• Journal of the Korea Academia-Industrial cooperation Society
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• 제22권5호
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• pp.98-107
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• 2021

During the sea trial test for the aerovane in AOE-II, a malfunction occurred in the wind detector movement around 40 to 90° on the starboard side and around 270 to 320° on the port side. The purpose of this study was to analyze and improve the cause of the above phenomenon. The wind detector was covered with a mast structure and was not affected directly by the blowing wind, and a vortex air current was formed behind the mast structure, causing the motion malfunction. The above problem was solved by moving and installing the wind detector on the newly installed mast yard. After conducting vibration analysis and reviewing the effects of vibration, the wind detector was installed in the new mast yard and verified by a sea trial test. Since the improvement plan was slightly effective, the position of the wind detector moved away from the mast on the new mast yard and was re-verified through a sea trial test. The movement malfunction of the wind detector did not occur, confirming that it is an appropriate improvement plan.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제24권5호
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• pp.638-645
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• 2020

The mast is the highest structure in a naval ship, and various communication and radar antennas are installed to achieve long-range communications and line of sight. The U.S. and European navy currently are adopting integrated mast to their new ships, as it can reduce the Radar Cross Section(RCS) of the new ships and thus improve survivability of the ship. In this paper, when other navies adopt integrated masts on new ships, types of antennas, according to the cases that the antennas are integrated on the integrated mast or not, are analyzed. Also the types of antennas and transmission techniques for the radio communication equipments of the Korean Navy are analyzed in various frequency bands. For adopting an integrated mast on Korean new ships, the effects of the ship RCS according to the types of antennas, the possibility of integration the antennas and the integrated mast and considerations were presented.

• The Bulletin of The Korean Astronomical Society
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• 제37권2호
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• pp.152.2-152.2
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• 2012

우주발사체 발사를 위해서는 발사대시스템 개발이 필수적이다. 발사대시스템은 기계설비와 추진제공급설비, 관제설비로 구성되며, 그 중 기계설비는 발사지지대(Launch Pad), 이렉터(Erector), 트랜스포터이렉터(Transport-Erector), 케이블마스트(Cable-mast), 자동체결장치(Auto-coupling Device) 총 다섯 부분으로 나눌 수 있다. 발사지지대는 발사 전까지 발사체를 지지하는 구조물로 발사체의 안전을 보장하고 공급배관 및 통신라인의 경로를 제공한다. 이렉터는 발사준비과정에서 수평으로 이송된 발사체를 2개의 대형 유압실린더를 사용하여 기립시키는 장비로 발사 취소 시 발사체를 수평으로 전환한다. 트랜스포터이렉터는 조립공간에서 조립을 마치고 최종점검이 완료된 발사체를 전용차량을 이용하여 발사대로 이동하고 발사체를 안전하게 잡아준다. 자동체결장치는 지상으로부터 발사체로 연결되는 추진제, 압축가스 등의 연결배관을 자동으로 연결/분리하는 장치이다. 케이블마스트는 우주발사체 상단부의 UCU-E(Umbilical Connectors Unit-Electrical)를 통해서 전기, 고압가스, 고온공기 등을 공급하기 위한 통로로 발사 전까지 발사체시스템과 지상장비와의 통신수단이다. 또한 발사체로 연결되는 라인들을 발사 시에 나오는 후류에 의한 충격으로부터 보호하고, UCU-E가 기계적으로 분리되도록 구성되어 있다. 본 논문은 기존에 적용된 케이블마스트에 대한 구성, 기능 및 운용절차에 관한 것으로, 현재 진행 중인 한국형발사체 개발을 위한 기초 자료조사로 활용하고자 한다.

• Journal of the Korea Institute of Military Science and Technology
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• 제27권5호
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• pp.581-587
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• 2024

The mast structure of a naval ship has a lot of expensive equipment attached and is easily exposed to strong vibration due to its structural characteristics, so it is necessary to manage vibrations well to prevent equipment failure and increase operating time. Since September 2015, the Navy has been managing the vibration of the ship's mast structure with a separate tolerance standard from the local vibration, but this standard is set at 1/2 of the vibration limits for mast-mounted equipment without any engineering basis. So the establishment of new vibration limits based on the operating conditions of naval ships is required. In this study, the mast structure vibration limits were reviewed considering the actual operating time of naval ships, and the results were compared with the standards of major overseas classification societies and the actual measurements of a ship that had mast structure vibration problems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제20권7호
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• pp.625-630
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• 2009

In this paper, we introduce the analysis and counter-measure of signal distortion of search radar equipped on the ship. Using ShipEDF program, the search radar's main antenna and ship structures are modeled in the view of electromagnetism. Ray tracing method is used for analysis of the search radar's radiation patterns in free space and ship condition. From analyzed radiation patterns, we can conclude that the search radar's signal distortion is due to radiation pattern distortion. We also analyze the surface current distribution of the mast to propose the counter-measure to reduce electro-magnetic field reflection of mast.

• Journal of the Korean Society of Marine Environment & Safety
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• 제23권6호
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• pp.746-753
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• 2017

Radar Cross Section (RCS) is a factor directly related to survivability, and a design to reduce the presence of this factor is needed. The upper structure, guns, radar and so on are related to warship RCS, but radar RCS reduction is difficult because of complex shapes involved. In this paper, an enclosed mast, which is one modern method for reducing radar RCS, and the characteristics of an applied Frequency Selected Surface (FSS) are analyzed. The RCS reduction ability of an enclosed mast has been confirmed by comparing RCS analysis results for a general radar with that of an enclosed mast for available frequency according to FSS shape. The characteristics of the enclosed mast have also been studied by analyzing the elevation angle and slope of the mast. General radar RCS was high because of its complex shape, but low RCS was shown for the enclosed mast model, which had a simpler shape.

• The Journal of Korean Institute of Information Technology
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• 제16권11호
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• pp.51-59
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• 2018

The Multi-Mission Unmanned Surface Vehicle(MMUSV), which is manufactured using glass Fiber Reinforced Plastic(FRP) material, is designed to perform a surveillance and reconnaissance on the sea. Various navigation sensors, such as RADAR, RIDAR, camera, are mounted on a mast to perform an autonomous navigation. And a dummy gun is mounted on the deck of the MMUSV for a target tracking and disposal. It is necessary to analyze a strength for structures mounted on the deck because the MMUSV performs missions under a severe sea state. In this paper, a strength analysis of the mast structure is performed on static loads and lateral external loads to verify an adequacy of the designed mast through a series of simulations. Based on the results of captive model tests, a strength analysis for a heave motion of the mast structure is conducted using a simulation tool. Also a simulation and fatigue test for a mounting part between the MMUSV and the dummy gun are performed using a specimen. The simulation and test results are represented that a structure of the mast and mounting part of the dummy gun are appropriately designed.he impact amount are performed through simulation and experiments.

• Journal of IKEEE
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• 제24권1호
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• pp.238-242
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• 2020

This paper presents a technique using a multilayered dielectric coating to reduce the radar cross section (RCS) value of an integrated mast mounted in a destroyer. The proposed multilayer structure has the advantage of being easy to fabricate because the dielectric constant is defined so that a general dielectric that does not contain a magnetic component that requires high dielectric constant or is frequently used for blocking electromagnetic wave absorption can be used. After applying the proposed multi-layer dielectric structure to the integrated mast shape, the simulation results show that the RCS reduction performance is 10.9dB at 6GHz, 11.95dB at 12GHz, and 11.63dB at 18GHz compared to the structure without the multilayer structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.108-108
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• 2009

The main object of this research is to minimize the shock effects which frequently result in fatal damage in wind met mast on impact of barge. The collision between wind met mast and barge is generally a complex problem and it is often not practical to perform rigorous finite element analyses to include all effects and sequences during the collision. LS-dyna generally purpose explicit finite element code, which is a product of ANSYS software, is used to model and analyze the non-linear response of the met mast due to barge collision. A significant part of the collision energy is dissipated as strain energy and except for global deformation modes, the contribution from elastic straining can normally be neglected. On applying impact force of a barge to wind met mast, the maximum acceleration, internal energy and plastic strain were calculated for each load cases using the finite element method and then compare it, varying to the velocity of barge, with one varying to the thickness of rubber fender conditions. Hence, we restrict the present research mainly to the wind met mast and also parametric study has been carried out with various velocities of barge, thickness of wind met mast, thickness and Mooney-Rivlin coefficient of rubber fender with experimental data. The equation of motion of the wind met mast is derived under the assumption that it was ignored vertical movement effect of barge on sea water. Such an analyzing method which was developed so far, make it possible to determine the proper size and material properties of rubber fender and the optimal moving conditions of barge, and finally, application method can be suggested in designing process of rubber fender considering barge impact.

• Journal of Korean Society of Steel Construction
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• 제18권6호
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• pp.697-706
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• 2006

Tower crane's wall tie is generally used for extending of mast height according to rising of lifting height. In order to get wall tie member force this problem, this study concerning wall tie is based on load data described in manual book of 290HC model. This study made the equation of wall tie member force and computer programming for calculating wall tie member force and then get ${\theta}-P$ curves(angle-wall tie force). After considering the ${\theta}-P$ curves, optimum angle range ($48.4^{\circ}{\sim}77.2^{\circ}$) about wall ties (A), (C) members was obtained. Member force of wall tie (B) was changed from tension to compression or from compression to tension at $74^{\circ}$ in service and $54^{\circ}$ in out of service. When both horizontal force($H_A$) and torsional moment ($M_D$) were varied from (+) to (-), wall tie force(A, B, C) were changed almost symmetrically about ${\theta}$-axis. Because this study was based on wall tie analysis conditions, wall tie members in symmetric and ideal geometry shape used for analizing wall tie of tower crane, it is necessary to have more careful verification in order to apply generally the results of this study.