• Journal of Nutrition and Health
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• 제35권3호
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• pp.332-351
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• 2002

The purpose of this study was to investigate effect of living condition and aging on food intake in Korea. 98 free-meal receivers and 81 members in well-being center for the aged were asked about their food frequency and food consumption and their socioeconomic status by a questionnaire. All data were analyzed by SPSS (Statistical Packages for the Social Sciences) 10.0 program. There were statistical differences of living condition, marital status, former job and teeth status between free-meal receivers and people with stable lives. Moreover, all age groups of free-meal receivers had lower income, living expenses, educational period and frequency of physical activity than those of people with stable lives. But smoking and drinking was much higher in free-meal receivers. Arthritis was the most prevalent disease in both groups. And free-meal receivers had higher blood pressure and lower Body Mass Index than people with stable lives. Food consumption of free-meal receivers was definitely lower than that of people with stable lives in terms of food frequency and standard amount of food eaten. But noodles, bean sprouts and eggs were very important foods for free-meal receives. Food consumption of the aged was affected by age, educational period, income, blood pressure, duration after retirement, frequency of physical activity and Body Mass Index. Therefore, as various socioeconomic status affects on food intakes of the aged, more effective and practical nutritional programs which consider the receivers'socioeconomic status are needed for the nutritionally at-risk groups like the aging free-meal receivers.

• Journal of Positioning, Navigation, and Timing
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• 제8권3호
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• pp.95-105
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• 2019

A method that applies space-time adaptive signal processing (STAP) algorithm based on an array antenna consisting of multiple antenna elements has been known to be effective to remove wide-band jamming signals in GPS receivers. However, the occurrence of phase distortion in navigation signals has been a problem when navigation signals, from which jamming signals are removed using STAP, are supplied to global positioning system (GPS) receivers. This paper verified the navigation performance degradation as a result of phase distortion. To mitigate this phenomenon, this paper proposes a mode switching scheme, in which a bypass mode is adopted to make the best use of the tracking performance of receivers without performing signal processing when jamming signals are not present or weak, and a STAP mode is employed when jamming signals exceed the threshold value. In this paper, the mode switching scheme is proposed for two environments: when receivers are stationary, and when receivers are moving. This paper confirmed that the performance of position error improved because phase distortion could be excluded due to STAP if the bypass mode was adopted under a condition where the jamming signal power level was below the threshold value in an environment where receivers were stationary. However, this paper also observed that the navigation failed due to the instability of tracking performance of receivers due to phase distortion that occurred at the switching time, although the number of switching could be reduced dramatically by proposing a dual threshold scheme of on- and off-thresholds that switched a mode due to the array antenna characteristics of varying gains according to the jamming signal incident direction in an environment where receivers were moving. The analysis results verified that running the STAP algorithm at all times is more efficient than the mode switching, in terms of maintaining stable navigation and ensuring position error performance, to remove jamming signals in an environment where receivers were moving.

• 한국통신학회논문지
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• 제23권7호
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• pp.1667-1676
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• 1998

적응형 MMSE(Minimum Mean Square Error) 수신기는 고정된 채널 환경에서 기존의 단일 사용자 CDMA(Code Division Multiple Access) 수신기에 비해 좋은 성능을 보이며 다른 다수 사용자 CDMA 수신기에 비해 간단한 구조를 가진다. 그러나 실제 무선 채널은 페이딩 채널이며, 수신신호의 크기와 위상이 시간에 따라 변하고 충분한 신호대 잡음 비가 항상 보장되지는 않는다. 이 경우 적응형 MMSE 수신기들은 그의 성능이 급격히 저하된다. 적응형 MMSE 수신기의 이러한 문제점을 해결하기 위하여, 본 논문에서는 새로운 구조와 적응 알고리듬을 갖는 적응형 MMSE 수신기를 제안하였으며, 컴퓨터 모의 실험을 통하여 제안된 수신기가 페이딩 환경에서 기존의 MMSE 수신기들에 비해 좋은 성능을 가짐을 확인하였다.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.124-128
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• 2014

We derive joint probability density functions (JPDFs) for two adjacent data from direct-detection optical receivers in dense wavelength-division multiplexing systems. We show that the decision using two data per bit can increase the receiver sensitivity compared with the conventional decision. Our JPDFs can be used for software-defined optical receivers enhancing the receiver sensitivities for intensity-modulated channels.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.183-185
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• 2011

A multiple charging method for a wireless power transfer system (WPTS) in the near-field region is proposed. We analyzed the frequency characteristics of multiple receivers in the near-field region. The results suggested that the time division WPTS can achieve efficient and equal power transmission at multiple receivers. We conclude that this system has an advantage for charging multiple receivers.

• Journal of Mechanical Science and Technology
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• 제14권12호
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• pp.1403-1411
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• 2000

Heat losses from the receivers for a dish-type solar energy collecting system constructed at Korea Institute of Energy Research are analyzed. The Stine and McDonald's model is used to estimate the convection loss. The Net Radiation method and the Monte-Carlo method are used to calculate the radiation heat transfer rate from the inside surface of the receiver to the surroundings. Two different receivers are suggested here and the performances of the receivers are estimated and compared with each other based on the prediction of the amount of heat losses from the receivers. The effects of the receiver shape and the radiation properties of the surface on the thermal performance are investigated. The performance of Receiver I is better than that of Receiver II, and the amount of solar irradiation that is not captured by the captured by the receiver after being reflected by the concentrator becomes significant if the temperature of the working fluid is low.

• 한국멀티미디어학회논문지
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• 제7권8호
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• pp.1078-1085
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• 2004

SARLM(Source Adaptive Receiver-Driven Multi-Layered Multicast)은 레이어 병합과 분할을 통해 수신자의 이질적인 대역폭 문제를 개선하고자 하였다. 그러나 이 기법은 레이어 병합 시에 상위 레이어의 수신자가 하위 레이어로 드롭되어 가용 대역폭의 이용률이 저하되는 문제가 있다. 본 논문에서는 수신자의 손실률 정도를 고려한 멀티캐스트 재그룹 기법을 제안한다. 제안 기법은 손실률에 따라 가중치를 부여하여, 상위 레이어와 하위 레이어 중 여유 대역폭이 많은 수신자를 그룹화하고, 하위 레이어와 상위 레이어 중 손실률이 높은 수신자를 그룹화한다. 실험 결과, 상위 레이어 수신자가 높은 전송률을 유지함으로써 수신자의 가용 대역폭 이용률이 향상됨을 알 수 있다.

• 한국식생활문화학회지
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• 제17권3호
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• pp.275-288
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• 2002

The purpose of this study was to investigate the cognitive differences among the aged who have different living conditions. 91 free-meal receivers and 86 people with stable lives were asked about their living conditions and cognitive function by using K-MMSE. All data were analyzed by SPSS 10.0 package. Free meal receivers had poorer socioeconomic status than the subjects who had stable lives. Cognitive function of free meal receivers was lower than the people with stable lives in the most cognitive factors. Especially age of 50 to 64, pre-aged group, who had been receiving free meals, showed lowest cognitive level than the other age groups. Among 7 cognitive factors, there was the greatest difference in attention and calculation between 2 groups. Percentage of 'conclusive dementia' among the free meal receivers was statistically higher than the people with stable lives and that of 'conclusively normal' was statistically lower in free meal receivers comparing with the people with stable lives. Moreover, socioeconomic factors like income, former job, marital status, housing and education, blood pressure and physical activity were significantly related to the subject's cognitive function.

• Journal of Mechanical Science and Technology
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• 제17권8호
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• pp.1185-1195
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• 2003

Heat losses from the receivers of a dish-type solar energy collecting system at the Korea Institute of Energy Research (KIER) are numerically investigated. It is assumed that a number of flat square mirrors are arranged on the parabolic dish structure to serve as a reflector. Two different types of receivers, which have conical and dome shapes, are considered for the system, and several modes of heat losses from the receivers are thoroughly studied. Using the Stine and McDonald model convective heat loss from a receiver is estimated. The Net Radiation Method is used to calculate the radiation heat transfer rate by emission from the inside surface of the cavity receiver to the environment. The Monte-Carlo Method is used to predict the radiation heat transfer rate from the reflector to the receiver. Tracing the photons generated, the reflection loss from the receivers can be estimated. The radiative heat flux distribution produced by a multifaceted parabolic concentrator on the focal plane is estimated using the cone optics method. Also, the solar radiation spillage around the aperture is calculated. Based on the results of the analysis, the performances of two different receivers with multifaceted parabolic solar energy collectors are evaluated.

• 한국통신학회논문지
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• 제41권9호
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• pp.1069-1080
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• 2016

수동형 감시시스템과 같은 TDOA(Time Difference Of Arrival) 기반의 위치탐지시스템은 다수의 수신기를 이격 설치 후에 수신기 간 시각동기화를 수행하여 동일한 시각으로 설정하고, 수신기에 수신되는 목표 신호의 도래시간차인 TDOA를 이용하여 쌍곡선(또는 쌍곡면)의 교점을 구함으로써 목표의 2차원(또는 3차원) 위치를 추정한다. 시각동기화를 수행하기 위해서는 다수의 수신기 중에 하나가 주수신기(Master)가 되어 나머지 종수신기(Slave)들의 시간을 보정하기 위한 기준을 제공해야 한다. TDOA 기반의 위치탐지 시스템은 서로 이격되어 배치되어 있는 다수의 수신기 중에 선택되는 주수신기에 따라 위치추정정확도가 달라진다. 따라서 다수의 수신기 중에 최적의 수신기를 주수신기로 선택해야 고려하는 시스템의 배치구조에서 최적의 위치추정 성능을 도출할 수 있다. 본 논문에서는 목표와 수신기의 기하학적 배치 기반의 DOP(Dilution Of Precision) 정보를 이용하여 낮은 복잡도와 짧은 수행시간을 가지면서 시스템 내에 자동화가 용이한 주수신기 선택 방법을 제안한다.