• The Journal of Korean Academy of Prosthodontics
• /
• v.46 no.5
• /
• pp.479-489
• /
• 2008

Statement of the problem: Under anatomical limitations on maxillary posterior region, a poor crown-to root ratio acting on dental implants can result in undesirable stress in surrounding bone, which in turn can cause bone defects and eventual failure of implants. Purpose: The purpose is to compare stress distribution due to different crown-root ratio and effect of splinting between natural teeth and implants in maxillary molar area under different loads. Material and methods: Analysis of stress arising supporting bone of the natural teeth and the implant was made with 3-dimensional finite element method. The model simulated naturel teeth was made with 2nd premolar and 1st molar in the maxillary molar region (Model T). The model simulated implants placed on same positions with two parallel implants of Straumann Dental Implant cemented abutment (Model I). Each model was designed in different crown-root ratio (0.7:1, 1:1, 1.25:1) and set cement type gold crown to make it non-splinted or splinted. After that, 300 N force was loaded to each model in five ways (Load 1: middle of occlusal table, Load 2: middle of buccal cusp, Load 3: middle of lingual cusp, Load 4: horizontal load to buccal cusp of anterior abutment only, Load 5: horizontal load to middle of buccal cusp of each abutment), and stress distribution was analyzed. Results and conclusion: On all occasions, stress was concentrated at the cervical region of the implant. Under load 1, 2 and 3, stress was not increased even when crown-root ratio increases, but under load 4 and 5, when crown-root ratio increases, stress also increased. There was difference in stress values between natural teeth and implants when crown-root ratio gradually increases; In case of natural teeth, splinting decreased stress under vertical and horizontal loads. In case of implants, splinting decreased stress under vertical loads 1,2 and 3, but increased maximal stress under loads 2 and 3. Under horizontal loads, splinting decreased stress, however the effect of splinting decreased under load 5 than load 4. Furthermore, the stress was increased, when crown-root ratio is 1.25:1. Clinical implications: This limited finite element study suggests that the stress on supporting bone may be increased under non-axial loads and poor crown-root ratio. Under poor crown-root ratio, excessive stress was generated at the cervical region of the implant, and decreased splinting effect for stress distribution, which can be related to clinical failure.

• Journal of Chest Surgery
• /
• v.40 no.10
• /
• pp.674-679
• /
• 2007

Background: Surgical resection is accepted widely as the standard therapy for complete resectable pulmonary metastases. The number of cases of pulmonary metastasectomy and its survival rate is increasing due to the development of the therapeutic modalities. We attempted to analyze the survival rate and prognosis factors of pulmonary metastasectomy during the last 10 years. Material and Method: We retrospectively analyzed the data of 89 patients who underwent 96 procedures of pulmonary metastasectomy between January 1996 and December 2005. The factors that may influence the long term prognosis such as completeness of resection, the type of primary cancer, the disease-free interval, the number and size of metastasis and the laterality were investigated. Result: There was no operative mortality. The mean disease free interval (DFI) was $29.6{\pm}27.9$ months and there were 3 cases of synchronous metastasis (3.4%). The overall 3, 5 and 10 year survival rate was 52.5%, 32.1% and 20.7%, respectively. The median survival time was 38 months. The 5-year survival rate according to the IRLM appraisal was 63.5%, 33.3%, 22.1% and 0% for stage I, II, III and IV, respectively Univariate analysis showed a better prognosis for patients with a disease free interval of 36 months or more, unilateral metastasis and 4 or less metastases. Conclusion: The survival rate for completely resectable pulmonary metastasectomy was favorable. The disease free interval, laterality and the number of metastasis were the prognosis factors.

• Journal of Yeungnam Medical Science
• /
• v.7 no.1
• /
• pp.81-93
• /
• 1990

The author fractographically analyized the cause of metal failure(the first time this procedure has been used for this metal failure)and also analyized it clinically. In this study, I selected eight cases which have been analyized fractographically. In all these cases, the analysis was done after treatment of metal failure of implants internally fixed to femur shaft fractures at the Department of Orthopedic Surgery, Yeung-Nam University Hospital during the six year period from May 1983 to September 1989. 1. Metal failure occured in five dynamic-compression plates, one Jewett nail, one screw in Rowe plate, and one interlocking nail. 2. The clinical cause of metal failure was deficiency of medial butress in five cases, incorrect position of implant in one case, and incorrect selection of implant in two cases. 3. The time interval between internal fixation and metal failure was four months in one case, between five months to twelve months in six cases, three years in one case. 4. The fractographically analytical cause of metal failure was ; first, impact failure, one case, second, fatigue failure, six cases, machining mark(stress liser), four cases type : low consistent cyclic fatigue failure irregular cyclic fatigue failure third, stress corrosion crack, one case. 5. 316L Stainless Steel has good resistance to corrosion. However, when its peculiar surface film is destroyed by fretting, it shows pitting corrosion. This is, perhaps, the main cause of metal failure. 6. It is possible that mechanical injury occured in implants during the manufacturing of implants or that making a screw hole is the main cause of metal failure.

• Korean small business review
• /
• v.42 no.2
• /
• pp.69-92
• /
• 2020

This study is aimed at the growth and development of family businesses that greatly contribute to Korea's economic development, but the specific research purpose is to firstly examine the research trends and current status of Korean family businesses and compare them with those of developed countries such as the United States. Second, I would like to look at the future research for revitalizing Korean family business research. In addition, we intend to contribute to increasing the interest in this field and the number of researchers involved. The research target of this paper is 212 papers published in professional academic journals for 13 years from 2006 to 2018 when family businesses began to be fully researched in Korea, 112 master's and doctoral dissertations (graduate schools), and 324 totals. As a result of empirical analysis, the number of published papers is increasing more than the initial ones, but it has been on the decline recently. In addition, 57.5% of the journals are papers that do not have specific definitions or simply list the claims of several scholars by analyzing content. Thesis was 33.9%. As for the type of research, qualitative research, which is a conceptual research, is a small number, and empirical research occupies most of the research topics. Research topics and academic dissertations also have a large proportion of management, management strategy, succession, financial accounting, and business performance. In other words, it can be said that the research on family business in Korea corresponds to the early childhood of the United States. First of all, in the future, we need to put more effort into increasing the qualitative research, starting with the definition of a family business, which is an essential problem, in addition to the theory building of family business. Second, as an analysis level of research, we should make family an important level of analysis for existing individuals, groups, and organizations. Third, the research subject and research area should be expanded. It is desperately necessary to study large companies including chaebols, mainly from small and medium-sized companies, which are the existing research areas of family business. In addition, it is considered that it is necessary to appropriately introduce various theories suitable for the interdisciplinary study, which is the characteristic of the family business, for example, theories of family science, psychology, and sociology. Fourth, it should build the research infrastructure.

• Korea Trade Review
• /
• v.48 no.3
• /
• pp.43-68
• /
• 2023

In this study, in relation to "Chapter 3 Support for Priority Purchase of Technology Development Products" of the 「Market Channel Support Act」, this study investigated the positive growth impact of technology development products subject to preferential purchase on small and medium sized enterprises. The data used for empirical verification is for 371 companies that obtained certification for technology development products subject to preferential purchase in 2016 and Data from SMEs were collected from 2017 to 2021, Sales, operating profit, and net profit was identified, and empirical verification. And conducted through statistical analysis to determine whether it had a positive effect on the growth factors of SMEs. In addition, data from 225 technology development product certification companies were collected, and empirical testing was conducted through t-test analysis on the change in growth factors before and after acquiring certification. As a result of statistical analysis, it was found that the total assets, certified sales, operating profit, and net profit, which are the growth factors of a company, are all positively affected according to the type of technology development product certification. However, in the case of authentication types, some authentications showed significant negative results. In addition, significant results were derived that after acquiring certification had a positive effect on growth factors than before acquiring certification. Consistent with this conclusion, I think that it is effective for technology development-based SMEs to enter the public procurement market and utilize the technology development product priority purchase policy for market exploitation and corporate growth. And the government should strengthen the market support policy to create demand so that SMEs can enter the procurement market and actively utilize the preferential purchase system, and come up with an improvement plan so that public institutions can actively utilize the preferential purchase system.

• Korean Security Journal
• /
• no.48
• /
• pp.147-176
• /
• 2016

Korean Peninsula is surrounded by ocean on three sides. Because of this geographical quality over 97% of export and import volumes are exchange by sea. Foreign ship and international passenger vessels carries foreign tourist and globalization and internationalization increases this trends. Leisure population grows with national income increase and interest of ocean. And accidents and incidents rates are also increases. Korea Coast Guard's jurisdiction area is 4.5 times bigger than our country. The length of coastline is 14,963km including islands. One patrol vessel is responsible for 24,068km and one coast guard substation is responsible for 94km. Efficient patrol activities can not be provided. This research focus on this problem. Analyze the status and trends of maritime crime and suggest efficient patrol activities. To deal with increasing maritime crime rate this study suggest to use geographical profile method which developed early 1900s in USA. This geographical profile analyse the spatial characteristic and mapping this result. With this result potential crime zone can be predicted. One of the result is hot spot management which gives data about habitual crime zone. In Korea National Police Agency adopt this method in 2008 and apply on patrol and crime prevention activity by analysis of different criteria. Korea National Police Agency analyse the crime rate with crime type, crime zone and potential crime zone, and hourly, regionally criteria. Korea Coast Guard need to adopt this method and apply on maritime to make maritime crime map, which shows type of crime with regional, periodical result. With this geographical profiling we can set a Criminal Point which shows the place where the crime often occurs. The Criminal Points are set with the data of numerous rates such as homicide, robbery, burglary, missing, collision which happened in ocean. Set this crime as the major crime and manage the data more thoroughly. I expect to enhance the reinforcement of marine crime using this Criminal Points. Because this points will give us efficient way to prevent the maritime crime by placing the patrol vessel where they needed most.

• Korean Journal of Environmental Biology
• /
• v.24 no.3
• /
• pp.248-257
• /
• 2006

Total naturalized plant species in the streams of Jeonju were listed as 109 taxa; 24 families, 75 genera, 106 species, 3 varieties. Dividing by stream, Jeonju stream has 75 taxa; 20 families, 55 genera, 73 species, 2 varieties. Samcheon stream has 86 taxa; 19 families, 64 genera, 84 species, 2 varieties. Soyang stream has 80 taxa; 21 families, 60 genera, 77 species, 3 varieties. Urbanization Index (UI) of total streams (109 taxa) was 40.2%. UI was 27.7% in Jeonju stream (75 taxa), 31.7% in Samcheon stream (86 taxa), 29.5% in Soyang stream (80 taxa). Dividing by degree of naturalization classification, 25 taxa (9.2%) were found in class 5, 17 taxa (6.2%) in class 4, 32 taxa (11.8%) in class 3, 27 taxa (9.9%) in class 2 and 8 taxa (2.9%) in class 1. Dividing by introduction period, 48 taxa (44%) aye in period I, 19 taxa (17%) in period II, 42 taxa (39%) in period III. Dividing by growth type, 48 taxa (44%) are annuals, 25 taxa (23%) are biennials, 33 taxa (30%) are perennials. Dividing by the place of origin, 39 taxa (35%) are from Euyope, 33 taxa (30%) from North America, 11 taxa (10%) from Tropic America, 9 taxa (8%) from Europe Asia,5 taxa (5%) from South America, 5 taxa (5%) from China.