• 청정기술
• /
• 제6권2호
• /
• pp.85-92
• /
• 2000

제강슬래그의 재활용 범위를 확대하기 위한 방안으로 제강슬래그를 여재로 이용하여 축산폐수 처리효과를 조사하였다. 제강슬래그를 접촉용 여재로 활용한 순환식 폐수처리 장치를 이용하여 기존의 시설에서 처리된 축산폐수를 재처리한 결과 pH는 제강슬래그의 특성으로 인하여 상승하였으며 질소와 인의 농도를 효과적으로 낮추었으며 COD와 BOD도 감소하였다. 축산단지의 현장실험 결과 여재로 사용한 제강슬래그는 부유물질을 효과적으로 제거하였으며 유입 농도의 갑작스런 변화를 완화하였다. COD와 BOD의 경우 재처리수에서 항상 유입 폐수보다 낮아졌으나 유입수의 농도에 영향을 받았다. 에이징된 제강슬래그를 열처리 한 경우 free-CaO 성분의 증가로 열처리를 하지 않은 경우에 비하여 처리수의 pH 상승 정도가 커졌으며 인 제거 특성도 향상되었다.

• 대한의용생체공학회:의공학회지
• /
• 제37권5호
• /
• pp.153-160
• /
• 2016

This study proposes an algorithm for removal of CPR artifact in order that automated external defibrillator (AED) can effectively diagnose ECG rhythm during cardiopulmonary resuscitation (CPR). Current AED required to interrupt chest compression for reliable rhythm analysis to avoid the effect of artifacts produced by CPR. However even temporarily interruption of chest compression during CPR adversely affects the probability of restoration of spontaneous circulation (ROSC) and survival after the delivery of the shock. Therefore, we proposed a method for removal of CPR artifacts using least mean square (LMS) filter. The removal of the CPR artifacts would enable compressions to continue during AED rhythm analysis, thereby increasing the likelihood of resuscitation success. It was tested on 31 segments of shockable and 300 segments of non-shockable ECG signals recorded from three pigs during CPR. In the result, sensitivity (Se) and specificity (Sp) analysis on the test segments showed values of Se = 3.2%, Sp = 66.0% and Se = 96.8%, Sp = 98.7% in the case of unfiltered and filtered signals during CPR. In conclusion, it was shown that the proposed method can be a useful tool to exactly diagnose the ECG rhythm during the CPR.

• 공업화학
• /
• 제22권4호
• /
• pp.400-404
• /
• 2011

백금이 코팅된 메탈 필터 소재의 NOx, soot 산화반응의 안정성 및 활성에 대하여 연구하였다. NOx와 soot 산화실험은 독립 또는 동시에 반응시킨 조건으로 수행되었다. 그 결과, 백금이 코팅된 소재는 20%의 NO의 $NO_2$로의 전환반응, 약 10%의 NOx 분해반응 그리고 soot의 완전산화반응이 진행됨을 보였다. Soot 산화반응은 $NO_2$의 생성으로 인하여 반응온도가 더 저온으로(약 $30^{\circ}C$) 이동할 수 있었다. 코팅 소재는 $Pt/Al_2O_3$ 또는 $Pt/TiO_2$ 촉매보다 표면구조의 안정성으로 인하여 열충격에 대한 내구성이 우수하였다.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 2009년도 IWAIT
• /
• pp.529-534
• /
• 2009

This paper reports a non-photorealistic rendering method for creating stream pattern from an input image. Our method extracts potential stream pattern in the given image. The proposed approach uses a shock filter based on a partial difference equation(PDE) which is implemented by applying a selective dilation and erosion processes. However, unlike the traditional first order solution to the PDE, we employ a second order scheme and compensate for the undesired diffusive effects caused by a viscosity form. The selection of dilation or erosion for a pixel is based on an edge detector computed from a structure tensor. By adding noises on to the input image, our method also can generate stream pattern even if there is less texture in some area. The experimental results show that the stream pattern is extracted very well.

• Journal of Power Electronics
• /
• 제13권1호
• /
• pp.51-58
• /
• 2013

This paper proposes the power conversion mechanism of a bailer-charge-transfer zero-current-switching (CT-ZCS) circuit. The operation modes are analyzed and researched using state trajectory equations. The topology of CT-ZCS based on soft-switching inverters offers some merits such as: tracking the input reference signal dynamically, bearing load shock and short circuit, multiplying inverter N+1 redundancy parallel, coordinating power balance for easy control, and soft-switching commutation for high efficiency and large capacity. These advantages are distinctive from conventional inverter topologies and are especially demanded in AC drives: new energy generation and grid, distributed generation systems, switching power amplifier, active power filter, and reactive power compensation and so on. Prototype is manufactured and experiment results show the feasibility and dynamic voltage-tracking characteristics of the topology.

• 전기학회논문지
• /
• 제56권8호
• /
• pp.1397-1404
• /
• 2007

It is important to measure the resistive component separately from the total leakage current at power distribution line. It is because electric disasters such as electric shock and fire are caused mainly by the resistive component of the total leakage current. In this paper, a new theory for measuring the resistive component separately from the total leakage current is suggested, and is embodied to an actual circuit using operational amplifiers, analog switch and R-C low pass filter. Through experiments for various cases containing both the resistive and capacitive leakage currents, the suggested algorithm is confirmed to be able to measure the resistive leakage current within 4.1% of error even when the capacitive leakage current is much bigger than the resistive one. The suggested method is expected to lower the total cost because it can be realized using simple and cheap devices, and implies the measuring time can be possibly reduced because the resistive leakage current is computed exactly from the signals during only a half period of power voltage.

• 천문학회보
• /
• 제44권2호
• /
• pp.42.1-42.1
• /
• 2019

We investigate a collapsing granule event and the associated excitation of waves in the photosphere and chromosphere. Our observations were carried out by using the Fast Imaging Solar Spectrograph and the TiO 7057Å Broadband Filter Imager of the 1.6 meter Goode Solar Telescope of Big Bear Solar Observatory. During our observations, we found a granule which became significantly darker than neighboring granules. The edge of the granule collapsed within several minutes. After the collapse, transient oscillations occurred in the photospheric and chromospheric layers. The dominant period of the oscillations is close to 4.5 minutes in the photosphere and 4 minutes in the chromosphere. Moreover, in the Ca II-0.5Å raster image, we observed brightenings which are considered as the manifestation of shock waves. Based on our results, we suggest that the impulsive collapse of a granule can generate upward-propagating acoustic waves in the solar quiet region that ultimately develop into shocks.

• 천문학회지
• /
• 제56권2호
• /
• pp.213-224
• /
• 2023

Type II solar radio bursts show frequency drifts from high to low over time. They have been known as a signature of coronal shock associated with Coronal Mass Ejections (CMEs) and/or flares, which cause an abrupt change in the space environment near the Earth (space weather). Therefore, early detection of type II bursts is important for forecasting of space weather. In this study, we develop a deep-learning (DL) model for the automatic detection of type II bursts. For this purpose, we adopted a 1-D Convolution Neutral Network (CNN) as it is well-suited for processing spatiotemporal information within the applied data set. We utilized a total of 286 radio burst spectrum images obtained by Hiraiso Radio Spectrograph (HiRAS) from 1991 and 2012, along with 231 spectrum images without the bursts from 2009 to 2015, to recognizes type II bursts. The burst types were labeled manually according to their spectra features in an answer table. Subsequently, we applied the 1-D CNN technique to the spectrum images using two filter windows with different size along time axis. To develop the DL model, we randomly selected 412 spectrum images (80%) for training and validation. The train history shows that both train and validation losses drop rapidly, while train and validation accuracies increased within approximately 100 epoches. For evaluation of the model's performance, we used 105 test images (20%) and employed a contingence table. It is found that false alarm ratio (FAR) and critical success index (CSI) were 0.14 and 0.83, respectively. Furthermore, we confirmed above result by adopting five-fold cross-validation method, in which we re-sampled five groups randomly. The estimated mean FAR and CSI of the five groups were 0.05 and 0.87, respectively. For experimental purposes, we applied our proposed model to 85 HiRAS type II radio bursts listed in the NGDC catalogue from 2009 to 2016 and 184 quiet (no bursts) spectrum images before and after the type II bursts. As a result, our model successfully detected 79 events (93%) of type II events. This results demonstrates, for the first time, that the 1-D CNN algorithm is useful for detecting type II bursts.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.400-403
• /
• 2002

The fundamental experiments for measuring soft x-ray characteristics from the vacuum capillary are described. These experiments were primarily performed in order to generate line spectra such as x-ray lasers. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, a turbo-molecular pump, and a radiation tube with a capillary. A high-voltage condenser of 200 nF in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. During the discharge, weakly ionized plasma forms on the inner and outer sides of a capillary. In the present work, the pump evacuates air from the tube with a pressure of about 1 mPa, and a demountable capillary was developed in order to measure x-ray spectra according to changes in the capillary length. In this capillary, the anode (target) and cathode elements can be changed corresponding to the objectives. The capillary diameter is 2.0 mm, and the length is adjusted from 1 to 50 mm. When a capillary with aluminum anode and cathode electrodes was employed, both the cathode voltage and the discharge current almost displayed damped oscillations. The peak values of the voltage and current increased when the charging voltage was increased, and their maximum values were -10.8 kV and 4.7 kA, respectively. The x-ray durations observed by a 1.6 ${\mu}$m aluminum filter were less than 30 ${\mu}$s, and we detected the aluminum characteristic x-ray intensity using a 6.8 ${\mu}$m aluminum filter. In the spectrum measurement, two sets of aluminum and titanium electrodes were employed, and we observed multi-line spectra. The line photon energies seldom varied according to changes in the condenser charging voltage and to changes in the electrode element. In the case where the titanium electrode was employed, the line number decreased with corresponding decreases in the capillary length. Compared with incoherent visible light, these rays from the capillary were diffracted and diffused greatly after passing through two slits.

• Journal of Microbiology and Biotechnology
• /
• 제27권10호
• /
• pp.1808-1819
• /
• 2017

Knowledge on the functional characteristics and temporal variation of anaerobic bacterial populations is important for better understanding of the microbial process of two-stage anaerobic reactors. However, owing to the high diversity of anaerobic bacteria, close attention should be prioritized to the frequently abundant bacteria that were defined as core bacteria and putatively functionally important. In this study, using MiSeq sequencing technology, the core bacterial community of 98 operational taxonomic units (OTUs) was determined in a two-stage upflow blanket filter reactor treating pharmaceutical wastewater. The core bacterial community accounted for 61.66% of the total sequences and accurately predicted the sample location in the principal coordinates analysis scatter plot as the total bacterial OTUs did. The core bacterial community in the first-stage (FS) and second-stage (SS) reactors were generally distinct, in that the FS core bacterial community was indicated to be more related to a higher-level fermentation process, and the SS core bacterial community contained more microbes in syntrophic cooperation with methanogens. Moreover, the different responses of the FS and SS core bacterial communities to the temperature shock and influent disturbance caused by solid contamination were fully investigated. Co-occurring analysis at the Order level implied that Bacteroidales, Selenomonadales, Anaerolineales, Syneristales, and Thermotogales might play key roles in anaerobic digestion due to their high abundance and tight correlation with other microbes. These findings advance our knowledge about the core bacterial community and its temporal variability for future comparative research and improvement of the two-stage anaerobic system operation.