• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.37-49
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• 2020

Objective: The purpose of this study was to investigate the injury factors of Taekwondo jumping kick during landing phase according to the experience of injury and to suggest a stable landing movement applicable to free style Poomsae. Method: The participants were non-injury group (NG), n = 5, age: 20.5±0.9 years; height: 171.6±3.6 cm; body weight: 65.7±4.4 kg; career: 5.0±2.7 years. Injury group (IG), n = 9, age: 21.0±0.8 years; height: 170.9±4.6 cm; body weight: 67.1±7.0 kg; career: 8.6±5.0 years. The variables are impact force, loading rate, vertical stiffness, lower limb joint angle, stability, balance, and muscle activity in the landing phase. Results: NG was statistically larger than IG in the gluteus medius (p<.05). The impact force, loading rate and vertical stiffness decreased as the landing foot angle, the ROM of lower limb joint angle and COM displacement increased (p<.05). Conclusion: Based on the results, it means that the landing foot angle plays an important role in the impact reduction during landing phase. It is required the training to adjust the landing foot angle.

• Archives of Reconstructive Microsurgery
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• v.20 no.1
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• pp.82-88
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• 2011

Vascularized free fibula head transfer is an established method for reconstruction of long bone defects of the upper limb involving the distal radius or the proximal humerus. For the wrist following tumor resection, in cases of resection of the radial articular surface, three reconstructive options are possible: 1. fibular head transfer to replace the radial joint surface, 2. fixation of the fibula to the scaphoid and lunate, 3. complete wrist fusion. The decision on the type of the operation depends on the amount of the resection and the remained normal anatomical structures, and also the necessity of function of the wrist in the future. The authors believe that the vascularized free fibula head graft is a safe and reliable method for reconstructing the upper limb, especially for patients with a defect of the distal radius, and report the operative methods, donor vascular consideration, complications, and functional result after this operation.

• Composites Research
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• v.12 no.5
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• pp.65-79
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• 1999

This paper descrives the method to analyzed the free vibratioin of supported composite cylindrical shells with a longitudinal, interior rectangular plate. To obtain the free vibration characteristics before the combination of two structures, the energy principle based on the classical plate theory and Love's thin shell theory is adopted. The frequency equation of the combined system is formulated using the receptance method. When the line load and moment applied along the joint are assumed as the the Dirac delta and sinusolidal function, the continuity conditions at the joint of the plate and shell are proven to be satisfied. The effects on the combined shell frequencies of the length-no-radius ratios and radius-to-thickness ratios of the shell, fiber orientation angles and orthotropic modulus ratios of the composite are also examined.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.92-98
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• 2003

This paper describes the numerical prediction of the thermal fatigue life of a $\mu$BGA(Micro Ball Grid Array) solder joint. Finite element analysis(FEA) was employed to simulate thermal cycling loading for solder joint reliability. Strain values, along with the result of mechanical fatigue tests for solder alloys were then used to predict the solder joint fatigue life using the Coffin-Manson equation. The results show that Sn-3.5mass%Ag solder had the longest thermal fatigue life in low cycle fatigue. Also a practical correlation for the prediction of the thermal fatigue life was suggested by using the dimensionless variable ${\gamma}$, which was possible to use several lead free solder alloys for prediction of thermal fatigue life. Furthermore, when the contact angle of the ball and chip has 50 degrees, solder joint has longest fatigue life.

• PNF and Movement
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• v.5 no.1
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• pp.49-56
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• 2007

Objectives : We find that the reaction force on the elbow joint during elbow flexion, extension with and without an object in the hand can be calculated the equations of motion that the sum of the torque and the sum of the force acting on the elbow joint must be zero and (moment of inertia x angular acceleration) and (mass x acceleration). Methods : we have calculated the equations of motion (${\Sigma}F=0$, ${\Sigma}{\tau}=0$, ${\Sigma}F=ma$, ${\Sigma}{\tau}=Ia$) to investigate the reaction force on the elbow joint during elbow flexion, extension by means of the simplified free-body technique for coplanar forces. Results : we found that the reaction force on the elbow joint during elbow flexion, extention as constant acceleration motion is more than constant velocity, static motion. Also, we found that the relation between during flexion and during extension like this ; $J_{flexion}$ < $J_{extension}$.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.3
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• pp.37-42
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• 2003

In soldering of electronic packaging, the research on substituting lead-free solder materials for Pb-Sn alloys has become active due to environmental and health concerns over the use of lead. The reliability of the solder joint is very important in the development of solder materials and it is known that it is related to wettability of the solder over the substrate and microstructural evolution during soldering. It is also highly affected by type and extent of the interfacial reaction between solder and substrate and therefore, it is necessary to understand the interfacial reaction between solder and substrate completely. In order to predict the intermetallic compound (IMC) phase which forms first at the substrate/solder interface during the soldering process, a thermodynamic methodology has been suggested. The activation energy for the nucleation of each IMC phases is represented by a function of the interfacial energy and the driving force for phase formation. From this, it is predicted that the IMC phase with the smallest activation energy forms first. The grain morphology of the IMC at the solder joint is also explained by the calculations which use the energy. The Jackson parameter of the IMC grain with a rough surface is smaller than 2 but it is larger than 2 in the case of faceted grains.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.83-85
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• 2003

This paper is investigated the shear strength by using the micro shear-punch test method for Sn-37Pb alloy, binary and ternary alloys of environment-friendly Pb-free solder alloys which would be surely applicable to the electronic packages. As a result, in case of Max. shear strength, Sn-4Ag-0.5Cu has the highest value and Sn-37Pb has the lowest value on every condition of experiment temperature. Also, In case of Pb-free solder joint specimens, it was found that Pb-free solder alloys have higher value of shear strength than eutectic Sn-Pb solder alloy and Sn-4Ag-0.5Cu has the highest value.

• Journal of the Korean institute of surface engineering
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• v.38 no.6
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• pp.216-226
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• 2005

Pb-Free Technology was born with environmental problems of electronic component, Being connected by big and small project of every country. Also, in each country environment is connected and various standards of IEC, ISO, MIL, JIS, KS, JEDEC, EIAJ etc. All products can divide at solder part and finishing part These can tested each and synthetically divide. This research is reliability evaluation for three kind of ph-free SnCu solder plating solution and it's deposit. First, executed analysis about Pure Sn, SnCu solutions and plating surface by way similar to other plating solution analysis. Next, executed reliability about test method and equipment for reliable analyzer system construction. Next, data comparison and estimation, main estimation test method and item's choice. In this paper the systematic surface analysis and reliability for plating solutions and it's deposit in metal surface finishing processes could be shown.

• Archives of Reconstructive Microsurgery
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• v.11 no.2
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• pp.167-172
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• 2002

The only treatment method for crushed soft tissue injuries in the proximal leg involving the knee joint is the microsurgical free flap transplantation, especially latissimus dorsi myocutaneous free flap is useful to cover the extensive soft tissue defects, therefore prevents iatrogenic below knee amputation and facilitates early wound healing, early ambulation and shortens hospital stay. Authors have treated the open amputation with crushed soft tissue and bone injuries in the proximal leg, and the repeated abrasion and infectious wound with traumatic neuroma in the below knee with myocutaneous free flap and succeeded to wear below knee amputation prosthesis and return to normal activities of the daily living in the relatively shorter period than usual.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.23-33
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• 2007

The growing environmental regulation governs the use of lead by RoHS, WEEE, and then. The electronic industry is moving to replace Pb-bearing solder with Pb-free solder. To use the Pb-free solder, microelectronic industry needs consequently the new reliability appraisal such as the packaging for high temperature process, various mechanical change caused by new solder, and the development of Pb-free sloder for long life of product. The evaluation of solder bar and mechanical properties of joint were performed compared with international standard, and new appraisal standard was established. The solderability and spread ability of Sn-0.7Cu solder material showed up to the standard. Shear test of solder joint using by the solder resulted that the shear strengths after thermal shock or after aging were not much lower than the shear strength of as-soldered and that they were also up to the standard.