• Journal of Institute of Control, Robotics and Systems
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• v.21 no.12
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• pp.1185-1192
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• 2015

In this paper, a study of advanced sound source localization is conducted by eliminating the noise of the sound source using the discrete wavelet transform. And experiments are conducted to evaluate the performance of the proposed system that the mobile robot follows sound source stably. In addition, we compare the position estimation performance by applying a discrete wavelet transform to improve the reliability of the sound signal. The experimental results reveal that the de-nosing filter which removes the noise component in sound source can make the performance of position estimation more precisely and help the mobile robot distinguish the objective sound source clearly.

• Agribusiness and Information Management
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• v.9 no.1
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• pp.18-22
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• 2017

It takes lots of time and labor if a worker have to measure the water quality at a certain but designated time every day in an un-automated aqua farm. In addition, if the equipment is soaked in the sea water consistently, it will be contaminated by diverse floating matters and barnacles, and it often becomes mal-functional within 2~3 months. Therefore, we need to develop a system with which the sensed data could be checked in real time and operated automatically, while preventing the contamination of the sensor, a crucial component for water quality measuring equipment, as much as possible, and increasing the replacement cycle. We have developed a non-cleaning water quality measuring equipment and its software which are used in the fishery household of offshore aqua farms. By providing the workers with a mobile application which has a function of monitoring the water quality in real time, they can check the situation directly without going to the fishery household.

• International Journal of Internet, Broadcasting and Communication
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• v.4 no.1
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• pp.3-7
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• 2012

Traditionally SCADA is connected only in a limited private network. With new technology and facilities, there are also demands of connecting SCADA though the internet. The internet SCADA facility has brought a lot of advantages in terms of control, data viewing and generation. Aside from connecting SCADA to the internet, there are also operators who want to connect their system wirelessly. This can save budget for communication lines. Along with the advantages it brings, are security issues regarding wireless internet SCADA. In this paper, we discuss internet SCADA, its connection through wireless communication and the security issues surrounding it. To answer the security issues, a symmetric-key encryption for internet SCADA is proposed.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.184-188
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• 2001

In this paper, a new fully digital control method for single-phase UPS inverter, which is based on the double control loop such as the outer voltage control loop and inner current control loop, is proposed. The inner current control loop is designed and implemented in the form of internal model control and takes the presence of computational time-delay into account. Therefore, this method provides an overshoot-free reference-to-output response. In the proposed scheme, the outer voltage control loop employing P controller with resonance model implemented by a DSP is introduced. The proposed resonance model has an infinite gain at resonant frequency, and it exhibits a function similar to an integrator for AC component. Thus the outer voltage control loop causes no steady state error as regard to both magnitude and phase. The effectiveness of the proposed control system has been demonstrated by the simulation and experimental results respectively.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.3
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• pp.47-55
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• 1996

An optical transmitter, which is a key component of the optical transmission system, converts the electrical signal to optical signal and consists of a high-speed current-pulse driver for laser diode and low-speed feedback loops that stabilize optical power against aging, power supply voltage fluctuations, and ambient temperature changes. In this paper, the power-stabilizing part, which forms the bulk of the optical transmitter circuitry was designed in integrted circuits. Operational amplifiers and reference voltage generation circuits, which were identified as key building blocks for the power-stabilizing feedback loops, were designed and were subsequently verified through HSPICE simulations. The designed operational amplifier consists of a two-stage folded cascode amplifier and class AB output stage, whereas the reference voltage is obtained by bandgap reference circuits. Finally the power-stabilizing circuitry was laid out based on 3\mu$m CMOS design rules for fabrication.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.12
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• pp.106-113
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• 1997

While driving, the low frequency interior noise below 200Hz causes the main component that irritates the auditory acoustic sense. But these passive control methods bring out increment in cost and weight of the vehicle and result in low efficiency. Recently, various ANC(Active Noise Control) methos to suppress the low frequency noise began to launch into application. In this study, we implemented the active noise control system for passenger vehicle to cancel the engine booming noise using DSP-based control unit, 4 micorphones, and 2 speakers. We used MEFX-LMS (Multiple Error Filtered X-Least Mean Square) algorithm since it can be easily implemented in real time. Also, MEFX-RLS algorithm was taken to enhance the suppression of the harmonic components of the engine booming noise inspite of its computational complexity. The performance of two adaptive algorithms were analyzed with experimental resutls.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.8
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• pp.569-576
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• 2007

The desiccant rotor is the most essential component of desiccant cooling system, but one of its drawbacks to spread out is rotor size. To reduce the size of rotor the analysis of rotor performance is crucial. Systematic examination on the effect of desiccant and channel geometries has been conducted based on the numerical program previously developed. Considered parameters related to channel geometries are channel shape and cross section area of channel, and parameters related to desiccant are mass fraction, heat capacity, density, maximum water uptake and separation factor of isotherm. Considerable reduction of rotor size is expected by adjusting the parameters.

• Language and Information
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• v.7 no.1
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• pp.55-68
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• 2003

Most of the previous approaches to English agreement phenomena have relied upon only one component of the grammar (e.g., either syntax, or semantics, or pragmatics). This paper argues that interrelationships among different grammatical components play crucial roles in such phenomenon too (cf. Kathol 1999 and Hudson 1999). The paper proposes that, contrary to traditional wisdom, English determiner-noun agreement is morpho-syntactic whereas subject-verb and pronoun-antecedent agreement are reflections of index agreement (cf. Pollard and Sag 1994). The present hybrid analysis of English agreement shows the importance of the interaction of different components of the grammar in accounting for English agreement phenomena. In particular, once we allow morphology to tightly interact with the system of syntax, semantics, or even pragmatics, we could provide a solution to some puzzling English agreement phenomena. This allows a more principled theory of English agreement.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.28-31
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• 2004

Since the discovery of the high temperature superconductors, many researches have been performed for the practical applications of superconductivity technologies in various fields. As results. significant progress has been achieved. Especially, Superconducting Fault Current Limiter (SFCL) offers an attractive means to limit fault current in power systems. In order to verify the effectiveness of the SFCL, in this paper, the analysis of fault current and voltage stability assessment in a distribution system are performed by the PSCAD/EMTDC-based simulation method in which a component for resistive type ot SFCL is presented. Through the simulation. the advantage of SFCL application is shown, and the effective parameters of the SFCL are also recommended.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.595-600
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• 2004

This paper deals with a cause analysis of a squeal noise in a brake system. It has been proved that the squeal noise is influenced by the angular misalignment of a disk, disk run-out, with the previously experimental study. In this study, a cause of the noise is examined by using FE analysis program(SAMCEF) and numerical analyses with a derived analytical equation of the disk based on the experimental results. The FE analyses and numerical results show that the squeal noise is due to the disk run-out as the experimental results and the frequency component of the noise equals to that of a disk's bending mode arising from the Hopf bifurcation.