• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.149-154
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• 1999

Response Surface Methodology was applied for optimizing the processing parameters of ultrasound treatment in order to produce low-molecular alginate. The use of ultrasound significantly reduced viscosity of alginate solutions. Suggested parameters of ultrasound treatment for maximum reduction of alginate molecular weight were: specific intensity, 115.81 $W/cm^2$ at 20kHz frequency; treatment time, 35.55 min; temperature, $20.08^{\circ}C$; alginate concentration, $2.5\%$. Low-molecular alginate obtained by ultrasound had two peaks on Sepharose CL-6B gel filtration. The viscosities of control, fraction I, and fraction II at $0.1\%$ concentration and $25^{\circ}C$ were 3.07, 1.23, and 0.82cps, respectively. Molecular weights of control, fraction I, and fraction II alginates were 336,500, 70,400, and 52,800 daltons, and their solubilities were 3, 6, and $14\%$, respectively. The lower molecular weight of alginate, the lower the alcohol precipitation and the higher $Ca^{2+}$ ion binding capacities. Heavy metal ion binding capacities of alginates were high in the following order of Pb, Cd, Zn, and Co.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.107-114
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• 2014

This paper applies a compensated low pass filter (LPF) to current measurements for permanent magnet synchronous motor (PMSM) drives. The noise limits the bandwidth of current controllers and has more adverse influences on control performances under the light load condition because of the low signal-to-noise ratio. In order to eliminate the noise sensitivity, this paper proposes a digital LPF with a compensator of gain attenuation and phase delay which are unacceptable in current information for PMSM drives. Characteristics of the proposed LPF are analyzed in comparison with the general LPFs. The compensated LPF is basically designed by the orthogonal property of the measured currents in the ${\alpha}{\beta}$ stationary reference frame. In addition, an implementation issue of the proposed method is discussed. Experimental results using the proposed method show improvements of the current control performance from two perspectives, rapid step responses and reductions of harmonic distortion.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.8 no.2
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• pp.39-49
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• 2004

Model of the novel Surface motor (SFM) is briefly discussed, and two types of control method including two-order feedback circuit control, indirect acceleration feedback control are analyzed to solve unstable characteristic such as low damp and negative stiffness. The simulation results demonstrate that the system has plain amplitude and wide frequency band arranging from 0 to 8kHz with no resonant peak through indirect acceleration feedback control.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.69-78
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• 1999

The attitude determination system is indispensable for navigation, guidance and control tasks. In order to construct this system some special products that use dual frequencies or have on receiver engine with multiple antennas are used. But they are so expensive. Thus there are still strong requirements for the conventional low cost single frequency off-the-shelf receiver. This paper will propose a new technique to resolve integer ambiguity with single frequency GPS receiver and will show the problems of the attitude applications in which low cost receiver are being used. Also, based on this new technique precise attitude determination is presented.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.5
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• pp.462-466
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• 2007

This paper proposes an automatic bandwidth control method for the performance improvement of Binary Amplitude Shift Keying (BASK) system for Giga-Bit Modem in millimeter band. In order to improve the performance of the BASK system with a fixed bandwidth, the proposed method is to adjust a bandwidth of low pass filter in receiver using the fuzzy system. The BASK system consists of a high speed shutter of the transmitter and a counter and a repeater of receiver. The repeater consists of four stage converters, and a converter is constructed with a low pass filter and a limiter. The inputs to the fuzzy system are the reminder and integral of remainder of counter, and output is a bandwidth. We used a Viterbi algorithm to find the optimum detection from the output of the counter. Simulation results showed that the proposed system improves the performance compared to the fixed bandwidth.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.99.4-99
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• 2001

PMAC(Permanent magnet AC) motor drives are widely used in the industrial applications and home appliances because of high torque ratio, high efficiency and precise control performance. In recent years there has been a significant development of PMAC motors of various kinds. Improvements in the properties of permanent magnet materials have increased the viability of related types of motors. However, precise speed and position information is essential for the good control performance. In order to produce correct torque, the rotor flux position information from position sensor has to be identified. In this paper, a low cost position sensor is proposed for improving of starting and low speed performance of PMAC. The proposed position ...

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.2
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• pp.133-139
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• 2007

An unmanned ground vehicle can perform its mission automatically without human control in unknown environment. To move up to a destination in various surrounding situation, navigational information is indispensible. In order to be adopted for an unmanned vehicle, the navigation box is small, light weight and low power consumption. This paper suggests navigation system using a low grade MEMS IMU for supplying position, velocity, and attitude of an unmanned ground vehicle. This system consists of low cost and light weight MEMS sensors and a GPS receiver to meet unmanned vehicle requirements. The sensors are basically integrated by loosely coupled method using Kalman filter and internal algorithms are divided into initial alignment, sensor error compensation, and complex navigation algorithm. The performance of the designed navigation system has been analyzed by real time field test and compared to commercial tactical grade GPS/INS system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.625-629
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• 2014

In this paper, a tile projector for the active control of low-frequency underwater echoes is studied using finite element method. Compared to the existing underwater actuators used for echo reduction, the tile projector is better suited for covering a wide area such as the hull of a submarine. In order to actively match the acoustic impedance at the water-object interface, the projector is driven to radiate a pressure wave that is the inverted replica of the echo at the interface. Finite element simulations demonstrate significant echo reductions due to the active impedance matching by the tile projector.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.848-850
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• 1997

A control method of UPFC (Unified Power Flow Controller) to reduce low frequency oscillation is proposed. UPFC is modelled by voltage source, which magnitude and phase angle can be controlled. Because there needs some time to change to desired value, d-axis voltage and Q-axis voltage is modeled by 1st order delay. LQG(Linear Quadratic Gaussian) is used. It is shown that low frequency can be damped by control of UPFC effectively.

• The Korean Journal of Food And Nutrition
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• v.30 no.3
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• pp.552-559
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• 2017

This research investigated quality characteristic and sensual characteristic of Chilhyanggye recipe comparing to general Samgyetang, through restoring the recipe recorded in old documents. pH appeared 6.60, high in control group, while Ungchu and Baekssemi Samgyetang displayed respectively 6.42, 6.41, no significant difference from control group, however Ungchu and Baekssemi chilhyanggye displayed 5.89, 5.90, significantly low. Brightness of breast appeared significantly high in Baekssemi Samgyetang however reddishiness appeared high in Ungchu Chilhyanggye, while yellowishness appeared high in Baekssemi Chilhyanggye compared to other groups. Brightness of chicken leg appeared highest in Baekssemi Chilhyanggye, significantly higher than other groups (p<0.05). Reddishness appeared higher in control group, however appeared low in Samgyetang. Brightness value of soup appeared very high in control group, Ungchu, and Baekssemi Chilhyanggye, which seems to be due to difference in chicken recipe. In case of reddishness, Ungchu Chilhyanggye appeared the highest, and significantly high in order of Baekssemi Chilhyanggye, Baekssemi Samgyetang (p<0.05). Yellowishness appeared significantly high in control group (p<0.05). Hardness of intensity of breast appeared highest in Ungchu Samgyetang and Ungchu Chilhyanggye, and in order of Baekssemi Samgyetang, Baekssemi Chilhyanggye, which seems to be the result of diversity of breed and using vinegar in recipe. Investigation of preference appeared significantly high in color, fragrance, taste, and overall preference in Ungchu and Baekssemi Chilhyanggye compared to control group and Samgyetang (p<0.001). Ungchu Chilhyanggyetang appeared significantly high in overall preference (p<0.001). Calorie appeared higher in Baekssemi compared to Ungchu, while Samgyetang displayed higher value than Chilhyanggye. Carbohydrate appeared higher in Samgyetang than Chilhyanggye. Crude protein content appeared higher in Ungchu breed than Baekssemi breed, on the contrary, crude fat appeared low. Saturated fat and cholesterol apepared lower in Ungchu than Baekssemi.