• Journal of Multimedia Information System
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• v.6 no.2
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• pp.107-118
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• 2019

This paper deals with actual optical data from rural as well as urban areas in a nationwide study captured with Fisheye cameras. Simultaneously data was collected (of the receiving power density) from the mobile communications satellite N-STAR. The visibility of the satellite is easily determined by checking the value of the pixels in the binarized fisheye image of its position. The process of determining the visible satellite is automatically performed. Based on the analyses of the field data measured in Japan, we are expecting HEOs (Highly inclined Elliptical Orbiters) that would reduce blockage in the extreme northern region of Wakkanai City well as in the most crowded urban area, in Tokyo Ginza. In case of HEOs operation, the elevation angle will improve from 37 with N-STAR GEO to 75 degrees. HEOs could replace 5G/Ka-band or support in rural areas where broadband circuit is not available. We are proposing combination operations with HEOs and 5G/Ka-band to solve blockage problems, because HEOs can keep line-of-sight propagation with high elevation angle for long duration. In such operations, the communications profile on the vehicle based on actual optical data will be very useful to predict blockages and to select/switch a suitable circuit.

• Current Optics and Photonics
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• v.6 no.2
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• pp.151-160
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• 2022

Fundus images can reflect ocular diseases and systemic diseases such as glaucoma, diabetes mellitus, and hypertension. Thus, research on fundus-detection equipment is of great importance. The fundus camera has been widely used as a kind of noninvasive detection equipment. Most existing devices can only obtain two-dimensional (2D) retinal-image information, yet the fundus of the human eye also has spectral characteristics. The fundus has many pigments, and their different distributions in the eye lead to dissimilar tissue penetration for light waves, which can reflect the corresponding fundus structure. To obtain more abundant information and improve the detection level of equipment, a snapshot nonmydriatic fundus imaging spectral system, including fundus-imaging spectrometer and illumination system, is studied in this paper. The system uses a microlens array to realize snapshot technology; information can be obtained from only a single exposure. The system does not need to dilate the pupil. Hence, the operation is simple, which reduces its influence on the detected object. The system works in the visible and near-infrared bands (550-800 nm), with a volume less than 400 mm × 120 mm × 75 mm and a spectral resolution better than 6 nm.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.6
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• pp.591-601
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• 2021

Recently, infrared object detection(IOD) has been extensively studied due to the rapid growth of deep neural networks(DNN). Adversarial attacks using imperceptible perturbation can dramatically deteriorate the performance of DNN. However, most adversarial attack works are focused on visible image recognition(VIR), and there are few methods for IOD. We propose deep learning-based adversarial attacks for IOD by expanding several state-of-the-art adversarial attacks for VIR. We effectively validate our claim through comprehensive experiments on two challenging IOD datasets, including FLIR and MSOD.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.565-572
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• 2022

The white plume from the cooling tower can be generated by mixing between discharging hot and humid air and cold air outside. This causes various problems such as icing, traffic disturbances, and fire factors in the vicinity, moreover it can also damage the image of a company. Various methods can be used to prevent white plume, one of them is to install a heat exchanger at the outlet of the cooling tower so that the heat exchanger transfers as much heat as possible to lower the temperature. Therefore the air flow path in the cooling tower should be optimized. Installation of the filler can be used to make the air flow better, thus we investigate the effect of filler on the air flow using CFD method. The pressure and velocity profile in the cooling tower could be acquired by the calculations. The filler made the velocity of the air entering the heat exchanger uniform this was because high flow resistance of the filler suppresses the generation of eddy in the cooling tower. But the total air pressure drop increased about 2 times with filler because the pressure drop by the filler accounted for about 60% of the total pressure drop.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.3
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• pp.51-57
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• 2010

Steganography techniques can be used to hide data within digital images with little or no visible change in the perceived appearance of the image. I propose a steganalysis to detecting hidden message in sequential steganography. This paper presents adjusted technique for detecting abrupt jumps in the statistics of the stego signal during steganalysis. The repeated statistical test based on CUSUM-SPRT runs constantly until it reaches decision. In this paper, I deal with a new and improved statistic $g_t$ by computing $S^{t^*}_j$.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.5
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• pp.507-518
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• 2022

This study aimed to measure the monetary and non-monetary effects on brand awareness at hypermarkets in Riyadh. The independent variable consists of three sub-variables: price reductions, free samples, and purchasing vouchers. The research population has all Saudi and non-Saudi buyers in Riyadh. The figures show that the population size reached 3.87 million in 2019. The proportional stratification sampling technique and the recommended sample size were 387 buyers. The five-point Likert scale with the fully structured questionnaire was used. The study concldes the effect of free samples on brand awareness while there was no effect of monetary instruments. The results show that the three sales promotion incentives (price reduction, free samples, and purchasing vouchers) moderately affected brand awareness and a key role in explaining consumer behavior, so the significant impact was proved. In summary, this study showed that price reductions have the power of creating the perception of buyers at hypermarkets in Riyadh. Non-cash instruments were more effective than cash instruments in enhancing brand awareness at the hypermarkets in the Saudi market. So, the price reductions and purchasing vouchers have less power in conducting communication-based awareness. Building awareness and improving brand image through free samples were most visible in communication strategy.

• Journal of People, Plants, and Environment
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• v.22 no.3
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• pp.233-239
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• 2019

This study was conducted in order to predict the vase life of cut lily 'Woori Tower' flowers using a non-destructive thermal imaging technique. It was found that the temperature of cut lily flowers was maintained at 20℃ and was slightly lower than the air temperature until they bloomed. On the 11th day, when flowers bloomed, the temperature of leaves and flowers was measured to be 18.75±0.38℃ and 19.23±0.32℃ respectively, and their difference with ambient temperature was over 3℃. The flower temperature increased slightly when the vase life of cut lily flowers ended, and the temperature difference between the air and leaf temperature (1.77℃) and between the air and flower temperature (1.39℃) got smaller. No visible aging symptom was observed, but it was found that the temperature had risen due to water losses and less functional stomata. The vase life of cut lily flowers can be predicted based on changes in temperature and it will be also possible to predict the potential quality and vase life of cut flowers before harvesting them in greenhouses.

• Applied Chemistry
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• v.15 no.1
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• pp.21-24
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• 2011

A sensitive silver nanoparticles (Ag NPs) enhanced chemiluminescence (CL) method is reported for the determination of mandelic acid (MA). This method is based on the luminol-KIO₄ system catalyzed by Ag NPs to produce CL spectra. Prepared Ag NPs were characterized by UV-visible spectra and TEM image. Under optimal condition, CL spectra of the system were responded linearly with the concentration of MA in the range of 2.5×10^-9 to 2.0×10^-8 mol L^-1 (r=0.9989) with a detection limit of 1.2×10^-10 mol L^-1. The relative standard deviation of 1.0×10^-7 mol L^-1 MA was found 1.45 (n=9).

• Current Optics and Photonics
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• v.8 no.1
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• pp.97-104
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• 2024

In aerial cameras, image quality is easily affected by weather, temperature, and the attitude of the aircraft. Aiming at this phenomenon, based on the theory of two-step zoom optical systems, a dual-band optical-despun two-step zoom optical system is designed. The system has a small field of view of 2.00° × 1.60°, and a large field of view of 4.00° × 3.20°. In the zoom process, the wavelength range is 0.45-0.70 ㎛ and 0.75-1.10 ㎛, and the size of the optical system is 168 mm (L) × 90 mm (W) × 60 mm (H). The overall lens weight is only 170.8 g, which has advantages for miniaturization and light weight. At the Nyquist frequency of 104 lp/mm, the modulation transfer function of the visible-light optical system is more than 0.44, and that of the near-infrared optical system is more than 0.30, both of which have good imaging quality and tolerance characteristics in the range of -45 to 60 ℃.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.875-884
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• 2000

Sea fog/stratus is very difficult to detect because of the characteristics of air-sea interaction and locality ,and the scantiness of the observed data from the oceans such as ships or ocean buoys. The aim of our study develops new algorism for sea fog detection by using Geostational Meteorological Satellite-5(GMS-5) and suggests the technics of its continuous detection. In this study, atmospheric synoptic patterns on sea fog day of May, 1999 are classified; cold air advection type(OOUTC, May 10, 1999) and warm air advection type(OOUTC, May 12, 1999), respectively, and we collected two case days in order to analyze variations of water vapor at Osan observation station during May 9-10, 1999.So as to detect daytime sea fog/stratus(OOUTC, May 10, 1999), composite image, visible accumulated histogram method and surface albedo method are used. The characteristic value during day showed A(min) .20% and DA < 10% when visible accumulated histogram method was applied. And the sea fog region which is detected is similar in composite image analysis and surface albedo method. Inland observation which visibility and relative humidity is beneath 1Km and 80%, respectively, at OOUTC, May 10,1999; Poryoung for visble accumulated histogram method and Poryoung, Mokp'o and Kangnung for surface albedo method. In case of nighttime sea fog(18UTC, May 10, 1999), IR accumulated histogram method and Maximum brightness temperature method are used, respectively. Maxium brightness temperature method dectected sea fog better than IR accumulated histogram method with the charateristic value that is T_max < T_max_trs, and then T_max is beneath 700hPa temperature of GDAPS(Global Data Assimilation and Prediction System). Sea fog region which is detected by Maxium brighness temperature method was similar to the result of National Oceanic and Atmosheric Administratio/Advanced Very High Resolution Radiometer (NOAA/AVHRR) DCD(Dual Channel Difference), but usually visibility and relative humidity are not agreed well in inland.