• Journal of the Institute of Convergence Signal Processing
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• v.14 no.3
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• pp.191-204
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• 2013

In this paper, we investigated the correlation outputs of Daejeon correlator at the viewpoints of the buffer memory setting related to the fine delay tracking and the under/overflow issue in FFT modules, in order to eliminate DC-like component and phase concentration to 0 degree. As the ring buffer memory is being used for the fine delay tracking, the DC-like component in correlation outputs is generated by improper setting of data read/write address, and then that address setting method is modified to exclude a polluted FFT segment in correlation processing when crossing the port/stream boundary. The phase concentration to 0 degree at beginning of bandpass is caused by inadequate scaling factors, which may be the origins of under/overflow occurred at internal computation of FFT stage. With the revised method of the ring buffer memory setting and the scaling factors in FFT, we could obtain higher signal-to-noise ratio and flux density, compared to the previous method, through the correlation processing of true observational data.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.5
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• pp.471-475
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• 2005

Recently, development of digital technology is occupying a large part of multimedia information like character, voice, image, video, etc. Research about video indexing and retrieval progresses especially in research relative to video. This paper proposes the novel notation in order to retrieve MPEG video in the international standards of moving picture encoding For realizing the retrieval-system, we detect DCT DC coefficient, and then we obtain shot to apply MVC(Mean Value Comparative) notation to image constructed DC coefficient. We choose the key frame for start-frame of a shot, and we have the codebook index generating it using feature of DC image and applying PCA(principal Component Analysis) to the key frame. Also, we realize the retrieval-system through similarity after indexing. We could reduce error detection due to distinguish shot from conventional shot detection algorithm. In the mean time, speed of indexing is faster by PCA due to perform it in the compressed domain, and it has an advantage which is to generate codebook due to use statistical features. Finally, we could realize efficient retrieval-system using MVC and PCA to shot detection and indexing which is important step of retrieval-system, and we using retrieval-system over the internet.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.271-279
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• 2015

Induction cooking application with multiple loads need high power inverters and appropriate control techniques. This paper proposes an inverter configuration with buck-boost converter for multiple load induction cooking application with independent control of each load. It uses one half-bridge for each load. For a given dc supply of $V_{DC}$, one more $V_{DC}$ is derived using buck-boost converter giving $2V_{DC}$ as the input to each half-bridge inverter. Series resonant loads are connected between the centre point of $2V_{DC}$ and each half-bridge. The output voltage across each load is like that of a full-bridge inverter. In the proposed configuration, half of the output power is supplied to each load directly from the source and remaining half of the output power is supplied to each load through buck-boost converter. With buck-boost converter, each half-bridge inverter output power is increased to a full-bridge inverter output power level. Each half-bridge is operated with constant and same switching frequency with asymmetrical duty cycle (ADC) control technique. By ADC, output power of each load is independently controlled. This configuration also offers reduced component count. The proposed inverter configuration is simulated and experimentally verified with two loads. Simulation and experimental results are in good agreement. This configuration can be extended to multiple loads.

• Journal of Power Electronics
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• v.14 no.5
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• pp.957-966
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• 2014

Some of DC actuators used in home automation, office automation, medical equipment and automotive systems require a position sensor. In low power applications, the introduction of such a transducer remarkably increases the whole system cost, which justifies the development of sensorless position estimation techniques. The well-known AC motor drive sensorless techniques exploiting the fundamental component of the back electromotive force cannot be used on DC motor drives. In addition, the sophisticated approaches based on current or voltage signal injection cannot be used. Therefore, an effective and inexpensive sensorless position estimation technique suitable for DC motors is presented in this paper. This technique exploits the periodic pulses of the armature current caused by commutation. It is based on a simple pulse counting algorithm, suitable for coping with the rather large variability of the pulse frequency and it leads to the realization of a sensorless position control system for low cost, medium performance systems, like those in the field of automotive applications.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1899-1901
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• 1998

A five-level VSI(Voltage Source Inverter) is introduced as a SVC(Static Var Compensator) like a large scale power source. The problems in using SVC are that the power device can easily be destroyed by voltage unbalance and accurate reactive power control is difficult because of voltage variation. A asymmetrical PAM(Pulse Amplitude Modulation) switching pattern is proposed to solve this problem and analyze both fundamental component and harmonic current in the system. Through experimental results of 3.5 kVA experimental test system. It is confirmed that DC capacitor voltage can be controlled by asymmetrical PAM switching pattern control.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.223-228
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• 1999

A five-level VSI(Voltage Source Inverter) is introduced as a SVC(Static Vu Compensator) like a large scale power source. The problems in using SVC are that the power device can easily be destroyed by voltage unbalance and accurate reactive power control is difficult because of voltage variation. A asymmetrical PAM(Pulse Amplitude Modulation) switching pattern is proposed to solve this problem and analyze both fundamental component and harmonic current in the system. Through experimental results of 3.5 kVA experimental test system, It is confirmed that DC capacitor voltage can be controlled by asymmetrical PAM switching pattern control.

• Journal of Power Electronics
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• v.11 no.2
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• pp.173-178
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• 2011

In order to verify the performance of brushless DC (BLDC) motors, the simulation method has been widely used. The current of a BLDC motors flows on two phase windings to obtain a constant torque. However, the freewheeling current caused by the inductance component of a BLDC motor exists at the commutation point so that the current can flow on three phase windings at the same time. Due to the changes of the excited phases, the model equations are frequently changed during BLDC motor drive operation. The model equations can be also changed by the applied switching pattern since the current path in the inverter circuit changes according to switching pattern. A BLDC motor system can utilize various switching patterns for many different purposes. However, such changes of the model equations complicate the simulation procedure. In this paper, the technique to set up model equations is proposed to ease the simulation of a BLDC motor system through an inverter circuit analysis. The proposed technique will be verified using the C language. Although this method does not provide the level of detail obtainable from commercial simulation tools like PSIM or SIMULINK, it can provide an efficient way to quickly compare various conditions.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.313-319
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• 2017

In this paper, we present a design technique that miniaturises the DC-DC converter, a key component in the electric vehicle system, using the advanced material (Ga-N HEMT) in the LLC resonant converter and freely changes the resonant frequency. This design is also proposed to improve the efficiency and temperature characteristics by adding SR Topology in the secondary side output during the operation of power supply. In this experiment, as a consequence of the constructed circuit with the operation of high switching frequency of 200 kHz, the size of LLC and PFC was able to be minimised by 40[%]. Thus, the characteristics of operating temperature demonstrated $60-65^{\circ}C$ without a heat sink, when the temperature was measured at 250W (12V/20A). The features were all due to the advantages of the change of switching frequency, switching circuits implementation, and the maximisation of switching frequency. Based on these design results, we would like to implement more than 1 [kW].

• Proceedings of the Korean Journal of Food and Nutrition Conference
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• 2000.05a
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• pp.1-3
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• 2000

A kind of traditional herbal prescription, Sip-Jeon-Dae-Bo-Tang (TJ-48), has been reported to improve the general condition of cancer patients receiving chemotherapy and /or radiation therapy, and to accelerate hematopoietic recovery from bone marrow injury by mitomycin C. In the present studies, we found that hot-water extract from Atractylodes lancea DC. rhizomes contributed mainly to intestinal immune modulating activity of TJ-48 on Peyer's patch cells mediated-hematopoietic response. After the fractionation, ALR-5 II a-1-1, 5 II b-2-2 and 5 II c-3-1 were further purified from crude polysaccharide fraction. Chemical analyses of each fraction indicated that ALR-5 II a-1-1 mainly contained arabinogalactan fraction whereas ALR-5 II b-2-2 and 5 II c-3-1 mostly comprised pectic polysaccharide fractions as the active polysaccharide ingredients. In order to analyze the essential structure of the activity, ALR-5 II a-1-1 was treated by sequential enzymatic digestion using exo-${\alpha}$-L-arabinofuranosidase and exo-${\beta}$-D-(1\longrightarrow3)-galactanase. Based upon the results of chemical and MALDI-TOF-MS analyses and activity on the digested fractions, the galactosyl side chains consisting of 6-linked Galf and Galp over tetrasaccharide in ALR-5 II a-1-1 might be responsible for the potent intestinal immune modulating activity. To characterize moiety of ALR-5 II c-3-1 for the expression of activity, endo-${\alpha}$-D-(1\longrightarrow4)-polygal acturonase (GL-PGase) purified from dried leaves of Panax ginseng digested ALR-5 II c-3-1. The results of structural analyses and activity on the digested fractions showed that PG-2, which structurally resembles to rhamnogalacturonan II (RG II), and PG-3 (galacturono-oligosaccharides) contained potent intestinal immune modulating activity. Further purification of the other acidic fraction (ALR-5 II b-2-2) indicated that ALR-5 II b-2-2Bb showed that the most potent activity. ALR-5 II b-2-2Bb also contained the unusual component sugars characteristics in RG- II as well as PG-2 derived from ALR-5 II c-3-1, but it could not be digested with GL-PGase. The present studies of relationship between structures and intestinal immune modulating activity of the active polysaccharides purified from A. lancea DC. rhizomes suggested that neutral galactosyl chains consisting mainly of (1\longrightarrow6)-linked Galf and Galp, and RG- II -like moiety with unique component sugars, such as 2-Me-Xyl, 2-Me-Fuc, Api, AceA, Kdo and Dha should play an important role in the potent intestinal immune modulating action of A. lancea DC. rhizomes.