• 한국정보통신학회논문지
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• 제21권7호
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• pp.1342-1348
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• 2017

디지털 정보화 시대에서 영상은 여러 매체에서 필수적으로 이용되며, 잡음은 이러한 영상을 획득, 전송하는 과정에서 여러 외부 원인에 의해 발생된다. 잡음 제거는 영상 처리에서 필수적인 과정이며, 잡음의 종류에는 발생 원인과 형태에 따라 다양한 종류가 있으며 AWGN이 대표적이다. 따라서 본 논문에서는 영상에 첨가된 잡음의 영향을 완화하기 위해, 전처리 과정으로 국부 마스크를 9개의 영역으로 구분하여 각 화소들의 평균을 이용한 에지 검출 방법을 적용한다. 그리고 변형된 에지 검출의 결과에 임계값을 적용하여 국부 마스크에 서로 다른 필터를 적용하는 알고리즘을 제안하였다. 제안한 알고리즘의 우수성을 입증하기 위해, 확대 영상 및 PSNR(peak signal to noise ratio)을 이용하여 기존의 방법들과 그 성능을 비교하였다.

• Journal of Biosystems Engineering
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• 제27권1호
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• pp.59-66
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• 2002

The objectives of the study were to analyze the acoustic characteristics related to the internal quality factors of watermelon(Citrulus Vulgaris Schrad). Among the various internal quality factors, only four factors such as ripeness, inside cavity, yellow belt and blood flesh were considered in this study. Relationships between the internal quality factors, the day after fruit set and the day after harvest were also investigated. Test apparatus was the same as the apparatus described in the previous study(Choi et at., 2000). The selected sample was divided into four groups; 69 samples used for ripeness tests 56 samples for ripeness test along the day after fruit set and for yellow belt detection, 60 samples for ripeness along the day after harvest 44 samples fur blood flesh detection. It was shown that the first peak frequencies shifted to the lower range and the energy ratios of the bandwidths between 0∼550 Hz to the bandwidths between 850∼2500 Hz increased as the day after fruit set elapsed. Since the acoustic responses of the watermelon such as frequency and magnitude began to change from 10 days after harvest, the storage period of watermelon in a normal temperature condition seemed to be approximately 10 days after harvest. The ratios of the first peak amplitude to the maximum peak amplitude fur the sound watermelon showed the higher value than that fur watermelon with cavity inside, and the separation between the sound and cavity inside could be accomplished by the ratio value of 0.25. The energy ratios (0∼550 Hz/850∼2,500 Hz) for the watermelon with cavity inside showed the higher value than 2.3. The frequency characteristics of the yellow belt watermelon appeared mostly in the range of 600∼900 Hz frequencies. The yellow belt watermelon showing the energy spectral density function at this frequency range to be over 70 seemed to be not a marketable commodity, The energy ratios(0∼550 Hz/850∼2,500 Hz) for the blood flesh watermelon showed the higher value than 3.5.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.157-166
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• 2016

In this paper, a new sag and peak voltage detector is proposed for a single-phase inverter using delta square operation. The conventional sag detector is from a single-phase digital phase-locked loop (DPLL) that is based on d-q transformations using an all-pass filter (APF). The d-q transformation is typically used in the three-phase coordinate system. The APF generates a virtual q-axis voltage component with a 90° phase delay, but this virtual phase cannot reflect a sudden change in the grid voltage at the instant the voltage sag occurs. As a result, the peak value is drastically distorted, and it settles down slowly. A modified APF generates the virtual q-axis voltage component from the difference between the current and the previous values of the d-axis voltage component in the stationary reference frame. However, the modified APF cannot detect the voltage sag and peak value when the sag occurs around the zero crossing points such as 0° and 180°, because the difference voltage is not sufficient to detect the voltage sag. The proposed algorithm detects the sag voltage through all regions including the zero crossing voltage. Moreover, the exact voltage drop can be acquired by calculating the q-axis component that is proportional to the d-axis component. To verify the feasibility of the proposed system, the conventional and proposed methods are compared using simulations and experimental results.

• Bulletin of the Korean Chemical Society
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• 제28권10호
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• pp.1720-1724
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• 2007

Electrochemical behaviors of bovine hemoglobin (Hb) at an acetylene black paste electrode based on the enhancement effect of sodium dodecyl sulfate (SDS) were investigated. In the optimal conditions, a very weak reduction peak was observed at an acetylene black paste electrode for hemoglobin in the absence of SDS. However, the reduction peak current increased remarkably after the addition of 4.0 × 10?4 mol L?1 SDS, suggesting that SDS exhibits obvious enhancement effect to the determination of hemoglobin. All the experimental parameters, such as pH value, concentration of SDS, accumulation time and accumulation potential were optimized for hemoglobin analysis. The proposed method possesses high sensitivity (detection limit is 3.0 × 10?9 mol L?1), wide linearity (6.0 × 10?9 to 6.0 × 10?7 mol L?1), rapid response and low cost. Finally, the method was successfully employed to determine hemoglobin in a spiked sample.

• 전기학회논문지
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• 제57권8호
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• pp.1470-1477
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• 2008

In this paper, a new detection method of series arc-fault signals occurring at the wiring of home appliances is proposed. The discrete wavelet transform was used for the numerical analysis of the variation rate in peak, RMS, noise energy, shoulder of the arc-fault current wave. As a results, the arc distinction threshold value of these variation rates was about 0.1 in most cases. The arc-fault current of the loads with the active PFC circuit showed a high rate of variation in noise energy and shoulder, but arc-fault current of the loads without the active PFC circuit showed a high rate of variation in peak and RMS. The arc fault current in resistive loads showed a high rate of variation in shoulder.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.705-706
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• 2006

Generally Short Circuit Test of transformers are tested according to IEEE std C57.12.00-2000, IEC 60076-5(2000-07), ES148(1998.6.26) or KS C4309(2003). But ES148(1998.6.26) is same as IEEE std C57. 12.00-2000 and KS C4309(2003) is revising coincidence with IEC 60076-5(2000-07). On this study condition of the transformers before short circuit test, calculation method for test current peak value, tolerance on the asymmetrical peak and r.m.s value, short circuit testing procedure, number of short circuit test, duration short circuit test, and detection of faults and evaluation of short circuit test result will be compared with ANSI and IEC.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.745-750
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• 2014

The chatter vibration in the machining process plays bad role in machining quality such as high roughness as well as tool life and machine failure. And the grinding process under this risk in the fully automated factory is exposed to the unexpected mass machining quality problem. Studying the vibration signal of the hub bearing grinding process, the reason of chatter vibration was explained with the specific machining pattern of chatter. And this study suggests the chatter detecting method in the production line, which is monitoring the peak acceleration level around the natural frequencies of the specimen, and calculating kurtosis value by assuming the chatter is related to the resonance of the specimen. The suggested method was applied to the vehicle hub bearing grinding process and proved good to detecting the chatter induced machining quality problem.

• Journal of Korean Neurosurgical Society
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• 제56권6호
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• pp.455-462
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• 2014

Objective : To propose a new measure for effective monitoring of intraoperative somatosensory evoked potentials (SEP) and to validate the feasibility of this measure for evoked potentials (EP) and single trials with a retrospective data analysis study. Methods : The proposed new measure (hereafter, a slope-measure) was defined as the relative slope of the amplitude and latency at each EP peak compared to the baseline value, which is sensitive to the change in the amplitude and latency simultaneously. We used the slope-measure for EP and single trials and compared the significant change detection time with that of the conventional peak-to-peak method. When applied to single trials, each single trial signal was processed with optimal filters before using the slope-measure. In this retrospective data analysis, 7 patients who underwent cerebral aneurysm clipping surgery for unruptured aneurysm middle cerebral artery (MCA) bifurcation were included. Results : We found that this simple slope-measure has a detection time that is as early or earlier than that of the conventional method; furthermore, using the slope-measure in optimally filtered single trials provides warning signs earlier than that of the conventional method during MCA clipping surgery. Conclusion : Our results have confirmed the feasibility of the slope-measure for intraoperative SEP monitoring. This is a novel study that provides a useful measure for either EP or single trials in intraoperative SEP monitoring.

• 지질공학
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• 제31권4호
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• pp.479-492
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• 2021

We conducted a fundamental study on geological and rock detection via drone-based hyperspectral imaging on various types of small rock samples and interpreted the obtained information to compare and classify rocks. Further, we performed hyperspectral imaging on ten rocks, and compared the peak data value and reflectance of rocks. Results showed a difference in the reflectance and data value of the rocks, indicating that the rock colors and minerals vary or the reflectance is different owing to the luster of the surface. Among the rocks, limestone used for hyperspectral imaging is grayish white, inverted rock contains various sizes and colors in the dark red matrix, and granite comprises colorless minerals, such as white, black, gray, and colored minerals, resulting in a difference in reflectance. The reflectance of the visible ray range in ten rocks was 16.00~85.78%, in the near infrared ray range, the average reflectance was 23.94~86.43%, the lowest in basalt and highest in marble in both cases. This is because of the pores in basalt, which caused the difference in reflectance.

• 한국수정란이식학회지
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• 제24권3호
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• pp.131-137
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• 2009

In dogs, correct diagnosis of estrus is important and the exact time of ovulation can be determined by variouse methods. Vaginal cytology has commonly used in conjunction with the physical examination, clinical history, vaginoscopy, and hormonal assays to determine the stage of the reproductive cycle. This study was therefore investigated the effectiveness of direct ovulation detector designed by changes of electrical resistance in vaginal mucus following different estrus cycles with several methods; vaginal cytology, concentration of plasma estrogen and progesterone, and direct examination by laparotomy. A total of 12 bitches was selected for the study and observed estrus signs. The bitches were evaluated clinical sign (vulvar swelling and bleeding), cytological examination (keratocyte and RBC), electrical resistance, plasma estrogen and progesterone concentration for estrus assessment. Accuracy of ovulation detection by vaginal cytology was significantly (p<0.05) lower than those by electrical resistance and plasma progesterone concentration, based on the confirmation by laparotomy. Vaginal smear is not confidential method compared to detection of electrical resistance and plasma progesterone concentration at ovulation. Although the value of electrical resistance was varied at the same points of estrus in individuals, ovulation was occurred at the first day which shown the peak of electrical resistance and mating time was third day after peak. In conclusion, ovulation detector designed by changes of electrical resistance is an effective and economic instrument for predicting estrus and ovulation in bitches.