• Title/Summary/Keyword: Vertical Restraints

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Study on Hydrodynamic Forces Acting on Tanker Hull with Consideration of Various Vertical Centers of Gravity in Drift Test (다양한 수직방향 무게중심을 고려한 사항 중 탱커 선체에 작용하는 유체력에 관한 연구)

  • Park, Taechul;Lee, Sungwook;Paik, Kwang-Jun;Moon, Sung-Ho
    • Journal of Ocean Engineering and Technology
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    • v.32 no.6
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    • pp.433-439
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    • 2018
  • An investigation was conducted to determine whether the changes in the maneuvering forces and moments acting on a hull could be affected by changing the vertical center of gravity (VCG) of a tanker. The changes in the hydrodynamic forces and moment acting on a hull according to the restraint conditions of motion were examined using CFD for cases where the VCG was located at the design draught (100% of draught), under the design draught (75% of draught), and at half of the design draught (50% of draught). The following motion restraint conditions were selected: (1) fixed restraints for everything; (2) heave, pitch, and roll free restraint; and (3) heave and pitch free restraints. It was found that restraint condition (2) had the best agreement with the model experiment results. In addition, it was found that the hydrodynamic forces and moment acting on the hull with restraint condition (2) could be greatly affected in the model tests and CFD calculations by the various configurations for the vertical center of gravity of the hull. Finally, it was concluded that the location of the vertical center of gravity of the hull could be an important factor when more accurate hydrodynamic maneuvering forces and moment are estimated.

Buckling Experiment of Eccentric Seismic Bracing Devices for Branch Lines (내진설계용 편심방식 가지배관 고정장치의 좌굴 실험)

  • Changsoo, Oh;Jihoon, Kim;Hasung Kong
    • Journal of the Korea Safety Management & Science
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    • v.26 no.1
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    • pp.9-14
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    • 2024
  • Restraints of Branch Lines are used as earthquake-resistant support devices for fire-fighting pipes along with sway brace devices. The central types are aligned and fixed in a straight line with center of the pipe, but the eccentric types are fixed to on side of the pipe, so a bending moment occurs. In this study, three specimens each of central type and eccentric type were installed at an angle of 45° from the vertical and a monotonic compression load of 1340N was applied. All central type samples satisfied 17.8mm of the allowable displacement, but all eccentric type samples failed to meet the target load and buckled. Therefore, when considering the performance of eccentric type restraints, both compressive load and bending moment must be considered. Even through material mechanics calculations, the yield stress of eccentric type - 3/8 inch all threaded steel bolt - exceeds 320Mpa of the allowable stress. A experiment standards need to be established for eccentric type restraints.

한미 FTA와 경쟁정책

  • Jeong, Yeong-Jin
    • Journal of Korea Fair Competition Federation
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    • no.127
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    • pp.6-19
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    • 2006
  • 사적 경쟁제한행위에 대한 효과적인 규제 없는 통상협정은 그 소기의 목적을 달성하기 힘들다. 통상협정은 근본적으로는 협정 당사국에 대한 시장접근(market access)을 높이기 위한 것이다. 그런데 협정을 통하여 공적 장벽을 없앤다고 하더라도 해당국가에 예컨대 고질적인 수직적 거래제한(vertical restraints)이 만연해 있어서 외국기업이 자국의 소비자에게 접근할 수 없다면 통상협정을 통하여 달성하고자 하는 시장접근은 공염불이 될 것이다. 한미 FTA협상에도 통상협정과 경쟁정책과의 이러한 상호보완적인 관계에 대한 깊이 있는 성찰이 있어야 할 것이다.

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Conflicts between Protected Franchise Territory and Unrestricted Delivery Trading Area

  • LEE, Soo-Duck
    • The Korean Journal of Franchise Management
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    • v.11 no.1
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    • pp.45-60
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    • 2020
  • Propose: The expansion of the delivery market in franchise business is a positive means of advertising and promotion for franchisees and contributes to substantial sales growth for stores. However, unrestricted and uncontrolled delivery sales and business activity of franchisee directly lead to encroachment of business territory between franchisees, resulting in increased operating costs of franchisees and conflicts between franchisees over rights and interests on franchise business. Moreover, in relation to the restrictions on the opening of competitors, it is incapacitating the law intent of prohibiting unfair encroachment of business territory, in the issue of the Fair Franchise Act in regard to guarantee of exclusive sales and business activity rights of franchisee. This study aims to point out major problems arising out of franchisee's infinite competition on delivery sales and business activity that are not restricted or controlled and then suggest legal supplements, policy tasks, and practical implications for improvement on the issues. Literature Review: In franchising business transactions, vertical restraints are associated with the exclusive territory establishment, control of transaction area, restriction of intangible sales and business activity of franchisee. Therefore, in the franchise business, it is necessary to take positive interpretation and application on e-commerce, the area of e-commerce, and delivery trading area and find proper and practical ways, by virtue of constructive attitude of each actor, to reduce the encroachment of business territory and various conflicts caused by unrestricted delivery trading area. Conclusion and suggestion: The finding shows that unrestricted or uncontrolled delivery sales and business activity of franchisees cause encroachment of business territory and many conflicts among franchisees. And this matters also weaken the legislation of the law on the protection of the business territory and can be negative factors that disrupt the protection of identity and sound development of the franchise industry in the long run. Therefore, in the franchise business, it is necessary to take positive interpretation and application on e-commerce, the area of e-commerce, and delivery trading area and find proper and practical ways, by virtue of constructive attitude of each actor, to reduce the encroachment of business territory and various conflicts caused by unrestricted delivery trading area.

Curling Behavior of Long-Span Concrete Pavement Slab under Environmental Loads (환경하중에 의한 장스팬 콘크리트 포장 슬래브의 컬링 거동 특성 분석)

  • Kim, Seong-Min;Shim, Jae-Soo;Park, Hee-Beom;Yun, Dong-Ju
    • International Journal of Highway Engineering
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    • v.11 no.3
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    • pp.151-161
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    • 2009
  • This study was conducted to investigate the characteristics of the curling behavior of long-span pavement slabs under environmental loads. By developing and using finite element models of the long-span pavement slabs, the stress distribution and the effects of slab length, slab thickness, stiffness of underlying layers, and the restraints of the slab ends on the curling behavior were analyzed. In addition, the field experiments were performed with the actual long-span pavement slab to obtain the curling behavior of the real structure under environmental loads. As a result of this study, it was found that the vertical displacements of the long-span pavement slab along the centerline due to the curling behavior were zero except for the areas near the slab ends, and the curling stresses were maximum and constant where the displacements were zero. The slab length and the stiffness of underlying layers did not affect the maximum curling stresses. The restraints at the slab ends made the curling stresses occur near the slab ends, but did not much affect the maximum curling stresses.

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Stability of structural steel tubular props: An experimental, analytical, and theoretical investigation

  • Zaid A. Al-Sadoon;Samer Barakat;Farid Abed;Aroob Al Ateyat
    • Steel and Composite Structures
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    • v.49 no.2
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    • pp.143-159
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    • 2023
  • Recently, the design of scaffolding systems has garnered considerable attention due to the increasing number of scaffold collapses. These incidents arise from the underestimation of imposed loads and the site-specific conditions that restrict the application of lateral restraints in scaffold assemblies. The present study is committed to augmenting the buckling resistance of vertical support members, obviating the need for supplementary lateral restraints. To achieve this objective, experimental and computational analyses were performed to assess the axial load buckling capacity of steel props, composed of two hollow steel pipes that slide into each other for a certain length. Three full-scale steel props with various geometric properties were tested to construct and validate the analytical models. The total unsupported length of the steel props is 6 m, while three pins were installed to tighten the outer and inner pipes in the distance they overlapped. Finite Element (FE) modeling is carried out for the three steel props, and the developed models were verified using the experimental results. Also, theoretical analysis is utilized to verify the FE analysis. Using the FE-verified models, a parametric study is conducted to evaluate the effect of different inserted pipe lengths on the steel props' axial load capacity and lateral displacement. Based on the results, the typical failure mode for the studied steel props is global elastic buckling. Also, the prop's elastic buckling strength is sensitive to the inserted length of the smaller pipe. A threshold of minimum inserted length is one-third of the total length, after which the buckling strength increases. The present study offers a prop with enhanced buckling resistance and introduces an equation for calculating an equivalent effective length factor (k), which can be seamlessly incorporated into Euler's buckling equation, thereby facilitating the determination of the buckling capacity of the enhanced props and providing a pragmatic engineering solution.

Welding deformation analysis based on improved equivalent strain method to cover external constraint during cooling stage

  • Kim, Tae-Jun;Jang, Beom-Seon;Kang, Sung-Wook
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.5
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    • pp.805-816
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    • 2015
  • In the present study, external restraints imposed normal to the plate during the cooling stage were determined to be effective for reduction of the angular distortion of butt-welded or fillet-welded plate. A welding analysis model under external force during the cooling stage was idealized as a prismatic member subjected to pure bending. The external restraint was represented by vertical force on both sides of the work piece and bending stress forms in the transverse direction. The additional bending stress distribution across the plate thickness was reflected in the improved inherent strain model, and a set of inherent strain charts with different levels of bending stress were newly calculated. From an elastic linear FE analysis using the inherent strain values taken from the chart and comparing them with those from a 3D thermal elasto-plastic FE analysis, welding deformation can be calculated.

A Study on the Application of GPS for Computation of the Vertical Deflection and Astro-coordinates (연직선편차와 천문좌표 산정을 위한 GPS의 적용연구)

  • Lee, Yong-Chang;Lee, Yong-Wook
    • Journal of Korean Society for Geospatial Information Science
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    • v.5 no.1 s.9
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    • pp.57-70
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    • 1997
  • Conventional procedures to determine vertical deflections and astronomical coordinates require the stellar observations which be under restraints of clear night-time weather conditions, surrounding environment, long observation time and the use of instruments, etc. Therefore the more effective observation method subjugatting these problems has requested. The objective of this study is to propose method to compute vertical deflections, astronomical coordinates(latitude and longitude), and astronomical azimuth by mixing GPS observation results and orthometric heights. For this study, programmed the program which able to obtain the change in geoid undulation by using the GPS- determined geodetic height difference and the orthometric height difference, and GPS satellite surveying was performed at both ten points of astronomical points and four triangulation points around each astronomical station in South Korea. The Astronomical results determined from GPS observations compared to those determined from both conventional astronomical measurements and the recent earth gravitational Model(EGM96).

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Seismic Analysis of 30/5 Ton Overhead Crane for 30MWTh Korea Multipurpose Research Reactor (KMRR) (다목적연구용 원자로의 30/5 톤 천정크레인에 대한 지진해석에 관한 연구)

  • Yoo, Bong;Suh, Ki-Suk;Chu, Yong-Sun;Hong, Sung-In
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1991.10a
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    • pp.111-114
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    • 1991
  • The KMRR 4-wheel crane which has a span of 30.6m long shall be designed to maintain its structural integrity during and after seismic shocks. Horizontal and vertical FRS for OBE and SSE conditions at the crane support are after seismic shock. Horizontal and vertical FRS for analysis are 4% for OBE and 7% for SSE. The crane consists of girder, saddle main and auxiliary trolley, and necessaries. They are modeled as beam elements and lumped masses for the following 4 cases ; trolley at center of the crane with and without the rated load, trolley at end with and without the rated load. The static analysis as well as the linear dynamic analysis including frequency and response spectrum analysis are performed for the seismic qualification of the crane using the Finite Element Method. For the simplicity of the analysis, the decoupling criteria are considered for the crane rope and the crane supporting beams. The main sections of the crane are stiffened until the calculated stresses satisfy the allowable limits. The seismic resultant loads are used to design the seismic restraints of the saddle and the trolley to protect the clue from the seismic uplifting loads the study results have show that the seismic design of the KMRR crane is governed by the OBE condition. not by the SSE condition. This paper briefly describes the analysis procedure used in the seismic design of the KMRR crane, and summarizes the analysis results.

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