• 한국통신학회논문지
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• 제29권9B호
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• pp.808-817
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• 2004

최근 Low-Rate WPAN 기술에 관한 많은 연구가 진행되고 있다. Low-Rate WPAN 은 사용자가 실질적으로 인식하지 못하는 상황에서도 주변환경에 존재하는 많은 수의 센서를 통해 컴퓨터를 이용한 개선된 서비스제공에 목적을 두고있다. Low-Rate WPAN 환경을 구성하는 센서 디 B} 이스는 빈번한 이동성을 가지게 되고 새로운 경로 탐색을 위한 메카니즘을 필요로 하게 되므로, 본 논문에서는 센서 디바이스의 위치정보를 이용한 Low-Rate WPAN 환경에서의 효율척언 라우팅 메카니즘을 제안한다. 제안한 메카니즘은 기존 방법들에 비해 라우팅 메시지 수를 감소시킬 수 있음을 시뮬레이션을 통해 입증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2480-2482
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• 1998

In this paper, the implementation of dual rate ADPCM using G.723 16Kbps and 40Kbps speech codec algorithm is handled. For small signals, the low rate 16Kbps coding algorithm shows the same SNR as the high rate 40Kbps coding algorithm, while the low rate 16Kbps coding algorithm shows the lower SNR than the high rate 40Kbps coding algorithm for large signal. To obtain the good trade-off between the data rate and synthesized speech quality, we applied low rate 16Kbps for the small signal and high rate 40Kbps for the large signal. Various threshold values determining the rate are tested for good trade off data rate and speech quality. Also the low pass filter effect of speech input and output devices is simulated at several cut-off frequencies. To simulation result shows the good speech quality at a low rate comparing with 16Kbps & 40Kbps.

• 한국통신학회논문지
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• 제25권5A호
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• pp.726-742
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• 2000

A novel rte control algorithm consisting of two major components, i.e. a variable encoding frame rate method and a hybrid DCT/wavelet I-frame coding scheme, is proposed in this work for low bit rate video coding. Most existing rate control algorithms for low bit rate video focus on bit allocation at the macroblock level under a constant frame rate assumption. The proposed rate control algorithm is able to adjust the encoding frame rate at the expense of tolerable time-delay. Furthermore, an R-D optimized hybrid DCT/wavelet scheme is used for effective I-frame coding. The new rate-control algorithm attempts to achieve a good balance between spatial quality and temporal quality to enhance the overall human perceptual quality at low bit rates. It is demonstrated that the rate control algorithm achieves higher coding efficiency at low bit rates with a low additional computational cost. The variable frame rate method and hybrid I-frame coding scheme are compatible with the bi stream structure of H.263+.

• 대한임베디드공학회논문지
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• 제2권1호
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• pp.24-30
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• 2007

According to development of wireless communication technologies, we need not only high data rate but low data rate system of low power consumption. This low data rate system is utilized in the field of home automation, health care, sensoring and monitoring, etc. IEEE 802.15.4 LR-WPAN system is the best choice for realizing ubiquitous networking system. In this paper SoC Architecture for IEEE 802.15.4 Low Rate WPAN is designed. IEEE 802.15.4 Low Rate WPAN system serves the functions and realization of home area network. We propose the SoC architecture for 868/915MHz frequency band of IEEE 802.15.4 Low Rate WPAN system. The key issue is to design SoC architecture which provides the function of Low Rate WPAN system to meet the requirement of IEEE 802.15.4 standards.

• 대한임상전기생리학회지
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• 제2권2호
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• pp.1-12
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• 2004

The purpose of this study was to determine the effect of muscle fatigue by neuromuscular electrical stimulation(NMES). Using Biodex System 3PRO(Biodex Medical Systems Inc, USA), experiment was conducted as to the normal group(I) composed of fifteen adults and the patient group(II) composed of fifteen patients with spastic hemiplegia. As to each group, maximal tolerated intensity(MTI) and maximal tolerated isometric contraction(MTIC) in electric currents yielded by low rate(20 pps) and high rate(100 pps) neuromuscular electrical stimulation and the aspects of decrease and restoration of the isometric contraction were examined, and their strength decrement index(SDI) and strength recovery index(SRI) were also calculated. 1. As for MTI in NMES, the MTI of the group II was higher than that of the group I in both low rate and high rate NMES. In comparison within group, MTI of group II was significantly higher in high rate NMES rather than in low rate NMES(p<0.05). 2. In comparison of MTIC between groups, the group I showed higher in both low rate and high rate NMES. In comparison within group, MTIC of group II was significantly higher in high rate NMES rather than in low rate NMES(p<0.01). 3. As for SDI, both groups showed highest SDI in high rate NMES, but no significant differences could be observed. 4. As for SRI, both groups showed significantly low SRI in low rate NMES(p<0.01, p<0.05), and comparison between groups showed no significant differences could be observed. These result lead us to the conclusion that muscle fatigue was influenced by frequency, high rate NMES was lower at SDI and higher at SRI on compare to low rate NMES, therefor, a further studies concerning electrical stimulation should consider differences each frequency in response to treatment.

• 대한가정학회지
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• 제43권11호
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• pp.165-183
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• 2005

Total fertility rate in South Korea is the lowest in the world. A fertility rate below replacement fertility level will result in serious social problems in the long term. Therefore, it is worthwhile to study a general understanding about the low fertility rate phenomenon and to investigate the effectiveness of fertility policies in order to ameliorate the resulting social problems due to the low fertility rate. This research was a descriptive examination into the low fertility rate phenomenon and an investigation of the needs for fertility potties and their effectiveness. The study subjects were consisted of 769 unmarried people aged from 18 to 40 years old. Data were collected from June to August 2004 and were analyzed by frequencies, mean, and standard deviation. The following results were revealed. First, unmarried people in general had positive perspectives about getting marriaged, giving birth, and being a parent. In addition, the primary cause of low fertility rate was economical difficulties for raising a child. Third, unmarried people thought that the low fertility rate phenomenon resoled in both positive and negative changes in a society. Fourth, policies for economical supports for raising children, establishing social atmosphere for gender equality, and trustful public educational systems were the political alternatives that people really wanted for having a child in the future. Effective alternatives for policies and strategies to address the low fertility rate problems are suggested in the discussion section.

• Geosystem Engineering
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• 제21권6호
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• pp.344-351
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• 2018

It is reported that the flooding rate in low permeability sandstones is low and the oil recovery is hard to increase after water breakthrough. Understanding characteristics of waterflood is hence important for the recovery improvement. In this work, flooding tests on low permeability sandstones were conducted. The corresponding flooding characteristics were investigated by means of CT scanning and Nuclear Magnetic Resonance. Effects of irreducible water and different rates were also discussed in detail. Experimental results reveal a piston-like displacement at a low rate in low permeability samples. The saturation profile is steep and almost vertical to the forward direction. The results at a low rate confirm that once water broke through, increasing the flooding rate or flooding time can hardly reduce the remaining oil inside the sample. It is probably due to the high pore-throat ratio proven by rate-controlled mercury. Results also confirm that the presence of initial water enhanced sweep efficiency substantially. On one hand, because water had previously occupied the small pores, the subsequent oil can only invade relatively large pores and became more movable. On the other hand, stable collars can not form due to the steep front, which may suppress the snap-off.

• Clinical and Experimental Pediatrics
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• 제54권11호
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• pp.429-435
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• 2011

Although Korean population has been growing steadily during the past four decades, the nation is rapidly becoming an aging society because of its declining birth rate combined with an increasing life expectancy. In addition, Korea has one of the lowest fertility rates in the world due to fewer married couples, advanced maternal age, and falling birth rate. The prevalence of low birth weight infants and multiple births has been increased compared with the decrease in the birth rate. Moreover, the number of congenital anomalies is expected to increase due to the advanced maternal age. In addition, the number of interracial children is expected to increase due to the rise in the number of international marriages. However, the maternal education level is high, single-mother birth rate is low, and the gender imbalance has lessened. The number of overweight babies has been decreased, as more pregnant women are receiving adequate prenatal care. Compared to the Asian average birth weight, the average birth weight is the highest in Asia. Moreover, the rate of low birth weight infants is low, and infant mortality is similarly low across Asia. Using birth data from Statistics Korea and studies of birth outcomes in Korea and abroad, this study aimed to assess the changes in maternal and infant characteristics associated with birth outcomes during the past four decades and identify necessary information infrastructures to study countermeasures the decrease in birth rate and increase in low birth weight infants in Korea.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.191-194
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• 2005

In this paper the platform system for IEEE 802.15.4 Low Rate WPAN is designed and fabricated. IEEE 802.15.4 Low Rate WP AN system serves the functions and realization of home-area network. According to the IEEE 802.15.4 standard, there are two modes, One is BPSK modulation in 868/915MHz frequency band. The other is O-QPSK modulation in 2.45GHz frequency band. In this paper we implemented the platform system mounted in one PCB board in 868/915MHz frequency band of IEEE 802.15.4 Low Rate WPAN system. We measured that the platform system which consists of digital part and RF part has good performance. Also RF part is realized by design and fabrication of the RF transceiver IC. The key issue is to make the platform system which provides the function of Low Rate WPAN system to meet the requirement of IEEE 802.15.4 standards.

• 한국생활과학회지
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• 제19권5호
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• pp.817-833
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• 2010

This study was dedicated to searching better course of low birth rate study in Korea by carefully analyzing past and present low birth rate researches. For this 179 studies(101 master thesis and 78 journal articles) from 1991 to 2009 were analyzed. Next, using SPSS Win 12.0, the research type, topic, participants, data collection and method of data analysis were compared to the studies' years of publication. The most frequently applied research approach, topic, sampling method, data collection procedure and data analysis method in the research was found to be a literature study, solution and prevention of low birth rate related policy, literature study, literacy analysis. In conclusion, low birth rate studies should become more diversified in terms of types of the research, data collection method, and data analysis. Additionally, research topics should become more realistic and specified. Moreover, research results should be verified before they are applied to the policy.