• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.13-21
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• 2015

In recent years energy consumption has become a main concern for network development, due to the exponential increase of network traffic. Potential energy savings can be obtained from a load-adaptive scheme, in which a day can be divided into multiple time periods according to the variation of daily traffic patterns. The energy consumption of the network can be reduced by selectively turning off network components during the time periods with light traffic. However, the time segmentation of daily traffic patterns affects the energy savings when designing multiperiod logical topology in optical wavelength routed networks. In addition, turning network components on or off may increase the overhead of logical topology reconfiguration (LTR). In this paper, we propose two mixed integer linear programming (MILP) models to design the optimal logical topology for multiple periods in IP-over-WDM networks. First, we formulate the time-segmentation problem as an MILP model to optimally determine the boundaries for each period, with the objective to minimize total network energy consumption. Second, another MILP formulation is proposed to minimize both the overall power consumption (PC) and the reconfiguration overhead (RO). The proposed models are evaluated and compared to conventional schemes, in view of PC and RO, through case studies.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.173-180
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• 2014

Random access protocols feature inherent sensing functionality and distributed coordination, making them suitable for cognitive radio communication environments, where secondary users must detect the white space of the primary spectrum and utilize the idle primary spectrum efficiently without centralized control. These characteristics have led to the adoption of carrier-sensing-multiple-access/collision-avoidance (CSMA/CA) in cognitive radio. This paper proposes a new analytical framework for evaluating the performance of a CSMA/CA protocol that considers the characteristics of idle periods based on the primary traffic behavior in cognitive radio systems. In particular, the CSMA/CA-based secondary network was analyzed in the terms of idle period utilization, which is the average effective data transmission time portion in an idle period. The use of the idle period was maximized by taking its statistical features into consideration.

• Clinical and Experimental Pediatrics
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• v.62 no.10
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• pp.367-373
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• 2019

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of preterm infants with multiple factors affected from prenatal to postnatal periods. Despite significant advances in neonatal care over almost 50 years, BPD rates have not decreased; in fact, they may have even increased. Since more preterm infants, even at periviable gestational age, survive today, different stages of lung development affect the pathogenesis of BPD. Hence, the definition of BPD has changed from "old" to "new." In this review, we discuss the various definitions of BPD, risk factors from the prenatal to postnatal periods, management strategies by phase, and future directions for research.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.9
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• pp.45-52
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• 2008

As multiple functions arc required in a robot controller, RTOS(Real Time Operating System) should be adopted to manage complex situations, such as choosing most urgent task among competing ones. In this paper, we implemented RTAI(Real Time Application Interface) based robot controller for wafer handling robots including graphic simulator. We showed how multiple tasks are organized and also explained in detail about task priorities and execution periods. Finally, we presented simulation results.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1024-1027
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• 2006

The electrical and the optical properties of organic light-emitting devices (OLEDs), with and without various kinds of multiple heterostructures were investigated. The efficiency in green OLEDs were significantly enhanced by the structure of the multiple heterostructures acting as a hole transport layer (HTL) rather than by the number of periods. These results indicate that highly efficient green OLEDs utilizing multiple heterostructures acting as a HTL can be fabricated.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.6
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• pp.506-513
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• 2002

Distributed control systems(DCS) using fieldbus such as CAN have been applied to process systems but it is very difficult to design the DCS while guaranteeing the given end-to-end constraints such as precedence constraints, time constraints, and periods and priorities of tasks and messages. This paper presents a scheduling method to guarantee the given end-to-end constraints. The presented scheduling method is the integrated one considering both tasks executed in each node and messages transmitted via the network and is designed to be applied to a general DCS that has multiple loops with several types of constraints, where each loop consists of sensor nodes with multiple sensors, actuator nodes with multiple actuators and controller nodes with multiple tasks. An assignment method of the optimal period of each loop and a heuristic assignment rule of each message's priority are proposed and the integrated scheduling method is developed based on them.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.311-314
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• 2003

In recent years, distributed control systems(DCS) using fieldbus such as CAN have been applied to process systems but it is very difficult to design the DCS while guaranteeing the given end-to-end constraints such as precedence constraints, time constraints, and periods and priorities of tasks and messages. This paper presents a scheduling method to guarantee the given end-to-end constraints considering aperiodic, periodic and non-real-time message and task simultaneously. The presented scheduling method is the integrated one considering both tasks executed in each node and messages transmitted via the network and is designed to be applied to a general DCS that has multiple loops with several types of constraints, where each loop consists of sensor nodes with multiple sensors, actuator nodes with multiple actuators and controller nodes with multiple tasks.

• Journal of Elementary Mathematics Education in Korea
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• v.7 no.1
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• pp.45-64
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• 2003

This study analyzes divisor and multiple in elementary school mathematics textbooks published according to the first to the 7th curriculum, in a view point of the didactic transposition theory. In the first and second textbooks, the divisor and the multiple are taught in the chapter whose subject is on the calculations of the fractions. In the third and fourth textbooks, divisor and multiple became an independent chapter but instructed with the concept of set theory. In the fifth, the sixth, and the seventh textbooks, not only divisor multiple was educated as an independent chapter but also began to be instructed without any conjunction with set theory or a fractions. Especially, in the seventh textbook, the understanding through activities of students itself are strongly emphasized. The analysis on the each curriculum periods shows that the divisor and the multiple and the reduction of a fractions to the lowest terms and to a common denominator are treated at the same period. Learning activity elements are increase steadily as the textbooks and the mathematical systems are revised. The following conclusion can be deduced based on the textbook analysis and discussion for each curriculum periods. First, loaming instruction method also developed systematically with time. Second, teaching method of the divisor and multiple has been sophisticated during the 1st to 7th curriculum textbooks. And the variation of the teaching sequences of the divisor and multiple is identified. Third, we must present concrete models in real life and construct textbooks for students to abstract the concepts by themselves. Fourth, it is necessary to develop some didactics for students' contextualization and personalization of the greatest common divisor and least common multiple. Fifth, the 7th curriculum textbooks emphasize inquiries in real life which teaming activities by the student himself or herself.

• Archives of Plastic Surgery
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• v.39 no.4
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• pp.426-430
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• 2012

Dupuytren's contracture is a condition commonly encountered by hand surgeons, although it is rare in the Asian population. Various surgical procedures for Dupuytren's contracture have been reported, and the outcomes vary according to the treatment modalities. We report the treatment results of segmental fasciectomies with multiple transverse incisions for patients with Dupuytren's contracture. The cases of seven patients who underwent multiple segmental fasciectomies with multiple transverse incisions for Dupuytren's contracture from 2006 to 2011 were reviewed retrospectively. Multiple transverse incisions to the severe contracture sites were performed initially, and additional incisions to the metacarpophalangeal (MCP) joints, and the proximal interphalangeal (PIP) joints were performed if necessary. Segmental fasciectomies by removing the fibromatous nodules or cords between the incision lines were performed and the wound margins were approximated. The mean range of motion of the involved MCP joints and PIP joints was fully recovered. During the follow-up periods, there was no evidence of recurrence or progression of disease. Multiple transverse incisions for Dupuytren's contracture are technically challenging, and require a high skill level of hand surgeons. However, we achieved excellent correction of contractures with no associated complications. Therefore, segmental fasciectomies with multiple transverse incisions can be a good treatment option for Dupuytren's contracture.

• Journal of Korean Society of Transportation
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• v.11 no.1
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• pp.67-86
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• 1993

A formulation of dynamic traffic assignment between multiple origins and single destination was first introduced in 1987 by Merchant and Nemhauser, and then expanded for multiple destination in the late 1980's (Carey, 1987). Based on behavioral choice theory which provides proper demand elasticities with respect to changes in policy variables, traffic phenomena can be analysed more realistically, especially in peak periods. However, algorithms for these models are not well developed so far(working with only small toy network) and solutions of these models are not unique. In this paper, a new model is developed which keeps the simplicity of static models, but provides the sensitivity of dynamic models with changes of O-D flows over time. It can be viewed as a joint departure time and route choice model, in the given time periods(6-7, 7-8, 8-9 and 9-10 am). Standard multinomial logit model has been used for simulating the choice behavior of destination, mode, route and departure time within a framework of the incremental network assignment model. The model developed is workable in a PC 386 with 175 traffic zones and 3581 links of Seoul and tested for evaluating the exclusive use of Namsan tunnel for HOV and the left-turn prohibition. Model's performance results and their statistical significance are also presented.