• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.491-497
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• 2016

This study aims to develop a vision inspection system for screw threads. To inspect external defects in screw threads, the vision inspection system was developed using front light illumination from which bright images can be obtained. The front light system, however, requires multiple side images for inspection of the entire thread surface, which can be performed by omnidirectional optics. In this study, an omnidirectional optical system was designed to obtain annular images of screw threads using an image sensor and two reflection mirrors; one large concave mirror and one small convex mirror. Optical simulations using backward and forward ray tracing were performed to determine the dimensional parameters of the proposed optical system, so that an annular image of the screw threads could be obtained with high quality and resolution. Microscale surface defects on the screw threads could be successfully detected using the developed annular inspection system.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.10
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• pp.353-360
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• 2016

Recently, solar photovoltaic(PV) power generation which generates electrical power from solar panels composed of multiple solar cells, showed the most prominent growth in the renewable energy sector worldwide. However, in spite of increased demand and need for a photovoltaic power generation, it is difficult to early detect defects of solar panels and equipments due to wide and irregular distribution of power generation. In this paper, we choose an optimal machine learning algorithm for estimating the generation amount of solar power by considering several panel information and climate information and develop a defect detection system by using the chosen algorithm generation. Also we apply the algorithm to a domestic solar photovoltaic power plant as a case study.

• Smart Structures and Systems
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• v.4 no.4
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• pp.449-464
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• 2008

An array based, outward monitoring, ultrasonic guided wave based SHM technique using a single transmitter and multiple receivers (STMR), with a small footprint is discussed here. The previous implementation of such SHM arrays used a phase-reconstruction algorithm (that is similar to the beam-steering algorithm) for the imaging of reflectors. These algorithms were found to have a limitation during the imaging of defects/reflectors that are present in the "near-field" of the array. Here, the "near-field" is defined to be approximately 3-4 times the diameter of the compact array. This limitation is caused by approximations in the beam-steering reconstruction algorithm. In this paper, a migration-based reconstruction algorithm, with dispersion correction in the frequency domain, is discussed. Simulation and experimental studies are used to demonstrate that this algorithm improves the reconstruction in the "near-field" without decreasing the ability to reconstruct defects in the "far-field" in both isotropic and anisotropic plates.

• International Journal of Korean Welding Society
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• v.1 no.2
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• pp.36-44
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• 2001

To get the appropriate welding process variables, mathematical modeling in conjunction with many experiments is necessary to predict the magnitude of weld bead shape. Even though the experimental results are reliable, it has a difficulty in accurately predicting welding process variables for the desired weld bead shape because of nonlinear and complex characteristics of welding processes. The welding condition determined for the desired weld bead shape may cause the weld defect if the welding current/voltage/speed combination is improperly selected. In this study, the $2^{n-1}$ fractional factorial design method and correlation parameter were used to investigate the effect of the welding process variables on the fillet joint shape, and the multiple non-linear regression analysis was used for modeling the gas metal arc welding(GMAW）parameters of the fillet joint. Finally, a fuzzy rule-based method and a neural network method were proposed so that the complexity and non-linearity of arc welding phenomena could be effectively overcome. The performance of the proposed neuro-fuzzy system was evaluated through various experiments. The experimental results showed that the proposed neuro-fuzzy system could effectively check the welding conditions as to whether or not weld defects would occur, and also adjust the welding conditions to avoid these weld defects.

• Archives of Plastic Surgery
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• v.45 no.3
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• pp.253-258
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• 2018

Background The nasolabial flap is ideal for reconstruction of the nasal alar subunit due to its proximity, color and contour match, and well-placed donor scar. When raised as a random-pattern flap, there is a risk of vascular compromise to the tip with increased flap length and aggressive flap thinning. Surgical delay can greatly improve the chances of tip survival, allowing the harvest of longer flaps with greater reach. Methods We describe our technique of lengthening the nasolabial flap through multiple delay procedures. A bipedicled flap was first raised and then transferred as a unipedicled flap with a 6:1 length-to-width ratio. During the delay process, the flap tip was thinned to the subdermal layer. Results In our case series of seven patients, defects as far as the medial canthal area and contralateral ala were reconstructed successfully with no incidence of tip necrosis or flap loss. The resultant flaps were thin enough to be folded over for the reconstruction of alar rim defects. Conclusions We highlight the success of our surgical technique in creating thin and robust nasolabial flaps for the reconstruction of full-thickness defects around the nose.

• International journal of advanced smart convergence
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• v.12 no.2
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• pp.47-55
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• 2023

The automotive industry is undergoing a paradigm shift due to the convergence of IT and rapid digital transformation. Various components, including embedded structures and systems with complex architectures that incorporate IC semiconductors, are being integrated and modularized. As a result, there has been a significant increase in vehicle defects, raising expectations for the quality of automotive parts. As more and more data is being accumulated, there is an active effort to go beyond traditional reliability analysis methods and apply machine learning models based on the accumulated big data. However, there are still not many cases where machine learning is used in product development to identify factors of defects in performance and durability of products and incorporate feedback into the design to improve product quality. In this paper, we applied a prediction algorithm to the defects of automotive door devices equipped with automatic responsive sensors, which are commonly installed in recent electric and hydrogen vehicles. To do so, we selected test items, built a measurement emulation system for data acquisition, and conducted comparative evaluations by applying different machine learning algorithms to the measured data. The results in terms of R² score were as follows: Ordinary multiple regression 0.96, Ridge regression 0.95, Lasso regression 0.89, Elastic regression 0.91.

• Clinical and Experimental Pediatrics
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• v.56 no.4
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• pp.176-181
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• 2013

Purpose: Apical muscular ventricular septal defects (MVSDs), especially in small infants, can be difficult to manage using surgical and percutaneous closure. An intraoperative perventricular procedure is a good option for closing apical MVSDs in small children with or without associated cardiac anomalies. We evaluated the results of hybrid perventricular closure of apical MVSDs performed using an Amplatzer duct occluder (ADO). Methods: We retrospectively reviewed the medical records of 5 patients who underwent hybrid perventricular closure of MVSDs with ADOs, from March 2006 to May 2011. The median patient age at the time of the procedure was 12 months (range, 25 days to 25 months), and the median body weight was 9.1 kg (range, 4.3 to 15 kg). Two patients had multiple ventricular septal defects (VSDs; additional perimembranous VSD in 1 patient and multiple MVSDs in the other) and 3 patients had associated cardiac anomalies; complete transposition of the great arteries in 1 patient and an atrial septal defect in 2 patients. All the procedures were performed on beating hearts, exception in 1 case. The ADO selected for the aortic side was at least 1 to 2 mm larger than the largest VSD in the left ventricle side. Results: The procedure was successful in all patients and each device was well positioned. During the median follow-up of 2.4 years, a small residual VSD was noted in 2 patients who had multiple VSDs and no leakage was seen in the other 3 patients. Conclusion: Perventricular closure of MVSD with an ADO is a good option for patients with apical MVSD. However, careful manipulation is important, especially in the case of small infants.

• Archives of Plastic Surgery
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• v.49 no.1
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• pp.61-69
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• 2022

Background Single free flaps are a commonly used reconstructive method for multiple soft tissue defects in digits. We analyzed the flap size, division timing, and degree of necrosis in cases with various types of flap division. Methods We conducted a retrospective review of the medical charts of patients who had undergone single free flap reconstruction for multiple soft tissue defects across their digits from 2011 to 2020. The flap types included were the lateral arm free flap, venous forearm free flap, thenar free flap, hypothenar free flap, anterolateral thigh free flap, medial plantar free flap, and second toe pulp free flap. Flap size, anastomosed vessels, division timing, and occurrence of flap necrosis were retrospectively investigated and then analyzed using the t-test. Results In total, 75 patients were included in the analysis. The success rate of the free flaps was 97.3%. All flaps were successfully divided after at least 17 days, with a mean of 47.17 days (range, 17-243 days) for large flaps and 42.81 days (range, 20-130 days) for the medium and small flaps (P=0.596). The mean area of flap necrosis was 2.38% in the large flaps and 2.58% in the medium and small flaps (P=0.935). Severe necrosis of the divided flap developed in two patients who had undergone flap division at week 6 and week 34. Conclusions In cases where blood flow to the flap has been stable for more than 3 weeks, flap division can be safely attempted regardless of the flap size.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.69-72
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• 2004

There are an electronic and a manual type in Bidet. The electronic bidet has some advantages. it supplies multiple functions and is up easily. However, it has frequent defects and a high price. The manual bidet is not need to supply electric and is cheaper than the electronic type. However, it is needed to supply hot water and is hard to set up. In order to solve these defects, this study designed a bidet heating unit using an electric instantaneous water heating method. To get a proper heating elements, experiments were performed about a Ni-Cr heater and a film heater.

• Archives of Craniofacial Surgery
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• v.20 no.6
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• pp.416-420
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• 2019

Reconstruction method choice in recurrent head and neck cancer depends on surgical history, radiation therapy dosage, conditions of recipient vessels, and general patient condition. Furthermore, when defects are multiple or three dimensional in nature, reconstruction and flap choice aimed at rebuilding the functional structure of the head and neck are difficult. We experienced successful reconstruction of recurrent laryngeal cancer requiring reconstruction of esophageal and tracheostomy stroma defects using a chimeric two-skin anterolateral thigh flap with a single pedicle.