• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.436-449
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• 2017

In this paper, the damage and failure behavior of triaxially braided textile composites was studied using progressive failure analysis. The analysis was performed at both micro and meso-scales through iterative cycles. Stress based failure criteria were used to define the failure states at both micro- and meso-scale models. The stress-strain curve under uniaxial tensile loading was drawn based on the load-displacement curve from the progressive failure analysis and compared to those by test and computational results from reference for verification. Then, the detailed failure initiation and propagation was studied using the verified model for both tensile and compression loading cases. The failure modes of each part of the model were assessed at different stages of failure. Effect of ply stacking and number of unit cells considered were then investigated using the resulting stress-strain curves and damage patterns. Finally, the effect of matrix plasticity was examined for the compressive failure behavior of the same model using elastic, elastic - perfectly plastic and multi-linear elastic-plastic matrix properties.

• Advances in concrete construction
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• v.4 no.1
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• pp.1-14
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• 2016

In this study, high performance concrete beams and prisms with high content of PFA were heated to various temperatures up to $450^{\circ}C$ at heating rates of $1^{\circ}C/min$, $3^{\circ}C/min$ and $10^{\circ}C/min$. The thermal gradient was found to increase first with the heating time until a peak value was reached and then decrease until the thermal equilibrium was reached, measured as $115^{\circ}C$, $240^{\circ}C$ and $268^{\circ}C$ for the three heating rates. Spalling occurred on some specimens when the heating temperature was over $400^{\circ}C$ for heating rates of $3^{\circ}C/min$ and $10^{\circ}C/min$. The hygric gradient was found to reach its maximum when the thermal gradient reached its peak. This study indicates that spalling of HPC could happen when the heating temperature was high enough, and both thermal and hygric gradients reached their maxima.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7B
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• pp.1351-1360
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• 1999

In frequency selective channels, conventional PN code acquisition schemes are not ideal candidates. This is because they are primarily designed for the AWGN channel. In this paper, a direct-sequence spread-spectrum(DSSS) PN code acquisition system based on digital matched filtering (DMF) with automatic threshold control(ATC) algorithm is presented and analyzed with regards to probability of detection and probability of false alarm. These two important probabilities, the probability of detection ($P_D$) and the probability of false alarm ($P_{FA}$) are derived and analyzed in considering Doppler shift, sampling rate, mean acquisition time, and PN chip rate in frequency selective Rayleigh fading channel when using serial-search method as detection technique. From computer simulation results of a DMF acquisition system model, it is shown that the performance of the acquisition system using ATC algorithm is better than that of constant threshold system.

• Economic and Environmental Geology
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• v.30 no.5
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• pp.443-450
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• 1997

The main purpose of this study is to investigate mineralogical and chemical changes during natural weathering, and assess the mobility of major and trace elements. Yongwol power plant utilize anthracite coal which is mainly composed of illite, kaolinite, pyrophyllite and quartz in mineralogy. Coal and coal-derived fly ash samples were sampled by the electrostatic precipitator in Yongwol coal-fired power plant in Korea. Short term weathered fly ash were also collected in ash disposal mound, and two profile soil samples were taken from an ash near the power plant. Amorphous materials are the main component of the fly ash, and mullite, quartz, magnetite and heamatite are present in all coal-derived fly ash. In chemistry, Si and Al are the most abundant elements of the total content. The ash samples were fractionated into upper $90{\mu}m$ and under $45{\mu}m$ size. Finer particles show higher concentrations in metal contents including Co, Cr, Cu, Ni, V, Zn and Pb. Concentration of Zn and Pb are nearly 4 times higher concentration in the finer particles. For the profile samples, the concentrations of $SiO_2$, $Na_2O$, MgO and $K_2O$ generally show increasing trends with depth, whereas those of $Fe_2O_3$ and $TiO_2$ appear to decrease with depth. Content of MnO does not show any specific depth trend. For the trace elements, Co, Cu, Ni and V show increasing concentrations with depth.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.77-77
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• 2003

Chimeric animals are referred to as an organism composed of tissues derived from more than one species. In order to examine if a pluripotency of embryonic stem cells can cross the limitation of a species, we tried to establish human-mouse chimeric animals. Human embryonic stem cells were genetically modified to express eGFP using eukaryonic expression vector pcDNA 3.1 (In Vitrogene) for an easy identification. After selection with neomycin, approximately 15 cells were implanted into mouse blastocoele cavity. Ten chimeric blastocysts were transferred to one of the uterine horn of 2.5 days pesudopregnent ICR female. Out of 272 blastocysts transferred to pseudopregnant recipients 20 live newborn were obtained after 20 days. When newborn were obtained, pups were quickly removed immersed into 4% PFA. By histological examination using fluorescent microscope, green fluorescence was observed from the liver, heart, and spleen in newborn mice. Three weeks after born, presence of eGFP sequence within mouse genome (tail and kidney) was reconfirmed by PCR. eGFP sequence was amplified from the progenies of the animal suggesting a genetic transmission of the transgene. These chimeric mice having human cells at the beginning of development, are expected to recognize human cells as “self”, therefore, human cells or tissues will be able to escape the immunological surveillance of the host if grafted into the animal. These animals will serve as a good model system for studying the graft rejection in tissue transplantation and the potential of the cells to work well in many human disease.

• Journal of Acupuncture Research
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• v.19 no.5
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• pp.10-27
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• 2002

연구목적 : 면역억제와 활성 작용을 지닌 것으로 알려진 녹용약침(CPH)을 type II collagen 유발 관절염 (CIA) 백서와 인산이온 유발 연골세포의 세포사에 있어 보호활성 효과를 연구하였다. 연구방법 : 7주된 암컷 Sprague-Dawley 쥐를 collagen으로 관절염을 유발시킨 후 CPH의 효과를 관절염 점수, 체중감소 등의 평가기준으로 검정하였다. CPH는 일주일에 5번씩 각각 10, 20, 30 및 $100{\mu}g/kg/day$의 용량으로 양측 신수혈에 주입하였다. 연구결과 : 1. 300 mg/kg/day CPH처리로 관절염점수의 감소를 기초로 한 collagen 유발 관절염의 발생을 완전히 억제하였으며 관절염 점수상에서 CPH의 효과작인 용량은 64 mg/kg이었다. 2. CHP는 쥐의 간에 있는 DHO-DHase 활성을 $Ki=843{\pm}43{\mu}g/ml$의 비교적 높은 비활성으로 억제하였다. 3. 관절염관련 세포의 증식억제활성을 검정한 결과 CPH의 항 증식효과는 세포주기 S기에서 정지시키는 활성을 나타내었다. 4. 쥐의 늑연골로부터 완전히 최종 분화된 비대연골세포를 분리 배양하여 3~5mM/L Pi를 첨가함으로서 세포사멸을 측정하였다. $10{\mu}g/ml$ CPH 처리에 의한 보호(억제) 효과가 Pi-유발 연골세포의 세포사에 대한 Na-Pi cotransport의 경쟁적 저해제로 알려진 phosphonoformic acid(PFA)의 억제활성과 상응하는 수준으로 CPH의 활성을 확인하게 되었다.

• Corrosion Science and Technology
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• v.8 no.3
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• pp.110-115
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• 2009

At the onset of corrosion of steel in concrete, hydrogen ions usually evolve in the process of electrochemical reaction, thereby decreasing the pH of the pore solution, which can be buffered by cement hydration products, as being representatively illustrated by calcium hydroxide. Hence, a fall in the pH is dependent on properties of cement hydration (i.e. hydration products and degree of hydration). The present study tested acid neutralization capacity (ANC) of cementitious binders of OPC(Ordinary Portland Cement), 30% PFA(Pulverized Fuel Ash), 60% GGBS(Ground Granulated Blast Furnace Slag), 10% SF(Silica Fume) to quantify the resistance of cement matrix to a pH fall. Cement pastes were cast at 0.4 of a free W/C ratio with 1.5% chlorides by weight of binder in cast. Powder samples obtained crushed and ground specimen after 200 days of curing were diluted in still water combined with different levels of 1M nitric acid solution, ranging from 0.5 to 20 mol/kg. Then, the pH of diluted solution was monitored until any further change in the pH did not take place. It was seen that the pH of the diluted solution gradually decreased as the molar amount of nitric acid increased. At some particular values of the pH, however, a decrease in the pH was marginal, which can be expressed in the peak resistances to a pH fall in the ANC curve. The peaks occurred at the variations in the pH, depending on binder type, but commonly at about 12.5 in the pH, indicate a resistance of precipitated calcium hydroxide. The measurement of water soluble chloride at the end of test showed that the amount of free chloride was significantly increased at the pH corresponding to the peaks in the ANC curve, which may reflect the adsorption of hydration products to chlorides.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.86-92
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• 2011

ITS(Intelligent Transport System) has been researched actively to guarantee the smooth traffic and the safety of the vehicle. In recent, as the sensor for the measurement of distance between vehicles, the FMCW radar system in millimeter wave band has been interested in ITS. Actually, 47, 60, 77, 94 and 139 GHz have been assigned for the vehicle radar frequencies in Europe and Japan. However, the performances of the FMCW radar are deteriorated due to the interferences from the surrounding radars and mobile devices. In this paper, in order to model and simulate the performance of FMCW radar under the exterior interference, we propose a new performance parameter, RER(Radius Error Rate), which contains the information of the range error due to the interferences, and show the effectiveness of the proposed parameter.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.447-452
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• 2013

In this study we report a new method for the synthesis of a silica monolithic column bed with bimodal pores (throughpores and mesopores). The template induced synthesis method was used to direct bimodal pores simultaneously instead of the usual post base-treating method. Block polymer Pluronic F127 was chosen as a dual-function template to form hierarchically porous silica monolith with both macropores and mesopores. This is a simplification of the method of monolithic column preparation. Poly(ethylene glycol) was used as a partial substitute for F127 can effectively prevent shrinkage during the monolith aging process without losing much surface area (944 $m^2/g$ to 807 $m^2/g$). More importantly, the resultant material showed a much narrower mesopore size (centered at 6 nm) distribution than that made using only F127 as the template reagent, which helps the mass transfer process. The solvent washing method was used to remove the remaining organic template, and it was proved to be effective enough. The new synthesis method makes the fabrication of the silica monolithic column (especially capillary column) much easier. All the structure parameters indicate that monolith PFA05 prepared by the above method is a good material for separation, with the merits of much higher surface area than usual commercial HPLC silica particles, suitable mesopore volume, narrow mesopore size distribution, low shrinkage and it is easily prepared.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1144-1154
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• 2019

There have been several studies regarding lichen-associated bacteria obtained from diverse environments. Our screening process identified 49 bacterial species in two lichens from the Himalayas: 17 species of Actinobacteria, 19 species of Firmicutes, and 13 species of Proteobacteria. We discovered five types of strong antimicrobial agent-producing bacteria. Although some strains exhibited weak antimicrobial activity, NP088, NP131, NP132, NP134, and NP160 exhibited strong antimicrobial activity against all multidrug-resistant strains. Polyketide synthase (PKS) fingerprinting revealed results for 69 of 148 strains; these had similar genes, such as fatty acid-related PKS, adenylation domain genes, PfaA, and PksD. Although the association between antimicrobial activity and the PKS fingerprinting results is poorly resolved, NP160 had six types of PKS fingerprinting genes, as well as strong antimicrobial activity. Therefore, we sequenced the draft genome of strain NP160, and predicted its secondary metabolism using antiSMASH version 4.2. NP160 had 46 clusters and was predicted to produce similar secondary metabolites with similarities of 5-100%. Although NP160 had 100% similarity with the alkylresorcinol biosynthetic gene cluster, our results showed low similarity with existing members of this biosynthetic gene cluster, and most have not yet been revealed. In conclusion, we expect that lichen-associated bacteria from the Himalayas can produce new secondary metabolites, and we found several secondary metabolite-related biosynthetic gene clusters to support this hypothesis.