• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.578-589
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• 2019

The drones, developed for military use, have recently expanded a wide range of areas of use, including agriculture, industry, broadcasting utility, police, fire fighting and leisure. Drone, combined with IT technology, is further expanding its utilization and emerging as a key part of the fourth industry. Purpose: This study designs and implements drones that can be utilized in disaster prevention areas such as disaster prevention, preparedness and response. Method: This study was conducted by examining hardware drone specifications and developing a program suitable for the purpose of research based on the literature review. Result: In this study, we developed a drone that can be controlled remotely, investigated program plans for drone remote control, and developed a program that enables remote control broadcasting from drones. Conclusion: The drone could be used in the disaster area based on functions such as remote control and remote broadcasting.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.723-724
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• 2017

Recently, researches are being conducted to build a smart environment using various sensors and devices and to provide customized services to users through inter object communication. However, the existing system utilizes a centralized method of transmitting measured sensor data in real time to the server and processing it in batches and As the system is expanded, there is a problem that a high-end server must be configured. In this paper, we design a Resource Allocation Algorithm for IoT distributed processing environment to solve these problems. The resources required for the device to operate are transferred to the server and the server allocates resources in comparison to the task in progress. Therefore, it is expected that the data throughput of the server will be reduced and various devices can be configured in a server having a low specification.

• Journal of Korea Water Resources Association
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• v.31 no.3
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• pp.337-345
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• 1998

DAMBRK-U model is developed for the evaluation of overtopping risk of dam and levee and for the estimation of uncertainty in floodwave simulation. The original algorithm is revised and expanded to include Monte-Carlo analysis to estimate them. The model is tested by applying to hypothetical channels of widening, uniform and narrowing geometry. Larger variation in discharge and water depth are expected at narrower sections of a river. It is calibrated by applying to the Hantan River, where severe damages from Yunchun dam-break and levee overtopping occurred on July, 1996. Overtopping risk of dam is calculated for various discharge conditions for Yunchun-dam, and that of levee is also calculated by comparing levee height with flood level at Hantan recreation area. Simulation results show that the overflow depth of flood level is 1,266~0.782 m and the overflow risk turns out to be 100%.

• Korean Journal of Acupuncture
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• v.26 no.4
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• pp.53-66
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• 2009

Objective : Acupuncture has been widely used throughout the world for the treatment of knee osteoarthritis (knee OA). This study investigated whether acupuncture, particularly Sa-am acupuncture, could be effective in relieving pain and improving the symptoms of knee OA. Method : This study was conducted as a prospective, randomized, controlled, and patient- and investigator-blinded clinical trial. Forty volunteers with knee OA participated in the study. All participants were screened through an inclusion and exclusion criteria. Thirty four participants completed the clinical trial. In total, forty subjects were randomly selected to receive Sa-am acupuncture. Eight sessions of acupuncture were given at the contralateral side of the problematic knee for 4 weeks. Korean translation of Western Ontario and McMaster Universities Osteoarthritis Index (KWOMAC) scores were measured twice: at the beginning and end of the clinical trial period. Both the Patient Global Assessment and physical health scores based on the 36-Item Short-Form Health Survey were also used to measure the results. Results : Compared to the pre-trial scores, the Sa-am acupuncture group (n=34) showed a significant decrease in KWOMAC total scores according to a paired t-test. The Sa-am acupuncture group also showed significant improvement in the Patient Global Assessment when compared to the pre-trial. Conclusions : Sa-am acupuncture for knee OA resulted in an improved KWOMAC total score. This was mostly driven by the function component score that was greatly affected by acupuncture. However, further studies with expanded designs are needed to solidify this finding with scientific rigor.

• Geomechanics and Engineering
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• v.22 no.5
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• pp.385-396
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• 2020

A uniaxial compression test was performed to analyse the mechanical properties and macroscale and mesoscale failure mechanisms of sandstone with pyrite concretions. The effect of the pyrite concretions on the evolution of macroscale cracks in the sandstone was further investigated through numerical simulations with Particle Flow Code in 2D (PFC2D). The results revealed that pyrite concretions substantially influence the mechanical properties and macroscale and mesoscale failure characteristics of sandstone. During the initial loading stage, significant stress concentrations occurred around the edges of the pyrite concretion accompanied by the preferential generation of cracks. Meanwhile, the events and cumulative energy counts of the acoustic emission (AE) signal increased rapidly because of friction sliding between the concretion and sandstone matrix. As the axial stress increased, the degree of the stress concentration remained relatively unchanged around the edges of the concretions. The cracks continued growing rapidly around the edges of the concretions and gradually expanded toward the centre of the sample. During this stage, the AE events and cumulative energy counts increased quite slowly. As the axial stress approached the peak strength of the sandstone, the cracks that developed around the edges of the concretion started to merge with cracks that propagated at the top-left and bottom-right corners of the sample. This crack evolution ultimately resulted in the shear failure of the sandstone sample around the edges of the pyrite concretions.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.471-474
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• 2006

Environment-friendly shock-absorbing materials were made of wastepaper such as old corrugated containers (OCC) and old newspapers (ONP) with a vacuum forming method. The plate-like cushioning materials made of OCC and ONP respectively by vacuum forming showed superior shock-absorbing properties with lower elastic moduli compared to expanded polystyrene (EPS) and pulp mold. Even though the plate-like materials had many free voids in their fiber structure, their apparent densities (${\approx}0.1g/cm^{3}$) were a little higher than that of EPS (${\approx}0.03g/cm^{3}$) and much lower than that of pulp mold (${\approx}0.3g/cm^{3}$). However, the elastic moduli of the cushioning materials made of wastepaper were much lower than that of EPS or pulp mold. This finding implies that the cushioning materials made of OCC fibers containing more lignin than ONP show better shock-absorbing properties than ONP Moreover, the cushioning materials made of OCC and ONP respectively showed greater porosity than pulp mold. The addition of cationic starch to the cushioning materials contributed to an increase in the elastic modulus to the same level as that of EPS. Furthermore, the deterioration in fiber quality by repeated use of wastepaper played a great role in improving shock-absorbing ability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.592-599
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• 2007

The advancement of wireless technology improves the electronic learning by combining with the mobile function, and promotes the expanded transition to the mobile learning. Basically, the mobile learning provides the usefulness in terms of tile and space to provide learners with the access to the educational contents. However, the small display device and limited memory space of mobile device is limiting the access to the learning contents simply to the text-based transmission. This paper designed and implemented the multimedia mobile learning system that reduces the size of parser by define into MSMIL composed only of needed tag to multimedia contents production in the mobile devices by using the SMIL that supports the multimedia object synchronization reduces the data of multimedia learning data and enhances the transmission efficiency by applying the macro method in creating the contents of learning. The results of implementation indicates that it simplifies the designing language, makes the language learning easy, and saves the CPU resources for the parsing by reducing the size of parser.

• Journal of Radiation Industry
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• v.7 no.1
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• pp.45-49
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• 2013

In tissue engineering application, a fibrous structure of scaffolds has been issued as an alternative system to regulate cell survival and tissue regeneration, and electrospinning technique has been popularly used to generate fibrous meshes or sheets mimicking the structure of native extracellular matrix (ECM). However, recent strategy in the scaffold development is expanded to provide the structural property as well as a biological property of native ECM, a variety of surface modification techniques have been used to introduce biological property. In this study, we developed biomimetic poly(L-lactide-co-${\varepsilon}$-caprolactone) (PLCL) nano- and micro-fibrous scaffolds as a unique platform with structural and biological properties with native ECM using electrospinning method and gamma-ray irradiation. Surface morphology of the scaffolds was observed by scanning electron microscopy, and alteration of surface property was evaluated with toluidine blue O staining, water contact angle measurement and ATR-FTIR analysis.

• Korean Journal of Remote Sensing
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• v.25 no.2
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• pp.175-184
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• 2009

This study attempts to analyze the difference among the variations of ecological distribution in Gobi desert and Manchuria through satellite based land cover classification. This was motivated by two well-known facts: 1) Gobi desert, which is an old source region, had been gradually expanded eastward; 2) Manchuria, which is located in east of Gobi desert, was observed as a new source region of yellow dust. An unsupervised classification called ISODATA clustering method was employed to detect the land cover change and to characterize the status of desertification and its expanding trends using NDVI (Normalized Difference Vegetation Index) derived from VEGETATION sensor onboard the SPOT satellite for 1999 and 2007. We analyzed NDVI annual variation pattern for every classes and divide into 5 level according to their vegetation's density level based on NDVI. As results, Gobi desert is showed positive variation: a decrease $78,066km^2$ in central Gobi desert and out skirts of Gobi desert (level-0) but Manchuria area is worse than previous time: an increase $25,744km^2$.

• Transactions of Materials Processing
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• v.30 no.6
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• pp.291-300
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• 2021

Currently, starting with electric vehicles, the application of ultra-high-strength steel sheets and light metals has expanded to improve mileage by reducing vehicle weight. At a time when internal combustion engine vehicles are rapidly changing to electric vehicles, the application of ultra-high-strength steel is expanding to satisfy both weight reductions and the performance safety of the chassis parts. There is an urgent need to improve the quality of parts without defects. It is particularly difficult to estimate the part formability through the finite element method (FEM) in the burring operation, so product design has been based on the hole expansion ratio (HER) and experience. In this study, design of experiment (DOE), analysis of variance (ANOVA), and regression analysis were combined to optimize the formability by adjusting the process variables affecting the burring formability of ultra-high-strength steel parts. The optimal variables were derived by analyzing the influence of variables and the correlation between the variables through FE analysis. Finally, the optimized process parameters were verified by comparing experiment with simulation. As for the main influence of each process variable, the initial hole diameter of the piercing process and the shape height of the preforming process had the greatest effects on burring formability, while the effect of a lower round of punching in the burring process was the least. Moreover, as the diameter of the initial hole increased, the thickness reduction rate in the burring part decreased, and the final burring height increased as the shape height during preforming increased.