• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2119-2125
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• 1992

An air-fuel ratio control method is studied to keep the air-fuel ratio of the exhaust gas in the neighborhood of the stoichiometric air-fuel ratio to maximize the conversion efficiency of the three-way catalytic converter. Estimators, which estimate the air-fuel ratio of the exhaust gas, are proposed using neural networks to overcome the limit of the presently used bang-bang type exhaust gas oxygen sensor. Using these estimators, PI controller for air-fuel ratio control is designed and is experimented for an automobile engine. The proposed controller reduces the variation of air-fuel ratio of the exhaust gas from the stoichiometric air-fuel ratio by 50%-75% when compared to the existing controller.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.23-30
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• 2016

The conventional natural gas engine realized lean combustion for the improved efficiency. However, in order to cope with exhaust gas regulations enforced gradually, the interest has shifted at the stoichiometric mixture combustion system. The stoichiometric mixture combustion method has the advantage of a three-way catalyst utilization whose purification efficiency is high, but the problem of thermal durability and the fuel economy remains as a challenge. Hydrogen-natural gas blend fuel (HCNG) can increase the rate of exhaust gas recirculation (EGR) because the hydrogen increases burning speed and lean flammability limit. The increase in the EGR rate can have a positive impact on heat resistance of the engine due to the decreased combustion temperature, and further can increase the compression ratio for efficient combustion. In this study, to minimize the exhaust emission developed HCNG engine with stoichiometric combustion method, developed three-way catalyst was applied to evaluate the conversion characteristics. The tests were carried out during the steady state and transient operating conditions, and the results were compared for both the conventional and proto-three-way catalyst of HCNG engine for city buses.

• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.13-19
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• 2008

Among the various prime movers for combined heat and power (CHP) system, the CNG engine is the most commonly used power generation equipment of which power is less than 1MW. The 300 kW class CNG engine for CHP can meet stringent emission regulations with the adoption of stoichiometric air-fuel ratio control and three way catalyst. As the thermal efficiency of the stoichiometric ratio engine is lower than that of lean burn engine, it is necessary to operate the stoichiometric engine at its minimum spark advance for the best torque (MBT). However, knock control should be introduced for the engine under high intake air temperature conditions because MBT operating conditions are generally very close to those of knock occurrence. In this study, engine performances and knocking characteristics were experimentally investigated for the CNG engine that needs to be operated at higher intake air temperature conditions than normal conditions.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.40-46
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• 2015

Stoichiometric combustion engine with Three-way catalyst had an advantage that can reduce the harmful emissions effectively. Fuel equivalence ratio controlled from engine is very important because Fuel equivalence ratio with high conversion efficiency was narrow. This study analyzed the conversion efficiency under whole range of operating area for to evaluate the performance of three-way catalyst. In order to identify the Optimum conversion efficiency, the conversion efficiency due to change the control value of fuel equivalence ratio was investigated. The result show that conversion efficiency of emissions(more than 95%) has discovered by means of fuel equivalence ratio control at each test condition. As engine power increases, optimal fuel equivalence ratio tended to increase linearly under operating conditions of similar exhaust gas temperature.

• (The) Research of the performance art and culture
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• no.40
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• pp.5-35
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• 2020

Affect is intensity and quality that are generated as the physical body senses the outside world. Of experienced affect, notions that are granted meaning and interpretation are emotions. Affect theory distinguishes emotion and affect and by focusing on affect, it provides methods with which to analyze physical body responses and changes and it presents new possibilities to performing arts research that uses the physical body as a medium. Nong-ak is art that concentrates mainly on the occurrence of affect rather than 'representation'. Nong-ak is a performance type in which sound, color, texture, and physical movement overlap and exist in a synesthetic way. Here, physical things such as instruments, props, costumes, and stage devices are gathered together with non-physical things such as rhythm, mood, and atmosphere around human bodies. The physical body is stimulated by these things, displays tendencies that suit performances, and becomes 'the body without an image' as it immerses itself into the performance, acting while displaying 'quasi-corporeality'. The body, which moves automatically as if without consciousness, appears more easily within groups. To transition individuals of everyday life to 'the body without an image', Nong-ak executes the group physical exercise of 'Jinpuri'. Such physical exercise builds up affect by increasing nonverbal communion and communication and brings out the creativity of individuals within mutual trust and a sense of belonging. Affect and emotion stirred up by Nong-ak act as confirmation and affirmation of the existence, vitality, and ability of one's self and groups. Such affirmation recalls Nong-ak as a meaningful and important value from group dimensions and perceives it as a performance form that should be preserved and passed on.

• (The) Research of the performance art and culture
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• no.35
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• pp.61-92
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• 2017

During the Japanese colonial era, traditional music performances were gradually diminishing and weakening in the particular condition of colonization. Meanwhile, from the time of enlightenment, Western genre performances were becoming vitalized with the influence of Western civilization that began to be spread steadily throughout the society. In that situation, traditional music performances tended to be mixed performances accompanied by Western ones, not independent performances. Mostly, they were accompanied by Western music, and also, they were performed along with other genres like plays, lectures, movies, dances, or magic, too. Such form of mixed performances accompanied by Western genres became even more vitalized in the 1920's and came to be positioned as a form of traditional music performances. Therefore, research on the forms of mixed performances between Western genres and traditional music is meaningful in examining the forms of traditional music performances that have not been studied in the history of Korean modern music and understanding the trends of traditional music performances which were generally found in the Japanese colonial era. However, such research has hardly been conducted concretely yet. Accordingly, concerning the forms of mixed performances between Western genres and traditional music in the 1920's, this author considered the background of vitalizing mixed performances between Western genres and traditional music mainly with newspaper articles of the time and their formal characteristics. Regarding the background of vitalizing the forms of mixed performances between Western genres and traditional music, from the 1920's, the forms of mixed performances between Western genres and traditional music became more vitalized than before. The causes of that may include the increase of groups hosting or sponsoring such performances from the 1920's and also the dramatic increase of such performances in general. Moreover, the increased performances were conducted in the forms of mixed performances mainly in order to satisfy the people's needs becoming diversified with the distribution of Western civilization. Concerning the formal characteristics of mixed performances between Western genres and traditional music, this researcher classified western genres performed with traditional music and examined what characteristics were found in such mixed performances of tradition music by the types of Western genres respectively. First, in the mixed performances type of western-type genre and traditional music, the number of programs for the western music had significant portion in general, and there were certain ensemble of the western music and traditional musical instrument that was rare at this period of time, and it also had the characteristics of classifying two genres to perform for each title or date. Second, in the mixed performances type of the drama and traditional music, the traditional music is directly participated in the drama with the similar type to the theater, or performed independently from the drama with the role of interlude performance for the stage conversion of the drama to have the characteristics of performing in audience publicity or entertainment. Third, in the mixed performances type of the lecture and traditional music, the traditional music is played before or after the lecture to play the role to set the atmosphere and entertainment for the lecture as displaying the feature to perform for the audience attraction. And, fourth, in the mixed performances type of the movie and traditional music, the traditional music sometimes directly participated in the movie or had the features of independent performance, and there was a characteristic to perform for the entertainment after showing a movie.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.587-592
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• 2010

A numerical analysis of reactive flow in a MILD(Moderate and Intense Low oxygen Dilution) combustor is accomplished to elucidate the characteristics of combustion phenomena in the furnace with the variation of air fuel ratio. For the smaller magnitude of air injection velocity(10 m/s), the air flow could not penetrate toward upper part of furnace. On the other hand, the air flow suppresses the fuel flow for the case of air injection velocity 30 m/s. The air velocity 18 m/s is corresponding to the stoichiometric air flow velocity, and for that case, the air flows to relatively more upper part of the furnace when compared with the case of air injection velocity 10 m/s. The reaction zone is produced with the previous flow pattern, so that the reaction zone of the air injection velocity 10 m/s is biased to the air nozzle side and for the case of air injection velocity 30 m/s, the reaction zone is inclined to the fuel nozzle side. For the cases with the air injection velocities 16, 18, 20 m/s, the reaction zone is nearly located at the center between air nozzle and fuel nozzle. The maximum temperatures and NOx concentrations for the cases of air injection velocity 16, 18, 20 m/s are lower than the cases with air injection velocity 10, 30 m/s. From the present study, the stoichiometric air fuel ratio is considered as the most optimal operating condition for the NOx reduction.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.407-410
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• 2006

Selection of flow channel in the separation plate of PEMFC is very important parameter to improve its performance and reduce parasite loss. Flow patterns in the channel have great influence on the transport of hydrogen and all and water generated from electrochemical reaction in diffusion layer In this study, fluid flow in flow channel with parallel and interdigitated patterns are simulated three dimensionally on full flow domain including anode and cathode electrode together. The numerical results show that the fuel cell with interdigitated flow channel represents better performance than that with parallel flow channel due to its strong convective transport across the gas diffusion layer. But the pressure drop in parallel flow channel is much more than that in nterdigitated flow channel. The effect of temperature and stoichiometric number on performance can be calculated and analyzed as well.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.78-85
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• 2006

Selection of flow channel in the separation plate of PEMFC is very important parameter to improve its performance and reduce parasite loss. Flow patterns in the channel have great influence on the transport of hydrogen and air and removal of water generated from electrochemical reaction in diffusion layer. In this study. fluid flow in flow channel with parallel and interdigitated patterns are simulated three dimensionally on full flow domain including anode and cathode channel together. The numerical results show that the fuel cell with interdigitated flow channel represents better performance than that with parallel flow channel due to its strong convective transport across the gas diffusion layer. But the pressure drop in parallel flow channel is much more than that in interdigitated flow channel. And effects of temperature and stoichiometric number on performance can be calculated and analyzed as well. Nomenclature.

• Journal of Korea Entertainment Industry Association
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• v.15 no.1
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• pp.27-38
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• 2021

Non-Contact society has arrived due to social distinctions by COVID 19 pandemic. The arrival of the era of non-contact is having a profound impact on educational activities as well as on our social and economic lives. In response to the pandemic situation universities and all other educational institutions have implemented non-contact online classes. In particular arts physical educations and other practical classes are experiencing many difficulties due to the limited environment caused by social distancing from COVID 19 pandemic. Vocal classes are undergoing a transition mainly from 1:1 individual face-to-face lessons or group teaching methods to the non-contact era of online teaching or lesson methods. It is necessary to look at the direction of non-face-to-face practical classes in preparation for accelerated educational innovation. Edu-tech, which innovates technology in the wake of the age of non-contact after COVID 19 pandemic is expected to begin in earnest at school sites in Korea which have remained in the traditional way of education. The purpose of this study is to effectively non-contact vocal instructional methods by cogitating the current state of higher practical education and vocal classes in Korea. In addition, This study conducted two components of satisfied instructions such as 'Priorlearning of monitoring of recorded singing', and 'Immediate analyzing of various vocal contents and supplementary lessons of music theory' with a research on the peos and cons of non-face-to-face vocal class. Over a period of time, The effective non-contact of vocal instructional methods is in need to supplement non-face-to-face vocal class problems and further research and system construction with non-face-to-face vocal class's pros and cons to construct high-quality lecture contents is warranted.