Jae-hyun Hwang

Two new methods are described in implementing power factor correction. They are simple, easy to implement, cost effective and provide comparable or better performance over the existing schemes. The first method is a generalization of the nonlinear carrier control method which could be applied to all second order power converters: the buck, boost and flyback power converters with either leading-edge or trailing-edge modulation. Equations are derived for each of these six topologies, and simulatio

The efficiency of a pre-/post-switching regulator degrades as the power delivered to the load lessens. To improve the efficiency of a pre-/post-switching regulator at light loads, a green-mode function is proposed in this paper. By using a green-mode function, efficiency can be improved at lower power consumption by 8 to 25 percentage points depending on the power level being delivered to the load. Experimental results are provided to confirm the improvement in the efficiency.

Adipose tissue secretes many adipokines which contribute to various metabolic processes, such as blood pressure, glucose homeostasis, inflammation and angiogenesis. The biology of adipose tissue in an obese individual is abnormally altered in a manner that increases the body’s vulnerability to immune diseases, such as psoriasis. Psoriasis is considered a chronic inflammatory skin disease which is closely associated with being overweight and obese. Additionally, secretion of leptin, a type of adi

This paper introduces a new 8 pin PFC/PWM controller using input current shaping topology. The input current shaping PFC topology previously proposed is revisited in this paper. With an innovative circuit, we were able to reduce the pin count and external components in a cost sensitive market place. The controller is analyzed and verified experimentally.

A pulse width modulation-voltage source inverter (PW M-VSI) outputs distorted voltage that has a bad effect on torque and speed. Also speed range of traction motor is limited on output voltage. In order to solve problem, this paper propose the control method. It can adjust the DC-link voltage of PWM-VSI by using a two phase interleaved bidirectional DC-DC converter. Also the method can response high power of vehicle. By replacing the diode of output with the switch, the system can operate the re

In the conventional power trunk locking system for vehicles, the mechanical latch is used. However, because the mechanical latch is exposed on the trunk exterior, it is vulnerable to damage during use. Therefore, this article proposes a novel power trunk locking system using electromagnetic force to remove protrusion of conventional trunk locking system. The proposed system consists of contact plate, magnetic module, gear train, and cinching motor. The electromagnetic force from the permanent ma

최근의 데이터센터 서버에서는 네트워크 처리 오버헤드를 줄이기 위해 다이렉트 캐시 액세스 (DCA) 기법이 사용되고 있다. 그러나 기존의 플로우 스티어링 기법들이 DCA나 멀티코어 환경을 고려하지 않아 네트워크 응용의 최적 성능을 달성하지 못한다. 본 논문에서는 aRFS+ 라는 새로운 플로우 스티어링 기법을 제안하며, 다음의 세 가지 설계사항을 고려하였다. 첫째, 네트워크 응용에 대해 DCA가 적용되는 NUMA 노드의 CPU 코어에서 동작되도록 하는 애플리케이션 스티어링 기법을 적용하였다. 둘째, 멀티코어 환경의 이점을 극대화하기 위해 네트워크 패킷 수신처리를 위한 코어와 응용 코어가 분리되도록 하였다. 더불어 두 코어가 같은 DCA 적용 NUMA 노드 코어에서 선택되도록 하여 높은 CPU 효율을 달성하도록 하였다. 셋째, 매 패킷에 대한 메모리 관리 오버헤드를 줄이는 최적화 기법을 도입하였다. 이를 통해 기존 기법 대비 최대 약 60%의 성능 향상을 보임을 확인하였다.