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H.264/AVC의 실시간 압축을 위한 고속 인터 예측 부호화 기술
김영현,최현준,서영호,김동욱,Kim, Young-Hyun,Choi, Hyun-Jun,Seo, Young-Ho,Kim, Dong-Wook 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.11C
This paper proposed a fast algorithm to reduce the amount of calculation for inter prediction which takes a great deal of the operational time in H.264/AVC. This algorithm decides a search range according to the direction of predicted motion vector, and then performs an adaptive spiral search for the candidates with JM(Joint Model) FME(Fast Motion Estimation) which employs the rate-distortion optimization(RDO) method. Simultaneously, it decides a threshold cost value for each of the variable block sizes and performs the motion estimation for the variable search ranges with the threshold. These activities reduce the great amount of the complexity in inter prediction encoding. Experimental results by applying the proposed method .to various video sequences showed that the process time was decreased up to 80% comparing to the previous prediction methods. The degradation of video quality was only from 0.05dB to 0.19dB and the compression ratio decreased as small as 0.58% in average. Therefore, we are sure that the proposed method is an efficient method for the fast inter prediction. 본 논문에서는 H.264/AVC에서 가장 많은 연산량을 차지하는 인터 예측(inter prediction)을 고속으로 수행할 수 있는 방법을 제안하였다. 제안한 방법은 율-왜곡 최적화 기법(Rate-Distortion Optimization, RDO)이 적용된 JM(Joint Model)의 FME(Fast Motion Estimation)를 대상으로 예측된 움직임 벡터의 방향성을 고려하여 탐색영역을 결정한 후 적응적인 후보 나선형 탐색을 수행한다. 동시에 가변 블록 크기에 대하여 비용함수의 임계값(threshold)을 결정한 후 가변 구간 움직임 탐색을 수행함으로써 인터 예측의 부호화 복잡도를 감소시킨다. 다양한 영상들을 대상으로 실험한 결과 기존의 예측 방식에 최대 80%의 연산량을 줄일 수 있음을 확인하였다. 이에 따른 화질 열화는 평균 $0.05dB{\sim}0.19dB$에 불과하며, 압축률은 평균 0.58%의 미미한 감소를 보임으로써, 제안한 방법이 고속 인터 예측 알고리즘으로 매우 효율적인 방법임을 확인하였다.
김영현,이종철,이형준,최정석,김보형,강성호,유명상,Kim, Young Hyun,Lee, Jong Cheol,Lee, Hyung Jun,Choi, Jung Suk,Kim, Bo Hyung,Kang, Sung Ho,Yu, Myeong Sang 대한기관식도과학회 2011 大韓氣管食道科學會誌 Vol.17 No.1
Spontaneous tonsillar bleeding is a rare condition in ENT unit. Almost reported cases have been related to infection of tonsils. Prior to introduction of antibiotics, spontaneous tonsillar bleeding was usually related to superficial capsular bleeding due to acute or chronic tonsillitis. The presented case is a 36-year old healthy man without history of acute, chronic tonsillitis, and coagulation disorder who complained of dyspnea and oropharyngeal foreign body sensation after vomitting. Examination revealed a reddish polypoid mass of the right tonsil. Furthermore, the mass pushed uvula and tongue base, caused nearly total obstruction of oropharynx. All rountine laboratory test results were within normal limits. Computed tomography (CT) showed low density mass of attached in upper pole of right tonsil without enhancement. We performed tonsillectomy including the reddish polypoid mass under general anesthesia. The pathology revealed lymphoepithelial tissue with reactive hyperplasia. This is the first reported tonsillar hematoma presenting as a large oropharyngeal mass which was caused by vomitting.
Ad Hoc Mobile Wireless Network에서 효과적인 Multicast Tree구축 기법
김영현(Young-Hyun Kim),최종원(Jong-Won Choe) 한국정보과학회 2000 한국정보과학회 학술발표논문집 Vol.27 No.2Ⅲ
무선 Ad-hoc 네트워크는 어떠한 하부구조와 중앙관리의 도움 없이 임시 네트워크를 구성하는 무선 이동 호스트들의 집합이다. Ad-hoc 네트워크에도 오디오/비디오 등의 컨퍼런스가 열릴 수 있으며, 이때 다중의 호스트에 데이터를 전달하는 멀티캐스트 작업이 필요하다. Ad-hoc 네트워크에서는 네트워크 토폴로지의 동적인 변화로 인하여 전송경로가 변동되는 문제가 발생될 수 있다. 따라서 기존의 유선 네트워크에서 사용하던 트리 구축방법을 사용할 수 없다. 이러한 문제를 미리 예측하기 위하여 게이트웨이 호스트들의 이동성을 단계별로 분류한 것과 결합도를 전송하여 트리를 구축함으로써 호스트들의 이동에 따른 트리상의 경로가 끊어질 확률을 줄여 트리 재구축으로 소모되는 시간과 경비를 줄일 수 있다.
초등영어 문법교육에 대한 영어 전담교사의 인식과 통합적 문법지도 방안
김영현 ( Young Hyun Kim ) 21세기영어영문학회 2018 영어영문학21 Vol.31 No.3
This paper has dual aims. One is to analyze the results of interviewing four English teachers about focus on form approaches and corrective feedback techniques as well as English grammar teaching in elementary schools, focused on the necessity, the timing and the methods of grammar instruction. The other is to discuss strategies for integrating grammar instruction with communicative language use to propose effective grammar teaching approaches which can be implemented in the elementary school English classroom. The results of this study are as follows: Grammar should be taught to 5th and 6th grade students deductively, if necessary, as well as inductively since they will have to develop productive skills and written language skills to communicate more accurately with each other. Focus on form approaches are needed for students to pay attention to specific forms or correct their errors by themselves during communicative tasks under the teacher’s preferred corrective feedback techniques such as recasts, elicitation, repetition, etc. Two types of approaches are discussed to integrate grammar instruction with communicative language use. One is to design focused communicative tasks that focus students' attention on the predetermined specific forms during the tasks. The other is to provide reactive feedback explicitly or implicitly when grammatical errors occur while students’ primary attention is on meaning during the tasks. It is suggested that grammar can be taught to students at the intermediate level or above based on the former approach in which they can pay attention to specific forms, whereas it can be taught to most other students based on the latter in which they can receive the teacher’s feedback to correct errors, during communicative tasks.
단지조성공사의 미세먼지 측정 및 GIS Mapping을 통한 미세먼지 측정 고려요소 도출
김영현 ( Kim Young Hyun ),한재구 ( Han Jae Goo ) 한국건축시공학회 2020 한국건축시공학회 학술발표대회 논문집 Vol.20 No.1
When measuring fine dust at a large-scale site such as complex construction, the change in the value of fine dust measurement is large due to the influence of the time, location, wind speed, wind direction, and humidity. This study aims to find out the results of measuring fine dust in an actual construction site and inferring the changes.
김영현(Young Hyun Kim),김선일(Sun Il Kim),김진환(Jin Hwan Kim) 한국공업화학회 2002 공업화학 Vol.13 No.3
Polysiloxane(PSX)의 함량이 다른 poly(siloxane-imide)(PSI) 공중합체막을 제조하고 막의 구조적인 특성과 기체의 투과특성을 연구하였다. PSI막은 1,2,4,5-benzenetetracarboxylic dianhydride(PMDA)와 4.4`- oxydianiline(ODA) 및 PSX를 반응시켜 제조하였다. PSI 막은 우수한 열적 안정성을 가졌으며, PSX의 함량이 증가할수록 사슬간의 평균거리인 d-spacing값이 증가하였다. 기체의 투과도는 PSX함량이 증가할수록 증가하였으며, H_2>CO_2>O_2>N_2>CH_4의 순서로 감소하였다. 투과도의 증가에도 불구하고 H_2/CH_4, O_2/N_2 및 N_2/CH_4에 대한 선택도는 거의 일정하였으며, CO_2/CH_4의 선택도는 오히려 증가하였다. Poly(siloxane-imide)(PSI) copolymer membranes with various poly siloxane(PSX) contents were prepared and their structural characteristics and gas permeation properties of H_2, CO_2, O_2, N_2 and CH_4 were studied. PSI membranes were obtained by the reaction of 1,2,4,5-benzenetetracarboxylic dianhydride(PMDA), 4,4`-oxydianiline(ODA) and amine-terminated PSX. The PSI membranes showed high thermal stability and their d-spacing value increased with increasing PSX content. The gas permeability coefficients through PSI membranes increased with increasing PSX content and decreased in the order of H_2>CO_2>O_2>N_2>CH_4. In spite of the permeability enhancement, the permselectivity of CO_2/CH_4 increased and even those of H_2/CH_4, O_2/N_2, N_2/CH_4 were nearly constant. It was found that the permeability and permselectivity could be controlled by the PSX content.