• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.21-25
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• 2009

The results of a recent case study for material characterizations and structural evaluation to design asphalt overlay thickness of William P Hobby airport in Houston, Texas are presented herein. The existing runway 12R-30L of Hobby airport consisted of thick asphalt overlay over Portland Cement Concrete (PCC) and the localized surface shoving as evident in the closure of surface groove has been observed recently. Using the field cored asphalt concrete mixtures, measurements of percent air voids, asphalt content and aggregate gradation were conducted to find out the causations of surface shoving and groove closure. The FAA layered elastic program, LEDFAA was utilized to evaluate pavement structural conditions for new asphalt overlay. Two different composition assumptions for existing pavement were made to evaluate the pavement as followings: 1) APC, Asphalt Concrete Overlay over PCC pavement and 2) AC, Asphalt Concrete pavement. Based on laboratory testing results, a ratio of percent passing #200 to asphalt content ranged 1.1 to 2.2, which is considered a high ratio and a tendency of tender mix design was observed. Thus, the localized surface shoving and groove closure of the runway 12R-30L could be attributed to the use of excessive fine contents and tender mix design. Based on the structural evaluation results, it was ascertained that the analysis assuming the pavement structure as AC pavement gives more realistic structural life when the asphalt overlay is thicker enough compared to PCC layer because the existing PCC pavement under asphalt overlay acts more like a high quality base material.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.527-535
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• 2017

Heat management is one of the most critical issues in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) installed inside the fuel cell power pack of a fuel cell battery hybrid UPS. If the heat generated by the chemical reaction in the fuel cell is not rapidly removed, the durability and performance of the fuel cell may be affected, which may shorten its lifetime. Therefore, the objective of this study is to select and propose a proper cooling method for the fuel cells used in the fuel cell power pack of a UPS. In order to find the most appropriate cooling method, the various design factors affecting the cooling performance were studied. The numerical analysis was performed by a commercial program, i.e., COMSOL Multiphysics. Firstly, the surface temperature of the 1 kW class fuel cell stack with the cooling fans placed at the top was compared with the one with the cooling fans placed at the bottom. Various rotation speeds of the cooling fan, viz. 2,500, 3,000, 3,500, and 4,000 RPM, were tested to determine the proper cooling fan speed. In addition, the influence of the inhaled air flow rate was investigated by changing the porous area of the grille, which is the entrance of the air flowing from the outside to the inside of the power pack. As a result, it was found that for the operating conditions of the 1 kW class PEMFC to be acceptable, the cooling fan was required to have a minimum rotating speed of 3500 RPM to maintain the fuel cell surface temperature within an acceptable range. The results of this study can be effectively applied to the development of thermal management technology for the fuel cells inside the fuel cell power pack of a UPS.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.1
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• pp.1-6
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• 2017

Recent researches on radio frequency energy harvesting networks(RF-EHNs) with limited energy resource like battery have been focusing on the development of a new scheme that can effectively extend the whole lifetime of a network to semipermanent. In order for considerable increase both in the amount of energy obtained from radio frequency energy harvesting and its charging effectiveness, it is very important to design a network that supports energy harvesting and data transfer simultaneously with the full consideration of various characteristics affecting the performance of a RF-EHN. In this paper, we proposes an interference-based charging aware routing protocol(ICARP) that utilizes interference information and charging time to maximize the amount of energy harvesting and to minimize the end-to-end delay from a source to the given destination node. To accomplish the research objectives, this paper gives a design of ICARP adopting new network metrics such as interference information and charging time to minimize end-to-end delay in energy harvesting wireless networks. The proposed method enables a RF-EHN to reduce the number of packet losses and retransmissions significantly for better energy consumption. Finally, simulation results show that the network performance in the aspects of packet transmission rate and end-to-end delay has enhanced with the comparison of existing routing protocols.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.552-555
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• 2009

A new standard rose cultivar "Snow Day" was bred from the cross between pink standard cultivar "Saphia" and pink standard cultivar "Bridal Beauty" at the National Institute of Horticulture & Herbal Science. The cross was made in 2003 and "Snow Day" was finally selected in 2008 after evaluating characteristics for three years from 2006 to 2008. A white standard cultivar, "Snow Day" grows vigorously and resistant to powder mildew. The major characteristics of this cultivar are $152stems/m^2/year$ in yield, 81.8 cm in length of cut flower, 11.3 cm in flower diameter, 29.2 in petal number, and 13.7 days in vase life. This cultivar can be propagated by both cutting and grafting. The consumer's preference for this cultivar is relatively higher than that for the control cultivar, "Tineke".

• FLOWER RESEARCH JOURNAL
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• v.19 no.4
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• pp.251-254
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• 2011

A new standard white-pink flower rose cultivar 'Innocence' was bred from the cross between white standard cultivar 'Juvena' and green-white standard cultivar 'Green Success' at the Jeollanamdo Agricultural Research and Extension Services (JARES). The cross was made in 2001 and, 'Innocence' was finally selected in 2006 after investigating characteristics for three times from 2004 to 2006. 'Innocence' a white-pink standard cultivar has good flower shape with few prickles. The major characteristics of this cultivar were $118.7stems{\cdot}m^{-2}$ in year yield, 68.0 cm in length of cut flower, 10.9 cm in flower diameter, 34.4 in petal number, and 10.7 days in vase life. This cultivar can be propagated by both cutting and grafting. The consumer's preference of this cultivar was relatively higher than that of control cultivar, 'Rose Yumi'.

• FLOWER RESEARCH JOURNAL
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• v.19 no.3
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• pp.164-167
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• 2011

A new spray rose cultivar 'Glory Purple' was bred from the cross between a pink spray cultivar 'Macarena' and a pink spray cultivar 'Million Pink' at the National Institute of Horticulture & Herbal Science. The cross was made in 2004 and a candidate genotype which named as 'Glory Purple' was selected in 2009 after three years investigation for agronomical characters from 2007 to 2009. 'Glory Purple', a purple colored spray cultivar, has vigorous growth and has powdery mildew resistance. The major characteristics of this cultivar are high yield and long stem with relatively large flower size with $157stems/m^2/year$ in yield, 63.5 cm in mean length of cut flower, 6.8 cm in mean flower diameter, 25.78 in mean petal number, and 10.2 days in mean vase life. This cultivar is suitable for propagation by both cutting and grafting methods. The consumer's preference of this cultivar is relatively higher than that of the control cultivars, 'Pinky and Charming'.

• FLOWER RESEARCH JOURNAL
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• v.19 no.2
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• pp.115-118
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• 2011

A light pink single freesia (Freesia hybrida Hort.) 'Bolero' was developed from a cross of breeding line ('Yellow Ballet' and 'Yellow Dream') and 'Sandra' followed by seedling and line selections at the National Institute of Horticultural and Herbal Science (NIHHS), Rural Development Administration (RDA) in 2007. Growth and flowering characteristic tests were conducted from 2003 to 2006. 'Bolero' has single type flower with light pink color (RHS, R55B). It has multiple florets, stable flower shape, upright leaves and stalks. The average cut flower yield of 'Bolero' observed in the greenhouse from 2005 to 2007 was 7.5 cuttings per plant. It has good production of cormlets and vigorous growth. 'Bolero' could be cultured under greenhouse conditions in Korea.

• Korean Journal of Comparative Education
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• v.24 no.3
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• pp.179-198
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• 2014

The purpose of this study is to find some implications for improving diversities of the senior high school system in Korea, by examining those of Australian high school system. Based on the literature review, school diversification can be defined as providing students or their parents with some range of alternative programs from which they can choose a school or program they believe are best suitable for them. In this point, the concept is very similar to that of school choice. The finding of this study can be summarized as follows. First, the programs of within-school diversification at Australian senior secondary schools include subject selecting, extension programs and vocational education and training courses(VET). Second, selective schools, independent schools and specialist schools are the types of between-schools diversity programs in Australia. Third, the characteristic of Australian school diversification was traditionally between-schools diversification, of which the purpose is to provide excellent learning opportunities for some talented students. However, the policy trend has, recently, been extended to within-school diversity programs. The conclusions of this study are as follows. First, the policy of high school diversification 300 in Korea can be seen as a suitable one because one of its aims was to overcome some limitations of the school equalization policy. Second, well defined within-school diversity programs should be considered in order to avoid educational disadvantage issues in education that can be inevitably risen from between-school diversification policies. Lastly, the possibilities of implementing VET programs at general high schools should also be urgently considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.117-124
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• 2019

Military Vehicles of the Korean army had been developed before 2004 and used manual transmissions. Manual transmissions contain a clutch system regulating the force from engine to transmission. In this study, a 2.5-ton military vehicle's clutch system was investigated. The existing clutch system had the characteristics that need to adjust the clearance between the clutch cover and release bearing. Improper clearance led to early wear of the clutch disk and failure of the clutch cover. To solve these problems, an improved clutch system was suggested and tested. The improved clutch system contains auto adjustment of the clearance and an enhanced clutch disk. To verify the improved clutch systems, 2 stage tests were conducted: an accelerated life test of the clutch system, and a driving test by trainee of driving more than 3,000km. As a result, the problems caused by the improper clearance adjustment were solved and this design was verified.

• Journal of the Korean Electrochemical Society
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• v.22 no.4
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• pp.148-154
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• 2019

Vanadium oxide based materials have been studied as novel negative electrode materials in lithium-ion batteries (LIBs) because of their high specific capacity. In this study, potassium metavanadate ($KVO_3$) was synthesized and its electrochemical properties are evaluated as a negative electrode materials. The aqueous solution of $NH_4VO_3$ is mixed with a stoichiometric amount of KOH. The solution is boiled to remove $NH_3$ gas and dried to obtain a precipitate. The obtained $KVO_3$ powders are heat-treated at 300 and $500^{\circ}C$ for 8 h in air. As the heat treatment temperature increases, the initial reversible capacity decreases, but the cycle performance and Coulombic efficiency are improved slightly. On the contrary, the electrochemical performances of the $KVO_3$ electrodes are greatly improved when a polyacrylic acid (PAA) as binder was used instead of polyvinylidene fluoride (PVDF) and a fluoroethylene carbonate (FEC) was used as electrolyte additive. The initial reversible capacity of the $KVO_3$ is 1169 mAh/g and the Coulombic efficiency is improved to 76.3% with moderate cycle performance. The $KVO_3$ has the potential as a novel high-capacity negative electrode materials.