• Korean Journal of Animal Reproduction
• /
• v.17 no.3
• /
• pp.173-181
• /
• 1993

In order to demonstrate whether ovoperoxidase hardens the zona of oocytes activated by incubating in M-S buffer supplemented with 20$\mu$M of Ca-ionophore A 23187, the effect of peroxidase inhibitors(250mM pheylhydrazine, 28mM sodilum sulfite, 350mM glycine ethyl ester and 50mM sodium azide), tyrosine analogue(12.5mM tyramine) and exogeneous peroxidase(50$\mu\textrm{g}$/ml horseradishperoxidase ; HRP) on zona hardening in ionorphore-treated oocytes were investigated. The results obtained from thses experiments were summarized as follows : 1. The zona solubility (t50) of ionophore-activated and DMSO-treated oocytes at 1, 2 and 3 hr of culture were 25.0, 31.6 and 40.6min., and 9.7, 10.8 and 15.5 min., respectively. The longest time required for zona lysis of ionophore activated oocytes at 1 hr after onset of ionophore treatment. The diferences int50 for zona was significantly greater as compared to DMSO-treated controls(P<0.01). 2. The inhibition rates of hardening in the oocytes treated with the phenylhydrazine, sodium sulfite, glycine ethyl ester and sodium azide, were 23.8, 61.9, 95.2 and 23.8%l, respectively, and the tyramine, was 14.3%. Several known peroxidase inhibitors and tyrosine analogue were blocked zona hardening in ionophore activated oocytes. 3. The treatment of exogeneous peroxidase promoted the zona hardening of activated oocytes but not unactivated oocytes. These resuls indicate that the ovoperoxidase apparently catalyzes the hardening of the zona following ionophore activation of mouse oocytes.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.2C
• /
• pp.75-81
• /
• 2008

In this study, a series of laboratory column test on Suction Drain Method which is one of the way to make an soft ground improvement were conducted in order to investigate the effect of the Hardening Zones and the ratio of improvements depending on periods of the improvements and various applied suction pressures. On this occasion, the experimental conditions are followings; in the case of the periods of effectiveness, 4 days, 8 days, 12 days, 16 days, 20 days and in the case of the applied pressures of the Suction are -20 kPa, -40 kPa, -60 kPa and -80 kPa were carried out. As a result of test, settlement increased with suction pressure and duration increase, and gradually converged. Also, as comparing permeability decrease ratio with which calculated back from water content and numerically predicted using Hansbo's radial consolidation theory, measured value was almost coincide with predicted value when permeability decrease ratio was assumed as 2~3. Furthermore, the hardening zone was appeared within 7~8 cm of whole radial (25 cm).

• Journal of the Korean Society for Heat Treatment
• /
• v.18 no.3
• /
• pp.172-176
• /
• 2005

Modern automobiles are built with a steadily increasing variety of materials and semifinished products. The traditional composition of steel sheet and cast iron is being replaced with other materials such as aluminum and magnesium. But low formability of these materials has prevented the application of the automotive components. The formability can be enhanced by conducting the warm hydroforming using induction heating device which can raise the temperature of the specimen very quickly. The specimen applied to the test is A6061, A7075 extruded tubes which belong to the age-hardenable aluminum alloys. But in the case of A6061 age hardening occurs at room temperature or at elevated temperatures before and after the forming process. In this study the effects of the heating condition such as heating time, preset temperature, holding time during die closing and forming time on the hydroformability are analyzed to evaluate the phenomena such as dynamic strain hardening and ageing hardening at high temperatures after the hydroforming process.

• Journal of the Korean Society for Heat Treatment
• /
• v.2 no.2
• /
• pp.17-26
• /
• 1989

This study has been performed to investigate into some effects of the Sursulf treatment time and the traveling speed of surface hardening treatment on the hardness and the wear characteristics by applying the combined heat treating techniques of Sursulf process followed by induction hardening treatment to mild steel. It has been shown that increasing the Sursulf treatment time increases the case depth, but both hardness and wear resistance are not considerably improved. When the combined heat treating technique of high frequency induction heating after Sursulf treatment is applied, an improvement in case depth as well as wear resistance is obtained. In particular, the hardness in diffusion zone is greatly increased due mainly to the formation of martensite and possibly lower bainite. Iron oxides formed during induction heating and subsequent water spray cooling in the outermost part of compound layer may be considered to cause some increases in hardness and wear resistance.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.1
• /
• pp.90-96
• /
• 2009

Injection molding process is one of the most important methods to produce plastic parts with high efficiency and low cost. Today, injection molded parts have been increased dramatically the demand for high strength and quality applications. This report investigates that the optimum injection molding condition for minimum of shrinkage. Molding shrinkage is occurred by several reasons such as thermal shrinkage, a hardening process and compressibility. This report concentrate on shrinkage by a hardening process. As Change a holding pressure and holding time, checked deflections of X, Y, Z directions by shrinkage based on same condition. In conclusion, it was found that holding pressure is stronger and holding time is longer, the deflection by shrinkage is smaller because injection molding needs enough time for cooling and high density. The FEM Simulation CAE tool. Moldflow, is used for the analysis of injection molding process.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.295-300
• /
• 2001

In road pavements, it is known that cement concrete pavement has superior durability, safety in compared with asphalt concrete pavement. But in reparing pavement cement concrete pavement is not usually applied because of the length of time while the road is interrupted when using Ordinary and Rapid-hardening Portland Cement. And Super High Early Strength Cement and Ultra Super High Early Strength Cement are not favorable for ready mixied concrete because of rapid setting time, high slump loss and other restrictions. We aim to develope specific cement and concrete developing 1 day strength of over 300 kg/$cm^{2}$ to open the road within one day and workable time is maintained over 1 hour that can be used as ready mixed concrete. In this study, we Produced cement using rapid-hardening cement, Hauyne clinker, anhydride gypsum and accelerator and studied on its properties. The concrete strength was over 300 kg/$cm^{2}$ at 1 day and 550 kg/$cm^{2}$ at 28 day and workable time was maintained for over 1 hour.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.233-238
• /
• 2001

In road Pavements, it is known that cement concrete pavement has superior durability, safety compared with asphalt pavement. But in repairing pavement, cement concrete pavement is not usually applied because of the length of time while the road is interrupted when using Ordinary and Rapid-hardening Portland Cement. And Super High Early Strength Cement and Ultra Super High Early Strength Cement are not favorable for ready mixed concrete because of rapid setting time, high slump loss and other restrictions. We aim to develope special cement and concrete developing 1 day strength of over 300 kg/$\textrm{cm}^2$ to open the road within one day and workable time is maintained over 1 hour that can be used as ready mixed concrete. In this study, we produced cement using rapid-hardening cement, Hauyne clinker, anhydride gypsum and accelerator and studied on its properties. The comperssive strength was over 400 kg/$\textrm{cm}^2$ and tensile at 1 day and workable time was maintained for over 1 hour.

• Structural Engineering and Mechanics
• /
• v.54 no.4
• /
• pp.809-827
• /
• 2015

In this paper, seismic energy response of inelastic steel structures under earthquake excitations is investigated. For this purpose, a numerical procedure based on nonlinear dynamic analysis is developed by considering material, geometric and connection nonlinearities. Material nonlinearity is modeled by the inversion of Ramberg-Osgood equation. Nonlinearity caused by the interaction between the axial force and bending moment is also defined considering stability functions, while the geometric nonlinearity caused by axial forces is described using geometric stiffness matrix. Cyclic behaviour of steel connections is taken into account by employing independent hardening model. Dynamic equation of motion is solved by Newmark's constant acceleration method in the time history domain. Energy response analysis of space frames is performed by using this proposed numerical method. Finally, for the first time, the distribution of the different energy types versus time at the duration of the earthquake ground motion is obtained where in addition error analysis for the numerical solutions is carried out and plotted depending on the relative error calculated as a function of energy balance versus time.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.43 no.3
• /
• pp.157-160
• /
• 1998

To find out the effects of humidification and hardening of rice (Oryza sativa L. cv. Ilpumbyeo) seeds on the germination, both normal and artificially aged seeds with 60% germination rate were humidified at 40, 60, and 80% RHs and $25^{\circ}C$ for five weeks or hydrated for 6, 12, 18, and 24 hours at $25^{\circ}C$ from one to five cycles for hardening. Relative humidity and duration of humidification did not affect the germination rate of normal seeds, while reduced the time to get 50% germination rate ($T_{50}$) by 1.0～1.6 days compared to that of normal seeds at $25^{\circ}C$. Aged seeds humidified at 40 and 60% RHs did not affect the germination rate and $T_{50}$ regardless of relative humidity and duration of treatment, while at 80% RH, the germination rate decreased and $T_{50}$ increased significantly with the duration of humidification. Hardening of normal seeds reduced $T_{50}$ by 0.7～1.1 days without changes in the germination rate. However, the germination rate and $T_{50}$ of aged seeds soaked in water for 6, 12, and 18 hours were similar regardless of soaking/drying cycles, while hardening of artificially aged seeds with 1～4 cycles in 24 hours soaking increased the germination rate by 11-16% and reduced $T_{50}$ by 1.4～2.0 days.

• Geomechanics and Engineering
• /
• v.9 no.4
• /
• pp.499-511
• /
• 2015

The creep property of salt rock significantly influences the long-term stability of the salt rock underground storage. Triaxial creep tests were performed to investigate the creep behavior of salt rock. The test results indicate that the creep of salt rock has a nonlinear characteristic, which is related to stress level and creep time. The higher the stress level, the longer the creep time, the more obvious the nonlinear characteristic will be. The elastic modulus of salt rock decreases with the prolonged creep time, which shows that the creep damage is produced for the gradual expansion of internal cracks, defects, etc., causing degradation of mechanical properties; meanwhile, the creep rate of salt rock also decreases with the prolonged creep time in the primary creep stage, which indicates that the mechanical properties of salt rock are hardened and strengthened. That is to say, damage and hardening exist simultaneously during the creep of salt rock. Both the damage effect and the hardening effect are considered, an improved Maxwell creep model is proposed by connecting an elastic body softened over time with a viscosity body hardened over time in series, and the creep equation of which is deduced. Creep test data of salt rock are used to evaluate the reasonability and applicability of the improved Maxwell model. The fitting curves are in excellent agreement with the creep test data, and compared with the classical Burgers model, the improved Maxwell model is able to precisely predict the long-term creep deformation of salt rock, illustrating our model can perfectly describe the creep property of salt rock.