• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.2
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• pp.125-134
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• 2016

NAND flash memory has unique characteristics like as 'out-place-update' and limited lifetime compared with traditional storage systems. According to out-of-place update scheme, a number of invalid (or called dead) pages can be generated. In this case, garbage collection is needed to reclaim invalid pages. Because garbage collection results in not only erase operations but also copy operations of valid (or called live) pages to other blocks, many garbage collection techniques have proposed to reduce the overhead and to increase the lifetime of NAND Flash systems. This techniques sometimes select victim blocks including cold data for the wear leveling. However, most of them overlook the cost of selecting victim blocks including cold data. In this paper, we propose a garbage collection technique named CAPi (Cost Age with Proportion of invalid pages). Considering the additional overhead of what to select victim blocks including cold data, CAPi improves the response time in garbage collection and increase the lifetime in memory systems. Additionally, the proposed scheme also improves the efficiency of garbage collection by separating cold data from hot data in valid pages. In experimental evaluation, we showed that CAPi yields up to, at maximum, 73% improvement in lifetime compared with existing garbage collections.

• Korean Journal of Animal Reproduction
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• v.9 no.1
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• pp.40-45
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• 1985

Eight 2-yr old bulls from Artificial Breeding Center, NLCF were used to determine the effectof collection frequency on semen characteristics and sexual activity. Two successive ejaculates per day were collected by artificial vagina for 4 weeks on weekly or twice a week. Total ejaculate volume included 2nd ejaculates for one time and two time bulls was 6.8ml and 6.0ml, but there was no significant difference between collection intervals. Sperm concentration of one time and two time bulls averaged 0.79$\times$109/ml and 0.89$\times$109/ml, respectively. Total sperm per ejaculate was 5.14$\times$109 for one time bulls and 5.45$\times$10 for two time bulls. Two time bulls had slight more sperm per ml and ejaculate than one time bulls, but there were no significant differences between two group bulls. Sperm motility and semen pH of two time bulls was slightly better than that of one time bulls. In changes of bulk minerals in semen, solium concentration of two time bulls was similar to that of one time bulls. Potassium and calcium was more concentrated in one time bulls than in two time bulls, but these concentrations did not differ significantly. Libido score for two time bulls was higher than that for one time bulls. However, there was no difference between two groups and these scores did not change for 4 weeks in two goups. Total time to 2nd ejaculation was 16.3 sec for one time bulls and 20.5 sec for two time bulls.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.422-428
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• 2009

NAND flash memory is widely used in embedded systems because of many attractive features, such as small size, light weight, low power consumption and fast access speed. However, it requires garbage collection, which includes erase operations. Erase operation is slower than other operations. Further, a block has a limited erase lifetime (typically 100,000) after which a block becomes unusable. The proposed garbage collection policy focuses on minimizing the total number of erase operations, the deviation value of each block and the garbage collection time. NAND flash memory consists of pages of three types, such as valid pages, invalid pages and free pages. In order to achieve above goals, we use a page ratio to decide when to do garbage collection and to select the target victimblock. Additionally, we implement allocating method and group management method. Simulation results show that the proposed policy performs better than Greedy or CAT with the maximum rate 85% of reduction in the deviation value of the erase operations and 6% reduction in garbage collection time.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.617-625
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• 2009

NAND flash memory is widely used in embedded systems because of many attractive features, such as small size, light weight, low power consumption and fast access speed. However, it requires garbage collection, which includes erase operations. Erase operation is very slow. Besides, the number of the erase operations allowed to be carried out for each block is limited. The proposed garbage collection method focuses on minimizing the total number of erase operations, the deviation value of each block and the garbage collection time. NAND flash memory consists of pages of three types, such as valid pages, invalid pages and free pages. In order to achieve above goals, we use a page rate to decide when to do garbage collection and to select the target victim block. Additionally, We implement allocating method and group management method. Simulation results show that the proposed policy performs better than Greedy or CAT with the maximum rate at 82% of reduction in the deviation value of erase operation and 75% reduction in garbage collection time.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.1-11
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• 2009

TCS Data imply characteristics of traffic conditions. However, there are outliers in TCS data, which can not represent the travel time of the pertinent section, if these outliers are not eliminated, travel time may be distorted owing to these outliers. Various travel time can be distributed under the same section and time because the variation of the travel time is increase as the section distance is increase, which make difficult to calculate the representative of travel time. Accordingly, it is important to grasp travel time characteristics in order to compute the representative of travel time using TCS Data. In this study, after analyzing the variation ratio of the travel time according to the link distance and the level of congestion, the outlier elimination model and the smoothing model for TCS data were proposed. The results show that the proposed model can be utilized for estimating a reliable travel time for a long-distance path in which there are a variation of travel times from the same departure time, the intervals are large and the change in the representative travel time is irregular for a short period.

• Journal of Korea Society of Digital Industry and Information Management
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• v.16 no.1
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• pp.33-39
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• 2020

A smart grid is a next-generation power grid that can improve energy efficiency by applying information and communication technology to the general power grid. The smart grid makes it possible to exchange information about electricity production and consumption between electricity providers and consumers in real-time. Advanced metering infrastructure (AMI) is the core technology of the smart grid. The AMI provides two-way communication by installing a modem in an existing digital meter and typically include smart meters, data collection units, and meter data management systems. Because the AMI requires data collection units to control multiple smart meters, it is essential to ensure network availability under heavy network loads. If the load on the work done by the data collection unit is high, it is necessary to allocation new data collection units to ensure availability and improve energy efficiency. In this paper, we discuss the allocation scheme of data collection units for the energy efficiency of the AMI.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.3
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• pp.279-287
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• 1996

Pressure drop and fractional collection efficiency of automotive cabin air filters were examined to obtain the basic data for the development of high performance domestic cabin air filters. Pressure drop of MA-V100 was higher than that of VF-V100, and it increased with the air flow rate. VF-V100 had longer time to rise the critical pressure drop than that MA-V100 had. Total collection efficiency of MA-V100 for initial and dust loaded conditions was higher than that of VF-V100. Also, fractional collection efficiency of MA-V100 for the fine particles was higher than that of VF-V100. Particla size distribution for the minimum collection efficiency ranged from 0.02 $\mu$m to 0.04 $\mu$m for MA-V100 and it ranged from 0.02 $\mu$m to 0.15 $\mu$m for VF-V100.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.276-277
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• 2002

One of drawbacks of the inertial impactor measurement is the required long sampling time (Keskinen et al., 1992). In a gravimetric method, an impaction substrate must be weighed and placed on the corresponding collection plate before being assembled. After sampling, the inertial impactor is disassembled and the collection plate is weighted again. The sampling time depends on the sampled particle mass because the collected particle mass must be sufficiently high to be measured by a sensitive microbalance. (omitted)

• Korean Journal of Medicinal Crop Science
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• v.26 no.3
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• pp.214-219
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• 2018

Background: This study was carried out to determine the best time for collecting ginseng berries without reducing the ginsenoside-Re content of ginseng roots, which are used as food, medicine, or cosmetic materials. Methods and Results: The test variety of ginseng used in this study was is Chunpung, which was collected from a 4-year-old ginseng field. Ginseng berries were collected at 7, 14, 21, 28, 35, 42, 49, and 56 days after flowering. The number of berry bunches per $1.62m^2$ ranged from 43.4 to 61.4, while the weight of berries per $1.62m^2$ was the greatest when they were collected 49 days after flowering. The root fresh weight per $1.62m^2$ was increased by 0.21 - 1.00 kg compared with that before the test, but root weight gain was decreased as the berry collection time was delayed. Total ginsenoside content of 4-year-old ginseng was the highest when berries were collected 7 days after flowering, while the ginsenoside-Re contents was the highest when collection was done 14 days after flowering. Conclusions: The most suitable period for ginseng berry collection was proposed to be from 14 to 21 days after flowering, as this is when the content of ginsenoside-Re, which is useful as a medicinal or cosmetic material, is still high and the ginseng root has not yet decreased in weight.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.485-492
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• 2013

The effect on collection efficiency with 2-stage vortex finder diameter and back mixing of solid flow due to swirling intensity, turbulence eddies, wall bouncing using the residence time distribution of particle flow in a common and modified cyclone. Higher collection efficiencies of fly ash in a modified cyclone(S = 13, 15cm) are showed than common cyclone. Collection efficiency in modified cyclone was highest at 2-stage vortex finder diameter, S = 13 cm. Variances of residence time distribution and average residence times of glass bead were increased with a diameter(S) of 2-stage vortex finder due to swirling intensity and turbulence eddies. Back mixing of solid flow in a modified cyclone were increased with a gas inlet velocity and showed higher than a common cyclone.