• 정보통신설비학회논문지
• /
• 제10권4호
• /
• pp.135-142
• /
• 2011

This paper proposes a performance evaluation method for power consumption of set-top box (STB) stand-by mode transition schemes. A stand-by mode transition scheme characterizes the timing of mode transition. The timing of mode transition affects the duration of stand-by mode operation, and the power consumptions of STB as well. Recently a fast stand-by mode transition scheme (FMT) has been proposed based on user input for selecting the device to be connected to TV. In this paper, we evaluate power consumption of FMT and a conventional mode transition scheme. For the computation of the duration of stand-by mode operation, the user input events are modeled as Poisson process. Simulation results based on the modeling reveals that the proposed scheme is more effective in power saving than the conventional scheme by up to 30%.

• 무역학회지
• /
• 제45권5호
• /
• pp.55-74
• /
• 2020

This study examines the policy direction and specific countermeasures for addressing possible port labour issues from the perspective of Just Transition which may be raised by closing coal fired power plants in Korea. Current energy transition policy and port labour policy in Korea are reviewed and case studies in the countries which has experienced closure of coal fired power plants are undertaken. Although it varies from country to country, a similar approach was found that the employment problem of coal fired power plant closures and measures based on Just Transition regime to mitigate the negative impacts that occur in the region are the key to successful transition. It is suggested that countermeasures for port labour should be institutionalized for providing stakeholders with legal stability covering labours not only directly employed by the plants but also employed in entities in the whole supply chains.

• 전력전자학회논문지
• /
• 제21권3호
• /
• pp.238-248
• /
• 2016

In this study, an automatic command mode transition strategy of direct power control (DPC) is proposed for permanent magnet synchronous generators (PMSGs) medium-voltage (MV) offshore wind turbines (WTs). Benchmarking against the control methods are performed based on a three-level neutral-point-clamped (NPC) back-to-back type voltage source converter (VSC). The ramping rate criterion of complex power is utilized to select the switching vector in DPC for a three-level NPC converter. With a grid command and an MPPT mode transition strategy, the proposed control method automatically controls the generated output power to satisfy a grid requirement from the hierarchical wind farm controller. The automatic command mode transition strategy of DPC is confirmed through PLECS simulations based on Matlab. The simulation result of the automatic mode transition strategy shows that the proposed control method of VOC and DPC achieves a much shorter transient time of generated output power than the conventional control methods of MPPT and VOC under a step response. The proposed control method helps provide a good dynamic performance for PMSGs MV offshore WTs, thereby generating high quality output power.

• 한국정보처리학회논문지
• /
• 제7권8호
• /
• pp.2520-2527
• /
• 2000

전력 평가를 위한 전이 밀도 전파에 대한 개선된 방법을 제안한다. 제로 지연 모델을 위한 전력 평가는 전력 소모의 하한 경계 값에 대한 적절한 기준이다. 전력 예측을 위한 하한 값으로 제로 지연 모델을 사용한 전이 전파 방법에 대한 연구가 있지만 전이 밀도 전파 과정 중 잉여 요소들을 제거하지 못하였다. 본 연구에서는 전이 전파 밀도 동작을 분석함에 의하여 잉여 요소들을 제거할 수 있는 향상된 신호 전이 밀도 예측 기법을 제안한다. 실험에 의하면 제안된 방법이 기존의 방법에 비하여 상대적으로 양호한 예측 정확도를 나타낸다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 추계종합학술대회 논문집
• /
• pp.240-243
• /
• 1999

This paper presents a data-dependent precharge suppression(DPS) D-flip-flop(DFF) with precharge suppression scheme according to data-transition probability The main feature of the DPS DFF is that precharge is suppressed when there is no data transition. The proposed DPS DFF consumes less power than the conventional Yuan-Svensson's true single phase clocking(TSPC) DFF when the data-transition probability is low. The simulation result shows that the power consumption is reduced by 42.2 % when the data-transition probability is 30%.

• Nuclear Engineering and Technology
• /
• 제53권8호
• /
• pp.2610-2615
• /
• 2021

The prediction of irradiation-induced transition temperature shift for RPV steels is an important method for long term operation of nuclear power plant. Based on the irradiation embrittlement data, an irradiation-induced transition temperature shift prediction model is developed with machine learning method XGBoost. Then the residual, standard deviation and predicted value vs. measured value analysis are conducted to analyze the accuracy of this model. At last, Cu content threshold and saturation values analysis, temperature dependence, Ni/Cu dependence and flux effect are given to verify the reliability. Those results show that the prediction model developed with XGBoost has high accuracy for predicting the irradiation embrittlement trend of RPV steel. The prediction results are consistent with the current understanding of RPV embrittlement mechanism.

• 전력전자학회논문지
• /
• 제27권4호
• /
• pp.356-366
• /
• 2022

This paper presents a mode transition method that applies frequency compensation technique of an LLC resonant converter for stable mode transition. LLC resonant converters used in various applications require high efficiency and high power density. However, because of circuit property, a wider voltage gain range equates to a greater circuit loss, so maintaining high efficiency at all voltage gain ranges is difficult. In this case, full bridge-half bridge mode transition method can be used, which maintains high efficiency even in a wide voltage gain range. However, this method causes damage to the circuit through overcurrent by the mode transition. This study analyzes the cause of the problem and proposes a mode transition method that applies frequency compensation technique to solve the problem. The proposed method verifies the stable transition through simulation analysis and experimental results.

• KIEE International Transactions on Power Engineering
• /
• 제5A권4호
• /
• pp.344-349
• /
• 2005

In conventional small signal stability analysis, the system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of the state matrix. However, when a system contains switching elements such as FACTS equipments, it becomes a non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is performed by means of eigenvalue analysis of the system's periodic transition matrix based on the discrete system analysis method. In this paper, the RCF (Resistive Companion Form) method is used to analyze the small signal stability of a non-continuous system including switching elements. Applying the RCF method to the differential and integral equations of the power system, generator, controllers and FACTS equipments including switching devices should be modeled in the form of state transition equations. From this state transition matrix, eigenvalues that are mapped into unit circles can be computed precisely.

• 정보과학회 논문지
• /
• 제43권7호
• /
• pp.763-772
• /
• 2016

다양한 센서가 부착된 스마트 폰의 보급으로 상황인지 어플리케이션 시장의 규모가 발달하고 있다. 하지만, 한정된 전력으로 인해 원활한 서비스를 제공받기는 어렵다. 상황인지 어플리케이션 관점에서 볼 때, 컨텍스트의 종류에 따라 필요한 센싱 정보가 다르기 때문에, 컨텍스트의 전이가 발생하면 필요한 센서들의 변화로 인해 센서 모듈들을 끄고 켜는 과정에서의 전력 소비가 크며, 정확한 센싱이 되지 않는 상황에서 과도한 센싱을 시도하게된다. 본 논문에서는 실내/실외 컨텍스트 전이에서 발생하는 전력 소모에 초점을 두고 해당 컨텍스트와 연관된 센서 활동을 모델링 한 뒤, 컨텍스트 전이가 일어나는 시점을 감지하여 전력 소모를 최소화할 수 있는 freezing 알고리즘을 적용하는 기법을 제안한다. 시중의 실내/실외 위치추적 어플리케이션을 이용하여 컨텍스트 전이가 발생하는 지점에서, 제안하는 기법의 유무에 따른 소비 전력 차이를 실측하였으며, 시중의 어플리케이션의 실제 구동 중 컨텍스트 전이과정에서의 전력 절감이 있었으며, 전체 시나리오에서 약 20%의 전력 절감 효과를 얻었다.

• 한국전자통신학회논문지
• /
• 제9권9호
• /
• pp.971-976
• /
• 2014

본 논문은 상태 전환 준비 방법을 이용한 저 전력 알고리즘을 제안하였다. 제안한 알고리즘은 태스크를 휴면 상태와 유휴 상태, 동작 상태로 구분하여 상태를 정의 한다. 각각의 상태 전환이 발생될 때 발생되는 지연시간으로 인하여 발생되는 소모 전력을 줄이기 위해 각각의 상태 중간에 준비 상태를 삽입한다. 준비 과정은 상태의 전환에서 발생되는 소모 전력과 지연시간을 고려한다. 지연시간이 긴 경우에는 스케줄링에서의 단계를 초과하여 수행 단계를 증가시키는 문제를 발생시킨다. 수행 단계의 증가는 소모 전력의 증가를 초래한다. 상태 전환에서 지연시간이 가장 긴 휴면 상태에서 동작 상태로 상태가 전환될 때 발생되는 시간지연으로 인하여 발생되는 동작시간의 증가를 줄여 전체 소모 전력을 줄이게 된다. 실험은 저 전력 알고리듬인 참고문헌 [6]과 비교하였다. 실험결과 참고문헌 [6]보다 소모 전력이 감소되어 알고리듬의 효율성이 입증되었다.