• Korea journal of population studies
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• v.29 no.3
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• pp.1-27
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• 2006

Labor market participation and occupational status for workers majoring in(natural) science and engineering are estimated and compared with workers of other majors at three levels: employment, prestigious occupations, and good occupations. For this, we utilized 2% Public Use Sample of 2000 Korea Census. The results of two-stage probit models, which adjust sample selection bias, do not support the argument that graduates of science and engineering majors are relatively disadvantaged. Workers of engineering majors are more likely to have 'good occupations' at their early job careers, but their advantages fade away quickly as they are aging. Especially at their 40s, their probability of having 'good occupations' start to be likely lower than workers of social science majors. This may be due to low human capital accumulation rates at work places along with quickly outdated skills which are acquired in colleges.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.50-55
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• 2000

Soluble methyl-hesperidin (MH) powder was prepared from crude MH, and was investigated on the stabilization to sunlight of natural coloring matter. Soluble MH powder was added to riboflavin, bixin, and paprika oleoresin solutions at concentration of 0.1 or 0.2%(w/w), and the absorbance of respective solutions was analyzed by spectrophotometer after exposing to sunlight for $10{\sim}24$ hr. While coloring matter solutions without MH was faded completely with lapse of time, addition of MH retarded to fade natural coloring matters. According as amount of MH added increased, MH showed more excellent stabilizing effect on the coloring matters. Especially, vitamin C with soluble MH showed remarkable synergistic effect in paprika oleoresin solution during the exposure to sunlight for 8 hr. Consequently, it was found that MH plays a role as excellent stabilizer of natural coloring matters to ultraviolet of sunlight.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1042-1049
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• 2014

In Military MicroWave communication, the distance of link, availability, transmission capacity is the important point in order to design the circuit. Currently, operated by fixed modulation, in the future it will be evolved to the modulation techniques enabled to increase the transmission capacity. It would be hard to consistently guarantee the transmission quality of the high-availability because the occurrence probability of fading increase in terms of the link distance for the case of the long distance. In the case of the modulation techniques for the transmission of high-capacity, as the distance is long, a falling-off in the fade margin from the link budget analysis cause the decrease in the availability. It is difficult to provide QoS guaranteed connection. In this paper, we propose the performance improvement technique of transmission by the variable allocation of the bandwidth and the higher priority transmission technique using setting the ratio of the higher priority capacity in association with the distance of link. Also we suggest the alternative of the calculation for channel transmission capacity to design the circuit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4192-4200
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• 2015

In this paper, dispersibility of steel fiber is improved mixing with form for material development of protection and blast resistant structure sprayed concrete. And it is developed a high toughness cellular sprayed concrete material using steel fiber. Oversupply form for dispersibility improvement of steel fiber is mostly fade away through sprayed, finally it is satisfied with the proper mixing ratio under 3 % ~ 6 %. This is considered for compressive strength and flexural toughness. Test results of compressive strength showed superior strength capability in 28, 56 days, also flexural strength and flexural toughness is great. Then oversupply form is enhanced for dispersibility of steel fiber and I think that it did not cause decreasing of strength. But analysis results of pore structure through image analysis failed for a great spacing factor and specific surface area. This is largely measured in spacing factor because air content have a grate evaporation effect for sprayed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8A
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• pp.786-795
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• 2002

In this paper, we present a histogram and moment-based vidoe scencd change detection technique using hierarchical Hidden Markov Models(HMMs). The proposed method extracts histograms from a low-frequency subband and moments of edge components from high-frequency subbands of wavelet transformed images. Then each HMM is trained by using histogram difference and directional moment difference, respectively, extracted from manually labeled video. The video segmentation process consists of two steps. A histogram-based HMM is first used to segment the input video sequence into three categories: shot, cut, gradual scene changes. In the second stage, a moment-based HMM is used to further segment the gradual changes into a fade and a dissolve. The experimental results show that the proposed technique is more effective in partitioning video frames than the previous threshold-based methods.

• Tribology and Lubricants
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• v.17 no.4
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• pp.267-275
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• 2001

Friction and wear properties of brake friction materials containing different metal fibers (Al, Cu or Steel fibers) were investigated. Based on a simple experimental formulation, friction materials with the same amount of metal fibers were tested using a pad-on-disk type friction tester. Two different materials (gray cast iron and aluminum metal matrix composite (MMC)) were used for disks rubbing against the friction materials. Results front ambient temperature tests revealed that the friction material containing Cu fibers sliding against gray cast iron disk showed a distinct negative $\mu$-v (friction coefficient vs. sliding velocity) relation implying possible stick-slip generation at low speeds. The negative $\mu$- v relation was not observed when the Cu-containing friction materials were rubbed against the Al-MMC counter surface. Elevated temperature tests showed that the friction level and the intensity of friction force oscillation were strongly affected by the thermal conductivity and melting temperature of metallic ingredients of the friction couple. Friction materials slid against cast iron disks exhibited higher friction coefficients than Al-MMC (metal matrix composite) disks during high temperature tests. On the other hand, high temperature test results suggested that copper fibers in the friction material improved fade resistance and that steel fibers were not compatible with Al-MMC disks showing severe material transfer and erratic friction behavior during sliding at elevated temperatures.

• Tribology and Lubricants
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• v.30 no.6
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• pp.323-329
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• 2014

The friction-reducing properties of lubricants containing ionic liquids based on ammonium dithiocarbamate are studied. The ionic liquids are produced through the following two steps: the synthesis of sodium alkyl dithiocarbamates via the substitution reaction of dialkylamine and carbon disulfide and their subsequent conversion into ammonium dithiocarbamate-based ionic liquids through an ion-exchange reaction with a quaternary alkyl ammonium halide salt. The structures of the ionic liquids are characterized by NMR spectroscopy and Fourier transform infrared spectroscopy. The isolated yields of the ionic liquids, which are viscous and pale yellow, are approximately 92%. The Brookfield viscosities and pour points of the ionic liquids are determined. Further, their wear resistances are measured through the four-ball wear test and the Schwingung Reibung Ver-schleiss (oscillation, friction, wear) test. The wear scar diameter of the lubricants containing 1 wt of the quaternary alkyl ammonium dithiocarbamate-based ionic liquids (0.475-0.631 mm) is significantly lower than that of the base oil (0.825 mm), proving that the ammonium dithiocarbamate-based ionic liquids have good friction-reducing characteristics. However, these friction-reducing characteristics fade significantly after long-term storage, owing to the degradation of the ionic liquids.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.223-230
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• 2008

This paper deals with the measurements of wireless image signal in subway tunnels at 2.45GHz. Measurements have been conducted in 3 subway stations with different types; a straight tunnel and two curved tunnels. As a analysis result for the measured data, we found that the signal level inside straight tunnel by the strong multipath waves fluctuate deeply compared to the curved tunnel. The path loss exponent for the Shin-hung station with the straight tunnel is 2.5, those for the Pan-am and Dae-dong station with curved tunnels are 1.6 and 1.9, respectively. The fade depth and width at 50% point became relatively serious at Shin-hung station, the level crossing rate inside the Pan-am station is larger than the other stations. Therefore, it can be concluded that the fading phenomena affect to the signal performance generate seriously at straight tunnel compared to the curved tunnel.

• Cross-Cultural Studies
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• v.27
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• pp.415-434
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• 2012

The Hanja used in Korean are traditional Chinese characters, but what Chinese people use now is simplified characters. So, there are differences in pronunciation and meaning between the characters used by Korean and Chinese. More than 70% of the Korean language vocabulary derived from or were influenced by hanja. For the inheritance and development of traditional culture,and for the communication among countries of the Chinese characters cultural circle in Northeast Asia, should we build up an authentic Chinese education system. But the government hasn't pay much attention to this work, and the government's policy can't implement the efficient education. Consequently, in these days, there are more and more Korean people who are functionally illiterate in Chinese. Recently, proficiency tests of Chinese characters are expected to promote the development of Chinese education. But, most Koreans' motives for Chinese study are usually to pass the college entrance exam or to compete for jobs. However, after passing the test, the motive for studying gradually fade away. It is the basic problem faced by Korean Chinese character education. Since the 1950s, various character education methods have been studied in China, the research results were appliedin their textbooks and other materials. Therefore, a well-organized and efficient learning-by-step education system was built up. At present, China's literacy education in the textbooks utilizes a range of methods including revisional centralized and distributed. Unfortunately, there is still one shortcoming worthy of concerns: how to solve the problems due to the simplification of traditional Chinese characters? Is it possible to revive traditional Chinese characters? Before adopting the results of research on China's literacy education and applying them to our character education, we should consider our specific situation carefully. Adopting the research results with cautious review and objective criticism should have a positive impact on Korean Chinese character education.

• Hwankyungkyoyuk
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• v.11 no.1
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• pp.275-290
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• 1998

Nowadays, mankind is suffering from serious pollutions. In proportion to industrial modernization, polltional problems have been increased and arised new one endlessly. Todays, we are cope with a newkind pollution materials threatening the life of mankind with root out. It is Environmental Hormon, that is, Endocrine Disrupting Chemical(EDs). EDs was made by dioxin, PCB, DDT, cadmium, lead, ether and even diethylstillbestrol(DES) that used to contraceptive pill etc. These EDs makes changing from normal human hormon to abnormal one and it kill off or fade out spermatozoa. Then the spermatozoa was infected with EDs makes man imposex, sexual malformations and infertility also. It is the more critical phenomenons that EDs invade into the field of wild-life; birds, invertebrate animals, fishes, mammalia especially. England TV(BBC) journalist Cadury, D. introduced a lot of case studies that many kind of male animals was changed feminization by EDs in her book (The Feminization of Nature;1997). Otherwise, Gibbs, P.E. and Bryan, G. W. reported about dog-whelk snail (a sort of sea shell) was changed gender from male to female by EDs in their study. Briefly speaking, Environmental Hormon (EDs) stem from polluted materials maloperate human and animal informational codes of hormon. It is a significant event to an individual ontogeny and ecological system. To overcome these problem WHO, OECD, UNEP held many work-shops, international seminars and researches but it is not enough yet. On May of 1997, the International Meeting of Environmental Administrators makes a $\ulcorner$Declaration on EDs Problems$\lrcorner$ for solving it fortunately and NHK(japan) reported Super Critical Fluid as a new materials for decrease toxicity of dioxin in recent. Key Words : Environmental Hormon, EDs, imposex feminization, gender, DES, spermatozoa. Super Critical Fluid.