• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3540-3545
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• 2009

Due to recent development of high temperature high pressure(HTHP) diamond synthetic and treatment technology, we need to identify the natural diamonds fast, reliable, and economically. We proposed using new method of UV fluorescence and X-ray Lang topography imaging for distinguishing one synthetic diamond from four natural colored diamonds. We observe unique local stress field uneven image in synthetic diamond using UV fluorescence and Lang topography characterization, while uniform images in natural diamonds. Especially, X-ray Lang method offered the better identification power with better high resolution on stress field images.

• Journal of the Korean Institute of Gas
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• v.2 no.3
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• pp.18-24
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• 1998

This paper attempts to improve domestic natural gas pricing system, thereby optimizing social welfare. This is done by deriving theoretical frameworks of natural gas pricing, which make use of both Ramsey component pricing rule and Efficient component pricing rule based on the theory of marginal cost. Allocative efficiency and social welfare between gas prices derived from the three pricing mechanism, present Cost-based pricing, Ramsey component pricing rule and Efficient component pricing rule, are analysed and compared in the case study. For the city gas, allocative efficiency of Cost-based pricing is higher than that of Ramsey component pricing rule and Efficient component pricing rule. In contrast, for the natural gas consumed for power generation, allocative efficiency of Cost-based pricing is lower than the other two pricing systems. It also turns out that social welfare is improved by the prices driven from Ramsey component pricing rule and Efficient component pricing rule rather than present Cost-based pricing.

• Journal of the Korean Solar Energy Society
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• v.29 no.1
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• pp.32-37
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• 2009

Photovoltaic(PV) permits the on-site production of electricity without concern for fuel supply or environmental adverse effects. The electrical power is produced without noise and little depletion of resources. So BIPV(Building-Integrated Photovoltaic) system have been increased around the world. Hereby the relative installation costs of the system will be relatively low compared to traditional installations of PV in high-rise buildings. This paper examined possibility of building integrated balcony PV system and analyzed both performance and problems of this system. The system is influenced by conditions such as irradiation, module temperature, shade and architectural component etc. If this BIPV system of 1.1kW is possible the natural ventilation in the summer case, the temperature of PV module decrease and then the efficiency of PV system increase generally. By the results, the annual averaged PR of BIPV system of cold facade type is about 74.7%.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.349-353
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• 2001

Korea has a variety of favorable conditions for utilizing wind as energy. First of all, as a geographical characteristic, it is a peninsular country with its three frontiers surrounded by sea. Such a location makes the country influenced, all the year round, both by sea winds and by seasonal winds, so that it has a good possibility of putting its rich wind resources to use as an energy source. Particularly, in view of the results of observations and analysis of actual data about wind sources, it is quite possible to build wind paver plants in many regions across the country, such as inhabited islands dotted on its southern and western coasts around the Korean peninsular, a number of uninhabited islets attached the main islands, large-scaled reclaimed lands, and major inland areas. In Korea, the attempt to develop the technology of wind paver generation started in the 1970's. It was since 1988, when the Law on the promotion of Alternative Energy Development was enacted, that research and development activities for employing the wind force as a part of energy source have got into full swing. At that moment, however, due to the low level of domestic technological development, such efforts were mainly focused on the attainment of basic technologies with regard to wind power generation. Recently, there have been many noticeable changes in the international as well as domestic environments, such as the conclusion of the International Climate Treaty and the increase in public concerns of natural environment. It is quite possible to predict that the demand for wind paver generation will increase in the near future. Therefore, recognizing that wind, as a clean energy source, can be a promising method for coping with the International Climate Treaty and for replacing the fossil fuel, oil, this essay investigates the development history of wind paver generation systems and the status of technological development in Korea and presents an appropriate model for the development of the paver generation system that can compete with other energy sources.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.387-393
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• 2010

The purpose of this study was to compare pregnant women's gait parameters and mechanical energies caused by changes in hormone levels and anatomical features such as body mass, body-mass distribution, joint laxity, and musculo-tendinous strength from pregnancy to postpartum. Ten subjects (height: $161{\pm}6.5cm$, mass: $62.7{\pm}10.4\;kg$, $66.4{\pm}9.3\;kg$, $68.4{\pm}7.7\;kg$, $57.2{\pm}7.7\;kg$) participated in the four times experiments (the first, middle, last term and after birth) and walked ten trials at a self-selected pace without shoes. The gait motions were captured with Qualisys system and gait parameters were calculated with Visual-3D. Pregnant women's gait velocities were decreased during the pregnancy periods, but increased after birth. Stride width and cycle time were increased during pregnancy, but decreased after birth. Thigh energy (77.4%) was greater than shank energy (19.06%) or feet (3.54%) about total energy of the lower limbs. Their feet (Left R2=0.881, Right R2=0.852) and shank (Left R2=0.318, Right R2=0.226) energies were significantly increased (positive correlation), but double limb stance time (DLST, R2=0.679) and body total energy (R2=0.138) were decreased (negative correlation) for their velocities. These differences suggest that thigh segment may be a dominant segment among lower limbs, and have something to do with gait velocities. Further studies should investigate joint power and joint work to find energy dissipation or absorption from pregnancy period to postpartum.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.754-760
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• 2010

This study was carried out not only to evaluate optimal operating condition to increase biogas production, but also to estimate feasibility of renewable energy from anaerobic digester of sewage sludge. Semi- continuous Fed and Mixed Reactors (SCFMRs) were operated in various condition to quantify the reactor variables. The result of SCFMR operation showed that the biogas productivity and total volatile solids (TVS) removal of total solids (TS) 4% reactor at hydraulic retention time (HRT) 20 days with Organic Loading Rate (OLR) of $1.45kg/m^3-d$ were $0.39m^3/m^3-d$ and 26.7%, respectively which was two times higher than that of TS 2.5% reactor. Consequently the daily biogas production of $20,000m^3$ would be possible from the total volume of $52,000m^3$ of anaerobic digesters of the municipal wastewater treatment plant in D city. In feasibility study for the Biogas utilization, combined heat and power system (CHP) and CNG gasification were examined. In case of CHP, the withdrawal period of capital cost for gas-engine (GE) and micro gas-turbine (MGT) were 7.7 years and 9.1 years respectively. biogas utilization as Clean Natural Gas (CNG) shows lower capital cost and higher profit than that of CHP system. CNG gasificaion after biogas purification is likely the best alternative for Biogas utilization which have more economic potential than CHP system. The withdrawal period of capital cost appeared to be 2.3 years.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.69-76
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• 2010

Recently, the natural environment changes drastically and the frequency of occurrence for lightning has gradually been increased. Such lightning delivers high volume of energy along the power line and communication line to the equipment in use. The high volume of energy arising from the lightning surge develops in fast velocity to destroy the facilities in power source and many other facilities in operation in sequential destruction with vast energy. This paper examines the characteristics of ZnO varistor to prevent from thermal runaway. We carry out performance evaluation of electrical characteristics on ZnO varistor. we will develop ZnO varistor Prevented from thermal explosion using test result of this paper.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.385-392
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• 2014

The isolators have been generally used to reduce a seismic force. If the isolators apply to the nuclear power plants(NPPs), the durability and capacity for the structures and equipments should be ensured during the life time. In this study, the long-term behavior of isolated NPPs was analyzed for ensuring the seismic safety. The properties of isolator due to the age-related degradation were analyzed. And the seismic behavior of isolated buildings was analyzed by considering the aging of rubber bearings in different temperature environments. According to the analysis results, the natural frequency of structures was increased with time. But the maximum acceleration and maximum displacement of isolated structures have not changed significantly. Although the damaged of structure did not occurred by aging of isolators, it was presented that the spectral acceleration at the target frequency of isolated structure increased with the temperature. Therefore the isolators in the isolated buildings should be carefully designed and manufactured considering the temperature-dependancy of rubber material.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.77-85
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• 2009

Flexible and lined segment air-tight tunnelling technology for Compressed Air Energy Storage-Gas Turbine(CAES-G/T) power generation was introduced. The distinguished characteristics of the air-tight tunnel system can be summarized by two facts. One is that the high inner pressure due to compressed air is sustained by surrounding rock mass with allowing sufficient displacement of lining segment. The other is that the air-tightness of storage tunnel was enhanced by adopting a specially designed rubber sheet. The flexible lined air-tight underground tunnel can be constructed at a comparatively shallow depth and near urban area so that the locally distributed CAES-G/T power generation can be accomplished. In addition, this air-tight tunnelling technology can be applied to a variety of energy underground storage tunnels such as Compressed Natural Gas(CNG), Liquifed Petroleum Gas(LPG), DeMethyl Ether(DME) etc.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.46-51
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• 2016

The TMCP steel has expanded in the marine structure during manufacturing process because of its excellent weld-ability and impact toughness. In the case of merchant ships, coverage of TMCP steel has been used widely on over DH36 Classifications material. The line heating process is applied to the outer surface of the steel plate for the shipbuilding. In this study, We compared between TMCP and normalizing steel for shipbuilding by analyzing some basic data through performing the natural cooling after the line heating. The experimental results show the angular misalignment changes in line heating. Heated surface of normalizing steel material expanded to $-0.3^{\circ}$ and reduced to $+0.2^{\circ}$ after cooling. And during cooling at $194^{\circ}C$ for 1,500 seconds, Angular Misalignment began from - direction to + direction, passed the critical point to the default at 2,200 seconds and did not take place any more at $103^{\circ}C$ after the 2,700 seconds. Angular Misalignment results of TMCP steels and Normalizing steel material show same angular misalignment lasted 1,200 seconds, TMCP steel has given more expansion and contraction angle which is $0.2^{\circ}$ than that of the Normalizing steel. Length difference between expansion and contraction is about 0.3 mm.