• Composites Research
• /
• v.29 no.1
• /
• pp.24-32
• /
• 2016

Ballistic impact analyses have been performed with the Kevlar fabric impregnated with STF(shear thickening fluid). Multi-layer laminates modeled with 3D isoparametric shell elements were used for the performance analysis and their results are compared with experimental results. Both experiments and numerical analyses have been done to verify the usefulness of STF to enhance the impact resistance performance. The results showed that STF increases friction within a bundle of fiber, and this phenomena is more apparent in the velocity range of under near 450 m/s. In this research, it is emphasized that FEA analyses of STF impregnated Kevlar fabric laminate were successfully conducted using shell elements. Moreover, the effectiveness of the technique and accuracy were verified through the comparison with reliable experimental data.

• Journal of Plant Biology
• /
• v.11 no.1
• /
• pp.7-14
• /
• 1968

Buckwheat seeds produced in previous year (1965) in an experimental pot culture in which nine levels of P-32 ranging from $1.4{\times}10-4 to 3.3{\times}104$\mu$c/pot(as of 27 July 1965)$, with the same specific activity, had been applied to the corresponding pots respectively, were used this year(1996) in water and soil culture as well as in germination test to investigate the feature and extent of possible residual effects of P-32 incorporated upon germination and plant growth, and the following results were obtained: 1. Under the given experimental conditions both stimulative and inhibitory effects of radiation were observed. 2. The germination rate of the seeds was lower at the higher level of P-32 aplication ranging from $3.0{\times}103 to 3.3{\times}104$\mu$c/pot$ and higher at 0.2 $\mu$c P/pot than the control. 3. Among the seeds produced at the higher level of application about 80% was failed to germinate, owing to the radiation injury. The remaining 80% was failed to germinate, owing to the radiation injury. The remaining 80% survived the damaging effect and showed vigorous growth and increased yield. The latter group of seeds thus proved themselves to be more radioresistant than the former. 4. The survived seeds produced later more straw and root on dry weight basis. The higher the level of P-32 applied, the stronger the stimulative effect showed in vegetative growth. 5. No radiation effect on linear growth of the plants was observed in the soil culture. 6. The dry weight of straw produced showed little difference at the moderate range compared with that of control in the soil culture. At high level of application, i.e. over $\mu$c P32/pot, however, the production was increased by 12-37% of control. 7. As for the dry weight of root harvested, the P-32 treatment over 24$\mu$c P32/pot produced 82-155% more than the control, whereas little difference was observed under 2.2$\mu$c P32/pot. 8. The seed production increased in general by the P-32 treatments. Particularly at the moderate level of application the rate of increase amounted to 70% of the control. 9. Those individual plants which survived damaging effects of radiation at the germinating stage shwoed remarkable stimulative effects both in vegetative and in reproductive stage of growth.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.31 no.1
• /
• pp.41-45
• /
• 2009

Background: Reduced bone height is one of the major problems faced in restoring tooth loss with implants. By the use of short implants, it is possible to reduce complicated and invasive treatment such as bone graft, allowing more simple surgery. But short implants are generally considered to have lower success rates than that of standard implants. Purpose: To assess the results of short Straumann implants by a retrospective study of short Straumann implants with TPS(titanium plasma-sprayed) and SLA(sandblasted, large grit, acid etched) surfaces. Materials and methods: 173 implants in 106 patients who received short Straumann implant surgery(${\le}8\;mm$) in the department of oral and maxillofacial surgery, Kyunghee Dental Hospital, from February 1996 to October 2006 were selected and studied. All of the implants were followed up after prosthetic rehabilitation. The average follow-up period was 34 months with 119 months as the longest follow up period. The average follow-up period after prosthetic rehabilitation was 31 months. 64 females(60.4%) and 42 males(39.6%) participated in the research with the age range of 19 to 85(mean age 47). 20 patients(18.9%) were under 40, 85 patients(80.2%) were over 40 and under 70, and only one patient(0.9%) was over 70 years old. Results: 27 implants(15.6%) had TPS surface while 146 implants(84.4%) had SLA surface. 9 implants(5.2%) were 3.3, 108 implans(62.4%) were 4.1mm and 56 implants(32.4%) were 4.8mm in diameter. 167 implants(96.5%) were 8mm and 6 implants(3.5%) were 6mm in length. There were 24 implants(13.9%) on the maxillas and 149 implants(68.8%) on the mandibles. 119 implants(68.8%) were rehabilitated with FPD(fixed partial denture), 47 implants(27.2%) with single crowns and 4 implants(2.3%) with overdentures. Among the fixed partial dentures, 30 of them were splinted with short implants only. After over an year of follow-up period, 139 implants(96.5%) out of 144 implants showed marginal bone loss of less than 1mm. 3 out of 173 implants failed showing 98.27% survival rate. Conclusions: The use of short Straumann implants(${\le}8mm$) can be a simple and reliable treatment method in minimal residual bone height.

• Earthquakes and Structures
• /
• v.8 no.3
• /
• pp.665-679
• /
• 2015

The strain rate of reinforced concrete (RC) structures stimulated by earthquake action has been generally recognized as in the range from $10^{-4}/s$ to $10^{-1}/s$. Because both concrete and steel reinforcement are rate-sensitive materials, the RC beam-column joints are bound to behave differently under different strain rates. This paper describes an investigation of seismic behavior of RC beam-column joints which are subjected to large cyclic displacements on the beam ends with three loading velocities, i.e., 0.4 mm/s, 4 mm/s and 40 mm/s respectively. The levels of strain rate on the joint core region are correspondingly estimated to be $10^{-5}/s$, $10^{-4}/s$, and $10^{-2}/s$. It is aimed to better understand the effect of strain rates on seismic behavior of beam-column joints, such as the carrying capacity and failure modes as well as the energy dissipation. From the experiments, it is observed that with the increase of loading velocity or strain rate, damage in the joint core region decreases but damage in the plastic hinge regions of adjacent beams increases. The energy absorbed in the hysteresis loops under higher loading velocity is larger than that under quasi-static loading. It is also found that the yielding load of the joint is almost independent of the loading velocity, and there is a marginal increase of the ultimate carrying capacity when the loading velocity is increased for the ranges studied in this work. However, under higher loading velocity the residual carrying capacity after peak load drops more rapidly. Additionally, the axial compression ratio has little effect on the shear carrying capacity of the beam-column joints, but with the increase of loading velocity, the crack width of concrete in the joint zone becomes narrower. The shear carrying capacity of the joint at higher loading velocity is higher than that calculated with the quasi-static method proposed by the design code. When the dynamic strengths of materials, i.e., concrete and reinforcement, are directly substituted into the design model of current code, it tends to be insufficiently safe.

• KSBB Journal
• /
• v.20 no.1 s.90
• /
• pp.26-33
• /
• 2005

The effects of carbon sources for exopolysaccharide production during batch cultivation of an Enterobacter sp. isolated from the composter were investigated. The highest amount of exopolysaccharide was obtained when lactose was used as carbon source. Lactose in medium was converted into glucose and galactose. Glucose was metabolized fast and was completely consumed, but about $20\%$ of lactose was accumulated as galactose. On the other hand, enzyme activity was about $350\~450$ unit with the increase of lactose concentration. Thus, it was considered that the exopolysaccharide might be produced in the course of that lactose was hydrolyzed into glucose and galactose by $\beta-galactosidase$ with respect to that enzyme activity on lactose hydrolysis was accorded to the exopolysaccharide production. When glucose and galactose were added to lactose medium, respectively, it could be considered that glucose was as a repressor and galactose was as a inducer for $\beta-galactosidase$ synthesis even though the mechanisms were not elucidated. The increase of lactose concentration was almost ineffective to the specific growth rate $(0.133\~0.151\;hr^[-1})$ but showed the difference in the biomass content. The higher carbon source concentration, the more residual sugar remained. It was assumed that the optimum lactose concentration for exopolysaccharide production was $30\~70g/L.$ On the other hand, it was considered that the nitrogen acted as growth limiting nutrients to the cell growth. In the cases of 30 and 70 g/L of the fixed carbon concentrations, the increase of the nitrogen sources concentration caused a remarkable increase within the range of $0.059\~0.225\;hr^{-1}$ and $0.141\~0.237hr^{-1}$ of the specific growth rate, respectively, while there was no significant difference in biomass.

• Journal of Environmental Science International
• /
• v.2 no.1
• /
• pp.43-49
• /
• 1993

Concentrations of sulfate and 6-values of sulfate, $({\delta}^{34}SO_4_){pw}$, dissolved In pore waters were measured from the sediment cores of the two different marine environments : deep northeast Pacific (57-1) and coastal Kyunggi Bay of Yellow Sea (57-2) . Sulfate concentration in pore waters decreases with depth at both cores, reflecting sulfate reduction in the sediment columns. However, much higher gradient of pore water sulfate at 57-2 than 57-1 indicates more rapid sulfate reduction at 57-2, because of high sedimentation rate at the coastal area compared to the deep-sea. The measured 6-values, $({\delta}^{34}SO_4_){pw}$, follow extremely well the predicted trend of the Rayleigh fractionation equation. The range of 26.756 to 61.35% at the coastal core 57-2 is not so great as that of 32.4$\textperthousand$ to 97.8$\textperthousand$ at the deep-sea core 57-1. Despite greater graclient of pore water sulfate at 57-2, the 6-values become lower than those of the deep- sea core 57-1. This inverse relation between the 6-values and the gradients of pore water sulfate could be explained by the combination of the two subsequent factors : the kinetic effect by which the residual pore water sulfate becomes progressively enriched with respect to the heavy isotope of $^{34}S$ as sulfate reduction proceeds, and the intrinsic formulation effect of the Rayleigh fractionation equation in which the greater becomes the fractionation factor, the more diminished values of $({\delta}^{34}SO_4_){pw}$ are predicted.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.6
• /
• pp.812-815
• /
• 2009

The effects of processing conditions on the ${\alpha}$-amylase activity of radish were investigated at various temperatures, pHs and drying conditions. The ${\alpha}$-amylase activity of radish root was 3.1-fold higher than that of radish trunk. As the freeze-dried radish was incubated at various temperatures and pHs, ${\alpha}$-amylase activity was stably maintained at pH range of $4{\sim}7$ and temperature of $25{\sim}40^{\circ}C$. When radish was processed to kakdugi and danmooji, the residual ${\alpha}$-amylase activity was 45.39% and 19.19%, respectively. Consequently, the ${\alpha}$-amylase activity was greatly affected by processing conditions such as heat treatment and pH. It is suggested that radish should be processed at below $60^{\circ}C$ and at neutral to acidic pH condition.

• Journal of Biomedical Engineering Research
• /
• v.18 no.3
• /
• pp.291-299
• /
• 1997

As a microimaging device detecting gamma rays emitted from small lesions or tumors during operation, the intraoperative surgical probe has been proposed and is now under development. We have designed a multipurpose portable gamma prove system and evaluated the performance both for the absolute counting purpose of residual radioactivities and for the localizing capability of gamma events using the NaI(Tl) crystal and two types of photomultiplier tubes(PMTs). Counting efficiencies in the range of routine clinical use of radiation dose were measured using the assembly of single channel PMTs and 0.5 inch thick NaI(Tl) crystal of 1 inch diameter. The positioning of gamma events for imaging purpose requires the multiple channel PMTs with appropriate positioning electronics. We have designed a simple and reliable positioning circuit based on the concept of modified Anger. In preliminary experiments using the multiple channel PMT of 3 inch diameter and the dim lighth source, we were able to trace and localize the correct position with reduced positioning error by the use of two multiplier/divider chipset and simplified peripherals. The energy resolutions for the counting gamma probe measured as full width at half maximum(FWHM) for Cs-137, F-18, Tc-99m were 12%, 13%, and 36%, respectively. The spatial resolution for the imaging gamma probe measured as FWHM for green LED was 2.9 mm. The results indicate that the currently developing probe is very promising and could be very useful for many applications in nuclear medicine. Future studies will include developing collimators, improving interface hardwares, and evaluating the system with clinical data.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.11
• /
• pp.834-846
• /
• 2011

The objective of this study is to development of IDFIS system, that are consisted of hydrocyclone, rapid flocculation and inclined settler with chitosan coagulant. As the results of Jar test, a chitosan optimum dosage of 40 mg/L for river sediment, and 5 mg/L for tunnelling wastewater sediment, which these conditions leaves of residual turbidity of less than 5 NTU. Because of the effectiveness of chitosan in removing turbidity was independent on pH, the operation of IDFIS system would be simple. The synthesized turbidity was made with clay particles, river sediment, river suspended sediment, and tunnelling wastewater sediment. Results indicate that the mean overall removal efficiency of turbidity, SS, COD and TP were 98%, 99%, 85% and 95%, respectively. Chitosan is very efficient in removing turbidity in the entire turbidity range examined. IDFIS system would have possibility with compact design, because of the increase of floc size favours the floc settling speed and reduces the settling time.

• Economic and Environmental Geology
• /
• v.25 no.4
• /
• pp.447-461
• /
• 1992

The Jurassic granitoids in the study area are divided into the "Gneissose granodiorite" and the "Daebo granodiorite" (1 : 250,000 Jeonju Geological map, 1973). The term of Geochang granodiorite was used in this study instead of "Daebo granodiorite". These granitoids were studied in terms of microscopic observation, petrochemistry, and zircon morphology. The granitoids are mostly granodiorite. Two kinds of progressive variation can also be recognized in the modal quartz~alkali feldspar~plagioclase triangular diagram; the Gneissose granodiorite is in accordance with the trondhjemitic (low k) trend, and the Geochang granodiorite with the granodioritic trend (medium k). The granitoids belong to the calc-alkaline series, and are classified into the I-type (magnetite series). Plagioclase ($An_{25.1}{\sim}An_{30.9}$) in the granitoids shows generally an oligoclase composition. Biotite has a wider range in (Si, Al) solution than in (Fe, Mg) solid solution. Hornblende occurs in a few thin sections of the Geochang granodiorite, and is plotted in the tschermakite field. The zircon prism shows a long variation between the {110} dominant type and the {100} dominant type in the Geochang granodiorite, but only the {110}={100} type in the Gneissose granodiorite. However, zircon crystals in the granitoids are mostly crystallized in a low-to-medium temperature magma. In the PPEF (Prism- Pyramid-Elongation-Flatness) diagram, the Gneissose granodiorite shows a closed scissors type, the Geochang granodiorite, a opened scissors type. It indicates that the Geochang granodiorite might originate from the mixed magma with crustal materials or pre-existed residual magma which had formed the Gneissose granodiorite.