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Method for Preventing Asphyxiation Accidents by a CO2 Extinguishing System on a Ship (선박 내 CO2 소화설비에 의한 질식사고 방지 기법)

  • Ha, Yeon-Chul;Seo, Jung-Kwan;Hwang, Jun-Ho;Im, Kichang;Ryu, Sang-Hoon
    • Fire Science and Engineering
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    • v.29 no.6
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    • pp.57-64
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    • 2015
  • Carbon dioxide extinguishing systems are broadly used for onshore and offshore fire accidents because of excellent performance and low cost. However, there is risk with carbon dioxide systems, which have caused many injuries and deaths by suffocation associated with industrial and marine fire protection applications. In this study, a numerical analysis was performed to predict the fire suppression characteristics of a carbon dioxide system in the compressor room of ships. A double protection safety system is suggested to prevent suffocation accidents from carbon dioxide extinguishing systems. Four scenarios were selected to study the variation of the heat release rate, maximum temperature, a $CO_2$ and $O_2$ mole fraction, and fire suppression characteristics with the carbon dioxide system. The importance of proper design is suggested for a ventilation system in the compressor room of ships.

Introduction to Chang'e-3 and Analysis of Estimated Mission Trajectory (창어 3호 개요 및 임무궤적 추정결과 분석)

  • Choi, Su-Jin;Lee, Donghun;Bae, Jonghee;Rew, Dong-Young;Ju, Gwanghyeok;Sim, Eun-Sup
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.11
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    • pp.984-997
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    • 2015
  • Chang'e-3 consisting of a lunar lander and exploration rover was launched on December 1, 2013 aboard a Long March 3B rocket flying from Xichang space launch center. Chang'e-3 was inserted into the lunar orbit after about a 5-day transit to the Moon and landed on the targeted landing site after orbiting around the Moon for 8 days. The successful landing of the Chang'e-3 gives a lot of help to analyze the future needs of the subsystem technologies and to figure out the trajectory from launch to lunar landing as well as operation sequences in the development of Korean lunar exploration is scheduled. Therefore, the configuration and analysis of overall mission of Chang'e-3 is performed based on the public information from the press and website. As a result, overall mission trajectory is reconstructed by solving boundary condition and then estimating control variable. Visibility status and eclipse status also analyzes so communication and power charge condition is as good as to operate lunar lander. Mass budget of the lander is derived using ${\Delta}V$ according to specific impulse.

Flight Technical Error Modeling for UAV supported by Local Area Differential GNSS (LADGNSS 항법지원을 받는 무인항공기의 비행 기술 오차 모델링 기법)

  • Kim, Kiwan;Kim, Minchan;Lee, Dong-Kyeong;Lee, Jiyun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.12
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    • pp.1054-1061
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    • 2015
  • Navigation accuracy, integrity, and safety of commercial Unmanned Aerial Vehicle (UAV) is becoming crucial as utilization of UAV in commercial applications is expected to increase. Recently, the concept of Local-Area Differential GNSS (LADGNSS) which can provide navigation accuracy and integrity of UAV was proposed. LADGNSS can provide differential corrections and separation distances for precise and safe operation of the UAV. In order to derive separation distances between UAVs, modeling of Flight Technical Error (FTE) is required. In most cases, FTE for civil aircraft has been assumed to be zero-mean normal distribution. However, this assumption can cause overconservatism especially for UAV, because UAV may use control and navigation equipments in wider performance range and follow more diverse path than standard airway for civil aircraft. In this research, flight experiments were carried out to understand the characteristics of FTE distribution. Also, this paper proposes to use Johnson distribution which can better describe heavy-tailed and skewed FTE data. Futhermore, Kolmogorov-Smirnov and Anderson-Darling tests were conducted to evaluate the goodness of fit of Johnson model.

Drone-Based Micro-SAR Imaging System and Performance Analysis through Error Corrections (드론을 활용한 초소형 SAR 영상 구현 및 품질 보상 분석)

  • Lee, Kee-Woong;Kim, Bum-Seung;Moon, Min-Jung;Song, Jung-Hwan;Lee, Woo-Kyung;Song, Yong-Kyu
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.9
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    • pp.854-864
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    • 2016
  • The use of small drone platform has become a popular topic in these days but its application for SAR operation has been little known due to the burden of the payload implementation. Drone platforms are distinguished from the conventional UAV system by the increased vulnerability to the turbulences, control-errors and poor motion stability. Consequently, sophisticated motion compensation may be required to guarantee the successful acquisition of high quality SAR imagery. Extremely limited power and mass budgets may prevent the use of additional hardwares for motion compensation and the difficulty of SAR focusing is further aggravated. In this paper, we have carried out a feasibility study of mico-SAR drone operation. We present the image acquisition results from the preliminary flight tests and a quality assessment is followed on the experimental SAR images. The in-flight motion errors derived from the unique drone movements are investigated and attempts have been made to compensate for the geometrical and phase errors caused by motions against the nominal trajectory. Finally, the successful operation of drone SAR system is validated through the focussed SAR images taken over test sites.

Effect of graphene oxide on mechanical characteristics of polyurethane foam (산화그래핀이 폴리우레탄 폼 기계적 강도에 미치는 영향)

  • Kim, Jong-Min;Kim, Jeong-Hyeon;Choe, Young-Rak;Park, Sung Kyun;Park, Kang Hyun;Lee, Jae-Myung
    • Journal of the Korean Society of Marine Engineering
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    • v.40 no.6
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    • pp.493-498
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    • 2016
  • In the present study, graphene oxide based polyurethane foams were manufactured as a part of the development process of mechanically strengthened polyurethane foam insulation material. This material is used in a liquefied natural gas carrier cargo containment system. The temperature of the containment system is $-163^{\circ}C$. First, graphene oxide was synthesized using the Hummers' method, and it was supplemented into polyol-isocyanate reagent by considering a different amount of graphene oxide weight percent. Then, a bulk form of graphene-oxide-polyurethane foam was manufactured. In order to investigate the cell stability of the graphene-oxide-polyurethane foam, its microstructural morphology was observed, and the effect of graphene oxide on microstructure of the polyurethane foam was investigated. In addition, the compressive strength of graphene-oxide-polyurethane foam was measured at ambient and cryogenic temperatures. The cryogenic tests were conducted in a cryogenic chamber equipped with universal testing machine to investigate mechanical and failure characteristics of the graphene-oxide-polyurethane foam. The results revealed that the additions of graphene oxide enhanced the mechanical characteristics of polyurethane foam. However, cell stability and mechanical strength of graphene-oxide-polyurethane foam decreased as the weight percent of graphene oxide was increased.

Synthesis of Cubic and Rod Shapes CaCO3 by Hydrothermal Method (수열합성법을 이용한 큐빅과 로드형의 탄산칼슘 합성)

  • Kang, Kuk-Hyoun;Jeon, Sang-Chul;Hyun, Mi-Ho;Lee, Dong-Kyu
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.6
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    • pp.255-261
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    • 2016
  • $CaCO_3$ was applied in various industries including rubber, plastics, paint, paper, food additives, and acid neutralizer, etc., owing to its excellent physical and chemical characteristics as well as various appearances of crystals and many reserves. In particular, research on controlling the structure and shape of $CaCO_3$ has attracted considerable attention recently, because the whiteness and physical characteristics of $CaCO_3$ depend on the size and shapes of the particles. In this study, $CaCO_3$ was synthesized using $CaCl_2$ and $(NH4)_2CO_3$, which has multi-shapes and structures, using a self-assembly method with a hydrothermal method. The structure and morphology of the $CaCO_3$ could be controlled by adjusting the pH and precursor concentration. In particular, the pH adjustment appeared to be a critical factor for the morphology and crystal form. In addition, the calcite and cubic shape were obtained at pH 7, while the mixed calcite, aragonite structure, and rod shapes appeared at pH 7 and over. Through an analysis of the particle formation process, the formation of the calcium carbonate particles was confirmed. The physicochemical properties of the synthesized $CaCO_3$ were analyzed by SEM, XRD, EDS, FTIR, and TG/DTA.

Development of a Decision Making Model for Construction Management in LNG Plant Construction - Focused on Construction Stage - (LNG 공사의 건설사업관리 의사결정지원모델 개발 - 시공단계 중심 -)

  • Park, Hwan Pyo;Han, Jae Goo;Chin, Kyung Ho
    • Korean Journal of Construction Engineering and Management
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    • v.15 no.3
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    • pp.47-57
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    • 2014
  • LNG plant projects tend to be implemented in overseas owing to its characteristics, so their project management scheme is somewhat different from those of general projects. Value chain in a LNG plant project includes exploration/production of gases, physical liquefaction/chemical conversion processes, transportation and storage. Key factors in the chain include liquefaction process (including ultra-low temperature liquefaction) to convert natural gas into liquid materials or fuel, and Front End Engineering Design (FEED) package, as well as Engineering, Procurement and Construction (EPC) technology comprising control, operation and construction. Success of a complex LNG plant project implemented in overseas depends on decision-making process in project management. Accordingly, to develop a decision-making model in of plant construction, the study extracted none factors in project management by EPC stage and assessed importance of each factor. The result showed that items in both project management and project risk management are important. Especially, the study developed a decision-making model in the construction stage of a LNG plant project based on the project management factors and importance assessment. The developed decision-making model would lay groundwork in building a decision-making system in construction stage of project management.

A Case Study on Elephant Foot Method for Railway Tunneling in Large Fault Zone (대규모 단층대구간에서의 철도터널 우각부 보강공법 적용성 연구)

  • Lee, Gilyong;Oh, Jeongho;Cho, Kyehwan;Lee, Doosoo
    • Journal of The Korean Society of Civil Engineers
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    • v.36 no.6
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    • pp.1161-1167
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    • 2016
  • In this study, an attempt was made to conduct a case study on the development of ground expansive displacement due to lack of bearing capacity of original ground in spite of applying reinforcement treatments that intended to enhance the stability of big size high-speed rail tunnel in large fault zone. For the purpose of this, in-situ measurements made in the middle of excavation stage were analyzed in order to characterize ground responses and numerical analysis was performed to evaluate the effectiveness of reinforcement technique such as elephant foot method applied for this site via comparing with field monitoring measurements. In addition, further numerical studies were carried out to investigate the influence of leg pile installation angle and length, which is one of types of elephant foot method. The results revealed that the optimum condition for the leg pile installation is to maintain 45 degree of installation angle along with 6 meter of embedment depth.

The implementation of cable path and overfill visualization based on cable occupancy rate in the Shipbuilding CAD (조선 CAD에서 선박의 Cable 점유율을 기반으로 Cable 경로 및 Overfill 가시화 구현)

  • Kim, Hyeon-Jae;Kim, Bong-Gi
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.11
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    • pp.740-745
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    • 2016
  • Cables are installed for tens of thousands of connections between various pieces of equipment to operate and control a commercial ship. The correct shortest-route data is necessary since these are complicated cable installations. Therefore, an overfill interval commonly exists in the shortest paths for cables as estimated by Dijkstra's algorithm, even if this algorithm is generally used. It is difficult for an electrical engineer to find the overfill interval in 3D cable models because the occupancy rate data exist in a data sheet unlinked to three-dimensional (3D) computer-aided design (CAD). The purpose of this study is to suggest a visualization method that displays the cable path and overfill interval in 3D CAD. This method also provides various color visualizations for different overfill ranges to easily determine the overfill interval. This method can reduce cable-installation man-hours from 7,000 to 5,600 thanks to a decreased re-installation rate, because the cable length calculation's accuracy is raised through fast and accurate reviews based on 3D cable visualization. As a result, material costs can also be reduced.

PM10 and Associated Trace Elements in the Subway Cabin of Daejeon by Instrumental Neutron Activation Analysis (기기 중성자방사화 분석을 이용한 대전 지하철 객차 내 PM10과 미량성분의 특성)

  • Jeong, Jin Hee;Lim, Jong Myoung;Lee, Jin-Hong
    • Journal of Korean Society of Environmental Engineers
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    • v.38 no.8
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    • pp.459-467
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    • 2016
  • In order to assess the pollution status and distribution characteristics of PM and PM-bound species, PM10 samples were collected using mini-volume air sampler at the subway cabin in Daejeon city. Measurements of about 24 elements including toxic metals (e.g., As, Cr, Mn, V, Zn) in PM10 were made by instrumental neutron activation analysis and X-ray fluorescence. The average PM10 concentration was $59.3{\pm}14.5{\mu}g/m^3$ in the subway cabin with a range of 42.2 to $97.4{\mu}g/m^3$, while the associated elemental concentrations were varied in the range of $10^{-3}$ to $10^5ng/m^3$. It was found that the concentration of Fe ($12.5{\mu}g/m^3$) was substantially higher than any other element. The Fe concentration was apportioned by about 20% of the PM10 concentration. The results of factor analysis indicate that there are no more than six sources in the cabin (e.g., brake-nonferrous metal particle, resuspended rail dust, fuel combustion, vehicle exhaust, black carbon, Cr-related).