• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.84-92
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• 2012

Anchorage zone in prestressed concrete cable stayed bridges is very important area due to the more accurate analysis is needed to estimate the behavior. In the study, since the cable anchorage zone in the prestressed concrete cable-stayed bridge is subject to a large amount of concentrated tendon forces, it shows very complicated stress distributions and causes a serious local cracks. Accordingly, It is necessary to investigate the parameters of affecting the stress properties, such as the cable inclination, the position of anchor plate, the modeling method and the three dimensional effect. The tensile stress distribution of anchorage zone is compared to the actual design condition by varing the stiffness of spring element in the local modeling and an appropriate position of anchor plate is determined. These results would be elementary data to the stress state of anchorage zone and more efficient design.

• International journal of steel structures
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• v.18 no.5
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• pp.1589-1597
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• 2018

Fatigue tests and numerical analysis were carried out to evaluate the fatigue performance at the U-rib to deck welded joint in steel box girder. Twenty specimens were tested corresponding to different penetration rates (80 and 100%) under fatigue bending load, and the fatigue strength was investigated based on hot spot stress (HSS) method. The detailed stress distribution at U-rib to deck welded joint was analyzed by the finite element method, as well as the stress intensity factor of weld root. The test results show that the specimens with fully penetration rate have longer crack propagation life due to the welding geometry, resulting in higher fatigue failure strength. The classification of FAT-90 is reasonable for evaluating fatigue strength by HSS method. The penetration rate has effect on crack propagation angle near the surface, and the 1-mm stress below weld toe and root approves to be more suitable for fatigue stress assessment, because of its high sensitivity to weld geometry than HSS.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.5
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• pp.169-178
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• 2008

Compressive flanges of steel box girder is designed based on the ultimate strength behavior of sub-panel which is enclosed with longitudinal stiffeners and transverse stiffeners on appropriate safety factor. However, it is rational that the ultimate strength is calculated considering the various factors such as number and stiffness of longitudinal stiffener, spacing of transverse stiffener, initial deformation and residual stress distribution. In this study, an analysis program based on Folded Plate theory is developed considering the geometric effects and the material nonlinearity. The analysis program is applicated to the steel box girder bridges which is really constructed in domestic.

• Journal of the Korean Dietetic Association
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• v.26 no.4
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• pp.243-253
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• 2020

The purpose of this study was to set new guidelines for adenosine triphosphate (ATP) bioluminescence hygiene monitoring of distribution trays at children's foodservices. Five dietitians visited 223 foodservices (95 institutional, 128 small) to examine whether they adhered to the norms of 'Keeping distribution tray sanitary by washing/sanitizing' and 'Performing food distribution in a clean and appropriate way'. In this visit, dietitians swabbed 100 ㎠ area of the distribution trays twice, once for obtaining ATP measurements and the second time for Aerobic Plate Counts (APC) using 3M Petrifilm Plates. Chi-square test and ANOVA were applied using SPSS 23.0 software. SPSS 23.0 was used to conduct graphical and statistical analysis of the raw data of ATP measurements, which were further transformed by a Box-Cox transformation. The mean of APC from all the subjects inspected was 3.8×10²±2,102.0 CFU/100 ㎠. A total of 208 (93.3%) trays were observed within the acceptable limits of APC (Pass<5.0×10² CFU/100 ㎠). APCs taken at institutional foodservices showed significantly lower levels (1.4×10²±600.0 CFU/100 ㎠, P<0.01) compared to the small foodservices (5.5×10²±2,718.7 CFU/100 ㎠). No significant differences were observed between the two groups in ATP measurements and in the performance rate of 2 checklist items. As against the 93.3% APC adequacy from the total subjected inspection, total ATP adequacy (Pass≤300 RLU/100 ㎠) was only 71.7%. Therefore, more practical guidelines should be prepared for the assessment of the hygiene of distribution trays. In the graphical and statistical analysis, levels below 250 RLU/100 ㎠ was considered 'Pass', while equal to or greater than 350 RLU/100 ㎠ was considered 'Fail' for distribution trays.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.737-749
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• 2007

Flexural design of double composite box girder over the interior pier for three-span continuous bridge was performed by the LRFD method. The maximum span length of the continuous bridge ranged from 80m to 120m and the relative ratio of the span length was assumed to be 1:1.25:1. The girder section was designed for the strength limit state and service limit state with additional design check for constructibility. Before the bottom concrete and compression flange showed a complete composite action, the buckling of lower compression flange was checked. The flexural stiffness and flexural resistance characteristics for the section and for the constituent members such as tension flange, compression flange, and web were analyzed for different thicknesses of the bottom concrete on top of the compression flange. The effect of the distribution ratio of steel between the top and bottom flanges was investigated by analyzing ductility behavior and stress distribution through the girder's depth for several different relative area ratios of steel between the top and bottom flanges. It was found that a total amount of 15% of steel can be saved by applying the double composite system compared with that of the conventional composite system.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.15 no.3
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• pp.83-91
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• 2009

It is very difficult to export the fresh agricultural products to long distance countries such as USA and EU without any damage. Fresh products exporting would overcome very severe conditions such as hot and cold weather changes, heavy vibrations with rolling and pitching during the target distribution period, therefore, the packaging needs the immobility of products in the container and the keeping its quality by packaging materials or methods under any surrounding environments, especially. The physical strength of outer box should be designated according to its own characteristics for agricultural product packaging. Packaging dimension which would be fit to standard pallet is also very important factor to reduce the distribution cost. There have been many agricultural products researches for export packaging to the USA so far. However they have never got desirable results which enough to apply it in real. The main purpose of this research is to develop optimum compressive strength and optimum dimension of corrugated fiberboard box which would be used to USA export packaging of fresh melon as well as Japan.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.2
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• pp.113-122
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• 2007

In this study, uranium migration experiments have been performed using a natural groundwater and a granite core with natural fractures in a glove-box constructed to simulate an appropriate subsurface environment. Groundwater flow experiments using the non-sorbing anionic tracer Br were carried out to analyze the flow properties of groundwater through the fracture of the granite core. The result of the uranium migration experiment showed a breakthrough curve similar to that of the non-sorting Br. This result may imply that uranium migrates as anionic complexes through the rock fracture since uranium can form carbonate complexes at a given groundwater condition. The distribution coefficient $K_d$ of the uranium between the groundwater and the fracture filling material was obtained as low as 2.7 mL/g from a batch sorption experiment. This result agrees well with the result from the migration experiment, showing a faster elution of the uranium through the rock fracture. In order to analyze retardation properties of the uranium through the rock fracture, the retardation factor $R_d({\sim}16.2)$ was obtained by using the $K_d$ obtained from the batch sorption experiment and it was compared with the $R_d({\sim}14.3)$ obtained by using the result from the uranium migration experiment. The values obtained from the both experiments were very similar to each other. This reveals that the retardation of the uranium is mainly occurred by the fracture filling material when the uranium migrates through the fracture of a granite core.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.140-145
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• 2012

The purpose of this study is to understand the change of impression by comparing the uniformity lighting with the compound lighting. In previous study, we proposed a light controlling method to harmonize daylight from a window and artificial lights from a ceiling and obtained the results to support our method. We referred this method as the Adjusted Compound-Lighting Model (AC Model). The model claims that lighting in a room with a side-window are perceived as harmonious when the overall light distribution in the room is well approximated by a compound of lights from the window and the entire ceiling. The experiment is carried out with the scaled-models and mock-up spaces that were supposed to be an office space. One is lit by the uniform lighting and the other by the compound lighting in each experimental space. In order to present varying illuminance distributions, thetwo variables were used in this study. One was the ratio of thelight from the window and ceiling in the standard and evaluation box. The standard box was provided by the ratio of 20% to 40% from the window and 80% to 60% from the ceiling as two lighting ratio patterns [Wu20(=Cu80) and Wu40(=Cu60)]. And the evaluation box was provided by the light ratio of 0% to 40 from the window and 100% to 60% from the ceiling [Wcp0(=Ccp100), Wcp20(=Ccp80) and Wcp40(=Ccp60)]. The other variable was themean illuminance level in both boxes. Two level of mean illuminance (700lx and 300lx) were used in this experiment. Each lighting condition was established at equal horizontal mean illuminance level, held constant near 700lx or 300lx in both boxes. Both of them were similar in the shape of distribution when there were same ratios of lights from the window and the ceiling. Subjects were asked to evaluate the point of difference by semantic differential rating on their overall impression after comparing with two rooms. The results showed that the impressions of compound lighting were more positive score than that of uniformity lighting on the items of 'dim-bright', 'dislike-like', 'artificial-natural' and 'closed-open', and that there was no significant difference in impressions between two spaces on other items.

• Food Engineering Progress
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• v.14 no.2
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• pp.106-111
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• 2010

In this study, we performed corrugation fluting experiments to examine the relationship between high-low corrugation of a corrugated medium and compressive strength of corrugated containers for food packaging. A low-grade corrugated medium was found to suffer from weak tensile resistance and to be prone to stealing, which tends to produce low corrugation. In contrast, a medium with a large corrugation deviation often caused slimming during fluting and produced irregular corrugations. Experiments of high-low corrugation distribution according to corrugated medium grades indicate that a high grade medium shows a smaller ratio of low corrugation. The thickness of corrugated fiberboard is weakly correlated to the basis weight of medium, yet positively correlated to the medium thickness (y=3.9732x+4.2712, $R^{2}=0.8142$) and inversely proportional to the medium density (y=-3.1213x+6.8736, $R^{2}=0.9919$). Compressive strength of a corrugated fiberboard box is low, if made of corrugated medium with large low corrugation distribution. Compressive strength showed 13% variation with respect to medium grades and 21% variation for various test samples. The corrugation fluting of a corrugated medium is related to physical properties such as basis thickness and density.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.24-31
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• 2019

In this study, we analyzed the cause of the burn out phenomenon in the power distribution system for aircraft and proposed the improvement method. The power distribution device for aircraft has an AC and DC, and there is a rectifier between the two devices. The capacitors in the power board burn out when the power is turned on and off. The main reason for this is the excessive voltage caused by the inductance built into the rectifier. The cases that can cause a failure are classified. The impact was analyzed and the solution was established through the experimental method.