• Title/Summary/Keyword: Roll period

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Influence of Tether Length in the Response Behavior of Square Tension Leg Platform in Regular Waves

  • El-gamal, Amr R.;Essa, Ashraf
    • International Journal of Ocean System Engineering
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    • v.4 no.1
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    • pp.19-28
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    • 2014
  • The tension leg platform (TLP) is a vertically moored structure with excess buoyancy. The TLP is regarded as moored structure in horizontal plan, while inherit stiffness of fixed platform in vertical plane. In this paper, a numerical study using modified Morison equation was carried out in the time domain to investigate the influence of nonlinearities due to hydrodynamic forces and the coupling effect between surge, sway, heave, roll, pitch and yaw degrees of freedom on the dynamic behavior of TLP's. The stiffness of the TLP was derived from a combination of hydrostatic restoring forces and restoring forces due to cables and the nonlinear equations of motion were solved utilizing Newmark's beta integration scheme. The effect of tethers length and wave characteristics such as wave period and wave height on the response of TLP's was evaluated. Only uni-directional waves in the surge direction was considered in the analysis. It was found that for short wave periods (i.e. 10 sec.), the surge response consisted of small amplitude oscillations about a displaced position that is significantly dependent on tether length, wave height; whereas for longer wave periods, the surge response showed high amplitude oscillations about that is significantly dependent on tether length.

A study on the vest shape and tailoring of the Korean Empire in the 1900s (대한제국기 남자 조끼 형태 및 제작법에 관한 연구)

  • Choi, Eunjoo
    • The Research Journal of the Costume Culture
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    • v.25 no.3
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    • pp.340-358
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    • 2017
  • The purpose of this study is to fundamentally examine the vests of the robes "Daeraebok" and "Soraebok" of the Korean Empire from the 1876 Port Opening to the 1910 annexation of Korea to Japan. Among the collections of different robes of the Korean Empire which belong to various universities and institutions, only the vests were surveyed. The shape of the vests in the Korean Empire were single-breasted and double-breasted. Most V-necklines and vests with a shawl collar look like a tailored collar, where the collar outline was shaped like a notched and picked collar, which is a mix of the step collar and roll collar of the 19th century. The rear center line was not flat, but inclined to a triangle. All vests of the robe Daeraebok were equipped with gold buttons, and those of the robe Soraebok had black satin buttons. The tailoring characteristic is that the front has a different material (dark black wool) from the back (black silk). This characteristic is expected to be an important basic piece of information in the restoration and reproduction of the vest, which was worn during the imperial period, especially to reveal its shape, characteristics and composition. This characteristic can also be used as data of cultural contents based on Korean modern history.

Dynamic response analysis of floating offshore wind turbine with different types of heave plates and mooring systems by using a fully nonlinear model

  • Waris, Muhammad Bilal;Ishihara, Takeshi
    • Coupled systems mechanics
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    • v.1 no.3
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    • pp.247-268
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    • 2012
  • A finite element model is developed for dynamic response prediction of floating offshore wind turbine systems considering coupling of wind turbine, floater and mooring system. The model employs Morison's equation with Srinivasan's model for hydrodynamic force and a non-hydrostatic model for restoring force. It is observed that for estimation of restoring force of a small floater, simple hydrostatic model underestimates the heave response after the resonance peak, while non-hydrostatic model shows good agreement with experiment. The developed model is used to discuss influence of heave plates and modeling of mooring system on floater response. Heave plates are found to influence heave response by shifting the resonance peak to longer period, while response after resonance is unaffected. The applicability of simplified linear modeling of mooring system is investigated using nonlinear model for Catenary and Tension Legged mooring. The linear model is found to provide good agreement with nonlinear model for Tension Leg mooring while it overestimates the surge response for Catenary mooring system. Floater response characteristics under different wave directions for the two types of mooring system are similar in all six modes but heave, pitch and roll amplitudes is negligible in tension leg due to high restraint. The reduced amplitude shall lead to reduction in wind turbine loads.

A View of Contemporary Issues of Housing Architecture in the European Housing Exhibition -Focused on the Floorplan Concepts of Werkbund Housing in the 20's-30's- (유럽의 주택전시회를 통해 본 주거건축 계획의 시대적 쟁점 - 1920-30년대 공작연맹주최 주택전시회에서 제시된 새로운 평면개념을 중심으로 -)

  • Jung, Nam-Il
    • Korean Institute of Interior Design Journal
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    • v.16 no.6
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    • pp.106-115
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    • 2007
  • The Werkbund housing exhibitions in Europe in the 20's and 30's presented various planning concepts and played a important roll for modernization of housing Architecture. This study, therefore, aims to understand the contemporary issues of housing in this period, which showed the meaningful momentum for housing plans today. In order to grasp the general characteristics of exhibition housing the representative cases -Weissenhofsiedlung, Dammerstock, Breslausiedlung, Werkbund Siedlung in $Z\"{u}rich-Neub\"{u}hl$, Werkbundsiedlung Wien und BaBa- were throught documents analyzed. The architects offered an innovative building typology such as row housing and new prototype of housing units accordingly social needs. Especially, In this study housing unitplans were in 6 groups such as flexible type, cabin type, free open plan, Raumplan, functional 2-story type and corridor type categorized. And they were analyzed how deeply technological development, architectural design perceptions as well as functional aspects had on the planning of floorplans reflected. As a result, in the housing exhibitions various architectural ideas presented the "Zeitgeist" not only such as improvement of physical environment of housing, but also such as rationalization, standardization, functionalization, normalization of housing architecture. Also their unitplans corresponded to newly developed building typology and modern household type. As well as they represented notable spatial concepts. Moreover it contributed to create a new paradigm of housing for the new epoch.

A Study on The Novel Structured 3-DOF Spherical Motor (새로운 3-자유도 구형 모터에 관한 연구)

  • Lee, Dong-Cheol;Kim, Dae-Kyong;Kwon, Byung-Il
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.8
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    • pp.1362-1370
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    • 2008
  • This paper describes the design and characteristic analysis of a novel 3-DOF(Degree of Freedom) spherical motor. For multi DOF actuating, several numbers of motors have been used. By the using of normal motors they connected each other in single joint, is necessary to a several type of complex power transmission devices. The 3-DOF spherical motor can drive roll, pitch, and yaw motion in only one unit and it is not necessary to use additional gears and links parts. Therefore the using of 3-DOF spherical motor can eliminate; combined effects of inertia, backlash, non-linear friction, and elastic deformation of gears. In this paper, we propose the novel structured 3-DOF spherical motor and derive its principles of operation. Firstly, we designed concept model of novel structured 3-DOF spherical motor. Next, we derive the control method by calculating the currents. Also, to have intuitive driving control, we express the rotor position in equivalent angle-axis system and determine the exciting period of currents from the calculation result of the currents. To verify the control method, we calculated the currents by the position of rotor. and then we analyzed the characteristics by 3D Finite Element Method when the calculated currents are excited.

Surgical outcomes of 14 consecutive bilateral cleft lip patients treated with a modified version of the Millard and Manchester methods

  • Al-Zajrawee, Mustafa Zahi;Aljodah, Mohammed Abd-Alhussein;Hassan, Qays Ahmed
    • Archives of Plastic Surgery
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    • v.46 no.2
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    • pp.114-121
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    • 2019
  • Background Bilateral cleft lip deformity is much more difficult to correct than unilateral cleft lip deformity. The complexity of the deformity and the sensitive relationships between the arrangement of the muscles and the characteristics of the external lip necessitate a comprehensive preoperative plan for management. The purpose of this study was to evaluate the repair of bilateral cleft lip using the Byrd modification of the traditional Millard and Manchester methods. A key component of this repair technique is focused on reconstruction of the central tubercle. Methods Fourteen patients with mean age of 5.7 months presented with bilateral cleft lip deformity and were operated on using a modification of the Millard and Manchester techniques. Patients with a very wide cleft lip and protruded or rotated premaxilla were excluded from this study. We analyzed 30 normal children for a comparison with our patients in terms of anthropometric measurements. Results By the end of the follow-up period (between 9 and 19 months), all our patients had obtained a full central segment with adequate white roll in the central segment and a deep gingivolabial sulcus, and we obtained nearly normal anthropometric measurements in comparison with age-matched normal children. Conclusions We recommend this modified technique for the treatment of bilateral cleft lip deformity.

Floating Gas Power Plants

  • Kim, Hyun-Soo
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.6_1
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    • pp.907-915
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    • 2020
  • Specification selection, Layout, specifications and combinations of Power Drives, and Ship motions were studied for FGPP(Floating Gas-fired Power Plants), which are still needed in areas such as the Caribbean, Latin America, and Southeast Asia where electricity is not sufficiently supplied. From this study, the optimal equipment layout in ships was derived. In addition, the difference between engine and turbine was verified through LCOE(Levelized Cost of Energy) comparison according to the type and combination of Power Drives. Analysis of Hs(Significant Height of wave) and Tp(spectrum Peak Period of wave) for places where this FGPP will be tested or applied enables design according to wave characteristics in Brazil and Indonesia. Normalized Sloshing Pressures of FGPP and LNG Carrier are verified using a sloshing analysis program, which is CFD(Computational Fluid Dynamics) software developed by ABS(American Bureau of Shipping). Power Transmission System is studied with Double bus with one Circuit Breaker Topology. A nd the CFD analysis allowed us to calculate linear roll damping coefficients for more accurate full load conditions and ballast conditions. Through RAO(Response Amplitude Operator) analysis, we secured data that could minimize the movement of ships according to the direction of waves and ship placement by identifying the characteristics of large movements in the beam sea conditions. The FGPP has been granted an AIP(Approval in Principle) from a classification society, the ABS.

Parametric optimization of FPSO hull dimensions for Brazil field using sophisticated stability and hydrodynamic calculations

  • Lee, Jonghun;Kim, Byung Chul;Ruy, Won-Sun;Han, Ik Seung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.13 no.1
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    • pp.478-492
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    • 2021
  • In this study, hull dimensions of an FPSO were optimized to maximize its operability at Brazil field. In contrast with the previous works which have used simplified models to evaluate some indicators related to stability and hydrodynamic performances of FPSOs for its own optimal design, we developed a generic hull and compartment modeler and sophisticated stability and hydrodynamic calculation modules. With the aid of the developed tools, the hull optimization was performed with initial dimensions of an FPSO originally designed for west Africa field. The optimization results indicated the relative importance of hydrodynamic performances compared with stability performances for the FPSO hull dimensioning by showing that there were 3 active constraints related to them, which were the natural periods of heave and roll and the maximum pitch angle under 1-year return period waves at full load condition. To the author's knowledge, this study is the first attempt to combine altogether the hull and compartment modeling and full set of stability and hydrodynamic calculations precisely to optimize an FPSO's hull dimensions within 30 min. Also, it is worthwhile to mention that the developed methods are generic enough to be applied to all types of ship-shaped offshore platforms.

A Strategic Quality Initiative and Its Opportunities to Improve Healthcare Environment (진료환경개선을 위한 우선적 전략과제 설정 및 그 적용)

  • Tark, Kwan-Chul;Park, Hyun-Ju;Park, Chang-Il;Kang, Jin-Kyung
    • Quality Improvement in Health Care
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    • v.5 no.2
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    • pp.324-334
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    • 1998
  • Background : Strategic planning is an organizationwide or systemwide, ongoing look into the future usually of 2~3 years, based on objective analysis of the current environment and trends, but it can incorporate both short-term and long-term goals. The strategic planning process includes external analysis, internal analysis, issue analysis, development of mission, vision and values, and lastly development of organizational goals and objectives. As a part of the strategic quality planning process, certain service lines, important organizationwide functions, or key processes supporting these functions can be prioritized to expedite and roll out certain strategic goals. This is called strategic quality initiatives. Methods : We organized a quality improvement team, a subgroup of 21st century vision planning corps of our medical center, and pursued QI activities for improvement of healthcare environment, particularly in the admission setting. We developed a strategic quality initiative based on the results of patient satisfaction surveys, and carried out functions of self-directed work team. Results : The strategic goal was to be the benchmark for peer group hospitals in Korea for providing cost-effective best-practice. The QI team included 3 medical doctors, 1 nurse, 1 social worker, and 1 QI consultant as well as many operational members to support services and quality initiatives met every Tuesday for 18 weeks. Outcome objectives were to improve patient satisfaction score. The issues included in the objectives were comfort, temperature, noise, cleanliness of the admission wards, quality and education of patient meals, matters regarding the admission process, and an appurtenant facility such as restaurant or convenience store. Every issue was discussed and recommendations, conclusions and opportunities were implemented. Conclusions : By developing a strategic quality initiative as a part of the strategic quality planning process, and pursuing a self-directed work team, certain sen/ice lines, important organizationwide functions, or key processes supporting these functions can be improved effectively within a short period. Strategic quality initiatives serve to support, or roll out, certain strategic goals that are relevant to performance improvement and development of specific measurable outcome objectives, and associated performance measure for each initiative. Each strategic quality initiative should include a statement of intent outcome objectives, and performance measures. We will come back with follow up of the strategic quality initiative, for improvement of healthcare environment, and results of patient satisfaction re-survey.

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Prediction on Mooring Tension & Motion Response Characteristics of a Floating Dock in Regular Waves (규칙파 중 플로팅 도크의 운동응답특성 및 계류장력 추정)

  • Oh, Young-Cheol;Gim, Ok-Sok;Ko, Jae-Yong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.19 no.2
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    • pp.200-206
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    • 2013
  • The paper was investigated on the mooring forces(or tension) and motion response characteristics for a 8-point mooring floating dock in regular waves using a commercial code(AQWA). To achieve the aim of the research, a numerical simulation was adapted on an inner port environment condition, which the water depth is 10 meters, significant wave amplitude(1.05 m). wave period(3.85 sec), wind speed(20.21 m/s), wind and current direction ($90^{\circ}$), incident waves(${\chi}=180^{\circ}$, $135^{\circ}$ and $90^{\circ}$). The dimension of the numerical model is length(140 m), breadth(32 m), depth(14.6 m). The maximum length of a mooring line is 120m. We can expected that roll and pitch motions appeared in beam seas better than head sea. the mooring forces also indicated higher in bean seas than in head seas including wind forces.