• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.57-58
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.211-212
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• 2009

• Transactions of Materials Processing
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• v.20 no.6
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• pp.420-426
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• 2011

Dent resistance is determined by both shape characteristics, i.e., local radius of curvature and sheet thickness, and material properties such as yield strength. This work presents results of a study on the effect of work hardening and bake hardening on dent resistance of aluminum alloy sheet parts by considering the forming condition and baking temperature.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.886-888
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• 2001

배관의 덴트 및 주름의 형태 크기와 위치, buckle의 여부와 위치, 배관의 난형도 및 곡률을 파악하기 위해서 사용되는 Gemometry PIG의 캘리퍼 시스템에 Mechanical Finger를 back-yoke의 유무, 영구자석의 크기, Pin Hole의 위치와 영구자석의 위치 등을 3차원 비선형 유한요소법으로 해석한 후 이를 바탕으로 최적설계를 하여 이를 실제 제작하여 측정치와 비교하였다.

• 학교보건
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• s.2
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• pp.10-13
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• 1976

교육과정이란 학교에서 이루어지는 정규 수업을 통한 교육 뿐만이 아니라 학교 생활 전체를 논하기도 한다. 교육과정은 간단없이 개정되어야 한다. 가령 의학교육에서 생각할 때 국민 의료에 가장 적합한 의사를 양성하기 위해서 혁신적인 교육을 아무리 잘 한다 해도 적합한 교육을 받은 의학생이 의사, 더욱이나 인턴과 레지덴트를 거친 후 국민 의료에 호응코자 할 떄는 벌써 국민 의료의 요구실정은 변화되어 충족을 시키기 힘들다는 것이다. 즉, 요구도는 앞질러 가고 충족도는 뒤늦게 따라 갈 수밖에 없다는 것이다. 따라서 우리 나라에서는 국민학교에서 최근 교육과정을 개정한 바 있고, 중,고등학교에서도 가까운 장래에 개정을 단행하기 위해서 작업을 서두르고 있다. 대학에 있어서는 다른 분야도 그렇겠지만 의학교육에서는 최근 교육과정을 시대적인 요청에 따라서 개정한 바 있다. 여기서는 건강교육을 중심으로 한 교육과정에 반영되어야 할 새로운 분야를 국민학교와 중고등학교 교육의 테두리 안에서 다음과 같이 생각해 보기로 한다.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.2
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• pp.184-190
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• 2008

Various ECT techniques have been applied basically to assess the integrity of steam generator tithing in nuclear power plant. Among these techniques, the bobbin probe technique is applied generally to examine the volumetric flaws such as a crack-like defect and wear which is generally occurred on steam generator tubing, and additionally MRPC probe is used to examine closely tile top of tubesheet and bending regions due to the high possibility of cracking. Dent and bulge also may be formed on tube during installation process and operation of steam generator, but the dent and bulge indications greater than specific size criteria are recorded on examination report because these indications are not considered as flaw. These indications can be easily detected with bobbin probe and approximately sized with profile bobbin probe, but the size and shape can not be accurately verified. Accordingly, in this study, the $8{\times}1$ multi-array EC probe was designed to increase the measurement accuracy of the sectional profiling EC testing of tube. As a result, we would like to propose the application of $8{\times}1$ multi-array EC probe for the measurement of size and shape of profile change on steam generator tube in OPR-1000 nuclear power plant.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.58-65
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• 2010

For the improvement of fuel consumption, the study on the use of lightweight material or thinner sheet have been carried out in automotive industry. With the need for the use of thinner sheet, the dent resistance became one of the major concern in th design of exterior panels in automotive industry. Many studies have been carried out for the dent resistance by experiment or quasi-static numerical simulation. In this study, the dent formation behavior is investigated by dynamic finite element analysis using ABAQUS. Dent formation may be affected by many factors such as sheet thickness, material properties, pre-strain, and sheet curvature. The effect of these factors on dent resistance is investigated. From the analysis following three conclusions are derived. First, dent resistance become hard as the sheet curvature radius increases. Second, dynamic dent resistance is mainly affected by bending stress rather than tensile stress. Third, the pre-strain itself do not give any guidance for dynamic dent resistance and dynamic dent resistance have to be decided considering the strain hardening and thickness reduction together. The results are considered to be reliable and useful to improve the dent damage of automotive panels.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.2
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• pp.20-26
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• 2009

The dominant incidents category for onshore and offshore natural gas transmission pipelines in the world is associated with outside forces. Incidents in the outside forces category embrace acts of nature, which typically cause widespread structural damage, as well as act of man, whose effects tend to cause dents and/or gouges localized at point of contact that are referred to as mechanical damage. Therefore, these damage types must be better addressed to avoid unnecessary and costly repairs and the possibility of catastrophic events. First of all, the characterizing features of mechanical damage in gas pipelines were evaluated by using of excavator or boring machine. There is no reliable method for evaluating the safe operating pressure of pipeline affected by mechanical damage. It is especially important to evaluate the remaining strength of damaged pipelines due to outside force. Therefore, the full scale burst tests were conducted to evaluate the remaining strength of pipe with mechanical damage that combines a dent and a gouge. This paper is supposed to provide information that will assist in developing a criterion to assess serviceability in pipelines with mechanical damage.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.3
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• pp.7-12
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• 2012

Steam generator tubes are critical boundary of the primary and secondary side in nuclear power plants. Eddy current testing is commonly used as the method of non-destructive testing for the safety and integrity of steam generator tubes in the nuclear power plants. Changes in the geometric shape act as a stress concentration factor likely to cause a defect during the steam generator operation. The mixed-signals with the geometric shape are distorted and attributes that are difficult to detect signals. An example is bending stress due to compression process at a U-bend occurring in the intrados region which has a small radius of curvature. The resulting change in the geometric shape may lead to a dent like occurrences. The dent can cause stress concentration and generates stress corrosion cracks. In this study, the steam generator tubes of nuclear power plant were selected to study for analysis of mixed-signal containing dent and stress corrosion cracks.

• Journal of Korean society of Dental Hygiene
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• v.23 no.4
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• pp.227-234
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• 2023

Objectives: Cetylpyridinium chloride CPC-based mouthwashes are well known to have no harmful ingredients in the mouth and can be used for a long time. The purpose of this study was to evaluate the effect of using CPC-based mouthwashes to suppress the biofilm formation and antibiotics for handling orthodontic appliances. Methods: To measure the antibacterial effect, Streptococcus mutans (S. mutans) cultured orthodontic appliances were precipitated in Gargreen and Polident for 5 minutes, incubated at 37℃ for 24 hours(h). In order to measure the biofilm removal effect, the degree of biofilm formation on the orthodontic appliances was stained with a methylene blue and the difference before and after was compared using image J software program (NIH Image J; NIH, Bethesda, MD). Results: The viability of S. mutans according to the concentration showed that Gargreen and Polident inhibited colony formation compared to the control, respectively (p<0.01). The degree of biofilm formation was significantly higher in the control, however both Gargreen and Polident significantly reduced it compared to the before and after condition on removable orthodontic appliances (p<0.01). Conclusions: This study suggests that the use of Gargreen, a cetylpyridinium chloride based oral cleaning cleanser, could be replaced by Polident for antibacterial effect and biofilm formation on removable orthodontic appliances.