• Title/Summary/Keyword: Weight and Center of Gravity

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Evaluation of dynamic behaviors of gravity-based structures under seismic load considering fluid-structure-ground interactions

  • Hyo-Jin Kim;Sunghun Jung;Seongpil Cho
    • Structural Engineering and Mechanics
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    • v.88 no.3
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    • pp.251-262
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    • 2023
  • This paper presents a method for assessing the dynamic responses of gravity-based structures (GBS) under various seismic loads, with a focus on fluid-structure-ground interactions. Models of GBSs and their surrounding environments were developed, incorporating interaction effects among the structure, seawater, and seabed. Dynamic responses of the GBS subjected to three seismic loads-Chi-Chi, Northridge01, and Northridge02-were calculated, with consideration of both horizontal and vertical accelerations, as well as displacements. Parametric studies indicated that the primary factors affecting the dynamic responses of GBS were seismic loads characterized by significant input forces and accelerations. The frictional force on the ground had minimal impact on the horizontal and vertical displacements of the GBS. Weight emerged as a critical factor in anchoring the GBS to the ground and minimizing vertical accelerations and displacements.

Modularization of plant structures (플랜트 구조물의 모듈화 공법)

  • Seo, Han Seol;Chang, Sang Soo
    • Plant Journal
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    • v.13 no.3
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    • pp.30-35
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    • 2017
  • Module can be categorized as PAS(Pre-Assembled Steel structure), PAR(Pre-Assembled pipe Rack), PAU(Pre-Assembled Unit), VAU(Vendor Assembled Unit) and VPU(Vendor Package Unit). At the stage of design and fabrication of module, the condition of land and ocean transportation is considered and these conditions are reflected on the module division design. The control of the module's center of gravity is important to transport and install modules safely and the steel structure should have the strength enough to resist the sea acceleration force during the ocean transportation. The transportation condition and the installation method influence the size and weight of module. The size and weight of module are considered for the design of module division.

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Aerodynamic Design of the Solar-Powered High Altitude Long Endurance (HALE) Unmanned Aerial Vehicle (UAV)

  • Hwang, Seung-Jae;Kim, Sang-Gon;Kim, Cheol-Won;Lee, Yung-Gyo
    • International Journal of Aeronautical and Space Sciences
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    • v.17 no.1
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    • pp.132-138
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    • 2016
  • Korea Aerospace Research Institute (KARI) is developing an electric-driven HALE UAV in order to secure system and operational technologies since 2010. Based on the flight tests and design experiences of the previously developed electric-driven UAVs, KARI has designed EAV-3, a solar-powered HALE UAV. EAV-3 weighs 53kg, the structure weight is 22kg, and features a flexible wing of 19.5m in span with the aspect ratio of 17.4. Designing the main wing and empennage of the EAV-3 the amount of the bending due to the flexible wing, 404mm at 1-G flight condition based on T-800 composite material, and side wind effects due to low cruise speed, $V_{cr}=6m/sec$, are carefully considered. Also, unlike the general aircraft there is no center of gravity shift during the flight because of the EAV-3 is the solar-electric driven UAV. Thus, static margin cuts down to 28.4% and center of gravity moves back to 31% of the Mean Aerodynamic Chord (MAC) comparing with the previously designed the EAV-2 and EAV-2H/2H+ to upgrade the flight performance of the EAV-3.

The investigation of shoulder height, center of gravity and plantar pressure by backpack weight and location (가방 휴대방법과 무게에 따른 어깨높이, 중력 중심선과 발바닥 압력 변화 연구)

  • Son, Seon-Ju;Han, Min-Kyu;Lee, Hye-Jin;Seo, Young-Mi;Park, Ha-Na;Lee, Sang-Young;Park, Cheol-Woo;Kwon, Gu-Hyun;Kim, Hyoung-Su
    • Journal of Korean Physical Therapy Science
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    • v.18 no.3
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    • pp.71-78
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    • 2011
  • Purpose : The purpose of this study found change that caused by various form and weight of bag. So we investigated how these things change the shoulder altitude and space between external acoustic pore and lateral malleolus and also plantar pressure. Method : We measured two different way for this study. One was backpack with 5, 10kg and another one was shoulder pack with same weight. Each trial was 10 seconds in duration with static stance posture. With these experiments, we checked space between plantar pressure, shoulder altitude, external acoustic pore and lateral malleolus with EMED system and GPS. We analyzed these results with PASW(SPSS) statistics 18.0. Result : In conclusion, there were no significantly differences in shoulder altitude by weight of pack, but average of plantar pressure and space between external acoustic pore and lateral malleolus was increased.

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Foundation Types of Fixed Offshore Wind Turbine

  • Yun Jae Kim;Jin-wook Choe;Jinseok Lim;Sung Woong Choi
    • Journal of Ocean Engineering and Technology
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    • v.38 no.2
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    • pp.74-85
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    • 2024
  • Offshore wind turbines are supported by various foundations, each with its considerations in design and construction. Gravity, monopile, and suction bucket foundations encounter geotechnical issues, while jacket and tripod foundations face fatigue problems. Considering this, a gravity foundation based on a steel skirt was developed, and a monopile foundation was analyzed for Pile-Soil Interaction using the p-y curve and 3D finite element method (3D FEM). In addition, for suction bucket foundations, the effects of lateral and vertical loads were analyzed using 3D FEM and centrifuge tests. Fatigue analysis for jacket and tripod foundations was conducted using a hotspot stress approach. Some hybrid foundations and shape optimization techniques that change the shape to complement the problems of each foundation described above were assessed. Hybrid foundations could increase lateral resistance compared to existing foundations because of the combined appendages, and optimization techniques could reduce costs by maximizing the efficiency of the structure or by reducing costs and weight. This paper presents the characteristics and research directions of the foundation through various studies on the foundation. In addition, the optimal design method is presented by explaining the problems of the foundation and suggesting ways to supplement them.

An Evaluation of the Tolerance of the Static Characteristics for Light Weight Torpedoes (경어뢰의 정특성 허용오차 산정)

  • 나영인
    • Journal of the Korea Institute of Military Science and Technology
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    • v.5 no.2
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    • pp.149-158
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    • 2002
  • Static Characteristics of the system, such as weight, center of gravity etc., are inspected and regulated through the whole design process of a light weight torpedo system, and the nominal condition of the characteristics is prescribed for standardization of manufacturing and fabrication. It is possible that a real system or assembled system has different static characteristics from that of the nominal condition. It is required to evaluate the tolerance of the static characteristics within which the performance of the system should not be contaminated by the static characteristics. In this paper, an evaluation method of the tolerance is described for light weight torpedo systems. The method is to check on the performance and related critical parameters of light weight torpedoes. The checking items are composed of general conditions of underwater mobile systems such as stability and dynamic sensitivity and specified performance requirements for light weight torpedoes.

A Study on Container Securing System for Optimum Arrangement (최적 적재를 위한 컨테이너 시큐어링 시스템 개발에 관한 연구)

  • Shin, Sang-Hoon
    • Journal of Navigation and Port Research
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    • v.27 no.4
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    • pp.397-402
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    • 2003
  • Generally, container arrangement has been carried out based on the Classification guidelines. However, guidelines provide only container securing forces for the given container arrangement and Classification requirements of the forces. In order to design container arrangement additional information is needed such as container securing forces and arrangement that accounts for lashing bridges, vertical lashing, vertical center of gravity (VCG), and maximum stack weight. Trial and error method using the existing guidelines requires excessive amount of calculation time and cannot provide accurate results of the calculations. In order to fulfill this need, a new container securing system has been established based on the equilibrium conditions that include lashing bridges and vertical lashing. An optimization algorithm has been developed for the new system since current optimization methods such as genetic algorithms and evolution strategies are unsuitable for the container securing problems, which involve equality constraint. Design variables are container weights of tier and objective function is either total container weight or VCG of a stack. The newly developed system provides optimum arrangement of containers for both maximum stack weight and maximum VCG. It also greatly reduces time for designing container arrangement.

The Effects of Lateral Wedged Insole to the Shoe of the Affected Side on Weight Bearing, Balance and Gait with Stroke (마비측에 적용한 외측 쐐기 깔창이 뇌졸증 환자의 체중부하율과 균형, 보행에 미치는 영향)

  • Kim, Hye-Lim;Shin, Won-Seob
    • PNF and Movement
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    • v.11 no.2
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    • pp.21-29
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    • 2013
  • Purpose : The study was to evaluate the weight distribution, balance and gait function of stroke patients wearing lateral wedged insole to the shoe of the affected side. Methods : 27 patients with stroke (15 men, 12 women) participated in this study. Participants performed weight distribution, dynamic balance and gait ability with or without wedged insole on affected side in a random order. The balancia was used to evaluate the weight distribution. Deviation from the center line was analyzed by Dartfish during sit to stand to evaluate dynamic balance. The functional walk ability evaluated by 10 m walking velocity. Results : The asymmetry index of weight bearing improved significantly with wedged insole of affected side(p<.05). During sit to stand, center of gravity significantly moved from non-affected side to more mid line of body(p<.05). Improvement were shown in walking speed after wearing the wedged insole(p<.05). Conclusion : Wedged insole applied on affected side have a beneficial effect on weight distribution, dynamic balance and walking speed with stroke.

Studies on the Physiological Characteristics of (Cervus e. canadensis) Velvet Antler in Elk

  • Jeon, Byong-Tae;Thomas, David G.;Cheong, Sun-Hee;Kim, Myeong-Hwa;Kim, Sung-Jin;Sung, Si-Heung;Park, Pyo-Jam;Park, Jae-Hyun;Moon, Sang-Ho
    • Journal of Animal Science and Technology
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    • v.52 no.3
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    • pp.237-244
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    • 2010
  • In order to investigate the physiological properties of velvet antler of elk (Cervus e. canadensis) raised in Korea, antlers (n=378) were collected from deer in 8 provinces including Gyeonggi-do (n=53), Gangwon-do (n=49), Chungcheongbuk-do (n=62), Chungcheongnam-do (n=68), Jeollabuk-do (n=52), Jeollanam-do (n=15), Gyeongsangbuk-do (n=30) and Gyeongsangnam-do (n=49). The exterior characteristics (weight, length, girth and crown) of all antlers were measured, and 18 antler samples were randomly selected for measurement of interior characteristics such as specific gravity, capacity and diameter of cross section. The mean antler weight, length of the main beam and mean length of upper section were $4.87{\pm}1.79\;kg$, $83.7{\pm}13.2\;cm$ and $40.6{\pm}11.4\;cm$, respectively. Mean girth of the top, middle and base of the main beam were $27.1{\pm}5.9\;cm$, $22.1{\pm}3.6\;cm$ and $22.9{\pm}3.6\;cm$ respectively, indicating a slight narrowing in the middle of the antler. In each of the tines, the girth at the base was markedly thicker compared to the top. The depth of the crown at the top of the antler, and the average number of crowns and tines were $14.1{\pm}7.0\;cm$, $2.1{\pm}0.6$ and $3.0{\pm}0.5$, respectively. Although there was no significant difference in mean specific gravity between top and base, mean specific gravity of main beam tended to increase from top to base of the antler with decreasing capacity. Additionally, the inner diameter of the base of the antler was significantly reduced compared to that of the top, indicating a greater integumental thickening due to mineralization. Information on the morphological and physiological properties of elk antlers is scarce. Therefore, these results may be useful in providing basic information for the physiological properties of antler, and encourage further studies on antler morphology in other deer species showing species specific differences.

A Study on Result Differences of Flight's Weight and Balance by Load Master (항공기 탑재 관리사들의 개인 특성에 따른 Weight and Balance C.G. 결과)

  • Lee, Gyu-Jin;Lee, Yun-Cheol
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.23 no.3
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    • pp.81-87
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    • 2015
  • Load master is authorized to be controlled all of loading stuffs for safety of flight such as passenger, baggage, cargo and e.t.c. There are many things are missed even though the weight and balance is the most important process. This study analyzes how the differences of C.G. by among ten load masters of each careers. This study is tested how load-master takes load-control by the respective result based on differences of each practical experiences, gender and a number of certification. In result, all of load masters set C.G. on the stability region. But the practical experience of load master is relative to set better C.G. for economical effectiveness of weight and balance control work.