• Geophysics and Geophysical Exploration
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• v.2 no.4
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• pp.184-190
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• 1999

A study of gas hydrate is a worldwide popular interesting subject as a potential energy source. A seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. General indicators of natural submarine gas hydrates in seismic data is commonly inferred from the BSR (Bottom Simulating Reflection) that occurred parallel to the see floor, amplitude decrease at the top of the BSR, amplitude Blanking at the bottom of the BSR, decrease of the interval velocity, and the reflection phase reversal at the BSR. So the seismic data processing for detecting gas hydrates indicators is required the true amplitude recovery processing, a accurate velocity analysis and the AVO (Amplitude Variation with Offset) analysis. In this paper, we had processed the field data to detect the gas hydrate indicators, which had been acquired over the East sea in 1998. Applied processing modules are spherical divergence, band pass filtering, CDP sorting and accurate velocity analysis. The AVO analysis was excluded, since this field data had too short offset to apply the AVO analysis. The accurate velocity analysis was performed by XVA (X-window based Velocity Analysis). This is the method which calculate the velocity spectrum by iterative and interactive. With XVA, we could determine accurate stacking velocity. Geobit 2.9.5 developed by the KIGAM was used for processing data. Processing results say that the BSR occurred parallel to the sea floor were shown at $367\~477m$ depths (two way travel time about 1800 ms) from the sea floor through shot point 1650-1900, the interval velocity decrease around BSR and the reflection phase reversal corresponding to the reflection at the sea floor.

• Journal of the Korea Society for Simulation
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• v.24 no.1
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• pp.35-43
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• 2015

This research proposed a new method to evaluate the objective validity to launch smart transportation services that various stakeholders are complicatedly inter-connected. First of all, we have designed the fundamental business model to form the smart transportation services and defined the stakeholders taking part in the services. Also, the criteria to evaluate the economical validity has been proposed based on the relationship among stakeholders. Especially, in the case EV drivers and charging service providers, the economical validity depends on the scale of spreading. Therefore, we have compared the two extreme scenarios, the poor and stable level of EV spreading. According to the result, it may be said that EV drivers and charging service providers cannot be guaranteed the economical validity due to the burden of initial investment. On the contrary to this, suppliers of EV and charging gears may secure more than a certain level of profit. In addition, the government may have great profit due to reducing the CO2 emission and cost for importing energy sources. Therefore, it is needed to enhance the level of supporting EV drivers and charging service providers at the first stage. Also, the impact of the ratio of EV and charging service stations on the economical validity of smart transportation should be further investigated.

• Journal of the Korean Electrochemical Society
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• v.7 no.4
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• pp.183-188
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• 2004

In order to develop polymer electrolyte for lithium/sulfur batteries, highly microporous P(VdF-HFP) membranes were prepared by phase inversion method. Porous structure was controlled by extracting NMP with mixture of deionized water and methanol. Porous structure of the membranes was observed with SEM. Polymer electrolytes were prepared by soaking the porous membranes in 1M $LiCF_3SO_3-TEGDME/EC$. The ionic conductivity of polymer electrolyte was found to be at high as $2\times10^{-3}S/cm$ when the polymer membrane extracted by $80\%$ methanol was used. The microporous polymer electrolyte optimized in this work displayed high ionic conductivity, uniform pore size, low interfacial resistance and stable ionic conductivity with storage time. The ionic conductivity of polymer electrolytes was measured with various lithium salts, and the conductivity showed $3.3\times10^{-3}S/cm$ at room temperature when $LiPF_6$ was used as a lithium salt.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.977-980
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• 2015

Beacons have been noted in the core of the recent things Internet. It is also the technology is spreading most rapidly among the things Internet-related communication technologies. Beacon is a data communications technology that provides information that is customized to know the user's location. Using the BLE technology, to grasp the position of such people and goods. In addition to the non-contact method, since it is possible to communicate within the maximum 70m, it has attracted the interest than the NFC. Beacon, guidance for the current coupon, you can use as an advertising platform, such as the provision of product information, it has also been used in the indoor positioning service. Therefore, in this paper, we introduce about whether Case Study beacon is utilized how in the Internet of Things, were analyzed. Beacon exit the smart phone, the date to be used in conjunction with a wearable device, such as Google glasses and smart watch was not far away. Future it is expected or beacons are used everywhere to be expanded.

• The KIPS Transactions:PartC
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• v.16C no.1
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• pp.51-56
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• 2009

Time synchronization algorithm in wireless sensor networks is essential to various applications such as object tracking, data encryption, duplicate detection, and precise TDMA scheduling. This paper describes CDRS that is a time synchronization algorithm using the Clock Drift rate and Reference Signals between two sensor nodes. CDRS is composed of two steps. At first step, the time correction is calculated using offset and the clock drift rate between the two nodes based on the LTS method. Two nodes become a synchronized state and the time variance can be compensated by the clock drift rate. At second step, the synchronization node transmits reference signals periodically. This reference signals are used to calculate the time difference between nodes. When this value exceeds the maximum error tolerance, the first step is performed again for resynchronization. The simulation results on the performance analysis show that the time accuracy of the proposed algorithm is improved, and the energy consumption is reduced 2.5 times compared to the time synchronization algorithm with only LTS, because CDRS reduces the number of message about 50% compared to LTS and reference signals do not use the data space for timestamp.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.7
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• pp.449-455
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• 2016

Fog causes economic losses in transportation. It also results in health problems when it is combined with air pollutants. Considerable research efforts have focused on developing fog removal systems. However, most systems operate themselves after monitoring the fog. Additionally, continuous energy supply and maintenance are required to retain the fog-removal efficiency of the system. This study included the demonstration of a moss filter (a polyolefin mesh interlaced with moss) as a fog-removal method overcoming the limitations of the fog removal system. Three types of mosses with different surface structures were investigated to elucidate the relation between the moisture absorption rate and the structures. Among the different moss types, Hypopterygium japinicum showed the highest efficiency based on the smallest pore diameter and the largest total pore area. The visibilities with the moss filter and the polyolefin mesh were compared to perform the fog removal tests. The moss filter could provide a cost-effective and eco-friendly fog removal system with sustainability.

• Journal of the Korean Magnetics Society
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• v.21 no.2
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• pp.43-47
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• 2011

It is known that the Fe-Al transition metal compounds have a lot of disagreement about structural stability and magnetism. In this study, the correlation between magnetism and atomic structure of ordered $B_2$, $L1_2$, and $D0_3$ structured Fe-Al compounds has been investigated using the all-electron full-potential linearized augmented plane wave (FLAPW) method based on the generalized gradient approximation (GGA). We found that considered all the structures were calculated to be stabilized in a ferromagnetic state. The calculated spin magnetic moments of the Fe atoms for B2 and $L1_2$ structures were 0.771 and 2.373 ${\mu}_B$, respectively, and that of Fe(I) and Fe(II) in $D0_3$ structure calculated to be 2.409 ${\mu}_B$, 1.911 ${\mu}_B$, respectively. In order to investigate structural stability between $L1_2$ and $D0_3$ structures, we performed the formation enthalpy calculations. As a result, the $D0_3$ structure is found to be more favorable than $L1_2 one by energy difference 16 meV/atom, which is well consistent with the experimental observation. We understood about structural stability and magnetism for Fe-Al compounds in terms of analysis of their atomic and electronic structures.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.4
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• pp.177-190
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• 2016

In case of the seabed around and under gravity structures such as submerged breakwater is exposed to a large wave action long period, the excess pore pressure will be generated significantly due to pore volume change associated with rearrangement soil grains. This effect will lead a seabed liquefaction around and under structures as a result from decrease in the effective stress. Under the seabed liquefaction occurred and developed, the possibility of structure failure will be increased eventually. Lee et al.(2016) studied for regular waves, and this study considered for irregular waves with the same numerical analysis method used for regular waves. Under the condition of the irregular wave field, the time and spatial series of the deformation of submerged breakwater, the pore water pressure (oscillatory and residual components) and pore water pressure ratio in the seabed were estimated and their results were compared with those of the regular wave field to evaluate the liquefaction potential on the seabed quantitatively. Although present results are based on a limited number of numerical simulations, one of the study's most important findings is that a more safe design can be obtainable when analyzing case with a regular wave condition corresponding to a significant wave of irregular wave.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.335-342
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• 2013

Since the seriousness of environmental pollution came to the fore recently, various efforts have been made globally for the reduction of the environmental load. In particular, in the field of construction, an industry responsible for a considerable amount of pollution, studies have been actively conducted to reduce $CO_2$ emissions and energy consumption. However, most conventional research about pollution as it relates to construction is focused on the maintenance stages where $CO_2$ emissions are the greatest. Research related to the design stage is in its infancy, as it has only been conducted thus far on steel buildings and RC buildings. In fact, in order to achieve environmentally friendly construction considering the Life Cycle Assessment(LCA), the building design should be derived to reduce the $CO_2$ emissions from the early building design stage, and structural engineers should be able to suggest a design plan considering its environmental friendliness. In this study, optimal structural design method for steel reinforced concrete(SRC) columns considering $CO_2$ emissions is presented. The trends of $CO_2$ emissions in SRC columns according to the variations of steel shapes, concrete strengths and loads are investigated.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.555-566
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• 1987

Fifty ancient Korean coins originated in Yi Dynasty have been determined for 9 elements such as Sn, Fe, As, Ag, Co, Sb, Ir, Ru and Ni by instrumental neutron activation analysis and for 3 elements such as Cu, Pb, and Zn by atomic absorption spectrometry. Bronze coins originated in early days of the dynasty contain as major constituents Cu, Pb and Sn approximately in the ratio 90 : 4 : 3, whereas, those in latter days contain in ratio 7 : 2 : 0. Brass coins which had begun in 17 century contain as major constituents Cu, Zn and Pb approximately in the ratio 7 : 1 : 1. The multivariate data have been analyzed for the relation among elemental contents through the variance-covariance matrix. The data have been further analyzed by a principal component mapping method. As the results training set of 8 class have been chosen, based on the spread of sample points in an eigen vector plot and archaeological data such as age and the office of minting. The training set and test set of samples have finally been analyzed for the assignment to certain classes or outliers through the statistical isolinear multiple component analysis (SIMCA).