• Title/Summary/Keyword: Velocity Data Reduction

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The Performance Assessment of a Straight-Type Five-Hole Pressure Probe Using a Zone Partition and Two-Dimensional Curve-Fitting Functions (영역분할과 2차원 커브피팅 함수들을 이용하는 직선형 5공 압력프로브의 성능 평가)

  • Kim, Jang-Kweon;Oh, Seok-Hyung
    • Journal of Power System Engineering
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    • v.18 no.1
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    • pp.22-31
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    • 2014
  • This paper introduced the new calibration algorithm of a straight-type five-hole pressure probe necessary for calculating three-dimensional flow velocity components. The new velocity data reduction method using both a commercial two-dimensional curve-fitting program and the zone partition method of a calibration map was firstly introduced in this study. This new calibration method can be applied up to the wide flow angle of ${\pm}80^{\circ}$ despite of using a five-hole pressure probe because this data reduction method showed a comparatively good performance in calculating yaw and pitch angles from the calibration map.

Intelligent Optimal Route Planning Based on Context Awareness (상황인식 기반 지능형 최적 경로계획)

  • Lee, Hyun-Jung;Chang, Yong-Sik
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.117-137
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    • 2009
  • Recently, intelligent traffic information systems have enabled people to forecast traffic conditions before hitting the road. These convenient systems operate on the basis of data reflecting current road and traffic conditions as well as distance-based data between locations. Thanks to the rapid development of ubiquitous computing, tremendous context data have become readily available making vehicle route planning easier than ever. Previous research in relation to optimization of vehicle route planning merely focused on finding the optimal distance between locations. Contexts reflecting the road and traffic conditions were then not seriously treated as a way to resolve the optimal routing problems based on distance-based route planning, because this kind of information does not have much significant impact on traffic routing until a a complex traffic situation arises. Further, it was also not easy to take into full account the traffic contexts for resolving optimal routing problems because predicting the dynamic traffic situations was regarded a daunting task. However, with rapid increase in traffic complexity the importance of developing contexts reflecting data related to moving costs has emerged. Hence, this research proposes a framework designed to resolve an optimal route planning problem by taking full account of additional moving cost such as road traffic cost and weather cost, among others. Recent technological development particularly in the ubiquitous computing environment has facilitated the collection of such data. This framework is based on the contexts of time, traffic, and environment, which addresses the following issues. First, we clarify and classify the diverse contexts that affect a vehicle's velocity and estimates the optimization of moving cost based on dynamic programming that accounts for the context cost according to the variance of contexts. Second, the velocity reduction rate is applied to find the optimal route (shortest path) using the context data on the current traffic condition. The velocity reduction rate infers to the degree of possible velocity including moving vehicles' considerable road and traffic contexts, indicating the statistical or experimental data. Knowledge generated in this papercan be referenced by several organizations which deal with road and traffic data. Third, in experimentation, we evaluate the effectiveness of the proposed context-based optimal route (shortest path) between locations by comparing it to the previously used distance-based shortest path. A vehicles' optimal route might change due to its diverse velocity caused by unexpected but potential dynamic situations depending on the road condition. This study includes such context variables as 'road congestion', 'work', 'accident', and 'weather' which can alter the traffic condition. The contexts can affect moving vehicle's velocity on the road. Since these context variables except for 'weather' are related to road conditions, relevant data were provided by the Korea Expressway Corporation. The 'weather'-related data were attained from the Korea Meteorological Administration. The aware contexts are classified contexts causing reduction of vehicles' velocity which determines the velocity reduction rate. To find the optimal route (shortest path), we introduced the velocity reduction rate in the context for calculating a vehicle's velocity reflecting composite contexts when one event synchronizes with another. We then proposed a context-based optimal route (shortest path) algorithm based on the dynamic programming. The algorithm is composed of three steps. In the first initialization step, departure and destination locations are given, and the path step is initialized as 0. In the second step, moving costs including composite contexts into account between locations on path are estimated using the velocity reduction rate by context as increasing path steps. In the third step, the optimal route (shortest path) is retrieved through back-tracking. In the provided research model, we designed a framework to account for context awareness, moving cost estimation (taking both composite and single contexts into account), and optimal route (shortest path) algorithm (based on dynamic programming). Through illustrative experimentation using the Wilcoxon signed rank test, we proved that context-based route planning is much more effective than distance-based route planning., In addition, we found that the optimal solution (shortest paths) through the distance-based route planning might not be optimized in real situation because road condition is very dynamic and unpredictable while affecting most vehicles' moving costs. For further study, while more information is needed for a more accurate estimation of moving vehicles' costs, this study still stands viable in the applications to reduce moving costs by effective route planning. For instance, it could be applied to deliverers' decision making to enhance their decision satisfaction when they meet unpredictable dynamic situations in moving vehicles on the road. Overall, we conclude that taking into account the contexts as a part of costs is a meaningful and sensible approach to in resolving the optimal route problem.

A Study on the Drag Reduction by Shear-thinning Fluid in Turbulent Flow Fields (난류유동장에서 Shear - thinning 유체에 의한 마찰저항 감소에 관한 연구)

  • 차경옥;김재근;오율권
    • Journal of Advanced Marine Engineering and Technology
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    • v.21 no.2
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    • pp.126-135
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    • 1997
  • Drag reduction in polymer solutions is the phenomenon where by extremely dilute solutions of high molecular weight polymers exhibit frictional resistance to flow much lower than the pure solvent. This effect, largely unexplained as yet, has attracted the attention of polymer scientists and fluid flow specialists. Although applications are beginning to appear, the principle interest to data has been in attempting to relate the effect to the fluid mechanics of turbulent flow. Drag reduction in two phase flow can be applied to the transport of crude oil, phase change system such as chemical reactor, and pool and boiling flow. But the research on drag reduction in two phase flow is not intensively investigated. Therefore, experimental investigations have been carried out to analyze the drag reduction produced by polymer addition in the single phase and two phase flow system. The objectives of the proposed investigation are primarily in identifying and developing high performance polymer additives for fluid transportations with the benefits of turbulent drag. Also we want to is to evaluate the drag reduction in horizontal flow by measuring pressure drop and mean velocity. Experimental results show higher drag reduction using co - polymer(A611P) then using polyacrylamide (PAAM) and faster degradation using PAAM than using A611P under the same superficial velocity.

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A New Calibration Algorithm of a Five-Hole Pressure Probe for Flow Velocity Measurement (유동속도계측을 위한 5공압력프로브의 새로운 교정 알고리듬)

  • Kim, J.K.;Oh, S.H.
    • Journal of Power System Engineering
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    • v.12 no.4
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    • pp.18-25
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    • 2008
  • This paper investigated the new calibration algorithm of a straight-type five-hole pressure probe necessary for calculating three-dimensional flow velocity components. The new data reduction method Includes a look-up, a geometry transformation such as the translation and reflection of nodes, and a binary search algorithm. This new calibration map was applied up to the application angle, ${\pm}55^{\circ}$ of a probe. As a result, this data reduction method showed a perfect performance without any kind of interpolation errors In calculating yaw and pitch angle from the calibration map.

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Application of the New Calibration Algorithm of a Straight-Type Five-Hole Pressure Probe (직선형 5공 압력프로브의 새로운 교정 알고리듬 적용)

  • Kim, Jang-Kweon;Oh, Seok-Hyung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.11
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    • pp.863-869
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    • 2008
  • This paper investigated the new calibration algorithm of a straight-type five-hole pressure probe for measuring three-dimensional flow velocity components. This new calibration algorithm was used for velocity data reduction from the calibration map and based on the combination of a look-up, a binary search algorithm and a geometry transformation including the translation and reflection of nodes in a calibration map. The calibration map was expanded up to the application angle, ${\pm}55^{\circ}$ of a probe. This velocity data reduction method showed a perfect performance without any kind of interpolating errors in calculating yaw and pitch angles from the calibration map. Moreover, when it was applied to an actual flow field including a swirling flow, a good result came out on the whole.

Analysis of the Mandibular Movements in Patients with Internal Derangement of the Temporomandibular Joint According to Diagnostic Subgroups (측두하악관절내장 환자의 진단분류에 따른 하악운동 특성의 분석)

  • 김병연;기우천;최재갑
    • Journal of Oral Medicine and Pain
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    • v.23 no.1
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    • pp.21-36
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    • 1998
  • The purpose of this study was analyse the mandibular movements in patients with internal derangement of the temporomandibular joint according to diagnostic subgroups. The author classified patients with internal derangement of the temporomandibular joint into 4 diagnostic subgroups by means of the magnet resonance imagings, and evaluated the clinical signs and the mandibular movements with Mandibular Kinesiograph(MKG) in each subgroups. The mandibular movements, measured in this study, were the types of movement in frontal and sagittal plane, velocities in opening and closing movement, and the opening and closing movement, and the opening and closing velocity pattern. The data were compared between the 5 groups including the normal group. The results were as follows : 1. Pain was more frequently observed in the anterior disc displacement without reduction group than in the anterior disc displacement with reduction group. Sound of joint was more frequently observed in the anterior disc displacement with reduction group, and limitation of mandibular opening movement was more frequently observed in the anterior disc displacement without reduction group. Duration of the anterior disc displacement without reduction group was significantly short compared to that of the anterior disc displacement with reduction group, and duration of the unilateral anterior disc displacement without reduction group was shortest in the experimental group. The frequency of Angle's classifications had not significant correlations between the experimental groups. 2. Active and passive range of the opening movement, maximum protrusive movement, maximum lateral movement toward left side were significantly decreased in the experimental groups compared to the control group, but there was no significant difference in the range of the maximum lateral movement toward right side between the control and experiment groups. In unilateral anterior disc displacement without reduction group, the range of maximum lateral movement toward unaffected side was no significant difference in the range of the maximum lateral movement between toward affected side and toward unaffected side. 3. Maximum opening velocity, maximum closing velocity, average opening velocity, average closing velocity and maximum velocity of terminal tooth contact were significantly decreased in the experimental groups compared to control group. There was no significant difference in maximum opening velocity and maximum velocity of Terminal tooth contact between the subgroups of the experimental group each other, but there was significant difference in maximum closing velocity, average opening velocity and average closing velocity between the subgroups each other. 4. In the frontal plane of the MKG, the frequency of complex deviation type(F-2)pattern was significantly increased in the anterior disc displacement with out reduction group compared to the anterior disc displacement with reduction group and the control group. In the sagittal plane, the frequency of coincident type(S-1)was decreased in the same group. 5. In the maximum opening velocity pattern, the frequency of no-peak type (OV-3)in the unilateral anterior disc displacement with reduction group was significantly increased compared to the control group. The frequency of 1-peak type (OV-1) and 2-peak type (OV-2) was decreased in the anterior disc displacement with out reduction group, but the frequency of no-peak type (OV-3)was increased in the same group. In the maximum closing velocity pattern, the frequency of no-peak type (CV-3) was significantly increased in the anterior disc displacement without reduction group. Compared to the anterior disc displacement with reduction group and the control group. The frequency of 1-peak type (CV-1) and 2-peak type (CV-2) in the anterior disc displacement with reduction group was decreased than that in the control group.

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Effects of an Anti-wind Net on Wind Velocity Reduction by a Wind Tunnel Test and CFD (풍동시험과 CFD를 통한 방풍망의 풍속저감 효과)

  • Yum, Sung-Hyun;Kang, Seung-Hee;Kim, Seoung-Hee;Lee, Sang-Bong;Kim, Min-Young
    • Journal of Biosystems Engineering
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    • v.36 no.5
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    • pp.355-360
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    • 2011
  • This study was carried out to analyze the installation effect of an anti-wind net on reducing wind velocity which was used to protect orchards as well as single-span plastichouses. The pressure drop through three types of anti-wind net was measured in a subsonic wind tunnel. The wind reduction through the anti-wind facility for several sets in respect to three types of the net and heights of the facility ranging from 3 to 11 m was analyzed by using computational fluid dynamics (CFD). The measured data showed that the pressure drop increased as an equation of the second degree of the inlet wind velocity. Numerical computations exhibited that the effect of wind reduction definitely augmented as the net size became smaller and increased with the height of the facility being heightened to some extent. For the typical and widely used anti-wind facility with a height of 5 m and a net size of 4mm, the amount of wind reduction came up to 5.1 m/s for the inlet wind velocity of 20 m/s, and also 7.6 and 10.1 m/s for the inlet wind velocities of 30 and 40 m/s, respectively. In case for the orchard's longitudinal length to be within about 200 m, the appropriately effective height of the facility was predicted to be 5 m. Finally, the negative total pressure on the top face of the single-span plastichouse certainly reduced for all the cases with the anti-wind facility being installed. In particular, the reduction of the negative total pressure was more considerable as the inlet wind velocity increased.

Measurement System Development for Three-Dimensional Flow Velocity Components Using Straight-Type Five-Hole Pressure Probe (직선형 5공 압력프로브를 이용한 3차원 유동속도 계측시스템 개발)

  • Kim, J.K.;Jeong, K.J.;Oh, S.H.
    • Journal of Power System Engineering
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    • v.10 no.4
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    • pp.56-64
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    • 2006
  • This paper shows the development process of a straight-type five-hole pressure probe for measuring three-dimensional flow velocity components. The data reduction method using a bi-cubic curve-fitting program in a new calibration map was introduced in this study. This new calibration map can be applied up to the application angle, ${\pm}55^{\circ}$ of a probe. As a result, for the application angle of ${\pm}45^{\circ}$, an error for yaw and pitch angles appeared from $-1.76^{\circ}\;to\;1.83^{\circ}$ and from $-1.91^{\circ}\;to\;1.75^{\circ}$, respectively. Moreover, an error for a vector magnitude and a static pressure compared with a dynamic one showed from -7.83% to 4.87% and from -0.73 to 0.77, respectively. Even though this data reduction method showed unsatisfactory errors in a vector magnitude, it resulted in an easy and simple application method. Especially, when it was applied to an actual flow field including a swirling flow, a good result came out on the whole. However, in order to obtain a better result, it is thought that a more sophisticated interpolation method needs to be introduced.

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The Effect of an Oxidation Precatalyst on the $NO_x$ Reduction by $NH_3$-SCR Process in Diesel Exhaust ($NH_3$-SCR 방법에 의한 디젤 배기 내 De-$NO_x$ 과정에서의 DOC에 의한 영향과 저감 성능 변화)

  • Jung, Seung-Chai;Yoon, Woong-Sup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.5
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    • pp.68-76
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    • 2008
  • Diesel $NO_x$ reduction by $NH_3$-SCR in conjunction with the effective oxidation precatalyst was analytically investigated. Physicochemical processes in regard to $NH_3$-SCR $NO_x$ reduction and catalytic NO-$NO_2$ conversion are formulated with detailed descriptions on the commanding reactions. A unified model is correctly validated with experimental data in terms of extents of $NO_x$ reduction by SCR and NO-$NO_2$ conversion by DOC. The present deterministic model based on the rate expressions of Langmuir-Hinshelwood reaction scheme finds a conversion extent directly. A series of numerical experiments concomitant with parametric analysis of the $NO_x$ reduction was conducted. $NO_x$ reduction is promoted in proportion to DOC volume ar lower temperatures and an opposite holds at lower space velocity and intermediate temperatures. $NO_x$ conversion is weakly correlated to the space velocity and the DOC volume at higher exhaust temperature. In DOC-SCR system, the $NO_x$ reduction efficiency depends on the $NH_3/NO_x$ ratio.

An experimental study on corrosion properties of reinforcing steel under environment of complex deterioration (표면피복종류에 따른 복합열화환경하의 철근콘크리트 부식특성에 관한 실험적 연구)

  • 조봉석;김영덕;윤종기;김재환;김용로;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.86-89
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    • 2003
  • It is recognized that reinforcement corrosion is the main distress behind the present concern regarding concrete durability. In this study, to confirm corrosion of reinforced concrete affected by thickness of cover, kinds of surface coating, measured electric potential, ratio of corrosion area, weight reduction, corrosion velocity of steel bar under environment of complex deterioration. The results showed that an increase in age also increases corrosion of steel bar. Ratio of corrosion area is largely related to ratio of weight reduction. as well, corrosion of steel bar by thickness of cover is superior to l0mm thick than 20mm thick. It showed that an increase in thickness of cover prevent steel bar from deteriorating. The results of this study showed that corrosion velocity was affected by thickness of cover, kinds of surface coating. data on the development of corrosion velocity made with none, organic B, organic A, inorganic B, and inorganic A is shown.

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