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박상환(Sang-Hwan Park),윤성수(Sung-Su Yun),이동식(Dong-Shik Lee),김홍진(Hong-Jin Kim),최준혁(Joon-Hyuk Choi),김종연(Jong-Yeon Kim) 대한외과학회 2007 Annals of Surgical Treatment and Research(ASRT) Vol.73 No.1
Purpose: Liver cell damage after ischemia and reperfusion injury has been a major cause of death after liver surgery. Yet there have been no exact and practical guidelines for assessing liver cell damage after ischemia and reperfusion injury. The aim of this study was to estimate the liver cell viability after ischemia and reperfusion injury. Methods: A 70% partial liver occlusion model with employing Spraque Dawley Rats was used. The ATP content of the liver tissue, the palmitic acid metabolic rate and the histologic change (H/E, TUNEL stain) were all measured at 30 minute intervals to assess liver cell viability during 120 minutes of ischemia. At 24 hours reperfusion after 30, 60 and 120 minutes ischemia, the same parameters and the AST/ALT level in the blood were measured. Results: The ATP content was decreased below 20% compared to normal liver after ischemia, but there were no significant changes in the histology and the palmitic acid metabolic rate during 120 minutes ischemia. At 24 hours reperfusion after 30, 60 and 120 minutes ischemia, the ATP content was decreased to around 50% in all the groups and the palmitic acid metabolic rate was decreased 90.9±2.4%, 80.0±5.3% and 79.1±7.7%, respectively, compared to the control liver. But histologic change was not as great as the change in the ATP content and the palmitic acid metabolic rate. Conclusion: Judging by these results, liver has relatively good tolerance during ischemia, but after reperfusion, the liver showed damage depending on the duration of ischemia. This study might be very helpful as a guide line of liver damage after ischemia and reperfusion in both clinical practice and basic research.
설계기준 분석 방법에 의한 지역사회 청소년 흡연율 추정
박순우,이상원,박정한,윤연옥,이원기,김종연,Park, Soon-Woo,Lee, Sang-Won,Park, Jung Han,Yun, Yeon-Ok,Lee, Won-Kee,Kim, Jong-Yeon 대한예방의학회 2006 예방의학회지 Vol.39 No.4
Objectives: This study was conducted to estimate the unbiased smoking prevalence and its standard errors among adolescents in a large city in Korea, by design-based analysis. Methods: All the students in Daegu city were stratified by grade, gender and region, and then schools as primary sampling units (PSU) were selected by probability proportional to size (PPS) sampling. One or two classes were sampled randomly from each grade, from 5th grade in elementary schools to the 3rd grade in high schools. The students anonymously completed a standardized self-administered questionnaire from October to December 2004. The total number of respondents was 8,480 in the final analysis, excluding the third graders in the general high schools because of incomplete sampling. The sampling weight was calculated for each student after post-stratification adjustment, with adjustment being made for the missing cases. The data were analyzed with Stata 8.0 with consideration of PSU, weighting and the strata variables. Results: The smoking prevalence (%) and standard errors for male students from the fifth grade in elementary schools to the second grade in high schools were $0.93{\pm}0.47,\;1.83{\pm}0.74,\;3.16{\pm}1.00,\;5.12{\pm}1.02,\;10.86{\pm}1.13,\;15.63{\pm}2.44\;and\;17.96{\pm}2.67$, and those for the female students were $0.28{\pm}0.28,\;1.17{\pm}0.73,\;3.13{\pm}0.60,\;1.45{\pm}0.58,\;3.94{\pm}0.92,\;8.75{\pm}1.86\;and\;10.04{\pm}1.70$, sequentially. Conclusions: The smoking prevalence from this study was much higher than those from the other conventional studies conducted in Korea. The point estimates and standard errors from the design-based analysis were different from those of the model-based analysis. These findings suggest the importance of design-based analysis to estimate unbiased prevalence and standard errors in complex survey data and this method is recommended to apply to future surveys for determining the smoking prevalence for specific population.
주기적 파형의 (波形) 고조파 (高調波) 분석 및 합성에 관한 실험 장비의 개발
이대준(Dai Joon Lee),박종연(Jong Yun Park) 대한공업교육학회 1994 대한공업교육학회지 Vol.19 No.2
This study is for improving the students` learning effect using a system for the harmonic analysis and synthesis of periodic waveforms. Checking the LC tesonance phenomena in harmonic analyzer, we can obtain the resonance frequency varing the inductance L. When the values of inductance can be varied with substituted by G1C using OP-Amps. The harmonic synthesizer is constitute of summing networks, Test results are used to verify those of simulator. And also we confirm the developed system is much available for the `electric theory` subject in technical high school.
음향 공명 제거 및 과도 상태 전류를 제한시킨 고출력 메탈 헬라이드 램프용 전자식 안정기 설계
김기남(Ki-Nam Kim),박종연(Jong-Yun Park),최영민(Young-Min Choi) 대한전기학회 2010 전기학회논문지 Vol.59 No.5
This paper presents the design of acoustic resonance free and over current limit during transient state consideration electronic ballast for 1.5㎾ Metal-Halide Lamp(MHL) that employs frequency modulation (FM) technique. The proposed ballast consists of a Full-Bridge(FB) rectifier, a passive power factor correction (PFC) circuit, a full-bridge inverter, an ignitor using LC resonance and a control circuit for frequency modulation. The frequency modulation technique is the most effective solution to eliminate acoustic resonance among other technique. It spreads power spectrum of lamp to reduce the supplied power spectrum under the energy level of eigen-value frequency. Moreover, the proposed ballast is simple and cost effective above conventional ballast. A new PFC circuit is proposed which combines with LCD type and PCSR filter. A new PFC circuit has higher PF and lower THD than conventional LCD type and secure high reliability. Finally, to protected switching components in transient state, the surge current into ballast is limited by increase the switching frequency. Performance of the proposed ballast was validated through computer simulation using Pspice, experimentation and by applying it to an electronic ballast for a prototype 1.5㎾ MHL.
조도 제어용 ASK 및 FSK 전력선 모뎀의 성능 평가
박종연,최현희 강원대학교 정보통신연구소 2008 정보통신논문지 Vol.12 No.-
In this paper, two type of power line modems are evaluated to realize the lamp control system using the power line communication. One is FSK modem using DS/SS and the other is the manchester coded ASK modem. Both modems apply (7,4) hamming code to correct errors. There are two kinds of used loads ; the electronic ballast and the magnetic ballast. The Electronic ballast is for a 250Watt HID lamp, a 50watt florescent lamp and a 50watt induction lamp. The Magnetic ballast is for a 250watt HID lamp. Bit errors are measured between the main modem and the ASK or the FSK sub-modems in loads at equal distances. As a result, it is estimated that the FSK modem is more appropriate than the ASK modem in terms of the lamp dimming system. And we also concluded that the (7,4) hamming code is not suitable for ASK application In the lamp control system.
박종연,안종구,이양범 울산대학교 1982 연구논문집 Vol.13 No.2
Weaver's analog단측파대 변조기의 원리와 Digital신호처리 기법을 적용하여 Digital단측파대 변조기의 특성을 computer simulation에 의하여 구하였다. 이러한 Digital단측파대 변조기는 주파수 분할 다중통신(FDM)시스템과 시분할 다중통신(TDM)시스템의 다중변환 시스템으로 사용할 수 있으며 Group band(60~108KHz)다중통신을 예로서 상호변환을 설명하고 시스템의 신호 대 잡음비(SNR)를 구하였다. The digital Weaver's single side band(SSB) modulator is simulated, using its corresponding theory and digital processing techniques. The simulated digital Weaver's modulator is used as a main part of the transmultiplexer which converts time division multiplexer(TDM) system to frequency division multiplexer(FDM) system. The digital filters are designed for this purpose and the SNR of the overall system is calculated.
레이저 수술용 금속 기관내 튜브를 이용한 기관내 삽관후 발생한 기종격증과 피하기종
박종연,황재현,윤미자 대한마취과학회 1998 Korean Journal of Anesthesiology Vol.34 No.5
We report a case of pneumomediastinum, subcutaneous emphysema, and mild pneumothorax that occurred after endotracheal intubation with a metallic endotracheal tube for the laser operation. Fortunately, pneumomediastinum and subcutaneous emphysema were self-limited. But potentially life-threatening events such as upper airway obstruction, tension pneumothorax, pneumopericardium, mediastinitis might be possible. These complications may result from mucosal perforation of upper airway. The use of a tube with rigid and relatively narrower internal diameter than polyvinylchloride endotracheal tube, tough endotracheal intubation technique, high peak inspiratory pressure, suction technique and negative pressure are included as complication factors. (Korean J Anesthesiol 1998; 34: 1046∼1050)