• Korean Journal of Metals and Materials
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• v.46 no.10
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• pp.609-616
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• 2008

Conventional bake-hardenable(BH) steels should be annealed at higher temperatures because of the addition of Ti or/and Nb which forms carbides and raises recrystallization start temperature. In this study, the development of new BH steels without Ti or Nb addition has been reviewed. The new BH steels have nearly same mechanical properties as the conventional BH steels even though it is annealed at lower temperature. The steels also show smaller deviation of the mechanical properties than that of the conventional BH steels because of the conarol of solute carbon content during steel making processes. The deviation of mechanical properties in conventional BH steels is directly dependent on the deviation of solute carbon which is greatly influenced by the amount of the carbide formers in conventional BH steels. Less alloy addition in the newly developed BH steels gives economical benefits. By taking the advantage of sulfur and/or nitrogen which scarenge in Interstitial-Free or conventional BH steels, fine manganese sulfides or nano size copper sulfides were designed to precipitate, and result in refined ferrite grains. Aluminum nitrides used as a precipitation hardening element in the developed steels were also and resull in fine and well dispersed. As a result, the developed steels with less production cost and reduced deviation of mechanical properties are under commercial production. Note that the developed BH steels are registered as a brand name of MAFE(R) and/or MAF-E(R).

• Journal of Environmental Health Sciences
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• v.38 no.5
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• pp.424-430
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• 2012

Objective: The purpose of this study was to present the standard deviation of the elemental normalization of concentration of selected heavy metals in the surface sediment of Lake Paldang. Methods: Grain size dependency of selected heavy metal concentrations in the surface sediments of Lake Paldang was analyzed by the extrapolation method. The heavy metal concentrations were the sum of all fractions. Results: Cd and Cu showed an increase of the coefficient of determination($r^2$) in the fractional content of particle size, from <256 ${\mu}m$ to <20 ${\mu}m$, and a decrease from <20 ${\mu}m$ to <1 ${\mu}m$. The normalized concentration of Cd and Cu by extrapolation at 50% <20 ${\mu}m$ were 0.8 mg/kg, 37.0 mg/kg, 57.6 mg/kg and 201.7 mg/kg respectively. Conclusions: The normalized concentrations in the sediment of Lake Paldang are 1.5-2.0 times higher than mean average concentration. We concluded that in interpretation of heavy metal concentration in the sediment of Lake Paldang, normalization of grain size dependency should be considered.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.916-922
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• 1997

This paper attempted to estimate mesh selectivity of gill nets for neon flying squid in the north Pacific Ocean. The 11 linear regressions, (P<0.05) were obtained using the data on catch ratios derived from mesh size combinations between two slightly different mesh sizes of 12 kinds of research gillnet (namely 33, 37, 42, 48, 55, 63, 72. 76, 86, 96, 105 and 115 mm in stretched mesh size). There was an increase in the optimum length with the increase in mesh size but standard deviation showed somewhat increase with the increase in the mesh size. The selectivity curves were well fitted to the length frequency distributions obtained from samples for the mesh sizes from 48 mm through 86 mm. For the mesh sizes of 33, 37 and 42 mm the DML (Dorsal Mantle Length) compositions were distributed towards the right hand-limb of the curves. The DML distributions from the 96 mm and larger meshes showed a trend towards the left hand-limb of the curves. The selectivity curves for different mesh sizes indicate that large mesh sizes catch a greater size range of squid, and the gill net fishery in the north Pacific Ocean captures effectively neon flying squid within the range of $9\~43cm$ DML.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2342-2352
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• 1995

Deposition of flame-synthesized silica particles onto a target is utilized in optical fiber preform fabrication processes. The particles are convected and deposited onto the target. Falkner-Skan wedge flow was chosen as the particle laden flow. Typically the particles are polydisperse in size and follow a lognormal size distribution. Brownian diffusion, thermophoresis, and coagulation of the particles were considered and effects of these phenomena on particle deposition were studied. A moment model was developed in order to predict the particle number density and the particle size distribution simultaneously. Particle deposition with various wedge configurations was examined for conditions selected for a typical VAD process. When coagulation was considered, mean particle size and its standard deviation increased and particle number density decreased, compared to the case without coagulation. These results proved the fact that coagulation effect expands particle size distribution. The results were discussed with characteristics of thermal and diffusion boundary layers. As the boundary layers grow in thickness, overall temperature and concentration gradients decrease, resulting in decrease of deposition rate and increase of particle residence time in the flow and thus coagulation effect.

• Journal of the Ergonomics Society of Korea
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• v.16 no.2
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• pp.61-71
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• 1997

In industrial designing of ready-to-wear shoes, one important factor to consider is that the population has diverse fooot shapes as well as foot length. The general shape of a foot could be represented by "foot ratio", i.e. the ratio of width to length. In this study, we measured several dey aspects of young Korean men's foot, and compared the results with their shoe sizes and general foot shapes. To this end, 172 male subjects were categorized according to their shoe size (small, medium, large) or foot ratio (wide, narrow, intermediate). The statistics of this survey indicated that the people with narrow foot shap have significantly greater foot length compared with the one having wide foot shape. Conversely, subjects having wide foot shape manifested significantly greater foot and ankle girth as well as significantly greater foot breadth. However, different foot shape groups showed no significant differences in heel width, heel ankle girth, instep height, and malleolus height. On the other hand, subjects wearing larger shoe size showed significantly larger foot measurements except instep and ankle heights, whereas subjects with shoe sizes 260 and below measured significantly more narrow heel and lateral metatarsal breadths. The deviation between foot length and dress shoe size(length) was greater in groups with wide foot shape and in groups wearing large shoe sizes. The results of this survey indicated that the subjects with wide foot shape apparently choose a size or two larger shoes for them as a compromise for a better breadth fit.eadth fit.

• Journal of the Korean Society of Safety
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• v.39 no.1
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• pp.96-103
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• 2024

The demand for mass calculation of offsite consequence analysis to conduct exhaustive single-unit or multi-unit Level 3 PSA is increasing. In order to perform efficient offsite consequence analyses, the Korea Atomic Energy Research Institute is conducting model optimization studies to minimize the analysis time while maintaining the accuracy of the results. A previous study developed a model optimization method using efficient plume segmentation and verified its effectiveness. In this study, we investigated the possibility of optimizing the model through particle size distribution setting by checking the reduction in analysis time and deviation of the results. Our findings indicate that particle size distribution setting affects the results, but its effect on analysis time is insignificant. Therefore, it is advantageous to set the particle size distribution as fine as possible. Furthermore, we evaluated the effect of multithreading and confirmed its efficiency. Future optimization studies should be conducted on various input factors of offsite consequence analysis, such as spatial grid settings.

• Journal of the Korean Society of Costume
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• v.55 no.6 s.96
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• pp.24-37
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• 2005

This study was performed to get basic data for gloves size system and pattern planning suitable Korean hand shape. Data was collected through measuring hand size of man and woman from age 18 to 30 as subjects living in metropolitan area. by analysing the measured data, the difference in man and woman and the gloves size system was established. The results of study are as follows: 1. The Deviation of hand girths and hand lengths was larger than that of hand width in both man group and woman group. In all items. deviation in man was larger than woman. 2. In sex difference, there was difference between mall group and woman group in all items. In age difference, there was difference between mall group and woman group in mainly girth and the difference was bigger in group under 24 years old than in group over 24 years old. 3. The weight showed the highest $correlation(r{\geqq}0.8)$ with girths and high correlation with widths $(r{\geqq}0.7).$ The height showed the highest positive $correlation(r{\geqq}0.8)$ with and elbow length and high correlations with width and girths item. There were high positive correlation between vertical lengths in hand and between horizontal lengths but low correlation between vertical lengths and horizontal lengths. 4. The basic parts for gloves size system, hand lengths and hand girths were divided into 1cm interval. The results shouted that $91.0\%$ of man group were ranged from 18cm to 20cm section and $92.4\%$, of woman group were ranged from 16cm to 18cm section. 5. The interval which has the highest covet· rate was hand length 19cm and hand girth 20cm interval which covered $18.65\%$ of man group. The intervals which showed cover rate more than $5\%$ was total 7 and they covered $73.1\%$ of man group. The interval which has which has the highest cover rate was hand length 17cm and hand girth 17cm interval which covered $21.37\%$ of woman group. The intervals which showed cover rate more than $5\%$ was total 6 and they covered $72.5\%$ of total woman group.

• Asian Journal of Atmospheric Environment
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• v.6 no.4
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• pp.304-313
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• 2012

In this study, the ${\AA}$ngstrom exponent for polydispersed aerosol during dynamic processes was investigated. Log-normal aerosol size distribution was assumed, and a sensitivity analysis of the ${\AA}$ngstrom exponent with regards the coagulation and condensation process was performed. The ${\AA}$ngstrom exponent is expected to decrease because of the particle growth due to coagulation and condensation. However, it is difficult to quantify the degree of change. In order to understand quantitatively the change in the ${\AA}$ngstrom exponent during coagulation and condensation, different real and imaginary parts of the refractive index were considered. The results show that the ${\AA}$ngstrom exponent is sensitive to changes in size distribution and refractive index. The total number concentration decreases and the geometric mean diameter of aerosols increase during coagulation. On the while, the geometric standard deviation approaches monodispersed size distribution during the condensation process, and this change in size distribution affects the ${\AA}$ngstrom exponent. The degree of change in the ${\AA}$ngstrom exponent depends on the refractive index and initial size distribution, and the size parameter changes with the ${\AA}$ngstrom exponent for a given refractive index or chemical composition; this indicates that the size distribution plays an important role in determining the ${\AA}$ngstrom exponent as well as the chemical composition. Subsequently, this study shows how the ${\AA}$ngstrom exponent changes quantitatively during the aerosol dynamics processes for a log-normal aerosol size distribution for different refractive indices; the results showed good agreement with the results for simple analytic size distribution solutions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.3
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• pp.386-392
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• 1996

A numerical method based on genetic algorithms was introduced to characterize the grain-size distribution more effectively. This technique was proved significant particularly for multimodal size distributions, as was verified for samples from Korea Strait continental shelf. Sediment samples collected from the Korea Strait continental shelf revealed that $96\%$ of the grain-size distributions were multimodal. Therefore, the use of grain-size parameters was not the ideal method. As an alternative method, the decomposition of sue curves into elementary normal component curves was used. Means and standard deviations of 593 decomposed normal components were calculated by a numerical method from 268 size curves of Korea Strait sediments. The mean values of decomposed normal components showed peaks at $1\~3\phi\;and\;7\~9\phi$ size classes. The plot of mean and standard deviation values of the coarse fraction normal components on the map showed a characteristic areal distribution. The characteristic distribution was found to derive from underlying Pleistocene sediment on the basis of sea bottom geologic distribution of the area. The method of decomposition into normal components was found to be more effective than the analysis using traditional grain-size parameters in investigation of multimodal size distribution of Korea Strait shelf sediment.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.127-130
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• 1999

Physical properties and microstructure of slag blended cement were investigated to evaluate the influence of sulphates and chlorides. The compressive strength developed as high chloride content dust and gypsum added and accordingly the microstructure modification was showed. The deviation of pore size distribution and hydrates was also observed. From these results we discussed optimum condition of gypsum and high chloride content dust leading to physical properties in this study.