• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.1
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• pp.1-14
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• 2000

The purpose of this study was to evaluate the efficacy of adding autogenous bone to the toothash-plaster mixture in the healing process of bone. Full-thickness round osseous defects with the diameter of 20mm were made at the calvarial bone of adult dogs (n=19) bilaterally, which were thought to be critical size defect. The right defects were repaired with the toothash-plaster mixture plus autogenous bone (compressed volume 0.3cc) and the left defects with only toothash-plaster mixture. At 2-, 4-, 8-, 12- and 20- week after implantation, dogs were sacrificed and evaluated the osseous healing of bony defects clinically, radiographically, and microscopically. The results were as follows; 1. At the clinical observation, the wound healed very well without any problem except severe swelling in the early period after operation. Slight depression was recognized at the both sides when the portions of cranial defect were palpated. 2. There were statistically significant differences between toothash-plaster mixture groups and autogenous bone added groups at the same period, and among the groups in the bone density of the digital radiograms (P<0.001). There was a tendency that bone density was increasing with time. 3. In light microscopic examination, new bone formation was more active in the autogenous bone added groups than toothash-plaster mixture groups at the early period after implantation but there is little difference at 20-week after implantation. 4. In fluorescent microscopic examination, the fluorescent band could be observed at the area of active bone formation and the band was more distinct in the autogenous bone added groups then toothash-plaster mixture groups. 5. In transmitted electron microscopic examination, organelles such as rER, Golgi complex and secretory granule and osteoblast were observed. In summary higher volume ratio of autogenous bone is needed to improve the bone healing in that there is little difference between toothash-plaster mixture group and autogenous bone added group at the 20-week after implantation in spite of new bone formation was more active in the autogenous bone added groups than toothash-plaster mixture groups at the early period after operation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.477-477
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• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• The korean journal of orthodontics
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• v.18 no.1 s.25
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• pp.189-207
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• 1988

In almost all biologic systems, mechanically induced electric charge separation is a fundamental phenomenon. Since the hypothesis was established that the generation of electric potentials in bone by mechanical stress including muscular force might control the activity in bone by mechanical stress including muscular force might control the activity of osseous cells and their biopolymeric byproduct, the concept of electrically mediate growth mechanism, which involves biological growth and bone remodeling by any means, in living systems has been applied clinically and experimentally to orthopedic fracture repair, the regulation of orthodontic tooth movement, epiphyseal cartilage regeneration, etc. On the other hand, recent numerous research data available show apparently that the mandibular condyle has the characteristics of growth center as well as growth site. In addition, there exists a considerable difference of opinion as to the role of external pterygoid muscle in condylar growth. In view of these evidences, this. experiment was performed to investigate the effect of the galavic current on the growth of the mandible and condyle for elucidating the nature of condylar growth. The bimetallic device was composed of silver and platinum electrode connected with resistor (3.9 Mohm), which was expected to produce galvanic current of 23.6 nA according to the galvanic principle. The 25 Sprague-Dawley rats were divided into two group, 2 week group comprising 8 animals exposed to satanic current for 2 weeks and 3 control animals not exposed for 2 weeks, 4 week group comprising 10 animals in experimental group and 4 animals in control group applied for 4 weeks respectively. The experimental rats were subjected to application of the galvanic current invasively to codylar head surface and the control groups with sham electrode. On the basis of anatomic and histologic data from the mandibular condyle of experimental and control group, the following results were obtained. 1. After 2 weeks, there was no increase of mandibular size in experimental group over that of the control group. 2. After 4 weeks, the size of the condylar head was larger in experimental group than that of the control. 3. In 2 week group, the thickness of the mitotic compartment and hypertrophic chondroblastic layer was increased in experimental group. 4. In 4 week group, the number and the size of the hypertrophic chondroblasts were increased significantly on experimental group over that of the control group. 5. The application of the satanic current caused an increase in chondrocytic hypertrophy and intercellular matrix in both groups.

• Polymer(Korea)
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• v.24 no.3
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• pp.314-325
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• 2000

Thermal degradation of thermoplasitc polyurethane modified polycarbonate has been investigated by means of DSC, GPC and FT-IR techniques. The polyurethanes used in this study are TPU-35 and TPU-53 containing 35.5 and 53.4 wt% of hard segments, respectively. The more content of hard segment, the higher the glass transition temperature (T$_{g}$) of TPU was observed. On the other hand, the T$_{g}$ of the TPU modified PC decreased with the content of TPU and the annealing temperature regardless of the hard segment contents. The latter behavior nay arise from the thermal degradation of TPU upon annealing process: the observed thermal degradation temperatures were at 240 and 25$0^{\circ}C$ for the PC/TPU-35 and PC/TPU-53, respectively. The molecular weight, molecular weight distribution and viscosity agree well with the DSC measurement, which implicates a thermal degradation of TPU. In addition, thermal stability of the TPU modified PC linearly decreased with an incorporation of TPU. Transesterification or any interaction was not observed using FT-IR: the evidence was no frequency shift or any variance betwere the carbonyl stretching and NH group. For the specimens prepared below the degradation temperature, the enhancement of the thickness dependent impact strength of the PC/TPU blend was observed, and the morphology of the two blends was compared.d.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1182-1190
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• 1996

The best treatment of congenital or acquired tracheal stenosis is resection and end to end anastomosis. Various prosthetic material and tissue graft replacement can be considered when the stenotic segment is too long, but their uses are still limited due to many serious complications. The present study examined the effect of immunosuppression and cryopreserved allograft trachea after intraperitoneal omental implantation for evaluation of the possibility of tracheal transplantation. Thirty tracheal segments were harvested from fifteen donor Wistar rats. Among them eighteen segments were implanted immediately(group I, II, III) and twelve segments were used for cryopreservation(group IV, V). Heterotopical intraperitoneal implantation was performed in five groups of rats(n=6); Group I was Wistar syngeneic controls and received no immunosuppression. Group II and III were those of Sprague-Dawley recipients, the former receiving no immunosuppression and the latter receiving immunosuppression(Cyclosporin A 15mg/kg/day, Methylprednisolone 2mg/kg/day). Group IV and V were groups of Sprague-Dawley recipients, the former receiving immunosuppression and the latter receiving no Immunosuppression. After 28 days, rats were sacrificed and the tracheal segments were histologically evaluated. Epithelial thickness was significantly decreased in group II, IV. Epithelial regeneration score was also significantly decreased in II. All rats maintained well their round tracheal contour. In conclusion; I) trachea could be preserved for a long time with cryo method, 2) epithelium could regenerate fully with omentopexy in cryopreserved trachea, 3) immunosuppresion was not necessary with cryopreserved trachea.

• Journal of Animal Science and Technology
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• v.64 no.2
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• pp.353-364
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• 2022

The present study aimed to assess the feasibility of increasing the slaughter weight (SW) of non-lean finishing pigs to improve their meat quality. A total of 36 (Landrace × Yorkshire) × Duroc gilts and barrows were slaughtered at 115 (Av), 125 (Hi), or 135 (XHi) kg, followed by physicochemical analyses and sensory evaluation on their longissimus dorsi (LD) and Semimembranosus (SM) muscles. Backfat thickness was greater (p < 0.05) for the XHi (31.2 mm) and Hi (29.3 mm) groups than for Av (25.0 mm). Dressing percentage and yield of the belly per whole carcass were also slightly greater for XHi and Hi vs. Av. The intramuscular fat (IMF) content of SM was greater for XHi (2.64%) than for Av (1.83%) and Hi (2.04%) and also was correlated with SW (r = 0.55). The pH value, lightness, redness, drip loss, shear force, and moisture and protein contents of LD and SM, as well as IMF content of LD, were unaffected by SW. Percentages of 14:0, 16:0, and total saturated fatty acids (FA) were less for Hi and XHi vs. Av in SM, those of total unsaturated FA, 18:2, 20:4, and n-6 being opposite; FA composition of LM was not influenced by SW except for a reduced 18:0 percentage for XHi vs. Av. The sensory score was less for XHi vs. Av for odor in fresh LD and SM, and less for Hi and XHi vs. Av for aroma in fresh LM; scores for color, drip loss, marbling, and acceptability were unaffected by SW. As for cooked muscles, none of the scores for color, aroma, flavor, juiciness, tenderness, and acceptability was affected by SW, except for a greater LD color score for Hi and XHi vs. Av. Collectively, the results suggested that the increased yield of the carcass and belly due to increased SW is outbalanced negatively by excessive backfat deposition in production efficiency, whereas the SW increase exerts little influence on overall sensory quality of fresh or cooked meat. Production of non-lean market pigs overweighing 115 kg therefore will be uneconomical unless consumers pay a substantial premium for the over-fattened pork.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.197-203
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• 2002

The TiO$_2$ coating solutions were synthesized with different concentrations (T1-0.7N, T2-2.0N) of hydrochloric acid used as catalyst. and TiO$_2$ thin films were prepared by sol-gel dip coating. Their structural and optical properties were examined as a function of calcination temperature. XRD results showed that T1 thin films calcined at 400~80$0^{\circ}C$ had the anatase phase, while those calcined at 100$0^{\circ}C$ had the rutile phase. T2 thin films calcined at 40$0^{\circ}C$ and $600^{\circ}C$ had the anatase phase, with the rutile phase for calcination at 80$0^{\circ}C$. Crystallinity of T2 thin films was superior to that of T1 thin films. The crystallite size of TiO$_2$ thin films increased with increasing calcination temperature, and the crystallite size of anatase phase in T2 thin films was larger than that in T1 thin films, but the crystallite size of rutile phase in T2 thin films was smaller. The surface morphology of the films showed that the films were formed more densely in the rutile phase than in the anatase phase, this phenomenon appeared conspicuously in T2 thin films. The transmittance of the samples with thin films on quartz glass calcined at 100$0^{\circ}C$ was significantly reduced at wavelength range about 300-700 nm due to the increased absorption originating from the change of crystallite phase and composition of the films and the scattering effect originating from increasing crystallite size. The refractive index of TiO$_2$ thin films increased, and hence the film thickness as well as the porosity of TiO$_2$ thin films decreased with increasing calcination temperature. Furthermore, the refractive index of T2 thin films was higher than T1 thin films, and porosity of T2 films was lower.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.322-335
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• 2003

Nutrient fluxes and sediment oxygen demands (SOD) were measured with intact sediment cores collected from three stations in the downstream of Nagdong River. The sediments were subjected to controlled oxic and hypoxic conditions and temperature gradients (from $10^{\circ}C$ to $30^{\circ}C$) of the overlying waters in laboratory batch system. The effect of temperature and labile layer thickness of the sediment on SOD were examined. $PO_4\;^{3-}$ and $NH_4\;^+$ fluxes were elevated above $20^{\circ}C$ and large mobilities were observed when they were coupled with a hypoxic and high-temperature condition. In the well oxygenated conditions, $PO_4\;^{3-}$ fluxes were negative or negligible but $NH_4\;^+$ fluxes ranged from 1.3 mg N $m^{-2}\;hr^{-1}$ to 2.3 $m^{-2}\;hr^{-1}$. Temperature quotients($Q_{10}$) of $PO_4\;^{3-}$ fluxes were 3.7 ${\sim}$ 7.3 ranges to have the most high values. $PO_4\;^{3-}$ and $NH_4\;^+$ fluxes had the logarithmic increase with temperature, while $NO_3\;^-$ was negatively absorbed to the sediment and linearly correlated with the temperature. $SiO_2$ fluxes showed no difference among oxic and hypoxic conditions and sediment texture. The nutrient fluxes would be closely correlated with pore water chemistry of sediments and activated by the top sediment layer composition such as labile organic matters or algal detritus. The ecological implications of the nutrient fluxes were discussed in terms of sources and sinks of nutrients coupled to algal productions in the Nagdong River.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.207-216
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• 2020

Purpose: To compare the polishing characteristics and their influence on Candida albicans adhesion to the recently introduced polyetherketoneketone (PEKK) and the conventional polymethylmethacrylate (PMMA) denture resin material. Materials and methods: Specimens from PEKK (Group E) and PMMA (Group M) were made in dimensions of 8 mm in diameter and 2 mm in thickness. The specimens were further divided into sub-groups according to the extent of polishing (ER, MR: rough; EP, MP: polished, N = 12 each). The specimens were polished using polishing machine and SiC foil. ER and MR group specimens were polished with 600 grit SiC foil only. EP and MP groups were further polished with 800, 1,000, 1,200 grit SiC foils sequentially. To measure the surface roughness values (Sa) of specimens, atomic force microscope (AFM) was used and scanning electron microscope (SEM) observation under 1,000, and 20,000 magnifications was performed to investigate surface topography. The polished specimens were soaked in C. albicans suspension for 2 hours with shaking to promote adhesion. The attached C. albicans were detached from the surface with 10 times of pipetting. The suspension of detached C. albicans was performed by serial dilution to 10³ times, and the diluted suspensions were inoculated on Sabouraud dextrose agar plates using spread plate method. After incubating the plate for 48 hours, colony forming unit (CFU)/plate of C. albicans was counted. Statistical analysis was performed using one-way ANOVA and Tukey HSD test to confirm significant difference between the groups (α=.05). Results: Average Sa value was significantly higher in MR group compared to other groups (P<.05), meaning that additional polishing steps reduced surface roughness effectively only in the PMMA specimens. There was no significant difference in Sa values between MP and EP groups. In SEM images, PEKK specimens showed numerous spikes of abraded material protruding from the surface and this phenomenon was more significant in EP group. The mean CFU/plate value was the highest in EP group and this was significant when it was compared to MP group (P<.05) which was the lowest. Conclusion: Polishing PEKK using serial SiC abrasive foil may result in higher adhesion of C. albicans. In clinic, this should be considered carefully.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2007.11a
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• pp.79-92
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• 2007

Oxidative stress have known to be a risk factor for the degenerative processes and closely related to a lot of diseases. It is well established that antioxidants are good in protection and therapeutic means against oxidative damage. There is increasing interest in natural antioxidants and many natural antioxidants have been found and utilized as the possible protection for various diseases and skin aging. We have screened natural antioxidant agents for cosmeceuticals, nutraceuticals, and drugs as therapeutic and preventive means against oxidative stress, and have developed a number of novel antioxidants from various natural sources. A novel melanin synthesis inhibitor, Melanocin A, isolated from the metabolite of a fungal strain Eupenicillium shearii F80695 inhibited mushroom tyrosinase and melanin biosynthesis of B16 melanoma cells with $IC_{50}$ value of 9.0 nM and MIC value of $0.9\;{\mu}M$, respectively. Melanocin A also exhibited potent antioxidant activity by scavenging of DPPH and superoxide anion radicals. UV was found to increase the level of hydrogen peroxides and other reactive oxygen species (ROS) in skin tissues. This increase in ROS may not only alter the structure and function of many genes and proteins directly but may also modulate their expressions through signal transduction pathways and, ultimately, lead to skin damage. We investigated the effect of Melanocin A on UV-induced premature skin aging. Firstly, the effect of Melanocin A on UV-induced matrix metalloproteinase (MMP)-9 expression in an immortalized human keratinocyte cell line, HaCaT in vitro was investigated. Acute UV irradiation induced MMP-9 expression at both the mRNA and protein levels and Melanocin A suppressed this expression in a dose-dependent manner. We then investigated UV-induced skin changes in hairless mice in vivo by Melanocin A. Chronic exposure of hairless mouse dorsal skin to UV increased skin thickness and induced wrinkle formation and the gelatinase activities of MMP-2 and MMP-9. Moreover, Melanocin A significantly suppressed UV-induced morphologic skin changes and MMP-2 and MMP-9 expression. These results show that Melanocin A can prevent the harmful effects of UV that lead to skin aging. Therefore, we suggest that Melanocin A should be viewed as a potential therapeutic agent for preventing and/or treating premature skin aging. Terrein is a bioactive fungal metabolite isolated from Penicillium species. Terrein has a relatively simple structure and can be easily synthesized. However, the biologic effects of terrein are comparatively unknown. We found for the first time that terrein potently inhibit melanin production in melanocytes and has a strong hypopigmentary effect in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment of Mel-Ab cells with terrein (10-100 mM) for 4 days significantly reduced melanin levels in a dose-dependent manner. In addition, terrein at the same concentration also reduced tyrosinase activity. We then investigated whether terrein influences the extracellular signal-regulated protein kinase (ERK) pathway and the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. Terrein was found to induce sustained ERK activation and MITF down-regulation, and luciferase assays showed that terrein inhibits MITF promoter activity in a dose-dependent manner. To elucidate the correlation between ERK pathway activation and a decreased MITF transcriptional level, PD98059, a specific inhibitor of the ERK pathway, was applied before terrain treatment and found to abrogate the terrein-induced MITF attenuation. Terrein also reduced the tyrosinase protein level for at least 72 h. These results suggest that terrain reduces melanin synthesis by reducing tyrosinase production via ERK activation, and that this is followed by MITF down-regulation.