• Journal of Power Electronics
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• v.18 no.2
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• pp.604-614
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• 2018

This paper proposes a synchronous switching technique for a Vienna rectifier that uses carrier-based pulse width modulation (CB-PWM). A three-phase Vienna rectifier, similar to a three-level T-type converter with three back-to-back switches, is used as a PWM rectifier. Conventional CB-PWM requires six independent gate signals to operate back-to-back switches. When internal switches are operated synchronously, only three independent gate signals are required, which simplifies the construction of gate driver circuits. However, with this method, total harmonic distortion of the input current is higher than that with conventional CB-PWM switching. A reactive current injection technique is proposed to improve current distortion. The performance of the proposed synchronous switching method and the effectiveness of the reactive current injection technique are verified using simulations and experiments performed with a set of Vienna rectifiers rated at 5 kW.

• Journal of the Korea Construction Safety Engineering Association
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• s.55
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• pp.10-17
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• 2012

Aging society may approached to our society during snatch very, and enter in super aging society for more span. Investment that we which live 21th century are many in people's quality of life elevation meantime did not consist, but stand in visual point that must improve many portions forward. For front, repletions for many equipments that consider aged on our society must consist, and much researches may have to be gone for this. According to traffic accident result, percentage of older pedestrian deaths was 46.5% as much in Korea. In particular, the crossing accidents by 59% or more of the older pedestrian traffic safety measures that target is an urgent situation. Therefore, in this study was to identify the domestic status and problem on no-sidewalk region for older pedestrians. In addition, side walk the installation and maintenance plan presented to prepare for aging society.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.63-67
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• 1993

In single-layer latticed domes with two-way grid, if we use the cross-membered junction's method for the advantage in fabrication and construction, the eccentricity is occurred in the nodal point of crossing members. This paper is aimed at investigating the buckling characteristics for the effect of eccentricity. Analysis method is based on FEM dealing with the geometically nonlinear deflection problems. As a result of the study, in the case of having eccentricity, the values of buckling strength are about 0.7 times than or not but the characteristics of buckling and deflection except buckling strength have a similar tendency each other.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1918-1924
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• 2000

Dynamic characteristics of a vertically coupled structure used for micro gyroscopes, is studied. The coupled motion between the reference and sensing vibrations causes the zero-point output which means non-zero sensing vibration without angular velocity. This structural coupling deteriorates sensing performance and dynamic stability. We theoretically analyze dynamic characteristics associated the coupling phenomenon. Effects of reference frequency and coupling factor on the rotational direction and amplitude of elliptic oscillation are studied. A method to predict the existence of curve veering or crossing in frequency trajectories is introduced for the application to the design of micro gyroscopes with a vertically decoupled structure.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.132-135
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• 2003

Solution chemistry, sorbate chemistry, and sorbent chemistry were widely investigated to find important factors that affect PAH sorption on mineral surfaces and to elucidate its microscopic mechanism. The solution chemistry, pH and ionic strength caused measurable change of HOC sorption reaction to minerals. The detectable change of Ka occurred at a pH region crossing the PZC (Point of Zero Charge) of each mineral. The PAH hydrophobicity, one of sorbate chemistry, was observed to have a strong correlation with PAM sorption to mineral. Mineral surface area was not found to be a predominant factor controlling PAH sorption. The mineral type might be more likely to play a crucial role in controlling the PAH sorption behavior. The CEC (Cation Exchange Capacity) of mineral, representing surface charge density, has meaningful correlation with regression slope of sorption coefficients (log $K_{d}$) versus aqueous activity coefficients (log Υ$_{w}$).).).

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.523-528
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• 2000

In this paper, the new type biped walking robot which is composed of the minimum number or links just for walking and its appropriate gaits are proposed. The proposed new gaits for this robot are four-crossing, crawling, standing and turning gait. In designing the biped robot we propose the Performance Index which means the needed torque per a moving distance and generate foot trajectories by $3^{rd}$ order spline Interpolation. Among those, numerically we find the optimal conditions which minimize the Performance Index. Dynamically stable walking of the biped robot is realized by satisfying the stability condition of ZMP(zero moment point), which is related to maintaining the ZMP within the region of the supporting foot during the s1n91e leg support phase. We determine the region of mass center from the stability condition of ZMP and plan references which track the mass conte. trajectory of constant velocity. Finally we implement the gaits statically tracking the planned trajectories using PD control method.

• Journal of the Korean Institute of Landscape Architecture
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• v.21 no.1
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• pp.83-94
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• 1993

After coming this century, as the propagative method of plants on a scientific foundation has been accompanied systematically, it has played an important part in the improvement of cultivar. But an existing propagative technique is not a few defects in our tasks and industrial structure which changes every hour and envirnment which undergoes a sudden change. To use developed biological knowledge recently, and existing propagative method which is main axis in sexual reproductive crossing, is increased much in the inside of internal organs by asexual reproductive means which is on a different level, and by, introducing a new character, it improves an inherited character etc. We have observed methods which supplement or replace a defect. These methods are not yet ripe for putting to practical use in the present research phase but convinced that they will offer an epoch-marking turning point.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.216-217
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• 2010

This paper presents a new software-based on-line dead-time compensation technique for single-phase grid-connected photovoltaic (PV) inverter system. To improve the mitigation of dead-time effect around the zero-crossing point of phase current, a selective harmonic elimination of instantaneous feedback current is used as an additional part of conventional current control scheme. Simulation and experimental results are shown to verify the effectiveness of proposed compensation method in the grid-connected power distributed generation systems.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.33-36
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• 1988

In this paper, the starting point of affricate is detected from the first predictor coefficient of a 12-pole linear predictive coding (LPC) analysis and phonemic segmentation is done through measuring short time energy and zero crossing rate. By this segmentation method, the duration of an aspirate can be mearsured in order to detect an aspirate or not.

• Journal of The Korean Digital Architecture Interior Association
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• v.3 no.1
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• pp.9-14
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• 2003

The purpose of this study is to find out organizing strategy of de-composition works in modern plastic arts. Through investigating the development process of De Stijl painters and Rietveld's early works and analyzing the composition and disposition type of elements such as point, line, plane, color in the selected works, we can draw some conclusions. First, Rietveld pursues the dissolution of traditional volume and the de-composition of elements as Mondrian does through crossing-connection of three listels with quadrangular section. Second, Rietveld reorganized de-composition elements with detached lines and color planes. Third, Rietveld experimented possibility of new plastic space through displacing elements, opening space, making anti-gravity space.