• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1785-1795
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• 2013

Most of the previous models for analysis of shallow water flow assumed the uniform velocity distributions over the flow depth so that they produced incorrect velocity prediction at meandering part due to the ignorance of secondary current. In this study, the vertical velocity profiles in longitudinal and transverse direction were decomposed as the mean and variation components, which resulted in additional dispersion stresses terms in momentum equations. The proposed model were applied at the channels with $30^{\circ}$, $90^{\circ}$, $270^{\circ}$ bends, and shallow water flow in curved channel was analyzed using dispersion stresses. The dispersion stresses acted as a sink or source in the momentum equations, which caused the transverse convection of momentum to shift from the inner bank to the outer bank.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.2
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• pp.62-67
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• 2002

This paper - following 'Development of multi-purpose marine waste cleaning systems for the shallow waters (Part I : preliminary conceptual design)'- describes on the system development and the sea trial performance evaluation(Cho[2003]). The multi-functional seabed waste collecting system and the towing hook system were developed. The maximum working depth of these systems are 15 and 100 meters, respectively(MOMAF[2001]). For the multi-purpose use to collect the marine waste, this system contains floating waste collecting device for the waste on seawater and remained waste collecting device for the waste on seabed, while steel wire cutting system is added for higher efficiency In order to evaluate the system performance, the prototype of multi-functional system was constructed and the sea trial test at shallow water were carried out. As a result, this system operated well with safe and without any interaction so that the developed systems are practicable and applicable.

• 한국해양학회지
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• v.17 no.2
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• pp.41-50
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• 1982

We present theoretical models for the unstedy transports driven by the time-varying wind stress in horizontally unbounded shallow seas of an uniform depth. We derive linearized transport equations that inchude the acceleration, the Coriolis firce, the wind stress and the bottom friction. The steady transport in a shallow sea is different from the classical Ekman transport because of a presence of non-negligible bottom fricttttion. The transient reansport and an inertial oscillation of which frequency of rotation is the same as the frequency of the wind stress forcing. The transprt associated with a wind stress of which direction changes linearlywith time is decribed by a superpoeition so a free inertial oscillation with a pweiod of one inertial day, The theoretical models of the transports are useful in understanding the time-varying currents and the transports of nutrients in shallow seas.

• The Journal of the Acoustical Society of Korea
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• v.43 no.4
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• pp.466-475
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• 2024

Matched-Field Processing (MFP) is a model-based approach that requires accurate knowledge of the ocean environment and array geometry (e.g., array tilt) to localize underwater acoustic sources. Consequently, it is inherently sensitive to model mismatches. In contrast, the waveguide invariant-based approach (also known as array invariant) offers a simple and robust means for source-range estimation in shallow waters. This approach solely exploits the beam angles and travel times of multiple arrivals separated in the beam-time domain, requiring no modeling of the acoustic fields, unlike MFP. This paper extends the waveguide invariant-based approach to shallow water environments featuring a shallow pit, where the waveguide invariant is not defined due to the complex bathymetry. An in-depth performance analysis is conducted using experimental data and numerical simulations.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.259-265
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• 1993

The variation of H/F coefficient (Hubnerite/Feberite coefficient) and the temperature of formation with depth have been studied for the hydrothermal tungsten-quartz veins from Ssangjeon, Weolag, Cheongyang, and Sannae mines. All samples were selected at the same paragenetic stage and mineral assemblege according to depth. The studied mines provide an opportunity to examine and regional variations in wolframite composition in different provinces. The formation temperature is linearly related to the depth. At the Weolag, Cheongyang and Sannae mines, the H/F ratio of wolframite and filling temperatures of fluid inclusions in quartz show a general tendency to decrease at shallow levels, in spite of different geological settings. This implies the pH of fluid will decrease vertically with falling temperature and the high H/F ratio of wolframite in deep zone result in an increase of pH with depth. The Ssangjeon mine exhibits a tendency to increase slightly upwards at shallow level. This implies a different geochemical environment (high pH environment) for the Ssangjeon mine, as compared to the other three mines. The H/F coefficient pattern suggests that it is a useful geothermometer for vein-type tungsten deposits in Korea. The H/F coefficient as an indication of depth should be examined for use in exploration.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.527-537
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• 2003

The characteristics of ship induced waves caused by navigation become widely different from both ship's speed and water depth condition. The ship induced waves specially generated in coastwise routes frequently give rise to call unforeseen danger for swimmers and small boats as well as shoreline erosion or sea wall destruction in coastal zones. The main concern of ship induced wave study until now is either how to reduce ship resistance or how to manoeuvre the ship safely under a constant water depth in the view point of shipbuilding engineers. Moreover, due to the trends for appearance of the high speed ships at the shallow coastal water, we are confronted with the danger of damages from those ship induced waves. Therefore, it is necessary to examine the development of ship induced waves and the influence of their deformation effects according to its propagation ray. In present study, in order to predict the development of the ship induced waves and their propagation under the conditions of complicate and variable shallow water depth with varying ship's speed, we constructed a computer model using Boussinesq equation with a fixed coordinate system and verified the model results by comparison with experimental results. Additionally, the model was applied under the variable water depth based on actual passage and we then confirmed the importance of the variable water depth consideration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.734-742
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• 2016

Global warming and the depletion of fossil fuels have been caused by decades of reckless development. Wind energy is one form of renewable energy and is considered a future energy source. The wind tower is designed with a fundamental frequency in the soft-stiff design between the 1P and 3P range to avoid resonance. Usually, to perform natural frequency analysis of a wind tower, the boundary condition is set to the Fixed-End, and soil-pile interaction is not considered. In this study, consideration of the effect of soil-pile interaction on the wind tower was included and the difference in the natural frequency was studied. The fixed boundary condition was not affected by the soil condition and depth of the pile and the coupled spring boundary condition was unaffected by the depth of pile but affected by the depth of the pile, and the Winkler spring boundary condition is affected by both the soil condition and the depth of the pile. Therefore, the coupled spring boundary condition should be used in shallow depth soil conditions because the soil condition does not take the shallow depth soil into consideration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.4
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• pp.361-366
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• 2017

This study was conducted to evaluate effects of seeding rate and depth during broadcast sowing on growth and yield of foxtail millet and proso millet over 2 years. The rate of sowing seeds was adjusted to 5, 7, 10 and 20 kg per ha on foxtail millet, and 5, 10, 15 and 30 kg per ha for proso millet. Sowing depth was 0.5, 1, 3, 5, 7, and 10 cm used tractor rotary attachment for shallow-tilling. The rate of seedlings standing when foxtail millet and proso millet were sowed to a depth of 0.5~5 cm was 72.0~78.0% and 73.0~80.5%, respectively. Plant height and weight at the three-leaf stage after emergence was highest for the treatment with 3 cm rotary depth. As the rate of broadcast seed sowing increased, plant length, diameter, seed length, and seeds on the panicle decreased. The grain yield of foxtail millet was highest with broadcast seed sowing of 10 kg per ha (3652, $3977kg\;ha^{-1}$) and proso millet was highest at broadcast seed sowing of 15 kg per ha (2226, $2052kg\;ha^{-1}$) in 2012 and 2013, respectively. Therefore, the optimum rate of sowed seeds under broadcast cultivation was $10kg\;ha^{-1}$ for foxtail millet and $15kg\;per\;ha^{-1}$ for proso millet. Optimum sowing depth for foxtail and proso millet under broadcast cultivation was 3 cm, using a rotary tractor attachment for shallow-tilling.

• Journal of the Korean association of regional geographers
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• v.9 no.2
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• pp.203-216
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• 2003

The process of constructing coastal digital elevation model(DEM), for the 3 dimensional analysis, is composed by abstracting land layers for land elevation and water depth, reprojecting UTM, relocating geographical grid, and interpolating works. The geomorphic set of shallow sea, including tidal current, tidal zone deposition, and water depth distribution, was analyzed by eye search of Landsat TM image, masking of land zone, band combination and regression analysis. Some horizontal differences, between combined DEM and surveyed data of shallow sea, was corrected for analysis. Analyzed geomorphic elements are stream channel, alluvial fan, coastal terrace, tidal current. and shallow sea bank. Results of analysis present that transported fluvial materials influence tidal sedimentation, especially from Gahwacheon river, for the role of artificial draining flooding waters from Jinyang Reservoir, almost in the summer season. In the coastal area with less tidal current, more fine materials are deposited. The influence of currental deposition are higher on small pockets with west coast of well developed terraces. The lower skirt of alluvial fans developed into the tidal zone of shallow sea. Small pocket type bays are closed by coastal current, and less influenced from tidal deposition. The bank of Jinju Bay are developed originally from submerging of remnant erosional mountain ranges, and play on the role of trapping fine materials.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.261-269
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• 2005

To investigate effects of fanning practice and $NO_3-N$ contents of groundwater in intensive horticultural greenhouse area of Yeongnam province, the groundwater samples from 1,370 sites were collected and analyzed. In addition, cultivation year, crops, desalinization methods, amounts of manure application, tube well depth and soil texture with clay contents were observed. Of the investigated sites, 19.7% of shallow groundwater and 1.3% of confined groundwater were exceeded over $10mg/{\ell}$ as the $NO_3-N$ drinking limit value, respectively. $NO_3-N$ concentration in groundwater was highly significantly correlative with clay content $(r=-0.241^{**})$, well depth $(r=-0.228^{**})$ and cultivation duration $(r=0.104^*)$, respectively. In case of desalting crop method being executed for desalinization of greenhouse soil, the $NO_3-N$ value of groundwater was lower than any other desalinization method. The fact that $NO_3-N$ contents of confined groundwater was affected by shallow groundwater was clarified by that $NO_3-N$ contents in shallow were significantly correlative with the confined groundwater $(r=0.532^{**})$.