• Carbon letters
• /
• v.4 no.1
• /
• pp.1-9
• /
• 2003

Recently, the control of pore-characteristics of nano-porous materials has been studied extensively because of their unique applications, which includes size-selective separation, gas adsorption/storage, heterogeneous catalysis, etc. The most widely adopted techniques for controlling pore characteristics include the utilization of pillar effect by metal oxide and of templates such as zeolites. More recently, coordination polymers constructed by transition metal ions and bridging organic ligands have afforded new types of nano-porous materials, porous metal-organic framework(porous MOF), with high degree and uniformity of porosity. The pore characteristics of these porous MOFs can be designed by controlling the coordination number and geometry of selected metal, e.g transition metal and rare-earth metal, and the size, rigidity, and coordination site of ligand. The synthesis of porous MOF by the assembly of metal ions with di-, tri-, and poly-topic N-bound organic linkers such as 4,4'-bipyridine(BPY) or multidentate linkers such as carboxylates, which allow for the formation of more rigid frameworks due to their ability to aggregate metal ions into M-O-C cluster, have been reported. Other porous MOF from co-ligand system or the ligand with both C-O and C-N type linkage can afford to control the shape and size of pores. Furthermore, for the rigidity and thermal stability of porous MOF, ring-type ligand such as porphyrin derivatives and ligands with ability of secondary bonding such as hydrogen and ionic bonding have been studied.

• Conservation Science in Museum
• /
• v.12
• /
• pp.1-7
• /
• 2011

The seated stone Buddha(Bon5190) of National Museum of Korea initially consisted of some 90 fragments, making it difficult to guess its overall appearance. Under a restoration work which lasted four months, the fragments were joined together, giving shape to a seated Stone Buddha in Bhumisparsa(earth touching) mudra and an associated figure of Bodhisattva missing the face. The statue was made from a single stone block by digging out the center. Traces of lacquer coating and a gilded layer above the lacquer coat were found in various parts. Polarizing microscopy and XRD analysis revealed that the stone was zeolite, a mineral formed through diagenesis of volcanic glassy ashes from trachytic tuff (Nuldaeri) and dacitic tuff (Guryongpo). In Korea, zeolite deposit found mostly in Gyeongsangbuk-do, in places like Yeonil, Guryongpo, Gampo and Ulsan. The restored statue of seated Buddha proved very similar in appearance to the seated stone Buddha of Deoksa Temple in Cheongdo-gun, Gyeongsangbuk-do (housed in Yeongsanjeon Hall). The scroll inside the statue, containing information about the background and circumstances of creation of this Buddhist sculpture, indicates that the monk Seung-ho took part in it as the head sculptor-monk.

• Geotechnical Engineering
• /
• v.12 no.5
• /
• pp.137-154
• /
• 1996

Pull-out tests for three different types of strip reinforcements are performed to investigate variation of the apparent coefficient of friction which occurs between the reinforcements and the weathered granite soils with different contents of fine materials. The contents of fine materials for the soil sample are varied from 7% to 36% and the reinforcements used for the pullout tests are smooth, ribbed steel strips and a textured shape Paraweb 1 Friction tie. Test results show that the apparent coefficient of friction tends to decrease with the increase of the content of fine meterials. It is known, however, that the minimum apparent coefficient of friction required to the design of reinforced earth structures can be achieved even at 35% fine contents by using appropriate reinforcements. The ribbed strip reinforcement is found to be the most effective in mobilizing the apparent friction when interacting to finer weathered granite soils. The textured reinforcement is also useful for 35% fine con tents if the textured depth is increased.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.14 no.4
• /
• pp.437-451
• /
• 2012

Application of 3D laser scanner to civil engineering is widely studied in various fields such as tunnel, bridge, calculation of earth volume, construction measurement, observation of rock joint, etc. Some studies on utilization of the 3D laser scanner for calculating the over-break and/or under-break of tunnels have also been carried out. However, in the previous research, the scanning data were usually compared with the 2D CAD blueprint results; although the shape of tunnel structure is relatively simple, for precise calculation of the over-break and/or under-break of tunnels, three-dimensional analysis based on BIM is needed. Therefore, in this paper, a new program that calculates the over-break and/or under-break of tunnels using the 3D laser scanner and the BIM is developed; moreover the effective and rapid process of data treatment is proposed. The accuracy of the developed program was verified by applying the new system to a real tunnels construction field.

• Journal of Environmental Science International
• /
• v.24 no.3
• /
• pp.291-302
• /
• 2015

The seasonal variations of sea surface winds and significant wave heights were investigated using the data observed from the marine meteorological buoys (nine stations) and Automatic Weather Stations (AWSs) in lighthouse (nine stations) around the Korean Peninsula during 2010~2012. In summer, the prevailing sea surface winds over the East/West Sea and the South Sea were northerly/southerly and easterly/westerly winds due to both of southeast monsoon and the shape of Korean Peninsula. On the other hand, the strong northerly winds has been observed at most stations near Korean marginal seas under northwest monsoon in winter. However, the sea surface winds at some stations (e.g. Galmaeyeo, Haesuseo in the West Sea) have different characteristics due to topographic effects such as island or coastal line. The significant wave heights are the highest in winter and the lowest in summer at most stations. In case of some lighthouse AWSs surrounded by islands (e.g. Haesuseo, Seosudo) or close to coast (e.g. Gangan, Jigwido), very low significant wave heights (below 0.5 m) with low correlations between sea surface wind speeds and significant wave heights were observed.

• Journal of the Korean GEO-environmental Society
• /
• v.22 no.12
• /
• pp.71-77
• /
• 2021

As the number of using road in Korea increases, maintenance costs and traffic congestion costs also increase. In order to reduce maintenance cost and time of road, existing long - lived modular road system has been proposed. In this study, the design and performance evaluation of the adaptable support module, which is the substructure of the proposed system, was performed. Two adaptable (Cross-Beam type)support modules were designed and fabricated to determine the load and shape. A adaptable support module was constructed and a static load test was carried out to select the type with better performance. As a result of the load test, the maximum value of the measured earth pressure difference is about 158 kPa and the settlement amount is about 0.032 mm in the two types of adaptable support modules. Based on these results, it is concluded that the performance of the adaptable support module of the bottom curved cross-beam type is better.

• Spatial Information Research
• /
• v.19 no.2
• /
• pp.29-36
• /
• 2011

This study performed quantitative assessment of the performance of adjustment models by a-priori analysis of the statistics of the surface parameter estimates against modeling factors. Lidar, airborne imagery, and SAR imagery have been used to acquire the earth surface elevation, where the shape properties of the surface need to be determined through neighboring observations around target location. In this study, parameters which are selected to be estimated are elevation, slope, second order coefficient. In this study, several factors which are needed to be specified to compose adjustment models are classified into three types: mathematical functions, kernel sizes, and weighting types. Accordingly, a-priori standard deviations of the parameters are computed for varying adjustment models. Then their corresponding confidence regions for both the standard deviation of the estimate and the estimate itself are calculated in association with probability distributions. Thereafter, the resulting confidence regions are compared to each other against the factors constituting the adjustment models and the quantitative performance of adjustment models are ascertained.

• Journal of Aerospace System Engineering
• /
• v.18 no.3
• /
• pp.27-33
• /
• 2024

According to the success of the Nuri Space Launch Vehicle (KSLV-II) and the development goal of the next generation space launch vehicle (KSLV-III), it is expected that the domestic geostationary satellite capability will be increased from (1 to 3.7) ton. Also, it is predicted that substantial ability of about 1 ton can be provided for the space exploration of the Moon, Mars, asteroids, etc. The Goheung space launch site is optimized for sun-synchronous small satellites, and due to the essential precondition that the launch trajectory does not impinge another country's sovereign airspace, it is not satisfactory as a geostationary satellite launching site. Its latitude also requires more energy to shape the rotating orbital plane from the initial injection status. This results in a decreasing factor of economic feasibility, including the operating complexity. Therefore, in parallel with the development of a next generation space launch vehicle, the practical process for acquisition of oversea land or sea space launch site near the Earth's equator and research for the optimization of orbiting methods of geostationary satellite injection must be continued.

• Journal of the Korean Geophysical Society
• /
• v.2 no.1
• /
• pp.57-64
• /
• 1999

To effectively identify near-surface faults with vertical slips from seismic refraction data, the GRM interpretation technique is tested and investigated in terms of various parameters through computer modeling. A characteristic change in shape of the velocity-analysis function near faults is noticed, and a new strategy of `Slope Variation Indicator (SVI)' is developed and tested in this study. The SVI is defined as a first horizontal derivative of the difference of velocity analysis functions for a large XY value and a small one, respectively. As the dip of refractor decreases and as the difference in XY value increases, the peak value of SVI increases and its duration decreases. Consequently, the SVI indicates accurately the location of buried fault in the test models. The SVI is believed to be an efficient tool in seismic refraction method to investigate location and distribution of shallowly buried faults.

• Geophysics and Geophysical Exploration
• /
• v.9 no.2
• /
• pp.148-154
• /
• 2006

The effect of small-scale near surface inhomogeneity on Rayleigh wave propagation and dispersion has been investigated in this study using two-dimensional FEM elastic modeling. Various inhomogeneity models with a variety of geometrical shape and embedment depth which exist in homogeneous half-space and two-layered media are considered. Results show that any near surface inhomogeneity greater than one wavelength in terms of minimum wavelength of Rayleigh wave shows dispersion characteristics. Such dispersion effect become stronger as the dimensions of the inhomogeneity increase. The effect of horizontal dimension is more dominant factor governing the dispersion characteristics than vertical dimension. However, the dispersion effect can not be identifiable in seismogram if the horizontal dimension is not wide enough. Nonetheless, even in this case, the existence of inhomogeneity can be inferred by the reflection or transmission event of Rayleigh wave. The results can be expected to provide insights on the behavior of Rayleigh wave which may be helpful for designating field work or new processing scheme to detect near surface inhomogeneity by surface wave method.