• Transactions of the Korean hydrogen and new energy society
• /
• v.22 no.1
• /
• pp.13-20
• /
• 2011

$SO_2$ has been absorbed and separated selectively by an ionic liquid from $SO_2/O_2$ mixture decomposed from sulfuric acid during the thermochemical SI cycle for the water splitting. In order to design and operate high pressure $SO_2/O_2$ separation system, the solubility of $SO_2$ in [EMIm]$EtSO_4$ (1-ethyl-3-methylimidazolium ethylsulfate) has been measured by Magnetic Suspension Balance at high pressure and temperature. Based on the measured solubility, a pressurized separation system was set up and operated. 194 L/h of $SO_2$($SO_2:O_2$=0.65:1) has been separated with 99.85% of $O_2$ at the vent of absorption tower, which is 22.7% of the theoretically ideal capacity of the system. This discrepancy results from the reduced contact between the gaseous $SO_2$ and the ionic liquid. Increased $SO_2$ supply, scale-up of the absorption column, and a faster ionic liquid circulation speed were suggested to improve the separation capacity.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.17 no.4
• /
• pp.4001-4008
• /
• 1975

The economic evaluation of the feasibility of expanding fully irrgated agriculture in the Ogseo project must consider preproject yields of rice under rainfed and partially irrigated paddy cultivation in order to assess incremental incomes from irrigation. Statistical data on yields available from official sources and field surveys conducted in the project area do not specify whether given unit yields refer to actually cropped or potentially cropped lands. This latter factor obviously affects any evaluation of marginal benefits to be derived from irrigation as the extent of rainfed areas actually cropped varies from year to year according to rain fall at the critical growth periods for low land rice. Although less dependent on direct rainfall, yields from partially irrigated lands are also highly affected by seasonal rainfalls. In this paper on attempt has been made to determine average yield under rainfed and partially irrigated conditions by relating yields to a available water. For rainfed paddy cultivation, the analysis discriminates between effects of rain deficiencies during transplanting and subsquent growth periods. For partially irrigated paddy cultivation, seasonal rainfalls have been considered, implying sufficient storage capacity for supplementary irrigation. The average yield of rainfed paddy has been calculated as 2.11 t/ha and that of partially irrigated paddy as 2.8 t/ha. Assuming even division between these two water supply patterns of areas not fully irrigated, a composite yield of 2.46 t/ha is oftained. This figure will be adopted as the basis for the on-going studies and project evaluation.

• Tunnel and Underground Space
• /
• v.22 no.1
• /
• pp.1-11
• /
• 2012

Thermal energy storage is defined as the temporary storage of thermal energy at high or low temperatures for later use in need. The energy storage can reduce the time or rate mismatch between energy supply and demand, and thus it plays an important role in conserving energy and improving the efficiency of energy utilization, especially for renewable energy sources which provide energy intermittently. Underground thermal energy storage (UTES) can have additional advantages in energy efficiency thanks to low thermal conductivity and high heat capacity of surrounding rock mass. In this paper, we introduced the technologies of underground thermal energy storage and rock caverns for hot water storage in Sweden.

• Journal of Korea Soil Environment Society
• /
• v.4 no.1
• /
• pp.119-126
• /
• 1999

This study was carried out to estimate the effect of forest fire on physical and chemical properties of soil The forest fire was in April 1995 at Kongju of Chungnam. Soil samples were collected at 0~5cm, 5~10cm, and 10~20cm soil depths in September 1998 from the burned and unburned sites. Soil organic matter concentrations at 0~5cm and 5~10cm soil depths were significantly greater in unburned site than in burned site. Soil concentrations were greater in unburned site than in burned site at all soil depths. Cation exchange capacity was significantly higher in unburned site than in burned site at 0~5cm soil depth. There were no differences in available soil P, exchangeable soil K, Ca, and Mg, and pH of soil between burned and unburned sites. Soil water content at 0~5cm soil depth was significantly greater in unburned site than in burned site. Bulk density at 0~5cm soil depth was significantly higher in burned site than in unburned site. Forest fire had an adverse effect on physical and chemical properties of soil in this study, Burning of vegetation and forest 리oor organic matter in burned site may reduce organic matter supply to soil and increase soil erosion. Consequently, forest fire may have adverse influence on long-term site productivity.

• Journal of the Korean Solar Energy Society
• /
• v.36 no.4
• /
• pp.21-29
• /
• 2016

Commercial wind farm design tools and the national wind map are used to determine the implementation potential of offshore wind power in Korea in this study. For this, the territorial waters of Korea were divided into nine analysis regions and a commercial CFD code was used to obtain wind resource maps at 100m A.S.L. which is the hub height of a 5MW wind turbine used in this study. With the wind resource obtained, factors including water depth, distance from substations, minimum and maximum capacity of a wind farm, distance between turbines and wind farms were considered to determine wind power potential. Also, the conservation areas, military zones, ports, fishing grounds, etc. were considered and excluded. As the result, a total capacity of 6,720 MW was found to be the implementation potential and this corresponds to $3.38MW/km^2$ in API. Also if the distance from the substation is not considered, the potential increased to be 10,040 MW. This offshore wind farm potential is considered enough to satisfy the target of wind farm capacities in the 7th national plan for electricity demand and supply.

• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.3
• /
• pp.43-48
• /
• 2019

Since the revision of the Rationalization of Energy Use Law, the spread of new and renewable energy in buildings has been promoted. In addition, the production of electric power and thermal energy is an important issue in the change of energy paradigm centered on the use of distributed energy. Among them, geothermal energy is attracting attention as a high-performance energy-saving technology capable of coping with heating / cooling and hot water load by utilizing the constant temperature zone of the earth. However, there is a disadvantage that the initial investment cost is high as a method of calculating the capacity of a geothermal facility by calculating the maximum load. The disadvantages of these disadvantages are that the geothermal energy supply is getting stagnant and the design of the geothermal system needs to be supplemented. In this study, optimization design of geothermal system was carried out using optimization tool. As a result of the optimization, the ground heat exchanger decreased by 30.8%, the capacity of the heat pump decreased by 7.7%, and the capacity of the heat storage tank decreased by about 40%. The simulation was performed by applying the optimized value to the program and confirmed that it corresponds to the load of the building. We also confirmed that all of the constraints used in the optimization design were satisfied. The initial investment cost of the optimized geothermal system is about 18.6% lower than the initial investment cost.

• Journal of the Korean Professional Engineers Association
• /
• v.1 no.1
• /
• pp.18-25
• /
• 1968

Higher yield in rice paddies is greatly dependent on adequately balanced and timely supply of water. A majority of rice paddy in Korea is generally irrigated by rainfall, but in many cases it has to be supplemented by artificial irrigation for optimum rice culture. Although the water requirement of rice plant is for higher Than that of athec crops, submerged condition of rice paddy is not Necessarily required. The moisture requirement of rice plant varies with its growing stages, and it is possible to increase the irrigation efficiency through reduction of water loss due to percolation in rice paddies. An experimental plots were set up by means of sandomized block design with three duplication; (a) All time submerged, (b) Economically controlled, and (c) Extremely controlled. Three different irrigation periods Were (a) Initial sage, (b) Inter-stage, and (c) Yast stage. The topsoil of the three plots were excavated to the depth of 30 cm and then compacted with clay of 6 cm thickness. There after, they were piled up with the excavated top soils, leveled and cored with clay of 6 cm thickness around footpath in order to prevent leakage. The results obtained from the experiments are as follows, 1. There is no difference among the three experiments plots in terms of physical and chemical conditions, soil properties, and other characteristics. 2. Culm length and ear length are not affected by different irrigation methods. 3. There is no difference in the mature rate and 1, 000 grain weight of rice for the three plots. 4. The control plot which was irrigated every three days shows an increased yield over the all the time submerged plot by 17.8 percent. 5. The clay lined plot whose water holding capacity was held 5 days long, needs only to be irrigated every 7 days. 6. The clay lined plot shows an increased yield over the untreated plot ; over all-the-time submerged plot by 18 percent ; extremely controlled plot by 18 percent, and economically controlled plot by 33 percent. 7. It may be saved in water requirement about one Thirds.

• Journal of Bio-Environment Control
• /
• v.6 no.3
• /
• pp.159-167
• /
• 1997

To cope with the mass-production and supply of plug seedling, the supply of transplanters is necessary. In the study, a transplanting test was carried out to find the optimum working condition in the mechanizd transplantation and to acquire the basic data for the improvement of transplanters by the research and analysis of working capacity of the local manual transplanters. The size of hopper affected transplanting stand and rate. Re-irrigation was required for the transplanted seedlings because they wilt 1 day after the transplanting if soil compaction is incomplete. Consequently, back-forth-left-right compaction method was good for soil covering and compaction. It may be thought to increase the amount of irrigation water at the time of transplanting by double-irrigation mechanism, but it needs to increase the larger water tank which makes the operation uneasy. So, assuming the working model by 1 or 2 operators with the machine size as small as possible, it seemed that eliminating of automatic irrigation method was desirable in view of efficiency. Though semiautomatic transplanter needs some structural improvements, it seemed still suitable for transplanting of plug seedlings such as 45-day red pepper seedlings in 128-hole tray and 25-day Chinese cabbage seedling in 128-hole tray. If traveling speed of the transplanter is limited to less than 14 m/min, with the transplanting depth of 2~3cm and transplanting space of 30cm.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.14 no.3
• /
• pp.2741-2748
• /
• 1972

With 31 existing reservoirs selected in the Yong San River Basin, the sedimentation of the reservoirs has been calulated by comparing the precent capacity with original value, which revealed its reduced reservoir capacity. The reservoirs have a total catchment area of 13,871 ha. with a total capacity of 17.6 million cubic meter, and are short of water supply due to reduction of reservoir capacity. Annual sedimentation in the reservoir ranged from 120 to 3,770 cubic meter per square kilometer with great difference in its distribution, and the average value was 877 cubic meter. This wide disparity is analysed to come principally from the topography, geology, vegetation and hydraulics. The reservoir basin had a large portion of devastated land but has become green more and more in the last 10 years. It can be summarized that in the reservoirs with an average period of sedimentation of 26 years, the reduction rate of reservoir capacity amounts 12.5%, and 0.48% is shown for annual capacity reduction rate.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.24 no.1
• /
• pp.44-52
• /
• 1982

Recently, estuary reserovoirs have been actively constructed in Korea and also in Japan there are a large number of estuary reservoirs constructed. But most of the estuary reservoirs are located at the downstream of a river where geographical condition is best for the construction of an enclosing dam. And an effective utilization of water from the estuary reservoir seems to be difficult even if estuary reservoirs are considered to be the water resources the most available for their watershed. Studies on estuary reservoirs so far have been mainly concentrated on the physical and engineering problems of the dam construction itself. The purpose of the present study is to review the estuary reservoir planning in connection with the water resources development and to study a basis of the planning. First, the levels of water use in Korea and Japan were compared with those of other countries in the world. And then, some representative reservoirs were selected to study the roles of a reservoir and water-using conditions in the watershed. Based on the study, a survey was given on the relation between a dam construction upstream and an estuary reservoir construction downstream of a river. Finally, a comprehensive examination was made of the bases of estuary reservoir planning. (1) The estuary reservoir planning is deeply related to the plan for water use develo- pment in the watershed. After the upstream water resources were fully developed up to the most, water reso- urces development by an estuary reservoir should be started. (2) If an estuary lake has a capacity big enough, it can store flood discharge of the watershed without any loss and become a basic facility that will bring about the maxi- mum use of water from the watershed. (3) Estuary reservoirs store water used in the upstream watershed, so recycling of water use is attained by the reservoir. Water in the estuary lake is difficult to be fresh water in its long run. Therefore, estuary reservoir should be located at a place where polluted water is purified and refused. All the planning should be based on the assumption that water in the estuary lake is not fresh but polluted after a long time. (4) The estuary lake can only supply water to the lower basin directly. But the upstream area is benefited from the estuary lake by exchange of irrigation water sources between the lower and the upper area. So a large-scale exchange plan between new and existing water resources is important. By constructing estuary reservoirs and the exchange of water sources between upper and lower areas, the reasonable maximum use of water from the whole watershed is at- tained. (5) The big problem coming from the water resources development by an enclosing estuary is salt water intrusion into the lake. To maintain the estuary lake salt-free, multi-purpose use of the lake should be avoided. It is necessary to take such fundamental measures as abolition of back flow operation of gate, and the closing of the fish port and the fish ladder. The results mentioned above were found in this study and these results of this study could be used for the adequate planning of estuary reservoirs in connection with the maximum water use of the watershed.