• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.379-382
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• 2001

In domestic construction industry, time and cost has been managed separately in most cases. Usually projects are managed focused on cost, so time is not yet managed systematically. Project performance in these managemental situation can not be assessed correctly. This would cause project delay, cost overrun, productivity loss. Therefore it is needed to adopt earned value concept, an approach used in the management and control of project costs and schedules. Using this EV concept through time-cost integration, project can be managed properly based on the consistency, predictability, and reliability of the performance data. This paper proposed time and cost integration process, proper PMT method, and practical performance management model through time and cost integration.

• The Transactions of the Korea Information Processing Society
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• v.6 no.9
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• pp.2533-2539
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• 1999

Two scheme are widely used for fault-tolerant systems : one is the duplex system that has a physical redundancy, and the other one is the checkpointing scheme that rolls back to the last checkpoint at a failure. The average execution time and availability are important factors for measuring the performance of the fault-tolerant systems. However, in fault-tolerant real-time systems with a time constraint, meeting the time constrain instead of reducing the average execution time is the most important factor in the performance evaluation. We analyze and compare the performance of two fault-tolerant scheme (the duplex system and the checkpointing scheme) for real-time applications.

• Journal of Auto-vehicle Safety Association
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• v.14 no.2
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• pp.20-25
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• 2022

This paper represents an adaptive Region of Interest (ROI) decision for real-time performance in an autonomous driving perception module. Since the whole automated driving system consists of numerous modules and subdivisions of module occur, it is necessary to consider the characteristics, complexity, and limitations of each module. Furthermore, Light Detection And Ranging (Lidar) sensors require a considerable amount of time. In view of these limitations, division of submodule is inevitable to represent high real-time performance for stable system. This paper proposes ROI to reduce the number of data respect to computation time. ROI is set by a road's design speed and the corresponding ROI is applied differently to each vehicle considering its speed. The simulation model is constructed by ROS, and overall data analysis is conducted by Matlab. The algorithm is validated using real-time driving data in urban environment, and the result shows that ROI provides low computational costs.

• Journal of Applied Reliability
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• v.12 no.3
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• pp.131-138
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• 2012

A design of reliability qualification test based on performance distribution is developed. In general, the performance of an item degrades as the time goes by and the failure of an item occurs when the performance degradation reaches the pre-determined critical level. This article considers the reliability qualification test based on a more tightened critical value at the earlier stage to reduce the evaluation testing time and cost. A numerical example is provided to illustrate how to use the developed reliability qualification test.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.1
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• pp.67-71
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• 2006

A total of 120 male and 240 female quail (Coturnix coturnix Pharaoh) were used to determine the effect of feeding time on laying and reproductive performance of Pharaoh quail. They were fed ad libitum between 09:00 to 17:00 or full day, daily. Each female-male pair was housed in multiple-bird cages and colony cages. Initial and final body weight, quail-day egg production, feed consumption per egg and mortality were measured to determine laying performance of breeders. A total of 960 eggs were used to determine reproductive performance of quail in each treatment group. Eggs were incubated in a commercial setter and hatcher in standard conditions. Embryonic mortality, apparent fertility, hatchability of total and fertile eggs were calculated to determine the reproductive performance. Results indicated that feeding between 09:00 to 17:00 h reduced final body weight and egg production (p<0.001, p<0.001). Whereas, limited time of feeding improved hatchability of total (p<0.001) and fertile eggs (p<0.001) and reduced embryonic mortality (p<0.001) when compared with the effects of feeding full day. It was found that there were no significant differences for the egg production of quail housed in different cage systems. Quail caged in multiple-bird cages consumed less feed (p<0.01) compared to quail housed in colony cages. There were significant differences for the mortality (p<0.05), hatchability of total (p<0.001) and fertile eggs (p<0.001), and embryonic mortality (p<0.001) during the incubation due to main effect of cage systems. There were significant cage $systems{\times}feeding$ time interactions for hatchability of total and fertile eggs and embryonic mortality (p<0.001). As a conclusion; feeding from 09:00 to 17:00 reduced laying performance of quail and improved the reproductive traits compared to full day feeding of quail breeders. But, further investigations are needed to determine the optimum length of feeding time and egg production of breeders in quail fed limited time must be evaluated in comparison with its beneficial or detrimental effects.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.2
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• pp.135-144
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• 2003

Traffic performance in a microcellular system is much more affected by cell dwell time and channel holding time in each cell. Cell dwell time of a call is characterized by its mobility pattern, i.e., stochastic changes of moving speed and direction. Cell dwell time provides important information for other analyses on traffic performance such as channel holding time, handover rate, and the average number of handovers per call. In the next generation mobile communication system, the cell size is expected to be much smaller than that of current one to accommodate the increase of user demand and to achieve high bandwidth utilization. As the cell size gets small, traffic performance is much more affected by variable mobility of users, especially by that of pedestrians. In previous work, analytical models are based on simple probability models. They provide sufficient accuracy in a simple second-generation cellular system. However, the role of them is becoming invalid in a picocellular environment where there are rapid change of network traffic conditions and highly random mobility of pedestrians. Unlike in previous work, we propose an improved probability model evolved from so-called Random walk model in order to mathematically formulate variable mobility of pedestrians and analyze the traffic performance. With our model, we can figure out variable characteristics of pedestrian mobility with stochastic correlation. The above-mentioned traffic performance measures are analyzed using our model.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.127-136
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• 2016

The camera based object detection systems should satisfy the recognition performance as well as real-time constraints. Particularly, in safety-critical systems such as Autonomous Emergency Braking (AEB), the real-time constraints significantly affects the system performance. Recently, multi-core processors and system-on-chip technologies are widely used to accelerate the object detection algorithm by distributing computational loads. However, due to the advanced hardware, the complexity of system architecture is increased even though additional hardwares improve the real-time performance. The increased complexity also cause difficulty in migration of existing algorithms and development of new algorithms. In this paper, to improve real-time performance and design complexity, a task scheduling strategy is proposed for visual object tracking systems. The real-time performance of the vision algorithm is increased by applying pipelining to task scheduling in a multi-core processor. Finally, the proposed task scheduling algorithm is applied to crosswalk detection and tracking system to prove the effectiveness of the proposed strategy.

• Fire Science and Engineering
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• v.17 no.2
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• pp.10-16
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• 2003

The main purpose of this study is to raise the point at issue and to propose reform direction about the current performance criteria of fire resistance through the examination of the fire resistance required for each use of compartment by using performance-based fire safety design method. To examine the performance criteria of fire resistance, this study compared the equivalent time of fire exposure which was calculated by using time-equivalent formulae with the required fire resistance time determined by existing prescriptive code, and surveyed factors such as the fire load energy density, ventilation factor, fire compartment materials and fire compartment geometry in order to calculate the equivalent time of fire exposure.

• Journal of Power System Engineering
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• v.11 no.3
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• pp.66-72
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• 2007

This study proposed new method to decide the reference model necessary for design PID controller. In generally, control design problems using the reference model have the following two factors. One factor is that numerical model of the controlled system can be obtained extremely, and the other is that specification for the closed-loop dynamic performance is pure moderate. Therefore, the control design procedure is essentially based on the partial reference model matching which offers a reasonable method to simplify the design and the controller configuration under the controlled system uncertainty. ITAE(Integral of time-multiplied absolute error) performance index and Kitamori method etc. which were used a reference model method had a limit to settling time and rising time of reference model that it arrived to steady state response according to the controlled system. On this study, if it only knew peak time of overshoot and settling time by measurement signal of the controlled system, it can be made the reference model easily. We proposed new method to improve performance index of the reference model superior to existing reference model index and illustrate the numerical simulation results to show the effectiveness of proposed control method design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8B
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• pp.760-770
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• 2002

Transmit diversity is an efficient diversity technique to improve performance and spectrum efficiency in wireless communication . Coding scheme designed for the transmit diversity is called space-time coding. In this paper, we propose a training structure to apply the transmit diversity to improve the performance of IEEE802.11a OFDM systems. Based on this training structure, we propose a channel estimation scheme using curve fitting. Also we compare and evaluate the performance of space-time codes. The performance of both diversity using space-time codes and channel estimation scheme is investigated by computer simulation in quasi-static 2-ray rayleigh fading environment.