• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.122-127
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• 2004

The purpose of this study is to introduce the standard of the durability and evaluation method for paper shredder. The major evaluation criteria include shredding capability, shredding blade (or cutter) hardness and edge roughness, and durability. Due to the difficulties in assessing the durability directly, performance deterioration of the shredder was assessed by measuring the torque variation along with the variation in shredded chip size and load, thereby proposing the indirect method of assessing the paper shredder durability.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.60-68
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• 2018

The Housing Act amended allows vertical extension up to three floors and increases the units of housing (or total floor area) to site up to 15%. Currently, the feasibility of performing vertical extension is evaluated based on safety diagnosis provisions and manuals with preliminary investigations on slope, uneven settlement, load-bearing capacity, and durability. However, a need for more reasonable evaluation methodology for the preliminary investigation is still required because the current procedures are borrowed from safety diagnosis provisions and manuals for reconstruction without detailed examinations on evaluation criteria and sampling methods. Accordingly, this study is intended to suggest a method to obtain feasible sampling size for durability assessment by statistically analyzing the safety evaluation data sets on concrete carbonation and steel corrosion obtained from apartment complexes. The results of this study are expected to be beneficial for establishing more reasonable field sampling size, and in turn, more reliable durability assessment protocol for vertical extension.

• Geomechanics and Engineering
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• v.38 no.6
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• pp.593-601
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• 2024

In this paper, the quantitative evaluation method is presented for the durability performance of mountain tunnel concrete linings experiencing freezing and thawing during winter season. To analyze the freeze-thaw characteristics of lining, the freezing time of the concrete lining was measured by the outside temperature. The heat flow analysis was conducted based on the freezing time measured through the indoor experiment, and based on this, the energy required to freeze the concrete lining by the temperature of the outside air could be analyzed. In addition, the temperature change during the winter season was measured through an instrument installed on the actual tunnel concrete lining, and based on the results of indoor and field experiments, criteria for freeze-thaw environment evaluation and progress evaluation were prepared. Also, an equation using the freezing index was proposed through regression analysis.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.3-4
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• 2015

Environmental load reduction and sustainable development one of the study's research into the available material is discharged, remove the coarse aggregate and fine aggregate from waste concrete and utilizing the remaining cement fine powder as an alternative raw material for limestone is the main raw material of cement developing playback cement that was the purpose. Physical over existing research and chemical quality was confirmed was evaluated for durability by promoting carbonation test, research studies on the durability evaluation insignificant. As honipyul within the aggregate differential lung fine powder increases carbonation resistance performance've found that increased sharply and, S0 showed fairly similar to the OPC. Therefore, the development within the technology research to separate fine aggregate discharge fully differential and waste fine powder is determined to be the development and use of the playback durability of the cement with the carbonation levels corresponding to the OPC if made.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.553-561
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• 2010

Like the shotcrete can be deteriorated by chemical compounds as service years increase, the grout which is used to fasten the cablebolt(rockbolt) system in the underground structures also can be deteriorated by chemical compounds such as sulphate and/or chloride contained in groundwater during service years. This can induce issues on the long term durability of cablebolt(rockbolt) system and consequently on the stability of underground structures. In this study, the deteriorations of long term durability of cement mortar grout by each chemical compound of sulphate or chloride are studied experimentally and also complex deterioration by the mix of sulphate and chloride is investigated. Based on the results obtained in this study, the characteristics and prediction of deterioration of long term durability of cement mortar grout for cablebolt(rockbolt) system are suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.663-668
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• 2003

In this paper, an environmental factor and a durability resistance factor which adapts the concept of the Load Resistance Factor Design for safety design of RC structures is derived and a basic principle of a durability evaluation for RC structures using the factors is proposed. It is shown that durability of RC structures can be evaluated by comparing predicted value of chloride ion concentration with limit value of concentration for steel corrosion generation in reinforcement steel position and the durability of concrete manufactured for the RC structures can be also evaluated by comparing characteristic diffusion coefficient of concrete with predicted diffusion coefficient during mixture design.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1131-1137
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• 2004

With the recent continuous expansion of subways, newly created subways tend to have lower locations and wider sections. Furthermore. since box structures and evacuating tunnels are classified into a category of mass-concrete. the thermal-stress, emitted from the inside. causes cracks to structures from the inception of constructing. In this paper, thermal-stress analysis and durability evaluation of box structure were carried out to investigate relationship between durability and parameter causing the heat of hydration. Through the examination, this paper tries to find out satisfactory solutions to regulated thermal crack and ensure the required duration period. The results of this paper showed that to control thermal crack and guarantee the required duration period it was more effective to use low-heat-portland cement and moderateheat-portland cement. As cement volume due to reduction of water-cement ratio increased, the possibility of thermal cracks occurrence increased but results of durability evaluation was different depending on evaluation method. The results showed that the appropriate water-cement ratio to control the heat of hydration and satisfy the required durability was $45\∼55\%$. And it was showed that during placement of concrete blocks ambient temperature affect the heat of hydration. thermal crack and long-term durability largely and when concrete was placed at low temperature to control thermal crack. it need to try to guarantee the required duration period. Henceforth, by studying not only internal and external conditions, such as the relative humidity and the unit weight. but also methods, to evaluate durability, in accordance with domestic situations, more reasonable design of durability should be achieved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.197-205
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• 2020

In 2014, The Housing Act amended to allows vertical extension and increases the units of housing (or total floor area) to site. Currently, the feasibility of performing vertical extension is evaluated based on safety diagnosis provisions and manuals with 1st investigation stage on slope, uneven settlement, load-bearing capacity, and durability. However, a need for more reasonable evaluation criteria for the investigation is still required because there had not been any other case study on the diagnosis for the vertical extension, and the engineering basis on evaluation criteria were not suggested. Accordingly, this study is intended to suggest feasible evaluation criteria on the carbonation, chloride ion contents, corrosion of reinforcements, crack and surface deterioration of concrete for durability assessment by codes and standards of domestic and foreign countries. The results of this study are expected to be beneficial for establishing more reasonable durability evaluation criteria, and in turn, more reliable assessment protocol for vertical extension.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.2
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• pp.250-256
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• 2017

Automatic transmission(A/T) is one of a car's core components. The durability of A/T has an effect on the durability of the car. The input shaft of A/T passes the power directly from the engine, so the durability of the input shaft for A/T is likewise vital. In this study, the test method of the input shaft is considered and the load spectrum of A/T is analyzed to secure durability of the input shaft. The shape parameter, T-N curve of the input shaft torsional fatigue test are obtained for life evaluation and analysis. Results of this study can be used to get the basic background of the durability test for A/T components.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.68-74
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• 2006

The evaluation of durability performance in Virtual Testing Laboratory(VTL) is a new concept of vehicle design, which can reduce the automotive design period and cost. In this study, the multibody dynamics model of a car is built with a reverse engineering design. Hard points and masses of components are measured by a surface scanning device and imported into CAD system. In order to simulate the non-linear dynamic behavior of force elements such as dampers and bushes, components and materials are tested with specialized test equipments. An optimized numerical model for the damping behavior is used and the hysteresis of bush rubber is considered in the simulation. Loads of components are calculated in VTL and used in the evaluation of durability performance. In order to verify simulation results, loads of components in the vehicle are measured and durability tests are performed.