• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권12호
• /
• pp.5307-5327
• /
• 2016

Restricted by finite battery energy, traditional wireless sensor networks (WSNs) can only maintain for a limited period of time, resulting in serious performance bottleneck in long-term deployment of WSN. Fortunately, the advancement in the wireless energy transfer technology provides a potential to free WSNs from limited energy supply and remain perpetual operational. A mobile charger called wireless charging vehicle (WCV) is employed to periodically charge each sensor node and keep its energy level above the minimum threshold. Aiming at maximizing the ratio of the WCV's vocation time over the cycle time as well as guaranteeing the perpetual operation of networks, we propose a feasible and optimal solution to this issue within the context of a real-time large-scale deployed WSN. First, we develop two different types of charging cycles: initialization cycles and renewable cycles and give relevant algorithms to construct these two cycles for each sensor node. We then formulate the optimization problem into an optimal construction algorithm and prove its correctness through theoretical analysis. Finally, we conduct extensive simulations to demonstrate the effectiveness of our proposed algorithms.

• Archives of Reconstructive Microsurgery
• /
• 제23권1호
• /
• pp.8-12
• /
• 2014

Purpose: The success rate of free flap operation has shown a recent increase. Especially for breast reconstructive patients, aesthetic results are considered a necessity. However, for patients who underwent reconstruction in parts of the body other than breast, for example, head and neck, lower and upper extremities, aesthetic considerations are underscored. Nowadays, however, aesthetic standpoint toward these patients is changing. Materials and Methods: We conducted a retrospective review of 8 patients who underwent secondary procedures after free flap surgery from March of 2011 to April of 2014. Results: Secondary refinement was a safe and less time-consuming technique for maximizing the function and aesthetic appearance for the patient. Conclusion: Appearance has become increasingly important with regard to function and quality of life. Therefore, for free flap reconstructive patients, secondary refinements may be considered in order to change the shape and contour. The secondary refinements are critical to the final result and must be a planned part of the entire reconstructive sequence.

• 한국기계가공학회지
• /
• 제3권3호
• /
• pp.32-38
• /
• 2004

Recently, the system of high speed milling(HSM) is widely used for reducing the operation time and maximizing efficiency of work. The most research of high speed milling system is still leaves much to be desired. Specially the research of mass pocket high speed processing with high precision is the first and probably the last. So this paper showed mass pocket processing of high precision with a duralumin and then confirmed a cause of inferior goods through the CAD/CAM pattern simulation and experimentation. And this paper showed high speed processing system reduce the rate of inferior from this optimal pattern.

• 대한전자공학회논문지
• /
• 제23권2호
• /
• pp.197-205
• /
• 1986

In this paper, we present an efficient test algorithm for data processing function of MC68000 \ulcorner. The test vector for functional testing is determined by stuck-at, coupling and transition fault for data storage and transfer. But for data manipulation it is determined by a boolean function of micro-operation. This test algorithm is composed of 3 parts, choosing optimum test instructions for maximizing fault coverage and minimizing test process time, deciding the test order for minimizing test ambiguity, and processing the actual test.

• 국제학술발표논문집
• /
• The 9th International Conference on Construction Engineering and Project Management
• /
• pp.418-425
• /
• 2022

For a commercial building, property managers play an important role in maximizing the benefit by reducing cost and increasing revenue in the operation and maintenance phase of the building. However, most of property managers are spending their time in monitoring facility managers who have little impact on cost reduction and maximization of operating profit. The industry practitioners have difficutlty in increasing the efficiency of thier work due to this work environment. In addition, both property managers(PMr) and facility managers(FMr) are dependent on the paper drawings and manuals, which can worsen the inefficiency and human errors are inevitable. This study aims to contribute to improvement of the current practice by developing a novel algorithm that autmatically links the facility information with 3D model, which can provide an efficient property management for commercial buildings.

• 한국태양에너지학회 논문집
• /
• 제34권5호
• /
• pp.33-41
• /
• 2014

Heliostat field in a tower type solar thermal power plant is the sun tracking mirror system which affects the overall efficiency of solar thermal power plant most significantly while consumes a large amount of energy to operate it. Thus optimal operation of it is very crucial for maximizing the energy collection and, at the same time, for minimizing the operating cost. Heliostat field operational algorithm is the logics to control the heliostat field efficiently so as to optimize the heliostat field optical efficiency and to protect the system from damage as well as to reduce the energy consumption required to operate the field. This work presents the heliostat field operational algorithm developed for the heliostat field of 200kW solar thermal power plant built in Daegu, Korea. We first review the structure of heliostat field control system proposed in the previous work to provide the conceptual framework of how the algorithm developed in this work could be implemented. Then the methodologies to operate the heliostat field properly and efficiently, by defining and explaining the various operation modes, are discussed. A simulation, showing the heat flux distribution collected by the heliostat field at the receiver, is used to show the usefulness of proposed heliostat field operational algorithm.

• 한국국방경영분석학회지
• /
• 제1권1호
• /
• pp.131-135
• /
• 1975

One of the pending issues of the Ministry of Defense is the efficient management of space parts for the weapon systems. It has been known that more than 000 million dollars are needed for spare parts for the weapon systems annually. Though the problem demands a serious consideration, there has not been any systematic study on the problem as far as the author knows. One way to approach the problem is through an investigation of the system reliability under constraints. A measure of how well a system performs or meets its design objectives is provided by the concept of system reliability. If successful operation is desired for a specified period of time, reliability is defined as the probability that the system will perform satisfactorily for the required time period. This interpretation of reliability is normally applied to devices which are subject to random failures such as electrical or mechanical systems. It has been found necessary to express system reliability in terms of the reliability of the components or subsystems which comprise the system. The major subsystems of an aircraft, for example, include the electronics, powerplant, airframe and armament subsystems. Therefore, the optimal spare part kit can be found by maximizing the system reliability subject to cost or other constraints.

• 한국군사과학기술학회지
• /
• 제14권5호
• /
• pp.904-912
• /
• 2011

In this paper, we have proposed a M&S tool for analyzing detection coverage and target localization in bistatic radar system. The detection coverage determined by radar parameters is meaningful when it satisfies the clear line-of-sight condition. We improved the method to find the minimum altitudes of transmitter and receiver for meeting the condition by considering three-dimensional coverage. Its computational burden is not problematic because the calculation is for maximizing the performance of the radar and does not demand a real-time operation. In addition, target localization on three-dimensional earth model based on the information of the height, longitude, and latitude is proposed instead of the previous unpractical calculation on two-dimensional bistatic plane. Its precalculated result can reduce its computation burden and it is suitable for real-time estimation of target location.

• 한국인터넷방송통신학회논문지
• /
• 제10권4호
• /
• pp.115-120
• /
• 2010

모듈화된 부품을 이용하여 완성된 제품을 만드는 제품완성업체는 효율적인 부품공급시스템을 통해 부품공급업체로부터 적시에 조립라인에 부품을 공급받기를 원하며 이종부품에 대한 결품이 발생하지 않기를 기대한다. 스마트 파렛트 기반 부품공급시스템은 이러한 요구를 만족시키기 위하여 수작업에 의한 과다한 이종부품확인 시간을 소비하는 기존의 바코드 기반 방식의 단점과 RFID 기반 방식이 가진 전송거리 제한 문제를 해결하고자 제안되었다. 본 논문에서는 스마트 파렛트 기반 부품공급시스템이 가진 제한된 전력 문제를 보완하고 운영의 효율성을 극대화하기 위한 PDA 시스템을 제안하고 실제 구현하였다.

• ETRI Journal
• /
• 제39권3호
• /
• pp.353-363
• /
• 2017

Recently, sink mobility has been shown to be highly beneficial in improving network lifetime in wireless sensor networks (WSNs). Numerous studies have exploited mobile sinks (MSs) to collect sensed data in order to improve energy efficiency and reduce WSN operational costs. However, there have been few studies on the effectiveness of MS operation on WSN closed operating cycles. Therefore, it is important to investigate how data is collected and how to plan the trajectory of the MS in order to gather data in time, reduce energy consumption, and improve WSN network lifetime. In this study, we combine two methods, the cluster-head election algorithm and the MS trajectory optimization algorithm, to propose the optimal MS movement strategy. This study aims to provide a closed operating cycle for WSNs, by which the energy consumption and running time of a WSN is minimized during the cluster election and data gathering periods. Furthermore, our flexible MS movement scenarios achieve both a long network lifetime and an optimal MS schedule. The simulation results demonstrate that our proposed algorithm achieves better performance than other well-known algorithms.