• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.359-365
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• 2002

The fatigue crack growth behavior of the SA516/60 steel which is used for pressure vessels was examined experimentally at room temperature $25^{\circ}C,\;-30^{\circ}C,\;-60^{\circ}C,\;-80^{\circ}C,\;-100^{\circ}C$ and $-120^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. Fatigue crack propagation rate da/dN related with stress intensity factor range ${\Delta}K$ was influenced by stress ratio in stable of fatigue crack growth (Region II) with an increase in ${\Delta}K$. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to tile extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are mainly explained by the crack closure and the strengthening due to the plasticity induced and roughness induced.

• Journal of the military operations research society of Korea
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• v.33 no.1
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• pp.75-92
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• 2007

Most of countries in the world are stepping up military conversion to achieve military modernization. The issues of military conversion hold reallocation of financial resources, reorientation of R&D, restructuring of military industry, demobilization, base closure and relocation, scrapping of surplus weapons and so on. Also ROK is stepping up military modernization through defense reform. In particular, ROK has the plan to convert bases; transfering U.S. Forces in Korea and conducting the merger and abolition of bases. In this respect, we expect increase of base conversion easily in the future. Therefore, we tried to find the strategy of base conversion that ROK can conduct base conversion with success in this study. So that we analyze cases of base conversion which were conducted in ROK and U.S. Moreover, we extract problems of the process of base conversion in ROK and finally find out substitutes.

• Journal of Periodontal and Implant Science
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• v.50 no.6
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• pp.406-417
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• 2020

Purpose: This study investigated whether the placement of ribose cross-linked collagen (RCLC) membranes without primary soft tissue closure predictably resulted in sufficient alveolar ridge preservation in contained and non-contained extraction sockets. Methods: Membranes were positioned across extraction sockets, undermining full-thickness flaps, and the gingival margins were fixed by double-interrupted sutures without crossed horizontal mattress sutures for 1 week. In non-contained sockets, a bone substitute was used to support the membrane within the bony envelope. Radiographs and clinical images obtained 4 months later were analyzed by ImageJ software using non-parametric tests. Results: In 18 patients, 20 extraction sockets healed uneventfully and all sites received standard-diameter implants (4.1, 4.8, or 5.0 mm) without additional bone augmentation. Soft tissues and the muco-gingival border were well maintained. A retrospective analysis of X-rays and clinical photographs showed non-significant shrinkage in the vertical and horizontal dimensions (P=0.575 and P=0.444, respectively). The new bone contained vital bone cells embedded in mineralized tissues. Conclusions: Within the limitations of this pilot study, open healing of RCLC membranes may result in sufficient bone volume for implant placement without additional bone augmentation in contained and non-contained extraction sockets.

• Journal of Korean Dental Science
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• v.16 no.2
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• pp.115-127
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• 2023

The demand for orthodontic clear aligner therapy (CAT) has increased significantly over the last decade, offering advantages over the fixed appliances (FA) including enhanced aesthetics, better hygiene and comfort, along with minimal restrictions on the patient's diet. Moreover, a marked improvement in the efficacy of tooth movement using aligners has been documented. On the contrary, there have been known limitations of CAT including the compliances issues and the apparent lack of efficacy for certain types of tooth movement such as closure of extraction space compared to FA. Thus, evidence-based evaluation of the accuracy of prediction of tooth movement with clear aligners and their ability to effectively perform major tooth and root movements compared to FA are crucial. Although several systematic reviews have investigated various aspects of the effectiveness of CAT, we are yet to obtain a rather conclusive answer to this question. The current review attempted to summarize the evidence-based findings of most systematic reviews about CAT available to date. Major issues regarding the predictability of tooth movement, the role of attachments and auxiliaries in improving the effectiveness of CAT, and the treatment outcomes in comparison to FA were investigated. Clinical recommendation have been also elaborated based on the interpretation of the findings of all systematic reviews included in this study.

• Computers and Concrete
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• v.33 no.4
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• pp.349-359
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• 2024

This study aims to investigate the effect of restraint configuration on crack formation due to shrinkage-and-creep-induced volumetric change in unbonded post-tensioned slabs. The first part of this study focuses on the comparison of existing shrinkage and creep calculation models that are used to predict the volume-changing behavior of concrete. The second part of this study presents the finite element analysis of a series of architectural configuration prototypes subjected to shrinkage and creep, which comprise unbonded post-tensioned slabs with various restraint configurations. The shrinkage and creep effects were simulated in the analysis by imposing strains obtained from one selected calculation model. The results suggest that a slab up to 300 ft. (90 m) in length does not require a closure strip if it is unrestrained by perimeter walls, and that the most effective restraint crack mitigation strategy for a slab restrained by perimeter walls is a partial wall release.

• Journal of Periodontal and Implant Science
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• v.40 no.1
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• pp.11-18
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• 2010

Purpose: Significant interest has emerged in the design of cell scaffolds that incorporate peptide sequences that correspond to known signaling domains in extracellular matrix and bone morphogenetic protein. The purpose of this study was to evaluate the bone regenerative effects of the synthetic peptide in a critical-size rat calvarial defect model. Methods: Eight millimeter diameter standardized, circular, transosseus defects created on the cranium of forty rats were implanted with synthetic peptide, collagen, or both synthetic peptide and collagen. No material was was implanted the control group. The healing of each group was evaluated histologically and histomorphometrically after 2- and 8-week healing intervals. Results: Surgical implantation of the synthetic peptide and collagen resulted in enhanced local bone formation at both 2 and 8 weeks compared to the control group. When the experimental groups were compared to each other, they showed a similar pattern of bone formation. The defect closure and new bone area were significantly different in synthetic peptide and collagen group at 8 weeks. Conclusions: Concerning the advantages of biomaterials, synthetic peptide can be an effective biomaterial for damaged periodontal regeneration.

• Journal of the Korean Society of Costume
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• v.65 no.8
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• pp.110-124
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• 2015

This study examined a phenomenon of exaggerated hairstyle in the history of Western custom through publications related with Western costume and research papers. By adopting the criteria of Delong, M. R. to analyze visual forms shown by interaction between human body and costume worn over the body, it analyzed the formative characteristics by the interaction between hairstyle and costume. In addition, it inferred the aesthetic characteristics through content analysis of examined phenomenon focusing on socio-cultural background and costume socio-psychological precedent studies. Formative characteristics of exaggerated hairstyle applied by analysis criteria of Delong, M. R. were in pursuit of the emphasis style. This was clearly and intensively recognized by forming spaces for mostly closure style, part style, three dimensional style, determinate style, and space separation style. Regarding the interaction between hair and ornamentations, 'precedence of ornamentation' was pursued as ornamentations were recognized earlier than the hair itself. It means associative meanings of the surface effect were accompanied by emotions of 'intensiveness' and the pursuit of the attractive style. As for the interaction between hairstyle and costume, there were many cases of pursuing 'continuity' mutually and visually by connecting the hairstyle and the costume. Aesthetic characteristics of exaggerated hairstyle were inferred as 1) the expression of the sprite of the age(i.e. art, culture, politics, society, ideology, religion), 2) symbols of wealth, class, authority, and excellence, 3) pursuit of addicted desire to ornament, and 4) harmony through continuity with costume. This study verified that hairstyle was connected as a part of costume, or formed as a way to express deeper human psychology beyond just a part of a costume. It was also confirmed that hairstyle was an expressive method to express the spirit of the age, such as art, culture, society, religion, ideology.

• Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.159-164
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• 2013

The mouse bioassay and high performance liquid chromatography (HPLC) post-column oxidation method are different methods of quantifying paralytic shellfish poisoning toxins. In this study, we compared their ability to accurately quantify the toxicity levels in two types of field sample (oysters and mussels) with different toxin profiles for routine regulatory monitoring. A total of 72 samples were analyzed by both methods, 44 of which gave negative results, with readings under the limit of detection of the mouse bioassay ($40{\mu}g/100g$ saxitoxin [STX] eq). In 14 oysters, the major toxin components were gonyautoxin (GTX) 1, -2, -3, -4, -5, decarbamoylgonyautoxin-2 (dcGTX2), and decarbamoylsaxitoxin (dcSTX), while 14 mussels tested positive for dcSTX, GTX2, -3, -4, -5, dcGTX2, neosaxitoxin (NEO), STX, and dcSTX. When the results obtained by both methods were compared in two matrices, a better correlation ($r^2=0.9478$) was obtained for mussels than for oysters ($r^2=0.8244$). Additional studies are therefore needed in oysters to investigate the differences in the results obtained by both methods. Importantly, some samples with toxin levels around the legal limit gave inconsistent results using HPLC-based techniques, which could have a strong economic impact due to enforced harvest area closure. It should therefore be determined if all paralytic shellfish poisoning toxins can be quantified accurately by HPLC, and if the uncertainties of the method lead to doubts regarding regulatory limits.

• Journal of Veterinary Clinics
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• v.25 no.6
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• pp.494-500
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• 2008

The aim of this study was to determine the effectiveness of hyaluronic acid-carboxymethylcellulose membrane (GUARDIX-$MB^{(R)}$) barriers on prevention against post-operative peritoneal adhesions. In this study, fourteen mongrel dogs were divided into two experimental groups: 0.1 % hyaluronic acid (0.1HA) group and hyaluronic acidcarboxymethylcellulose membrane (HA-CMC) group. In order to induce adhesions, the anti-mesenteric serosa of the ileum was exteriorized and then abraded in a standard manner by scraping with a scalpel blade to create homogenous petechial hemorrhagic surface over a $1\;{\times}\;1cm$ area. Solution of 0.1HA were simply coated over the abraded tissues, $1.5\;{\times}\;1.5cm$ HA-CMC membrane was placed over the abraded tissues, allowed to spread across the intra-abdominal organs before closure of the abdomen. On day 1 before and day 1, 4, 7, 14, and 21 after operation, venous blood specimens were collected for measurement of fibrinogen and total WBC. The adhesions were blindly assessed 3 weeks later by using a computerized tensiometer. The fibrinogen and total WBC values of two groups showed no statistical significances. The mean tensile strength (gram force, gf) of formed adhesions day 21 after surgery was $88.1\;{\pm}\;55.70gf$ in the 0.1 % HA group and $24.8\;{\pm}\;22.69gf$ in the HA-CMC group. The tensile strength values of adhesion separation HA-CMC membrane group was significantly lower than the 0.1HA group (p<0.05). Therefore, we suggest that HACMC membrane reduce peritoneal adhesions may be applicable to preventing post-operative intraperitoneal adhesions in dogs.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.148-153
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• 2007

Background : Computer- and web-based simulation methods help students develop problem solving and decision making skills. In addition, they provide reality based learning to the student clinical experience with immediate medical feedback as well as repetitive training, on-site reviews and case closure. Materials and Methods : Seventy-five third-year medical students participated in a two-week simulation program. The students selected four modules from eight modules as follows: airway and breathing 1, cardiac arrest 1, cardiac arrhythmia 1, and chest pain 1, and then selected the first case within each of the modules. After 2 weeks, a pass score was obtained and the data analyzed. The average pass score of over 70% was considered a passing grade for each module. If the student did not pass each module, there was no score (i.e., pass score was zero). In addition, when at least one of the four modules was zero, the student was not included in this study. Results : Seventy-five students participated in the simulation program. Nineteen students were excluded based on their performance. The final number of students studied was 56 students (74.7%). The average scores for each module 1 to 4 were 86.7%, 85.3%, 84.0%, and 84.0%, and the average obtained pass score was 88.6 for the four modules in all 56 students. Conclusion : Medical simulation enabled students to experience realistic patient situations as part of medical learning. However, it has not been incorporated into traditional educational methodology. Here we describe the introduction and the development of various simulation modules and technologies for medical education.