• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.247-255
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• 2005

ice yield and plant growth response to nitrogen (N) fertilizer may vary within a field, probably due to spatially variable soil conditions. An experiment designed for studying the response of rice yield to different rates of N in combination with variable soil conditions was carried out at a field where spatial variation in soil properties, plant growth, and yield across the field was documented from our previous studies for two years. The field with area of 6,600 m2 was divided into six strips running east-west so that variable soil conditions could be included in each strip. Each strip was subjected to different N application level (six levels from 0 to 165kg/ha), and schematically divided into 12 grids $(10m \times10m\;for\;each\;grid)$ for sampling and measurement of plant growth and rice grain yield. Most of plant growth parameters and rice yield showed high variations even at the same N fertilizer level due to the spatially variable soil condition. However, the maximum plant growth and yield response to N fertilizer rate that was analyzed using boundary line analysis followed the Mitcherlich equation (negative exponential function), approaching a maximum value with increasing N fertilizer rate. Assuming the obtainable maximum rice yield is constrained by a limiting soil property, the following model to predict rice grain yield was obtained: $Y=10765{1-0.4704^*EXP(-0.0117^*FN)}^*MIN(I-{clay},\;I_{om},\;I_{cec},\;I_{TN},\; I_{Si})$ where FN is N fertilizer rate (kg/ha), I is index for subscripted soil properties, and MIN is an operator for selecting the minimum value. The observed and predicted yield was well fitted to 1:1 line (Y=X) with determination coefficient of 0.564. As this result was obtained in a very limited condition and did not explain the yield variability so high, this result may not be applied to practical N management. However, this approach has potential for quantifying the grain yield response to N fertilizer rate under variable soil conditions and formulating the site-specific N prescription for the management of spatial yield variability in a field if sufficient data set is acquired for boundary line analysis.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.186-192
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• 2011

Recently, due to the expansion of electric power demands, nonlinear load such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electric devices, disturbance of the electric power system and its influences on industries have been continuously increasing. In this research, we develop a novel aggregation algorithm by considering the harmonics characteristics for residential loads. Using data sets acquired from various experiments, we analyzed load characteristics according to harmonics and presented the results obtained the proposed method.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.1
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• pp.42-54
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• 2001

The use of nitrogen fertilizer in intensive agricultural production is of major concern due to its role on agricultural productivity and water quality. Crop production inputs on farm are usually applied at a uniform rate across an entire field. However, actual input requirements often vary within fields. The field variations in yield potential, soil moisture, soil N status, and the efficiency of fertilizer use, uniform application of crop production inputs does not allow optimum efficiency or profitability. This occurs because uniform application often results in areas of over- and under-application which may affect water quality and crop yield. This study used biophysical and economic models to assess the economic feasibility and water quality benefits of site specific nitrogen management for 10 soil types and 35 sample fields in Goodwater Creek watershed located near Centralia, Missouri. Results showed that the economic feasibility and water quality benefits of variable rate application were sensitive to the distribution of soil types within a field. Variable rate(VR) application was not uniformly more profitable than uniform rate(UR) application for the four agricultural systems evaluated and the water quality benefits were insubstantial relative to uniform application of N.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.962-977
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• 2019

The human voice is a convenient method of information transfer between different objects such as between men, men and machine, between machines. The development of information and communication technology, the voice has been able to transfer farther than before. The way to communicate, it is to convert the voice to another form, transmit it, and then reconvert it back to sound. In such a communication process, a vocoder is a method of converting and re-converting a voice and sound. The CELP (Code-Excited Linear Prediction) type vocoder, one of the voice codecs, is adapted as a standard codec since it provides high quality sound even though its transmission speed is relatively low. The EVRC (Enhanced Variable Rate CODEC) and QCELP (Qualcomm Code-Excited Linear Prediction), variable bit rate vocoders, are used for mobile phones in 3G environment. For the real-time implementation of a vocoder, the reduction of sound quality is a typical problem. To improve the sound quality, that is important to know the size and shape of noise. In the existing sound quality improvement method, the voice activated is detected or used, or statistical methods are used by the large mount of data. However, there is a disadvantage in that no noise can be detected, when there is a continuous signal or when a change in noise is large.This paper focused on finding a better way to decrease the reduction of sound quality in lower bit transmission environments. Based on simulation results, this study proposed a preprocessor application that estimates the SNR (Signal to Noise Ratio) using the spectral SNR estimation method. The SNR estimation method adopted the IMBE (Improved Multi-Band Excitation) instead of using the SNR, which is a continuous speech signal. Finally, this application improves the quality of the vocoder by enhancing sound quality adaptively.

• The Journal of the Acoustical Society of Korea
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• v.28 no.8
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• pp.815-821
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• 2009

Information processing in variable and noisy environments is usually accomplished by means of adaptive filters. Among various adaptive algorithms, Least Mean Square (LMS) has become the most popular for its robustness, good tracking capabilities and simplicity, both in terms of computational load and easiness of implementation. In practical application of the LMS algorithm, the most important key parameter is the Step Size. As is well known, if the Step Size is large, the convergence rate of the algorithm will be rapid, but the steady state mean square error (MSE) will increase. On the other hand, if the Step Size is small, the steady state MSE will be small, but the convergence rate will be slow. Many researches have been proposed to alleviate this drawback by using a variable Step Size. In this paper, a new variable Step Size LMS(VSSLMS) called Categorized VSSLMS (CVSSLMS) is proposed. CVSSLMS updates the Step Size by categorizing the current status of the gradient, hence significantly improves the convergence rate. The performance of the proposed algorithm was verified from the view point of convergence rate, Excessive Mean Square Error(EMSE), and complexity through experiments.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.102-105
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• 1999

AAL type 2 provides for the bandwidth efficient transmission of low bit rate, short and variable packets in delay sensitive application. The service object for these networks ranges from POTS to multimedia conference. In this paper, we present one possible architecture which common part sublayer for new AAL type 2. The proposed CPS function has been achieved with on a FPGA The proposed architecture is faithful to the standardization of ITU-T and ATM-forum recommendation The proposed architecture applies to variable packet length from architecture CODECs for cellular network.. It's maximum process capability is 155Mbps with 256 CIDs. The architecture has sync./async. interface to application block and UTOPIA interface is used for physical layer interface.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.481-482
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• 2007

This paper demonstrates OFDM with adaptive modulation applied to Multiple-Input Multiple-Output (MIMO) systems. We apply an optimization algorithm to obtain a bit and power allocation for each subcarrier assuming instantaneous channel knowledge. The analysis and simulation is considered in two stages. The first stage involves the application of a variable-rate variable-power MQAM technique for a Single-Input Single-Output(SISO) OFDM system. This is compared with the performance of fixed OFDM transmission where a constant rate is applied to each subcarrier. The second stage applies adaptive modulation to a general MIMO system by making use of the Singular Value Decomposition to separate the MIMO channel into parallel subchannels. For a two-input antenna, two-output antenna system, the performance is compared with the performance of a system using selection diversity at the transmitter and maximal ratio combining at the receiver.

• Journal of Digital Contents Society
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• v.16 no.5
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• pp.775-781
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• 2015

EBS started 2HD MMS experimental broadcasting for the first time in Korea on Feb. 11, 2015. It uses the picture compression technique based on MPEG-2 CODEC, and applies the result of the experiment about variable bit rates and changes according to the scanning types, 1080i and 720p. But when changing channels, the delay in displaying picture occurs because of the operation of the variable GOP on MMS broadcasting, which optimizes image quality by application variable bit rates. In this study, verified the relationship between the decoding time of I frames and the GOP set in the encoding step by experimenting and analyzing ON-AIR TS. By using the verification data and adjusts the Encoder GOP parameters, improved the different video display time delays according to the scanning mode 1080i and 720p.

• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.479-484
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• 2003

In the current Internet, it is difficult for an Internet Phone to guarantee the QoS due to variable network conditions such as packet loss rate, delay and bandwidth. In addition, the QoS of an Internet Video Phone is more hard to guarantee because of video data. In this paper, we investigate application-level QoS control schemes that can adapt to variable network conditions, and describe an error control scheme and a congestion control scheme. Based on these QoS control schemes, we have designed and implemented an Internet Video Phone System that supports adaptive audio and video delivery. Through experiments, we found that the Internet Video Phone can reduce the packet loss rate considerably as well as adjust the transmission rate considering other TCP flows.

• KSBB Journal
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• v.26 no.5
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• pp.374-380
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• 2011

Earlier in Korea Kimchi was made in every family and every province has own taste and specialties. These days almost of the Kimchis are manufactured. We collected variable Kimchis, which were made for private use and isolated microorganisms. Some interesting micobial cells were identified and studied for its application as food and drinks. One of them was identified as Lactobacillus sakei KJ123. This strain is known as producing interesting aromatic components during Sakei fermentation like Kimchi in variable conditions. We tried to develop a health beverage with fermentation process. The Cucurbita maxima has been known as a traditional healthy food and variable positive effects on the human body were already reported. In this study we tried to develop a production process for a healthy fermented drink on this substrate with strains originated from Kimchi. Many kinds of lacctobacilli species existed in the fermented food cannot survive in the acidic conditions like human stomach. So we selected resisting strains in this conditions. The survival rate of Lactobacillus sakei cells in the artificial gastric juice and bile acid and other physiological characteristics at the variable conditions have been tested. After fermentation process some sensory tests on the product with panels were tried.