• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.10a
• /
• pp.176-179
• /
• 2000

The PLL synthesizer is used often in communication system due to several merits, such as broad bandwidth, high accuracy and stability of frequency. But it is difficult to use in current digital communication systems that need frequency hopping at a high speed because of its long frequency hopping time. In this paper, we designed frequency synthesizer that generate the clock frequency randomly at a high speed using the DDS technology and is applied to the pattern generator systemfor for digital image.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.3B
• /
• pp.91-98
• /
• 1999

In order to reject the steady-state tracking error, it is common to introduce integral compensators in servosystems for constant reference signals. However, if the mathematical model of the plant is exact and no disturbance input exists, the integral compensation is not necessary. From this point of view, a two-degree-of-freedom(2DOF) servosystem has been proposed, in which the integral compensation is effective only when there is a modeling error or a disturbance input. The present paper considers a synthesis problems of this 32DOF servosystem with direct transfer term in the system representation. And, a method how we may obtain a gain such that desirable transient response is achieved, is proposed in the presence of the modelling error and disturbance input.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.4
• /
• pp.18-23
• /
• 1998

Approximations inherent in the Cohn synthesis theory, which is generally perferree as a convinient design technique for direct-couple waveguide filter, results in considerable devications from the required responses as the design bandwidth increases. In this paper, two main deviations likely to occur in practice are examined using the mode-matching technique. They are a shift in couoff frquencies and large return loss occuring near coutoff frequencyles. Using the power loss ratio, the first effect is corrected to the resulant filter structure from cohn synthesis. In order to show the validity of the intorduced approackes. Ka-band waveguide filter ahs been designed and manufactored. The experimental curve follow the expected curves after corrections fairly closly.

• Journal of the Korean Ceramic Society
• /
• v.23 no.1
• /
• pp.27-32
• /
• 1986

This study is aimed at synthsizing high dielectric material (Ba, Sr)$TiO_3$ through direct wet process. Pure and ultra fine particle of (Ba, Sr)$TiO_3$ Powder was synthesized from $BaCl_2$ $SrCl_2$ and TiCl4 aqeous solution at KOH Solution in the $N_2$ gas atmosphere. $BaCl_2$ $SrCl_2$ and TiCl4 were Mixed with the mole ratio of 1:9, 3:7:10, 5:5:10, 7:3:10, 9:1:10 and sythesized at 4$0^{\circ}C$~9$0^{\circ}C$ for 10min~15hrs. The particle size particle shape crystallinity and synthesis condition of (Ba, Sr)$TiO_3$ powder with the variation of temperature and reaction time in the aqueous solution studied by the exprimental instruments of DTA. TGA, X-ray diffratometer SEM.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.443-447
• /
• 2001

The PLL synthesizer is used often in communication system due to several merits, such as broad bandwidth, high accuracy and stability of frequency. But it is difficult to use in torrent digital communication systems that need frequency hopping at a high speed because of its long frequency hopping time. In this paper, we designed frequency synthesizer that generate the clock frequency randomly at a high speed using the DDS technology and is applied to the pattern generator system for digital image.

• Textile Coloration and Finishing
• /
• v.13 no.2
• /
• pp.1-1
• /
• 2001

In the Previous studies, we reported about the synthesis of poly[3-methylence-3-methylenesodiumbisulfite-bis(4-hydroxypheny)sulfone] (PMSBPS) and their effect on the staining of direct dye on nylon in the dyeing of nylon/cotton union. The results showed that PMSBPS have good staining resist effect on nylon in the dyeing of nylon/cotton union. In this study, the staining resist effects of PMSBPS in varied dyeing process and method were investigated, and the fastness to washing, light, and rubbing of the deed N/C unions was tested. The results are as follows ; 1. In the two bath two step method, the staining of direct dye on nylon was decreased with the concentration of PMSBPS, and the fastness to washing, light, and rubbing of the dyed N/C unions were increased by addition of PMSBPS. 2. In the one bath two step method, optimun concentration of PMSBPS was 4% 0.w.f..

• Textile Coloration and Finishing
• /
• v.13 no.2
• /
• pp.87-92
• /
• 2001

In the Previous studies, we reported about the synthesis of poly(3-methylence-3-methylenesodiumbisulfite-bis(4-hydroxypheny )sulfone] (PMSBPS ) and their effect on the staining of direct dye on nylon in the dyeing of nylon/cotton union. The results shoved that PMSBPS have good staining resist effect on nylon in the dyeing of nylon/cotton union. In this study, the staining resist effects of PMSBPS in varied dyeing process and method were investigated, and the fastness to washing, light, and rubbing of the deed N/C unions was tested. The results are as follows , 1. In the two bath two step method, the staining of direct dye on nylon was decreased with the concentration of PMSBPS, and the fastness to washing, light, and rubbing of the dyed N/C unions were increased by addition of PMSBPS. 2. In the one bath two step method, optimun concentration of PMSBPS was 4% 0.w.f..

• Bulletin of the Korean Chemical Society
• /
• v.30 no.3
• /
• pp.683-686
• /
• 2009

Slurry phase reaction of elemental silicon with methanol has been studied in the presence of copper using a small amount of cuprous chloride as an activator in DBT (dibenzyltoluene) at various temperatures from 200 ${^{\circ}C}$ to 320 ${^{\circ}C}$. Trimethoxysilane (1a) with a Si-H unit was obtained as the major product and tetramethoxysilane (1b) as the minor product. The reaction worked well using a 0.5 wt % CuCl as an activator. The optimum temperature for this direct synthesis of 1a was 240 ${^{\circ}C}$. Methoxysilanes were obtained in 95% yield with 81% selectivity to 1a from 85% conversion of elemental silicon.

• International Journal of Computer Science & Network Security
• /
• v.21 no.8
• /
• pp.212-218
• /
• 2021

The Proportional Integral Derivative (PID) controller is the most popular industrial controller and more than 90% process industries use this controller. During the past 50 years, numerous good tuning methods have been proposed for Single Input Single Output Systems. However, design of PI/PID controllers for multivariable processes is a challenge for the researchers. A comparative study of three PID controllers design methods has been carried-out. These methods include the DS (Direct Synthesis) method, IMC (Internal model Control) method and ETF (Effective Transfer Function) method. MIMO PID controllers are designed for a number of 2×2, 3×3 and 4×4 process models with multiple delays. The performance of the three methods has been evaluated through simulation studies in Matlab/Simulink environment. After extensive simulation studies, it is found that the Effective Transfer Function (ETF) Method produces better output responses among two methods. In this work, only decentralized methods of PID controllers have been studied and investigated.

• International Journal of Computer Science & Network Security
• /
• v.21 no.9
• /
• pp.11-18
• /
• 2021

The Proportional Integral Derivative (PID) controller is the most popular industrial controller and more than 90% process industries use this controller. During the past 50 years, numerous good tuning methods have been proposed for Single Input Single Output Systems. However, design of PI/PID controllers for multivariable processes is a challenge for the researchers. A comparative study of three PID controllers design methods has been carried-out. These methods include the DS (Direct Synthesis) method, IMC (Internal model Control) method and ETF (Effective Transfer Function) method. MIMO PID controllers are designed for a number of 2×2, 3×3 and 4×4 process models with multiple delays. The performance of the three methods has been evaluated through simulation studies in Matlab/Simulink environment. After extensive simulation studies, it is found that the Effective Transfer Function (ETF) Method produces better output responses among two methods. In this work, only decentralized methods of PID controllers have been studied and investigated.