• Journal of Energy Engineering
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• v.29 no.2
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• pp.68-78
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• 2020

According to the new climate change agreement, technology development to reduce greenhouse gases is actively conducted worldwide, and research on energy efficiency improvement in the field of power generation and transmission and distribution is underway [1,2]. Economic analysis of the operation method of storing and supplying surplus electricity using energy storage devices, and using energy storage devices as a frequency adjustment reserve power in regional cogeneration plants has been reported as the most profitable operation method [3-7]. Therefore, this study conducted an economic analysis for the installation of energy storage devices in the combined heat and power plant in the Czech Republic. The most important factor in evaluating the economics of battery energy storage devices is the lifespan, and the warranty life is generally 10 to 15 years, based on charging and discharging once a day. For the simulation, the ratio of battery and PCS was designed as 1: 1 and 1: 2. In general, the primary frequency control is designed as 1: 4, but considering the characteristics of the cogeneration plant, it is set at a ratio of up to 1: 2, and the capacity is simulated at 1MW to 10MW and 2MWh to 20MWh according to each ratio. Therefore, life was evaluated based on the number of cycles per year. In the case of installing a battery energy storage system in a combined heat and power plant in the Czech Republic, the payback period of 3MW / 3MWh is more favorable than 5MW / 5MWh, considering the local infrastructure and power market. It is estimated to be about 3 years or 5 years from the simple payback period considering the estimated purchase price without subsidies. If you lower the purchase price by 50%, the purchase cost is an important part of the cost for the entire lifetime, so the payback period is about half as short. It can be, but it is impossible to secure profitability through the economy at the scale of 3MWh and 5MWh. If the price of the electricity market falls by 50%, the payback period will be three years longer in P1 mode and two years longer in P2 and P3 modes.

• Clean Technology
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• v.24 no.3
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• pp.198-205
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• 2018

This study investigated the influence of catalyst preparation on the activity of $Co-CeO_2$ catalyst for $N_2O$ decomposition. $Co-CeO_2$ catalysts were synthesized by co-precipitation and incipient wetness impregnation. In order to estimate the performance of the as prepared catalysts, direct catalytic $N_2O$ decomposition test was carried out under $250{\sim}375^{\circ}C$. As a result, the catalyst prepared by co-precipitation (CoCe-CP) showed an enhanced performance on $N_2O$ decomposition reaction even in the presence of $O_2$ and/or $H_2O$, whereas the impregnation catalyst (CoCe-IM) did not. In order to investigate the difference in catalytic activity, characterization such as XRD, BET, TEM, $H_2-TPR$, $O_2-TPD$, and XPS was conducted. It is confirmed that the particle size and specific surface area were changed depending on the catalyst preparation method and the synthesis process influenced the physical properties of the catalysts. In addition, the improvement in the activity of the catalyst prepared by co-precipitation is due to the enhanced reduction from $Co^{3+}$ to $Co^{2+}$ and the improved oxygen desorption rate. However, it has been confirmed that the surface electron state and binding energy, which are related to $N_2O$ decomposition, do not change depending on the preparation method.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.441-447
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• 2012

Purpose: This paper is about development and design of the 1x optical path relay adapter for the beam splitting prism by us the day & night scope. Methods: To product the day & night scope by using the beam splitting prism and the commercial zoom optical system with the C-mount lens barrel structure, the optical path relay adapter, which doesn't change the image size of the zoom optical system and can stretch the position of the image-forming surface, is needed. We could design the 1x optical path relay adapter by using the CodeV program in which the Lens Module mode is offered. Results: We could design the optical path relay adapter used in the day&night scope with the beam splitting prism, of which characteristics have the EFL of -56.0 mm, the magnification of +1.0x, the distance from the 1st lens surface to the last lens surface of about 20.4 mm. The resolution of this system is characterized by 30 lp/mm at 40% MTF. This is enough to accommodate the designed optical path relay adapter can overcome the resolution of the 3rd generation of image intesifier tubes. Conclusions: By designing and applying the optical path relay adapter of which optical characteristics have the EFL of -56.0 mm, the magnification of +1.0x, the distance from the 1st lens surface to the last lens surface of about 20.4 mm, and the resolution of 30 lp/mm at 40% MTF, we could develop the new type day&night scope consisting of the beam splitting, the commercial zoom optical system with the C-mount lens barrel structure, and the 3rd generation of image intesifier tubes.

• Applied Biological Chemistry
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• v.18 no.2
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• pp.71-97
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• 1975

To improve the food qualities in Korea, two hundred and fourtynine kinds of food additives have been allowed in food processing, of which one hundred and nineteen kinds could be used under the limitted conditions. Hence, in practical uses in food processing, many kinds of them are mixed at random within the permitted amounts for their special purposes. For last several years, many kinds of the food additives were prohibited because they have been proved to be toxic even with the single dose. Until recently a few studies on the toxicity in the mixture of food additives were reported, however, they were shown to be no severe additional effect on the animal. This study was performed to see if any elevation of chronic or subacute toxicity of food additives occur especially when they are mixed with each other, using three kinds of food additives (DHA, AF-2, BHT) most widely used as food preservatives, antiseptics and antioxidants. One hundred and fifty young male rats were taken and divided into ten feeding groups, one first control group (food additives blank), three second control groups (DHA 0.1%, AF-2 0.1%, BHT 0.5%), three mixture groups of low level (mixture of each 60% of two second control level) and three mixture groups of high level (mixture of each 90% of two second control level). As the methods of biological and clinical tests, the change of body weight (growth rate), daily intake of diets, organ to body weight ratio, histopathological findings of organs, hematological observation, liver and kidney function tests were checked three times during the periods of 24 weeks. The following results were obtained. 1. The low level group of DHA, AF-2 mixture and DHA, BHT mixture revealed a little retardation in growth rate than the first control group, however, they were similar to the second controls, while all the mixture groups of high level showed a more remarkable retardation than the first and second controls. 2. Average daily intake of the diets was the same in each group, showing a similar decreasing tendency (70-100g/kg of body weight) in accordance with the growth rate. It was observed that there are no differences in the taste and appetite in each group of rats. 3. Abnormal enlargements of kidney and lung were not seen in all the mixture groups compared with the controls, while a slight hepatomegaly was observed in all mixture groups of low level as in the second controls. Significant differences (almost 1% level) were observed between the high level groups and the first control group. 4. Histopathological effects of the food additives on lung, kidney and liver tissues were found in all mixture group of high level. The less frequencies of the same effects were also seen in the low level groups. 5. The esterified cholesterol to total cholesterol ratio in the mixture groups of high level showed a little lower values, and the activities of serum glutamate oxaloacetate transaminase and alkaline phosphatase decreased almost with significance of 5% level compared with the first control group. The serum A/G ratio in the mixture groups also decreased. The results demonstrated that the liver function was decreased in the mixture groups compared with the controls. 6. In all groups throughout the test period, kidney functions (concentration of protein and creatinine excreated per hour in urine and renal filtration rate) were shown almost as normal as the first control. 7. Average values of hematocrit, erythrocytes and leucocytes in the mixture groups were in the normal ranges as in the controls, which denotes that the production of blood cells in bone marrow were also normal in all groups. With the above results, it is concluded that when the food additives (DHA, AF-2, BHT) were given together to the rats in several combinations even in less amount, they showed more toxic signs than the single doses.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.473-479
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• 2012

Water reuse has been highlighted as a representative alternative to solve the lacking water resource. This study carried out a study on the pipe corrosion and water quality change which can occur through the supply of reclaimed water, using a simulated reclaimed water distribution pipeline. Galvanized steel pipe (GSP), cast iron pipe (CIP), stainless steel pipe (STSP) and PVC pipe (PVCP) were used for the pipe materials. Reclaimed water(RW) and tap water(TW) were respectively supplied into simulated reclaimed water distribution pipelines. As a result of performing a loop test to supply reclaimed water to simulated reclaimed water distribution pipelines, the weight reduction of pipe coupons showed the sequence of CIP > GSP > STSP ${\approx}$ PVCP. In addition, reclaimed water showed a high corrosion rate comparing to that of tap water. In case of CIP, the initial corrosion rate showed 3.511 mdd(milligrams per square decimeter per day) for reclaimed water and 2.064 mdd for tap water and the corrosion rate for 90 days showed 0.833 mdd for reclaimed water and 0.294 mdd for tap water. Also in case of GSP, the initial corrosion rate showed 2.703 mdd for reclaimed water and 2.499 mdd for tap water and the corrosion rate for 90 days showed 0.349 mdd for reclaimed water and 0.248 mdd for tap water, which was a tendency similar to that appeared in CIP with a tendency to reduce the corrosion rate. As a result of water quality changes of reclaimed water at pipe materials to carry out the loop test, there was higher conversion ratio of ammonia into nitrate in CIP and GSP with higher corrosion rate than that in STSP and PVCP where no corrosion has occurred. The highest denitrification rate of nitrate could be observed from CIP with the most particles generated from corrosion. In CIP, it could be confirmed that there was MIC (Microbiologically Induced Corrosion) as a result of EDS (Energy Dispersive X-ray spectrometer System) analysis results.

• Geophysics and Geophysical Exploration
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• v.10 no.3
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• pp.183-190
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• 2007

The site effects of seismic stations were evaluated by conducting a simultaneous inversion of the stochastic point-source ground-motion model (STGM model; Boore, 2003) parameters based on the accumulated dataset of horizontal shear-wave Fourier spectra. A model parameter $K_0$ and frequency-dependent site amplification function A(f) were used to express the site effects. Once after a H/V ratio of the Fourier spectra was used as an initial estimate of A(f) for the inversion, the final A(f) which is considered to be the result of combined effect of the crustal amplification and loca lsite effects was calculated by averaging the log residuals at the site from the inversion and adding the mean log residual to the H/V ratio. The seismic stations were classified into five classes according to $logA_{1-10}^{max}$(f), the maximum level of the site amplification function in the range of 1 Hz < f < 10 Hz, i.e., A: $logA_{1-10}^{max}$(f) < 0.2, B: 0.2 $\leq$ $logA_{1-10}^{max}$(f) < 0.4, C: 0.4 $\leq$ $logA_{1-10}^{max}$(f) < 0.6, D: 0.6 $\leq$ $logA_{1-10}^{max}$(f) < 0.8, E: 0.8 $\leq$ $logA_{1-10}^{max}$(f). Implication of the classified result was supported by observing a shift of the dominant frequency of average A(f) for each classified stations as the class changes. Change of site classes after moving seismic stations to a better site condition was successfully described by the result of the station classification. In addition, the observed PGA (Peak Ground Acceleration)-values for two recent moderate earthquakes were well classified according to the proposed station classes.

• Journal of Intelligence and Information Systems
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• v.22 no.4
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• pp.157-176
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• 2016

For a long time, mobile phone had a sole function of communication. Recently however, abrupt innovations in technology allowed extension of the sphere in mobile phone activities. Development of technology enabled realization of almost computer-like environment even on a very small device. Such advancement yielded several forms of new high-tech devices such as smartphone and tablet PC, which quickly proliferated. Simultaneously with the diffusion of the mobile devices, mobile applications for those devices also prospered and soon became deeply penetrated in consumers' daily lives. Numerous mobile applications have been released in app stores yielding trillions of cumulative downloads. However, a big majority of the applications are disregarded from consumers. Even after the applications are purchased, they do not survive long in consumers' mobile devices and are soon abandoned. Nevertheless, it is imperative for both app developers and app-store operators to understand consumer behaviors and to develop marketing strategies aiming to make sustainable business by first increasing sales of mobile applications and by also designing surviving strategy for applications. Therefore, this research analyzes consumers' mobile application usage behavior in a frame of substitution/supplementary of application categories and several explanatory variables. Considering that consumers of mobile devices use multiple apps simultaneously, this research adopts multivariate probit models to explain mobile application usage behavior and to derive correlation between categories of applications for observing substitution/supplementary of application use. The research adopts several explanatory variables including sociodemographic data, user experiences of purchased applications that reflect future purchasing behavior of paid applications as well as consumer attitudes toward marketing efforts, variables representing consumer attitudes toward rating of the app and those representing consumer attitudes toward app-store promotion efforts (i.e., top developer badge and editor's choice badge). Results of this study can be explained in hedonic and utilitarian framework. Consumers who use hedonic applications, such as those of game and entertainment-related, are of young age with low education level. However, consumers who are old and have received higher education level prefer utilitarian application category such as life, information etc. There are disputable arguments over whether the users of SNS are hedonic or utilitarian. In our results, consumers who are younger and those with higher education level prefer using SNS category applications, which is in a middle of utilitarian and hedonic results. Also, applications that are directly related to tangible assets, such as banking, stock and mobile shopping, are only negatively related to experience of purchasing of paid app, meaning that consumers who put weights on tangible assets do not prefer buying paid application. Regarding categories, most correlations among categories are significantly positive. This is because someone who spend more time on mobile devices tends to use more applications. Game and entertainment category shows significant and positive correlation; however, there exists significantly negative correlation between game and information, as well as game and e-commerce categories of applications. Meanwhile, categories of game and SNS as well as game and finance have shown no significant correlations. This result clearly shows that mobile application usage behavior is quite clearly distinguishable - that the purpose of using mobile devices are polarized into utilitarian and hedonic purpose. This research proves several arguments that can only be explained by second-hand real data, not by survey data, and offers behavioral explanations of mobile application usage in consumers' perspectives. This research also shows substitution/supplementary patterns of consumer application usage, which then explain consumers' mobile application usage behaviors. However, this research has limitations in some points. Classification of categories itself is disputable, for classification is diverged among several studies. Therefore, there is a possibility of change in results depending on the classification. Lastly, although the data are collected in an individual application level, we reduce its observation into an individual level. Further research will be done to resolve these limitations.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.2
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• pp.40-51
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• 2011

Recently, the public's interest in quality of life and good design has increased, and the opportunities for their participation in space planning and the design process are expanding. However, the public still lacks understanding of the role(and importance) of space and environment and is not experienced in expressing their opinion on improving the urban environment. At this point, 'Built Environment Education for Kids' will be the key to understanding space and environment as future citizens and to developing the ability of problem-solving and expressing their opinions. This study aims to change the awareness of the public as well as experts, and to make a better urban space through comparison and analysis of domestic and foreign 'Built Environment Education.' In 27 countries around the world(more than 110 institutions), 'Built Environment Education' from childhood is being implemented. Such movements aim to make people participate in the space design and decision-making process by understanding a fundamental element of the built environment and space perception. In this study, the United States, Britain, Finland, Japan and South Korea's 'Built Environment Education' are discussed Above all, the definition, range and target of 'Built Environment Education' are discussed For each case, the purpose and effect, laws and educational processes, systems and roles, and examples of programs are analyzed. Through reviewing each attribute and their implications, a conclusion is drawn on the aspects we have to consider in laying the foundation for implementing the 'Built Environment Education' in Korea, such as consideration of the locality, organizing systematic networks and composing a pool of experts, building proper institutions, and establishing the role of the government. This case study of 'Built Environment Education' can help increase the awareness of the public and build their strength in establishing a better future space. Through the analysis of the purpose, laws, systems, and contents, this case study is expected to provide and build the foundation for an educational system and develop an appropriate program that best suits our society.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.609-614
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• 2013

This study investigated the spontaneous combustion behavior of solvent-treated low rank coals. Indonesian lignite (a KBB and SM coal) and sub-bituminous (a Roto coal) were mixed with non-polar 1-methyl naphthalene (1MN) either by mechanical agitation or ultrasonication. The property change associated with 1MN treatment was then analyzed using proximate analysis, calorific value analysis, Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy and moisture re-adsorption test. Susceptibility to spontaneous combustion was evaluated using crossingpoint temperature (CPT) measurement along with gas analysis by GC. A FT-IR profile showed that oxygen functional groups and C-H bonding became weaker when treated by 1 MN. XPS results also indicated a decrease of the oxygen groups (C-O-, C=O and COO-). Increased hydrophobicity was found in the 1MN treated coals during moisture readsorption test. A CPT of the treated coals was ${\sim}20^{\circ}C$ higher than that of the corresponding raw coals and the ultrasonication was more effective way to enhance the stability against spontaneous combustion than the agitation. In the gas analysis less CO and $CO_2$ were emitted from 1MN treated coals, also indicating inhibition of pyrophoric behavior. The surface functional groups participating in the oxidation reaction seemed to be removed by the ultrasonication more effectively than by the simple mechanical agitation.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.8
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• pp.555-564
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• 2013

Innovative evolution in mobile devices along with recent spread of Tablet PCs and Smart Phones makes a new change not only in individual life but also in enterprise applications. Especially, in the case of medium-large mobile applications for large enterprises which generally takes more than 3 months of development periods, importance and complexity increase significantly. Generally Agile-methodology is used for a development process for the medium-large scale mobile applications, but some issues arise such as high dependency on skilled developers and lack of detail development directives. In this paper, S-MADP (Smart Mobile Application Development Process) is proposed to mitigate these issues. S-MADP is a service oriented development process extending a object-oriented development process, for medium-large scale mobile applications. S-MADP provides detail development directives for each activities during the entire process for defining services as server-based or client-based and providing the way of reuse of services. Also, in order to support various user interfaces, S-MADP provides detail UI development directives. To evaluate the performance of S-MADP, three mobile application development projects were conducted and the results were analyzed. The projects are 'TBS(TB Mobile Service) 3.0' in TB company, mobile app-store in TS company, and mobile groupware in TG group. As a result of the projects, S-MADP accounts for more detailed design information about 'Minimizing the use of resources', 'Service-based designing' and 'User interface optimized for mobile devices' which are needed to be largely considered for mobile application development environment when we compare with existing Agile-methodology. Therefore, it improves the usability, maintainability, efficiency of developed mobile applications. Through field tests, it is observed that S-MADP outperforms about 25% than a Agile-methodology in the aspect of the required man-month for developing a medium-large mobile application.