• Archives of Plastic Surgery
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• 제45권1호
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• pp.62-68
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• 2018

Background Amputation is commonly performed for toe necrosis secondary to peripheral vascular diseases, such as diabetes mellitus. When amputating a necrotic toe, preservation of the bony structure is important for preventing the collapse of adjacent digits into the amputated space. However, in the popular terminal Syme's amputation technique, partial amputation of the distal phalanx could cause increased tension on the wound margin. Herein, we introduce a new way to resect sufficient bony structure while maintaining the normal length, based on a morphological analysis of the toes. Methods Unlike the pulp of the finger in the distal phalanx, the toe has abundant teardrop-shaped pulp tissue. The ratio of the vertical length to the longitudinal length in the distal phalanx was compared between the toes and fingers. Amputation was performed at the proximal interphalangeal joint level. Then, a mobilizable pulp flap was rotated $90^{\circ}$ cephalad to replace the distal soft tissue defect. This modified toe fillet flap was performed in 5 patients. Results The toe pulp was found to have a vertically oriented morphology compared to that of the fingers, enabling length preservation through cephalad rotation. All defects were successfully covered without marginal ischemia. Conclusions While conventional toe fillet flap coverage focuses on the principle of length preservation as the first priority, our modified method takes both wound healing and length into account. The fattiest part of the pulp is advanced to the toe tip, providing a cushioning effect and enough length to substitute for phalangeal bone loss. Our modified method led to satisfactory functional and aesthetic outcomes.

• Computers and Concrete
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• 제10권1호
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• pp.1-18
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• 2012

This paper presents the details of studies conducted on hollow concrete block masonry (HCBM) units and wall panels. This study includes, compressive strength of unit block, ungrouted and grouted HCB prisms, flexural strength evaluation, testing of HCBM panels with and without opening. Non-linear finite element (FE) analysis of HCBM panels with and without opening has been carried out by simulating the actual test conditions. Constant vertical load is applied on the top of the wall panel and then lateral load is applied in incremental manner. The in-plane deformation is recorded under each incremental lateral load. Displacement ductility factors and response reduction factors have been evaluated based on experimental results. From the study, it is observed that fully grouted and partially reinforced HCBM panel without opening performed well compared to other types of wall panels in lateral load resistance and displacement ductility. In all the wall panels, shear cracks originated at loading point and moved towards the compression toe of the wall. The force reduction factor of a wall panel with opening is much less when compared with fully reinforced wall panel with no opening. The displacement values obtained by non-linear FE analysis are found to be in good agreement with the corresponding experimental values. The influence of mortar joint has been included in the stress-strain behaviour as a monolith with HCBM and not considered separately. The derived response reduction factors will be useful for the design of reinforced HCBM wall panels subjected to lateral forces generated due to earthquakes.

• Imaging Science in Dentistry
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• 제48권4호
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• pp.255-259
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• 2018

Purpose: This study proposes a new ball-type phantom for evaluation of the image layer of panoramic radiography. Materials and Methods: The arch shape of an acrylic resin phantom was derived from average data on the lower dental arch in Korean adult males. Metal balls with a 2-mm diameter were placed along the center line of the phantom at a 4-mm mesiodistal interval. Additional metal balls were placed along the 22 arch-shaped lines that ran parallel to the center line at 2-mm buccolingual intervals. The height of each ball in the horizontal plane was spaced by 2.5 mm, and consequently, the balls appeared oblique when viewed from the side. The resulting phantom was named the Panorama phantom. The distortion rate of the balls in the acquired image was measured by automatically calculating the difference between the vertical and horizontal length using $MATLAB^{(R)}$. Image layer boundaries were obtained by applying various distortion rate thresholds. Results: Most areas containing metal balls (91.5%) were included in the image layer with a 50% distortion rate threshold. When a 5% distortion rate threshold was applied, the image layer was formed with a small buccolingual width along the arch-shaped center line. However, it was medially located in the temporomandibular joint region. Conclusion: The Panorama phantom could be used to evaluate the image layer of panoramic radiography, including all mesiodistal areas with large buccolingual width.

• 대한구강악안면병리학회지
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• 제42권5호
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• pp.145-152
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• 2018

A 57 years old female complained of severe pain on the right temporomandibular joint (TMJ) area. Her right condyle had been partly resected under surgical operation 13 years ago due to condyle hypertrophy, thereafter she felt dull pain on TMJ area and recently the lesion became severely swelled and painful leading to cancer phobia. The present radiological views showed slightly enlarged and sclerosed condyle with increased radiopacity, but its articular sliding function was almost disable during mouth opening. The patient's TMJ lesion was carefully managed with conservative physiotherapy and pain treatment. The microsection of condyle head obtained from the previous operation was re-evaluated histologically, and it was finally diagnosed as osteochondrosis dissecans (OCD), exhibiting hyperplastic proliferation of cartilage in condyle head and marked vascular dilatation in epiphyseal zone. This abnormal cartilage tissue was distinguishable from normal cartilage tissue found in the peripheral cartilaginous cap of the same microsection. The involved cartilage cap showed thick hypertrophic chondrocyte zone with horizontal and vertical clefts accompanying diffuse hyaline degeneration. The superficial fibrous zone of cartilage cap was thickened and frequently peeled off, while lower hypertrophic zone of cartilage cap was highly cellular and proliferative. Consequently, the endochondral ossification became aberrant and resulted pre-mature apoptosis of many hypertrophic chondrocytes, followed by diffuse and mild inflammatory reaction in the underlying marrow tissue. Therefore, it was suggested that this hypertrophic condyle lesion, OCD, be differentiated depending on radiological and histological features from ordinary condyle hyperplasia, osteochondroma, and osteoarthritis, and that the pathological confirmation of OCD may provide a reliable modality for dental and medical treatment of chronic and painful TMJ lesion.

• Journal of Korean Neurosurgical Society
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• 제62권5호
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• pp.567-576
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• 2019

Objective : Minimal data exist regarding non-operative management of suspected pseudarthrosis after pedicle subtraction osteotomy (PSO). This study reports radiographic and clinical outcomes of non-operative management for post-PSO pseudarthrosis at a minimum 5 years post-detection. Methods : Nineteen consecutive patients with implant breakage indicating probable pseudarthrosis after PSO surgery (13 women/six men; mean age at surgery, 58 years) without severe pain and disability were treated with non-operative management (mean follow-up, 5.8 years; range, 5-10 years). Non-operative management included medication, intermittent brace wearing and avoidance of excessive back strain. Radiographic and clinical outcomes analysis was performed. Results : Sagittal vertical axis (SVA), proximal junctional angle, thoracic kyphosis achieved by a PSO were maintained after detection of pseudarthrosis through ultimate follow-up. Lumbar lordosis and PSO angle decreased at final follow-up. There was no significant change in Oswestry Disability Index (ODI) scores and Scoliosis Research Society (SRS) total score, or subscales of pain, self-image, function, satisfaction and mental health between detection of pseudarthrosis and ultimate follow-up. SVA greater than 11 cm showed poorer ODI and SRS total score, as well as the pain, self-image, and function subscales (p<0.05). Conclusion : Non-operative management of implant failure of probable pseudarthrosis after PSO offers acceptable outcomes even at 5 years after detection of implant breakage, provided SVA is maintained. As SVA increased, outcome scores decreased in this patient population.

• 대한치과교정학회지
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• 제52권1호
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• pp.29-41
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• 2022

Objective: Condylar resorption (CR) is one of the major post-surgical complications of orthognathic surgery. This systematic review (SR) aimed to evaluate epidemiological data, risk factors, and therapeutical management of CR. Methods: Six databases were screened by two investigators until September 2020 to obtain all SRs. After reading the titles and abstracts, eligible SRs were determined and data extraction was performed. Using the latest version of A Measurement Tool to Assess Systematic Reviews, the methodological quality of the included SRs was determined. Results: Ten SRs with low or critically-low methodological quality were included in this review. Mandibular hypoplasia on the sagittal plane and hyperdivergent growth pattern on the vertical plane were the most common skeletal alterations in which CR could occur after orthognathic surgery. Post-operative condylar changes were analyzed both on two-dimensional and three-dimensional (3D) radiographic examinations. The incidence of CR was not related to the fixation method. Based on the severity of the pathological conditions, management of CR can include conservative or surgical therapy. Conclusions: Despite the limited evidence in literature, CR is considered a consequence of orthognathic surgery. However, an accurate diagnosis of CR and a better orthognathic surgical planning must include 3D radiographic examinations to improve pre- and post-surgical comparison. Well-designed studies with long-term follow-up and 3D data are needed to clarify the findings of this analysis..

• Geomechanics and Engineering
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• 제27권5호
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• pp.497-509
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• 2021

A large deformation FEM (Finite Element Method) based numerical analysis has been performed to study the behaviour of the bell-shaped anchor embedded in undrained saturated (cohesive) soil with the help of finite element based software ABAQUS. A typical model anchor with bell-diameter of 0.125 m, embedded in undrained saturated soil with varying cohesive strength (from 5 kN/m² to 200 kN/m²) has been chosen for studying the characteristic behaviour of the bell-shaped anchor installed in cohesive soil. Breakout factors have been evaluated for each case and verified with the results of experimental model tests for three different types of soil samples. The maximum value of breakout factor was found as about 8.5 within a range of critical embedment ratio of 2.5 to 3. An explicit model has been developed to estimate the breakout factor (F_c) for uplift capacity of bell-shaped anchor within clay mass in terms of H/D ratio (embedment ratio). It was also found that, the ultimate uplift capacity of the anchor increases with the increase of the value of cohesive strength of the soil and H/D ratio. The empirical equation developed in the present investigation is usable within the range of cohesion value and H/D ratio from 5 kN/m² to 200 kN /m² and 0.5 to 3.0 respectively. The proposed model has been validated against data obtained from a series of model tests carried out in the present investigation. From the stress-profile analysis of the soil mass surrounding the anchor, occurrence of stress concentration is found to be generated at the joint of anchor shaft and bell. It was also found that the vertical and horizontal stresses surrounding the anchor diminish at about a distance of 0.3 m and 0.15 m respectively.

• 반도체디스플레이기술학회지
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• 제21권4호
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• pp.65-70
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• 2022

In manufacturing and semiconductor industries, transfer robots increase productivity through accurate and continuous work. Due to the nature of the semiconductor process, there are environments where humans cannot intervene to maintain internal temperature and humidity in a clean room. So, transport robots take responsibility over humans. In such an environment where the manpower of the process is cutting down, the lack of maintenance and management technology of the machine may adversely affect the production, and that's why it is necessary to develop a technology for the machine failure diagnosis system. Therefore, this paper tries to identify various causes of failure of transport robots that are widely used in semiconductor automation, and the Prognostics and Health Management (PHM) method is considered for determining and predicting the process of failures. The robot mainly fails in the driving unit due to long-term repetitive motion, and the core components of the driving unit are motors and gear reducer. A simulation drive unit was manufactured and tested around this component and then applied to 6-axis vertical multi-joint robots used in actual industrial sites. Vibration data was collected for each cause of failure of the robot, and then the collected data was processed through signal processing and frequency analysis. The processed data can determine the fault of the robot by utilizing machine learning algorithms such as SVM (Support Vector Machine) and KNN (K-Nearest Neighbor). As a result, the PHM environment was built based on machine learning algorithms using SVM and KNN, confirming that failure prediction was partially possible.

• Earthquakes and Structures
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• 제24권6호
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• pp.439-453
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• 2023

Older brick masonry structures generally suffer from low strength defects. Using a cement mortar layer (CML) or steel-meshed cement mortar layer (S-CML) to reinforce existing low-strength brick masonry structures (LBMs) is still an effective means of increasing seismic performance. However, performance indices such as lateral displacement ratios and skeleton curves for LBMs reinforced with CML or S-CML need to be clarified in performance-based seismic design and evaluation. Therefore, research into the failure mechanisms and seismic performance of LBMs reinforced with CML or S-CML is imperative. In this study, thirty low-strength brick walls (LBWs) with different cross-sectional areas, bonding mortar types, vertical loads, and CML/S-CML thicknesses were constructed. The failure modes, load-carrying capacities, energy dissipation capacity and lateral drift ratio limits in different limits states were acquired via quasi-static tests. The results show that 1) the primary failure modes of UBWs and RBWs are "diagonal shear failure" and "sliding failure through joints." 2) The acceptable drift ratios of Immediate Occupancy (IO), Life Safety (LS), and Collapse Prevention (CP) for UBWs can be 0.04%, 0.08%, and 0.3%, respectively. For 20-RBWs, the acceptable drift ratios of IO, LS, and CP for 20-RBWs can be 0.037%, 0.09%, and 0.41%, respectively. Moreover, the acceptable drift ratios of IO, LS, and CP for 40-RBWs can be 0.048%, 0.09%, and 0.53%, respectively. 3) Reinforcing low-strength brick walls with CML/S-CML can improve brick walls' bearing capacity, deformation, and energy dissipation capacity. Using CML/S-CML reinforcement to improve the seismic performance of old masonry houses is a feasible and practical choice.

• 마케팅과학연구
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• 제19권1호
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• pp.37-46
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• 2009

The Census Bureau of the Department of Commerce announced in May 2008 that U.S. retail e-commerce sales for 2006 reached $ 107 billion, up from $ 87 billion in 2005 - an increase of 22 percent. From 2001 to 2006, retail e-sales increased at an average annual growth rate of 25.4 percent. The explosive growth of E-Commerce has caused profound changes in marketing channel relationships and structures in many industries. Despite the great potential implications for both academicians and practitioners, there still exists a great deal of uncertainty about the impact of the Internet channel introduction on distribution channel management. The purpose of this study is to investigate how the ownership of the new Internet channel affects the existing channel members and consumers. To explore the above research questions, this study conducts well-controlled mathematical experiments to isolate the impact of the Internet channel by comparing before and after the Internet channel entry. The model consists of a monopolist manufacturer selling its product through a channel system including one independent physical store before the entry of an Internet store. The addition of the Internet store to this channel system results in a mixed channel comprised of two different types of channels. The new Internet store can be launched by the independent physical store such as Bestbuy. In this case, the physical retailer coordinates the two types of stores to maximize the joint profits from the two stores. The Internet store also can be introduced by an independent Internet retailer such as Amazon. In this case, a retail level competition occurs between the two types of stores. Although the manufacturer sells only one product, consumers view each product-outlet pair as a unique offering. Thus, the introduction of the Internet channel provides two product offerings for consumers. The channel structures analyzed in this study are illustrated in Fig.1. It is assumed that the manufacturer plays as a Stackelberg leader maximizing its own profits with the foresight of the independent retailer's optimal responses as typically assumed in previous analytical channel studies. As a Stackelberg follower, the independent physical retailer or independent Internet retailer maximizes its own profits, conditional on the manufacturer's wholesale price. The price competition between two the independent retailers is assumed to be a Bertrand Nash game. For simplicity, the marginal cost is set at zero, as typically assumed in this type of study. In order to explore the research questions above, this study develops a game theoretic model that possesses the following three key characteristics. First, the model explicitly captures the fact that an Internet channel and a physical store exist in two independent dimensions (one in physical space and the other in cyber space). This enables this model to demonstrate that the effect of adding an Internet store is different from that of adding another physical store. Second, the model reflects the fact that consumers are heterogeneous in their preferences for using a physical store and for using an Internet channel. Third, the model captures the vertical strategic interactions between an upstream manufacturer and a downstream retailer, making it possible to analyze the channel structure issues discussed in this paper. Although numerous previous models capture this vertical dimension of marketing channels, none simultaneously incorporates the three characteristics reflected in this model. The analysis results are summarized in Table 1. When the new Internet channel is introduced by the existing physical retailer and the retailer coordinates both types of stores to maximize the joint profits from the both stores, retail prices increase due to a combination of the coordination of the retail prices and the wider market coverage. The quantity sold does not significantly increase despite the wider market coverage, because the excessively high retail prices alleviate the market coverage effect to a degree. Interestingly, the coordinated total retail profits are lower than the combined retail profits of two competing independent retailers. This implies that when a physical retailer opens an Internet channel, the retailers could be better off managing the two channels separately rather than coordinating them, unless they have the foresight of the manufacturer's pricing behavior. It is also found that the introduction of an Internet channel affects the power balance of the channel. The retail competition is strong when an independent Internet store joins a channel with an independent physical retailer. This implies that each retailer in this structure has weak channel power. Due to intense retail competition, the manufacturer uses its channel power to increase its wholesale price to extract more profits from the total channel profit. However, the retailers cannot increase retail prices accordingly because of the intense retail level competition, leading to lower channel power. In this case, consumer welfare increases due to the wider market coverage and lower retail prices caused by the retail competition. The model employed for this study is not designed to capture all the characteristics of the Internet channel. The theoretical model in this study can also be applied for any stores that are not geographically constrained such as TV home shopping or catalog sales via mail. The reasons the model in this study is names as "Internet" are as follows: first, the most representative example of the stores that are not geographically constrained is the Internet. Second, catalog sales usually determine the target markets using the pre-specified mailing lists. In this aspect, the model used in this study is closer to the Internet than catalog sales. However, it would be a desirable future research direction to mathematically and theoretically distinguish the core differences among the stores that are not geographically constrained. The model is simplified by a set of assumptions to obtain mathematical traceability. First, this study assumes the price is the only strategic tool for competition. In the real world, however, various marketing variables can be used for competition. Therefore, a more realistic model can be designed if a model incorporates other various marketing variables such as service levels or operation costs. Second, this study assumes the market with one monopoly manufacturer. Therefore, the results from this study should be carefully interpreted considering this limitation. Future research could extend this limitation by introducing manufacturer level competition. Finally, some of the results are drawn from the assumption that the monopoly manufacturer is the Stackelberg leader. Although this is a standard assumption among game theoretic studies of this kind, we could gain deeper understanding and generalize our findings beyond this assumption if the model is analyzed by different game rules.