• Korean journal of food and cookery science
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• v.20 no.1
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• pp.34-41
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• 2004

The retention rate of riboflavin in two cooked vegetable salads (spinach salad and sesame leaf salad) were examined at every cooking stage, holding temperature and holding time, with various cooking methods, and a better food preparation method developed. The riboflavin contents of the samples were analyzed by HPLC, with fluoresence detection. The changes in the pH and water contents of the samples were measured during the holding stage at various temperatures and times. There were significant differences in the riboflavin contents during the various preparation and cooking processes, such as trimming, washing, boiling and parching etc. The retention rates of the riboflavin with the various holding methods and cooking temperature were also significantly different. The boiling process caused large losses of riboflavin: in the cases of spinach salad and sesame leaf salad these were 78％ and 52％ respectively. The pH and water contents showed faster change during 0-6 hours than during 6-12 hours.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.6
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• pp.400-402
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• 2015

The typical winter heating unit heating mat. The product is to be found in the development of new water heating mat today. The product that circulates the water through the hose inside the mat with your existing heating mat electric heated mat is different from boiling water. However, no clear standards for noise and safety, consumer choice is giving confusing information about the product is low. We were to develop a high heat retention and stability than conventional sleeping mats to produce creative than traditional hot mats, heated mats general comparison with experimental results is a more efficient heat retention mat is produced.

• Environmental Engineering Research
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• v.22 no.2
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• pp.203-209
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• 2017

Innovations in the biofiltration process can provide effective solutions to overcome crucial water pollution problems. The elimination of pollutants is a result of the combined effects of biological oxidation, adsorption and filtration processes. This research aims to evaluate the performance of quartz sand biofiltration for removing total suspended solids, turbidity, color, organic matter, and ammonium from polluted river water and develop an empirical model for designing quartz sand biofilters for the treatment of polluted river water. Experiments were conducted using two biofilter units filled with quartz sand as filter media. A set of experiments were performed to evaluate the effect of hydraulic retention time on biofilter performance in removing water contaminants. The kinetics of organic matter removal were also determined to describe the performance of the biofilter. The results show that biofiltration can significantly remove river water pollutants. Removal efficiency depends on the applied hydraulic retention time. At a hydraulic retention time of two hours, removal efficiencies of total organics, ammonium and total suspended solids were up to 78%, 82%, and 91%, respectively. A model for designing quartz sand biofiltration has been developed from the experimental data.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.6
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• pp.335-343
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• 2002

Methods of bedsoil analysis were difficult to be applied universally because use and material of bedsoil are diverse from country to country. Korean Standard Methods for Bedsoil Analysis was developed to measure the water content, water retention, and saturated hydraulic conductivity. Fifty-three samples for horticultural bedsoil and nine samples for paddy rice bedsoil in the current market were collected. Water content of bedsoil was determined using gravimetric method through $105^{\circ}C$ oven-dry for 16 hours, but different calculations between horticultural and paddy rice bedsoils were chosen according to different predominant component, plant residue or mineral. Water content percentage of horticultural bedsoil was calculated as [(weight of sample before oven-dry - weight of sample after oven-dry)/(weight of sample before oven-dry)]${\times}100$, while that of paddy rice bedsoil as [(weight of sample before oven-dry - weight of sample after oven-dry)/(weight of sample after oven-dry)]${\times}100$. Water retention was measured at water potential -0.5, -1, -3, -5, -7, -10 kPa by Sandbox method and saturated hydraulic conductivity was measured by constant head method using acryl cylinder (${\Phi}5cm{\times}L\;20cm$). By new 'Korean Standard Methods of Bedsoil Analysis', the average water content of horticultural bedsoil was obtained 46.34%(w/w) and that of paddy rice bedsoil 16.89%. For horticultural bedsoil, easily available water(EAW), water buffering capacity(WBC), and optimal matric potential(OMP) was estimated at 28.4%, 7.01%, and -5.60 kPa, respectively. Optimal moisture content was 44.41% and average saturated hydraulic conductivity for bedsoils was estimated at $28.4cm\;min^{-1}$.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.4
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• pp.471-478
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• 2012

The role of moisture absorptive capacity of pre-silage material and its relationship with silage effluent in high moisture by-product feedstuffs (HMBF) is assessed. The term water retention capacity which is sometimes used in explaining the rate of effluent control in ensilage may be inadequate, since it accounts exclusively for the capacity of an absorbent incorporated into a pre-silage material prior to ensiling, without consideration to how much the pre-silage material can release. A new terminology, 'potential water retention capacity' (PWRC), which attempts to address this shortcoming, is proposed. Data were pooled from a series of experiments conducted separately over a period of five years using laboratory silos with four categories of agro by-products (n = 27) with differing moisture contents (highest 96.9%, lowest 78.1% in fresh matter, respectively), and their silages (n = 81). These were from a vegetable source (Daikon, Raphanus sativus), a root tuber source (potato pulp), a fruit source (apple pomace) and a cereal source (brewer's grain), respectively. The pre-silage materials were adjusted with dry in-silo absorbents consisting wheat straw, wheat or rice bran, beet pulp and bean stalks. The pooled mean for the moisture contents of all pre-silage materials was 78.3% (${\pm}10.3$). Silage effluent decreased (p<0.01), with increase in PWRC of pre-silage material. The theoretical moisture content and PWRC of pre-silage material necessary to stem effluent flow completely in HMBF silage was 69.1% and 82.9 g/100 g in fresh matter, respectively. The high correlation (r = 0.76) between PWRC of ensiled material and silage effluent indicated that the latter is an important factor in silage-effluent relationship.

• Korean journal of food and cookery science
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• v.18 no.4
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• pp.461-469
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• 2002

In order to develop a better food preparation method in terms of vitamin retention in food service establishments, the retention rate of riboflavin in two kinds of Korean dish (stir-fried sausage with vegetables, stir-fried garlic young stems) were examined during various cooking stages, holding temperature and duration time. Riboflavin content of the sample was analyzed using by using a HPLC with a fluorescent detector at various holding durations and temperatures. Also the changes in the pH and water contents of the samples were measured during holding at various temperatures to find any relation among the pH, water contents and riboflavin content. In the results, there were significant differences in riboflavin contents at various cooking processes such as washing, slicing, blanching, soaking, etc. Also, the retention rates of riboflavin at various holding methods and temperature were significantly different from one another. Especially 50% reduction of riboflavin content occurred during blanching of young garlic stem and only 38% of riboflavin was left after slicing carrots for stir-frying of sausage.

• Journal of Environmental Science International
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• v.1 no.2
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• pp.49-57
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• 1992

First, We classified man-made lakes in Korea as 4-type lakes, that is, there were River-run lakes, Dendritic lakes, Reservoir-lakes, River-mouth lakes, We studied on the environmental factors of 3-type lakes except River-mouth lakes, compared these lakes with natural lakes in foreign country. Environmental factors were watershed area, lake storage, mean depth, hydraulic retention time. As a results, 3-type lakes in Korea had remarkable differences one another according to above-mentioned environmental factors. First, We recognized that River-run lakes had higher nutrient loading according to having wider watershed area than natural lakes, and had lower algal growth rate according to shorter hydraulic retention time than natural lakes. Dendritic lake had higher nutrient loading than natural lakes, longer retention time than River-run lake. Reservoir-lakes had environmental factors between Dentritic lakes and River-run lakes. Therefore, If this studies had no quantitative results about various factors, We recognized that man-made lakes in korea had different environmental factors as compared with natural lakes, and had clear classification among 3-type lakes.

• Journal of Korean Society of Rural Planning
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• v.30 no.2
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• pp.69-77
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• 2024

As impervious area increases due to urbanization, rainfall on the impervious area does not infiltrate into the ground, and stormwater drains quickly. Low impact development (LID) practices have been suggested as alternatives to infiltrate and store water in soil layers. The practices in South Korea is applied to urban development projects, urban renewal projects, urban regeneration projects, etc., it is required to perform literature research, watershed survey, soil quality, etc. for the LID practices implementation. Prior to the LID implementation at fields, there is a need to simulate its' effect on watershed hydrology, and Storm Water Management Model (SWMM) provides an opportunity to simulate LID practices. The LIDs applied in South Korea are infiltration-based practices, vegetation-based practices, rainwater-harvesting practices, etc. Vegetation-based practices includes bio-retention cell and rain garden, bio-retention cells are mostly employed in the model, adjusting the model parameters to simulate various practices. The bio-retention cell requires inputs regarding surface layer, soil layer, and drain layer, but the inputs for the drain layer are applied without sufficient examination, while the model parameters or inputs are somewhat influential to the practice effects. Thus, the approach to simulate vegetation-based LID practices in SWMM uses was explored and suggested for better LID simulation in South Korea.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.6
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• pp.815-824
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• 2011

In this study, a non-thermal plasma system was employed to simultaneously remove odorous compounds and organic sludge. The system consisted of two reactors; the first one was the non-thermal plasma reactor where ozone was produced by the plasma reaction and the ozone oxidized hydrogen sulfide, the model odorous compound, and then the ozone-laden gas stream was introduced to the second reactor where wasted sludge was disintegrated and solubilized by ozone oxidation. In this study, the gas retention time (GRT) and the hydraulic retention time (HRT) were changed in the two-reactor system, and the effects of GRT and HRT on reduction efficiencies of odor and sludge were determined. As the GRT increased, the ozone concentration increased resulting in an increasing efficiency of hydrogen sulfide removal. However, the overall ozone loading rate to the second sludge reactor was the same at any GRT, which resulted in an insignificant change in sludge reduction rate. When HRTs in the sludge reactor were 1, 2, 4 hours, the sludge reduction rates were approximately 30% during the four-hour operation, while the rate increased to 70% at the HRT of 6 hours. Nevertheless, at HRTs greater than 4 hours, the solubilization efficiency was not proportionally increased with increasing specific input energy, indicating that an appropriate sludge retention time needs to be applied to achieve effective solubilization efficiencies at a minimal power consumption for the non-thermal plasma reaction.

• Advances in concrete construction
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• v.6 no.6
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• pp.561-583
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• 2018

A variety of polycarboxylate ether (PCE)-based superplasticizers are commercially available. Their influence on the rheological retention and slump loss in respect of concrete differ considerably. Fluidity and slump loss are the cardinal features responsible for the quality of concrete. These are related to the dispersion of cement particles and the hydration process which are greatly influenced by type of polycarboxylate ether (PCE)-based superplasticizers. On the backdrop of relatively less studies in the context of rheological retention of high strength self-consolidating concrete (HS-SCC), the experimental investigations were carried out aiming at quantifying the effect of the six different PCE polymers (PCE 1-6) on the rheological retention of HS-SCC mixes containing two types of Ordinary Portland Cements (OPC) and unwashed crushed sand as the fine aggregate. The tests that were carried out included $T_{500}$, V-Funnel, yield stress and viscosity retention tests. The supplementary cementitious materials such as fly ash (FA) and micro-silica (MS) were also used in ternary blend keeping the mix paste volume and flow of concrete constant. Low water to binder ratio was used. The results reveal that not only the PCEs of different polymer groups behave differently, but even the PCEs of same polymer groups also behave differently. The study also indicates that the HS-SCC mixes containing PCE 6 and PCE 5 performed better as compared to the mixes containing PCE 1, PCE 2, PCE 3 and PCE 4 in respect of all the rheological tests. The PCE 6 is a new class of chemical admixtures known as Polyaryl Ether (PAE) developed by BASF to provide better rheological properties in even in HS-SCC mixes at low water to binder mix. In the present study, the PCE 6, is found to help not only in reduction in the plastic viscosity and yield stress, but also provide good rheological retention over the period of 180 minutes. Further, the early compressive strength properties (one day compressive strength) highly depend on the type of PCE polymer. The side chain length of PCE polymer and the fineness of the cement considerably affect the early strength gain.