• Fibers and Polymers
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• v.5 no.1
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• pp.19-24
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• 2004

PET yarns textured at different texturing conditions were treated with superheated steam or dry heat at different temperatures for different times. The effects of the treatment conditions on the thermomechanical and structural changes of the yarn were examined by shrinkage, X-ray diffraction and birefringence measurements. With increase in superheated steam temperature, the crystalline orientation factor and birefringence decreased, whereas crystal size increased. Dry heat treatment had a smaller effect on shrinkage and structural properties in comparison with superheated steam treatment. The additional shrinkage after texturing process was investigated. The effect of heat-setting in both media was more significant at $200^{\circ}C$. The time dependence of the properties was not linear.

• Textile Coloration and Finishing
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• v.22 no.2
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• pp.173-179
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• 2010

In this study, we determine the stretch and shrinkage properties of conjugated yarns. The shrinkage(%) and elasticity(%) were determined by applying twist conditions of 0, 350, 800, 1000, 1200, 1400, 1600, 2000 T/M (twisting per meter). It is found that the shrinkage(%) and elasticity(%) gradually decreased with increasing T/M. Especially the elasticity(%) dramatically decreased over 1400 T/M condition. In contrast, it is showed that the handle and drapery properties decreased below 1000 T/M, which indicates that the optimal T/M condition could be 1000~1400. The effect of shrinkage(%) and elasticity(%) with different steam setting temperatures (60, 70, 80 and $90^{\circ}C$) was also determined. The shrinkage(%) decreased with increasing setting temperature, while the elasticity not changed. In this context, the optimal steam setting temperature could be $80^{\circ}C$ because it is not easy to weave with the yarns which was set below $80^{\circ}C$. The elasticity(%) decreased with increasing the density of warp and weft. To produce soft handle, excellent drapery and good stretch fabrics, the warp density needs to be reached by 90% of the ideal warp density. In the case of NaOH treatments to the fabrics, the elasticity(%) increased with increasing weight reduction. Therefore, this study have demonstrated that the conjugated yarns with core yarn and the SDY CD(cation dyeable spindraw yarn) as an effect yarn would be appropriate to produce excellent mixture-yarn, which displays clean appearance, good handle and excellent elasticity, The optimized conditions are as follows; 1000~1200 twist per meter, $80^{\circ}C$ steam setting temperature, 90% of ideal warp density and relaxation condition treated with 5g/l NaOH concentration.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.19-24
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• 2018

Fuel cells are used to generate electricity with a reformer. In particular, methanol has various advantages among the fuels for reformer. Methanol steam reformer devices can efficiently supply hydrogen to PEM fuel cell. This study investigated the optimal operation conditions of a methanol steam reforming process. For this purpose, aspen HYSYS was used for the optimization of reforming process. The optimal operating condition could be designed by setting independent variables such as temperature, pressure and steam to carbon ratio (SCR). The optimal temperature and steam to carbon ratio were $250-270^{\circ}C$ and 1.3-1.5, respectively. It is advantageous to operate at a pressure of 15-20 barg, considering the performance of the hydrogen purifier. In addition, a heat exchange network was designed to supply heat constantly to reformer through the latent heat of steam.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.141-148
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• 2017

This study is experimentally investigated the effects of various steam curing parameters on the early-age compressive strength development of high strength concrete (over 40 MPa) in the precast plant production. High strength concrete are used only ordinary portland cement (type I) and water-cement ratio selected 3cases (25%, 35% and 45%). Also, steam curing parameters are as followings ; (1) Preset period 2cases (3 hours and 6 hours) (2) Maximum curing temperature 3cases ($45^{\circ}C$, $55^{\circ}C$ and $65^{\circ}C$) (3) Maintenance time of curing temperature 3cases (4 hours, 6 hours and 8 hours) (4) Maximum rate of heating and cooling $15^{\circ}C$/hr. Initial setting time and adiabatic temperature rising ratio of these concrete according to water-cement ratio are tested before main tests and examined the compressive strength development for the steam curing parameters. Also compressive strength are compared with optimum steam curing condition and standard curing at test ages. As test results, the optimum steam curing conditions for high strength concrete(over 40 MPa) are as followings. (1) Preset period ; over initial setting time of concrete (2) Maximum curing temperature ; bellow $55^{\circ}C$ (3) Maintenance time of curing temperature ; bellow 6hours. Also strength development of steam curing concrete show in the reversed strength at 28 days. It is to propose an efficient steam curing condition for high strength concrete in the precast method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.1
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• pp.20-28
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• 2012

The monofilament with 0.304mm of diameter was produced using a polybutylene succinate (PBS) resin, and a gill net was made by it. We investigated the impact of heat setting temperature on the mechanical properties, knot state and height of gill net. Heat treatment was carried out using the high pressure steam machine for 20 minutes at temperature of $55^{\circ}C$, $60^{\circ}C$, $70^{\circ}C$ and $75^{\circ}C$. Before heat treatment, the strength and elongation of PBS monofilament were estimated to be $48.1kg/mm^2$, 23.8% at unknot, $37.6kg/mm^2$, 18.8% at single knot, $26.6kg/mm^2$, 22.9% at double knot in dry condition, respectively. The strength and elongation of PBS monofilament with double knot were decreased as heat setting temperature increased, and the decreasing rate of strength was showed to be higher than that of elongation. It was not found any differences in strength and elongation of PBS monofilament yarn with double knot at the $65^{\circ}C$ and $70^{\circ}C$ of heat setting temperature by 5% significance of T-test, but there was a significant difference at the $70^{\circ}C$ and $75^{\circ}C$ of heat setting temperature. The net's height and length from leg to leg appeared no differences at the $70^{\circ}C$ and $75^{\circ}C$ of heat setting temperature. In results, it was investigated that the PBS monofilament gill net with the maximized physical properties could be manufactured at $70^{\circ}C$ of heat setting temperature using a high pressure steam machine for 20 minutes.

• Journal of the Korean Society of Earth Science Education
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• v.11 no.3
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• pp.224-236
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• 2018

The purpose of this study was to develop a reasoning-based HTE-STEAM program for the development of the cognitive capacity of middle school students and enhancement of their STEAM literacy, and to investigate the effectiveness of this study in the school setting. The subjects of this study were the students of two middle schools located in the central region of Korea. The students participated in the HTE-STEAM program during their free-learning semesters and 202 of them were selected by random sampling method. Main findings were as follows: First, pre- and post-HTE-STEAM program has shown a significant value in statistical verification (p<.05) and the level of logical thinking ability of the research participants improved after the class compared to before the class. Second, the paired samples t-test comparing the difference between the pre and post scores of the STEAM attitude test has shown a significant value in statistical verification (p<.05), and the HTE-STEAM program has turned out to have a positive effect on the STEAM literacy of the research participants. Third, in the HTE-STEAM satisfaction scale test, the mean value of the sub-construct stood at 3.27~4.12, showing a positive overall response. Therefore, the HTE-STEAM program under the topic of earth science of 'Disaster and Safety' developed at the final stage of this study has proven to have a positive influence on the research participants in terms of the development of cognitive capacity by reasoning and collaborative learning, an important quality of communication and consideration necessary for STEAM literacy.

• The Korean Journal of Food And Nutrition
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• v.22 no.2
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• pp.199-204
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• 2009

For the purpose of developing a safe & hygienic manufacturing method to acquire low levels of benzo(a)pyrene in black and red ginseng products, this study investigated the effects of steam- and dry-processing temperatures on benzo(a)pyrene production in ginseng. By the red ginseng with a fix dry-process temperature of $50^{\circ}C$ and setting the steam-process temperature between $80{\sim}120^{\circ}C$, an extremely small amount(0.1 ppb) of benzo(a)pyrene was produced, indicating there was no relationship between the steam-temperature and benzo(a)pyrene production. On the other hand, when the red and black ginseng were steamed at the fixed temperature of $100^{\circ}C$ and dried at various temperatures between $50{\sim}120^{\circ}C$, the amount of benzo(a)pyrene produced was closely connected with the dry-temperature, and increased with higher drying temperatures. Upon repeating the steam and dry process nine times, in which the steam-temperature was set at $100^{\circ}C$ and the dry-temperature at $50^{\circ}C$, higher amount of benzo(a)pyrene were produced in red and black ginseng, respectively, with increasing steam- and dry-processing time. However, the level of benzo(a)pyrene still remained extremely small(below 0.12 ppb), showing a maximum amount in the black ginseng that was steamed and dried nine times. This suggests that the fine root of ginseng may be carbonized by increasing the number of times it is steam- and dry-processed. From the above results, this study determined that the optimum temperatures for manufacturing red and black ginseng products with safe levels of benzo(a)pyrene would be a temperature between 80 and $120^{\circ}C$ for steaming and a temperature less than $50^{\circ}C$ for drying.

• Plant Journal
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• v.4 no.3
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• pp.66-72
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• 2008

The vibration of steam turbine is caused by Mass unbalance, Shaft misalignment, Oil whip and rubbing etc. But in turbine which is normally operated and maintained, the Mass unbalance component possesses the greatest portion. Our power plant has two steam turbines in capacity of 200 MW and 135 MW respectively and each turbine is supported by 6 journal bearings. However, we had many difficulties because the vibration amplitude of #3 and #4 Bearings was high during the start-up and operation mode change of steam turbine. But, with this study, we completely solved the vibration problem caused by the mass unbalance of #1 steam turbine. Until a recent date, #3 and #4 bearings which support high pressure turbine for #1 steam turbine had shown about $135{\mu}m$ in vibration amplitude (sometimes it increased to $221{\mu}m$ maximum. alarm: 6 mils, trip: 9 mils) at base load. After applying the study, they decreased to about $45{\mu}m$ maximum. It is a result from that we did not change the setting value of bearing alignment and only changed the assembly position of internal parts in Synchro clutch coupling rachet wheel which links between high pressure turbine and low pressure turbine, and increased the internal gap and machining of the Pawl cage surface. In the operation of steam turbine, if the vibration value increases by 1X, we should reduce the vibration of bearing by weight balancing. However, unless the vibration of bearing is declined by the balancing, we will have to disassemble and check the component and find the cause. In this study, we researched the way to lower mass unbalance that is 1X vibration component which has the greatest portion of vibration generated by steam turbine and we got good result by applying the findings of this study.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.232-235
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• 2008

The vibration of steam turbine is caused by Mass Unbalance, Shaft Misalignment, Oil Whip and Rubbing etc. but in turbine which is normally operated and maintained, the Mass Unbalance component possesses the greatest portion. Our power plant has two steam turbines in capacity of 200MW and 135MW respectively and each turbine is supported by 6 journal bearings. However, we had many difficulties because the vibration amplitude of No 3 and 4 Bearings was high during the start-up and operation mode change of steam turbine. But, with this study, we completely solved the vibration problem caused by the mass unbalance of No 1 steam turbine. Until a recent date, No 3 and 4 bearings which support high pressure turbine for No 1 steam turbine had shown about 135${\mu}$m in vibration amplitude (sometimes it increased to 221${\mu}$m maximum. alarm: 6mils, trip: 9mils) at base load. After applying the study, they decreased to about 40${\mu}$m maximum. It is a result from that we did not change the setting value of Bearing Alignment and only changed the assembly position of internal parts in Synchro Clutch Coupling Rachet Wheel which links between high pressure turbine and low pressure turbine, and increased the internal gap and machining of the Pawl stopper surface. In the operation of steam turbine, if the vibration value increases by 1X, we should reduce the vibration of bearing by weight balancing. However, unless the vibration of bearing is declined by the balancing, we will have to disassemble and check the component and find the cause. In this study, We researched the way to lower mass unbalance that is 1X vibration component which has the greatest portion of vibration generated by steam turbine and We got good result by applying the findings of this study.

• Journal of Ceramic Processing Research
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• v.19 no.5
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• pp.407-412
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• 2018

In this study, we have made a cement based inorganic insulation material and added CSA (Hauyne Clinker) to reduce the demolding time and enhance the handling workability. CSA contents were varied by 0%, 1%, 3%, 5% and the atmospheric steam curing was tried for enhancing the compressive strength. As the CSA contents are increased to 5%, a rapid reaction of hydration caused the sinking of the slurry. So, the setting-retarder was added to control the reaction of hydration. By this, the sinking of the slurry was controlled but the height of the green body after expansions was a little bit lowered. In the CSA-added slurry, it was possible to demold within 24 hours and in case of CSA 5%-added, the sufficient workability was secured. Atmospheric steam curing (temperatures $-40{\sim}80^{\circ}C$, for 6~10 hrs.) was attempted to improve the compressive strength and found that an excellent strength of 0.25 MPa was achieved at $80^{\circ}C$ for 8 hrs. Specific gravity was about $0.12{\sim}0.13g/cm^3$ and heat conductivity was about 0.045 W/mK in all specimens. This strategy significantly improves the compressive strength of CSA 5%-added specimen up to 25% compared to without CSA added specimen.