• Journal of Welding and Joining
• /
• v.34 no.6
• /
• pp.20-27
• /
• 2016

This study deals with the proper conditions of the trail rolling method (TRM) for the prevention of the buckling welding distortion at the AA5083 GMA butt weldment. For it, the effect of the working conditions of TRM including the rolling depth and the rolling distance between the welding torch and the roller on the longitudinal welding shrinkage force of the weldment was evaluated by using 3 dimensional thermo-mechanical FE analyses. The longitudinal welding shrinkage force inducing the buckling welding distortion at the GMA butt weldment was mitigated with an increase in the rolling depth and the rolling distance between the welding torch and the roller. Based on the results, the proper conditions of trail rolling method were established to reduce the longitudinal welding shrinkage force of the GMA butt weldment to below the critical value corresponding to the bucking distortion.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1611-1613
• /
• 2000

In this study in order to find out the trends and the residual lifetime for electric connections/contacts using infrared image camera, "lifetime temperature rise model" is theoretically proposed on the base of "lifetime resistance model" and to prove this theory, experiments have been performed for various kinds of electric connections/contacts. Two suggestions have been builded up or the "lifetime temperature rise model" ; one is the linear relationship between the temperature rise $\Delta K$ and contact resistance, and the other is the functional relationship between the temperature of electric connections/contacts and the operating time which ascribed in the "lifetime resistance model". From the experimental results, measured values were quite similar to the theoretical value so that two suggestions in "lifetime temperature rise model" were appeared to be correct.

• Journal of Industrial Technology
• /
• v.31 no.A
• /
• pp.87-94
• /
• 2011

This paper is results of analyzing characteristics of landslides occurred in Wonju, Gangwondo, around July, 16 in 2006, caused by heavy rainfall and antecedent precipitation by two typhoons of Ewiniar and Bilis. The main causes of landslides were antecedent precipitation during July 8 to 15, resulting in weakening grounds by increasing the degree of saturation previously, and the heavy rainfall during July 15 to 16. Most of landslides in natural slopes were transitional failures occurred along the boundary between the residual weathered soil in shallow depth and the hard mother rock. From results of conclusive analyses regarding 28 sites in Wonju region where landslides occurred, the slope length of landslide, the slope width, and the slope area were less than 50m with 71% of frequency, 20m with 79% of frequency and $300m^2$ of 64% of frequency respectively. The average value of slope angle was $35^{\circ}$. The most probable direction of slope was found to be north because of topography and advancing direction of seasonal rain front.

• Journal of Magnetics
• /
• v.4 no.3
• /
• pp.73-75
• /
• 1999

By appliying an slternate pulsed magnetic field -generated by using a sequential ignition circuit and a magnet exciting circuit- with peak value of about 10 T to the rod type Nd based magnet Nd2Fe12.7Cr1.3B with length of 5 mm and diameter of 3.6 mm, the basic magnetic properties such as saturation magnetization, residual magnetization, coercivity, maximum energy products, magnetic anisotropy and anisotropic field are investigated with obtaining the major and minor J-H loops of the magnet. The increase in coercivity due to eddy currents in ac measurement of coercivity is calculated considering eddy current loss by analyzing a wave of generating magnetic field. The average coercivity calculated for the magnet is about 12.2 kOe, anisotropy magnetic field and anisotropic constant are measured as 60 kOe 2.43 Mj/$m^3$, respectively.

• Convergence Security Journal
• /
• v.9 no.1
• /
• pp.39-44
• /
• 2009

To get legitimacy of a security investment, the analysis of ROI about the security investment is required. In this paper, we suggest a practical quantitative model with considering factors that do decision-making of optimized security investment difficult. This model makes use of the value of a residual risk to decide the best information security solution and considers a corelation of response techniques of the information security solution against each threat to do exact decision-making.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.745-748
• /
• 2006

This study investigates the fundamental properties and examines spalling appearances and residual compressive strength of high strength concrete containing hybrid organic fibers subjected to fire. Test showed that overall, an increase of fiber content decreased the fluidity of concrete, but specimens containing polyvinyl alcoho(PVA)+polypropylene(PP) fiber and nylon(NY)+PP fiber had improved flow. In addition, the air content of all specimens was properly ranged in target value, regardless of fiber content. As for the spalling properties when completed the fire test, control concrete exhibited spalling occurrence due to sudden elevated temperature. However, specimens containing more than 0.1 vol% of PP fiber prevented the spalling, while specimens containing PP+CL and PVA+PP fiber can protected from fire in more than 0.15vol% of the fiber content. Importantly, a specimen containing only 0.05vol% of NY+PP showed the favorable spalling resistance performance.

• Journal of Chest Surgery
• /
• v.23 no.3
• /
• pp.507-513
• /
• 1990

We experienced an intraatrial baffle repair for unroofed coronary sinus syndrome in TOF. The patient was a 32-month old female, with complaints of cyanosis, exertional dyspnea and growth retardation. Physical examination showed cyanosis of lip, clubbing of finger, growth retardation and systolic murmur[0 /Gr VI] on left sternal border. With an aid of noninvasive and invasive diagnostic procedure, the patient was diagnosed as TOF combined with unroofed coronary sinus syndrome and LSVC connecting to left atrium. After patch closure of VSD, infundibulectomy and pulmonary valvotomy, the intraatrial baffle redirection of anomalous LSVC to right atrium was undertaken. The Dacron baffle was constructed along the roof of the left atrium to the plane of the atrial septum. The intraatrial septum was then reconstructed with Dacron which was sutured to residual septal tissue. After surgery, the systemic oxygen saturation was elevated to 95.5%, as compared with preoperative value 61%. The postoperative course was uneventful.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.445-448
• /
• 2005

Recently, injection molding process became more popular than ever to produce large quantities of high precision products or optical products. Injection molding products can cause sensorial problems because of high birefringence or deformation from the residual stresses in the optical media. In the present study, we have focussed on the effect of holding and compression pressures on the optical anisotropy remaining in the MOD by examining the gapwise distribution of birefringence and extinction angle The effect of holding pressure was found to form the inner two birefringence peaks. But the effect of compression pressure on the birefringence distribution was found to make the uniform distribution near the center in the gap-wise direction. Finally, the value of the birefringence near the wall decreased as the mold temperature increased.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1993.10a
• /
• pp.29-34
• /
• 1993

In many circumstances, it is desired to move a mass from one position to another without inducing any vibration in the mass being moved. Two such problems are considered here: the motion of a pendulum initiated by the specified motion of its support. In each case, it is desired that the system start at rest and come to rest in the second position. A simple strategy for the specified motion is given here. The method is motivated by engine cam-follower design. The force required to move the system in question is determined as well as the maximum value of the force required (and the times at which these forces take place) is determined.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.03a
• /
• pp.481-490
• /
• 2003

This paper presents an efficient eigensolution method for non-proportionally damped systems. The proposed method is obtained by applying the accelerated Newton-Raphson technique and the orthonormal condition of the eigenvectors to the linearized form of the quadratic eigenproblem. A step length and a selective scheme are introduced to increase the convergence of the solution. The step length can be evaluated by minimizing the norm of the residual vector using the least square method. While the singularity may occur during factorizing process in other iteration methods such as the inverse iteration method and the subspace iteration method if the shift value is close to an exact eigenvalue, the proposed method guarantees the nonsingularity by introducing the orthonormal condition of the eigenvectors, which can be proved analytically. A numerical example is presented to demonstrate the effectiveness of the proposed method.