• Proceedings of the KSME Conference
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• 2001.06a
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• pp.175-180
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• 2001

In real structure, multi-point spot welded joints are more frequently used than a single-point spot welded joint. Most researches, however, have been focused to a single-point spot welded joint until now. In this paper, the fatigue behavior of multi-point spot welded joints are investigated both experimentally and analytically using the finite elements. The local strain approach is used rather than the stress intensity factor approach to estimate the fatigue life since the former is quite simple and straightforward. It is found that the fatigue behavior of multi-point spot welded joints is different from that of single-point spot welded joints. The local strain approach is still applicable to multi-point spot welded joints.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.3
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• pp.447-455
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• 1998

It is important to identify and evaluate poor working postures properly to prevent work-related musculoskeletal disorders. The purpose of this study is to develope a new upper body micropostural classification scheme for analyzing postural stress in industry. Most of the existing postural classification schemes were based either on the literature, or on simple biomechanical principles, or on a subjective ranking system. The scheme suggested in this study was based on perceived joint discomfort measured through experiment, in which nineteen subjects participated and the magnitude estimation method was employed to obtain subjects' joint discomfort. Also, the criteria for evaluating postural stress of working postures were presented for practitioners of health and safety to be able to redesign working methods and workplaces, which was based on maximum holding time by Miedema and other people. It is expected that the scheme developed in this study could be used as a valuable tool when evaluating working postures.

• International Journal of Automotive Technology
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• v.6 no.5
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• pp.519-527
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• 2005

Recently, weight reduction of vehicles has been of great interest and consequently the use of low-density materials in the automotive industry is increasing every year. However, the substitution of one material for another is not simple because it accompanies several problems, for example, weakness in the strength and stiffness and difficulty in the joining. To overcome these problems, the structure of the automobile redesigned totoally. Aluminum spaceframe is rapidly being adopted as a body structure for accommodating lightness, stiffness and strength requirement. In aluminum spaceframe manufacturing, it is often required to join aluminum tube. However, there are few suitable methods for joining aluminum tube, so that much interest has been focused on testing suitable joining methods. Joining by electromagnetic forming (EMF) can be useful method in joining aluminum tube, which offers some advantages compared with the conventional joining methods. In this paper, joining by EMF was investigated as a pre-study for applying an automotive spaceframe. Finite element simulations and strength tests were performed to analyze the influence of geometric parameters on joint strength. Based on these results, configurations of axial joint and torque joint were suggested and guidelines for designing EMF joint were established.

• International journal of steel structures
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• v.18 no.4
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• pp.1284-1296
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• 2018

Carbon fiber reinforced polymer (CFRP), plates bonding repair method is one of the simple repair methods for cracked steel structures. In this study, the influence of width of CFRP plates on bending fatigue life of out-of-plane gusset joint strengthened with CFRP plates was investigated from the experimental and numerical point of view. In the bending fatigue test of cracked out-of-plane gusset joint strengthened with CFRP plates, the effect of width of CFRP plates on crack growth life was clarified experimentally. Namely, it was revealed that the crack growth life becomes larger with increasing the width of CFRP plates. In the numerical approach, the stress intensity factor (SIF) at the surface point of a semi-elliptical surface crack was estimated based on the linear fracture mechanics. Furthermore, the extended fatigue life of cracked out-of-plane gusset joint strengthened with CFRP plates was evaluated by using the estimated SIF at the surface point and the empirical formula of the aspect ratio of semi-elliptical crack. As the results of numerical analysis, the estimated fatigue life of the specimen strengthened with CFRP plates showed the good agreement with the test results.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.49-56
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• 1999

Crustal velocity model is very important to determine the hypocenters of the local earthquakes because the real crust is more complex and heterogeneous than simple homogeneous layerd model. But the exact crust model in and around Kyeongsang basin area is not fixed till now. To solve this problem Joint Hypocenter Determination(JHD) method is applied to the 133 local earthquakes that is recorded at KIGAM local network from Dec. 14 1994. to May 14, 1998. According to the comparision of earthquake locations and depths for the conventional procedure and JHD relocation procedure each locations is very similar but depth distributions are different. An initial depth distribution derived from the conventional methods is irregular and does not show the general trends. JHD relocations reduce scatter and define a dipping plane which is parallel to and apart 15km north from Ulsan fault.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.8-12
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• 2003

Crustal velocity model is very important to determine the hypocenters of the local earthquakes, because the real crust is more complex and heterogeneous than simple homogeneous layered model. But the exact crust model in and around Kyeongsang basin area is not fixed till now. To solve this problem, Joint Hypocenter Determination(JHD) method is applied to the 151 local earthquakes, that is recorded at KIGAM local network from Mar. 25, 1999 to Dec. 16, 2001. According to the comparison of earthquake locations and depths for the conventional procedure and JHD relocation procedure, each locations is very similar, but depth distributions are different. An initial depth distribution derived from the conventional methods is irregular and does not show the general trends. JHD relocations reduce scatter and define a dipping plane.

• Journal of Chest Surgery
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• v.18 no.3
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• pp.492-496
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• 1985

Two cases of surgical correction of funnel chest using metal struts were presented. The main procedures of the method were transverse submammary incision, subperichondrial resection of the deformed costal cartilages, division of the xiphisternal joint, wedge osteotomy of the sternum, freeing of the posterior surface of the sternum and stabilization by means of 2 metal struts. The struts were removed postoperative 3 and 6 months by a small incision under the local anesthesia. The results in both patients were satisfactory. This method of correction is simple, easy to perform and free of any operative risks.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.2
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• pp.3-12
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• 2001

This paper presents the proposed methods of DE (distinct element) modelling to estimate the stability of tunnels in jointed rock masses. First, the criterion to select the joint set(s) contributed to the discontinuous behaviour in a tunnel section is proposed. Selected joint set(s) is(are) considered to form the edges of distinct elements (rock blocks) and the others to modify the elastic properties of rock blocks. The complex DE model with the average and the deviation of joint orientation and joint length for each joint set was compared to the simple model with only the average of joint orientation and the assumption that joint length is infinite. As a result, the latter is suitable to the purpose of tunnel design because it can show the consistent behaviour of a jointed rock mass such as the locally discontinuous failure and the global anisotropic behaviour.

• Journal of Korea Multimedia Society
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• v.3 no.3
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• pp.272-279
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• 2000

When the multiple video sources are together transmitted through the channel of fixed bandwidth, the efficiently joint bandwidth allocation is necessary. This paper presents the joint bandwidth allocation method to keep the constant picture duality ratio among the video sources. We first find an approximated model of distortion and bitrate for the multiplexing system of multiple sources. Then we obtain the bitrate for each source to have constant distortion ratio among the sources by using the approximated model parameters for simple implementation. It is shown by simulation that the proposed bandwidth allocation can keep almost constant picture quality ratio among the sources in comparison to an independent bandwidth allocation method.

• Land and Housing Review
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• v.1 no.1
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• pp.67-73
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• 2010

Method of protruding steel bar embedded in PHC pile for connecting with foundation plate is an intermediate form of fixed and hinged connection and has often been used in architectural structures such as apartment complex. However, mechanical properties of this method have not been proved and its construction process is not simple. In this study, therefore, by analyzing previous research and by considering ratio of steel bar and concrete in PHC pile, which is minimum reinforcement of rebar, the newly optimized method of reinforcing joint of PHC pile and foundation plate is suggested with respect to PHC pile type (PHC 450, PHC 500, and PHC 600). To assess mechanical properties (ultimate tensile and shear strength) of joint of PHC pile and foundation plate, full scale experimental tests are performed. As a result, all cases are satisfied with required design criteria and can be practically applied. Our results indicate that reduction of rebar reinforcement compared to previous method would lead cost saving in PHC pile construction.