• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.466-471
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• 2009

The vector control algorithm has come to be used as induction motor for high performance torque and response improvement. This paper deals with new control algorithm which improves the performance of the rotor flux control by combining the conventional current controller with the flux controller and the hysteresis controller. In voltage shortage condition, proposed algorithm shows that the response and the stability can be improved both in the simulation results and in the experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.9
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• pp.774-781
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• 2013

The purpose of this paper is to design a DVL-RPM based VKF (Velocity Kalman Filter) design for a performance improvement underwater integrated navigation system. The proposed approach relies on a VKF, augmented by a altitude from Echo-sounder based switching architecture to yield robust performance, even when DVL (Doppler Velocity Log) exceeds the measurement range and the measured value is unable to be valid. The proposed approach relies on two parts: 1) Indirect feedback navigation Kalman filter design, 2) VKF design. To evaluate proposed method, we compare the results of the VKF aided navigation system with simulation result from a PINS (Pure Inertial Navigation System) and conventional INS-DVL method. Simulations illustrate the effectiveness of the underwater navigation system assisted by the additional DVL-RPM based VKF in underwater environment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.58-63
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• 2016

This paper presents a study of heat dissipation away from the fuel combustion of a marine diesel engine. These engines are operated for long periods under high load conditions: so cooling systems are necessary for radiation and control of the high temperature levels. In the study, each component of the water cooling system was developed to achieve improvements in cooling and safety. Heat transfer considerations and arrangement design for the components were important and an intercooler and exhaust manifold incorporated. An optimization of the cooling water's flow path was achieved subject to the need for convenient maintenance. The 750Ps marine diesel engine was used for performance testing of the cooling system. The test results showed adequate cooling performance improvement.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.9
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• pp.861-869
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• 2012

This paper presents a high performance position controller in a driving system using a time optimal control which is widely used to control driving systems to a desired reference position or velocity in minimum response time. The main purpose of this study is an improvement of transient response performance rather than steady-state response comparing with another various control strategies. In order to improve the performance of time optimal control, we tried to find the cause of the steady-state error in the driving system we have already made up and also suggest the newly modified type of time optimal control method in this paper.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.296-303
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• 2006

Recently, micro hydropower attracts attention because of its clean. renewable and abundant energy resources to develop. However, suitable turbine type is not normalized yet in the range of micro hydropower and it is necessary to study for the effective turbine type. Moreover, relatively high manufacturing cost by the complex structure of the turbine is the highest barrier for developing the micro hydropower turbine. Therefore a cross-flow turbine is proposed for micro-hydropower in this study because of its simple structure and high possibility of applying to low head. The purpose of this study Is to further optimize the turbine structure and improve the performance. A guide vane is removed and the runner chamber is made compact using a new air supply method. The results show that the efficiency of the turbine is improved in a wide operating range and the size of the turbine is remarkably reduced.

• Journal of Power System Engineering
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• v.5 no.2
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• pp.87-92
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• 2001

Automotive suspension system is a mechanism for isolation of the vibration coming from the road inputs. Recently, the electronically controlled suspension systems which may improve ride and handling performance have been developed. Here, the continuously controlled semi-active suspension system is focused. As a mechanism to control damping forces continuously, a solenoid valve is used. The modeling for the solenoid valve is introduced briefly, a vehicle dynamics modeling is constructed, and then combined system model is completed. To design the efficient control algorithm for the semiactive suspension system the knowledge based fuzzy logic is applied and the technique how to apply the sky-hook theory to the fuzzy logic is developed. Finally, to confirm the improvement of performance the computer simulation is carried out.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.5
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• pp.243-249
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• 2020

Event detection in wireless sensor networks is a key requirement in many applications. Acoustic sensors are one of the most frequently used sensors for event detection in sensor networks, but they are sensitive and difficult to handle because they vary greatly depending on the environment and target characteristics of the sensor field. In this paper, we propose a learning-based improvement of CFAR algorithm for increasing node-level event detection performance in acoustic sensor networks, and verify the effectiveness of the designed algorithm by comparing and evaluating the event detection performance with other algorithms. Our experimental results demonstrate the superiority of the proposed algorithm by increasing the detection accuracy by more than 45.16% by significantly reducing false positives by 7.97 times while slightly increasing the false negative compared to the existing algorithm.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.730-735
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• 2009

The purpose of this study is to consider improvement performance to prevent condensation and draw the optimum insulation design method for building using simulation tool. In this study, the three corners, weak part in condensation, were conducted by three-dimensional steady state simulation. From the results, it is required to strengthen insulation design, and it is founded that existing insulation system typically applied to most Korean apartment buildings has serious insulation defect that insulation is disconnected by structural components at the joints of wall-slab and wall-wall in envelope. So, it is considerate to need a concrete technology improvement.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.7-10
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• 2003

In this paper, we present a new echo kernel, which is a modification of polar echo kernel. to improve the detection performance and robustness against attacks. Polar echo kernel may take advantage of large detection margin from the polarity of inserted echo signal, but its poor frequency response in low frequency band degrades sound quality. To solve this problem, we applied bipolar echo pulses to the polar echo kernel. Using the proposed echo kernel the distributions of autocepstrum peaks fur data ‘0’ and ‘1’ are located more distant and improvement of detection performance is achieved. It also makes the low frequency band flat so that the timbre difference in the polar echo kernel can be removed to reproduce the imperceptible sound qualify. Informal listening tests as well as robustness test against attacks were performed to evaluate the proposed echo kernel. Experimental results demonstrated the superiority of the proposed echo kernel to both conventional unipolar and polar echo kernels

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1595-1600
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• 2012

This paper shows an improvement of the WRSM (Wound Rotor Synchronous Motor) by satisfying the voltage limit condition at high speed. After that, it compares the performance of the improved WRSM to that of the IPMSM (Interior Permanent Magnet Synchronous Motor). The comparison has been made under the condition where the dimension of the motor is identical to that of the IPMSM, having the rotor switched to a wounded rotor form. Moreover, this paper compares the Basic Model of the two motor, and estimates the parameters of the WRSM, thereby proposing the method to improve high speed performance. Furthermore, this paper presents the feasibility of switching the conventional motor into rare-earth-free motors for traction purpose.