• Food Science and Preservation
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• v.10 no.3
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• pp.297-301
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• 2003

The hardness of corrugated packaging box decreased during storage period because of high humidity. Therefore, the strength-decreasing factor of corrugated packaging box had to be investigated to determine the compression strength of the corrugated packaging box. This study was conducted to define the characteristics of moisture absorption as well as compression strength of corrugated fiberboard. (1) The moisture content of the corrugated fiberboard was rarely influenced by the kinds of raw materials and water repellent. However, the moisture adsorption of the corrugated fiberboard was shown to be clearly affected by air temperature changes. (2) The moisture content of the corrugated fiberboard was significantly affected by relative humidity. The moisture adsorption of corrugated fiberboard was also greatly influenced by composition of raw materials rather than water repellent. The results indicated that the improvement of raw materials was more effective than the increase of water repellent of corrugated fiberboard to reduce the moisture adsorption of the corrugated fiberboard. (3) The vertical compression strength was significantly decreased with increasing relative humidity. The reduction rate of vertical compression strength was not charged with the increase of relative humidity, which was regardless of kinds of corrugated fiberboard. (4) For improving the strength of the corrugated packaging box, new technique should be found to develop better quality of raw materials. Moreover, the physical construction of corrugated packaging box should be clearly understood because the corrugated packaging box for the agricultural products was usually used for the circumstances of high humidity and low air temperature

• Progress in Superconductivity and Cryogenics
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• v.15 no.4
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• pp.6-9
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• 2013

Korea Superconducting Tokamak Advanced Research (KSTAR) has a helium refrigeration system (HRS) with the cooling capacity of 9 kW at 4.5 K. Main cold components are composed of 300 tons of superconducting (SC) magnets, main cryostat thermal shields, and SC current feeder system. The HRS comprises six gas storage tanks, a liquid nitrogen tank, the room temperature compression sector, the cold box (C/B), the 1st stage helium distribution box (DB#1), the PLC base local control system interconnected to central control tower and so on. Between HRS and cold components, there's another distribution box (DB#2) nearby the KSTAR device. The entire KSTAR device was constructed in 2007 and has been operated since 2008. This paper will present the maintenance result of the KSTAR HRS during the campaign and discuss the operation record and maintenance history of the KSTAR HRS.

• Geomechanics and Engineering
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• v.35 no.5
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• pp.475-486
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• 2023

Ballast particles have an irregular shape and are discrete in nature. Due to the discrete nature of ballast, it exhibits complex mechanical behaviour under loading conditions. The discrete element method (DEM) can model the behaviour of discrete particles under a multitude of loading conditions. DEM is used in this paper to simulate a series of three-dimensional direct shear tests in order to investigate the shear behaviour of railway ballast and its interaction at the microscopic level. Particle flow code in three dimension (PFC3D) models the irregular shape of ballast particles as clump particles. To investigate the influence of particle size distribution (PSD), real PSD of Indian railway ballast specification IRS:GE:1:2004, China high-speed rail (HSR) and French rail specifications are generated. PFC3D built-in linear contact model is used to simulate the interaction of ballast particles under various normal stresses, shearing rate and shear box sizes. The results indicate how shear resistance and volumetric changes in ballast assembly are affected by normal stress, shearing rate, PSD and shear box size. In addition to macroscopic behaviour, DEM represents the microscopic behaviour of ballast particles in the form of particle displacement at different stages of the shearing process.

• Structural Engineering and Mechanics
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• v.73 no.2
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• pp.167-179
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• 2020

This study provides a simplified method for the evaluation of shear lag stress in rectangular box T-joints. The occurrence of shear lag phenomenon in the box T-joint generates stress concentration localized at both web-flange junctions of the beam, which leads to cracking or failure in the weld region of the joint. To prevent such critical circumstance, peak stress at the weld region is required to be checked during a preliminary design stage. In this paper, the shear lag stresses in the T-joints were evaluated using least-work solution in which the longitudinal displacements of the beam flange and web were presumed. The evaluation process considered particularly the effect of column flange flexibility, which was represented by an axial spring model, on the shear lag stress distribution. A simplified method for stress evaluation was provided to avoid solving complex mathematical problems using a stress modification factor β_s from a parametric study. The results showed that the proposed method was valid for predicting the shear lag stress in the box T-joints manually, as well compared with finite element results. The results are further summarized, discussed, and clarified that more flexible column flange caused higher stress concentration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.11
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• pp.1669-1676
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• 1993

In this paper, a thin-straight monopole antenna attached to a conducting box is analyzed using a moment method with the pocklington integral expression for the exact Green's function. A modeling of a conducting box is based on a Wire-Grid method for an efficient calculation procedure. A system of linear equation is obtained using the piecewise sinusoidal basis function. And a Junction basis function is enforcing to represent the physical current on the edge of the conducting box. Especially, the junction basis functions are overlapped for the current continuity preserving on the vertexes. Numerical results are obtained for the current distribution on the unified antenna/conducting box system, input impedance and radiation pattern. The results are compared with the known data.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.557-564
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• 2002

Corrugated board is an efficient low-cost structure material fur the boxes that are widely used for transporting, storing and distributing goods. Corrugated board is also considered as an orthotropic because the principal material directions are the same as in paperboard. The purpose of this study was to elucidate the principal design parameters of ventilating box through the FEA on the various types of ventilating hole. From the viewpoint of the stress distribution and stress level, the optimum pattern and location of the ventilating hole were vertically oblong, and symmetry position with a short distance to the right and left from the center of front and rear panel. And, the optimum location and pattern of hand hole were a short distance to the top from the center of both side panels, and modified shape to increase the radius of curvature of both side in horizontal oblong. In general, the optimum pattern and location of both the ventilating hole and hand hole based on the FEM analysis were well verified by experimental investigation. It is suggested that decrease in compressive strength of the box could be minimized in the same ventilating hole area under the condition of the length of major axis of ventilating hole is less than 1/4 of box length, the ratio of minor axis/major axis is 113.5∼l/2.5, and number of the ventilating holes is even and symmetrical.

• Structural Engineering and Mechanics
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• v.48 no.3
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• pp.395-414
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• 2013

The present study fundamentally investigated the mechanical performance of the rib-stiffened super-wide bridge deck with twin box girders in concrete, which is a very popular application to efficiently widen the bridges with normal span. The shear lag effects of the specific cross-sections were firstly studied. The spatial stress distribution and local stiffness of the bridge deck with twin box girders were then investigated under several typical wheel load conditions. Meanwhile, a comparative study for the bridge deck with and without stiffening ribs was also carried out during the investigation; thereby, a design optimization for the stiffening ribs was further suggested. Finally, aiming at the preliminary design, an approximate methodology to manually calculate the bending moments of the rib-stiffened bridge deck was analytically proposed for engineers to quickly assess its performance. This rib-stiffened bridge deck with twin box girders can be widely applied for concrete (especially concrete cable-stayed) bridges with normal span, however, requiring a super-wide bridge width due to the traffic flow.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.20-27
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• 2005

Solar radiation causes non-uniform temperature distribution in the structure, depending on the shape of the structure and its shadows. Especially in cases of curved steel box girder bridges, non-uniform temperature distribution due to solar radiation can reduce bridge life and serviceability when combined with another load combination. In this study, the method for predicting the temperature distribution of curved bridges developed by Kim et al., was used to predict the non-uniform temperature distribution which served as a basis for structural analysis of 3-D bridge behavior. In order to seek the most unfavorable conditions of solar radiation, observation data from the Korea Meteorological Administration for solar radiation were analyzed. The region of the most high solar radiation condition was selected and its one year variation of the solar radiation data was considered. From this analysis, the most unfavorable solar radiation condition with lower solar altitude and intense solar radiation was selected. Based on the selected solar radiation condition, structural behavior of curved bridges with diverse bridge direction, span length, radius and support conditions are analyzed.

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.240-244
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• 2000

The three-dimensional orientation distribution function of a conical shaped tungsten liner prepared by the thermo-mechanical forming process was analyzed by 1.525$\AA$ neutrons to carry out the Rietveld refinement. The pole figure data of three reflections, (110)(220) and (211) were measured. The orientation distribution functions for the normal and radial directions were calculated by the WIMV method. The inverse pole figures of the normal and radial directions were obtained from their orientation distribution functions. The Rietveld refinement was performed with the RIETAN program that was slightly modified for the description of preferred orientation effect. We could successfully do the Rietveld refinement of the strongly textured tungsten liner by applying the pole density of each reflection obtained from the inverse pole figure to the calculated diffraction pattern. The correction method of preferred orientation effect based on the inverse pole figures showed a good improvement over the semi-empirical texture correction based on the direct usage of simple empirical functions.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.8 no.1
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• pp.11-14
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• 2002

Packaging and distribution status of watermelon Korean markets; Chunanm and Chunbuk, Kyungnam and Kyungbuk from January, 1999 to December, 1999 was surveyed to shipping methods, quality. Distribution and marketing of watermelon was different to the producing area, and quality of it was four grade. In a grade, difference of weight was 86%, and that of soluble solid content was 130%. Packaging status was almost non-pack, in case of packaging, packaging material was corrugated fiberboard and wooden-collar box, and packaging unit was mainly used to 8 to 10kg box, for one head or 4 heads was a few.