• Steel and Composite Structures
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• v.13 no.3
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• pp.239-258
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• 2012

In this paper, experimental investigations on high strength steel (HSS) stud connected steel-concrete composite (SCC) girders to understand the effect of shear connector density on their flexural behaviour is presented. SCC girder specimens were designed for three different shear capacities (100%, 85%, and 70%), by varying the number of stud connectors in the shear span. Three SCC girder specimens were tested under monotonic/quasi-static loading, while three similar girder specimens were subjected to non-reversal cyclic loading under simply supported end conditions. Details of casting the specimens, experimental set-up, and method of testing, instrumentation for the measurement of deflection, interface-slip and strain are discussed. It is found that SCC girder specimen designed for full shear capacity exhibits interface slip for loads beyond 25% of the ultimate load capacity. Specimens with lesser degree of shear connection show lower values of load at initiation of slip. Very good ductility is exhibited by all the HSS stud connected SCC girder specimens. It is observed that the ultimate moment of resistance as well as ductility gets reduced for HSS stud connected SCC girder with reduction in stud shear connector density. Efficiency factor indicating the effectiveness of high strength stud connectors in resisting interface forces is estimated to be 0.8 from the analysis. Failure mode is primarily flexure with fracturing of stud connectors and characterised by flexural cracking and crushing of concrete at top in the pure bending region. Local buckling in the top flange of steel beam was also observed at the loads near to failure, which is influenced by spacing of studs and top flange thickness of rolled steel section. One of the recommendations is that the ultimate load capacity can be limited to 1.5 times the plastic moment capacity of the section such that the post peak load reduction is kept within limits. Load-deflection behaviour for monotonic tests compared well with the envelope of load-deflection curves for cyclic tests. It is concluded from the experimental investigations that use of HSS studs will reduce their numbers for given loading, which is advantageous in case of long spans. Buckling of top flange of rolled section is observed at failure stage. Provision of lips in the top flange is suggested to avoid this buckling. This is possible in case of longer spans, where normally built-up sections are used.

• Food Science and Preservation
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• v.13 no.5
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• pp.603-610
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• 2006

Korean traditional soy paste (Doenjang) was fermented using Meju prepared by the culture of wild microorganisms in steamed soy beans. During the fermentation, changes in the physicochemical and several functional properties were monitored. Total acidity and amino acidity increased from 0.09 to 0.96, and 2.24% to 3.28% respectively, Amylase and protease activities increased and showed the maximal level after 60 days of fermentation, which were 4.03 and 7.29 units/ml, respectively. However, both enzyme activities decreased after then. The inhibitory activities against tyrosinase and angiotensin converting enzyme increased and reached 20.57 and 38.18% respectively. Antimutagenic activities against N-methyl-N'-nitro-N-nitiosoguanidine and 4-nitro-O-phenylenediamine (NPD) increased for 90 days and roached 70.21 and 60.01% in S. enterica serovar Typhimurium TA100, respectively. Against NPD and 4-nitroquinoline-1-oxide, the antimutagenic activities also increased and reached 50.91 and 46.35% in the strain TA98, respectively.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.343-348
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• 2012

Developmental period, mummification, pupal mortality, and sex ratio of Korean strain of Aphelinus varipes F$\ddot{o}$rster parasitizing the green peach aphid, Myzus persicae were studied at 20, 25, 30, and $35^{\circ}C$ in controlled climate cabinets. The plastic container with a leaf disc of sweet pepper (Capsicum annuum L.) was used as experimental units. Green peach aphids at different developmental stages were reared in four different temperatures and presented to A. varipes for 12 hours. A female adult of A. varipes was allowed to parasitize for 12 hours in each plastic petri dish. The periods from egg to adult of A. varipes were 18.3 days, 14.7 days, 10.4 days, and 9.3 days at $20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$, and $35^{\circ}C$, respectively. The pupal mortalities of A. varipes were 0%, 1.5%, 2.8%, and 10.2% at $20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$, and $35^{\circ}C$, respectively. The mummifications of A. varipes were significantly different in all developmental stages of the aphid. The mummification of A. varipes parasitizing green peach aphid was the highest at 1st and 2nd in $20^{\circ}C$ and $25^{\circ}C$, but the highest at 3rd (84.4-85.0%) in $30^{\circ}C$ and $35^{\circ}C$. The host feedings of A. varipes were $20^{\circ}C$ (12.5%), $25^{\circ}C$ (17.3%), $30^{\circ}C$ (16%), and $35^{\circ}C$ (10.9%), respectively. The sex ratios of A. varipes female were $20^{\circ}C$ (49%), $25^{\circ}C$ (46%), $30^{\circ}C$ (69%), and $35^{\circ}C$ (60%), respectively.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.63-68
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• 2019

Dielectric and piezoelectric properties of PIN-PMN-PT piezoelectric single crystals with variation of temperature and compressive stress were investigated. The crystal phase of the single crystal was changed from the ferroelectric rhombohedral structure to tetragonal structure in the 110℃ region and from the tetragonal structure to the paraelectric cubic structure in the 190℃ region. The piezoelectric constant and relative dielectric constant were calculated from the rate of change of polarization and displacement with the application of electric field, which was similar to the value measured from the instrument. As the compressive stress applied to the sample increased, the piezoelectric constant d₃₃ and relative dielectric constant values tended to increase. When the compressive stress applied to the sample at 5℃ was 60 MPa, the d₃₃ was calculated as 4,500 pC/N. At 60℃, the relative dielectric constant of 62000 was calculated when the compressive stress applied to the sample was 40 MPa. The increase in piezoelectric constant and relative dielectric constant when the compressive stress increased could be attributed to the phase transition from the rhombohedral structure to orthorhombic.

• Nuclear Engineering and Technology
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• v.21 no.2
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• pp.111-122
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• 1989

With the Zircaloy-4 tube oxidized in high temperature (1323 K) steam for 5, 10, 30 and 60 minutes, the expanding copper mandrel test was carried out over a temperature range of 673-l173k at $\varepsilon\;=\;3.0\times10^5S\;^1$. The oxidation parameters $(K_i)$ in the present study were linearly proportional to square root of time $(Ki= \delta_{kit})$ and their rate constants ($\delta_{ki}$) are 0.281, 2.82, and 2.313 for weight gain and thickness of Zr02 and $\alpha$(0) layer, respectively. Activation energy for high temperature (873-1073k) plastic deformation of Zircaloy-4 increases from 251 KJ/mol to 323 KJ/mol with increase in oxidation time from 5 minutes to 60 minutes due to the high strengthened Zr02. With the oxide layer thickness [K ; expressed in "Equivalent Cladding Reacted" (ECR,%)] and the yield stress obtained from the mandrel test, an empirical relation was derived as ($\sigma/C)^n=K^mexp$ (Q/RT) with n=6.9, m=5.7, C=0.155, 0.138, 0.051, and 0.046 MPa for Q=251, 258, 316, 323 KJ/mol, respectively.

• Journal of Adhesion and Interface
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• v.18 no.1
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• pp.13-24
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• 2017

In this study, nanoparticles which encapsulated hydrophobic antimicrobial compounds with 50wt% of payload and 70%of solid content were prepared. These nanoparticles could be dispersed at water as well as various medium. Water dispersible organic-inorganic (O-I) hybrid nanoparticles were first prepared using alkoxysilane-functionalized amphiphilic polymer precursors through a conventional sol-gel process. Hydrophobic antimicrobial compound, Eugenol encapsulated nanoparticles were prepared using these O-I hybrid nanoparticles through a new nanoprecipitation process. The effect of various preparation on the size of nanoparticles, amount of payload, antimicrobial activity, and release rate of encapsulated compounds was investigated. All eugenol-encapsulated O-I nanoparticles regardless of preparation condition showed the same minimal inhibitory concentration (MIC) (50mg/ml) and 99% of antimicrobial activity for every strain. Their antimicrobial activity could maintain longer than two weeks. Especially, eugenol-encapsulated O-I nanoparticles prepared using tetraethoxysilane (TEOS) exhibited the highest payload (50wt%) and the lowest release rate which was owing to higher inorganic content in the O-I nanoparticles. And these O-I nanoparticles dispersed in hexanediol (HD) showed the highest antimicrobial activity and solid content (70wt%) because HD acted as a solvent as well as a antimicrobial agent.

• Journal of Ginseng Research
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• v.3 no.1
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• pp.1-34
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• 1979

Our nation is confronted with the situation that the rice, a principal food, short of some essential amino acids, leads to imbalanced meals insufficient in the nutrient of Protein, to bring many difficulties in the elevation of nutritional state in our nation. While. our country has been produced much amounts of Panax Ginseng roots which has a stimulating effects on the metabolism of protein, lipid and nucleic acids in the body. And the leaf and trunk of Panax Ginseng were also produced a considerable amounts as the by-products. Author believe that these by-products (leaf and trunk) of Panax Ginseng might have some components possessing simillar activity with Panax Ginseng root although the quantity and qualify of the functional components may more or less be different. Therefore, this study was demised to observe the supplemental effect of the Panax Ginseng-by-Products on the dietary protein efficiency and nutritional state of rats. The feeds used for this experiment were rice containing 30% barely, fish four, and the leaf, trunk and small root of the Panax Ginseng, and the contents of the general nutrients including protein, lipid and carbohydrate etc. in each feed were analyzed for the combination of each feed. And, being based on analytical values of Protein in food. fish Pour as Protein source was added were rice containing 30% barely to be include 8.6 to 8.7%, 12%, 15% and 18% of protein. Then 2% of the leaf, trunk or small reef of Panax Ginseng was supplemented into each of above protein diet group, ton 16 kinds of diets were Prepared. The male albino rats from a Pure strain, weighing 70g to 80g. were used for experimental animals. They were maintained with coresponding fist for f and 8 weeks, and the growth rate, consumption of diets and protein, efficiency of feed and Protein in animals were determined. The lipids, proteins and cholesterols in serum and liver were also determined quantitatively after they were sacrificed in coresponding term. The results obtained are summarized as follows: 1. Body weigh of diet group containing 8.6 to 8.7%,12%, and 15% of protein are increased remarkably by supplement of 2% of the leaf or small root of Panax Ginseng in comparison with each of controls. But this tendency could not observed in diet group containing 18eA Proteins. 2. Feed efficiency showed same tendency in comparison with changes of gained body weight. Specially, in each of diets containing 8.7%, 12%, 15% and 18% of Proteins, supplement of the leaf of Panax Ginseng showed the better feed efficiency than supplement of the trunk or small root. 3. In feeding group for 8 weeks, protein efficiency showed worst efficiency in diet containing 18% proteins and showed the best efficiency was the diet group containing 12% Proteins. And the efficiency was improved according to supplement of the leaf of Panax Ginseng. 4. Nitrogen contents in serum and liver did not show large differences each other in all diet groups. But contexts of total cholesterol and 1ipid were decreased markedly in diet groups containing 12%, 15% and 18% of proteins in comparison with diet group containing 8.6% to 8.8% of proteins.

• Weed & Turfgrass Science
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• v.5 no.1
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• pp.29-34
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• 2016

Large patch disease in Zoysia japonica Steud. is the most destructive disease in turfgrass. For large patch management, it has been dependent on chemical controls but pesticides are harmful to soil, water and biodiversity. In this study, we evaluated 4 Streptomyces spp. strains (S2, S5, S8 and S12) which were selected in previous studies using metagenome approaches. Root colonization of the strains, large patch suppressing effect and the pathogen density change in actual golf course were investigated to evaluate biological control potential of the strains. All strains exhibited reliable root colonization ability that strains populations were higher than $6log\;cfu\;g^{-1}$ in turfgrass rhizosphere. The pathogen density, with S8 treatment, was detected average of 0.7 after a week and average of 1.2 after 4 weeks. Disease control and suppressive the pathogen population by S8 strain showed higher efficiency than other strains. S8 was applied in an actual golf course for the large patch control and pathogen density. The pathogen density in S8 treatment plot was detected below 1.6 per toothpick and lower compared with untreated plot. The results indicated that pathogen density was suppressed by S8 and the stain has great potential as a biological control agent for the large patch.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.239-247
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• 2008

Use of both carbon fiber (CF) and glass fiber (GF) at the same time to strengthen existing flexural members was exploited. Using a proper volumetric GF / CF ratio, the CF can rupture first followed by subsequent rupture of GF at higher stress and strain showing a pseudo-ductile behavior. A theoretical study indicated that the ratio is 4.62 : 1 and higher where the pseudoductile effect can be shown. Flexural tests of plain concrete beams strengthened using fibers were first carried out. Hybrid FRP sheet using 8.8 : 1 ratio was then fabricated and the sheet was used to strengthen reinforced concrete beams. The RC beams strengthened using 1-ply and 2-ply hybrid sheets both revealed increased strength over a non-strengthened beam and ductile flexural behavior. A comparable beam strengthened using CF also showed increased strength but with limited ductility.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.37-44
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• 1999

Because of bone resorption, wear of ultra-high molecular weight polyethylene(UHMWPE) in total knee arthroplasty has been recognized as a major factor in long-term failure of knee implant. The surface damage and the following harmful wear debris of UHMWPE is largely related to contact stress. Most of the previous studies focused on the contact condition only at the articulating surface of UHMWPE. Recently, contact stress at the metal-backing interface has been implicated as one of major factors in UHMWPE wear. Therefore, the purpose of the is study is to investigate the effect of the contact stress for different thickness, conformity friction coefficient, and flexion degree of the UHMWPE component in total knee system, considering the contact conditions at both interfaces. In this study, a two-dimensional non-linear plane strain finite element model was developed. The results showed that the maximum value of von-Mises stress occurred below the articulating surface and the contact stress was lower for the more conforming models. All-polyethylene component showed lower stress distribution than the metal-backed component. With increased friction coefficient on the tibiofemoral contact surface, the maximum shear stress increased about twofold.