• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.408-411
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• 1987

We have designed the power supply of an 120W $CO_2$ Laser for non-metal material processings. High voltage is automatically controlled by means of thyristor triggered phase control. Pulse and C.W. mode are selectively generated by means of discharge current control. It is possible to interface this system with other Numerical Controller. Also, safety interlock circuit is incorporated in this system.

• Environmental Engineering Research
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• v.16 no.1
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• pp.19-27
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• 2011

This paper introduces an approach to identify the total energy consumption with subsequent $CO_2$ emissions, for both industrial and non-industrial sectors. Statistical data for 2005 were compiled in a national account system to construct an energy input-output table for investigating the influence between energy demand and supply activities. The methodological approach was applied to South Korea. Twelve types of energy and fifteen industrial and non-industrial sectors are formed as the compartments of the input-output table. The results provided quantitative details of the energy consumption and identified the significant contributions from each sector. An impact analysis on the $CO_2$ emissions for the demand side was also conducted for comparison with the supply side.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.5
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• pp.33-41
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• 2018

Most important thing when designing and implementing a supply chain network is to consider various problems which may occur in real world situation. In this paper, we propose a supply chain network considering two problems (environmental factor and transportation types) under real world situation. CO2 emission amount as environmental factor is considered since it is usually generated from production and transportation processes. Normal delivery, direct delivery and direct shipment as transportation types are also considered since many customers ask various transportation types for delivery or shipment of their products under on-line or off-line purchase environment. The proposed supply chain network considering environmental factor and transportation types is represented in a mathematical formulation and implemented using hybrid genetic algorithm (HGA) approach. In numerical experiments, several scales of supply chain networks are presented and implemented using HGA approach. The performance of the HGA approach is compared with those of some conventional approaches under various measures of performance. Finally, it is proved that the performance of the HGA approach is superior to those of the others.

• Environmental and Resource Economics Review
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• v.30 no.2
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• pp.325-345
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• 2021

In this paper, we empirically evaluate the potential performance of energy conversion policy and analyze its effects on power generation sector. We first examine the degree of substitutability between energy inputs by measuring the price elasticities of energy demands and then estimate the changes in CO₂ generation when the proportions of nuclear power plants and renewable power generation are increased. The shadow prices of nuclear power and renewable energy are calculated to compare the potential costs of power generation between the two energy sources. We analyze the impacts of the expansion of nuclear power plants and renewable power generation on power supply price. Nuclear and renewable energy were measured to be complementary to each other. The expansion of nuclear power plants has been more effective in reducing CO₂ emissions than increasing renewable power generation. In most years over 2002 to 2016, the impact of nuclear power expansion on the power supply price was generally higher than that of renewable power generation, with relatively large range of fluctuations.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.332-340
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• 2017

This study aims to propose a new optimization-based approach for design and analysis of the stand-alone hybrid energy supply system using renewable energy sources (RES). In the energy supply system, we include multiple energy production technologies such as Photovoltaics (PV), Wind turbine, and fossil-fuel-based AC generator along with different types of energy storage and conversion technologies such as battery and inverter. We then select six different regions of Korea to represent various characteristics of different RES potentials and demand profiles. We finally designed and analyzed the optimal RES stand-alone energy supply system in the selected regions using multiobjective optimization (MOOP) technique, which includes two objective functions: the minimum cost and the minimum $CO_2$ emission. In addition, we discussed the feasibility and expecting benefits of the systems by comparing to conventional systems of Korea. As a result, the region of the highest RES potential showed the possibility to remarkably reduce $CO_2$ emissions compared to the conventional system. Besides, the levelized cost of electricity (LCOE) of the RES-based energy system is identified to be slightly higher than conventional energy system: 0.35 and 0.46 $/kWh, respectively. However, the total life-cycle emission of $CO_2$ ($LCE_{CO2}$) can be reduced up to 470 g$CO_2$/kWh from 490 g$CO_2$/kWh of the conventional systems.

• Journal of agriculture & life science
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• v.45 no.1
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• pp.21-32
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• 2011

This study was conducted to estimate carbon dioxide $(CO_{2})$ absorption and bioenergy supply potential of forests in Muju county based on GIS RS In results, it was estimated that 7,800,130 $tCO_{2}$ was absorbed and all bioenergy supply potential of 11,868,202,837 Mcal was available. Futhermore, bioenergy supply potential of 314,876,637 Mcal was available each year that was able to be supplied for the hitting during winter period to 11,241 households. This was more than all households of 10,902 in Muju county. This study suggested the methodology for estimating $CO_{2}$ absorption and bioenergy supply potential of forests on the national scale, and it was believed that reliability would be increased by estimation on the national scale using detailed forest information based on the latest techniques such as GIS RS techniques.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.739-745
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• 2001

The objective of this research is to analyze the ventilation effectiveness in the non-isothermal air supply using mixing and displacement ventilation systems for indoor air quality control and management. In this study, a ventilation effectiveness is evaluated in a simplified model chamber using a tracer gas technique of $CO^2$ gas injected into a supply duct as a function of ventilation rates, supply/extract sites and cooling/heating air supply. The ventilation effectiveness decreased with increasing ventilation rate on the cooling and heating conditions. And the ventilation effectiveness of case 3 (down supply and upper extract) was better thant that of case 1(upper supply and upper extract) and case 2(upper supply and down extract) with the cooling supply conditions. but for the heating supply air conditions, the ventilation effectiveness of case 2 was better than that of case 3 and case 1.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.103-110
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• 2011

This study is to comparatively analyze the characteristics of pH decrease in recycled fine aggregates for embankment and landfill produced from waste concrete by using natural process and artificial process. The result was as follows In case of recycled fine aggregates left outdoor, it was found that pH level was decreased if the thickness of embankment becomes thinner, or the materials left outdoors owing to high concentration of $CO_2$ in atmosphere caused by respirations of people. When the air was permeated, pH level was decreased more effectively. It was analyzed that this phenomenon was caused by efficient supply of $CO_2$ in the recycled fine aggregates owing to high-pressure ventilators. In case of water spraying treatment, sprayed water facilitated hydration of unhydrated cement to dissolve calcium hydroxides which neutralized $CO_2$ in the atmosphere during desiccation process and decrease pH level by a considerable margin. In case of Immersed treatment, decrease of pH was not sufficient. When facilitating the supply of $CO_2$, pH level of the recycled fine aggregates was decreased by the largest margin. It was analyzed that this phenomenon was caused by efficient supply of $CO_2$. From the above results, it was analyzed that the most effective method of reducing pH level of the recycled fine aggregates from the aspects of pH reduction performance, economic efficiency and workability was repeated wet-dry cycles of spraying water to the aggregates in the proportion of 1:0.5 by weight and then treating by forcefully blowing $CO_2$ gas into the aggregates.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1072-1074
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• 1999

In this study, it is the purpose to develope a cheap and compact pulsed $CO_2$ laser with pulse repetition rate range of 1 kHz. We used a IGBT switched power supply as a power supply, which is cheap and simple comparing to others. PIC one-chip microprocessor was used for precise control of a laser power supply on the control part. And the laser cavity was fabricated as an axial and water cooled type. The laser performance characteristics as various parameters, such as pulse repetition rate gas pressure, and gas mixture rate have been investigated. The experiment was done under the condition of total pressure of $CO_2:N_2$:He = 1.3:10, 1:1.5:5 1:9:15 from 6 Torr to 15 Torr and pulse repetition rate from 100 Hz to 900 Hz. As a result, the maximum average output was about 20.5 W at the total pressure of 15 Torr, the gas mixture $CO_2:N_2$:He = 1:9:15 and the pulse repetition rate of 700 Hz.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.2
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• pp.75-87
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• 2019

This paper presents a fully digital controlled power supply unit for the wireless controlled dimmable LED lighting system. The proposed power supply designed using a fly-back converter, which is directly controlled by a microprocessor. Although the proposed circuit does not sense the AC input current and has not AC input voltage feed-forward, it can achieve a high power factor. The proposed power supply directly regulates the output power for LED loads using the PWM and PFM control of the fly-back converter without additional regulator. For a wireless remote control function, the Zigbee modem is equipped in the proposed power supply. A prototype set-up has been built and tested. Through the experiment with a prototype set-up, the usefulness of the proposed power supply is verified.