• Clean Technology
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• v.28 no.1
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• pp.46-53
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• 2022

The agglomeration characteristics of coal and silica sand were investigated under various conditions using mixed samples consisting of coal, silica sand, and potassium hydroxide, which is an agglomeration accelerator. The samples were prepared by either physically mixing or using aqueous solutions. The experiments using the physically mixed powder samples were performed with a two hour reaction time. The results showed that the number of aggregates generated increased as the reaction temperature and the total potassium content increased. The experiments using aqueous solutions were performed at 880 ℃, which is the operating temperature of a fluidized bed boiler, and at 980 ℃, which assumes a local hot spot. The amount of agglomeration generated as the reaction time increased and the total potassium content increased was identified. In the experiment performed at 880 ℃, the amount of aggregate generated clearly increased with the reaction time, and in the experiment performed at 980 ℃, assuming a local hot spot, a large amount of aggregate was generated in a relatively short time. The aggregates became harder as the potassium content increased. When the total potassium content was less than 1.37 wt.%, the aggregates were weak at both temperatures and collapsed even with a slight impact. Additionally, the surface characteristics of the silica sand and ash aggregates were observed by SEM-EDS analysis. The analysis revealed a large amount of potassium at the bonding sites. This result indicates that there is a high possibility of aggregation in the form of a eutectic compound when the alkali component is increased.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.5
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• pp.34-40
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• 2001

In this paper, a narrowband active noise control system to reduce the noise in thermal power plants is proposed. The narrowband active noise control system contains rectangular wave generator and has a multi channel feed forward adaptive algorithms which uses the adjoint LMS algorithm. Although the effectiveness have been proven in the filtered-X LMS broadband active noise control system, this algorithm has much more computational complexity than that of narrowband active noise control system. The proposed active control system that uses the adjoint LMS algorithm, compared to the previous broadband active noise control system, not only is more effective in controlling narrowband noise but also has a more stable structure. Adaptive filter contains the FIR structure and IIR structure for primary and secondary path models. The simulation proves the effectiveness of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.382-383
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• 2008

현재 가정이나 산업용으로 사용하는 가스 화기나 보일러 등에서 가스 누출에 의한 화재사고나 폭발사고가 빈번하게 발생하고 있다. 가스 누출에 의한 사고는 오랜 시간 가스 누출 후 점화원에 의한 폭발이나 화재사고가 대다수를 차지한다. 일반적으로 천연가스를 사용하는 경우 상단부에 가스누출검지기를 설치하고 있다. 하지만 이러한 설치 위치는 대략적인 가스의 특성을 고려한 것이다. 본 연구에서는 가스 누출이 발생할 수 있는 누출위치를 가정의 가스레인지 화구와 밸브 연결부로 선정하고, 전산유체역학(CFD)을 이용하여 가스누출검지기의 시간에 따른 응답특성을 파악하여, 빠른 가스 검지를 위해 가스누출검지기 설치 위치를 최적화하였다. 본 연구의 결과를 기초로 가정이나 건물의 가스누출검지기출 설치할 경우, 가스가 누출되었을 때 신속한 검지를 통하여 위험을 알림으로서 가스폭발이나 사고를 미연에 방지할 수 있을 것이다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.188-190
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• 2012

고전단력을 갖도록 개발된 Homogenizer를 이용해 IFO 380cst Bunker-C 시료를 미립화 및 균질화하는 전처리를 시행하였다. 전처리된 시료의 슬러지 저감효과를 확인하기위하여 유청정기(oil purifier)를 이용하였고, 실험결과 약 13% 가량 슬러지 생성이 감소하는 것을 확인하였다. 또한, 전처리 후 유청정기를 통과한 시료를 실제 보일러 시스템에서 연소시켜 연소 성능 특성을 확인한 결과 CO가 감소하는 경향을 확인하였다. 선박운항비용 분석을 통해 U.L.C.C 기준 연 8,800만원 가량의 연료비 절감 효과가 있을 것으로 추정된다.

• Journal of the Korean Wood Science and Technology
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• v.39 no.1
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• pp.41-52
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• 2011

This study was carried out to investigate the effect of energy saving and sound insulation of building materials mixed with charcoal. To investigate the functionality of building based on the difference of construction materials, three different experimental buildings were constructed. They were buildings built with the conventional construction materials (A), the charcoal construction materials (B), and the charcoal-sericite construction materials (C). The study showed that energy consumption could be reduced approximately 9.5% and 14.5% by replacing A with B and C, respectively. Especially, it is revealed that the lower outdoor temperature was, the higher energy saving effect was. Also, after shutoff the boiler switch the decrease rate of room temperature of the one using B was lower than those of others using A and C so that the room temperature at the building using B was higher by $3.5{\sim}4.2^{\circ}C$ in the 1 meter air above the ground and by $4.4{\sim}5.4^{\circ}C$ on the floor surface after 12 hours passed. In the building noise test the heavy-and light-weight impact sound of the plate, represented by criterion of noise between floors in multi-story building, tended to decrease in the test sample containing charcoal.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.89-96
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• 2015

Recently, much research has been put into finding the causes and solutions of slagging/fouling problems that occur at the end of the boiler. This slagging/fouling, caused by low-rank coal's ash, disturbs the thermal power and greatly reduces efficiency. In environmental aspects, such as NOx pollution, governments have been implementing restrictions on the quantity of emission gases that can be released into the atmosphere. To solve these problems, research on Ash Free Coal (AFC), which eliminates ash from low-rank coal, is in progress. AFC has advantages over similar high-rank coals because it increases the heating value of the low grade coal, reduces the contaminants that are emitted, and decreases slagging/fouling problems. In this study, using a DTF, the changes of NOx emissions, unburned carbon, and the characteristics of ash deposition were identified. KCH raw coal, AFC extracted from KCH, residue coal, Glencore, and Mixed Coal (Glencore 85wt% and residue coal 15wt%) were studied. Results showed that AFC had a significantly lower emission of NOx compared to that of the raw coal and residue coal. Also, the residue coal showed a higher reactivity compared to raw coal. And finally, In the case of the residue coal and mixed coal, they showed a lower ash deposition than that of low-rank coal.

• Clean Technology
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• v.24 no.4
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• pp.339-347
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• 2018

In order to cope with environmental problems and climate change caused by fossil fuels, renewable energy supply is increasing year by year. Currently, waste energy accounts for 60% of renewable energy production. However, waste has a lower calorific value than fossil fuels and contains various harmful substances, which causes serious problems when applied to power generation boilers. In particular, the chlorine in the waste fuel increases slagging and fouling of boiler heat exchangers, leading to a reduction in thermal efficiency and the main cause of high temperature corrosion, lowering facility operation rate and increasing operating cost. In this study, the high temperature corrosion experiments of superheater materials (ASME SA213/ASTM A213 T2, T12 and T22 alloy steel) by alkali chlorides were conducted, and their corrosion characteristics were analyzed by the weight loss method and SEM-EDS. Experiments show that the higher the temperature and chloride content, the more corrosion occurs, and KCl further corrodes the materials compared to NaCl under the same condition. In addition, the higher the chromium content of the material, the better the corrosion resistance to the alkali chlorides.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.6
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• pp.467-472
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• 2021

In this paper, the ignition trans used in the gas boiler was produced to measure current, power factor, and power consumption. As a result of measuring the power factor, the self-made ignition trans was higher than that of foreign products and the power consumption was lower. The ignition gap was fixed to 2 m, and when the ignition rod length was 30cm, 500cm, and 1000cm, it was measured as 3.45A, 14.5A, and 16.2A. When the ignition gap was fixed to 4mm and the ignition rod length was 30cm, 500cm, and 1000cm, it was measured as 2.8A, 10.1A, and 13.2A. When the ignition gap was fixed at 6mm and the ignition rod length was 30cm, 500cm, and 1000cm, it was measured as 2.73A, 10.2A, and 32.6A. When the ignition gap was fixed at 8 mm and the ignition rod length was 30 cm, 500cm, and 1000cm, it was measured as 3.13A, 9.37A, and 21.4. The ignition gap was fixed at 10 mm, and when the ignition rod length was 30cm, it was measured as 3.4A, 14.4 A, and 25.6A. In conclusion, as the length of the ignition rod increased, the current also increased.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.366-375
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• 2022

The monitoring of electricity consumption using Internet of Things (IoT) technology is attracting attention as a technology to reduce operation costs of smart farms. In this study, we propose a method to apply a real-time electrical consumption monitoring system (the e-Gauge system) and utilization of the collected data real-time while a melon-producing smart farm is in operation. For this purpose, the electrical consumption data for the individual smart-farm facilities such as boilers, nutrient distribution systems, automatic controllers, circulation fans, boiler controllers, and other IoT-related utilities were collected during three months of melon cultivation period. By using the monitoring results, the electrical energy consumption pattern was analyzed as an example, and necessary considerations needed to optimally utilize the measurement data were suggested. This paper will be useful in lowering the technological implementation barriers for new researchers to build a electrical consumption monitoring system and reducing trial and errors in the usage of the generated data.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.29-42
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• 2016

This study analyzes the economic efficiency of utilizing hot waste water at a thermoelectric power plant, which is part of recent projects supported by the Korean government to foster new energy industry. The author proposes an institution that provides economic incentives to promote the project. Based on a method of calculating Levelized cost of energy (LCOE), this study finds that the LCOE of using hot waste water at power plants is higher than that of oil boiler, biomass and a power plant's auxiliary steam but similar to that of the geothermal system. Also, according to sensitivity analysis on the LCOE of each element in the system of using hot waste water, a distance of heat supply is most sensitive. Therefore, this study shows that when the government devises an incentive-based institution to expand the project of utilizing hot waste water, it is necessary to establish Renewable Energy Certificate (REC) weights that are differentiated by a distance of heat supply.