• The Journal of the Korean bone and joint tumor society
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• v.4 no.1
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• pp.44-52
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• 1998

We treated 19 cases of unicameral bone cysts with methylprednisolone acetate (MPA) from January 1988 to December 1995. We evaluated the effect of MPA injections through simple follow-up radiographs according to Oppenheim's, classification and retrospectively reviewed the sites of cyst, age of the patients at diagnosis, the incidence of pathologic fracture, cystic nature, and cystic proximiy to the growth plate, We then analyzed the relationship between these variables with the results of MPA injections. According to Oppenheim's classification, the results with the use of MPA injections were as follows: healed in six cases, improved in seven cases, incomplete obliteration in five cases and recurred in one case, If healed and improved were considered satisfactory results, then 13 cases(68.4%) were satisfactory at the last follow-up. Sites of cyst, age of the patients at diagnosis, incidence of pathologic fracture, cystic nature and cystic proximiy to the growth plate appeared not to influence the results of MPA injections statistically. On these data, we thought that the treatment of unicameral bone cysts with MPA injection was the most effective first choice of treatment before operative options such as curettage and bone graft.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.2
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• pp.88-100
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• 1998

Since fractures may serve as major conduits of groundwater flow in crystalline rocks, characterization of conductive fractures is especially important for interpretation of flow system. In this study, characterization of fractures to investigate hydraulically conductive fractures in gneisses at an abandoned mine area was performed. The orientation, width, length, movement sense, infilling materials, spacing, aperture, roughness of both joints and faults and intersection and connectivity to other joints were measured on outcrops. In addition, characteristics of subsurface fractures were examined by core logging in five boreholes, of which the orientations were acquired by acoustic televiewer logging from three boreholes. The dominant fracture sets were grouped from outcrops; GSet 1: N50-82$^{\circ}$E/55-90$^{\circ}$SE, GSet 2: N2-8$^{\circ}$E/56-86$^{\circ}$SE, GSet 3: N46-72$^{\circ}$W/60-85$^{\circ}$NE, GSet 4:Nl2-38$^{\circ}$W/15-40$^{\circ}$SW and from subsurface; HSet 1: N50-90$^{\circ}$E/55-90$^{\circ}$SE, HSet 2: N10-30$^{\circ}$E/50-70$^{\circ}$SE, HSet 3: N20-60$^{\circ}$W/50-80$^{\circ}$NE, HSet 4: N10-50$^{\circ}$E/$\leq$40$^{\circ}$NW. Among them, GSet 1, GSet 3 and HSet 1, HSet 3 are the most intensely developed fracture sets in the study area. The mean fracture spacings of HSet 1 are 30-47cm and code 1 fractures, such as faults and open fractures, comprise 21.0-42.9 percent of the whole fractures in each borehole. HSet 3 shows the mean fracture spacings of 55-57cm and the ratio of code 1 fractures is 15.4-26.9 percent. In spite of the mean fracture spacing of 239cm, code 1 fractures of HSet 4 have the highest ratio of 54.5 percent. From the fact that faults or open fractures have high hydraulic conductivity, it can be inferred that the three fracture sets of N55-85$^{\circ}$E/50-80$^{\circ}$SE, N20-60$^{\circ}$W/50-75$^{\circ}$NE and N10-30$^{\circ}$E/$\leq$30$^{\circ}$NW from a fracture system of relatively high conductivity. It is indirectly verified with geophysical loggings and constant injection tests performed in the boreholes.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.1
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• pp.1-9
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• 1998

The attenuation of acoustic emission (AE) waves was evaluated for injection-molded short-fiber-reinforced thermoplastic composites employing simulated AE waves. Values of attenuation coefficient (${\alpha}$) decreased more with increasing fiber volume fraction ($V_f$) than that expected from a simple linear relation between ${\alpha}$ and $V_f$. The effect of wave attenuation was taken into account in a quantitative analysis of the AE peak amplitude distribution which was obtained from each zone partitioned in a specimen gage portion. The amplitude distribution compensated for the measured attenuation loss was exhibited almost similar in every zone of the specimen. Consequently, it was, shown that the AE amplitudes obtained from fiber/plastic composites were considerably affected by the attenuation.

• The Korean Journal of Pain
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• v.31 no.4
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• pp.261-267
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• 2018

Background: To compare the effects of adding two different doses of dexamethasone on the duration and quality of the fascia iliaca block in patients undergoing proximal femoral fracture surgery. Methods: A total of 60 patients (age 18-70 years) undergoing proximal femoral nailing surgery under spinal anesthesia were given fascia iliaca block after random assignment to one of the two groups: Group H received an injection of levobupivacaine (0.5%) 28 ml with 2 ml (8 mg) dexamethasone, and Group L received an injection of levobupivacaine (0.5%) 28 ml with dexamethasone 1 ml (4 mg) with 1 ml normal saline. Assessment of the duration of analgesia and the total tramadol requirement over 48 hours were noted after a successful block. Results: The duration of analgesia was found to be significantly longer in Group H ($17.02{\pm}0.45h$) than in the Group L patients ($14.29{\pm}0.45h$) with a p-value of 0.000. Postoperative analgesic requirement (amount of tramadol in mg) was significantly higher in Group L (Q2: 200.0; IQR: 100.0, 200.0) as compared to Group H (Q2: 100.0; IQR: 100.0, 200.0) with a p-value of 0.034. No patient showed any sign of neurotoxicity. Conclusions: Dexamethasone, in a dose of 8 mg, is superior to 4 mg when used as an adjuvant with levobupivacaine in the FIB. Though both prolonged analgesia and were effective in reducing oral/intravenous analgesics, 8 mg dexamethasone can be recommended as a more efficacious adjuvant to local anesthetics in the FIB.

• Composites Research
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• v.32 no.6
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• pp.360-367
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• 2019

In order to apply thermoplastic composites using PETG resin to various industrial fields such as bicycle frames and industrial parts, it is necessary to verify the impact resistance, durability, mechanical properties and 3D analysis of the manufactured composite materials. To improve the mechanical properties, durability and impact resistance of PETG resin, an amorphous resin, in this study, compound and injection molding process were carried out enhanced various weight percent POE(polyolefin elastomer). The thermal and mechanical properties of the thermoplastic composites, and the charpy impact strength, The analysis was performed to evaluate the characteristics according to weight percent of POE. Charpy impact strength test was conducted to analyze the impact characteristics, and the fracture section was analyzed after the impact strength test. In the case of POE material-added thermoplastic composites, thermal and mechanical properties tend to decrease, but workability and impact resistance tend to be superior to those of PETG materials.

• Journal of Korean Neurosurgical Society
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• v.29 no.3
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• pp.365-371
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• 2000

Objectives : To describe a technique for percutaneous vertebroplasty of osteoporotic vertebral body compression fractures and to report preliminary results of its use. Methods : The technique was used over a 8-month period in 9 patients with 10 painful vertebral fractures. The technique involves percutaneous puncture of the involved vertebrae with a Jamshidi needle via a transpedicular approach followed by injection of polymethylmethacrylate(PMMA) into the vertebral body. Results : The procedure was technically successful in all patients, with an average injection amount of 5.9 cc per vertebral body. One patient complained of flank pain postoperatively in spite of improvement in back pain caused by the fractured vertebra. Remaining eight patients reported significant pain relief early after treatment. The patients were followed up for 3 to 15 months(average 7.2 months) and demonstrated no recurrence of pain or aggravation of deformity. Conclusion : Vertebroplasty appears to be a valuable tool in the treatment of painful osteoporotic vertebral fractures, providing acute pain relief and early mobilization in appropriate patients. However, it needs to have more extensive prospective clinical study to confirm its definitive role in the management of this condition.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.157-171
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• 2019

The fracturing by liquid carbon dioxide ($LCO_2$) as a fracking fluid has been an alternative to mitigate the environmental issues often caused by the conventional hydraulic fracking since it facilitates the fluid permeation owing to its low viscosity. This study presents how $LCO_2$ injection influences the breakdown pressure, acoustic emission, and fracture morphology. Three fracturing fluids such as $LCO_2$, water, and oil are injected with different pressurization rate to the synthetic and porous mortar specimens. Also, the shale which has been a major target formation in conventional fracking practices is also tested to examine the failure characteristics. The results show that $LCO_2$ injection induces more tortuous and undulated fractures, and particularly the larger fractures are developed in cases of shale specimen. On the other hand, the relationship between the fracturing fluids and the breakdown pressure shows opposite tendency in the tests of mortar and shale specimens.

• The Journal of Engineering Geology
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• v.12 no.1
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• pp.35-51
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• 2002

This study aims to establish the methodology for design of an optimum water curtain system of the unlined underground oil storage cavern satisfying the requirements of hydrodynamic performance in a volcanic terrain of the south coastal area. For the optimum water curtain system in the storage facility, the general characteristics of groundwater flow system in the site are quantitatively described, i.e. distribution of hydraulic gradients, groundwater inflow rate into the storage caverns, and hydrogeologic influence area of the cavern. In this study, numerical models such as MODFLOW, FracMan/MAFIC and CONNECTFLOW are used for calculating the hydrogeological stability parameters. The design of a horizontal water curtain system requires considering the distance between water curtain and storage cavern, spacing of the water curtain boreholes, and injection pressure. From the numerical simulations at different scales, the optimum water curtain systems satisfying the containment criteria are obtained. The inflow rates into storage caverns estimated by a continuum model ranged from about 120 m$^3$/day during the operation stage to 130~140m$^3$/day during the construction stage, whereas the inflow rates by a fracture network model are 80~175m$^3$/day. The excavation works in the site will generate the excessive decline of groundwater level in a main fracture zone adjacent to the cavern. Therefore, the vertical water curtain system is necessary for sustaining the safe groundwater level in the fracture zone.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.1
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• pp.42-48
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• 2006

Open reduction and rigid internal fixation is the most popular treatment method for maxillofacial fracture patients, and it is unevitable that postoperative pain can be developed. Many surgeons including oral & maxillofacial surgeons have made constant efforts to decrease postoperative pain. This study is a comparison of postoperative analgesia and intramuscular analgesia in patients with mandibular fractures. In this study, twenty-one patients (Experimental group) were randomly selected and they were injected with IV patient-controlled analgesia (PCA; Walkmed$^{(R)}$, USA). For control group another twenty-one patients were injected with intramusclar non-steroid anti-inflammatory drugs (Rheoma$^{(R)}$, Samsung Pharm. Co.). And then, we measured visual analogue scale (VAS) scores from first postoperative day to second day at regular time interval. The following results were uptained; 1. In patient group who with open reduction and rigid internal fixation, there was significant difference of postoperative analgesic effect during the first postoperative day(p<0.05). 2. In patient group with over 90 minutes surgery time, there was significant difference of postoperative analgesic effect during the first and second postoperative day when compared between experimental group and control group(p<0.05). 3. In patient group with less than 90 minutes surgery time, there was no significant difference of postoperative analgesic effect during the first and second postoperative day when compared between experimental group and control group(p>0.05). 4. In patient group with surgery of open reduction using rigid internal fixation at single fractured site, there was no significant difference of postoperative analgesic effect during the first and second postoperative day when compared between experimental group and control group(p>0.05). 5. In patient group with surgery at two fractured sites, there was significant difference of postoperative analgesic effect during the first postoperative day when compared between experimental group and control group(p<0.05). As mentioned above, it suggest that patient-controlled analgesia is more effective for postoperative pain relief than intramuscular injection in patients with rigid internal fixation by open reduction after mandibular fracture occurred. Especially, it is considered that in patient with more than 90 minutes surgery time or in cases with multiple fractured sites had more effective results with PCA therapy than conventional intramuscular analgesics.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.3
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• pp.229-243
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• 2013

An in situ solute migration system was designed and installed in KAERI Underground Research Tunnel (KURT) constructed in the site of Korea Atomic Energy Research Institute (KAERI) in order to investigate the migration and retardation of non-sorbing and sorbing tracers through a rock fracture. The system is composed of three main parts including injection, extraction, and data treatment. For the selection of a water-conducting fracture, boreholes were drilled. The fractures in the drilled boreholes were investigated using borehole image analysis using borehole image processing system (BIPS). The results of BIPS analysis showed that borehole YH 3-1 and YH 3-2 were connected each other. Moreover, hydraulic tests were carried out to determine the test section with connectivity for the in situ experiments. The in situ solute migration experiments were accomplished to understand the migration of solutes through fractures in KURT using non-sorbing tracers which were fluorescein sodium, eosin-B, bromide and sorbing tracers which were rubidium, nickel, zirconium, and samarium.