• 한국통신학회논문지
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• 제40권12호
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• pp.2539-2548
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• 2015

이종 셀룰러 네트워크 환경에서 셀 간 간섭 문제와 부족한 주파수자원 환경을 극복하는 것은 통신 성능을 향상시키기 위한 주요 방법 중 하나이다. 정적 주파수 재사용 방식은 한정된 주파수 자원 환경에서 셀 간 간섭 문제를 효율적으로 해결하기 위해 제안된 방식이다. 이러한 방식은 미리 정해진 파워와 대역으로 주파수를 할당하기 때문에 네트워크의 통신 성능향상에 제한이 있다. 또한 기존의 동적 주파수 재사용 방식들은 대부분의 경우 셀 안에 존재할 수 있는 스몰 셀 환경을 고려하지 않고 있고, 네트워크의 트래픽 부하기 심하고 불균일한 환경에 특화되어 있지 않다. 제안한 동적 주파수 재사용 기법은 다중 이종 셀룰러 네트워크 환경에서 네트워크 환경에 적응하여 각 셀의 트래픽 비율에 알맞게 동적으로 주파수를 할당한다. 제안한 기법은 먼저 각 셀 Edge의 PRB 사용량을 수집하고 이에 적응하여 스몰 셀을 제외한 전 셀 지역에 주파수를 재 할당한다. 그 후 이를 고려하여 스몰 셀을 위한 주파수를 할당하고 이를 반복하여 전체 셀의 주파수 자원을 할당한다. 해당 기법은 네트워크의 트래픽 부하가 심하고 불균일할 때 스몰 셀 환경을 위해 각 셀의 트래픽 부하에 적합한 주파수 자원을 할당시킴으로써, 기존의 방식에 비해 Spectral Efficiency 성능을 향상시켜 결과적으로 시스템의 Throughput 성능을 향상시킨다.

• Weed & Turfgrass Science
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• 제7권2호
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• pp.130-139
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• 2018

The colors of packaging of herbicides and non-selective herbicides on the market in Korea are defined as brown and red, respectively, according to the notification of RDA. The present study aimed to understand consumer's electroencephalographic (EEG) response when looking at brown and red colors of herbicide and non-selective herbicide packaging papers. The EEG cap was placed on the scalp of each participant (men and women, 10 to 20 years old) and white (control) - brown - white - red colors were sequentially displayed for 5 seconds using the computer monitor. The EEG was measured and statistical analysis was performed using SPSS. For the brown color of the herbicide, men showed a decrease in concentration and a distracting response due to a decrease in the ratio of mid beta to theta (RMT) and the spectral edge of frequency (SEF90). In women, an increase in the ratio of SMR to theta (RSMT) and the spectral edge frequency 50% of the alpha (ASEF) was observed in different brain regions and these EEG changes may enhance the relaxation, stabilization and awakening states of the brain. For the red color of the non-selective herbicide, ASEF increased psychological stability in men. In women, a decrease in absolute high beta (AHB) may associate with a decrease in attention state of the brain. Overall data of the present study clearly revealed that the colors of two herbicides showed significantly different EEG response and gender difference.

• 한국광학회지
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• 제8권3호
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• pp.175-182
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• 1997

가시광선 영역의 고분해능 3반사 망원경 광학계 설계를 위하여, 광학계의 기구적 제한사항을 만족함과 동시에 Flat Field Anastigmat 조건을 만족하는 해를 구하는 초기설계 기법이 제시되었으며, 이를 기초로 프로그램을 작성하여 F/14.5, 구경 600 mm, 시야 0.27.deg. * 1.3.deg.의 3반사 망원경광학계의 초기설계를 수행하였다. 초기 설계된 광학계의 최적화를 위하여 Code V를 사용하였으며, 그 결과로서 CCD의 모서리 부분 Field를 제외한 모든 Field에서 Nyquist Frequency에서의 MTF값이 0.5이상이었다.

• The Korean Journal of Physiology and Pharmacology
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• 제3권5호
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• pp.491-499
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• 1999

This study was designed to evaluate the efficacy of dynamic parameters, such as correlation dimension $D_2,$ by comparing spectral electroencephalographic (EEG) parameters. These parameters are used to estimate the depth of halothane anesthesia as defined by the presence of body movement in response to a tail clamp. Six rats were used and each of them was exposed to halothane sequentially at the concentrations of 0%, 0.5%, 1.0% and 1.5% for 30 min. A tail clamp was applied every five min and the movements were recorded at each concentration level. The spectral parameters and the dynamic parameters were derived from 20-sec and 10-sec segments, respectively, from the last 5-mins of EEG recording at each concentration level. Correlation coefficients between the parameters and the movements were calculated. Standardized values of three parameters, betaL power, median power frequency (MPF), and $D_2$ were derived by calculation based on the number of animals showing the movement in response to a tail clamp. The betaL power had the largest correlation coefficient to spontaneous movement and to the response to a tail clamp than any other band parameter. MPF had a better correlation with the movement than 90% spectral edge frequency. Among the dynamic parameters, $D_2$ on the parietal cortex had a better correlation with the movement. The level of deviation and variation of standardized $D_2,$ MPF, and betaL were significant (p<0.01). The order of deviation and variation was; betaL power > MPF > $D_2.$ The correlation dimension serves as a better index for the depth of halothane anesthesia defined in forms of a response to external stimulation.

• 전자공학회논문지S
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• 제34S권7호
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• pp.28-38
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• 1997

Previously, we have proposed the M-BECM(Modified-Band Edge Component Maximization), which is a symbol synchronization algorithm based on spectral line method for all-digital high speed digital communications. However, Until now, the characteristics of the timing detector based on the spectral line method including M-BECM was not analyzed, particularly the effect of a timing offset at the optimal convergence pont. In this paper, we analyze the timing dtector's characteristics of the M-BECM and present optimal design value. First, the expression for the timing detector's mean value(often called its S-Curver) as a function of the normalized symbol timing offset is derived. Next, the P $D_{bias}$, the value for compensating the timing offset at an optimal convergence point, and the bandwidth of bandpass filter in the timing detector are calculated. It is also shown and analyzed that the P $D_{bias}$ is affected by varuous factors such as the excess bandwidth of input signal, frequency offsets, noise and particularly, the excess bandwidth of input signal is a major parameter to decide P $D_{bias}$. Finally, analytic resutls are compared to simulation results.

• 한국통신학회논문지
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• 제40권3호
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• pp.559-567
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• 2015

This paper focuses on evaluating the performance of a cellular network using power control based frequency reuse partitioning (FRP) in downlink (DL). In our work, in order to have the realistic environment, the spectral efficiency of the system is evaluated through traffic analysis, which most of the previous works did not consider. To further decrease the cell edge user's outage, the concept of power ratio is introduced and applied to the DL FRP based cellular network. In considering network topology, we first divide the cell coverage area into two regions, the inner and outer regions. We then allocate different sub-bands in the inner and outer regions of each cell. In the analysis, for each zone ratio, the performance of FRP system is evaluated for the given number of power ratios. We consider performance metrics such as call blocking probability, channel utilization, outage probability and effective throughput. The simulation results show that there is a significant improvement in the outage experienced by outer UEs with power control scheme compared to that with no power control scheme and an increase in overall system throughput.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.186-193
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• 1999

Sensor feedback for process control is one of the essential elements is an automated deburring procedure. This paper presents the implementation of acoustic emission (AE), which has been developed as a feedback sensing technique for precision (mechanical) deburring, in a precision laser deburring process. AE signals were sampled for laser machining/deburring under various experimental conditions and analyzed using several signal-processing methods including AErms and spectral analysis. The results, such as the sensitivity of AE signals for different laser cutting depths, edge detection capability and the frequency analysis show a clear correlation between physical process parameters and the AE signals. A subsequent control strategy for deburring automation is also briefly discussed.

• 대한수의학회지
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• 제46권1호
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• pp.47-55
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• 2006

To evaluate method for monitoring anesthetic depth with quantitative electroencephalography (q-EEG), we recorded processed EEG (raw EEG) and pain score till 100 minutes in beagle dogs anesthetized for 60 minutes with propofol (n = 5, PRO group), isoflurane (n = 5, ISO group) and propofol-ketaminefentanyl (n = 5, PFK group). Raw EEG was converted into 95% spectral edge frequency (SEF) by fast Fourier transformation (FFT) method. We investigated anesthetic depth by comparing relationship (Pearson's correlation) between q-EEG (95% SEF) and pain score. Pearson's correlation coefficients are +0.2372 (p = 0.0494, PRO group), +0.79506 (p < 0.001, ISO group) and +0.49903 (p = 0.0039, PFK group).

• Journal of Mechanical Science and Technology
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• 제16권12호
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• pp.1604-1612
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• 2002

Rollers in the continuous process systems are ones of key components that determine the quality of web products. The condition of rollers (e.g. eccentricity, runout) should be consistently monitored in order to maintain the process conditions (e.g. tension, edge position) within a required specification. In this paper, a new diagnosis algorithm is suggested to detect the defective rollers based on the frequency analysis of web tension signals. The kernel of this technique is to use the characteristic features (RMS, Peak value, Power spectral density) of tension signals which allow the identification of the faulty rollers and the diagnosis of the degree of fault in the rollers. The characteristic features could be used to train an artificial neural network which could classify roller conditions into three groups (normal, warning, and faulty conditions) The simulation and experimental results showed that the suggested diagnosis algorithm can be successfully used to identify the defective rollers as well as to diagnose the degree of the defect of those rollers.

• 생명과학회지
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• 제23권9호
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• pp.1170-1176
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• 2013

에센셜오일은 신경생리학적 장애의 치료에 오랜동안 사용되었지만 아직까지 그 효능이 과학적으로 구명되지 않았다. 저자들은 한의학에서 산조인으로 알려져 있는 Zizyphus jujuba 종자의 에센션오일이 인간의 뇌파에 미치는 영향을 연구하였다. 초임계이산화탄소추출법을 이용하여 산조인으로부터 에센셜오일을 얻고, 20명의 피험자를 대상으로 EEG 파워 스펙트럼을 측정하였다. 산조인 에센셜오일 흡입 전과 흡입 중 다른 부위와 비교하여 theta파가 좌측 두정엽 부위($17.277{\rightarrow}13.854{\mu}V$)와 우측 두정엽 부위($15.324{\rightarrow}13.020{\mu}V$)에서 통계학적으로 차이를 나타내었다(p<0.05). 산조인 정유 흡입으로 fast alpha 파, relative gamma 파, spectral edge frequency 50% 지수가 증가하였는데, 이들 지수 중 fast alpha 파는 좌측 전전두엽 부위($0.063{\rightarrow}0.08{\mu}V$), 우측 전전두엽 부위($0.064{\rightarrow}0.085{\mu}V$), 그리고 좌측 두정엽 부위($0.073{\rightarrow}0.100{\mu}V$)에서 통계학적으로 차이를 나타내었다. 본 연구의 결과는 산조인 에센셜오일 흡입에 의한 EEG 변화는 두뇌기능 중 각성과 진정상태를 증가시켜 인간의 심리학적인 조건을 향상시킨다는 것을 추론하게 한다.