• Journal of the Korean Institute of Telematics and Electronics T
• /
• v.35T no.3
• /
• pp.120-127
• /
• 1998

In this paper, ultrasonic images of 25MHz bandwidth were acquired by applying peak value variation, time average and depth profile algorithm to acoustic microscopy and its performance was compared and analysed with each other. In the time average algorithm, total reflecting pulse wave from a spot on the coin was converted to digital data in time domain and average value of the converted 512 data was calculated in computer. Time average image was displayed by gray levels colour of acquired N x N matrix average data in the scanning area on the sample. This technique having smoothing effects in time domain make developed an ultrasonic image on a highly scattering area. In depth profile technique, time difference between the reference and the reflected signal was detected with minimum resolution performance of 2ns, thus we can acquired real 3 dimensional shape of the scanning area in accordance with relative magnitude. Through these experiments, peak value, time average and depth profile images were analysed and advantages of each algorithm were proposed.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.10
• /
• pp.89-95
• /
• 2013

Smoking in elevators is a criminal offense that is included in a misdemeanor. Because of that smoking in elevators can be very critical for our growing children and weak women. In this paper, we would like to extract criminals doing this criminal offense to smoke in elevators. Extraction method detect difference value using modified color-X2-test and it was normalized. Next, we find frames that has occurred scene change in successive frames using the four-step algorithm of scene change detection. Finally, we present the method of smoking image retrieval and extraction in stored large amount of video. In the experiment, we show process and number of scene change detection, and the number of video searched per retrieval time. The extracted smoking video is to submit as evidence for the police or court.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.8 no.4
• /
• pp.213-219
• /
• 2005

In this study, we try to Quantitatively assess the micropollutants in Gwangyang bay, Gamag bay and Yeoa bay, using simultaneous analytical method fir 310 chemicals. In the results, several dozen organic pollutants were detected in sampling sites, and the major chemicals detected were CH type chemicals, such as aliphatic and polycyclic compounds, and CHN(O) type chemicals, such as aromatic ammines and nitro compounds. The concentration of organic pollutants was higher in summer than in winter. However, there was no association of species of organic pollutants with season. The total concentration of pesticides at each sampling site was measured within the range of $ND{\sim}9.11{\mu}g/L$. Insecticides and fungicides of pesticide type were detected in Gwangyang bay and Gamag bay, while six kinds of endocrine disrupter were detected in southern coastal waters. From the results of this study, we should estimated that the insecticides, the fungicides, and a few of the endocrine disrupters are major pollutant factors in southern coastal waters.

• Journal of IKEEE
• /
• v.25 no.4
• /
• pp.710-715
• /
• 2021

Power line signal can show disturbances due to various causes. Typical anomalies are temporary sag/swell of the amplitude, flat topped signal, and harmonic distortions. The disturbances need to be detected and treated properly for the quality of the power signal. In this study, the power disturbances are detected using the inflection points (IP). The inflection points are defined as points where local maxima/minima or the slope changes occur. The power line signal has a fixed IP pattern since it is basically sinusoidal, and it may have additional inflection points if there is any disturbance. The disturbance is detected by comparing the IP patterns between the normal signal and distorted signal. In addition, by defining a cost function, the time instant where the disturbance happens can be decided. The computer simulation shows that the proposed method is useful for the detection of various disturbances. The simple sag or swell signal only shows the amplitude changes at the detected inflection points. However, the flat top signal and harmonically distorted signal produce additional inflection points and large values in the cost function. These results can be exploited for the further processing of disturbance classification.

• Analytical Science and Technology
• /
• v.12 no.2
• /
• pp.151-158
• /
• 1999

This study was conducted to measure the residual PCBs in sediments of 4 great rivers in Korea by gas chromatography-mass spectrometry. From the results, PCBs were positively detected in all samples. The residue levels of total PCBs in sediments in near of SS and OS were $290.87{\mu}g/kg$ and $221.11{\mu}g/kg$, respectively. The PCBs contamination may be in association with total organic compound (TOC) in sediments. Congener 66, 74, 90, 101, 105, 110, 118, 138, 149, 153, 180, 187 as IUPAC No were predominant species found in sediments and the polyCBs detected most aboundantly in sediments were tetraCBs and pentaCBs. From the study, it appears that the PCBs contamination in sediments of 4 great rivers is not serious and the analysis from enough many sites is needed for the next survey.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.4
• /
• pp.905-912
• /
• 2011

Interaocular pressure (IOP) sensor and external coil to detect the resonance frequency of the IOP sensor are designed and implemented using MEMS technology. The IOP sensor is designed using 3-D electromagnetic (EM) simulation. The resonance frequency of IOP sensor needs to be lower than that of the external coil. Additionally, the resonance frequency of the IOP sensor needs to be located near the resonance frequency of the coil to get the sufficient amplitude of phase variation. The frequency where the phase peak appears must be constant according to the distance between the IOP sensor and the external coil. From the measurement results, we demonstrated that the designed IOP sensor has the same resonance frequency with various distances between the IOP sensor and the coil.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.8
• /
• pp.44-49
• /
• 2003

In case of an extrinsic Fabry-Perot interferometric sensor, the phase compensating technique is particularly necessary in applying the interferometer to detecting acoustic emission signals because of signal-fading problems. The technique makes it possible to maintain the phase at the quadrature point. In this paper, we developed the stabilization control sensor system that is composed of a broadband light source, a tunable Fabry-Perot (F-P) filter and a control-circuit board. A tension test of a composite specimen was performed to verify if the developed system could compensate the phase change induced from the tension strain and keep the phase at the quadrature point.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.4
• /
• pp.294-299
• /
• 2009

To investigate the pollution levels and behavior of PCDD/Fs in ambient air, gaseous and particulate phase concentrations were measured at Cheongju city in 2008. The samples were collected at 3 sites (industrial, residential/commercial and rural region) by season (winter, spring and summer). The concentrations and TEQ concentrations of PCDD/DFs ranged from 0.73 to 2.43 pg/$m^3$ and from 0.007 to 0.122 pg TEQ/$m^3$, respectively. These levels were similar or lower than that of other domestic researches (from n.d. to 2.149 pg TEQ/$m^3$). The concentration of PCDD/Fs in particulate phase (from 54% to 98% against total concentration) were higher than that of gas phase. As a results of comparison of congener patterns and statistical analysis, PCDD/Fs was mainly influenced by a combustion process in ambient air, Cheongju city.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.05a
• /
• pp.275-278
• /
• 2003

본 연구에서는 축산폐수공공처리장내에 설치된 Pilot-scale SBR(유효부피,20㎥)를 이용하여 sub-cycle의 폭기/무산소구간을 최적화하기 위하여 DO를 입력으로 하여 넓은 운전조건에서 적용될 수 있는 퍼지제어기를 개발하고, 또한 부하이상을 신속히 진단하여 유입부하량을 제어할 수 있는 퍼지 시스템 제어기를 개발하였다. DO값을 입력으로 한 퍼지제어기로서 안정성과 연속성에서 우수하였으나 시스템에 따라서 소속함수의 범위를 재조정해야 할 필요가 있다. DO미분값은 변화폭이 큰 지점을 검출함으로써 지연시간(lag time)의 DO값에 관계없이 적용할 수 있는 장점이 있다. 제어기의 적용성과 안정성을 높이기 위해서는 두 가지 제어인자를 동시에 고려할 필요가 있으며 퍼지 소속함수에 대한 입력으로서 DO값과 DO미분값을 적용하였다. 그 결과 폭기구간에서 매우 안정적이고 신속하게 폭기제어지점의 검출을 보여주고 있어 최적화된 제어가 가능함을 보여준다. 현장실험결과 지연시간에서의 DO가 높고 외란이 심한 경우에도 적용될 수 있음을 보여주었다.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.23 no.3
• /
• pp.225-237
• /
• 1990

Various chemical constituents were measured from April to August 1988 at the down-ward 20 stations of Keum River, which is located in the Midwest of Korea, to understand the characteristics of water quality with respect to spatio-temporal variations of each constituent. The 24-hrs continuous measurements with 2-hrs interval were made simultaneously at station 2 near the estuary weir and station 9(Ganggyeong) of 35 km upstream from the weir in April. By the results observed for one day in April at station 2, salinity has a range of $7.88\~22.14\%_{\circ}$ and its temporal variability is identical to the pattern of tidal cycle in the neigh-bouring Kunsan Harbor. However, turbidity shows relatively high values only at an interval of 4~5 hours after the lowest salinity time, though hourly fluctuation of pH is very small. Silicate and dissolved inorganic nitrogen have inversively linear correlationships with salinity, implying the concentration of the two nutrients strongly regulated by estuarine mixing of sea and river waters. In contrast, phosphate sustains roughly a constant level over a wide salinity range and distinctly lower values than those corresponding to nitrate in the oceans. Such distributions of phosphate have been observed in some estuaries, and interpreted as driven by removal of dissolved phosphate into bottom sediments and the bufforing of phosphate by particulate matter. COD values at station 2 are relatively high in day-time(particularly afternoon) and in high-salinity periods. At station 9, saltwater intrusion was never found but water level changed to the extent of 2.5 m for one day. Although each parameter at this station exhibits very slight variations in their abundance for 24 hours compared with station 2, the contents of COD, silicate and ammonia are significantly higher than at station 2. Concentration of suspended matter is relatively high in the brackish water region up to $\~20$ km above the river mouth, probably due to strong tidal stirring of the bottom de-posits. Also, relatively high pH, COD and $O_2$ saturation at the upward stations of $40\~50$ km from the weir are presumably attributable to active photosynthesis of plants in the region. In general, COD and nutrients except phosphate are higher values at the upper stations than in the estuary zone, and show the highest abundances in July nearly at all stations. Finally, in the estuarine region tidal mixing of sea-river waters seems to be an important factor controlling the distributions of turbidity, COD, silicate and nitrate as well as salinity. However, water quality in the upward fresh-water zone is remarkably variable according to months or seasons.