• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.2
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• pp.102-107
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• 2007

A remarkable sea surface cooling (SSC) event was observed in the eastern sea of Korean peninsula based on new generation sea surface temperature (NGSST) satellite images in September 2005, when typhoon Nabi passed over the East Sea. The degree of SSC ranged from $1^{\circ}C\;to\;4^{\circ}C$, and its maximum was observed in the southeastern sea area. Daily variations in sea surface temperature at a longitudinal line $(35^{\circ}-41^{\circ}N,\;132^{\circ}E)$, derived from satellite data for September 1-13, 2005, showed that the SSC lasted about 3 days after the typhoon passed in the south of $39^{\circ}N$, whereas it was unclear in the north of$39^{\circ}N$. Water temperature measured by a mooring buoy suggested that the SSC was caused mainly by a vertical mixing of the water column driven by the typhoon, rather than by coastal upwelling.

• Journal of Industrial Convergence
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• v.18 no.1
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• pp.79-85
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• 2020

Recently, the RPAS(Remote Piloted Aircraft System), by remote control and autonomous navigation, has been increasing in interest and utilization in various industries and public organizations along with delivery drones, fire drones, ambulances, agricultural drones, and others. The problems of the stability of unmanned drones, which can be self-controlled, are also the biggest challenge to be solved along the development of the drone industry. drones should be able to fly in the specified path the autonomous flight control system sets, and perform automatically an accurate landing at the destination. This study proposes a technique to check arrival by landing point images and control landing at the correct point, compensating for errors in location data of the drone sensors and GPS. Receiving from the Google Map API and learning from the destination video, taking images of the landing point with a drone equipped with a NAVIO2 and Raspberry Pi, camera, sending them to the server, adjusting the location of the drone in line with threshold, Drones can automatically land at the landing point.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1414-1424
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• 2004

In this paper, an algorithm using wavelet transform for detecting a cut that is a radical scene transition point, and fade and dissolve that are gradual scene transition points is proposed. The conventional methods using wavelet transform for this purpose is using features in both spatial and frequency domain. But in the proposed algorithm, the color space of an input image is converted to YUV and then luminance component Y is transformed in frequency domain using 2-level lifting. Then, the histogram of only low frequency subband that may contain some spatial domain features is compared with the previous one. Edges obtained from other higher bands can be divided into global, semi-global and local regions and the histogram of each edge region is compared. The experimental results show the performance improvement of about 17% in recall and 18% in precision and also show a good performance in fade and dissolve detection.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.159-162
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• 2017

Along with the popular use of commercial drones, there are increased concerns on the possible threats from drones intruding into secured areas. The difficulty of drone detection is attributed to its stealthy operation flying at low altitude with low level signature. Consequently, the anti-drone technique has been of major research topic in recent years and among others, the radar detection is considered as the most promising technique. However, the use of conventional radar detection may not be effective due to the low level radar cross sections of the commercial drones. In this paper, ISAR technique has been employed to implement drone detection in urban area. To this purpose, a pulsed radar system is set up on the ground to track flying drones and the corresponding ISAR images are produced by coherent processing.

• Journal of Broadcast Engineering
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• v.23 no.2
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• pp.261-273
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• 2018

As progress on image processing, computer vision and display technologies aroused market's interests on generation and consumption of various types of media, interests on UWV media are also increasing. In context of consumption of UWV media, to effectively manage load of servers and resources of end terminal devices and provide user-derived services, technology which enables users to select and consume interested regions of media seems to be needed. Here, this paper proposes a method for description and transmission of spatial relationships among media, which composes UWV, by expanding MPEG-CI and Layout signaling to enable users' selective consumption of UWV media.

• Korean Journal of Remote Sensing
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• v.29 no.2
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• pp.161-172
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• 2013

The construction of hyperspectral test-bed dataset is essential for the effective performance of hyperspectral image for various applications. In this study, we analyzed the technical points for generating of optimal hyperspectral test-bed site for hyperspectral sensors and the efficiency of hyperspectral test-bed site. In this regard regions we analyzed existing construction techniques for generating test-bed site in domestic and foreign, and designed the test-bed site to acquire images from the airborne hyperspectral sensor. To produce a reference data from the image of constructed test-bed site, this study applied vicarious correction as a pre-processing and analyzed its efficiency. The result presented that it was ideal to use tarp for the vicarious correction, but it is possible to use the materials with constant spectral reflectance or with relatively low variance of spectral reflectance. The test-bed data taken in this study can be employed as the reference of domestic and foreign studies for hyperspectral image processing.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.49-58
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• 2005

In this paper, we proposed a blind watermarking algerian to use characteristics of a scalar quantizer which is the recommended in the JPEG2000 and JPEG. The proposed algorithm shifts a quantization index according to the value of each watermark bit to prevent losing the watermark information during the compression by quantization. Therefore, the watermark is embedded during the process of quantization, not an additional process for watermarking, and is adaptively applied as a assigned quantizer according application areas. Before embedding process, a LFSR(Linear feedback shift register) rearranged the watermark for the security of the watermark itself and in the embedding process, a LFSR is used to hide the watermarking positions. Therefore the embedded watermark can he extracted by only the owner who knows the initial value of LFSR without the original image. The visual recognizable pattern such as a binary image was used as the watermark. The experimental results showed that the proposed algerian satisfies the robustness and imperceptibility corresponding to the major requirement of watermarking. The results showed the largest error rate to be $5.7\%$ for attack. The experimental result which compares the proposed algorithm with the Mohamed algorithm showed that the proposed algorithm was better than it, exactly $4\~5$ times for the attacks of JPEG and JPEG2000.

• Journal of the Korean Society of Radiology
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• v.81 no.3
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• pp.620-631
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• 2020

Purpose We aimed to assess local tumor progression (LTP) rate and associated prognostic factors in 92 patients who underwent radiofrequency ablation (RFA) using saline-perfused electrodes to treat hepatocellular carcinoma (HCC) (≤ 5 cm). Materials and Methods Total 92 patients with 148 HCCs were treated with RFA using saline-perfused electrodes, from 2009 to 2015. We retrospectively evaluated technical success, technique efficacy, and LTP rates. Potential prognostic factors for LTP were perivascular tumor, subphrenic tumor, artificial ascites, tumor size (≥ 2 cm), and previous treatment of transarterial chemoembolization. Analysis was performed by lesion, rather than by person. Results During follow-up period from 1 to 97.4 months, total cumulative LTP rates were 7.9%, 11.4%, and 14.6% at 1, 3, and 5 years, respectively. These values were significantly higher in the perivascular (35.1%; p = 0.009) and subphrenic group (38.9%; p = 0.002) at 5-year. We did not observe any significant difference in LTP according to other prognostic factors (p > 0.05). Conclusion RFA with saline-perfused electrode is a safe and effective treatment modality for HCC (≤ 5 cm), with lower LTP rates. Nevertheless, perivascular and subphrenic HCCs demonstrated higher LTP rate than other sites. It is imperative to note that perivascular and subphrenic location of HCC are associated with a high risk of local recurrence, despite the use of saline-perfused electrodes.

• Journal of Chest Surgery
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• v.29 no.5
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• pp.585-588
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• 1996

We experienced a case of upper esophageal leiomyoma successfully excised by thoracoscopic surgery. A 29-year-old male was presented with retrosternal discomfort and mild dysphagia and an esophagogram revealed smooth fElling defect In the upper third of the intrathor cic esophagus, and esophagoscopy showed a submucosal tumor without mucosal infiltration. Chest CT and MRI were performed to confirm size, character and location of the esophageal mass, the absence of infiltration of surrounding structures, and to define mediastinal Iymphadenopathy. The tumor was excised by thoracoscopic surgery and it was diagnosed as leiomyoma (4$\times$2xlcm in size). The postoperative course was uneventful.

• Imaging Science in Dentistry
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• v.37 no.2
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• pp.79-82
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• 2007

Purpose: The purpose of this study was to investigate whether panoramic radiographs were useful in predicting osteoporosis. Materials and Methods: 50 postmenoposal women between the age of 41.8 and 78.5 were classified as normal and osteoporosis groups according to the bone mineral density of lumbar vertebrae. Panoramic radiographs were taken. Age, body mass index, remaining mandibular teeth, mandibular cortical thickness and morphology, and fractal dimensions at periapical areas of mandibular first molars were evaluated to differentiate the two groups. Results: The age of osteoporotic group was statistically significantly higher than that of normal group (p<0.05), but not the body mass index or number of remaining mandibular teeth. The mean fractal dimension of osteoporotic group was $1.391{\pm}0.085$, and was significantly lower than that of the normal group, which was $1.523{\pm}0.725$ (p<0.01). Thick mandibular cortical thickness was common in normal group, whereas thin or very thin mandibular cortical thickness was common in osteoporotic group and the difference was significant (p < 0.05). C2 pattern was common in normal group followed by C1, whereas C2 was common in osteoporotic group followed by C3. The difference was statistically significant (p< 0.0 1). Conclusion: Age, mandibular cortical thickness and shape, fractal dimension on panoramic radiographs were useful in predicting osteoporosis.