• Journal of Biosystems Engineering
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• v.23 no.4
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• pp.351-358
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• 1998

It was intended to investigate that how hardness of chestnut shell affects the flame peeling characteristics of Korean Chestnut. Effects of the hardness on the flame peeling characteristics need to be found to establish the optimum drying conditions for chestnut of various cultivars, sizes and harvested years. The equation based on the hardness of the chestnut shells was developed. It was found that the flame peeling characteristics of the corresponding to the various drying conditions did not differ significantly to the groups with the same hardness. The flame peeling characteristics of the chestnut with the same hardness were not influenced by cultivars, size, and harvested year, The peeling ratio and the heating depth were increased by decrease of the hardness of the chestnut shells. On the other hand, the peeling ratio and the heating depth were increased as the flame temperature was increased with the same hardness. When the heating depth was limited to 2.1 mm regarding the process characteristics and the damage ratio, the proper hardness and peeling ratio of chestnut shells were 1,369.8 g/$\textrm{mm}^2$ and 83.9%, respectively, at the flame temperature of $700^{\circ}C$. And also 1,517.7 g/$\textrm{mm}^2$ and 80.7% at 75$0^{\circ}C$.

• Tribology and Lubricants
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• v.36 no.6
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• pp.320-323
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• 2020

Thin film coatings are commonly exploited to minimize wear and optimize the frictional behavior of various precision mechanical systems. The enhancement of thin film durability is directly related to the performance maximization of the system. Therefore, a fine approach to analyze the thin film wear behavior is required. Archard's equation is a representative and well-developed law that defines the wear coefficient, which is the probability of creating wear particles. A ploughing model is a commonly used model to determine the friction force during the abrasive contact. The equations demonstrate that the friction force and wear coefficient are inversely proportional to the hardness of the material. In this study, Archard's equation and ploughing models are modified with an effective hardness to minimize the gap between the experimental and numerical results. It is noted that the effective hardness is the hardness variation with respect to the penetration depth owing to the substrate effect. The nanoindentation method is utilized to characterize the effective hardness of Cu film. The wear coefficient value considering the effective hardness is more than three times higher than that without considering the effective hardness. The friction force predicted with the effective hardness agreed better with the results obtained directly from the friction force detecting sensor. This outcome is expected to improve the accuracy of friction and wear amount predictions.

• Tribology and Lubricants
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• v.36 no.6
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• pp.378-384
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• 2020

The friction surfaces of mechanical parts are heat-treated or coated with hard materials to minimize wear. Increasing the hardness is a very useful way to reduce abrasive wear. The general Brinell hardness test, which is widely used for metallic materials, is not suitable because it hardly shows any change in hardness when coated with thin films. In this study, we propose a basis for the application of the new Brinell hardness test method to the coated friction surface. An indentation analysis of the rigid sphere and elastic-perfectly plastic materials is performed using a commercial finite element analysis software. The results indicate that their loadto-diameter ratio is the same; the Brinell hardness test method can be applied even when the indenter diameter is on the micrometer scale. In the case of hard coating, it is difficult to calculate Brinell hardness using the diameter of the indentation, but the study revealed, for the first time, that it can be calculated using the depth of the indentation regardless of coating. The change in hardness owing to thin film coating over a wide load range implies that the hardness evaluation method is appropriate. Additional studies on various properties related to the substrate and coating material are required to apply the proposed method.

• Journal of the Korean Society of Tobacco Science
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• v.13 no.1
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• pp.13-18
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• 1991

This experiment carried out to review influence of relative humidity, temperature and net weight on cigarette hardness for the uniformal control of cigarette quality. Obtained results are as follows: 1. The difference in the cigarette physical properties of constant hardness control is considerably lower than that of constant net weight control. 2. Contribution rate for cigarette hardness is relative humidity > net weight > temperature. 3. The multiple regression equation of cigarette hardness related with relative humidity, temperature and net weight is calculated as follows.

• Journal of the Korean Society for Precision Engineering
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• v.4 no.1
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• pp.65-73
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• 1987

In recent days, the application of ultrasonics has been increased in the field of engineering and medicine. The ultrasonic hardness tester to apply the principle of contact compliance method is entirely different from hardness tester in the past and in the practical use, the more pre- cisive measurement is required because it has a slight change of hardness value due to the difference of resonance frequency. Therefore, in this study, as one type of applicative transducers which can detect the optimum pressure load, ring type load cell was used in the measurement of ultrasonic hardness. From experimental results, it was compared ultrasonic hardness testing method with the other hardness testing methods. Also, the measurement error of ultrasonic hardness tester could be measured within .+-. 0.5 HRC F.S. in the case of 3.0Kg pressure load.

• Journal of the Korean Society of Tobacco Science
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• v.22 no.2
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• pp.157-163
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• 2000

Filter hardness is important to filter and cigarette manufactures because it is directly related to the ability of a plugmaker during making filter and to the acceptability of the filter by the consumer. In general, glycerol triacetate(Triacetin, TA) is the currently used common plasticizer in making filters from cellulose acetate tow and the effect of triacetin on hardness of filter which is made of mono cellulose acetate tow was well known. But unfortunately, the effect of triacetin on the hardness of cellulose acetate filter containing ativated carbon(carbon filter) was not reported so far. In this study, we manufactured filters with various carbon content at different triacetin concentrations and then analyzed the filter hardness and pressure drop. Filter hardness was directly increased with triacetin concentration but pressure drop was not affected and the effect of carbon content on filter hardness was smaller than that of triacetin concentration. However, pressure drop was directly increased with carbon content.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.376-381
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• 2012

This paper deals with application of instrumented indentation technique for quality inspection methodology for automobile component. For this, the instrumented indentation tests were performed the normal and cracked compressor journal, which is made from spheroidal graphite cast iron and utilized in air-conditioning system. And the Brinell hardness was estimated using the unloading slope and maximum indentation force. With the aid of Normal distribution, this Brinell hardness was statistically compared and analyzed with hardness measured by indentation hardness tests. Also, application possibility of reliability-based quality inspection criteria for compressor journal was evaluated through the probabilistic analysis for the Brinell hardness estimated by instrumented indentation technique.

• Journal of Powder Materials
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• v.31 no.4
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• pp.318-323
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• 2024

Cemented carbide for cutting tools, which is composed of carbide as a hard phase and metallic component as a metallic phase, mainly uses cobalt as the metallic phase due to the excellent mechanical properties of cobalt. However, as the demand for machining difficult-to-machine materials such as titanium and carbon fiber-reinforced plastics has recently increased, the development of high-hardness cemented carbide is necessary and the replacement of cobalt metal with a high-hardness alloy is required. In this study, we would like to introduce high-hardness cemented carbide fabricated using nickel-tungsten alloy as the metallic phase. First, nickel-tungsten alloy powder of the composition for formation of intermetallic compound confirmed through thermodynamic calculations was synthesized, and cemented carbide was prepared through the sintering process of tungsten carbide and the synthesized alloy powder. Through evaluating the mechanical properties of high-hardness cemented carbide with the nickel-tungsten alloy binder, the possibility of producing high-hardness cemented carbide by using the alloys with high-hardness was confirmed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.5
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• pp.115-127
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• 2012

This study was conducted on the measurement of soil hardness through a hardness testing machine in slopes of natural environments and artificial environments which is generally known as slope revegetation. The soil hardness as one of physicochemical soil properties is significantly associated with plant growth. Although another studies related to the slope revegetation was focused on herbaceous plants, studies related to soil properties for arbor appearance is lack. It was focused on the correlation analysis between the soil hardness and the plant appearance. the results were as follows : The higher the soil hardness is, the less the appearance of plants is as a result of survey. Species appearing in the high levels of the soil hardness represented mugwort and grass. The levels of the soil hardness in the slope of natural environments was good environmental conditions with various plants in the range of 6 to 12mm. The levels of the soil hardness in the slope revegetation was in the 6.88-30mm range. The soil hardness below 21mm showed a variety of plants with arbors and herbaceous plants, whereas it above 21mm represented a monotonous style of plant structure including Artemisia princeps, Lolium perenne, Poa pratensis L and Setaria viridis. The result of the correlation analysis between the soil hardness and the plant appearance was negatively correlated with justifiable significance levels. The result of a logistic regression analysis for tree appearance was statistically proved when the numerical value of the soil hardness is lower.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.291-296
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• 2002

The midsole hardness of athletic footwear affects capability of absorbing impact shock and controls rearfoot movement during running and walking. The prior studies were focused on examining the proper hardness of footwear for rearfoot movement or to finding effective hardness for absorbing impact shock. The displacements of maximal Achilles tendon angle described a amount of pronation motion is decreased when medial hardness of midsole is large more than lateral. Increasing hardness of footwear midsole are effected to reduce maximum and intial pronation angle, but declined the ability of impact shock during heelstrike. For determination of effectiveness hardness of midsole, therefore, the study that makes a compromise between rearfoot movement and absorbing impact during footstrike must be performed. The purpose of this study is to examine quantitative values of rearfoot control and absorbing impact shock with different hardness of medial and lateral midsole on heel portion. The results are useful to define biomechanical hardness of midsole for developing running shoes. As variable for impact shock, accelerations onto shank and knee are measured during 4 running speeds (5, 7, 9, 11km/h). Also, maximum and $10\%$ pronation angle (Achilles tendon angle) were measured using high-speed camera.