• Journal of the wind engineering institute of Korea
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• v.22 no.4
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• pp.163-169
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• 2018

In this study, wind loads exerted on the offshore wind turbine rotor in parked condition were predicted with variations of wind speeds, yaw angles, azimuth angle, pitch angles, and power of the atmospheric boundary layer profile. The calculated wind loads using blade element theorem were compared with those of estimated aerodynamic loads for the simplified blade shape. Wind loads for an NREL's 5 MW scaled offshore wind turbine rotor were also compared with those of NREL's FAST results for more verification. All of the 6-component wind loads including forces and moments along the three axis were represented on a non-rotating coordinate system fixed at the apex of rotor hub. The calculated wind loads are applicable for the dynamic analysis of the wind turbine system, or obtaining the over-turning moment at the foundation of support structure for wind turbine system.

• Journal of the Korean Geotechnical Society
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• v.37 no.6
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• pp.39-50
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• 2021

Recently, as the occurrence of earthquakes with a magnitude of 5.0 or higher in Korea increases, many studies and interests in seismic design are increasing. A lot of damage was caused by the Pohang earthquake in 2017, and port facilities such as a breakwater were also damaged. This study analyzed the dynamic behavior of the upright breakwater, an external facility, based on a centrifugal model experiment. A series of centrifugal model test was conducted by three different seismic waves such as Pohang Earthquake Wave, Artificial Wave I, and II. As a result, the dynamic behavior of upright breakwater was analyzed. The review showed that acceleration amplification tends to be suppressed as breakwater foundation ground increases support and stiffness through DCM reinforcement and riprap replacement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.5
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• pp.701-708
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• 2021

In this paper, I investigate the performances of the discovery and the message transmission of the DDS (Data Distribution Service) included the security function. The DDS serves the communication protocol, a publication- subscription method, for the real-time communication in the distributed system. The publication-subscription method is used in the various area in terms of defence, traffic and medical due to the strength such as a performance, scailability and availability. Nowadays, many communication standard has included and re-defined the security function to prepare from dramatically increased a threat of the security, the DDS also publishes the standard included the security function. But it had been not researched that the effect of increased a overhead for legacy systems due to the using of the security DDS function. The experimental results show that the comparative performance of legacy DDS and security DDS in terms of the discovery and the message transmission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.208-213
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• 2021

The use of computers has increased greatly, and services have been developed very much for the convenience of users. As the use of computers increases, human activity has declined, and symptoms of deterioration in health are increasing. As the time to sit and live increased, humans are more exposed to diseases of low back pain, and low back pain includes pain related to the lower back centering on the herniated disc. Most of the back pain is caused by abnormalities in the muscles and ligaments that support the spine and trunk. In this paper, we present an overall design for developing an app that can obtain lumbar exercise effects to reduce low back pain or help treatment. In order to use this effectively, we propose a plan to obtain lumbar exercise effect, and aim to present an app design that can help effectively treat low back pain by using graphic-based guidance points.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.35-41
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• 2008

Stone columns, one of the soft ground improvement techniques, are being used for not only accelerating consolidation but also increasing bearing capacity of soft grounds. In this study, in order to observe the stress distribution characteristics which are one of the important factors to estimate the settlement reduction of the soft ground, lab-scale experiments were performed in stone column reinforced clay ground. The stress distribution ratio of stone column decreased with the lapse of time after surcharge loading but increased as the stiffness of clay deposit increases. It shows that the modified Baumann and Bauer's solution, which is able to easily predict the stress distribution ratio of stone column reinforced soft ground, exhibits reasonable agreement with the measured data.

• Composites Research
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• v.19 no.6
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• pp.8-15
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• 2006

In this study, computational rotor dynamic analyses of a composite roller used for large LCD panel manufacturing process have been conducted. The present computational method is based on the general finite element method with rotating gyroscopic effects of rotor systems. General purpose commercial finite element code, SAMCEF which has special rotordynamics analysis module is applied. For the purpose of numerical verification, comparison study for a benchmark dual rotor model with support bearings is also presented. Detailed finite element models for composite roller with optimized lamination angles are constructed and analyzed considering gravity effect in order to investigate vibration characteristics in actual operation environment. As results of the present study, rotor stability diagrams and mass unbalance responses are presented for different rotating conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.121-128
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• 2009

The King George Island, where the King Sejong Station is located, represents one of the gateways to the Antarctica from the point of its geographical aspect. It also serves as an advanced post, and plays an important role in the extending for Korea's Antarctic research activities. The existence of maps is not only a basic element for the constructing geographic informations supporting these activities, but also an implied way of announcing the sovereignty over the KingSejong Station in global world. However, the precise surveying for the geographic information has not been carried out, and thus topographical maps as well as geographic information assuring enough accuracy are still missed in this area. This fact had forced Korea to rely on using maps produced by foreign countries. Therefore, this study aims to generate digital topographical maps of 1: 5,000 scale for the constructing geographic information using lightweight aerial photogrammetry system first. And further, it will contribute to offer practical base data for the future research related to the Antarctic environment through the analysis of glacier retreat and change using this new digital map comparing with existing one.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1C
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• pp.21-31
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• 2009

Based on the proven feasibility of bottom ash and tire shred-soil mixtures as lightweight fill materials, tire shred-bottom ash mixtures were suggested as a new lightweight fill material to replace the conventional construction material (soil) with bottom ash. Therefore, we carried out the field compaction test and performance test of large scale embankment in order to evaluate their suitability for the use of lightweight fill materials. In these tests, we could assess the settlement, earth pressure, stress-strain relation, vibration of large scale embankment which were made with tire shred-bottom ash mixture and the conventional fill material(weathered soil) respectively. The earthpressure and vibration transmission was decreased and the settlement behaviour of the 2 materials (tire shred mixture and weathered soil) was measured similarly under static/cyclic loading condition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.3
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• pp.92-97
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• 2024

To improve the efficiency of water splitting systems for hydrogen production, the high overvoltages of electrochemical reactions caused by catalysts in the oxygen evolution reaction (OER, Oxygen Evolution Reaction) must be reduced. Among them, LDH (Layered Double Hydroxide) compounds containing transition metal such as Ni, are attracting attention as catalyst materials that can replace precious metals such as platinum that are currently used. In this study, nickel foam, an inexpensive metallic porous material, was used as a support, and NiCo LDH (Layered Double Hydroxide) nanocrystals were synthesized through a hydrothermal synthesis process. In addition, changes in the shape, crystal structure, and water decomposition characteristics of the Mo-doped NiCo LDH nanocrystal samples synthesized by doping Mo to improve OER properties were observed.

• Korean journal of applied entomology
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• v.63 no.1
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• pp.77-80
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• 2024

Aedes albopictus, a common species in the Republic of Korea, is internationally known as a major vector for various diseases, and it is well-adapted to urban environments. Recent insect outbreaks in urban areas, attributed to climate change and urban heat islands, have increased the necessity of researching the effects on mosquito populations. This study analyzed climate data from 25 Automatic Weather System (AWS) stations in Seoul, identifying urban areas with pronounced heat island effects and suburban areas with milder effects. Nine urban heat island conditions were established based on this analysis, under which the hatching rates of Ae. albopictus were examined. The results revealed an increase in hatching rates correlating with the intensity of the urban heat island effect. Regression analysis further indicated that this trend accelerates as the strength of the heat island effect increases. This study suggests that temperature variations resulting from urban heat island phenomena can significantly influence the hatching rates of Ae. albopictus.