• The Journal of Engineering Geology
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• v.19 no.4
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• pp.433-439
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• 2009

The compressed packer device is designed to improve the underground contamination prevention facilities of ground water wells. As for the device, the installation is simple because of the safety lock device and the compression of the casing are simple the installation is simple. There is no leakage of ground water because the pressure resistance with $4.5\;kg/cm^2$ makes it equipped with the watertightness The single casing is installed and the reaming for grouting is possible with 300 mm excavation so that installation cost can be saved. Silicon rubber is used for the compressed packer so that the extension rate is 590%. In terms of environmental pollution, it is an environmental friendly product which does not contain harmful ingredients such as Pb, Cd, and phenol. below the standard or undetectable level Furthermore, the installation costs are 35 to 62% or lower than the conventional grouting construction method and are 87% or lower than the expansion packer construction method, the new environmental technology No.47 Also, the device is designed to meet the relevant regulations such as Rules on Preserving the Ground Water Quality, The Standard on Jeju Island Ground Water Development and Facility Installation and Management, and The Plan and Guideline on Operating and Managing the Small-Scale Tap Water Facilities of Ministry of Environment and Ministry of Food, Agriculture, Forestry and Fisheries.

• Elastomers and Composites
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• v.46 no.4
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• pp.284-289
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• 2011

Prismatic reflective sheets were prepared using microprisms, and their retroreflection and structural properties were investigated and compared with encapsulated lens type reflective sheets based on glass beads. As prepared, the prismatic reflective sheets show well arranged array of microprisms. The arrangement of glass beads in encapsulated lens type reflective sheets is also found to be uniform without any cracks. However, during the coating process of the PET layer, the beads are coming out and the gaps are formed due to the application of high pressure. Even though the preparation method for reflective sheets based on microprisms is similar to that of reflective sheets based on glass beads, the method is relatively simple and cost effective, and also needs less time. Prismatic reflective sheets show higher coefficient of retroreflection from all entrance angles compared to reflective sheets based on glass beads. The results prove that the prismatic reflective sheets can be used for preparing the traffic sign boards to secure a clear view.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.4
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• pp.303-308
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• 2010

Excessive oral and maxillofacial bleeding causes upper airway obstruction, bronchotracheal and gastric aspiration and hypovolemic shock. Therefore, the rapid and correct bleeding control is very important for saving lives in the emergency room. Despite the conventional bleeding control methods of wiring (jaw fracture, wound suture and direct pressure), continuous bleeding can occur due to the presence of various bleeding disorders. There are five main causes for excessive bleeding disorders in the clinical phase; (1) vascular wall alteration (infection, scurvy etc.), (2) disorders of platelet function (3) thrombocytopenic purpura (4) inherited disorders of coagulation, and (5) acquired disorders of coagulation (liver disease, anticoagulant drug etc.). In particular, infections can alter the structure and function of the vascular wall to a point at which the patient may have a clinical bleeding problem due to vessel engorgement and erosion. Wound infection is a frequent cause of postoperative active bleeding. To prevent postoperative bleeding, early infection control using a wound suture with proper drainage establishment is very important, particularly in the active bleeding sites in a contaminated emergency room. This is a case report of a rational bleeding control method by rapid wiring, wound suture with drainage of a rubber strip & iodoform gauze and wet gauze packing, in a 26-year-old male cerebral palsy patient with active oral and maxillofacial bleeding injuries caused by a traffic accident.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.47-67
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• 1996

The purpose of this study was to observe the effect of $Biocoral^R$ graft and bioglass 45S5 graft in combination with ePTFE membrane in periodontal osseous defects for new bone formation. Nine healthy dogs were used. Under general anesthesia, 3-wall defects were created on the mesial and distal surfaces of the maxillary right canines, the mesials of the maxillary right second premolars, the distals of the mandibular right canines and the mesials of the mandibular right third premolars. To induce periodontitis, a silicone rubber, $Provil^R$ light body, was injected under pressure into the defects. Ninety days later, $Provil^R$was removed and followed by thorough root planing. The followings were then applied in the mesial and distal defects of the maxillary right canines, the mesials of the maxillary right second premolars, the distals of the mandibular right canines and the mesials of the mandibular right third premolars by random selections : 1) ePTFE membrane only application, 2) $Biocoral^R$ graft, 3) $Biocoral^R$ graft and ePTFE membrane application, 4)Bioglass 45S5 graft, 5) Bioglass 45S5 graft and ePTFE membrane application. The membranes were removed 1 month later. The dogs were sacrified at 1, 2 and 3 months following the graft, and block sections were made, demineralized, embedded, stained and examined by light microscope and transmission electron microscope. On the sections from teeth treated with ePTFE membrane only, the defect demonstrated extensive connnective tissue and alveolar bone regeneration. The $Biocoral^R$ graft group demonstrated extensive bone regeneration compared with ePTFE membrane only group. In the $Biocoral^R$ graft plus ePTFE membrane group, regeneration of new alveolus and crest occurred within the defect. As the experimental period lengthened, bone regeneration was increased and bone bridge was formed among the graft particles. The but bioglass 45S5 graft group demonstrated extensive bone regeneration but the amount of new bone was less than that of the $Biocoral^R$ graft group. For the bioglass 45S5 graft plus ePTFE membrane group, the amount of new bone was also increased. As the experimental period lengthened, bone regeneration was increased. Multinucleated giant cells, fibroblasts and macrophages were observed. As the bone formation was increased, the number of such cells was decreased. In conclusion, the $Biocoral^R$ was found better than the bioglass 45S5 for new bone formation, and the use of ePTFE membrane alone or with $Biocoral^R$/bioglass 45S5 can be supported as potential methods of promoting bone formation.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.331-338
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• 2008

A new ground water sampler was developed and evaluated for target depth sampling under most rigorous field conditions. This new concept sampler comprises an air-cylinder, a hypodermic needle and a sampling bottle. Pressurized air or nitrogen gas can be used as a mechanical power source to operate the sampler. The air-cylinder is used to jab the hypodermic needle into the rubber cap of the sampling bottle. The hypodermic needle functions as a pathway to inject groundwater into the sampling bottle. Field test was conducted in a seawater intrusion monitoring well located at Handong district of Jeju Island. Water qualities in this well are periodically changed from the effects of sea water. Water sampling fir the same target depth in this well were tried at various times, and variations in electrical conductivity and pressure at the inside and outside of the sampler were measured using CTD divers. We found that the device could collect water samples only when it was actuated, and the pattern and range of variations in electrical conductivities and pressures measured at the inside and outside of the sampler were nearly identical. These results indicate that water samples using the sampler presented in this study represent correctly water qualities in which the samplings were made at a specific target depth in a well.

• Elastomers and Composites
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• v.41 no.2
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• pp.116-124
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• 2006

Cloud-point data to $160^{\circ}C$ and 1,000 bar are presented with poly(ethylene-co-15.3 mole% octene) copolymers ($PEO_{15}$) in pure 1-octene and mixtures of ethylene - 1-octene. The cloud-point curves for $PEO_{15}$ - ethylene - 1-octene mixture dramatically increase in pressure to as high as 1,000 bar with an increasing ethylene concentration. At ethylene concentrations less than 18 wt%, the ternary mixture has bubble- and cloud-point curves. As the ethylene concentration of the ternary mixture increases, the bubble-point curve and the single-phase region reduce. The reduction in the single phase region with increasing ethylene concentrations is the result of reduced dispersion interactions between $PEO_{15}$ and the mixed solvent. The single-phase region decreases with increasing temperatures when ethylene concentrations are lower than 36 wt%, whereas the single-phase region increases with temperatures at ethylene concentrations greater than 50 wt%. At ethylene concentrations greater than 50 wt% the effect of the polar interactions of the mixed solvent, which is unfavorable to dissolve PEO, is greater than the effect of the density of the mixed solvent. Therefore, the cloud-point pressures increase with a decreasing temperature. However, at ethylene concentrations less than 50 wt%, the cloud-point pressures decrease with temperature, because the effect of the polar interactions is less than the density effect.

• Elastomers and Composites
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• v.40 no.4
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• pp.277-283
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• 2005

LV transition curves for poly(ethylene-co-15.3 mol% octene) ($PEO_{15}$) and poly(ethylene- co-17.0 mol% octene) ($PEO_{17}$) were measured in cyclo-pentane and cyclo-hexane. Between $40{\sim}150^{\circ}C$, the LV curve for ($PEO_{15}$ + cyclo pentane) located $1.1{\sim}2.7$ bar higher than that for ($PEO_{17}$+ cyclo-pentane). In cyclo-hexane, similar behavior was observed for $PEO_{15}$ and $PEO_{17}$ solution except the pressure difference reduced to $0.9{\sim}l.6$ bar. If the backbone structure of $PEO_{15}$ were identical to that of $PEO_{17}$, the LV line for $PEO_{17}$ would locate at high pressures than that for $PEO_{15}$, since the number average molecular weight of $PEO_{17}$ (Ave. Mn=153,040) is 1.9 times higher 4han that of $PEO_{15}$ (Ave. Mn=82,200). The difference in the octene comonomer content between $PEO_{15}$ and $PEO_{17}$ is only 1.7 mole%, nevertheless this small difference in the backbone structure of the PEO greatly affected the location of the L-V curves in the mixtures comprised of PEO and cyclo-alkane.

• The Journal of the Acoustical Society of Korea
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• v.42 no.6
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• pp.565-571
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• 2023

With the introduction of the post-verification system, the measurement of floor impact noise performance on-site has become mandatory, and the evaluation method has changed. To track the performance changes since the policy implementation, research is needed on how the characteristics of heavyweight impact sound change according to the varied evaluation method. In this study, we analyzed the contribution rate of the frequency band-specific sound pressure level on the single-number quantity for a multi-family housing unit with the same floor plan and floor structure, comprising 59 households, based on the changed impact sources and evaluation indicators. It is difficult to compare simply because the method of calculating contributions by frequency band according to the single-day evaluation is different, but the average contribution rate of 63 Hz was 80.8 % in the evaluation method before the introduction of the post-confirmation system (Tire measurement and evaluated as L'_i,Fmax,AW), and the average contribution rate of 125 Hz was 19.2 %. The current evaluation method (rubber ball measurement and evaluation as L'_iA,Fmax) shows that the contribution rate has decreased to 33.1 % on average at 50 Hz ~ 80 Hz, 58.7 % on average at 100 Hz ~ 160 Hz, 6.9 % on average at 200 Hz ~ 315 Hz, and 1.3 % on average at 400 Hz ~ 630 Hz. This result is a case analysis for the target apartment house, and it is necessary to analyze measurement data for more diverse apartment houses.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.4
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• pp.287-293
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• 2010

Purpose: This study evaluated the effect of polishing techniques on surface roughness of polymethyl methacrylate (PMMA), as well as the influence of light-cured surface glaze and subsequent brushing on surface roughness. Materials and methods: A total of 60 PMMA specimens ($10{\times}10{\times}5\;mm$) were made and then divided into 6 groups of 10 each according to the polymerization methods (under pressure or atmosphere) and the surface polishing methods (mechanical or chemical polishing) including 2 control groups. The mechanical polishing was performed with the carbide denture bur, rubber points and then pumice and lathe wheel. The chemical polishing was performed by applying a light-cured surface glaze ($Plaquit^{(R)}$; Dreve-Dentamid GmbH). Accura $2000^{(R)}$, a non-contact, non-destructive, optical 3-dimensional surface analysis system, was used to measure the surface roughness (Ra) and 3-dimensional images were acquired. The surface roughness was again measured after ultrasonic tooth brushing in order to evaluate the influence of brushing on the surface roughness. The statistical analysis was performed with Mann-Whitney test and t-test using a 95% level of confidence. Results: The chemically polished group showed a statistically lower mean surface roughness in comparison to the mechanically polished group (P = .0045) and the specimens polymerized under the atmospheric pressure presented a more significant difference (P = .0138). After brushing, all of the groups, except the mechanically polished group, presented rougher surfaces and showed no statistically significant differences between groups. Conclusion: Although the surface roughness increased after brushing, the chemical polishing technique presented an improved surface condition in comparison to the mechanical polishing technique.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.27-47
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• 1992

Engineers have developed new instruments that aid in diagnosis and therapy Ultrasonic imaging has provided a nondamaging method of imaging internal organs. A complex transducer emits ultrasonic waves at many angles and reconstructs a map of internal anatomy and also velocities of blood in vessels. Fast computed tomography permits reconstruction of the 3-dimensional anatomy and perfusion of the heart at 20-Hz rates. Positron emission tomography uses certain isotopes that produce positrons that react with electrons to simultaneously emit two gamma rays in opposite directions. It locates the region of origin by using a ring of discrete scintillation detectors, each in electronic coincidence with an opposing detector. In magnetic resonance imaging, the patient is placed in a very strong magnetic field. The precessing of the hydrogen atoms is perturbed by an interrogating field to yield two-dimensional images of soft tissue having exceptional clarity. As an alternative to radiology image processing, film archiving, and retrieval, picture archiving and communication systems (PACS) are being implemented. Images from computed radiography, magnetic resonance imaging (MRI), nuclear medicine, and ultrasound are digitized, transmitted, and stored in computers for retrieval at distributed work stations. In electrical impedance tomography, electrodes are placed around the thorax. 50-kHz current is injected between two electrodes and voltages are measured on all other electrodes. A computer processes the data to yield an image of the resistivity of a 2-dimensional slice of the thorax. During fetal monitoring, a corkscrew electrode is screwed into the fetal scalp to measure the fetal electrocardiogram. Correlations with uterine contractions yield information on the status of the fetus during delivery To measure cardiac output by thermodilution, cold saline is injected into the right atrium. A thermistor in the right pulmonary artery yields temperature measurements, from which we can calculate cardiac output. In impedance cardiography, we measure the changes in electrical impedance as the heart ejects blood into the arteries. Motion artifacts are large, so signal averaging is useful during monitoring. An intraarterial blood gas monitoring system permits monitoring in real time. Light is sent down optical fibers inserted into the radial artery, where it is absorbed by dyes, which reemit the light at a different wavelength. The emitted light travels up optical fibers where an external instrument determines O2, CO2, and pH. Therapeutic devices include the electrosurgical unit. A high-frequency electric arc is drawn between the knife and the tissue. The arc cuts and the heat coagulates, thus preventing blood loss. Hyperthermia has demonstrated antitumor effects in patients in whom all conventional modes of therapy have failed. Methods of raising tumor temperature include focused ultrasound, radio-frequency power through needles, or microwaves. When the heart stops pumping, we use the defibrillator to restore normal pumping. A brief, high-current pulse through the heart synchronizes all cardiac fibers to restore normal rhythm. When the cardiac rhythm is too slow, we implant the cardiac pacemaker. An electrode within the heart stimulates the cardiac muscle to contract at the normal rate. When the cardiac valves are narrowed or leak, we implant an artificial valve. Silicone rubber and Teflon are used for biocompatibility. Artificial hearts powered by pneumatic hoses have been implanted in humans. However, the quality of life gradually degrades, and death ensues. When kidney stones develop, lithotripsy is used. A spark creates a pressure wave, which is focused on the stone and fragments it. The pieces pass out normally. When kidneys fail, the blood is cleansed during hemodialysis. Urea passes through a porous membrane to a dialysate bath to lower its concentration in the blood. The blind are able to read by scanning the Optacon with their fingertips. A camera scans letters and converts them to an array of vibrating pins. The deaf are able to hear using a cochlear implant. A microphone detects sound and divides it into frequency bands. 22 electrodes within the cochlea stimulate the acoustic the acoustic nerve to provide sound patterns. For those who have lost muscle function in the limbs, researchers are implanting electrodes to stimulate the muscle. Sensors in the legs and arms feed back signals to a computer that coordinates the stimulators to provide limb motion. For those with high spinal cord injury, a puff and sip switch can control a computer and permit the disabled person operate the computer and communicate with the outside world.