• International Journal of Fluid Machinery and Systems
• /
• v.10 no.3
• /
• pp.209-217
• /
• 2017

The paper presents two novel concepts of increasing the energy storage capacity at pumped storage power plants, both existing and new projects. The concepts utilize compressed air as a working medium to displace water from a volume originally not available for storage. The concepts are likely to give additional storage volume at a low cost, however, much development and many investigations are needed before the concepts can be shown to be technical and economical feasible solutions for energy storage. The concepts are disclosed so that researchers and utilities can start those investigations, hopefully helping the green transition by providing highly valuable energy storage for a future renewable energy having a much higher share of renewable energies than the current systems.

• Journal of the Korean Geophysical Society
• /
• v.5 no.1
• /
• pp.63-71
• /
• 2002

The integral equation method is a powerful tool for electromagnetic numerical modeling. But the difficulty of this technique is the size of their linear equations, which demands excessive memory and calculation time to invert. This limitation of the integral equation method becomes critical in inverse problem. To overcome this limitation, a lot of approximation and series methods, such as conventional Born, modifed Born and extended Born, were developed. But all the methods need volume integration of Green tensor, which is very time consuming. In electromagnetic theory, Green tensor rapidly decreases as the distance between source and field cell increases. Therefore, the source cell which are far away from the field cell does not make an effect on the electric field of the field cell. Consequently, by ignoring the effect of Green tensor due to far away source cells, computing time for electromagnetic numerical modeling can be reduced dramatically. Comparisons of this new method against a full integral equation, extended Born approximation and series code show that the method is accurate enough much less time consuming.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.233-233
• /
• 2010

It is important to form the n+ emitter layer for generating electric potential collecting EHP(Electron-Hole Pair). In this paper the formation on the n+ emitter layer of silicon wafer has been made with respect to uniformity of shallow diffusion from a liquid source. The starting material was crystalline silicon wafers of resistivity $0.5{\sim}3\{Omega}{\cdot}cm$, p-type, thickness $200{\mu}m$, direction[100]. The formation of n+ emitter layer from the liquid $POCl_3$ source was carried out for $890^{\circ}C$ in an ambient of $N_2:O_2$::10:1 by volume. And than each conditions are pre-deposition and drive-in time. It has been made uniformity of at least. so, the average of sheet resistance was about 0.12%. In this study, sheet resistance was measured by 4-point prove.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.21 no.3
• /
• pp.255-263
• /
• 2018

This paper investigated design requirements for piston pumps, which were used as the power source of light rescue vehicle, and designed a piston pump satisfying such requirements. In order to satisfy the driving specification of the rescue device, the pump needs to be designed using the displacement volume of 110 cc/rev, the pressure of 350 bar and the rotation speed of 2,200 rev/min. The design was verified by flow and structural analyses respectively. The shape of the piston pump was optimized in terms of both flow characteristics and structural stability. A test equipment was also fabricated to verify the developed piston pump and test conditions were established. Finally, the developed piston pump was tested for its performance and operating temperature.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.6
• /
• pp.403-410
• /
• 2020

The difficulty of securing freshwater sources is increasing with global climate change. On the other hand, seawater is less affected by climate change and regarded as a stable water source. For utilizing seawater as freshwater, seawater desalination technologies should be employed to reduce the concentration of salts. However, current desalination technologies might accelerate climate change and create problems for the ecosystem. The desalination technologies consume higher energy than conventional water treatment technologies, increase carbon footprint with high electricity use, and discharge high salinity of concentrate to the ocean. Thus, it is critical to developing green desalination technologies for sustainable desalination in the era of climate change. The energy consumption of desalination can be lowered by minimizing pump irreversibility, reducing feed salinity, and harvesting osmotic energy. Also, the carbon footprint can be reduced by employing renewable energy sources to the desalination system. Furthermore, the volume of concentrate discharge can be minimized by recovering valuable minerals from high-salinity concentrate. The future green seawater desalination can be achieved by the advancement of desalination technologies, the employment of renewable energy, and the utilization of concentrate.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.19 no.3
• /
• pp.90-99
• /
• 2020

The "Low Emission Zone" (LEZ) system restricts entry of vehicles with high air pollutants into city centers. Implementation of the system improves air environment around the world. Since 2012, operating restrictions have been applied to all of Seoul's metropolitan areas and some other metropolitan areas in the state. Beginning in December 2019, entry of 5th class vehicles to the central green transport zone of Seoul has been restricted. In this study we examine the status of operational restrictions in this zone, and predict the amount of traffic reduction expected when numbers of target vehicles are expanded in the future, we use data for each vehicle's emission grade: by region and 'Origin-Destination Traffic Volume'. After estimating the amount of traffic entering Seoul's 25 autonomous districts, by emission class, we propose a target region that may have a significant effect if target areas for automobile operation restrictions expand in the future.

• Journal of Korean Society for Atmospheric Environment
• /
• v.28 no.3
• /
• pp.273-281
• /
• 2012

The government is carrying forward a sustainable development which reduces green-house gas and environmental pollution by preparing 'Low Carbon Green Development' policy basis as a new paradigm of national development. This study aims to understand the status of atmosphere contamination which Seoul has by finding correlation among social, economical indexes and carbon, the humanities and social characteristic materials which best express types of city and correlation and to suggest implications. According to the results of the analysis, first the carbon emission volume of Seoul recorded 0.56 ppm, Jongno, Jung-Gu, Kuro, Kangnam and Songpa were more than the average of Seoul and Kwangjin-Gu & Kangbuk-Gu, relative north east regions, Yeongdeungpo-Gu and Dongjak-Gu, south west regions showed lower CO occurrences. Second, according to the correlation and factor analysis, elements which affect CO emission volume of Seoul are largely represented by regional level, traffic level and development density level. Third, when the importance of influence factors based on the analyzed standard coefficient by a regression model, traffic and development density level were most important by recording traffic level (0.967), environmental level (0.385), regional level (0.530) and development density (0.561). Consequently, it was revealed that the traffic level most affected CO emission.

• Advances in nano research
• /
• v.15 no.4
• /
• pp.355-366
• /
• 2023

Biological corrosion, a crucial aspect of metal degradation, has received limited attention despite its significance. It involves the deterioration of metals due to corrosion processes influenced by living organisms, including bacteria. Soil represents a substantial threat to pipeline corrosion as it contains chemical and microbial factors that cause severe damage to water, oil, and gas transmission projects. To combat fouling and corrosion, corrosion inhibitors are commonly used; however, their production often involves expensive and hazardous chemicals. Consequently, researchers are exploring natural and eco-friendly alternatives, specifically nano-sized products, as potent corrosion inhibitors. This study aims to environmentally synthesize silver nanoparticles using an extract from Lagoecia cuminoides L and evaluate their effectiveness in preventing biological corrosion of buried pipes in soil. The optimal experimental conditions were determined as follows: a volume of 4 ml for the extract, a volume of 4 ml for silver nitrate (AgNO3), pH 9, a duration of 60 minutes, and a temperature of 60 degrees Celsius. Analysis using transmission electron microscopy confirmed the formation of nanoparticles with an average size of approximately 28 nm, while X-ray diffraction patterns exhibited suitable peak intensities. By employing the Scherer equation, the average particle size was estimated to be around 30 nm. Furthermore, antibacterial studies revealed the potent antibacterial activity of the synthesized silver nanoparticles against both aerobic and anaerobic bacteria. This property effectively mitigates the biological corrosion caused by bacteria in steel pipes buried in soil.

• The Korean Journal of Food And Nutrition
• /
• v.20 no.4
• /
• pp.399-405
• /
• 2007

The quality characteristics of breads made by adding levels of 30%, 60%, and 100% aloe gel were investigated. The 60% aloe gel sample had a larger dough volume than the control dough. Also, the loaf volume and specific volume of the bread made with 60% aloe gel were larger than those of the control bread. The pasting temperature increased gradually with the increasing amounts of substituted aloe gel as compared to wheat flour with water added$(66.5{\pm}12^{\circ}C)$; the wheat flour with 100% aloe gel had a pasting temperature of $90.7{\pm}1.1^{\circ}C$. Peak viscosity decreased gradually with increasing amounts of aloe gel when compared to the wheat flour with water added. Setback also was decreased gradually with the increasing amounts of aloe gel as compared to the wheat flour with added water. From the setback decrease it is suggested that the aloe controlled retrogradation of the bread during short-term storage. The crumb color of the bread made with the aloe gel was not significantly different to that of the control bread, and the color of the crumb was yellow-white. Bread hardness decreased gradually with increasing amounts of the substituted aloe gel. However, bread gumminess and chewiness increased gradually with increasing amounts of aloe gel. The springiness of the bread made with 100% aloe gel was lower than that of the control bread. With regard to flavor and taste, the bread made with 100% aloe gel produced a green-like odor and had a bitter taste. The mouth feel of the breads made with aloe gel was considered soft and moist. The overall acceptabilities of the breads made with 30% and 60% aloe gel were not significantly different from the control bread, but the bread made with 100% aloe gel had a green smell and bitter taste. Yet accordingly, the results indicate that functional and health products with improved quality could be developed by adding aloe gel to breads and cakes.

• Korean Journal of Environment and Ecology
• /
• v.24 no.2
• /
• pp.166-177
• /
• 2010

This study is to identify potential factors to impact on appearance of wildbirds which live in the core forest around urban area in Gangdong-gu, Seoul. As a result of analysis of, studies on biotope showed most of urbanization biotope was biotope of residential areas with high green coverage and biotope of residential and business areas with low green coverage while most of biotope of green and openspace was core green biotope. The research area was divided into several blocks based on biotope types in the urbanization areas excluding green and openspace. As a result of research on wildbirds, total 51 species 3,419 individuals appeared in spring and total 35 species 4,213 individuals appeared in winter. 24 wild bird species were selected as subjects of this study among 31 species seen in urbanization areas, since urban birds, rapacious birds, waterside birds were excluded from the study for the proper consideration. Then this study looked at how many species and individuals of the subjects were observed at each research block in urbanization areas during spring and winter separately. Landuse structure and green structure in each block were examined to see whether these structures affect the number of wild birds observed in urbanization areas of Gangdong-gu. Furthermore, the distance between these blocks and green was assessed. While studying the potential links between the landuse structure and the number of wild birds observed in urbanization areas of Gangdong-gu, block area, green coverage, and building-to-land ratio were believed to affect the number of types and species of wild birds in the research area. In terms of correlation analysis of whether green structure affected the number of wild birds observed in urbanization areas of Gangdong-gu, crown volume of layers, the average green patch area, the average height of canopy layer were found to have an impact not only on the number of types but also species of wild birds in the research area.