• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.479-482
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• 2005

The concrete box girder members are extensively used as a superstructure in bridge construction. The load carrying capacity of concrete box girders in lateral direction is generally influenced by the sizes of haunch and web. The internal upper decks are restrained by the webs and exhibit strength enhancement due to the development of aching action. The current codes do not have generally consider the arching action of deck slab in the design because of complexity of the behavior. However, there are significant benefits in utilizing the effects of arching action in the design of concrete members. The main objective of this paper is to propose a rational method to predict the ultimate load of deck slab by considering various haunch sizes and web restraint effect of concrete box girder bridges. To this end, a comprehensive experimental program has been set up and seven large-scale concrete box girders have been tested. A transverse analysis model of concrete box girders with haunches is proposed and compared with test data. The results of present study indicate that the ultimate strength is significantly affected by haunch dimension. The increase of strength due to concrete arcing action is reduced with an increase of prestressing steel ratio in laterally prestressed concrete box girders and increases with a larger haunch dimension. The proposed theory allows more realistic prediction of lateral ultimate strength for rational design of actual concrete box girder bridges.

• Structural Engineering and Mechanics
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• v.55 no.5
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• pp.953-964
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• 2015

A model has been proposed that can predict the ultimate torsional strength of single-box multi-cell reinforced concrete box girder under combined loading of bending, shear and torsion. Compared with the single-cell box girder, this model takes the influence of inner webs on the distribution of shear flow into account. According to the softening truss theory and thin walled tube theory, a failure criterion is presented and a ultimate torsional strength calculating procedure is established for single-box multi-cell reinforced concrete box girder under combined actions, which considers the effect of tensile stress among the concrete cracks, Mohr stress compatibility and the softened constitutive law of concrete. In this paper the computer program is also compiled to speed up the calculation. The model has been validated by comparing the predicted and experimental members loaded under torsion combined with different ratios of bending and shear. The theoretical torsional strength was in good agreement with the experimental results.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.69-77
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• 2007

Carton and corrugated paperboard have excellent convertibility characteristics that could be easily slitted, folded, and inserted to become a certain shape of box or case. This excellent processing characteristics of carton and corrugated paperboard as well as their recyclability will continue to make them possess high portion in packaging markets. However, staple, tape, or adhesive have been used to seal a paperboard packaging box or case. Staples among them have been frequently used in many cases because of their convenience. Staples could enter the inside the box and give wounds to the goods in the box or case. Furthermore additional handling and waste treatment costs in the making and recycling processes would be necessary when staple is used to seal box or case. This study has been carried out to develop non-staple paperboard packaging box & case designs that can be used to make non-staple boxes & cases. It is believed that the non-staple folding paperboard boxes & cases could be more environmental-friendly, beautiful, and economic than staple boxes & cases.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.997-1010
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• 2017

The black box model is a relatively new option for nonlinear dynamic system identification. It can be used for prediction problems just based on analyzing the input and output data without considering the changes of the internal structure. In this paper, a black box model was presented to solve unconstrained overlying strata movement problems in coal mine production. Based on the black box theory, the overlying strata regional system was viewed as a "black box", and the black box model on overburden strata movement was established. Then, the rock mechanical properties and the mining thickness and mined-out section area were selected as the subject and object respectively, and the influences of coal mining on the overburden regional system were discussed. Finally, a corrected method for height prediction of the fractured zone was obtained. According to actual mine geological conditions, the measured geological data were introduced into the black box model of overlying strata movement for height calculation, and the fractured zone height was determined as 40.36 m, which was comparable to the actual height value (43.91 m) of the fractured zone detected by Double-block Leak Hunting in Drill. By comparing the calculation result and actual surface subsidence value, it can be concluded that the proposed model is adaptable for height prediction of the fractured zone.

• Wind and Structures
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• v.32 no.4
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• pp.293-308
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• 2021

For the past three decades a significant amount of research has been conducted on bridge flutter. Wind tunnel tests for a 2000 m class twin-box suspension bridge have revealed that a twin-box deck carrying 4 m tall 50% open area ratio wind screens at the deck edges achieved higher critical wind speeds for onset of flutter than a similar deck without wind screens. A result at odds with the well-known behavior for the mono-box deck. The wind tunnel tests also revealed that the critical flutter wind speed increased if the bridge deck assumed a nose-up twist relative to horizontal when exposed to high wind speeds - a phenomenon termed the "nose-up" effect. Static wind tunnel tests of this twin-box cross section revealed a positive moment coefficient at 0° angle of attack as well as a positive moment slope, ensuring that the elastically supported deck would always meet the mean wind flow at ever increasing mean angles of attack for increasing wind speeds. The aerodynamic action of the wind screens on the twin-box bridge girder is believed to create the observed nose-up aerodynamic moment at 0° angle of attack. The present paper reviews the findings of the wind tunnel tests with a view to gain physical insight into the "nose-up" effect and to establish a theoretical model based on numerical simulations allowing flutter predictions for the twin-box bridge girder.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.22-28
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• 2017

According to the National Fire Data System (NFDS), more than 5,000 vehicle fires have occurred every year for the last 10 years. Vehicle fires are primarily caused by mechanical (breaking system and engine), electrical (wiring and battery), and chemical (oil and fuel gas leakage) problems. The electrical factor has increased with the installation of driver convenience equipment. For example, today, the black box is widely used to provide video data recording of motor vehicle accidents. The black box consists of a front camera, rear camera, and wires. The black box wires are directly connected to the junction box or fuse box from the start battery that operates to provide normal on power supplying for engine stop. It is extremely dangerous when the wires short circuit due to insulation aging, mechanical and electrical stress, etc. In this study, the black box wiring fire risk have been analyzed and investigated when the steady state and abnormal operations, and under the following conditions: wiring arrangements with a high temperature condition, insulation aging, poor contact, and short circuits. The results showed that black box wiring short circuits had a higher fire risk than the other fire hazard elements. To prevent fire hazards caused by black box wiring, the black boxes must be installed by qualified service personnel. Do not modify the wiring, remove the fuse and secure the wiring using cable ties or insulation tape.

• Food Science and Preservation
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• v.10 no.1
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• pp.23-27
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• 2003

This study was conducted to develop the corrugated fiberboard box which is suitable to pre-cooling and low temperature distribution of chinese cabbage Consider from a cooling performance viewpoint, the folding type box with 5.4% vent hole ratio was most efficient for fast cooling and even temperature distribution in the packaging box. At the end of storage periods, the compressive strength of the folding type box was less than the bliss type box. However, the compressive strength of the folding type box after storage was higher than required safety compressive strength for long term storage. So the folding type box was considered to have no problems toy practical use. The shelf-life of the chinese cabbage packaged with the developed box was 6∼7 days which was 2∼3 days longer than usual packaging.

• Journal of the Korean earth science society
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• v.31 no.3
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• pp.246-258
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• 2010

A convective circulation box was redesigned after analyzing reasons why adolescent elementary school students could not derive a convective circulation concept from the convection circulation box experiments. Even though students were in the formal operational period of Piaget, the adolescents felt difficult to understand a concept of the natural phenomena they have never seen before. Thus, we designed a method to help students increase their scientific understandings about the concept through developing a miniature convective circulation box. Findings indicated that an application of redesigned convective circulation box in the classroom experiment significantly increased the students' understanding about the convective circulations of land and sea breezes, and as well as their participation in the activities. In addition, the redesigned convective circulation box motivated students to develop their scientific thinking skills by allowing them to decide where to put visible incenses inside the box and to directly observe the smoke currents circulation formed accordingly. Redesigning and using a convective circulationbox as a miniature of natural phenomenon helps students avoid having misconceptions. The biggest merits of the box are that it is observable in all directions, it provides much clearer convective circulations comparing to the extant box, and it requires low production costs.

• Food Science and Preservation
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• v.6 no.3
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• pp.255-259
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• 1999

This study was measured weight loss, total ascorbic acids, titratable acidity and soluble solids contents to investigate the effect of EPS(expended polystrene foam) box, double wall corrugated paperboard box and LDPE film pouches during storage at 25oC. The rate of weight loss was 5.9% in corrugated paperboard box after 7 days, but those of 20LD, 40LD film and EPS box were 1.1, 1.0, and 1.1% , respectively. Total ascorbic acid content of EPS box was 20% higher than that in corrugated paperboard box, but the obvious differents were not observed among the LDPE film pouches and EPS box. The titratable acidity was decrease during storage, but total soluble solids content was increase. Overall appearences of LDPE pouches and EPS box were better than those of corrugated paperboard box.

• Food Science and Preservation
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• v.6 no.3
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• pp.260-263
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• 1999

This study was measured weight loss, total ascorbic acids, titratable acidity and soluble solids contents to investigate the effect of EPS(expended polystyrene foam) box. double wall corrugated paperboard box and LDPE film pouches during storage at 25$^{\circ}C$. The rate of weight loss was 5.7% in corrugated paperboard box after 10 days. but those of 20LD, 40LD film and EPS box were 1.0, 0.8, and 0.9%, respectively. Total ascorbic acid content and titratable acidity of EPS box was 15.0% and 24.4% higher than that in corrugated paperboard box, but the obvious differents were not observed among the LDPE film pouches and EPS box. The titratable acidity was decrease during storage, but total soluble solids content was slightly increase. Overall appearences of LDPE pouches and EPS box were boner than those of corrugated paperboard box.