• Title/Summary/Keyword: Stream order

Search Result 1,276, Processing Time 0.026 seconds

HTTP Adaptive Streaming Method for Service-compatible 3D Contents Based on MPEG DASH (MPEG DASH 기반 service-compatible 3D 콘텐츠 대상 HTTP adaptive streaming 적용방안)

  • Park, Gi-Jun;Lee, Gil-Bok;Lee, Jang-Won;Kim, Kyu-Heon
    • Journal of Broadcast Engineering
    • /
    • v.17 no.2
    • /
    • pp.207-222
    • /
    • 2012
  • Recently, many consumer electronics manufacturers have produced 3D devices such as 3DTVs and 3D monitors as interests in a stereoscopic video service are getting increased. However, most of 3D services are focused on local storage or bandwidth guaranteed service since 3D stereoscopic video service require bandwidth more stable and larger. This property causes difficulties in seamless stereoscopic video streaming services under IP based open network environment that cannot guarantee quality of services. In order to achieve a seamless video streaming service the international standard organization MPEG (Moving Pictures Experts Group) has developed the adaptive HTTP streaming technology called as DASH (Dynamic Adaptive Streaming over HTTP). However, the DASH doesn't have obvious scheme which can express the two elementary video streams based service-compatible stereoscopic contents in one segment. Therefore, this paper proposes a scheme of efficient 3D adaptive streaming service based on the DASH, which covers not only frame-packing stereoscopic contents but also service-compatible ones. The 3D adaptive HTTP streaming scheme introduced in this paper is able to provide 3D contents with various qualities to user and also has benefit that single 3D content can be applied to a variety of devices.

High-Altitude Environment Simulation of Space Launch Vehicle in a Ground-Test Facility (지상시험장비를 통한 우주발사체 고공환경모사 기법 연구)

  • Lee, Sungmin;Oh, Bum-Seok;Kim, YoungJun;Park, Gisu
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.45 no.11
    • /
    • pp.914-921
    • /
    • 2017
  • The experimental research on a high-altitude environment simulation of space launch vehicle is important for securing independent technologies with launching space vehicles and completing missions. This study selected an altitude of 65 km for the experiment environment where it exceeded Mach number of 6 after the launch of Korean Space Launch Vehicle(KSLV-II). Shock tunnel was used to replicate the flight condition. After flow establishment, in order to confirm aerodynamic characteristics and normal and oblique shockwaves, the flow verification was carried out by measuring stagnation pressure and heat flux of a forebody model, and shockwave stand-off distance of a hemispherical model. In addition, a shock-free technique to recover free-stream condition has been developed and verified. From the results of the three verification tests, it was confirmed that the flow was replicated with the error of about ${\pm}3%$. The error between the slope angle of inclined shockwave of the scaled down transition section model using the shock-free shape and the slope angle of the horizontal plate model, and between the theoretical and the experimental value of the static pressure of the model were confirmed to be 2% and 1%, respectively. As a result, the efficiency of the shockwave cancellation technique has been verified.

Epidemiological Survey of Paragonimus westermani in Ulchin County, Kyoungpook Province, Korea (경북 울진등에서의 폐흡충 역학적 조사)

  • Ju, Jong-Yun;Park, Yeong-Chun;An, Seong-Hun
    • Parasites, Hosts and Diseases
    • /
    • v.23 no.1
    • /
    • pp.102-110
    • /
    • 1985
  • In order to determine the epidemiological pattern of the Paragonimus westermani, the infestation rates for the cercarial and metacer-carial larvae of digenetic trematodes in the snail and crayfish hosts, and the prevalence of Paragonimus westermani among the residents in the vicinity of the stream Namdae, Wyangpi, and Kwang, in the Ulchin county, Kyungpook Province were studied from March to October in 1984. The population density of the snails per square meter of the habitats ranged from 5 to 25, with an average of 15. Among the seven habitats, one, Ducheon, had snails infested with the cercariae of Paragonimus westermani, and the proportion of infested snails was very low, the average being 0.152 per thousand. Of six hundred and four crayfish examined, 113 or 18.7 per cent harboured the encysted larvae of Paragonimus westermani. A high infestation rate for the metacercariae in the crayfish was found in two habitats; 39.0 per cent in the Ducheon and 21. 6 per cent m the Sokwang. The prevalence of Paragonimus westermani among the residents in Ulchin county was relatively high, 25.8 per cent by the Paragonimus intradermal tests, and the difference in the rate of infection between males and females was found to be significant (t>2). The results obtained in this study indicate that endemic foci of Paragonimus westermani exist in Ulchin county and the prevalence of this lung fluke among the residents is relatively high.

  • PDF

Drag Coefficient Variations of an Oscillating NACA 0012 Airfoil (진동하는 NACA 0012 에어포일에서의 항력계수 변화)

  • Kim, Dong-Ha;Chang, Jo-Won;Kim, Hak-Bong;Jeon, Chang-Soo
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.36 no.2
    • /
    • pp.137-145
    • /
    • 2008
  • An experimental study was performed in order to investigate the influence of Reynolds number on the drag coefficient variations of an oscillating airfoil. A NACA 0012 airfoil was sinusoidally pitched at the quarter chord point with an oscillating amplitude of ${\pm}6^{\circ}$. The free-stream velocities were 1.98, 2.83 and 4.03 m/s and the corresponding chord Reynolds numbers were $2.3{\times}10^4$, $3.3{\times}10^4$ and $4.8{\times}10^4$, respectively. The drag coefficient was calculated from the ensemble average velocity measured by an X-type hot-wire probe(X-type, 55R51) in the near-wakes region. In the case of Re=$2.3{\times}10^4$, variation of drag coefficient shows a negative damping (counter-clockwise variation), which implies an unstable state which could be excited by aerodynamic force, whereas the drag coefficient represents the positive damping (clockwise variation) as the Reynolds number increases from Re=$3.3{\times}10^4$ to $4.8{\times}10^4$. Hence, the drag coefficient variations show significant differences between Re=$2.3{\times}10^4$ and $4.8{\times}10^4$이다.

A Case Study for Simulation of a Debris Flow with DEBRIS-2D at Inje, Korea (DEBRIS-2D를 이용한 인제지역 토석류 산사태 거동모사 사례 연구)

  • Chae, Byung-Gon;Liu, Ko-Fei;Kim, Man-Il
    • The Journal of Engineering Geology
    • /
    • v.20 no.3
    • /
    • pp.231-242
    • /
    • 2010
  • In order to assess applicability of debris flow simulation on natural terrain in Korea, this study introduced the DEBRIS-2D program which had been developed by Liu and Huang (2006). For simulation of large debris flows composed of fine and coarse materials, DEBRIS-2D was developed using the constitutive relation proposed by Julien and Lan (1991). Based on the theory of DEBRIS-2D, this study selected a valley where a large debris flow was occurred on July 16th, 2006 at Deoksanri, Inje county, Korea. The simulation results show that all mass were already flowed into the stream at 10 minutes after starting. In 10minutes, the debris flow reached the first geological turn and an open area, resulting in slow velocity and changing its flow direction. After that, debris flow started accelerating again and it reached the village after 40 minutes. The maximum velocity is rather low between 1 m/sec and 2 m/sec. This is the reason why debris flow took 50 minutes to reach the village. The depth change of debris flow shows enormous effect of the valley shape. The simulated result is very similar to what happened in the field. It means that DEBRIS-2D program can be applied to the geologic and topographic conditions in Korea without large modification of analysis algorithm. However, it is necessary to determine optimal reference values of Korean geologic and topographic properties for more reliable simulation of debris flows.

Grid Cell Analysis using Species Diversity Index of Birds in the Northern Area of Yeongjong Island, Incheon, Korea (영종도 북부지역의 조류 종다양도를 이용한 격자별 공간 분석)

  • Kang, Jong-Hyun;Cho, Hang-Soo;Lee, Yun-Kyoung;Kim, Dong-Won;Kim, Chang-Hoe;Kim, Myungjin;Bae, Yang-Seop
    • Journal of Environmental Impact Assessment
    • /
    • v.21 no.5
    • /
    • pp.649-664
    • /
    • 2012
  • The grid cell analysis is used to select good sites as habitats at the region. The northern area of Yeongjong Island, Incheon has been disturbing by habitat loss due to human activities such as residential development, deforestation. In order to determine significant places as bird habitats and to select conservation areas at this island, the study area was divided into 70 grid cells($500{\times}500m$ each grid) and then each grid was ranked by spatial analysis using the species diversity index. Fieldwork was carried out in Spring and Autumn of 2010. To examine grid cells which were ranked high in both seasons in common, we used the average ranking value, combined data from two seasons. This area consists of mainly agricultural areas and forests(more than 68%) among eight habitat types: the agricultural land, forest, coast, lake, meadow, stream, city and other things. A total of 110 species was recorded: 4,183 birds of 102 species in Spring and 3,326 birds of 58 species in Autumn. In other words, the number of individuals and species was higher in Spring than in Autumn. Species diversity index presented the highest value at M8 grid cell in Spring(3.380) and at A4 gird cell in Autumn(2.736). In 18 of 22 grid cells where the average ranking value was higher than 3, the forest was distributed and in 4 grid cells, the coast and wetland were widely distributed, in which theses were located apart from human-associated disturbances such as construction works for a leisure complex. Our results present a new estimate method not only to minimize loss of bird habitats but also to conserve important habitats when the large-scale development takes place at particular region.

Multihoming Effect of SCTP Over TCP in the Link-down Environment (링크다운 환경에서 TCP어| 대한 SCTP의 멀티호밍 효과)

  • Choi, Yong-Woon;Lee, Yong-Jin
    • The Journal of the Korea Contents Association
    • /
    • v.9 no.8
    • /
    • pp.73-83
    • /
    • 2009
  • TCP(Transmission Control Protocol) is currently used connection-oriented protocol as a typical transport layer protocol in the Internet. However, it has deficiency not be able to communicate with other TCP entities when any link included in the path is down because of single-homing on single path. SCTP(Stream Control Transmission Protocol) suggested as the new transport layer protocol supports multi-homing feature, which provides several paths between source and destination. It can communicate with other SCTP entities using alternate path even when any link on the primary path is down. This paper aims to measure and analyze the multi-homing effect of SCTP over TCP in case of link-down using NS-2 simulator. We classify SCTP into $SCTP_{single-homing}$ and $SCTP_{multi-homing}$ because SCTP with single-homing can also be used like TCP. We measured throughput and bandwidth utilization varying link-down duration, bandwidth, and RTT(round trip time), Simulation results show that throughput of $SCTP_{multi-homing}$ is more than that of TCP by 18 % on average. It is also shown that $SCTP_{multi-homing}$ on varying RTT and bandwidth increases the throughput of TCP by 'l7% and 9% on average, respectively in the link-down environment. In above cases, more or less difference between $SCTP_{single-homing}$ and TCP on throughput and bandwidth utilization was found To summarize, multi-homing effect of SCTP over TCP on throughput is about 18 % on average in the link-down environment This experimental result can be used as the benchmark in order to estimate the multi-homing effect of SCTP over TCP when the link-down happens in the real Internet.

Sensitivity Analysis for Parameter of Rainfall-Runoff Model During High and Low Water Level Season on Ban River Basin (한강수계의 고수 및 저수기 유출모형 매개변수 민감도 분석)

  • Choo, Tai-Ho;Maeng, Seung-Jin;Ok, Chi-Youl;Song, Ki-Heon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.9 no.5
    • /
    • pp.1334-1343
    • /
    • 2008
  • Growing needs for efficient management of water resources urge the joint operation of dams and integrated management of whole basin. As one of the tools for supporting above tasks, this study aims to constitute a hydrologic model that can simulate the streamflow discharges at some control points located both upper and down stream of dams. One of the currently available models is being studied to be applied with a least effort in order to support the ongoing project of KWATER (Korea Water Resources Corporation), "Establishment of integrated operation scheme for the dams in Han River Basin". On this study, following works have been carried out : division of Han River Basin into 24 sub-basins, use of rainfall data of 151 stations to make spatial distribution of rainfall, selection of control points such as Soyanggang Dam, Chungju Dam, Chungju Release Control Dam, Heongseong Dam, Hwachun Dam, Chuncheon Dam, Uiam Dam, Cheongpyung Dam and Paldang Dam, selection of SSARR (Streamflow Synthesis and Reservoir Regulation) model as a hydrologic model, preparation of input data of SSARR model, sensitivity analysis of parameter using hydrologic data of 2002. The sensitivity analysis showed that soil moisture index versus runoff percent (SMI-ROP), baseflow infiltration index versus baseflow percent (BII-BFP) and surface-subsurface separation (S-SS) parameters are higher sensitive parameters to the simulation result.

A Study on Geomorphic Environments and Sediments of Channels at Naeseongcheon River in Gyeongpook Province (경북 내성천의 하도 지형 환경 및 퇴적물 분석)

  • Lee, Gwang-Ryul;Cho, Yong-Dong;Kim, Dae-Sik;Kim, Jung-Suk;Jeong, Woo-Heon;Cho, Hyun-Jin;Yun, Kuk-Hyun
    • Journal of the Korean association of regional geographers
    • /
    • v.16 no.2
    • /
    • pp.85-99
    • /
    • 2010
  • This study analyzes the geomorphic environments of river channels and properties of sediments in the Naeseong-River basin, a branch of Nakdong-River. While the area at NU1 located in the uppermost reaches indicates the landscapes with the gravel riverbeds, the sand riverbeds can be seen in the downstream of NU2 whose basin consists mostly of the granite regolith. The downstream of NU2 has the braided channels in the beds and this may be due to the large quantities of sand particles supply to the bed under the favorable geologic and geomorphic conditions, properties of river flowing within the floodplains less resistant to the erosion and great fluctuations of discharges. Whereas the river at NU2 may seem that sand particles are actively eroded during the high water-level periods, the particles may be actively deposited during the periods at NM2 and NL2. Moreover, in the reaches of NU2 to NM1 and NL1 to NL2, the mean grain sizes of sediments increase downstream suggesting the other supplies of coarse sediments from the lower order streams running the steep slopes because the river flows in the areas consisting of the metamorphic rocks rather than the granites and shows the properties of incised meander.

  • PDF

Adsorption of VOCs from Dry Cleaning (세탁소 배출 휘발성유기화합물의 흡착 제거 기술)

  • Lee, Seung-Jae;Moon, Seung-Hyun
    • Journal of Korean Society of Environmental Engineers
    • /
    • v.31 no.11
    • /
    • pp.1025-1032
    • /
    • 2009
  • This study investigated a possibility to develop an adsorption process for volatile organic compounds (VOCs) of the solvent emitted during dry cleaning. Pitch activated carbon fiber (ACF) was chosen as an adsorbent of VOCs, and an electric swing adsorption process was utilized for the reproduction of the adsorbent after the completion of VOCs adsorption. Effects of ACF types and several solvents such as trichloroethylene (TCE) and toluene were examined on breakthrough curves and amounts of adsorbed VOCs. ACF was pretreated under various conditions in order to enhance the amounts of the adsorbed VOCs. Temperatures and voltages were measured for the reproduction of the ACF after full adsorption. ACF having micropores exhibited high adsorption of TCE, and high surface area of ACF could increase the adsorption property of toluene. In general, ACF could adsorb 41~54% TCE of the adsorbent weight. The increase of inlet VOCs concentration significantly decreased the breakthrough time and slightly lowered the amounts of adsorbed VOCs. Thus, ACF could effectively adsorb VOCs in low concentration in the feed stream. ACF pretreated by heat under vacuum showed excellent toluene adsorption with controlling oxygen functional groups on the ACF surface, which revealed that vacant carbon site could be the adsorption point of toluene. Most adsorbed toluene was desorbed at $150^{\circ}C$.