• Wind and Structures
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• v.4 no.4
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• pp.333-352
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• 2001

A two dimensional discrete vortex method (DIVEX) has been developed to predict unsteady and incompressible flow fields around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow field that the particles collectively induce. This paper gives a brief description of the numerical implementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section. The predictions for the static section demonstrate that the method captures the character of the flow field at different angles of incidence. In addition, flutter derivatives are obtained from simulations of the flow field around the section undergoing vertical and torsional oscillatory motion. The subsequent predictions of the critical flutter velocity compare well with those from both experiment and other computations. A brief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and the results from DIVEX are shown to be in accordance with previous analytical and experimental studies. In conclusion, the results indicate that DIVEX is a very useful design tool in the field of wind engineering.

• Earthquakes and Structures
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• v.9 no.5
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• pp.957-981
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• 2015

Earthquakes occur as a cluster in many regions around the world where complex fault systems exist. The repeated shaking usually induces accumulative damage to affected structures. Damage accumulation in structural systems increases their level of degradation in stiffness and also reduces their strength. Many existing analytical tools of modeling RC structures lack the salient damage features that account for stiffness and strength degradation resulting from repeated earthquake loading. Therefore, these tools are inadequate to study the response of structures in regions prone to multiple earthquakes hazard. The objective of this paper is twofold: (a) develop a tool that contains appropriate damage features for the numerical analysis of RC structures subjected to more than one earthquake; and (b) conduct a parametric study that investigates the effects of multiple earthquakes on the response of RC moment resisting frame systems. For this purpose, macroscopic constitutive models of concrete and steel materials that contain the aforementioned damage features and are capable of accurately capturing materials degrading behavior, are selected and implemented into fiber-based finite element software. Furthermore, finite element models that utilize the implemented concrete and steel stress-strain hysteresis are developed. The models are then subjected to selected sets of earthquake sequences. The results presented in this study clearly indicate that the response of degrading structural systems is appreciably influenced by strong-motion sequences in a manner that cannot be predicted from simple analysis. It also confirms that the effects of multiple earthquakes on earthquake safety can be very considerable.

• Journal of the Korea Society of Computer and Information
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• v.8 no.3
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• pp.66-72
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• 2003

An ordinary differential equation in analytical numerics is utilized to some applications, for example, physics, mechanical engineering, electrical engineering, thermodynamics and etc. But this equation has problems a lots to process in the real time processing by software method. This paper is proposed a systolic Arrays architecture for solving the Runge-Kutta method. it is one of method for solving an ordinary differential equation. the proposed its architecture is very high speed and regular. this hardware proposed in this paper may be part of the mathematical problem solver's tool kit in the future and may be available to many applications in the engineering.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.05a
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• pp.106-109
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• 2005

The awareness of ecological friendliness has been emerging in the recent years, and the application to housing is quite notable. The purpose of this study was to examine multi-family housing that has recently developed with the idea of ecological friendliness, and to investigate the residents' attitudes toward and their preferences for the features. The research utilized in-depth interviews and site visits, and seven residents in the studied housing developments participated in the study. The analytical tool used in the interview was reviewed by a panel of professionals and included five aspects of ecologically friendliness: residential comfort, energy saving, open housing, storage, and safety and security. The respondents pointed out that south-facing housing in relation to residential comfort was most favorable. With regard to energy-saving, water-saving features and dehydrator of food waste were most needed features. As for open housing-related features, flexibility in spatial configuration was necessary, and efficient storage was regarded as important. Also, the respondents mentioned the preference for flooring preventing slippery in bathroom for the safety of family member.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2007.10b
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• pp.127-132
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• 2007

Geomancy(風水, Fengshui in Chinese) is a geographic idea of the Orient that studies a piece of land(a site) to pursue the healthier and more comfortable life for people seeking a harmony with nature, and also, a practical science. Among the theoretical systems of the traditional geomancy handed down by the scriptures, the compass school(理氣論) makes researches into mountains, winds, the currents and amount of water circulation by using luo-pan(羅盤) for finding spot(穴), and it has been considered that it is the objective and logical analysis system of natural environment of selecting a good site by dividing the vitality of the ground into 12 levels of natural circulation principles and judging its direction by means of 88-direction method. In this context, researcher optimized the logic of 88-direction method by the 12-circulation system(胞胎法) of the compass school on the basis of directional theory, then after, using GIS analytical tool, researcher performed comparative analysis between the results from land suitability analysis of the subject site and the resulting value of the directional method in geomancy. The results therefrom indicated that more flexible directions and site could be chosen by applying 88-direction method. For the future research, it is required to apply wider variety of variables to the field study and more careful review of the case study with a focus on the 88-directiont method.

• Journal of Sensor Science and Technology
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• v.19 no.6
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• pp.403-420
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• 2010

Nano and micro structure-based biosensors are promising tool for label-free detection of biomolecular interactions with great accuracy. This review gives a brief survey on nano and micro platforms to sense a variety of analytes such as DNA, proteins and viruses. Among incredible nano and micro structure for bio-analytical applications, the scope of this paper will be limited to micro and nano resonators and nanowire field-effect transistors. Nanomechanical motion of the resonators transducers biological information to readable signals. They are commonly combined with an optical, capacitive or piezo-resistive detection systems. Binding of target molecule to the modified surface of nanowire modulates the current of the nanowire through electrical field-effect. Both detection methods have advantages of label-free, real-time and high sensitive detection. These structures can be extended to fabricate array-type sensors for multiplexed detection and high-throughput analysis. The biosensors based on these structures will be applied to lab-on-a-chip platforms and point-of-care diagnostics. Basic concepts including detection mechanisms and trends in their fields will be covered in this review.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.843-847
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• 2014

In Super Junction (SJ) MOSFETs, charge balance is the most important issue of the SJ fabrication process. In order to achieve the best electrical characteristics, such as breakdown voltage and on-resistance, the N-type and P-type drift regions must be fully depleted when the drain bias approaches the breakdown voltage, which is known as the charge balance condition. In conventional charge balance analysis, based on multi-epi process SJ MOSFETs, analytical model has only N, P pillar width and doping concentration parameter. But applying a conventional charge balance principle to trench filling process, easier than Multi-epi process, is impossible due to the missing of the trench angle parameter. To achieve much more superior characteristics of on-resistance in trench filling SJ MOFET, the appropriate trench angle is necessary. So in this paper, modulated charge balance analysis is proposed, in which a trench angle parameter is added. The proposed method is validated using the TCAD simulation tool.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.719-728
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• 2013

Probabilistic assessment of voltage stability margin (VSM) with existence of correlated wind speeds is investigated. Nataf transformation is adopted to establish wind speed correlation (WSC) model. Based on the saddle-node bifurcation transversality condition equations and Monte Carlo simulation technique, probability distribution of VSM is determined. With correlation coefficients range low to high value, the effect of WSC on VSM is studied. In addition, two risk indexes are proposed and the possible threat caused by WSC is evaluated from the viewpoint of risk analysis. Experimental results show that the presence of correlated wind speeds is harmful to safe and stable operation of a power system as far as voltage stability is concerned. The achievement of this paper gives a detailed elaboration about the influence of WSC on voltage stability and provides a potentially effective analytical tool for modern power system with large-scale wind power sources integration.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.878-888
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• 2016

Cogging torque has a negative impact on the operation of permanent magnet machines by increasing torque ripple, speed ripple, acoustic noise and vibration. In this paper Magnet Shifting Method has been used as a tool to reduce the cogging torque in inset Line Start Permanent Magnet Synchronous Motor (LSPMSM). It has been shown that Magnet Shifting Method can effectively eliminate several lower-order harmonics of cogging torque. In order to implement the method, first the expression of cogging torque is studied based on the Fourier analysis. An analytical expression is then introduced based on Permanent Magnet Shifting to reduce cogging torque of LSPMS motors. The method is applied to some existing machine designs and their performances are obtained using Finite Element Analysis (FEA). The effect of magnet shifting on pole mmf (magneto motive force) distribution in air gap is discussed. The side effects of magnet shifting on back-EMF, core losses and torque profile distortion are taken into account in this investigation. Finally the experimental results on two prototypes 24 slot 4 pole inset LSPMS motors have been used to validate the theoretical analysis.

• Korean Journal of Pharmacognosy
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• v.41 no.3
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• pp.161-165
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• 2010

A study was performed to assess the quality equivalence of commercially available Hwang-Ryun-Hae-Dok-Tang granules from various vendors in terms of the contents of characterizing compounds. 'Hwang-Ryun-Hae-Dok-Tang'(or 'Huanglian Jiedu Tang') is the complex medicinal herbal product which is composed of four different herbal drugs; Scutellariae Radix, Coptidis Rhizoma, Phellodendri Cortex and Gardeniae Fructus. Using a high performance liquid chromatography and direct analysis in real time mass spectrometer (DART-MS), five characterizing compounds such as baicalin, baicalein, berberine, palmatine, and geniposide were analyzed to compare the variance of the contents between the products from four different vendors. Although five characterizing compounds were all successfully detected from all the products, the contents of each compound were shown to have significant difference among vendors. For real time monitoring of characterizing compounds in medicinal herbal products, DART-MS can be successfully adopted as a powerful analytical tool.