• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.435-441
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• 2021

This research was performed to study the effect of the Ni + Mo addition on the fatigue properties in 12Cr steel. After heat treatment of 12Cr steel and 12Cr-Ni-Mo steel, tensile tests, impact tests, hardness tests, and rotary bending fatigue tests were performed, respectively. The fatigue fracture surface was observed and analyzed using SEM and EDS. The fatigue limit of 12Cr steel was 554 MPa, which was 49 MPa higher than 505 MPa of 12Cr-Ni-Mo steel. Striations, which are the shape of the typical fatigue fracture surface, were observed at the fracture surface near the starting point of fatigue fracture in the 12Cr steel and 12Cr-Ni-Mo steel. However, unlike the case of 12Cr steel, 12Cr-Ni-Mo steel also had a mixed fracture surface with the fatigue and the ductile fracture surface. When brittle non-metallic inclusions exist near the starting point of fatigue failure, the crack propagation was further promoted and the fatigue life was drastically reduced.

• 대한상한금궤의학회지
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• v.13 no.1
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• pp.1-19
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• 2021

Purpose : Sayeok-tang (Sini decoction, SND) is a cold-dispelling formula used for cold deficiency syndrome and is composed of Aconiti Lateralis Radix Preperata, Zingiberis Rhizoma, and Glycyrrhizae Radix et Rhizoma. It is used for diseases such as myocardial infarction, heart failure, acute and chronic gastroenteritis, and gastric effusion. This study proposes the possibility of expansion of basic research and clinical applications for ischemic heart disease (IHD) through systematic analysis of domestic and foreign studies on SND. Methods : We collected studies within the last 10 years on the use of SND in IHD and excluded those lacking relevance. Selected studies were classified by research method and the main themes of the studies were analyzed for each classification. Result: Out of 15 studies, there were 5 animal studies, 8 metabolite analyses in animals, 1 in vitro study, and 1 systematic review. Our review suggests that SND may be used as an adjuvant to nitroglycerin and percutaneous transluminal coronary angioplasty, and may improve symptoms and quality of life of patients with IHD. Myocardial protective effects through antioxidant, anti-inflammatory, anti-apoptotic, and anti-hypertensive actions were confirmed through these studies. Effects on carbohydrate, protein, and lipid metabolism were also reported. Conclusions : This study suggests that SND has potential as a treatment for IHD.

• Childhood Kidney Diseases
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• v.25 no.2
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• pp.112-116
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• 2021

Hyperammonemia is mainly caused by diseases related to liver failure. However, there are also non-hepatic causes of hyperammonemia, such as urinary tract infection (UTI) due to urease-producing organisms. Urease production by these bacteria induces a hydrolysis of urinary urea into ammonia that can cross the urothelial cell membrane and diffuse into blood vessels, leading to hyperammonemia. Delayed diagnosis and treatment of hyperammonemia can lead to lethal encephalopathy that can cause brain damage and life-threatening conditions. In the presence of obstructive uropathy, UTI by urease-producing bacteria can lead to more severe hyperammonemia due to enhanced resorption of ammonia into the systemic circulation. In this report, we present a case of acute severe hyperammonemic encephalopathy leading to brain death due to accumulation of ammonia in blood caused by Morganella morganii UTI in a 10-year-old girl with cloacal anomaly, causing obstructive uropathy even after multiple corrections.

• Journal of Information Technology Services
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• v.21 no.1
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• pp.41-59
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• 2022

Metaverse which was not mentioned until recently due to the failure of 'Second Life' in the past is drawing attention again with the emergence and popularity of metaverse platforms such as 'Roblox' and 'Zeppetto'. On the other hand, there are concerns that past failures will still be repeated. In order to create and sustain the ecosystem surrounding the metaverse, it is important to diagnose and analyze the development process of the metaverse industry and market to define a clear concept that expresses the current metaverse boom. In this paper, the metaverse of the future is defined as "Metaverse 2.0: A virtual world that evolves into a 'Hyper world' through the convergence of hyper-connectivity, hyper-intelligence, and hyper-reality." And six issues that need to be resolved for the activation of the metaverse were analyzed. Based on the contents of this study, it is expected that the metaverse ecosystem will be formed and spread by establishing the roles of the public sector and the private sector.

• Structural Engineering and Mechanics
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• v.80 no.5
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• pp.563-583
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• 2021

Composite materials, composed of multiple constituent materials with dissimilar properties, are actively adopted in a wide range of industrial sectors due to their remarkable strength-to-weight and stiffness-to-weight ratio. Nevertheless, the failure mechanism of composite materials is highly complicated due to their sophisticated microstructure, making it much harder to predict their residual material lives in real life applications. A promising solution for this safety issue is structural damage detection. In the present paper, damage detection of composite material via electrical resistance-based technique and infrared thermography is reviewed. The operating principles of the two damage detection methodologies are introduced, and some research advances of each techniques are covered. The advancement of IR thermography-based non-destructive technique (NDT) including optical thermography, laser thermography and eddy current thermography will be reported, as well as the electrical impedance tomography (EIT) which is a technology increasingly drawing attentions in the field of electrical resistance-based damage detection. A brief comparison of the two methodologies based on each of their strengths and limitations is carried out, and a recent research update regarding the coupling of the two techniques for improved damage detection in composite materials will be discussed.

• Journal of the Korean Wood Science and Technology
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• v.31 no.3
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• pp.61-69
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• 2003

This study investigated the effect of moisture content and loading direction on dowel bearing strength of two types of SCL. Dowel bearing tests of LVL and PSL were conducted with two different MC level, 7.5% and 19%, and two different oriention, L-direction(loading parallel to grain) and X-direction(loading perpendicular to grain). Most of specimens showed typical load-deformation curves and intersected 5% offset line. Failure modes were classified into two categories; spliting(for L-direction specimens) and peeling(for X-direction specimens). Dowel bearing strength generally decreased with increasing MC. The decreasing rate was more significant in X-directon. ESG also decreased with increasing MC, and the ratio of ESG of 7.5% versus 19% was about 1.47. Dowel bearing strength of LVL and PSL in L-direction was higher than that of X-direction. This results indicated that MC and loading orientation had a significant effect on dowel bearing strength of SCL. The average dowel bearing strength of LVL were higher than that of PSL in each loading direction. Two types of probability distribution model were chosen to quantify strength distribution, normal and 2-parameter weibull distribution. The two models showed good agreement with the data, especially in lower tail of the cumulative distribution. Normal and 2-parameter weibull distribution seemed to proper model of the dowel bearing strength for each MC levels.

• Earthquakes and Structures
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• v.23 no.6
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• pp.503-515
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• 2022

Global or partial damage to a structure due to the failure of gravity or lateral load-bearing elements is called progressive collapse. In the present study, the alternate load path (ALP) method introduced by GSA and UFC 4-023-03 guidelines is used to evaluate the progressive collapse in special steel moment-resisting frame (SMRF) buildings. It was assumed that the progressive collapse is due to the earthquake force and its effects after the removal of the elements still remain on the structures. Therefore, nonlinear dynamic time history analysis employing 7 earthquake records is used to investigate this phenomenon. Internal and external column removal scenarios are investigated and the stiffness of the connections is changed from semi-rigid to rigid. The results of the analysis performed in the OpenSees program show that the loss of the bearing capacity of an exterior column due to a seismic event and the occurrence of progressive collapse can increase the inter-story drift of the structure with semi-rigid connections by more than 50% and make the structure unable to satisfy the life safety performance level. Furthermore, connection stiffness severely affects the redistribution of forces and moments in the adjacent elements of the removed column.

• International Journal of Advanced Culture Technology
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• v.10 no.1
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• pp.253-264
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• 2022

In the era of the pandemic, the importance of a wireless LAN environment has become increasingly important, especially as the era of smart working and non-face-to-face education has become a universal and daily routine. Smartphones, tablets, laptops, PCs, smart watches, and wearable devices, collective referred to as wireless terminals, can be accessed anytime and anywhere through the internet, allowing for consistent and constant access to offices, factories, warehouses, shopping malls, railways, hotels, hospitals, schools, logistics centers, airports, exhibition halls, etc. This sort of access is currently being used in roads, parks, traditional markets, and ports. Since the release of the IEEE 802.11 Legacy Standard in 1997, Wi-Fi technology has been continuously supplemented and revised, and the standard has been continuously developed. In the era of smart working, the importance of efficient wireless deployment and scientific design has become more important. The importance of wireless in the smart factory, in the metaverse era, in the era of pursuing work and life that transcend time and space by using AR, VR, MR, and XR, it is more urgent to solve the shadow area of Wi-Fi. Through this study, we intend to verify the wireless failure problem of the xr training center and suggest improvement measures.

• Geomechanics and Engineering
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• v.32 no.5
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• pp.523-540
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• 2023

The failure of slope can cause remarkable damage to either human life or infrastructures. Stabilizing piles are widely utilized to reinforce slope as a slip-resistance structure. The workability of pile-stabilized slopes is affected by various parameters. In this study, the performance of earth slope reinforced with piles and the behavior of piles under static load, by shear reduction strength method using the finite difference software (FLAC^3D) has been investigated. Parametric studies were conducted to investigate the role of pile length (L), different pile distances from each other (S/D), pile head conditions (free and fixed head condition), the effect of sand density (loose, medium, and high-density soil) on the pile behavior, and the performance of pile-stabilized slopes. The performance of the stabilized slopes was analyzed by evaluating the factor of safety, lateral displacement and bending moment of piles, and critical slip mechanism. The results depict that as L increased and S/D reduced, the performance of slopes stabilized with pile gets better by raising the soil density. The greater the amount of bending moment at the shallow depths of the pile in the fixed pile head indicates the effect of the inertial force due to the structure on the pile performance.

• Archives of Plastic Surgery
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• v.50 no.4
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• pp.422-431
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• 2023

Background Posttraumatic lymphedema (PTL) is sparsely described in the literature. The aim of this study is to propose a comprehensive approach for prevention and treatment of PTL using lymphovenous anastomosis (LVA) and lymphatic vessels free flap, reporting our experience in the management of early-stage lymphedema. Methods A retrospective observational study was performed between October 2017 and July 2022. Functional assessment with magnetic resonance lymphangiography and indocyanine green lymphography was performed. Patients with lymphedema and functional lymphatic channels were included. Cases with limited soft tissue damage were proposed for LVA, and those with acute or prior soft tissue damage needing skin reconstruction were proposed for superficial circumflex iliac artery perforator lymphatic vessels free flap (SCIP-LV) to treat or prevent lymphedema. Primary and secondary outcomes were limb volume reduction and quality of life (QoL) improvement, respectively. Follow-up was at least 1 year. Results Twenty-eight patients were operated using this approach during the study period. LVA were performed in 12 patients; mean reduction of excess volume (REV) was 58.82% and the improvement in QoL was 49.25%. SCIP-LV was performed in seven patients with no flap failure; mean REV was 58.77% and the improvement QoL was 50.9%. Nine patients with acute injury in lymphatic critical areas were reconstructed with SCIP-LV as a preventive approach and no lymphedema was detected. Conclusion Our comprehensive approach provides an organized way to treat patients with PTL, or at risk of developing it, to have satisfactory results and improve their QoL.