• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.535-543
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• 2017

For column-beam gussets of wooden structures, slit-processed members inserted with a steel plate are used in general. In this study, a rigid portal frame bonded with a joint was fabricated and a semi-rigid portal frame was fabricated by making a wooden gusset, a replacement for steel plate, of which a half was integrated into the column member and the other half was joined with the beam member by drift-pins. The lateral strength performance of the wooden portal frame was compared with that of the steel plate-inserted joint portal frame. The lateral strength performance was evaluated through a perfect elasto-plasticity model analysis, sectional stiffness change rate, and short-term permissible shear strength. As a result of the experiment, the maximum strength of the rigid portal frame was lower than that of the steel plate-inserted joint portal frame. The yield strength and ultimate strength were calculated as 0.58 and 0.48, respectively, but the measurements of initial stiffness and cumulative ductility improved by 1.35 and 1.1, respectively. As a result of the perfect elasto-plasticity model analysis of the semi-rigid portal frame, the maximum strength was lower than that of the rigid portal frame, but the toughness after failure was excellent. Thus, the ultimate strength was higher by 1.05~1.07. The steel plate-inserted portal frame showed rapid decrease in stiffness with the progress of repeated tests, but the stiffness of the portal frames with a wooden joint decreased slowly.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.301-308
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• 2014

Despite Korea forest take 63.7% of the nation's territory, productivity of domestic structural lumber is low. Studies of domestic small lumbers need to be improved domestic structural timber productivity. In this study, small diameter lumber and finger joint small diameter lumber took bending test to calculate MOE and MOR. MOE of small diameter lumber was $9.3kN/mm^2$ and MOE of finger joint small diameter lumber was $15.4kN/mm^2$. Allowable standard bending stress of small diameter lumber and finger joint small diameter lumber was calculated according to ASTM D 2915. Standard allowable bending stress of small diameter lumber was $12N/mm^2$ and standard allowable bending stress of finger joint small diameter lumber was $11N/mm^2$. Standard allowable bending stress of finger joint small diameter lumber should be considered to design structural beam members.

• Journal of Korean Association for Spatial Structures
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• v.5 no.4 s.18
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• pp.71-77
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• 2005

Bonded CFRP Plate method used murk in reinforcement method is very efficient for stress increment of reinforced members. But CFRP plate dosen't display enough its capacity and have the destruction characteristic of premature failure that reach failure by debond plate, because near-surface-bond using epoxy. Such destruction character of reinforced specimens take the influence at variables as steel reinforcement ratio, concrete strength, kind of reinforcement materials, reinforced length, property of epoxy used in binder and so on. In this study, performed experiment results are compared and considered on flexural performance of Near Surface Mounted Reinforcement used CFRP-Rod, as complement about structural behavior of RC beam reinforced flexural capacity in CFRP plate and premature failure of reinforcement material. Main variables of RC beam applied CFRP Plate external bond method are experimental variables as reinforcement length, reinforcement position (tension face and side face of beam) and existence of ironware in end parts. In case of CFRP-Rod, variable is reinforcement length.

• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.140-145
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• 2000

This paper was composed with fatigue test of the cruciform specimens, as load carrying and non-load carrying type. It also has performed computational analyses for geometric condition of the fillet welding bead. As test results, the effect of stress ratio in the specimen was insignificant. Stress ranges were varied with R=0.1~0.2. The fatigue cracks that were found in the load carrying type specimens and most specimens welded with contact were developed at the end of welds. The fatigue strength of specimen that have fractured in maternal plate was found about ${\Delta}\sigma_c$=63.5MPa. It's about 24% less than that of the non-load carrying type specimens having about ${\Delta}\sigma_c$=83.8MPa. A category of the Fatigue design specifications which provide for cruciform details was defined grade C as a stress of the maternal member. And then, the fatigue strength to be transformed into the maternal stress was found about 78.27 MPa, it tends to be less than that of allowable fatigue strength.

• Journal of the Society of Disaster Information
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• v.11 no.2
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• pp.235-243
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• 2015

The methods to improve the protection and explosion-proof performance of concrete structures include the backside reinforcement or concrete material property improvement and the addition of structural members or supports to increase the resistance performance, but they are inefficient in terms of economics and structural characteristics. This study is about the basic study on the fiber composite panel cover, and the nano-composite material and adhesive as the filler, to maximize the specific performance of each layer and the protection and explosion-proof performance as the composite panel component by improving the tensile strength, light weight, adhesion and fire-proof performances. The fiber composite panel cover (aramid-polyester ratios of 6:4 and 6.5:3.5) had a 2,348 MPa maximum tensile strength and a 1.8% maximum elongation. The filler that contained the nano-composite material and adhesive had a 4 MPa maximum tensile shear adhesive strength. In addition, the nano-composite filler was 30% lighter than the normal portland cement

• Journal of Conservation Science
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• v.26 no.4
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• pp.361-370
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• 2010

The open pore of stone cultural heritage is not expected to have an effect only by consolidation, and it has a drawback that only the internal wall adheres and gets consolidated due to the incrase of liquidity caused by the low viscosity and difference of materials in the case of filling with high molecules synthetic resins. Therefore, this research selected the effective filler for Three-storied Stone Pagoda at the West of Gameunsaji Site through the verification of filling effects of materials using the information about various fillers based on minerals. As the result of filler experiment, got filled with the combination of KSE 500 STE + KSE Filler A${\cdot}$KSE Filler B that is the same as the Member or has very similar properties. The total surface area of the west stone is $252.6m^2$ and the area where the internal opening has been developed is $17.77m^2$(7.03%) requiring a task that fills the internal($24,885m{\ell}$).

• Conservation Science in Museum
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• v.14
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• pp.91-113
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• 2013

Cheongpung Buwongun Kim Wu-myeong's Funeral Bier, an important folklore cultural property No.120, possessed by Chuncheon National Museum was donated in 2002 (by Kim Seonggu). It consists of a bier, yoyeo(腰輿), myeongjeongdae(銘旌臺), and manjangdae(輓章臺). It has a high value as the oldest royal bier. The bier which had a resting time in the storage for special exhibition of "The great cultural treasure of Gangwon province" was inspected in September 2012 and colored pigment layer of the wooden part had the risk of peeling off and surface damage of the textile was serious. Therefore, conservation treatment was conducted. In addition, knots and susiks(垂飾) were severely damaged and their exhibition was impossible. Therefore, a reproduction to replace them through a close investigation was made. All parts of the funeral bier were in separation except for the basic furniture. Conservation was made by dividing the parts into wooden parts and textile parts. Yoyeo was reinforced after disassembling bujae from it and then was reassembled. Paraloid B-72 2 wt% (in ethyle acetate), acrylic resin, was applied to the wooden part of the bier in order to reinforce the colored pigment layer with the addition of sodium alginate 2 wt%(in stilled water) and glue 4 wt%(in stilled water). The pollutants on the surface of the textile part were removed (vacuuming) and its creases were smoothed out (steaming). Fat-soluble pollutants were removed using an nonionic surfactant(Saponin, concentration at 0.25 to 0.5 g/𝑙, in de-ionized water). After the disassembly of the yoyeo from the broken wooden, it was bonded with glue (3 wt% for the first gluing, 35 wt% for gluing), and pine wood was used to restore missing parts. In the process of connecting Wongak(雲角), the original metal hinge and nails were reused to complete the assembly.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.212-228
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• 2013

Stone cultural heritages are repaired by the use of metal stiffeners. The problem is that this type of repair has been based on the experience of workers without specific guidelines and has caused various problems. This is to suggest the structural reinforcement and behavioral characteristics of metal rods to minimize the secondary damage of materials and have the specimens tested and verified to establish the guidelines on how to insert metal stiffeners. When only epoxy resin is applied to the cut surface, only 70% of the properties of the parent material are regenerated and it is required to structurally reinforce the metal stiffener for the remaining 30%. The metal rod is under the structural behavior after the brittle failure of stone material and the structural behavior does not occur when the metal stiffener is below 0.251%. When it accounts for over 0.5%, it achieves structural reinforcement, but causes secondary damage of parent materials. The appropriate ratio of metal stiffener for the stone material with the strength of $1,500kgf/cm^2$, therefore, should be between 0.283% and 0.377% of the cross section of attached surface to achieve reversible fracture and ductility behavior. In addition, it is more effective to position the stiffeners at close intervals to achieve the peak stress of metal rod against bending load and inserting the stiffener into the upper secions is not structurally supportive, but would rather cause damage of the parent material. Thus, most stiffeners should be inserted into the lower part and some into the central part to work as a stable tensile material under the load stress. The dispersion effect of metal rods was influenced by the area of reinforcing rods and unrelated to their diameter. However, it ensures stability under the load stress to increase the number of stiffeners considering the cross section adhered when working on large-scale structures. The development length is engineered based upon the diameter of stiffener using the following formula: $l_d=\frac{a_tf_y}{u{\Sigma}_0}$. Also, helically-threaded reinforcing rods should be used to perform the behaviors as a structural material.

• Journal of Conservation Science
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• v.37 no.5
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• pp.536-544
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• 2021

In the present study, safe management and value improvement of bamboo sunblind, which is an item of cultural heritage, were performed by adopting stable conservation treatment methods. The bamboo sunblind used in the present study was excavated from No. 1 catchment site in Baesanseongji, Busan. It was determined that the main material used to make the sunblind was bamboo, and herbal plants were used to weave the bamboo using lacquer as an adhesive agent. All contaminants and soil adhered to the sunblind was removed. Thereafter, the sunblind, which was recovered in the form of blocks, was washed separately after fixing it to a temporary plaster frame and to avoid the blocks from breaking during washing. Then, polyethylene glycol (PEG) impregnation was utilized for the reinforcement treatment. Based on the preliminary test results, the shape of the sunblind was fixed using a stainless-steel frame to prevent physical damage that may occur during the drying process. Thereafter, the bamboo sunblind was vacuum freeze-dried. PEG 20% (in ethyl alcohol) was applied as a surface treatment agent for stabilization the sunblind. After the surface treatment, the bamboo sunblind were joined together to fit the maximum width, and the rectangular shape of the sunblind was restored-as best as possible-while filling in the missing parts by maximizing the use of unknown members such as in the disturbed layers below bamboo sunblind surface. The conservation treatment was completed by fixing the bamboo sunblind into the fabricated frame.

• Korean Journal of Heritage: History & Science
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• v.48 no.4
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• pp.62-73
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• 2015

The Tae-Jo Geonwolleung is the tomb of the first king Tae-Jo of the Joseon Dynasty in the complex of the Royal Tombs of the Joseon Dynasty which is listed in World Heritage, and it contains various types of stone properties. The material of the stone properties consist of a single type of medium-grained biotite granite, however, each properties have different intensity and types in deterioration phenomena according to their locations and purposes. The major deterioration types of the stones are analyzed as physical decomposition and biodeterioration. The exfoliation, breaking-out and granular decomposition are widespread types of the deterioration throughout the entire burial mound stone properties and surrounding stone properties. On the other hands, the colonization of mosses and plants, and contamination by foreign materials are found more frequent in the burial mound stone properties as these stones are in contact with the soil of the tomb mound and moisture in the soil helped biodeterioration. It is suggested that anti-biology treatment and physical reinforcement are applied to the deteriorated stones to prevent further damage on the stone components of the tomb.