• Mass Spectrometry Letters
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• v.7 no.4
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• pp.102-105
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• 2016

This study explored the feasibility of using a carburization technique to enhance the ion intensity of isotopic analysis of ultra-trace levels of uranium using thermal ionization mass spectrometry (TIMS). Prior to fixing uranium samples on TIMS filaments, graphite powder suspended in nitric acid was deposited on rhenium filaments. We observed an enhancement of $^{238}U^+$ intensity by a factor of two when carburization was used, and were able to roughly optimize the amount of graphite powder necessary for carburization. The positive shift in heating current when evaporating filaments upon carburization implies that uranium was chemically altered by carburization, when compared to normal fixation processes. The good agreement between our method and known standards down to an ultra-trace level shows that the proposed technique can be applied to isotopic uranium analysis down to abundances of ~10 pg.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.4
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• pp.1-12
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• 2008

The study suggests an answer to the question of what determines category diversification of Internet portals in Korea. First, as external factors, competition intensity and market growth are hypothesized to have influence on the degree of category diversification. Second, an internal factor, user loyalty to portals, is hypothesized to influence negatively category diversification. The study performed empirical analysis based on weekly portal-specific panel data of eighteen internet portals in Korea during the period between 2001 and 2004. The result shows that category diversification increases as competition intensity increases, and that category diversification decreases as user loyalty increases. There was no effect of market-level growth rate on category diversification.

• Journal of Biosystems Engineering
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• v.20 no.2
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• pp.117-126
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• 1995

High level of tractor noise may reduce operator's work performance and cause a hearing problem. This study was carried out to investigate the cab noise of a selected agricultural tractor. The noise was measured and analyzed in terms of sound and sound intensity levels. Form the results it was known that a structure-born noise was induced from the feet-rest and rear floor panel of the cab. The air-borne noise caused mainly by the engine was transmitted into the operator's position through the small openings of cab structures in the operator's lower front area.

• Journal of Welding and Joining
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• v.18 no.5
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• pp.33-40
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• 2000

Fatigue crack propagation life of weld toe crack through residual stress field was estimated with Elber's crack concept. Propagation of weld toe crack is heavily influenced by residual stress caused by welding process, so it is essential to take into account the effect of residual stress on the propagation life of weld toe crack. Fatigue crack at transverse and longitudinal weld toe was studied respectively, which represent typical weld joint in ship structure. Numerical and experimental studies are performed for both cases. Residual stress near weldment was estimated through nonlinear thermo-elasto-plastic finite element method, and residual stress intensity factor with Glinka's weight function method. Effective stress intensity factor was calculated with Newman-Forman-de Koning-Henriksen equation which is based on Dugdale strip yield model in estimating crack closure level U at different stress ratio. Calculated crack propagation life coincided well with experimental results.

• KIEAE Journal
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• v.9 no.5
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• pp.63-68
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• 2009

As with the disappearance of a living room window due to the trend in apartment housing construction that prefers a larger, expanded living room, the sound insulation performance of the balcony window is becoming an important factor to determine the level of indoor noise at an apartment unit. Considering that the indoor noise inside an apartment unit is mandated by law at or below 45dB(A), the balcony window is increasingly assuming an even more important role. Sound insulation performance of the window was measured by examining differences in data involving varying angles of incidence of the sound source as obtained from the same balcony window. Also, acoustic intensity measuring was performed at and around the window to determine its sound insulation quality. Results of measuring on the sound source's angles of incidence indicated that the performance showed some differences in lower frequency ranges, though with no significance. Intensity measuring results showed that the sound insulation performance was reduced near the connection part of the window and the window frame.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.662-665
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• 2005

In this study acoustical characteristics of system air conditioner in different ceiling systems was investigated in anechoic and real conditions. Same Types of air conditioners were installed in two different rooms. The results showed that motor's tonal component was emphasized at near fart of air blast blower in the exposed type while fan's harmonic component is emphasized rather in the enclosed type. This confirms tile result of acoustical intensity mapping which showed that Intensity level of 125Hz octave band increased in the exposed type while there was no noticeable difference at the frequency band in the enclosed type.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.108-114
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• 1999

This study was conducted to investigate the optimum environment for leaf lettuce (Lactuca sativa L. var. crispa) in a plant factory to increase mass-production efficiency of quality leaf lettuce. Transpiration rate and $CO_2$ assimilation rate were increased with increasing the photosynthetic photon flux density (PPFD). The highest fresh weight and dry weight were observed at the PPFD of 200 and 300 U moi $m^{-2}$ $s^{-l}$, respectively. The optimum aerial environment for the growth and quality of leaf lettuce in the plant factory was determined to be over 200 $\mu$mol $m^{-2}$ $s^{-1}$ for PPFB. Although the interaction between light intensity and nutrient level was not significant, the lettuce growth was the best under electrical conductivity (EC) of 1.8 mS $cm^{-1}$ / at high light intensity (250 $\mu$mol $m^{-2}$ $s^{-1}$ ) and EC of 2.4 mS cm-1 at low light level (150 $\mu$mol $m^{-2}$ $s^{-1}$ ) respectively.y.

• Journal of Technology Innovation
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• v.18 no.2
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• pp.33-58
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• 2010

This paper explores the patterns of technological innovation in Korean manufacturing sector in accordance with technology intensity which classifies industries into four sectors; high-technology, medium-high-technology, medium-low-technology and low-technology. Empirical study using Korea Innovation Survey(KIS 2008) data shows that the patterns of technological innovation in Korea exhibits the characteristics of science-based firm described by Pavitt across all industry sectors regardless of the level of technology. On the other hand, overseas studies have found the distinct differences between high-and low-technology sectors; the former is shaped by science-based firm and the latter by supplier-dominated firm. It implies that technological innovation activities in Korea do not reflect the level and/or nature of technology and innovation patterns conform to a single standard of high-technology sector. Further studies on causes and impacts of this inclination would be required for effective technology and innovation policy that fits with the level and/or nature of technology in individual industries.

• Journal of the Korean Society of Clothing and Textiles
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• v.7 no.2
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• pp.61-69
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• 1983

This study was undertaken as a useful material not only to understand the clothing behaviors and the personal variables (age, education, occupation, yearly clothing expenses, weight, and persons who influence on one's choice of clothes) of the middle-aged women in Seoul, Korea but to lend itself to other uses concerning attitudes toward clothing. For the measurement of the attitudes toward specified activities related to clothing use, attitude method by Mary F. Pasnak (1968) was reworded and modified for use with the sample for this study. Analysis of the data revealed that the clothing behaviors of 450 women 30 to 59 years of age made a significant difference according to the personal variables. First, women in thirties showed the most positive clothing attitude of the three age groups. The younger age groups were positively related to relief from boredom through clothing, intensity, sureness, and involvement of attitude among eight attitudes related to clothing. Second, the positiveness of relief from boredom through clothing, intensity, sureness, and involvement of attitude increased in proportion to the education level. On the other hand, dressing for self was negatively related to the level of education. Third, a significant relationship was found between the amount of the clothing expenses and dressing for others, tactual pleasure through clothing, intensity, sureness, and involvement of attitude. Among the personal variables of the middle-aged women, age, the educational level, and the clothing expenses have a relationship with the clothing behaviors, while job, weight, and the persons who influence on one's choice of clothes have no relationship. The extensive interpretation on the result of this study will have to be taken with deliberation. For the more practical material researches on the clothing behaviors of the middle-aged women should be continued steadily in every possible way.

• Journal of The Korean Astronomical Society
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• v.45 no.2
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• pp.39-48
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• 2012

We investigate non-LTE effects on the $H_3^+$ level populations to help the analysis of the observed 2 and 3.5 micron $H_3^+$ emissions from the Jovian ionosphere. We begin by constructing a simple three-level model, in order to compute the intensity ratio of the R(3,4) line in the hot band to the Q(1,0) line in the fundamental band, which have been observed in the Jovian auroral regions. We find that non-LTE effects produce only small changes in the intensity ratios for ambient $H_2$ densities less than or equal to $5{\times}10^{11}cm^{-3}$. We then construct two comprehensive models by including all the collisional and radiative transitions between pairs of more than a thousand known $H_3^+$ rovibrational levels with energies less than 10000 $cm^{-1}$. By employing these models, we find that the intensity ratios of the lines in the hot and fundamental bands are affected greatly by non-LTE effects, but the details depend sensitively on the number of collisional and radiative transitions included in the models. Non-LTE effects on the rovibrational population become evident at about the same ambient $H_2$ densities in the comprehensive models as in the three-level model. However, the models show that rotational temperatures derived from the intensities of rotational lines in the ${\nu}_2$ and $2{\nu}_2$ bands may differ significantly from the ambie temperatures in the non-LTE regime. We find that significant non-LTE effects appear near and above the $H_3^+$ peak, and that the kinetic temperatures in the Jovian thermospheric temperatures derived from the observed line ratios in the 2 and 3.5 micron $H_3^+$ emissions are highly model dependent.