• Proceedings of the KSR Conference
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• 1998.05a
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• pp.436-441
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• 1998

We developed the composite long rod insulator for railway, and the developed insulators were applied to commercial lines, KNR through a series of preparations such as establishment of specification, diverse tests and evaluation of reliability, and improvement of manufacturing system, etc. This paper presents some considerations for mass Production of the composite insulators in view of steady quality especially. 1 believe that our tries, though it is incomplete in view of low cost, is effective in good performance of the insulators in service and these in-service experience is enough to be a basis of more progress in field of insulation technique.

• International Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.24-28
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• 2015

Composite materials are highly sensitive to the presence of manufacturing and service-related defects that can reach a critical size during service condition and thereby may affect the safety of the structure. When the structure undergoes some kind of damage, its stiffness reduces, in turn the dynamic responses change. In order to avoid safety issues early detection of damage is necessary. The knowledge of the vibration behavior of a structure is necessary and can be used to determine the existence as well as the location and the extent of damage.

• Journal of Preventive Medicine and Public Health
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• v.45 no.3
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• pp.148-155
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• 2012

Since the reformation of the National Health Insurance Act in 2000, the Health Insurance Review and Assessment Service (HIRA) in the Republic of Korea has performed quality assessments for healthcare providers. The HIRA Value Incentive Program (VIP), established in July 2007, provides incentives for excellent-quality institutions and disincentives for poorquality ones. The program is implemented based on data collected between July 2007 and December 2009. The goal of the VIP is to improve the overall quality of care and decrease the quality gaps among healthcare institutions. Thus far, the VIP has targeted acute myocardial infarction (AMI) and Caesarian section (C-section) care. The incentives and disincentives awarded to the hospitals by their composite quality scores of the AMI and C-section scores. The results of the VIP showed continuous and marked improvement in the composite quality scores of the AMI and C-section measures between 2007 and 2010. With the demonstrated success of the VIP project, the Ministry of Health and Welfare expanded the program in 2011 to include general hospitals. The HIRA VIP was deemed applicable to the Korean healthcare system, but before it can be expanded further, the program must overcome several major concerns, as follows: inclusion of resource use measures, rigorous evaluation of impact, application of the VIP to the changing payment system, and expansion of the VIP to primary care clinics.

• Steel and Composite Structures
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• v.34 no.3
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• pp.321-332
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• 2020

The loss of composite action at the hogging moment zone for a continuous composite girder reduces the girder stiffness and strength. This paper presents an experimental investigation of the use of an ultra-high performance concrete (UHPC) slab at the hogging moment zone and a normal concrete (NC) slab at the sagging moment zone. The testing was conducted to verify the level of loading at which composite action is maintained at the hogging moment zone. Four two-span continuous composite girders were tested. The thickness of the UHPC varied between a half and a full depth of slab. The degree of shear connection at the hogging moment zone varied between full and partial. The experimental results confirmed the effectiveness of the UHPC slab to enhance the girder stiffness and maintain the composite action at the hogging moment zone at a load level much higher than the upper service load limit. To a lesser degree enhanced performance was also noted for the smaller thickness of the UHPC slab and partial shear connection at the hogging moment zone. Plastic analysis was conducted to evaluate the ultimate capacity of the girder which yielded a conservative estimation. Finite element (FE) modeling evaluated the girder performance numerically and yielded satisfactory results. The results indicated that composite action at the hogging moment zone is maintained for the degree of shear connection taken as 50% of the full composite action and use of UHPC as half depth of slab thickness.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.445-454
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• 2003

Health monitoring is a major concern not only in the design and manufacturing but also in service stages for composite laminated structures. Excessive loads or low velocity impact can cause matrix cracks and delaminations that may severely degrade the load carrying capability of the composite laminated structures. To develop the health monitoring techniques providing on-line diagnostics of smart composite structures can be helpful in keeping the composite structures sound during their service. In this study, we discuss the signal processing techniques and some applications for health monitoring of composite structures using piezoceramic sensors and fiber optic sensors.

• Archives of Plastic Surgery
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• v.44 no.5
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• pp.370-377
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• 2017

Background Composite grafts are frequently used for facial reconstruction. However, the unpredictability of the results and difficulties with large defects are disadvantages. Adipose-derived stem cells (ADSCs) express several cytokines, and increase the survival of random flaps and fat grafts owing to their angiogenic potential. Methods This study investigated composite graft survival after ADSC injection. Circular chondrocutaneous composite tissues, 2 cm in diameter, from 15 New Zealand white rabbits were used. Thirty ears were randomly divided into 3 groups. In the experimental groups (1 and 2), ADSCs were subcutaneously injected 7 days and immediately before the operation, respectively. Similarly, phosphate-buffered saline was injected in the control group just before surgery in the same manner as in group 2. In all groups, chondrocutaneous composite tissue was elevated, rotated 90 degrees, and repaired in its original position. Skin flow was assessed using laser Doppler 1, 3, 6, 9, and 12 days after surgery. At 1 and 12 days after surgery, the viable area was assessed using digital photography; the rabbits were euthanized, and immunohistochemical staining for CD31 was performed to assess neovascularization. Results The survival of composite grafts increased significantly with the injection of ADSCs (P<0.05). ADSC injection significantly improved neovascularization based on anti-CD31 immunohistochemical analysis and vascular endothelial growth factor expression (P<0.05) in both group 1 and group 2 compared to the control group. No statistically significant differences in graft survival, anti-CD31 neovascularization, or microcirculation were found between groups 1 and 2. Conclusions Treatment with ADSCs improved the composite graft survival, as confirmed by the survival area and histological evaluation. The differences according to the injection timing were not significant.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.203-206
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• 2005

The objective of study on composite cylinder for alternative fuel vehicle is to develop safe, efficient, and commercially viable, on-board fuel storage system for the fuel cell vehicle or natural gas vehicle that use highly compressed gaseous fuel such as hydrogen or natural gas. This study presents the whole procedure of development and certification of a type 3 composite cylinder of 207bar service pressure and 70 liter water capacity, which includes design/analysis, processing of filament winding, and validation through various testing and evaluation. Design methods of liner configuration and winding patterns are presented. Three dimensional, nonlinear finite element analysis techniques are used to predict burst pressure and failure mode. Design and analysis techniques are verified through burst and cycling tests. The full qualification test methods and results for validation and certification are presented.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.65-72
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• 2003

In order to evaluate the strength of carbody structures of railway rolling stock made of laminated fiber-reinforced composite materials, total laminate approach was introduced. Structural analyses were conducted to check the basic design of the hybrid composite carbody structure of the Korean Tilting Train eXpress(TTX) with the service speed of l80km/h. The mechanical tests were also conducted to obtain strengths of composite laminates. The results shown that all stress components of composite carbody structures were inside of failure envelopes and total laminate approach was recommended to predict the failure of composite carbody structures at the stage of the basic design.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.53-56
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• 1999

헬기 로터깃은 최초로 항공기의 일차구조물로 사용된 대형 복합재료구조물이다. 헬기 로터깃은 운용기간(service life)동안에 $10^{7}$이나 $10^{8}$의 high-cycle 피로환경을 경험가게 된다. 로터깃은 복합재료가 알맞게만 사용된다면 거의 무한대의 피로수명을 갖게된다고 알려져 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.918-923
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• 2008

Since crack detection for laminated composites in-service is effective to improve the structural reliability of laminated composites, it have been tried to detect cracks of laminated composites by various nondestructive methods. An electric potential method is one of the widely used approaches for detection of cracks for carbon fiber composites, since the electric potential method adopts the electric conductive carbon fibers as reinforcements and sensors and the adoption of carbon fibers as sensors does not bring strength reduction induced by embedding sensors into the structures such as optical fibers. However, the application of the electric method is limited only to electrically conductive composite materials. Recently, a piezoelectric method using piezoelectric characteristics of epoxy adhesives has been successfully developed for the adhesive joints because it can monitor continuously the damage of adhesively bonded structures without producing any defects. Polymeric materials for the matrix of composite materials have piezoelectric characteristics similarly to adhesive materials, and the fracture of composite materials should lead to the fracture of polymeric matrix. Therefore, it seems to be valid that the piezoelectric method can be applied to monitoring the damage of composite materials. In this research, therefore, the feasibility study of the damage monitoring for composite materials by piezoelectric method was conducted. Using carbon fiber epoxy composite and glass fiber composite, charge output signals were measured and analyzed during the static and fatigue tests, and the effect of fiber materials on the damage monitoring of composite materials by the piezoelectric method was investigated.