• International Journal of High-Rise Buildings
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• 제7권4호
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• pp.375-387
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• 2018

This paper presents a review on progressive collapse mechanism of steel framed buildings exposed to fire. The influence of load ratios, strength of structural members (beam, column, slab, connection), fire scenarios, bracing systems, fire protections on the collapse mode and collapse time of structures is comprehensively reviewed. It is found that the key influencing factors include load ratio, fire scenario, bracing layout and fire protection. The application of strong beams, high load ratios, multi-compartment fires will lead to global downward collapse which is undesirable. The catenary action in beams and tensile membrane action in slabs contribute to the enhancement of structural collapse resistance, leading to a ductile collapse mechanism. It is recommended to increase the reinforcement ratio in the sagging and hogging region of slabs to not only enhance the tensile membrane action in the slab, but to prevent the failure of beam-to-column connections. It is also found that a frame may collapse in the cooling phase of compartment fires or under travelling fires. This is because that the steel members may experience maximum temperatures and maximum displacements under these two fire scenarios. An edge bay fire is more prone to induce the collapse of structures than a central bay fire. The progressive collapse of buildings can be effectively prevented by using bracing systems and fire protections. A combination of horizontal and vertical bracing systems as well as increasing the strength and stiffness of bracing members is recommended to enhance the collapse resistance. A protected frame dose not collapse immediately after the local failure but experiences a relatively long withstanding period of at least 60 mins. It is suggested to use three-dimensional models for accurate predictions of whether, when and how a structure collapses under various fire scenarios.

• Advances in nano research
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• 제10권1호
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• pp.77-90
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• 2021

In the present study, novel chitosan coated magnetic magnetite (Fe3O4) nanoparticles were successfully biosynthesized from mushroom, Agaricus campestris, extract. The obtained bio-nanocomposite material was used to investigate ultra-fast and highly efficient for removal of Ni2+ ions in a fixed-bed column. Chitosan was treated as polyelectrolyte complex with Fe3O4 nanoparticles and a Fungal Bio-Nanocomposite Material (FBNM) was derived. The FBNM was characterized by using X-Ray Diffractometer (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Fourier Transform Infrared spectra (FTIR) and Thermogravimetric Analysis (TGA) techniques and under varied experimental conditions. The influence of some important operating conditions including pH, flow rate and initial Ni2+ concentration on the uptake of Ni2+ solution was also optimized using a synthetic water sample. A Central Composite Design (CCD) combined with Response Surface Modeling (RSM) was carried out to maximize Ni2+ removal using FBNM for adsorption process. A regression model was derived using CCD to predict the responses and analysis of variance (ANOVA) and lack of fit test was used to check model adequacy. It was observed that the quadratic model, which was controlled and proposed, was originated from experimental design data. The FBNM maximum adsorption capacity was determined as 59.8 mg g-1. Finally, developed method was applied to soft drinks to determine Ni2+ levels. Reusability of FBNM was tested, and the adsorption and desorption capacities were not affected after eight cycles. The paper suggests that the FBNM is a promising recyclable nanoadsorbent for the removal of Ni2+ from various soft drinks.

• Journal of the Korean Society of Food Science and Nutrition
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• 제32권5호
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• pp.752-757
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• 2003

This study was carried out in order to develop the method for isolation of red ginseng acidic polysaccharide (RGAP) haying immunomodulating antitumor activity from red ginseng by-product. The red ginseng by-product was obtained from red ginseng residues produced in processing of red ginseng ethanol extract. The yield of RGAP isolated by ultrafiltration was 20.9%. The active substance (GFP) was purified by DEAE-sepharose column chromatography RGAP induced nitric oxide (NO) exhibited tumoricidal activities against P8l5 (mastocytoma) tumor cells. Acid-hydrolyzed RGAP fragments were shown four to five spots. These sopts showed the same R$_{f}$ values with sugars designated as rhamnose, glucose, glactose and glucuronic acid. Some physico-chemical properties of RGAP were investigated. pH and dry reduction content at 105$^{\circ}C$ were 4.74 and 4.72%, respectively. Crude protein, ash and Pb contents were 3.30%, 4.74% and 2.30 ppm. These results suggest that we will be able to produce RGAP from red ginseng by-product by ultrafiltration in a large scale.e.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.774-780
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• 1999

The study of bond behavior between concrete and rebar has been performed for a long time. On this study, we tried to analysed variation of bond behaviors quantitatively with varying the strength of concrete. Bond stress which observed below the neutral surface of beam and at connecting part of beam and column is affected by various bond parameters. Resistance of deformed bars which embedded in concrete to the pullout force is divided 1) chemical adhesive force 2) frictional force 3) mechanical resistance of ribs to the concrete and these horizontal components of resistance is being bond strength. We selected the most common and typical variable which is concrete strength among various variables. So we used two kinds of concrete strength like as 25MPa(NSC) and 65MPa(HSC). Tension Test was performed to verify how bond behavior varied with two kinds of concrete strength. Concentration of bond stress was observed at load-end commonly in Tension Test of the initial load stage. At this stage stress distribution was almost coincident at each strength. As tension load added, this stress distribution had difference gradually and movement of pick point of bond stress to free-end and central section was observed. This tendency was observed at first and moving speed was more fast in NSC. At the preceeding result the reason of this phenomenon is considered to discretion of chemical adhesion and local failure of concrete around rebar in load-end direction. Especially, when concrete strength was increased 2.6 times in tension test, ultimate bond strength was increased 1.45 times. In most recent used building codes, bond strength is proportioned to sqare root of concrete compressive strength but comparison of normalized ultimate bond strength was considered that the higher concrete strength is, the lower safety factor of bond strength is in each strength if we use existing building codes. In Tension Test, in case of initial tensile force state, steel tensile stress of central cross section is not different greatly at each strength but tensile force increasing, that of central cross section in NSC was increased remarkably. Namely, tensile force which was shared in concrete in HSC was far greater than that of concrete in NSC at central section.

• The Korean Journal of Mycology
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• 제29권1호
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• pp.1-8
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• 2001

To examine the structural properties of the proteoglycan (GMPG, Ganoderma lucidum mycelial proteoglycan) obtained from mycelia in Ganoderma lucidum IY009, we obtained the low and high molecular proteoglycan by ultrafiltration and sepharose CL-4B column chromatography. The physicochemical properties of these fractions were as follows. When the proteoglycan separated by ultrafiltration and sepharose CL-4B column chromatography, its was not fractionated completely. The molecular weight of high molecular proteoglycan by the gel column chromatography (CH) was 250 kD and 2,000 kD, and low molecular proteoglycan was 12kD. The total carbohydrate was consisted of 75.7% (UH) and 96.7% (CH), and the low fraction was 72.7% (UL) and 87.1% (CL), respectively. The sugar of high and low molecular proteoglycan composed of glucose, mannose, fructose, galactose, xylose, ribose and arabinose. Glucose contents of all fraction were ranged from $46.9%{\sim}82.4%$ of the total sugar and the ratio of ${\alpha}$\;and\;{\beta}-glucose$ was $0.84{\sim}1.14$, and its indicated the proteoglycan to be ${\beta}-glucan$. Amino acids pattern showed that the fractions contained a large amount of aspartie acid, glutamic acid, alanine and leucine. These fractions showed the characteristics of IR absorption for ${\beta}-glucan$ at $890\;cm^{-1}\;and\;^{13}C-NMR$ spectroscopy showed the presence of the ${\beta}-1,3-glucan$ and a ${\beta}-1,6-glucan$.

• Journal of the korean society of oceanography
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• 제38권1호
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• pp.1-10
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• 2003

A time-series sediment trap was deployed at a depth of 1034 m in the eastern Bransfield Strait from December 25, 1998 to December 24, 1999. Particle fluxes showed large seasonal variation; about 99% of the annual total mass flux (49 g m/sup -2/) was collected during the austral summer and fall (January-March). Settling particles consisted primarily of biogenic silica, organic carbon, calcium carbonate, and lithogenic material. Biogenic silica and lithogenic material predominated settling particles, comprising 36% and 30% of the total mass flux, respectively, followed by organic carbon, 11% and calcium carbonate, merely 0.6%. The annual organic carbon flux was 5.4 g C m/sup -2/ at 1000 m in the eastern Bransfield Strait, which is greater than the central Strait flux. The relatively lower flux of organic carbon in the central Bransfield Strait may be caused by a stronger surface current in this region. Organic carbon flux estimates in the eastern Bransfield Strait are the highest in the Southern Ocean, perhaps because of the fast sinking of fecal pellets, which leads to less decomposition of organic material in the water column. Approximately 5.8% of the organic carbon produced on the surface in the eastern Bransfield Strait is exported down to 1000 m; this percentage exceeds the maximum EF/sub 1000/ values observed in the Atlantic and Southern Oceans. The eastern Bransfield Strait appears to be the most important site of organic carbon export to the deep sea in the Southern Ocean.

• Steel and Composite Structures
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• 제8권6호
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• pp.491-510
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• 2008

This paper presents a plan and guidelines that were drawn for Korean based research carried out on the fire-resistance of CFT columns. This research was carried out by reviewing the Korean regulations related to the fire-resistance of CFT columns and examining studies which had been made in Korea as well as overseas. The first phase of the study plan was to compare the fire-resistance of square CFT columns without fire protection (obtained through fire-resistance tests and numerical analyses) with estimated values (obtained through fire-resistance design formulas proposed in Korea and overseas). This comparison provided conclusions as outlined below. Fire-resistance tests conducted in this study proved that, when the actual design load is taken into consideration, square CFT columns without fire protection are able to resist a fire for more than one hour. A comparison was made of test and analysis results with the fire-resistance time based on the AIJ code, the AISC design formula and the estimation formula suggested for Korea. The results of this comparison showed that the test and analysis results for specimens SAH1, SAH2-1, SAH2-2 and SAH3 were almost identical with the AIJ code, the AISC design formula and estimation formula. For specimens SAH4 and SAH5, the estimation formula was more conservative than the AIJ code and the AISC design formula. It was necessary to identify the factors that have an influence on the fire-resistance of CFT columns without fire protection and to draw fire-resistance design formulas for these columns. To achieve this, it is proposed that numerical analyses and tests be conducted in order to evaluate the fire-resistance of circular CFT columns, the influence of eccentricity existing as an additional factor and the influence of the slenderness ratio of the columns. It is also suggested that the overall behavior of CFT structures without fire protection within a fire be evaluated through analysis simulation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권1호
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• pp.1-5
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• 2002

A fusion protein, consisting of a human epidermal growth factor (hEGF) as the recognition domain and human angiogenin as the toxin domain, can be used as a targeted therapeutic against breast cancer cells among others. The fusion protein was expressed as inclusion body in recombinant E. coli, and when the conventional, solution-phase refolding process was used the refolding yield was very low due to severe aggregation. It was probably because of the opposite electric charge at a neutral pH resulting from the vastly different pI values of each domain. The solid-phase refolding process that exploited the ionic interactions between ionic exchanger surface and the fusion protein was tried, but the adsorption yield was also very low, below $ 30\%$, regardless of the resins and pH conditions used. Therefore, to provide a higher ionic affinity toward the solid matrix, six lysine residues were tagged to the N-terminus of the hEGF domain. When heparin-Sepharose was used as the matrix, the adsorption capacity increased 2.5-3 times to about $88\%$. Besides the intrinsic affinity of angiogenin to heparin, the poly-lysine tag provided additional ionic affinity. And the subsequent refolding yield increased nearly 13-fold, from ca. $4.8\%$ in the conventional refolding of the untagged fusion protein to $63.6\%$. The process was highly reproducible. The refolded protein in the column eluate retained RNase bioactivity of angiogenin.

• Journal of the Korean earth science society
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• 제38권2호
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• pp.115-128
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• 2017

Aso caldera volcano is located in central Kyushu, Japan which is one of the largest caldera volcanoes in the world. Nakadake crater is the only active central cone in Aso caldera. There was an explosive eruption on October 8, 2016, the eruption column height was 11 km, and fallout ash was found 300 km away from the volcano. In this study, we performed a numerical simulation to analyze the ash dispersion and the fallout tephra deposits during this eruption using Ash3D that was developed by the United States Geological Survey. The result showed that the ash would spread to the east and northeast, that could not affect the Korean peninsula, and the volcanic ash was deposited at a place from a distance of 400 km or more in the direction of east and northeast. The result was in close agreement with the identified ashfall deposits. Ash3D can be useful for quick forecast for the effects of hazards caused by volcanic ash.

• Journal of Microbiology and Biotechnology
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• 제29권2호
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• pp.274-282
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• 2019

Mercury-resistant ($Hg^R$) bacteria were isolated from heavy metal polluted wastewater and soil collected near to tanneries of district Kasur, Pakistan. Bacterial isolates AZ-1, AZ-2 and AZ-3 showed resistance up to $40{\mu}g/ml$ against mercuric chloride ($HgCl_2$). 16S rDNA ribotyping and phylogenetic analysis were performed for the characterization of selected isolates as Bacillus sp. AZ-1 (KT270477), Bacillus cereus AZ-2 (KT270478) and Bacillus cereus AZ-3 (KT270479). Phylogenetic relationship on the basis of merA nucleotide sequence confirmed 51-100% homology with the corresponding region of the merA gene of already reported mercury-resistant Gram-positive bacteria. The merE gene involved in the transportation of elemental mercury ($Hg^0$) via cell membrane was cloned for the first time into pHLV vector and transformed in overexpressed C43(DE3) E. coli cells. The recombinant plasmid (pHLMerE) was expressed and the native MerE protein was obtained after thrombin cleavage by size exclusion chromatography (SEC). The purification of fusion/recombinant and native protein MerE by Ni-NTA column, dialysis and fast protein liquid chromatography (FPLC/SEC) involved unfolding/refolding techniques. A small-scale reservoir of wastewater containing $30{\mu}g/ml$ of $HgCl_2$ was designed to check the detoxification ability of selected strains. It resulted in 83% detoxification of mercury by B. cereus AZ-2 and B. cereus AZ-3, and 76% detoxification by Bacillus sp. AZ-1 respectively (p < 0.05).