• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.4
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• pp.365-370
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• 2012

International Organization for Standardization has recently published ISO 12215-5 which is the small craft-hull construction and scantling. According to ISO 12215-5 AnnexB, the scantling determination can be accomplished by drop test for craft with a length $L_H$ of 2.5m up to 6m and single-skin construction. The current method, however, of visual test has the issue where it is difficult to make an objective evaluation of ship body strength. In this study, in order to develop an evaluation system that can make a quantitative evaluation of the drop test of leisure boats, the domestic/foreign regulations on drop test of leisure boats are analyzed and the drop test evaluation system is designed, and the system applicability is reviewed through 5-meter level aluminum ship, and the issues incurred by the state of the ship and the posture while dropping were checked.

• Journal of the Korean Professional Engineers Association
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• v.23 no.2
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• pp.81-93
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• 1990

The blasting to construct subways in Seoul, Korea. have often increased complaints of ground vibration. In order to prevent the damage to structures, it was necessary to predict the level of blasting induced vibration and to determine the maximum charge weight per delay within a allowable vibration level. A total of 109 blasts were recorded at ten sites. Blast-to-structure distances ranged from 8 to 84.2 meter, where charge weight varied from 0,1125 to 7.85 kg per delay. The data from blast were studied to determine the effect of explosives type on the vibration constants(k). Vibration constants were also analyzed in terms of compressive strength of rock and blasting patterns.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.3
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• pp.204-209
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• 2003

Utilization of soluble protein recovered from surimi wastewater using calcium powder of cuttle bone were examined. The crude ash content of the heat-induced surimi gel was increased linearly by increasing substitution ratio of recovered protein-ATC toward commercial surimi. Moisture (approximately $76\%$) and lipid $(0.2\%)$ contents were not change, but their protein contents were decreased 15.7 to $14.3\%$ depend on increasing of substitution ratio. The white index of the heat-induced surimi gel by color meter was increased up to $10\%$ of substitution ratio. There were no difference between $0\%\;and\;5\%$ substituted surimi gel in the gel strength. The sensory score on white index and texture of the heat-induced surimi gel did not change in 0 to $10\%$ as a substitution ratio of recovered protein-ATC toward commercial surimi, while decreased in more $15\%.$ The optimal substitution ratio of recovered protein-ATC as a bulking agent was $10\%.$ The heat-induced surimi gel prepared with $10\%$ substitution of recovered protein-ATC was similar to the content and composition of total amino. acids, and superior to calcium content and the ratio of calcium and phosphorus toward those of commercial surimi.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.27-33
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• 2010

In this study, a monotonic loading test to estimate structural capacity of 12 meter long full scale precast pre-stressed concrete beam specimen was performed with a 2,000 kN dynamic actuator. A couple of embedded steel plate was installed at the ends of the beam and specimens were connected to steel girder frame with high tension bolts. Nominal compressive strength of pre-stressed concrete beam and slab were 50 MPa and 24 MPa respectively. Two HD25 tensile steel reinforcements were welded on vertical plate of embedded steel plate. Pre-stressed concrete beam specimen was loaded by displacement control method with a certain loading pattern which was repeated loading and unloading with 10mm increment displacement. About 88.34%, 86.97% and 66.83% of displacement restoration ratios were evaluated at elastic, inelastic and plastic behavior region of specimen respectively.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.457-469
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• 2012

Bedform data at 4 shallow zones in the Yellow Sea where waves as well as tidal range are high and bed material is relatively coarse were collected and analyzed here. Water depths in the study area where the bedform data were collected are 10 ~ 65 meters, and ripple lengths well developed are between 6 ~ 13 meters. Existing empirical formula for prediction of ripple length as for coexistence of waves and currents include Khelifa and Ouellet(2000) and Soulsby(2005), both of which have been based on laboratory measurements, or field measurements at different physical environment from the Yellow Sea with respect to tidal range, wave strength, and bed material. New scaling factors are proposed here for better prediction of the ripple length on coastal zone in the Yellow Sea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.245-252
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• 1990

The distributions of copepods and chaetognaths in waters off the southern coast of Korea were investigated to evaluate their reliability as indicator species of different water masses. The samples for this study were collected vertically from about 5m above the bottom at 28 stations along 8 transects in three different months, February, April, and August, 1988. The sampling gear used was 0.45-meter NORPAC plankton net fitted with 0.33mm mesh. Acartia clausi, Centropages abdominalis, and Sagitta crassa were found to be reliable indicator species of neritic cold waters; Pleuromamma gracilis, Undinula darwini, Calocalanus plumulosus, Calanopia elliptica, and Sagitta enflata were of oceanic warm waters; Temora discaudata and Centropages furcatus were of neritic warm waters. According to the cluster analyses of the species found, the distinctive area in February was divisible into two regions or water masses, the coastal and off-shore regions; in April, however, it was divisible into four regions. In August, it was divisible into three areas, further indicating the strength of the Kuroshio tributaries pushing toward the coast.

• Earthquakes and Structures
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• v.11 no.1
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• pp.83-107
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• 2016

In this study, the response and behavior of machine foundations resting on dry and saturated sand was investigated experimentally. A physical model was manufactured to simulate steady state harmonic load applied on a footing resting on sandy soil at different operating frequencies. Total of (84) physical models were performed. The parameters that were taken into consideration include loading frequency, size of footing and different soil conditions. The footing parameters are related to the size of the rectangular footing and depth of embedment. Two sizes of rectangular steel model footing were used. The footings were tested by changing all parameters at the surface and at 50 mm depth below model surface. Meanwhile, the investigated parameters of the soil condition include dry and saturated sand for two relative densities; 30 % and 80 %. The dynamic loading was applied at different operating frequencies. The response of the footing was elaborated by measuring the amplitude of displacement using the vibration meter. The response of the soil to dynamic loading includes measuring the stresses inside soil media by using piezoelectric sensors. It was concluded that the final settlement (St) of the foundation increases with increasing the amplitude of dynamic force, operating frequency and degree of saturation. Meanwhile, it decreases with increasing the relative density of sand, modulus of elasticity and embedding inside soils. The maximum displacement amplitude exhibits its maximum value at the resonance frequency, which is found to be about 33.34 to 41.67 Hz. In general, embedment of footing in sandy soils leads to a beneficial reduction in dynamic response (displacement and excess pore water pressure) for all soil types in different percentages accompanied by an increase in soil strength.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.80.2-81
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• 2016

We investigate the dependence of solar proton events (SPEs) on solar and interplanetary type II bursts associated with solar flares and/or CME-driven shocks. For this we consider NOAA solar proton events from 1997 to 2012 and their associated flare, CME, and type II radio burst data with the following subgroups: metric, decameter-hectometric (DH), and meter-to-kilometric (m-to-km) type II bursts. The primary findings of this study are as follows. First, about half (52%) of the m-to-km type II bursts are associated with SPEs and its occurrence rate is higher than those of DH type II bursts (45%) and metric type II bursts (19%). Second, the SPE occurrence rate strongly depends on flare strength and source longitude, especially for X-class flare associated ones; it is the highest in the central region for metric (46%), DH (54%), and m-to-km (75%) subgroups. Third, the SPE occurrence rate is also dependent on CME linear speed and angular width. The highest rates are found in the m-to-km subgroup associated with CME speed 1500 kms-1: partial halo CME (67%) and halo CME (55%). Fourth, in the relationships between SPE peak fluxes and solar eruption parameters (CME linear speed, flare flux, and longitude), SPE peak flux is mostly dependent on SPE peak flux for all three type II bursts (metric, DH, m-to-km). It is noted that the dependence of SPE peak flux on flare peak flux decreases from metric to m-to-km type II burst.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.5
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• pp.259-266
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• 2018

This is the study for developing the hetero-core optical fiber sensors which are purpose to measure the prestress of PSC bridges during the life cycle period. The goal of this study is to improve the resolution of hetero-core sensors. As a result of the test, it is possible to measure the displacement in $2{\mu}m$ increments. In other words, if the length of the sensor module is 30cm, it is possible to measure the prestress variations in 0.2MPa increments at specified compressive strength of concrete(fck) of 40MPa by Hook's Law. So it can be useful for development of a sensor module measuring internal prestress measurement.

• Magazine of the Korea Concrete Institute
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• v.20 no.6
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• pp.28-35
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• 2008

The Burj Dubai Project will be the tallest structure ever built by man; when completed the tower will be more than 700 meter tall and more than 160 floors. While the early integration of aerodynamic shaping and wind engineering considerations played a major role in the architectural massing and design of this multi-use/residential tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria, the material selection for the structural systems of the tower was also a major consideration and required detailed evaluation of the material technologies and skilled labor available in the market at the time Concrete was selected for its strength, stiffness, damping, redundancy, moldability, free fireproofing, speed of construction, and cost effectiveness. In addition, the design challenges of using concrete for the design of the structural system components will be addressed. The focus on this paper will also be on the early planning of the concrete works of the Burj Dubai Project.