• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.726-733
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• 2017

A magnetic shutter gear is a device that transfers mechanical power by synchronizing the magnetic field between permanent magnet layers facing circumferentially through a harmonic modulator. However, magnetic gears uses many rare-earth permanent magnets to guarantee comparable torque density to that of mechanical reducer. Hence, we propose a novel axial magnetic gear with a dramatically reduced number of permanent magnets and a closed magnetic path. The torque of the system was compared to that of an existing shutter gear through a harmonic analysis of the air-gap magnetic field. The modulator thickness and open ratio were considered as the primary design parameters, and the cogging effect was analyzed for variation of the reduction ratio. A dynamic model between the high-speed side and low-speed side was derived, and position control was performed for a constructed hardware implementation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.900-907
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• 2009

In this research, railway transportation by means of the characteristics of tourism in the selection of railroad tourism and to clarify the difference in IPA is a primary purpose of this research. In addition, the train travel experience would like to clarify the difference in the importance and performance. This research fellows the indication points. First, by means of transportation to select train tourism product is the difference in the importance and performance in the 25 items. Second, the urgent needs to improve part 'Concentrate Here' side of the train, the temperature of the reasonable air-conditioning, and the appropriate means of transport links to the information service has been identified.'Low Priority' side of the entry tourist train operation of the frequency and interval, a total of 26 items, including the efforts of more than the current level of commitment was expected to be unnecessary. Third, according to the experience of sightseeing train railway transportation as a means to help train tourism product selection was the difference in the importance and performance.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.3
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• pp.291-302
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• 2011

[ $PM_{10}$ ]measurements were made at two coastal sites, i.e., Taean and Gangneung, for summer to examine the characterization of water-soluble organic carbon (WSOC) and inorganic ionic species, and to investigate their difference between the sites. The fractions of three major inorganic water-soluble components ($NO_3^-$, $SO_4^{2-}$, and $NH_4^+$) at Taean and Gangneung sites were 30.6% (16.2~62.0%) and 25.6% (13.0~52.5%) of the $PM_{10}$, respectively. $SO_4^{2-}$ is the most dominant species of water-soluble ions at both sites, accounting for up to 20.5% (9.1~44.9%) and 16.3% (5.5~34.2%) of their respective PM10 mass concentrations. Using the paired T-test, $PM_{10}$ (p<0.01), $NO_3^-$ (p<0.05), $SO_4^{2-}$ (p<0.01), $NH_4^+$ (p<0.001), and WSOC (p<0.05) concentrations exhibited strong fluctuations on a daily basis between Taean and Gangneung sites. Relationship between the concentrations of $SO_x$ ($SO_4^{2-}+SO_2$) and CO indicates that the slopes of $SO_x$ /CO were 0.007 and 0.019 in the Taean and Gangneung sites, respectively. The smaller $SO_x$/CO slope in the Taean site could be related to the aged air with wet scavenging of $SO_x$ during transport. The correlation between the concentrations of CO and WSOC suggests that WSOC observed in the Gangneung ($R^2$=0.82) be transported from combustion-related sources, while the WSOC at the Taean site could be formed through atmospheric processing of primary volatile organic species during transport.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.206-219
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• 2008

The purpose of this study is to evaluate concentrations of carbonyl compounds during summer season in Seoul metropolitan area. The air samples were collected at 7 sites in this area from June 2001 to June 2003. The carbonyl compounds were analyzed by DNPH/HPLC method. The analytical method applied in this study showed good repeatability, linearity, and sensitivity. The most abundant carbonyl was formaldehyde (average 4.48 ppb), and followed by acetone, acetaldehyde, methyl ethyl ketone, butyraldehyde, propionaldehyde and benzaldehyde, respectively. Concentrations of carbonyl compounds in June were higher than those in August. There was not only higher solar radiation but also higher ozone concentration in June than in August. As a result o photochemical reactions, carbonyl compounds from both primary and secondary sources are likely to contribute to the formation of ozone. The contributions to photochemical ozone creation of two carbonyl compounds such as formaldehyde and acetaldehyde were estimated to be about 70%. Ratios of formaldehyde to acetaldehyde in this study ranged from 1.13 to 4.26, which are generally equivalent levels to those of other urban areas in domestic and foreign countries.

• Asian Journal of Atmospheric Environment
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• v.11 no.3
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• pp.165-175
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• 2017

In Japan, the primary carbonaceous particles emitted from motor vehicles and waste incinerators have been reduced due to strict regulations against exhaust gas. However, the relative contribution of carbonaceous particles derived from plants and biomass has been increasing. Accordingly, compositional analysis of carbonaceous particles has become increasingly important to determine the sources and types of particles produced. To reveal the sources of the organic particles contained in particulate matter with diameters of ${\leq}2.5{\mu}m$ ($PM_{2.5}$) and the processes involved in their generation, we analyzed molecular marker compounds (2-methyltetrols, cis-pinonic acid, and levoglucosan) derived from the plants and biomass in the $PM_{2.5}$ collected during daytime- and nighttime-sampling periods in summer (July and August) and autumn (November) in Kazo, which is in the northern area of Saitama prefecture, Japan. We also measured $^{14}C$ carbonaceous concentrations in the same $PM_{2.5}$ samples. The concentrations of 2-methyltetrols were higher in the summer than in the autumn. Because the deciduous period overlaps with this decrease in the levels of 2-methyltetrols, we considered the emission source to broad-leaved trees. In contrast, the emission source of the cis-pinonic acid precursor was considered to be conifers, because its concentration remained almost constant throughout the year. The concentration of levoglucosan was considerably increased in the autumn due to frequent biomass open burning. The ratio of plant-derived carbon to total carbon, obtained by measuring of $^{14}C$, in summer $PM_{2.5}$ sample was higher in the nighttime, and could be influenced by anthropogenic sources during the daytime.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.170-178
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• 2005

Multi-hole type oxygen combustion burner was developed for industrial gasification and smelting furnace. We investigated characteristics of flame, radiation transfer, and soot emission in the convectional oxygen burner with respect to the feeding condition of fuel and oxygen. Regarding the results of the conventional burner, we designed new burners which have larger fuel consumption rate and radiation heat transfer. We changed the size and hole number and shape of the exit plane of the burner. In addition, the performance of the burner was tested with respect to the feeding condition of the fuel and air: Normal Diffusion flame(NDF) and Inverse Diffusion Flame(IDF). We investigated the flame configuration, radiation heat transfer, and soot formation by using a CCD camera, heat flux meter, and Laser Induced Incadescence(LII), respectively. The stable operating condition was obtained by the flame configuration and the flame of the burner which has dented exit plane was more stable in whole operating conditions. The characteristics of radiative heat transfer were sensitive to the feeding condition of reactants and the flame of 75% primary oxygen and 25% secondary oxygen of the IDF case shows maximum radiation heat transfer. The soot volume fraction of the flame was measured in the axial direction of the flame and the amount of soot volume fraction is proportion to the radiation heat transfer. As a result, we can get the optimal operating condition of the newly designed burner which enhances the characteristics of flame stabilization and radiation heat transfer.

• Journal of Aerospace System Engineering
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• v.10 no.4
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• pp.98-104
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• 2016

This research describes the functional requirements of anti-ship ballistic missile (ASBM) defense systems, which depend on the threat characteristics of the ASBM. Recently, China has carried out a training launch of the DF-21D strategic countermeasures for the placement of Korean terminal high-altitude air defense (THAAD). The ASBM is being used as a primary means of attacking aircraft carriers, using an anti-access/area denial (A2/AD) strategy. Considering the missile technology connection between China and North Korea, there is a very high probability that North Korea already owns an ASBM. From this point of view, work with Aegis operational concepts provided implications for an ASBM threat. Utilizing quality function deployment (QFD) based on the operational concepts, the functional requirement were calculated.

• Food Science and Preservation
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• v.16 no.2
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• pp.253-258
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• 2009

This study investigated the effects of mycelium and culture supernatant of Cordyceps ochraceostromat(Co) on air way hyper-responsiveness, pulmonary immune cell infiltration, and Th2 cytokine expression in animal models of atopy and asthma. After ConA(+/-) activation of mouse primary spleen cells, decreased IL-4 and IL-13 cytokine production were seen in the presence of Co mycelium extracts and culture supernatant. The asthma model involved mice sensitized to ovalbumin by i.p. injection treatment; Co mycelium extract was also injected. The atopy model was the dinitrofenylbenzene-treated mouse ear. Ear thicken ing induced by DNFB was decreased by Co mycelium extract, and the extract also inhibited lung cell infiltration in ovalbumin-induced asthmatic mice. The results thus indicated that the Co mycelial extract reduced the undesirable immune responses seen in asthma and atopy.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.18 no.2
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• pp.145-153
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• 2007

Objectives: This study was focused on the influence of chronic aircraft noise exposure on children's continuous performance, intelligence and reading skill. Methods: We enrolled 586 children in 4-6th grade of 7 primary schools near air base in Korea. Continuous performance was measured using the computerized ADS program. We analyzed 477-512 children on the visual continuous performance test, auditory continuous performance test, intelligence test, and reading and the vocabulary test. Intelligence was measured using vocabulary, digit span, block design, and digit symbol tests of K-WISC-III. Results: The commission error and variability deviation of auditory continuous performance test and reading test were significantly higher among children in schools with the helicopter noise and the fighting plane noise compared to children in the low noised schools. Conclusion: There was a possibility that chronic aircraft noise exposure was associated with impairment of the school performance. The result of our study also shows chronic aircraft noise was associated with reading ability.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.413-420
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• 2020

The Tactical Information and Communication Network system provides real-time multimedia services such as voice and data by utilizing the Mobile Subscriber Access Point. At this time, an external transmission path is constructed through the Low Capacity Trunk Radio and the High Capacity Trunk Radio system. The communication devices of each wireless transmission system are mounted on a tactical vehicle and a secondary battery is used to prevent a power interruption when the supply power to the tactical vehicle is transferred to the integrated power control device. In this paper, the basic design of the Wireless Power Transfer device for charging the battery of the integrated power control system of the mobile base station system using the Loading Distribution Method and checking the number of primary windings and the core material selection by the air gap through the Finite Elements Method.