• Journal of the Korean Geotechnical Society
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• v.27 no.11
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• pp.83-92
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• 2011

The random and heterogeneous pore structure is a significant factor that dominates physical and mechanical behaviors of soils such as fluid flow and geomechanical responses driven by loading. The characterization method using non-destructive testing such as micro X-ray CT technique which has a high resolution with micrometer unit allows to observe internal structure of soils. However, the application has been limited to qualitatively observe 2D and 3D CT images and to obtain the void ratio at macro-scale although the CT images contain enormous information of materials of interests. In this study, we constructed the 3D particle and pore structures based on sequentially taken 2D images of glass beads and quantitatively defined complex pore structure with void cell and void channel. This approach was enabled by implementing image processing techniques that include coordinate transformation, binarization, Delaunay Triangulation, and Euclidean Distance Transform. It was confirmed that the suggested algorithm allows to quantitatively evaluate the distribution of void cells and their connectivity of heterogeneous pore structures for glass beads.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.120-126
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• 1999

;The consicErations for reminder life of transmission line is gradually higher. It is requisite for investigation of ACSR's life to test tensile load of ACSR as a fundamental data. It is vary important to analysis correlations between results of tensile load testing and elasped years. Estimation of ACSR's life can be obtained by statistics processing using mechanical experirrental results. It is a general method to use regression analysis as a statistics processing technique. In this paper, we did experiment on tensile strength of ACSR by using a new and old ACSR as sample experirrental materials. The limit of life estimation is decided by basic line using twenty percentage reduction of rate tensile strength. This basic line is like to results of Canada Ontario Hydro-research. There are $95[\textrm{mm}^2]$, $97[\textrm{mm}^2]$, $120[\textrm{mm}^2]$, $240[\textrm{mm}^2]$ ACSRs which are experimented on this study. 1be life estimation of these ACSR is presented by table 1 to be obtained through the linear regression and nonlinear regression analysis. SPSS and statistics toolbox of matlab is used for analysis.lysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.1
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• pp.23-29
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• 2016

In this paper, in order to quantify the peristalsis occurrence in a guinea pig's large intestine, a miniaturized air-gap capacitive pressure sensor was fabricated through micro-electro-mechanical system (MEMS). The proposed pressure sensor is a two-layered biocompatible polyimide substrate consisting of an air-gap capacitive plates between the substrates. The proposed pressure sensor was designed with a careful consideration of the structure and motility mechanism of the guinea pig's large intestine. Artificial pellets were mounted on a prototype pressure sensor to provide some redundancies in the form of size and shape of the guinea pig feces. Capacitance of a prototype sensor was recorded to be 2.5 ~ 3 pF. This capacitance value was later converted to count value using a lab fabricated data conversion system. Sensitivity of the pressure sensor was recorded to be below 1 mmHg per atmospheric pressure. During in vivo testing, artificial peristalsis caused by drug injection was measured by inserting the prototype pressure sensor into the guinea pig's large intestine and pressure data obtained due to artificial peristalsis was graphed using a labview program. The proposed pressure sensor could measure the pressure changes in the proximal, medial, and distal parts of the large intestine. The results of the experiment confirmed that pressure changes of guinea pig's large intestine was proportional to the degree of drug injection.

• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.33-41
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• 2001

Wire ropes have been widely used in industrial applications, wherever heavy weight should be carried safely or mechanical energy should be transmitted fast. Especially, wire rope failures in operating elevator may lead to extensive property damage and serious injury to nearby personnel. Hence, it is very important to inspect wire rope periodically. Failure defection of wire rope requires fundamental knowledge of wire rope construction, rope behavior, properties of fault, sensing and signal processing method. In this research, the development of a new fault detecting system incorporating Hall-effect sensors to detect flaws such as abrasion, broken wire, corrosion and deformation for aged wire ropes in elevator, is described. For using a detector as a portable instrument, several performances for implementing sensing part with Hall-effect sensor, analog signal processing unit and programs are described. Experiments and field testing results for the implemented detecting system are also given. As a result, it is verified that the detecting system has good efficiency for inspecting faults of aged wire ropes in service.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.7
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• pp.70-75
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• 2014

The experiment was done on traveling at the speed of 20km/h, 60km/h and 100km/h using the performance testing mode for chassis dynamometer. The experimental method were employed to measure the waveform of secondary ignition coil and exhaust emission. In this experiment, the correlation between the secondary waveform coming from ignition coil and exhaust emission were measured in decrepit vehicle. The secondary waveform characterized by the value of effective discharge energy. The following results are obtained by analyzing the data relativity between the effective discharge energy and exhaust emission. The variation rate of effective discharge energy was largest 60km/h, 20km/h, 100km/h velocity in the ordered named. As the vehicle velocity increases, the average variation rate of CO and $NO_X$ decreases and that of HC and $CO_2$ decrease. The value of effective discharge energy, CO, $NO_X$ and fuel consumption is measured badly in case of car with failures in MAP, spark plug and good in case of car with before and after maintenance regardless of vehicle velocities. The value of effective discharge energy is to be nearly parabolic shape as vehicle velocity increases. As the value of effective discharge energy increases, the value of $NO_X$, HC and $CO_2$ decrease, the value of CO increase. The most sensible factors of exhaust emission were CO, $NO_X$, and the small variation factors were HC, $CO_2$.

• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.391-400
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• 2012

Recently, the construction industry commonly uses FRP as a reinforcement material because of its material advantages. FRP attached reinforcement has various advantages such as high strength, stiffness, excellent durability and construction practicability comparing to its weight. However, external attachment of FRP is water-tighted with low water permeable material, not draining water, probably causing damages on a permanent structure. The study manufactured it through pultrusion and examined GP(glass fiber panel) of which material-mechanical properties are almost same as the existing FRP but durability and attachment performance are better by stationary experiments, testing load-deflection curve, destruction types and load-deflection relation under repetitive loading test. As a result of 2,000,000 fatigue tests, it did not result in the destruction and showed excellent permanent attachment and durability as it displays significantly low compressive strain of concrete.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6282-6288
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• 2014

$CO_2$ welding is used widely in the field. On the other hand, welding defects occur when welders cannot adjust the current and voltage needed for welding and have to stop working to adjust the current and voltage, causing sudden cooling down of the welding structure inside a vehicle or tank where the control panel is invisible or when work site is far. This study used three types of existing $CO_2$ welders. This also applied SS400 rolled steel for welding structural purposes for remote control torch welding, perform a welding test through v-groove butt welding with a remote control torch and existing $CO_2$ welding torch, conducted visual inspection on the appearance of a welded top bead. In addition, the appearance quality of the welding part was monitored mainly through penetrant testing and a bending test to evaluate the welding defect reduction and the effect on the performance and compatibility by replacing the existing welder.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.111-119
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• 2016

Rebound hammer test, SonReb method and concrete core test are most useful testing methods for estimate the concrete compressive strength of deteriorated concrete structures. But the accuracy of the NDE results on the existing structures could be reduced by the effects of the uncertainty of nondestructive test methods, material effects by aging and carbonation, and mechanical damage by drilling of core. In this study, empirical procedure for verifying the in-situ compressive strength of concrete is suggested through the probabilistic analysis on the 268 data of rebound and ultra-pulse velocity and core strengths obtained from 106 bridges. To enhance the accuracy of predicted concrete strength, the coefficients of core strength, and surface hardness caused by ageing or carbonation was adopted. From the results, the proposed equation by KISTEC and the estimation procedures proposed by authors is reliable than previously suggested equation and correction coefficient.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.1-8
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• 2010

This study is performed to evaluate the physical and mechanical characteristics of an acryl polymer concrete that is developed as an overlay material for cement concrete slabs and pavements. Various laboratory tests including viscosity, flow, compressive strength, flexural strength, tensile strength, linear shrinkage, thermal expansion and thermal compatibility tests are performed. It is observed from the laboratory tests that the acryl polymer concrete developed in this study satisfies all the requirements suggested by ACI guideline. In addition to the laboratory tests, an accelerated performance testing (APT) is conducted to validate the performance of the acryl polymer concrete. During the APT, no significant distresses are observed until 15,903,939 cycles of equivalent single axle loading is applied. Finally, a 10mm thick overlay with the acryl polymer concrete is applied on top of an old deteriorated concrete pavement to evaluate field performance. Right after the field construction, skid resistance, noise and roughness are measured. The skid resistance and noise level have been significantly improved while the roughness is increased. Periodic investigation for the field study section will be conducted to evaluate the long-term performance.

• Journal of Sericultural and Entomological Science
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• v.35 no.1
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• pp.52-59
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• 1993

Raw silk degumming, by which the sericin and other marterials are eliminated from fibroin, is very essential process to produce silk fabrics. Alkali chemicals and enzymes have been used for the silk-degumming process. In this paper, the effect of heat treatment was investigated on silk fibers degummed by two different methods, soap and enzymatic degumming method. The difference between these two degumming methods was analyzed on the basis of results of mechanical testing, thermal analysis and intrated spectroscopy. The tenacity and the elongation of silk fiber are decreased by the heat-treatment in wet state. This tendency is observed in both cases of two degumming methods. The peak temperature in DSC analysis, which is attributed to thermal decomposition of silk fiber, was shifted to higher value with the heat-treatment temperature for the soap degummed silk fiber, however, it was not for the enzymatic degummed one. The IR crystallinity of soap digummed silk fiber is increased with the heat-treatment temperature, while that of enzymatic degummed fiber is not.