• Title/Summary/Keyword: application layer

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Ground-Roll Suppression of the Land Seismic Data using the Singular Value Decomposition (SVD) (특이값 분해를 이용한 육상 탄성파자료의 그라운드롤 제거)

  • Sa, Jin-Hyeon;Kim, Sung-Soo;Kim, Ji-Soo
    • The Journal of Engineering Geology
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    • v.28 no.3
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    • pp.465-473
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    • 2018
  • The application of singular value decomposition (SVD) filtering is examined for attenuation of the ground-roll in land seismic data. Prior to the SVD computation to seek singular values containing the highly correlatable reflection energy, processing steps such as automatic gain control, elevation and refraction statics, NMO correction, and residual statics are performed to enhance the horizontal correlationships and continuities of reflections. Optimal parameters of SVD filtering are effectively chosen with diagnostic display of inverse NMO (INMO) corrected CSP (common shot point) gather. On the field data with dispersion of ground-roll overwhelmed, continuities of reflection events are much improved by SVD filtering than f-k filtering by eliminating the ground-roll with preserving the low-frequency reflections. This is well explained in the average amplitude spectra of the f-k and SVD filtered data. The reflectors including horizontal layer of the reservoir are much clearer on the stack section, with laminated events by SVD filtering and subsequent processing steps of spiking deconvolution and time-variant spectral whitening.

Interactions between Soil Moisture and Weather Prediction in Rainfall-Runoff Application : Korea Land Data Assimilation System(KLDAS) (수리 모형을 이용한 Korea Land Data Assimilation System (KLDAS) 자료의 수문자료에 대한 영향력 분석)

  • Jung, Yong;Choi, Minha
    • 한국방재학회:학술대회논문집
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    • 2011.02a
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    • pp.172-172
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    • 2011
  • The interaction between land surface and atmosphere is essentially affected by hydrometeorological variables including soil moisture. Accurate estimation of soil moisture at spatial and temporal scales is crucial to better understand its roles to the weather systems. The KLDAS(Korea Land Data Assimilation System) is a regional, specifically Korea peninsula land surface information systems. As other prior land data assimilation systems, this can provide initial soil field information which can be used in atmospheric simulations. For this study, as an enabling high-resolution tool, weather research and forecasting(WRF-ARW) model is applied to produce precipitation data using GFS(Global Forecast System) with GFS embedded and KLDAS soil moisture information as initialization data. WRF-ARW generates precipitation data for a specific region using different parameters in physics options. The produced precipitation data will be employed for simulations of Hydrological Models such as HEC(Hydrologic Engineering Center) - HMS(Hydrologic Modeling System) as predefined input data for selected regional water responses. The purpose of this study is to show the impact of a hydrometeorological variable such as soil moisture in KLDAS on hydrological consequences in Korea peninsula. The study region, Chongmi River Basin, is located in the center of Korea Peninsular. This has 60.8Km river length and 17.01% slope. This region mostly consists of farming field however the chosen study area placed in mountainous area. The length of river basin perimeter is 185Km and the average width of river is 9.53 meter with 676 meter highest elevation in this region. We have four different observation locations : Sulsung, Taepyung, Samjook, and Sangkeug observatoriesn, This watershed is selected as a tentative research location and continuously studied for getting hydrological effects from land surface information. Simulations for a real regional storm case(June 17~ June 25, 2006) are executed. WRF-ARW for this case study used WSM6 as a micro physics, Kain-Fritcsch Scheme for cumulus scheme, and YSU scheme for planetary boundary layer. The results of WRF simulations generate excellent precipitation data in terms of peak precipitation and date, and the pattern of daily precipitation for four locations. For Sankeug observatory, WRF overestimated precipitation approximately 100 mm/day on July 17, 2006. Taepyung and Samjook display that WRF produced either with KLDAS or with GFS embedded initial soil moisture data higher precipitation amounts compared to observation. Results and discussions in detail on accuracy of prediction using formerly mentioned manners are going to be presented in 2011 Annual Conference of the Korean Society of Hazard Mitigation.

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Measurement of minimum line width of an object fabricated by metal 3D printer using powder bed fusion type with stainless steal powder (스테인리스강을 사용한 분말 적층 용융 방식의 금속 3차원 프린터에서 제작된 물체의 최소 선폭 측정)

  • Son, BongKuk;Jeong, Youn Hong;Jo, Jae Heung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.10
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    • pp.346-351
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    • 2018
  • Metal three-dimensional (3D) printing technologies are mainly classified as powder bed fusion (PBF) and direct energy deposition (DED) methods according to the method of application of a laser beam to metallic powder. The DED method can be used to fabricate fine and hard 3D metallic structures by applying a strong laser beam to a thin layer of metallic powder. The PBF method involves slicing 3D graphics to be a certain height, laminating metal powders, and making a 3D structure using a laser. While the DED method has advantages such as laser cladding and metallic welding, it causes problems with low density when 3D shapes are created. The PBF method was introduced to address the structural density issues in the DED method and makes it easier to produce relatively dense 3D structures. In this paper, thin lines were produced by using PBF 3D printers with stainless-steel powder of roughly $30{\mu}m$ in diameter with a galvano scanner and fiber-transferred Nd:YAG laser beam. Experiments were carried out to find the optimal conditions for the width of a line depending on the processing times, laser power, spot size, and scan speed. The optimal conditions were two scanning processes in one line structure with a laser power of 30 W, spot size of $28.7{\mu}m$, and scan speed of 200 mm/s. With these conditions, a minimum width of about $85.3{\mu}m$ was obtained.

Analysis of Observational Cases Measured by MRR and PARSIVEL Disdrometer for Understanding the Physical Characteristics of Precipitation (강수의 물리적 특성 이해를 위한 MRR 및 PASIVEL 우적계의 관측사례 분석)

  • Cha, Joo-Wan;Chang, Ki-Ho;Oh, Sung-Nam;Choi, Young-Jean;Jeong, Jin-Yim;Jung, Jae-Won;Yang, Ha-Young;Bae, Jin-Young;Kang, Sun-Young
    • Atmosphere
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    • v.20 no.1
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    • pp.37-47
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    • 2010
  • The methods measuring the precipitation drop size distribution(hereafter referred to as DSD) at Cloud Physics Observation System (CPOS) in Daegwallyeong are to use PARSIVEL (PARticle SIze and VELocity) disdrometer (hereafter referred to as PARSIVEL) and Micro Rain Radar (hereafter referred to as MRR). First of all, PARSIVEL and MRR give good correlation coefficients between their rain rates and those of rain gage: $R^2=0.93$ and 0.91, respectively. For the DSD, the rain rates are classified in 3 categories (Category 1: rr (Rain Rate) ${\leq}0.5\;mm\;h^{-1}$, Category 2: $0.5\;mm\;h^-1$ < rr < $4.0\;mm\;h^{-1}$, Category 3: rr ${\geq}4\;mm\;h^{-1}$). The shapes of PARSIVEL and MRR DSD are relatively most similar in category 2. In addition, we retrieve the vertical rain rate and liquid water content from MRR under melting layer, calculated by Cha et al's method, in Daegwallyeong ($37^{\circ}41{\prime}N$, $128^{\circ}45^{\prime}E$, 843 m ASL, mountain area) and Haenam ($34^{\circ}33^{\prime}N$, $126^{\circ}34^{\prime}E$, 4.6 m ASL, coast area). The vertical variations of rain rate and liquid water content in Daegwallyeong are smaller than those in Haenam. We think that this different vertical rain rate characteristic for both sites is due to the vertical different cloud type (convective and stratiform cloud seem dominant at Haenam and Daegwallyeong, respectively). This suggests that the statistical precipitation DSD model, for the application of weather radar and numerical simulation of precipitation processes, be considered differently for the region, which will be performed in near future.

Parameter Optimization and Automation of the FLEXPART Lagrangian Particle Dispersion Model for Atmospheric Back-trajectory Analysis (공기괴 역궤적 분석을 위한 FLEXPART Lagrangian Particle Dispersion 모델의 최적화 및 자동화)

  • Kim, Jooil;Park, Sunyoung;Park, Mi-Kyung;Li, Shanlan;Kim, Jae-Yeon;Jo, Chun Ok;Kim, Ji-Yoon;Kim, Kyung-Ryul
    • Atmosphere
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    • v.23 no.1
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    • pp.93-102
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    • 2013
  • Atmospheric transport pathway of an air mass is an important constraint controlling the chemical properties of the air mass observed at a designated location. Such information could be utilized for understanding observed temporal variabilities in atmospheric concentrations of long-lived chemical compounds, of which sinks and/or sources are related particularly with natural and/or anthropogenic processes in the surface, and as well as for performing inversions to constrain the fluxes of such compounds. The Lagrangian particle dispersion model FLEXPART provides a useful tool for estimating detailed particle dispersion during atmospheric transport, a significant improvement over traditional "single-line" trajectory models that have been widely used. However, those without a modeling background seeking to create simple back-trajectory maps may find it challenging to optimize FLEXPART for their needs. In this study, we explain how to set up, operate, and optimize FLEXPART for back-trajectory analysis, and also provide automatization programs based on the open-source R language. Discussions include setting up an "AVAILABLE" file (directory of input meteorological fields stored on the computer), creating C-shell scripts for initiating FLEXPART runs and storing the output in directories designated by date, as wells as processing the FLEXPART output to create figures for a back-trajectory "footprint" (potential emission sensitivity within the boundary layer). Step by step instructions are explained for an example case of calculating back trajectories derived for Anmyeon-do, Korea for January 2011. One application is also demonstrated in interpreting observed variabilities in atmospheric $CO_2$ concentration at Anmyeon-do during this period. Back-trajectory modeling information introduced in this study should facilitate the creation and automation of most common back-trajectory calculation needs in atmospheric research.

Filtration Characteristics of Paticulate Matter at Bag Filters Coated with PTFE Membrane During Off-Line Pulsing (PTFE membrane이 코팅된 여과백의 off-line 탈진시 미세먼지 집진 특성)

  • Kim, Joung-Hun;Moon, Il-Shik;Hwang, Min-Young;Kim, Ryang-Gyoon;Ko, Daekwun
    • Journal of Korean Society of Environmental Engineers
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    • v.39 no.7
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    • pp.391-402
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    • 2017
  • Particulate matter becomes an important issue in the environmental society recently so that it is necessary to evaluate that the commercial application of baghouse systems for effective control of fine particulates is viable. A laboratory-scale baghouse experimental apparatus with filter bags made of PTFE felt or PTFE felt coated with PTFE membrane is used to investigate the filtration performances of fine particulates. Experiments by changing filtration velocity, inlet dust concentration, and average dust particle size show that the dust collection efficiency becomes higher at lower filtration velocity, higher inlet dust concentration and larger average dust particle size. The total pressure drop through the filter media and dust layer becomes higher at higher filtration velocity and higher inlet dust concentration. The dust collection efficiency is higher and the pressure drop is lower at a baghouse with filter bags coated with PTFE membrane than that without membrane coating. From the result that the dust collection efficiency of $PM_{2.5}$ in a reasonable filtration velocity range during off-line pulsing at a baghouse with PTFE felt bag filters coated with PTFE membrane is as high as 99.99%, it is confirmed that the use of baghouse is an effective measure to control the fine particulates.

Corrosion control technique for pipeline system through injecting water stabilizer (수질안정화 약품 주입에 따른 상수도관 내부 부식제어 특성 연구)

  • Hwang, Byung-Gi;Woo, Dal-Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.1
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    • pp.545-551
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    • 2011
  • Recently, demands for generating high quality tap waters are increasing with high concern of water pollution and corrosion of water pipelines. For the reasons, developing water quality stabilization technique in water purification system is sought rather than replacing to a new pipelines. In this study, high-purity liquid lime($Ca(OH)_2$) was introduced for a water quality stabilization technique in water purification process and simulated water distribution system of pilot-scale size was applied to evaluate anti-corrosion control effect. The effect of anti-corrosion control was calculated in terms of LSI(Langelier Saturation Index) In conclusion, the result of pilot plant showed improvement of corrosiveness by liquid lime($Ca(OH)_2$) with reduction of released iron(Fe). Application of anti-corrosion control technique to the mild steel coupon and the copper coupon were effective by indicating 35.4, 44.5% of improvements. Besides, sample pipes which were treated with liquid lime had formated more thicker layer of corrosion product inside of pipes. As a result, the process of injecting water stabilizer can greatly contribute to the high quality of tap water.

Internal Defection Evaluation of Spot Weld Part and Carbon Composite using the Non-contact Air-coupled Ultrasonic Transducer Method (비접촉 초음파 탐상기법을 이용한 스폿용접부 및 탄소복합체의 내부 결함평가)

  • Kwak, Nam-Su;Lee, Seung-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.11
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    • pp.6432-6439
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    • 2014
  • The NAUT (Non-contact Air coupled Ultrasonic Testing) technique is one of the ultrasonic testing methods that enables non-contact ultrasonic testing by compensating for the energy loss caused by the difference in acoustic impedance of air with an ultrasonic pulser receiver, PRE-AMP and high-sensitivity transducer. As the NAUT is performed in a state of steady ultrasonic transmission and reception, testing can be performed on materials of high or low temperatures or specimens with a rough surface or narrow part, which could not have been tested using the conventional contact-type testing technique. For this study, the internal defects of spot weld, which are often applied to auto parts, and CFRP parts, were tested to determine if it is practical to make the NAUT technique commercial. As the spot welded part had a high ultrasonic transmissivity, the result was shown as red. On the other hand, the part with an internal defect had a layer of air and low transmissivity, which was shown as blue. In addition, depending on the PRF (Pulse Repetition Frequency), an important factor that determines the measurement speed, the color sharpness showed differences. With the images obtained from CFRP specimens or an imaging device, it was possible to identify the shape, size and position of the internal defect within a short period of time. In this paper, it was confirmed in the above-described experiment that both internal defect detection and image processing of the defect could be possible using the NAUT technique. Moreover, it was possible to apply NAUT to the detection of internal defects in the spot welded parts or in CFRP parts, and commercialize its practical application to various fields.

A Performance Analysis of the Virtual CellSystem for Mobile Hosts (이동 호스트를 위한 가상 셀 시스템의 성능 분석)

  • Lim, Kyung-Shik
    • The Transactions of the Korea Information Processing Society
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    • v.5 no.10
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    • pp.2627-2640
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    • 1998
  • In this paper, we analyze the performance of the virtual cell system[1] for the transmission of IP datagrams in mobile computer communications. A virtual cell consistsof a group of physical cells shose base stationsl are implemented b recote bridges and interconnected via high speed datagram packet switched networks. Host mobility is supported at the data link layer using the distributed hierachical location information of mobile hosts. Given mobility and communication ptems among physical cells, the problem of deploying virtual cells is equivalent to the optimization cost for the entire system where interclster communication is more expesive than intracluster communication[2]. Once an iptimal partitionof disjoint clusters is obtained, we deploy the virtual cell system according to the topology of the optimal partition such that each virtual cell correspods to a cluser. To analyze the performance of the virtual cell system, we adopt a BCMP open multipel class queueing network model. In addition to mobility and communication patterns, among physical cells, the topology of the virtual cell system is used to determine service transition probabilities of the queueing network model. With various system parameters, we conduct interesting sensitivity analyses to determine network design tradeoffs. The first application of the proposed model is to determine an adequate network bandwidth for base station networking such that the networks would not become an bottleneck. We also evaluate the network vlilization and system response time due to various types of messages. For instance, when the mobile hosts begin moving fast, the migration rate will be increased. This results of the performance analysis provide a good evidence in demonsratc the sysem effciency under different assumptions of mobility and communication patterns.

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Preparation and Physical Properties of Diamond Grade Reflective Sheets Using Microprism (마이크로프리즘을 사용한 초고휘도 재귀반사시트의 제조 및 특성)

  • Lee, Min-Ho;Lim, Du-Hyun;Heo, Min-Yeong;Ahn, Jou-Hyeon;Park, Jin-Woo;Yu, Ji-Hyun;Kim, Jong-Seon;Ryu, Ho-Suk;Ahn, Hyo-Jun;Kim, Ik-Hwan
    • Elastomers and Composites
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    • v.46 no.4
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    • pp.284-289
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    • 2011
  • Prismatic reflective sheets were prepared using microprisms, and their retroreflection and structural properties were investigated and compared with encapsulated lens type reflective sheets based on glass beads. As prepared, the prismatic reflective sheets show well arranged array of microprisms. The arrangement of glass beads in encapsulated lens type reflective sheets is also found to be uniform without any cracks. However, during the coating process of the PET layer, the beads are coming out and the gaps are formed due to the application of high pressure. Even though the preparation method for reflective sheets based on microprisms is similar to that of reflective sheets based on glass beads, the method is relatively simple and cost effective, and also needs less time. Prismatic reflective sheets show higher coefficient of retroreflection from all entrance angles compared to reflective sheets based on glass beads. The results prove that the prismatic reflective sheets can be used for preparing the traffic sign boards to secure a clear view.