• JSTS:Journal of Semiconductor Technology and Science
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• 제16권3호
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• pp.330-338
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• 2016

Phase change memory (PCM) has been studied as an emerging memory technology for last-level cache (LLC) due to its extremely low leakage. However, it consumes high levels of energy in updating cells and its write endurance is limited. To relieve the write pressure of LLC, we propose a delta value indicator (DVI) by employing a small cache which stores the difference between the value currently stored and the value newly loaded. Since the write energy consumption of the small cache is less than the LLC, the energy consumption is reduced by access to the small cache instead of the LLC. In addition, the lifetime of the LLC is further extended because the number of write accesses to the LLC is decreased. To this end, a delta value indicator and controlling circuits are inserted into the LLC. The simulation results show a 26.8% saving of dynamic energy consumption and a 31.7% lifetime extension compared to a state-of-the-art scheme for PCM.

• 대한임베디드공학회논문지
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• 제6권5호
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• pp.287-293
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• 2011

As chip multiprocessors have been widely adopted in embedded systems, achieving both high performance and low power consumptions of parallel applications becomes challenging. In order to meet these requirements, it is crucial for developers to analyze the performance and energy consumption of parallel applications. In this paper, we propose a tool for profiling and optimizing the performance and energy consumption of OpenMP applications (energy PROfiler and analyzer for OpenMP: ePRO-OMP). The main advantage of ePRO-OMP is that it can analyze both the performance and energy consumption of each parallel region of an OpenMP application, which can help developers find the bottleneck of parallel applications in detail.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제13권5호
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• pp.241-251
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• 2007

최근의 내장형 프로세서를 설계하는데 있어서는 성능 못지 않게 에너지 효율성이 중요하게 고려되어야 한다. 내장형 프로세서에서 소모되는 에너지의 상당 부분은 캐쉬 메모리에서 소모되는 것으로 알려지고 있다. 특히 1차 명령어 캐쉬는 거의 매 사이클마다 접근이 이루어지므로 상당히 많은 양의 동적 에너지를 소모하게 된다. 그러므로, 내장형 프로세서를 설계하는데 있어서 1차 명령어 캐쉬의 에너지 효율성을 높이는 기법은 프로세서의 총 에너지 소모를 줄여주는 결과로 이어질 것으로 기대된다. 본 논문에서는 내장형 프로세서에 적합한 저전력 1차 명령어 캐쉬를 설계하는 기법을 제안하고자 한다. 제안하는 기법은 명령어 캐쉬를 여러 개의 작은 서브 캐쉬들로 분할하는 기법을 통해 명령어 접근 시 활성화되는 캐쉬의 크기를 줄임으로써 1차 명령어 캐쉬에서 소모되는 동적 에너지를 감소시켜 준다. 또한, 하나의 서브 캐쉬 크기를 페이지 크기와 동일하게 함으로써 캐쉬 내에서 태그가 차지하는 칩 공간을 없애고, 태그 비교에 소모되는 에너지도 없애는 효과를 얻는다. 제안하는 1차 명령어 캐쉬는 물리적인 접근 시간 감소를 통해 캐쉬 분할로 인한 성능 저하를 최대한 줄이고, 에너지 감소 효과는 최대로 얻고자 한다. 모의 실험 결과, 제안하는 구조는 기존의 1차 명령어 캐쉬 구조와 비교하여 명령어 접근에 소모되는 동적 에너지를 평균 $37%{\sim}60%$ 감소시키는 결과를 보인다.

• Journal of Communications and Networks
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• 제15권3호
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• pp.292-300
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• 2013

Nowadays, energy saving has become a hot topic and information and communication technology has become a major power consumer. In long term evolution advanced (LTE-A) networks, heterogeneous deployments of low-power nodes and conventional macrocells provide some new features, such as coverage extension, throughput enhancement, and load balancing. However, a large-scale deployment of low-power nodes brings substantial energy consumption and interference problems. In this paper, we propose a novel switching strategy (NS), which adaptively switches on or off some low-power nodes based on the instantaneous load of the system. It is compatible with the microcells' load balancing feature and can be easily implemented on the basis of existing LTE-A specifications. Moreover, we develop an analytical model for analyzing the performance of system energy consumption, block rate, throughput, and energy efficiency. The performance of NS is evaluated by comparison with existing strategies. Theoretical analysis and simulation results show that NS not only has a low block rate, but also achieves a high energy efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권8호
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• pp.2490-2506
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• 2022

In Mobile Edge Computing (MEC), attackers can speculate and mine sensitive user information by eavesdropping wireless channel status and offloading usage pattern, leading to user privacy leakage. To solve this problem, this paper proposes a Privacy-preserving and Energy-efficient Offloading Algorithm (PEOA) based on Lyapunov optimization. In this method, a continuous Markov process offloading model with a buffer queue strategy is built first. Then the amount of privacy of offloading usage pattern in wireless channel is defined. Finally, by introducing the Lyapunov optimization, the problem of minimum average energy consumption in continuous state transition process with privacy constraints in the infinite time domain is transformed into the minimum value problem of each timeslot, which reduces the complexity of algorithms and helps obtain the optimal solution while maintaining low energy consumption. The experimental results show that, compared with other methods, PEOA can maintain the amount of privacy accumulation in the system near zero, while sustaining low average energy consumption costs. This makes it difficult for attackers to infer sensitive user information through offloading usage patterns, thus effectively protecting user privacy and safety.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.183-186
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• 2010

Advanced Railway countries are developing technologies of production and management for low-carbon and green growth of their railway industry to hold a dominant position under post-Tokyo protocol regime through integrated approach which uses environmental quantitative analysis of train life cycle by using LCA(Life Cycle Assessment). On the contrary, Korea railroad industry attempts to make an environmental improvement only for using regenerative energy and improvement in operating energy consumption through adapting reduction weight of material technology and etc. without systematic environmental analysis approaches such as comparing and analyzing energy consumption as well as GHG emission in each life cycle stages of train. Therefore, In this paper, low-carbon management and comprehensive environmental improvement for sustainable development of Korea railway industry through analyzing the result of life cycle analysis in abroad are suggested.

• KIEAE Journal
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• 제14권2호
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• pp.37-46
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• 2014

University buildings are energy-guzzling facility that consume more than 10,000TOE within a campus annually. Even the consumption is on an upswing trend. Behind such high consumption are there cheap power rates for education facility, lack of high-efficiency equipment and ever-increasing use of various information equipment. Being keenly aware that greenhouse gas emission increases due to such rise of energy consumption, the present study carried out a case study. In the case study, the study chose the buildings of E university from top 10 universities that consume energy most in Seoul and examined the current status of their energy consumption and greenhouse gas emission. And then it set the reduction target of greenhouse gas by year. Putting aside a middle and long-termed strategy for later endeavor, it first established the 1st year's implementation plan (2014) for energy saving and greenhouse gas reduction with limited budget and according to greenhouse gas reduction target. The plan is specified as follows. Targets for energy saving are mainly divided into two sectors: machine equipment and electric equipment. 7 ideas were proposed. Three ideas to improve machine equipment are to replace with high-efficiency boilers and chillers and to adjust the position of the cooling tower. By doing so, it was estimated that energy could be saved by 176.34TOE in total and greenhouse gas could be reduced by 370.771t$CO_2$-eq. Four ideas to improve electric equipment include the replacement with LED lights, LED emergency lights and high-efficiency motors and the installation of motion sensors. It was calculated that such replacement could conserve 1,076.08TOE (electric energy) and reduce 2,181.420t$CO_2$-eq (greenhouse gas).

• 한국시뮬레이션학회논문지
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• 제21권4호
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• pp.47-56
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• 2012

본 연구에서는 센서 네트워크용 병렬 시뮬레이터인 PASENS(Parallel SEnsor Network Simulator)를 이용하여 센서 네트워크에 이용되는 라우팅 알고리즘 중에서 계층적 라우팅 프로토콜의 대표적인 방식인 LEACH(Low-Energy Adaptive Clustering Hierarchy)와 그의 변형인 TL-LEACH(Two Level Low-Energy Adaptive Clustering Hierarchy), M-LEACH(Multihop Low-Energy Adaptive Clustering Hierarchy), 그리고 LEACH-C(LEACH-Centralized)의 전력 소모량과 데이터의 수신율을 비교하고 분석하였다. 시뮬레이션을 이용한 분석 결과에 따르면, M-LEACH 라우팅 프로토콜의 경우에는 여러 센서 노드들을 통하여 데이터가 전달되기 때문에 일정한 크기 이상의 넓은 공간에서 높은 수신율을 보였으며, LEACH-C 라우팅 프로토콜은 싱크 노드(서버)가 전체 센서 노드의 잔여 에너지와 위치를 고려하여 클러스터 헤드를 결정하기 때문에 좁은 공간에서 보다 오랜 수명을 필요로 하는 센서 네트워크를 구축하는데 가장 효율적이라는 것을 확인 할 수 있었다.

• Journal of Information Processing Systems
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• 제14권4호
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• pp.948-960
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• 2018

Many mobile sensing frameworks have been developed to help researcher doing their mobile sensing research. However, energy consumption is still an issue in the mobile sensing research, and the existing frameworks do not provide enough solution for solving the issue. We have surveyed several mobile sensing frameworks and carefully chose one framework to improve. We have designed an adaptive sampling module for a mobile sensing framework to help solve the energy consumption issue. However, in this study, we limit our design to an adaptive sampling module for the location and motion sensors. In our adaptive sampling module, we utilize the significant motion sensor to help the adaptive sampling. We experimented with two sampling strategies that utilized the significant motion sensor to achieve low-power consumption during the continuous sampling. The first strategy is to utilize the sensor naively only while the second one is to add the duty cycle to the naive approach. We show that both strategies achieve low energy consumption, but the one that is combined with the duty cycle achieves better result.

• 반도체디스플레이기술학회지
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• 제20권4호
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• pp.44-48
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• 2021

Semiconductor inspection equipment makes components using materials with insulating properties for functional inspection including current and voltage of semiconductor parts. A representative insulating material is plastic, and plastic is made of a component through an injection process using plastic pellet. When plastic pellets contain excessive moisture, problems such as performance degradation and product surface defects occur. To prevent this, pre-drying is essential, and the heat convective type is the most applied. However, the heat convective type has a problem of low consumption efficiency and a long drying time. Recently, many studies have been conducted on a drying method using microwaves due to high energy efficiency. In this paper, drying was performed using a microwave for drying PC pellets. Energy consumption and drying efficiency analyzed by set up an experimental apparatus of heat convective, microwave, and hybrid(heat convective + microwave) types. It was confirmed that energy consumption and drying efficiency were high when drying using microwaves, and it was confirmed that the hybrid method improved drying performance compared to the heat convective method. It is expected that the research results of this paper can be used as basic data for drying plastic pellets using microwave.