• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1427-1433
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• 2008

There is SARLM scheme for dynamic adaptation to network congestion status which arises from multicast applications. However, in this scheme, when congestion occurs in a local, the waste of available bandwidth occurs in non-congestion local because of reducing of transmission rate in congestion local. In this paper, we propose a hierarchical multicast for dynamic adaptation to network congestion. In proposed scheme, we select a representative in each local. while congestion status. It receives packet from multicast sender and hierarchically transmits packet to the representative in congestion status by unicast for preventing decrease of transmission rate and the representative in congestion local transmits packet to the receivers in local by multicast. In experimental results, it was known that the proposed scheme could improve transmission rate of receivers in congestion status and more efficiently used available bandwidth.

• Journal of the Korean Geographical Society
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• v.32 no.1
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• pp.91-112
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• 1997

This paper is mainly concerned with an understanding of spatial pattern of welfare by social indicators; thus an attempt for a social research is made to clarify spatial characteristics of welfare in Pusan through local welfare approach. The use of objective and subjective indicators simultaneously helps supplement the weakness which each of this indicators holds. The welfare level in Pusan showed various characteristics in the whole study area and in the all welfare sectors. Especially, the differences between objective and subjective welfare are found in the whole city. If the redistributional strategy is given to the priority among the welfare policies, it may be expected that the welfare level will be more equally distributed in Pusan.

• Journal of Digital Contents Society
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• v.12 no.3
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• pp.355-360
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• 2011

In this paper, the performance of OFDM (Orthogonal Frequency Division Multiplexing) was assessed by using computer simulations performed using Matlab. We analyzed channel estimation algorithm for adaptive modulation techniques and effect of system using designed simulator in Multimedia wireless communication multipath fading channel environment. Also, we analyzed performance of adaptive OFDM systems that apply adaptive equalizer using guided result through BER. In result, in case of adaptive modulation OFDM systems that modulation mode changes according to channel state, we knew that adaptive modulation OFDM systems have gains of about 7dB performance than general system (BER=$10^{-1}$). Thus we know that adaptive OFDM propose systems is required for efficient transmission in the high speed Multimedia wireless communication channel environment.

• Korean Journal of Psychosomatic Medicine
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• v.11 no.2
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• pp.182-195
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• 2003

Background: Marriage is one of the major life events and the primary source of individual happiness and meaning of life. It is not possible to predict who will marry whom and which marriage will be successful. Marital adjustment has significant influences on an individual and relationship functioning and is associated with mental health. Good marital quality may imply good general relationship. There are several factors that correlate with or predict good marital quality. Especially individual personality factors may be a major factor in achieving and maintaining marital stability, satisfaction and happiness. The aim of the present study was to investigate the possible relationship between dyadic adjustment and personality dimensions in urban married women. Methods: Dyadic Adjustment Scale, Eysenck's Personality Questionnaire, Beck Depression Inventory and State-Trait Anxiety Inventory were administered to 215 married women. Data analysis was based on 170 women who provided reliable informations. The descriptive statistics of demographic data and 4 scales were obtained. Then the possible relationships between each data were tested by calculating Pearson's product moment correlations. To test the effects of depression and anxiety on dyadic adjustment, stepwise multiple regression analysis was done. Results: Age and length of marriage were negatively correlated with affectional expression and dyadic cohesion. Educational level was positively correlated with total dyadic adjustment score and dyadic satisfaction. Family income was positively correlated with total dyadic adjustment score, dyadic consensus, dyadic satisfaction and dyadic cohesion. Different family type showed different total dyadic adjustment score, dyadic satisfaction and dyadic cohesion. Psychoticism was negatively correlated with total dyadic adjustment score, dyadic consensus, dyadic satisfaction, affectional expression and dyadic cohesion. Neuroticism was negatively correlated with total dyadic adjustment score, dyadic consensus, dyadic satisfaction and affectional expression. Extraversion and lie were not correlated with any factors. Beck Depression Inventory and State-Trait Anxiety Inventory scores were negatively correlated with total dyadic adjustment score, dyadic consensus, dyadic satisfaction, affectional expression and dyadic cohesion. The result of multiple regression analysis indicated that psychoticism was correlated with dyadic adjustment. Conclusion: These results showed that the demographic factors such as age, length of marriage, educational level, family income and family type were significantly correlated with dyadic adjustment. Psychoticism and neuroticism measured by Eysenck Personality Inventory were significantly correlated with dyadic adjustment. But the correlations with extraversion and lie were not significant. Especially correlation between neuroticism and dyadic adjustment seemed to be mediated by emotional state such as depression and anxiety. These findings suggest that personality factors may be involved in marital relationship and that clinician must consider personality aspect in dealing with marital problems. Future study about differences between control group and psychiatric patient group will be needed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9C
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• pp.826-833
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• 2007

In this paper, we present an adaptive transmission system model to establish the baseline for wireless adaptive transmission using CR (Cognitive Radio) systems, and propose an adaptive transmission scheme based on IT (Interference Temperature) cognition for CR systems in the presented system environment. The proposed CR adaptive transmission scheme is the method that provides the CR user with the maximum transmit power in the range of not causing any interference to the incumbent user and guaranteeing the optimal throughput by applying CR-AMC (CR-Adaptive Modulation and Coding) in the given channel state. Simulation results show that in case of using the proposed CR adaptive transmission scheme, there is little degradation of BER performance, while causing no interference to the incumbent user. At the same time, the proposed scheme guarantees the optimal throughput to the CR user in the given channel state.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.24-35
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• 2018

In wireless communications environments, a link adaptation technique that selects the proper rate from among several transmission rates is adopted to cope with variations in channel status. In block coded modulation, the frame time and/or the block length can be adjusted to the channel status. A smaller frame time can cause inter-frame interference (IFI), however, a larger frame time can reduce the data rate. Therefore, frame time is the design factor decided by a tradeoff between performance and the data rate. This paper presents a method to determine the frame time based on the processing gain for the channel model, CM1~CM4, recommended by IEEE 802.15a. Also, a link adaptation technique for block coded modulation is proposed for efficient communications by varying the frame time and the block length. Through simulation, link adaptation can be carried out with a step size of 2~5 nsec in a frame time range of 14~ 50 nsec for channel models CM1~CM4.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12A
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• pp.1182-1188
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• 2006

Adaptive OFDM(Orthogonal Frequency Division Multiplexing) improves data capacity and system performance over multipath fading by adaptively changing modulation schemes according to channel state information(CSI). To achieve a good performance in adaptive OFDM systems, CSI should be transmitted from receiver to transmitter in real time through feedback channel. However, practically, the CSI feedback delay d which is the sum of the data processing delay and the propagation delay is not negligible and damages to the reliability of CSI such that the performance of adaptive OFDM is degraded. This paper presents an adaptive OFDM system with a multistep predictor on the frequency axis to effectively compensate the multiple feedback delays $d(\geq2)$. Via computer simulation we compare the proposed scheme and existing adaptive OFDM schemes with respect to data capacity and system performance.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.334-343
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• 1995

The eyes of Nilaparvata lugens were examined for ultrastructural changes in the light and dark adapted states. Inspection of light microscope sections taken at similar levels of compound eyes from insects kept in light or darkness for periods up to 72 hors revealed some differences between light and dark adapted eyes. Using the electronmicroscope, in light adapted eyes the palisade layer was narrower than that in dark adapted eyes. The pigment granules still formed a ring around the palisade layer in the dark adapted eye but, they did not form a tight circle around the rhabdom. No constant difference was found between the diameters of the microvilli in light and dark adapted eyes. The pigment movements at the junction of the cone and the rhabdom took the effect on varying the pigment aperture at the tip of the cone in front of the rhabdom tip.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11A
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• pp.831-843
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• 2009

In this paper, we propose a new adaptive cooperation scheme with multi-relay nodes which achieves higher performance and spectral efficiency than that of some conventional cooperative schemes. The relay-selection is applied to choose the most potential relay among K ones. Afterward, the instantaneous signal-to-noise ratio (SNR) differences between S-D, S-R and R-D channels are considered for adaptive selection between the direct and the cooperation transmission strategy. In the proposed adaptive protocol, if the direct link is of high quality, the source will transmit to destination directly with all power consumption. Otherwise, the source broadcasts the signal with a lower power and requires the help of the chosen relay if it decodes correctly, else the source will transmit again with remaining power. Firstly, the spectral efficiency is derived by calculating the probability of each mode. Subsequently, the BER performance for the adaptive cooperation scheme is analyzed by considering each event that one of K relays is selected and then making the summation of all. Finally, the numerical results are presented to confirm the performance enhancement offered by the proposed schemes.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1351-1354
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• 2005

무선 환경에서는 모바일 기기의 이동 혹은 링크의 충돌, 부족한 대역폭등 모바일 기기의 외적 환경 변화에 의해 무선 링크의 단절이 빈번하게 일어나는데, 링크의 단절은 네트워크 자원을 사용하는 어플리케이션의 에러로 이어진다. 이러한 무선 환경의 단절을 어플리케이션이 알 수 있다면, 링크의 단절로 인한 어플리케이션의 에러를 방지 할 수 있게 된다. 본 논문에서는 어플리케이션이 무선 링크에 적응할 수 있도록 링크의 상태 정보를 판단 및 예측할 수 있는 dynamic watermark 기반의 상태 정보 추적 알고리즘을 제안한다.