• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.5
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• pp.385-393
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• 2004

This paper proposes a swing-arm type dual-stage actuator, which consists of a PZT actuator for fine motion and a VCM(voice coil motor) for coarse motion, for an SFF ODD(small form factor optical disk drive), in order to achieve fast access speed and precise track-following control. Over the past few decades there have been a lot of researches related to the VCM and dual-stage actuator. In this paper, we focus our attention on the design and control of the PZT actuator. Due to the dual cantilever structure. the PZT actuator can generate precise translational tracking motion at its tip to which an optical pickup is attached. and the effect of hysteric behavior of the PZT element is reduced. The dynamic model of the PZT actuator is derived by using the Hamilton's principle, and verified by comparing it with the experimental frequency response. The sliding mode control is designed in order to be robust against modeling uncertainties. Simulations and experimental results confirm the effectiveness of the suggested control scheme.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.204-215
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• 2020

People who have sleep disorders such as insomnia take a long time to get to sleep, namely sleep latency. In order to reduce it, effective stimulations and environments to induce sleep such as ASMR or pink noise are necessary. However these have different effects and preferences for each individual. Therefore customized service and control for the sleep induction will be provide to him/her. In this paper, we proposed SIS control system which provides selectively sound control among various kinds of ASMR and pink noise according to sleep state measured from brain wave data for an individual. In order to verify the effectiveness of the system, we had conducted totally 30 experiments for 5 people, and all EEG data measured from all the people during sleep. An average of 3.7 hours was spent per experiment. In comparison experiments with and without sound control for sleep induction, the latency time was reduced by an average of 8 minutes as well as delta waves and theta waves, which appear only in deep sleep, are increased by 21%.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1223-1230
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• 2017

The back emf harmonics of a permanent magnet (PM) synchronous motor is a major source of torque ripple. For torque control applications including column fitted MDPS (motor driven power steering) systems, it is essential to reduce the mechanical vibrations due to torque ripples at low speeds. In this paper, a torque ripple reduction algorithm for interior PM synchronous motors is proposed. The harmonic currents that cancel the $6^{th}$ order torque harmonic are added to the nominal dq currents for MTPA (maximum torque per ampere) operation. The compensated harmonic currents are derived from flux linkage harmonics based on a FFT analysis of the back emf harmonics. Simulation and experimental results verify that the $6^{th}$ order torque harmonic and THD of the torque ripple are reduced by compensating the dq harmonic currents.

• Journal of Power Electronics
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• v.13 no.1
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• pp.122-138
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• 2013

Adaptive control of a peak current mode controlled (PCM) boost converter supplied by a PEM fuel cell is described in this paper. The adaptive controller with reference model and signal adaptation is developed in order to compensate the deviation of the response during the change of the operating point. The procedure for determining the adaptive algorithm's weighting coefficients, based on a combination of the pole-zero placement method and an optimization method is proposed. After applying the proposed procedure, the optimal adaptive algorithm's weighting coefficients can be determined in just a few iterations, without the use of a computer, thus greatly facilitating the application of the algorithm in real systems. Simulation and experimental results show that the dynamic behavior of a highly nonlinear control system with a fuel cell and a PCM boost converter, can fairly accurately be described by the dynamic behavior of the reference model, i.e., a linear system with constant parameters.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.891-894
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• 1993

To improve limitations of fuzzy PI controller especially when applied to high order systems, we propose two types of fuzzy logic controllers that take out appropriate amounts of accumulated control input according to fuzzily described situations in addition to the incremental control input calculated by conventional fuzzy PI controllers. The structures of the proposed controller were motivated by the problems of fuzzy PI controllers that they generally give inevitable overshoot when one tries to reduce rise time of response especially when one tries to reduce rise time of response especially when a system of order higher than one is under consideration. Since the undesirable characteristics of the fuzzy PI controller are caused by integrating operation of the controller, even though the integrator itself is introduced to overcome steady state error in response, we propose two fuzzy controllers that fuzzily clear out integrated quantities according to situation. The first contr ller determines the fuzzy resetting rate by situations described fuzzily by error and error rate, and the second one by error and control input. The two structures both give reduced rise time as well as small overshoot. To show the usefulness of the proposed controller, that are applied to systems that are difficult to get satisfactory response by conventional fuzzy PI controllers.

• Plant Journal
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• v.17 no.1
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• pp.38-49
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• 2021

In order to increase power plant efficiency, the steam temperature was increased to 610 ℃ which deteriorates the durability of the boiler tube and as the use of low-calorie coal increases the post combustion and delayed combustion phenomenon, the overheating of the final reheater and the tube rupture are becoming frequent. In order to prevent overheating of the final reheater, desuperheater water injection was increased, leading to a decrease in boiler efficiency. In this study install a baffle plate at the back of some overheated tube groups, thereby reduce the temperature of the tube by reducing the amount of combustion gas, and the reduced combustion gas moves to an adjacent place to increase the temperature of other tubes. As a result of the study, the temperature deviation between tubes decreased 1.5. And the heat-reducing injection amount was reduced to 6,929 kg/h and the maximum tube temperature was reduced to 623.4℃ which is 6.6℃ more below than the control standard of 630℃.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.1
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• pp.42-48
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• 2009

An in vitro incubation study was conducted to investigate effects of 2-bromoethanesulfonic acid (BES) on ruminal fermentation characteristics and methanogen population. BES at the final concentration of 0, 1 and 5 mM with two different substrates having a different ratio of timothy and concentrate (100% timothy vs. 40% timothy-60% concentrate) was incubated for 0, 24, 48 and 72 h in a $39^{\circ}C$ incubator. Total DNA extracted from culture fluid was used as a template for real-time PCR to measure the population of methanogens. Four different primer sets were used for amplification of total bacteria, total methanogens, the order Methanobacteriales and the order Methanomicrobiales. BES reduced (p<0.01) total gas and methane production in a dose-dependent manner. BES at 5 mM inhibited methane production by more than 95% compared to the control. An interaction between substrate and level of BES in total gas and methane was detected (p<0.01). The decrease of methane production with increasing BES level was more pronounced on mixed substrate than on timothy alone. However, hydrogen production was increased by BES treatment (p<0.01). Total VFA concentration was not affected, but molar percentage of propionate and butyrate was increased and acetate to propionate ratio was reduced by BES treatment (p<0.01). BES did not affect the population density of total bacteria but reduced (p<0.01) the population of total methanogens, the order Methanobacteriales and the order Methanomicrobiales in a dose-dependent manner. The type of substrate did not influence the trend, although the magnitude of response was different between all-roughage and 40% roughage substrate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.942-946
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• 2009

A scan order converter has to be placed before the JPEG encoder to provide $8{\times}8$ blocks from the pixels in raster scan order. Recently a hardware architecture has been proposed to implement a scan converter based on the single line memory. Since both read and write accesses happen at each cycle, however, the largest part of the entire power budget is occupied by the SRAM itself. In this paper, the data packing and unpacking procedure is inserted in the processing chain, such that the access frequency to the SRAM is reduced to 1/8 by adopting a packed larger data unit. The simulation results show that the resultant power consumption is reduced down to 16% for the SXGA resolution.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.137-145
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• 2023

In this paper, we propose system access control software that improves the survivability of the naval combat system while maintaining security and stability. The software was improved by improving the operating environment configuration and user authentication process of the system access control software that constitutes the naval combat system, defining the operating environment classification of the naval combat system, and applying a software parallel execution process considering the load rate. Through this, the waiting time required to configure the environment is shortened, providing rapid operation to the operator, and improving the fact that the naval combat system cannot be operated unless the environment configuration is completed even in emergency situations. In order to test the performance, a test environment was created by simulating the existing naval combat system, and the execution time for each operation category was measured and compared. Compared to the existing naval combat system, the execution time of the basic combat system was reduced by about 69.3%, the execution time of the combat system was reduced by about 54.9%, and the execution time of the integrated combat system was confirmed to be reduced by about 8.4%.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.92.1-92
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• 2003

In order to develop an effective spray program for control of apple white rot with reduced use of fungicides, the control efficacy of several fungicides that has been intensively used for control of the disease was assessed. They were sprayed on the same tree with 15 day interval from late May to early August. Just prior to and after each spray, 100 fruits were bagged with two layered fruit bag to limit the chemical application in only one time, and the disease incidence and latent infection frequency on the bagged apples were examined. Some fungicides such as folpet, iminoctadine-triacetate and azoxystrobin showed a high post-infectional activity even though the former two are non- systemic. Folpet suppressed symptom development, iminoctadine-triacetate reduced infection frequency and azoxystrobin acted in both ways. When those fungicides were ！！ adopted in a spray program, once in a cropping season, their post-infectional activity became much greater. This activity shown by the non-systemic fungicides was supposed to be derived from the peculiar infection process of the white rot fungus of which the pathogen is usually remain latent in the corked cells of lenticel until the apple reach mature stage.