• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1764-1769
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• 2014

Numerical investigations have been conducted on the junction that connect the multi-tubular section and the single shell section in order to evaluate applicability of hybrid sections in wind turbine towers instead of conventional single shell towers. Major characteristics in structural details include extension of multi-tubular member into shell end section, installation of wing stiffeners, and different layout of floor beams. Elastic and nonlinear incremental analyses were conducted to examine stress concentration patterns and ultimate behaviors, respectively. Based on evaluation of structural performance due to vertical and horizontal forces, it has been confirmed that installation of floor beams and wing stiffeners sensitively affect ultimate strength of global wind tower.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.602-606
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• 2011

In this study, operational vibration experiment and analysis have been conducted for the 4-blade small vertical-axis wind turbine (VAWT) including the effect of tower elastic behavior. Computational structural dynamics analysis method is applied to obtain Campbell diagram for the VAWT with elastic tower. An open type wind-tunnel is used to change and keep the wind velocity during the ground test. Equivalent reduced elastic tower is supported to the VAWT so that the elastic stiffness effect of the tower can be reflected to the present vibration experiment. Various excitation sources with aerodynamic forces are considered and the dominant operating vibration phenomena are physically investigated in detail.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.2
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• pp.209-215
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• 2010

In this study, seismic response analyses of a MW class wind-turbine have been conducted considering applied wind-loads using advanced computational method based on CFD and FEM. Typical lateral and vertical acceleration levels induced by earthquake is also considered herein. Practical numerical method for seismic response analysis of wind-turbine tower models are presented in the time-domain and the effects of wind load and seismic excitation for responses are compared to each other. It is importantly shown that possible earthquake effect during typical operating conditions should be taken into account in the design of huge wind-turbine tower systems because of its enormous inertia characteristics for induced maximum stress level.

• Korean Journal of Construction Engineering and Management
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• v.5 no.2 s.18
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• pp.47-54
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• 2004

Recently, many high-rise buildings have been constructed, and are under construction. And a high-rise building with more than 100 floors is under planning. From site logistics management point of view, it is very important to manage vertical transportation of resource (e.g., material, equipment and construction labors) in high-rise building construction. The higher the building is constructed, the more important it is to manage for vertical transportation of it. In case of labors, vertical movement needs longer time in high-rise building construction than in low-rise. This results in low productivity and work efficiency of the construction. Therefore, this study presents a process of a vertical movement plan for labors using discrete-event simulation. And then the process applies to MT 130 project, which is a virtual high-rise building construction project.

• The KSFM Journal of Fluid Machinery
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• v.16 no.3
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• pp.5-9
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• 2013

In this study, operational vibration experiment and analysis have been conducted for the 4-blade small vertical-axis wind turbine (VAWT) including the effect of tower elastic behavior. Computational structural dynamics analysis method is applied to obtain Campbell diagram for the VAWT with elastic tower. An open type wind-tunnel is used to change and keep the wind velocity during the ground test. Equivalent elastic tower is used to support the VAWT so that the effect of elastic stiffness of the tower can be considered in the present vibration experiment. Various excitation conditions with wind loads are considered and the dominant operating vibration phenomena are physically investigated in detail.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.663-670
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• 2011

In this study, the design and verification of 6kW class lift-type vertical-axis wind turbine (VAWT) has been conducted using advanced CAE technique based on computational fluid dynamics (CFD), finite element method (FEM), and computational structural dynamics (CSD). Designed aerodynamic performance of the VAWT model is tested using unsteady CFD method. Designed structural safety is also tested through the evaluation of maximum induced stress level and resonance characteristics using FEM and CSD methods. It is importantly shown that the effect of master eccentricity due to rotational inertia needs to be carefully considered to additionally investigate dynamic stress and deformation level of the designed VAWT system.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.141-147
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• 2002

I-PARK 삼성동 APT PROJECT는 무역센타에서 영동대교 사이의 구릉에 위치한 지상 46층의 주거용 건물로서 3개동 449세대로 구성되었고 각 동을 4세대 조합의 타워형으로 설계되었다. SLAB 구조 방식은 2방향 플랫 프레이트 구조(2WAY FLAT PLATE SLAB SYSTEM)로서 SLAB는 수직하중에 대한 기본적인 지지구조 역할 뿐만 아니라 주 골조 SYSTEM 구성 요소의 일부로서 풍하중 및 지진하중등의 횡력에 대하여 저항할 수 있는 구조로 구성되어 있다. 본 SLAB 구조 SYSTEM을 적용한 국내 최고 높은 건물로서 당 현장에 적용된 시공사례중 가설계획, 고강도 콘크리트, SYSTEM FORM, RE-BAR, 4-DAY CYCLE SCHEDULE 등에 대하여 기술하기로 한다.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.153-157
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• 2007

본 논문은 지표면 현상의 관측에 날씨의 영향을 거의 받지 않는 마이크로파 L-밴드(1.95 GHz)와 C-밴드(5.3 GHz) scatterometer 시스템을 이용하여 농업과학기술원 내의 논에서 자라는 추청벼를 대상으로 2006년 5월 29일부터 10월 9일까지 생육에 따른 군락의 후방산란계수를 관측한 데이터와 작물의 생육과의 관계를 살펴보고 또한，측정 시스템의 개요，측정 시스템의 보정 방법들을 기술하고자 한다. Scatterometer 시스템의 송 수신기로 HP 8753D 벡터 네트워크 분석기를 사용하며，타워 위에 안테나를 설치하여 3.4 m의 높이에서 측정하도록 하였다. L-밴 드와 C-밴드 scatterometer는 VV-, VH-, HV-, HH-편파를 측정하여 fully polarimetric한 데이터를 얻도록 설계된 레이더시스템으로 입사각을 $30^{\circ}{\sim}60^{\circ}$에서 $10^{\circ}$간격으로 각각 30개의 독립적인 샘플을 측정하여 통계적으로 후방산란계수를 얻었다. 타워에서 발생하는 전파 잡음과 안테나 패턴의 부엽에 의한 지면에서의 수직반사(coherent 성분) 전파를 제거하기 위해 네트워크 분석기의 time gating 기능을 사용하며，55 cm 크기의 trihedral 전파반사기를 보정용 반사기로 사용하고， STCT(single target calibration technique) 방법을 이용하여 시스템을 보정하였다. 측정 결과를 분석하여 주파수， 입사각도， 편파의 변화에 대한 벼의 후방산란 특성과 벼의 생육상태과의 관계를 살펴보았다. L-밴드와 C-밴드 모두 벼의 생육과 밀접한 결과를 나타내었으나，입사각이 작을 때는 C-밴드와의 상관이 높게 나타났고 입사각이 커질수록 L-밴드와의 상관이 높게 나타났다. 편파는 L-밴드 와 C-밴드 모두 hh 편파가，입사각은 50도에서 가장 생육의 변이를 잘 설명하는 것으로 나타났다. 생육 데이터 모두를 이용한 경우보다는 유수형성기 또는 출수기 등 벼 생육의 질적인 변화를 보이는 시기에 따라 나누어 분석하는 것이 변화추이를 더 잘 설명하는 것으로 나타났다.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.81-89
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• 2012

Commonly used horizontal-axis wind turbines (HAWT) have the following structure: two or three blades, a nacelle which contains power converting equipments, generators, and a tower which supports the nacelle. The generated power is transmitted from the nacelle to the ground. Due to this structure, the power transmission lines are twisted when the nacelle is yawing. Thus, slip ring or additional yaw control mechanism is required. We propose a new structure of HAWT which is free of this transmission line problem. Moreover, the size of inverter can be reduced since two generators are connected in parallel in our mechanism so that power is distributed. A controller for yawing is developed so that it works in harmony with the controller for power generation. A MPPT (Maximum Power Point tracking) algorithm is implemented for the proposed system and efficiency of the system is validated by simulation.

• Fire Science and Engineering
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• v.32 no.4
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• pp.75-85
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• 2018

The Grenpell tower fire in England in June of 2016 is a representative example of damage caused by a vertical fire spreading through external insulation. Organic insulation materials, which are widely used in external insulation, have the disadvantage that they have good insulation performance but are vulnerable to fire. Aluminum composite panels are used as exterior wall finishing materials, and plastics used in aluminum are regarded as the cause of vertical fire spread. Due to the steel frame used to secure the aluminum composite panel to the outer wall, a cavity is formed between the outer wall and outer wall finish. When a fire occurs on the outer wall, the flammable outer wall as well as the flame generated from the heat-insulating material spreads vertically through the cavity, resulting in damage to people and property. In Korea, material unit performance tests are carried out by the Ministry of Land, Infrastructure and Transport notice 2015 - 744. However, in the UK, the BS 8414 test is used to measure the vertical fire spreading time on the outer wall in real scale fire tests. In this study, the risk of external wall fire was evaluated in an actual fire by conducting a real scale wall fire test (BS 8414), which was carried out in Europe, using aluminum composite panels of semi-noncombustible materials suitable for current domestic standards. The purpose of this study was to confirm the limitations of material unit evaluation of finishing materials and to confirm the necessity of introducing a system to prevent the spread of outer wall fire through an actual scale fire test.