• Title/Summary/Keyword: Space Model

Search Result 8,200, Processing Time 0.033 seconds

Comparative Analysis on Surplus Production Models for Stock Assessment of Red Snow Crab Chinonoecetes japonicus (붉은대게(Chinonoecetes japonicus) 자원평가를 위한 잉여생산량모델의 비교 분석)

  • Choi, Ji-Hoon;Kim, Do-Hoon;Oh, Taeg-Yun;Seo, Young Il;Kang, Hee Joong
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.53 no.6
    • /
    • pp.925-933
    • /
    • 2020
  • This study is aimed to compare stock assessment models which are effective in assessing red snow crab Chinonoecetes japonicus resources and to select and apply an effective stock assessment model in the future. In order to select an effective stock assessment model, a process-error model, observation-error model, and a Bayesian state-space model were estimated. Analytical results show that the least error is observed between the estimated CPUE (catch per unit effort) and the observed CPUE when using the Bayesian state-space model. For the Bayesian state-space model, the 95% credible interval(CI) ranges for the maximum sustainable yield (MSY), carrying capacity (K), catchability coefficient (q), and intrinsic growth (r) are estimated to be 10,420-47,200 tons, 185,200-444,800 tons, 3.81E-06-9.02E-06, and 0.14-0.66, respectively. The results show that the Bayesian state-space model was most reliable among models.

Modeling of Space Radiation Exposure Estimation Program for Pilots, Crew and Passengers on Commercial Flights

  • Hwang, Junga;Dokgo, Kyunghwan;Choi, Enjin;Park, Jong-Sun;Kim, Kyung-Chan;Kim, Hang-Pyo
    • Journal of Astronomy and Space Sciences
    • /
    • v.31 no.1
    • /
    • pp.25-31
    • /
    • 2014
  • There has been a rapid increase of the concern on the space radiation effect on pilots, crew and passengers at the commercial aircraft altitude (~ 10 km) recently. It is because domestic airline companies, Korean Air and Asiana Airlines have just begun operating the polar routes over the North Pole since 2006 and 2009 respectively. CARI-6 and CARI-6M are commonly used space radiation estimation programs which are provided officially by the U.S. federal aviation administration (FAA). In this paper, the route doses and the annual radiation doses for Korean pilots and cabin crew were estimated by using CARI-6M based on 2012 flight records. Also the modeling concept was developed for our own space radiation estimation program which is composed of GEANT4 and NRLMSIS00 models. The GEANT4 model is used to trace the incident particle transports in the atmosphere and the NRLMSIS00 model is used to get the background atmospheric densities of various neutral atoms at the aircraft altitude. Also presented are the results of simple integration tests of those models and the plan to include the space weather variations through the solar proton event (SPE) prediction model such as UMASEP and the galactic cosmic ray (GCR) prediction model such as Badhwar-O'Neill 2010.

A Study on Path Loss Prediction for the PNG of Russia Using the Free Space Model and the Hata Model (자유 공간 모델과 하타 모델을 이용한 러시아 PNG 지역의 경로 손실 예측에 관한 연구)

  • Park, Kyung-Tae;Cho, Hyung-Rae
    • The Journal of The Korea Institute of Intelligent Transport Systems
    • /
    • v.10 no.5
    • /
    • pp.87-92
    • /
    • 2011
  • In this paper, we got the 800 ~ 900 MHz path loss model for Russia PNG area using the free space model and the Okumura-Hata Model. In order to add new regional properties to the existing path loss model, the mean square error technique is used to obtain the correction factor. The correction factors for the free space and the Hata model are 28, 13 dB respectively. By applying this correction factors, the new Russain PNG path loss model is proposed.

A Numerical Study of Smoke Movement by Fire In Atrium Space (화재 발생시 연기 거동에 대한 수치해석적 연구 - 아트리움 공간을 중심으로 -)

  • 노재성;유홍선;정연태
    • Journal of the Korean Society of Safety
    • /
    • v.13 no.1
    • /
    • pp.70-76
    • /
    • 1998
  • The smoke filling process for the atrium space containing a fire source is simulated using two types of deterministic fire models : Zone model and Field model. The zone model used is the CFAST(version 1.6) model developed at the Building and Fire Research Laboratories, NIST in the USA. The field model is a self-developed fire field model based on Computational Fluid Dynamics(CFD) theories. This article is focused on finding out the smoke movement and temperature distribution in atrium space which is cubic in shape. A computational procedure for predicting velocity and temperature distribution in fire-induced flow is based on the solution, in finite volume method and non-staggered grid system, of 3-dimensional equations for the conservation of mass, momentum, energy, species and so forth. The fire model i. e. Zone model and Field model predicted similar results for the clear height and the smoke layer temperature.

  • PDF

A Study on the Deep Neural Network based Recognition Model for Space Debris Vision Tracking System (심층신경망 기반 우주파편 영상 추적시스템 인식모델에 대한 연구)

  • Lim, Seongmin;Kim, Jin-Hyung;Choi, Won-Sub;Kim, Hae-Dong
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.45 no.9
    • /
    • pp.794-806
    • /
    • 2017
  • It is essential to protect the national space assets and space environment safely as a space development country from the continuously increasing space debris. And Active Debris Removal(ADR) is the most active way to solve this problem. In this paper, we studied the Artificial Neural Network(ANN) for a stable recognition model of vision-based space debris tracking system. We obtained the simulated image of the space environment by the KARICAT which is the ground-based space debris clearing satellite testbed developed by the Korea Aerospace Research Institute, and created the vector which encodes structure and color-based features of each object after image segmentation by depth discontinuity. The Feature Vector consists of 3D surface area, principle vector of point cloud, 2D shape and color information. We designed artificial neural network model based on the separated Feature Vector. In order to improve the performance of the artificial neural network, the model is divided according to the categories of the input feature vectors, and the ensemble technique is applied to each model. As a result, we confirmed the performance improvement of recognition model by ensemble technique.

Propulsion System Modeling and Reduction for Conceptual Truss-Braced Wing Aircraft Design

  • Lee, Kyunghoon;Nam, Taewoo;Kang, Shinseong
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.18 no.4
    • /
    • pp.651-661
    • /
    • 2017
  • A truss-braced wing (TBW) aircraft has recently received increasing attention due to higher aerodynamic efficiency compared to conventional cantilever wing aircraft. For conceptual TBW aircraft design, we developed a propulsion-and-airframe integrated design environment by replacing a semi-empirical turbofan engine model with a thermodynamic cycle-based one built upon the numerical propulsion system simulation (NPSS). The constructed NPSS model benefitted TBW aircraft design study, as it could handle engine installation effects influencing engine fuel efficiency. The NPSS model also contributed to broadening TBW aircraft design space, for it provided turbofan engine design variables involving a technology factor reflecting progress in propulsion technology. To effectively consolidate the NPSS propulsion model with the TBW airframe model, we devised a rapid, approximate substitute of the NPSS model by reduced-order modeling (ROM) to resolve difficulties in model integration. In addition, we formed an artificial neural network (ANN) that associates engine component attributes evaluated by object-oriented weight analysis of turbine engine (WATE++) with engine design variables to determine engine weight and size, both of which bring together the propulsion and airframe system models. Through propulsion-andairframe design space exploration, we optimized TBW aircraft design for fuel saving and revealed that a simple engine model neglecting engine installation effects may overestimate TBW aircraft performance.

A State Space Model using mode analysis by the Finite Elements Method for the Huge Marine Diesel Engine (박용 엔진의 유한요소 모드해석을 통한 상태 공간 모델 개발)

  • Lee W.C.;Kim S.R.;Ahn B.S.;Choi H.O.;Kim C.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2006.05a
    • /
    • pp.387-388
    • /
    • 2006
  • This article provides a dynamic analysis model for huge marine engine that examined analytically variation effects of frequency response by fitting of transverse stays such as hydraulic type. First, vibration analysis using the three dimensional finite element models for the huge marine engine has performed in order to find out the dynamic characteristics. Second, three dimensional finite elements model for the huge marine engine was modifued so that generate forcing nodes in crosshead part and top bracing nodes in cylinder frame part. Third, a system matrix and output matrix was derived for the general siso(single input single out) state space model. Finally, developed state space model for the three dimensional finite elements model for the huge marine engine without the additional modifying process.

  • PDF

Denoising solar SDO/HMI magnetograms using Deep Learning

  • Park, Eunsu;Moon, Yong-Jae;Lim, Daye;Lee, Harim
    • The Bulletin of The Korean Astronomical Society
    • /
    • v.44 no.2
    • /
    • pp.43.1-43.1
    • /
    • 2019
  • In this study, we apply a deep learning model to denoising solar magnetograms. For this, we design a model based on conditional generative adversarial network, which is one of the deep learning algorithms, for the image-to-image translation from a single magnetogram to a denoised magnetogram. For the single magnetogram, we use SDO/HMI line-of-sight magnetograms at the center of solar disk. For the denoised magnetogram, we make 21-frame-stacked magnetograms at the center of solar disk considering solar rotation. We train a model using 7004 paris of the single and denoised magnetograms from 2013 January to 2013 October and test the model using 1432 pairs from 2013 November to 2013 December. Our results from this study are as follows. First, our model successfully denoise SDO/HMI magnetograms and the denoised magnetograms from our model are similar to the stacked magnetograms. Second, the average pixel-to-pixel correlation coefficient value between denoised magnetograms from our model and stacked magnetogrmas is larger than 0.93. Third, the average noise level of denoised magnetograms from our model is greatly reduced from 10.29 G to 3.89 G, and it is consistent with or smaller than that of stacked magnetograms 4.11 G. Our results can be applied to many scientific field in which the integration of many frames are used to improve the signal-to-noise ratio.

  • PDF

Improving the Accuracy of a Heliocentric Potential (HCP) Prediction Model for the Aviation Radiation Dose

  • Hwang, Junga;Yoon, Kyoung-Won;Jo, Gyeongbok;Noh, Sung-Jun
    • Journal of Astronomy and Space Sciences
    • /
    • v.33 no.4
    • /
    • pp.279-285
    • /
    • 2016
  • The space radiation dose over air routes including polar routes should be carefully considered, especially when space weather shows sudden disturbances such as coronal mass ejections (CMEs), flares, and accompanying solar energetic particle events. We recently established a heliocentric potential (HCP) prediction model for real-time operation of the CARI-6 and CARI-6M programs. Specifically, the HCP value is used as a critical input value in the CARI-6/6M programs, which estimate the aviation route dose based on the effective dose rate. The CARI-6/6M approach is the most widely used technique, and the programs can be obtained from the U.S. Federal Aviation Administration (FAA). However, HCP values are given at a one month delay on the FAA official webpage, which makes it difficult to obtain real-time information on the aviation route dose. In order to overcome this critical limitation regarding the time delay for space weather customers, we developed a HCP prediction model based on sunspot number variations (Hwang et al. 2015). In this paper, we focus on improvements to our HCP prediction model and update it with neutron monitoring data. We found that the most accurate method to derive the HCP value involves (1) real-time daily sunspot assessments, (2) predictions of the daily HCP by our prediction algorithm, and (3) calculations of the resultant daily effective dose rate. Additionally, we also derived the HCP prediction algorithm in this paper by using ground neutron counts. With the compensation stemming from the use of ground neutron count data, the newly developed HCP prediction model was improved.

A robust multi-objective localized outrigger layout assessment model under variable connecting control node and space deposition

  • Lee, Dongkyu;Lee, Jaehong;Kang, Joowon
    • Steel and Composite Structures
    • /
    • v.33 no.6
    • /
    • pp.767-776
    • /
    • 2019
  • In this article, a simple and robust multi-objective assessment method to control design angles and node positions connected among steel outrigger truss members is proposed to approve both structural safety and economical cost. For given outrigger member layouts, the present method utilizes general-purpose prototypes of outrigger members, having resistance to withstand lateral load effects directly applied to tall buildings, which conform to variable connecting node and design space deposition. Outrigger layouts are set into several initial design conditions of height to width of an arbitrary given design space, i.e., variable design space. And then they are assessed in terms of a proposed multi-objective function optimizing both minimal total displacement and material quantity subjected to design impact factor indicating the importance of objectives. To evaluate the proposed multi-objective function, an analysis model uses a modified Maxwell-Mohr method, and an optimization model is defined by a ground structure assuming arbitrary discrete straight members. It provides a new robust assessment model from a local design point of view, as it may produce specific optimal prototypes of outrigger layouts corresponding to arbitrary height and width ratio of design space. Numerical examples verify the validity and robustness of the present assessment method for controlling prototypes of outrigger truss members considering a multi-objective optimization achieving structural safety and material cost.