• Wind and Structures
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• 제32권5호
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• pp.405-421
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• 2021

To gain insight into the wind-induced safety concerns associated with attached tower cranes during the construction of super-tall buildings, a 606 m level frame-core tube super-tall building is selected to investigate the wind-induced vibration response and fragility of an outer-attached tower crane at all stages of construction. The wind velocity time history samples are artificially generated and used to perform dynamic response analyses of the crane to observe the effects of wind velocity and wind direction under its working and non-working resting state. The adverse effects of the relative displacement response at different connection supports are also identified. The wind-resistant fragility curves of the crane are obtained by introducing the concept of incremental dynamic analysis. The results from the investigation indicate that a large relative displacement between the supports can substantially amplify the response of the crane at high levels. Such an effect becomes more serious when the lifting arm is perpendicular to the plane of the connection supports. The flexibility of super-tall buildings should be considered in the design of outer-attached tower cranes, especially for anchorage systems. Fragility analysis can be used to specify the maximum appropriate height of the tower crane for each performance level.

• 한국산림과학회지
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• 제79권4호
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• pp.413-418
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• 1990

해방(解放)이후 약 40여년간 우리나라 산림정책의 기본목표를 치산녹화사업에 두고 지속적으로 조림사업을 확대 시행하여 온 결과 조림성공임지 및 기존 천연성숙림에서 목재를 수확하기에 이르렀으므로 최근에 와서는 산림정책의 기본목표를 식수임업위주에서 수확임업위주로 전환하고 있다. 종래에는 벌목, 조재, 집재 등의 목재수확작업, 특히 산원에서의 집재작업을 주로 인력작업에 의존하고 있으나 최근에 와서는 산촌지역에서의 임업노동력의 부족 및 노무비의 급격한 상승 등으로 인하여 기계화작업의 도입이 절실하게 요구되고 있다. 산림청 임업기계훈련원에서 도입하여 시험사용작업을 하고 있는 이동식 타워 소형 케이블크레인(K-300)을 이용하여 집재작업을 시행할 때 인력작업과 비교하여 경제성을 분석한 결과 조사당시에는 일반적을 실시다고 있는 인력을 이용한 집재작업에 비해 경쟁력(최초 투자비가 과대하므로)이 뒤떨어지나 점차적인 인건비 상승경향으로 볼 때에 기계사용비가 상대적으로 낮아져서 케이블크레인을 이용한 집재작업의 국내 적용 가능성은 점차 높아지리라 생각된다. 집재작업의 기계화 계획 및 실행에 관한 시험적 연구가 시급히 요망된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.563-565
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• 1999

In this paper, we control attitude of an unstructured object with gyro actuator. It is well known that the attitude control of an object hanging with wire is not easy using usual actuators. Even though an actuator such as a fan can be used for control of the object, it is difficult to meet a desired control objectives. We, because of these reasons, make a gyro actuator with two motors. The first motor is responsible for spinning the wheel at high speed and the second motor is used to turn the inner gimbal. Applying the torque to the second motor, which results in the turn of the outer gimbal, torque about the vertical axis will be obtained while the wheel of the gyro is spinning constantly. This torque is used to control the attitude of the object attached. Gyro actuator utilize control unstructured object such as I-beam carrying by tower crane, and isolate construction workers from the dangerous environments. We derive a relationship of wheel and its motor, find a proper capacity of wheel motor in order to rotate a wheel. Through experiments of attitude control, we show to obtain desired control objectives.