• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.3
• /
• pp.66-74
• /
• 2016

The aim of this research work is to investigate the mix proportion of multi-component cement incorporating ground granulated blast furnace(GGBFS), fly ash(FA) and silica fume(SF) as an addition to cement in ternary and quaternary combinations. The water-binder ratio was 0.45. In this study, 50% and 60% replacement ratios of mineral admixture to OPC was used, while series of combination of 20~40% GGBFS, 5~35% FA and 0~15% SF binder were used for fundamental characteristics tests. This study concern the GGBFS/FA ratio and SF contents of multi-component cement including the compressive strength, water absorptions, ultrasonic pulse velocity(UPV), drying shrinkage and X-ray diffraction(XRD) analysises. The results show that the addition of SF can reduce the water absorption and increase the compressive strength, UPV and drying shrinkage. These developments in the compressive strength, UPV and water absorption can be attributed to the fact that increase in the SF content tends basically to consume the calcium hydroxide crystals released from the hydration process leading to the formation of further CSH(calcium silicate hydrate). The strength, water absorption and UPV increases with an increase in GGBFS/FA ratios for a each SF contents. The relationship between GGBFS/FA ratios and compressive strength, water absorption, UPV is close to linear. It was found that the GGBFS/FA ratio and SF contents is the key factor governing the fundamental properties of multi-component cement.

• Journal of Mushroom
• /
• v.18 no.4
• /
• pp.403-409
• /
• 2020

This study was carried out to investigate the changes in the biological activity and nutritional content of Flammulina velutipes, Grifola frondosa, and Sparassis crispa extracts after roasting treatment. Regarding biological activities, the DPPH radical scavenging activity was the highest in the extracts of air-dried G. frondosa, while the nitrite scavenging activity was significantly higher in the extracts of roasted S. crispa (p<0.05). The total polyphenol contents of F. velutipes and S. crispa were significantly increased by the roasting treatment compared with those in fresh samples (p<0.05). Regarding the amino acid composition of edible mushrooms, the content of sweet-taste amino acids, including serine (Ser) and alanine (Ala), increased in G. frondosa after roasting, whereas bitter amino acids, including decreased in roasted versus samples. Moreover, the contents of essential amino acids such as leucine (Leu), isoleucine (Ile), methionine (Met), valine (Val), and histidine (His) in F. velutipes and S. crispa were increased due to the roasting treatment (versus fresh samples). Thus, it was confirmed that the r method is effective in improving the nutritional content of edible mushrooms.

• Journal of Korea Soil Environment Society
• /
• v.4 no.3
• /
• pp.95-104
• /
• 1999

Comparative biodegradation studies of liquid and solid alkanes and of two different solid alkanes were conducted by an isolated Acinetobacter sp., which degraded crude oil alkanes simultaneously. for the determination of degradation mechanism of hydrophobic crude oil constituents. Also a model oil experimental system composed of a solid alkane. heneicosane, as a substrate and a non-degradable non-aqueous phase liquid. pristane, as an oil matrix was established and studied. It was proposed that the Acinefobacter sp. utilized hydrophobic substrates directly on the surface of them with no difference in the degradation rates between the liquid and solid alkanes. On the basis of the results from the heneicosane/pristane system which imitates crude oil matrix containing solid constituents. the crude oil matrix was considered to reduce the bioavailability of contained substrates by reducing the specific surface area of substrates to contact with microorganisms.

• Membrane Journal
• /
• v.8 no.3
• /
• pp.138-147
• /
• 1998

This paper compared selectivities and mass transfer rates of valuable aromatics (naphthalene group: carbon number 10-12) in the light cycle oil obtained from solvent extraction (SE) with those obtained from liquid membrane permeation (LMP). An aqueous solution of dimethylsulfoxide (DMSO) and an aqueous solution of saporrin and DMSO were used as extraction solvent of SE and the membrane phase of LMP, respectivdy. Selectivities of naphthalene group in reference to n-nonane obtained from SE runs were rapidly increased with decreasing the operating temperature, whereas, those obtained from LMP runs were remained constant throughout the operating temperature. At room temperature, selectivities of naphthalene group obtained from SE were greater than those from SE. Furthermore, mass transfer rates of naphthalene group by SE and LMP were measured in a baffled batch stirred vessel. It was found that the extraction rates of SE were faster by about 280 times than the permeation rates of LMP.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.6 no.6
• /
• pp.536-541
• /
• 2005

Large displacement and rigidity about rubber component are expected by nonlinear and large deformation analysis in this study. Rubber is also used by the model of Mooney-Rivlin and the self contact between rubbers is established. There is the friction between rigid body and rubber, wall and floor. The nonlinear simulation analysis used in this study is expected to be widely applied in design, analysis and development of several rubber components which are used in automotive, railroad, and mechanical elements etc. By utilizing this method, time and cost can also be saved in developing new rubber product. The analysis of rubber components requires special material modeling and non-linear finite element analysis tools that are quite different from those used for metallic parts. The objective of this study is to analyze the rubber component with large deformation and non-linear properties.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.9
• /
• pp.2994-3001
• /
• 2000

In this paper. a method for color image segmentation using region merging is proposed. A inhomogeneity which exists in image is reduced by smoothing with non-linear filtering. saturation enhancement and intensity averaging in previous step of image segmentation. and a similar regions are segmented by non-uniform quantization using zero-crossing information of color histogram. A edge strength of initial region is measured using high frequency energy of wavelet transform. A candidate region which is merged in next step is selected by doing this process. A similarity measure for region merging is processed using Euclidean distance of R. G. B color channels. A Proposed method can reduce an over-segmentation results by irregular light sources et. al, and we illustrated that the proposed method is reasonable by simulation.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.7 no.3
• /
• pp.209-218
• /
• 1995

Nonlinear interaction between directional wave components is theoretically analyzed in deep water. The perturbed solution for an irregular wave is derived accurate up to the third order of the wave steepness and it is shown that the wave characteristics are modulated due to the nonlinear interaction. The convergence rate of the perturbed solution depends on not only wave steepness but also wavelength ratio between wave components. The long-wave component of the perturbed solution converges rapidly. while the short-wave solution converges slowly or diverges. The short wave properties in a broad-band wave spectrum cannot accurately be obtained by the conventional wave-mode method because it fails to properly describe the modulation of short-wave frequency caused by the nonlinear interaction with much longer wave.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.2
• /
• pp.9-18
• /
• 2004

OFDM is a special case of multicarrier transmission, where a high-rate datastream is transmitted over a number of lower rate subcarriers. In this paper, the structure of ORM system is studied, and causes of inter carrier interference (ICI) are analyzed. Based on analysis, this paper shows a technique to prevent a distortion due to nonlinearity of high power amplifier. The proposed scheme is a predistorter(PD) for high power amplifier linearization in OFDM system. This is verified by comparing BER characteristics of OFDM system, between used PD and not used PD, and superiority is shown by comparing BER characteristics of OFDM system, between used the proposed PD and used some other PDs.

• Culinary science and hospitality research
• /
• v.8 no.1
• /
• pp.55-69
• /
• 2002

Sedum Sarmentosum Bunge has been used as medical material and food in Korea. To upgrade it's value as a materials of beverage, I research and analysed nutritive substance and taste. Inorganic components content was included in the order of Ca, mg, P, K, Na, in line, and there were little Fe, Cu, Zn. It appeared much Ascorbic acid contents in May sample for March sample, but it was included less than other Green Vegetables. Chlorophyll contents decreased about 37.8% and 37.6% to the first each contents after seven days resulting measuring May sample and March sample in room temperature. There was much difference in appearance. Sedum Sarmentosum Bunge included a little polyphenol contents. Polyphenol contents decreased a little in five days in May sample and March sample. I measured phenol compounds of garlic acid, vani11ic acid, caffeic acid, p-coumaric acid, ferulic acid, most of consisted in corrected forms. Fragrance components were confirmed 9 kinds in March sample, 11 kind in May sample the common components in May sample and March sample were 7-octen-4-o1.

• Journal of Environmental Science International
• /
• v.12 no.6
• /
• pp.665-676
• /
• 2003

To investigate the chemical characteristics of PM$\_$2.5/ in Seoul, Korea, atmospheric particulate matters were collected using a PM$\_$10/ dichotomous sampler including PM$\_$10/ and PM$\_$2.5/ inlet during the period of October 2000 to September 2001. The Inductively Coupled Plasma-Mass Spectromety (ICP-MS), ion Chromatography (IC) methods were used to determine the concentration of both metal and ionic species. A statistical analysis was performed for the heavy metals data set using a principal component analysis (PCA) to derived important factors inherent in the interactions among the variables. The mean concentrations of ambient PM$\_$2.5/ and PM/sub10/ were 24.47 and 45.27 $\mu\textrm{g}$/㎥, respectively. PM$\_$2.5/ masses also showed temporal variations both yearly and seasonally. The ratios of PM$\_$2.5/PM$\_$10/ was 0.54, which similar to the value of 0.60 in North America. Soil-related chemical components (such as Al, Ca, Fe, Si, and Mn) were abundant in PM$\_$10/, while anthropogenic components (such as As, Cd, Cr, V, Zn and Pb) were abundant in PM2s. Total water soluble ions constituted 30∼50 % of PM$\_$2.5/ mass, and sulfate, nitrate and ammonium were main components in water soluble ions. Reactive farms of NH$_4$$\^$+/were considered as NH$_4$NO$_3$ and (NH$_4$)$_2$SO$_4$ during the sampling periods. In the results of PCA for PM$\_$2.5/, we identified three principal components. Major contribution to PM$\_$2.5/ seemed to be soil, oil combustion, unidentified source. Further study, the detailed interpretation of these data will need efforts in order to identify emission sources.