• 전기학회논문지
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• 제66권1호
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• pp.7-15
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• 2017

Ambient Adjusted line Rating(AAR) method for overhead transmission lines considering Risk Tolerance(RT) was proposed in this paper. AAR is suitable for system operators to plan their operation strategy and maintenance schedule because this can be designed as a seasonal line rating. Several candidate transmission lines are chosen to apply the proposed method in the paper. As a result, it is shown that system reliability was significantly enhanced through maximizing transfer capability, solving the system constraints.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 춘계학술발표대회
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• pp.216-217
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• 2015

Duty-cycling could efficiently prolong the life time of Wireless Sensor Networks (WSNs) by let nodes be in dormant state most of the time, and only wake up (for sending or receiving) for a very short period. Flooding is one critical operation of WSNs. Many studies have been studied to improve the delay and/or energy efficiency of flooding. In this paper, we propose a novel time slot design, and the switching decision that reduce energy consumption for the schedule-based flooding tree. Each node, if failed to receive from its parent, will look for other candidate, among its siblings to overhear the flooding packet. By accurately collect information from other siblings, each node can make the best as possible switching decision; therefore the energy efficiency of the network is improved.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권6호
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• pp.2824-2837
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• 2019

Container technologies are widely used in infrastructures to deploy and manage applications in cloud computing environment. As containers are light-weight software, the cluster of cloud applications can easily scale up or down to provide Internet-based services. Container-based applications can well deal with fluctuate workloads by dynamically adjusting physical resources. Current works of scheduling applications often construct applications' performance models with collected historical training data, but these works with static models cannot self-adjust physical resources to meet the dynamic requirements of cloud computing. Thus, we propose a self-adaptive automatic container scheduling framework AutoScale for cloud applications, which uses a feedback-based approach to adjust physical resources by extending, contracting and migrating containers. First, a queue-based performance model for cloud applications is proposed to correlate performance and workloads. Second, a fuzzy Kalman filter is used to adjust the performance model's parameters to accurately predict applications' response time. Third, extension, contraction and migration strategies based on predicted response time are designed to schedule containers at runtime. Furthermore, we have implemented a framework AutoScale with container scheduling strategies. By comparing with current approaches in an experiment environment deployed with typical applications, we observe that AutoScale has advantages in predicting response time, and scheduling containers to guarantee that response time keeps stable in fluctuant workloads.

• 한국인터넷방송통신학회논문지
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• 제19권3호
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• pp.53-58
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• 2019

본 논문은 전술 통신망에서 QoS 향상을 위한 클래스 기반의 FQ-CoDel(Flow queue-Control Delay) 알고리즘을 제안한다. 전술 통신망에서 다양한 응용체계 서비스를 제공하게 되면서 병목현상으로 인한 트래픽 손실 및 지연 문제가 대두되었고 따라서 효과적인 트래픽 처리 방안 연구에 대한 필요성이 제기되었다. 제안방안은 클래스 기반의 FQ-CoDel 알고리즘을 이용한 동적인 버퍼 관리 및 스케줄링 기술로써 서비스 특성 및 중요도에 따라 해당 큐에 패킷을 분류하고 주기적으로 각 패킷의 대기시간을 체크하여 기준 대기 시간을 초과하는 경우 해당 패킷을 폐기하여 큐에 저장된 트래픽 양을 일정 수준으로 조절한다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.674-690
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• 2021

This study proposes a hybrid marine power system combining dual-fuel generators, a fuel cell, and Vanadium Redox Flow Batteries (VRFB). Rigorous verification and validation of the dynamic modelling and integration of the system are conducted. A case study for the application of the hybrid propulsion system to a passenger ship is conducted to examine its time-variant behaviour. A comprehensive model of the reversible and irreversible capacity degradation of the VRFB stack unit is proposed and validated. The capacity retention of the VRFB stack is simulated by being integrated within the hybrid propulsion system. Reversible degradation of the VRFB stack is precisely predicted and rehabilitated based on the predefined operational schedule, while the irreversible portion is retained until the affected components are replaced. Consequently, the advantages of the VRFB system as an on-board ESS are demonstrated through the application of a hybrid propulsion system for liner shipping with fixed routes.

• Geomechanics and Engineering
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• 제32권2호
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• pp.209-232
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• 2023

A comprehensive study was conducted to design economical foundations for a number of buildings on soft cohesive soil in the southern coastal regions of Iran. Both static and seismic loads were considered in the design process. Cyclic experiments indicated that the cohesive soil of the area has potential for softening. Consequently, the major challenge in the design stages was relatively high dimensions of settlement, under both static and seismic loadings. Routine soil-improvement methods were too costly for the vast area of the project. After detailed numerical modeling of different scenarios, we concluded that, in following a performance-based design approach and applying a special time schedule of construction, most of the settlement would dissipate during the construction of the buildings. Making the foundation as rigid as possible was another way to prevent any probable differential settlement. Stiff subgrade of stone and lime mortar under the grid foundation and a reinforced concrete slab on the foundation were considered as appropriate to this effect. In favor of an economical design, in case the design earthquake strikes the site, the estimations indicate no collapse of the buildings even if considerable uniform settlements may occur. This is a considerable alternative design to costly soil-improvement methods.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.639-640
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• 2015

Traditional construction planning based on historical data and heuristic adjustment can no longer incorporate all the operational details and guarantee the expected performance. The variation between the expected and the actual production leads to cost overruns or delay. Although predicting reliable productivity on construction site is getting more important, the difficulty of this increases. In this regard, this paper suggested to develop BIM-integrated simulation framework. This framework could predict productivity dynamics by considering factors affecting on construction productivity at operational phase. We developed the following processes; 1) enabling a BIM model to produce input data for simulation; 2) developing the construction operation simulation; 3) running simulation using BIM data and obtaining productivity results. The BIM-integrated simulation framework was tested with structural steel erection model because steel erection work is one of the most critical process influencing on the whole construction budget and duration. We could improve to predict more dynamic productivity from this framework, and this reliable productivity helps construction managers to optimize resource allocation, increase schedule reliability, save storage cost, and reduce material loss.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.336-338
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• 2015

This research is to propose an applicable framework for real-time health surveillance and safety monitoring at construction sites. First this study aims at finding (1) a framework for health surveillance that is likely to benefit employers and employees in the industry, (2) a valid way to identify factors or conditions with potential health concerns that can occur under particular work conditions, (3) An effective way to apply wireless/mobile sensors to construction workers using real-time/live data transmission methods, and (4) A relationship between a worker's vital signs and job site environment. Biosensors for physiological response and devices for weather/work related data are to collect real-time data. Relationships between jobs and physiological responses are analyzed and factors that touched particularly contributing to certain responses are identified. When data are incorporated with tasks, factors affecting tasks can be identified to estimate the magnitude of the factors. By comparing work and normal responses possible precautionary actions can be considered. In addition, the study would be lead to improving (1) trade-specific dynamic work schedules for workers which would be based on various factors affecting worker health level and (2) reevaluating worker productivity with health status and work schedule, thereby seeking ways to maximize worker productivity. Through a study, the paper presents expected benefits of implementing health monitoring.

• 전자공학회논문지
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• 제50권6호
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• pp.188-198
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• 2013

낸드 플래시 메모리 기반 저장장치는 성능을 높이기 위하여 내부에 다수의 플래시 메모리가 공유하는 데이터 버스들을 구성하고, 이 구조를 이용하여 다수의 플래시 메모리 오퍼레이션을 동시에 수행하는 병렬 기법을 사용한다. 저장장치의 성능은 개별 데이터 버스의 성능에 의하여 많은 영향을 받기 때문에, 저장장치 컨트롤러가 오퍼레이션을 효과적으로 스케줄링 함으로써 버스의 성능을 높이는 것이 중요하다. 그러나 오퍼레이션 별로 상이한 동작시간과 버스사용 특성으로 인하여 시시각각 변화하는 버스의 상황은 스케줄링을 어렵게 만든다. 또한 단순히 버스 사용효율을 높이기 위한 스케줄링 기법은 예상하지 못한 오퍼레이션의 지연과 저장장치의 자원 낭비를 초래할 수 있다. 본 논문에서는 데이터 버스의 성능과 저장장치의 자원 효율을 고려한 동적인 오퍼레이션 스케줄링 기법들을 제안한다. 제안하는 기법들은 오퍼레이션을 세 단계로 구분한 후 오퍼레이션의 특성과 데이터 버스의 상황에 따라 이들을 스케줄링 한다. 제안된 기법들을 컨트롤러에 적용하여 FPGA 플랫폼에서 검증한 결과, 제안된 기법을 적용한 컨트롤러는 정적인 스케줄링 기법을 사용하는 컨트롤러에 비하여 쓰기 오퍼레이션의 수가 1.9% 줄어들었으며 4-7% 높은 버스 사용효율과 4-19% 높은 처리량을 보였다.

• 대한교통학회지
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• 제27권1호
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• pp.143-155
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• 2009

현재 이용되는 모든 동적 통행배정모형들은 출발시간을 기준으로 기종점간의 통행량을 정의하고 있다. 하지만, 동적 OD가 출발시간을 통행수요의 동적 기준점으로 이용하는 것은 동적 통행배정 모형의 계산상 편의를 위한 것이다. 즉, 통행이 활동참여를 위해 발생하고 종료된다는 것을 고려하면 이러한 출발시간 기준 기종점표는 모든 종류의 통행들에 적용될 수는 없다. 예를 들어, 오전의 출근통행은 업무개시시간을 고려한 희망도착시간이 기준시간이 되고, 통근자들이 가정을 떠나는 출발시간은 희망도착시간과 예상 기종점 통행시간을 고려해 결정되는 것이다. 그러나 현재 개발되어 있는 모든 통행배정기법들은 출발시간으로부터 시간의 흐름에 따라 기점에서 종점으로 통행을 이동시키기 때문에 통행수요를 종점 희망도착시간을 기준으로 역방향계산을 할 수 없다. 따라서 현실과 동일한 결정과정을 통해 동적 통행배정을 할 수 있는 모형은 아직 개발되지 않았다. 본 연구에서는 이러한 문제인식 아래 희망도착시간을 기준으로 정의된 동적 기종점표를 교통망에 부하할 수 있는 동적 통행배정모형을 개발하였다. 개발된 모형은 희망도착시간분포와 예상 경로 통행시간을 이용하여 출발시간분포를 갱신하는 방법을 이용하였으며, GLS함수를 통해 수학식을 구성하였다. 개발된 모형은 두 가지의 소규모 교통망들에 적용되어 그 성능을 확인하였다.