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정우창(Woo-Chang Jung),강경우(Kyung-Woo Kang),유종걸(Jong-Gul Yoo),홍순찬(Soon-Chan Hong) 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.11
In this paper, a new energy recovery circuit for AC PDP(Plasma Display Panel) is proposed to decrease a sustain voltage and voltage stress on switching elements. In the proposed circuit, two auxiliary capacitors are connected directly to the power source through switching elements and inductors when ground potential is suppied to the panel. Therefore, the voltage across auxiliary capacitors can be increased by turns over the half of the source voltage. Because the intrinsic capacitance of PDP is charged sufficiently from the auxiliary capacitors, the level of sustain voltage and the voltage stress on the switching devices are decreased. To verify the validity of the proposed energy recovery circuit, computer simulations using PSpice program are carried out
정우창(Woo-Chang Jung),강경우(Kyung-Woo Kang),유종걸(Jong-Gul Yoo),고종선(Jong-Sun Ko),홍순찬(Soon-Chan Hong) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
A new multi-level type energy recovery sustaining driver for AC PDP(Plasma Display Panel) is proposed in this paper. The multi-level driver has been developed to reduce the voltage stress on switching elements. Comparing the proposed driver with the conventional multi-level driver, 4 switching elements, 4 diodes, and two auxiliary capacitors are eliminated in the viewpoint of circuit structure. Moreover, the voltage stress on switching elements is more reduced and the sustain period is extended. To verify the validity of the proposed energy recovery circuit, computer simulations using PSpice program are carried out.
기구학적 모델링과 지자기센서 최소사용을 결합한 IMU 기반 하지 위치추정
정우창(Woo Chang Jung),이정근(Jung Keun Lee) 제어로봇시스템학회 2020 제어·로봇·시스템학회 논문지 Vol.26 No.4
The lower limb positions of pedestrians are an important physical attribute required in various fields, such as augmented reality, sports science, and physical medicine and rehabilitation. Due to the advantages of the wearability of inertial measurement units (IMUs), IMU-based position estimation of human lower limbs has attracted much attention. In IMU-based estimation, magnetometers are usually used to estimate the headings of tracking objects, e.g., lower limb segments. However, the heading estimation performance can be compromised by magnetic disturbances. In particular, in the case of pedestrian lower limb tracking, a foot-attached magnetometer is exposed to severe magnetic disturbances caused by the wires or structural materials embedded in the building floor or ground, resulting in significant position estimation errors. This paper proposes an IMU-based position estimation of lower limbs via a combination of kinematic modeling with minimal utilization of magnetometers. The proposed method uses only a thigh-attached magnetometer to minimize the effects of magnetic disturbance occurring on the ground or floor and estimates the heading of the entire lower limb using only the thigh magnetometer through kinematic modeling. As our treadmill walking test results, the averaged heading estimation error and position estimation error were 3.4° and 7.2 m, respectively, outperforming the conventional methods both with multiple magnetometers and without any magnetometers.
AC PDP용 멀티레벨 에너지 회생회로의 개선에 관한 연구
정우창(Woo-Chang Jung),강경우(Kyoung-Woo Kang),정대택,유종걸(Jong-Gul Yoo),고종선(Jong-Sun Ko),홍순찬(Soon-Chan Hong) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
A new multi-level type energy recovery sustaining driver for AC PDP(Plasma Display Panel) is proposed in this paper. The hard switching is eliminated using CIM(Current Injection Method) and thus the voltage stress on switching elements is more reduced. The Vs/2 sustain period is eliminated as much Vs sustain period can be extended. Moreover, Comparing the proposed sustain driver with the conventional multi-level driver, 4 switching elements, and 2 auxiliary capacitors are eliminated in the viewpoint of circuit structure. To verify the validity of the proposed energy recovery circuit, computer simulations using PSpice program are carried out.
종양유발 인체 감마허피스바이러스를 제어하는 천연 식물화합물의 항바이러스 작용
정우창(Woo-Chang Cheong),송문정(Moon Jung Song) 고려대학교 생명자원연구소 2017 생명자원연구 Vol.25 No.-
Abstract Gammaherpesviruses are a subtype of the Herpesviridae family. They undergo lytic replication in epithelial cells and establish latency in lymphocytes, leading to persistent infection in the host. Human gammaherpesviruses are called oncogenic viruses, as their infections are associated with various types of cancers. Therefore, the control of human gammaherpesviruses is important for the treatment of virus-associated cancers and inhibition of virus infection in the host. Although there are antiviral treatments against human gammaherpesviruses, toxicity issues and the emergence of drug resistance are limitations to their use. To overcome these issues, studies are focusing on identifying alternative treatments, such as natural phytochemical products with antiviral activity against gammaherpesviruses. In this paper, we review the characteristic features of two human gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV), and their related diseases. The current state of research on natural phytochemicals with anti-gammaherpesvirus activity is then discussed. Finally, we further discuss the limitations and prospects of anti-gammaherpesvirus research.
홍순찬,정우창,강경우,유종걸,Hong, Soon-Chang,Jung, Woo-Chong,Kang, Kyoung-Woo,Yoo, Jong-Gul 한국조명전기설비학회 2005 조명·전기설비학회논문지 Vol.19 No.4
본 연구는 AC PDP(Plasma Display Panel)용 멀티레벨 에너지 회수회로에 관한 연구로서, 기존 멀티레벨 구동회로의 문제점을 해결한 새로운 멀티레벨 구동회로를 제안한다. 기존 멀티레벨 구동회로는 Weber회로에서 나타나는 스위칭 소자의 전압 및 전류 스트레스를 개선하였지만 공진 인덕터와 기생 커패시턴스에 의한 기생공진전류가 존재하고 하드스위칭이 발생하며 또한 천이구간이 다소 긴 문제점이 있다. 제안 회로는 사용소자의 수를 줄여 회로를 간단히 하였으며, 기생공진전류를 제거하여 회로 동작의 안정성을 높였다. 또한 CIM(Current Injection Method) 을 사용하여 하드스위칭 문제를 해결하였으며 Vs/2 유지구간을 제거하여 동작주파수를 증가시킬 수 있도록 하였다. 제안 회로의 유용성을 입증하기 위해 모드별로 동작을 해석하였으며, PSpice프로그램을 이용하여 시뮬레이션하고 그 결과를 확인하였다. This paper proposes a novel multi-level energy recovery sustaining driver for AC PDP(Plasma Display Panel), which solves the problems of the conventional multi-level sustaining driver. While the conventional circuit improves the voltage md current stress of the switching elements in Weber circuit not only there are parasitic resonant currents between resonant inductors and parasitic capacitance and hard switching, but also the changing period between 0 and sustain voltage is too long. Comparing the proposed circuit with the conventional circuit, the number of components are reduced and the parasitic resonant currents in resonant inductors are eliminated Moreover the hard switching problem is solved by using CIM(Current Injection Method) and the operating frequency will be high as much as possible by removing Vs/2 sustain period. And the circuit operations of the proposed circuit are analyzed for each mode and the validity is verified by the simulations using PSpice program.
이정근 ( Jung-keun Lee ),정우창 ( Woo-chang Jung ) 한국센서학회 2019 센서학회지 Vol.28 No.1
Inertial measurement units (IMUs) are widely used for wearable motion-capturing systems in the fields of biomechanics and robotics. When the IMUs are combined with optical motion sensors (hereafter, OPTs) for their complementary capabilities, it is necessary to align the coordinate system orientations between the IMU and OPT. In this study, we compare the application of two coordinate transformation- based orientation alignment methods between two coordinate systems. The first method (M1) applies angular velocity coordinate transformation, while the other method (M2) applies gyroscopic angle coordinate transformation. In M1 and M2, the angular velocities and angles, respectively, are acquired during random movement for a least-square algorithm to determine the alignment matrix between the two coordinate systems. The performance of each method is evaluated under various conditions according to the type of motion during measurement, number of data points, amount of noise, and the alignment matrix. The results show that M1 is free from drift errors, while drift errors are present in most cases where M2 is applied. Thus, this study indicates that M1 has a far superior performance than M2 for the alignment of IMU and OPT coordinate systems for motion analysis.