• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.1
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• pp.73-83
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• 1997

Most of the materials used in various industrial fields and also in our daily life are multi-component materials or composite materials, and it is well known that there are many cases where adhesion between the constituents within the bonded systems plays an important role. There are various types of performance evaluation tests for the bonded materials, among which tests for evaluating the bond performance under various conditions may be regarded as the most interesting ones for those engaged in work related to adhesion. I have studied on the mechanism of adhesion form the rheological standpoint with my colleagues, including some students from Korea, and I am very happy to be able to have a talk on some of our research works. In Japan, the so-called "adhesives" are usually classified into two categories;adhesives and pressure sensitive adhesives (PSA). Adhesives are the materials which solidify after bonding and are after used as the structural adhesives because the adhesive strength is comparatively strong. On the other hand, the pressure sensitive adhesives never solidify and are used as PSA tapes, labels or decals. About the adhesives, we have examined the dependence of adhesive strength(shear, tensile, peel) upon both temperature and rate of deformation, and found out some empirical rules which are applicable to most of the adhesive systems. We have also developed a simplified theory of adhesion, which is deseribed in terms of mechanical equivalent mode1 and a few failure criteria. Although some of the common rules can be accounted for according to this theory, it must be pointed out that a fracture mechanical approach ms inevitable especially in the region where the meehanical relaxation time of the adhesive is extremely large [W. W. Lim and H. Mizumachi]. About the pressure sensitive adhesives, we have studied on the PSA performance (peel, tack, holding power) as a function of both the viscoelastic properties and surface chemical properties of the materials, and found out some rules, and again we have developed a theory which deseribes the mechanism. And in addition, we have studied on the miscibility between linear polymers and oligomers, because PSA is generally manufactured by blending gums and tackifier resins. Many phase diagrams have been found and some of them have been analyzed on thermodynamic basis, and it became evident that the miscibility is a very important factor in PSA [H. J. Kin and H. Mizumachi]. In this presentation, I want to emphasize the fact that the adhesion performance is closely related to the structure/property of the adhesives.adhesives.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.369-376
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• 2003

In this paper, a nonlinear structural analysis for the composite structure composed of the spent nuclear fuel disposal canister and the 50㎝ thick bentonite buffer is carried out to predict the collapse of the canister while the horizontal symmetric sudden rock movement of 10㎝ is applied on the composite structure. This sudden rock movement is anticipated by the earthquake etc. at a deep underground. Elastoplastic material model is adopted. Drucket-Prager yield criterion is used for the material yield prediction of the bentonite buffer and von-Mises yield criterion is used for the material yield prediction of the canister(cast iron, copper). Analysis results show that even though very large deformations occur beyond the yield point in the bentonite buffet, the canister structure still endures elastic small strains and stresses below the yield strength. Hence, the 50㎝ thick bentonite buffet can protect the canister safely against the 10㎝ sudden rock movement by earthquake etc.. Analysis results also show that bending deformations occur in the canister structure due to the shear deformation of the bentonite buffer.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.839-844
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• 2024

This study analytically analyzed the impact of underground structure displacement behavior on track damage due to adjacent excavation work, ground deterioration, and changes in groundwater level. The concrete track that was the subject of the study was analyzed for sleeper floating track(STEDEF) and precast concrete slab track(B2S). Sleeper floating track is a track structure in which the concrete bed and sleepers are voided. precast concrete slab track is a track structure that induces the elastic behavior of the rail by assembling rails and fasteners using slabs. For numerical analysis, each concrete track, from rail to concrete bed, was modeled as three-dimensional elements. In addition, the displacement behavior of the underground structure was set as a variable to analyze the damage effect on the concrete bed. Using numerical analysis, the concrete bed stress due to uplift and subsidence was analyzed, and the level of crack effect was analyzed by comparing it to the tensile strength and shear strength. As a result of the analysis, it was found that the sleeper floating track was more vulnerable than the precast concrete slab track when the same uplift and subsidence occurred. In addition, uplift and subsidence, it was analyzed that the cracks range in the sleeper floating track was large.

• The Journal of the Petrological Society of Korea
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• v.6 no.2
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• pp.77-85
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• 1997

The Early Proterozoic reworked rock association occurs within the Preacmbrian high grade metamorphic rocks in the area of Daqingshan, Inner Molgolia. In this association, the various large scale ductile deformation belts, form a nappe structure where the foliation steeply dips to north and the lineation ($340^{circ}-30^{\circ}$) plunges at $45^{\circ}55^{\circ}$. This result indicates the subduction/extension with northern part thrusting over the southern part at high angle. The southern subducted microlithon has the characteristics of prograde metamorphism. The northern thrusted microlithon shows the evidence of retrograde metamorphism with decreasing pressure and increasing temperature. The main rock types of Early Proterozoic Moyites are biotite adamellite and syenogranites occurring in the form of small batholiths or stocks and alkali-feldspar granites in veins. The biotite adamellites are progressively contacted with the Archean and Early Proterozoic rocks and contain a great deal of enclaves of metamorphosed rocks, suggesting an anatexis origin. The geochemical characteristics of moyites show the typical features of anatexis granite. At middle to late Early Proterozoic time, the continent-continent collision formed the large scale thrusting and imbrication of Archean basement rocks. According to the mineral assemblage and thermobarometer of Paria et al. (1988) give the following P-T condition : up-faulted block; $700-710^{\circ}C$, 0.72-0.78 Gpa (early stage) and $600^{\circ}C$, 0.44 Gpa (late stage), footwall block; $620^{\circ}C$, 0.8 Gpa (early stage), $620-840^{\circ}C$, 0.64-0.45 Gpa (peak) and $620-630^{\circ}C$, 0.35Gpa (late stage). These results suggest a clockwise P-T-t path (jin et al., 1991, 1994). According to the depth-temperature model in the comperature subduction zone and the experimental data of Wyllie et al. (1983), we propose a tectonic-magmatic-thermal model to account for metamorphism-anatexis of moyite occurring in subduction-shear zone.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.191-205
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• 1997

Measurements on subsurface movement of the Songsanri tomb site including the Muryong royal tomb was conducted using a tiltmeter system for the period of 15 months form July 7, 1996 to September 30, 1997. Two coordinate tilt monitoring data shows the biggest movement rate of 2.3mm/m/yr toward south in the frontal wall(N-S tilt) of the Muryong royal tomb. Southward tilting of bricks above the southern fire place in the western wall of the Muryong royal tomb is a proof of southward tilting of the royal tomb since its excavation in 1971. The eastern wall of the Muryong royal tomb is also tilting toward inside the tomb with the rate of 1.523mm/m/yr. Furthermore, tilting rate of wall increases twice in rainy season. It is interpreted tbat infiltration of water into the tomb and nearby ground in rainy season results in dangerous status for the safety of tomb structure. On the whole, normal component tilting of the walls of the 5th tomb is large than its shear component. It shows a small displacement toward one direction without no abrupt change in its direction and amount of tilting. The tilting rate of walls of the 6th tomb is about 8.8mm/m/yr in the dry season which is much bigger than those of other tombs in rainy season. Deformation events of walls of the tombs are closely related to amount of precipitation and variation of temperature. In comparison with different weather conditions, tilting is much bigger during the period of rainy weather than sunny weather. It is interpreted that rainwater flew into the turm through faults and nearby ground. High water content in nearby ground resulted strength of ground. The tilting event of walls shows a hysterisis phenomenon in analysis of temperature effect on tilting event. The walls tilt rapidly with steep rising of temperature, but the tilted walls do not come back to original position with temperature falling. Therefore, a factor of steep increase of the temperature must be removed. It means the tomb have to be kept with constant temperature. The observation of groundwater level using three boreholes located in construction site and original ground represented that groundwater level in construction site is higher than that of original ground during the rainy season from the end of June to August. It means that the drainage system of the Muryong royal tomb is worse than original ground, and it is interpreted that the poor drainage system is related to safety of tomb structure. As above mentioned, it is interpreted that artificial changes of the tomb environment since the excavation, infiltration of rainwater and groundwater into the tomb site and poor drainage system had resulted in dangerous situation for the tomb structure. According to the result of the long period observation for the tomb site, it is interpreted that protection of the tomb site from high water content should be carried out at first, and the rise of temperature by means of the dehumidifier inside the tomb must be removed.