• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.229-234
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• 2000

최근에 제외국에서는 소출력 무선기기의 용도미지정(개방용)주파수대를 확보하거나 여러 용도의 소출력 무선기기의 유사용도 주파수대역을 통합하여 한정된 주파수 환경의 효율을 높이고 있다. 본 논문에서는 소출력 무선기기에 주파수대역 검토, 유사용도 통합 및 ISM 주파수대역의 개방용 주파수 활용방안을 제안하여, 한정된 주파수환경의 효율적인 활용을 목적으로 한다.

• Computers and Concrete
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• 제27권2호
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• pp.85-97
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• 2021

In this study, the effect of steel fiber utilization, boundary conditions, different beam cross-section, and length parameter are investigated on the free vibration behavior of fiber reinforced self-compacting concrete beam on elastic foundation. In the analysis of the beam model recommended by Euler-Bernoulli, a method utilizing Stokes transformations and Fourier Sine series were used. For this purpose, in addition to the control beam containing no fiber, three SCC beam elements were prepared by utilization of steel fiber as 0.6% by volume. The time-dependent fresh properties and some mechanical properties of self-compacting concrete mixtures were investigated. In the modelled beam, four different beam specimens produced with 0.6% by volume of steel fiber reinforced and pure (containing no fiber) SCC were analyzed depending on different boundary conditions, different beam cross-sections, and lengths. For this aim, the effect of elasticity of the foundation, cross-sectional dimensions, beam length, boundary conditions, and steel fiber on natural frequency and frequency parameters were investigated. As a result, it was observed that there is a noticeable effect of fiber reinforcement on the dynamic behavior of the modelled beam.

• 한국안전학회지
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• 제35권5호
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• pp.15-21
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• 2020

Quantitative risk assessment (QRA) is used as a legal or voluntary safety management tool for the hazardous material industry and the utilization of the method is gradually increasing. Therefore, a leak frequency analysis based on reliable generic data is a critical element in the evolution of QRA and safety technologies. The aim of this paper is to derive the leak frequency function that can be applied more flexibly in QRA based on OGP report with high reliability and global utilization. For the purpose, we first reviewed the data on the 16 equipments included in the OGP report and selected the predictors. And then we found good equations to fit the OGP data using non-linear regression analysis. The various expectation functions were applied to search for suitable parameter to serve as a meaningful reference in the future. The results of this analysis show that the best fitting parameter is found in the form of DNV function and connection function in natural logarithm. In conclusion, the average percentage error between the fitted and the original value is very small as 3 %, so the derived prediction function can be applicable in the quantitative frequency analysis. This study is to contribute to expand the applicability of QRA and advance safety engineering as providing the generic equations for practical leak frequency analysis.

• 한국통신학회논문지
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• 제37권8B호
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• pp.677-686
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• 2012

In the presence of a high power cellular network, picocells are added to a Macro-cell layout aiming to enhance total system throughput from cell-splitting. While because of the different transmission power between macrocell and picocell, and co-channel interference challenges between the existing macrocell and the new low power node-picocell, these problems result in no substantive improvement to total system effective throughput. Some works have investigated on these problems. Pico Cell Range Expansion (CRE) technique tries to employ some methods (such as adding a bias for Pico cell RSRP) to drive to offload some UEs to camp on picocells. In this work, we propose two solution schemes (including cell selection method, channel allocation and serving process) and combine new adaptive frequency partitioning reuse scheme to improve the total system throughput. In the simulation, we evaluate the performances of heterogeneous networks for downlink transmission in terms of channel utilization per cell (pico and macro), call blocking probability, outage probability and effective throughput. The simulation results show that the call blocking probability and outage probability are reduced remarkably and the throughput is increased effectively.

• 한국정보과학회논문지:정보통신
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• 제37권3호
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• pp.249-253
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• 2010

폭발적인 트래픽 양의 증가와 함께 ISM 대역과 같이 라이선스가 필요 없는 주파수 대역의 포화상태로 인하여 무선네트워크의 주파수 자원이 점점 부족해지고 있다. 그러나 반대로 라이선스 주파수 대역의 이용률은 극히 저조한 상태라는 것이 여러 실험결과를 통해 알려졌다. 이러한 라이선스 주파수의 비효율적인 측면을 완화하기 위해 최근 인지라디오 기술이 제안되고 있다. 인지라디오는 비록 라이선스가 없는 사용자라도 라이선스 사용자를 방해하지 않는 한에서 라이선스 주파수 대역을 사용할 수 있도록 하는 기술로써 라이선스 주파수 대역을 좀 더 효율적으로 사용할 수 있게 하는 기술이다. IEEE 802.22는 인지 라디오를 기반으로 하는 첫 번째 표준 무선네트워크이다. IEEE 802.22는 라이선스 사용자의 충분한 보호와 주파수 대역 사용의 효율성을 극대화 하기 위해 Two-Stage 채널 센싱 기법을 제안하고 있다. 본 논문에서는 Two-Stage 채널 센싱의 오버헤드를 분석하고 센싱에 사용되는 시간이 오버헤드에 미치는 영향을 알아보고자 한다.

• 한국식생활문화학회지
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• 제14권4호
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• pp.271-287
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• 1999

A change in distribution structure affect a consumption structure which may result in considerable changes in lifestyle including food purchase. The purpose of this study was to investigate the effect of change of distribution structure on the indigenous fermented food purchase. The informations of this study were obtained from 407 housewives residing in Seoul and the capital area by using questionnaire during May to June, 1997 Their data were statistically analyzed based on frequency, mean, and $X^2-test$. The results were as follows; 1) The percentages of subjects buying ready made fermented food were 69.8% for Jotkals(salt-fermented fish products), 22.3% for Kochujang(fermented red pepper soybean paste), 21.6% for Janachis(pickled basic side dishes), 21% for Kanjang(Korean style soybean sauce), 17.1% for Toenjang(Korean style soybean paste), and 3% for Kimchi(seasoned and fermented vegetables). 2) With decreasing age, preparation ability of Kanjang, Janachis, and Kimchi. The subjects living close to the new distribution channel were higher in ready made fermented food than the others. 3) Compared to the subject living far from the new distribution channel, the subject living close to the new distribution channel was high in frequency of new distribution channel utilization for indigenous fermented food purchase but low in frequency of conventional market utilization. The younger in age, higher in educational level, and nuclear family, the higher the utilization of new distribution channel for indigenous fermented food purchase.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.186-205
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• 2019

Intercell interference coordination (ICIC) is considered as a promising technique to increase the spectral efficiency of OFDMA cellular systems. The soft frequency reuse (SFR) and fractional frequency reuse (FFR) are representative and efficient management techniques for ICIC. Herein, to enhance the performance of the SFR scheme, we propose a call admission (CAC) scheme. In this CAC scheme, called Spectrum handoff-SFR(S-SFR), the spectrum handoff technique is applied to the user equipment (UE) located near the cell center. We derive the traffic analysis model to describe the S-SFR. In addition, a two-dimensional (2-D) Markov chain and an outage analysis are used in our analytical model. From the traffic analysis, the significant performance measures are the outage probability, call blocking probability, system throughput and resource utilization. Based on those, the outage probability and system throughput are obtained using resource utilization as an interference pattern. The analytical results are verified with computer simulation results. Finally, we compare our proposed scheme with other ICI schemes.

• Journal of the Korean Data and Information Science Society
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• 제27권2호
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• pp.419-427
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• 2016

본 연구는 한국의료패널 조사 자료 2008-2012년의 연간 통합자료를 활용하여 흡연력에 따른 구강질환과 관련하여 치과외래이용횟수에 미치는 영향을 알아보고자 하였다. 2010-2012년의 연간 통합자료 중 연령이 20세-60세이면서 3차례 모두 조사된 남성 3,866명을 최종 분석대상으로 하였다. 음이항회귀모형을 이용한 분석에서 연령, 혼인상태, 가구소득수준와 만성질환여부를 통제한 후 치과외래이용횟수에 미치는 영향은 유의하였으며 흡연력이 10갑년 증가할 때마다 치과외래이용횟수는 6%씩 증가할 것으로 예측되었다. 특히, 40~50대 남성의 치과외래이용횟수는 비흡연자에 비교하여 평균적으로 20~29.9갑년의 흡연자는 25%, 30갑년 이상 흡연자는 52% 더 많이 이용하는 것으로 나타났다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.526-529
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• 2015

스마트폰 산업이 발전하면서 내부 하드웨어 장치들이 고사양의 장치가 되었고 이전 보다 많은 전력소비를 요구 한다. 그러므로 고용량의 배터리가 필요 하지만 스마트폰의 소형화로 인해 부피가 큰 배터리를 탑재하는 것에 한계가 있다. 리눅스 커널은 이러한 한계점을 소프트웨어 기술로 보완하기 위해 DVFS Mechanism을 제공 한다. DVFS는 동적으로 CPU의 동작주파수를 조정 하여 CPU의 전력소비를 줄이는 Mechanism이다. DVFS에서 기본정책인 ondemand는 up_threshold를 넘을 때 마다 최대 동작주파수를 적용 하여 상당 시간 유지되므로 CPU 자원의 낭비를 초래 한다. 본 논문에서는 이러한 점에 착안하여 계속해서 현재 동작주파수 대비 높은 CPU 이용률을 유지함으로써 CPU자원의 낭비를 막고 에너지를 절약 하는 기법을 제안한다.

• 가정과삶의질연구
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• 제9권1호통권17호
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• pp.113-130
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• 1991

The purpose of the present study was to describe the expectation and the performance on the housework socialization of the age homemakers and to ivestigate their relationships to the demographic characteristics and the influences of other related factors. 344 homemakers who were older than 45 years and were living in Chunlabuk-do, 1990 were sampled for this study. The data were collected by questionnaire designed by the researcher and analyzed by using frequency, one-way ANOVA analysis of variance, t-test, and multiple regression analysis. The major findings were as follows ; 1) The aged homemakers' housework socialization score was higher than the average, The score of the expectation was higher than one of the present performance. Scores for the utilization of the household equipments and the utilization of employes's services were higer comparing to those for other variables of the performance and the expectation respectively. 2) There was the significant differences in the each of the present performance varibles related to th housework socialization among the following demographic varables ; Age of homemakers, years of marriage, education, residence area, types of housing, monthly income, and level of housework equipment possession. 3) There was the significant differences in the expectation on the housework socialazation among the following variables ; age of homemakers, years of marriage, education, monthly income, and types of housing. The significant differences were found in the utilization of grouped, the utilization of the commodity, the utilization of the household equipments as subvariables of housework socialization, among age of homemakers, years of marriage, and level of education, The significant differences were found in the utilization of employee's services among age of homemakers, types of family, and level of health. 4) The level of education and monthly income significantly influenced on the present performance of the house work socialization. Years of marriage, significantly influenced on the utilization of grouped, education on the utilization of the commodity.(the utilization of the producted materials) and the utilization of employee's services and monthly income on the utilization of the household equipments (the utilization of the household appliances, and equipments). The years of marriage and education significantly influenced on the expectation on the housework socialization in the order, Age of homemakers and years of marriage significantly influenced on the utilization of grouped, the utilization of the commodity, the utilization of employee's services and age of homemakers and monthly income on the utilization of the household equipments.