• 소성∙가공
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• 제8권1호
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• pp.7-13
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• 1999

In this study, side panels were developed using the laser-welded tailored blank (T.B.) of both the same thickness and different thickness. At first, the formability of the same thickness T.B. was investigated to compare with one of the non-welded panel with respect to weldline movement and strain distribution in blank during the stamping process. Based on these results, we determined the weld line positions and the die step for T.B. forming of the blanks composed of different thickness combination. Then we made some stamping tryouts with selected types of blanks to investigate the formability of T.B. of the different thickness. During the tryouts, wrinkles were found in the a-pillar lower region which is under the deformation mode of the shrink flange. In the b-pillar region, fractures were also found. These defects have been reduced and corrected by controlling the blank design, the die faces and process parameters.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.487-488
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• 2006

In these days, demand of a LCD monitor is remarkably increasing with development of the LCD technology. However, there are thermal problems for improvement of efficiency for the LCD monitor. Thus, this research analyzed thermal problems such as convection and conduction heat transfer characteristics in the LCD monitor using an infrared (IR) camera. Also, the results of the outer side of the front LCD panel using the IR camera have been compared with the results of the inner side of the front panel using T-type thermocouples. The equations have been derived for the temperature distribution of the inner side of the front LCD panel by a multiple regression method including variables for ambient temperature, humidity and temperature differences between the front and back panels of the LCD monitor.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.51-55
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• 2004

A composite Iso-grid panel is manufactured and tested by compressive load. Vertical stringers and side stringers are joined with skin by secondary bonding using a liquid type adhesive. Bonding fixtures were developed to attach the stringers to skin. A-scan was done for inspection of secondary bonding region. The out of displacement field is visualized by shadow moire system. The strain and vertical displacement are measured by strain gages and L VDT (Linear Variable Differential Transformer). A local buckling is occurred at all grid sections. After that, the final failure is occurred. The strain of side stringer is much less than that of vertical stringer and skin. Due to the side stringer, the local buckling is delayed. Therefore the ratio of the first buckling to failure load is greater than that of vertical stringer stiffened panel.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 제2회 박판성형심포지엄 논문집 박판성형기술의 현재와 미래
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• pp.102-109
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• 1998

In this study, the side panels were developed using the laser-welded Tailored Blanks (TB) with both the same thickness and the different thickness. At first, the formability of the same thickness T.B was investigated to be compared with one of the non welded panel with respect to weldline movements and strain distribution on blank during the stamping. Based on these results, we selected candidates of T.B with different thickness for stamping experiments. That is, we determined the weld line positions and the die step. Then we made some stamping tryouts with selected types of blank designs to investigate the formability of T.B with different thickness. During the tryouts, the wrinkles were found in the a-pillar lower region which is under the deformation mode of the shrink flange. In the b-pillar region, the fractures were found also, these defects have been reduced and corrected by controlling the blank design and the die faces and process pamameters.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.25-26
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• 2023

The internal core material and external color of a sandwich panel have a significant impact on the performance of the sandwich panel. For use on roofs and walls, the internal core material and external color must be considered. Therefore, the surface and back side temperatures were measured for each exterior color and inner core material type. For the internal core materials, urethane foam and Expanded Poly Styrene(EPS), which are core materials mainly used in sandwich panels, were selected. As colors, black and ivory were selected according to brightness, and a total of five colors were selected: red, blue, and green, which are the three primary colors of light. As a result, there were differences in surface and temperature depending on the external color and type of internal core material. Regardless of the color, the temperature was measured lower for panels with urethane foam than for panels with an internal core of EPS. This is believed to have been influenced by the difference in thermal conductivity of urethane foam being 0.023W/(m·K) and that of EPS being 0.032W/(m·K). In addition, panels with a black exterior color were found to have higher surface and back temperatures than panels of other colors, and ivory-colored panels had lower back temperatures regardless of the core material. This is proportional to the brightness and light-absorbing characteristics.

• 동력기계공학회지
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• 제10권4호
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• pp.78-82
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• 2006

Recently, The demands for the reduction of noise generated by transformers have been increasing. Almost all of the noise generated by transformers is a result of magnetostricitive vibration in the core. The noise radiates into the atmosphere from the tank through the insulation oil. As the noise of transformer irritates residents, needs for decreasing the noise of transformer have been arised. One method of reduction such a noise is to build a free-standing enclosure of concrete and steel plates around the transformer. However, this method has some disadvantages. Another method of noise reduction is to mount a close-fitting sound insulation panel on the side of a transformer tank. Side plate vibrations of transformer are transmitted to such a sound insulation panel along two paths. In one case, they are transmitted through air by sound pressure and in the other through supporting structures. In the paper, the vibration and noise effect which is transferred from reinforce channel to insulation panel generated by transformer have been identified for the several kinds of insulation panel and damping sheet analytically and experimetally.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.85-96
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• 1996

Most protection systems such as seat belts and airbags are not effective means for side structure. There has been significant effort in the automobile industries in seeking other protective methods, such as stiffer structure and padding on the door inner panel. Therefore, a car-to-car side impact model has been developed using ATB occupant simulation program and validated for test data of the vehicle. Compared to the existing side impact models, the developed model has a more detailed vehicle side structure representation for the more realistic impact response of the door. This model include impact bar which effectively increases the side structure stiffness without reduction of space between the occupant and the door and padding for absorbing impact energy. The established model is applied to a 4-door vehicle. The parameter study indicated that a stiffer impact bar would reduce both the acceleration-based criteria, such as thoracic trauma index: TTI(d), and deformation-based criteria, such as viscous criterion(VC). Padding on the door inner panel would reduce TTI(d) while VC gives the opposite indication in a specified thickness range. For a 4-door vehicle, the stiffness enhancement of B-pillar is more beneficial than that of A-pillar for occupant injury severity indices.

• Structural Engineering and Mechanics
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• 제6권2호
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• pp.125-141
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• 1998

Recent test results of steel moment connections repaired with a haunch on the bottom side of the beam have been shown to be a very promising solution to enhancing the seismic performance of steel moment-resisting frames. Yet, little is known about the effects of using such a repair scheme on the global seismic response of structures. When haunches are incorporated in a steel moment frame, the response prediction is complicated by the presence of "dual" panel zones. To investigate the effects of a repair on seismic performance, a case study was conducted for a 13-story steel frame damaged during the 1994 Northridge earthquake. It was assumed that only those locations with reported damage would be repaired with haunches. A new analytical modeling technique for the dual panel zone developed by the author was incorporated in the analysis. Modeling the dual panel zone was among the most significant consideration in the analyses. Both the inelastic static and dynamic analyses did not indicate detrimental side effects resulting from the repair. As a result of the increased strength in dual panel zones, yielding in these locations were eliminated and larger plastic rotation demand occurred in the beams next to the shallow end of the haunches. Nevertheless, the beam plastic rotation demand produced by the Sylmar record of 1994 Northridge earthquake was still limited to 0.017 radians. The repair resulted in a minor increase in earthquake energy input. In the original structure, the panel zones should dissipate about 80% (for the Oxnard record) and 70% (for the Sylmar record) of the absorbed energy, assuming no brittle failure of moment connections. After repair, the energy dissipated in the panel zones and beams were about equal.

• Journal of the Korean Data and Information Science Society
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• 제19권2호
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• pp.559-568
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• 2008

This paper analyzes Korean residential tenure choice for house which is the most important in Korean households' assets. Data used in the analysis is the data of Korean Labor and Income Panel Study for the period from 1998 to 2006 and with 2341 households. In this paper, a household chooses a housing tenure mode, either by renting or by owing house. We use a mixed-logit panel model as an estimation model to take into consideration household's heteroscedasticity of preference in tenure choice. It turns out that the heteroscedasticity is significant in households' tenure choice behavior, implying that Korean housing policy emphasizing supply side should consider the demand side.

• 한국정밀공학회지
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• 제22권5호
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• pp.113-120
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• 2005

Because of the turbulent markets and the increasing demand on product quality, the application of new technology to practice is increasingly important. In case of automotive industries, they take interest in laser welding to solve these problems because laser welding has many advantages such as good accessibility, welding quality, fast welding speed and so on. To apply this technology to welding of car body, the data of laser welding are collected through lots of the experiment according to the material, geometry and layer number of welding points. Based on the experiment results and the information of product, i.e. the car side panel, the clustering of stitches for laser welding was carried out and the optimal equipments are selected through the comparison between the requirements of welding and the potential of equipments. Using these results, laser welding cell for the car side panel are configured with the concept of the digital manufacturing, which ensures maximum planning security with visualization and simulation. Finally, the optimal laser welding cell is chosen by the evaluation of alternative cells with assessment criteria.