• The Journal of Engineering Geology
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• v.20 no.2
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• pp.203-212
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• 2010

The aim in this study is used to develop the remediation technologies for contaminated ground water. Slug, single well pumping and step-drawdown tests have been used to obtain hydraulic parameter estimates in the field. Slug tests yield hydraulic conductivity values using the Bouwer and Rice and C-B-P analysis methods. The mean and median hydraulic conductivity values of Bouwer and Rice method are $4.48{\times}10^{-3}$ and $1.16{\times}10^{-3}cm/sec$, respectively. On the other hand, C-B-P method gave mean and median hydraulic conductivity values of $2.37{\times}10^{-3}$ and $7.09{\times}10^{-4}cm/sec$, respectively. These analyses show a trend for the Bouwer and Rice method to yield lower hydraulic conductivity values in low permeability zones of granite in the study area. Sing well pumping test data were calculated through type curve in GW7, GW12 and MW9 wells. It could be interpreted that the differences of hydraulic conductivity and transmissivity values between GW7 and GW12, MW9 is related with fault clays and fractures in the bedrock among the wells. Step-drawdown tests were carried out in the KDPW1 and KDPW2 wells. The hydraulic parameter of KDPW1 and KDPW2 showed very litter difference between the values. The study of hydraulic parameter estimates can be used to purify in contaminated groundwater.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.233-244
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• 2017

We conducted hydraulic fracturing experiments on cement samples to investigate the dependency of fracture propagation on the viscosity of injection fluid and the in situ stress state. Ten cubic samples (20 cm side length) were produced using cement that was cured in water for more than one month. Samples were placed in a tri-axial compression apparatus with three independent principal stresses. An injection hole was drilled and the sample was hydraulically fractured under a constant injection rate. We measured injection pressures and acoustic emissions (AE) during the experiments, and investigated the fracture patterns produced by hydraulic fracturing. Breakdown pressures increased exponentially with increasing viscosity of the injection fluid. Fracture patterns were dependent on differential stress (i.e., the difference between the major and minor principal stresses). At low differential stress, multiple fractures oriented sub-parallel to the major principal stress axis propagated from the injection hole, and in some samples the fracture orientation changed during propagation. However, at high differential stress, a single fracture propagated parallel to the major principal stress axis. AE results show similar patterns. At low differential stress, AE source locations were more widespread than at high differential stress, consistent with the fracture pattern results. Our study suggests that hydraulic fracturing during shale gas extraction should be performed parallel to the orientation of minimum differential stress.

• Clinics in Shoulder and Elbow
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• v.15 no.2
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• pp.117-122
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• 2012

Purpose: To assess the effectiveness of internal fixation using a precontoured locking compression plate for the treatment of the displaced clavicle fracture by analyzing both radiological and clinical outcomes. Materials and Methods: We reviewed 34 cases of displaced clavicle shaft fracture treated by internal fixation using precontoured locking compression plates between May 2009 and February 2010. Radiological outcomes were analized on the basis of bone union and the differences between the time for bone union depending on sex and age. Clinical outcomes were analyzed on the basis of quick DASH Scores and the differences in the range of motion of the affected shoulder compared to the contralateral shoulder. Results: In the radiological evaluation, all fractures showed bone union, and the average time for bone union was 12.3 weeks, without delayed unions. Time for bone union did not differ significantly with respect to sex and age (p=0.87). In the clinical evaluation, the average final quick DASH Score was 23.5 (range, 12~42). At final follow up, the range of motion after bone union in the affected shoulder was not significantly different from that of the contralateral shoulder (p=0.69). Conclusion: The internal fixation achieved using precontoured locking compression plate in displaced clavicle shaft fracture showed effective bone union and can be considered as a reliable method with fine clinical results showing early range of motion at the shoulder joint.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.4
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• pp.296-303
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• 2016

This study was performed to evaluate the effect of hemoglobin (Hb) on bone mineral density (BMD) in university students by performing a quantitative analysis. The subjects included healthy university students aged 20 to 30 years. Although osteoporosis has traditionally been considered as a disease of aging women, it is becoming an increasingly concerning male health problem. Diagnosis of osteoporosis is calculated with a quantitative assessment of BMD. Laboratory blood and urine tests are mainly used with low BMD or fragility fractures to identify any possible causes of bone metabolism disorders. In this study, there was no difference in BMD according to gender. The average red blood cell (RBC), Hb, and Hematocrit (HCT) were significantly higher in males (p<0.01). The correlation between lumbar spine, skeletal muscle mass (SMM), and basal metabolic rate (BMR) was statistically significant (p<0.01). Hb showed a 51.7% statistical influence on BMD by multiple regression analysis. These findings are useful to understand the relationship between BMD and Hb; lower Hb level is associated with lower BMD. The Hb level was the strongest predictor of abnormal BMD. In conclusion, this study showed that a low Hb value was significantly correlated with low bone mass, suggesting that a low Hb value is a risk factor for changes in bone turnover that leads to a decrease bone density.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.638-644
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• 2020

This study examines cracks that occur under the load of an aircraft. The life of aircraft vulnerability structures was analyzed and structural fitting improvements were made. Structural integrity and safety have been achieved through preemptive life expectancy and life management of aircraft structures. The crack size inspection capability of the aircraft under analysis is 0.03inch, compared with 0.032inch, which is the lowest of the three vulnerable parts. In addition, the fatigue life analysis results in approximately 1450 operating hours, the lowest of the three vulnerable parts relative to the aircraft's required life of more than 15000 operating hours, which increased the repeat count of the aircraft's initial and re-inspection times, and hence raised the resulting costs and manpower consumption. Finally, the features were improved through structural fitting of the identified three weak parts. The lowest critical crack size was secured at 0.13 through increased structural resistance to generated cracks and increased aircraft safety. The lowest structural fatigue life for cracks occurring during aircraft operation is 25000 operating hours, which are analyzed above the required structural life, resulting in more optimized improvements than the repair costs and excessive fitting range caused by cracks and fractures.

• Journal of Korean Tunnelling and Underground Space Association
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• v.4 no.4
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• pp.301-317
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• 2002

Recently, a geophysical exploration technology is frequently utilized in the civil engineering field as well as in the resource exploration. It might be important for civil engineers to understand the fundamental theory of seismic survey and limitation of the technique when utilizing these techniques in the civil engineering field. A 3-dimensional migration technique based on the principle of ellipsoid to predict the fractured zone ahead of tunnel face utilizing the tunnel seismic survey was proposed so that the geometry of the fractured zone can be estimated, i.e. the angle between tunnel axis and discontinuity zone, and the dip. Moreover, a numerical analysis technique to simulate the TSP (Tunnel Seismic Prediction) test was proposed in this paper. Based on parametric studies, the best element size, the analysis time step, and the dynamic characteristics of pressure source were suggested to guarantee the stability and accuracy of numerical solution. Example problems on a hypothetical site showed the possibility that the 3-dimensional migration technique proposed in this paper appropriately estimate the 3D-geometry of fractures ahead of tunnel face.

• Journal of Yeungnam Medical Science
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• v.13 no.2
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• pp.261-271
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• 1996

Introduction: Osteoporosis, the most common metabolic bone disorder, is a condition of reduced bone density and increased susceptibility to fractures. Osteoporosis is a major public health problem and a significant cause of morbidity in postmenopausal women. Therefore family physicians as primary care physicians are in a key position for preventing and treating this disorder. So we studied the factors affecting to bone mineral density in postmenopausal women. Materials and Methods: A total of 136 spontaneous postmenopausal women were participated in the study. They have measured spinal bone mineral density by dual energy x-ray absorptiometry from January 1992 to June 1995 at Yeungnam University Hospital. Age, height, weight, age at menarche and menopause, number of child and breast feeding child, history of oral pill ingestion, family history of osteoporosis, amount of milk and coffee ingestion, consumption of tobacco and alcohol and physical activity were assessed by qustionnaire and medical records. Results: The mean age is 55.2 and mean age at menopause is 47.9. Height, weight and physical activity were significantly positive correlated to bone mineral density. But age, duration after menopause and number of child were significantly negative correlated. Also age, height, weight, physical activity and duration after menopause were significantly correlated to % age-matched bone mineral density. In multiple regression analysis, which dependent variable is bone mineral density, duration after menopause, physical activity and weight were significant contributors. Duration after menopause is most the largest contributor. In multiple regression analysis, which dependent variable is % age-matched bone mineral density to adjust the age effect, physical activity and weight were significant contributors. Physical activity is most the largest contributor. Conclusions: Among factors affecting to BMD in postmenopausal women, physical activity and weight were more important factors. Therefore continuous physical activity is significant factor to prevent osteoporosis in postmenopausal women.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.2
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• pp.113-122
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• 2007

In this study, uranium migration experiments have been performed using a natural groundwater and a granite core with natural fractures in a glove-box constructed to simulate an appropriate subsurface environment. Groundwater flow experiments using the non-sorbing anionic tracer Br were carried out to analyze the flow properties of groundwater through the fracture of the granite core. The result of the uranium migration experiment showed a breakthrough curve similar to that of the non-sorting Br. This result may imply that uranium migrates as anionic complexes through the rock fracture since uranium can form carbonate complexes at a given groundwater condition. The distribution coefficient $K_d$ of the uranium between the groundwater and the fracture filling material was obtained as low as 2.7 mL/g from a batch sorption experiment. This result agrees well with the result from the migration experiment, showing a faster elution of the uranium through the rock fracture. In order to analyze retardation properties of the uranium through the rock fracture, the retardation factor $R_d({\sim}16.2)$ was obtained by using the $K_d$ obtained from the batch sorption experiment and it was compared with the $R_d({\sim}14.3)$ obtained by using the result from the uranium migration experiment. The values obtained from the both experiments were very similar to each other. This reveals that the retardation of the uranium is mainly occurred by the fracture filling material when the uranium migrates through the fracture of a granite core.

• Journal of Biomedical Engineering Research
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• v.30 no.2
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• pp.135-141
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• 2009

Purpose: The aim of present study is to evaluate a possibility of clinical application for the effect of low intensity ultrasound stimulation (LIUS) in mechanical characteristics of bone on osteoporotic fractures prevention. Materials and Methods: Eight virgin ICR mice (14 weeks old, approximate weight 25g) were ovariectomized (OVX) to induce osteoporosis. The right hind limbs were then stimulated with LIDS (US Group), whereas left hind limbs were not stimulated (CON Group). Both hind limbs of all mice were scanned by in-vivo micro-CT to acquire two-dimensional (2D) images at 0 week before stimulation and 3 weeks and 6 weeks after stimulation. Three-dimensional (3D) finite element (FE) models generated by scanned 2D images were used to determine quantitatively the effect of LIUS on strength related to bone structure. Additionally, distributions of Hounsfield units and elastic moduli, which are related to the bone quality, for the bones in the US and CON groups were determined to analyze quantitatively a degree of improvement of bone qualities achieved by LIUS. Results: The result of FE analysis showed that the structural strength in US Group was significantly increased over time (p<0.05), while that in CON Group was statistically constant over time (p>0.05). High values of Hounsfield units obtained from voxels on micro-CT images and high values of elastic moduli converted from the Hounsfield units were dominantly appeared in US Group compared with those in CON Group. Conclusion: These finding indicated that LIUS would improve the mechanical characteristics of osteoporotic bone via the effects of bone structure (bone strength) and quality (Hounsfield unit and elastic modulus). Therefore, the LIUS may decrease effectively the risk of osteoporotic fracture in clinics.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.2
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• pp.115-120
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• 2009

Purpose: To evaluate the outcomes of three different surgical approaches in treating a distal radius fracture with dorsal communition. Materials and Methods: From April, 2006 to May, 2009, 49 patients over age of 60years old with unstable dorsal communition distal radius fracture were analyzed. We compared maintainability of reduction by radiological follow-up observations and clinical outcomes using Mayo wrist scores. One-Way ANOVA test was performed to examine the statistical correlation between the methods. Results: All three approaches provided satisfactory post-op reduction results. However, follow-up observations showed significant loss of reduction in the external fixation only group compared to the added bone graft group and the volar anatomical locking plate group (P<0.05). Mayo wrist score was indifferent between the three groups. Conclusion: Treatment of a distal radius fracture with severe dorsal communition using an external fixation only appears to be insufficient in maintaining reduction of a cancellous bone defect.