• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.2
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• pp.187-198
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• 2018

The monthly salinity maps from Aquarius satellite covering the entire East Sea were produced to analyze the low-salinity water appearing in fall every year. The low-salinity water in the northern East Sea began to appear in May-June, spreading southward along the coast and eastward north of the subpolar front. Low-salinity water from the East China Sea entered the East Sea through the Korea Strait from July to September and was mixed with low-salinity water from the northern East Sea in the Ulleung Basin. The strength of the low-salinity water from the East China Sea was dependent on the strength of the southerly wind of the East China Sea in July-August. The salinity reaches a minimum in September with a distribution parallel to the latitude of $37.5^{\circ}N$. In October, low salinity water is distributed along the mean current path and subpolar front and the entire East Sea is covered with the low salinity water in November. Water with salinity larger than 34 psu starts to flow into the East Sea through the Korea Strait in December and it expands gradually northward up to the subpolar front in January- February.

• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.57-64
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• 2013

In this paper, in order to solve high water content of water sludge and promote its recycle, sludge mixtures with various mixing ratios were produced. Sludge mixture consisted of water sludge and weathered granite soil. Their physical properties and unsaturated characteristics (soil-water characteristic curve, and unsaturated permeability function) were investigated by laboratory tests. Experimental test results indicated that at a given matric suction volumetric water content of sludge mixture increased as water sludge content increased. Air entry values of sludge mixture increased from 0.9 kPa to 2.4 kPa with an increase in water sludge content or fine content. In addition, unsaturated permeability function, which is an important factor for performing infiltration analysis, was predicted using saturated permeability and soil-water characteristic curve of sludge mixture.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1016-1023
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• 2006

The water content of dewatered cake produced from belt press dewatering equipment was about 75 wt% which was some high to handle it, so the equipment contained a limit at the economical and environmental aspect. The thermal dewatering equipment built as an alternative to overcome several problems was set up at the sludge treatment field and estimated some feasibility as comparison with the dewatering performance of belt press. First, dewatering properties of waterworks sludge was analyzed by monthly. The sludge of a water shortage season contained a high organic content which led to be difficult to dewater the cake, the other side the sludge of rainwater season was ease to dewater because of low organic content. According to the results to analysis the water content of dewatered cake produced from two equipments on the base of the seasonal dewatering properties, the water content of dewatered cake produced from thermal dewatering for sludge of water shortage season was $41.6{\sim}48.3$ wt% and $71{\sim}84$ wt% from belt press. In the case of rainwater season, the water content of dewatered cake produced from thermal dewatering was $34{\sim}37.7$ wt% and $57{\sim}70$ wt% from belt press. It was understood that thereduction of water content of cake by thermal dewatering was larger than belt press. The economical aspect for two equipments was evaluated on considering the reduction of cake treatment amount as the decrease of water content of cake. When putting the cost index of thermal dewatering into 100, belt press was 121. This meant that thermal dewater was more economical than belt press by about 20% in the side of construction and operation. In conclusion, thermal dewatering equipment was estimated by producing the low water content dewatered cake as well as being operated with low coat.

• 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.

• Journal of the Korean Solar Energy Society
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• v.24 no.1
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• pp.13-19
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• 2004

Four solar stills that were fabricated each with cubes and glazing tilted angles of $15^{\circ},\;30^{\circ},\;45^{\circ},\;60^{\circ}$, were compared with the quantities of condensed water. The quantifies of condensed water were analysed with the weather conditions and temperatures for three months. On fine days, the quantify of average condensed water was more similar to those of $15^{\circ}$ and $30^{\circ}$ than to those of $45^{\circ}$ and $60^{\circ}$. The quantity of condensed water produced by those of $45^{\circ}$ and $60^{\circ}$ were very irregular compared to those of $15^{\circ}$ and $30^{\circ}$. On rainy days, the quantify of condensed water was the most in that of $30^{\circ}$ than those of the other angles and in cloudy, rainy and sunny conditions, the condensation quantify was the largest in that of $60^{\circ}$.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.04a
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• pp.24-28
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• 1990

The purpose of this study is to examine through the experimental study whether the water cooled unprocessed blast furnace slag produced in the country is useful for the fine aggregate of concrete or not. The results of this study show that the quality of the water cooled blast furnace slag is inferior to that of natural river sand and that the concrete made by substituting the water cooled blast furnace slag for fine aggregate have a tendency to decrease to some extent in strength. But if the water cooled blast furnace slag is transformed into more hardened state material, to use it as the fine aggregate of concrete will be possible.

• Microbiology and Biotechnology Letters
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• v.21 no.6
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• pp.622-627
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• 1993

Rhodospirillum rubrum P17 was used to investigate the pontential for the treatment of soybean curd waste and for the utilization of the biomass produced. The maximal biomass production and COD removal from the waste water were obtained at 30C, pH 7.0 under 2,500lux production and 50 rpm of agitation. The initial COD level of the soybean curd waste water was 3,240mg/l, and after 4 days of cultivation in batch culture, 3.46g/l of cells was obtained and COD level of the waste water reduced to 150mg/l (COD removal rate 95.4%).

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.235-238
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• 2003

In this study, we developed Open Water Management Program (OWMP) with an open architecture to deal with newly arising upgrade problems for a water management automation system. When we executed OWMP with data produced from an experimental field in Korea, the relative errors of this simulation were less than 5%. We developed runoff calculation model and verified it with measured data of 4 basins included in IHP. The relative errors came out less than 5% in all basins, except for one basin. We also applied OWMP to seongju irrigation reservoir to simulate daily runoff from 1998 to 2002, and the day, month, and year relative error between measured and simulated value was 0.25-0.05. Therefore the OWMP can be a tool nicely adapted to the optimal water management of irrigation reservoir.

• Spatial Information Research
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• v.4 no.2
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• pp.147-157
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• 1996

A rural water quality management information system(RWQMIS) by integrating Geo¬graphic Information System(GIS) with the existing models (pollutants transport and river water quality) is described. A simple pollutant load model to calculate delivered pollutants to stream, Tank model to generate daily runoff and QUAL2E model to predict river water quality, were incorporated into GIS. The system was applied to $80km^2$ watershed in Icheon Gun and Yongin Gun, Kyonggi Do. The spatial distributions of produced pollutant load, discharged pollutant load, delivered ratio to the stream, and the river water quality status for given sites were successfully generated.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.45-49
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• 2001

To maintain the freshness of produce, because of stand away between produced and consumer, we need refrigeration system that can supply to consumer at cold chain as soon as gathering. General refrigeration system consist of refrigeration chamber or low temperature store. But the vacuum technology can rapidly refrigeration without refrigerator. This precool system possible to get low precooled temperature, suitable for the fishes, the meat, the vegetables, the fruit etc. Especially get advantage that quality maintain through rapid refrigeration of ferment directly generate heat. Vacuum precool system's principle is that water saturated temperature reduce according to pressure is get to vacuum area, so product temperature reduce as water evaporation at product. In vacuum suction, unit, on early experiment period run the rotary type vacuum pump at purpose pressure, then maintain pressure by water-diven ejector. As the results, cabbage took about 60 minutes to reach from $23.2^{\circ}C$ to $4.5^{\circ}C$at 5mgHg abs.