• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.800-803
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• 2007

Gasification has been regarded as a core technology in dealing with environmental pollutants and in obtaining higher efficiency for power generation. Among several ways in utilizing produced syngas from gasification, power generation would be the most prominent application. Syngas from coal was applied to the readily available LPG engine from automobiles. Main purpose was to identify the combustion characteristics in the modified gas engine when using syngas of low heating value and to test the modification optionsin the LPG gas engine. Gas engine rpm and the corresponding flue gas composition were measured for each syngas input condition. Results showed that even with syngas at the heating value of $1300{\sim}1800$ kcal/$Nm^3$ corresponding to the $6{\sim}7%$ of LPG heating value, gas engine operated successfully only with the problems of high CO and oxygen concentrations in the flue gas.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.5
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• pp.473-479
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• 2017

This study was designed to understand characteristics of oxy-combustion of coal, dried sewage sludge and solid refuse fuel (SRF). Thermogravimetric analysis was conducted by burning the fuels with air, 21% oxygen ($O_2$)/79% carbon dioxide ($CO_2$) and 30% $O_2/70%$ $CO_2$. Heating rates were varied as 5, 10, 25, 40 and $100^{\circ}C/min$. Complete coal combustion was found at the heating rates of 5, 10, 25 and $40^{\circ}C/min$, and different combustion behavior was found with the gas composition at the heating rates of 10, 25, 40 and $100^{\circ}C/min$. Coal combustion with 30% $O_2/70%$ $CO_2$ showed the highest while coal combustion with 21% $O_2/79%$ $CO_2$ showed the lowest combustion rate. On the other hand, the combustion of dried sewage sludge and SRF showed similar combustion behavior with respect to the combustion gas composition. This suggests that oxy-combustion of dried sewage sludge and SRF which contain a large amount of volatile matter may show similar combustion behavior to their air combustion.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.223-228
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• 2017

Aluminum nitride (AlN) powder was successfully synthesized at low temperature via carbothermal reduction and nitridation (CRN) assisted by microwave heating. The synthesis processes of AlN powder were investigated with X-ray diffraction, FE-SEM, FT-IR and TGA/DSC. Aluminum nitrate was used as an oxidizer and aluminum source, urea as fuel, and glucose as carbon source. These starting materials were mixed with D.I water and reacted in a flask at $100^{\circ}C$ for 20 minutes. After the reaction was finished, black foamy intermediate product was formed, which was considered to be an amorphous $Al_2O_3$ particles through intermediate product obtained by solution combustion synthesis (SCS) at the results of X-ray diffraction patterns and FT-IR. This intermediate product was nitridated at temperatures of $1300^{\circ}C$ and $1400^{\circ}C$ in $N_2$ atmosphere by a microwave heating furnace and then decarbonated at $600^{\circ}C$ for 2 hours in air. It should be noticed from FE-SEM images that as nitridated particles, identified as AlN from X-ray diffraction patterns, are covered with carbon residues. After decarbonating the nitridated powders, the spherical pure AlN powders were obtained without alumina and their particle sizes were dependent on the nitridating temperature with high temperature of $1400^{\circ}C$ giving large particles of around 70~100 nm.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.32-37
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• 2007

Regarding the need of energy in advance and the depletion of fossil fuel energy, all researches around the world now are trying to extract energy from many alternative sources especially the renewable one. Solar, ocean tidal, wind and geothermal energy are renewable energy fields which many researches are focused on. This paper explains about effort to replace electric pump used in solar water heating system by bubble pump. The utilization of bubble pump in this system is very efficient since it needs heat energy for its operation that can be obtained easily. In addition, it can also simplify the construction of the system. Bubble pump also functions as a controller to circulate water inside the system. Before the installation of bubble pump, the special quality and performance of bubble pump should be analyzed. The result got from the analysis could show the fluctuation of water flow rate occurred because it sensitively reacts to the heat quantity. Here the heat quantity is taken from the solar that, as we know, is not stable in a whole day. Problems often occurred are the flow rate in this system is very low moreover it could be stop if the pressure exceeds the limit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.12 s.255
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• pp.1181-1187
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• 2006

Stringent regulations of exhaust emission from vehicles become a major issue in automotive industries. In SI engines, it is one of the crucial factor to reduce exhaust emissions during cold start in order to meet stringent regulations such as SULEV or EURO-4, because SI engines emit a large portion of total harmful exhaust compounds when they are cold. At early stages of cold start in gasoline engines, exhaust gas temperature plays a key role to improve three way catalyst by virtue of fast warmup. Therefore, this study focused on the increase of exhaust gas temperature under controls of engine operating parameters such as spark ignition timing, valve overlap by virtue of intake VVT and catalyst heating function. Furthermore, effects on harmful emission due to these parameters are also investigated. Experiments showed that retarded spark ignition timings and increased valve overlap may be helpful to increase exhaust gas temperature. It was also found that $NO_x$ was decreased with increased valve overlap. This study also showed that sudden changes in ISA and amount of fuel due to the deactivation of catalyst heating function cause temporal increase of harmful emissions.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2204-2209
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• 2008

Flame pattern in burner used in steel industry that constitutes 30% of country energy consumption is generally characterized as long narrow flame pattern so that localized heating causes product quality worse and many burners are needed for proper heating. This paper deals with flat wide flame pattern which has advantage in terms of uniform heating using less number of burners. For that purpose, impinging jet system of fuel and oxidant was used for making flat wide flame. Results show that nozzle angle $75^{\circ}$ of impinging jet is found to be optimum configuration for making effective wide flame which has uniform radiation heat transfer and flame temperature is also most uniform along the flame width for that nozzle angle.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.8
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• pp.418-425
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• 2015

The Korean government plans to establish large-scale horticultural facilities using reclaimed land to improve the competitiveness of the national agricultural sector at the government level. One of the most significant corresponding problems is the ongoing dependence of these facilities on fossil fuel, whereby constant heating is necessary during the winter season to provide the necessary breeding conditions for greenhouse crops. In particular, high-level energy consumption is incurred from the use of heating-related coverings with large heat-transmission coefficients such as those composed of vinyl and glass. This study investigated the potential applicability of waste-incineration heat for use in large-scale horticultural facilities by evaluating the hot-water temperature, heat loss, and available greenhouse area as functions of the distance between the incineration facility and the greenhouse. In conclusion, waste-incineration heat from a HDPE pipe can heat a horticultural facility of 10 ha if the distance is less than 8 km.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.104-117
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• 1998

Rising concern about climate change has evoked interest in the potential for urban vegetation to help reduce the level of atmospheric CO\sub 2\, a major heat-trapping gas. This study quantified the functio of home energy savings and carbon emission reduction by shading, evapotranspiration and windspeed reduction of urban vegetatioin in Chuncheon. Tree and shrub cover averaged approximately 13% in residential land. The effects of shading, evapotranspiration and windspeed reduction annually saved heating energy by 2.2% and cooling energy by 8.8%. The heating and cooling energy savings reduced carbon emissions by 3.0% annually. These avoided emissions equaled the amount of carbon emitted annually from fossil fuel consumption by a population of about 1,230. Carbon emission reduction per residential building was 55kg for detached buildings and 872 kg for multifamily buildings. Urban vegetation annually decreased heating and cooling energy cost by ￦1.1 billions, which were equivalent to annual savings of ￦10,000 savings and carbon emission reduction due to tree plantings in the wrong locations, while windspeed reduction had a great effect. Plantings fo large trees close to the west and east wall of buildings, full tree plantings on the north, and avoidance of shade-tree plantings or selection of solar-friendlytrees on the south were recommended to improve the function of building energy savings and carbon emission reduction by urban vegetation.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.4
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• pp.379-384
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• 2002

As automotive diesel engines adopt the direct injection method for a lower level of the exhaust emission and a higher fuel efficiency, the maximum temperature of engine coolant decreases. Consequently, the total available heat source from the engine coolant decreases over 35%. However, the heating source of air-conditioning system in automobiles depends on the hot engine coolant completely, so that it is nearly impossible to control air conditioning in heating season. Therefore, the present study has been carried out to develop the air conditioning system for the high efficient heat pump type using the HFC-134a. Especially, the air conditioning system of heating has been developed at a beginning stage, when it has low heat source from small and medium sized diesel recreation vehicles. To develop a control logic system for air conditioning system which is a heat pump type with a heat recovery exchanger, its cycle characteristics has been investigated according to the opening of LEV at a bench system.

• Journal of the Korean institute of surface engineering
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• v.52 no.1
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• pp.43-51
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• 2019

The environmental pollution which is global warming and abnormal climate is caused by increasing population and activated economics. To reduce environmental pollution, we have being efforts into reducing $CO_2$ emission and use of energy, resources. Especially, for the sake of light weight and fuel efficiency of automotive industry, many countries have defined the restrict environmental regulation which stipulate high magnitude of reducing $CO_2$ emission. In this study, we have predicted the problem of Mu-cell injection molding through the finite element analysis as a function of temperature controlled by Joule heating or in terms of mold temperature. From the result of finite element analysis, we have determined the optimized process and made the injection mold included electric current heating system with Mu-cell manufacturing. Lastly, we analyzed the surface characteristics of the injection products with mold temperature.