• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.3-9
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• 1996

In this study, comparison of theoretical solutions with experimental results is examined through fracture conditions for the case of float glasses subjected static loading. The range of fracture generation limits and critical penetration energies are solved according to the impactor mass under the high velocity, and analytical method of fracture strength and penetration strength are presented. Also, fracture patterns are investigated according to impact velocities. The results obtained from this study are as follows ; 1) Radial cracks are generated from the loading point regardless of plate thickness in the case of the plate subjected to the static loading. In the case of high-speed impact, dimensions of ring cracks become to smaller and length of radial cracks becomes shorter with the rapidity of impact velocity. 2) Kinetic change volume of collision after/before is constant regardless of velocities over the range of critical penetration velocity. 3) Although the same impact energy is working, the critical penetration energy is increased with the shorter of impactor mass. 4) Although the same impact energy is working, the penetration fracture of lighter Impactor mass is generated more than that of heavier impactor mass, and the impulse of lighter impacter mass appear more than that of heavier impactor mass. Therefore, the penetration fracture in the case of greater impulse is generated earlier regardless of the of the dimensions of Impact loading.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.91-97
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• 2004

The first Korean liquid propellant rocket KSR-III successfully finished its flight test on Nov. 28, 2002. Herein, we summarize the results of range safety system operation which is employed for the first time in flight tests of rockets developed by Korea Aerospace Research Institute(KARI). During the flight, safety-critical flight data including instantaneous impact points are monitored in realtime by range safety officers utilizing Range Safety Display Systems. The recorded screen of the display system is presented for the explanation of safety operation. In addition, comparisons are made between onboard navigation system based and radar based results in calculating instantaneous impact points, and also errors from the finally recorded impact point are described.

• Structural Engineering and Mechanics
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• v.60 no.2
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• pp.225-235
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• 2016

Fluid impact tests on plates containing mesh reinforcement and polypropylene fibers were modeled and simulated using explicit finite element analysis software, LS-DYNA. The scabbing dimensions obtained by the experiments and the simulations were compared and crack formations were matched. The objective was to test the accuracy and fidelity of the model and to confirm that damage caused by fluid impact on the plates can be estimated with a reasonable accuracy over a wide range of impact velocity.

• Asian Journal of Innovation and Policy
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• v.10 no.1
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• pp.68-89
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• 2021

The expansion of irrigated agricultural production can be appropriate for the southeast region in the U.S. as a climate change adaptation strategy. This study investigated the effect of supplemental development of irrigated agriculture on the regional economy by applying the supply side Georgia multiregional input-output (MRIO) model. For the analysis, 100% conversion of non-irrigated cultivable acreage into irrigated acreage for cotton, peanuts, corn, and soybeans in 42 counties of southwest Georgia is assumed. With this assumption, the difference in total net returns of production between the non-irrigation and irrigation method is calculated as input data of the Georgia MRIO model. Based on the information of a 95% confidence interval for each crop's average price, the lower and upper bounds of estimated results are also presented. The total impact of cotton production was $60 million with the range of $35 million to $85 million: The total impact of peanuts, soybeans, corn was $10.2 million (the range of $3.28 million to $23.7 million), $6.6 million (the range of $3.1 million to $10.2 million), $1.2 million (the range of -$6 million to $8.5 million), respectively.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.3
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• pp.89-100
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• 1997

The purpose of this paper was to analyze the content of impact prediction in EISS, in order to find the degree of the acuracy of impact prediction . 30 EISS were selected as analysis objects through variance miximization strategy. Content analysis of the selected EISS was performed by 5 analysis items, such as quantification of measurement, range of impact area, time frame of impact, likelihood of impact, and explict characterization of impact significance. The results showed that the accuracy investigated by the 5 items was very low. In conclusion, 5 suggestions were proposed in order to improve the credibility of EIS as a scientific report. The 5 suggestions were : 1) impact prediction should be described by quantitative measurement; 2) In establishing the time frame of the impact and the referent populatioin influenced by the impact, the characteristics of the proposed action should be carefully considerd; 3) the significance of the predicted impact should be quantitatively described; 4) specific description should also be used in the likelihood or the probability of the predicted impact in a real world; 5) equal emphasis should be put on the three environment, including natural and social as well as living environment.

• Journal of the Korean Society of Safety
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• v.38 no.5
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• pp.36-42
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• 2023

In this study, 50 ABE-type hard hats were procured from five certified commercial manufacturers, and shock absorption tests were conducted in accordance with Protective Equipment Safety Certification Notice No. 2020-35. The tests were performed under both high- and low-temperature conditions, adhering to safety helmet testing standards. The highest shock transmission ranges were recorded in the tests, with an average energy range of 2,600-4,108 N at high temperatures and 2,316-3,991 N at low temperatures. All five hard hat models demonstrated a maximum transmitted impact force below 4,450 N, without any loss of cap and attachment functionality, confirming their compliance with performance standards. Furthermore, we evaluated the side impact performance of the safety helmets of each company, with an average range of 4,722-5,267 N. Company A exhibited the lowest measurement at 4,722 N. Comparing these results with international safety standards and the national shock absorption test criteria, it was observed that the maximum transmitted shock value using government-specified impact weight falls within the range of 4,450-5,000 N. However, it was noted that developed countries have established specific standards for the side impact forces on safety helmets, which are legally mandated. Consequently, it is imperative for South Korea to enhance its safety helmet side impact performance test methodology to align with domestic standards in the future.

• Journal of Korea Foundry Society
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• v.2 no.2
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• pp.2-9
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• 1982

This paper is concerned with the improvement of impact and tensile Properties of spheroidal graphite cast iron of the following duplex matricess which were heat treated in the eutectic transformation temperature range (that is, $({\alpha}+{\gamma})$ coexisting range) ; ferrite-martensite, ferrite-bainite and ferrite-pearlite. The absorbed energy and maximum load was measured by recording the load-deflection curve with instrumented Charpy impact testing machine in the temperature range from $+100^{\circ}C$ to $-196^{\circ}C$. It was found the ferrite-bainite duplex matrix showed the highest toughness among the above matrices in the room temperature and the low temperature range. Comparison of this matrix to ferrite-pearlite matrix(that is, as cast) showed a lowering of $27^{\circ}C$ in the nil-ductility transition temperature (NDT) and a lowering of $40^{\circ}C$ in the ductile-brittle transition temperature (TrE), Which seems to result from the finner dimple pattern observed using miorofractography.

• Journal of Bio-Environment Control
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• v.5 no.1
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• pp.23-33
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• 1996

This study was performed to induce a quality improvement and standardization of materials used for greenhouse. For this purpose, physical and mechanical properties of agricultural films for greenhouse were measured by kinds and thickness of the films. The properties are composed of impact, tensile, tear propagation strength and light transmittance. The results were summarized as follows. 1. At the impact test result of the falling dart, the thicker the film, the greater the impact strength of soft film. The impact weight at 50 percents is from 158g to 213g and the strength of low density polyethylene(LDPE) film is higher than the rest of any other films. 2. Seeing the leveling of the impact rupture, maximum impact weight which was ruptured very little ranges from 62g to 192g. The impact strength of 0.1mm films was higher than that of 0.05mm as from 1.8 to 3.2 times. 3. Tensile weight covers from 0.95kg to 2.22kg in the test materials, and the weight of lengthwise film is larger than that of width. LDPE film has high value of tensile weight. Elongation range is from 345 to 102 percent and lengthwise elongation is greater than width as much as from 1.4 to 2.7 times. 4. Tea. propagation strength ranges from 80.5kg/cm to 121.7kg/cm, and unlike which of LDPE film has high value, EVA film has low value in the films tested. The width strength is higher than the lengthwise. 5. The light transmittance of the soft film is about 78-92 percent in the range of ultraviolet ray, but has high value in the visible ray range.

• Steel and Composite Structures
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• v.48 no.3
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• pp.305-320
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• 2023

The mechanical properties of polymeric composites are degraded under elevated temperatures due to the effect of temperature on the mechanical behavior of the resin and resin fiber interfaces. In this study, the effect of temperature on the impact response of the carbon fiber reinforced plastics (CFRP) was investigated at low-velocity impact (LVI) using a drop-weight impact tester machine. All the composite plates were fabricated using a vacuum infusion process with a stacking sequence of [45/0_2/-45/90_2]s, and a thickness of 2.9 mm. A group of the specimens was exposed to an environment with a temperature cycling at the range of -30 ℃ to 65 ℃. In addition, three other groups of the specimens were aged at ambient (28 ℃), -30 ℃, and 65 ℃ for ten days. Then all the conditioned specimens were subjected to LVI at three energy levels of 10, 15, and 20 J. To assess the behavior of the damaged composite plates, the force-time, force-displacement, and energy-time diagrams were analyzed at all temperatures. Finally, radiography, optical microscopy, and scanning electron microscopy (SEM) were used to evaluate the effect of the temperature and damages at various impact levels. Based on the results, different energy levels have a similar effect on the LVI behavior of the samples at various temperatures. Delamination, matrix cracking, and fiber failure were the main damage modes. Compared to the samples tested at room temperature, the reduction of temperature to -30 ℃ enhanced the maximum impact force and flexural stiffness while decreasing the absorbed energy and the failure surface area. The temperature increasing to 65 ℃ increased the maximum impact force and flexural stiffness while decreasing the absorbed energy and the failure surface area. Applying 200 thermal cycles at the range of -30 ℃ to 65 ℃ led to the formation of fine cracks in the matrix while decreasing the absorbed energy. The maximum contact force is recorded under cyclic temperature as 5.95, 6.51 and 7.14 kN, under impact energy of 10, 15 and 20 J, respectively. As well as, the minimum contact force belongs to the room temperature condition and is reported as 3.93, 4.94 and 5.71 kN, under impact energy of 10, 15 and 20 J, respectively.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.10-20
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• 2022

About 21% of domestic chemical accidents are caused by transport vehicles for the past 10 years in Korea. Also, ammonia is a chemical substance with the largest number of accidents, 82 out of 672. In this study, supposed seasonal alternative scenario and worst scenario in case of releasing ammonia during bunkering it from tank lorry to fishing vessel and interpreted seasonal impact and range through Python, ALOHA, Probit analysis. Radiation impact range of possibility for 2nd burn and for maximum radiation in winter scenario, which is one of the alternative scenarios, was the highest(range: 41m, radiation: 5.01kW/m²) while overpressure impact was less than minimum standard of impact. And toxicity impact range(EPRG-2) of the summer scenario was the widest(5.0km) and took a very high death rate near accident area(port area, tourist area) according to Probit analysis. the wort scenario had a similar impact and range of summer scenario.