• 연구논문집
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• 통권28호
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• pp.193-207
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• 1998

Fully dense THCN) based carbonitride ceramics were fabricated by pressureless sintering. During sintering, solid solutions were formed from the ceramic ingredients. The ceramics exhibited microvickers hardness of 1560-2050kgf/mm2, fracture toughness of 3.0-5.4 MPa $m^(1/2)$, and three point flexural strength of 645-1072 MPa. Some of the ceramics were shaped in a cutting tool, and the cutting performance was evaluated. In case of cutting SCM440 alloy steel, the ceramics showed better performance than the commercially available alumina-titanium carbide ceramic cutting tool. Considering the excellent productivity of pressureless sintering compared with other densification methods and their cutting performance, this new class of ceramics are very promising for wear resistant applications.

• 대한건축학회논문집:구조계
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• 제36권5호
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• pp.147-154
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• 2020

Currently, there are no specific repair methods for RC structures damaged by fire, and repair methods are applied when durability deteriorates due to aging. In addition, a number of recent studies have been reported that have conducted fire resistance assessment of the repair materials themselves, assuming exposure to high-temperature environments such as fires. However, researches that evaluate the fire resistance performance of the repair materials by applying existing repair materials to the actual fire damaged reinforced concrete structures are very rare. Therefore, in this study, a number of existing repair materials were applied to fire-damaged concrete column to compare and evaluate the fire resistance performance with the original cover concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.23-24
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• 2021

Since 2011, apartment houses account for about 41% of the fires in residential facilities for the past 10 years. Fire-resistant performance of fire doors is becoming more important to prevent the spread of fire in apartment houses. This research analyzed the structure of fire door through each 10 DB based on the quality inspection report of Continuous Acquisition & Life-cycle Support(CALS) from 2016 to 2020, which passed the fire performance test based on the laws and notices of domestic fire door. Therefore, based on the results of the analysis of DB in the future, we will conduct a study on structural improvement and addition for fireproof performance improvement of fire door.

• 한국기계가공학회지
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• 제17권2호
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• pp.89-94
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• 2018

Due to industrial advancement and environmental concerns, there is a demand for light-weight material parts with high-performance characteristics. In order to meet this demand, various studies have been conducted on developing high-performance castings to achieve composite features by coating only specific parts that require high performance, with dissimilar joining, rather than coating the entire material part. This study analyzed the possibility of forming a local composite layer on an aluminum alloy through evaporation pattern casting, and the effects of parameters on the aluminum alloy.

• Computers and Concrete
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• 제22권1호
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• pp.63-70
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• 2018

The steel fiber reinforced concrete (SFRC) shows better performance under dynamic loading than conventional concrete in virtue of its good ductility. In this paper, a series of quasi-static experiments were carried out on the SFRC with volume fractions from 0 to 6%. The compressive strength increases by 38% while the tension strength increases by 106% when the fraction is 6.0%. The contact explosion tests were also performed on the ${\Phi}40{\times}6cm$ circular SFRC slabs of different volume fractions with 20 g RDX charges placed on their surfaces. The volume of spalling pit decreases rapidly with the increase of steel fiber fraction with a decline of 80% when the fraction is 6%, which is same as the crack density. Based on the experimental results, the fitting formulae are given, which can be used to predict individually the change tendencies of the blast crater volume, the spalling pit volume and the crack density in slabs with the increase of the steel fiber fraction. The new formulae of the thickness of damage region are established, whose predictions agree well with our test results and others. This is of great practical significance for experimental investigations and engineering applications.

• 디지털융복합연구
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• 제18권3호
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• pp.227-234
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• 2020

이 연구는 종합병원 간호사를 대상으로 다제내성균 감염관리 수행도에 영향을 미치는 요인을 확인하여 감염관리 교육프로그램 개발의 기초자료를 제공하고자 시도되었다. 202명의 간호사를 대상으로 구조화된 설문지를 이용해 자료를 수집하였다. 연구결과 간호사의 다제내성균 감염관리 지식은 평균 17.68점이었으며 간호사의 지각된민감성, 지각된 심각성, 지각된 유익성과 수행도는 양의 상관관계가 있었다. 또한 일반적 특성에서 결혼, 임상경력, 직위, 근무부서에 따라 수행도의 차이가 있었다. 다제내성균 감염관리 수행도에 영향을 미치는 요인으로는 지각된 유익성과 근무부서로 설명력은 35%였다. 간호사의 다제내성균 감염관리 교육프로그램 개발시 다제내성균 감염관리 지침 수행에 따른 장점, 효과 등을 포함하여 유익성을 강조하는 것이 필요하다. 또한 간호사를 대상으로 다제내성균 감염관리 교육이 필수적으로 시행되어야 한다.

• Wind and Structures
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• 제32권1호
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• pp.55-69
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• 2021

Ultrapure ferritic stainless steel provides a new generation of long-span metal roof systems with continuous welding technology, which exhibits many unknown behaviors during wind excitation. This study focuses on the wind-resistant capacity of a new continuous welding stainless steel roof (CWSSR) system. Full-scale testing on the welding joints and the CWSSR system is performed under uniaxial tension and static ultimate wind uplift loadings, respectively. A finite element model is developed with mesh refinement optimization and is further validated with the testing results, which provides a reliable way of investigating the parameter effect on the wind-induced structural responses, namely, the width and thickness of the roof sheeting and welding height. Research results show that the CWSSR system has predominant wind-resistant performance and can bear an ultimate wind uplift loading of 10.4 kPa without observable failures. The welding joints achieve equivalent mechanical behaviors as those of base material is produced with the current of 65 A. Independent structural responses can be found for the roof sheeting of the CWSSR system, and the maximum displacement appears at the middle of the roof sheeting, while the maximum stress appears at the connection supports between the roof sheeting with a significant stress concentration effect. The responses of the CWSSR system are greatly influenced by the width and thickness of the roof sheeting but are less influenced by the welding height.

• 한국항공우주학회지
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• 제49권5호
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• pp.355-363
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• 2021

리오셀계 탄소/페놀릭 복합재료의 항공우주용 내열 부품 적용 가능성을 확인하기 위하여 내열성능 평가 및 열 해석을 수행하였다. 탄소/페놀릭의 열반응 평가는 내열성능평가모터(Thermal Protection Evaluation Motor, TPEM)로 수행되었다. 본 논문에서는 열 해석을 위해 유체의 경계층 해석을 고려한 경계층 적분 코드와 삭마 및 열분해를 고려한 MSC-Marc 2018 코드를 사용하였다. 추진기관의 압력 곡선, 연소 시험 후 절개된 목삽입재 시편을 통하여 삭마 및 단열성능을 분석하였고, 리오셀계 탄소/페놀릭 복합재료의 열반응은 레이온계 탄소/페놀릭 재료와 유사하였다. 연소시험을 통한 결과를 바탕으로 국산 리오셀계 탄소/페놀릭의 항공우주용 내열 부품으로의 적용 가능성을 확인하였다.

• Structural Monitoring and Maintenance
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• 제10권3호
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• pp.243-260
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• 2023

Indonesia has had seismic codes for earthquake-resistant structures designs since 1970 and has been updated five times to the latest in 2019. In updating the Indonesian seismic codes, seismic hazard maps for design also update, and there are changes to the Peak Ground Acceleration (PGA). Indonesian seismic design uses the concept of building performance levels consisting of Immediate occupancy (IO), Life Safety (LS), and Collapse Prevention (CP). Related to this performance level, cases still found that buildings were damaged more than their performance targets after the earthquake. Based on the above issues, this study aims to analyze the performance of base isolation design on existing target buildings and analyze the seismic fragility for a case study in Indonesia. The target building is a prototype design 8-story medium-rise residential building using the reinforced concrete moment frame structure. Seismic fragility analysis uses Incremental Dynamic Analysis (IDA) with Nonlinear Time History Analysis (NLTHA) and eleven selected ground motions based on soil classification, magnitude, fault distance, and earthquake source mechanism. The comparison result of IDA shows a trend of significant performance improvement, with the same performance level target and risk category, the base isolation structure can be used at 1.46-3.20 times higher PGA than the fixed base structure. Then the fragility analysis results show that the fixed base structure has a safety margin of 30% and a base isolation structure of 62.5% from the PGA design. This result is useful for assessing existing buildings or considering a new building's performance.

• International Journal of Advanced Culture Technology
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• 제12권1호
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• pp.190-201
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• 2024

This study examined the effect of the distance Infection Control Education Program (ICEP), developed based on the ADDIE model, on infection control knowledge, attitude, and performance among care workers in long-term care facilities nationwide. The program, developed based on the ADDIE model, was applied to 173 care workers directly responsible for nursing care of elderly residents in lomg-term care facilities. The distance ICEP for care workers was conducted through the website and lasted 30 minutes for each of the eight topics. To determine the effectiveness of the education, infection control knowledge, attitude, performance, and satisfaction were surveyed before and four weeks after the program. Differences in infection control knowledge, attitude, and performance before and after the distance ICEP were assessed by a t-test. A significant difference was observed in knowledge and infection control performance after the distance ICEP was administered to care workers. In the sub-domains of infection control performance, overall understanding of infection, regular infection control education, infection control by special pathogen (multidrug-resistant bacteria, tuberculosis, tick-borne infectious diseases), and detailed infection control education by infection site (pressure ulcers and urinary tract infections) were significantly improved. Infection control knowledge and performance improved through the distance ICEP applied to care workers. Satisfaction also displayed high scores on most items and indicated that it was helpful for infection control in facilities, confirming the effectiveness of infection control education. Based on the survey of care workers nationwide, the infection education program can be effectively used for care workers in the future.