경량 비디오 코덱을 위한 3D 웨이블릿 코딩 기법

이승원,김성민,박성호,정기동,Lee, Seung-Won,Kim, Sung-Min,Park, Seong-Ho,Chung, Ki-Dong 한국정보처리학회 2004 정보처리학회논문지B Vol.11 No.2

비디오 압축에 사용되는 움직임 예측은 많은 계산과정을 요구하기 때문에 전체적인 부호기 복잡도를 높이는 단점을 지닌다. 이러한 부호기의 복잡도를 줄이기 위해 3D-WT과 같은 움직임 예측을 사용하지 않는 연구들이 소개되고 있다. 하지만, 기존의 3D-WT 기법들은 부호화를 위한 과도한 메모리 요구사항과 복호를 위한 수신 측의 지연시간이 가장 큰 단점으로 지적되었다. 본 논문에서는 수정된 Haar wavelet filter와 개선된 부호화 알고리즘을 통해서 메모리 사용량과 재생을 위한 지연시간을 최소로 하는 확장 가능한 3D-WT 기법인 FS(Fast playable and Scalable) 3D-WT를 소개한다. 3D-WT 중 가장 개선된 형태인 3D-V 기법과의 실험 결과 3D-V와 거의 비슷한 계산 처리 시간으로 높은 압축률과 수신 측에서의 짧은 지연시간을 보였다. It is a weak point of the motion estimation technique for video compression that the predicted video encoding algorithm requires higher-order computational complexity. To reduce the computational complexity of encoding algorithms, researchers introduced techniques such as 3D-WT that don't require motion prediction. One of the weakest points of previous 3D-WT studies is that they require too much memory for encoding and too long delay for decoding. In this paper, we propose a technique called `FS (Fast playable and Scalable) 3D-WT' This technique uses a modified Haar wavelet transform algorithm and employs improved encoding algorithm for lower memory and shorter delay requirement. We have executed some tests to compare performance of FS 3D-WT and 3D-V. FS 3D-WT has exhibited the same high compression rate and the same short processing delay as 3D-V has.

시멘트콘크리트 포장구조계의 층별물성 및 응력추정에 관한 연구

이승원,김문겸,김수일,황학주,Lee, Seong Won,Kim, Moon Kyum,Kim, Soo Il,Hwang, Hak Joo 대한토목학회 1990 대한토목학회논문집 Vol.10 No.1

본 연구에서는 FWD시험의 표면 처짐곡선으로부터 시멘트 콘크리트 포장구조체의 물성 및 응력을 추정할 수 있는 역산반복기법을 개발하였다. 국내에 가설되어 있는 시멘트 콘크리트 포장구조체에 대한 요소설계를 실시하여 구한 모형들에 대하여 유한요소와 층탄성이론을 조합한 해석방법을 적용하여 처짐 특성 및 탄성 계수 추정식을 구하였다. 추정식에 의한 각 층의 탄성계수를 초기 탄성계수로 하고, 탄성계수 변화율과 처침 변화율의 관계를 이용하여 반복역산시 탄성계수 보정에 사용하였다. 각 고속도로 노선별로 효율적인 역산반복기법을 전산화하였으며, 수치모델을 통하여 신뢰성 및 타당성을 검증하였다. An inverse self-iterative procedure is developed to estimate layer moduli and stresses in cement concrete pavement systems from the falling weight deflectometer deflection basins. The existing concrete pavement highways are analyzed using coupled analysis procedure of finite element and layer elastic theory for models obtained through factorial design, from which the characteristics of deflection basins are studied and the empirical equations are proposed for the estimation of layer moduli. The empirical equations are used to assume initial moduli, and the relations between the rate of change of moduli and deflections are used in the self-iterative procedure to ensure accuracy of moduli. The developed computer program of this procedure is verified through various numerical model tests.

용융 Fe 및 Fe-C 합금에서의 질소의 용해

이승원,양훈영 ( Seong Won Lee,Hoon Yung Yang ) 한국주조공학회 1984 한국주조공학회지 Vol.4 No.4

Nitrogen solubility in liquid Fe and Fe-C alloys has been measured by the levitation melting method under 1 atm N₂pressure. Experiments were carried out at the temperature range of 1774 - 2097˚K and carbon content of 0 - 5.06wt%. The nitrogen solubilities measured in pure Fe and Fe-C alloys were log (wt%N)_(Fe) = -424/T - 1.129 and log (wt%N)_(Fe-C)= -[424/T+1.129+(%C)/19.14{5447/T-0.612}+(%C)^2/19.14 2478/T- 1.265]

이동환경에서 연속미디어 서비스를 위한 협력적인 프록시 캐슁

이승원,이화세,박성호,정기동,Lee Seung-Won,Lee Hwa-Sei,Park Seong-Ho,Chung Ki-Dong 한국정보처리학회 2004 정보처리학회논문지B Vol.11 No.6

본 연구는 이동환경에서 연속 미디어 객체에 대한 사용자 요구들에 대하여 효율적으로 자원을 관리하기 위하여, 사용자의 이동성 정보를 반영하는 협력적 프록시 캐슁 정책을 제안한다. 제안된 정책은 담당영역 내에서 사용자의 요구들을 참조함으로서 캐슁하는 기존의 프록시 캐슁정책과는 다르게 인접한 영역의 많은 사용자 요구 정보들을 이용하여 캐슁 객체를 선택함으로써 이동환경에서 발생하는 사용자들의 랜덤 액세스 요구들을 충분히 반영할 수 있도록 한다. 그리고 제안된 캐슁 정책을 위해서 각 프록시에서 발생한 요구 정보의 가중치와 재생량을 기반으로 하는 재배치 기법을 제안한다. 그래서 객체단위와 세그먼트 단위로 재배치 기법을 수행하여 결과를 평가하고 캐슁 정책의 성능을 분석하였다. 그 결과, 이동환경에서 적절한 사용자의 이동성 비율이 협력적 캐슁의 성능에 영향을 미치는 중요한 요인이 된다는 것을 알았다. This paper proposes a user's mobility based cooperative proxy caching policy for effective resource management of continuous media objects in mobile environments. This policy is different from the existing proxy caching policies in terms of how to exploit users' mobility. In other words, existing caching policies work based on the information about objects by referring to user's requests within a specified domain whereas the proposed caching policy runs by utilizing a number of user's requests across several domains. So, the proposed policy is applicable to random requests in mobile environments Moreover, we also propose a replacement policy based on weights and playback time. To check the efficiency of the proposed caching policy, the proposed replacement policy is run with different size of caching unit object or segment. The result of performance analyze tells what a ratio of user's mobility is are major factors for the efficient operation of the cooperative caching.

시멘트 콘크리트 포장구조계의 구조거동의 해석방법에 관한 비교연구

이승원,김문겸,황학주,Lee, Seong Won,Kim, Moon Kyum,Hwang, Hak Joo 대한토목학회 1989 대한토목학회논문집 Vol.9 No.4

본 연구에서는 비파시 시험 및 구조해석에 의한 포장구조계상태의 판단 및 유지관리시스템에 이용하고자 포장구조계의 여러 해석방법을 구조거동면에서 분석하였다. 해석대상으로는 4층 구조체로 된 포장구조계를 택하여 3차원 유한요소, 평면변형률 유한요소, 판과 Winkler 기초, 판과 Burmister 기초로 해석을 실시하였다. 각 해석 방법에 따른 수치해석 결과는 변위와 응력을 기준으로 비교 분석하였다. 각 해석 방법의 장단점을 분석한 후 그 결과 Burmister 기초해석방법이 수치해석이 용이하며 콘크리트 포장구조체의 구조적인 거동과 가장 비슷하므로 포장구조체의 변위 및 응력해석에 가장 효용적인 방법이라는 결론을 얻었다. Various analytical procedures for the structural behavior of concrete pavement system are studied in order to identify a suitable method which will be incorperated in the pavement management system using nondestructive test and mechanistic evaluation. A typical four layered system is adopted and analyzed using 3 dimensional finite elements, plane strain elements, plates with Winkler foundation, and plates with Burmister foundation. Numerical analysis results of various structural analysis procedures are compared and analized based on displacements and stresses. It is concluded, after analysis of merits and demetits of the procedures, that Burmister foundation analysis procedure is the most sui-table procedure for implementation for the analysis of stresses and displacements because of its accuracy and simplicity.

CRITICAL HEAT FLUX ENHANCEMENT IN FLOW BOILING OF Al2O3 AND SiC NANOFLUIDS UNDER LOW PRESSURE AND LOW FLOW CONDITIONS

이승원,SEONG DAE PARK,SARAH KANG,SEONG MAN KIM,HAN SEO,DONG WON LEE,방인철 한국원자력학회 2012 Nuclear Engineering and Technology Vol.44 No.4

Critical heat flux (CHF) is the thermal limit of a phenomenon in which a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water), which suddenly decreases the heat transfer efficiency, thus causing localized overheating of the heating surface. The enhancement of CHF can increase the safety margins and allow operation at higher heat fluxes; thus, it can increase the economy. A very interesting characteristic of nanofluids is their ability to significantly enhance the CHF. Nanofluids are nanotechnology-based colloidal dispersions engineered through the stable suspension of nanoparticles. All experiments were performed in round tubes with an inner diameter of 0.01041 m and a length of 0.5 m under low pressure and low flow (LPLF) conditions at a fixed inlet temperature using water, 0.01 vol.% Al2O3/water nanofluid, and SiC/water nanofluid. It was found that the CHF of the nanofluids was enhanced and the CHF of the SiC/water nanofluid was more enhanced than that of the Al2O3/water nanofluid.

건조방법에 따른 하수슬러지 건조속도 비교 및 경제성 평가

박성훈 ( Seong-hun Park ),김한석 ( Han-seok Kim ),이승원 ( Seung-won Lee ) 한국환경기술학회 2021 한국환경기술학회지 Vol.22 No.3

In this study investigated the effect of the chemical injection ratio on the drying rate of sewage sludge. Then the economic efficiency was evaluated by comparing the results of the NIR(near infrared ray) and microwave drying rate test. The near infrared ray device showed drying speed of 31.9 %, 28.1 %, and 27.1 % at polymer dose ratio of 8 %, 10 %, and 12 %, respectively. Compared to 8 % polymer dose ratio, polymer dose ratio of 10 % and 12 % showed differences of 8.0 % and 13.6 % respectively, suggesting that drying efficiency decreased as polymer dose ratio increased. The microwave device showed drying speed of 26.2 %, 24.3 %, 21.3 % at polymer dose ratio of 8 %, 10 %, and 12 %, respectively. Compared to 8 % polymer dose ratio, polymer dose ratio of 10 % and 12 % showed differences of 5.2 % and 13.4 % respectively, suggesting that drying efficiency decreased as polymer dose ratio increased. Drying evaluation estimated the treatment cost of near infrared ray device at optimal dose ratio(6 %) was 35,591 won/ton while that of actual dose ratio(8 %) was 38,928 won/ton. Drying evaluation estimated treatment cost of microwave device at optimal polymer dose ratio(6 %) and at 8 % to be 16,683 won/ton and 18,352 won/ton, respectively.

다양한 시험기법을 이용한 반복하중을 받는 철도노반의 변형특성 평가

이승원(Lee Seong-Won),권기철(Kweon Gi-Chul),정재민(Chung Jae-Min),황택진(Hwang Taik-Jean) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-

It is very important to evaluate the reliable deformational characteristics of soils not only in the analysis of geotechnical structures under working stress conditions as foundation in railroad or road system but also for the soil dynamic problems. Different testing techniques are likely to have different testing conditions as strain amplitude, stress level, loading frequency and number of loading cycles. The deformational characteristics of soils can be affected by these variables. In this paper, the effects on modulus of soils subjected to cyclic load were investigated. For the evaluation of deformational characteristics of soils subjected cyclic load, various testing such as TS, RC, TX, and FFRC tests were performed. It was shown that the modulus evaluated by various testing methods are comparable to each other fairly well when the effects of these factors were properly taken into account. For reliable evaluation, therefore, those effects on the modulus need to be considered, and measured values should be effectively adjusted to actual conditions where the soil is working.

철도교 교량보강공사에 따른 실시간 궤도계측사례 분석

이승원(Seong-Won Lee),김대성(Dae-Sung Kim),이근호(Keun-Ho Lee),유지형(Ji-Hyeung Yoo) 한국철도학회 2020 한국철도학회 학술발표대회논문집 Vol.2020 No.7

철도구조물의 안전관리를 위한 MEMS센서의 온도변화에 따른 변위 계측

이승원(Seong Won Lee),이근호(Keun Ho Lee),유지형(Ji Hyeung Yoo),김대성(Dae Sung Kim) 한국철도학회 2019 한국철도학회 학술발표대회논문집 Vol.2019 No.11