• Journal of Nutrition and Health
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• v.35 no.3
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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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• v.8 no.3
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1667-1676
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• 1998

It is known that adaptive minimum mean square error (MMSE) receivers exhibit better performance than coventional single-user code division multiple access (CDMA) receivers in fixed (or static) channels and have the simple structure compared to other multi-user CDMA receivers. In practice, the radio channels are fading channels where the amplitude and phase of the received signal are time-varying and the sufficient signal-to-noise ratio is not always guaranteed. Thus, the performance of adaptive MMSE receivers is severely degraded in fading environments. We propose a new structure and adaptation algorithm for an adaptive MMSE receivers. Based on computer simulation results, it is observed that the proposed receiver demonstrates substantial performance improvement over currently available adaptive MMSE receivers in fading environments.

• Journal of the Optical Society of Korea
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• v.18 no.2
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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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• v.11 no.3
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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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• v.14 no.12
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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.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1078-1085
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• 2004

The SARLM(Source Adaptive Receiver-Driven Multi-Layered Multicast) has been proposed to address heterogeneous bandwidth constraints through layer merging and splitting. However, this method causes that receivers subscribing to the higher layer drop down to the lower layer and hence may decrease utilization of available bandwidth after layer merging. In this paper, we proposed a multicast regrouping method considering distributive status of receivers according to loss rates. The proposed method weights receivers according to loss rates. And then it groups higher layer with receivers subscribing to lower layer have extra bandwidth and lower layer with receivers subscribing to higher layer have high loss rate. Experimental results show that receivers subscribing to higher layer can receive in high transmission rate and consequently the proposed method effectively improves utilization of available bandwidth.

• Journal of the Korean Society of Food Culture
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• v.17 no.3
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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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• v.17 no.8
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.1069-1080
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• 2016

TDOA(Time Difference Of Arrival)-based localization system such as the passive surveillance system performs the time synchronization between the receivers after separated installing multiple receivers to set the same clock for all receivers. And it estimates 2D(or 3D) location of the target by solving intersection of the multiple hyperbola(or hyperboloid) using TDOA. To perform time synchronization, one receiver must be set to the master, and it provide the reference data to compensate the clock of the rest of the slaves. The positioning accuracy of TDOA-based localization system is changed in accordance with the master that is selected among multiple receivers. So, the optimum receiver which is selected among multiple receivers must be set to master to get best performance in the considered deployment of receivers. In this paper, we propose a selection scheme of master receiver for time synchronization using DOP(Dilution Of Precision) which is based on location of the target and the multiple receivers. The proposed scheme has low complexity and short processing time, and it is easy to automate in the TDOA-based localization systems.