• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.3
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• pp.202-208
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• 2001

Explicit approximation has been developed to estimate the run-up height on S-berm breakwater on the basis of Saville's hypothetical slope method. For the explicit expression of run-up height several relations are developed to represent the ratio of run-up height against breakwater slope with various conditions of water depth and wave steepness. For the verification of explicit approximation the results are compared with Saville's measurement data and simple expression of Delft Hydraulic Laboratory.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.3
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• pp.128-133
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• 1990

An equation is presented to calculate wave height due to shoaling, refraction and bottom friction. The equation in an integral form is evaluated by two different methods： A numerical method and an analytical method based on approximation. Both methods are used to calculate wave height and show very good agreement between their results. As shown in the figure of wave height variation vs. relative water depth, an increase of incident angle leads to a decrease in wave height. For the case of normal incident wave, the present equation can be reduced, under some assumptions, to the existing equation of Bretschneider and Reid (1954).

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.261-264
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• 2005

For concrete structures immersed in seawater, the concentration of chloride used to estimate the chloride diffusion coefficient can be defined as the seawater chloride concentration. However, for seashore concrete structures which are not coming into direct contact with seawater, establishing the interface concentration of chloride becomes delicate. In addition, concrete structures are greatly affected by salt attack primarily due to airborne sea salt like it can be seen through the corrosion of rebar. This study intends to investigate characteristics on the salinity of airborne sea salt by height. Salinity measurement devices were installed at height of 2, 10 and 19m on the seashore water tower located in the area of Samchuk in the Eastern coast. Analysis results of the decrease of salinity with respect to the height above the ground at a distance of 30m from the seashore showed that the reduction reached about 40$\%$ at a height of 10m and 60$\%$ at 20m.

• Journal of Soil and Groundwater Environment
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• v.21 no.1
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• pp.80-85
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• 2016

Acoustic cavitation can induce various sonochemical effects including pyrolysis and radical reactions and sonophysical effects including microjets and shockwave. In environmental engineering field, ultrasound technology using sonochemical effects can be useful for the removal and mineralization of recalcitrant trace pollutants in aqueous phase as one of emerging advanced oxidation processes (AOPs). In this study, the effect of liquid height, the distance from the transducer to the water surface, on sonochemical oxidation reactions was investigated using KI dosimetry. As the liquid height/volume increased (40~400 mm), the cavitation yield steadily increased even though the power density drastically decreased. It was found that the enhancement at higher liquid height conditions was due to the formation of standing wave field, where cavitation events could stably occur and a large amount of oxidizing radicals such as OH radicals could be continuously provided.

• Journal of Korea Water Resources Association
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• v.34 no.4
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• pp.381-390
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• 2001

This is to evaluate the ascending capacity of migratory fish in the pool and weir type fishways. Ascending environment of the migratory fish in rivers is analyzed through eco-hydraulic experiments using sweetfish, Plecoglossus altivelis, trout, Oncorhnchus mykiss, and surveying the fall height of existing pool and weir type fishways. When the fall height is less than 16.0cm, the ascending capacity of sweetfish in the pool and weir type fishways is greater than trout. On the other hand when the fall height is over 20.0 cm, the ascending capacity of trout is greater than sweetfish. A sweetfish may prefer to jump for upward moving than trout. And its endurance after upward jumping over wear is greater than that of sweetfish. Because of high fall height of existing pool and weir type fishways the migratory environment in rivers is so poor. When the pool and weir type fishways are designed and constructed in river the fall height of weir must be considered for the variety of migratory fish living in river and the fall height of weir less than 20.0cm is suggested.

• The Journal of Pediatrics of Korean Medicine
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• v.28 no.2
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• pp.1-22
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• 2014

Objectives The purpose of this study is to investigate the relationship between weak children and growth indices. Methods One hundred twenty-six of the first and the second grade elementary school students who didn't have to develop yet their secondary sexual characteristics answered the questionnaire. Their bone age and body composition were measured. Results 1. According to the Weak Children questionnaire analysis, respiratory problem was one of the biggest problems in the weak children group (35.7%), followed by digestive problems (23.0%), psycho-neurological problems (22.2%), neuromotor problems (9.5%), and urogenital problems (8.7%). 2. From the comparison between growth indices of weak children and that of normal children are as follows: 1) The group of children who had problem in their digestive system had lower growth indices than the normal average children group. The growth indices includes mean height, weight, total body water, protein mass, mineral mass, body fat, skeletal muscle mass, body fat percentage, body mass index (BMI), and basal metabolic rate (BMR). 2) The children who had urogenital weakness had lower mean height, RH (Recent Height), RH - MPH {Recent Height(%) - Mid-Parental Height(%)}, RUS (Radius, Ulna and Short bone) score, weight, protein mass, body fat, BMI, and visceral fat than the normal children group. 3. The results of the multiple comparisons of growth indices and weak children groups are as follows: 1) Digestive weak children were the lowest in total body water, protein mass, mineral mass, skeletal muscle mass, and basal metabolic rate. 2) Urogenital weak children were the lowest in height, RH, RH - MPH, RUS score, and weight. Conclusion These results showed that children's growth is strongly correlated to their own growth problems, especially to those children who have digestive and urogenital problems. Therefore, this may be an effective way for children growth treatment in Korean medicine to treat weak symptoms.

• Journal of Korean Society on Water Environment
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• v.38 no.5
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• pp.211-219
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• 2022

In this study, the effect of liquid height/volume on sonochemical oxidation reactions was investigated in 300 kHz sonoreactors. The gas mixture of Ar/O₂ (50:50) was applied in two modes including saturation and sparging, and zero-order reaction (KI dosimetry) and first-order reaction (Bisphenol A (BPA) degradation) were used to quantitatively analyze sonochemical oxidation reactions. For the zero-order reaction, the highest sonochemical oxidation activity was obtained for the liquid height of 5𝛌, and the lowest height for both the gas saturation and sparging conditions. In addition, the sparging did not enhance the sonochemical oxidation activity for all height conditions except for 50𝛌, where very low activity was obtained. It was found that in sonochemiluminescence (SCL) images the sonochemical active zone was formed adjacent to the liquid surface for the gas sparging condition due to the formation of the standing wave field while the active zone was formed adjacent to the transducer at the bottom due to the blockage of ultrasound. For the first-order reaction, the highest activity was also obtained at 5𝛌 and the comparison based on the reactant mass was not appropriate because the concentration of the reactant (BPA) decreased significantly as the reaction time elapsed. Consequently, it was revealed that the determination of optimal liquid height (ultrasound irradiation distance) based on the wavelength of the applied ultrasound frequency was very important for the optimal design of sonoreactors in terms of reaction efficiency and reactor size.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.481-494
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• 2003

Flow through the culvert is very complex depending on the characteristics of hydraulic conditions. A design method using a monograph is normally employed due to the wide range of flow characteristics and the difficulty of calculating inlet water depth. The present study suggests the method for determining the inlet water depth of box culvert using Bernoulli's equation. By employing the explicit equation of inlet water depth, a standard design method of box culvert is developed for a wide range of flow characteristics. Explicit solution techniques are proposed to determine the width and height, slope and discharge of box culvert.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.5
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• pp.609-614
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• 2014

Researcher of this study improved conventional circle secondary settling basin, through the way such as extend of inlet pipe length, introduction of device for inducting uniforming of flow, keeping of height of sludge interface. Also, we compared conventional circle settling basin to improved circle settling basin the water treatment efficiency. Result of research, when SVI is average 117, improvement rate of SS and BOD were 51.0%, 37.0% approximately compared to conventional settling basin. And when SVI is average 178, improvement rate of SS and BOD were 22.7%, 36.0% approximately. Also when SVI is average 196, improvement rate of SS and BOD were 24.7%, 30.3% approximately. When it's winter, improvement rate of SS, BOD, COD, TN and TP were 20.6%, 17.9%, 13.9%, 13.5%, 12.4% approximately. Therefore, we can be the judge, this improved settling basin can be used as the final settling basin in the waste water treatment plant.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.1-10
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• 2008

We patterned water quality of agricultural reservoirs according to the differences of six physico-chemical environmental factors (TN, TP, DO, BOD, COD, and SS) using four different ordination methods: Principal Components Analysis (PCA), Detrended Correspondence Analysis (DCA), Nonmetric Multidimensional Scaling (NMS), and Isometric Feature Mapping (Isomap). The data set was obtained from the water quality monitoring networks operated by the Ministry of Agriculture and Forestry and the Ministry of Environments. Chlorophyll-${\alpha}$ displayed the highest correlation with COD, followed by TP, BOD, SS, and TN (p<0.01), while negatively correlated with altitude and bank height of the reservoirs (p<0.01). Although four different ordination methods similarly patterned the reservoirs according to the gradient of nutrient concentration, PCA and NMS appeared to be the most efficient methods to pattern water quality of reservoirs based on the explanation power. Considering variable scores in the ordination map, the concentration of nutrients was positively correlated with Chl-${\alpha}$, while negatively correlated with altitude and bank height. These ordination methods may help to pattern agricultural reservoirs according to their water quality characteristics.