• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.2
• /
• pp.88-97
• /
• 2011

For Korean design provisions are not equipped for skewed steel box girder bridges, when American provisions are adopted, load distribution factors different from real behavior are determinated. Furthermore the possibility of over or under estimated bridge design involves. The aim of this study is to provide more rational load distribution factor formulas based on real behavior for shear at obtuse corner of skewed steel box girder bridges. In order to accomplish the aim finite element analysis for a variety of skewed steel box girder bridge structural models is carried out, and each parameters degree of influence on wheel load distribution factors of skewed steel box girder bridges are analyzed. Then multiple regression analysis is fulfilled in order to propose formulas for determinating shear force load distribution factor of skewed steel box girder bridges.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.1
• /
• pp.9-14
• /
• 2008

In the case of horizontally curved bridges, the use of curved composite box girder bridges are increased due to its functionality and for aesthetical reason. As it compared with the open section, the steel box girder bridges have advantages to resistant of distortion and corrosion. In practice the grid analysis is conducted by utilizing only the cross beam. Since the stiffness of the concrete slab is not included in the grid analysis, the cross beam is induced the distribution of the live load. In this study the affects of the radius of curvature, the number of diaphragm and cross beam to the load distribution of the curved steel box girder bridge was investigated by applying the finite element method. The results indicate that the curvature of curved bridge had a large affect of the load distribution and as the curvature was increased the load distribution factor was increased. A single diaphragm at the center of girder is important role for the load distribution effects and structural stability, but additional diaphragm did not affect it as much. The affects of the cross beam to the load distribution were investigated and its influence was minor. It can be safely concluded that the addition of cross beam does not aid the purpose of the live load distribution. And the stiffness of concrete slab for the load distribution effects should be concerned in the design of curved steel box girder bridges.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.13 no.4 s.56
• /
• pp.148-158
• /
• 2009

Firstly the problems of existing foreign code concerning wheel load distribution factor for skew box girder bridges have been examined, and the main parameters which have effects on wheel load distribution factors are evaluated in this study. Further finite element analyses on various skew steel box girder bridges are carried out. Based on the analysis results, formulas to determine wheel load distribution factors are proposed using multiple regression analysis. It is found when using the proposed formulas in this study weak points of existing specifications could be improved and also time spent at structural analysis should be saved a lot, so that the validity and practicality could be verified.

• Korean Journal of Food Science and Technology
• /
• v.20 no.6
• /
• pp.845-849
• /
• 1988

A laboratory scale storage facility consisting of a cold room, sample jars and a ventilation device was designed and built. Storaging sample jars (1.7 l) for fruit were fabricated with transparent acryl and provided with a constant air flow. For the supplying of air to sample jars, the air distributing system was built with solenoid valves, an air precooling coil and a pressure equalizing tank. To provide the programmable storaging environment of the facility a microprocessor-based controller was designed and installed. The controller was built with the 8 bit microprocessor (Z-80), EPROM, RAM, programmable peripheral interface(8255 PPI), and A/D converter. Softwares for the auto-temperature measurement and control of the storage system were developed and systemized in ROM. The automated storage system was applied to citrus storage, and the temperature of the storage facilities was successfully acquisited to the computer and controlled.

• Journal of Korean Society of Steel Construction
• /
• v.15 no.5 s.66
• /
• pp.489-497
• /
• 2003

Bridge has to be long-spanned and of simple structure, considering the social environment. As a result of this trend in bridge construction, it is important for the sake of economical efficiency to improve the structural system and increase the life cycle of a bridge. To attain these goals in constructing a steel bridge, the detail analyses based on real structure must be performed. In the steel structure bridge, the parts that are a main focus of interest are the diaphragm and the vertical bracing of the steel box girder support. This study observed the behavior of the diaphragms on the bearings of a closed section steel box girder bridge support, as dead load was increased. Stress variation of the support diaphragms in a steel box girder was considered, and both experimental test and structural analyses were performed to verify the behavior of a composite steel box girder bridge under repair or maintenance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.1
• /
• pp.7-16
• /
• 2006

Both the computational and experimental analysis have been conducted in this study to develop the high efficiency agriculture products dryer by the uniform thermal flow distribution in the drying room. It has been developed based on the results of the computation and experiment in the conventional dryer to improve the thermal flow distribution in drying room. The developed dryer can be prevented the local concentration of the heated wind and achieved the uniform flow distribution using the installation of vertical branch ducts, ribs, guide vanes and porous plates. As a result, the developed dryer reduced the fuel consumption up to $15\%$ and the electricity consumption up to $31.5\%$ compared with the conventional dryer.

• School Mathematics
• /
• v.7 no.2
• /
• pp.123-137
• /
• 2005

Elementary combinatorial problem may be classified into three different combinatorial models(selection, distribution, partition). The main goal of this research is to determine the effect of type of combinatorial operation and implicit combinatorial model on problem difficulty. We also classified errors in the understanding combinatorial problem into error of order, repetition, permutation with repetition, confusing the type of object and cell, partition. The analysis of variance of answers from 339 students showed the influence of the implicit combinatorial model and types of combinatorial operations. As a result of clinical interviews, we particularly noticed that some students were not able to transfer the definition of combinatorial operation when changing the problem to a different combinatorial model. Moreover, we have analysed textbooks, and we have found that the exercises in these textbooks don't have various types of problems. Therefore when organizing the teaching , it is necessary to pose various types of problems and to emphasize the transition of combinatorial problem into the different models.

• Environmental and Resource Economics Review
• /
• v.27 no.4
• /
• pp.725-743
• /
• 2018

Industrial groups (representing the polluters) and environmental non-governmental organizations (representing the victims) respond differently to various environmental policy instruments. As the affected group's power is large either politically or economically, it is unlikely that a single instrument will be actually selected despite being effective or efficient because of the high political costs associated with it. In this paper, we focus on the political role that energy subsidies play in creating a compromise between energy consuming polluters and victims of pollution. The use of a Dolbear (1967)'s triangle Edgeworth box model makes it possible to examine how policy selection affects the income distribution and welfare levels of two groups. The effects of a single policy instrument of either direct regulation or tax are compared with those of a policy mix that includes energy subsidies. We found that the addition of energy subsidies would increase the chance of compromise between polluters and victims.

• Korean journal of applied entomology
• /
• v.61 no.4
• /
• pp.657-658
• /
• 2022

This study was conducted to identify methods to improve the emergence rate of Aphidius spp. in agricultural fields. The emergence rates of Aphidius colemani released into agricultural fields were 37.2%, 54.4% under 'sun blind' conditions, and 63.1% in the group in which shade and moisture were provided. Provision of shade and moisture upon introduction of Aphidius spp., can increase adult emergence 1.69 times more relative to a control group.