• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1326-1327
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• 2008

Recently, the air pollution is supposed is to be the most serious environmental problem. Therefore, a small air cleaner is asked to make comfortable indoor environment for the moderns who have frequent indoor activity. In this study, without generating of the second pollution source, dust in the air and harmful microorganisms can be removed by the electric dust collecting technology which has high reliability and efficiency to be able to remove the impurities even though it is just 0.01${\mu}m$. Accordingly, power sources of the dust collector use, it is not inefficiency and offering to dust collector unstable. In order to overcome the point at issue, a this study, for power factor compensating use the PFC circuit, for removing the noise use EMI filter and for generating the hight voltage use the Cockcroft Walton Circuit. And we study power source on characteristic and improvement.

• Journal of Welding and Joining
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• v.30 no.5
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• pp.13-15
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• 2012

Stainless steels is widely used in various industries due to its high strength and excellent corrosion resistance. However, in the case of fusion welding for stainless steel, chromium deficiency layer produced by chromium carbide precipitation during welding process causes corrosion-resistance to be lower and formation of intergranular corrosion. It requires a inevitable complex procedure such as pre-heating and post-heating process etc. to prevent such weld defects. From this viewpoint, the new welding process such as a solid state welding method is suited for welding of stainless steels due to its advantages over the fusion welding. Therefore this paper intends to investigate the research trend on friction stir welding, one of solid state welding processes for stainless steels.

• Corrosion Science and Technology
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• v.19 no.1
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• pp.1-7
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• 2020

Chalk River Unidentified Deposits (CRUDs) were collected from the Korean pressurized water reactor (PWR) plant (A, B, and C) where the axial offset anomaly (AOA) occurred. AOA, also known as a CRUD-induced power shift, is one of the key issues in maintaining stable PWR plant operations. CRUDs were sampled from spent nuclear fuel rods and analyzed using an electron probe micro-analyzer (EPMA). This paper describes the characteristics of boron-deposits from the CRUDs sampled from twice-burnt assemblies from the Korean PWR. The primary coolant of a PWR contains boron and lithium. It is known that boron deposition occurs in a thick CRUD layer under substantial sub-cooled nucleate boiling (SNB). The results of this study are summarized as follows. Boron was not found at the locations where the existence was confirmed in simulated CRUDs, in other words, the cladding and CRUD boundaries. Nevertheless, we clearly observed the presence of boron and confirmed that boron existed as a lump in crystalline form. In addition, the study confirmed that CRUD existed in a crystal form with a unique size of about 10 ㎛.

• Korean Membrane Journal
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• v.3 no.1
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• pp.32-38
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• 2001

Using the hollow fiber membrane module in a lab-scale membrane bioreactor, the anoxic- oxic (AO) process for nitrogen removal was operated for about one year. For the influent wastewater containing 1,200-1,400 mg $1^{-1}$ of CODcr and 200-310 mg $1^{-1}$ of nitrogen, this process achieved a high quality effluent of less than 30 mgCOD $liter^{-1}$ and 50 mgN $liter^{-1}$. The removal rate of organics was above 98% at a loading rate larger than 2.5 kgCOD $m^{-3}$$d^{-1}$. When the internal recycle from the oxic to the anoxic reactor changed room 2n to 600% rout the influent flow rate, the nitrogen removal rate increased from about 70 to 90% at a loading rate of 0.4 kgT-N m-s d-1. The initial increase of transmembrane pressure (TMP) was observed after a 4-month operation while maintaining the flux and MLSS concentration at 7-9 1 $m^2$ $h^{-1}$ and 6,000-14,000 mg $1^{-1}$, respectively. The TMP could be maintained below 15 cmHg for an 8-month operation. The chemical cleaning with an acid followed by an immersion in an alkali solution gave better cleaning result with the membrane operated for 10 month rather than that only by an alkali immersion.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2056-2065
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• 2021

The transition toward clean energy is an issue of great importance with growing debate in climate change mitigation. The complex nature of nuclear energy-CO₂ emissions nexus makes it difficult to predict whether or not nuclear acts as a clean energy source. Hence, we examined the relationship between nuclear energy consumption and CO₂ emissions in the context of the IPAT and Environmental Kuznets Curve (EKC) framework. Dynamic Auto-regressive Distributive Lag (DARDL), a newly modified econometric tool, is employed for estimation of long- and short-run dynamics by using yearly data spanning from 1971 to 2018. The empirical findings of the study revealed an instantaneous increase in nuclear energy reduces environmental pollution, which highlights that more nuclear energy power in the Indian energy system would be beneficial for climate change mitigation. The results further demonstrate that the overarching effect of population density in the IPAT equation stimulates carbon emissions. Finally, nuclear energy and population density contribute to form the EKC curve. To achieving a cleaner environment, results point out governmental policies toward the transition of nuclear energy that favours environmental sustainability.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1657-1663
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• 2022

This study uses data from 1970 to 2016 to analyze the effect of nuclear energy use on CO₂ emissions and attempts to validate the EKC hypothesis using the Fourier Autoregressive Distributive Lag model in India for the first time. Because of India's rapidly rising population, the environment is being severely strained. However, with 22 operational nuclear reactors, India boasts tremendous nuclear energy potential to cut down on CO₂ emissions. The EKC is validated in India as the significant coefficients of GDP and GDP.² The short-run estimates also suggest that most environmental externalities are corrected within a year. Given the findings, some policy recommendations abound. The negative statistically significant coefficient of nuclear energy consumption is an indication that nuclear power expansion is essential to achieving clean and sustainable growth as a policy goal. Also, policymakers should enact new environmental laws that support the expansion and responsible use of nuclear energy as it is cleaner than fossil fuels and reduces the cost and over-dependence on oil, which ultimately leads to higher economic growth in the long run. Future research should consider studying the nonlinearities in the nuclear energy-CO₂ emissions nexus as the current study is examined in the linear sense.

• Journal of Information Technology Services
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• v.22 no.5
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• pp.17-30
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• 2023

A company's sustainable growth is a very important goal, and for this purpose, the company's business model is changing into a convergence of products and services. The purpose of PS-Offering is to maintain a long-term relationship with customers, and customer experience management is necessary for this. This study presents a service design methodology that can support customer experience management of the PS-Offering business model. The experience management portfolio analysis methodology consists of four steps: 1. Deriving service encounter through customer journey maps; 2. Identify the service structure of each service encounter in three forms (FFC, FSC, FSE). 3. Analyze the customer's emotional variables, that is, customer experience, at each service encounter, Finally, 4. After plotting the level of customer experience at the service encounter, the analysis is conducted with a customer experience management portfolio that seeks future strategic plans for this. The methodology presented in this study will help in the service design of the service encounter unit centered on customer experience. And it will improve the financial performance of the company by raising the service level of the business model.

• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.107-113
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• 2010

The object of this research is to conform of practicable possibility and recycling of producing junk after citrus fruits is processed. With extracting d-limonene oil that have 70~90% a component of oil out of junk citrus peel, making certain the about 12000ppm concentration of it. Limonene derived from citrus in jeju using conventional synthetic detergents can be replaced with the development of environmentally friendly natural detergent investigated the possibility. Mostly due to ocean dumping, disposal and cause environmental problems by recycling natural citrus cleaner alternative to the research conducted on the possibility. Cleaning efficiency with temperature did not affect the largest concentrations were able to identify the difference between cleaning efficiency. At least 10% of the d-limonene oil could be from the cleaning performance, increasing the concentration of the cleaning efficiency was increased in size. Ultrasonic is very high removal efficiency under the conditions shown in the cause of pure self-generated ultrasonic cleaning power as co-effects of d-limonene oil appears to chemical cleaning effect of ultrasonic cavitation occurs in the physical cleaning effect due to a combination of synergistic stability is maximized by low concentrations of d-limonene oil in a short time showed an excellent cleaning ability. Having the ability of cleaning at the same time, considering the side recycling in the junk citrus peels reflects possibility of basic materials utility eco-friendly in the skin soap, bath soap, cosmetics etc, through ability of exclusion a contaminant in based cleaning effect(EC) it can prospect substitution effect environmentally in the pre existence synthetic detergents.

• Clean Technology
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• v.14 no.4
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• pp.232-241
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• 2008

European directive DIRECTIVE 2002/96/EC requires minimum recycling & recovery rates on waste electrical and electronic equipment (WEEE). We tried to make references for recycling and recovery rates of parts and materials used in electrical and electronic equipment (EEE), which could be used to calculate recyclability and recoverability rates of a product in the development phase. First, we investigated recycling processes of WEEE and recycling and recovery characteristics of parts and materials. Based on the investigation results and the european recycling data, we made a data base of parts and materials for calculation of recycling and recovery rates of EEE. The developed DB was improved by reflecting advices of european experts.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.313-321
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• 2008

The current IAEA programs for $2008{\sim}2009$ and the resultant prospects for the applications of radioisotopes and radiation have been presented, thus providing a condensed understanding of the Agency's programs for an effective and efficient deployment of the respective national R&D projects in Korea. The considerable and beneficial advantages of Korea's participation in the IAEA programs have been reviewed and their immediate relevance has been emphasized. Also a strategic approach for an enhancement of Korea's active participation in these programs and their efficient implementation has been established.