• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1436-1441
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• 2004

Abnormal current-voltage characteristics of an oxide semiconductor have been investigated and a novel method of detecting reducing gases utilizing self-heating mechanism of sensing layer without an additional heater has been developed. Planar-type sensors based on WO3-doped SnO2 were fabricated using a screen-printing technique. The applied voltage across the sensing layer caused heating of the sensing layer and the current abruptly varied upon exposure to a gas mostly as a result of surface reactions. A unique and fascinating aspect of the gas sensing scheme is that no additional heater is necessary for detection. The new sensing method has been applied to C2H5OH gas in this preliminary work.

• Journal of the Korean Society for Railway
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• v.15 no.6
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• pp.558-565
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• 2012

Abnormal climate or weather is more frequently reported nowadays due to the global climate change. Especially, extremely low temperature in winter season may cause bad thermal discomfort of passengers. In this study, the effect of car heating modes on cabin temperature change and distribution was studied by using a real-scale environmental chamber for passenger cabin. It was found that the cabin temperature rose quickly at the initial stage of heating system operation, but it stopped increasing after certain point. And, temperature was higher when the height from the floor was higher. Based on the obtained result, the way to minimize the decrease of passengers' thermal comfort was suggested.

• Journal of architectural history
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• v.27 no.3
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• pp.15-26
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• 2018

As a result of reviewing various documents and existing researches, since the late Goryeo period, the most active period in the Ondol(溫突, Korean floor heating system) facilities is the 17th century. The phenomenological reason was recovering the buildings destroyed by the Japanese Invasion of Korea in 1592(壬辰倭亂) & the Manchu War of 1636(丙子胡亂), but the underlying cause was an abnormal climate in which a pair of summer and winter cold continued. In the 17th century, as the Ondol facilities grew rapidly without distinction between regions and classes, the supply and demand of fuel caused economic and natural environmental problems. And a negative and positive view on Ondol was suggested. Since the middle of the 18th century, when the demand and supply of Ondol reached its peak, which could no longer increase, a new awareness of Ondol began to grow. The room was called the Panbang(板房) and the Ondol, depending on the material that made up the floor. It was considered natural to have the Ondol from this time on. The Incan(因間) and Jo(竈) that were made to burn were started to be recorded as a kitchen, regardless of size and function. Changes in social awareness of Ondol have led to concerns about heating efficiency. A variety of architectural explorations were conducted. Such a search was later realized in concrete architectural form. There is a double Ondoll structure, and the column spacing is reduced compared to the previous one. The heat buffer space is formed around the Ondol room, and the double window can control the light and the air going in and out.

• Journal of Welding and Joining
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• v.20 no.2
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• pp.102-108
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• 2002

Resistance spot welding of aluminum alloys is based upon Joule heating of the components by passing a large current in a short duration. Since aluminum alloys have the potential to replace steels fur automobile body assemblies, it is important to study the process robustness of aluminum spot welding process. In order to evaluate the effects of process parameters on the weld quality, major process variables and abnormal process conditions were selected and analyzed. A newly developed two-stage, sliding-level experiment was adopted fur effective parameter design and analysis. Suitable ranges of welding current and button diameters were obtained through the experiment. The effects of the factors and their levels on the variation of acceptable welding current were considered in terms of main effects. From the results, it is concluded that any abnormal process condition decreases the suitable current range in the weld lobe curve. Pareto analysis of variance was also introduced to estimate the significant factors on the signal-to-noise (S/N) ratio. Among the six factors studied, fit-up condition is found to be the most significant factor influencing the SM ratio. Using a Pareto diagram, the optimal condition is determined and the SM ratio is significantly improved using the optimal condition.

• 전기의세계
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• v.24 no.1
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• pp.75-85
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• 1975

In order to develop the commercial frequency (60Hz) plasma torch of small capacity for material cutting, welding and other industrial heating, the A.C plasma jet generator of non-transfered type is made domestically and the electrode configurations of plasma torch are composed of two kinds of electrodes W-C and W-Cu, combined by thermal emission and field emission electrode materials. In this paper, the characteristics of input power, thermal efficiency, electrode consumption, the flame and forms of arc voltage and arc current for A.C plasma torch are investigated in relation to such variables as arc current, argon flow and magnetic field intensity to obtain the basic design data necessary to A.C plasma jet generator. The result are as follows; (1)The input power, thermal efficiency and electrode consumption are influenced greatly by argon flow, magnetic field intensity and nozzle materials. (2)A.C arc voltage and current are non-symmetrial, involving D.C Component. Due to this current of D.C Component, transformer core is saturated and a large abnormal current flows into the primary winding coil. In order to prevent this abnormal current flow, a condenser must be connected in series to the main discharge circuit. (3)The stability and sharpness of jet flame are improved more in the torch of W-C electrode configuration than in the torch of W-Cu electrode configuration.

• Atmosphere
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• v.16 no.3
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• pp.187-201
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• 2006

During summer (JJA) of 2004, a record-high temperature in Korea appeared at Miryang ($38.5^{\circ}C$ on July 30). Moreover, Miryang showed the most frequent occurrence (25 days in JJA) of the daily highest temperature among observational sites in Korea. Based on meteorological analysis, it is found that this phenomenon is caused by neither the global warming effect nor the urban climate effect. It is caused by the mesoscale and synoptic and/or global scale atmospheric circulations, as evidenced by several factors described below. Firstly, the hottest areas have normally occurred not at a point but over an area, particularly along an axis connecting Sancheong and Daegu. But in 2004, this axis has moved southward and locates over Namhae-Miryang due to northerlies that were induced by the heating effect related to the low snow-cover on the Tibet Plateau. Secondly, although the maximum temperature was the highest among observational sites in Korea, the daily mean temperature and the number of nights with air temperature over $25^{\circ}C$ were not the highest at Miryang. Thirdly, the downdraft induced by the second circulation of typhoon and abnormal development of the North-Pacific High were found to have exerted an important role.

• Journal of Astronomy and Space Sciences
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• v.33 no.4
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• pp.305-311
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• 2016

The spatial size and variation of Arctic sea ice play an important role in Earth's climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP) F13 Special Sensor Microwave/Imagers (SSMI) and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS) sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.53-58
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• 2015

Systemic heating and cooling air conditioning systems are popular in various industrial fields and even home. Recently, the rate of supply of this kind of multi-heat pump has been increased under ESCO financing supporting system. Generally the heat pumping system has a structural simplicity and easy installation benefits. and has good running efficiency under normal designed condition. But under extreme climate condition (over $+30^{\circ}C$, under $-10^{\circ}C$), this system exposes abnormal power consumption. It causes high progressive electric power rates and resultant peak power capacity of power plant. In this paper, a novel system concept of buffering refrigerant accumulator and constant pressure control system to relieve peak power load is proposed and this system's utility is verified with an prototype experimental system.

• Journal of the Korea Safety Management & Science
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• v.26 no.1
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• pp.31-38
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• 2024

In this paper, as there are many cases of fires occurring due to the failure or inoperability of the thermostat of electronic products, the purpose is to test and analyze the risks and probabilities through fire cases and reproduction experiments, and suggest countermeasures. Among electronic products, water purifiers are composed of a refrigerant system with a compressor to make cold water, a heating device to make hot water, and an electric device used as an energy source. Due to the nature of the water purifier manufacturing, these devices are subject to a lot of moisture and dust. etc. exist in large quantities and use electrical energy, so there is a possibility of fire due to short circuit in the wire, electrical abnormal overheating (tracking phenomenon) in the thermostat, electronic board, starting relay, etc., and overheating of the heating device (Band Heater). there is. Therefore, in order to prevent fires from these devices, a system to remove foreign substances inside the water purifier is necessary, the use of heat-resistant (fire-resistant) wires for electrical devices is essential, and the use of non-combustible materials (semi-combustible materials) for each part is necessary to prevent fire. The risk must be eliminated through prevention and combustion expansion prevention devices.

• Fire Science and Engineering
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• v.34 no.3
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• pp.67-75
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• 2020

In this study, the risk of heat generation due to normal and overload currents that vary with the abnormal loosening angle of wire-connecting bolts were identified. The risks were analyzed based on the thermal characteristics to minimize the carbonization accidents of terminal blocks inside distribution panels typically used in industrial sites. We applied a method for measuring the heating temperature and temperature variations in the terminal blocks in real-time by installing a resistance temperature detector sensor board in the terminal block. The experimental results showed that the terminal block model with a low-rated current exhibited a higher heating temperature, thus, confirming the need to select the terminal block capacity based on load currents. Additionally, the higher the rated current of the terminal block with a high-rated current and the higher the degree of loosening, the faster the carbonization point. Such heating temperature monitoring enabled real-time thermal temperature measurement and a step-by-step risk level setting through thermal analysis. The results of the measurement and analysis of carbonization risks can provide a theoretical basis for further research regarding the risk of fire due to carbonization. Furthermore, the deterioration measurement method using the temperature sensor board developed in this study is widely applicable to prevent fires caused by poor electrical contact as well as risk-level management.