• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.209-222
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• 2024

The Earth Pressure Balance (EPB) shield Tunnel Boring Machine (TBM) is widely used for underground tunnel construction for its advantages, such as eliminating the need for additional facilities compared to the slurry shield TBM, which requires Slurry Treatment Plant (STP). During EPB shield TBM excavation, a soil conditioning technique is employed to enhance the physical properties of the excavated soil by injecting additives, thus broadening the range of applicable ground conditions to EPB shield TBMs. This study explored the use of xanthan gum, a type of biopolymer, as an alternative to the commonly used polymer additive. Biopolymers, derived from biological sources, are fully biodegradable. In contrast to traditional polymers such as polyacrylic acid, which contain environmentally harmful components, xanthan gum is gaining attention as an eco-friendly material due to its minimal toxicity and environmental impact. Test conditions with similar workability were established through slump tests, and the rheological characteristics were assessed using a laboratory pressurized vane shear test apparatus. The experiments demonstrated that, despite exhibiting similar workability, the peak strength in the flow curve decreased with increasing the content of xanthan gum. Consequently, a correlation between the xanthan gum content and peak strength was established. Replacing the traditional polymers with xanthan gum could enable stable EPB shield TBM operation by reducing equipment load, in addition to offering environmental benefits.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.9-16
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• 2018

Hangover after drinking is different from person to person symptoms and degree, but usually thirst, fatigue, headache, general boredom, gastrointestinal disorder, vomiting, diarrhea, deficiency of vitamin appears. This hanging phenomenon is caused by the action of precursors such as ethyl acetate and acetaldehyde, which are the by products of fermentation contained in alcohol and alcohol accumulated in hepatocytes and body. In order to solve the hangover phenomenon, the same Origin as polysaccharide Polydeoxyribonucleotide, which is a nucleic acid-sugar-phosphate complex, which is a semen or testicular extract in salmon extract, and a water soluble salmon extract powder having the same structure and lower price than Polydeoxyribonucleotide And D-Glucuronic acid and N-Acetyl glucosamine. It has excellent biocompatibility, viscoelasticity and moisturizing power. It has effect on reduction of body water loss and skin moisture content in hangover phenomenon. It is antioxidant and skin moisturizing effect Hyaluronic acid was irradiated with gamma rays, and the composition was prepared by using the salmon extract powder and the main raw material. The ethanol degradation, the acetaldehyde reduction amount, the blood acetaldehyde concentration and the acetic acid concentration were measured to evaluate the alcoholysis effect, Skin moisture evaporation rate To examine the evaluation unit water content of the skin was improved determine whether the antioxidant and provide skin moisturizing effect. The addition of ethanol extracts of salmon extracts showed a decrease of 5 to 7 times compared with no addition, and a decrease of 3 to 5 times of acetaldehyde. In addition, the change of acetaldehyde concentration and acetic acid concentration in blood showed a rapid decrease compared to the no - added control group. In addition, when the raw material of hyaluronic acid was used, skin moisture content was high and skin moisture evaporation amount was decreased. Therefore, hyaluronic acid, which is a polysaccharide polymer, has excellent viscoelasticity and moisturizing ability, It is considered to provide antioxidant and skin moisturizing effect. Therefore, it can be said that the composition containing salmon extract powder and hyaluronic acid as a main ingredient is effective for the hangover phenomenon which occurs after drinking.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.83-89
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• 2020

For the past few decades, as part of efforts to protect the environment where fossil fuels, which have been a key energy resource for mankind, are becoming increasingly depleted and pollution due to industrial development, ecofriendly secondary batteries, hydrogen generating energy devices, energy storage systems, and many other new energy technologies are being developed. Among them, the lithium-ion battery (LIB) is considered to be a next-generation energy device suitable for application as a large-capacity battery and capable of industrial application due to its high energy density and long lifespan. However, considering the growing battery market such as eco-friendly electric vehicles and drones, it is expected that a large amount of battery waste will spill out from some point due to the end of life. In order to prepare for this situation, development of a process for recovering lithium and various valuable metals from waste batteries is required, and at the same time, a plan to recycle them is socially required. In this study, we introduce a nanoscale pattern transfer printing (NTP) process of Li2CO3, a representative anode material for lithium ion batteries, one of the strategic materials for recycling waste batteries. First, Li2CO3 powder was formed by pressing in a vacuum, and a 3-inch sputter target for very pure Li2CO3 thin film deposition was successfully produced through high-temperature sintering. The target was mounted on a sputtering device, and a well-ordered Li2CO3 line pattern with a width of 250 nm was successfully obtained on the Si substrate using the NTP process. In addition, based on the nTP method, the periodic Li2CO3 line patterns were formed on the surfaces of metal, glass, flexible polymer substrates, and even curved goggles. These results are expected to be applied to the thin films of various functional materials used in battery devices in the future, and is also expected to be particularly helpful in improving the performance of lithium-ion battery devices on various substrates.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.193-202
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• 2016

Purpose: This study was performed in order to assess the effect of the surface treatment methods and the use of bonding agent on the shear bond strength (SBS) between the aged CAD-CAM (computer aided design-computer aided manufacturing) hybrid materials and added composite resin. Materials and methods: LAVA Ultimate (LU) and VITA ENAMIC (VE) specimens were age treated by submerging in a $37^{\circ}C$ water bath filled with artificial saliva (Xerova solution) for 30 days. The surface was ground with #220 SiC paper then the specimens were divided into 9 groups according to the combination of the surface treatment (no treatment, grinding, air abrasion with aluminum oxide, HF acid) and bonding agents (no bonding, Adper Single Bond 2, Single Bond Universal). Each group had 10 specimens. Specimens were repaired (added) using composite resin (Filtek Z250), then all the specimens were stored for 7 days in room temperature distilled water. SBS was measured and the fractured surfaces were observed with a scanning electron microscope (SEM). One-way ANOVA and Scheffe test were used for statistical analysis (${\alpha}=.05$). Results: Mostly groups with bonding agent treatment showed higher SBS than groups without bonding agent. Among the groups without bonding agent the groups with aluminum oxide treatment showed higher SBS. However there was no significant difference between groups except two subgroups within LU group, which revealed a significant increase of SBS when Single Bond Universal was used on the ground LU specimen. Conclusion: The use of bonding agent when repairing an aged LAVA Ultimate restoration is recommended.

• Analytical Science and Technology
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• v.28 no.6
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• pp.398-408
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• 2015

Carbon monoxide (CO) intoxication, arising from CO from an ignited charcoal briquette (ICB), is a popular means of committing suicide in Korea. Most CO intoxications are related to suicide attempts; however, the possibility of a homicide disguised as a suicide cannot be ruled out. Therefore, forensic investigation of the deceased and the crime scene is crucial to confirm that the deceased committed suicide. Detection of the components of an ICB on the objects suspected of being contacted by the deceased, such as the hands, nostrils, and doorknobs, is essential for linking the crime scene to the victim in the case of suicides by ignited ICBs. The traces from an ICB were analyzed by investigating the morphological characteristics and obtaining elemental compositions. The ICBs were completely different from blackened wood, as detected by discriminant analysis with the elements of carbon and oxygen. We analyzed one case of CO intoxication to demonstrate an excellent procedure for verifying whether a suicide occurred with an ICB. We employed SEM-EDX for the analysis of an ICB, microscope-FT/IR and pyrolysis-GC/MS for a partly burnt resin-type substance, GC/MS for diphenhydramine (a sleeping drug), and GC/TCD for the CO-Hb level. We detected traces of an ICB on the hands, nostrils, and doorknobs, which were all discriminated into an ICB group. Detection of ICB traces from the nostrils could indicate that the deceased started the fire themselves to commit suicide. The partially burnt black material was analyzed as an acrylronitrilestyrene polymer, which is normally used to make bags for carrying or wrapping and could be assumed to have been used to transport the ICB. Diphenhydramine, a sleeping drug, was detected at a level of 2.3 mg/L in the blood, which was lower than that in fatal cases (8-31 mg/L; mean 16 mg/L). A CO-Hb level of 79% was found in the blood, which means that the cause of death was CO intoxication. The steps shown here could represent an ideal method for reaching a verdict of suicide by CO intoxication produced by burning an ICB in a sealed room or a car.

• Radiation Oncology Journal
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• v.9 no.1
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• pp.27-35
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• 1991

An interstitial radiofrequency needle electrode system was constructed for interstitial heating of brain tissue. Radiofrequency electrodes with Thermotron RF 8 were tested in an agar phantom and in a normal canine brain to determine how variations in physical factors affected temperature distributions. Temperature distributions were checked after heating with 1 mm diameter needle electrode implants on the corners of 1 and 2 cm squares in a phantom and plot isotherms for various electrodes arrangement. We observed that the 1 cm square array would heat a volume with a 1.25 cm radius circular field cross section to therapeutic temperatures ($90\%$ relative SAR using Tm) and the 2 cm square array with a 1.75 cm radius rectangular field with central inhomogeneity. With 2 cm long electrode implants, we observed that the 1 cm square array would heat a 3 cm long sagittal section to therapeutic temperature ($90\%$ relative SAR using Tm). We found that radiofrequency electrodes could be selected to match the length of the heating area without affecting its performance. The histopathological changes associated with RF heating of normal canine brains have been correlated with thermal distributions. RF needle electrode heating was applied for 50min to generate tissue temperatures of $43^{\circ}C$. We obtained a quarter of the heated tissue material immediately after heating and sacrificed at intervals from $7\sim30$days. The acute stage (immediately after heating) was demonstrated by liquefactive necrosis, pyknosis of neuronal element in the gray matter and by some polymer-phonuclear leukocytes infiltration. The appearance of lipid-laden macrophages surrounding the area of liquefaction necrosis was demonstrated in all three sacrificed dogs. Mild gliosis occurring around the necrosis was demonstrated in the last sacrificed (Days 30) canine brain.

• Journal of Chest Surgery
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• v.37 no.6
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• pp.482-491
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• 2004

Background: The xenogenic or allogenic valves after in Vitro repopulation with autologous cells or in vivo repo-pulation after acellularization treatment to remove the antigenicity could used as an alternative to synthetic polymer scaffold. In the present study, we evaluated the process of repopulation by recipient cell to the acellu-larized xenograft treated with NaCl-SDS solution and grafted in the right ventricular outflow tract. Material and Method: Porcine pulmonary valved conduit were treated with. NaCl-SDS solution to make the grafts acellularized and implanted in the right ventricular outflow tract of the goats under cardiopulmonary bypass. After evaluating the functions of pulmonary valves by echocardiography, goats were sacrificed at 1 week, 1 month, 3 months, 6 months, and 12 months after implantation, respectively. After retrieving the implanted valved conduits, histopathologic examination with Hematoxylin-Eosin, Masson' trichrome staining and immunohistochemical staining was performed. Result: Among the six goats, which had been implanted with acellularized pulmonary valved conduits, five survived the expected time period. Echocardiographic examinations for pulmonary valves revealed good function except mild regurgitation and stenosis. Microscopic analysis of the leaflets showed progressive cellular in-growth, composed of fibroblasts, myofibroblasts, and endothelial cells, into the acellularized leaflets over time. Severe inflammatory respon-se was detected in early phase, though it gradually decreased afterwards. The extracellular matrices were regenerated by repopulated cells on the recellularized portion of the acellularized leaflet. Conclusion: The acellularized xenogenic pulmonary valved conuits were repopulated with fibroblasts, myofibroblasts, and endothelial cells of the recipient and extracellullar matrices were regenerated by repopulted cells 12 months after the implantation. The functional integrity of pulmonary valves was well preserved. This study showed that the acellularized porcine xenogenic valved conduits could be used as an ideal valve prosthesis with long term durability.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.313-318
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• 1997

Effects of the concentration of NaCl, the concentration and the molecular weight of chitosan on the permeability of capsule type fertilizer and herbicide were investigated. The encapsulating process was based on the electrostatic interaction between chitosan (a polycationic polymer) and sodium alginate (an anionic polysaccharide). Sodium alginate solution $(1\%)$ was dropped into chitosan solution $(1\%)$ in which various amounts of NaCl was added. The capsule strength was increased with the addition of NaCl and the maximum value of capsule strength was observed at 0.3M NaCl. Capsule type fertilizer and herbicide were immersed in deionized water to determine its permeability, and it was affected by the concentration of NaCl and chitosan, and the molecular weight of chitosan. As the concentration of NaCl in chitosan solution increased, permeability of the capsule increased and marked the maximum value of $ 88\%$(fertilizer), $87\%$ (herbicide) at 0.75M NaCl. As concentration of chitosan solution increased, permeability tended to decreased; it showed the maximum value of $90\%$ (fertilizer) and $90.3\%$ (herbicide) at $0.25\%$ chitosan and the minimum value of $83\%$ (fertilizer) and $82\%$ (herbicide) at $1\%$ chitosan. Permeability of fertilizer and herbicide also decreased, as the molecular weight of chitosan (material of capsule) was decreased; it was showed $86\%$ (fertilizer) and $83\%$ (herbicide) at M.W 330,000 (sonication time 0min) and $52\%$ (fertilizer) and $51\%$ (herbicide) at M.W 119,000 (sonication time 180 min). The chitosan-alginic acid capsule was manufactured (defined as prepared capsule), dried for 6 hrs and immersed in deionized water (defined as restored capsule) to examine restoration of capsule. Restoration of capsule was good, and capsule strength was slightly decreased form $20g/cm^2$ (prepared capsule) to $17g/cm^2$ (restored capsule)

• Journal of Korean Society of Environmental Engineers
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• v.36 no.7
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• pp.514-520
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• 2014

In this study, the production potential of alternative coagulant ($Al_2(SO_4)_3$ solution) having the identical coagulation activity with respect to the commercial coagulant was investigated. The raw material of alternative coagulant was a spent catalyst including aluminium (waste activated alumina) generated in the manufacturing process of the polymer. The alternative coagulant was produced through a series of processes: 1) intense heat and grinding, 2) chemical polymerization and substitution with $H_2SO_4$ solution, 3) dissolution and dilution and 4) settling and separation. To determine the optimal operating conditions in the lab-scale autoclave and dissolver, the content of $Al_2O_3$ in alternative coagulant was analyzed according to changes of the purity of sulfuric acid, reaction temperature, injection ratio of sulfuric acid and water in the dissolver. The results showed that the alternative coagulant having the $Al_2O_3$ content of 7~8% was produced under the optimal conditions such as $H_2SO_4$ purity of 50%, reaction temperature of $120^{\circ}C$, injection ratio of $H_2SO_4$ of 5 times and injection ratio of water of 2.3 times in dissolver. In order to evaluate the coagulation activity of the alternative coagulant, the Jar-test was conducted to the effluent in aerobic reactor. As a result, in both cases of Al/P mole of 1.5 and 2.0, the coagulation activity of the alternative coagulant was higher than that of the existing commercial coagulant. When the production costs were compared between the alternative and commercial coagulant through economic analysis, the production cost reduction of about 50% was available in the case of the alternative coagulant. In addition, it was identified that the alternative coagulant could be applied at field wastewater treatment plant without environmental problem through ecological toxicity testing.

• Journal of Periodontal and Implant Science
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• v.31 no.1
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• pp.1-23
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• 2001

Chitosan is biodegradable natural polymer that has been demonstrated its ability to improve wound healing, and calcium metaphosphate(CMP) is a unique class of phosphate minerals having a polymeric structure. In this study, chitosan/CMP and platelet derived growth factor(PDGF-BB) loaded chitosan/CMP sponges were developed, and the effect of the sponges on bone regeneration and their possibility as scaffolds for bone formation by three-dimensional osteoblast culture were examined. PDGF-BB loaded chitosan/CMP sponges were prepared by freeze-drying of a mixture of chitosan solution and CMP powder, and soaking in a PDGF-BB solution. Fabricated sponge retained its 3-dimensional porous structure with $100-200\;{\mu}m$ pores. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with $^{125}I-labeled$ PDGF-BB. In order to examine their possibility as scaffolds for bone formation, fetal rat calvarial osteoblastic cells were isolated, cultured, and seeded into the sponges. The cell-sponge constructs were cultured for 28 days. Cell proliferation, alkaline phosphatase activity were measured at 1, 7, 14 and 28 days, and histologic examination was performed. In order to examine the effect on the healing of bone defect, the sponges were implanted into rat calvarial defects. Rats were sacrificed 2 and 4 weeks after implantation and histologic and histomorphometrical examination were performed. An effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. PDGF-BB loaded chitosan/CMP sponges supported the proliferation of seeded osteoblastic cells as well as their differentiation as indicated by high alkaline phosphatase activities. Histologic findings indicated that seeded osteoblastic cells well attached to sponge matrices and proliferated in a multi-layer fashion. In the experiments of implantation in rat calvarial defects, histologic and histomorphometric examination revealed that chitosan/CMP sponge promoted osseous healing as compared to controls. PDGF-BB loaded chitosan/CMP sponge further echanced bone regeneration. These results suggested that PDGF-BB loaded chitosan/CMP sponge was a feasable scaffolding material to grow osteoblast in a three-dimentional structure for transplantation into a site for bone regeneration.