• Journal of The Korean Society of Agricultural Engineers
• /
• v.63 no.3
• /
• pp.75-85
• /
• 2021

This study evaluated variations in the paddy rice water demand based on the continuous changing in rice transplanting period and ponding depth at the four study paddy fields, which represent typical rice producing regions in Korea. Total 7 scenarios on rice transplanting periods were applied while minimum ponding depth of 0 and 20 mm were applied in accordance with maximum ponding depth ranging from 40 mm to 100 mm with 20 mm interval. The weather data from 2013 to 2019 was also considered. The results indicated that the highest rice water demand occurred at high temperature and low rainfall region. Increased rice transplanting periods showed higher rice water demand. The rice water demand for 51 transplanting days closely matched with the actual irrigation water supply. In case of ponding depth, the results showed that the minimum ponding depth had a proportional relationship with rice water demand, while maximum ponding depth showed the contrary results. Minimum ponding depth had a greater impact on rice water demand than the maximum ponding depth. Therefore, these results suggest that increasing the rice transplanting period, which reflects the current practice is desirable for a reliable estimation of rice water demand.

• KCID journal
• /
• v.17 no.2
• /
• pp.95-104
• /
• 2010

Water quality data for 10 years (2000~2009) from about 826 reservoirs that are operated as a agricultural water quality survey network were analyzed in order to seek water quality management plan based on physical and chemical characteristics of agricultural reservoirs. The 95% reservoirs that exceed agricultural water quality standard of Chl-a (35mg/ $m^3$) had effective water depth shallower than 5m. The reason was that the reservoirs had more inflows of nutrient salts from the watershed, bigger surface water area of weak structure to algae occurrence. As the reservoirs of effective water depth shallower than 5m cover 49% of benefited area for irrigation, it is critical for agricultural water quality management of the reservoirs. The water quality of reservoir with shallower than 5m effective water depth was worse than reservoir with deeper than 5m effective water depth. Therefore, it is desirable that effective water depth of reservoirs make more than 5m for water quality management by building the bank higher and dredging the bottom of reservoirs.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.4
• /
• pp.55-65
• /
• 2003

Pilot study was conducted to examine the effects of ponded-water depth and reclaimed wastewater irrigation on paddy rice culture. For the ponded-water depth effect, three treatments of shallow, traditional, and deep water depths were applied, and each treatment was triplicated. The irrigation water for the treatment pots was an effluent from constructed wetland system for sewage treatment, while the control pot was irrigated with tap water kept traditional ponded-water depth. Irrigation water quantity varied with ponded-water depth as expected and drainage water quantity also varied similarly, which implies that shallow irrigation might save irrigation water and also reduce environmental impacts on downstream water quality. Rice growth and production were not significantly affected by ponded-water depth within the experimental condition, instead there was an indication of increased production in shallow and deep ponded-water depths compared to the traditional practice. Raising drainage outlet to the adequate height in paddy dike might be beneficial to save water resources within the paddy field. There was no adverse effect observed in reclaimed wastewater irrigation on the rice production, and mean yield was even greater than the control pots with tap water irrigation although statistically not significant. Water-saving irrigation by shallow ponded-water depth, raising the outlet height in diked rice paddy fields, minimizing forced surface drainage by well-planned irrigation, and reclaimed wastewater irrigation are suggested to save water and protect water quality. However, deviation from traditional farming practices might affect rice growth in long term, and therefore, further investigations are recommended before full scale application.

• International Journal of Internet, Broadcasting and Communication
• /
• v.16 no.2
• /
• pp.169-178
• /
• 2024

This study aimed to investigate the effects of water depth and speed on the activation of lower muscles during squat exercises, utilizing electromyography(EMG). It involved ten male participants in there. Participants performed 30 squats over a minute at a speed of 60bpm and maximum speed squats until exhaustion within a minute. The Integrated electromyography(iEMG) readings for the rectus femoris showed statistically significant differences due to water depth and speed, with a significant interaction effect between depth and speed during squat exercises. The iEMG readings for the biceps femoris also showed statistically significant differences, with a significant interaction effect between depth and speed during squat exercises. The iEMG readings for the gastrocnemius showed statistically significant differences according to water depth and speed. However, the interaction effect of water depth and speed during squat exercises did not show a statistically significant difference. In contrast, the iEMG readings for the tibialis anterior demonstrated statistically significant differences, with a statistically significant interaction effect during squats. These findings suggest that water depth and speed positively influence the activation patterns of lower muscles. Therefore, appropriately tailored aquatic exercises based on water depth for individuals with musculoskeletal discomfort, including the elderly or those with physical impairments, can effectively reduce physical strain and enhance balance, as well as physical and perceptual aspects. It is concluded that such exercises could provide a safer and more effective method of exercise compared to ground-based alternatives.

• Journal of Korean Port Research
• /
• v.14 no.1
• /
• pp.97-105
• /
• 2000

This paper presents an automatic mesh generation considering water depth, which is based on the depth interpolation. The key feature of this method is that the position of a mesh on any depth in the shallow water area can be generated. The Examples are carried out, and the results are shown to be good. This method is shown to be a useful and powerful tool for the flow calculation for the seabed topography.

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

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

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2003.10a
• /
• pp.263-266
• /
• 2003

The purpose of this study is to investigate the effects of ponding depth treatment on water balance in paddy fields. The ponding depth treatments were very shallow, shallow and deep. Daily values of rainfall amount, ponding depth, irrigation water, drainage water, evapotranspiration, and infiltration were measured in the field. The medium ponded plots saved irrigation water about 16% to 53.4% without any statistical difference in rice growth and yields. Hence, the medium ponded depth treatment is better than the traditional deep ponded depth to save water in the transplanted rice culture.

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

• Journal of Korean Society of Water and Wastewater
• /
• v.27 no.2
• /
• pp.177-184
• /
• 2013

This study analyzed the hydraulic characteristics of a venturi flume with a circular cone using a 3-D numerical model which uses RANS(Reynolds-Averaged Navier-Stokes Equation) as the governing equation. The venturi flume with the circular cone efficiently measures the discharge in the low-flow to high-flow range and offers the advantage of accurate discharge measurements in the case of a low flow. With no influence of the tail-water depth, the stage-discharge relationship and the flow behaviors were analyzed to verify the numerical simulation results. Additionally, this study reviewed the effect of the tail-water depth on the flow. The stage-discharge relationship resulting from a numerical simulation in the absence of an effect by the tail-water depth showed a maximum margin of error of 4 % in comparison to the result of a hydraulic experiment. The simulation results reproduced the overall flow behaviors observed in the hydraulic experiment well. The flow starts to become influenced by the tail-water depth when the ratio of the tail-water depth to the total head exceeds approximately 0.7. As the ratio increases, the effect on the flow tends to grow dramatically. As shown in this study, a numerical simulation is effective for identifying the stage-discharge relationship of a venturi flume with various types of venturi bodies, including a venturi flume with a circular cone.