• Journal of the Speleological Society of Korea
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• no.68
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• pp.23-73
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• 2005

Purpose of study; The purpose of this study is specifically classified as two parts. The one is to attempt the chronological annals of Quaternary topographic surface through the study over the formation process of alluvial surfaces in our country, setting forth the alluvial surfaces lower-parts of Han River area, as the basic deposit, and comparing it to the marginal landform surfaces. The other is to attempt the classification of micro morphology based on the and condition premising the land use as a link for the regional development in the lower-parts of Han river area. Reasons why selected the Lower-parts of Han river area as study objects: 1. The change of river course in this area is very serve both in vertical and horizontal sides. With a situation it is very easy to know about the old geography related to the formation process of topography. 2. The component materials of gravel, sand, silt and clay are deposited in this area. Making it the available data, it is possible to consider about not oかy the formation process of topography but alsoon the development history to some extent. 3. The earthen vessel, a fossil shell fish, bone, cnarcoal and sea-weed are included in the alluvial deposition in this area. These can be also valuable data related to the chronological annals. 4. The bottom set conglometate beds is also included in the alluvial deposits. This can be also valuable data related to the research of geomorphological development. 5. Around of this area the medium landform surface, lower landform surface, pediment and basin, are existed, and these enable the comparison between the erosion surfaces and the alluvial surfaces. Approach : 1. Referring to the change of river beds, I have calculated the vertical and horizontal differences comparing the topographic map published in 1916 with that published in 1966 and through the field work 2. In classifying the landform, I have applied the method of micro morphological classification in accordance with the synthetic index based upon the land conditions, and furthermore used the classification method comparing the topographic map published in 1916 and in that of 1966. 3. I have accorded this classification with the classification by mapping through appliying the method of classification in the development history for the field work making the component materials as the available data. 4. I have used the component materials, which were picked up form the outcrop of 10 places and bored at 5 places, as the available data. 5. I have referred to Hydrological survey data of the ministry of Construction (since 1916) on the overflow of Han-river, and used geologic map of Seoul metropolitan area. Survey Data, and general map published in 1916 by the Japanese Army Survbey Dept., and map published in 1966 by the Construction Research Laboratory and ROK Army Survey Dept., respectively. Conclusion: 1. Classification of Morphology: I have added the historical consideration for development, making the component materials and fossil as the data, to the typical consideration in accordance with the map of summit level, reliefe and slope distribution. In connection with the erosion surface, I have divided into three classification such as high, medium and low-,level landform surfaces which were classified as high and low level landform surfaces in past. furthermore I have divided the low level landform surface two parts, namely upper-parts(200-300m) and bellow-parts(${\pm}100m$). Accordingly, we can recognize the three-parts of erosion surface including the medium level landform surface (500-600m) in this area. (see table 22). In condition with the alluvial surfaces I have classified as two landform surfaces (old and new) which was regarded as one face in past. Meamwhile, under the premise of land use, the synthetic, micro morphological classification based upon the land condition is as per the draw No. 19-1. This is the quite new method of classification which was at first attempted in this country. 2. I have learned that the change of river was most severe at seeing the river meandering rate from Dangjung-ni to Nanjido. As you seee the table and the vertical and horizontal change of river beds is justly proportionable to the river meandering rate. 3. It can be learned at seeing the analysis of component materials of alluvial deposits that the component from each other by areas, however, in the deposits relationship upper stream, and between upper parts and below parts I couldn't always find out the regular ones. 4. Having earthern vessel, shell bone, fossil charcoal and and seaweeds includen in the component materials such as gravel, clay, sand and silt in Dukso and Songpa deposits area. I have become to attempt the compilation of chronicle as yon see in the table 22. 5. In according to hearing of basemen excavation, the bottom set conglomerate beds of Dukso beds of Dukso-beds is 7m and Songpa-beds is 10m. In according to information of dredger it is approx. 20m in the down stream. 6. Making these two beds as the standard beds, I have compared it to other beds. 7 The coarse sand beds which is covering the clay-beds of Dukso-beds and Nanjidobeds is shown the existence of so-called erosion period which formed the gap among the alluvial deposits of stratum. The former has been proved by the sorting, bedding and roundness which was supplied by the main stream and later by the branch stream, respectively. 8. If the clay-beds of Dukeo-bed and Songpa-bed is called as being transgressive overlap, by the Eustatic movement after glacial age, the bottom set conglomerate beds shall be called as being regressive overlap at the holocene. This has the closest relationship with the basin formation movement of Seoul besides the Eustatic movement. 9. The silt-beds which is the main component of deposits of flood plain, is regarded as being deposited at the Holocene in the comb ceramic and plain pottery ages. This has the closest relationship with the change of river course and river beds.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.721-724
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• 2005

With the advantages of large vibration energy dissipation of structures, the granular materials are used as vibration and acoustic treatments. In this case of vibro acoustic controls, a finite dynamic strength of the solid component (frame) is an important design factor. The dynamic stiffness of hollow cylindrical beams containing porous and granular materials as damping treatment was measured. Using the Rayleigh-Ritz method, the effects of damping materials on the dynamic characteristics of beams were investigated. The results suggested that the acoustic structure Interaction between the frame and the structure enhances the dissipation of the vibration energy significantly. The same methods were applied also to vibration control of sandwich panels. By filling the cavities of honeycomb cores using unconsolidated granular materials, its sound transmission toss was improved significantly.

• Carbon letters
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• v.4 no.4
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• pp.180-184
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• 2003

The role of KOH in the one-stage KOH-activation of rice straws was studied using FTIR, XPS, TGA, and DTG techniques. It was found that at the impregnation, KOH extracts to some extent the lignin component from rice straw and reacts with hydroxyl groups. On heat-treatment, the impregnated KOH facilitates intermolecular condensation reaction on one hand but retards the thermal degradation of cellulose molecules on the other hand. The oxygen-containing surface functional groups newly created by oxidation of KOH may facilitate the bulk, not controlled, consumption of carbon atoms so that the effective porosities may not be able to be developed by the one-stage activation process.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.10-17
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• 2005

In this paper, the life cycle assessment(LCA) methodology is applied to Personal Computer's basic materials in order to analyze the impact to the environment. LCA data collection is carried out taking into account on main materials of PC's parts and component. And the impact assessment is the environmental burden on three factor into air emission(CO2, SOx, NOx), five factor into water emission(BOD, COD, SS, N, P), and three factor on transported substance(cl, NH4, SO4). According to the result, the environmental burden of PC's basic materials was proved to be used total energy 6,285Mj and emitted CO2 259.8kg, SOx 3,571g, NOx 330g, COD 1,328g, P 246g, N 2,434g. And this paper was presented the problems of its disposition-incinerating, landfill, and recycling.

• Korean Journal of Materials Research
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• v.25 no.10
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• pp.537-542
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• 2015

One-dimensional (1D) silver nanostructures, which possess the highest conductivity among all room-temperature materials, moderate flexibility and high transmittance, are one of the most promising candidate materials to replace conventional indium tin oxide transparent electrodes. However, the short length and large diameter of 1D silver nanostructures cause a substantial decrease in the optical transparency or an increase in the sheet resistance. In this work, ultra-long silver nanofiber networks were synthesized with a low-cost and scalable electrospinning process, and the diameter of the nanofibers were finetuned to achieve a higher aspect ratio. The decrease in the diameter of the nanofibers resulted in a higher optical transparency at a lower sheet resistance: 87 % at $300{\Omega}/sq$, respectively. It is expected that an electrospun silver nanofiber based transparent electrode can be used as a key component in various optoelectronic applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.28-28
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• 2010

Photoelectrochemical solar cells such as dye-sensitized cells (DSSCs), which exhibit high performance and are cost-effective, provide an alternative to conventional p-n junction photovoltaic devices. However, the efficiency of such cells plateaus at 11-12%, in contrast to their theoretical value of 33%. Improvements in efficiency can only occur through a fundamental understanding of the underlying physics, materials, and device designs of DSSCs. A photoelectrode consisting of semiconducting oxide nanoparticles and a transparent conducting oxide electrode (TCO) is a key component of DSSC and design of photoelectrode materials is one of promising strategies to improving energy conversion efficiency. We introduce monodisperesed $TiO_2$ nanoparticles prepared by forced hydrolysis method and their superiority as photoelectrode materials was characterized with aids of optical and electrochemical analysis. Multi-layered TCO materials are also introduced and their feasibility for use as photoelectrodes is discussed in terms of optical absorption and charge collecting properties.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.2
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• pp.47-54
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• 2020

To develop the bright-vivid red- and yellow-inorganic fluorescent pigments with high luminescence properties, A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments were synthesized by a water assisted solid state reaction (WASSR) method and a conventional solid state reaction method. Although impurity peaks corresponding to the AVO₃ and AV₃O₈ (A = K, Rb, and Cs) were observed in all samples prepared, the trigonal structure A₃V₅O₁₄ (A = K and Rb) and orthorhombic structure Cs₂V₄O₁₁ were successfully obtained as a main phase. These inorganic pigments showed the broad absorption band (under 550 nm) originated from CT transitions of VO₄ polyhedron, and the strong broad red- and green-emission bands due to ³T₂ → ¹A₁ and ³T₁ → ¹A₁ transitions of the [VO₄]^3- group. The A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ pigments showed a bright-vivid red- and yellow-body color, where the a* values of the A₃V₅O₁₄ (A = K and Rb) were +35.5 and +45.9, respectively, and b* value of Cs₂V₄O₁₁ pigments was +50.3. The L* values of the A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments were over +45. These results indicate that the A₃V₅O₁₄ (A = K and Rb) and Cs₂V₄O₁₁ inorganic pigments could be an attractive candidate as a bright-vivid red- and yellow inorganic pigments.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.351-354
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• 2006

We developed highly efficient fluorescent dopants for full-color OLEDs. For blue, green and red OLEDs, current efficiencies of 8.7cd/A, 20.5 cd/A and 11.4 cd/A at $10mA/cm^2$ were achieved, respectively. Lifetime of the blue device was estimated to be 23,000hours at an initial luminance of $1,000cd/m^2$. Moreover, long lifetime over 100,000 hours was estimated in the green and red devices. Furthermore, we obtained a three-component white OLED by using these new fluorescent materials. This white OLED shows a current efficiency of 16.1cd/A with extrapolated lifetime over 70,000 hours at $1,000cd/m^2$, and more excellent color reproducibility for full-color displays with color filters and general lighting, compared to previous fluorescent white OLEDs.

• Advances in concrete construction
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• v.3 no.3
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• pp.223-236
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• 2015

Concrete is the most widely used material of construction. Concrete gained the popularity as a construction material due to the easy availability of its component materials, the easy formability, strength and rigidity upon setting and curing.In construction industry, strength is the primary criterion in selecting a concrete for a particular application. Now a days, the substantial amount of waste materials, containing the properties of the Pozzolana, is being generated from the major industries; and disposal of such industrial wastes generated in abundance is also a serious problem from the environmental and pollution point of view. On this backdrop, efforts are made by the researchers for exploring the possible utilization of such waste materials in making the sustainable construction material. The present paper reports the experimental investigations to study the strength characterization of concrete made from the pozzolanic waste materials. For this purpose, the Pozzolanic materials such as fly ash and ground granulated blast furnace slag were used as a cement replacing materials in conjunction with ordinary Portland cement. Equal amount of these materials were used in eight trial mixes with varying amount of cement. The water cement ratio was also varied. The chemical admixture was also added to improve the workability of concrete. The compressive strengths for 7, 28, 40 and 90 days' were evaluated whereas the flexural and tensile strengths corresponding to 7, 28 and 40 days were evaluated. The study corroborates that the pozzolanic materials used in the present investigation along with the cement can render the sustainable concrete.

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.509-517
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• 1995