• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1927-1929
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• 2000

PD indicates the inception and progress of degradation of solid insulation system, so it has been used to determine degradation of insulation. PD provides means for detection and recognition of defects. However, there is still marked difficult to recognize defects by PD methods. In this paper, we investigated properties of PD in solid insulation by using statistical method with surface discharge, electrical tree and void discharge with source of discharge, we used statistical parameters of PD distributions specified such as $H_n(q)$, $H_{an}(\phi)$, $H_n(\phi)$, $H_a(\phi)$. The parameters induced from its specified distributions are average discharge, average repetition rate, Skewness, Kurtosis, asymmetry and correlation. From the parameters, we classified PD patterns and built up DB(data-base).

• 한국재료학회지
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• 제26권3호
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• pp.123-129
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• 2016

The morphology, crystal structure and size of aerosol nanoparticles generated by erosion of electrodes made of different materials (titanium, copper and aluminum) in a multi-spark discharge generator were investigated. The aerosol nanoparticle synthesis was carried out in air atmosphere at a capacitor stored energy of 6 J, a repetition rate of discharge of 0.5 Hz and a gas flow velocity of 5.4 m/s. The aerosol nanoparticles were generated in the form of oxides and had various morphologies: agglomerates of primary particles of $TiO_2$ and $Al_2O_3$ or aggregates of primary particles of $Cu_2O$. The average size of the primary nanoparticles ranged between 6.3 and 7.4 nm for the three substances studied. The average size of the agglomerates and aggregates varied in a wide interval from 24.6 nm for $Cu_2O$ to 46.1 nm for $Al_2O_3$.

• 정보학연구
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• 제6권1호
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• pp.65-70
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• 2003

본 논문에서 우리는 변압기의 부분방전형태를 진단하기위하여 새로운 방법을 제시하였다. 웨이블렛 변화을 위하여, 다우비치 필터가 사용되어졌다. 우리는 3개의 전극 종류(침대평판자극, IEC전극, 보이드 전극)마다 고주파 전류신호에 관한 통계적인 특징 파라메터(최대값, 평균값, 분산, 왜도, 첨쇄도)를 추출하기위하여 사용하였다. 역시 이들 계수들은 변압기내 내부부분방전의 신호의 정체를 알기위하여 사용되어졌다. 그 결과로서 고주파전류신호의 진폭과 평균값의 비교로부터 우리는 IEC electrode> Void electrode> Needle-Plane electrode의 결과를 얻었다. 반면에 왜도와 첨쇄도의 경우, 우리는 Void electrode> IEC electrode> Needle-Plane electrode을 얻었다.

• 환경영향평가
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• 제21권3호
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• pp.339-352
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• 2012

Total maximum daily load have been implemented and indicated that nonpoint discharge coeffients in flow duration curve were 0.50 of Normal flow duration ($Q_{185}$) and 0.15 of low flow duration($Q_{275}$). By using SWAT, nonpoint discharge coefficients are studied with the conditions of the instream flow and the rainfall in two study areas. The nonpoint discharge coefficient average of BOD and TP for normal flows duration in 3 years are 0.32~0.36 and 0.28~0.31. For the low flow duration, the nonpoint discharge coefficient avergae of BOD and TP were 0.10~0.12 and 0.10~0.11. These are lower than the coefficients of total maximum load regulation. There are big differences between one of regulation and one of SWAT for the normal flow duration. With the consideration of rainfall condition, the nonpoint discharge coefficient of flood flow duration are influenced on the amount of rainfalls. However, the nonpoint discharge coefficients of normal flow duration and low flow duration are not effected by the rainfall condition. Since the spatial distribution and geomorphological characteristics could be considered with SWAT, the estimation of nonpoint discharge coefficient in watershed model is better method than the use of the recommended number in the regulation.

• Journal of Biosystems Engineering
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• 제8권2호
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• pp.26-38
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• 1983

Binder harvesters introduced to Korea were originally designed to be used for Japonica varieties which are highly resistant to shattering. In order to improve the performance of the binder to Indica varieties which are easily shattered and have shorter stem, mechanical modifications of the binder are inevitable. Shattering losses of the binder can be classified into two major parts; one incurred before and one after binding operations. The latter has been evaluated as great as the former. Previous studies indicated that the high discharge losses resulted from a great impact force of the discharge arm on the rice bundle during the discharge process. This study was intended to theoretically analyze the discharge mechanism of four-bar linkage. For this purpose, two commercially available binder harvesters having a four-bar linkage as a discharge mechanism were analyzed. Using the results from the motion analysis and the other structural constraints of the machines, they were modified and experimentally compared with the machines without modification to see whether any decrease in grain losses was obtained. The results obtained in this study are summarized as follows: 1. The path, velocity and acceleration of discharge arm were computer analyzed by vector analysis. Using results of the analysis and intrinsic constraints of the binder, discharge mechanism was modified to reduce the impact force on bundle by discharge arm in the range where the discharge performance was not deteriorated. This modification of the discharge mechanism could be done with an aid of four-bar linkage synthesis technique. As a result, average velocity and acceleration of the discharge arm during the discharge process were reduced respectively by 19 percent and 33 percent for binder A, and 17 percent and 35 percent for binder B. 2. Through the modification of the discharge mechanism, discharge losses of binder A were reduced by 42-56 percent for Milyang 23, Poongsan and Hangang chal, and discharge losses of binder B were reduced by 13-20 percent for Milyang 23 and Poongsan. 3. Discharge losses were decreased as the bundle size became larger and the size effect on the decrease rate appeared more significant in the binders with modifications than in those without modifications.

• 한국학교ㆍ지역보건교육학회지
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• 제20권2호
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• pp.69-80
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• 2019

Objectives: In this study, we tried to analyze the factors affecting Length Of Stay for serious patients in Republic of Korea. Methods: The study included 139,172 serious patients in the 2012-2016 discharge details. Using the SPSS 23.0 program, we conducted a rank regression analysis with social and social demographic characteristics as control variables, medical institution characteristics and medical use characteristics as independent variables, and Average Length Of Stay as a dependent variable. Results: Average Length Of Stay for participants was found to be 9.92days. And the location and bed size of medical institutions were not statistically significant, the hospitalization path was more urgent(B=0.43) than the outpatient (p<0.001), and there was no secondary diagnosis(B=0.35). However, Average Length Of Stay was higher (p<0.001) than there was no main surgery(B=0.80). After discharge, Average Length Of Stay for funding(B=0.43) and death(B=0.72) was long (p<0.001). Average Length Of Stay for participants was found to be 9.92days. And the location and the bed size of the medical institution were not statistically significant, and the hospitalization pass had longer Length Of Stay for emergency patients(B=0.43) than for outpatients(p<0.001). There was a longer Length Of Stay(B=0.35) than none was diagnosed. There were longer Length Of Stay(p<0.001) than there was no major surgery(B=0.80). After discharge, the outpatients had longer Average Length Of Stay(B=0.43) and deaths(B=0.72) than those who returned home(p<0.001). Conclusion: As a result of analyzing the factors affecting Average Length Of Stay of the participants, it was confirmed that regardless of the location and bed size of medical institutions, hospitalization route, department diagnosis, main surgery, and whereabouts after discharge. Therefore, appropriate interventions and necessary support must be provided so that efficient Length Of Stay can be managed according to the medical use characteristics of serious patient.

• 한국환경과학회지
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• 제22권2호
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• pp.251-257
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• 2013

Discharge data examine the process of hydrologic cycle and used significantly in water resource planning and irrigation and flood control planning. It makes high quality discharge data, they carry out research on standard and method of discharge measurement, and equipment improvement. Now various flow meters are utilized to make discharge data in Korea. However, accuracy of equipment and exprerimental research data from measurement are not enough. ADCP(Acoustic Doppler Current Profiler) have been introduced and utilized for flow measurements since the end of 1980's. ADCP flow method is a formal method for flow measurement can easily applyd to relatively large rivers gradually recognized. This equipment can measure the non-contact three-dimensional velocity and water depth data very quickly and efficiently. Also, spatial and temporal resolution of the data is more accurate than any other flow measurement methods which measure flow rate by velocity - area measurement method. In this paper, the velocity is measured using various flow meter and verified the effectiveness by applying from the ADCP in Geum-river. Various flow meters which are med for discharge measurements are VALEPORT002, FLOW TRACKER, PRICE AA and ADCP. The average of five times flow measurement result by ADCP was $10.412m^3/s$, with a standard deviation of 0.68. The repeat test by ADCP and comparison between ADCP and other flow devices to verify the most import factor, flow measurement accuracy. In the result, repeat test of the ADCP showed similar values, flow values were similar to other velocity device results and the average error is 7.7%.

• 한국안전학회지
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• 제25권5호
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• pp.22-26
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• 2010

The ignitability(minimum ignition energy, MIE) of a suspended dust clouds is very important aspect of technical safety indices. This paper reported the experimental results dealing with the influence of discharge circuit on the MIE of a suspended dust clouds. The movement of a suspended dust clouds was also observed with the high speed camera. The Hartmann vertical-tube apparatus(MIKE-3) described in the international standard of IEC and Polypropylene (PP, 50% volume-average, D50: $761{\mu}m$) resin powders were used in this experiment. The following results were obtained: (1) the MIE of a suspended PP powder depended markedly on the discharge circuit; in other words, when a resistor was connected in series with the discharge sparking circuit(RC), the lowest value(31mJ) of MIE was obtained for a suspended PP powder comparison with the other circuits(C circuit; 370mJ or LC circuit; 71mJ). (2) the discharge duration time is more important than other factors with regard to MIE of a suspended PP powder.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1995년도 추계학술발표회논문집
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• pp.85-95
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• 1995

This paper describes a diagnosis of transformer by ultrasonic signal due to partial discharge. The ultrasonic signal can be measured when partial discharge is generated in a real transformer. The trend of partial discharge in transformer was estimated by counting the number of ultrasonic signals until insulation paper in the point-to-plane electrode is destroyed. The number of ultrasonic signals is closely related to the number of the electrical signals by partial discharge. The trend of the ultrasonic signal number could easily be distinguished by taking moving average.

• Applied Science and Convergence Technology
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• 제26권4호
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• pp.74-78
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• 2017

The discharge characteristics of the radio frequency (RF) surface dielectric barrier discharge have been simulated for the investigation of the ratio of the ion transit time to the RF period. From one-dimensional particle-in-cell (PIC) simulation for a planar dielectric barrier discharge (DBD), it was observed that the high-frequency driving voltage confines the ions in the plasma because of a shorter RF period than the ion transit time. For two-dimensional surface dielectric barrier discharges, a fluid simulation is performed to investigate the characteristics of RF discharges from 1 MHz to 40 MHz. The ratio of the peak density to the average density decreases with the increasing frequency, and the spatiotemporal discharge patterns change abruptly with the change in the ratio of ion transit time to the RF period.