• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.585-592
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• 2005

Nowadays it has been strongly required to control emissions from vehicles specially in diesel engines because of increasing number of vehicle in korea. This research aims to provide with some of deterioration factors on vehicles for emissions characteristics and the test was done on an electronically controlled heavy-duty diesel engine under severe driving conditions such as 1200 driving hours, 220,000 km driving distance and a full load. Under various driving conditions, CO, HC, $NO_{x}$, PM and Soots emissions were estimated under D-13 mode and D-3 mode respectively. CO emission was not changed until 500 running hours, and as engine aging is progressed THC was not changed until 500 running hours but it decreased to about $33\%,\;NO_{x}$ decreased constantly but on the other hand PM increased up to $6.9\%$ during the aging process.

• 보존과학연구
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• s.30
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• pp.189-202
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• 2009

Ceramics from Taean shipwreck were studied to investigate the deterioration by soluble salts and desalination pattern according to each ceramic characterization. NaCl crystals were found as a crystal growth on the ceramic microstructure and deteriorated to push off the glaze layer of some Puncheong ware sample. As a result of monitoring the desalination pattern of ceramics for 74days, the earthenware sample with big pores and no glaze removed soluble salts so fast, but Puncheong ware and Whiteware samples removed lots of soluble salts slowly and continuously. Generally, it takes long time to remove soluble salts from porcelains, due to small pores and glaze, but the long-term desalination probably can cause the damage on the surface layer such like glaze. As some soluble salts still remains in the ceramic microstructures after desalination, it is very important to control and keep the relative humidity stable through the proper storage. There are various ceramic deterioration patterns by soluble salts. Therefore, it needs to select the desalination method of ceramics from shipwreck, considering the material characteristics and the production techniques.

• 보존과학연구
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• s.30
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• pp.93-102
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• 2009

This study was carried out to investigate the effect of artificial accelerated ageing treatment on the permanence of lining papers produced from Korea and Japan. As time gone by, organic cultural properties are affected by chemical and physical deterioration because of various factors including the conditions of preservation environment and their material properties. In the public historical storage or owned as private collections, are vulnerable to sever amages caused by poor preservation environment as well as by other natural factors. In this study, the deterioration behaviors of lining paper in optical & mechanical properties were discussed. Overall, lining papers produced from Korea showed lower reduction in mechanical strength properties compared to the lining papers produced from Japan.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.280-285
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• 2014

In order to evaluate the insulation deterioration in the stator windings of five gas turbine generators(137 MVA, 13.8 kV) which has been operated for more than 13 years, diagnostic test and AC dielectric breakdown test were performed at phases A, B and C. These tests included measurements of AC current, dissipation factor, partial discharge (PD) magnitude and capacitance. ${\Delta}I$ and ${\Delta}tan{\delta}$ in all three phases (A, B and C) of No. 1 generator stator windings showed that they were in good condition but PD magnitude indicated marginally serviceable and bad level to the insulation condition. Overall analysis of the results suggested that the generator stator windings were indicated serious insulation deterioration and patterns of the PD in all three phases were analyzed to be internal, slot and spark discharges. After the diagnostic test, an AC overvoltage test was performed by gradually increasing the voltage applied to the generator stator windings until electrical insulation failure occurred, in order to determine the breakdown voltage. The breakdown voltage at phases A, B and C of No. 1 generator stator windings failed at 28.0 kV, 17.9 kV, and 21.3 kV, respectively. The breakdown voltage was lower than that expected for good-quality windings (28.6 kV) in a 13.8kV class generator. In the AC dielectric breakdown and diagnostic tests, there was a strong correlation between the breakdown voltage and the voltage at which charging current increases abruptly ($P_{i1}$, $P_{i2}$).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.791-795
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• 2014

In this paper, in order to impart the aging condition of the parts, by configuring the cycle of temperature from low temperature was performed by applying the aging conditions for vehicle cockpit module. The reason for the selected modules of the cockpit vehicle parts, because the joint occurrence typical components of the room component is a first module and ceiling cockpit module. After setting the excitation profile using the BSR exciter only that this is for the module degradation after the initial and grasp the change in the dynamic characteristics of the modules based on the before and after deterioration may be made in the module, grasp the noise generating position I measured the noise and proximity. Was also visualized on the position of the joint is generated using a sound camera to objective results occurring where the joint is selected through subjective evaluation.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1758-1760
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• 1997

Automatic detection system to detect acoustic emission pulse and fractal dimension were developed, to observe tree deterioration phenomena in LDPE. The purpose of our work are to use acoustic emission system and fractal dimension and to investigate the treeing phenomena in polymeric insulation under applied AC voltage 11[kV] with an artificial needle-shaped void(1.5[mm]) using the above system. We analyzed and phase angle-acoustic emission pulse amplitude-deterioration time ($\Phi$-AEA-t) pattern and phase angle-acoustic emission pulse number-deterioration time($\Phi$-AEN-t) pattern using statistical operators such as skewness, fractal dimension. In this paper show that the correlation of $\Phi$-AEA-t, $\Phi$-AEN-t, fractal dimension using regression analysis by the method of least squares can be used to predict the breakdown just before the breakdown occurs.

• Wind and Structures
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• v.23 no.1
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• pp.19-43
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• 2016

In the present study, a new methodology is presented to study the ride comfort and bridge responses of a long-span bridge-traffic-wind coupled vibration system considering stochastic characteristics of traffic flow and bridge surface progressive deterioration. A three-dimensional vehicle model with 24 degrees-of-freedoms (DOFs) including a three-dimensional non-linear suspension seat model and the longitudinal vibration of the vehicle is firstly presented to study the ride comfort. An improved cellular automaton (CA) model considering the influence of the next-nearest neighbor vehicles and a progressive deterioration model for bridge surface roughness are firstly introduced. Based on the equivalent dynamic vehicle model approach, the bridge-traffic-wind coupled equations are established by combining the equations of motion of both the bridge and vehicles in traffic using the displacement relationship and interaction force relationship at the patch contact. The numerical simulations show that the proposed method can simulate rationally the ride comfort and bridge responses of the bridge-traffic-wind coupled system; and the vertical, lateral, and longitudinal vibrations of the driver seat model can affect significantly the driver's comfort, as expected.

• Computers and Concrete
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• v.4 no.1
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• pp.1-18
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• 2007

Over the past decades, an enormous amount of effort has been expended in laboratory and field studies on concrete durability estimation. The results of this research are still either widely scattered in the journal literature or mentioned briefly in the standard textbooks. Moreover, the theoretical approaches of deterioration mechanisms with a predictive character are limited to some complicated mathematical models not widespread in practice. A significant step forward could be the development of appropriate software for computer-based estimation of concrete service life, including reliable mathematical models and adequate experimental data. In the present work, the basis for the development of a computer estimation of the concrete service life is presented. After the definition of concrete mix design and structure characteristics, as well as the consideration regarding the environmental conditions where the structure will be found, the concrete service life can be reliably predicted using fundamental mathematical models that simulate the deterioration mechanisms. The prediction is focused on the basic deterioration phenomena of reinforced concrete, such as carbonation and chloride penetration, that initiate the reinforcing bars corrosion. Aspects on concrete strength and the production cost are also considered. Field observations and data collection from existing structures are compared with predictions of service life using the above model. A first attempt to develop a database of service lives of different types of reinforced concrete structure exposed to varying environments is finally included.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.200-203
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• 2005

Most of electrical fires are caused by short circuits, overheating of wires, deterioration and incomplete connection of wiring devices. The last two cases are predictable before the occurrence of fire because of its slow progress. In this paper, we have simulated the discharge signals caused by the deterioration and incomplete connection of wiring devices using an aged concent to provide information on the characteristics of discharge signals. From the experimental data, we could characterize the frequency spectrums of the discharge signals depending on the cases. The higher frequency components of the signal are attenuated by the capacitance and inductance of power lines as the measuring point is getting away from the discharges. Main frequency components of the discharge signal are existent at 600 kHz - 1.5 MHz in incomplete connections and at 210 kHz - 8 Mhz in deteriorations of the concent.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.71-77
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• 2010

The concrete structure's durability and integrity is reduced owing to various deterioration phenomena. Therefore, it is important to prevent the deterioration phenomena. This study inquired into the various experimental results of specimens with different dilution concentration and impregnation time by the each solution to present the economic and efficient using method of the inorganic surface penetration agents. As a results, the reasonable dilution concentration and impregnation time of colloidal silica solutions are 15% and 5 minute and for the sodium alumina silicate solutions are 17% and 10 second.