• Transactions of Materials Processing
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• v.33 no.2
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• pp.96-102
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• 2024

This study addresses evaluation of performance of hardening model for a titanium alloy (Ti6Al4V) based on the artificial neural network (ANN) regarding the strain rate and the temperature. Uniaxial compression tests were carried out at different strain rates from 0.001 /s to 10 /s and temperatures from 575 ℃ To 975 ℃. Using the experimental data, ANN models were trained and tested with different hyperparameters, such as size of hidden layer and optimizer. The input features were determined with the equivalent plastic strain, strain rate, and temperature while the output value was set to the equivalent stress. When the number of data is sufficient with a smooth tendency, both the Bayesian regulation (BR) and the Levenberg-Marquardt (LM) show good performance to predict the flow behavior. However, only BR algorithm shows a predictability when the number of data is insufficient. Furthermore, a proper size of the hidden layer must be confirmed to describe the behavior with the limited number of the data.

• Archives of design research
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• v.20
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• pp.199-208
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• 1997

The emphasis of simplicity in design is because of the desire to deliver much content with a simplest way. Since in general, a simple form is outstanding in its symbolical nature and the relief of plastic beauty is easy by it, it is usually applied to a form of a symbol mark. However, in the meantime, if any local autonomous group or enterprise which has not tried to give efforts to its advertisement than they might expect and might be disadvantageous in competition. For consumers, when they experienced several, forms of simple, symbol mark, would not remember the special features of each mark. Rather, for the psychology of perception, they might remember only the formative, common features, there by grouping the marks by their common features. In this study, some symbol marks in Dobong-gu Ward Office and Wonju city were inspected, reviewed, and analized. And its is a finding that the subjects of this study could not distinguish or identify any of marks from another mark having a similar image of it: the reason is that the simplicity of a symbol mark made or allowed them to recognize it identical with the other imaged: it proves that the mistakes, defects of memory, and accumulated errors are oriented to the identical image. After all, the appearented image and perceived image are differnt. Any of symbolmarks which takes a simple form does not mean the perceived image is also simple. As a final conclusion, designers, in order to produce any of competitive symbolmarks, need to thoroughly understand psychology of gestalt.

• Korean Journal of Heritage: History & Science
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• v.55 no.4
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• pp.138-164
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• 2022

The Neolithic shell midden in Daejuk-ri, Seosan, is distributed on the gentle slope of a low hill close to the west coast. The bedrock of the area consists mainly of schist with various mafic minerals, but shows a partial gneiss pattern. The site consists of loamy topsoil and clay loam subsoil, and the degree of siallization is relatively low. Although the pottery excavated from the shell midden shares mostly similar features, a variety of shapes and patterns coexist. The surface colors, thickness and physical properties are slightly different. The pottery can be subdivided into three types (IA, IB and II) according to the composition of the body clay, the temper and the existence of a black core. Types IA and IB are colorless mineral pottery with a non-black or black core respectively. TypeII is colored mineral pottery with a non-black core. Type I pottery also contains non-plastic colored minerals, but type II contains a large amount of biotite, chlorite, talc, amphibole, diopside and tremolite, which include a large amount of Mg and Fe. The studied pottery contains a small amount of organic matter. Considering the grain size and relatively poor sorting and roundness of the non-plastic particles, the pottery appears to be made by adding coarse non-plastic tempers for special purposes to the untreated weathered soil around the site. The three types of pottery seem to have been incompletely fired in general. While type IB has the lowest degree of oxidation, typeII shows the highest degree of redness and oxidation. It can be interpreted that these differences depend on the firing temperature and the ratio of non-plastic particles. Through a synthesis of the minerals, geochemical data and thermal history, it can be determined that the firing temperature ranged from 600 to 700℃. The pottery types of the Daejuk-ri Shell Midden have slightly different production conditions, mineral compositions, and physical properties, but have undergone similar production processes with basically the same clay materials. The clay is almost identical to the composition of the bedrock and weathered soil distributed in the Daejuk-ri area. Currently, there is an industrial complex in the area, so it is difficult to confirm the soil and geological distribution of the site. However, it is highly probable that the area around the site was self-sufficient for the clay and tempers required for the production of the Neolithic pottery. Therefore, it can be interpreted that the group that left the shell midden in Daejuk-ri lived near the site, visited the site for the purpose of collecting and processing shellfish, and discarded the broken pottery along with shells.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.1
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• pp.63-79
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• 1993

To repair bony defects with tansplanted bone in the body, fresh autogenous bone is undoubtly, the most effective bone graft for clinical applications. But the demineralized bone has the matrix-induced bone formation which was suggested by Urist in 1965. Many authors assisted that demineralized bone powder induces phenotypic conversion of mesenchymal cells into osteoblasts, with high-density bone formation. The process of inducing differentiated cells becomes osteogenic properties. The purpose of this study was to evaluate the osteoinductive capacity of allogenic freeze-dried demineralized bone block (FDD, $7{\times}7mm$) and to compare FDD with the same sue of deep-frozen allogenic bone(DF), fresh autogenous bone (A) after implantation. The histological and ultrastructural features of tissue responses were examined after 1, 2, 4, 6, 8 weeks implantation of each experimental groups in the operative site of the New Zealand white rabbits. The results were as follows : 1. Inflammatory cell infiltration generally has appeared at 1 week, but reduced at 4 weeks in each group, but most severe in DF group. 2. Osteoblastic activity has increased for 4 weeks, but decreased at 6 weeks in each group and there was no significant difference among experimental groups. 3. New bone formation has begun at 1week, least activations in A groups, and showed the revesal line of bone formation among each group at 6 to 8 weeks. 4. Bone resorption has appeared at 1 week, but disappeared at 4 weeks in both A and DF groups, but more severe in DF than A groups. 5. In ultrastructural changs, the DF group have showed the most remarkable osteoclastic activities among experimental groups. 6. Osteoid or tangled collagen fibrils near the implanted sites were replaced by more mature, lamellated bony trabeculae during bone remodeling. There was little difference among each experimental groups. 7. During the convertion osteoblasts to osteocytes which embedded within the bone matrix, there was organ-less-poor cytoplasm, increased nuclear chromatin, abundant rough endothelial reticulum (RER) in each groups. From the above the findings, the DF group shored more bone resorption and foreign body reaction than FDD and A groups, and FDD group showed more new bone formation or osteoblastic activity than DF and A groups in early stage. There was no significant difference of cellular activities among the FDD DF, and A groups according to the time.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.15 no.4
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• pp.338-345
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• 1993

Mandibular discontinuity defect due to benign tumor, malignant tumor, infection, or truma results in major esthetic and biologic compromise. The primary goal of reconstruction is full restitution of function, which secondarily lead to normalization of the cosmetic deformity. The authors make a clinical study of 61 consecutive bone graft cases for mandibular reconstruction of discontinuity defect which were studied retrospectively using clinical data and radiographic findings. The cases were reviewed to evaluate the clinical success in the period from 1981 to 1990 in the Dept. of Oral & maxillofacial Surgery, Seoul National University Hospital. The criteria of the success in bone graft, are no residual infection, graft in with maintain its integrity, and remain over a half of its original size of graft in the radiographic features. The purpose of this clinical survey is to study of the mandibular discontinuity defects and success rate of free bone graft in mandibular defects. To summarize the clinical study of free bone graft, the main type of autogenous bone graft is iliac bone and corticocancellous type. Overall success rate is 80.3% in 61 followup cases over 6 months. Wire fixation and Extraoral approach has realtively better prognosis than other methods. It showed relatively poor prognosis in symphysis defects than other recipient site.

• Korean Institute of Interior Design Journal
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• v.16 no.2 s.61
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• pp.262-269
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• 2007

The blur phenomenon obscuring the boundary between the field of designers and that of users may be the key paradigm in the 21st century. However, we observed a number of chair design cases that could be considered as the results of blur pheonomenon in the furniture design field from mid 1960s. The backgrounds include the repulsion against the uniform functionalism, deliberation on the life in the future and the development of plastic materials and their processing methods. Under such backgrounds, the designers pursued the new and futuristic furniture design. In that process, what is about the "freedom" that the consumers as well as the designers should have in using the furniture was the important concept. This concept enabled the creation of chair design inducing the participation of consumers. They created various kinds of shapes, functions and structures that the consumers became interested in as if they had fun with toy blocks by mainly using the new material "plastic". In a formative aspect, the entire shape is classified into the organic shape and geometric shape. The unit types are divided into two kinds; type that the unit of simple shape is repeated only with size difference and irregular combination type of the units comprised of more than two shapes. In the functional aspect, some cases showed the transformation and expansion of the function more variously. Other cases changed the function of chairs to tables, cabinets, or objects. In the structural aspect, on the basis of the method assembling each unit, one method is to assemble using the hardware and the other is to assemble only with intrinsic units of chair. The chair design created by the blur phenomenon between the designers and the users as described above causes the blur phenomenon between the furniture and the space where the furniture is installed. Accordingly, it is expanding the furniture design sphere including the case that the furniture is not selected as the rifle article depending on the characteristics of interior space but it becomes the element leading the characteristics of space. This study aims to estimate the change of interior space and the furniture that my cause the blur phenomenon by examining the cases above appropriate for the paradigm of the 21st century. Furthermore, this study will enable the discussion oil the directions of future furniture design based on its results.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.4
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• pp.343-348
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• 2009

Kaposi's sarcoma was first descrided by Kaposi in 1872 as an idiopathic multiple hemorrhagic sarcoma. Its clinical features revealed to be erythematous red or purple macule started out, and developing into palpable dome-shaped nodules. Etiology is not defined to detail at present. Kaposi's sarcoma is classified to 4 categories; Classical, African, Epidemic and Immunosuppressive type. Epidemic categories is found approximately 20% of all AIDS patients and has strong predilection for head and neck region. The first case of immunosuppresive type Kaposi's sarcoma in patients with kidney transplants was reported in 1969. Kaposi's sarcoma accounts for 5% of all tumors associated with transplanted patients. The most common site of Kaposi's sarcoma in immunosuppressed patients are extremities, but rare in head and neck area. A 42 years old woman who had systemic lupus erythematosus visited to our clinic because of gingival hyperplasia, and excisional biopsy revealed Kaposi's sarcoma. We experienced a case of favorable results using excision and chemotherapy, so we report with review of literatures.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.52.1-52.8
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• 2019

Background: A compact passive oxide layer can grow on tantalum (Ta). It has been reported that this oxide layer can facilitate bone ingrowth in vivo though the development of bone-like apatite, which promotes hard and soft tissue adhesion. Thus, Ta surface treatment on facial implant materials may improve the tissue response, which could result in less fibrotic encapsulation and make the implant more stable on the bone surface. The purposes of this study were to verify whether surface treatment of facial implant materials using Ta can improve the biohistobiological response and to determine the possibility of potential clinical applications. Methods: Two different and commonly used implant materials, silicone and expanded polytetrafluoroethylene (ePTFE), were treated via Ta ion implantation using a Ta sputtering gun. Ta-treated samples were compared with untreated samples using in vitro and in vivo evaluations. Osteoblast (MG-63) and fibroblast (NIH3T3) cell viability with the Ta-treated implant material was assessed, and the tissue response was observed by placing the implants over the rat calvarium (n = 48) for two different lengths of time. Foreign body and inflammatory reactions were observed, and soft tissue thickness between the calvarium and the implant as well as the bone response was measured. Results: The treatment of facial implant materials using Ta showed a tendency toward increased fibroblast and osteoblast viability, although this result was not statistically significant. During the in vivo study, both Ta-treated and untreated implants showed similar foreign body reactions. However, the Ta-treated implant materials (silicone and ePTFE) showed a tendency toward better histological features: lower soft tissue thickness between the implant and the underlying calvarium as well as an increase in new bone activity. Conclusion: Ta surface treatment using ion implantation on silicone and ePTFE facial implant materials showed the possibility of reducing soft tissue intervention between the calvarium and the implant to make the implant more stable on the bone surface. Although no statistically significant improvement was observed, Ta treatment revealed a tendency toward an improved biohistological response of silicone and ePTFE facial implants. Conclusively, tantalum treatment is beneficial and has the potential for clinical applications.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.41
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• pp.49.1-49.8
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• 2019

Background: The purpose of this study was to review the clinical features of oromaxillofacial infections in patients presenting to a hospital emergency ward, to identify the key factors affecting the requirement for hospitalization, and the potential risk factors predisposing to a prolonged length of hospital stay. Methods: A retrospective medical record review of the 598 patients treated for oromaxillofacial infection from 2013 to 2017 at the oral and maxillofacial surgery department, Yangsan Pusan National University Hospital, was conducted. The following information was collected from each patient: sex, age, past medical history, site of infection, etiology, admission or outpatient care, level of C-reactive protein (mg/dL), fascial spaces involved, treatment method, and duration of hospitalization. Chi-squared tests were used to identify risk factors, which were further analyzed using multivariable logistic regression. Results: A total of 606 patients were eligible for inclusion in the study, of which eight were excluded due to having incomplete charts; thus, 598 patients were included: 55% were male, mean patient age was 47.1 ± 19.9 years, and 12.9% of patients were diabetic. Furthermore, 71.2% of patients had infection originating in the mandible; the most common tooth of origin was lower posterior, and 29.8% of patients were hospitalized. Risk factors for hospital admission were elderly patients with concurrent disease, elevated C-reactive protein level, and multiple-space infection in the oromaxillofacial area. The duration of hospitalization was correlated with both diabetes and age. Conclusions: The requirement for hospital admission is determined by the severity of the infection; even severe infections, once treated with appropriate surgery, have no relation to the length of hospital stay. The important risk factors for increased duration of hospitalization are diabetes mellitus and older age. The understanding of risk factors associated with a prolonged hospital stay during the treatment of oromaxillofacial infection will aid in treatment planning as well as highlight the importance of adequate diabetes control in patients at risk of such infection.

• Korean Journal of Organic Agriculture
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• v.14 no.2
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• pp.179-189
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• 2006

After examining the difference in the photosynthesis rate of corn according to the planting distance, the distance of $40{\times}40cm$ showed the lowest rate by 23 days after transplanting (May 31); however, there was no significant difference in the photosynthesis rate due to increased salt tolerance in the plant as time went by. As for the difference in growth features of a plant, the planting distance of $40{\times}40cm$ showed a growing disorder due to the influence of salt by 23 days after trans-plantation (May 31); however, there was a desirable growth as time went by. For the difference in the salt content within a plant, the planting distance of $40{\times}40cm$ tended to be higher than other planting distances, and the K+ content is much higher than other kinds of salt after examining the difference in salt absorption. As for the correlation between saline components within a plant, there was a significant negative correlation among $K^{+},\;Ca^{2+},\;and\;Na^{+}$ while there was a significant positive correlation among $Mg^{2+},\;Ca^{2+}$, and Na+. After examining the effectiveness of salt removal from soil according to com cultivation, the planting distance of $30{\times}30cm$ showed a remarkable decrease by 37 days, compared with 23 days, after transplantation in $K^{+}$ by 28%, $Ca^{2+}$ by 36.6%, $Mg^{2+}$ by 30.6%, and $Na^{+}$ by 22.9%. And the salt content is higher in surface soil than in subsoil.