• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.396-401
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• 1995

Epoxy coated reinforcing steels (ECRs) were acquired from ten sources and coatings from each source were initially characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in three aqueous solutions at elevated temperature (8$0^{\circ}C$) and in chloride-contaminated concrete slabs under outdoor exposure, It was found that the density and size of coating defects was the promary factor affecting ECR performance. The equivalent circuit analysis using electrochemical impedance spectroscopy (EIS) data indicated that the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here. Experimental results also indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1053-1056
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• 2007

The acoustical performance of noise reducing devices installed on the top of a noise barrier were tested by small-scale outdoor tests. Noise measurements before and after installation of the devices were carried out using sound intensity methods. It is well known that the sound intensity method can specify the strength and directivity of sound, and it is convenient to consider the feature of sound around a noise barrier. The noise reduction effect of each edge device was evaluated using the difference between the input and output sound power levels calculated from sound intensities. It was investigated that each device had different efficiency in the shadow zone, while there was no significant difference between edge devices in the illuminated zone.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.58-64
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• 2010

Spontaneous ignition tests of five different coals with non-iso-thermal and iso-thermal test method based on the standard test procedure of NF T20-036 were carried. These five coals included the 2 low rank coals and 3 bituminous coals. Test results showed that the ignition temperatures of all coals at the iso-thermal conditions were higher than that of non-isothermal condition, and those of low rank SM and BR coal in both nonisothermal and isothermal conditions were lower than bituminous AN and CN coals. The chemical species of coals such as oxygen and hematite also plays an important role in enhancing the ignition rate that the ignition temperature of SM coal was lowered. The heat accumulation tendency of five coals inside outdoor stack pile was monitored with emphasis on the change in the temperature of the coal depth in stack pile. In case of low rank BR coal, its temperature inside coal stack pile due to the rate of high heat accumulation and oxidation was $59^{\circ}C$ compared to $51^{\circ}C$ for other SW bituminous coal. And the heat accumulation rate inside coal stack piles was increased with increased the Cp value which it was defined as the specific heat of coal at constant pressure, whereas other factors such as thermal diffusivity and conductivity of coal relatively had less effect on heat accumulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.525-531
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• 2011

Recently, the demand of environmentally friendly transportation has increased due to the environmental issues. Electric two-wheeled vehicles do not have the noise pollution nor exhaust gases of vehicles with internal combustion engines. Performance evaluation of an electric two-wheeled vehicle was carried out. A driving test on outdoor roads was performed and a chassis dynamometer was used. The chassis dynamometer simulates the road load of the vehicle. The road load influences the tests using the chassis dynamometer. The differences between the table method and the coasting test for setting the road load was compared and analyzed.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.711-717
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• 2007

Location information will become increasingly important for future Pervasive Computing applications. Location tracking system of a moving device can be classified into two types of architectures: an active mobile architecture and a passive mobile architecture. In the former, a mobile device actively transmits signals for estimating distances to listeners. In the latter, a mobile device listens signals from beacons passively. Although the passive architecture such as Cricket location system is inexpensive, easy to set up, and safe, it is less precise than the active one. In this paper, we present a passive location system using Cricket Mote sensors which use RF and ultrasonic signals to estimate distances. In order to improve accuracy of the passive system, the transmission speed of ultrasound was compensated according to air temperature at the moment. Upper and lower bounds of a distance estimation were set up through measuring minimum and maximum distances that ultrasonic signal can reach to. Distance estimations beyond the upper and the lower bounds were filtered off as errors in our scheme. With collecting distance estimation data at various locations and comparing each distance estimation with real distance respectively, we proposed an equation to compensate the deviation at each point. Equations for proposed algorithm were derived to calculate relative coordinates of a moving device. At indoor and outdoor tests, average location error and average location tracking period were 3.5 cm and 0.5 second, respectively, which outperformed Cricket location system of MIT.

• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.237-242
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• 2020

This paper deals with relative position estimation using a Kalman filter (KF) based on inertial sensors that have been widely used in various biomechanics-related outdoor applications. In previous studies, the relative position is determined using relative orientation and predetermined segment-to-joint (S2J) vectors, which are assumed to be constant. However, because body segments are influenced by soft tissue artifacts (STAs), including the deformation and sliding of the skin over the underlying bone structures, they are not constant, resulting in significant errors during relative position estimation. In this study, relative position estimation was performed using a KF, where the S2J vectors were adopted as time-varying states. The joint constraint and the variations of the S2J vectors were used to develop a measurement model of the proposed KF. Accordingly, the covariance matrix corresponding to the variations of the S2J vectors continuously changed within the ranges of the STA-causing flexion angles. The experimental results of the knee flexion tests showed that the proposed KF decreased the estimation errors in the longitudinal and lateral directions by 8.86 and 17.89 mm, respectively, compared with a conventional approach based on the application of constant S2J vectors.

• Journal of the Korean Wood Science and Technology
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• v.43 no.5
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• pp.641-651
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• 2015

The aim of this study was to estimate the service life of alkaline copper quaternary (ACQ)-treated wood. The service life of preservative-treated wood was estimated by comparing a residual quantity of ACQ in wood with toxic threshold to fungi. Indoor and outdoor leaching tests were carried out in order to predict residual ACQ quantity within wood. As a result, the leaching ratio of ACQ from treated wood above ground via precipitation was 18.1% for 50 years. When the H4 treated wood, which is traditionally used in contact with the ground and fresh water, is used above-ground, the leaching ratio of ACQ for 50 years is 18.1% and the residual quantity of ACQ is $4.2kg/m^3$, which is higher than the toxic threshold of ACQ. Thus, the H4 treated wood used above-ground will be resistant to biodeterioration for at least 50 years.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.705-706
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• 2008

When heat generated inside a large factory building is not discharged due to a stagnant flow, the working environment of workers becomes worse and the cooling of high-temperature products such as hot-rolling coils is delayed. To investigate the natural ventilation inside a large factory building, experimental studies were carried out using wind-tunnel tests. The scale-down factory building models were placed in an atmospheric boundary layer (ABL) and the mean and fluctuating velocity fields were measured using a particle image velocimetry (PIV) technique. For the prototype factory model, the outdoor air is only entrained into the factory building through the one-third open windward wall, and stagnant flow is formed in the rear part of the target area. In order to improve the indoor ventilation environment of the factory building, three different louver-type ventilators were attached at the upper one-third open windward wall of the factory model. Among the three louver ventilators tested in this study, the ventilator model #3 with the outer louver (${\theta}_o$ = 90$^{\circ}$) and the inner louver (${\theta}_i$ = -70$^{\circ}$) was found to improve the natural ventilation inside the factory building model effectively. The flow rate of the entrained air was increased with aligning the outer louver blades with the oncoming wind and guiding the entrained air down to the ground surface with elongated inner louver blades.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.664-667
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• 2009

There is strong demand to create wearable PC systems that can support the user outdoors. When we are outdoors, our movement makes it impossible to use traditional input devices such as keyboards and mice. We propose a hand gesture interface based on image processing to operate wearable PCs. The semi-transparent PC screen is displayed on the head mount display (HMD), and the user makes hand gestures to select icons on the screen. The user's hand is extracted from the images captured by a color camera mounted above the HMD. Since skin color can vary widely due to outdoor lighting effects, a key problem is accurately discrimination the hand from the background. The proposed method does not assume any fixed skin color space. First, the image is divided into blocks and blocks with similar average color are linked. Contiguous regions are then subjected to hand recognition. Blocks on the edges of the hand region are subdivided for more accurate finger discrimination. A change in hand shape is recognized as hand movement. Our current input interface associates a hand grasp with a mouse click. Tests on a prototype system confirm that the proposed method recognizes hand gestures accurately at high speed. We intend to develop a wider range of recognizable gestures.

• Agricultural and Biosystems Engineering
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• v.6 no.2
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• pp.65-69
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• 2005

A windheat generation system with a Savonius windturbine was developed and the performance was evaluated through field tests. The system consisted of a heat generation drum, heat exchanger, water storage tank, and two circulation pumps. Frictional heat is created by rotation of a rotor inside the drum containing thermo oil, and was used to heat water. In order to estimate the capacity of this windheat generation system, weather data was collected for one year at the site near the windheat generation system. Wind Power from the savonius wind turbine mill was transmitted to the heat generation system with an one-to-three gear system. Starting force to rotate the savonius wind turbine and the whole system including the windheat generation system were 1.0 and 2.5 kg, respectively. Under the outdoor wind condition, maximum speed of the rotor in the drum was 75rpm at wind speed 6.5 m/sec, which was not fast enough to produce heat for greenhouse heating. Annual cumulative hours for wind speeds greater than 5 m/sec at height of 10, 20, 30 m were 190, 300 and 1020 hrs, respectively. A $5^{\circ}C$ increase in water temperature was achieved by the windheat generation system under the tested wind environment.