• Archives of Plastic Surgery
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• v.38 no.6
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• pp.808-814
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• 2011

Purpose: Despite wide clinical use of breast implants, there is continued concern about the lifespan of these devices. The causes of explantation were infection, deflation of implant and patient's want. The deflation of saline-filled breast implant was related to strength and durability of implant shell. The purpose of this study is to evaluate the clinical durability of saline-filled breast implant through the analysis of duration until deflation occurred, causes, incidence and influencing factors. Methods: Retrospective analyses were conducted on clinical records for 19 cases of deflation of saline-filled breast implant from 201 cases of breast reconstruction with saline-filled implant between May 1995 and June 2011. The authors had been analyzed the causes of deflation, survival duration, symptom, sign, nipple excision, volume of implant, saline filling, method of reoperation, breast cancer stage and combined capsular contracture. Results: The causes of deflation were attributed to the cases that cannot be evaluated the causes in 15 cases, fall down in 1 case, mammography in 2 cases, accidental needle injury in 1 case. Mean survival duration was 4 years and 5 months. The duration of survival was less than 1 year for 5 cases, 1 year to 10 years for 10 cases, more than 10 years for 4 cases. The volume between 201 and 250 cc of deflated breast implant was rated as high by 14.0 percent. The deflation rate of underfilled implants was 11.4 percent, adequate filled implants was 9.3 percent. None of overfilled implant was deflated. The deflation of smooth surface implant was 5 of 152 cases. Textured implant was 14 of 49 cases. The capsular contracture of non-deflated breast implant was 28 of 182 cases and that of deflated breast implant was 6 of 19 cases. Conclusion: The patients who underwent saline-filled breast implant implantation should be informed that their implant could deflate. The analysis of clinical durability and causes of deflation in breast implant was important for the prediction and prevention of reopeation. The authors could suppose the causes of deflation of saline-filled breast implant through history, duration of survival, inspection of the shell of implant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.193-199
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• 2017

The purpose of this study was to provide basic data for the development of fall prevention programs for the elderly and for improvement of quality of life based on history of falls, chronic diseases, location, fear of falling, daily living activities, and quality of life. This study was conducted from 15th August to 17th September of 2016 on 185 elderly subjects above the age of 65 living in four centers of J city and four centers of J rural. The results of this study are as follows: There were no statistically significant differences in daily living activities, fear of falls, and quality of life regarding falls in the past. There were statistically significant differences in fear of falling and quality of life regarding chronic diseases. There were statistically significant differences in daily living activities and quality of life regarding residence. This study confirms that there were relations among daily living activities, fear of falling, and quality of life, and there was a negative correlation between fear of falling and accomplishment of daily living activities(r=-.386, p<.000). There was also a positive correlation between accomplishment of daily living activities and quality of life(r=.513, p<.000). Therefore, avoiding outings on slippery roads and creating safe environments for the elderly are important to reduce fear of falling. Additionally, a system should be developed for the elderly to acquire necessary information for daily life.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.229-232
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• 2008

In rapid cycle construction, RC structure which is not cured fully can be loaded with construction load and this construction load can influence on the safety of construction and cracks on slabs. Therefore, to reduce the term of construction, the safety of construction and prevention of cracks should be assured against construction load. In the previous study, temperature load can significantly influence on the behavior of structure under construction. However, existing construction sequential analysis or design code do not consider temperature load reasonably. In the present study, through construction sequential analysis method using FE analysis, the behavior of structure under construction was analyzed according to temperature changes. According to the results of analysis, as the temperature falls, shoring load drops and the temperature rises, shoring load rises. These variations of shoring load can affect the safety of construction. Moment of slab goes up by fall in temperature. This increase of moment can cause cracks on the slab. Therefore to assure the safety on construction and prevent cracks on slabs, temperature load has to be considered reasonably in construction sequential analysis.

• Journal of the Korean GEO-environmental Society
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• v.15 no.11
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• pp.53-59
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• 2014

It has been generally recognized that the conventional rockfall protection nets have several problems to actual field application in the aspect of shock absorption, lack of pullout bearing capacities, and net damages. Because of the recognition, authors have tried to develop a new rockfall protection system consisted of shock absorption parts and hexagonal net configuration. In the previous research by the authors, the performance of the newly developed rockfall protection system has been investigated through the laboratory tests and the full-scale testing. In this study, subsequently, numerical analysis program is organized to make a confirmation of the structural stability and performance. For the correct design procedure of the hexagonal net system, it is essential to understand the various mechanical behavior of the entire system. It is also important to be reproduced the systematic characteristics of the system acquired by laboratory and full-scale testing by numerical analysis in order to carry out the numerical experiment to understand various mechanical behavior of the system. As a conclusion, the hexagonal net has better performance in mechanical and physical behavior compared with that of the rectangular net. Furthermore, due to the hexagonal net shows a good performance in aspect of the load distribution, it gives a good alternative in long-term management of the rockfall protection net.

• Journal of Preventive Medicine and Public Health
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• v.41 no.4
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• pp.265-271
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• 2008

Objectives: This study was conducted to estimate the cumulative incidence rate (CIR) of unintentional injuries in Korean daily life and to describe the pattern of unintentional injuries. Methods: The study population was the people who used the National Health Insurance because of injuries (ICD code: S00$\sim$T98) during 2006. The stratified sample according to gender, age and the severity of injury (NISS, New Injury Severity Score) was randomly selected. The questions on the questionnaire were developed as a reference for an international classification tool (ICECI, International Classification of External Causes of Injury). The questions included the locations of injury, the mechanisms of injury and the results of injury. Moreover, we used age, gender, region and income variables for analysis. Results: The CIR of unintentional injuries that occurred in daily life for 1 year per 100,000 persons was 17,606, and the CIR of severe injuries was 286. Many injuries were occurred at home (29.6%), public places (19.0%), school (13.7%) and near home (12.0%). The major mechanisms of injuries were slipping (48.8%), contact (14.0%), physical over-exertion (13.8%), and fall (6.6%). Infants and old aged people were vulnerable to injuries, and those who lived rural area and who were in a low income level were vulnerable too. Conclusions: We signified the risk groups and risk settings of unintentional injuries in Korean daily life. These results could contribute to establishing strategies for injury prevention and implementing these strategies.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.23 no.2
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• pp.69-75
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• 2012

Objectives : The current study was conducted in order to investigate teachers' recognition of school bullying using a nationwide database of adolescents in middle and high school in Korea. Methods : Students in the 7th to 12th grades at 23 secondary schools participated in the current study during the fall of 2009. Subjects completed the self-report form of the Adolescent Mental Health and Problem Behavior Screening Questionnaire-II (AMPQ-II) and Symptom Checklist-90 Revised (SCL-90-R). In addition, relevant teachers used the teachers' rating scale of the AMPQ-II to report their students' status. Differences in the number of bullied students between teachers' recognition and students' report were explored. Results : A total of 2270 subjects provided relevant responses to the questionnaire. While the one-month prevalence of victimization according to students' self-reports was 28.9%, the recognized prevalence by teachers was only 10.6%. For prediction of the presence of school bullying according to students' self reports on the AMPQ-II, item 7 of the teachers' report on the AMPQ-II showed a sensitivity of 16%, a specificity of 92%, a positive predictability of 44%, a negative predictability of 72%, a false positive rate of 8%, a false negative rate of 84%, and an accuracy of 69%, respectively. No significant differences in subscores of students' self reports of the AMPQ-II and SCL-90-R were observed between bullied students who were recognized by teachers and those who were not recognized. In stepwise discriminant analysis, classification of teachers' item 2 and item 7 on the AMPQ-II with respect to school bullying according to students' reports showed an accuracy of 63.4%. Using this model, 75.2% of non-victimized subjects were classified correctly, while only 35.2% of victimized subjects were classified correctly. Conclusion : Despite the high prevalence in Korea, teachers' recognition of school violence among their students remains low. Pre-professional and continuing education to improve teachers' understanding of school bullying and knowledge of effective classroom-based prevention activities should be encouraged.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.6
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• pp.306-316
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• 2015

Objectives: The facial bones are the most noticeable area in the human body, and facial injuries can cause significant functional, aesthetic, and psychological complications. Continuous study of the patterns of facial bone fractures and changes in trends is helpful in the prevention and treatment of maxillofacial fractures. The purpose of the current clinico-statistical study is to investigate the pattern of facial fractures over a 4-year period. Materials and Methods: A retrospective analysis of 1,824 fracture sites was carried out in 1,284 patients admitted to SMG-SNU Boramae Medical Center for facial bone fracture from January 2010 to December 2013. We evaluated the distributions of age/gender/season, fracture site, cause of injury, duration from injury to treatment, hospitalization period, and postoperative complications. Results: The ratio of men to women was 3.2:1. Most fractures occurred in individuals aged between teens to 40s and were most prevalent at the middle and end of the month. Fractures occurred in the nasal bone (65.0%), orbital wall (29.2%), maxillary wall (15.3%), zygomatic arch (13.2%), zygomaticomaxillary complex (9.8%), mandibular symphysis (6.5%), mandibular angle (5.9%), mandibular condyle (4.9%), and mandibular body (1.9%). The most common etiologies were fall (32.5%) and assault (26.0%). The average duration of injury to treatment was 6 days, and the average hospitalization period was 5 days. Eighteen postoperative complications were observed in 17 patients, mainly infection and malocclusion in the mandible. Conclusion: This study reflects the tendency for trauma in the Seoul metropolitan region because it analyzes all facial fracture patients who visited our hospital regardless of the specific department. Distinctively, in this study, midfacial fractures had a much higher incidence than mandible fractures.

• Nuclear Engineering and Technology
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• v.44 no.5
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• pp.523-534
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• 2012

The objective of this study was to experimentally investigate the effect of heat curing methods on the temperature history and strength development of slab concrete exposed to $-10^{\circ}C$. The goal was to determine proper heat curing methods for the protection of nuclear power plant structures against early-age frost damage under adverse (cold) conditions. Two types of methods were studied: heat insulation alone and in combination with a heating cable. For heat curing with heat insulation alone, either sawdust or a double layer bubble sheet (2-BS) was applied. For curing with a combination of heat insulation and a heating cable, an embedded heating cable was used with either a sawdust cover, a 2-BS cover, or a quadruple layer bubble sheet (4-BS) cover. Seven different slab specimens with dimensions of $1200{\times}600{\times}200$ mm and a design strength of 27 MPa were fabricated and cured at $-10^{\circ}C$ for 7 d. The application of sawdust and 2-BS allowed the concrete temperature to fall below $0^{\circ}C$ within 40 h after exposure to $-10^{\circ}C$, and then, the temperature dropped to $-10^{\circ}C$ and remained there for 7 d owing to insufficient thermal resistance. However, the combination of a heating cable plus sawdust or 2-BS maintained the concrete temperature around $5^{\circ}C$ for 7 d. Moreover, the combination of the heating cable and 4-BS maintained the concrete temperature around $10^{\circ}C$ for 7 d. This was due to the continuous heat supply from the heating cable and the prevention of heat loss by the 4-BS. For maturity development, which is an index of early-age frost damage, the application of heat insulation materials alone did not allow the concrete to meet the minimum maturity required to protect against early-age frost damage after 7 d, owing to poor thermal resistance. However, the combination of the heating cable and the heat insulating materials allowed the concrete to attain the minimum maturity level after just 3 d. In the case of strength development, the heat insulation materials alone were insufficient to achieve the minimum 7-d strength required to prevent early-age frost damage. However, the combination of a heating cable and heat insulating materials met both the minimum 7-d strength and the 28-d design strength owing to the heat supply and thermal resistance. Therefore, it is believed that by combining a heating cable and 4-BS, concrete exposed to $-10^{\circ}C$ can be effectively protected from early-age frost damage and can attain the required 28-d compressive strength.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.499-510
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• 2015

Artificial accelerated weathering test evaluated rocks from near the circuit road of Ulleungdo island, approximately 120 km from east of the Korean Peninsula. The tests subjected rock specimens to conditions based on the climate of the island. The specimens (such as basaltic breccia, trachyte, volcanic breccia) were preliminarily classified using a TAS diagram (XRF data) and based on the constituent minerals (XRD data); they were further classified by weathering degree according to their absorption ratios. During the artificial accelerated weathering, the absorption ratio of most of the specimens increased, but the point-load strength did not decrease in most cases, except for the volcanic breccia. The greater initial absorption ratio of trachyte rock specimen in comparison with the other specimens led to a greater increase of its absorption ratio during the artificial accelerated weathering test. The volcanic breccia specimens showed the greatest increase of absorption ratio and the biggest reduction ratio of the point- load strength during the tests. These results could aid prediction of the weathering rate of rocks in Ulleungdo island subjected to weathering processes; trachyte which appears to accelerate with time, and volcanic breccia whose mechanical strength can largely decrease in a relative short period of time. Proper measures therefore appear necessary for the prevention of natural disaster such as rock fall and landslide around the circuit road.

• Journal of the Korean Society of Safety
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• v.35 no.5
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• pp.49-58
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• 2020

In domestic construction sites, when installing steel pipe scaffolding and system scaffolding, the guardrails are installed after the installation of the work platforms. This conventional guardrail system (CGS) is always exposed to the risk of falls because the safety railing is installed later. In order to prevent fall disasters during erecting and dismantling scaffolds, it is necessary to introduce the advanced guardrail system (AGS) which installs railings in advance of climbing onto a work platform. For the introduction of the AGS, the structural performance of the system scaffolding applying the CGS and the AGS was compared and evaluated. The structural analysis of the system scaffold (height: 31 m and width: 27.4 m) with AGS confirmed that structural safety was ensured because the maximum stress of each element of the system scaffolding satisfies the allowable stress of each element. As a result of performance comparison of CGS and AGS for each element, the combined stress ratio of vertical posts in AGS was 6.4% lower than that of CGS. In addition, in the case of ledger and transom, the combined stress ratios of AGS and CGS were almost the same. The compression test of the assembled system scaffolding (three-storied, 1 bay) showed that the AGS had better performance than the CGS by 9.7% (8.91 kN). The cross bracing exceeds the limit on slenderness ratio of codes for structural steel design. But the safety factor for the compressive load of the cross bracing was evaluated as meeting the design criteria by securing 3 or more. In actual experiments, it was confirmed that brace buckling did not occur even though the overall scaffold was buckled. Therefore, in the case of temporary structures, it was proposed to revise the standards for limiting on slenderness ratio of secondary or auxiliary elements to recommendations. This study can be used as basic data for the introduction of AGS for installing guardrails in advance at domestic construction sites.