• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.5
• /
• pp.404-413
• /
• 2017

This paper suggests an isolated PFC converter for electric vehicle (EV) chargers with wide-output voltage range. The proposed converter is based on voltage-fed full-bridge structure. All the harmonic and output controls are performed by secondary and primary switches are only operated under a fixed frequency with 50% duty-ratio. In addition, harmonic modulation technique is adopted to obtain a near unity power factor without input current monitoring. The feasibility of the proposed charger has been verified with a 10-kW prototype.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.111-113
• /
• 2018

본 논문에서는 3상 듀얼 액티브 브리지 (3P-DAB) 컨버터의 경부하 조건에서 전력 변환 효율을 향상시키기 위한 효과적인 스위칭 알고리즘을 제안한다. 3P-DAB 컨버터는 교차배치 (Interleave) 구조로 인한 작은 필터 크기와 낮은 전도 손실을 얻을 수 있고, 추가적인 회로없이 소프트 스위칭이 가능하며 양방향 전력 흐름에서의 무절체 제어로 인해 고전력 애플리케이션에서 널리 사용되는 토폴로지 중 하나이다. 그러나 3P-DAB의 위상천이 방법(SPS)을 이용한 제어 방식의 경우 경부하 조건에서 영전압 스위칭(ZVS)의 실패 가능성이 높기때문에 효과적이지 않다. 본 논문에서는 SPS 제어 알고리즘과 비대칭 시비율 변조법 (Asymmetrical Pulse Width Modulation; APWM)을 연쇄적으로 사용하여, 경부하에서 스위치의 ZVS 영역을 넓히고자 한다. 3-kW의 3상 DAB 컨버터의 시작품을 구현하고 실험을 통해 제안된 방법의 효율성을 검증 하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.8B
• /
• pp.1453-1459
• /
• 2000

In this paper, the method which compensates the problem occurred in case M-ary QAM is applied to system is proposed. The conventional CMA has two problems, First, when M is larger than 4, it has a poor performance of equalizer due to a degradation of convergence property. Second, the phase of conventional CMA is distorted after convergence. To compensate these problems, we set the proper interval according to modulated signal when the signal using 16-QAM modulation method is equalized and use a different equalizing method for each interval. Using this method, the ISI is reduced and the performance of equalizing is improved. Also, the computer simulation using residual ISI shows an improved performance.

• YAKHAK HOEJI
• /
• v.56 no.4
• /
• pp.236-239
• /
• 2012

The aim of present study was to investigate the possible influence and the related mechanism of Cinnamomum cassia derived-cinnamaldehyde on the inflammation or nociception. Cinnamomum cassia was referred to be treated for common cold or dyspepsia in the traditional medicine. However, there are no reports on the antinociceptive or anti-inflammatory properties of cinnamaldehyde, the primary ingredient of Cinnamomum cassia. We hypothesized that cinnamaldehyde would play a role in the modulation of inflammation or nociception evoked by carrageenan, acetic acid or heat. Male Institute of Cancer Research mice were used and the size of edema, frequency of writhing and latency of abnormal behaviors such as licking, flicking, shaking or jumping were measured and recorded. The present study was carried out to evaluate the antiinflammatory and antinociceptive effects of cinnamaldehyde. The administration of cinnamaldehyde (30 and 100 mg/kg) inhibited carrageenan-induced paw edema only at the final phase, suggesting the blockade of synthesis or release of prostaglandins. It also reduced the frequency of the acetic acid-induced writhing reflex in mice. In addition, the administration of cinnamaldehyde prolonged the latency for extraordinary reaction at the hot plate in mice. In conclusion, cinnamaldehyde has anti-inflammatory and analgesic properties and is a potential therapeutic for inflammation and nociception.

• Journal of the Korea Society of Computer and Information
• /
• v.3 no.4
• /
• pp.78-85
• /
• 1998

In this paper, we analyzed the performances for FH/CPFSK system with limiter - discriminator detection and integrate-and-dump post-detection filtering under thermal noise and partial-band jamming noise. And, we considered intersymbol interference - related SNR and differential phase parameters for all eight of the possible adjacent bit data patterns, FM noise clicks for evaluating FH/CPFSK and CPFSK systems. In result, the optimum modulation index h was 0.7 and the optimum value of bandwidth-time product D was 1.0. Next, when we considered the thermal noise under the partial-band jamming, the thermal noise significantly influenced the error probability of system below 20dB approximately but could ignore above 20dB.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.05a
• /
• pp.319-323
• /
• 2003

In this paper, we propose a hybrid transceiver for underwater acoustic communication, which allows the system to reduce complexity and increase robustness in time variant underwater channel environments. It is designed in the digital domain except for amplifiers and implemented by using a multiple digital signal processors (DSPs) system. The digital modulation technique is quadrature phase shift keying (QPSK) and frame synchronization is an energy (non-coherent) detection scheme based on the quadrature receiver structure. DSP implementation is based on block data parallel architecture (BDPA). We shaw experimental results in th? underwater anechoic basin at KRISO. The results indicate that the frame synchronization is performed without PLL. Also, we shaw that the adaptive equalizer can compensate frame synchronization error and the correction capability is dependent on the length of equalizer.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.3
• /
• pp.1137-1145
• /
• 2017

This paper proposes the dead time effect compensation algorithm using proportional resonant controller in pulse width modulation inverter of motor drive. To avoid a short circuit in the dc link, the dead time of the switch device is surely required. However, the dead time effect causes the phase current distortions, torque pulsations, and degradations of control performance. To solve these problems, the output current including ripple components on the synchronous reference frame and stationary reference frame are analyzed in detail. As a results, the distorted synchronous d-and q-axis currents contain the 6th, 12th, and the higher harmonic components due to the influence of dead time effect. In this paper, a new dead time effect compensation algorithm using proportional resonant controller is also proposed to reduce the output current harmonics due to the dead time and nonlinear characteristics of the switching devices. The proposed compensation algorithm does not require any additional hardware and the offline experimental measurements. The experimental results are presented to demonstrate the effectiveness of the proposed dead time effect compensation algorithm.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.1
• /
• pp.44-53
• /
• 2020

A bridgeless single-stage AC-DC converter for wireless power charging systems is proposed. This converter is composed of a PFC stage and a three-level hybrid DC-DC stage. The proposed converter can control the wide output voltage (200-450 V_DC) by the variable link voltage and the pulse-width voltage applied to the primary resonant circuit due to the phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and the total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype was fabricated and validated through experimental results and analysis.

• International Journal of Aeronautical and Space Sciences
• /
• v.13 no.1
• /
• pp.64-73
• /
• 2012

Pointing stability of high precision observation satellites must satisfy the stringent requirements to perform at a designed level. As even a small vibrational disturbance can result in severe degradation of the optical performance, the effects of inorbit vibrational environment on the performance of optical payload must be predicted and analyzed in the design phase in order to ensure that the requirements imposed on the payload are fully met. In this paper, an integrated framework for the evaluation of the performance of optical payloads is developed. The developed simulation tool comprises of the reaction wheel induced disturbance model, state space model of a structure in modal form and Cassegrain reflector model. The performance degradation of the optical system due to jitter is expressed by using modulation transfer function (MTF) and image simulation. Moreover, vibration isolator model is also added to show the effectiveness of using a vibration isolator for the elimination of the effects of jitter in the acquisition of an image.

• Proceedings of the KIPE Conference
• /
• 2002.11a
• /
• pp.171-174
• /
• 2002

This paper deals with a novel method in order to analyze the harmonic characteristics in the multi-level inverter. Generally, the magnitude of harmonic components is different according to the carrier PWM techniques, modulation Index(Mi), and the level of multi-level inverter The previous papers analyzed the harmonic characteristics from the viewpoint of the space vector. Hence, the calculation of the harmonic vector becomes difficult and complex in 4-level or more than S-level. However, the proposed method of this paper reduced an amount of calculation and simplified the process of calculation by using the relationship between reference voltage and output phase voltage to load neutral. This paper analyzed the harmonic and it is applied to the multi-carrier PWM techniques in 5- level and other-level of cascaded inverter system.