• The KIPS Transactions:PartD
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• v.13D no.4 s.107
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• pp.463-476
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• 2006

R-trees have been traditionally optimized for the I/O performance with the disk page as the tree node. Recently, researchers have proposed cache-conscious variations of R-trees optimized for the CPU cache performance in main memory environments, where the node size is several cache lines wide and more entries are packed in a node by compressing MBR keys. However, because there is a big difference between the node sizes of two types of R-trees, disk-optimized R-trees show poor cache performance while cache-optimized R-trees exhibit poor disk performance. In this paper, we propose a cache and disk optimized R-tree, called the PR-tree (Prefetching R-tree). For the cache performance, the node size of the PR-tree is wider than a cache line, and the prefetch instruction is used to reduce the number of cache misses. For the I/O performance, the nodes of the PR-tree are fitted into one disk page. We represent the detailed analysis of cache misses for range queries, and enumerate all the reasonable in-page leaf and nonleaf node sizes, and heights of in-page trees to figure out tree parameters for best cache and I/O performance. The PR-tree that we propose achieves better cache performance than the disk-optimized R-tree: a factor of 3.5-15.1 improvement for one-by-one insertions, 6.5-15.1 improvement for deletions, 1.3-1.9 improvement for range queries, and 2.7-9.7 improvement for k-nearest neighbor queries. All experimental results do not show notable declines of the I/O performance.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.19-30
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• 2006

This study deals with the optimized detector location considering the traffic characteristics in National Highway. Although there ave many construction works for ITS in National Highway, there is not specific criteria for detector location which can effect the accuracy of traffic information. This study. therefore. aims to Provide the optimized detector location criteria which can represent the traffic characteristics of National Highway. It collects traffic factors of study area by GPS Probe-car and defector, and Presents the optimized detector location by the correlation analysis between spot-speed and link-travel-time. The main results of this study are as followings ; First, the correlation between the spot-speed and link-travel-time Presents the opposite bell shape of the graph (U-type owe) which is increased it?on the upstream then, declined through some unspecified Point of the link. Second, the optimized detector location usually distributes around midstream of link, even though it does not have a consistency. Third, therefore, the optimized detector location generally should be located between $55{\sim}60%$ of total link length. Forth. high level of vertical slope is one of the most important factors of detector location, so it should be excluded for determination of optimized detector location. Finally, expecting that the results of this study would improve the accuracy of travel time estimation and forecasting.

• Journal of Nutrition and Health
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• v.51 no.1
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• pp.73-86
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• 2018

Purpose: The aim of this study was to design optimized food intake patterns that meet the nutritional recommendations with minimal changes from the current food intake patterns among Korean adults using linear programming. Methods: Data of a one day 24-hour dietary recall from the 2010 ~ 2014 Korea National Health and Nutrition Survey were used to quantify the food items that Korean adults usually consumed. These food items were categorized into seven groups and 24 subgroups. The mean intakes and intake distributions of the food groups and the food subgroups were calculated for eight age (19 ~ 29, 30 ~ 49, 50 ~ 64, and over 65 years old) and gender (male and female) groups. A linear programming model was constructed to minimize the difference between the optimized and mean intakes of the food subgroups while meeting the Dietary Reference Intakes for Koreans (KDRIs) for energy and 13 nutrients, and not exceeding the typical quantities of each food subgroup consumed by the respective age and gender groups. Results: The optimized food intake patterns, which were a set of quantities of 24 food subgroups, were obtained mathematically for eight age and gender groups. Overall, major modifications of current diet were required to increase the intake of vegetables and milk/dairy products and decrease the Kimchi intake. The optimized intake of seasonings, including salt, was calculated to be 0 g for all the age and gender groups. Conclusion: The optimized food intake patterns designed using linear programming in this study lack feasibility because they suggest a seasoning consumption of 0 g. Modification of intake goal for sodium is needed to obtain optimized food intake patterns with improved feasibility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.2
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• pp.303-311
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• 2012

In this study, we introduce a dynamic process model as well as the design methodology of optimized fuzzy controller for its efficient application to vacuum production system to produce a semiconductor, solar module and display and so on. In a vacuum control field, PID control method is widely used from the viewpoint of simple structure and preferred performance. But, PID control method is very sensitive to the change of environment of control system as well as the change of control parameters. Therefore, it's difficult to get a preferred performance results from target system which has a complicated structure and lots of nonlinear factors. To solve such problem, we propose the design methodology of an optimized fuzzy PID controller through a following series of steps. First a dynamic characteristic of the target system is analyzed through a series of experiments. Second the process model is built up and its characteristic is compared with real process. Third, the optimized fuzzy PID controller is designed using genetic algorithms. Finally, the fuzzy controller is applied to target system and then its performance is compared with that of other conventional controllers(PID, PI, and Fuzzy PI controller). The performance of the proposed fuzzy controller is evaluated in terms of auto-tuned control parameters and output responses considered by ITAE index, overshoot, rise time and steady state time.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.3
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• pp.101-109
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• 2004

In this paper, we propose an efficient algerian for wavelet-based sti image coding method that utilizes the rate-distortion (R-D) theory. Since conventional tree-structured image coding schemes do not consider the rate-distortion theory properly, they show reduced coding performance. In this paper, we apply an rate-distortion optimized embedding (RDE) operation into the set partitioning in hierarchical trees (SPIHT) algorithm. In this algorithm, we use the rate-distortion slope as a criterion for the coding order of wavelet coefficients in SPIHT lists. We also describe modified set partitioning and rate-distortion optimized list scan methods. Experimental results demonstrate that the proposed method outperforms the SPIHT algorithm and the rate-distortion optimized embedding algerian with respect to the PSNR (peak signal-to-noise ratio) performance.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.285-295
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• 2016

A contact strip shape of a high speed train pantograph system was optimized with CFD to increase the aerodynamic performance and stability of contact force, and the results were validated by a wind tunnel test. For design of the optimal contact strip shape, a Kriging model and genetic algorithm were used to ensure the global search of the optimal point and reduce the computational cost. To enhance the performance and robustness of the contact strip for high speed pantograph, the drag coefficient and the fluctuation of the lift coefficient along the angle of attack were selected as design objectives. Aerodynamic forces were measured by a load cell and HWA (Hot Wire Anemometer) was used to measure the Strouhal number of wake flow. PIV (Particle Image Velocimetry) was adopted to visualize the flow fields. The optimized contact strip shape was shown a lower drag with smaller fluctuation of vertical lift force than the general shaped contact strip. And the acoustic noise source strength of the optimized contact strip was also reduced. Finally, the reduction amount of drag and noise was assessed when the optimized contact strip was applied to three dimensional pantograph system.

• Journal of Biosystems Engineering
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• v.32 no.3
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• pp.137-144
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• 2007

An anti-backlash gear was developed to reduce the rattle noise generated from the gearbox of a direct-engine PTO driveline of agricultural tractors under idling. A pair of gears using the anti-backlash gear as driven part was modeled and verified. Using the verified model, a computer simulation was conducted to investigate the effects of design parameters of the anti-backlash gear on the reduction of rattle noise. The optimum values of the design parameters were also determined by the computer simulation. The optimized anti-backlash gear was then manufactured and installed on the experimental PTO driveline for the performance test. Measurement of rattle noise was made to evaluate its performance before and after the driven gear of the PTO gearbox was replaced by the optimized anti-backlash gear. Results of the study were as follows: The optimum values of the design parameters, spring constant and deformation, may be determined by a relationship: $$k{\ge}\frac{4364.7}{150{\delta}-23.564}$$ The optimized anti-backlash gear reduced the rattle noise maximally by 16.9 dBA. This concluded that it would be most effective to use the optimized anti-backlash gear to eliminate the rattle noise in the PTO driveline.

• Journal of Korea Multimedia Society
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• v.10 no.1
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• pp.83-93
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• 2007

WFQ (Weighted Fair Queuing) is the most popular fair queuing algorithm, but it had the inherent drawback of a poet bandwidth utilization, particularly under the traffic requiring a low rate but tight delay bound such as internet phone. It was recently identified that the poor utilization is mainly due to the non-optimized latency of a flow and then LOFQ(Latency-Optimized Fair Queuing) to overcome the drawback was introduced. In this paper, we improve the performance of LOFQ by introducing an occupied resource optimization function and reduce the implementation complexity of recursive resource transformation by revising the transformation scheme. We also prove the superiority of LOFQ over WFQ in terms of utilization. The simulation result shows that the improved LOFQ provides $20{\sim}30%$ higher utilization than that in the legacy LOFQ.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.155-162
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• 2007

WFQ (Weighted Fair Queuing) is the most popular fair queuing algorithm, but it had the inherent drawback of a poor bandwidth utilization, particularly under the traffic requiring a low rate but tight delay bound such as internet phone, It was recently identified that the poor utilization is mainly due to non optimized latency of a flow and then LOFQ(Latency-Optimized Fair Queuing) to overcome the drawback was introduced, LOFQ was also improved through introducing an occupied resource optimization function and the implementation complexity of recursive resource transformation was reduced with revising the transformation scheme. However, the performance of LOFQ has been evaluated by means of simulation, so that there are some difficulties in evaluating the performance in the terms of the accuracy and evaluation time, In this paper, we develop how to analytically compute the bandwidth utilization in LOFQ.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.123-129
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• 2004

Rolling bearings are assorted one of the most important machine elements. The various functions of bearings are greatly influenced by grease, and higher performance of rolling bearing greases is required to improve rolling bearing lubrication. The two conditions for optimum grease synthesis were selected by SSRED (Six Sigma Robust Engineering Design) program by using dropping points and OIT values respectively. And the optimized two urea/ether oil greases were synthesized to compare the performance. The typical physical properties of grease were investigated. And life test of these greases was conducted by rolling bearing grease life tester The characteristics of the greases before and after life test were investigated using FTIR, microscope, SEM, TG/DSC, OIT and TAN meter The optimized two greases showed longer life time than typical urea/ether oil grease. The optimized grease by means of OIT value showed higher performance such as long life time. low TAN value and high oil bleeding amount in comparison with the optimized grease using dropping point.