• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.52 no.7
• /
• pp.393-400
• /
• 2003

In this paper we deal with the virtually zero power control for the rigid rotor with radial suspension by the permanent magnetic bearing and axial suspension by electromagnetic bearing. The purpose of the virtually zero power control is to reduce the power consumption of the electromagnetic bearings. The axial active force is expressed by the normal second order equation which has only one degree-of-freedom. The virtually zero power control structure has two schemes. One is the coil control current integrator which is used to make the convergence of the control current to a range which is very close to zero. By using the current integrator the DC component which is included in the control current is eliminated, thus the control current converges to a range which is close to zero. The other is normal PD control loop which is used to make the rotor reach to stable equilibrium point and to maintain air gap so that the axial force produced by radial permanent magnet always balances the total weight of the rotor and its load. First we show a simple mathematical plant model and the virtually zero power (VZP) control blocks. Second, we investigate the theoretical feasibility and the stability of the proposed virtually zero Power control levitation system with PD feedback loop by using linear control theory Finally we show the effectiveness of the proposed control method to reduce the power consumption by simulations.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.4
• /
• pp.439-447
• /
• 2011

Longitudinal cracks due to traffic truck loadings that are caused by local deformations of steel orthotropic bridge decks are sometimes observed in the wearing surface. So, underlying causes of the longitudinal pavement crack induced by structural behaviors of steel decks are investigated in this study. For this purpose, The rational finite element model of the steel deck and the pavement having the box girder is developed and a parametric study is performed by varying thickness or elastic modulus ratios of both the steel deck plate and the pavement. As a result, a large tensile strain above the webs of the u-rib and the box girder, which becomes the main cause of the cracks of the pavement, is detected from variation of the normal strain component of the wearing surface in the transverse direction.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.6
• /
• pp.33-39
• /
• 2007

The seismic source parameters of the Uljin earthquake on 29 May 2004, including focal depth, focal mechanism, magnitude, and moment tensor elements for source characteristics, are analysed using moment tensor seismic source inversion. The Green‘s function for 3 crust models representing the southern Korean Peninsula are used. Also 3 kinds of epicenters are used to find optimum solution for seismic source parameters. Results show that seismic source parameters have a little dependency of azimuthal distribution and epicentral distances of seismic stations. Final results show that the event, considering 6 moment tensor elements, is caused by the typical reverse fault with nearly NS strike. The focal mechanism implies that the tectonic force around epicenter area currently has compressive environment, with nearly EW principal axis. The focal depth is estimated to be about 12km. The resultant focal mechanism show fairly good agreement to those of other studies. However, focal depth is much different from that of other studies.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.3
• /
• pp.56-60
• /
• 2017

In hypersonic aircraft, increase of aerodynamic heat and engine heat leads heat loads in airframe. It could lead structural change of aircraft's component and malfunctioning. Endothermic fuels are liquid hydrocarbon fuels which are able to absorb the heat load by undergoing endothermic reactions. In this study, exo-tetrahydrodicyclopentadiene was selected as a model endothermic fuel and experiments were investigated in endothermic fuel cooling system with zeolite catalyst. Three shapes of catalysts have been manufactured and endothermic characteristics were recovered. Bineded catalyst showed higher heat absorption and conversion than other two zeolite catalysts. In product distribution, binded catalyst showed higher aromatics composition.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.11
• /
• pp.1105-1111
• /
• 2015

The exhaust system is one of the major sources of vibrations, along with the suspension system and engine. When the exhaust system is connected directly to the engine, it transfers vibrations to the vehicle body through the body mounts. Therefore, in order to reduce the vibrations transmitted from the exhaust system, the vibration characteristics of the exhaust system should be predicted. Thus, the dynamic characteristics of the bellows, which form a key component of the exhaust system, must be modeled accurately. However, it is difficult to model the bellows because of the complicated geometry. Though the equivalent beam modeling technique has been applied in the design stage, it is not sufficiently accurate in the case of the bellows which have complicated geometries. In this paper, we present an improved technique for modeling the bellows in a vehicle. The accuracy of the modeling method is verified by comparison with the experimental results.

• YAKHAK HOEJI
• /
• v.56 no.1
• /
• pp.20-25
• /
• 2012

In Northeast Asia, Paeoniae Radix has been used in treatments of inflammation-causing diseases such as arthritis for many centuries. Paeoniflorin, one of the principle bioactive monoterpene glucosides from the paeony root, is reported to be mostly responsible for the effectiveness of the treatments. However, the anti-inflammatory effect of a monoterpene, paeoniflorigenone (PFG) which partially has the moiety of paeoniflorin minus a glucose structure is unknown. Thus, the aim of this work was to investigate anti-inflammatory activity of PFG. For the investigation, PFG activity on the NO (nitric oxide) production from LPS-stimulated macrophages, and the anti-inflammatory effect was tested in the animal model of septic arthritis caused by Candida albicans, a major etiological agent for septic arthritis. For induction of the arthritis, mice were administered with an emulsion of C. albicans cell wall (CACW) mixed with Complete Freund's Adjuvant (CFA) via footpad-injection (Day 0); PFG at a dose of 0.5 or 1 mg/mouse (25 or 50 mg/kg of body-weight) was given to the animals on Day 3, 6, and 9; footpads were scored for arthritis. Moreover, the PFG effect on proliferation of T-lymphocyte that causes aggravation of arthritis was additionally tested. Data resulting from those tests showed that PFG inhibited the NO production from the stimulated macrophage in a dose dependent manner (P<0.05), indicating that PFG is an anti-inflammatory. To confirm the in-vitro results, anti-inflammatory activity of PFG was determined against C. albicans-caused septic arthritis. Data showed that PFG-treatment reduced footpad-swelling which indicates that PFG has anti-arthritic effect (P<0.05), which is therapeutic. The anti-arthritic effect appeared to be mediated by PFG suppression of T-cell proliferation. Ultimately, PFG, a monoterpene component, has anti-inflammatory activity analogous to paeoniflorin. The anti-inflammatory activity treats the septic arthritis due to a pathogenic fungus C. albicans.

• Journal of The Korean Association of Information Education
• /
• v.14 no.3
• /
• pp.329-339
• /
• 2010

This study has been pointed out that Information Communication Ethics Education has been mentioned only about a cognitive factor. Then the purpose of this study is verify the effects through the Instructional design of Information Communication Ethics that was compensate the problem. To achieve this, it was included all the cognitive, emotional and active factor of Integrated Character by Thomas Lickona. It has been modified that Information Communication Ethics Test of Lee Chae Young(2009) to be included all the factors of Integrated Character to verify the designed instruction. It has been designed that each steps included the component of Integrated Character using Gerlach & Ely systematic instruction model then, the designed instruction has been applied to the secondary school and verified the effectiveness. As a result, it has been proved that Experimental group is more effective than Control group.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.39 no.2
• /
• pp.69-78
• /
• 2002

This paper addresses a method to automatically detect out a person's face from a given image that consists of a hair and face view of the person and a complex background scene. Out method involves an effective detection algorithm that exploits the spatial distribution characteristics of human skin color via an adaptive fuzzy color classifier (AFCC), The universal skin-color map is derived on the chrominance component of human skin color in Cb, Cr and their corresponding luminance. The desired fuzzy system is applied to decide the skin color regions and those that are not. We use RGB model for extracting the hair color regions because the hair regions often show low brightness and chromaticity estimation of low brightness color is not stable. After some preprocessing, we apply convex-hull to each region. Consequent face detection is made from the relationship between a face's convex-hull and a head's convex-hull. The algorithm using the convex-hull shows better performance than the algorithm using pattern method. The performance of the proposed algorithm is shown by experiment. Experimental results show that the proposed algorithm successfully and efficiently detects the faces without constrained input conditions in color images.

• Journal of IKEEE
• /
• v.19 no.4
• /
• pp.541-547
• /
• 2015

In current semiconductor manufacturing, as the feature size of integrated circuit (IC) devices continuously shrinks, detecting endpoint in plasma etching process is more difficult than before. For endpoint detection, various kinds of sensors are installed in semiconductor manufacturing equipments, and sensor data are gathered with predefined sampling rate. Generally, detecting endpoint is performed using OES data of by-product. In this study, OES data of both by-product and etchant gas are used to improve reliability of endpoint detection. For the OES data pre-processing, a combination of Signal to Noise Ratio (SNR) and Principal Component Analysis (PCA),are used. Polynomial Regression and Expanded Hidden Markov model (eHMM) technique are applied to pre-processed OES data to detect endpoint.

• Management & Information Systems Review
• /
• v.31 no.4
• /
• pp.377-395
• /
• 2012

The purposes of this research was to examine the relationship between two forms of satisfaction, commitment and turnover intentions at organization, job. Also consistent with the Meyer et al(1993) notion of the three-component model of organizational commitment. Although researchers have examined organizational commitment in relation to a wide range of variables, there has been no discriminant validity of commitment at occupation and job. The purpose of the present article, are to compare the relation between satisfaction forms, commitment forms and turn intentions forms. Confirmatory factor analysis supported the proposed distinction between the three forms of commitment and two turnover intentions forms at the measurement level in the distribution industry(N=156). Results using structural equation analysis with AMOS18 showed that job satisfaction had an positive impact on job commitment forms. Organizational satisfaction positive impact on two turnover intentions forms. However it revealed that no significant relation between organizational satisfaction and job commitment, job commitment and job turnover intentions.