• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.573-579
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• 2004

For the fast construction and replacement of bridges in urban area, a prefabricated bridge system can be an excellent alternative. Details of prefabricated slabs for PSC girders were developed and static tests on shear connections were conducted to propose design equations of the shear connection. Stirrups and stud connectors were used as shear connectors and non-shrink mortar was used for the filling material in shear pockets for shear connectors. Stirrups and studs were fabricated to insert embedded nut-type devices in PSC girders. Shear strength of the shear connection considering chemical bond, friction and mechanical connectors was evaluated and empirical equations were suggested. Due to the mechanical connectors, ultimate slip capacity of the shear connection was sufficient for shear load redistribution, and suggested details of the shear connection showed good performance in terms of strength and ductility.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.305-310
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• 2001

Within some degree of journal misalignment, maximum pressure, maximum temperature, bearing load, friction and side leakage in high-speed journal bearing operation are examined under the condition of variable density and specific heat. The results are compared with the calculation results under the conditions of constant density and specific heat, and variable density and constant specific heat. It is found that the effects of variable density and specific heat on shaft misalignment are significant in determining the load capacity of a journal bearing operating at high speed.

• Tribology and Lubricants
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• v.27 no.4
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• pp.183-192
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• 2011

In this study, using the governing equations for thermohydrodyamic lubrication involving the homogeneous mixture of incompressible fluid derived by based on the principle of continuum mechanics, it is discussed the effects of water dispersed within engine oil on the performance of high speed journal bearing of a turbocharger. The governing equations are the general equations being able to be applied on the mixture of Newtonian fluid and non-Newtonian fluid. Here, the fluid viscosity index, n of power-law non-Newtonian fluid is supposed to be 1 for the application of the journal bearing on a turbocharger lubricated with the mixture of two Newtonian fluids, water dispersed within engine oil. The results related with the bearing performance are showed that the friction force and bearing load capacity decrease as increasing the volume percent of water.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.1 no.1
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• pp.65-74
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• 1995

There is no line of demarcation between the shoulder and elbow regions. Pain In the arm may originate at the shoulder with reference downwards or less often at the elbow with reference upwards. Most pains indicated by the patient at the elbow or forearm have a local origin, since at the more distal part of the upper limb the capacity for correct localization is good. Once it is clear that the elbow region is at fault, the joint and the muscles about it are tested by ten movements. 1. Four. Passive extension, flexion, pronation, supination-full range, LOM, painful, painless. 2. Four. Resisted extension, flexion, pronation, supination-strong, weak, painful, painless. 3. Two. Resisted flexion, extension at the wrist-painful, painless. The muscles that perform theses two movements arise from the humeral epicondyles and a lesion in either often causes pain felt at the elbow although the tissuse affected is not functionally a part of the elbow (i. e. Tennis elbow and Golfer's elbow).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.9
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• pp.595-603
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• 2011

In this study, an effort has been made to analyze the subcooled boiling heat transfer in a natural circulation vertical evaporator. To verify the analysis, a small-scale model was made and tested. The friction correlation by Ueda, void fraction and quality correlation by Saha and Zuber along with the superposition heat transfer model by Rohsenow yielded a satisfactory agreement with the model test data. The analysis was extended to simulate a 1 ton/day concentration system. Comparison with the test results of 1 ton/day prototype revealed that the data were overpredicted by 13%. The capacity of the prototype was 1.2 ton/day with COP of 5.77.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.766-772
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• 2002

In this investigation, experimental attempts were made to observe and determine the variations in elastic and damping properties of the PVC depending on the amounts of MBS added to the mixture, PVC/MBS, and also on the thicknesses of the specimens. An acoustic resonance technique was used for the tests In this investigation. It serves as a method to characterize properties of materials set in vibrational motions, which is initiated by low level stresses generated by externally supplied acoustic energy. Substantial variations were observed in the test results with the addition of the MBS to the PVC. It was found that the magnitudes of elastic constants decrease while the damping capacity improve when MBS rubber was added in the range up to 9 phr.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.3
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• pp.234-240
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• 2011

This study deals with progressive collapse of a structure retrofitted with MR dampers. In order to assess their effect of mitigation which prevents progressive collapse, control force ratio is defined by friction force of MR dampers divided by external force. First, simple model of a structure with MR dampers is suggested. Using the model, exact solution with the control force ratio is obtained. When and where the system is stopped is predicted by the derived solution. Through the dissipated energy by MR dampers during collapse event, equivalent damping ratio is derived. Finally, comparison of exact and equivalent solutions is presented.

• Steel and Composite Structures
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• v.15 no.1
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• pp.41-55
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• 2013

This paper presents a numerical study of axially loaded concrete-filled steel tubular columns with "T" shaped cross section (CFTTS) based on the ABAQUS standard solver. Two types of columns with "T" shaped cross section, the common concrete-filled steel tubular columns with "T" shaped cross section (CCFTTS) and the double concrete-filled steel tubular columns with "T" shaped cross section (DCFTTS), are discussed. The failure modes, confining effects and load-displacement curves are analyzed. The numerical results indicate that both have the similar failure mode that the steel tubes are only outward buckling on all columns' faces. It is found that DCFTTS columns have higher axial capacities than CCFTTS ones duo to the steel tube of DCFTTS columns can plays more significant confining effect on concrete. A parametric study, including influence of tube thickness, concrete strength and friction coefficient of tube-concrete interface on the axial capacities is also carried out. Simplified formulae were also proposed based on this study.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.400-403
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• 2004

A non-heat기leafed steel does not need quenching and tempering processes that are called a heat treatment differently from conventional steel. Since the tensile strength of this steel is higher than 900MPa, a conventional forming process should be changed to incremental forming process such as a cross wedge rolling that requires lower load capacity than conventional ones. In this paper, the cold cross wedge rolling (CWR) die has been designed using CAD/CAE In order to produce near-net-shaped component of ball stud of non-heat-treated cold steel. Finite element analyses were applied in order to investigate process parameters of CWR. Results provide that the stretching angle and the forming angie at knifing zone in CWR process is important parameter to be the stable process under the low friction coefficient condition.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.99-106
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• 2005

본 연구에서는 케이싱을 영구부재로 사용함으로써 기존의 현장타설말뚝과 비교하여 시공 성,품질균일성,경제성, 내구성 등을 검토한다. 연구결과 케이싱을 영구부재로 사용하는 경우, 케이싱의 재사용을 위한 인발작업이 불필요하게 되고,말뚝길이전체에 대하여 케이싱을 사용한다면 R.C.D공법에 서 적용하는 슬러리공벽보호공정이 불필요하므로 시공성이 향상되는 것으로 판단된다. 케이싱을 영구부 재로 사용하는 현장타설말뚝의 지지력은 일반 깊은 기초의 지지력을 산정하는 방법과 동일하게 구해질 수 있다. 대구경의 영구케이싱이 있는 현장타설말뚝을 시공한다면 공내에 간단한 장비와 인력을 투입해서 선단부를 그라우팅방법 등으로 강화시킴으로써 선단지지력을 효과적으로 증대시킬 수 있을 것이다. 또한 케이싱 내부로부터 미리제작한 구멍을 통하여 그라우팅, 전단키(shear key) 등을 주입 또는 압입 함으로써 주면마찰력도 크게 향상될 수 있을 것으로 사료된다.