• Structural Engineering and Mechanics
• /
• v.12 no.2
• /
• pp.119-134
• /
• 2001

This paper deals with an experimental and numerical study of a mono-strand wedge anchor head mechanism. First, the experimental program is presented and monitored data such as wedge slippage, anchor deflection and strain distributions along external peripheral surfaces of the anchor head are presented and discussed. In accordance with the experimental set up, these data concern only the global behaviour of the mechanism and cannot provide valuable information such as internal stress-strains distributions, stress concentrations and percentage of yielded volume. Therefore, the second part of this paper deals with the development of an efficient numerical finite element model capable of providing mechanism of the core information. The numerical model which includes all kinematics/material/contact non-linearities is first calibrated using experimental data. Subsequently, a numerical study of the anchorage mechanism is performed and its behaviour is compared to the behaviour of a slightly geometrically modified mechanism where the external diameter has been increased by 5 mm. Finally, different topics influencing the anchorage mechanism behaviour are addressed such as lubrication and wedge shape.

• Journal of Ginseng Research
• /
• v.27 no.4
• /
• pp.178-182
• /
• 2003

Vesicular-arbuscular mycorrhizae (VAM) fungi naturally colonise American ginseng roots and this relationship is highly beneficial to enhance plant productivity. Our goal was to determine the effect of adding two Glomus species (Glomus etuticatum, G. intraradices) on survival, photosynthetic capacity, growth, morphology and root ginsenoside content of one-year-old American ginseng plants grown in a broadleaf forest. While our study revealed that VAM inoculations significantly affected root morphology and Re ginsenoside content, the survival, photosynthetic capacity and root growth of American ginseng plants were not significantly influenced by VAM inoculations. Surface area and volume of rootlets were 16-25% higher for ginseng grown in VAM-inoculated soil compared to those grown in the control plots. Also, Re ginsenoside content was 18 ％ higher in YAM-inoculated roots compared to controls.

• Journal of Ginseng Research
• /
• v.32 no.4
• /
• pp.347-356
• /
• 2008

Forest-grown American ginseng (Panax quinquefolius L.) is exposed to daily and seasonal light variations. Our goal was to determine the effect of understory light changes on the maximum quantum yield of photosystem II, expressed as $F_v/F_m$, and photosynthetic pigment composition of two-year-old plants. Understory light photon flux density and sunfleck durations were characterized using hemispherical canopy photography. Our results showed that understory light significantly affected the $F_v/F_m$ of American ginseng, especially during the initial development of the plants when light levels were the highest, averaging 28 mol $m^{-2}d^{-1}$. Associated with low $F_v/F_m$ during its initial development, American ginseng had the lowest levels of epoxidation state of the xanthophyll cycle of the season, suggesting an active dissipation of excess light energy absorbed by the chlorophyll pigments. As photon flux density decreased after the deployment of the forest canopy to less than 10 mol $m^{-2}d^{-1}$, chlorophyll a/b decreased suggesting a greater investment in light harvesting pigments to reaction centers in order to absorb the fleeting light energy.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.18 no.1
• /
• pp.8-15
• /
• 2014

The ablation characteristics of graphite nozzle throat insert is analyzed for the use in solid rocket propulsion system. The propulsion system is composed of three types of conventional nozzles, such as De-Laval type, blast tube type, and submerged type. Various kinds of propellants are used in the thirteen kinds of propulsion system that has different shapes of each other. Total thirty seven tests are performed. From the results of the analysis, it is found that the ablation rate is higher for the higher average chamber pressure and the higher concentration of oxidizing species in combustion gas.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.4
• /
• pp.12-20
• /
• 2017

The ablation characteristics of graphite nozzle throat insert was analyzed for the use in solid rocket propulsion system. The propulsion system was composed of three types of conventional nozzles, such as De-Laval type, blast tube type, and submerged type. Various kinds of propellants were used in ten kinds of propulsion system that had different shapes with each other. Total forty eight tests were performed. From the results of the analysis, it was found that the ablation rate was increased for the higher average chamber pressure and the higher oxidizer mole fraction. A useful correlation for nozzle throat ablation rate was developed in terms of the chamber pressure, oxidizer mole fraction, and throat size. The calculated ablation rates from the correlation showed agreement within ${\pm}0.10mm/s$ with the experimentally determined values.

• International Journal of Precision Engineering and Manufacturing
• /
• v.6 no.1
• /
• pp.23-30
• /
• 2005

The air-jet loom represents a major step in the development of shutterless weaving due to its ability to weave a wide range of yarns at high speeds. The air-jet weaving involves inserting a pre-measured length of yarn through the wraps, which is shed by means of compressed air. The analysis of air flow characteristic of the main nozzle and acceleration tube is required for improving the loom performance. In this paper, we examined the effects of the main nozzle with different acceleration tubes as well as diameters. Also, we compared the performance of a straight-type tube with a Laval-type tube and the effect of installing a suction hole on the acceleration tube.

• Journal of ILASS-Korea
• /
• v.8 no.2
• /
• pp.16-23
• /
• 2003

The Air-jet loom represents a major step in the development of shutterless weaving due to its ability to weave a wide range of yarns at high speeds. The Air-jet weaving involvers, inserting a pre-measured length of yam through the wrap, is sheds by meads of compressed air. The analysis of air flow characteristic of the main nozzle and acceleration tube is required for the loom performance. h this paper We examined the effect of the main nozzle with different acceleration tubes as well as diameters. And also, we compared the performance of straight type tube with laval type tube and of according to be suction hole on the acceleration tube, respectively.

• The Korean Journal of Zoology
• /
• v.38 no.4
• /
• pp.465-482
• /
• 1995

The 7 zoeal and 1 megalopal stages of Cha~bdi8 bimaculata (Miers, 1886) are descrihed and iflustrated in detail from larvae reared in lahoratory. Under isboratory conditions of 22$^{\circ}C$ temperature and 33.3~ salinity, the magalopa was attained in 32 days or more after hatching. The larval morphology of the first zoea of C. bimaculata are coincide with those of Charybdis species by hearing lateral spines on carapace, ~type antenna, A-type telson, 1,6 setae on the endoped of maxillule, and 6 setae on the endopod of maxilla. Morphological features of C. bimaculata larvae were compared to the previous descriptions of larvae of the other spedes helonging to the same genus.

• Journal of Aquaculture
• /
• v.9 no.1
• /
• pp.11-18
• /
• 1996

We described morphological characteristics of embryonic, larval, and juvenile period of the yellow puffer, Takifugu obscurus. We defined seven periods of embryogenesis the zygote, cleavage, blastula, gastrula, segmentation, pharygula, and hatching periods. The eggs were adhesive and spherical in shape. The egg yolk had numerous tiny oil globules. Hatching began about 280 hours after insemination at $17.0{\pm}1.0^{\circ}C$ water temperature. Melanopores of star shape were seen on yolk, head and trunk during the pharygula and hatching period. The hatched larvae haying large yolk were $3.00\~3.54$ mm in size with $25\~26$ myomeres. The larvae completely absorbed the yolk materials and oil globules within 7 days after hatching and became post-larvae. Laval fish became juveniles within 60 days after hatching, and they reached $23.54\~30.12$ mm in total length and had fin-rays.

• Journal of Aquaculture
• /
• v.20 no.4
• /
• pp.260-264
• /
• 2007

We investigated egg collection and the effects of water temperature (4, 7, 10, 13 and $16^{\circ}C$) on egg development, hatching and larval growth of Pacific cod Gadus macrocephalus under laboratory conditions. Fertilized eggs were round in shape ($1.01{\pm}0.03\;cm$) and adhesive to nylon nets. Fertilization rate was 68% by wet method. The time of egg development was negatively proportional to water temperature with the range of $4^{\circ}C$ to $13^{\circ}C$. Eggs hatched only at $7^{\circ}C$ after 288 hours of fertilization and $10^{\circ}C$ after 192 hours. Hatching rate was highest as 65% at $7^{\circ}C$ followed by $34.4^{\circ}C$ at $10^{\circ}C$. Survival rate was 18.3% at $7^{\circ}C$ and 5.2% at $10^{\circ}C$.