• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.609-618
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• 2009

This paper proposes a versatile formula which can be used to evaluate the fire resistant time of steel beams under various design conditions. Towards this end, the key parameters which affect the fire performance of steel beams were first determined through thermo-mechanical considerations, and classified into two groups: structural parameters and thermal parameters. Then the degree of influence of each parameter on the fire performance was investigated through a fully coupled thermo-mechanical analysis up to the occurrence of run-away deflection. The accuracy of the numerical model used was verified using an available full-scale fire test before conducting an extensive parametric analysis. Multiple linear regression analysis was performed to obtain the formula which can be used to predict the fire resistance time of steel beams under various design conditions. The statistical analysis showed that the proposed formula is very robust. The application of the formula in practical fire design under the current code was illustrated in detail. The economy and other advantages of the proposed formula were clearly shown.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.66-71
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• 2010

With large specific strength and outstanding corrosion resistance and erosion resistance in sea water, titanium and titanium alloy are widely used in heat exchanger production. In particular, pure titanium demonstrates outstanding molding performance and may be considered optimal for production of heat exchanger. Since titanium is very vulnerable to oxidation and embrittlement during welding, processes with less heat input are widely used, and laser welding is widely applied by considering production performance and shield etc in atmosphere. So far, 1st report and 2nd report compared and analyzed embrittlement degrees by bead colors of weldment through oxygen and nitrogen quantitative analysis and hardness measurement, and evaluated welding performance and mechanical properties of butt welding. This study evaluated field applicability of lap welding to heat exchange plate of LPG re-liquefaction device for ships through tensile stress test, hardness test and internal pressure test etc after deducing optimal weding condition and applying to actual heat exchange plate. In bead overlap area, the experiment produced sound welds with no porosity or defect by increasing and decreasing laser power, and tensile-shear test results indicated virtually the same tension and yield strength as base metal. As a result of measuring hardness at lateral cross section and bead overlap zone of actual heat exchanger welds, hardness difference within 20Hv was produced at base metal, HAZ and weldment, and as a result of pneumatic and hydraulic pressure test, no leakage occurred.

• Korean Journal of Veterinary Research
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• v.57 no.4
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• pp.227-233
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• 2017

To reduce swine production costs, a slaughter check system has been developed in countries with an advanced swine industry. Evaluation of lung lesions in carcasses is a critical part of the slaughter check system. This study was performed to collect background information for use in developing a slaughter check system in Korea. Lung tissues and their gross images were collected from slaughterhouses in Gyeonggi-do, Korea. Scoring of the gross lung lesions was performed on the lung images. Histopathologic examination was conducted to classify the pulmonary lesions as bronchopneumonia or interstitial pneumonia. Scores of the gross lung lesions were significantly different between bronchopneumonia and interstitial pneumonia groups (p < 0.001). A 90% confidence interval of gross lung lesion scores was established for the bronchopneumonia group, and the lesion scoring had a sensitivity of 100% and specificity of 77.3%. The gross lung lesion scoring test was subjected to a diagnostic distinction evaluation by examining the receiver operating characteristic curve and was appraised as having good discrimination for bronchopneumonia. Establishment of a gross lung lesion scoring test for the diagnosis of bronchopneumonia could be valuable as a screening test of macroscopic bronchopneumonia in swine slaughter check system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1181-1187
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• 2012

For the fatigue design of aircraft landing gear, the safe-life approach is applied. Structural defects such as cracks or detrimental deformations should not occur under the fatigue load spectrum depicting the entire lifetime usage of the aircraft. In the design phase, the fatigue life of the landing gear is estimated analytically by adopting the stress-based approach because the fatigue of aircraft landing gear is generally high-cycle fatigue. This utilizes S-N curves that are factored to produce design curves that account for the scatter and surface finish of the material. In the test and evaluation phases, a fatigue test should be conducted for full-scale landing gear to substantiate the fatigue design requirement in the end. In this study, the procedure for the fatigue test and evaluation of aircraft landing gear is presented with real application cases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.65-70
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• 2014

This paper introduces a preform design method for a ring rolling process with an outer step. Underfilling is one of the general defects of the profile ring rolling process. It occurs when the deformation amount is small or step depth of the profiled region is large. To prevent underfilling, increasing the deformation amount or using a preform of size similar to that of the final product are required. Furthermore, the filling limit equation is suggested based on the shape factor and deformation ratio for preventing defects in the products. The filling limit equation has been derived through finite element analyses and production tests for four different cases. For verifying the suggested method, realsized profile rolling tests were performed, and test results were compared with the predictions of the equation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.8
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• pp.56-64
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• 2005

It is prerequisite that we have to fomulate the nonlinear mathematical modeling to design the guidance and control system of rotorcraft-based unmanned aerial vehicle using a small-scaled commercial helicopter. The small-scaled helicopters are very different from the full-scale helicopters in dynamic behavior such as high rotation speed and high frequency dynamic characteristics. In this paper, the formulation of the mathematical model of the small-scaled helicopter to minimize the complexity is presented by component and source build-up approach. It is linearized at the trim condition of hovering and forward flight and analyzed the flight modes. The results of this approach have general trends but a little difference. To verify this approach, it is necessary to compare this theoretical model with experimental results by system identification using flight test as a next research topic.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.336-342
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• 2005

Stone column or granular compaction pile have been used in widely during the several decades as a technique to reinforce soft cohesive soils and increase bearing capacity, accelerate consolidation settlement of the foundation soil. The bearing capacity of the granular compaction pile is governed mainly by the lateral confining pressure mobilized in the native soft soil to restrain bulging collapse of the granular pile. Therefore, the technique becomes unfeasible in soft, compressible clayey soils that do not provide sufficient lateral confinement. This paper presents the main results of numerical study of granular compaction pile which is partly mixed with lean concrete. 3D finite element analyses are performed with composite reinforced foundations by both granular compaction pile and partly mixed granular compaction pile with lean-mixed concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.116-124
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• 2011

To purpose of this study is to develop the new type of precast concrete baseplate which is only for bimodal tram. The experiments with real size specimens, which are hollowed precast baseplate, prove the efficacy of new designed baseplate by comparing with the result of RCAHEST. Through tests progressed according to different loading locations, the specimens show the stability by the safety factor of 8~9. Also the results of RCAHEST that is the nonlinear finite element method program, appropriately estimate the occuring crack on concrete, yielding reinforcement and ultimate behavior at failure.

• Journal of Information Management
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• v.35 no.2
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• pp.1-40
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• 2004

Theses and dissertations are works embodying results of original research on a subject and substantiating a particular point of view by usually graduate students, as a degree requirement. Most theses and dissertations are not controlled by commercial publishing interests, and thus are not obtained in book-form by most libraries. Due to their lack of physical and ready availability and information about the contents, theses and dissertations have been extremely underutilized sources of information without distinction of nations. The goal of this paper is to provide the current informations on the distribution and management systems of theses and dissertations in Foreign and Korea. The findings of this study will provide the basis for developing an standardized management model of theses and dissertations that meets the needs of researchers, students, and librarians in Korea.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.1
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• pp.1-10
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• 2009

The purpose of this study was to investigate the effects of the types and the colors of men's casual wear, hairstyles, and the methods of stimulus manufacture on men's image perception. The subjects were 360 women from the metropolitan area of Seoul. The clothing types used for the study were a sweater and a jumper(casual jacket) with jean pants. The clothing colors were beige, indigo, and red. Two hairstyles, the short and the medium length hairs, were compared. Two types of stimuli, the photograph and the computer simulation picture, were used. The results of the factor analysis disclosed five dimensions on men's image: neatness, individuality, ability, activity, and sociability. In general, the photograph stimuli were evaluated more positively in activity, individuality, and sociability than the picture stimuli. The sweaters were perceived higher in ability, activity, and sociability than the jumpers. The Indigo color was evaluated as neat. The medium length hairstyles were perceived as neat and the short hairstyles were perceived as sociable. The jumpers were evaluated lower in individuality in the picture stimuli than in the photograph stimuli. The beige and indigo colors were evaluated to be neater in the picture stimuli than in the photograph. When using the picture stimuli, the men's image wearing the sweaters with the medium length hairstyles were evaluated lower in individuality. When using the photograph stimuli, the men's image wearing the sweater with the short hairstyles were evaluated higher in activity. Men's image wearing the indigo jumper and the beige sweater with medium length hairs were evaluated as high in neatness.