• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.85-90
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• 2015

In this study, the life evaluation due to the structural configuration of bumper attached at the front side of ATV vehicle is studied on the basis of fatigue analysis. As the purpose of this study, the characteristic of bumper exposed on the repetitive loading condition like the vibration is understood. The position of crack happened at the fatigue situation is grasped in advance and complemented in advance. It is considered that the multipurpose vehicle is designed to not be driven on the paved general road but the rough road like the unpaved load. And the weak part of bumper is understood through the study of life evaluation on this driving environment. The durability can be improved by doing the safe design of automotive bumper on the basis of the analysis result. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• Korean Journal of Food Science and Technology
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• v.21 no.2
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• pp.252-257
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• 1989

Nylon laminated low density polyethylene(LDPE) film is mostly used for package of Vienna sausage in Korea. The water vapor permeability and gas transmission rate of Nylon laminated LDPE film is higher than that of Oriented polypropylene/polyvinylidene chloride coated LDPE film. Comparision of shelf-life of Vienna sausage packed with both film was as follows. The water vapor permeability and gas transmission rate of PVDC coated film were 2.5 times lower and 20.7 to 30 times lower than those of Nylon laminated film, respectively. Shelf-lives of Vienna sausage packed with Nylon laminated film and PVDC coated films were 25 days and 31 days at $15^{\circ}C$, 32 days and 41 days at $5^{\circ}C$, respectively.

• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.122-126
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• 1992

The shelf-life of wrapped chewing gum(7 sticks) under the climate condition of Seoul was predicted by using moisture gain equation to reach safe moisture limits of 3.16% (dry basis). The overall water vapor permeability of multilayer packaging material was about 0.00045g water/pack day mmHg. The water activity of chewing gum at any temperature was predictable using Clausius-Clapeyron equation. The most significant loss of shelf-life was occurred between June and July, and most products reached the end of shelf-life at July and August. The product which were made in October and November had the longest shelf-life as seven months.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.115-124
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• 2008

This Study was investigated in main breakage types of 50 interlocking block pavements in apartment houses and evaluated on their performance. According to performance evaluation, maintenance control index of 9 aged interlocking block pavements ranged 7.9 to 8.9. These values meant that the condition of interlocking block pavements were still good. Therefore, it was concluded that the 10-year cycle of the block replacement recommended by Ministry of Construction & Transportation is necessary to reappraise. To objectively evaluate the performance of interlocking block pavements, this study presented the criteria of maintenance control by combining two maintenance control standards suggested by Ministry of Construction & Transportation and the Japan Interlocking Block Pavement Engineering Association. Also, this study suggested that the domestic standard is necessary to include durability standards and quality standards of joint filling materials and bedding sand layer for increasing expectation life and reducing maintenance costs of interlocking block pavements.

• International Journal of Highway Engineering
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• v.6 no.4 s.22
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• pp.101-108
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• 2004

Asphalt overlay method is a general method to extend the of life old concrete pavements. However, reflection cracks are the typical problem of the AC overlay on distressed concrete pavement. Joint sealing, stress absorbtion layer have been used to prevent reflection cracks however partial success of to delay the timing of reflection cracking was recognized. Reflection crack problem can be eliminated by using rubblization method, which crush concrete pavement slab into piece of aggregate size that can be used base material. Previous research on rubblization method indicated that the size of rubblized PCC ranged 40-70mm at upper layer, and more than 100mm at lower layer. In this study, the adequate depth of rubblized PCC that ran prevent reflection cracking of AC overlay is estimated base on the simulation test of reflection cracking with 0, 10, 20cm rubblized PCC base.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.41-50
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• 2011

It is well-known that pavement is easily damaged by several factors including permanent deformation and fatigue crack, causing service life of the pavement to be shorter than expected. It is very important to predict amount of permanent deformation for designing pavement and developing design method of pavement. A new model of permanent deformation of pavement materials based on concept of shear stress ratio has been proposed because the lower pavement materials are highly affected by shear strength of the material. In this study a large repetitive triaxial load test has been adapted for performing test of permanent deformation of crushed subbase materials. The test procedure which includes concept of shear stress ratio has been newly developed. Several important model parameters can be obtained from the test that can be used for making correct permanent deformation model of the material.

• Journal of Mushroom
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• v.19 no.3
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• pp.234-245
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• 2021

To extend the shelf life of king oyster mushrooms for export, we investigated the impacts of mushroom quality grade, fruiting body trimming, and packaging method (tray container sealed packaging vs string-tied OPP bag packaging). Quality is divided into two grades: 1^st grade, which is mushrooms adapted by lowering the cultivation temperature to 9~11℃, and 2^nd grade, mushrooms held at 13~15℃ prior to harvest. Using selected 1^st and 2^nd grade mushrooms, 3 treatments were carried out to assess effects of trimming and packaging method. Test groups included 1) trimming plus string-tied OPP bag packaging (Cut & OPP), 2) no trimming plus string-tied OPP bag packaging (Uncut & OPP), and 3) trimming plus tray container sealing packaging (Cut & Tray). Gas composition inside the packaging, changes in quality factors, and sensory evaluation for fresh quality were performed over 42 days of 0℃ storage. Overall freshness was best maintained in the following order: Cut & Tray > Cut & OPP > Uncut & OPP for both 1^st and 2^nd grade mushrooms. The shelf-life of 1st grade mushrooms was about 30 days for Cut & Tray, 28 days for Cut & OPP, and 21 days for Uncut & OPP. The shelf-life of 2^nd grade mushrooms was about 22 days for Cut & Tray, 17 ays for Cut & OPP, and 14 days for Uncut & OPP. Factors affecting fresh mushroom quality included browning of cap and stalk, and mushroom decay index. Browning of the lower part of the stalk, with related color change as noted in a^* and b^* values were the main factors indicating quality deterioration of king oyster mushrooms.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.809-817
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• 2008

This paper deals with the development of ViscoElastic Continuum Damage Finite Element Program (VECD-FEP++) and its verification with the results from both field and laboratory accelerated pavement tests. Damage characteristics of asphalt concrete mixture have been defined by Schapery's work potential theory, and uniaxial constant crosshead rate tests were carried out to be used for damage model implementation. VECD-FEP++ predictions were compared with strain responses (longitudinal and transverse strains) under moving wheel loads running at different constant speeds. To this end, an asphalt pavement section (A5) of Korea Expressway Corporation Test Road (KECTR) instrumented with strain gauges were loaded with a dump truck. Also, a series of accelerated pavement fatigue tests have been conducted at pavement sections surfaced with four asphalt concrete mixtures (Dense-graded, SBS, Terpolymer, CR-TB). Planar strain responses were in good agreement with field measurements at base layers, whereas strains at both surface and intermediate layers were found different from simulation results due to the complexity of tire-road contact pressures. Finally, fatigue characteristics of four asphalt mixtures were reasonably described with VECD-FEP++.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6932-6942
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• 2014

The expressway is a key area of road networks for national industry, economics and social development. In addition, the number of lines are increasing continuously. Recently, road management policy have shown a paradigm shift to safe road, low-carbon and green etc. Nevertheless, the road condition has deteriorated dramatically by fatigue cracking, thermal cracking and weather impact. On the other hand, the budgets for highway maintenance have shrunk dramatically. In this study, an effective pavement management and maintenance process was developed to extend the pavement serviceability and pavement life to overcome the rack of budgets.

• Journal of the Korean Geosynthetics Society
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• v.1 no.1
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• pp.53-61
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• 2002

Even though a lot of laboratory and field tests for asphalt pavements using geosynthetics have been conducted recently, any rational and systematic analysis for the economic efficiency of the asphalt pavement systems reinforced by using geosynthetics has not been proposed yet. In this study, the economic analysis considering the traffic characteristics for the glass fiber sheet reinforced asphalt pavement was performed using the Life Cycle Cost Analysis(LCCA) which is commonly used for the economic analysis technique. The economic efficiency for the glass fiber sheet reinforcement and the traffic characteristics was examined by applying the test results from the literature review to the economic analysis model.