• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.1-6
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• 1991

In this study, intermediate thermo-mechanical treated Al-2.0 wt%Li, and Al-2.0 wt%Li-1.2 wt%Cu-1.0 wt%Mg-0.12 wt%Zr alloys were tested in tension at $10^{\circ}C$ and elevated temperature(100, 200 and $300^{\circ}C$). The results are follows : The tensile strength of Al-Li-Cu-Mg-Zr alloy is the highest but the elongation of Al-Li alloy is the highest(106%) among the all alloys in tension at $300^{\circ}C$. The Portervin-LeChartlier effect is showed in AI-Li-Cu-Mg-Zr alloy at 10 and $100^{\circ}C$, because of tangled dislocation by Mg and Cu. In the true stress-strain curves of all alloy, the peaks of stress at $300^{\circ}C$ are showed at the strain less than 0.1. In the binary alloy, the dynamic restoration process at 200 and $300^{\circ}C$ is nearly similar to dynamic recovery type. The hot deformation stress is decreased with increase of dynamic recovery degree, but the elongation is increased. When the strain the strain rate are constant, the temperature dependence of hot deformation stress is increased with increase of deformation temperature. The elongation and degree of dynamic recovery are decreased with increase of hot deformation activation energy, but the deformation stresses slightly increased.

• Parasites, Hosts and Diseases
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• v.22 no.2
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• pp.153-160
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• 1984

An experimental study was undertaken to observe the difference in susceptibility of mouse strains to Metagonimus yokogawai infection by estimating it from worm recovery rate and dimension of worms. It was also studied the effects of prednisolone injection on the chronological pattern of worm recovery in ICR mice. The metacercariae were obtained from sweetfish and 300 in each number were given to 5 strains (CBH, A, DBA, $C^{57}BL$ and KK) of mice, and after 7 days period, the worms were collected from their intestine. Prednisolone at the dose of 10 mg/kg was injected to ICR mice every other day from 7 days prior to infection until sacrificed at 6 hours to 35th post-infection day. ICR mice infected with M. yokogawai but untreated were used for controls. The success rate in infection of mice ranged 25.0-83. 3% by strains, the worm recovery rate 1. 2-18. 9%, and the average size of worms O. 554-0. 683 mm long and 0.214-0.244 mm wide. The higher rates and larger size of worms were observed in KK and $C^{57}BL$ strains than others and the difference was statistically significant. In ICR mice for control, the worm recovery rate until 1 day after infection was relatively high (38-66%) but it became much lower (less than 0.7%) during 1-35 days. However, prednisolone injection brought about persistently high recovery rates (16-80%) until 21 days. It was concluded that the susceptibility to M. yokogawai infection is different by strains of mice but it can be elevated by prednisolone injection probably due to suppression of Immune respon3e3 in ICR mice.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.164-166
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• 1996

Human aorta has viscoelastic behavior. The test of tissues such as aorta, skin, muscle, and ok. is required to consider visco effect on deformation behavior. Creep and slow recovery are main aspects of viscoelasticity of tissue engineering. Volumatric strain plays a important role in determine slow recovery of human arota. This study is to suggest the method avoiding viscous effect in tissue experiment The results shows the time scale when the specimen can be fully recovered from slow deformation. Also, this study observes the qualitative creep-effect on elastic strain in 1 minute at the same loading.

• Transactions of Materials Processing
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• v.9 no.1
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• pp.72-79
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• 2000

Dynamic recrystallization (DRX), which may occur during hot deformation, is important for the microsturctural evolution of 304 stainless steel. Especially, the current interest in modelling hot rolling demands quantitative relationships among the thermomechanical process variables, such as strain, temperature, strain rate, and etc. Thus, this paper individually presents the relationships for flow stress and volume fraction of DRX as a function of processing variables using torsion tests. The hot torsion tests of 304 stainless steel were performed at the temperature range of 900~110$0^{\circ}C$ and the strain rate range of 5x10-2~5s-1 to study the high temperature softening behavior. For the exact prediction of flow stress, the equation was divided into two regions, the work hardening (WH) and dynamic recovery (DRV) region and the DRX region. Especially, The flow stress of DRX region could be expressed by using the volume fraction of DRX (XDRX). Since XDRX was consisted of the critical strain($\varepsilon$c) for initiation of dynamic recrystallization (DRX) and the strain for maximum softening rate ($\varepsilon$*), that were related with the evolution of microstructure. The calculated results predicted the flow stress and the microstructure of the alloy at any deformation conditions well.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.6
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• pp.717-726
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• 2005

Statement of problem. One of the common problems of provisional crown and fixed partial denture materials is that when they are subjected to constant loads for a long period of time, they exhibit a dimensional change (creep). Purpose. The aim of this study was to investigate the viscoelastic behaviour of polymer-based provisional crown and fixed partial denture materials with time at constant compressive load. Material and methods. Three dimethacrylate-based materials (Protemp 3 Garant, Temphase, Luxatemp) and one monomethacrylate-based material (Trim) were selected. Dimensional changes of the specimens were recorded by a LVDT to evaluate their viscoelastic behavior and creep strain. For all specimens, two loading procedures were used. At first, static compressive stress of 4 MPa was applied for 30 minutes and followed by 1 hour of strain recovery. Then, after 24 hours of water storage, the specimens were loaded again. The creep values between materials were statistically analyzed using one-way ANOVA and multiple comparison $Scheff\acute{e}$ test. Independent samples t-test was also used to identify the difference of creep strain between first and secondary loading conditions at the significance level of 0.05. Results. Following application of the first loading, Trim showed the highest maximum creep strain (32.7%) followed by Luxatemp, Protemp 3 Garant and Temphase, with values of 3.78%, 2.86% and 1.77%, respectively. Trim was significantly different from other materials (P<0.05), while there were no significant differences among Luxatemp, Protemp 3 Garant and Temphase (P>0.05). The highest recovery and permanent set of Trim, were significantly different from those of others (P<0.05). At the secondary loading of the dimethacrylate-based materials, creep deformation, recovery and permanent set decreased and the percentage of recovery increased, while in Trim, all values of the measurements increased. This result showed that the secondary loading at 24 hours produced a significant creep magnitude. Conclusion. The dimethacrylate-based provisional crown and fixed partial denture materials showed significantly higher creep resistance and lower deformation than the monomethacrylate-based material. Thus, monomethacrylate-based materials should not be used in long-term stress-bearing situations.

• Journal of Food Hygiene and Safety
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• v.25 no.4
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• pp.320-324
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• 2010

Five different enrichment methods were studied to find an optimal method to recover Yersinia enterocolitica from swine feed samples. When the recovery of Y. enterocolitica GER-C (serotype O:3) strain was studied at 1000 CFU/g feed, phosphate-buffered saline (PBS) enrichment at $4^{\circ}C$ and PBS plus sorbitol and bile salts (PSB) enrichment at $4^{\circ}C$ and $21^{\circ}C$ were not effective (< 22%). In contrast, both irgasan-ticarcillin-potassium chlorate (ITC) and tryptic soy broth plus polymyxin B sulfate and novobiocin (TSBPN) enrichment methods showed a full recovery (100%) at 100-1000 CFU/g feed. At 10 CFU/g feed, both ITC and TSBPN methods still recovered the strain (> 50%). In recovery of ATCC 9610 (serotype O:8) strain, TSBPN method was more sensitive than any other methods (P < 0.05) at 1000 CFU/g feed. Using TSBPN method, the strain was still recovered at 100 CFU/g feed, but not at 10 CFU/g feed. With its sensitivity and relatively simple recipe, TSBPN was most desirable method to recover Y. enterocolitica from swine feed samples.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.243-257
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• 2003

The purpose of this study was to search the influences of the increase of the contents of sodium alginate in the experimental alginates on the some mechanical properties. 3 commercial alginates were selected for the purpose of comparison of the results of experiments. 7 experimental alginates were manufactured with the rise of contents of sodium alginate from 8.8% to 18.3% with the decrease of contents of diatomaceous earth and with the constant contents of calcium sulfate 12.5%. sodium phosphate 2.2%, zinc fluoride 2.0%. Splitable metal mold with 12.5mm diameter and 20.0mm height was filled with mixed alginate to prepare the cylinder shaped specimens. Strain in compression, elastic recovery, compressive strength were tested using the ISO specification number 1563, alginate impression material. Experimental groups were 7, and 10 specimens were used for each test items and each groups. Following results were obtained ; 1. Strain in compression was decreased with the increase of sodium alginate contents (p=0.0077, r2 = 0.6302). 2. Elastic recovery was decreased with the increase of sodium alginate contents but was not significant(p=0.0639, r2=0.7449). 3. Compressive strength was increased with the increase of sodium alginate contents (p<0.0001, r2 = 0.9617). These results mean that the increase of sodium alginate contents make alginate harder but may result the increased permanent deformation.

• Fashion & Textile Research Journal
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• v.8 no.3
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• pp.349-356
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• 2006

The purpose of this study was to compare the thermophysiological responses and subjective sensations of clothing materials with different water transfer property investigated in exercising and resting subjects at an ambient temperature of $20^{\circ}C$ and a relative humidity of 40%. Two kinds of clothing ensemble were tested: 100% cotton with highly water-absorbent but slowly dry properties(C) and 100% polyester with quickly water-absorbent and dry properties by four capillary channels(QADP). Seven apparently healthy male participants each undertook two series of experiments comprised 10-min of rest, 20-min of exercise with 70% of $VO_{2max}$ on a treadmill and 20-min of recovery. Mean skin temperature was significantly lower in QADP than in C during exercise and recovery. Clothing microclimate temperature was significantly lower in QADP during exercise and clothing surface temperature was also lower in QADP especially during recovery. Also, clothing surface humidity was significantly higher in QADP after the later half of exercise. The concentration of blood lactic acid tended to decrease to a lower level at recovery 3 minutes when wearing QADP rather than C clothing ensemble. Metabolic energy was marginally significantly less during the second half of exercise in QADP. Body mass loss tended to be greater in C than in QADP. The participants had better scores in thermal sensation, comfortable sensation and wetness in QADP during exercise and recovery. These results show that functional materials with quickly water-absorbent and dry properties can alleviate heat strain and induce more comfortable clothing microclimates and subjective sensations in the exercise-induced hyperthermia.

• Fashion & Textile Research Journal
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• v.9 no.3
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• pp.347-350
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• 2007

To analyse basic properties for making packing batt according to doubling condition, packing batt yarn, of $300^D$, $900^D$, $3600^D$ made from DTY yarn $150^D$/48 were produced from KTDI. The results are as follows: The birefringence of the sample yarn increased with increasing the annealing temperature and denier. The initial modulus of the sample yarn decreased with increasing the annealing temperature and denier. The higher than annealing temperature of $160^{\circ}C$, initial modulus of the sample are equilibrated. The strain recovery ratio of samples decreased with increasing the annealing temperature and denier. The lower than annealing temperature of $140^{\circ}C$, strain recovery ratio of the sample are decreased Where the $900^D$, $3600^D$ yarns are at $100^{\circ}C$ the specific bending rigidity value obtained is 0.65kgf/d but the twisted yarn (3,600) obtained 0.006 ($gfcm^2/tex^2$). However, where the heat temperature is $160^{\circ}C$, specific bending rigidity value obtained 0.003($gfcm^2/tex^2$).

• Elastomers and Composites
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• v.40 no.4
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• pp.258-265
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• 2005

To study the compressive stress, recovery force and permanent strain of foams for footwear midsole, polyurethane(PU), phylon(PH) and injection phylon(IP) foams were repetitively compressed with constant compressive stress. Maximum compressive stress of PU did not decrease with repetitive compression on the constant compressive stress, but that of IP largely decreased. Engineering strain of foams were formed by repetitively compressing the three types of foam. The engineering strain of PU was smaller than that of IP and PH. Compressive stress and recovery force of IP and PH at certain strain were decreased with repetitive compression, but that of PU was not noticeably changed.