• Economic and Environmental Geology
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• v.33 no.2
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• pp.129-138
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• 2000

The various types of geohazards like landslides resulted from civil construction (i.e. highway construction) must of analysed considering all the possible influential factor systematically. Thus, by using GIS, slope stability can be evaluated, and it can be used as a data for further detailed investigation. So the aim of this study is to present a data for decision making in selecting suitable point for remediation. For analysing slope instability, through appropriate definition and classification, landslide mechanism must be understood. In building GIS model, the selection of appropriate factors and their rating system should be made. For this, the characteristics and the mechanism of landslide have to be understood. And suitable coverage should be chosen for the model considering the slope conditions. In this study, field investigation in lst and 2nd Section, Chung-ang highway was carried out. From the field data, GIS model on slope instability was created. 5 coverages were used for it. From the result of this study, 12 unstable sections were found out and more detailed investigation is needed there.

• Bulletin of the Korean Mathematical Society
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• v.51 no.2
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• pp.457-478
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• 2014

In this paper, a 3D autonomous system, which has only stable or non-hyperbolic equilibria but still generates chaos, is presented. This system is topologically non-equivalent to the original Lorenz system and all Lorenz-type systems. This motivates us to further study some of its dynamical behaviors, such as the local stability of equilibrium points, the Lyapunov exponent, the dissipativity, the chaotic waveform in time domain, the continuous frequency spectrum, the Poincar$\acute{e}$ map and the forming mechanism for compound structure of its special cases. Especially, with the help of the Project Method, its Hopf bifurcation of codimension one is in detailed formulated. Numerical simulation results not only examine the corresponding theoretical analytical results, but also show that this system possesses abundant and complex dynamical properties not solved theoretically, which need further attention.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.201-202
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• 2012

This paper presents design and implementation of the PCU(150 kVA 3-Phase PWM Inverter for Electric Vehicles). For Implementation of the PCU, it is consist with Case, Connectors, IGBT module for PWM switching, DC-capacitor for dc-source, resolver for sensing of speed & position, and PCB board for control & gate-driver. Also, for the purpose of stable operation of the PCU in vehicle with variable torque condition in motor, current control scheme based on torque-map are developed. According to real-car test mode, the prototype of proposed the PCU is verified with performance and stability. Thus, design and implement of the PCU are discussed, and experimental results are presented in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.936-941
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• 2001

This paper deals with the design of oil-tree motor-driven two-stage centrifugal compressor supported by air-lubricated multi-leaf foil bearings. The design of this compressor is performed, based upon prediction of critical speeds, load capacity, and stability. It is demonstrated in this paper that multi-leaf foil bearings can be adopted to satisfactorily support this centrifugal compressor.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.1-6
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• 2016

Keeping a system in stable state is one of the important issues of control theory. The main goal of our basic research is stability of unmanned aerial vehicle (quadrotor). This type of system uses a variety of sensors to stabilize. In control theory and automatic control system to stabilize any system it is need to apply feedback control based on information from sensors. Our aim is to provide balance based on the 3D spatial information in real time. We used PID control method for stabilization of a seesaw balancing system and the article presents our experimental results. This paper presents the possibility of balancing of seesaw system based on feedback information from stereo vision system only.

• Journal of the Korean Mathematical Society
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• v.46 no.1
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• pp.71-82
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• 2009

In this paper, a stage-structured predator-prey system with impulsive perturbations and time delays is presented to investigate the ecological problem of how a pest population and natural enemy population can coexist. Sufficient conditions are obtained using a discrete dynamical system determined by a stroboscopic map, which guarantee that a 'predator-extinction' periodic solution is globally attractive. When the impulsive period is longer than some time threshold or the impulsive harvesting rate is below a control threshold, the system is permanent. Our results provide some reasonable suggestions for pest management.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.6
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• pp.37-45
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• 2005

Almost every year, Korea has been suffered from serious damages of lives and properties, due to landslides that are triggered by heavy rains in monsoon season. In this paper, we systematized the physically based landslide prediction model which consisted of 3 parts, infinite slope stability analysis model, groundwater flow model and soil depth model. To evaluate its applicability to the prediction of landslides, the data of actual landslides were plotted on the predicted areas on the GIS map. The matching rate of this model to the actual data was $84.8\%$. And the relation between hydrological and land form factors and potential landslide were analyzed.

• Journal of Power Electronics
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• v.14 no.4
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• pp.778-787
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• 2014

This study presents an input filter resonance mitigation method for an AC-DC matrix converter. This method combines the advantages of the one-cycle control strategy and the active damping technique. Unnecessary sensors are removed, and system cost is reduced by employing the grid-side input currents as feedback to damp out LC resonance. A model that includes the proposed method and the input filter is established with consideration of the delay caused by the actual controller. A zero-pole map is employed to analyze model stability and to investigate virtual resistor parameter design principles. Based on a double closed-loop control scheme, the one-cycle control strategy does not require any complex modulation index control. Thus, this strategy can be more easily implemented than traditional space vector-based methods. Experimental results demonstrate the veracity of theoretical analysis and the feasibility of the proposed approach.

• The Journal of Korea Robotics Society
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• v.13 no.4
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• pp.220-229
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• 2018

In the midst of disaster, such as an earthquake or a nuclear radiation exposure area, there are huge risks to send human crews. Many robotic researchers have studied to send UGVs in order to replace human crews at dangerous environments. So far, two-dimensional camera information has been widely used for teleoperation of UGVs. Recently, three-dimensional information based teleoperations are attempted to compensate the limitations of camera information based teleoperation. In this paper, the 3D map information of indoor and outdoor environments reconstructed in real-time is utilized in the UGV teleoperation. Further, we apply the LTE communication technology to endure the stability of the teleoperation even under the deteriorate environment. The proposed teleoperation system is performed at explosive disposal missions and their feasibilities could be verified through completion of that missions using the UGV with the Explosive Ordnance Disposal (EOD) team of Busan Port Security Corporation.

• Journal of Auto-vehicle Safety Association
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• v.11 no.1
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• pp.48-54
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• 2019

Optimal engine control is needed to cope with the global environmental regulations that are globally enforced. For optimum engine control, the electronic throttle control system (ETCS) is a prerequisite. Automotive makers are having an effect on reducing emissions and improving fuel economy by applying ETCS which is designed to secure stability. The ETCS controls the output of the throttle valve by passing the output value of the accelerator position sensor (APS) to the engine control unit (ECU). In this study, the authors investigated the safety standards of domestic and overseas accelerator control system and tried to understand how the air flow control affects the engine output by replacing the throttle. The authors suggest an improvement proposal of safety standard based on the result of driving evaluation by various modes.