• Journal of Power Electronics
• /
• v.16 no.5
• /
• pp.1650-1660
• /
• 2016

This paper proposes a compensator to eliminate the DC bias of inductor current. This method utilizes an average-current sensing technique to detect the DC bias of inductor current. A small signal model of the DC bias compensation loop is derived. It is shown that the DC bias has a one-pole relationship with the duty cycle of the left side leading lag. By considering the pole produced by the dual active bridge (DAB) converter and the pole produced by the average-current sensing module, a one-pole-one-zero digital compensation method is given. By using this method, the DC bias is eliminated, and the stability of the compensation loop is ensured. The performance of the proposed compensator is verified with a 1.2-kW DAB converter prototype.

• Broadcasting and Media Magazine
• /
• v.11 no.1
• /
• pp.78-85
• /
• 2006

Cognitive radio is a paradigm for wireless communication in which either network of wireless node itself changes particular transmission or reception parameters to execute its tasks efficiently without interfering with the licensed users. This paper represents a performance of the cognitive radio technology on dual polarized MIMO system using six-port receiver. Six-port technology is well known direct conversion receiver. In this paper, a six-port phase discriminator based polarization signal separation is shown. That is, the SER(Symbol Error Rate) performance is improved using polarization separator and simple receiver architecture is proposed applying six-port receiver. The six-port technology has priority to adapt changeable frequency system and variable environments for cognitive radio. In general, dual polarized MIMO system has good capacity and quality using polarization separator [1].

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.10
• /
• pp.993-1001
• /
• 2001

Experimental investigation on the performance of dual-evaporator refrigeration system with an ejector has been carried out. In this study, a hydrofluorocarbon (HFC) refrigerant R134a is chosen as a working fluid. The condenser and two-evaporators are made as concentric double pipes with counter-flow type heat exchangers. Experiments were performed by changing the inlet and outlet temperatures of secondary fluids entering condenser, high-pressure evaporator and low-pressure evaporator at test conditions keeping a constant compressor speed. When the external conditions (inlet temperatures of secondary fluid entering condenser and one evaporator) are fixed, results show that coefficient of performance (COP) increases as the inlet temperature of the other evaporator rises. It is also shown that the COP decreases as the mass flaw rate ratio of suction fluid to motive fluid increases. The COP of dual-evaporator refrigeration system with an ejector is superior to that of a single-evaporator vapor compression system by 3 to 6%.

• Journal of Electrical Engineering and Technology
• /
• v.2 no.1
• /
• pp.50-54
• /
• 2007

In this paper, a dual-servo type VCM (Voice Coil Motor) for the measuring of nano-level displacement and small thrust is proposed and developed. The shape of VCM for improving the resolution of displacement and ensuring a large displacement are presented. The FEM (finite element method) is utilized to analyze the characteristics of VCM that produces linear driving thrust and satisfies the thrust that the measurement system requires. The Prototype is fabricated and an experiment is performed in order to measure displacement. As a result of simulation and testing, the proposed VCM shows the applicable possibility for a nano-level measurement system.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.23 no.3
• /
• pp.247-253
• /
• 2015

Platform standardization is widely used in commercial auto industries and other industries to acquire cost reduction as well as high reliability. This paper reviews some application examples and estimates expected effect of Korean army's platform standardization for combat system and combat support system. Also, military platform standardization based on utilization of commercial vehicles has been studied with the standard vehicles used in Korean army. It is estimated that outstanding results may be achieved if a dual platform, the public and military platforms, is utilized. So, when the strategy of the military transportation system is decided, "dual use" concept is necessary and this could maximize the effect of the military strategy reinforcement.

• Proceedings of the KIPE Conference
• /
• 2015.07a
• /
• pp.235-236
• /
• 2015

본 논문에서는 universal line 입력 및 전 부하영역에서 영전압 스위칭(Zero Voltage Switching) 보장을 통한 500kHz 고 주파수 구동의 Dual Mode control LLC 컨버터를 제안한다. 제안 회로는 전 부하영역에서의 ZVS(영전압 스위칭)보장으로 고주파 구동이 가능하여 전원회로의 부피 중 상당량을 차지하는 수동소자의 부피를 대폭 저감 할 수 있다. 또한, 소용량 전원회로는 PFC(Power Factor Correction)의 규제가 없기 때문에 universal line 입력에 대응이 가능해야하므로, 제안회로는 변화하는 입력전압과 출력전류에 따라 PFM과 PWM의 두 가지 모드로 동작하여 universal line 입력 및 전 부하 영역에서 정확한 출력전압 제어가 가능하다. 최종적으로 제안 회로의 타당성 검증을 위하여 60W급 adapter의 전원회로를 위한 시작품을 제작하여 고찰된 실험 결과를 제시한다.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.37 no.5 s.113
• /
• pp.63-69
• /
• 2005

This study was performed to introduce recently developed polyvinylamine as a wet-end process and paper strength improving aids. As a retention and drainage aids, high cationic charged polyvinylamine was more effective at the BCTMP and ONP stock condition than LBKP stock condition. As a dry tensile strength aid, dual system of polyvinylamine with anionic polyacrylamide was the best at the LBKP or ONP stock conditions. On the other hand, polyvinyl amine alone was better than dual system of polyvinylamine with anionic polyacrylamide at the BCTMP condition. As a wet tensile strength aid, polyvinylamine single system and dual system of polyvinylamine with anionic polyacrylamide were good at LBKP, BCTMP and ONP stock conditions. However, poly(aminoamide)-epichlorohydrin resin was good at LBKP and ONP stock conditions but efficiency of poly(aminoamide)-epichlorohydrin resin was remarkably decreased at BCTMP stock condition.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.6
• /
• pp.239-242
• /
• 2016

In this paper, we proposed the dual curved lens of concave type. HDPE (High Density Polyethylene) used to fabricate the dual curved lens. The dual curved lens consisted of two concave structures. Role of two concave structures is to beam uniform and expansion. A small concave structure has the greater curvature than big concave structure. The dual curved lens will apply to millimeter imaging system. We measured the dual curved lens performance using 250 GHz VDI source. And we simulated the dual curved lens using ZEMAX. Fabricated lens have a good performance for beam uniform and expansion.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.9
• /
• pp.887-891
• /
• 2013

Human rights at poor working condition is the severe problem in modern manufacturing system. The industrial dual-arm robot is being developed to meet these social issues fundamentally. The dual-arm robot can work instead of human workers. We developed the new dual-arm robot for manufacturing mobile phone and TV. It has advantages such as the solo controller for both arms, the human sized body and arms. The software platform for the industrial dual-arm robot is being developed which has strength in its convenience and intelligence compared to conventional the robot software platforms. Here the development of the dual-arm robot software platform is introduced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.11
• /
• pp.898-905
• /
• 2018

In this work, infrared targets for a developed hardware-in-the-loop simulation(HILS) system are proposed for a performance test of a dual-sensor imaging seeker equipped with an infrared and a visible sensor that can lock and track for ground and air targets. This integrated system is composed of 100 modules of heat and light sources to simulate various kinds of target and the trajectory of moving targets based on scenarios. It is possible to simulate not only the position, velocity, and direction for these targets but also background clutter and jamming environments. The design and measurement results of an infrared target, such as the HILS system configuration, developed for testing and evaluation of a dual-sensor imaging seeker are described. In the future, it is planned to test the lock-on and tracking performance of an imaging seeker equipped with single or dual sensors dynamically in real time based on a simulation flight scenario in the developed HILS system.