• Communications for Statistical Applications and Methods
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• v.16 no.4
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• pp.627-637
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• 2009

Our economic system highly depends on the international trade market and demands high level of foreign language abilities to the young generation. Scores of various internationally authorized language tests are used to estimate students's language ability before giving their admission to universities or high schools. According to increase of unemployment rate of the young people, universities put their strength on the language abilities of their students, and each university uses some authorized language scores before determining students who win scholarships. This study suggests two types of indices to evaluate students's relative achievement of foreign language abilities between two time points considering their current abilities. One, named one-side relative achievement index, is defined as the ratio of additional score between two time points to the remaining score at the base time point to the full score. The second one, named two-side relative achievement index, is defined as the same manner as the first one if the score is improved, and if not, is defined as the ratio of the amount of losing scores to the current score at the base time point. Two-side achievement index is more useful since it has smaller variation than the former and is easier to interpret. However, both indices are useful to compare the achievements of different tests.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.2
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• pp.287-293
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• 2010

Regarding the physical properties of wheat flour added with lily's root powder, elasticity in farinograms tended to increase as the ratio of added lily's root powder increased. However, viscoelasticity, absorptivity, absorption time, and stability tended to decrease after an initial increase when a certain ratio of lily's root powder was added to the wheat flour. Results from the rapid viscosity analyzer (RVA) indicated that the retention strength, final viscosity, break down, set back value, $P_{max}$ value of the alveogram, and falling number value decreased. As for gaseous release, measured with a rheofermentometer, the total amount of $CO_2$ gas generated and retained tended to decrease. As for the gelatinizing properties in terms of differences in the granularity and the amount of lily's root powder (bulbs) added to wheat flour, the initial gelatinization temperature had no effect regardless of the type or amount of general grinding and minute (ultra-fine, $10\;{\mu}m$) lily's root powder. Meanwhile, the peak viscosity and peak viscosity time exhibited significant differences in 3, 5% general grinding lily's root powder additive groups. On the other hand, there was no significant difference between 3, 5% minute lily's root powder additive groups. This is likely because the activity of the enzyme in wheat flour decreased relatively and differences in the lily's root powder granularity resulted in a variation in water absorptivity. In the preference test, flavor retention of the functional bread increased according to the granularity of lily's root powder and the ratio of added lily's root powder, thus resulting in significant differences in the mouth feel and flavor; the texture and crumb color, however, did not exhibit significant differences.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5277-5281
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• 2014

Published studies have evaluated associations between the MDM2 SNP309T>G polymorphism and bladder cancer susceptibility. However, these generated inconsistent results. The aim of the present investigation was to quantify the strength of association between MDM2 SNP309T>G polymorphism and bladder cancer risk by conducting a meta-analysis. We searched PubMed and Embase for related studies that had been published in English before April 1, 2014 and associations were assessed by summarizing the odds ratios (ORs) with the corresponding 95% confidence intervals (CIs). Five case-control studies with a total of 972 cases and 1,012 controls were finally identified to be eligible for the meta-analysis. Overall, the results indicated that there was no significant association between the MDM2 SNP309T>G polymorphism and bladder cancer risk (for the allele model G vs. T: OR=1.08, 95% CI 0.85-1.36, p=0.54; for the co-dominant model GG vs. TT: OR=1.20, 95% CI 0.74-1.93, p=0.46; for the dominant model GG+GT vs. TT: OR=0.98, 95% CI 0.80-1.20, p=0.83; for the recessive model GG vs. GT+TT: OR=1.20, 95% CI 0.83-1.74, p=0.33). However, on subgroup analysis by ethnicity, significant associations were found in Caucasians in three models (for the allele model G vs. T: OR=1.41, 95% CI 1.10-1.81, p=0.006; for the co-dominant model GG vs. TT: OR=2.16, 95% CI 1.28-3.63, p=0.004; for the recessive model GG vs. GT+TT: OR=2.06, 95% CI 1.31-3.22, p=0.002). In summary, the present meta-analysis provides evidence that the genotype for the MDM2 SNP309T>G polymorphism may be associated with genetic susceptibility to bladder cancer among Caucasians.

• Ocean and Polar Research
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• v.37 no.2
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• pp.127-140
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• 2015

A continuous series of 60 snow samples was collected at a 2.5-cm interval from a 1.5-m snow pit at a site on the Styx Glacier Plateau in Victoria Land, Antarctica, during the 2011/2012 austral summer season. Various chemical components (${\delta}D$, ${\delta}^{18}O$, $Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, $SO_4{^2-}$, $NO_3{^-}$, $F^-$, $CH_3SO_3{^-}$, $CH_3CO_2{^-}$ and $HCO_2{^-}$) were determined to understand the highly resolved seasonal variations of these species in the coastal atmosphere near the Antarctic Jang Bogo station. Based on vertical profiles of ${\delta}^{18}O$, $NO_3{^-}$and MSA, which showed prominent seasonal changes in concentrations, the snow samples were dated to cover the time period from 2009 austral winter to 2012 austral summer with a mean accumulation rate of $226kgH_2Om^{-2}yr^{-1}$. Our snow profiles show pronounced seasonal variations for all the measured chemical species with a different pattern between different species. The distinctive feature of the occurrence patterns of the seasonal variations is clearly linked to changes in the relative strength of contributions from various natural sources (sea salt spray, volcanoes, crust-derived dust, and marine biogenic activities) during different short-term periods. The results allow us to understand the transport pathways and input mechanisms for each species and provide valuable information that will be useful for investigating long-term (decades to century scale periods) climate and environmental changes that can be deduced from an ice core to be retrieved from the Styx Glacier Plateau in the near future.

• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.60-65
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• 2015

In the present study, compact $0^{th}$ order resonant antenna for 2.4 GHz ISM frequency band is newly proposed. In case of wireless communication systems such as wi-fi, bluetooth and Zigbee, antennas with omni-directional radiation pattern are necessary because of the demands for uniformly received electric field strength without variation for direction. It is well-known that $0^{th}$ order resonant antennas are not only advantageous for miniaturization but also have advantage of maintaining omni-directional radiation pattern. The proposed antenna is composed of two-element array in which the size of unit element should be smaller than ${\lambda}/4$ correspondent to the resonant length of typical monopole antennas The proposed antenna which is placed at middle and upper side of PCB with $50{\times}50mm^2$ size is designed and fabricated within limited space of $8{\times}5mm^2$. The measured impedance bandwidth ($S_{11}{\leq}-10dB$) is about 100 MHz (2.4~2.5 GHz) which corresponds to quite wide bandwidth in comparison with the antenna size, and also the measured peak gain over the passband is more than 3 dBi which is thought to be slightly wider than the other $0^{th}$ order resonant antenna.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.81-88
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• 2009

This study has shown the tendency to enhance Sand Flux, a device of separating screening the foreign matter, for the recycling of construction waste possible to improve the quality of wet type production system meaningfully as part of research. As a result of experiment on the basic material properties, this study had a tendency to improve the quality and performance significantly in case of absolute surface dried density, 0.08mm sieve throughput, volume of clay lumps, and content of organic foreign matter. In addition, as a result of examining the quality characteristics of mortar, this study has shown the tendency that the flow and compressive strength more increased than the mortar using RS-II by utilizing RS-VI recycled sand produced finally through the device Sand Flux. As for the shrinkage properties, this study has shown the character the generation rate of crack of mortar using RS-IV recycled sand produced finally through the device Sand Flux.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.4
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• pp.60-74
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• 2007

For quantitative analysis of spatio-temporal distribution pattern on marine environment, spatial autocorrelation statistics on the both global and local aspects was applied to the observed data obtained from Gwangyang Bay in South Sea of Korea. Global indexes such as Moran's I and General G were used for understanding environmental distribution pattern in the whole study area. LISAs (local indicators of spatial association) such as Moran's I ($I_i$) and $G_i{^*}$ were considered to find similarity between a target feature and its neighborhood features and to detect hot spot and/or cold spot. Additionally, the significance test on clustered patterns by Z-scores was carried out. Statistical results showed variations of spatial patterns quantitatively in the whole year. Then all of general water quality, nutrients, chlorophyll-a and phytoplankton had strong clustered pattern in summer. When global indexes showed strong clustered pattern, the front region with a negative $I_i$ which means a strong spatial variation was observed. Also, when global indexes showed random pattern, hot spot and/or cold spot were/was found in the small local region with a local index $G_i{^*}$. Therefore, global indexes were useful for observing the strength and time series variations of clustered patterns in the whole study area, and local indexes were useful for tracing the location of hot spot and/or cold spot. Quantification of both spatial distribution pattern and clustering characteristics may play an important role to understand marine environment in depth and to find the reasons for spatial pattern.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.261-269
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• 2015

In this study, we applied a membrane distillation process to investigate a feasibility of treating a wastewater with high concentration of organic matters including nitrogen and phosphorus. The laboratory scale experiment was performed by using a hydrophobic PVDF membrane with the pore size of $0.22{\mu}m$ and porosity of 75%. The installation was direct contact type where the temperature difference between a feed and permeate side was controlled to have a range from 20 to $60^{\circ}C$. We observed a flux variation and a concentration changes of COD, $PO{_4}^{3-}$-P, $NH_4{^+}$-N and conductivity of feed side as well as permeate side with various temperature differences (20 to $60^{\circ}C$), cross flow velocities (0.09 to 0.27 m/s) through the module, and pH (6.6 to 12.0) of the feed that has the initial concentration of COD about 1,000 mg/L, total nitrogen 390 mg/L, total phosphorus 10 mg/L, conductivity of $7,000{\mu}s/cm$. The results showed that the average flux was ranged from 4 to $40L/m^2/hr$ which was almost similar with the flux of NaCl and deionized water used as a feed solution. The lowest flux was obtained at the operating condition with the temperature difference of $20^{\circ}C$ and cross flow velocity of 0.09 m/s while the highest one was measured with $60^{\circ}C$ and 0.27 m/s. Above 99% of COD and $PO{_4}^{3-}$-P in the feed could be rejected regardless of an operating condition. However, the removal rate of ammonium nitrogen was varied from 64 to 99% depending on the pH of feed solution.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.953-959
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• 1995

It was investigated that reinforced species, billet condition and extrusion variation in Al 6061 composite material effected on extrusion process of particulate reinforced composite material. The strength of composite material with reinforcement species revealed SiC$\sub$w/> A1$_2$O$\sub$3f/ > A1$_2$O$\sub$3f/ > A1$_2$O$\sub$3f/ orderly. K$\sub$w/ increased as volute fraction increased in all composite material. The composite materials reinforced by A1$_2$ $O_3$required the larger pressure in hot extrusion process than those by SiC$\sub$p/ at all condition. Extrusion process tended to decrease as the semi-angle of extrusion dies increased because larger contact area caused larger shear friction. Extrusion temperature went up about 50$^{\circ}C$ in low elevated deformation temperature. In extrusion temperature above 500$^{\circ}C$, severe tearing occurred on extrusion surface. More reinforcement in volume fraction, more hot tearing.

• Korean Journal of Materials Research
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• v.10 no.6
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• pp.403-408
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• 2000

The Al-Cr-Zr composite metal powders were prepared by mechanical alloying and consolidated by vacuum hot pressing. The microstructural characteristics and the thermal stability of the MA Al-Cr-Zr alloys were evaluated by means of microhardness measurement, XRD and TEM in order to develop high temperature, high strength aluminum alloys. The mechanical alloying was conducted in attritor with 300rpm for 20 hours. The density of the vacuum hot pressed Al-Cr-Zr alloy reached at 97% of theoretical one. After exposing at $300^{\circ}C$ for 100 hours, there is almost no variation in hardness change of the MA alloys. Even after exposing at $ 500^{\circ}C$ for 100 hours, the hardness of the alloy was decreased within 6% of the initial value. The fine stable $Al_3Zr\;and\; Al_{13}Cr_2$ intermetallics were formed at the stage of consolidation and heat treatment in aluminum matrix. The good thermal stability of the MA Al-Cr-Zr alloy can ab attributed to the role of the dispersoids, inhibiting grain growth of nanocrystalline, and the final grain size after heat treatment was less than 150nm.