• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.943-948
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• 2022

Drones have been widely used in various fields due to the rapid development of done-related technologies, which causes various problems. The schemes which can track target drones by using signal transmitted by target drones have been investigated as a key technology for anti-drone systems to solve these problems. In this paper, we investigate an illegal drone tracking system based on swarming flight that consists of multiple small drones in order to resolve the limitations of a conventional system that consists of a single drone. In addition, we also propose a scheme with which we can adaptively adjust the separation distance between small drones in a swarm according to channel situations. We analyzed the performance of the proposed scheme in terms of success ratio and the number of movements. The proposed scheme can improve the success ratio and the number of movements by 170% and 63% respectively, compared to the conventional scheme.

• Journal of Astronomy and Space Sciences
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• v.39 no.2
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• pp.43-50
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• 2022

The unified scheme of Seyfert galaxies hypothesizes that the observed differences between the two categories of Seyfert galaxies, type 1 (Sy1) and type 2 (Sy2) are merely due to the difference in the orientation of the toroidal shape of the obscuring material in the active galactic nuclei. We used in this paper, a sample consisting of 120 Seyfert galaxies at 1.40 × 10⁹ Hz in radio, 2.52 × 10¹⁷ Hz in X-ray and 2.52 × 10²³ Hz in γ-ray luminosities observed by the Fermi Large Area Telescope (Fermi-LAT) in order to test the unified scheme of radio-quiet Seyfert galaxies. Our main results are as follows: (i) We found that the distributions of multiwave luminosities (L_radio, L_X-ray, and L_γ-ray) of Sy1 and Sy2 are completely overlapped with up to a factor of 4. The principal component analysis result reveals that Sy1 and Sy2 also occupy the same parameter spaces, which agrees with the notion that Sy1 and Sy2 are the same class objects. A Kolmogorov-Smirnov test performed on the sub-samples indicates that the null hypothesis (both are from the same population) cannot be rejected with chance probability p ~ 0 and separation distance K = 0.013. This result supports the fact that there is no statistical difference between the properties of Sy1 and Sy2 (ii) We found that the coefficient of the best-fit linear regression equation between the common properties of Sy1 and Sy2 is significant (r > 0.50) which plausibly implies that Sy1 and Sy2 are the same type of objects observed at different viewing angle.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1264-1264
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• 2001

The affect of surface temperatures of fruits on spectrum which measures actual sugar contents was observed. PLSR was applied to develop the sugar content evaluation system that was not affected by temperature. The reflected spectrum was used at the wavelengths of 654 and 1052nm with the separation distance of 2.5nm. To increase the conformance of a model using unknown samples, let the minimum value of PRESS be an optimum factor. 71 Shingo pears stored in a refrigerator were left in a room temperature for a while and these temperatures and reflected spectrums were measured. Reflected spectrums were measured at the wavelengths of 654 and 1052nm, 3 samples in one second. To measure these at different temperatures, the experiment was repeated hourly and four times. Starting temperatures of 2-3 were increased up to 17. The total number of measured spectrum was 284. To develop a sugar content evaluation system model using measured reflected spectrum, three groups of samples were considered. First group had 51 samples at 14 and second group had 141 samples with lower or higher temperatures than 14. Third group had 155 samples with well distributed temperatures. Other samples were used as validations to ensure the conformance. Measuring the sugar contents of samples with surface temperatures other than 14 were difficult with PLS model I, developed by using a sample temperature of 14. If the sugar contents were compensated using samples' temperatures, results of prediction would be close to the expected results and it would be one of the most important factors to develop this system. PLS models I and II could compensate the temperature but the precision would not come up to the standard. High precision was expected by using samples with wide ranges of temperatures and sugar contents. Both models showed the possibility of an improvement of a sugar content evaluation system disregarding the temperature. For practical use of a system, selecting samples should be done carefully to reduce the effect of the temperature.

• New & Renewable Energy
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• v.18 no.4
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• pp.38-53
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• 2022

T Recently, the government has been promoting the expansion and supply of renewable energy as an alternative for achieving carbon neutrality and the nationally determined contributions by 2030. In 2020, the Ministries of Industry and Environment and the Korea Forest Service collaborated to build a nationwide onshore wind energy siting atlas considering wind resources and forestry and environmental regulations focused on central regulations. In this study, the ordinances of the local governments were analyzed to examine the effects of regional location regulations on the expansion of onshore wind power energy generation facilities, in addition to those of central regulations. A development permit standard survey of 226 urban plan ordinances of the local governments nationwide showed that presently in 2022, 52 municipalities are applying regulations on wind energy generation facilities by ordinances. This is twice more than that in 2018, when renewable energy power generation facility development was difficult. Additionally, the location regulations applied by these ordinances were organized by items and regions, and regulatory characteristics, such as the number and scope, were analyzed by regions. To analyze the spatial distribution characteristics, JeollaNamdo was selected as the case area. A spatial DB was established for regulated areas based on the regional and central regulations, and the spatial distribution characteristics and the regulatory scope were compared and analyzed.

• Journal of Korean Society of Disaster and Security
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• v.16 no.1
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• pp.71-80
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• 2023

Fuel cells are low-carbon power sources that can expand distributed energy system and electric vehicle charging infrastructure when installing fuel cells in gas stations. In order to ensure safety for fuel cells in gas stations, quantitative risk assessments were conducted after deriving accident scenarios based on accident data of domestic and foreign gas stations and fuel cells. It calculates the expected extent of damage from fire and explosion that can occur in reality, not the worst accident scenario, and analyzes the damage impact. The separation distance of more than 9.0 m from a dispenser, 15.5 m from a car under refueling, 4.1 m from the ventilation pipe, 1.1 m from the gas adjustment device prevent the severe damage caused by the expected accident. This study result can be used to deploy fuel cells in gas stations and establish safety measures.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.425-434
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• 2023

To measure the wear amount of the TBM disk cutter in real time, it is important not only to automate the measurement using sensors, but also to stably transmit the measured data to the information processing system. In this study, we investigated the viability of utilizing Bluetooth Low Energy (BLE) technology to wirelessly transmit sensor data from the TBM cutter head to a receiver located at the chamber's rear. Through laboratory experiments, we analyzed the Received Signal Strength Index (RSSI) of the receiver considering various signal strength of the transmitter, separation distances between the transmitter and receiver and chamber fill materials. Our results demonstrate that wireless data transmission is feasible across all tested conditions when the transmitter signal strength is 0 dBm or higher.

• The Journal of the Acoustical Society of Korea
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• v.26 no.7
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• pp.353-360
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• 2007

Rapid urbanization and population increasing are making a high-rise residential building and high-density residential area. According to spacial concentration of population is occurred road traffic noise problem. Now we are popularly using almost only noise barrier installation, but it makes many disfunctions such as poor landscape, low noise barrier performance and crimes. The purpose of this research is to figure out which is best method one the traffic noise management. Alternative are composed to building layout type ($30^{\circ},\;90^{\circ},\;180^{\circ}$), separation between road and residential building, noise barrier types(noise barrier only, noise barrier and forests and etc). The noise barrier are shown to reduce barrier and building layout angle $30^{\circ}$ position is the best comparing with horizontal and vertical layouts. The gab distance is decreased approximately noise level 5dB(A). We figured out there are noise important method except noise barrier wall and it was analyzed how much decreased. This can be very useful before making a road planning and residential building design.

• Journal of Aquaculture
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• v.17 no.1
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• pp.69-80
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• 2004

The objective of the present study was to analyze genetic distances, variation and characteristics of individuals in rainbow trout, Oncorhynchus mykis using amplified fragment length polymorphism (AFLP) method as molecular genetic technique, to detect AFLP band patterns as genetic markers, and to compare the efficiency of agarosegel electrophoresis (AGE) and polyacrylamide gel electrophoresis (PAGE), respectively. Using 9 primer combinations, a total of 141 AFLP bands were produced, 108 bands (82.4%) of which were polymorphic in AGE. In PAGE, a total of 288 bands were detected, and 220 bands (76.4%) were polymorphic. The AFLP fingerprints of AGE were different from those of PAGE. Separation of the fragments with low molecular weight and genetic polymorphisms revealed a distinct pattern in the two gel systems. In the present study, the average bandsharing values of the individuals between two populations apart from the geographic sites in Kangwon-do ranged from 0.084 to 0.738 of AGE and PAGE. The bandsharing values between individuals No.9 and No. 10 showed the highest level within population, whereas the bandsharing values between individuals No.5 and No.7 showed the lowest level. As calculated by bandsharing analysis, an average of genetic difference (mean$\pm$SD) of individuals was approximately 0.590$\pm$0.125 in this population. In AGE, the single linkage dendrogram resulted from two primers (M11+H11 and M13+H11), indicating six genetic groupings composed of group 1 (No.9 and 10), group 2 (No. 1, 4, 5, 7, 10, 11, 16 and 17), group 3 (No. 2, 3, 6, 8, 12, 15 and 16), group 4 (No.9, 14 and 17), group 5 (No. 13, 19, 20 and 21) and group 6 (No. 23). In AGE, the genetic distances among individuals of between-population ranged from 0.108 to 0.392. In AGE, the shortest genetic distance (0.108) displaying significant molecular differences was between individuals No.9 and No. 10. Especially, the genetic distance between individuals No. 23 and the remnants among individuals within population was highest (0.392). Additionally, in the cluster analysis using the PAGE data, the single linkage dendrogram resulted from two primers (M12+H13 and M11+H13), indicating seven genetic groupings composed of group 1 (No. 15), group 2 (No. 14), group 3 (No. 11 and 12), group 4 (No.5, 6, 7, 8, 10 and 13), group 5 (No.1, 2, 3 and 4), group 6 (No.9) and group 7 (No. 16). By comparison with the individuals in PAGE, genetic distance between No. 10 and No. 7 showed the shortest value (0.071), also between No. 16 and No. 14 showed the highest value (0.242). As with the PAGE analysis, genetic differences were certainly apparent with 13 of 16 individuals showing greater than 80% AFLP-based similarity to their closest neighbor. The three individuals (No. 14, No. 15 and No. 16) of rainbow trout between two populations apart from the geographic sites in Kangwon-do formed distinct genetic distances as compared with other individuals. These results indicated that AFLP markers of this fish could be used as genetic information such as species identification, genetic relationship or analysis of genome structure, and selection aids for genetic improvement of economically important traits in fish species.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.855-867
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• 2018

When a weak zone exists ahead of tunnel face, the stress in the adjacent area would increase due to the longitudinal arching effect and the stability of the tunnel is affected. Therefore, it is critical to prepare a countermeasure through the investigation of the frontal weakness zone of the excavated face. Although there are several researches to predict the existence of weak zone ahead of tunnel face, such as geophysical exploration, numerical analysis and tunnel support, lack of studies on the relaxation zone depending on the width or distance from the vulnerable area. In this study, the impact of the weak zone on the formation of the relaxation zone was investigated. For this purpose, a series of laboratory test were carried out varying the width of the weak zone and the separation distance between tunnel face and weak zone. In the model test, sand with a water content of 3.8% was used to form a model ground. The model weak zone was constructed with dry sand curtains. The tunnel face was adjusted to allow a sequential excavation of upper and lower half part. load cells were installed on the bottom of the foundation and the tunnel face and measuring instruments for displacement were installed on the surface of the model ground to measure the vertical stress and surface displacements due to tunnel excavation respectively. The test results show that the width of weak zone did not affect the ground settlement while the ground subsidence drastically increased within 0.25D. The vertical stress and horizontal stress increased from 0.5D or less. In addition, the longitudinal arching effect is likely within the 1.0D zone ahead of the tunnel face, which may reduce the vertical stress in the ground following tunneling direction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2381-2391
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• 2013

In general, ground's thermal properties, types of heat exchanger, operational method, thermal interference between piles can be considered as key factors which affect the thermal performance of energy pile. This study focused on the effect of these factors on the performance by a numerical model reflecting a real ground condition. Depending on the degree of saturation of ground, pile's heat transfer rate showed a maximum difference of three times, and the thermal resistance of pile made a maximum difference of 8.7%. As for the type of heat exchanger effects on thermal performance, thermal efficiency of 3U type energy pile had a higher value than those of W and U types. The periodic operation (8 hours operation, 16 hours pause) can preserve about 20% of heat efficiency compared to continuous operation, and hence it has an advantage of preventing the thermal accumulation phenomenon. Thermal interference effect in group piles may vary depending on the ground condition because the extent decreases as the ground condition varies from saturated to dry. The optimal separation distance that maintains the decreasing rate of heat efficiency less than 1% was suggested as 3.2D in U type, 3.6D in W type, and 3.7D in 3U type in a general ground condition.