• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.159-163
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• 2022

A linearly moving structure in the area where the friction force is dominant - such as ducts filled with grease in the nuclear power plant - experiences increase in friction since the contact surface gets larger as the structure proceeds. To solve this problem is critical for the pipe inspection robot to investigate further area and this makes the system more energy-efficient. In this paper, we propose a passively growing sheath that can be added to linearly moving structures using zipper mechanism. The mechanism enables the linearly moving structures to maintain rolling contact condition against external environment, which provides substantial reduction in kinetic friction. To analyze the effect of the mechanism's head shape, we establish a physical model and compare to the experimental results. Finally, we have shown that the passively growing sheath can be successfully applied to the pipe inspection robot for the nuclear power plant.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.6
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• pp.837-842
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• 2003

Five varieties of napiergrasses (Pennisetum purpureum) were fractionated botanically into leaf blade, leaf sheath, stem and head. Chemical composition of each of whole napiergrass and their botanical fractions were determined. Correlation, linear and multiple regressions between botanical fractions and nutritive value of varieties of napiergrass were also estimated. All botanical fractions differed due to the effect of variety. Napier Pusha contained the highest proportion of leaf blade and internode, but the lowest proportion of leaf sheath. Napier Hybrid contained the lowest proportion of leaf blade, but highest proportion of node. Consequently, napier Pusha contained the highest (p<0.01) crude protein (CP, 9.0%), but Napier Hybrid had the lowest CP (7.0%). Chemical composition of whole plant differed significantly (p<0.01; except NFE, p>0.05) due to the variety. Not only the whole plant, chemical composition of most botanical fractions of whole plant differed (p<0.05 to 0.01) due to the variety. The intrarelationships between leaf blade and leaf sheath was negative (r=-0.43). Leaf sheath was also negatively correlated to CP, but positively correlated to ash of whole Napier or their botanical fractions. Leaf blade, on the other hand, increases CP but decreases ash content of whole plant or their fractions. These results, therefore, suggest that napiergrass varieties differ widely in terms of botanical fractions and nutritive value, which may have important implications on intake and productivity of animals. Furthermore, napiergrass varieties should be selected for leaf blade only for a better response.

• Korean Journal of Agricultural Science
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• v.3 no.1
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• pp.23-30
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• 1976

This study was done to find out the effect of seeding seasons of rice varieties on the occurence of sheath blight caused by Corticium sasakii. The results obtained are summarized as follows; 1. The percentage of infected stems and susceptibilities to sheath blight wered ecreased as the transplanting dates were delayed. 2. The susceptibilities to sheath blight of early maturing varieties were high, medium maturing varieties were intermediate and late maturing varieties were least. 3. The percentages of infected stems of Indica X Japonica varieties checked on 28th July were lower than those of Japonica varieties, but the susceptibilities were not significant between them. 4. At all varieties, highly significant correlation was recognized between the susceptibilities and the heading dates. Also relatively high correlation was appeared between the susceptibilities and the accumulated temperatures from 10 days before heading date to 30 days after it. This indicates that the susceptibility was much influenced by high temperature of the latter part of the rice plants growth.

• Journal of Embryo Transfer
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• v.26 no.3
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• pp.181-186
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• 2011

Spermatozoa sorted by flow cytometry have been successfully used to produce offspring in domestic animals and are commercially available for cattle. Also sheath fluid is the important environment for viability of sex-sorted sperm in flow cytometry. The aim of this study was to investigate whether or not HEPES (N-2-hydroxyethylpiperazine-N'-2-Ethanesulfonic acid) has any effect on the viability in sex-sorted Hanwoo (Korean native cattle) sperm. In this study, the semen was collected from Hanwoo of Hoengseong Livestock Cooperation by artificial vagina method then pooled and subjected to cryopreservation in straws. Sperm were cultured for 0, 30, 60 and 120 min with 0, 2.5, 5, 7.5 and 10 mM of HEPES added to the sheath fluid and incubated at 4, 20 and 38$^{\circ}C$, respectively. For the cytometric analysis the frozen-thawed semen was extended with 5 mM HEPES extender to final concentration ($2{\times}10^7$ spermatozoa) at 4, 20 and 37$^{\circ}C$. Sperm viability was assessed with SYBR-14 and propidium iodide (PI) staining. This study shows that the viability of sperm was decreased with prolongation of incubation time in all of test. But the viability of sperm which were treated with 38$^{\circ}C$ was gently decreased than that of treated with other temperature. The viability of the control was sharply decreased (p<0.05) than all of the HEPES treatment group at 60 to 120 min in 38$^{\circ}C$. X-sexed sperm was more sensitive than Y-sexed sperm to temperature during f10w cytometry (p<0.05). In conclusion, the results of this study suggest that the sheath fluid with 5 mM HEPES has effect on maintenance of viability after sperm sexing at 37$^{\circ}C$ in Hanwoo.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.148-150
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• 2002

The distributed jointing method is used in the underground tunnel due to narrow space of jointing. This method causes non-uniform length between cable joints. It has an effect on the sheath circulating current and the induced voltage. Furthermore the distributed jointing method may cause transient overvoltage resulting from lightning in underground cable which is connected with overhead line. The author diversely studied the sheath circulating current and induced voltage on underground cable depending on the distributed jointing length under the normal and the transient circumstances. The various simulation results really improve the cable system utility.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.131-133
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• 2003

The effect of axial strain and thermal cycling on the critical current is investigated for the Bi-2223/Ag PIT tapes. The axial strain was applied to the tapes by the U-shape sample holder. Two kinds of Bi-2223/Ag tapes with different Ag sheath are used to know the effect of sheath alloying for the tensile strain. The influence of thermal cycling between room temperature and 77 K on critical current are examined. Critical current is drastically decreased for Ag/alloy and Ag/alloy/alloy sheathed tapes at tensile strain above 0.22％ and 0.3％, respectively.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2059-2063
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• 2008

When a thermocouple is placed in a high temperature gas-flow stream, the measured temperature could be biased from the true gas temperature due to a large radiation heat loss from a thermocouple surface to its surroundings. In this study, two thermocouples of unequal diameters with 1/8 inch and 1/16 inch are used to correct the radiation effect. The method is called the reduced radiation error (RRE). The preliminary test results show that the radiation and the sheath conduction cannot be negligible for the gas temperature measurement. To minimize the sheath conduction effect, all the thermocouples will have a grounded junction and 1/8 inch thermocouple will be replaced with 1 mm thermocouples. In addition, the computational fluid dynamics code analysis shows that there is a negligible temperature difference between the positions where the thermocouples were installed.

• The Journal of Korea Robotics Society
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• v.14 no.3
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• pp.221-227
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• 2019

This paper studies an effect of vibration on twisted string actuation inside conduit at high curvature angles. In our previous work. we have mentioned that twisted string actuators can be used to transmit power even at significant curvature angles of the conduit. However, several undesirable effects, namely pull-back, hysteresis, and chattering, were present during actuation due to friction between strings and the internal sheath of the conduit. This paper reports the results of experimental study on effects of vibration on twisted string actuation inside curved conduits. We have demonstrated that applying vibration generated near natural frequency of the system during the stages of twisting and untwisting cycles helped reduce pull-back and hysteresis and increase string contraction. In case when sheath was deflected by $180^{\circ}$ under a constant load of 3 kg, we were able to achieve over 40% decrease in pull-back and 30% decrease in hysteresis, compared with no vibration case.

• Proceedings of the Korean Society of Crop Science Conference
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• 1996.05a
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• pp.60-61
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• 1996

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.276-279
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• 2000

When high temperature superconducting tapes is fabricated using the PIT (Powder In Tube) method, the length of HTS tapes is increased more than 500 ${\sim}$ 1,000 times of initial powder packed billet. On mechanical processing, heterogeneous properties between the ceramic superconducting core and Ag/Ag alloy sheath occur the non-uniformity deformation as like sausaging that deteriorate the critical current properties of HTS tapes. In this study, we investigated the workability of Bi-2223/Ag/Ag alloy sheath tapes fabricated by the PIT method involving a number of different mechanical processes, multi drawing and rolling. In order to obtain the high critical current density and high uniformity of Bi-2223/Ag sheath tapes, the influences of powder packing density, drawing die angle and rolling parameters were studied. We found that the roll diameter is an important variable in the rolling process, as critical current of tapes rolled using 250 mm rolls was higher than that using 150 mm rolls.