• The Journal of Korean Academy of Prosthodontics
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• v.45 no.1
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• pp.107-118
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• 2007

Statement of problem: Implant-type distractor uses a removable distraction device that has an appearance similar to that of a dental implant and utilizes many of the same techniques for placement as are used for dental implants. Material and method: In this study, 48 implant type titanium distractors were inserted into the osteotomized alveolar bone of 12 beagle dogs. After a 7-day latency period, the alveolar bone was augmented by 5mm vertically at a rate of 1.0 mm/day. The dogs were sacrificed after 4weeks, 8weeks and 12 weeks for radiographic, histologic, and histomorphometric analysis. Result: Copper equivalent value showed significant difference between 4 weeks and the other weeks(8, 12 weeks)(p<0.05). But there was no significant difference between maxillary and mandibular groups. In the bone to metal contact analysis, there was a significant difference between 4 weeks and 12 weeks(p<0.05). On the contrary, there was no significant difference between maxilla and mandible. The bone area showed significantly higher values in 12 weeks compared to 4 weeks(p<0.05). Histologically mineralization began at the host bone margins. At 12 weeks, increasing accumulation of $Ca^{++}$ element was confirmed. Conclusion: From the results above, the new bone formation was increased according to consolidation period. Especially there was significant difference between 4 weeks and 12 weeks(p<0.05). Implant type distractors used in this study to augment vertical ridge defect may prove to be a clinically useful treatment option in selected cases.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.27-33
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• 2017

This study is intended to identify issues on the basis of investigating the actual state of laboratory environment and outlet circuit, and derive end states by expressing sequences from the initiating event of disaster to accident in leakage current, poor contact and overload through ETA(event tree analysis). To this end, this study investigated the actual state of electric equipment of laboratory at universities in all parts of country. And it is shown that most of them are failure in electric work and user negligence in the investigation of actual state. It is found that there is earth fault and defect in wire diameter in the failure of electric work and the problem of partial disconnection due to wire bundling and poor contact in user negligence. Outlet-related component, failure rate and initiating events are composed of a total of 41 initiating events, i.e., 30 internal initiating events and 11 external initiating events. And end states are composed of a total of 15 parts, i.e., 3 electric power parts and 12 safety parts. Earthing class 3 is the most important safety device against leakage current (initiating event). And in case of poor contact, it is necessary for manager to check thoroughly because there is no safety device. In case of overload/overcurrent, when high-capacity equipment is connected, a molded case circuit breaker, safety device, worked. However, in most cases, it is verified that this doesn't work. This study can be utilized as electric equipment safety guide for laboratory safety manager and managers.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.7
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• pp.7-15
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• 2020

Recently, the fourth industrial revolution has been presented as a new paradigm and additive manufacturing (AM) has become one of the most important topics. For this reason, process monitoring for each cross-sectional layer of additive metal manufacturing is important. Particularly, deep learning can train a machine to analyze, optimize, and repair defects. In this paper, image classification is proposed by learning images of defects in the metal cross sections using the convolution neural network (CNN) image labeling algorithm. Defects were classified into three categories: crack, porosity, and hole. To overcome a lack-of-data problem, the amount of learning data was augmented using a data augmentation algorithm. This augmentation algorithm can transform an image to 180 images, increasing the learning accuracy. The number of training and validation images was 25,920 (80 %) and 6,480 (20 %), respectively. An optimized case with a combination of fully connected layers, an optimizer, and a loss function, showed that the model accuracy was 99.7 % and had a success rate of 97.8 % for 180 test images. In conclusion, image labeling was successfully performed and it is expected to be applied to automated AM process inspection and repair systems in the future.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.67-73
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• 2014

Due to the development of the communication technology and the high-performance mobile device, the number of video streaming service user has been increasing. Video streaming services in the restricted network environments need error control to support users for the Ultra High Definition(UHD) video delivery. Packet-level FEC method was used to control the error for delay-sensitive video service, but it has a defect in huge occupation of network resources by redundant packets. In this paper, we proposed a packet-level FEC algorithm which maintains the video quality by previous FEC methods and also reduces the occupation of network resource in the restricted network environments. The proposed algorithm controls the redundant rate with using the delivery characteristic of the video coding technology, and improves the efficiency of network resources by reducing the traffic by around 33% in comparison with the previous FEC methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.185-188
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• 2001

Chemical mechanical polishing(CMP) process is widely used for global planarization of inter-metal dielectric (IMD) layer and inter-layer dielectric (ILD) for deep sub-micron technology. However, as the IMD and ILD layer gets thinner, defects such as micro-scratch lead to severe circuit failure, which affect yield. In this paper, for the improvement of CMP process, deionized water (DIW) pressure, purified $N_2 \; (PN_2)$ gas, slurry filter and high spray bar were installed. Our experimental results show that DIW pressure and $PN_2$ gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. Also, the filter installation in CMP polisher could reduce defects after CMP process, it is shown that slurry filter plays an important role in determining consumable pad lifetime. The filter lifetime is dominated by the defects. However, the slurry filter is impossible to prevent defect-causing particles perfectly. Thus, we suggest that it is necessary to install the high spray bar of de-ionized water (DIW) with high pressure, to overcome the weak-point of slurry filter. Finally, we could expect the improvements of throughput, yield and stability in the ULSI fabrication process.

• Design & Manufacturing
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• v.13 no.4
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• pp.57-62
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• 2019

In this study, we investigated the halo surface defection of various phenomenon occurred during the injection molding process which is caused by the thinning of the product thickness and the importance of the appearance. Surface analysis was performed to observe the difference between the surface where defects appeared and the surface which did not appear. Based on these results, we analyzed the phenomenon of halo surface defects was caused by unstable flow of resin generated in injection molding and velocity change of flow front. Furthermore, we will conduct a clear analysis of halo surface defects through observations through optical microscopy and subsequent observations with atomic force microscope. It has been analyzed that halo in PP is due to the rheological difference between the crystalline and amorphous regions while that in PC/ABS is due to shear separation of PC and ABS.

• Clinical and Experimental Pediatrics
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• v.61 no.6
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• pp.200-204
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• 2018

Atopic dermatitis (AD) is a chronic inflammatory skin disease in children. Patients with AD experience a high rate of colonization of the skin surface by Staphylococcus aureus. Because of a skin barrier defect, there is a potential risk of staphylococcal invasive infection in patients with AD. Here, we present 2 cases of breast abscess caused by S. aureus in 2 adolescent girls with severe AD. Methicillin-sensitive S. aureus was identified from the breast abscess material. They were treated with appropriate antibiotics, however surgical drainage of the abscess was needed in case 1. Identical strains were found from the breast abscess material as well as the lesional and the nonlesional skin of the patients through matrix-assisted laser desorption/ionization time-of-flight analysis. We characterized the differential abundance of Firmicutes phylum in patients' skin in microbiota analysis. In particular, S. aureus, a member of Firmicutes, differed significantly between the lesional and the normal-appearing skin. Our cases demonstrate the potential severity of bacterial deep tissue infection in AD and the dysbiosis of skin microbiota may be involved in inflammation in AD.

• Archives of Plastic Surgery
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• v.41 no.4
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• pp.337-343
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• 2014

Background The reconstruction of large skin and soft tissue defects on the lower extremities is challenging. The skin graft is a simple and frequently used method for covering a skin defect. However, poor skin quality and architecture are well-known problems that lead to scar contracture. The collagen-elastin matrix, Matriderm, has been used to improve the quality of skin grafts; however, no statistical and objective review of the results has been reported. Methods Thirty-four patients (23 male and 11 female) who previously received a skin graft and simultaneous application of Matriderm between January 2010 and June 2012 were included in this study. The quality of the skin graft was evaluated using Cutometer, occasionally accompanied by pathologic findings. Results All 34 patients showed good skin quality compared to a traditional skin graft and were satisfied with their results. The statistical data for the measurement of the mechanical properties of the skin were similar to those for normal skin. In addition, there was no change in the engraftment rate. Conclusions The biggest problem of a traditional skin graft is scar contracture. However, the dermal matrix presents an improvement in skin quality with elastin and collagen. Therefore, a skin graft along with a simultaneous application of Matriderm is safe and effective and leads to a significantly better outcome from the perspective of skin elasticity.

• Archives of Plastic Surgery
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• v.40 no.3
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• pp.238-243
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• 2013

Background Primary malignant tumors of the hand, although unusual, may present varied and often complex clinical problems. The main treatment modality of skin cancer of the hand has changed. Methods We retrospectively reviewed the medical records of 43 patients who underwent surgery for malignant skin tumors of the hand during an 18-year period, from September 1994 to February 2012. The characteristics of the tumor, methods of reconstruction, and long-term results were reviewed. Results We had 43 patients with 27 melanomas, 14 squamous cell carcinomas, and 2 sarcomas. Their ages ranged from 19 to 74 years (mean, $53.4{\pm}14.5$ years), from 46 to 79 years (mean, $59.7{\pm}9.6$ years), and from 15 to 43 years (mean, $29{\pm}19.8$ years), respectively. Thirty-four cases occurred on the fingertip (16 of those cases on the thumb), 5 cases occurred on the palm, and 4 cases on the dorsum of the hand. Amputation was most frequently used in early cases, but recently, tissue-sparing excision has been performed frequently. The incidence of local recurrence was 3 cases and distant metastasis was 1 case, and the 5-year survival rate was 100%, except in 4 cases due to follow-up loss. Conclusions The principles of treatment-to be curative and to preserve function and appearance-are important points. "Preservative surgery" preserves function and cosmesis of the involved finger or hand dorsum or palm. Preservative surgery not only emphasizes less resection and surgery of a smaller scale, but also optimal reconstruction of the soft tissue defect of the digit.

• Journal of Korean Society for Quality Management
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• v.48 no.2
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• pp.297-307
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• 2020

Purpose: The purpose of this study is to analyze the factors that affect ammunition performance by applying data mining techniques to the Ammunition Stockpile Reliability Program (ASRP) data of the 155mm propelling charge. Methods: The ASRP data from 1999 to 2017 have been utilized. Logistic regression and decision tree analysis were used to investigate the factors that affect performance of ammunition. The performance evaluation of each model was conducted through comparison with an artificial neural networks(ANN) model. Results: The results of this study are as follows; logistic regression and the decision tree analysis showed that major defect rate of visual inspection is the most significant factor. Also, muzzle velocity by base charge and muzzle velocity by increment charge are also among the significant factors affecting the performance of 155mm propelling charge. To validate the logistic regression and decision tree models, their classification accuracies have been compared with the results of an ANN model. The results indicate that the logistic regression and decision tree models show sufficient performance which conforms the validity of the models. Conclusion: The main contribution of this paper is that, to our best knowledge, it is the first attempt at identifying the significant factors of ASPR data by using data mining techniques. The approaches suggested in the paper could also be extended to other types ammunition data.