• Smart Structures and Systems
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• 제15권6호
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• pp.1439-1461
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• 2015

Design criteria, modeling rules, and analysis principles of seismic isolation systems have already found place in important building codes and standards such as the Uniform Building Code and ASCE/SEI 7-05. Although real behaviors of isolation systems composed of high damping or lead rubber bearings are nonlinear, equivalent linear models can be obtained using effective stiffness and damping which makes use of linear seismic analysis methods for seismic-isolated buildings possible. However, equivalent linear modeling and analysis may lead to errors in seismic response terms of multi-story buildings and thus need to be assessed comprehensively. This study investigates the accuracy of equivalent linear modeling via numerical experiments conducted on generic five-story three dimensional seismic-isolated buildings. A wide range of nonlinear isolation systems with different characteristics and their equivalent linear counterparts are subjected to historical earthquakes and isolation system displacements, top floor accelerations, story drifts, base shears, and torsional base moments are compared. Relations between the accuracy of the estimates of peak structural responses from equivalent linear models and typical characteristics of nonlinear isolation systems including effective period, rigid-body mode period, effective viscous damping ratio, and post-yield to pre-yield stiffness ratio are established. Influence of biaxial interaction and plan eccentricity are also examined.

• 패션비즈니스
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• 제15권5호
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• pp.103-114
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• 2011

During a wearer's movement, the apparel fabric layers collide each other in a highly complicated manner. The collision involves cloth-cloth, and cloth-body collision. The diversity of the textile fabrics, including silk, wool, cotton, and other synthetic fibers, together with the complex details of the apparel construction, makes the collision and other calculation procedure involved in the 3-dimensional clothing software system much more complicated. Therefore, there is a need to measure the behavior of the fabrics during the fabric collision cycles. In this study, as a first step, static measurements pertinent to the factors governing the appearance of the apparel fabrics were implemented. The drape profile, stiffness(Sd and Sf), tensile properties, thickness, and the air permeability were measured. The correlation between the parameters were calculated and reviewed. It is found that there is a high correlation of 0.97 between the actual fabric drape parameters and the 3D virtual fabric drape parameters. The measured drape coefficients of the fabrics show relatively good correlation with the measured fabric stiffness.

• 대한임상검사과학회지
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• 제51권3호
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• pp.277-285
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• 2019

비만과 혈관 경직도간에 역상관 관계가 보고되고 있으나, 고령자나 노인에서는 일관된 결과를 보이고 있지 않다. 이 연구에서는 건강한 노인을 대상으로 CAVI로 측정한 동맥 경직도와 BMI간의 연관성을 조사하였다. 이 연구는 2018년 7월부터 2019년 6월까지 경기지역 종합병원에서 건강검진을 시행한 65세 이상 건강한 노인을 629명을 대상으로 하였다. 대사증후군 진단은 US National Cholesterol Education Program(NCEP)의 Adult Treatment Panel (ATP) III의 기준에 따랐으며, NCEP-ATP III의 기준 중 허리둘레 및 비만기준은 WHO의 기준에 따랐다. 모든 연구 대상자는 생화학적 혈액검사 및 CAVI를 측정하였다. 남녀 모두에서 CAVI치는 정상체중군보다 비만군에서 낮았으며, 성별(P=0.047), 연령(P<0.001), BMI (P<0.001), 허리둘레(P=0.009)는 CAVI에 영향을 미치는 요인이었다. 또한 성별, 높은 혈압, 고혈당은 CAVI치의 독립적인 정적 예측인자이지만, 비만은 부적 예측인자로 나타나 CAVI와 BMI는 역상관 관계를 보였다. 결론적으로, 이 연구는 노인을 대상으로 CAVI와 BMI간에 역상관 관계를 나타내며, BMI로 측정한 비만은 CAVI의 부적 예측인자였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.208-211
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• 2005

This paper describes the development process of steering system for reduce idle vibration through the data level of frequency and sensitivity. High stiffness and light weight vehicle is a major target in the refinement of passenger cars to meet customers' contradictable requirements between NVH performance and fuel economy. The target frequency of the steering system is set by benchmarking of a competitive vehicle and the vibration mode map is used to separate steering column modes from resonance of body structure and engine idle rpm. This paper descirbes the analysis approach process for high stiffness of steering system and the design guideline is suggested about steering column and support system by using mother car at initial design stage. We used a patent map in order to analyze accurately a technical trend and suggested the design process using dynamic damper of steering system considering sensitivity. And we established techniques of analysis on steering system and evaluated the level of accuracy of analysis through correlating the test and analysis results. It makes possible to design the good NVH performance vehicle at initial design stage and save vehicles to be used in tests. These improvements can lead to shortening the time needed to develop better vehicles.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.102-103
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• 2014

Due to the nature of the existing load, the criteria of assessing the intensity of the lightweight wall's impact resistance has been though of as obscure. The current study, therefore, focuses on the standardized assessment of the impact resistance to the force of the large soft body applying to the lightweight wall. The gypsum board wall showed a low level of the maximum residual displacement. It is, however, required to be careful about the selection of the finishing process since the high level of the maximum displacement is likely to cause harm to finishing materials. Unlike the gypsum board, the ALC block wall displayed a considerable rigidity while showing almost no maximum residual displacement. Even with the low level of the maximum displacement due to the stiffness, the ALC block wall is still likely to be affected by the vibration derived from any impact on the surface, which demands a need for additional study. The future experimental study, accordingly, will focus on the impact of the vibration on finishing materials, consequently leading to the accurate prediction of the possibility of potential damage to the lightweight wall caused by the large soft body.

• 한국가시화정보학회지
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• 제19권1호
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• pp.18-27
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• 2021

As the photo-voltaic (PV) industry grows, the floating PV has been suggested to resolve current environmental destruction and a lack of installation area. Currently, various floating PV systems have been developed, but there is a lack of studies on how the shape of the floating body and other compositions are affecting structural behavior. In this study, the behavior of the floating PV was investigated at the various length of mooring lines, stiffness of connecting hinges, and size of floating bodies. The shortest mooring lines with the distributed type floating PV showed the least force on the floating body and corresponding motion. A frictionless hinge is safer at the regular and low-height wave, while a stiff hinge is safer at irregular and high-height wave. In addition, due to the bi-axial distribution of the connecting hinge, 45° direction wave was found to be the most dangerous.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 춘계학술발표대회 논문집
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• pp.65-68
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• 2003

Using composite materials for lilting train system has many advantages such as manufacturing variety, specific high-strength & stiffness characteristics, and long-life durability, but the strongest advantage could be the possibility of lightweight product. In the leading countries, the composite materials are used for the material fer drivers' cabs, interior/exterior equipments for railway train, and it is now developing the composite materials applied for the train car body structure. In this paper, we examine the use of composite materials for the drivers' cabs and interior/exterior equipments for the developing tilting train in Korea, and review the car body design using composite materials.

• 소음진동
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• 제7권2호
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• pp.261-272
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• 1997

Recently washing machines are to be in lower vibration and lower sound because of better environment. Vibration problems in washing machines occur in both washing mode and spinning mode, but vibration in spinning mode becomes main problem because of its high rotating speed and continuity. Vibration while spinning is mainly due to rigid body motion of total washing system which includes suspending rods, washing bath, spinning bath, and gear sets. In this study, some researches were done in order to analyze the rigid body motion of washing system and flexible vibration of spinning bath. A basic mathematical model was established, and the effect of position of salt water and shape change of salt water case were considered. And the effect of lengths of suspending rods, attaching angles, vertical and horizontal position, stiffness of spring on the change of vibration were also considered. To identify the effect of salt water on vibration, some measurements were done. When salt water was positioned at upper part, the effect was most and this coincides with the tendency of simulation.

• 한국산학기술학회논문지
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• 제18권6호
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• pp.78-84
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• 2017

최근 자동차 업계는 연비향상 및 안전성 강화를 위해 경량 신소재를 적용하여 부품의 경량화를 추구하고 있다. 이를 위해 차체 부품 소재로서 고장력강판의 적용 비중이 50%를 넘고 있는 실정이다. 이에, 본 논문에서는 범퍼빔 부품의 소재로 고장력강판 적용을 위한 기초 연구로서 소재 및 두께 변경에 따른 범퍼빔의 구조강성과 에너지 흡수능력을 해석적 방법으로 비교 평가하였다. 우선 고장력강판을 범퍼빔에 적용하기 위해 기존의 범퍼빔 단면형상과는 다른 타입의 범퍼빔 단면형상을 설계하였으며, 굽힘해석을 통해 설계된 범퍼빔이 충분한 구조성능, 즉, 구조강성과 굽힘하중력을 가지고 있는지 조사하였다. 중앙접합부의 형상에 따라 굽힘에 대한 구조성능은 현저한 차이가 관찰되지는 않았으며, 25ton, 7.5ton/mm내외의 충분한 굽힘저항력과 강성을 가지고 있는 것으로 조사된다. 또한, 충돌해석을 통해 소재 및 두께를 변경하였을 경우의 효과를 비교평가하였다. 해석결과 고장력강판을 범퍼빔에 적용하기 위해서는 두께를 줄임으로써 기존소재에 버금가는 에너지흡수성능을 구현할 수 있으며, 동시에 뚜렷한 경량화를 이룰 수 있을 것으로 판단된다. 본 기초연구를 토대로 고장력강판 범퍼빔의 구조성능 개선을 위한 향후 연구방향에 대해 제시하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.181-186
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• 2002

Laser welding application for car body manufacturing has many advantages in the stiffness and the lightness of vehicle, the productivity of assembly line, and the degree of freedom in design. This presentation will express the innovation of car body manufacturing including parameter optimization, process modeling, and system integration. In this application the investment for systems was cut down dramatically by real time switching over the laser path between two welding stations. Points of technical discussion are as follows: optimization of parameters such as laser power, robot speed and trajectory, compact and useful design of jig & fixture to assure welding quality for 3 sheet-layer zinc-coated steel, system integration between 4kW Nd:YAG laser device and the other systems, on-line real time welding quality monitoring system, perfect safety standards for high power laser, minimization of consumption costs such as arc lamp, protective glass for optic, etc. Laser welding has found a place on Hyundai's production plant in conjunction with the startup of mass production of new sports car, and this production system is the result of a collaboration of its engineers. Outer side sheets are joined to inner side sheets by 122 stitch welds totally. And the length is about 2.4meter.