• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.737-743
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• 2016

Coastal hazards such as high waves are expected to increase due to global climate change. Therefore, we investigated new armor unit structures for disaster prevention. Recently, a concrete caisson has been used in many breakwaters against high waves in South Korea, but the demand for concrete armor unit has increased due to the high cost and many installation requirements. Though many new armor units have been developed over the world since Tetrapod in 1950, few have been used due to lack of systematical development. The representative armor units in current use have many advantages, but they cannot be applied to waves higher than 8 m. One of the new armor units developed by the design guide based on recent trend and hydraulic model experiments were conducted. The new armor unit was developed as a single layer due to cost effectiveness. However, the thickness is close to 1.5 times by overlapping the alphabet A and V. It showed higher overtopping compared to a double layer because of the thickness and the high packing density. It has a high interlocking vertically but low horizontally. It shows good stability at 9 m in model testing.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1051-1057
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• 2010

Database for the damage reference by armor piercing bullet test was established for both tube and plate specimens having a range of thickness. As the inclined angles of hit are increasing, it has been found that penetration damage diameter tends to increases accordingly in both specimen of the tube and plate, and such penetration damage diameter on the rear side becomes bigger than those on the front side. The tube specimen showed that the damage becomes bigger when central areas rather than the peripheral were hit. Through the plate test, it also has been found that the penetration ballistic limit for Al alloy is about 25.4mm and that of stainless steel about 12.7mm. From the fatigue analysis results using the database for damage reference, it has been identified whether the safety requirements of military aircraft could be met.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.478-484
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• 2019

The submarine cable for Yongsu wave power plant was cut in 2014 winter. This study investigated the probability of high-wave occurrence exceeding the 50-year return period and the underestimation of armor unit weight used to protect the cable. The observation data from KMA buoy and the hindcast wave data were reviewed to determine the return period of wave height during the winter. In order to investigate the armor unit weight of cable-protection, we calculated the required weight of armor unit using not only Design Standard for Harbor and Fishery Port, but also the previous researches for the wave with large incident angle. As a result, it appeared that the high wave exceeding the 50-year return period did not occur during the winter of 2014 and the armor unit weight of the cable protection was not sufficient to sustain the obliquely incident wave, which induced the cable protection failure.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.64-72
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• 2005

In this paper, we propose a design method of the millimeter-wave(W-Band) waveguide cavity harmonic voltage controlled oscillator(VCO) using a Gunn diode for the armor sensor. Using the 3-dimensional simulation tool(Ansoft $HFSS^{TM}$), we were able to find the impedance matching point between waveguide and Gunn diode and estimate the oscillation frequency. A varactor diode is used for the frequency tuning, and we find out the equation for the calculation of the tunable frequency range. The designed VCO shows good performances; 17dBm output power at 94GHz center frequency, 520MHz frequency tuning range similar to the estimated value(480MHz).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.4
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• pp.319-326
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• 2001

This paper reports on a recent investigation to determine criteria for the design of rubble-mound breakwaters. Existing theories and empirica] equations have been carefully reviewed and a new relation is proposed for the determination of optimum weight of armor unit of rubble-mound breakwater. A new parameter is introduced into the new semi-theoretical equation, which is closely related with the surface particle velocity of wave motion. The laboratory data reported by van der Meer(1987) were used for the determination of proper relations of empiricat parameters introduced into the new empirical equation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.336-344
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• 2007

A method is developed to evaluate partial safety factors for armor units, by which uncertainties of random variables in reliability function as well as wave height distribution with service periods could take into account straightforwardly. It is found that partial safety factors for resistance and wave height are correctly increased with improving target levels on failure of coastal structures at the same return and service periods. Therefore, it nay be possible to determine design variables through the same processes as those of deterministic method by using the partial safety factors for resistance and wave height evaluated in this paper, since uncertainties of random variables and the effects of service periods and target probability failure are directly considered in the processes of evaluation of partial safety factors.

• Steel and Composite Structures
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• v.23 no.2
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• pp.153-160
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• 2017

It is extremely important to be aware of the ballistic performances of engineering materials in order to be able to choose the lightest armor providing full ballistic protection in civil and military applications. Therefore, ballistic tests are an important part of armor design process. In this study, ballistic performance of plates made of carbon steel and cold worked tool steel against 7.62 mm AP (armor-piercing) bullets was examined experimentally and numerically in accordance with NIJ standards. Samples in different sizes were prepared to demonstrate the effect of target thickness on ballistic performance. Some of these samples were coated with titanium nitride using physical vapor deposition (PVD) method. After examining all successful and unsuccessful samples at macro and micro levels, factors affecting ballistic performance were determined. Explicit non-linear analyses were made using Ls-Dyna software in order to confirm physical ballistic test results. It was observed that the ballistic features of steel plates used in simulations comply with actual physical test results.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.5
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• pp.345-356
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• 2009

Tetrapod has been used as the armor blocks of most rubble mound breakwaters constructed in Korea. The Hudson formula has been widely used in the design of breakwater armor blocks in Korea. In the present study, we calculate the load and resistance partial safety factors of the Hudson formula for Tetrapod armors. The partial safety factors were calculated for the typical breakwater cross-sections of 12 trade harbors and 8 coastal harbors in Korea. The mean and standard deviation of them were also calculated. The mean values were compared with the partial safety factors of US Army (2006). The load and resistance factors are slightly smaller and larger, respectively, than the US Army values. However, the overall safety factors obtained by multiplying the load and resistance factors are close to the US Army values. The result of the present study could be used as the basic data to propose authorized partial safety factors in the future.

• Steel and Composite Structures
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• v.14 no.4
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• pp.313-333
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• 2013

The web-encased steel-concrete composite (WESCC) beam is a new developed steel-concrete composite beam. Experiments of six simply supported WESCC beam specimens were conducted. The effects of the shear-span ratio and steel section type were all investigated on the static behaviors such as failure modes, failure mechanism and bearing capacity. The experimental results denoted that all specimens failed in bending mode and the degree of combination between the bottom armor plate of steel shape and concrete were very well without any evident slippage, which demonstrated that the function of bottom armor plate and web were fully exerted in the WESCC beams. It could be concluded the WESCC beams have high stiffness, high load carrying capacity and advanced ductility. The design methods are proposed which mainly consist the bearing capacity calculation of bending and flexural rigidity. The calculation results of the bearing capacity and deflection which take the shear deflection into account are in agreement with the experimental results. The design methods are useful for design and application of the innovative composite beams.

• Journal of the Korean Society of Costume
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• v.63 no.6
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• pp.69-83
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• 2013

This research is to analyze costumes of Greek Mythology Gods in films using Morris' semiotics. In film "Clash of The Titans", Zeus' costume of shining gold armored body suit and long manteaux expressed the limitless sublime. The definite form contouring body shape of his costume also demonstrated classical beauty. Hades' costume of dark colored armor, long manteaux, and transformation via smoke also described the limitless sublime. The unbalanced and irregular shaped armor showed ugliness. In "Percy Jackson & The Olympians: The Lightening Thief", the armor and long manteaux of Zeus showed the limitless sublime. The beauty of his body and his sophisticated business wear indicated classical beauty. These features were also present in Poseidon's costume as well. The limitless sublime and ugliness are implied in Hades' look by portraying him as having a monster body with horns and wings, and his costume of punk look. In "Immortals", gods of Olympus wore clothing that was reminiscent of Egyptian times, which represented a time of strong royal authority, in order to expose the limitless sublime. Classical beauty was shown in the beauty of their body. Titans' costumes and look of non-human being were composed of black and red to present ugliness. The inherent meanings of Gods' costumes are death of god, patriarchy, and the good triumphing over the evil. The Greek gods are not held in the same reverence in the contemporary society. However mythology inspires lots of visual creations. The results help to accumulate a creative design database for fashion.