• Asian Journal of Atmospheric Environment
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• v.11 no.3
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• pp.184-193
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• 2017

People spend the majority of their time in indoor environments. Maintaining adequate indoor temperature and humidity is necessary to support health and improve quality of life. However, people with low incomes can be vulnerable because they may not be able to use effective cooling and heating systems in their homes. In this study, the indoor temperature and humidity in low-income residences over a year in Seoul, Korea was characterized. Indoor temperature and humidity were measured in three types of homes (12 rooftop residences, 16 basement residences, and 18 public rental apartments) occupied by low-income residents. Both differed significantly among the three types of residence, particularly during the summer and winter seasons. A regression model between indoor and outdoor temperature detected a heating threshold at $3.9^{\circ}C$ for rooftop residences, $9.9^{\circ}C$ for basement residences, and $17.1^{\circ}C$ for public rental apartments. During tropical nights and cold-wave advisory days, rooftop residences showed the most extreme indoor temperatures. This study demonstrates that people living in rooftop residences could be at risk from extreme hot and cold conditions.

• New & Renewable Energy
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• v.5 no.4
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• pp.60-65
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• 2009

The present study was conducted for a comparative evaluation of wet and dry floor heating systems using geothermal heat pump. We circulated hot water from geothermal heat pump which is $10{\sim}15^{\circ}C$ lower than that from boiler. In order to access indoor temperature ($25^{\circ}C$) it took 74 minutes for dry type and 247 minutes for wet type. Average floor temperature was $23.9^{\circ}C$ for wet type and $32.7^{\circ}C$ for dry type. Energy saving rate gradually increased by 66% after 138 minutes. As a result, in case of floor heating system using low temperature circulation water, dry type was more practicable for stable floor heating than wet type in terms of floor temperature and access time to indoor set temperature.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.655-663
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• 2024

In order to meet the technological demand for indoor heating systems that ensure winter thermal comfort during the transition from internal combustion engines to electrification, a localized proximity heating module using surface heating elements was developed. The operational performance of heating module was tested in the low temperature chamber. The experiment conditions were varied by changing the chamber temperature (-10, 0℃), the air flow rate (6.2, 6.0, 4.2m³/h), the heater power (100, 80, 60, 40W). Thermal comfort model was confirmed using the CBE Thermal Comfort Tool applying ASHRAE standard 55. Under -10℃ condition, thermal comfort was satisfied at 23.4, 23.2℃ at power of 100W and air flow rate 6.0, 4.6m³/h. Under 0℃ condition, at power of 80W, air flow rate 6.2, 6.0m³/h, and at power of 60W, air flow rate 4.6m³/h showed results of 25.7, 26.1, 23.0℃, respectively, satisfying thermal comfort. This study analyzed the operating performance of the local proximity heating module in the low temperature chamber and applied thermal comfort model to prove applicability of local proximity heating module using surface heating elements and how to utilize the thermal comfort model.

• Journal of Korean Society for Quality Management
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• v.48 no.3
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• pp.463-479
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• 2020

Purpose: The purpose of this study is to evaluate the performance of heating equipments by implementing the extreme environment in which ships navigating the ice zone are exposed and to study and apply the experimental method to infer the optimized design for each factors. Methods: It is required to verify by analysis and experiment how the environment with low temperature and wind speed implemented through the test facility affects the heating walk-way and The optimum design of the heating walk-way in that extreme environment is derived using the Taguchi technique. Results: The results of this study are as follows; It was found the effect on the condition of each factor and derive optimized conditions that satisfy the performance condition of the heating walk-way in extreme use environment. Conclusion: Ships operating in Polar waters require reliable and durable facilities for all environments during sailing.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.83-85
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• 2013

With an increase in the use of low rank coals in power plants, various operational issues were raised in the fuel storage and supply, combustion, boiler and flue gas treatment systems. In the fuel storage and supply system, the main issue is the self-heating propensity of low rank coals leading to spontaneous combustion in yard storage, transport and pulverization. This study evaluated the reactivity of various sub-bituminous and bituminous coals with oxygen at low temperatures by analyzing the temperature increase characteristics of coals under a constant flow rate of oxygen supply. The results were quantified to a self-heating index and the relation with the fuel properties were evaluated.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.9 no.2
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• pp.1-7
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• 2013

Most researches done on heat pumps have been on heat pumps for refrigeration, cooling and heating. There is therefore the need for more research on hot water heat pumps, especially for high temperature. Even though the cascade heat pump cycle has a great potential more efficient hot water generation even at low evaporating temperatures, it has been researched least for this purpose. In this study, the heating performance of a variable speed cascade heat pump was investigated by varying operating conditions. For the same heating capacity values, it was found that increasing the low stage compressor speed was more suitable for enhancing the performance of the system to get a higher temperature.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.4
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• pp.177-182
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• 2020

Interest in heat pumps is increasing as an eco-friendly and energy-saving heating method. In particular, in order to develop a heat pump capable of heating in a low-temperature area, research to prevent frost on the surface of the outdoor unit is increasing. In other words, when heating through a heat pump in a low-temperature area, a frost layer is formed on the surface of the outdoor unit, which lowers the heat transfer performance, thereby reducing the heating capacity. Therefore, in this study, an adsorption-type dehumidification system is attached to remove the moisture vapor of the air into the outdoor unit of the heat pump. It is believed that this study can suggest the most effective dehumidification method in low temperature regions. In addition, it is expected that a heat pump with high energy efficiency can be developed by attaching an adsorption dehumidifying system to the front of the outdoor unit of the heat pump.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.136-144
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• 2002

Melting method has long been considered difficult to realize because of problems such as the low foamability of molten metal, the varying size of cellular structures and solidification shrinkage. The parameters to solve the problem in electric furnace were stirring temperature, stirring velocity, heating velocity and foaming temperature It is important to consider the effects of induction heating, because it brings about the inner flow by the temperature gradient. Aspect ratio also depends on the induction heating. Mechanical properties are dependent on cell sizes and aspect rations. Therefore, this paper presents the effects of these parameters on the cell sizes. For the sake of this, combined stirring process was used to fabricate aluminum foam materials by the above mentioned parameters. Image analysis was performed to calculate the cell sizes, distributions, and aspect ratioes at the cross section of feared aluminum in the direction of height.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.295-301
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• 2000

The effect of V2O5 addition on the low temperature sintering of Pb(Mn1/3Sb2/3)O3-PZT ceramics, which is known as a prominent material for piezoelectric transformer application was studied, and the densification behavior and piezoelectric characteristics of the samples as a function of heating rate were also examined. V2O5 led the system to liquid phase sintering by forming liquid phase during sintering, which accelerated densification through the particle rearrangement in the early stage of sintering. The liquid phase mostly existed at grain boundaries retarded the evaporation of PbO, while the densification temperature and the weight loss of V2O5-free samples were higher than those of samples with V2O5. Faster heating improved the densification of the samples regardless of V2O5 addition. The low temperature sintering at 100$0^{\circ}C$ was achieved in PMS-PZT ceramics with high density and reasonable dielectric and piezoelectric characteristics. This result revealed optimistic way to the development of multi-layered piezoelectric transformers.

• Journal of Ginseng Research
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• v.19 no.3
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• pp.249-253
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• 1995

In the browning reaction of Korean ginseng, it appears that enzymatic and non-enzymatic browning reaction occurred in the initial stage of heating fresh ginseng at low temperature, and then non-enzymatic browning reaction followed in the drying period after heating. Activation energy of the browning reaction for red ginseng was about 9.0 kcal/mol. Browning reaction of red ginseng was accede- rated with an increase in steaming time, and a great extent of browning reaction occurred between 60-90 min of steaming at 10$0^{\circ}C$. Browning pigments of red ginseng were mostly water soluble subset.