• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.304-308
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• 2012

This paper presents a numerical investigation on propagation of hydrocarbon (ethylene-air mixture) detonation in a deformable copper tube. In this study, we deal with interactions of multi-materials, gas and solid. In gas phase, the model consists of the reactive compressible Navier-Stokes equations and one step chemical reaction. Also we use Inviscid Euler equations in solid. In order to the interface tracking and the determination of boundary values, our model handle level-set and ghost fluid method. Through the numerical simulation results, we identify generations of expansion waves and interferences by the wall deformation. In addition, we predict the minimum copper tube thickness that ensures safety under an incident detonation.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.36 no.5
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• pp.59-70
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• 2020

The purpose of this study is to derive the environmental factors affecting child loss through correlation analysis between child loss and pedestrian density. The status of lost children was identified through the lost child records and interviews in large parks. In addition, the behavior survey was conducted by photographing the entire outdoor of each park, and visitors was marked on the behavioral maps. Also, the pedestrian density was analyzed by GIS as 100㎡ and 1㎡ grid. As a result, child loss was related to the pedestrian density rather than the number of visitors or the area. Especially, 'Dynamic pedestrian density' and 'Ratio of pedestrian in high density to area' was related to child loss. In other words, the more dynamic behaviors such as play and movement appear, and the more the local area of high density, the higher the probability of child loss. In addition, environmental factors that induce such high density include bottlenecks, overlap of circulation due to multi-functionality of space, concentration of rides, and concentration of guardians due to visual obstacles.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.2
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• pp.83-87
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• 1978

Using the Buhler laboratory mill three Korean wheat varieties were tested for milling quality. Comparison was made to USA soft white wheat varieties grown in 1977. This test indicated that the milling rate and milling score of Korean varieties were inferior to the variety Paha but were equal to or better than the variety Nugaines.

• Economic and Environmental Geology
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• v.36 no.3
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• pp.213-223
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• 2003

We estimated the Moho depth of Korean Peninsula from gravity anomalies and digital elevation model. The satellite radar altimetry-derived global free-air gravity model was used to ensure the homogeneity in both data and frequency domains of the original data. Two different methods were implemented to calculate the Moho depth; the wavenumber correlation analysis (Kim et al., 2000a) and the power spectrum analysis. The former method calculates depth-to-the-Moho by correlating topographic gravity effect with free-air gravity anomaly in the wavenumber domain under the assumption that the study area is not isostatically compensated. The latter one, on the other hand, considers the different density layers (i.e., Conrad and Moho), using complete Bouguer gravity anomaly in the Frequency domain of the Fourier transform. The correlation coefficient of the two Moho model is 0.53, and methodology and numerical error are mainly responsible for any mismatch between the two models. In order to integrate the two independentely-estimated models, we applied least-squares adjustment using the differenced depth. The resultant model has mean and standard deviation Moho depths of 32.0 km and 2.5 km with (min, max) depths of (20.3, 36.6) kms. Although this result does not include any topographic gravity effect, however, the validity of isostasy and the role of local stress field in the study area should be further studied.

• The Journal of Engineering Geology
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• v.20 no.3
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• pp.297-310
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• 2010

This study represents basic research into the utilization of mixed ash (fly ash and bottom ash) from the ash pond of the Taean Thermal Power Plant as a construction material. We conducted physical and mechanical experiments on the mixed ash and examined its engineering characteristics in terms of its use as a material for road landfill and structure backfill. We evaluated the physical and chemical characteristics of the ash by performing tests to determine specific gravity, maximum and minimum density, liquid limit and plastic limit, grain size distribution, composition (by X-ray diffraction), and loss on ignition. We also evaluated the mechanical characteristics by testing for permeability, compaction, CBR, and tri-axial compression. The experiments on the mixed ash yielded a specific gravity of 2.18-2.20, dry density of $9.38-13.32\;kN/m^3$, modified CBR of 16.5%-21%, permeability coefficient of 1.32 to $1.89-10^{-4}cm/sec$, and drained friction angle of $36.43^{\circ}-41.39^{\circ}$. The physical and mechanical properties of the mixed ash do not meet the quality standards stipulated for road landfill and structure backfill materials. Mixed ash with a high content of fly ash failed to meet some of the quality standards. Therefore, in order to utilize the mixed ash as a material for road landfill and structure backfill, it is necessary to improve its properties by mixing with bottom ash.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.795-810
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• 2019

In this paper, The study was conducted on the method to roughly determine the area and length of the multi-utility tunnel before the planning and design phase of the multi-utility tunnel construction. For this purpose, four feasibility indexes were used: traffic density, population density, disaster prevention index (number of workers), and urbanization rate, which reflect the regional characteristics. The installation criteria were set in consideration of the average value and minimum value of the feasibility indexes for the tunnel type among areas that can be installed in the multi-utility tunnel of Seoul. The analysis area included 200 areas based on 14 zones. The results of the analysis based on the minimum value of feasibility indexes indicated that the tunnel type of multi-utility tunnel is suitable for 39 areas with high traffic volume and population. On the other hand, the 'gun' area, etc., has a wider population than the 'si' and 'gu', suggesting that it is not suitable to install multi-utility tunnel. In addition, it can be seen that the larger the index value centered on the minimum value of each index, the smaller the tunnel type of multi-utility tunnel installation area.

• Journal of Korean Society of Forest Science
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• v.78 no.3
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• pp.314-322
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• 1989

For the improvement of nursery condition and the study of eco-physiological characteristics of Pinus koraiensis(2-2) seedlings, the primary productivity was investigated and the growth characteristics and their correlationship were analyzed from May to September in 1987. Seedlings used in this study were grown at the nursery of Experimental Forestry of Kyung Hee Univ. The installation of experimental plots were divided into control plot (100%), 63%, 37% and 19% relative light intensity, and each relative light intensity plots were split into $15{\times}15/m^2$, $12{\times}12/m^2$, $9{\times}9/m^2$ and $6{\times}6/m^2$ plnting density by randomized black design method. To take into account the edge effect of plant population, material were selected from each plot by random sampling at 30 days interval. Each sampled material was divided into leaf and stem drived in a drying oven at the temperature of $85^{\circ}C$ until it had constant weight and weighed. and leaf area was surveyed. Growth analysis for RGR and NAR was done by Blackman method and correlation coefficient were investigated between RGR and NAR by analyzing the dry matter production and growth characteristics of the material, cultivated on the experimental nursery under the condition of different treatment the obtained result were as follows : 1. The increasing rate of dry matter was similar at early stage of growth, but not at late stage. 2. Leaf area growth was the maximum value at 63% relative light intensity and the minimum at 19% RLI 3. The value of RGR was the highest on June under $6{\times}6/m^2$ planting density in 63% relative light intensity, the lowest on September under $12{\times}12/m^2$ of 19% relative light intensity. 4. The change NAR decreased in early stage of growth, while it increased on August and September, The value of RGR on June under $6{\times}6/m^2$ planting density in 100 light intensity was the highest, and on September under $12{\times}12/m^2$ planting density in 19% relative light intensity was the lowest. 5. Regression and correlation between RGR and NAR showed significantly positive.

• Journal of the Korean Geographical Society
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• v.41 no.2 s.113
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• pp.212-226
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• 2006

Surface data generally represent continuous distribution of geographical or social phenomena of a region in urban analysis. Instances include distribution of temperature, population of region, and various distributions related to human activities. When spatial data are given in the form of surface, surface comparison is required as a way of comprehending the surface change or the relationship between two surfaces. As for previous approaches of surface comparison, there are visualization, quantitative methods and qualitative method. All those approaches, however, show the difference between two surfaces in a limited way. Especially, they are not able to distinguish spatial difference between two surfaces. To overcome such problem, this paper proposes a method of comparing two surfaces in terms of their spatial structure. Main concept of the method comes from earth moving problem and the method is named minimum surface transformation, here. When a surface is transformed into another, total surface volume moved in the process of transformation should be the minimum. Both quantitative and spatial differences between two surfaces are evaluted by total surface volume moved and the distribution of moved surface volume of each cell respectively. The method is applied to hypothetical and actual data. From the former, it is understood that the method explains how two surfaces are quantitatively and spatially different. The result of the latter shows that moved total surface volume decreases as time goes by which fits the actual situation that population change rate gets smaller. Concerning the other measure of surface difference, the distribution of $X_{ij}$ describes detailed flow of surface volume than that of simply subtracting surface volume by indicating to what direction the population change occurs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.645-653
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• 1998

Twenty seven species of pufferfishes (family Tetraoaontidae) have been examined to find their generic characters based on vertebrae and pterygiophore characters of specimens collected in 20 localities along the coast of Korea from March, 1991 to March, 1994. It was divided by 3 groups based on vertebrae number as follow : the genera Lagocephalus, Pleurancanthus, Spheoides, Arothron, Chelonoeon and Canthigaster have 17$\~$19 vertebrae, genera Ephippion, Boesemanichthys and Feroxodon have 20 vertebrae, and genus Takifugu have 19$\~$25 vertebrae, The number of vertebrae ranged from 17 to 25 with the maximum of 25 in Takifugu obscurus. The modal number of vertebrae in Lagocephalus is 17 (L. lunaris), 18 (L. inermis), and 19 (L. gloveri, L. wheeleri, L. larigatus), with the lower number more specialized. Paired neural spines appear at number of the 1st$\~$5th vertebrae in Takifugu pardalis, Takifugu obscurus and at number of the 1 st$\~$4 th vertebrae in the other species and genera. All of the species of Lagocephalus and Pleurancanthus have dorsal and ventral pterygiophores processes, and flat-shaped epural, while none of the abdominal vertebrae processes complete haemal arches. The neural and haemal spines of the last few caudal vertebrae aye shorter in Pleurancanthus than in the other genera, associated with the depressed caudal peduncle. The genus Canthigaster is distinguished the first pterygiophores of the dorsal and ventral fins is always much larger than the others genera. Based on the haemal arches and spines of the abdominal vertebrae, genus Canthigaster has different characters from the other genera of the family Tetraodontidae.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.6-11
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• 1999

Dialkylamine (di-)nitrobenzoates as vapor corrosion inhibitor were synthesized with dialkylamines and (di-)nitrobenzoic acids. The compounds were analyzed by elemental analyzer, FT-IR and $^1H$-NMR spectrophotometer. Corrosion inhibition of synthetic compounds and additives [$(NH_4)_2CO_3$, $NaHCO_3$] against ferrous and non-ferrous metal was investigated by potentiostatic method [1% (w/v) corrosion inhibitor in 1M $Na_2SO_4$ aqueous solution] respectively. For corrosion inhibition of ferrous metal, dialkylamine 4-nitrobenzoates were better inhibitor than dialkylamine 3, 5-dinitrobenzoates, the passivating current density ($i_p$) of dialkylamine 4-nitrobenzoate was shown $4.78mA/cm^2$. While, for non-ferrous metal, dialkylamine 3, 5-dinitrobenzoates were better, those of dipropylamine 3, 5-dinitrobenzoate and hexamethyleneimine 3, 5-dinitrobenzoate were shown 36 and $37mA/cm^2$. Additive effect of $(NH_4)_2CO_3$ and $NaHCO_3$ for corrosion inhibition of ferrous metal was excellent but that of non-ferrous metal was not. Optimum ratios of diethylamine 4-nitrobenzoate with $(NH_4)_2CO_3$ and $NaHCO_3$ were 4 : 6 and 5 : 5 (V/V), and passivating current densities ($i_p$) of the mixtures were shown 0.26 and $0.85mA/cm^2$, respectively.