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철도차량용 보조전원장치의 전향제어를 이용한 Flicker 제어
박채운(Park Chae-Woon),신형진(Shin Hyung-Jin),조국춘(Cho Kook-Choon),원충연(Won Chung-Yun) 한국철도학회 1999 한국철도학회 학술발표대회논문집 Vol.- No.-
The auxiliary power supply system for passenger service of railway car has been developed from MA(Motor-Alternator) to CVCF Inverter (Static Inverter). Generally, a customer wants to apply the new control method and device for auxiliary power supply of railcar. However, if the auxiliary power supply is supplied to extended existing line, the maintenance cost of the old system is less expensive than new developed system, so, the customer specifies that the auxiliary power supply has compatibility with existing one completely. At that time, the hardware is nearly same as existing system except small changes of accessories for better performance. This paper describes the flicker control using feed-forward method of auxiliary power supply system for new 50 electric railcars, which are delivered to Korean National Railroad (KNR) Kwa-chon Line. The existing power supply system has damping resistor box to stabilize the DC input (1.5 ㎸). At this time, for better system efficiency the new system has not include resistor box but new control method including feed-forward control is applied. This control algorithm realizes the better stabilization of input power compared to tile result of the existing system, which includes resistor box.
조국춘(Cho Goog-Chun),박채운(Park Chae-Woon),최종묵(Choi Jong-Mook) 한국철도학회 1999 한국철도학회 학술발표대회논문집 Vol.- No.-
Three phase full bridge rectifier has been used to obtain de voltage from three phase ac voltage source. The rectifier system has drawbacks that power factor is low and power flow is unidirectional. Therefore, when de voltage increases due to regeneration of power, the dynamic resistor for dissipation of regeneration power must be installed. But three phase PWM converter can be controlled to operate with unity power factor and bidirectional power flow. Therefore when the PWM converter is used as dc supply system, the dissipating resistor is not necessary. On this thesis, in order to design a controller having good performance, the three phase PWM converter is completely modeled by using circuit DQ-transformation and thus a general and simple instructive equivalent circuit is obtained; the inductor set becomes a second order gyrator-coupled system and three phase inverter becomes a transformer as well. Under given phase angle(α) and modulation index(MI) of the three phase inverter, the de and ac characteristics are obtained by analysis of the transformed equivalent circuit. The validity of the equivalent circuit is confirmed through PSPICE simulation. And based on the de and ac characteristics a controller with unity power factor is proposed.
온도감응중합체 및 트립신 처리에 의한 중간엽줄기세포의 계대 배양 비교
배소현 ( So Hyun Bae,),박채운 ( Chae Woon Park ),손혜경 ( Hye Kyung Son ),전춘주 ( Choon Ju Jeon ),김호언 ( Ho Eon Kim ) 한국조직공학·재생의학회 2007 조직공학과 재생의학 Vol.4 No.3
Mesenchymal stem cells (MSCs) possess extraordinary proliferation and broad differentiation potential, drawing much attention from the fields of regenerative medicine and tissue engineering. These stem cell potentials, however, are known to steadily decrease during ex vivo expansion. Upon serial passage in vitro, MSCs exhibit significant aging-related transformation, the progression of which is presumably accelerated by the routine use of trypsin. In this study, we have investigated whether a new passage method with using RepCellTM, a temperatureresponsive polymer (TRP)-coated culture dish, is superior, in terms of proliferative potential, to the traditional trypsin-mediated method. The results showed that the cells passaged five times by trypsin treatment assumed much older cell morphology and grew more slowly than those passaged with RepCellTM, suggesting that trypsin might exert deleterious effects on proliferative potential of MSCs. In addition, DNA microarray-based differential transcriptional profiling revealed a notable, but not significant, difference in gene expression between these two cell populations, indicating a slow deposition of trypsin-mediated molecular changes. In conclusion, TRP-mediated passage would be a preferred method for ex vivo expansion of MSCs without risking damage to the stem cell properties.
김경원(Kyung-Won Kim),홍순찬(Soon-Chan Hong),유종걸(Jong-Gul Yoo),김상균(Sang-Kyun Kim),박채운(Chae-Woon Park) 전력전자학회 2001 전력전자학술대회 논문집 Vol.2001 No.7
This paper proposes a modified a conduction mode for controlling the output voltage magnitude of three-phase square-wave VSIs with an R-L load. From the viewpoint of both power capacity and switching losses, three-phase square-wave inverters are now used in most high power systems. When the square-wave VSI is driven with a conduction mode to control the magnitude of output voltages, interval over than half period is operated with 180?conduction mode and the other interval with 120?conduction mode. In 120?conduction mode operation, two output terminals are connected to DC supply and the third one remains open. The potential of this open terminal will depend on the load characteristics and is unpredictable except the case of pure resistive loads. To cope this problem, we propose the modified a conduction mode.
단상 인버터로 구성된 3상 구형파 인버터의 고조파 저감기법에 관한 연구
이주훈(Ju-Hoon Lee),조승연(Seung-Youn Cho),홍순찬(Soon-Chao Hong),이인환(In-Hwan Lee),황용하(Yong-Ha Hwang),박채운(Chae-Woon Park),한성수(Sung-Soo Han) 전력전자학회 2000 전력전자학술대회 논문집 Vol.2000 No.11
This paper deal with the harmonic reduction technique in three-phase square-wave inverter system formed by single-phase inverter. To reduce the harmonics, six single-phase inverters are used for forming multi-phase inverter and zig-zag connected output transformer for eliminating the harmonic 6(2k-l)±1 orders. And an ac filter is furnished at output side. Computer simulations show that the THD of the output voltage can be reduced immensely.