• Journal of Life Science
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• v.25 no.5
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• pp.533-538
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• 2015

Four sites and one site were used to analyze fish diversity at the water systems of the Sineun reservoir and the Jeonchon reservoir, respectively. The field experiments were conducted to test the density dependence that could lead to population regulation by artificial inferences and environmental changes. We examined the effects of environmental factors on fish densities using SMATR freeware. It was estimated to be reduced to the density effect at four sites in 2012. Shannon-Weaver indices of the diversity (H’) of the Sineun reservoir were similar to those of the Jeonchon reservoir. Species diversity was in a range of 0.645 to 2.105. The H’ value of the upper region was higher than those of middle and low regions were, and values of richness were lower in downstream than upstream. Using the maximum likelihood solution for the removal estimators of two low regions of the river stations, the estimated migration probabilities from the resident fish to the migrated fish for five species (Cyprinus cuvieri, Carassius auratus, Pseudorasbora parva, Misgurnus mizolepis, and Oryzias latipes) had a mean of 0.623. Especially, migration probabilities from the Jeonchon reservoir to the Sineun reservoir for five species were high (a mean of 0.681). The period of migration was suggested to be about one month because of short geographical distances (50 m). We found no significant difference between the three categories in the distribution of the other four species, indicating the species probability was similar among stations.

• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.52-61
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• 2019

On 30 June, 2017, the Ministry of Land, Infrastructure, and Transport announced the minimum size of parking section will be expanded in parking lots. The expansion of parking section could lead to increase in apartment prices because of increase in total area of the parking lots. It is necessary to adjust the column spacing and number in the parking lots and to apply the 8-Bay long-span parking module with good parking efficiency. According to the study, the construction cost of the 6-Bay module and 8-Bay module was almost the same. But The 8-Bay module was more economical than the 6-Bay module because of the reduction in total area of 8-Bay multi-moduel. The Result of construction cost of 8-Bay modules, Removal Deck-plate RC system was most economical. While the construction cost of PC system was higher due to increase in volume of the member, it would ensure sufficient economy by reducing the girder height to apply a pre-stress method. Also, the construction cost of hollow slab system was the highest. But it could be used as the underground parking lots for apartment, because it had the lowest cost per square meter. This Study has a academic significance by proving the applicability of the 8-Bay Module to underground parking lot of apartment. And it is expected that this study will be used as basic data to derive optimal construction method that applies 8-Bay Module.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.575-584
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• 2021

Objective : Cervical expansive laminoplasty is an effective surgical method to address multilevel cervical spinal stenosis. During surgery, the spinous processes of C2 and C7 are usually preserved to keep the insertion points of the cervical musculature and nuchal ligament intact. In this regard, dome-like laminectomy (undercutting of C7 lamina) instead of laminoplasty is performed on C7 in selected cases. However, resection of the lamina can weaken the C7 lamina, and stress fractures may occur, but this complication has not been characterized in the literature. The objective of the present study was to investigate the incidence and risk factors for C7 laminar fracture after C7 dome-like laminectomy and its impact on clinical and radiological outcomes. Methods : Patients who underwent cervical open-door laminoplasty combined with C7 dome-like laminectomy (n=123) were classified according to the presence of C7 laminar fracture. Clinical parameters (neck/arm pain score and neck disability index) and radiologic parameters (C2-7 angle, C2-7 sagittal vertical axis, and C7-T1 angle) were compared between the groups preoperatively and at postoperatively at 3, 6, 12, and 24 months. Risk factors for complications were evaluated, and a formula estimating C7 fracture risk was suggested. Results : C7 lamina fracture occurred in 32/123 (26%) patients and occurred at the bilateral isthmus in 29 patients and at the spinolaminar junction in three patients. All fractures appeared on X-ray within 3 months postoperatively, but patients did not present any neurological deterioration. The fracture spontaneously healed in 27/32 (84%) patients at 1 year and in 29/32 (91%) at 2 years. During follow-up, clinical outcomes were not significantly different between the groups. However, patients with C7 fractures showed a more lordotic C2-7 angle and kyphotic C7-T1 angle than patients without C7 fractures. C7 fracture was significantly associated with the extent of bone removal. By incorporating significant factors, the probability of C7 laminar fracture could be assessed with the formula 'Risk score = 1.08 × depth (%) + 1.03 × length (%, of the posterior height of C7 vertebral body)', and a cut-off value of 167.9% demonstrated a sensitivity of 90.3% and a specificity of 65.1% (area under the curve, 0.81). Conclusion : C7 laminar fracture can occur after C7 dome-like laminectomy when a substantial amount of lamina is resected. Although C7 fractures may not cause deleterious clinical outcomes, they can lead to an unharmonized cervical curvature. The chance of C7 fracture should be discussed in the shared decision-making process.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.550-556
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• 2021

The scissor-type rope cutter is the most widely used amongst all kinds of commercially available rope cutters in Korea. In this study, we performed finite element analysis on the scissor-type rope cutter. We determined the structure of the cutter that would ensure its stable operation in various situations involving rope entanglement, and verified its effectiveness by testing it in the lab and in an actual ship. These investigations revealed that when the propeller shaft was not rotated by rope entanglement, the constant torque generated by the engine resulted in the torsion of the rope cutter and maximum deformation in the lower blade, which was not restricted by finite element analysis. With increasing blade thickness, the maximum values of deformation and equivalent stress decreased, resulting in a rise in the safety factor. At the constant blade thickness, the effect of the torque variations on the maximum equivalent stress and the maximum deformation is independent of the position of the external force of the rope cutter and decreases in direct proportion. The results of this study confirmed that the rope-cutter structure determined by analysis could lead to a hassle-free removal of ropes and fishing nets under all conditions and environments.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.1
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• pp.82-89
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• 2023

The tongue is one of the most common sites of oral cancer. Glossectomy is known as the gold standard for tongue cancer treatment. However, surgical removal can lead to reduced mobility of the tongue and the patients may have difficulty performing normal oral functions like swallowing and pronunciation. Therefore, additional prosthetic consideration to supplement the function of the impaired tongue is needed for oral rehabilitation of such patients. Palatal augmentation prosthesis helps the tongue to reach the palate by lowering the position of the palatal polished surface. The oral functions of the patients with limited tongue mobility can be improved by the prosthesis. In this case, palatal augmented maxillary denture and conventional mandibular denture were fabricated for the completely edentulous patient with reduced tongue mobility after glossectomy due to tongue cancer. As a result, the oral functions of the patient were improved with the prosthesis.

• Journal of Chest Surgery
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• v.43 no.6
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• pp.619-626
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• 2010

Background: The indications and the optimal time of surgery of infective endocarditis are controversial. We report the surgical results of our hospital during the last 10 years with literature review. Material and Method: Between January 2000 and December 2009, we enrolled 23 infective endocarditis patients who underwent surgery, and analyzed retrospectively. In the preoperative blood culture, 8 cases (34.8%) were positive. The average preoperative antibiotics treatment period was $20.78{\pm}16.00$ days. There were 12 (52.2%) urgent operations. The average follow up period was $49.26{\pm}33.21$ months. Result: 20 mechanical valve replacements were performed, 9 in aortic position, 8 in mitral position and 3 in the both positions. The other procedures were one mitral valvuloplasty, one infected myxoma extirpation, and one infected pacemaker lead removal with debridement. The average period of postoperative intravenous antibiotic treatment was $24.39{\pm}15.98$ days. There were 5 complications, including 2 cases of postoperative bleeding, one postcardiotomy syndrome, one cerebral ischemia, and a low cardiac output syndrome. There were statistically significant postoperative improvement in NYHA class, left ventricle end diastolic/end systolic volume, and left atrium size (p-value < 0.05). Conclusion: We could obtain the satisfactory results without any moftalities by using sufficient preoperative antibiotics in hemodynamically stable patients, and by prompt surgery in unstable patients.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.13-22
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• 2015

The combined impact of Dissolved Organic Matter (DOM) fouling and inorganic ($CaSO_4,Ca_3(PO_4)_2$) scaling on the retention of TNT (2, 4, 6-Trinitrotoluene), RDX (Hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine) and HMX (1, 3, 5, 7-Tetranitro-1, 3, 5, 7-tetrazocane) explosive contaminants by nano-filtration membrane were studied, since organic fouling and salt scaling are the major limitations for membrane filtration. Results reported here indicate that DOM fouling layer with a humic acid does not necessarily lead to an immediate loss of permeate flux but can result in a severe impact on the flux loss when both humic acid and inorganic scaltants were presented simultaneously. The $Ca_3(PO_4)_2$ mixed with humic acid showd most sever flux loss (42%) compared to that of only humic acid presence (8%). It could be a result that the scaling formation of the NF membrane was dominated by cake layer formation of DOM and it was along with pore blocking by the formation of crystals inside the porous active matrix of the NF membrane. In addition, these results indicated that the membrane selectivity of the explosives retention trended correlated with respect to increasing explosives size (listed by MW) based on greater steric interactions and followed the order (MW, g $mol^{-1}$; removal, %): HMX (296.15; 83%) ${\gg}$ RDX (222.12; 49%) ≋ TNT (227.13; 32%). Because the scaling and fouling layer could lead to a additional cake-enhanced concentration polarisation effect, the retention of explosives with the presence of humic acid in the feed solution and inorganic scaling formation on top of an organic fouling layer do not differ substantially retention from that of pure DI feed and NaCl solution.

• Tunnel and Underground Space
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• v.32 no.1
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• pp.30-58
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• 2022

The deep geological repository for high-level radioactive waste disposal is a multi barrier system comprised of engineered barriers and a natural barrier. The long-term integrity of the deep geological repository is affected by the coupled interactions between the individual barrier components. Erosion and piping phenomena in the compacted bentonite buffer due to buffer-rock interactions results in the removal of bentonite particles via groundwater flow and can negatively impact the integrity and performance of the buffer. Rapid groundwater inflow at the early stages of disposal can lead to piping in the bentonite buffer due to the buildup of pore water pressure. The physiochemical processes between the bentonite buffer and groundwater lead to bentonite swelling and gelation, resulting in bentonite erosion from the buffer surface. Hence, the evaluation of erosion and piping occurrence and its effects on the integrity of the bentonite buffer is crucial in determining the long-term integrity of the deep geological repository. Previous studies on bentonite erosion and piping failed to consider the complex coupled thermo-hydro-mechanical-chemical behavior of bentonite-groundwater interactions and lacked a comprehensive model that can consider the complex phenomena observed from the experimental tests. In this technical note, previous studies on the mechanisms, lab-scale experiments and numerical modeling of bentonite buffer erosion and piping are introduced, and the future expected challenges in the investigation of bentonite buffer erosion and piping are summarized.

• Korean Journal of Environmental Agriculture
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• v.14 no.2
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• pp.202-212
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• 1995

In order to elucidate the degrading characteristics of the pyrethroid acaricide-insecticide, acrinathrin in two different types of soils, Soil A(pH, 5.8; organic matter, 3.4%; C.E.C., 115 mmol(+)/kg soil; texture, sandy loam) and Soil B(pH, 5.7; organic matter, 2.0%; C.E.C., 71 mmol(+)/kg soil; texture, sandy loam), residualities of the non-labeled compound under the field and laboratory conditions, extractability with organic solvents and formation of non-extractable bound residues, and degradabilities of [$^{14}C$]acrinathrin as a function of aging temperature and aging period were investigated. The half lives of acrinathrin in Soil A treated once and twice were about 18 and 22 days and in Soil B about 13 and 15 days, respectively, in the field, whereas, in the laboratory, those in Soil A and B were about 36 and 18 days, respectively, suggesting that the compound would be non-persistent in the environment. The amounts of $^{14}CO_2$ evolved from [$^{14}C$]acrinathrin in Soil A and B during the aging period of 24 weeks were 81 and 62%, respectively, of the originally applied $^{14}C$ activity, and those of the non-extractable soil-bound residues of [$^{14}C$]acrinathrin were about 70% of the total $^{14}C$ activity remaining in both soils, increasing gradually with the aging period. Degradation of [$^{14}C$]acrinathrin in both soils increased with the aging temperature. Three degradation products of m/z 198(3-phenoxy benzaldehyde), m/z 214(3-phenoxybenzoic acid), and m/z 228(methyl 3-phenoxybenzoate) as well as an unknown were detected by autoradiography of acetone extracts of both soils treated with [$^{14}C$]acrinathrin and aged for 15, 30, 60, 90, 120, and 150 days, respectively, and the degradation pattern of acrinathrin was identical in both soils. Acrinathrin in soil turned out to be degraded to 3-phenoxybenzaldehyde cyanohydrin by hydrolytic cleavage of the ester linkage adjacent to the $^{14}C$ with a cyano group, the removal of hydrogen cyanide therefrom led to the formation of 3-phenoxybenzaldehyde as one of the major products, and the subsequent oxidation of the aldehyde to 3-phenoxybenzoic acid, followed by decarboxylation would lead to the evolution of $^{14}CO_2$.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.484-489
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• 2010

The cultivation of green manure crops plays an important role in soil quality and sustainability of agricultural system. However, the incorporation of green manure crops may be of concern because it can lead to strongly reducing conditions in the submerged soil. This study was conducted to evaluate the effects of rice husk carbon on rice (Oryza sativa L.) cultivation using green manure mixtures (hairy vetch + rye) in rice paddy. Field experiments were conducted in rice paddy soil (Shinheung series, fine loamy, mixed, nonacid, mesic family of Aeric Fluventic Haplaquepts) at the National Institute of Crop Science (NICS), Korea from October 2007 to October 2008. The experiments consisted of three treatments: application or no application of carbonized rice husk, and conventional fertilization. These treatments were subdivided into whole incorporation and aboveground removal of green manure mixtures. The redox potential (Eh) was higher upon application of the carbonized rice husk when compared to no application at 8 and 37 days after transplanting (DAT). The ammonium-N ($NH_4$-N) in soil was highest upon the application of carbonized rice husk + whole green manure incorporation at 17 and 49 DAT. Plant height and tiller number of rice were similar to the $NH_4$-N concentration in soil. Rice yields of application and no application of carbonized rice husk treatment were not significant. However, application of carbonized rice husk improved the soil physical properties such as bulk density and porosity after rice harvest. Therefore, the results of this study suggest that carbonized rice husk could be used as soil amendment for environmentally-friendly rice production under a green manure mixture-rice cropping system.