전력시스템의 전압변동 현상과 최적 전압보상 방안에 관한 연구

김승환,유인근 창원대학교 산업기술연구소 2001 産技硏論文集 Vol.15 No.-

In resent years, electric power quality has become an important issue in power systems. A rapid development of high technology society encompassing sensitive loads raise the increasing dependence of higher quality electric power, and consumers request the high reliability in electric power than ever before. Consumers wanted mainly the reduction of duration of voltage variation in the past. Generally, power quality is voltage, frequency, reliability(outage) etc. The sources and characteristics for voltage variation of power system and the effects for electric equipment of voltage variation are analized in this paper. The voltage variation and compensation countermeasures of west Kyung-nam province in KEPCO system have been simulated using PSS/e. The voltage drop is measured in the case of SLGF(single line ground fault) and TPSCF(three phase short circuit fault), at 345kV transmission line and bus, 154kV, 23kV bus and 6.6kV bus of industry. The voltage compensation characteristic of Generator, transformer and Static condenser, and the voltage compensation limits value of the compensation methods are observed, and the results of measurement at the condition of normal and abnormal(the status of 1 line open) of the 2 lines radial power systems are also analyzed. In the abnormal power system, the adaption of S.V.C, with method of high speed and continuous controls is simulated for voltage compensation. It is shown that the S.V.C is the best voltage compensation method in loop power system or 2 lines radial system.

Early Percutaneous Catheter Drainage Reduces Hospital Stay but Not Mortality in Patients with Pyogenic Liver Abscess

( Chang Hun Lee ),( Yun Chae Lee ),( Jaehee Park ),( Song Yi Yu ),( Hun Gil Jo ),( Jae Sun Song ),( Gum Mo Jung ),( Yong Keun Cho ),( Eun Young Cho ),( In Hee Kim ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: To investigate the factors associated with prolonged hospital stay and mortality among patients with pyogenic liver abscess (PLA) who underwent percutaneous drainage (PCD). Methods: We retrospectively reviewed data from PLA patients admitted from 2005 to 2018 at three tertiary hospitals in Jeonbuk province. We selected patients who underwent PCD during the admission period and early PCD was defined whether the procedure was done within 3 days of admission. Results: Among 655 patients diagnosed with PLA, 366 patients who underwent PCD were enrolled for the study. The patients had a mean age of 65.5 ± 14.7 years, and mean maximal diameter of the hepatic abscess was 6.1 ± 2.6 cm and 71.9% of the lesion was single. Next, two groups were divided depending on the time period of PCD and 269 patients (73.5%) underwent PCD within 3 days of hospitalization. In baseline characteristics, early PCD group was significantly higher in the number of abscess as well as the maximal abscess diameter. However, hospitalization period was significantly lower in the early PCD group though in-hospital mortality was not different. We checked laboratory results at 1 week after the admission and CRP levels were significantly lower in the early PCD group. We further analyzed the factors related to the long-term hospitalization more than 14 days. In multivariate analysis, underlying diabetes, lower albumin levels, and PCD inserted after 3 days of admission were independent factors associated with prolonged hospital stay. Conclusions: Early PCD facilitated improvement of inflammatory laboratory markers and shortened the hospital stay. Early PCD may be beneficial in patients with PLA.

전기설비에서의 고조파 영향분석과 저감대책에 관한 연구

박석훈,유인근 창원대학교 산업기술연구소 2001 産技硏論文集 Vol.15 No.-

In recent years there has been an increasing usage of switching devices such as SCR, IGBT, Power TR and etc, in home appliances and industrial machinery. A lot of harmonics are generated through the switching processes, which cause considerable harmonic distortion in the network and may result severe damages to the precise power equipments. This work presents the performance characteristic of digital watt-hour meter under the harmonics of voltage and current. Each waveform involved is different in magnitude, phase, and THD(Total Harmonic Distortion). It is possible to generate harmonics and control those waveforms using RTDS. Tests were performed on a selected sample of three-phase digital watt-hour meter which is coupled with data acquisition system via RS 485/232 converter. The percentage error rate of the watt-hour meter is compared for both sinusoidal and non-sinusoidal cases and the results are given. This paper also deals with observations of events that occur in the Dimmer circuits and phase control which could affect harmonics problem to the commercial power system. In order to reduce the effect of harmonics and design filters, Solid State Relay Dimmer(SCRs or TRIACs) and Noise Filter are described, and the effects of harmonics is also analyzed.

EMTDC를 이용한 전력계통의 전압저감현상 해석

유인근,김창회 國立 昌原大學校 産業技術硏究所 1999 産技硏論文集 Vol.13 No.-

In this paper, the voltage sags, which are momentary dips in voltage and usually caused by faults or sudden increases of major loads, of actual and model power systems are simulated using EMTDC. The simulation results on the several sorts of faults, that is, single phase to ground faults and three phase ground faults are analyzed and discussed in detail. It is obvious to say that both the configuration of transmission systems and the distance of fault point from the interested bus heavily affect the voltage sags, and the connection type of transformer also has explicit influence on the voltage sags. It is strongly emphasized, through the test results of the study, that the analysis of actual power systems using EMTDC is needed in order to evaluate the present situations on voltage profiles precisely, and consider those results in operation and expansion planning of the power systems. Sort of useful informations, which can be used for the purpose of practical applications, are also extracted and given in detail.

산업용 전력시스템의 전압저감내성 해석 및 대책

유인근,지화수 國立 昌原大學校 産業技術硏究所 1999 産技硏論文集 Vol.13 No.-

This paper describes the causes of voltage sags in industrial plants, their impacts on equipment operation, and the possible countermeasures. The voltage sags analysis of power systems under faulted conditions provides very important information regarding the sensitivity of different types of industrial equipment, adjustable speed drive controls, programmable logic control, motor contactor and so on. The ability to predict voltage sag characteristics offers a unique opportunity to evaluate alternate configurations and prevent problems with optimum supply and ride-though specifications. Currently, the voltage sags are facing an increasing concern of industrial plants due to increasing automation facilities as electronic controllers, which are more sensitive to voltage sags than other loads. Several countermeasures are chosen and simulated in order to improve voltage sags of industrial plant and the simulation results are discussed in detail.

EMTDC를 이용한 산업체 수전설비의 전압저감현상 해석

유인근,김기대 國立 昌原大學校 産業技術硏究所 1999 産技硏論文集 Vol.13 No.-

Voltage sags are characterized by magnitude and duration, and are very important to industrial customers because they can cause tripping of important equipments, facilities and processes. This paper presents the study results of an industrial power systems voltage sag phenomena caused by not only the faults but also the steady state operation of some particular facilities using EMTDC. Electrical furnaces and induction motors, which cause serious load fluctuation in operation and starting, have been simulated for a steel manufacturing company which is located in Changwon Industrial Complex. Both single-line ground faults and three-phase faults are modeled for several cases, and the magnitude and duration of voltage sags are analysed in detail in order to discuss the effects of the faults to the voltage sags of the industrial power system. The frequency of voltage sag, however, is ignored because it mainly depends on the fault frequency of real power systems. The magnitude of motor capacity has been changed for the purpose of studying the voltage sags of adjacent buses and the capacity of arc furnaces have been varied to study the effects of facilities itself.

전력계통에서의 전문가 시스템을 도입한 발전기 기동정지 계획 산법에 관한 연구

유인근 國立 昌原大學校 産業技術硏究所 1989 産技硏論文集 Vol.3 No.-

An expert system based algorithm to solve the problem of short-term unit commitment is presented. The general scheme of the algorithm is Hybrid Dynamic Programming which includes a couple of modified techniques in comparison with Dynamic Programming, namely, search-and-selection method based on the priority order of generation units, and state reconciliation approach that consider the secondary states as well as the primary one in the solution procedure by dynamic programing for the purpose of guarantee on the existence of feasible solution all the time and the computational problem is solved using load variation rates of each step, and security function is also introduced to take generation system reliability into account. In addition to the above-mentioned scheme, an expert system approach is applied to assist operators in scheduling the operation of generating units. Especially, for the effective handling of several necessary constraints which must be considered in the solution procedure and have a great influence on the results, that is, start-up and down cost of units, minimum and maximum run time, minimum down time, the number of possible start-up of a generating unit daily, transmission line over-load and crew constraint etc., the knowledge of an experienced power system operator were taken into account through an expert system rule base which provides information in response to questions raised by system operator to improve the results by indicating how to adjust input data and relax the constraints. The effectiveness of the proposed algorithm has been demonstrated by applying it to a model power system.

정상인에서 부분적 수면박탈이 수면구조에 미치는 영향

왕성근,이정규,이충숙,최하석,유남재,정인형,이선우 충남대학교 의과대학 지역사회의학연구소 1992 충남의대잡지 Vol.19 No.2

To identify the effects of partial sleep deprivation on the sleep structure, the authors performed polysomnographic study for 9 healthy young adults. The subjects were college students, ranging in age from 20 to 25 years, without personal past or present histories of medical, neurological, or psychiatric illness and suffering from current sleep disturbance or parasomomnias. Sleep records were analyzed according to the criteria of Rechtschaffen and Kales' manual and tried paired t-test. The results were summarized as follows. 1. As for sleep parameters, total sleep time(TST), REM latency and REM duration were not changed significantly during deprivation period and recovery period compared with baseline. Sleep efficiency increased significantly during deprivation period and recovery period compaired with baseline, and sleep latency and WASO were shortened significantly during deprivation period and recovery period compared with baseline. 2. As for sleep structure, 1) The absolute value(minutes) of stage 1 decreased significantly during deprivation period and first recovery night compared with baseline, and the relative value(percentage) of stage 1 decreased significantly during deprivation period and recovery period compared with baseline. 2) The absolute value(minutes) of stage 2 decreased significantly during deprivation period compared with baseline, and the relative value(percentage) of stage 2 decreased significantly during deprivation period and first recovery night compared with baseline. 3) The absolute value(minutes) of slow wave sleep were not changed significantly during deprivation period and recovery period compared with baseline, and the relative value(percentage) of slow wave sleep increased significantly during recovery period compared with baseline. 4) The absolute value(minutes) of REM sleep decreased significantly during deprivation period compared with baseline, and the relative value(percentage) of REM sleep decreased significantly in the first deprivation night but, were not changed significantly during recovery period compared with baseline.

Imageable Antigen‐Presenting Gold Nanoparticle Vaccines for Effective Cancer Immunotherapy In Vivo

Lee, In‐,Hyun,Kwon, Ho‐,Keun,An, Sukyung,Kim, Daejin,Kim, Sunghyun,Yu, Mi Kyung,Lee, Jae‐,Hyuk,Lee, Tae‐,Sup,Im, Sin‐,Hyeog,Jon, Sangyong WILEY‐VCH Verlag 2012 Angewandte Chemie Vol.124 No.35

<P><B>Goldnanopartikel</B> (AuNPs) wurden mit einem rot fluoreszierenden Protein (RFP, rosafarbene Formen im Bild) als Modellantigen und einem Oligonukleotid (CpG), das die Immunantwort stimuliert, funktionalisiert. Diese AuNPs ermöglichten bei Verwendung als Krebsimpfstoffe in einem Tumormodell den effizienten Transport eines Antigens zum Zielort, die Verfolgung des Impfstoffs mithilfe nichtinvasiver klinischer Bildgebung sowie Vorbeugung und Behandlung von Krebs.</P>

Wavelet 변환을 이용한 단기부하 예측기법에 관한 연구

김봉태,유인근 창원대학교 산업기술연구소 2001 産技硏論文集 Vol.15 No.-

This paper proposes a novel wavelet transform based algorithm for the seasonal load forecasting. In this paper, Daubechies DB2, DB4 and DB10 wavelet transforms are adopted to predict the seasonal loads and the numerical results reveal that certain wavelet components can effectively be used to identify the load characteristics in electric power systems. The wavelet coefficients associated with certain frequency and tiem localization are adjusted using the conventional multiple regression method and then reconstructed in order to forecast the final loads through a five-scale synthesis technique. The outcome of the study clearly indicates that the wavelet transform approach can be used as an attractive and effective means of the seasonal load forecasting.