study is to establish the environmental sustainability principles, based on the concept of ESSD, and to develop the evaluation model of environmental sustainability for korean rural housing estates. A sustainability indices system, which is composed of 5 principles, 16 categories, an 37 estimation items, was finally established. Five principles of environmental sustainability for rural housing estate were. 'Sustainable Land Use', 'Interdependence of Men and Nature', 'Ecological Principles and Diversity', 'Efficient use of Energy and Recycling', and ' Minimizing Environmental Pollution'. And weighting values of each indicators, such as estimation items, categories, and principles, were estimated, based on the result of AHP etc. The questinnaire survey was conducted for experts of four related major fields. Finally, the validity and reliability of the sustainability indices system were verified.

• Journal of Korean Medicine for Obesity Research
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• v.4 no.1
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• pp.55-60
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• 2004

Objective: Obesity is an established risk factor for Coronary Heart Disease, but its role as risk factor for Stroke remains controversial. And we examined association between Obesity indices and Stroke cross sectionally. Methods: The subjects were 30 stroke patients admitted in hospital. We measured obesity indices of BMI, waist circumference and waist-to-height ratio. Result: There was a significant correlation among BMI, waist circumference and waist-to-height ratio. 47% of subjects were obese in BMI and 93% of subjects were obese in waist-to-height ratio. Conclusion: Abdominal obesity measured by waist circumference and waist-to-height ratio may be a better predictor of stroke than BMI.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.45-45
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• 2013

We present a test of the emission statistics of active galactic nuclei (AGN), probing the connection between the red-noise temporal power spectra and multi-modal flux distributions known from observations. We simulate AGN lightcurves under the assumption of uniform stochastic emission processes for different power-law indices of their respective power spectra. For sufficiently shallow slopes (power-law indices beta ${\leq}$ 1.0), the flux distributions (histograms) of the resulting lightcurves are approximately Gaussian. For indices corresponding to steeper slopes (beta ${\geq}$ 1.0), the flux distributions become multi-modal. This finding disagrees systematically with result of recent mm/radio observations. Accordingly, we conclude that the emission from AGN does not necessarily originate from uniform stochastic processes even if their power spectra suggest otherwise. Possible mechanisms include transitions between different activity states and/or the presence of multiple, spatially disconnected, emission regions.