• Proceedings of the KOSOMBE Conference
• /
• v.1998 no.11
• /
• pp.281-282
• /
• 1998

Recently, there has been growing interest in the assessment of physiological parameters on brain perfusion that provide more information than pure morphologic diagnosis. Quantification of parameters that characterize cerebral micro-circulation with magnetic resonance imaging is of great relevance for clinical application. We determine the local tissue concentration by exponential relationship between the relative signal reduction S(t)/$S_0$ and local tissue concentration of contrast material $C_m(t)$ in dynamic susceptibility contrast enhanced MR imaging. And then we made relative regional blood volume map by calculating the area under the measured concentration-time curves $C_m(t)$ during first pass of paramagnetic contrast material as a preliminary step for perfusion map. These images make it possible to compare the rCBV in different brain regions in one individual at a time. We have it in contemplation to obtain arterial and brain signal time curves simultaneously to make absolute rCBV and perfusion (rCBF) map. These maps may provide the method of comparative investigations of different patients having strong variation in AIF.

• Applied Biological Chemistry
• /
• v.40 no.6
• /
• pp.531-535
• /
• 1997

An efficient process for recovery of calcium from the eggshell was developed and some organic acids were used in an attempt to enhance the degree of calcium ionization. Eggshell membrane was readily separated from crushed eggshell based on the differences in specific gravities. The conditions which allowed most efficient membrane removal were found to be 30 rpm of speed, 30 min of residence time and 0.08 of volume fraction. It took 3 hours for the eggshell powder prepared at $1000^{\circ}C$ to reach L value of 90 with the Hausner ratio being 1.43. The calcium ion concentrations were 990, 3500, 3900 and 4200 ppm in pure water, acetic acid, citric acid and lactic acid$(0.05{\sim}3%)$ aqueous solution, respectively. The degrees of ionization of calcium-citrate-malate complex(CCM), calcium-citric acid complex(CC) and calcium malic acid complex(CM) increased by 4 to 5 times compared to eggshell calcium powder.

• Applied Microscopy
• /
• v.26 no.1
• /
• pp.95-104
• /
• 1996

A comprehensive methodology to characterize the interfacial reaction products of $SiC_p/2024$ Al composites is introduced on the basis of the experimental results obtained using XRD, SEM and TEM. XRD performed on the electrochemically extracted $SiC_p$ and bulk $SiC_p/2024$ Al composite have shown that the interfacial reaction products consist of $Al_{4}C_3$ having hexagonal crystallographic structure, pure eutectic Si having diamond cubic crystallographic structure, and $CuAl_2$, having tetragonal crystalloraphic structure, respectively. According to the images observed by SEM, $Al_{4}C_3$, which has been reported to have needle shape, has a hexagonal platelet-shape and eutectic Si is found to have a dendritic shape. In addition eutectic $CuAl_2$, was observed to form near interface and/or along the grain boundaries. In order to confirm the results obtained by XRD, the primitive cell volume and reciprocal lattice height of such interfacial reaction products were calculated using the data obtained from convergent beam electron diffraction (CBED) patterns, and then compared with theoretical values.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.20 no.4
• /
• pp.528-535
• /
• 2017

Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.

• Neonatal Medicine
• /
• v.25 no.4
• /
• pp.186-190
• /
• 2018

Esophageal atresia (EA) with proximal tracheoesophageal fistula (TEF; gross type B) is a rare defect. Although most patients have long-gap EA, there are still no established surgical guidelines. A premature male infant with symmetric intrauterine growth retardation (birth weight, 1,616 g) was born at 35 weeks and 5 days of gestation. The initial diagnosis was pure EA (gross type A) based on failure to pass an orogastric tube and the absence of stomach gas. A "feed and grow" approach was implemented, with gastrostomy performed on postnatal day 2. A fistula was detected during bronchoscopy for recurrent pneumonia; thus, we confirmed type B EA and performed TEF excision and cervical end esophagostomy. As the infant's stomach volume was insufficient for bolus feeding after reaching a body weight of 2.5 kg, continuous tube feeding was provided through a gastrojejunal tube. On the basis of these findings, esophageal reconstruction with gastric pull-up was performed on postnatal day 141 (infant weight, 4.7 kg), and he was discharged 21 days postoperatively. At 12 months after birth, there was no catch-up growth; however, he is currently receiving a baby food diet without any complications. In patients with EA, bronchoscopy is useful for confirming TEF, whereas for those with long-gap EA with a small stomach volume, esophageal reconstruction with gastric pull-up after continuous feeding through a gastrojejunal tube is worth considering.

• The Journal of Advanced Prosthodontics
• /
• v.12 no.6
• /
• pp.369-375
• /
• 2020

PURPOSE. This study evaluated the availability of multi-directionally forged (MDF) titanium (Ti) as a component of removable partial dentures (RPDs). MDF-Ti remarkably improved the mechanical properties of RPDs due to its ultrafine-grained structure. MATERIALS AND METHODS. The wear resistance, plaque adhesion, and machinability of MDF-Ti were tested. As controls, commercially pure (CP) titanium was used for wear, plaque adhesion, and machinability tests. For wear resistance, the volume losses of the titanium teeth before and after wear tests were evaluated. Plaque adhesion was evaluated by the assay of Streptococcus mutans. In the machinability test, samples were cut and ground by a steel fissure bur and carborundum (SiC) point. An unpaired t-test was employed for the analysis of the significant differences between MDF-Ti and the control in the results for each test. RESULTS. Wear resistance and plaque adherence of MDF-Ti similar to those of CP-Ti (P>.05) were indicated. MDF-Ti exhibited significantly larger volume loss than CP-Ti in all conditions except 100/30,000 g/rpm in machinability tests (P<.05). CONCLUSION. Although the wear resistance and plaque adherence of MDF-Ti were comparable to those of controls, MDF-Ti showed better machinability than did CP-Ti. MDF-Ti could be used as a framework material for RPDs.

• Computers and Concrete
• /
• v.29 no.6
• /
• pp.375-391
• /
• 2022

This paper examined the impact of the cross-sectional structure on the structural results under different loading conditions of reinforced concrete (RC) members' management limited in Carbon Fiber Reinforced Polymers (CFRP). The mechanical properties of CFRC was investigated, then, totally 32 samples were examined. Test parameters included the cross-sectional shape as square, rectangular and circular with two various aspect rates and loading statues. The loading involved concentrated loading, eccentric loading with a ratio of 0.46 to 0.6 and pure bending. The results of the test revealed that the CFRP increased ductility and load during concentrated processing. A cross sectional shape from 23 to 44 percent was increased in load capacity and from 250 to 350 percent increase in axial deformation in rectangular and circular sections respectively, affecting greatly the accomplishment of load capacity and ductility of the concentrated members. Two Artificial Intelligence Models as Extreme Learning Machine (ELM) and Particle Swarm Optimization (PSO) were used to estimating the tensile and flexural strength of specimen. On the basis of the performance from RMSE and RSQR, C-Shape CFRC was greater tensile and flexural strength than any other FRP composite design. Because of the mechanical anchorage into the matrix, C-shaped CFRCC was noted to have greater fiber-matrix interfacial adhesive strength. However, with the increase of the aspect ratio and fiber volume fraction, the compressive strength of CFRCC was reduced. This possibly was due to the fact that during the blending of each fiber, the volume of air input was increased. In addition, by adding silica fumed to composites, the tensile and flexural strength of CFRCC is greatly improved.

• Nuclear Engineering and Technology
• /
• v.7 no.3
• /
• pp.213-222
• /
• 1975

Immobilization of the second-cycle radioactive liquid wastes from a Purex process was developed with the blown asphalt (manufactured by Kukdong Shell Oil Company Ltd) to eliminate the possibility that the radioactive materials will be redispersed into the environment. Attempts to incorporate these wastes directly into the asphalt martrices without any pretreatment were not successful, as it was observed that the sulphuric acid in the waste oxidised the asphalt. Hence, the waste was treated with caustic soda and made alkaline prior to bituminization, so that it was found that this pretreatment made the waste compatible to the asphalt matrices. The pure blown asphalt samples irradiated with doses of 4.0$\times$10$^{7}$ rad showed no evidence of volume increase. The suitable temperature for incorporation of the alkaline wastes into blown asphalt was 180-20$0^{\circ}C$. The Products containing 50 wt% salts represented the following good properties viz., volume reduction (about 1.4), homogeneity, teachability etc. During the period of 131 day $s^{l37}$Cs from products containing 40wt% salts was leached at rates ranging from 2.70$\times$10-4 to 8.27$\times$10-4g/cm2_day but the rate for $^{90}$ Sr was lower by one to two orders of magnitude by distilled water. The leaching rates for $^{137}$ Cs and $^{90}$ Sr by sea water were slightly lower than by distilled water. Both of the leaching rates decreased with increasing pH.H.

• Archives of Craniofacial Surgery
• /
• v.25 no.4
• /
• pp.161-170
• /
• 2024

Background: The eyes are the central aesthetic unit of the face. Maxillofacial trauma can alter facial proportions and affect visual function with varying degrees of severity. Conventional approaches to reconstruction have numerous limitations, making the process challenging. The primary objective of this study was to evaluate the application of three-dimensional (3D) navigation in complex unilateral orbital reconstruction. Methods: A prospective cohort study was conducted over 19 months (January 2020 to July 2021), with consecutive enrollment of 12 patients who met the inclusion criteria. Each patient was followed for a minimum period of 6 months. The principal investigator carried out a comparative analysis of several factors, including fracture morphology, orbital volume, globe projection, diplopia, facial morphic changes, lid retraction, and infraorbital nerve hypoesthesia. Results: Nine patients had impure orbital fractures, while the remainder had pure fractures. The median orbital volume on the normal side (30.12 cm³; interquartile range [IQR], 28.45-30.64) was comparable to that of the reconstructed orbit (29.67 cm³; IQR, 27.92-31.52). Diplopia improved significantly (T(10)= 2.667, p= 0.02), although there was no statistically significant improvement in globe projection. Gross symmetry of facial landmarks was achieved, with comparable facial width-to-height ratio and palpebral fissure lengths. Two patients reported infraorbital hypoesthesia at presentation, which persisted at the 6-month follow-up. Additionally, five patients developed lower lid retraction (1-2 mm), and one experienced implant impingement at the infraorbital border. Conclusion: Our study provides level II evidence supporting the use of 3D navigation to improve surgical outcomes in complex orbital reconstruction.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2004.09a
• /
• pp.201-209
• /
• 2004

As the European Community's Directive on the Restriction of Hazardous Substances in Electrical and Electronic Equipment banning lead (Pb) in electronics products will take effect on July 1, 2006, most electronics manufacturers will be commencing with volume production of Pb-free components by the middle of 2004. Electrodeposited pure tin finishes on electronic components are a leading contender to replace the industry standard tin-lead. Commensurate with this shift will be a somewhat steep learning curve as manufacturers adapt a variety of equipment and processes to contend with the issues surrounding this critical, industry-wide material conversion. Since the electrodeposited finish directly influences the critical reliability characteristics of the component itself, the nature of the Pb-free component finish must be well characterized and understood. Only through a thorough examination of the attributes of the electroplated tin deposit can critical decisions be made regarding component finish reliability. This paper investigates the properties of electrodeposited tin that may have an effect on component reliability, namely, grain structure (size and shape), oxide formation, tin whisker formation, and solderability. Data will be presented from laboratory and production settings, with the objective being to enable manufacturers to draw their own conclusions regarding previously established perceptions and misconceptions about electrodeposited tin properties.