• Journal of Convergence for Information Technology
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• 제11권6호
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• pp.1-6
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• 2021

In the field of speech recognition, as the DNN is applied, the use of speech recognition is increasing, but the amount of calculation for parallel training needs to be larger than that of the conventional GMM, and if the amount of data is small, overfitting occurs. To solve this problem, we propose an efficient method for robust voice feature extraction and voice signal noise removal even when the amount of data is small. Speech feature extraction efficiently extracts speech energy by applying the difference in frame energy for speech and the zero-crossing ratio and level-crossing ratio that are affected by the speech signal. In addition, in order to remove noise, the noise of the speech signal is removed by removing the noise of the speech signal with an average predictive improved LMS filter with little loss of speech information while maintaining the intrinsic characteristics of speech in detection of the speech signal. The improved LMS filter uses a method of processing noise on the input speech signal by adjusting the active parameter threshold for the input signal. As a result of comparing the method proposed in this paper with the conventional frame energy method, it was confirmed that the error rate at the start point of speech is 7% and the error rate at the end point is improved by 11%.

• Journal of the Korean Institute of Gas
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• 제26권5호
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• pp.1-9
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• 2022

Selection of a suitable artificial lift is important in terms of efficient operation and economics for oil production. In general, process of well design includes the selection of artificial lift, but the oil recovery could be enhanced by use of hybrid system combined with two types of artificial lift method according to reservoir condition for oil production. Electric submersible pump (ESP), as a presentative artificial lift method, is a manner for supplying the pressure in the lower part of oil well by using of a multi-stage centrifugal pump with an electric energy. However, there is a disadvantage that has a limit to the application period because of mechanical defection on ESP. Accordingly, it is possible to reduce the shutdown time of production well by applying the ESP/Gas lift hybrid system, which is to switch to a gas lift when an ESP is defective. This study describes the effect of ESP/gas lift hybrid system compared with ESP method for a onshore horizontal well locating in the of Permian basin, USA. As a result of study, ESP/gas lift hybrid system could make more effective productivity than ESP method. Also, we quantitatively predicted how much economic benefit would be obtained when the hybrid system was applied in the production well.

• KSBB Journal
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• 제23권4호
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• pp.281-284
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• 2008

A simple and efficient microwave-assisted extraction procedure was developed and optimized for the extraction of paclitaxel from the plant cell cultures of Taxus chinensis. The biomass, immersed in a methanol-water mixture, was irradiated with microwaves in a closed-vessel system. The microwave-assisted extraction was compared with the existing conventional solvent extraction in terms of yield, extraction time, and solvent consumption. The use of microwave energy allows rapid recovery of paclitaxel from biomass and dramatically reduces extraction time and solvent usage compared to conventional solvent extraction. The paclitaxel was completely extracted from biomass by microwave-assisted extraction for 3 min at $50^{\circ}C$, for 6 min at $30^{\circ}C$ and $40^{\circ}C$, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제14권3호
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• pp.774-780
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• 2010

USN(Ubiquitous Sensor Network) is a core infrastructure that u-life use to enable the realization in the ubiquitous society through various services of area such as u-city, u-Health. Therefore, we need a research for domestic standards to establish USN technique. Currently, status of USN standards is most standard and research that it is a technology for sensor node implementation and a protocol for energy-efficient communication and interlock with existing network. But, Standard and research for sensor network and integration management of heterogeneous sensor networks for USN application and sensing data management and USN database structure definition such as application and middleware is weak level. In this paper, we researched for standard development of domestic a sensor network and the relevant standard analysis to configure SWE(Sensor Web Enablement) of OGC(Open Geospatial Consortium) for standarded plattform technology. Also we researched that it's a connection between domestic ITA(Telecommunications Technology Association) standards and SWE Standard.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제10권1호
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• pp.57-64
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• 2006

Multiprocessor system on chip (MPSoC) platforms has set a new innovative trend for the SoC design. Quality of service parameters and performance matrix are leading to the adoption of new design methodology for SoC, which will incorporate highly scalable, reusable, predictable, cost and energy efficient platform not only for underlying communication backbone but also for the entire system architecture of NOC. Like the layered architecture for the communication backbone of NOC, we have proposed the entire system architecture for NOC to be a seven layered architecture in itself. Such a platform can separate the domain specific issues which will model concurrency along with the synchronization issues more effectively. For such a layered architecture, model of computation will provide a framework to that can model concurrency and synchronization issues which are natural for any application. Therefore it becomes extremely important to use a right computation model in a specific NOC region.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제37권7호
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• pp.921-927
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• 2013

The performance estimation of a landing gear with uncertain parameters is presented. In actual use, many parameters can have certain degrees of variations that affect the energy absorbing performance. For example, the shock strut gas pressure, oil volume, tire pressure, and temperature can deviate from their nominal values. The objective function in this study is the ground reaction during touchdown, which is a function of the abovementioned parameters and time. To consider the uncertain properties, convex modeling and interval analysis are used to calculatethe objective function. The numerical results show that the ground reaction characteristics are quite different from those of the deterministic method. The peak load, which affects the efficiency and structural integrity, is increases considerably when the uncertainties are considered. Therefore, it is important to consider the uncertainties, and the proposed methodology can serve as an efficient method to estimate the effect of such uncertainties.

• Journal of Biosystems Engineering
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• 제15권1호
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• pp.14-22
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• 1990

For efficient use of solar energy in plastic greenhouse, thermal storage system was developed. The system was constructed with the counter-flow type air-water heat exchanger using a thin polyethylene film as a medium of heat exchange parts. Experiments were carried out to investigate the heat exchange rate, optimum water flow rate, overall heat transfer coefficient, and the effectiveness of the counter-flow type air-water heat exchanger with polyethylene film bags. Mathematical model to predict air temperature leaving heat exchanger was developed. The results obtained in the present study are summarized as follows. 1. Heat exchange rate in the counter-flow type air-water heat exchanger with polyethylene film bags was compared to that of polyethylene film. Heat exchange rate was almost identical at air velocity of 0.5m/s on polyethylene film surface. But, heat exchange rate of heat exchanger with polyethylene film bag was $32{\sim}55KJ/m^2$ hr higher than that of polyethylene film at air velocity of 1.0m/s. 2. Considering the formation of uniform water film and the sufficient heat exchange rate of polyethylene film bags, optimum water flow rate in polyethylene film bags was $3.0{\sim}6.0{\ell}/m^2$ min. 3. The overall heat transfer coefficient of polyethylene film bags was found to be $35.0{\sim}130.0KJ/m^2\;hr\;^{\circ}C$ corresponding to the air velocity ranging 0.5 to 4.0 m/s on polyethylene film surface. And the overall heat transfer coefficient showed almost linearly increasing tendency to the variation of air velocity. 4. Mathematical model to predict air temperature leaving the heat exchanger was developed, resulting in a good agreement between the experimental and predicted values. But, the experimental results were a little lower than predicted. 5. Effectiveness of heat exchanger for the experiment was found to be 0.40~0.81 corresponding to the number of transfer units due to the variation of air velocity ranging 0.6 to 1.7 m/s.

• Applied Chemistry for Engineering
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• 제26권3호
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• pp.247-250
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• 2015

Organic light-emitting diode (OLED) research field has received great attention from academic and industrial circles. Recently, The technical feature of OLEDs is more and more attractive in the lighting market, including area emission characteristics different from other existing light sources. Features are environmentally friendly and efficient use of energy, large area, ultra-light weight, and ultrathin shape, etc. Furthermore, OLED light became the mainstream of next-generation lighting to replace the light emitting diode (LED) fluorescent light. This article summarizes phosphorescent emitting materials that have been applied to white OLEDs. In particular, the chemical structures and device performances of the important yellow, orange, and red phosphorescent emitting materials is discussed. Systematic classification and understanding of the phosphorescent materials can aid the development of new light-emitting materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제13권2호
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• pp.760-771
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• 2012

In this paper, a blind spot of motor car, and the put case that is driven the miniature model motor system, when make practical application of the permanent magnet synchronous motors(PMSM) braking and having had the ability that can all absorb regenerative power by means of electric brake which is occurred. a tow system of a miniature model motor traction system is established by 1C1M methods to control individually permanent magnet synchronous motors (PMSM) of each motor. vector control method is applied in order to improve ride quality of motor car and the efficient use of energy. it was obtained excellent experiment results from the simulations as a function of momentum load and miniature model. Also, this study is investigated the regenerative braking power securities of permanent magnet synchronous motors, speed detection to stop electric brake at extremely very low speed and motor control method of algorithm.

• Journal of the Institute of Electronics Engineers of Korea SP
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• 제41권3호
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• pp.209-219
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• 2004

In order to implement a real time hardware for keyword spotting, we propose a Single-End-Point DTW(SEP-DTW) algorithm which is simple and less complex for computation. The SEP-DTW algorithm only needs a single end point which enables efficient applications, and it has a small wont of computations because the global search area is divided into successive local search areas. Also, we adopt new local constraints and a new distance measure for a better performance of the SEP-DTW algorithm. Besides, we make a normalization of feature same vectors so that they have the same variance in each frequency bin, and each frame has the same energy levels. To construct several reference patterns for each keyword, we use a clustering algorithm for all training patterns, and mean vectors in every cluster are taken as reference patterns. In order to detect a key word for input streams of speech, we measure the distances between reference patterns and input pattern, and we make a decision whether the distances are smaller than a pre-defined threshold value. With isolated speech recognition and keyword spotting experiments, we verify that the proposed algorithm has a better performance than other methods.