• Korean Journal of Materials Research
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• v.9 no.2
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• pp.217-225
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• 1999

The effect on the pitting corrosion resistance of laser welding and surface treatment developed as a repair method of stream generator tubing material that was a major component of primary system at nuclear power plant was observed. Some heat-treated Alloy 600 tubing materials used at domestic nuclear power plants were laser-surface observed. Some heat-treated Alloy 600 tubing materials used at domestic nuclear power plants were laser-surface melted and the microstructural characteristics were examined. The pitting corrosion resistance was examined through Ep(pitting potential) and degree of pit generation by means of the electrochemical tests and the immersion tests respectively. The pit formation characteristics were investigated through microstructural changes and the pit initiation site and pit morphology. The test results showed that the pitting corrosion resistances was increased in the order of the followings; sensitized Alloy 600, solution annealed alloy600, and laser surface melted Alloy 600. Pits were initiated preferably at Ti-containing inclusions and their surroundings in all tested specimens and it is believed that higher pitting resistance of laser-surface treated Alloy 600 was caused by fine, homogeneous distribution of non-soluble inclusions, the disappearance of grain boundary, and the formation of dense, stable oxide film. The major element of corrosion products filled in the pit was Cr. On the other hand, Fe was enriched in the deposit formed on the pit.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.6
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• pp.281-286
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• 2021

Arc ion plating (AIP), laser cladding, and nitriding are methods that can prevent mold damage or repair and create cracks and breakages on the die surface. The dissolution and soldering behavior of coated SKD61 by using arc ion plating, laser cladding, and nitriding was investigated. The structure of the coating was investigated as a function of deposition conditions by X-ray diffraction and the crystallographic orientation was determined using the texture factor. The TiAlN film deposited with AIP showed excellent corrosion resistance in the molten aluminum alloy at 680℃. In this paper, we have detailed the corrosion and mass loss phenomena associated with these steel-cast metal interactions.

• Archives of Craniofacial Surgery
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• v.20 no.2
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• pp.84-88
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• 2019

Background: Epidermal cysts are benign, slow growing cysts that often develop on the head, neck, chest, and back of adults. The most common method of surgical excision involves the use of a scalpel and often leaves a scar proportional to the size of the cyst. Therefore, minimally invasive techniques are required. Among these techniques, the $CO_2$ laser-based technique is minimally invasive and has lower complication rate, shorter recovery times, and lesser scarring. This paper aimed to compare the results and postoperative complications associated with a $CO_2$ laser-based excision against conventional surgical excision for epidermal cysts. Methods: We surveyed 120 patients, aged 16 to 65 years, with epidermal cysts on the face measuring 0.5 to 2.2 cm in diameter. Twelve months later, we compared the scar length, recurrence rate, patient satisfaction, and complications between patients treated with $CO_2$ laser excision versus surgical excision. Results: The mean scar length (12 months postoperative) after $CO_2$ laser excision was $0.30{\pm}0.15cm$, and that following surgical excision was $1.23{\pm}0.43cm$ (p= 0.001). The procedure time (time from incision after local anesthesia to the end of repair) was $16.15{\pm}5.96minutes$ for $CO_2$ laser excision versus $22.38{\pm}6.05minutes$ for surgical excision (p= 0.001). The recurrence rates in the surgical excision group and $CO_2$ laser excision group were 3.3% and 8.3%, respectively; this difference was not statistically significant (p= 0.648). Conclusion: The cosmetic outcome of $CO_2$ laser excision is excellent. For epidermal cysts measuring 2.2 cm or smaller, $CO_2$ laser excision is recommended, especially when aesthetic outcome is considered important.

• Current Optics and Photonics
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• v.7 no.4
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• pp.387-397
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• 2023

Tooth surface shape error is an important parameter in gear accuracy evaluation. When tooth surface shape error is measured by laser interferometry, the gear interferogram is highly distorted and the gray level distribution is not uniform. Therefore, it is important for gear interferometry to extract the foreground region from the gear interference fringe image directly and accurately. This paper presents an approach for foreground extraction in gear interference images by leveraging the sinusoidal variation characteristics shown by the interference fringes. A gray level mask with an adaptive threshold is established to capture the relevant features, while a local variance evaluation function is employed to analyze the fluctuation state of the interference image and derive a repair mask. By combining these masks, the foreground region is directly extracted. Comparative evaluations using qualitative and quantitative assessment methods are performed to compare the proposed algorithm with both reference results and traditional approaches. The experimental findings reveal a remarkable degree of matching between the algorithm and the reference results. As a result, this method shows great potential for widespread application in the foreground extraction of gear interference images.

• The Journal of Advanced Prosthodontics
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• v.12 no.5
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• pp.273-282
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• 2020

PURPOSE. To assess shear bond strengths (SBS) of resin composites on aged and non-aged prosthetic materials with various surface treatments. MATERIALS AND METHODS. Cerasmart (CE), Vita Enamic (VE), Vita Mark II (VM), and IPS e.max CAD (EC) blocks were sliced, and rectangular-shaped specimens (14 × 12 × 1.5 mm; N = 352) were obtained. Half of the specimens were aged (5000 thermal cycles) for each material. Non-aged and aged specimens were divided into 4 groups according to the surface treatments (control, air abrasion, etching, and laser irradiation; n = 11) and processed for scanning electron microscopy (SEM). The repair procedure was performed after the surface treatments. SBS values and failure types were determined. Obtained data were statistically analyzed (P≤.05). RESULTS. The material type, surface treatment type, and their interactions were found significant with regard to SBS (P<.001). Aging also had a significant effect on prosthetic material-resin composite bonding (P<.001). SBS values of non-aged specimens ranged from 12.16 to 17.91 MPa, while SBS values of aged specimens ranged from 9.46 to 15.61 MPa. Non-aged VM in combination with acid etching presented the highest score while the control group of aged CE showed the lowest. CONCLUSION. Etching was more effective in achieving durable SBS for VM and EC. Laser irradiation could be considered as an alternative surface treatment method to air abrasion for all tested materials. Aging had significant effect on SBS values generated between tested materials and resin composite.

• Journal of Computational Design and Engineering
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• v.3 no.4
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• pp.322-329
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• 2016

The advent of high-performance terrestrial laser scanners has made it possible to capture dense point-clouds of engineering facilities. 3D shape acquisition from engineering facilities is useful for supporting maintenance and repair tasks. In this paper, we discuss methods to reconstruct box shapes and polygonal prisms from large-scale point-clouds. Since many faces may be partly occluded by other objects in engineering plants, we estimate possible box shapes and polygonal prisms and verify their compatibility with measured point-clouds. We evaluate our method using actual point-clouds of engineering plants.

• Korean Journal of Acupuncture
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• v.27 no.1
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• pp.49-62
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• 2010

Objective: This study was performed to investigate the effect of manual acupuncture, invasive laser acupuncture and laser skin irradiation at LU8, LR4, HT8 and LR2(Liver Seunggyeok) on D-galN-induced liver injury in rats. Method: Liver injury was induced with D-galN. The experimental rats were divided four groups(Control group, EXP-1, EXP-2, EXP-3). In the Control group, liver injury-induced and not treated. EXP-1 group was liver injury-induced and carried out manual acupuncture with Young-Su(against the meridian course and following the course of the meridian) & Won-Bang(by twisting and rotating the needle) acupuncture method at Liver Seunggyeok. EXP-2 group was liver injury-induced and carried out invasive laser acupuncture at Liver Seunggyeok. EXP-3 group was liver injury-induced and carried out laser skin irradiation at Liver Seunggyeok. Result: In the change of body weight(in 1 week), EXP-1, EXP-2 and EXP-3 groups were significantly increased as compared with control group. In the change AST & ALT, EXP-1 and EXP-2 groups were significantly decreased as compared with control group. In the change of SOD, EXP-1, EXP-2 and EXP-3 groups were significantly increased as compared with control group. In the change of WBC, EXP-2 group was significantly increased as compared with control group. Conclusion: Manual acupuncture, invasive laser acupuncture and laser skin irradiation at Liver Seunggyeok had hepatotherapeutic effect on the treatment of hepatocytotoxity. Invasive laser acupuncture was as effective as manual acupuncture on the treatment of hepatocytotocity.

• Smart Structures and Systems
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• v.31 no.1
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• pp.79-88
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• 2023

As the number of deteriorated buildings increases, the importance of safety diagnosis, maintenance, and the repair of buildings also increases. Traditionally, building condition assessments are performed by one person or one company and various inspections are needed. This entails a subjective judgment by the inspector, resulting in different assessment results, poor objectivity and a lack of reliability. Therefore, this study proposed a method to bring about accurate grading results of building conditions. The limitations of visual inspection and condition assessment processes previously conducted were identified by reviewing existing studies. Building defect data was collected using the reverse-engineered three-dimensional (3D) model. The accuracy of the results was verified by comparing them with the actual evaluation results. The results show a 50% time-saving to the same area with an accuracy of approximately 90%. Consequently, defect data with high objectivity and reliability were acquired by measuring the length, area, and width. In addition, the proposed method can improve the efficiency of the building diagnosis process.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.64-67
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• 1997

In the total artificial heart(TAH), a transcutaneous information transmission system(TITS) is vely important to monitor the TAH status and detect the device failure, and repair the possible problems. First of all, the communication channel(skin) and method were simulated in terms of transmittance, scattering, reflection and absorption, then the system was designed with size reduction including low power consumption and reliability compared to the previous one. The informations are transmitted through the skin(approximately 1cm in depth) by frequency modulated near infrared(NIR) pulses using 780nm laser diodes as transmitters and photodiode as receiver with high speed and high spectral sensitivity. The logic high and low frequencies are 3MHz, 1MHz respectively. The system is a bidirectional data link for more than 38.4Kbps data rate, full-duplex with a bit error rate of less than $10^{-5}$.

• International Journal of Fluid Machinery and Systems
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• v.10 no.2
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• pp.146-153
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• 2017

Sediment flow through hydropower components causes hydro-abrasive erosion resulting in loss of efficiency, interruptions in power production and downtime for repair/maintenance. Online instruments are required to measure/capture the variations in sediment parameters along with collecting samples manually to analyse in laboratory for verification. In this paper, various sediment parameters viz. size, concentration (TSS), shape and mineral composition relevant to hydro-abrasive erosion were measured and discussed with respect to a hydropower plant in Himalayan region, India. A multi-frequency acoustic instrument was installed at a desilting chamber to continuously monitor particle size distribution (PSD) and TSS entering the turbine during 27 May to 6 August 2015. The sediment parameters viz. TSS, size distribution, mineral composition and shape entering the turbine were also measured and analysed, using manual samples collected twice daily from hydropower plant, in laboratory with instruments based on laser diffraction, dynamic digital image processing, gravimetric method, conductivity, scanning electron microscope, X-ray diffraction and turbidity. The acoustic instrument was able to capture the variation in TSS; however, significant deviations were found between measured mean sediment sizes compared to values found in the laboratory. A good relation was found for turbidity ($R^2=0.86$) and laser diffraction ($R^2=0.93$) with TSS, which indicated that turbidimeter and laser diffraction instrument can be used for continuous monitoring of TSS at the plant. Total sediment load passed through penstock during study period was estimated to be 15,500 ton. This study shall be useful for researchers and hydropower managers in measuring/monitoring sediment for hydro-abrasive erosion study in hydropower plants.