• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.482-484
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• 2015

대표적인 위치기반 기술인 GPS는 건물 내부와 같이 실내에서의 위치추정이 거의 불가능하다. 따라서 실내 측위의 방안으로 BlueTooth 4.0LE 기반의 장치인 비콘(Beacon)을 활용하여 실내 GPS의 역할을 수행하도록 하는 기법이 활용되고 있다. 그러나, 비콘의 거리측정에 사용되는 RSSI의 문제점으로 인해, 위치추정의 정확도가 급격히 저하되는 문제점을 가지고 있다. 본 논문에서는 개선된 위치선정 알고리즘을 통하여 오차율을 줄여, 정밀한 위치 추정이 가능한 알고리즘을 제안하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.3
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• pp.301-308
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• 2001

Nowadays GPS play a important roles in the navigation system of vehicles, but, it doesn't determine the kinematic positions of vehicles accurately because of few satellites in the urban canyon covered with trees and high buildings. So GLONASS (GLObal Navigation Satellites System), the Russian satellites'system, operated in 1996, was introduced to overcome this drawbacks. Therefore, this study deals with the kinematic positioning of vehicles with Real-time code differential positioning methods. As a result, Real-time DGPS/GLONASS is better than Real-time DGPS in the differential corrected positions and HDOP (Horizontal Dilution of Precision). And it was shown that the combined GPS/GLONASS contributes to the precise kinematic positioning of vehicles.

• Tunnel and Underground Space
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• v.26 no.4
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• pp.274-282
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• 2016

Natural ventilation is employed in limestone mines that have been currently operated in Korea, and there has been a growing issue of a significantly weak airflow caused by the large-scale excavation. Thus, the air quality in the working area is considerably poor. In order to improve this circumstance, it is mainly required to examine ventilation performance. In this study, the examination of ventilation efficiency was conducted by using tracer gas method. The result of this work indicated detailedly the ventilation problems in research mine, in that extremely low air velocity, recirculation, and air change rate were evaluated quantitatively using tracer gas. Therefore the ventilation performance evaluation using tracer gas can be opted as a precise method to improve the working area in mines.

• Smart Media Journal
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• v.10 no.4
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• pp.45-54
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• 2021

The skin is the body's first line of defense against external infection. When a skin disease strikes, the skin's protective role is compromised, necessitating quick diagnosis and treatment. Recently, as artificial intelligence has advanced, research for technical applications has been done in a variety of sectors, including dermatology, to reduce the rate of misdiagnosis and obtain quick treatment using artificial intelligence. Although previous studies have diagnosed skin diseases with low incidence, this paper proposes a method to classify common illnesses such as warts and corns using a convolutional neural network. The data set used consists of 3 classes and 2,515 images, but there is a problem of lack of training data and class imbalance. We analyzed the performance using a deep metric loss function and a cross-entropy loss function to train the model. When comparing that in terms of accuracy, recall, F1 score, and accuracy, the former performed better.

• Journal of Life Science
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• v.13 no.4
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• pp.428-432
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• 2003

This study was carried out to develop and investigate integrated mechanization system for culture of carrot. Compared with the conventional hand planting, use of a mechanical planter for pelleted seeds resulted in a saving of planting time by 225 hours. An additional saving of 460 hours was obtained for thinning the seedlings. Besides seeds could be saved by 72%, planting and thinning be done only in 35 hours per ha field when the pelleted seeds were planted with a planter. Work hour reduced by adopting the mechanical planting of pelleted seeds sharply contrasted to that of 720 hours required for hand-planting the thinning hours, resulting in a reduction of labor by more than 95%. SMP followed pelleting tended not only to increase the percentage of seedling emergence in the field but to induce an a day earlier germination.

• Korean Journal of Optics and Photonics
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• v.28 no.4
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• pp.153-157
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• 2017

An infrared camera and laser common-path optical system is applied to DIRCM (directional infrared countermeasures), to increase boresighting accuracy and decrease weight. Thermal effects of a laser beam in a common-path optical system are analyzed and evaluated, to predict any degradation in image quality. A laser beam with high energy density is absorbed by and heats the optical components, and then the surface temperature of the optical components increases. The heated optical components of the common-path optical system decrease system transmittance, which can degrade image quality. For analysis, the assumed simulation condition is that the laser is incident for 10 seconds on the mirror (aluminum, silica glass, silicon) and lens (sapphire, zinc selenide, silicon, germanium) materials, and the surface temperature distribution of each material is calculated. The wavelength of the laser beam is $4{\mu}m$ and its output power is 3 W. According to the results of the calculations, the surface temperature of silica glass for the mirror material and sapphire for the lens material is higher than for other materials; the main reason for the temperature increase is the absorption coefficient and thermal conductivity of the material. Consequently, materials for the optical components with high thermal conductivity and low absorption coefficient can reduce the image-quality degradation due to laser-beam thermal effects in an infrared camera and laser common-path optical system.

• Explosives and Blasting
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• v.40 no.2
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• pp.25-34
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• 2022

Recently, there has been an increasing number of cases of improving constructability by using electronic detonators with precise delay time in tunnel blasting sites. This case is a case of conducting test blasting using with non-electric detonator and electronic detonator at the site of 『Seoul Metropolitan Area Express Railroad Route A Private Investment Project Section 00』 that requires careful management of vibration and noise. Although this site was designed with a non-electric detonator, it was attempted to improve the advance rate and control vibration and noise by mixing the non-electric detonator and the electronic detonator due to the decrease in the advance rate. As a result of the blasting, the target value was achieved with an advance rate of about 85% and a maximum measured value of vibration and noise is 0.215cm/sec and 73.22dB(A) which were measured below regulatory standards. As blasting works in downtown areas, it is necessary to designate measurement and management objects to continuously manage vibration and noise.

• Journal of Yeungnam Medical Science
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• v.4 no.1
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• pp.75-80
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• 1987

The positive rate for serum anti-HBs was analized among 424 of HB vaccinated and 2035 of non-vaccinated cases at the Yeungnam University Hospital, Computed Automated Med-screening Center. Most of them from Kyungbook province and they had the last HB vaccination in the periods of 3 to 42months prior to this study. The followings were obtained. 1. The positive rates for serum HBsAg were 0.7% in the vaccinees, 9.6% in the non-vaccinated and 8.0% in the whole cases. 2. The positive rates for serum anti-HBs were 66.3% in the vaccinees, 47.9% in the non-vaccinated and 51.0% in the whole cases. 3. The positive rates for serum anti-HBs were 51.4% in the cases with one time of vaccination and 68.6% in the cases with two times of vaccination. on the vasis of these findings the positive rate for serum anti-HBs among the vaccinees was significantly higher than thau of non-vaccinated(P<0.05). The positive rate for seaum anti-HBs shortly after vaccination was higher than that of present our study which was made relatively long period after vaccination. As the reason a natural decrease of the titers of the serum anti-HBs can be postulated as one of the contributing factors for the discrepancy. In order to keep the serum antibody of perfect protectivity against HBV, it may be better to check the serum anti-HBs just after vaccination, follow up and take booster injection when it is needed.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.12
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• pp.445-452
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• 2022

Class distribution of unbalanced data is an important part of the digital world and is a significant part of cybersecurity. Abnormal activity of unbalanced data should be found and problems solved. Although a system capable of tracking patterns in all transactions is needed, machine learning with disproportionate data, which typically has abnormal patterns, can ignore and degrade performance for minority layers, and predictive models can be inaccurately biased. In this paper, we predict target variables and improve accuracy by combining estimates using Synthetic Minority Oversampling Technique (SMOTE) and Light GBM algorithms as an approach to address unbalanced datasets. Experimental results were compared with logistic regression, decision tree, KNN, Random Forest, and XGBoost algorithms. The performance was similar in accuracy and reproduction rate, but in precision, two algorithms performed at Random Forest 80.76% and Light GBM 97.16%, and in F1-score, Random Forest 84.67% and Light GBM 91.96%. As a result of this experiment, it was confirmed that Light GBM's performance was similar without deviation or improved by up to 16% compared to five algorithms.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.609-616
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• 2017

National Geographic Information Institute has established a plan that preoccupies UCPs (Unified Control Points) at 2~3km intervals in urban areas by considering the distance between existing UCPs by satellite images and aerial photographs in 2015. In this study, we discussed the method of selecting the locations of optimal UCPs by simulating GPS reception environment in candidate sites for UCPs using GIS. For this purpose, we selected new candidate sites for installing UCPs using satellite images and aerial photographs, and analyzed the GPS reception environment by calculating the visibility distance from buildings around UCPs using GIS skyline analysis. The number of and the arrangement of visible satellites that are capable of GPS satellite reception from the viewpoint of sky view were showed by GIS skyline analysis. Quality evaluation results of GPS observation data were compared with average PDOP calculated from hourly PDOP and TEQC in two points of Sungkyunkwan University during 8 hours. As a result of GPS reception environment using GIS, if the PDOP increases, the data acquisition rate is lowed, and the multipath error and the cycle slip are increased. Thus, this study verified that the quality of GPS observation data can be secured by constructing three-dimensional spatial information and simulating PDOP when preoccupying multiple UCPs using GIS.