• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.135-147
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• 2000

Section design of vehicle structure has been developed by two methods. One is the section property method which uses section property as a design variable. This method shows the tendency of an optimum section approximately. The other method is the section shape method which utilizes geometric parameter of section as a design variable. Practical solutions are obtained by this method. However, it is very expensive for large-scale problems due to the large number of geometric parameters. These two methods are compared through several sample problems. The finite element method is used for the structural and sensitivity analyses. The results are analyzed based on the number of function evaluations, the quality of cost function, the complexity of programing, and etc. The applications of both methods are also discussed.

• Structural Engineering and Mechanics
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• v.28 no.5
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• pp.587-601
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• 2008

In this study, a numerical procedure based on the finite element method for materially and geometrically nonlinear analysis of reinforced and prestressed concrete slender columns with arbitrary section subjected to combined biaxial bending and axial load is developed. In order to overcome the low computer efficiency of the conventional section integration method in which the reinforced concrete section is divided into a large number of small areas, an efficient section integration method is used to determine the section tangent stiffness. In this method, the arbitrary shaped cross section is divided into several concrete trapezoids according to boundary vertices, and the contribution of each trapezoid to section stiffness is determined by integrating directly the trapezoid. The space frame flexural theory is utilized to derive the element tangent stiffness matrix. The nonlinear full-range member response is traced by an updated normal plane arc-length solution method. The analytical results agree well with the experimental ones.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2505-2510
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• 2009

Semiconductor processes need measurement to confirm where there are problems in quality after progresses manufacturing process. This paper suggests equipment and automatic measure sampling method that control monitoring ratio according to change point occurrence availability of process that is not measure method by the existent simple ratio rate. This paper defines measure section as ailment section, metastable section and stability section by change point standard and create statistical model of each section and developed suitable measure rate model by section. As a result, we have accomplished maximum throughput and minimum sampling number that needs to maintain constant level of quality. Proposed method minimizes load of measure process by brings production quality sophistication and decrease of process badness and lowers measure rate in stable section making perception about problem occurrence quick heightening measure rate at change point occurrence.

• Journal of Ocean Engineering and Technology
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• v.18 no.2
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• pp.46-51
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• 2004

Natural frequencies of the transverse vibration of beams with step change in cross-section are obtained by using the asymptotic closed form solution. This closed form solution is found by using WKB method under the assumption of slowly varying properties, such as mass, cross-section, tension etc., along the beam length. However, this solution is found to be still very accurate even in the case of large variation in cross-section and tension. Therefore, this result can be easily applied to many engineering problems.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.247-250
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• 1998

The scattering of plane ultrasonic waves by the nuclear fuel pin of liquid metal reactor in sodium is studied. According to the internal composition in the cladding tube, the fuel pin has three cross sections, i.e. helium gas plenum, sodium-filled section, and fuel insertion section. The scattering spectra for each section of the fuel pin are different. The circumnavigating ultrasonic waves of each section are analyzed by the resonance scattering method. The whispering gallery wave modes are generated in the sodium-filled plenum section and the fuel rod insertion section with a sodium-gap. The circumferential wave modes are propagated in the cladding tube of the helium gas plenum section. The annular gap between the cladding tube and metal uranium pellet rod affects the scattering spectra. The different propagation characteristics can be utilized for the nondestructive method of detecting the unbonded area and measuring the level of the sodium-filled section of the fuel pin.

• Steel and Composite Structures
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• v.29 no.4
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• pp.509-526
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• 2018

The direct strength method adopted by the AISI Standard and AS/NZS 4600 is an advanced design method meant to substitute the effective width method for the design of cold-formed steel structural members accounting for local instability of thin plate elements. It was proven that the design strength formula for the direct strength method could predict the ultimate strength of medium strength steel welded section compressive and flexural members with local buckling reasonably. This paper focuses on the modification of the direct strength formula for the application to high strength and high performance steel welded section columns which have the nominal yield stress higher than 460 MPa and undergo local buckling, overall buckling or their interaction. The resistance of high strength steel welded H and Box section columns calculated by the proposed direct strength formulae were validated by comparison with various compression test results, FE results, and predictions by existing specifications.

• Structural Engineering and Mechanics
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• v.73 no.1
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• pp.75-82
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• 2020

In this study, the problem of torsion of bars with open cross section surrounded by corrugated boundaries is analyzed. An approximate analytical solution is given using perturbation technique. First, the stress analysis for circular open cross-section for arbitrary opening angle is formulated and the problem is analytically solved. Second, the open cross-section with corrugated cross section is analyzed using perturbation method. First order contributions to the stresses and the torques have been added. The results have been exemplified and compared by considering special examples.

• 대한공업교육학회지
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• v.30 no.2
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• pp.23-32
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• 2005

The purpose of this study is to investigate and analyze the actual state of teaching and learning methods which are applied to the vocation inquiry section-related subjects of the College Scholastic Ability Test(CSAT) by the teachers who teach specialized subjects of vocational high schools. In order for us to get the background and feature of establishment in the area of vocation inquiry section of the CSAT, previous studies and literature was analyzed and sample survey on the 600 teachers who teach the vocation inquiry section-related subjects was made. The result of this survey is as shown below; First, the teachers who are in charge of vocation inquiry section-related subjects understand that theory and practice is in the ratio 60.76:39.24 and ratio of theory is higher than that of practice. Second, teaching and learning method which is the most relevant to the vocation inquiry section is in the order of lecture(83.9%), experiment & practice(50.4%), computerized learning(41.1%). Third, teaching and learning method which is the most used by the teachers who are in charge of vocation inquiry section-related subjects is in the order of lecture(85.8%), computerized learning(50.1%), experiment and practice(44.4%). Forth, the most desirable teaching and learning method which the teachers who are in charge of vocation inquiry section for this subject believe is in the order of lecture(62.7%) experience & practice(47.7%), computerized learning(44.4%). In light of this result, even though there were not so much difference among the teaching-learning methods which are the most consistent with the contents of the subject in relation to the vocation inquiry section, the most used teaching-learning method by the teachers who teach vocation inquiry section-related subjects and the most desirable teaching-learning method which the teachers who are in charge of vocation inquiry section believe, the most used teaching-learning method by the teachers who are in charge of the vocation inquiry section is lecture. Therefore, it is necessary for us to reinforce the contents in relation to the practice & experiment so that the experience and application can be accumulated and improved through practice which is the specialty of the course of the study in the vocational high school and various teaching and learning method should be developed in consideration of contents of the subject, capability & quality of the learners and status of a classroom.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.862-870
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• 2010

This thesis has been researched on optimized design method for the total cross section of embankment considering the fact that the size of embankment cross section is directly related with economic efficiency when dam designing. In general, embankment cross section of fill dam is either determined by cohesion and angle of internal friction, a strength parameter of embankment materials or by permeability of embankment. Therefore the size of embankment cross section depending on strength parameter of embankment materials was determined by using MIDAS-GTS program through stress-seepage coupled analysis at the time of fill dam design. As a result, determination of embankment cross section was more affected by the size of central core and permeability rather than by slope stability by shear strength and it was revealed that in case of embankment height being over 20m, stability against infiltration and slope action could be secured only when embankment slope is at least over 1:2.5. In addition, it was also revealed that in case of making the size of central core exceeding specification standard, total cross section of embankment could be reduced considerably and at the time of embankment design, adequate size and appropriateness of embankment cross section could be determined with referring the table suggested by this study.

• 보존과학연구
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• s.27
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• pp.181-201
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• 2006

In this study, radiocarbon dating by the benzene synthesis method and liquid scintillation counting method were performed for the age determination of coal sample at the Cheongok-dong archaeologicalsite, Ulsan. The results of radiocarbon age(BP year) are section Ga #1 $2920\pm50$ BP year, section Ga #5 $3100\pm55$BP year, section Ga #6 $2820\pm60$ BP year, section Na #5 $2650\pm50$ BP year. These ages were converted to calibrated age(AD/BC year) using high precision curve. The products on the excavation of Cheongok-dong archaeological site, Ulsan, section Ga #1 BC 1260-980 BC, section Ga #5 BC1460-1200 BC, section Ga #6 BC 1110~830 BC, section Na #5 BC 920-760 BC. Comparison of samples with radiocarbon and archaeological ages for revealed the approximation.