• Title/Summary/Keyword: stream side

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A Study on Inversion at Leeward Side of High-rise Building in Winter (동절기 고층건물 풍하면의 기온역전에 관한 연구)

  • Zheng, Hai-Yan;Jin, Wen-Cheng;Oh, Sung-Nam;Lee, Kyoo-Seock
    • Journal of Environmental Impact Assessment
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    • v.19 no.6
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    • pp.583-590
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    • 2010
  • To determine nocturnal inversion characteristics at the leeward side of high-rise building, air temperature data were observed at 10 minute interval from February 22, 2010 to April 15, 2010. The observed data were compared, analyzed and examined to illustrate air temperature differences between the roof (XAR) and surface (XAG) of X apartment. The wind speed, wind direction and precipitation data were also observed at XAR and YJL (Yangjae Stream) sites at the same time. After the analysis, the maximum nocturnal inversion was observed by $4.0^{\circ}C$ at 3:40, 3:50, 4:10 on February 24th 2010, at that time the weather condition was clear and weak wind. Air temperature inversions at the leeward side of high-rise building were observed on whole day in wintertime and air temperature inversion intensity was also higher than other nearby area (SMG).

Application of Stimuli-responsive Chitosan Micelles for Improved Therapeutic Efficiency of Anticancer Agents (항암제의 치료 효율성을 높이기 위한 다양한 자극 응답성 물질이 개질된 키토산 마이셀의 응용성 고찰)

  • Jeong, Gyeong-Won;Park, Jun-Kyu;Nah, Jae-Woon
    • Applied Chemistry for Engineering
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    • v.29 no.2
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    • pp.147-154
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    • 2018
  • Currently, to overcome low therapeutic efficiencies and side effects of anticancer agents, the study of drug carrier based on polymers have been consistently investigated. Although the traditional drug carrier based on polymers displayed an excellent result and significant progress, there has been a problem with the side effect and low therapeutic efficiency because of the premature drug release before reached to the targeted region by the low stability in blood stream and sustained drug release. In this review article, to improve the problem of inefficient drug release, methods were suggested, which can maximize the therapeutic efficiency by increasing the stability in the blood stream and triggering drug release at the target site by introducing a stimuli-responsive substance to the non-toxic and biocompatible natural polymer chitosan.

Numerical Analysis of Flow and Bed Changes due to Tributary Inflow Variation at the Confluence of the Namhan River and the Geumdang Stream (남한강과 금당천 합류부 구간에서의 지류 유입유량 변화에 따른 흐름특성 및 하상변동 수치모의)

  • Ji, Un;Jang, Eun Kyung
    • Journal of Korea Water Resources Association
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    • v.47 no.11
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    • pp.1027-1037
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    • 2014
  • Flow and bed changes due to tributary inflow variation at the confluence of the Namhan River and the Geumdang Stream were analyzed in this study using a two-dimensional numerical model. As a result of the numerical analysis, the velocity downstream of the confluence was greater than the velocity upstream of the confluence in the main channel regardless of the magnitude of tributary inflow. However, as tributary discharge increased, the channel erosion was accelerated and the dry area was produced at the tributary. Due to the bed erosion at the tributary, sediment transport was increased and the eroded sediments were deposited in the confluence area. The deposition in the confluence area changed the flow direction at the main channel to the left side and the localized flow eroded the channel bed at the left side. Therefore, it is expected that bank failure due to continuous bed degradation is possible in this area.

Development of the Estimation Model on Daily Pollutant Loads for the Watersheds in the Nakdong River Basin I. Correction and Verification for the Model (낙동강 유역에 대한 일별 유달부하량 산정모델개발 I. 모델식의 보정 및 검증)

  • Yoon, Young-Sam;Kim, Moon-Soo;Yu, Jae-Jung;Lee, Hae-Jin;Lee, Jun-Bae;Yang, Sang-Yong
    • Journal of Environmental Science International
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    • v.16 no.2
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    • pp.203-210
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    • 2007
  • The delivery load data obtained from Nakdong river basin are used for developing the model estimating the daily delivery load on the main side streams of Nakdong River. The developed model assesses the daily contamination loads of the main thirteen side streams that contribute to the main stream of Nakdong river. It is developed that the model using the simplified equation that can estimate the daily delivery loads on the side main streams of Nakdong river for a period of having no data of the water quality and flow. The developed model for estimating the daily delivery loads from the main side streams in Nakdong river basin on each item such as BOD, TN, and TP is expressed as Daily delivery load ($\frac{kg}{day}$) = Production load $(\frac{kg}{day}){\times}(1-{\alpha}){\times}(\frac{daily\;runoff}{average\;runoff\;per\;year}){\gamma}$. The estimated values obtained by using the model are almost fit to the calculated values (real data) that have been acquired from the thirteen main side streams in Nakdong river basin. The correlation coefficient values, R, that indicate the correlation between the estimated and the calculated show over 0.7 that mean the estimated values from the used model are adapted to the real data except TN values of Nam-river, Hwang-river, Gam-river, We-river. Especially, the correlation of TP values between the estimated and the calculated implies quite a creditable data to use.

Gradation and Transport Characteristics of Bed Materials in Pool-Riffle Sequence in the Gap Stream, Korea (갑천의 웅덩이-여울 연속구조에서 하상토의 입도 및 이동 특성)

  • Choi, Sung-Uk;Bae, Hye-Deuk
    • Journal of Korea Water Resources Association
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    • v.44 no.1
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    • pp.65-72
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    • 2011
  • Natural streams meander, forming pools at the outer part of bend and riffles at the crossing. Pools are deep at a lower flow velocity, and riffles are shallow at a higher flow velocity. Attentions are being paid to pool-riffle sequences in meandering streams because pool-riffle sequences tend to increase biodiversity of the stream ecosystem. This study investigates the characteristics of distribution of bed sediment particles in the upstream reach of the Gap Stream, which is a tributary of the Geum River in Korea. The upstream part of the Gap Stream, the study reach, is a gravel-bed stream, showing a pool and three riffles due to meandering. The reach also includes pools at the upstream and downstream parts of the weir. The characteristics of bed sediment particles sampled at the wetland and in the side channel are studied, revealing that the median particle diameter in the riffle is about four times larger than that in the pool. In addition, flow simulations are carried out for ordinary discharge and design flood, and such parameters important to sediment transport as velocity, shear stress, dimensionless shear stress (or Shields number), and dimensionless shear velocity are provided to see the mobility of sediment particles in the pool-riffle sequence.

The Change of Riverside Vegetation by Construction of Ecological Stream in Suwoncheon, Gyeonggi Province (경기도 수원천 생태하천 복원사업 이후 식생변화 연구)

  • Choe, Il-Hong;Han, Bong-Ho;Ki, Kyong-Seok
    • Korean Journal of Environment and Ecology
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    • v.24 no.6
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    • pp.723-734
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    • 2010
  • This study aims to analyze the change in vegetation for 10 years after the construction, targeting Suwoncheon, the first domestic ecological stream construction project. As for the section for the study, the section from Gyeonggi bridge to Youngyeon bridge, the first restoration project section, was targeted. The research districts consisted of 3 districts depending on topographical structure. Investigation check cosisted of cross-sectional topographical structure, vegetation status and the structure of herbaceous plant community. As for the cross-sectional topographical structure of the stream, the width of entire stream was 26.5~28.0m and water channel is 10~20m. The area for hydrophilic space was securing spacious riverside. Upper stream of reservoir beam was shallow and slow in reservoir area above weir. Lower stream of reservoir beam, the width of water channel was narrow and ripples were formed. Among species, 9 plants were planted and 6 species plants including Salix gracilistyla, Phragmites communis and Zoysia japonica were planted at the time of construction. In the water side, there were 2 species, such as Zoysia japonica and Trifolium repens, etc, still remained after seeding at the time of constrcution. The planted plants which were observed through this investigation, were 2 species such as Festuca arundinacea and Dactylis glomerata. Apart from the planted plants, arid climate herbaceous plant such as Setaria viridis and Artemisia princeps var. orientalis formed power and the naturalized species variously emerged in 15 species. For revetment, natural stone stacking method was condicted and Salix gracilistyla, Aceriphyllum rossii, etc were planted. But all the planted plants disappeared and now it was covered with Equisetum arvense and Humulus japonicus. It was because that the base for growth and development of the plants was not constructed at the time of restoration in a way of attaching natural stones onto the concrete base. In the water channel, various wetland species including Typha orientalis, Acorus calamus var. angustatus and Phragmites communis, etc, were planted but only Salix gracilistyla, Phragmites communis and Zizania latifolia remained. As for species of the autochthons, Persicaria thunbergii was dominant. In the lower stream of reservoir beam, Humulus japonicus formed forces. In the hydrophilic space, it was necessary to direct the landscape of in-stream vegetation in cosideration of users. For this, planting Miscanthus sacchariflorus in a community was proposed. In the upper stream of reservoir beam, suplementary screen seeding was necessary so that Zizania latifolia, Typha orientalis and Phragmites communis can fit the depth of water. In the Lower stream of reservoir beam, it was necessary to constantly manage Humulus japonicus so that the wetland autochthons species, such as Phragmites communis and Persicaria thunbergii can establish power more stably.

An Experimental Study of Heat Transfer Characteristics on the Electronic Module Arrangement (전자모듈의 배열에 따른 열전달특성의 실험적 연구)

  • Lee, Dae-Hee;Lee, Dae-Keun;Cha, Yoon-Seok;Lee, Jun-Sik
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2420-2425
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    • 2007
  • Heat transfer from three-dimensional heat-generating modules was investigated. A simulated electronic module in an array configured with dummy module elements was used to measure the average heat transfer coefficients. Various module arrangements were tested using module spacings of 0.85 and 1.15 cm for six Reynolds numbers ranging from 500 to 975. The results show that a module placed in-line with and upstream of a heated module results in the heat transfer enhancement due to a high level in turbulence prompted by upstream modules. The highest enhancement occurs when the separation distance between modules is close to the module length in the flow direction. Flow visualization reveals laminar flow on the front of the first module, slow recirculation regions on the sides parallel to the air stream, and turbulence on the back side. It appears that the first module serves to trip the air stream and produce a high level of turbulence, which enhances the heat transfer rate downstream.

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Applying the Polder Levee of the Stream Specific by Using Hydordynamic Model (수치해석을 이용한 윤중제 흐름특성해석 적용성)

  • Choi, Han-Kuy;Kim, Jang-Uk;Baek, Hyo-Sun
    • Journal of Industrial Technology
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    • v.28 no.B
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    • pp.193-198
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    • 2008
  • When the existing polder levee was constructed, the river's numerical analysis decided the bank raise by applying the planned flood stage or by using the result from the sectional 1st dimensional numerical analysis. But, it was presented that there is a limitation in the 1st dimensional value analysis when the structure like the polder levee obstructs the special shaped running water flow. Therefore, in order to verify the numerical value applicability when the polder levee is constructed, this report compared each other through the 1st and 2nd dimensional numerical analysis and the mathematical principle model laboratory. In case of the polder levee construction through the numerical analysis and the mathematical principle model laboratory, it was decided that there was no big problem in the 1st dimensional numerical analysis applied design, considering the uncertainty of mathematical principle analysis though the first dimensional numerical analysis was calculated a little bigger than the second. But, after construction, it was found that the water level deviation of the 1st, 2nd occurred biggest at the place where the flow was divided into two. Also, as a result of comparing the 1st, 2nd dimensional numerical analysis with the mathematical principle model laboratory, it was confirmed that the 1st numerical analysis applied design decreased the modal safety largely, as the left side water level was calculated smaller more than 0.5m in case of the 1st dimensional numerical analysis.

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Implementation of Parallel Cyclic Redundancy Check Code Encoder and Syndrome Calculator (병렬 CRC코드 생성기 및 Syndrome 계산기의 구현)

  • 김영섭;최송인;박홍식;김재균
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.1
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    • pp.83-91
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    • 1993
  • In the digital transmission system, cyclic redundancy check(CRC) code is widely used because it is easy to be implemented and has good performance in error detection. CRC code generator consists of several shift registers and modulo 2 adders. After manipulation of input data stream in the encoder, the remaining value of shift registers becomes CRC code. At the receiving side, error can be detected and corrected by CRC codes immediately transmitted after data stream. But, in the high speed system such as an A TM switch, it is difficult to implement the serial CRC encoder because of speed limitation of available semiconductor devices. In this paper, we propose the efficient parallel CRC encoder and syndrome calculator to solve the speed problem in implementing these functions using the existing semiconductor technology.

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Unequal Error Protection and Error Concealment Schemes for the Transmission of H.263 Video over Mobile Channels

  • Hong, Won-Gi;Ko, Sung-Jea
    • Journal of IKEEE
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    • v.2 no.2 s.3
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    • pp.285-293
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    • 1998
  • This paper presents unequal error protection and error concealment techniques far robust H.263 video transmission over mobile channels. The proposed error protection scheme has three major features. First, it has the capability of preventing the loss of synchronization information in H.263 video stream as much as possible that the H.263 decoder can resynchronize at the next decoding point, if errors are occurred. Secondly, it employs an unequal error protection scheme to support variable coding rates using rate compatible punctured convolutional (RCPC) codes, dividing the encoded stream into two classes. Finally, a macroblock-interleaving scheme is employed in order to minimize the corruption of consecutive macroblocks due to burst errors, which can make a proper condition for error concealment. In addition, to minimize the spatial error propagations due to the variable length codes, a fast resynchronization scheme at the group of block layer is developed for recovering subsequent error-free macroblocks following the damaged macroblock. futhermore, error concealment techniques based on both side match criterion and overlapped block motion compensation (OBMC) are employed at the source decoder so that it can not only recover the lost macroblock more accurately, but also reduce blocking artifacts. Experimental results show that the proposed scheme can be an effective error protection scheme since proper video quality can be maintained under various channel bit error rates.

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