• Microbiology and Biotechnology Letters
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• v.22 no.2
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• pp.217-221
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• 1994

The essential oil of astringent persimmon leaves was extracted by a gas co-distillation method and its effects on Kimchi fermentation were examined. The changes of pH and titratable acidity of Kimchi during fermentation at 15$\circ $C generally decreased by the addition of essential oil of astringent persimmon leaves, and the growth of microorganisms associated with Kimchi fermentation was also inhibited. The fermentation time of Kimchi reaching to the maximum number of cell counts was greatly extended as compared to that of the Kimchi fermented without the addition of essential oil. The greatest antimicrobial activity activity of essential oil of persimmon leaves was shown against Lactobacillus plantarum among varoius bacteria associated with Kimchi fermentation. The antimicrobial activity of essential oil against Saccharomyces cerevisiae was much higher then that against lactic acid bacteria such as L. plantarum.

• Journal of Institute of Convergence Technology
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• v.6 no.2
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• pp.15-20
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• 2016

This paper presents the effects of a virtual mass on the stability boundary of a virtual spring in the haptic system. A haptic system consists of a haptic device, a sampler, a virtual rigid body and zero-order-hold. The virtual rigid body is modeled as a virtual spring and a virtual mass. According to the virtual mass and the sampling time, the stability boundary of the virtual spring is analyzed through the simulation. As the virtual mass increases, the value of the virtual spring to guarantee the stability gradually increases and then decreases after reaching the maximum value. These simulation results show that the addition of the virtual mass enables to expand the stability boundary of the virtual spring.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.60-63
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• 1988

An adaptive model following controller is designed using the theory of variable structure systems. The proposed method allows the designer to satisfy the requirements of short sliding plane reaching time and chattering reduction in the sliding mode. This method is based on the modified condition for the sliding mode. The result of computer simulation shows that state trajectories reach switching plane fast and chattering is reduced.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1856-1857
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• 2006

The existing automation transfer systems such as AGV(Automated Guided Vehicle) have many problems (maintenance, accuracy, velocity, etc.) and wastes of a vast space and time. Hence we have suggested to LMTT(Linear Motor-based Transfer Technology). This paper deals with fundamental LMTT, and proposes a concept of mass reduction and propulsion control for LMTT when it is starting and reaching an object by using lift-force. By applying optimal controller and the repulsive lift forte in the LMTT, a large percent of vehicle weight is compensated and it reduces friction, then it needs less thrust force to propel the vehicle.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.677-680
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• 2004

In the mobile environment, according to the movement of the object, the query finds the nearest special object or place from object position. However, because query object moves continuously in the mobile environment, query demand changes according to the direction attribute of query object. Also, in the case of moving of query object and simply the minimum distance value of query result, sometimes we find the result against the query object direction. Especially, in most road condition, as user has to return after reaching U-turn area, user rather spends time and cost. Therefore, in order to solve those problems, in this paper we propose the nearest neighbor method considering moving object position and direction for mobile recommendation system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.826-828
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• 2015

In this paper, Propose an efficient method that can operate at fixed stations Beam-Steering. Typical Beam-Forming techniques are performed using a delay time between the signal reaching each antenna array. The Beam-Forming method requires a lot of complexity and cost. This paper suggest a Beam-Steering method using a signal-to-noise ratio and a received signal strength. Analyzes the algorithm about proposed method.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.579-582
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• 1999

This paper presents a design method of deadbeat controller for DC motor driving a rotational system with gear. The results of sampling a continuous-data process does not guarantee that no ripples occur between the sampling instants in the continuous-data output, but the proposed deadbeat control system that consists of the integral controller and the full state observer, and zero order hold using in continuous systems, has many advantages of such as an output response without the ripple and reaching the steady state without error after a given sampling period and faster settling time than the optimal control system in the short sampling period. The results of case study through matlab simulation shown that the efficiency of the proposed controller for DC motor driving a rotational system with gear, is verified by comparing with optimal controller etc.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.906-908
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• 1999

In this paper, new sliding mode surfaces are proposed by defining novel virtual states. These sliding surfaces have nominal dynamics of an original system and makes it possible that the Sliding Mode Control(SMC) technique is used with the various types of controllers. Its design is based on the augmented system whose dynamics have m-th higher order than those of the original system where m is the number of inputs. The reaching phase is removed by setting the initial virtual states which makes the initial switching functions equal to zero.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.3
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• pp.250-259
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• 2010

The ability for energy harvesting via the piezoelectric effect was studied for a unimorph element such as piezo buzzer. A simple equivalent circuit was proposed to predict the energy generated based on the internal stress. Unimorphs with a metal-cavity were used as a driving device of the generation panel. Both the AC open voltage and DC output voltage as a function of pressure period and number of element were measured. For the unimorph generation circuit, DC output voltage varies with pressure period, reaching a maximum value at $470{\mu}F$. The maximum output voltage a according to load resistance was measured at $1M{\Omega}$. Data analysis of the DC output voltage and time constant indicated that number of piezoelectric element of optimum was 60~80. It was found that piezoelectric unimorph has the possibility to be used as the driving element of the electric generation.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.261-264
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• 1992

In designing the fuzzy rule-based system, it has effected by the four significant factors such as the choice of membership function, scaling factor, the numbers of fuzzy control rule, the method of defuzzification. In this paper we design the fuzzy rule based system and evaluate by three factors, as followes reaching time, overshoot, and amplitude. And then we wiII show that the significant factors are the choice of scaling factor and the numbers of fuzzy control rule, and the system performance can be improved by the proper selection of the scaling factors.