• Proceedings of the Korea Information Processing Society Conference
• /
• 2013.11a
• /
• pp.1483-1486
• /
• 2013

최근 무선통신의 급격한 발전과 스마트 기기의 확산으로 인해 Tving, pooq 등 다양한 모바일 방송 서비스가 급속도로 증가하고 있다. 또한 다양한 영상처리 기법 등이 등장함에 따라 4K, 8K급의 UHD 동영상들이 속속들이 등장하고 있다. 이로 인해 트랜스코딩을 통해 가공되는 동영상의 포맷 및 해상도 또한 매우 다양해질 것으로 전망된다. 현재까지의 트랜스코딩 연구사례는 사용자의 이동환경을 고려한 안정적 QoS 보장 또는 서버의 부하를 줄이기 위한 분산처리 기법 등의 연구 위주로 진행되어 온 것이 현실이다. 하지만 상기 조건(adaptive streaming 및 서버부하 처리)들을 충족시키긴 위해선 보다 효율적인 트랜스코딩 시스템의 제공이 선행 되어야 할 것이다. 이에 따라 본 논문에서는 사용자 관점에서 보다 빨리 스트리밍 서비스를 제공 받기 위하여 우선순위 큐 알고리즘을 적용한 시스템을 설계 및 구현하였다. 검증을 위하여 4가지 콘테이너(.MOV, .FLV, .MKV, .AVI)를 실험대상으로 하였고, 비교 대상 트랜스코딩 시스템은 상용 스트리밍 서비스인 YouTube를 활용하였다. 성능 측정결과, 총 트랜스코딩 완료시간은 YouTube에 비해 41.61%로 시간이 단축되었다. 또한 모바일 TV시청자가 55%를 차지한다는 점을 고려하여 컨트롤 서버에서는 최단시간 서비스 제공을 위하여 저해상도부터 추출하여 스트리밍 서버를 통해 송출하도록 구현하였다. 본 연구결과는 트랜스코딩 성능개선 뿐만 아니라 모바일 대상자를 위한 맞춤형 서비스를 보다 빨리 제공할 수 있을 것이며, 그 수요는 점차 증대될 것으로 예상된다.

• Journal of Intelligence and Information Systems
• /
• v.26 no.4
• /
• pp.87-109
• /
• 2020

Currently, thanks to the major stride made in developing wired and wireless communication technology, a variety of IT services are available on land. This trend is leading to an increasing demand for IT services to vessels on the water as well. And it is expected that the request for various IT services such as two-way digital data transmission, Web, APP, etc. is on the rise to the extent that they are available on land. However, while a high-speed information communication network is easily accessible on land because it is based upon a fixed infrastructure like an AP and a base station, it is not the case on the water. As a result, a radio communication network-based voice communication service is usually used at sea. To solve this problem, an additional frequency for digital data exchange was allocated, and a ship ad-hoc network (SANET) was proposed that can be utilized by using this frequency. Instead of satellite communication that costs a lot in installation and usage, SANET was developed to provide various IT services to ships based on IP in the sea. Connectivity between land base stations and ships is important in the SANET. To have this connection, a ship must be a member of the network with its IP address assigned. This paper proposes a SANET-CC protocol that allows ships to be assigned their own IP address. SANET-CC propagates several non-overlapping IP addresses through the entire network from land base stations to ships in the form of the tree. Ships allocate their own IP addresses through the exchange of simple requests and response messages with land base stations or M-ships that can allocate IP addresses. Therefore, SANET-CC can eliminate the IP collision prevention (Duplicate Address Detection) process and the process of network separation or integration caused by the movement of the ship. Various simulations were performed to verify the applicability of this protocol to SANET. The outcome of such simulations shows us the following. First, using SANET-CC, about 91% of the ships in the network were able to receive IP addresses under any circumstances. It is 6% higher than the existing studies. And it suggests that if variables are adjusted to each port's environment, it may show further improved results. Second, this work shows us that it takes all vessels an average of 10 seconds to receive IP addresses regardless of conditions. It represents a 50% decrease in time compared to the average of 20 seconds in the previous study. Also Besides, taking it into account that when existing studies were on 50 to 200 vessels, this study on 100 to 400 vessels, the efficiency can be much higher. Third, existing studies have not been able to derive optimal values according to variables. This is because it does not have a consistent pattern depending on the variable. This means that optimal variables values cannot be set for each port under diverse environments. This paper, however, shows us that the result values from the variables exhibit a consistent pattern. This is significant in that it can be applied to each port by adjusting the variable values. It was also confirmed that regardless of the number of ships, the IP allocation ratio was the most efficient at about 96 percent if the waiting time after the IP request was 75ms, and that the tree structure could maintain a stable network configuration when the number of IPs was over 30000. Fourth, this study can be used to design a network for supporting intelligent maritime control systems and services offshore, instead of satellite communication. And if LTE-M is set up, it is possible to use it for various intelligent services.

• Korean Journal of Remote Sensing
• /
• v.34 no.2_2
• /
• pp.419-429
• /
• 2018

An unmanned autonomous maritime surface system can move the vehicle to the areas for observing the ocean accidents, disasters, and severe weather conditions. Detection and monitoring technologies have been developed by the converging of the regional and local surveillance system. Wave Glider, one of the autonomous maritime surface systems, is ocean-wave propelled autonomous surface vehicle and controlled using Iridium satellite communication. In this study, we carried out two-time Wave Glider observations for 2016 and 2017 summer in the East China Sea that the area was influenced by low-salinity water. We observed the sea surface warming effect due to the low-salinity water using the regional (satellite) and local (Wave Glider) surveillance system. We also monitored the effect of the typhoon and understood the change of the ocean-atmosphere environments in real-time. New unmanned surface system with autonomous system and high endurance structure can measure comprehensively and usefully a long observation in complicated ocean environments because of connecting with other surveillance systems.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2015.07a
• /
• pp.100-102
• /
• 2015

In recent years, using a smart phone that can access the Internet becomes routine in society through development of information and communication technology. On land, as especially actual accidents and research results show risk that using the smart phone while driving at the same time, and there are traffic laws and regulations that restriction of using of smart phone. But the regulations on the use of smart phones at sea is incomplete state. On this paper. We invested present status of use and reality of smart phone at sea and analyzed the subjective risk for judging to apply to regulation. And we analyzed risk quantitatively by using the simulation experiment; it Suggested a direction of guideline for use of smart phone at sea.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.1 s.39
• /
• pp.251-258
• /
• 2006

When producing a wireless web contents by using wire web contents for PC environment, we should consider how to represent lots of information being suitable with PC environment to wireless devices having narrow performance. Therefore, we propose mobile page editor for manager to select and modify specific contents with the existing wire web page. Also, we try to define an intermediate language based on DID(Digital Item Declaration) of MPEG-21 multimedia framework which defines source of converting information and wireless web contents generating at mobile editor in considering real time service problem when transcoding multimedia information in a web server into wireless device having low resolution, narrow performance of media process, memory, and so on.

• The Journal of the Acoustical Society of Korea
• /
• v.38 no.1
• /
• pp.106-113
• /
• 2019

In this paper, we propose an algorithm to classify the received active pulse when the active sonar system is operated as a non-cooperative mode. The proposed algorithm uses CNN (Convolutional Neural Networks) which shows good performance in various fields. As an input of CNN, time frequency analysis data which performs STFT (Short Time Fourier Transform) of the received signal is used. The CNN used in this paper consists of two convolution and pulling layers. We designed a database based neural network and a pulse feature based neural network according to the output layer design. To verify the performance of the algorithm, the data of 3110 CW (Continuous Wave) pulses and LFM (Linear Frequency Modulated) pulses received from the actual ocean were processed to construct training data and test data. As a result of simulation, the database based neural network showed 99.9 % accuracy and the feature based neural network showed about 96 % accuracy when allowing 2 pixel error.

• Journal of Software Assessment and Valuation
• /
• v.17 no.2
• /
• pp.1-10
• /
• 2021

The ability to recognize human emotions by computer vision is a very important task, with many potential applications. Therefore the demand for emotion recognition using not only RGB images but also thermal images is increasing. Compared to RGB images, thermal images has the advantage of being less affected by lighting conditions but require a more sophisticated recognition method with low-resolution sources. In this paper, we propose a Divide and Conquer-based CNN training strategy to improve the performance of facial thermal image-based emotion recognition. The proposed method first trains to classify difficult-to-classify similar emotion classes into the same class group by confusion matrix analysis and then divides and solves the problem so that the emotion group classified into the same class group is recognized again as actual emotions. In experiments, the proposed method has improved accuracy in all the tests than when recognizing all the presented emotions with a single CNN model.

• Journal of Advanced Navigation Technology
• /
• v.27 no.5
• /
• pp.674-684
• /
• 2023

In this paper, a real-time prediction technique for gravity disturbances is proposed using a multi-layer perceptron (MLP) model. To select a suitable MLP model, 4 models with different network sizes were designed to compare the training accuracy and execution time. The MLP models were trained using the data of vehicle moving along the surface of the sea or land, including their positions and gravity disturbance. The gravity disturbances were calculated using the 2160^th degree and order EGM2008 with SHM. Among the models, MLP4 demonstrated the highest training accuracy. After training, the weights and biases of the 4 models were stored in the embedded computer of the INS to implement the MLP network. MLP4 was found to have the shortest execution time among the 4 models. These research results are expected to contribute to improving the navigation accuracy of INS through gravity disturbance compensation in the future.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.4A
• /
• pp.239-249
• /
• 2012

Recently, the virtual view generation method using depth data is employed to support the advanced stereoscopic and auto-stereoscopic displays. Although depth data is invisible to user at 3D video rendering, its accuracy is very important since it determines the quality of generated virtual view image. Many works are related to such depth enhancement exploiting a time-of-flight (TOF) camera. In this paper, we propose a fast 3D scene capturing system using one TOF camera at center and two high-resolution cameras at both sides. Since we need two depth data for both color cameras, we obtain two views' depth data from the center using the 3D warping technique. Holes in warped depth maps are filled by referring to the surrounded background depth values. In order to reduce mismatches of object boundaries between the depth and color images, we used the joint bilateral filter on the warped depth data. Finally, using two color images and depth maps, we generated 10 additional intermediate images. To realize fast capturing system, we implemented the proposed system using multi-threading technique. Experimental results show that the proposed capturing system captured two viewpoints' color and depth videos in real-time and generated 10 additional views at 7 fps.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.6C
• /
• pp.349-354
• /
• 2011

Passive millimeter wave imaging has the capability of detecting concealed objects under clothing. Also, passive millimeter imaging can obtain interpretable images under low visibility conditions like rain, fog, smoke, and dust. However, the image quality is often degraded due to low spatial resolution, low signal level, and low temperature resolution. This paper addresses image registration and fusion between passive millimeter images and visual images. The goal of this study is to combine and visualize two different types of information together: human subject's identity and concealed objects. The image registration process is composed of body boundary detection and an affine transform maximizing cross-correlation coefficients of two edge images. The image fusion process comprises three stages: discrete wavelet transform for image decomposition, a fusion rule for merging the coefficients, and the inverse transform for image synthesis. In the experiments, various types of metallic and non-metallic objects such as a knife, gel or liquid type beauty aids and a phone are detected by passive millimeter wave imaging. The registration and fusion process can visualize the meaningful information from two different types of sensors.