• Journal of the Korean Society for Nondestructive Testing
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• v.13 no.1
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• pp.40-45
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• 1993

The steam generator tubes of the nuclear power plant should be inspected using eddy current techniques. Recently the crack-like defects become a major concern for the integrity of the steam generator tubes. These defects could be detected by the MRPC(Motorized Rotating Pancake Coil) method, not by the conventional bobbin coil method. In this paper it has been attempted to estimate the length of the cracks at the tube expansion region using of MRPC technique. The lengths of both axial and circumferential cracks show a tendency of overestimation compared to the real lengths. As the depths of the defects decrease from 100% through 50% of the wall thickness, the error of the length estimation is increased.

• Journal of Periodontal and Implant Science
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• v.32 no.2
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• pp.325-338
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• 2002

Bone graft using growth factors and guided tissue regeneration have been used for the regeneration of infrabony defects which caused by periodontal disease. Calcium sulfate which is one of the resorbable barrier materials used for guided tissue regeneration. Platelet rich plasma which is a easy method to obtain the growth factors had many common points but, platelet rich plasma was still studying. This study was the comparative study between bone graft using platelet rich plasma and guided tissue regeneration using calcium sulfate barrier material in clinical view. For the study, 28 sites(2 or 3 wall infrabony defects) were treated. 14 infrabony defects were received surgical implantation of BBP-calcium sulfate composite with a calcium sulfate barrier and the others received BBP mixed with platelet rich plasma. Clinical outcome was accessed 3 and 6 months of postsurgery. 1. There was no statistical difference between CS group and PRP group in pocket depth, gingival recession, clinical attachment level, and probing bone level at baseline. 2. There was statistically significant reduction in probing depth, clinical attachment level, and probing bone level at 3 and 6 months postsurgery(p<0.05). 3. In the probing depth and clincial attachment level PPR group had less improvement than CS group, but there was no statistically difference at 3 and 6 months postsurgery. 4. In the recession PPR group had less recession than CS group, but there was no statistically difference at 3 and 6 months postsurgery. 5. In the probing bone level PPR group had less improvement than CS group, but there was no statistically difference at 6 months postsurgery. In conclusion bone graft using platelet rich plasma and guided tissue regeneration using calcium sulfate barrier showed similar clinical improvement for the treatment of 2 or 3 wall infrabony defects.

• Archives of Plastic Surgery
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• v.49 no.1
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• pp.25-28
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• 2022

The authors performed rigid reconstruction using the sandwich technique for full-thickness chest wall defects by using two layers of acellular dermal matrix and bone cement. We assessed six patients who underwent chest wall reconstruction. Reconstruction was performed by sandwiching bone cement between two layers of acellular dermal matrix. In all patients, there was no defect of the overlying soft tissue, and primary closure was performed for external wounds. The average follow-up period was 4 years (range, 2-8 years). No major complications were noted. The sandwich technique can serve as an efficient and safe option for chest wall reconstruction.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.61-61
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• 2010

In the present work, we present the optimized the hybrid structures of carbon nanotubes (CNTs) and metal nanocomposites including Cu, Al, Co and Ni using the first principle calculations based on the density functional theory. Introduction of CNTs into a metal matrix has been considered to improve the mechanical properties of the metal matrix. However, the binding energy between metals and pristine CNTs wall is known to be so small that the interfacial slip between CNTs and the matrix occurs at a relatively low external stress. The application of defective or functionalized CNTs has thus attracted great attention to enhance the interfacial strength of CNT/metal nanocomposites. Herein, we design the various hybrid structures of the single wall CNT/metal complexes and characterize the interaction between single wall CNTs and various metals such as Cu, Al, Co or Ni. First, differences in the binding energies or electronic structures of the CNT/metal complexes with the topological defects, such as the Stone-Wales and vacancy, are compared. Second, the characteristics of functionalized CNTs with various surface functional groups, such as -O, -COOH, -OH interacting with metals are investigated.We found that the binding energy can be enhanced by the surface functional group including oxygen since the oxygen atom can mediate and reinforce the interaction between carbon and metal. The binding energy is also greatly increased when it is absorbed on the defects of CNTs. These results strongly support the recent experimental work which suggested the oxygen on the interface playing an important role in the excellent mechanical properties of the CNT-Cu composite[1].

• Journal of the Korean Chemical Society
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• v.56 no.1
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• pp.34-46
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• 2012

Dopants and defects can be introduced as well as the intercalation of metals into single wall carbon nanotubes (SWCNTs) to modify their electronic and magnetic properties, thus significantly widening their application areas. Through spinpolarized density functional theory (DFT) calculations, we have systemically studied the following: (i) (10,0) and (5,5) SWCNT doped with nitrogen ($CN_xNT$), (ii) (10,0) and (5,5) SWCNT with pyridine-like defects (3NV-$CN_xNT$), and (iii) chemical functionalization of (10,0) and (5,5) 3NV-$CN_xNT$ with 12 different transition metals (TMs) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pd, and Pt). Attention was done in searching for the most stable configurations, deformation, calculating the formation energies, and exploring the effects of the doping concentration of nitrogen and pyridine-like nitrogenated defects on the electronic properties of the nanotubes. Also, calculating the corresponding binding energies and effects of chemical functionalization of TMs on the electronic and magnetic properties of the nanotubes has been made. We found out that the electronic properties of SWCNT can be effectively modified in various ways, which are strongly dependent not only on the concentration of the adsorbed nitrogen but also to the configuration of the adsorbed nitrogen impurities, the pyridine-like nitrogenated defects, and the TMs absorbed; due to the strong interaction between the d orbitals of TMs and the p orbitals of N atoms, the binding strengths of TMs with the two 3NV-$CN_xNT$ are significantly enhanced when compared to the pure SWCNTs.

• Journal of Periodontal and Implant Science
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• v.38 no.1
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• pp.97-102
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• 2008

Purpose: Periodontal intrabony defects have great deal of importance since they contribute to the development of periodontal disease. Current treatment regimens for intrabony defects involve grafting of numerous bony materials, GTR using biocompatible barriers, and biomodification of root surface that will encourage the attachment of connective tissue. Xenograft using deproteinized bovine bone particles seems to be very convenient to adjust because it doesn't require any donor sites or imply the danger of cross infections. These particles are similar to human cancellous bone in structure and turned out to be effective in bone regeneration in vivo. We here represent the effectiveness of grafting deproteinized bovine bone particles in intrabony defect and furcation involvements that have various numbers of bony walls. Materials and methods: Open flap debridement was done to remove all root accretions and granulation tissue from the defects within persisting intrabony lesions demonstrating attachment loss of over 6mm even 3 months after nonsurgical periodontal therapy have been completed. Deproteinized bovine bone particles($BBP^{(R)}$, Oscotec, Seoul) was grafted in intrabony defects to encourage bone regeneration. Patients were instructed of mouthrinses with chlorohexidine-digluconate twice a day and to take antibiotics 2-3 times a day for 2 weeks. They were check-up regularly for oral hygiene performance and further development of disease. Probing depth, level of attachment and mobility were measured at baseline and 6 months after the surgery. The radiographic evidence of bone regenerations were also monitored at least for 6 months. Conclusion: In most cases, radio-opacities increased after 6 months. 2- and 3-wall defects showed greater improvements in pocket depth reduction when compared to 1-wall defects. Class I & II furcation involvements in mandibular molars demonstrated the similar results with acceptable pocket depth both horizontally and vertically comparable to other intrabony defects. Exact amount of bone gain could not be measured as the re-entry procedure has not been available. With in the limited data based on our clinical parameter to measure pocket depth reduction following $BBP^{(R)}$ grafts, it was comparable to the results observed following other regeneration techniques such as GTR.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.746-751
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• 2003

A method of measuring the length of defects on the wall of the spent nuclear fuel pool using the image processing and a laser slit beam is proposed. Since the defect monitoring camera is suspended by a crane and hinged to the crane hook, the camera viewing direction can not be adjusted to the orientation that is exactly perpendicular to the wall. Thus, the image taken by the camera, which is horizontally rotated along the axis of the camera supporting beam, is distorted and thus, the precise length can not be measured. In this paper, by using the LASER slit beam generator, the horizontally rotated angle of the camera is estimated. Once the angle is obtained, the distorted image can be easily reconstructed to the image normal to the wall. The estimation algorithm adopts a 3-dimensional coordinate transformation of the image plane where both the laser slit beam and the original image of the defects exist. The estimation equation is obtained by using the information of the beam projected on the wall and the parameters of this equation are experimentally obtained. With this algorithm, the original image of the defect taken at arbitrary rotated angle can be reconstructed to an image normal to the wall. From the result of a series of experiments, the accuracy of the defect is measured within 0.6 and 1.3 % error bound of real defect size in the air and underwater, respectively under 30 degree of the inclined angle of the laser slit beam generator. Also, the error increases as the inclined angle increases upto 60 degree. Over this angle, the defect length can not be measured since the defect image disappears. The proposed algorithm enables the accurate measurement of the defect length only by using a single camera and a laser slit beam.

• Journal of Magnetics
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• v.21 no.1
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• pp.57-60
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• 2016

Non Destructive Testing (NDT) methods that are capable of detecting the wall thinning and defects through insulation and cladding sheets are necessary. In this study we developed a Pulsed Eddy Current (PEC) system to detect wall thinning of ferro magnetic steel pipes covered with 95 mm thick fiber glass thermal insulator and shielded with aluminum plate of thickness 0.4 mm. In order to confirm the thickness change due to wall thinning, two different sensors, a hall sensor and a search coil sensor were used as a detecting element. In both the cases, the experimental data indicates a considerable change in the detected pulse corresponding to the change in sample thickness. The thickness of the tube was made to change such as 2.5 mm, 5 mm and 8 mm from the inner surface to simulate wall thinning. Fast Fourier Transform (FFT) was calculated using window approach and the results were summarized which shows a clear identification of thickness change in the test specimen by comparing the magnitude spectra.

• Journal of Periodontal and Implant Science
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• v.38 no.1
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• pp.51-58
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• 2008

Purpose: In dental clinical fields, various periodontal membranes are currently used for periodontal regeneration. The periodontal membranes are categorized into two basic types: resorbable and non-resorbable. According to the case, clinician select which membrane is used. Comparing different membranes that are generally used in clinic is meaningful. For this purpose, this study evaluates histological effects of various membranes in canine one wall intrabony defect models and it suggest a valuation basis about study model. Material and Method: The membranes were non-resorbable TefGen $Plus^{(R)}$, resorbable Gore Resolut $XT^{(R)}$ and resorbable $Osteoguide^{(R)}$. One wall intrabony defects were surgically created at the second and the mesial aspect of the fourth mandibular premolars in either right or left jaw quadrants in two dogs. The animals were euthanized 8 weeks post-surgery when block sections of the defect sites were collected and prepared for histological evaluation. Results: 1. While infiltration of inflammatory cells were observed in control, TefGen $Plus^{(R)}$ and Gore Resolut $XT^{(R)}$, it was not observed in $Osteoguide^{(R)}$. 2. TefGen $Plus^{(R)}$ had higher integrity than others and $Osteoguide^{(R)}$ was absorbed with folding shape. Gore Resolut $XT^{(R)}$ was divided everal parts during resorbtion and it was also absorbed from inside. 3. Quantity of new bone and new cementum was not abundant in all membranes. 4. For histologic evaluation of membranes we should consider infiltration of inflammatory, migration of junctional epithelium, integrity of membrane, quantity of new bone and new cementum, connective tissue formation and aspect of resorption. Conclusion: This histologic evaluation suggests that $Osteoguide^{(R)}$ provides periodontal regenerative environment with less inflammatory state. It is meangful that this study model suggests a valuation basis about other study model.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.1
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• pp.1-9
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• 2005

A stoichiometric mixture of evaporating materials for AgGaS₂ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, AgGaS₂ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were 590℃ and 440℃, respectively. The temperature dependence of the energy band gap of the AgGaS₂ obtained from the absorption spectra was well described by the Varshni's relation, E/sub g/(T) = 2.7284 eV - (8.695×10/sup -4/ eV/K)T²/(T + 332 K). After the as-grown AgGaS₂ single crystal thin films was annealed in Ag-, S-, and Ga-atmospheres, the origin of point defects of AgGaS₂ single crystal thin films has been investigated by the photoluminescence (PL) at 10 K. The native defects of V/sub Ag/, V/sub s/, Ag/sub int/, and S/sub int/ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Ag-atmosphere converted AgGaS₂ single crystal thin films to an optical n-type. Also, we confirmed that Ga in AgGaS₂/GaAs crystal thin films did not form the native defects because Ga in AgGaS₂ single crystal thin films existed in the form of stable bonds.