• Radiation Oncology Journal
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• v.16 no.4
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• pp.497-504
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• 1998

Purpose : To evaluate the usefulness of electronic portal imaging device through objective compare of the images acquired using an EPID and a conventional port film Materials and Methods : From Apr. to Oct. 1997, a total of 150 sets of images from 20 patients who received radiation therapy in the pelvis area were evaluated in the Inha University Hospital and Severance Hospital. A dual image recording technique was devised to obtain both electronic portal images and port film images simultaneously with one treatment course. We did not perform double exposure five to ten images were acquired from each patient. All images were acquired from posteroanterior (PA) view except images from two patients. A dose rate of 100-300 Mu/min and a 10-MV X-ray beam were used and 2-10 MUs were required to produce a verification image during treatment. Kodak diagnostic film with metal/film imaging cassette which was located on the top of the EPID detector was used for the port film. The source to detector distance was 140 cm. Eight anatomical landmarks (pelvic brim, sacrum, acetabulum. iliopectineal line, symphysis, ischium, obturator foramen, sacroiliac joint) were assessed. Four radiation oncologist joined to evaluate each image. The individual landmarks in the port film or in the EPID were rated - very clear (1), clear (2), visible (3), not clear (4), not visible (5). Results : Using an video camera based EPID system. there was no difference of image quality between no enhanced EPID images and port film images. However, when we provided some change with window level for the portal image, the visibility of the sacrum and obturator foramen was improved in the portal images than in the port film images. All anatomical landmarks were more visible in the portal images than in the port film when we applied the CLAHE mode enhancement. The images acquired using an matrix ion chamber type EPID were also improved image qualify after window level adjustment. Conclusion : The quality of image acquired using an electronic portal imaging device was comparable to that of the port film. When we used the enhance mode or window level adjustment. the image quality of the EPID was superior to that of the port film. EPID may replace the port film.

• Journal of Internet Computing and Services
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• v.17 no.4
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• pp.145-159
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• 2016

This study points out the problems of absence of the legislation for standard regulation on Video on Demand(VoD) advertisement which grows so fast lately, for this it recommends making legal references, which have the definition of non-linear broadcasting & VoD advertisement and VoD advertisement standard regulation in the merged Broadcasting Act, and adopting co-regulation system. Pay TV operators providing VoD service have the opportunities to make money as subscribers uses it increasingly. In case of linear service, the Broadcasting Act regulates the advertisement strictly, but not the VoD ads. The reason why is that Korean legislation including the Broadcasting Act does not have legal reference to regulate it, instead of that, it rely on the self-regulation system which is operated by pay-tv players who provide the VoD ads. So, there is the limitation to protect the minors such as children and youth from the harmful VoD ads, to be invulnerable for advertisers to influence to advertising agents, and to ensure the regulatory effectiveness under player-centric self-regulatory regime. In this context, this study analyses the how to regulate VoD ads standard with a three-pronged approach. First, it analyses the VoD ads regulation system in overseas countries, UK, Canada, EU and Ireland. Each country has the legal reference to regulate it in the Broadcasting Act or lower statures and adopts the co-regulatory regime the NRA and the 3rd entity operate together. Second, it reviews the objectives and scope of VoD ads standard. This study recommends that the objective of it is users protection and the scope of it is standard regulation not commercial practice. Third, this study researches how to legislate for regulation of VoD ads standard. Considering VoD service's characteristics(non-linear service) and legal position of Ads agency(i.e. pay tv operators), it suggest that legal reference will be in the integrated Broadcasting bill, which is the general law, not individual. If it is available to regulate VoD ads standard with co-regulatory regime, it expects the enhancement of user protection from the harmful VoD ads and make up sustainability of the pay-tv players' self-regulation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.117-126
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• 2010

In the case of failure images with controlling lighting like backlighting and excessive frontlinghting, the compensation scheme for a specific area in an image is required. The interested region is first selected by user in our method to compensate the first frame. Then we define the matching function of brightness and energy function is proposed with weight of matching function and the relationship among the neighbors. Finally, the energy is minimized by the graph-cut algorithm to compensate the brightness of the first frame. Other frames are straightforwardly compensated using the results of the first frame. The brightness variations of the previous frame is transmitted to the next frame via motion vectors. The reliability of the brightness variation is calculated based on the motion vector reliability. Video compensation result is achieved by the process of the image case. Simulation show that the proposed algorithm provides more natural results than the conventional algorithms.

• The Journal of the Acoustical Society of Korea
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• v.21 no.6
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• pp.566-575
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• 2002

Low-titrate audio coding enables a number of Internet and mobile multimedia streaming service more efficiently. For the help of next-generation mobile telephone technologies and digital audio/video compression algorithm, we can enjoy the real-time multimedia contents on our mobile devices (cellular phone, PDA notebook, etc). But the limited available bandwidth of mobile communication network prohibits transmitting high-qualify AV contents. In addition, most bandwidth is assigned to transmit video contents. In this paper, we design a novel and simple method for reproducing high frequency components. The spectrum of high frequency components, which are lost by down-sampling, are modeled by the energy rate with low frequency band in Bark scale, and these values are multiplexed with conventional coded bitstream. At the decoder side, the high frequency components are reconstructed by duplicating with low frequency band spectrum at a rate of decoded energy rates. As a result of segmental SNR and MOS test, we convinced that our proposed method enhances the subjective sound quality only 10%∼20% additional bits. In addition, this proposed method can apply all kinds of frequency domain audio compression algorithms, such as MPEG-1/2, AAC, AC-3, and etc.

• The Journal of Information Technology
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• v.7 no.2
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• pp.93-104
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• 2004

Sports scene is characterized by large amount of global motion due to pan and zoom of camera motion, and includes many small objects moving independently. Some short period of sports games is thrilling to televiewers, and important to producers. At the same time that kinds of scenes exhibit exceptionally dynamic motions and it is very difficult to analyze the motions with conventional algorithms. In this thesis, several algorithms are proposed for global motion analysis on these dynamic scenes. It is shown that proposed algorithms worked well for motion compensation and panorama synthesis. When cascading the inter frame motions, accumulated errors are unavoidable. In order to minimize these errors, interpolation method of motion vectors is introduced. Affined transform or perspective projection transform is regarded as a square matrix, which can be factorized into small amount of motion vectors. To solve factorization problem, we preposed the adaptation of Newton Raphson method into vector and matrix form, which is also computationally efficient. Combining multi frame motion estimation and the corresponding interpolation in hierarchical manner enhancement algorithm of motion parameters is proposed, which is suitable for motion compensation and panorama synthesis. The proposed algorithms are suitable for special effect rendering for broadcast system, video indexing, tracking in complex scenes, and other fields requiring global motion estimation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.997-1005
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• 2010

Recently, there has been a growing interest in the use of WLAN technology due to its easy deployment, flexibility and so on. Examples of WLAN applications range from standard internet services such as Web access to real-time services with strict latency/throughput requirements such as multimedia video and voice over IP on wireless network environments. Fair and efficient distribution of the traffic loads among APs(Access Points) has become an important issue for improved utilization of WLAN. This paper focuses on an AP selection scheme for achieving better load balance, and hence increasing network resource utilization for each user on wireless network environments. This scheme makes use of active scan patterns and the network delay as main parameters of load measurement and AP selection. This scheme attempts to estimate the AP traffic loads by observing the up/down delay and utilize the results to maximize the link resource efficiency through load balancing. We compared the proposed scheme with the original SNR(Signal to Noise Ratio)-based scheme using the NS-2(Network Simulation.2). We found that the proposed scheme improves the throughput by 12.5% and lower the network up/down link delay by 36.84% and 60.42%, respectively. All in all, the new scheme can significantly increase overall network throughput and reduce up/down delay while providing excellent quality for voice and video services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.10
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• pp.858-866
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• 2013

In the DVB-S2, which is the technical specification of the second generation digital video broadcasting via satellite, APSK modulation scheme along with LDPC coding schemes are defined. APSK is a multi-lelvel PSK modulation scheme and decoding of LDPC coded signal requires soft decision information. Therefore, the APSK demodulator at the receiver should have capability of estimating soft information. In this paper, we introduce a method to estimate soft information by using simple distance estimation, and show that this method overestimates the soft information. Subsequently, this overestimated soft information leads to performance degradation. In order to overcome this problem, we propose a scaling method to improve the performance at the receiver In addition, we show that the proposed scaling scheme enables us to estimate the soft information with linear order complexity and produce the performance close to the maximum likelihood detection.

• Korean Journal of Social Welfare
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• v.60 no.1
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• pp.77-102
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• 2008

The purpose of this study is to know what impression management(IM) tactics social work applicants use in their job interviews and what relation between their IM tactics and interviewers' evaluation exists. To accomplish this purpose, we reviewed the precedent researches about IM and conducted a qualitative study with the applicants in a community welfare center which adopted open approach in recruitment process. We analyzed the applicants' IM tactics through observing video-taped interview sessions and reviewing interviewers' rating paper. The results showed that the social work applicants mainly used self-promotion tactic for emphasizing their strengths and justification tactics for expressing their weaknesses. Some applicants often used fit-with-organization and other-enhancement belonged to ingratiation tactics. According to interviewers' rating results, the applicants with deep eye contact, calm attitude or smiling face gave a good impression to the interviewers. In the final discussion, an applicant who adopted diverse verbal and non-verbal tactics and expressed her point clearly was perceived attractive by the interviewers and accepted as the best choice. Based on this qualitative analysis, we have made several practical suggestions for social work applicants, social work researchers and social work organizations.

• Journal of KIISE:Information Networking
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• v.35 no.6
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• pp.549-556
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• 2008

To achieve flexible visual content adaption for multimedia communications, the ISO/IEC MPEG & ITU-T VCEG form the JVT to develop SVC amendment for the H.264/AVC standard. JVT uses inter-layer prediction as well as inter prediction and intra prediction that are provided in H.264/AVC to remove the redundancy among layers. The main goal consists of designing inter-layer prediction tools that enable the usage of as much as possible base layer information to improve the rate-distortion efficiency of the enhancement layer. But inter layer prediction causes the computational complexity to be increased. In this paper, we proposed an efficient residual prediction. In order to reduce the computational complexity while maintaining the high coding efficiency. The proposed residual prediction uses modified interpolation that is defined in H.264/AVC SVC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2485-2490
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• 2010

In this paper, gather the sleep environment data of bedroom to sleeping and analyze the relationship between the obtained conditional data and the sleep. Based on this, system provide the optimal sleep environment of individual person by extracting the simulation model. The experiments of system was using H-MOTE2420 sensor composed of temperature/humidity sensor and ambient light sensors. We use difference image method in motion extraction from video for extraction of tossing and turning. In addition, it was entered such as ratio of fatigue, ratio of drinking, ratio of empty stomach as the information of weight can affect to sleep. Resultingly of experience, we can extract the optimal sleep environment. From now on, we will try to enhance to help to lead more pleasant daily life providing proper indoor environment changes depending on the situation even a partial of organic living environments such as eating and work as well as special sleep circumstances.