• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.739-742
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• 2007

For the mass evaluation on the earth cutting volume, Geographic information system(GIS) based on digital topographical map executed on the ground condition in presents states and after installing utilities, and making visual decision. This study presents that the general reviews considering economical, technological efficiency as well as natural factors was carried. To the rational examines about plan and procedure of development was approved, the geographical analysis was performed that was based on the topographical shape before construction and the field states after construction, which will be utilized more useful data for mass curve calculation.

• Korean Journal of Remote Sensing
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• v.19 no.3
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• pp.255-261
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• 2003

Recently, the enormous increase in the volume of remotely sensed data is being acquired by an ever-growing number of earth observation satellites. The combining of diversely sourced imagery together is an important requirement in many applications such as data fusion, city modeling and object recognition. Aerial triangulation is a procedure to reconstruct object space from imagery. However, since the different kinds of imagery have their own sensor model, characteristics, and resolution, the previous approach in aerial triangulation (or georeferencing) is purformed on a sensor model separately. This study evaluated the advantages of aerial triangulation of large number of images from multi-sensors simultaneously. The incorporated multi-sensors are frame, push broom, and whisky broom cameras. The limits and problems of push-broom or whisky broom sensor models can be compensated by combined triangulation with other sensors The reconstructed object space from multi-sensor triangulation is more accurate than that from a single model. Experiments conducted in this study show the more accurately reconstructed object space from multi-sensor triangulation.

• Journal of the Korean Geophysical Society
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• v.7 no.4
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• pp.283-291
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• 2004

To find out the locus of the Quinling-Dabie-Sulu continental collision’s boundary and to estimate underground structure of the sedimentray basin in the Yellow Sea, three dimensional density modelling is carrid out by using gravity dataset (Free Air Anomaly), which is measured by Tamhae 2, KIGAM in a period between 2000 and 2002. The measured gravity anomaly in the investigations area is mainly responsed by depth and density differences between the sedimentary basin and the basement. The high density model-bodies extend mainly from the southern part of China to the middle-western part of the Korean Peninsula, which might be emplaced along the continental collision’s boundary. The total volume of the very low density model-bodies might be expected at about 20,000 km3 in the model area.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.4
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• pp.159-164
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• 2021

The Improvement of thermal performance using heat treatment of carbon nanotubes coated on the copper heat sink to take the radiation energy from solar ray for the energy harvesting in earth orbit. Using the additive coating of purified CNT for the increase of specific area and development of thermal conductive capacity, the performance of heat transfer is improved about 0.181 K/W while applying the power of 22 W under temperature of 3.98℃. Coating of purified CNT shows increase of area and volume of thermal layer however it led the partial thermal resistance.

• Atmosphere
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• v.29 no.2
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• pp.227-239
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• 2019

This paper reviews various bulk-type cloud microphysics parameterizations (BCMPs). BCMP, predicting the moments of size distribution of hydrometeors, parameterizes the grid-resolved cloud and precipitation processes in atmospheric models. The generalized gamma distribution is mainly applied to represent the hydrometeors size distribution in BCMPs. BCMP can be divided in three different methods such as single-moment, double-moment, and triple-moment approaches depending on the number of prognostic variables. Single-moment approach only predicts the hydrometeors mixing ratio. Double-moment approach predicts not only the hydrometeors mixing ratio but also the hydrometeors number concentration. Triple-moment approach predicts the dispersion parameter of hydrometeors size distribution through the prognostic reflectivity, together with the number concentrations and mixing ratios of hydrometeors. Triple-moment approach is the most time expensive method because it has the most number of prognostic variables. However, this approach can allow more flexibility in representing hydrometeors size distribution relative to single-moment and double-moment approaches. At the early stage of the development of BMCPs, warm rain processes were only included. Ice-phase categories such as cloud ice, snow, graupel, and hail were included in BCMPs with prescribed properties for densities and sedimentation velocities of ice-phase hydrometeors since 1980s. Recently, to avoid fixed properties for ice-phase hydrometeors and ad-hoc category conversion, the new approach was proposed in which rimed ice and deposition ice mixing ratios are predicted with total ice number concentration and volume.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.709-731
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• 2022

Loss of fracture resistance due to thermal aging degradation is a potential limiting factor affecting the long-term (80+ year) viability of nuclear reactors. To evaluate the effects of decades of aging in a practical time frame, accelerated aging must be employed prior to mechanical characterization. In this study, a variety of chemically and microstructurally diverse austenitic stainless steels were aged between 0 and 30,000 h at 290-400 ℃ to simulate 0-80+ years of operation. Over 600 static fracture tests were carried out between room temperature and 400 ℃. The results presented include selected J-R curves of each material as well as K_0.2mm fracture toughness values mapped against aging condition and ferrite content in order to display any trends related to those variables. Results regarding differences in processing, optimal ferrite content under light aging, and the relationship between test temperature and Mo content were observed. Overall, it was found that both the ferrite volume fraction and molybdenum content had significant effects on thermal degradation susceptibility. It was determined that materials with >25 vol% ferrite are unlikely to be viable for 80 years, particularly if they have high Mo contents (>2 wt%), while materials less than 15 vol% ferrite are viable regardless of Mo content.

• Geomechanics and Engineering
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• v.30 no.5
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• pp.461-469
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• 2022

One of the most important factors that should be considered for using any ground improvement technique is the stability of stabilized soil and the durability of the provided solution for getting the required engineering properties. Generally, most of the earth structures that are constructed on clayey soils are exposing movements due to the long periods of drying or wetting cycles. Over time, environmental changes may result in swells or settlements for these structures. In order to mitigate this problem, this research has been performed on mixtures of high plasticity clay with traditional additives such as lime, cement and non-traditional additives such as polypropylene fiber. The purpose of the research is to assess the most appropriate ground improvement technique by using commercially available additives for resisting the developed desiccation cracks during the drying process and resisting the volume changes that may result during wet/dry cycles as an attempt to simulate the changes of environmental conditions. The results show that the fiber-reinforced samples have the lowest volumetric deformation in comparision with cement and lime stabilized samples, and the optimum fiber content is identified as 0.38%. In addition, the desiccation cracks were not visible on the samples' surface for both unreinforced and chemically stabilized samples. Regarding cracks resistance resulting from the desiccation process, it is observed, that the resistance is connected with the fiber content and increases with the increase of the fiber inclusion, and the optimum content is between 1% and 1.5%.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1396-1403
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• 2009

The Ministry of Construction and Transportation (MOCT) has been constructing a nationwide soil information DB since 2000, as basic data for the construction of 'underground geographical information,' a project under the 2nd National Geo-spatial Information System (NGIS) master plan. The inputted soil information includes not only underground conditions such as the layer depth, type, color, and groundwater level, but also engineering information that can be applied to construction work design, such as on the standard penetration test and the compression test. It is difficult to use this information in soil analysis and design, however, because only the test results are currently available. A web-based geo-spatial information system was developed in this study to facilitate the effective application of the soil information database (DB). First, the space information, layer information, and engineering test information were loaded from the soil information DB in real time, and the earth volume, bearing capacity, and settlement were calculated to develop a web client that will evaluate the ground softness and liquefaction. It seems that the soil information DB can be actively applied to the planning and design of construction works using this system.

• International Journal of Contents
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• v.18 no.1
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• pp.76-84
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• 2022

Tidal power generation plays a critical role in reducing greenhouse gas emissions. It uses a tidal force generated by gravitational force between the moon, the earth, and the sun. The change of seawater height generates the tide-generating force, and the magnitude of the change is the tide level. The tide level change has the same period as the tide-generating force twice a day, every 29.5 days, every year, and every 18.6 years. Sihwa Lake Tidal Power Station is Korea's first tidal power plant that began commercial power generation in August 2011 and has been accumulating a large volume of data on electricity production, power generation sales, sluice displacement, and tide levels. The purpose of this paper was to analyze the impact of the inefficiency factors affecting production and the tidal level change on tidal power generation and their characteristics using Sihwa Lake Tidal Power's operational performance data. Throughout this paper we show that tidal power generating operation is accurately predicting the trends of magnitude of tidal force to be periodical for each day. determining the drop to initiate the water turbine generator factoring the constraints on the operation of Sihwa Lake, and reflecting the water discharge through the floodgate and water turbine during the standby mode in the power generation plan to be in the optimal condition until the initiation of the next power generation can maximize power generation.

• Journal of Astronomy and Space Sciences
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• v.40 no.4
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• pp.237-245
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• 2023

Laser communication has been considered as a novel method for earth observation satellites with generation of high data volume. It offers faster data transmission speeds compared to conventional radio frequency (RF) communication due to the short wavelength and narrow beam divergence. However, laser beams are refracted due to atmospheric turbulence between the ground and the satellite. Refracted laser beams, upon reaching the receiver, result in angle-of-arrival (AoA) fluctuation, inducing image dancing and wavefront distortion. These phenomena hinder signal acquisition and lead to signal loss in the course of laser communication. So, precise alignment between the transmitter and receiver is essential to guarantee effective and reliable laser communication, which is achieved by pointing, acquisition, and tracking (PAT) system. In this study, we simulate the effectiveness of tip/tilt compensation for more efficient laser communication in the satellite-ground downlink. By compensating for low-order terms using tip/tilt mirror, we verify the alleviation of AoA fluctuations under both weak and strong atmospheric turbulence conditions. And the performance of tip/tilt correction is analyzed in terms of the AoA fluctuation and collected power on the detector.