• Journal of Conservation Science
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• v.36 no.6
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• pp.475-482
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• 2020

In this study, we synthesized rosin-based epoxy resin and manufactured two components adhesives and epoxy putty using this epoxy resin. This study manufactured main element of adhesives for enabling it to form epoxide group by letting epichlorohydrin react to maleic anhydride modified rosin, and used room temperature curing type triethylenetetramine for hardener. The ratio between main element and hardener of of manufactured adhesives was 100 : 20, and main element and hardener of filling material were manufactured as clay type by mixing them with filler. Manufactured undiluted adhesives and filling material showed very stable result in the adhesive strength (3.06 MPa) and ultraviolet irradiation, showing outstanding result comparing to existing restoration adhesives. And it is considered a material having reversibility as it was dissolved in organic solvents such as acetone and toluene after being hardened, which showed a result that solved part of possible problems caused by restoration. As a result of use and application of manufactured adhesives and filling material for actual wood crafts, they showed excellent results in workability, stability, removability etc., and this study confirmed that the material can be used for and applied to various fields.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.234-234
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• 2015

Metallic microwires are a promising material for use as a filler in various conductive composite structures. Because of their high anisotropy in shape, a low percolation threshold could be achieved, which is beneficial to a low-cost fabrication and better electrical conductivity even under an extremely low solid content. Here we developed a facile method to fabricate the Cu (core)-Ni (shell) microwires.

• Journal of Welding and Joining
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• v.12 no.2
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• pp.39-48
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• 1994

In comparison to the conventional brazing, laser welding of ceramics has advantages of direct bonding without filler material, which causes the thermal stress due to the differences of thermal expansion coefficients. In pulse-mode, laser welding of dispersion ceramic having high thermal resistance is possible at relatively low preheating temperature of $1300^{\circ}C$ In CW-mode, alumina can be welded at high preheating temperature $1500^{\circ}C$ under the condition of low feed rate of 500 mm/min, respectively. Further studies on developing mechanism of pores in the bead during laser welding of ceramics is required.

• 한국기계연구소 소보
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• s.20
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• pp.105-114
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• 1990

The relationship between the properties of two kinds of calcined cokes and graphitized forming bodies were examined. The microstructures of the forming bodies are already determined to some degree at the stage of baking. Calcined cokes as well as baked forming bodies using the same coke as filler were heat treated at various temperatures and their structural and properties changes with heat treated temperature were studied. The transition in properties changes with heat treatment in forming bodies were observed around $2000^{\circ}C$. The characteristics of the finial graphite bodies are strongly dependent on the properties of the raw material cokes.

• Journal of Welding and Joining
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• v.30 no.3
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• pp.21-25
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• 2012

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.4
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• pp.130-140
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• 2017

Lightning protective design of an aircraft fuel system is closely related to the safety of the flight. Recently, composite material in building an aircraft becomes more important because it can reduce the weight of the aircraft. The composite materials decrease the protection against the effect of lightning. Lightning protective design of metal material aircraft has been researched for a long time and the design technique has been announced widely. However, research on the lightning protective design using composite material aircraft is very limited. In this study, lightning protective design for fuel tank structural component, access cover, fuel filler cap and drain valve in carbon fiber composite material aircraft have been presented. To show the compliance with FAA airworthiness standard regarding the presented protection designs, three steps, including lightning strike analysis, lightning environment analysis and certification test, were conducted in accordance with FAA AC 20-53.

• Journal of Forest and Environmental Science
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• v.14 no.1
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• pp.89-100
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• 1998

The study was carried to investigate the change of internal stress and physical properties of paper by the mutiplying of paper structuring that is an useful means to maximize the performance and use of the fiber raw material. The effects of recycled fiber on the physical properties of multiplied paper also were studied. The beating increased the internal stress of single layered paper, while filler loading decreased the internal stress. Multiplying the structure of paper decreased the internal stress and the most of physical properties except for tear index. It was found that the properties of paper could be changed by the pulp type, beating and the combination of raw materials. The introduction of filler in the middle and/or outer layer could improved the internal stress, tensile index, tear index and burst index. The addition of recycled fiber increased the opacity and stiffness of paper in both single layered and multiplied paper. Multiplying the structure of paper improved the air permeability and stiffness, while decreased burst index.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8679-8683
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• 2015

Using a surface modification technique, ion beam assisted deposition (IBAD) of Ti thin film it becomes possible to prepare an active ceramic surface to braze $Al_2O_3$-STS304 with conventional Ag-Cu eutectic composition filler metal. Researches on bonding formations at interfaces of ceramic joints were mainly related on the development of filler metals to ceramic, the process parameters, and clarifications of reaction products. From the results, the reactive brazing is a very convenient technique compared to the conventional Mn-Mo method. However melting point of reactive filler is still higher than that of Ag-Cu eutectic and it forms the brittle inter metallic compound. Recently several new approaches are introduced to overcome the main shortcomings of the reactive metal brazing in ceramic-metal, metal vapor vacuum arc ion source was introduced to implant the reactive element directly into the ceramics surface, and sputter deposition with sputter etching for the deposition of active material.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.1002-1008
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• 2001

The absorbing structure composed of multi-layered fiber reinforced composite materials was designed and microwave absorbing properties are investigated. On the basis of transmission line theory, the theoretical equations to predict the reflection loss and the appropriate composite material for each functional layer are suggested. The most significant result of this study is the successful design and fabrication of triple-layered composite laminates which has the superior microwave absorbing porperties (more than 10 dB in 4∼12 GHz range), without using the ferrite filler in the impedance transforming layer. In the two-layered composite laminate (absorber/substrate), however, the use of ferrite filler (about 40 wt %) in the absorbing layer is necessary to obtain the certain level of microwave absorbance. By combining the glass-fiber composite with ferrite filler and carbon-fiber composite substrate, the microwave absorbing properties more than 10 dB in 4∼12 GHz frequencies than be obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.423-429
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• 2007

The clock recovery module of gap filler for satellite DMB is proposed. Proposed module sustains the output frequency of 10 MHz whether the received signal from the satellite is unstable or cut off within 0.5 sec. The advantages of this module is without frequency tuning at regular interval and low material cost. This module is fabricated by using CPLD as clock recovery IC and new type of loop filter for satisfying the fast lock time and long hold over time simultaneously. The measured performance of the fabricated module has a holdover time of 11 sec at frequency stability less than 0.01 ppm, and phase noise of -113 dBc/Hz at 100 Hz offset.