• Geomechanics and Engineering
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• v.19 no.2
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• pp.115-126
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• 2019

The long-term settlement characteristics for the cast-in-place bored pile in the deep-thick soft soil are investigated by post-grouting field tests. Six cast-in-place bored engineering piles and three cast-in-place bored test piles are installed to study the long-term settlement characteristics. Three post-grouting methods (i.e., post-tip-grouting, post-side-grouting, and tip and side post-grouting) are designed and carried out by field tests. Results of the local test show that decreased settlements for the post-side-grouted pile, the post-tip-grouted pile and the tip and side post-grouted pile are 22.2%~25.8%, 30.10%~35.98% and 32.40%~35.50%, respectively, compared with non-grouted piles. The side friction resistance for non-grouted piles, post-side-grouted pile, post-tip-grouted pile and the tip and side post-grouted pile undertakes 89.6~91.3%, 94.6%, 92.4%~93.0%, 95.7% of the total loading, respectively. At last, the parameters back analysis method and numerical calculation are adopted to predict the long-term settlement characteristics of the cast-in-place bored pile in the deep-thick soft soil. Determined Bulk modulus (K) and a creep parameter (Ks) are used for the back analysis of the long-term settlement of the post-grouted pile. The settlement difference between the back analysis and the measurement data is about 1.11%-7.41%. Long-term settlement of the post-grouted piles are predicted by the back analysis method, and the predicted results show that the settlement of the post-grouted pile are less than 6 mm and will be stable in 30 days.

• Textile Coloration and Finishing
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• v.34 no.1
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• pp.58-67
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• 2022

In this study, self-reinforced composite(SRC) was prepared using HDPE(High density polyethylene) fabric(2×2 plain) and LDPE(Low density polyethylene) film. The optimal conditions were derived by manufacturing specimens according to the temperature of 100 ~ 140℃ using a hot stamping at a pressure of 100bar for 10 minutes in order to find the optimal conditions for the SRC. The manufactured SRC was analyzed for tensile properties, compressive strength and shear strength through a universal testing machine(UTM). As a result of the measurement, the P3 specimen prepared by hot stamping at a temperature of 130℃ and a pressure of 100bar for 10 minutes was found to be higher than other specimens with tensile strength and tensile modulus of 210MPa and 19GPa, compressive strength 69MPa and shear strength 13MPa and it was considered to be optimal condition. Finally, the composite material according to the fabric structure was modeled using experimental values and the physical properties of the composite material according to the fabric structure were predicted using GeoDict and Digimat.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.33-38
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• 2021

Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiN_x thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiN_x thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiN_x thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiN_x thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiN_x thin films fabricated through the same deposition condition increased compared to the ~130 nm SiN_x thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.

• Journal of Adhesion and Interface
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• v.11 no.4
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• pp.149-154
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• 2010

Interfacial evaluation was investigated for single-carbon fiber/phenolic and carbon nanotube (CNT)-phenolic composites by micromechanical technique and electrical resistance measurement combined with wettability test. Compressive strength of pure phenol and CNT-phenolic composites were compared using Broutman specimen. The contact resistance of CNT-phenolic composites was obtained using a gradient specimen by two and four-point methods. Surface energies and wettability by dynamic contact angle measurement were measured using Wilhelmy plate technique. Since hydrophobic domains are formed as heterogeneous microstructure of CNT in the surface, the dynamic contact angle exhibited more than $90^{\circ}$. CNT-phenolic composites exhibited a higher apparent modulus than neat phenolic case due to better stress transferring effect. Work of adhesion, $W_a$ between single-carbon fiber and CNT-phenolic composites exhibited higher than neat phenolic resin due to the enhanced viscosity by CNT addition. It was consistent with micro-failure patterns in microdroplet test.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.92-97
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• 2002

A real-time OTF (optical transfer function) measuring system with on- and off-axis nodal slide bench type for the camera lens is fabricated and evaluated. It consists of a nodal slide bench including a T-bar for the OTF measurement of an off-axis object, two dimensional CCD (charge coupled device) with pixel of 9.9${\mu}{\textrm}{m}$$\times$9.6${\mu}{\textrm}{m}$ for real-time OTF measurment, and a collimating lens of focal length of 300 mm for the optimization of this system. The OTF system is corrected by using the OTF of a SIRA lens of fnumber of F/8 and focal length 50 mm. In order to confirm the reliability of the OTF system, two MTFs (modulus transfer functions) of CCTV & VIDEO lens (JAPAN, AVENIR-SE 2514) of focal length of 25mm and field of view 10.6$^{\circ}$are measured by the camera bench type OTF system of reference OTF system and the nodal slide bench type OTF system and compared with each other. As a result, these two values are agree well with each other within 4% from 0 1p/mm to 100 1p/mm.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.1
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• pp.65-75
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• 1990

There have been many methods for measuring the injection rate of diesel engines, but the results of them are not always identical and the reason for the discordance is not clear. Besides, a single shot injection equipment has been used for the fuel spray and the combustion research of diesel engines, but the results of experiment using the equipment don't apply to a volleyed shot injection of real engines. This paper investigates the merits and faults of the Bosch's method and the Zeuch's method, at the same, this paper also compares the injection rates of single shot inject rates of single shot injection and a volleyed shot injected by the Bosch's method. the results are summarized as follows: (1) The measurement error of the Bosch's method is about $\pm$1%, therefore, its accuracy is reliable. (2) By the Bosch's method, as the speed and the load of fuel pump increase, the injection rate becomes higher, on the contrary, the injection period(ms) shortens as the speed increases and the load decreases. (3) In this experiment, the injection rate of a single shot injection is lower than that of a volleyed shot injection under the same conditions. (4) The bulk modulus of elasticity using the Zeuch's method increases in proportion to the back pressure. (5) The Zeuch's method is less accurate than the Bosch's method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.208-215
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• 2018

The causes of column shrinkage and the codes that have been studied up to now are discussed. The documents mentioned in the code deal with the drying shrinkage, creep, compressive strength and elastic modulus of the specimen, and the elastic deformation calculated from the structural analysis. However, the deformation due to the temperature caused by the long term monitoring is less than that caused by the factors generated by the previous studies. In the previous studies, it was found that dehydration shrinkage, creep, and elastic deformation were not considered for temperature-induced deformation, while for the specimen experiments, the temperature-related items were replaced with the humidity-related terms The compensation value by the proposed equation showed error of 4.9 mm in the upper direction and 1.0mm in the lower direction when calculating column shortening, and it was found that its value by the proposed equation almost coincided with the measurement value in Site. Therefore, it is necessary to further study the temperature that can be omitted in calculating the existing column shortening, to consider the influence factors, and to supplement the criteria for the temperature measurement of the structure as well as the specimen tests.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.15.2-22
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• 1995

Evaluating stiffness of near-surface materials has been one of the critically important tasks in many civil engineering works. It is the main goal of geotechnical characterization. The so-called deflection-response method evaluates the stiffness by measuring stress-strain behavior of the materials caused by static or dynamic load. This method, however, evaluates the overall stiffness and the stiffness variation with depth cannot be obtained. Furthermore, evaluation of a large-area geotechnical site by this method can be time-consuming, expensive, and damaging to many surface points of the site. Wave-propagation method, on the other hand, measures seismic velocities at different depths and stiffness profile (stiffness change with depth) can be obtained from the measured velocity data. The stiffness profile is often expressed by shear-wave (S-wave) velocity change with depth because S-wave velocity is proportional to the shear modulus. that is a direct indicator of stiffiiess. The crosshole and downhole method measures the seismic velocity by placing sources and receivers (geophones) at different depths in a borehole. Requirement of borehole installation makes this method also time-consuming, expensive, and damaging to the sites. Spectral-Analysis-of-Surface-Waves (SASW) method places both source and receivers at the surface, and records horizontally-propagating surface waves. Based upon the theory of surfacewave dispersion, the seismic velocities at different depths are calculated by analyzing the recorded surface-wave data. This method can be nondestructive to the sites. However, because only two receivers are used, the method requires multiple measurements with different field setups and, therefore, the method often becomes time-consuming and labor-intensive. Furthermore. the inclusion of noise wavefields cannot be handled properly, and this may cause the results by this method inaccurate. When multi-channel recording method is employed during the measurement of surface-waves, there are several benefits. First, usually single measurement is enough because multiple number (twelve or more) of receivers are used. Second, noise inclusion can be detected by coherency checking on the multi-channel data and handled properly so that it does not decrease the accuracy of the result. Third, various kinds of multi-channel processing techniques can be applied to f1lter unwanted noise wavefields and also to analyze the surface-wavefields more accurately and efficiently. In this way, the accuracy of the result by the method can be significantly improved. Fourth, the entire system of source, receivers, and recording-processing device can be tied into one unit, and the unit can be pulled by a small vehicle, making the survey speed very fast. In all these senses, multi-channel recording of surface waves is best suited for a routine method for geotechnical characterization in most of civil engineering works.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.29-42
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• 1999

The SASW (Spectral-Analysis-of-Surface-Waves) method, which evaluates the stiffness structure of the subsurface and structures nonintrusively and nondestructively, has been successfully used in the civil engineering applications. However, the SASW method assumes that the subsurface or structures consist of horizontal multi-layers, so that the method has some difficulty in continuously evaluating the integrity of a tunnel lining and a pavement system. This difficulty prevents the SASW method from being used to generate a tomographic image of stiffness for the subsurface or structures. Recently, the GPR technique which has the advantage of continuously evaluating integrity of the subsurface and structures has been popular. This advantage of GPR technique initiated the efforts to make the SASW method, which is superior to GPR and other nondestructive testing methods due to its capability of evaluating stiffness and modulus, be able to do continuous evaluation of stiffness structure, and the efforts finally lead to the development of \ulcornerTomographic SASW Technique.\ulcorner Tomographic SASW technique is a variation of the SASW method, and can generate a tomographic image of stiffness structure along the measurement line. The tomographic SASW technique was applied to the investigation of lateral variability of a sand box placed by the raining method for the purpose of verifying its effectiveness. Tomographic SASW measurements on the sand box revealed that the investigated sand box has different shear stiffness along the measurement line, which gave a clue of how to make a better raining device.

• The Journal of Engineering Geology
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• v.14 no.1
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• pp.61-69
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• 2004

Building stones are used mainly as a material for making decoration and sculpture, and consequently they must have predominant physical properties extensively. Among various physical properties, the coefficient of pore dominates the usefulness of building stones, so the plans were made for establishing the quality classification of building stones with respect to the nature of pore. For this study, bore-hole core samples according to the depth of the biotite granites and the granitic gneiss were applicated. From the related chart between porosity and absorption ratio, Mungyeong granitic gneiss($Gn_1$) shows the widest phase of distribution in the range of measurement values, and the values decrease in the order of Pocheon granite($Gr_2$) and Mungyeong granite($Gr_1$) in the range. The strength of each rock mass varies with the degree of alteration. Also in correlation between compressive strength and tensile strength, the range of measurement values decrease in the order of $Gn_1$, $Gr_2$and $Gr_1$. Porosity is adopted as a representative physical property for establishing the quality classification of building stones, and then relative evaluation was made with regard to various physical properties. From the related chart between porosity(n)-specific gravity(G), absorption ratio(Ab), compressive strength(${\sigma}_{c}$), tensile strength(${\sigma}_{t}$), shore hardness(Hs) and Young's modulus($E_{t}$), standard of each grade is established.