• Title/Summary/Keyword: forced oscillation

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Precarity and Hope in Digital Labor: In-depth Interviews on the Off-campus Internship Experiences of College Students (디지털 노동의 불안과 희망: 대학생의 '대외활동'에 대한 심층 인터뷰)

  • Lee, Hee-Eun
    • Korean journal of communication and information
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    • v.66
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    • pp.211-241
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    • 2014
  • In the era of neoliberalism with high rate of youth unemployment, young college students are forced to believe that the only way to enter the job market is by accepting and participating temporary off-campus apprenticeship, which often disguised as an internship for the creative culture and knowledge. This article discusses that the mode of off-campus apprenticeship, which is supposed to voluntary and participatory, bears in fact a strong resemblance with digital labor. Based on a series of in-depth interviews with college students, this study argues that the apprentice-typed labor denotes a process by which immaterial labor or free labor coincides with self-directed job training. Throughout the digital labor processes young college students are in a constant oscillation between precarity and hope, negotiating their autonomy and social conditions in the neoliberal work environment. The digital labor accumulates students' knowledge and information as a form of commodity, which in turn supports communicative capitalism.

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Design and testing of the KC-100 Spin Recovery Parachute System (SRPS)

  • Lee, Dong-Hun;Nho, Byung-Chan;Kang, Myung-Kag;Kang, Kyung-Woo;Lee, Ju-Ha;Kim, Su-Min;Kwon, Young-Suk
    • International Journal of Aeronautical and Space Sciences
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    • v.13 no.1
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    • pp.117-125
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    • 2012
  • This paper presented the design of SRPS, ground function test, and the deployment test on a high speed taxi of KC-100 airplane. KAI has developed a spin recovery system in collaboration with Airborne Systems for KC-100 general aviation airplane. Spin mode analysis, rotary balance and forced oscillation tests were performed to obtain the rotational, dynamic derivatives in the preliminary design phase. Prior to the detailed design process of SRPS, approximations for initial estimation of design parameters- fineness ratio, parachute porosity, parachute canopy filling time, and deployment method- were considered. They were done based on the analytical disciplines such as aerodynamics, structures, and stability & control. SRPS consists of parachute, tractor rocket assembly for deployment, attach release mechanism (ARM) and cockpit control system. Before the installation of SRPS in KC-100 airplane, all the control functions of this system were demonstrated by using SBTB(System Breakout Test Box) in the laboratory. SBTB was used to confirm if it can detect faults, and simulate the firing of pyrotechnic devices that control the deployment and jettison of SRPS. Once confirmed normal operation of SRPS, deployment and jettison of parachute on the high speed taxiing were performed.

Reference values for respiratory system impedance using impulse oscillometry in school-aged children in Korea (학동기 소아에서 impulse oscillometry system로 측정한 폐기능 정상치)

  • Wee, Young Sun;Kim, Hyoung Yun;Jung, Da Wun;Park, Hye Won;Shin, Yoon Ho;Han, Man Yong
    • Clinical and Experimental Pediatrics
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    • v.50 no.9
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    • pp.862-867
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    • 2007
  • Purpose : The impulse oscillometry (IOS) is applicable to young children because it requires minimal cooperation and a non-invasive method to measure the mechanics of respiratory system. This study aimed to develop the reference values in school-aged children in Korea, using IOS which is a modification of forced oscillation technique (FOT). Methods : Measurements were performed in 92 previously untrained healthy children, aged 7 to 12 years old, using IOS. We analyzed the relationships between the data about their age, height, weight, body surface area (BSA), body mass index (BMI) and the result of IOS using the linear regression test. Results : The success rate of IOS was 92.4%. Stepwise multiple regression of resistance of respiratory system (Rrs) and reactance of respiratory system (Xrs) in natural form for age, height, weight, BSA, BMI showed that height was the most significant predictor and altogether of 5 variables explained the Rrs and Xrs most. Our regression equations at multiple frequencys were comparable to published reference values, especially about the Rrs obtained at 5 Hz. Conclusion : IOS is a feasible method to measure the respiratory resistance in untrained children. We got the reference values using IOS and it seems to be useful to diagnose a variety of respiratory diseases.

Regional Realtime Ocean Tide and Storm-surge Simulation for the South China Sea (남중국해 지역 실시간 해양 조석 및 폭풍해일 시뮬레이션)

  • Kim, Kyeong Ok;Choi, Byung Ho;Lee, Han Soo;Yuk, Jin-Hee
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.2
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    • pp.69-83
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    • 2018
  • The South China Sea (SCS) is a typical marginal sea characterized with the deep basin, shelf break, shallow shelf, many straits, and complex bathymetry. This study investigated the tidal characteristics and propagation, and reproduced typhoon-induced storm surge in this region using the regional real-time tide-surge model, which was based on the unstructured grid, resolving in detail the region of interest and forced by tide at the open boundary and by wind and air pressure at the surface. Typhoon Haiyan, which occurred in 2013 and caused great damage in the Philippines, was chosen as a case study to simulate typhoon's impact. Amplitudes and phases of four major constituents were reproduced reasonably in general, and the tidal distributions of four constituents were similar to the previous studies. The modelled tide seemed to be within the acceptable levels, considering it was difficult to reproduce the tide in this region based on the previous studies. The free oscillation experiment results described well the feature of tide that the diurnal tide is prevailing in the SCS. The tidal residual current and total energy dissipation were discussed to understand the tidal and sedimentary environments. The storm-surge caused by typhoon Haiyan was reasonably simulated using this modeling system. This study established the regional real-time barotropic tide/water level prediction system for the South China Sea including the seas around the Philippines through the validation of the model and the understanding of tidal characteristics.

Total Dynamic Analysis of Deep-Seabed Integrated Mining System (심해저 광물자원 채광시스템의 통합거동 해석)

  • Kim, Hyung-Woo;Hong, Sup;Lee, Chang-Ho;Choi, Jong-Su;Yeu, Tae-Kyeong
    • Journal of Navigation and Port Research
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    • v.34 no.3
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    • pp.195-203
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    • 2010
  • This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely cohesive soft soil is applied to the self-propelled miner. Hinged and ball constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, self-propelled miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-${\beta}$ method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

Study on the Measurement System of Behavior of a Slender Structure using an Underwater Camera which is applied in DOEB (심해공학수조에 적용되는 수중카메라를 이용한 세장체의 연속 거동 측정방법에 관한 연구)

  • Jung, Dong-Ho;Kwon, Yong-Ju;Park, Byeong-Won;Jung, Jae-Hwan;Choi, Jong-Su;Cho, Seok-Kyu;Sung, Hong-Gun
    • Journal of Navigation and Port Research
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    • v.42 no.1
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    • pp.1-8
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    • 2018
  • This study covers the selection of systems measuring the behaviour of the slender structure in the underwater environment and its performance assessment. From a comparison of an instrumentation system that can measure the continuous behaviour along the entire length of the slender structure, the underwater camera system is finally selected as the most appropriate semi-permanent measurement system for Deep-sea Ocean Engineering Basin of KRISO. An experiment on the rigid pipes for a basic performance evaluation of the underwater camera is conducted in this study. The motion of a top excited rigid pipe is measured with the utilization of the underwater camera system. The performance of the underwater camera is evaluated by comparing the movement of a pipe measured by the underwater camera with the measured input signals. Through the top excitation experiment for the slender structure, the real-time three-dimensional measurement of the underwater camera system is qualitatively evaluated in this case. The developed underwater camera system can apply to the system to measure dynamic behaviour of a slender structure and mooring line in Deep Ocean Engineering Basin.