• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.403-410
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• 2005

This Paper Presents development of solar may shunt switching unit with a fully regulated Power regulation for Geostationary Earth Orbit(GEO) satellite. This shunt switching unit comprises the solar may shunt modules that regulate the solar array power. These solar array shunt modules connect/disconnect the solar array segments to/from the bus through switching actions. And that is also possible simply extension to an existing design by FPGA control logic changing. In order to verify the proposed design, the control logic and worst case analysis are analyzed and the simulation and experimental results we shown.

• Journal of the Korean earth science society
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• v.26 no.8
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• pp.751-758
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• 2005

The purpose of this study was to develop an inquiry analysis framework based on the features of earth science inquiry methodology and to analyze inquiry activities in the 8th grade 'Earth History and Diastrophism' unit by using this framework. The framework classified earth science methods as logical inference, hermeneutic, and historical methods, each of which was subdivided in consideration of its subordinate methods and characteristics. The analysis revealed that the logical inference method reflected in the unit as the 'abductive method' (70%) was used more frequently than the 'inductive' (23%) and 'deductive' (22%) methods. The hermeneutic method was found in terms of the 'forestructures of understanding' (92%), 'circular reasoning' (9%). and 'historical nature of human understanding' (17%). The historical method also used as the 'constructing proper taxonomy' (53%), 'adhering to the modem principle of uniformitarianism' (47%), and 'relic interpretation' (41%) were identified with ratios more fester than those for the 'place substituting for time in stage theorizing' (3%) and 'evaluating independent lines of inquiry for convergence' (3%).

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.55-61
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• 2005

Mononobe-Okabe method is generally used to evaluate dynamic earth pressure for the seismic design of retaining walls. However, Mononobe-Okabe method does not consider the effects of dynamic interactions between backfill soil and walls. In this research, shaking table tests on retaining walls were performed to analyze the phase and magnitude of dynamic earth pressure. The unit weight of walls, the amplitude of input acceleration and the base friction coefficient of walls were varied to analyze the influence of these factors on the dynamic earth pressure. Test results showed that the dynamic earth pressure was 180 degrees out of phase with the wall inertia force for the low sliding velocity of the wall, whereas small peaks of the dynamic earth pressure, which are in phase with the wall inertia force, were developed for the high sliding velocity of the wall. The amplitude of dynamic earth pressure was proportional to that of wall acceleration and the unit weight of the wall. In addition, the dynamic earth forces calculated by the Mononobe-Okabe method were the upper limit of the dynamic earth pressures.

• KIEAE Journal
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• v.10 no.5
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• pp.115-121
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• 2010

Lime was the solidifier mostly used at the fields of construction and civil works in the past. however, the development of Portland cement remarkably reduced the use of it. Recently as the concernment on circumstances gets higher, lime wined attention again as an eco-friendly material and was used at earth-using construction. This study examined the physical and chemical capacity of lime complexes with lime capacity improved, and performed fundamental study on the way to concretize by mixing it with earth. As a result, lime complex pressure strength was lower than cement pressure strength but it showed the possibility that its strength was improved by W/B control. The measurement of XRD after paste formation confirmed a compound generated by the reaction of Ca2+ion and Si, Al, and Fe from pozzolan reaction. A earth wall experiment by using lime complexes and earth showed that the higher, WB or the lower the quantity of unit combined materials, the lower the pressure strength was. The maximum pressure strength was maximum 11MPa when the quantity of unit combined materials was 450. It is because the composed earth particles had a high content of micro powder less than silt, so a lot of combination are demanded to secure fluidity. As a result of peptization experiment, after hardening, the material was not dissolved, which informed of the possibility of use as an outer subsidiary material. If the material is hardened by mold formation method, natural hardening crack appears. Cast expresses smart surface quality and enables to design for multiple purpose. The result shows the possibility of construction of low-story structures by using earth wall made of lime complexes and earth.

• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.39-46
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• 2010

The past studies on reinforced earth retaining wall have been mostly focused on the internal and external failure of reinforced earth retaining wall, and the research for external impact was limited on earthquake. However, the potential external impact such as vehicle collision to reinforced earth retaining wall near the road are increasing with development of roads. Therefore, in this study, the reinforced earth retaining wall was modeled by using LS-DYNA, which is a general purpose finite element program recognized for its reliability. The behavior of reinforced earth retaining wall by vehicle speed was analyzed with Ford single unit truck offered by NCAC (National Crash Analysis Center), which is 8 tons weight. In addition, in order to obtain stability of reinforced earth retaining wall for vehicle collision, the gravity retaining wall was applied at the bottom of reinforced earth retaining wall. With varying the height of retaining wall (0.5m, 1.0m, 1.5m), the numerical study was performed to analyze the stability and behavior of reinforced earth retaining wall.

• KIEAE Journal
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• v.11 no.4
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• pp.95-101
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• 2011

Earth has been used as a building material not only our country but also many foreign countries in the world. In foreign countries, we can often find the high-storied earthen houses which have been maintained for over several hundred years, which means the fact that earth differs in durability according to the methods of utilizing earth. So, the purpose of this study is to progress the fundamental research for utilizing earth as a wall material. Also, the another purpose of this study is to utilize the optimum micro-filler effect which adjusts the grain size of earth and the lime composite which promotes chemical combining power, and so examine whether earth material ensures its high compressive strength. This study applied both of rammed earth method and pour earth method among earth architecture methods. This study investigated compressive strength, slump, and air content according to unit binder weight. On the basis of such experimental results, this study derived the following conclusions. 1) Optimum micro-filler mixtures reduce a lot of fine particles contained in earth. If optimum micro-filler mixtures are used as aggregates, they develop lower W/B and relatively higher strength than general earth. 2) In this study, which uses optimum micro-filler earth mixtures and lime composite, rammed earth method develops 29MPa and pour earth method develops 28MPa in 28 days compressive strength. Such strengths can be utilized in building walls.

• Geomechanics and Engineering
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• v.8 no.4
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• pp.523-540
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• 2015

Based on limit equilibrium principles, this study presents a theoretical derivation of a new analytical formulation for estimating magnitude and lateral earth pressure distribution on a retaining wall subjected to seismic loads. The proposed solution accounts for failure wedge inclination, unit weight and friction angle of backfill soil, wall roughness, and horizontal and vertical seismic ground accelerations. The current analysis predicts a nonlinear lateral earth pressure variation along the wall with and without seismic loads. A parametric study is conducted to examine the influence of various parameters on lateral earth pressure distribution. Findings reveal that lateral earth pressure increases with the increase of horizontal ground acceleration while it decreases with the increase of vertical ground acceleration. Compared to classical theory, the position of resultant lateral earth force is located at a higher distance from wall base which in turn has a direct impact on wall stability and economy. A numerical example is presented to illustrate the computations of lateral earth pressure distribution based on the suggested analytical method.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.232-235
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• 2008

The mission of the EO(electro-optical) based low earth orbit satellite is provision of the high-resolution images required for GIS(Geographical Information Systems) establishment and the applications for environmental, agriculture and ocean monitoring. AEISS(Advanced Earth Imaging Sensor System) which is the main payload on the satellite consists of EOS(electro-optical subsystem) and PDTS(Payload Data Transmission Sub-system). IDHU(Image Data Handling Unit) which is one of the major unit in PDTS is capable of compression, storage, encryption and encoding. In this paper, the payload system of the EO based satellite is briefly introduced and the influence of the compression on AEISS is analyzed.

• Journal of the Korean earth science society
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• v.30 no.5
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• pp.588-597
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• 2009

Measurements of atmospheric $CO_2$ were made in the mountainous region of Srinagar-Garhwal, India (January to December 2006). Concentrations of $CO_2$ averaged $393\pm4.9$ ppm in 2006. Daily variations of $CO_2$ values showed minimum during the daytime (376.2 ppm) and peaked in the morning/evening (410.1 ppm). At monthly intervals, the $CO_2$ values varied from $367\pm11.14$ (May) to $425.2\pm13.54$ ppm (March). If divided on a seasonal basis, the values declined to minimum amounts in post-monsoon ($389.9\pm9.0$ ppm) and reached maximums during winter ($397.1\pm11.6$ ppm). Although phenology is significant in controlling $CO_2$ levels, short-term changes cannot be explained without the anthropogenic perturbations (e.g., vehicular pollution and forest fires). The $CO_2$ concentrations in Srinagar-Garhwal (393.4 ppm) were generally higher than those of other major monitoring locations around the world.

• Journal of the Korean Society of Earth Science Education
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• v.1 no.1
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• pp.85-98
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• 2008

Though the investigation of the suggested references proverbs related weather were collected and considered the probability of the usage on science instruction. The results are as follows. 130 proverbs related to weather were collected through the investigation of the suggested references. Most of weather proverbs are based on the states of sky, clouds, wind, precipitation, actions of animal, states of plants and the condition of people in daily life. they were classified according to weather types, natural phenomena and seasons. According to the results of analysing the students' recognition and interests on weather proverbs, most of students heard weather proverbs in their elementary school years firstly through their parents, books, and teachers. However they have only heard a few. Also many students also tend to think weather proverbs have a scientific base because weather proverbs have been told by many people through the ancient time and correspond to their personal experiences. Students responded that weather proverbs are useful for science learning on weather and can teach heritage and wisdom. After reading the suggested weather proverbs, their interests on weather proverbs were increased more than before reading. This is one of reasons why weather proverbs can be introduced to science classes. Weather proverbs were considered related to science curriculum. The third grade has a Unit "Fine days and Cloudy days", the fifth grade, "Unit of Weather Change", the Sixth grade, "Unit of Weather Forecast" , the Ninth grade, "Unit of Water cycle and Weather Change" and the tenth grade has "Unit of Earth". So the author consider that weather proverb materials can be used so effectively to bring about interest and motive in science learning.