• Journal of Wind Energy
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• v.15 no.1
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• pp.69-81
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• 2024

In order to understand water depth distribution in the waters of the southwestern sea offshore wind power demonstration complex, field observations were conducted using a multi-beam echosounder from before construction (2018.2) to operation (2022.8). After data processing and correction of the observed depth, cross-sectional analysis was performed to calculate the maximum water depth value, and time phase analysis was performed using the maximum water depth value. The maximum water depth change rate over time tended to gradually decrease, and there was little difference in the rate of change before the construction of the wind turbine foundation structure, and the rate of change was rapid when the foundation structure was under construction. As a result of time phase analysis, the rate of change of the first (2018.02) and the second (2018.05) showed a rate between -6.27 and -4.13, on average, as the rate of change before the construction of the offshore wind farm, and there was no difference between the first and second rates. The third (2018.11) rate of change was -4.25 to -1.82, and the fourth (2019.04) rate of change was -2.34 to -1.22, and the rate of change increased rapidly after the third time. The fifth (2019.07) rate of change was -2.11 to -1.31, the sixth (2021.05) rate of change was -2.09 to -1.28, and the seventh (2022.08) was -2.11 to -1.22 rate of change, and after the rate of change reached some extent, the change was analyzed in an insufficient graph.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.51-58
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• 2016

On account of the increase in water demand and climate change, droughts are in great concern for water resources planning and management. In this study, rainfall characteristics with stationary and non-stationary perspectives were analyzed using Weibull distribution model with 40-year records of annual minimum rainfall depth collected in major cities of Korea. As a result, the non-stationary minimum probable rainfall was expected to decrease, compared with the stationary probable rainfall. The reliability of ${\xi}_1$, a variable reflecting the decrease of the minimum rainfall depth due to climate change, in Wonju, Daegu, and Busan was over 90%, indicating the probability that the minimal rainfall depths in those city decrease is high.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.7-12
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• 2006

The multi-functional one-chip sensor has been fabricated to reduce output variation under various water environment. There were a temperature sensor, a piezoresistive type pressure sensor, and a electrode type conductivity sensor in the fabricated one-chip sensor. This sensor was measured water depth in the range of $0{\sim}180cm$, temperature in the range of $0{\sim}50^{\circ}C$, and salinity in the range of 0 $0wt%{\sim}5wt%$, respectively. Since the change of water depth in solution environment depends on various factors such as salinity, latitude, temperature, and atmospheric pressure, the water depth sensor is needed to be compensated. We tried to compensate the salinity and temperature dependence for the pressure in water by using lookup-table method.

• Magazine of the Korean Society of Agricultural Engineers
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• v.21 no.3
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• pp.121-126
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• 1979

The objective of this study was to grasp the condition of the distribution of water temperature in the warm water pool, and these observations were performed in Wudu warm water pool located at Wodu-Dong in Chuncheon. The results summarized in this study are as follows; 1. The horizontal distribution charts of water temperature at each depth of points were shown as Fig. 3, Fig. 4, and Fig. 5, respectively. In consequence of the observation, the condition of warm water was stagnant in the coner of warm water pool. As the result, it was found out that stagnant condition was the heaviest at water surface (depth; 0.05m), more heavier at middle depth (depth; 0.55m) and some heavy at bottom of the pool (depth; 1.10m). 2. The vertical water temperature change was shown as Fig. 6, and the mean water temperature of water surface (depth;0.05m) was higher about $2.2{\sim}3.3^{\circ}C$ than bottom water temperature. 3. Therefore, it was required to device such structures as form of broad cannels or overflow diversion weirs to mingle with top and bottom water.

• Journal of the Korean Geographical Society
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• v.42 no.1 s.118
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• pp.121-132
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• 2007

This paper examines the spatial and temporal variability in the water depth caused by artificial structures in Geum Estuary of South Korea. Water depth data set extracted from marine maps of 1979, 1990, 1996 and 2004 were used in a GIS to derive volumetric estimates of gains and losses of sedimentary material. Artificial structures caused above 2m in water depth to be shallow between 1979 and 2002 in the estuary system, particularly through disturbance of a natural transport in suspended sediment concentrations. The mutt significant change in suspended sediment transport were observed in area affected by embankment for fresh water, inducing the water depth shallower than before in almost 80% of the area. This was probably because of an continuous abundant mud supply from coastal river oven after blocking the fresh water. The spatial analysis made it possible to identify area wide patterns of water depth change subject to many different type of artificial structures, which tanner be acquired by traditional field sampling. It is anticipated thai this research could be used as a valuable reference to confirm the outputs from past field researches for sedimental process in more visual and quantitative manner.

• KCID journal
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• v.19 no.1
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• pp.19-29
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• 2012

The data of the agricultural water quality survey network was analyzed between from 1990 to 2010 in order to propose effective plans for water quality management by analyzing the characteristics of agricultural lakes and the change of water quality. The result of the analysis shows that there is a correlation between water quality and items that can be a function of water depth such as dam height, dam length, dam height/dam length ratio and active storage/surface area of lake ratio. This means that, Korean agricultural lakes, there is a correlation between water quality and water depth. Water quality of the lakes that have lower than 5m of active storage/surface area of lake ratio (effective water depth) especially tends to get worse rapidly. The Chl-a and COD concentration of Korean agricultural lakes have a tendency to increase between June and September. Therefore, we recommend first taking a water quality improvement project for the lakes preformed watershed management project, and taking a preventive short-term water quality improvement project for the unperformed lakes before June among lakes that have lower than 5m of effective water depth.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.152-160
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• 2021

The purpose of this study was to investigate the difference in the number of repetitions and the change in electromyographic response during the maximum speed squat exercise according to the depth conditions and the maximum speed squat exercise according to the time of each depth. Ten men in their 20s were selected as subjects and the maximum speed squat was performed for one minute in three environmental conditions (ground, knee depth, waist depth). We found that the number of repetitions according to the depth of water showed a significant difference, and as a result of the post-mortem comparison, the number of repetitions was higher in the ground condition and the knee depth than in the waist depth. And the muscle activity of rectus abdominis, erector spinae, rectus femoris, biceps femoris was increased during ground squat exercise, activity of all muscle was decreased during knee depth squat exercise, and activity of rectus abdominis, erector spinae, biceps femoris, tibialis anterior, gastrocnemius was decreased during waist depth squat. In conclusion, muscle activity of lower extremities during squat exercise in underwater environment can be lowered as the depth of water is deep due to buoyancy, but muscle activity of trunk muscles can be increased rather due to the effect of viscosity and drag.

• Journal of Ocean Engineering and Technology
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• v.20 no.3 s.70
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• pp.61-66
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• 2006

The estuary has a very complex coastline and bottom topography. Before the close of floodgate, the Keum river estuary was deposited with sediment from the Keum river, created bythe construction of the Keum river estuary dike. So, a periodical dredging is necessary to assure water depth for boat entry and departure to Kunsan port. Theof this study is to find the change of tidal current of M2tide and the topography before and after construction at the Geum River estuary dike. The change of water depth is investigated by digitizing the sea map (No.305) of Kunsan port, which was edited by National Oceanographic Research Institute. The calculated co-range and co-tidal charts of M2tide before the dike construction are similar to the observed ones. Therefore, the amplitude and phase after construction at Geum River estuary dike increases compared to before construction at Geum River estuary dike. The scour occurred in the A-A' section.

• The Korean Journal of Ecology
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• v.17 no.4
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• pp.435-442
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• 1994

In the littoral zone of Lake Paltangho, a vegetation map of aquatic macrophytes was constructed to estimate their occupied area, and the change of abundance of submersed macrophytes was examined along water depth to elucidate niche perferences on the depth gradient. Total area of the littoral zone was 267 ha, of which submersed, emergent and floating-leaved macrophytes covered 155ha, 103 ha and 10ha, respectively. Submersed macrophytes were distributed within a water-depth of 2.5m, with an apparent pattern of zonation: Vallisnaria gigantea and Ceratophyllum demersum at the deeper water depth of 1.5~2.5m.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.6
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• pp.494-500
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• 2015

It has been reported that a ship sailing in shallow water possesses better straight-line stability due to the change of fluid flow around the ship. This tendency affects manoeuvring characteristics of the ship. To investigate this phenomenon, indoor free running model test(FRMT) on KVLCC2 was carried out in three water depth conditions(H/T = 1.2, 1.5 & 2.0). Turning circle tests(± 35° ) and zigzag tests(± 20° /5° and ± 20° /10° ) were conducted with newly developed indoor FRMT system, and the manoeuvring results were compared with test results from other institutes. As the water depth decreased, the yaw rate of the ship decreased, and the distances of circular trajectories at the same heading angle increased in the turning circle tests. The first overshoot angles of the zigzag tests decreased. From both tests, the time for course change increased as the water depth decreased. These manoeuvring characteristics show that KVLCC2 in shallow water becomes more stable in terms of straight-line stability.