• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 15TH KACG TECHNICAL MEETING-PACIFIC RIM 3 SATELLITE SYMPOSIUM SESSION 4, HOTEL HYUNDAI, KYONGJU, SEPTEMBER 20-23, 1998
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• pp.117-121
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• 1998

The Rapid Expansion of supercritical fluid Solutions (RESS) process was applied to particles coating. Experiments were conducted in a fluidized bed with an internal nozzle in the center of the reaction tube. Microcapsules (mean particle size : 49$\mu\textrm{m}$) prepared by spray drying method were used as the core particles. Supercritical CO2 solutions of paraffin were expanded through the nozzle in to the bed that was fluidized by air. Surface morphology prepared particles was observed by SEM. For the inspection of particle size change, particle size distributions were measured before and after coating. The releasing behavior of Mg2+ ions inspected by AA.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.97-100
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• 2004

Steel encased composite columns are widely used due to their excellent structural performance in terms of stiffness, strength, and ductility. However, experimental studies were usually for the columns having higher steel ratio $(3-4\%)$. There are two different design concepts for SRC columns. ACI-318 specifies the design strength of the column using the same concept of reinforced concrete columns. AISC-LRFD specifies the P-M diagram using the concept of steel column. In this paper, SRC columns have the steel ratio of $0.53\%\;and\;1.06\%$. From the test results, ACI-318 specifications showed better evaluation of SRC columns having low steel ratio. H beam and steel tube partially filled with concrete were embedded in concrete. Flexural tests showed considerably high ductility.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.317-320
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• 2006

In order to determine a minimum thickness of the pultruded GFRP panel as a structural member, some experimental studies were performed. GFRP tubes with 2mm, 4mm, 6mm thickness were manufactured by pultrusion process. First, coupon tests for finding mechanical properties were carried out. Comparisons between test results and analysis results based on classical laminate theory showed large differences in case of 2mm, 4mm specimens. The reason is that it is difficult to apply appropriate pultruding force and keep layered stitched fabric flat for the pultrusion process of complex shaped FRP member with small thickness. On the consequence, we decide 6mm as a minimum thickness of FRP member. Second, 4-point bending tests were performed and the results with compared with numerical analysis. The behavior of FRP tube can be exactly predicted by numerical analysis if buckling analysis is included.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.648-649
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• 2006

The dry-milling technique was used for mixing and crushing oxides and graphite powders. The ratio of ball-to-powder was 30:1 and argon gas was filled in jar. The excess carbon was $10{\sim}20wt%$ of the stoichiometric amount. The dry-milling was carried for 20 hours. The mixed powders were reduced and carburized at $900{\sim}980^{\circ}C$ for 3 hours flowing Ar gas in tube furnace. The dry-milled powders showed the wide diffraction patterns of X-ray. The reactions of reduction and carburization were completed in 3 hours at $980^{\circ}C$. After the reactions, the mean size of WC particles was about 200 nm. The content of free carbon in WC/Co mixed powders was less as the reaction temperature increased.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.599-600
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• 2006

This paper described the state of art of porous metal materials, the typical manufacturing technologies and performances of sintered metal porous materials, with emphasis on the recent research achievements of CISRI in development of porous metal materials. High performance porous metal materials, such as metallic membrane, sub-micron asymmetric composite porous metal, large dimensional and structure complicated porous metal aeration cones and tube, metallic catalytic filter elements, lotus-type porous materials, etc, have been developed. Their applications in energy industry, petrochemical industry, clean coal process and other industrial fields were introduced and discussed.

• Structural Engineering and Mechanics
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• 제88권3호
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• pp.287-299
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• 2023

This article describes experimental and numerical analyses of eccentrically loaded over the axially loaded circular concrete filled double-skinned steel tubular (CFDST) short columns. Tests on circular CFDST short columns under eccentric and concentric loading were conducted to assess their responses to the frequent intensity of 5-30 mm at the interval of each 5 mm eccentric loading conditions with constant cross-sectional proportions and width-to-thickness ratios of the outside and internal tubes. The non-linear finite-element analysis of circular CFDST short columns of eccentrically loaded over the axially loaded was performed using the ABAQUS to predict the structural behavior and compare the concentric loading capacity over the various eccentric loading conditions. The comparison outcomes show that the axial compressive strength of the circular CDFST short columns was 2.38-32.86%, lesser than the concentrically loaded short column with the inner circular section. Also, the influence of computer simulation employed is more efficient in forecasting the experimentally examined performance of circular CFDST stub columns.

• Geomechanics and Engineering
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• 제35권2호
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• pp.181-194
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• 2023

The primary objective of this study is to examine the influence of geometry on the stability characteristics of cylindrical microstructures. This investigation entails a stability analysis of a bi-directional functionally graded (BD-FG) cylindrical imperfect concrete beam, focusing on the impact of geometry. Both the first-order shear deformation beam theory and the modified coupled stress theory are employed to explore the buckling and dynamic behaviors of the structure. The cylinder-shaped imperfect beam is constructed using a porosity-dependent functionally graded (FG) concrete material, wherein diverse porosity voids and material distributions are incorporated along the radial axis of the beam. The radius functions are considered in both uniform and nonuniform variations, reflecting their alterations along the length of the beam. The combination of these characteristics leads to the creation of BD-FG configurations. In order to enable the assessment of stability using energy principles, a numerical technique is utilized to formulate the equations for partial derivatives (PDEs).

• 국제초고층학회논문집
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• 제12권3호
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• pp.235-239
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• 2023

In this study, the fire resistance performance of the concrete-filled steel tube (CFT) columns and thin steel-plate composite (TSC) beams installed at a 20-story office building were designed using a performance-based structural fire design. Because of the lack of any specific provisions in the building code and guidelines for structural engineers about the performance-based approach, the only prescriptive approach has been selected for designing fire-resistant structures in Korea. To evaluate the fire resistance performance of the CFT columns and TSC beams, finite element analysis verified by the experimental results studied by several researchers was conducted with ABAQUS. From the fire scenario, the temperature distributions of the CFT columns and TSC beams were found via finite element analysis and the behaviors of the CFT columns and TSC beams were investigated in the structural field based on the temperature distribution.

• Composites Research
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• 제23권4호
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• pp.44-51
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• 2010

최근 토목분야에서 철근콘크리트 압축재에 발생하고 있는 부식, 중성화 등의 문제점을 해결하기 위해 섬유강화복합재로 외부를 보강한 합성부재가 개발되어 적용되고 있다. 이러한 합성부재는 외부를 섬유강화플라스틱으로 보강하고 있어 부재 전체의 구조적 성능을 향상시킬 뿐만 아니라 내화학성이 우수하여 기존 콘크리트 부재와 비교할 때 내구성이 향상된다. 그러나 복합재로 외부를 보강한 콘크리트 합성부재에 대한 기존 연구자료들은 구조적 거동해석에서 큰 차이가 없이 유사한 결과를 보여주었으나 그 결과가 부재의 단면구성과 크게 관계되기 때문에 이 연구에 직접적으로 적용하는데는 어려움이 있고, 또한 설계기준으로 적용하기에는 여전히 미흡한 실정이다. 이 연구에서는 RCFFT 부재의 설계규준 마련을 위한 기초자료를 확보하기 위해 압축 및 준정적 휨실험을 수행하여 구조적 거동을 조사하였고, 압축강도를 추정할 수 있는 근사식을 제안하였으며, 휨강성을 예측할 수 있도록 하였다.

• Restorative Dentistry and Endodontics
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• 제32권1호
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• pp.1-8
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• 2007

본 연구는 자가 산부식 접착제를 적용한 법랑질에 광중합과 이원중합 복합레진을 접착시켜 접착제와 복합레진의 종류에 따른 미세전단 결합강도를 상호 비교하기 위하여 시행하였다. 발거된 상 하악 대구치를 근, 원심 방향으로 1 mm 두께가 되도록 절단하여 사용된 접착제의 종류에 따라 Xeno 군 (Xeno III), Adper 군 (Adper Prompt L-Pop), AQ 군(AQ Bond)으로 분류하였다. 각 시편의 법랑질 표면에 각 군에 해당하는 접착제를 적용한 후 Tygon tube를 이용하여 광중합형 복합레진 (Z 250)이나 이원중합 복합레진 (Luxacore)을 접착하였다. 실온의 증류수에 24시간 동안 보관한 후. universal testing machine을 이용하여 각 시편의 복합레진과 법랑질의 접착계면이 파절될 때가지 분당 1 mm의 crosshead speed를 가하여 미세전단 결합강도를 측정 한 후 통계학적으로 분석하여 다음과 같은 결과를 얻었다. 1. 동일 접착제로 결합된 광중합과 이원중합 복합레진의 법랑질에 대한 미세인장 결합강도는 광중합 복합레진에서 통계학적으로 높게 나타났다 (p<0.05). 2. Z 250을 접착시킨 각 군의 미세전단 결합강도는 Xeno군에서 $7.73{\pm}2.01\;MPa$, Adper군에서 $6.74{\pm}1.80\;MPa$, AQ 군에서 $9.59{\pm}2.51\;MPa$를 나타내어 AQ 군이 Adper군 보다 통계학적으로 높게 나타났다 (p<0.05). 3. Luxacore를 접착시킨 각 군의 미세전단 결합강도는 Xeno군에서 $5.19{\pm}1.32\;MPa$, Adper 군에서 $3.41{\pm}1.19\;MPa$, AQ군에서 $4.50{\pm}0.96\;MPa$를 나타내어 Xeno군이 Adper군 보다 통계학적으로 높게 나타났다(p<0.05).