• Journal of Korean Society of Steel Construction
• /
• v.18 no.5
• /
• pp.643-654
• /
• 2006

Thispaper presents the results of an experimental investigation into the fire performances ofsimply supported iTECH composite beams using an ISO834 standard fire. There are very few independent studies on the fire resistance of composite steel and concrete structures of various designs. The iTECH composite beam system has been used in construction, but nothing is known about its influence in a fire. To evaluate the fire resistance performanceof the iTECH beam, a test was conducted for 4.7m-span-length iTECH beams under given conditions in a laboratory. The fire resistance performance of unprotected coatings of the iTECH beam has been examined, and a longer period of fire resistance was achieved by increasing the beam coating's section size and decreasing its load ratio. Coatings for the fire protection of iTECH beams reduce the rate of temperature rise of the beam in case of fire, and the required thickness of spray-on fire protection coatings can be determined by means of tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.4
• /
• pp.298-304
• /
• 2014

The lifting-line method based on Weissinger's method is extended to be able to analyze the ground effect. The method is applied to predict the variation of aerodynamic performance due to ground effect for the elliptic wing with aspect ratio of 10 and the wing of human powered aircraft. While the vortex strength of the wing increases slightly, the downwash decreases significantly as the wing approaches to the ground. For the wing of human powered aircraft, the increment of lift at the height of 2m is 5% than the lift outside the influence of ground effect. The decrease of induced drag at the height of wing span is 10% and at the height of 2m is 55% than that out of ground effect.

• Fire Science and Engineering
• /
• v.25 no.6
• /
• pp.64-72
• /
• 2011

The concrete void slab structure with the existing mushroom slab, is the structure that maximizes the advantages, while minimizing the weakness with removing useless body force of the concrete part, located on the center of the slab cross-section, which does not need to support the structural weight. In this research, a fire test is performed to analyze how the blaze behave according to the thickness of slab cover, with the practical span length of concrete void slab for the slab length 7.5 m. With this heating test, we assumed the uniform-load-model considering fixed loads and live loads, and chose the standard fire test condition. We measured the temperature changes and the deflection character according to the depth from the heat exposure side, and assessed the resisting capability according to the standard KS F 2257-1. The result comes out with the EPS model can secure about 2 hour fire-resisting-capability with 50 mm of cover depth.

• Journal of the Korean Institute of Gas
• /
• v.19 no.1
• /
• pp.23-27
• /
• 2015

The stress and deformation behavior safeties of cylindrical hollow rollers have been analyzed by the finite element method, and investigated for over design capability based on the computed results. According to the stress analysis result which is related to the strength of a hollow roller, the maximum stress of 39.8MPa in which is operated near the bearing for supporting a hollow roller structure is overestimated design as 15.9% level compared with a yield strength, 250MPa of a steel material. And the maximum deformation of 0.032mm in which is operated at the middle span of a total length of cylindrical hollow rollers is very small and sufficiently safe compared with a total length and a thickness of a hollow roller. Thus, the FEM computed results for a stress and deformation indicate that a current FEM analysis model of cylindrical hollow rollers is over designed.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.57.1-57.1
• /
• 2011

본 논문에서는 소음을 저감하고 구조적 안전도를 향상시키기 위하여 10kW급 소형 복합재 풍력터빈 블레이드를 해석, 설계하였다. 풍력터빈 블레이드 설계의 기본 사항에 맞추어 블레이드의 스팬 길이는 약 4m, 중량은 30kg 내외가 되도록 설정하였다. 풍력발전기용 블레이드는 경량화가 중요하므로 유리섬유복합재 (glass fiber reinforce pastics), 탄소섬유복합재 (carbon fiber reinforced plastics)가 사용되었다. 본 설계에서는 Carbon prepreg (WSN3KY), Carbon UD(UIN150c), E-glass 등을 사용하였다. 상용 유한요소 프로그램인 NASTRAN을 이용해 Carbon prepreg (WSN3KY), Carbon UD (UIN150c)의 탄소섬유복합재만으로 구성된 블레이드 구조해석을 수행한 결과 중량 조건 및 강도의 안전도는 충족되었으나, 높은 가격을 감안하여 E-glass와 조합하여 블레이드를 재설계할 예정이다. 이번 설계는 소형 풍력발전용 블레이드 설계이므로 좌굴은 고려하지 않았으며, 향후 필요에 따라서 좌굴 및 피로해석도 수행하여 검증할 예정이다. 그리고 블레이드가 복합재로 구성되면 감쇠력이 감소할 가능성이 있다. 탄소섬유복합재로만 구성된 블레이드 구조해석에서도 최대 40cm의 변형이 예측되었으며, 감쇠값 저하 문제도 고려하여야 될 것 같아 BEMT (Blade Element Momentum Theory) 공력모델을 이용해 구조-유체 연성 결합 해석을 수행할 계획이다.

• Journal of Korean Association for Spatial Structures
• /
• v.9 no.2
• /
• pp.91-97
• /
• 2009

This study presents geometric nonlinear and material analysis of under-tension structure using Total Lagrangian and Updated Lagrangian method. In the regard, the under-tension system enables the load of upper part to carry to the end of beam by pre-tensional force in cable. The under-tension system on lower part of the structure is applied in order to reduce the deflection and size of member. This study is performed with conforming of the effect by pretension value in the cable and applying loading. Dead and Live loads are supposed to apply nodal on the top member. The member force and deflection of the structure are with MIDAS and ADINA.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.6 no.3
• /
• pp.63-71
• /
• 2002

The seismic design regulations have not been applied to the low-rised buildings which are less than 6 stories in Korea. For these buildings which are designed only for gravity loads, theoretical formulas which can estimate the seismic strength of building are derived. The column hinge sway and beam hinge sway mechanism are assumed for the formulars. For the comparisons with the formulas, the results of push-over analyses of 3 and 4 storied buildings are used. It can be shown that the estimating formulas correspond well with the push-over analyses. And the seismic strength of building has a little relations with the number of bay and becomes larger as the building becomes lower. Also, as the ratio and strength of reinforcing steel increase, the seismic strength of building is increased.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.8 no.1
• /
• pp.29-37
• /
• 2004

The overstrength factor and the ductility factor are the two important factors that determine response modification factors used in current seismic codes, In this paper the overstrength and ductility factors of special concentric braced frames are determined by performing pushover analysis of model structures with various stories and span lengths. and by using those factors the response modification factors are obtained. According to the analysis results. the overstrength and the ductility factors are larger than the values proposed by the codes in low-rise structures. and the opposite is true in medium to high-rise structures, It is also found that the factors increase as the height of structures decreases and the span length increases.

• Journal of the Korea Concrete Institute
• /
• v.22 no.5
• /
• pp.703-710
• /
• 2010

Reinforced concrete beams of existing structure often encounter insufficient shear problems for various reasons. Application of steel plates is one of widely used methods for shear strengthening of reinforced concrete beams that are insufficient of shear capacity. This study presents test results on strengthening shear deficient RC beams by external bonding of vertical and diagonal slit type steel plates with anchor bolt. Test parameters are width, interval, angle and length of slits with anchor bolt. The purpose was to evaluate the failure modes and shear capacities for RC beams strengthened by various slit type steel plates with anchor bolt. The results showed that the slit type steel plate specimens strengthened by adhesive bonding and bolting failed in shear fracture modes at maximum load. Flexural crack first occurred on the tension face of beam and then inclined cracks occurred on the shear span. Finally, slit type steel plates strengthened by adhesive bonding and fastening bolts managed to delay abrupt debonding and didn't detach fully from main body of RC beam.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.14 no.6
• /
• pp.60-68
• /
• 2010

In this study, the conventional plane tip, double squealer tip, and various groove tip blades were tested in a linear cascade in order to measure the effect of the tip shapes on tip surface heat transfer coefficient distributions. Detailed heat transfer coefficient distributions were measured using a hue-detection based transient liquid crystals technique. Two tip gap clearances of 1.5% and 2.3% of blade span were investigated and the Reynolds number based on cascade exit velocity and chord length was $2.48{\times}10^5$. Results showed that the overall heat transfer coefficients on the tip surface with various grooved tips were lower than those with plane tip blade. The overall heat transfer coefficient on grooved along suction side tip was lower than that on the squealer tip.