• Polymer(Korea)
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• v.27 no.4
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• pp.323-329
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• 2003

Stretchable Polypyrrole films using functionalized doping agent, di(2-ethylhexyl) sulfosuccinate sodium salt (NaDEHS), were synthesized by chemical and electrochemical method. Chemically and electrochemically Prepared Polypyrrole films were stretch-oriented (L/L$\_$0/＝ 1.0 ∼ 2.5) by zone drawing method and the electrical conductivities were measured. As the draw ratio was increased, the electrical conductivities were increased. This result was confirmed by the increase in crystallinity through the increase in draw ratio. The temperature dependence of electrical conductivity showed that 3D-variable range hopping model (L/L$\_$0/ ＝ 1.0∼2.0) and ID-VRH model (L/L$\_$0/ ＝ 2.5) gave the best fit to the data for stretched Ppy-DEHS films.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.57-64
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• 2001

The high speed in the wire-drawing process to meet the demands for the increased productivity has a great effect on the heat generated due to plastic deformation and friction between the wire and the drawing dies. During the high carbon steel wire drawing process, the temperature rise gives a great influence to the fracture of wire. In this paper, to control the temperature rise in the wire after the deformation through the drawing die, the calculation method of the wire temperature, which includes the temperature rise in the deformation zone as well as the temperature drop in the block considering the heat transfer among the wire, cooling water and surrounding air, is proposed. These calculated results of the wire temperature at the inlet and exit of the drawing die at each pass are compared with the measured wire temperatures and verified its efficiency. So, using the program to predict the wire temperature, the isothermal pass schedule program was developed. By applying this isothermal pass schedule program to the conventional process condition, a new isothermal pass schedule is redesigned through all passes. As a result, the possibility of wire fracture could be considerably reduced and the productivity of final product could be more increased than before.

• 한국터널공학회:학술대회논문집
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• 2005.04a
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• pp.117-128
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• 2005

This Paper present design parameters of grouting by reviewing several published equations and the results of coupled analysis considering the difference of permeability between soil and grouted zone. Also, the feasibility of couped analysis in the design of grouting is studied for seeping water quantity into tunnel, displacement of tunnel face, drawing down of groud water table, settlement of ground and stress of tunnel supports.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.904-909
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• 2004

The study area adjoins with Yangsan fault in Sangbuk-myeon, Samsam-ri, Kyongsang-namdo and consist of the natural steep slope. After drawing data layer which have altitude by using digital topography data, it is converted to lattice DEM of $10m{\times}10m$ size. From this, gradient map of unit lattice, slant direction map and shadow relif map are made. Using flow apportioning algorithm, upper slope contributing area and wetness index by established lattice can be calculated. Area that have high wetness index shows lineament structure of northwest-southeast direction, and this agrees with shear fracture system. The result of electricity specific resistance survey in the study area shows that area of high wetness index has low electricity specific resistance anomaly. That is, wetness index conforms with distribution of fractured zone that accompanied chemical weathering of rock. Therefore, wetness index can be used as the method of detecting fractured zones and judging the stability of the area.

• Progress in Superconductivity
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• v.3 no.1
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• pp.130-133
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• 2001

A multifilamentary Bi-2223 HTS tape for superconducting power applications was studied through the fabrication of 250-meter long tapes by the PIT(powder in tube) process. To fabricate continuous long wire, a drawing machine, a two-drum bull block and a rolled tape winding machine were developed. Especially, 250-meter long tapes were heat treated in the shape of pancake coil to reduce the heat affect zone and to achieve the high critical current. Engineering critical current density was improved through both the enhancements of critical current density by control of thermal process and the increase of filling factor by using thin Ag alloy sheath tubes less than 1.5 mm in thickness. We have made successfully 250-meter long 37 filamentary tapes with high filling factor up to 31 % employing the modified drawing and rolling technique. The critical current of 250-meter long tapes with pancake coil type was measured by transport method at self-field up to 250 gauss of center field. The measured values, based on the transport critical current at self-field, $I_{c}$ -B characteristics and magnetic field analysis, are 34 A of I$_{c}$ and 4.0 $kA/\textrm{cm}^2$ of $J_{e}$ at 250 m, 77 K, and 0 T. We also have achieved the 56 A of I$_{c}$ and 7.0 $0 kA/\textrm{cm}^2$ of$ J_{e}$ in short tapes at 77K, self-field, and 1$mutextrm{V}$/cm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.2
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• pp.7-15
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• 1993

In order to generate database, we need to obtain speedy and corret topographic information according to requisite purpose. Generally methods to an acquisition of topographic information are available by the use of maps, satellite images, stereo models of aerophoto and so forth. But we must choose a optimal method in consideration of area of object region, spatial solution of image, required accuracy and economic. Therefore, this study aims at providing the establish method of efficient topographic data base of small object region by means of spatial layer techniques of geo-spatial information system and using acquisition of geo-information and production method of base map with photoballoon system to obtain topographic information for reasonable plan and design of object region which select a zone preparation of a collective village with small region. As a result of this study, we decided an f-stop and a shutter speed of camera to obtain accurate stereo model and were able to obtain stereo photography and topography for small region by using of photoballoon system through accuracy analysis according to change flight height and air base speedly and economically. We can establish the data base useable to efficient plan and design as existence map with overlay plan drawing.

• Transactions of Materials Processing
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• v.27 no.1
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• pp.37-47
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• 2018

In this paper, a double spot welding process, utilizing electric resistance heating dies, is suggested for the spot welding of dissimilar metal plates for drawing and concurrent spot welding. This double welding process has two heating methods for the fusion welding at the interfacial zone between steel and aluminum plates, such as heating method by thermal conduction of electric resistance by welding current induced to heating dies, and heating method by electric resistance between contacted surfaces of two plates by welding current induced to copper electrode. This double welding process has welding variables such as each current induced in heating dies and in copper electrode, outer diameters of heating dies, and edge shape of copper electrode. Experiments for current conditions in welding process should be demanded in order to get successful welding strength. It was known that the welding strength could be reached to the value demanded on industry fields under such welding conditions as heating dies of outer ring dia.12mm contacted on steel plate, as heating dies of outer ring dia. 14mm contacted on aluminum plate, and as copper electrode of dia. 6.0mm, and as 3 times continuous heating method by $1^{st}$ current of 11 kA(9cycle), $2^{nd}$ current 11 kA(60cycle), $3^{rd}$ current 7 kA(60cycle) applied in steel heating dies and copper electrodes, flat edge of copper electrode, for double spot welding process of dissimilar metal plates of steel and aluminum of 1.0 mm thickness.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.2
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• pp.11-25
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• 2001

A wetland is an ecosystem which is the most useful and highly-energetic transition area. This study has been carried out to classify and identify the various types of wetlands in Korea. The main objective of this study are 1) defining and classifying of wetlands, and 2) identifying the wetlands characteristics, and 3) studying cases on the natural wetlands such as Han river, DMZ(Demillitarized Zone), Upo wetland and Yong(Dragon) wetland. The results as follows： 1) Development of the indices for identifying and classifying wetlands in encompassing in such as Ramsar Conference, US NWI(National Wetlands Inventory), Hydrogeomorphic system. 2) Development on the classifying method on the wetlands in the level of supersystem, system, subsystem, class and subclass. The systems include Palustrine and Riverine, and the subsystems are Seasonal, Permanent(Palustrine) and Impersistent, Lower perennial, Impersistent (Riverine). 3) Finally, we find out Young wetland is Palustrine/Permanent/Slope/Persistent, and Upo wetland consists of various types of wetlands, those are, Palustrine/Permanent/Depression/Forest Deciduous, Palustrine/Permanent/Depression/Shrub Deciduous, Palustrine/Permanent/Depression/Persistent, Palustrine /Permanent/Depression/Hydrophytes, and Lacustrine/Permanent/Openwater/Hydrophytes. The taxonomy of this study stems from identifying and classifying wetlands with indices mainly based on hydrologic features and substrates. So, it is needed that consequent studies are to be performed with various viewpoints. And the studying cases were limited because of the restricted entrance into the DMZ, And, we selected only 10 crucial sites in Han river as the subject for wetlands regulation and creation. And, for advanced studies, drawing up inventory and mapping are necessary.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.97-104
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• 2015

The pollution of particulate matter (PM) is considered one of the hot socioenvironmental issues at present time. In this study, we investigated the distribution of fine particulate matter ($PM_{2.5}$) in Wangsimni commercial areas in Seoul, Korea to learn more about its environmental behavior in an urban area. Our analysis of $PM_{2.5}$ was made to distinguish the $PM_{2.5}$ pollution levels between three different types of site characteristics: (1) densely populated area, (2) thinly populated area, and (3) traffic roadside. Moreover, to assess the temporal trends in our study, the concentration levels of $PM_{2.5}$ were also compared between weekdays and weekends and between early in the afternoon and evening. The average concentration of $PM_{2.5}$ from densely and thinly populated areas were measured as $36.0{\pm}13.1$ and $32.3{\pm}11.2{\mu}g/m^3$, respectively. If the results are compared between different time bands, there were apparent differences between weekdays ($29.6{\pm}10.8{\mu}g/m^3$) and weekends ($36.9{\pm}12.1{\mu}g/m^3$). Such difference was also evident between noon ($27.8{\pm}5.8{\mu}g/m^3$) and evening ($38.3{\pm}13.7{\mu}g/m^3$). According to our research, concentration of $PM_{2.5}$ in the study area was affected more sensitively by time zone rather than the population density. The measurement data was also analyzed by drawing concentration map of $PM_{2.5}$ in the Wangsimni commercial areas based on data contouring method.