• 한국자동차공학회논문집
• /
• 제3권5호
• /
• pp.38-46
• /
• 1995

In this paper, an experimental study on the effects of the impact damage and the perforation characteristic of CFRP laminates with different fiber stacking orientation and ply number was done through an observation of interrelations between the impact energy vs. transmitted energy and the impact energy vs. absorbed energy per unit volume. The velocities of the ball before or after impact are measured by the high-speed camera. And when CFRP laminates are subjected to tranverse impact by a steel ball(${\phi}10$), the delamination shapes generated by impact damage are observed by using SAM (Scanning acoustic Microscope).

• Journal of Biosystems Engineering
• /
• 제35권3호
• /
• pp.182-188
• /
• 2010

Post-Harvest processing engineering is a field that studies prevention of the quality change of agricultural products during sorting, packaging, storage, and distribution after harvested. In distribution steps, agricultural products could be damaged by physical force, it is the main reason of low quality and they lost value of commodities. This study was performed to find the vibration characteristics of the peach, and to find the extent of the damage on the peach by fatigue stress. The vibration data was obtained on expressway and the vibration characteristics of peach was used to find the damage on the peach. To analyze the vibration characteristics of peach, the resonance frequency and vibration transmissibility were measured. The resonance frequency of the peach was 167.98 Hz and the transmissibility was 4.06 at resonance point. It was 150 ~ 250 Hz that the transmissibility was more than 1. And the transmissibility in simulated test was measured. When the trasmissibility was more than 1, the range was 15 ~ 65 Hz, and when it was less than 1, the range was 65 ~ 175 Hz. When the transmissibility was about 1, the range was 5 ~ 15 Hz. The damage and the vibration cycle numbers of peaches were compared with input frequency and acceleration. More damage and less cycle number happened in 30 Hz than in 62.5 Hz. The reason was that the transmissibility of 30 Hz was higher and the vibration displacement in lower frequency was more. The more acceleration and cycle number increased, the more the bruising volume of peaches increased. The bruising volume ratio for vibration fatigue was measured according to input acceleration and cycle number. Using measured data, regression models for bruising volume ratio(BVR) was developed as a function of the acceleration(A) and cycle number(CN) as follows. BVR = a * $A^b*$ $(CN)^c$

• 대한조선학회논문집
• /
• 제48권3호
• /
• pp.275-280
• /
• 2011

In the present study, a unified viscoplastic-damage model has been applied in order to describe the mechanical characteristics of fresh water ice such as nonlinear material behavior and volume fraction. The strain softening phenomenon of fresh water ice under quasi-static compressive loading has been evaluated based on unified viscoplastic model. The material degradation such as growth of slip/fraction has quite close relation with material inside damage. The volume fraction phenomenon of fresh water ice has been identified based on volume fraction (nucleation and growth of damage) model. The viscoplastic-damage model has been transformed to the fully implicit formulation and the discretized formulation has been implemented to ABAQUS user defined subroutine (User MATerial: UMAT) for the benefit of application of commercial finite element program. The proposed computational analysis method has been compared to uni-axial compression test of fresh water ice in order to validate the compatibilities, clarities and usefulness.

• 한국작물학회지
• /
• 제47권1호
• /
• pp.1-12
• /
• 2002

Flour characteristics of Korean winter wheat grown in Suwon in 1997 and 1998, and in Suwon and Deokso in 1998 were evaluated. Korean winter wheat cultivars were significantly influenced by years and locations in flour properties such as ash content, protein content, damaged starch content, starch swelling volume and power. Protein content was highly correlated with starch damage and alkaline water retention capacity. There were highly significant correlations between mixing time of mixograph and SDS sedimentation volume. Swelling properties of flour and starch were highly correlated with pasting properties of flour and starch, respectively. Compared to commercial flours for baking, Alchanmil, Gobunmil, Keumkangmil and Tapdongmil showed similar protein content, SOS sedimentation volume and mixograph mixing time. Eunpamil, Geurumil, Olgeurumil, Suwon 258, Suwon 261, Suwon 265, Suwon 275, Suwon 276, Suwon 277, Suwon 278 and Urimil had similar values to commercial noodle flours in SDS sedimentation volume. Alchanmil, Olgeurumil, Suwon 274, Suwon 275, Suwon 276 and Urimil showed higher swelling and pasting properties than the others. Chokwang, Olgeurumil, Suwon 277 and Urimil were similar to commercial cookie flours. Friabilin-absence lines showed higher protein content and starch damage than those of friabilin-presence lines. Absence lines of 1D$\times$2.2 + 1Dy12 subunit in high molecular weight glutenin subunits showed higher SDS sedimentation volume and mixing time of mixograph than those of presence lines.

• Structural Engineering and Mechanics
• /
• 제60권5호
• /
• pp.875-890
• /
• 2016

A new structural damage index for seismic fragility analysis of reinforced concrete columns is developed based on a local tensile damage variable of the Lee and Fenves plastic-damage model. The proposed damage index is formulated from the nonlinear regression of experimental column test data. In contrast to the response-based damage index, the proposed damage index is well-defined in the form of a single monotonically-increasing function of the volume weighted average of local damage distribution, and provides the necessary computability and objectivity. It is shown that the present damage index can be appropriately zoned to be used in seismic fragility analysis. An application example in the computational seismic fragility evaluation of reinforced concrete columns validates the effectiveness of the proposed damage index.

• 한국기계가공학회지
• /
• 제11권6호
• /
• pp.107-114
• /
• 2012

Fracture of brittle material due to dynamic load such a particle impact has been reported by many researchers as the fracture behavior by variation of stress for a short minute. Especially, the brittle material, such a ceramic, applied to the structural component of machine, is considered as the important project. In order to evaluate the improvement of impact resistance, the particle impact test for the $Al_2O_3-TiO_2$ coated glass is practiced. And then, the damage variation according to the impact energy of steel ball was evaluated. There was a large improvement by the ceramic coating on the surface of a glass substrate. The damage volume was especially imported to evaluate damage behavior in quantity. These data were plotted on logarithmic coordinate and experimental equations were induced by data analysis based on test results. And the variation of critical energy for crack initiation was analyzed with critical impact energy when each crack occurs.

• 대한한방내과학회지
• /
• 제22권2호
• /
• pp.127-134
• /
• 2001

The purpose of this investigation is to evaluate the effects of Samwha-tang(三化湯) Extracts on reversible forebrain ischemia experimentally induced from the occlusion of middle cerebral artery. The volume of cerebral ischemia, the volume of cerebral edema, and the change of pyramidal neuron of the CA1 area in hippocampus through light microscopy were investigated. we obtained the following results. The volume of the control group, which had ischemic damage was 21%, and the volume of the sample group, which had ischemic damage, was 16%. The ratio of the volume of the right/left hemisphere was 117.2 in the control group, and 108.8 in the sample group. Also, the light microscopy revealed that the pyramidal cells of CA1 area in hippocampus had many damages like changes into discontinuous and unsystematic forms. But, in the sample group, the cells were less damaged compared with the control group.

• Computers and Concrete
• /
• 제22권1호
• /
• pp.63-70
• /
• 2018

The steel fiber reinforced concrete (SFRC) shows better performance under dynamic loading than conventional concrete in virtue of its good ductility. In this paper, a series of quasi-static experiments were carried out on the SFRC with volume fractions from 0 to 6%. The compressive strength increases by 38% while the tension strength increases by 106% when the fraction is 6.0%. The contact explosion tests were also performed on the ${\Phi}40{\times}6cm$ circular SFRC slabs of different volume fractions with 20 g RDX charges placed on their surfaces. The volume of spalling pit decreases rapidly with the increase of steel fiber fraction with a decline of 80% when the fraction is 6%, which is same as the crack density. Based on the experimental results, the fitting formulae are given, which can be used to predict individually the change tendencies of the blast crater volume, the spalling pit volume and the crack density in slabs with the increase of the steel fiber fraction. The new formulae of the thickness of damage region are established, whose predictions agree well with our test results and others. This is of great practical significance for experimental investigations and engineering applications.

• 대한본초학회지
• /
• 제37권5호
• /
• pp.75-81
• /
• 2022

Objectives : In 『Treatise on Cold Damage Diseases』, the volume of preparation dosage measured in Hap was 6.5mL. This study aimed to confirm that a square-inch-spoon, which measures powder preparation dosage, was 1/3 Hap, and that Jeon-bi was 1/8 square-inch-spoon. Based on these values, this study also aimed to adjust the diameter of Firmiana-Seed-sized pill preparation, currently known as 6.5mm, so that one square-inch-spoon of powder preparation creates 16 pills. Methods : Calculated the ratio between the floor areas of square-inch-spoon and Jeon-bi and measured the ratio of volume; assumed that powder preparations were stacked as much as possible in the shape of a square pyramid when scooped comfortably, then calculated the slopes of 1/3 Hap and 1/4 Hap; measured the volumes of powdered Oryeongsan and Lijungwhan in square-inch-spoon and Jeon-bi; created the powders into Firmiana-Seed-sized pill preparation; adjusted the diameter of Firmiana Seed so that 16 pills could be created. Results : Inferring from the floor areas, the volume of square-inch-spoon is 9.2 times that of Jeon-bi; one square-inch-spoon should be 1/3 Hap for the powder to reach its maximum slope of 47° and, according to actual measurement of powder preparations, reach its maximum volume; when created into Firmiana-Seed-sized pill preparations, one square-inch-spoon should be 1/3 Hap so that approximately 16 pills were created. Conclusions : One square-inch-spoon of powder preparation was 1/3 Hap(2.17mL), Jeon-bi was 1/8 square-inch-spoon(0.27mL), and the diameter of Firmiana-Seed-sized pill preparation was 5.5mm.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.253-256
• /
• 2006

The HPFRCCs show the multiple crack and damage tolerance capacity due to the interfacial bonding of the fibers to the cement matrix. For practical application, it is needed to investigate the fractural behavior and of HPFRCCs and understand the micro-mechanism of cement matrix with reinforcing fiber. The objectives of this paper are to examine the compressive behavior, fracture and damage process of HPFRCC by acoustic emission technique. Total four series were tested, and the main variables were the hybrid type, polyethylene (PE) and steel cord (SC), and fiber volume fraction. The damage progress by compressive behavior of the HPFRCCs is characteristic for the hybrid fiber type and volume fraction. And from acoustic emission (AE) parameter value, it is found that the second and third compressive load cycles resulted in successive decrease of the ring-down count rate as compared with the first compressive load cycle.