• KIEAE Journal
• /
• v.15 no.4
• /
• pp.91-104
• /
• 2015

Recently, various researches for the improvement of Han-ok performance carried out. But, most of them are tend to come from the viewpoint of suppliers rather than that of Han-ok habitants. It means that environmental elements which real habitants feel are not reflected in the design of initial Han-ok design. Therefore, it is necessary that many researchers should analyze the degree of dwelling satisfaction derived from real life. Purpose: The purpose of this study is to find the avaliable factors that need to be considered in the process of initial Han-ok design and construction through the analysis on the living performance satisfaction ratio of modern New Han-ok's habitants. Method: To achieve this goal, surveys were carried out in 83 Han-oks which actual habitants were living, located in 14 happy villages Jeonnam province. Following are survey items about residential environmental conditions; kinds of wall material, gap(connection joint between wall and wood columns) reinforcement or not, kinds of window, kinds of facilities around windows, kinds of heating source, heating types(single, multiple), financial burdens, selective heating or not and so on. Result: The results of this study may be used to improve the living performance satisfaction ratio of new Han-ok habitants and as a basis for the specifying the desired thermal comfort environment of dwelling.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.3 no.4
• /
• pp.307-314
• /
• 1998

A novel high power factor Dual Half Bridge Series Resonant Inverter (DHB-SRI) for an induction heating appliance with multiple loads is proposed to remove the interferential acoustic noise caused by the difference between operating frequencies of adjacent loads. The circuit enables independent full power range control of two induction heating elements by one inverter circuit and has minimum switching losses due to the zero voltage switching characteristic. According to the mode analysis, I will explain the operation of the proposed circuit. To evaluate the required cooling capacity, loss analysis is performed through deriving some loss equations. In order to obtain the power factor correction capability and to lessen the system size, suitable design guides are given. Using the designed values, the proto-type circuit with 2.8kW power consumption for each induction heating element is built and tested to verify the operation of the proposed circuit.

• Journal of the Korean earth science society
• /
• v.29 no.7
• /
• pp.523-530
• /
• 2008

The phase changes and variations of elemental contents in hematite medicinal mineral were investigated by a traditional processing operation including heating and quenching in vinegar. Hematite was processed at $650^{\circ}C$ and $900^{\circ}C$ through at least 5 processing cycles. Metal extraction tests in water were carried out with the processed hematite. Heating and quenching in vinegar could not change the phase of hematite. The effect of this traditional method was not clear because there were no variational trends between extracted elements and the number of processing cycles at $650^{\circ}C$ and $900^{\circ}C$. However, the traditional processing operation of heating and quenching in vinegar was very effective to change the hematite mineral towards soft and easily crushing medicinal material.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.2
• /
• pp.666-671
• /
• 2014

Using positive temperature coefficient (PTC) heater as supplementary heating for diesel engine vehicles with low heat source is a good method to enhance the heating performance during cold start. In this study, the PTC elements were made by using screen printing process for forming ohmic contact layer, and prototype of PTC heater was designed and made for a diesel engine vehicle. In process of designing the PTC heater, the thermal flow analysis of PTC element modules was conducted for verifying the effect of the shapes of contact surface between each of the components (cooling fin, insulator, ceramic element). We also investigated the performance characteristic (heating capacity, energy efficiency, pressure drop) of the PTC heater through the experiments. Therefore, the experimental results indicated that prototype of PTC heater had satisfactory performance. This study will be basis for improving the manufacturing process and increasing the performance of the PTC element and heater.

• Corrosion Science and Technology
• /
• v.19 no.6
• /
• pp.296-301
• /
• 2020

Failure analysis on the welded type 304 pipe used for cooling water piping in the district heating primary side was conducted. Inorganic elements and bacteria in the cooling water and in corrosion products were analyzed, and the weldment was inspected by microscopy and a sensitization test. Corrosion damages were observed in the heat-affected zone, on weld defects such as incomplete fusion or excessive penetration caused by improper welding, or/and at the 6 o'clock position along the pipe axial direction. However, the level of concentration of chloride in the cooling water as low as 80 ppm has been reported to be not enough for even a sensitized type 304 steel, meaning that the additional corrosive factor was required for these corrosion damages. The factor leading to these corrosion damages was drawn to be the metabolisms of the types of bacteria, which is proved by the detection of proton, sulfur containing species, biofilms, and both bacteria and corrosion product analyses.

• Composites Research
• /
• v.33 no.6
• /
• pp.395-400
• /
• 2020

In this paper, we manufactured silsesquiaznae (SSQZ)-coated carbon nanotube (CNT) surface heating elements, which allowed stable heating at high temperatures. The prepared composite sheet was confirmed by FE-SEM that the SSQZ fully coated the surface of CNT sheet. Furthermore, it was also confirmed that the silicon carbonitride (SiCN) ceramic formed by heat treatment of 800℃ have no defects found and maintain intact structure. The CNT/SiCN composite sheet was able to achieve higher thermal stability than raw CNT sheets in both nitrogen and air atmosphere. Finally, the CNT/SiCN composite sheet was possible to heat up at a temperature of over 700℃ in the atmosphere, and the re-heating was successfully operated after cooling.

• Journal of the Korean housing association
• /
• v.24 no.6
• /
• pp.189-197
• /
• 2013

The purpose of the study was to analyze the improvement elements depended on housing quality measurement tool related to mental health. The data for the analysis was collected through questionnaire survey method from November 1, 2012 to January 17, 2013, and the sample consisted of 720 respondents living in single detached houses, multi-families detached houses, apartments, and town houses in 4 cities, Seoul, Busan, Daejeon, and Kwangju. The data were analyzed using descriptive statistics. The results of improvement elements are as follows: 1) Pedestrian-threaten street from cars in physical safety 2) A secluded or dark spot and fear of walking at night in social security, 3) Indoor noise, outdoor noise, and evidence of abandoned trash heap/bottle in neighborhood in health & sanitation, 4) Illegal parking and heating control system in facility convenience, 5) Extra kitchen, number of bathrooms, and community spaces in space convenience, 6) Openness and spaciousness of indoor room, and satisfaction of house and neighborhood in comfort, 7) Management common/sharing space in maintenance, 8) Energy saving facility and environment friendly materials use in sustainability, 9) Burden on housing cost, asset value on house, and school district in economic value, 10) Reflection of residents style, surrounding building's number of layers, and neighborhood appearance of preference in housing environment image.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2008.11a
• /
• pp.452-457
• /
• 2008

The purposes of this study were to determine the actual state of indoor environment and to analyze the relationship between the living factors and indoor physical elements in solitary elderly houses at rural district during winter. The field surveys were consisted of measurements of physical elements, observations of living factors, and interviews of resident's responses. The field surveys were fulfilled in 4 houses from February to March 2008. Measuring elements were air temperature, relative humidity, floor temperature, seated place temperature, $CO_2$, CO, and illumination. The results showed that the average of indoor temperature for houses was $13.5{\sim}22.5^{\circ}C$, relative humidity was $30.6{\sim}55.4%$, floor temperature was $13.9{\sim}24.0^{\circ}C$, seated place temperature was $27.6{\sim}51.1^{\circ}C$, $CO_2$ was $1434.6{\sim}3305.5ppm$, CO was $2.8{\sim}8.4ppm$, illumination was $31.0{\sim}96.7lux$. The residents' clothing values were $1.10{\sim}1.78clo$. Most of the residents' subjective responses were in discord with the physical elements. It was evaluated to be uncomfortable state, and the main reason was revealed lack of heating and ventilation.

• Advances in materials Research
• /
• v.5 no.1
• /
• pp.21-34
• /
• 2016

Fire is one of the most destructive powers to which a building structure can be subjected, often exposing concrete elements to elevated temperatures. The relative properties of concrete after such an exposure are of significant importance in terms of the serviceability of buildings. Unraveling the heating history of concrete and different cooling regimes is important for forensic research or to determine whether a fire-exposed concrete structure and its components are still structurally sound or not. Assessment of fire-damaged concrete structures usually starts with visual observation of colour change, cracking and spalling. Thus, it is important to know the effect of elevated temperatures on strength retention properties of concrete. This study reports the effect of elevated temperature on the mechanical properties of the concrete specimen with polypropylene fibres and cooled differently under various regimes. In the heating cycle, the specimen were subjected to elevated temperatures ranging from $200^{\circ}C$ to $800^{\circ}C$, in steps of $200^{\circ}C$ with a retention period of 1 hour. Then they were cooled to room temperature differently. The cooling regimes studied include, furnace cooling, air cooling and sudden cooling. After exposure to elevated temperatures and cooled differently, the weight loss, residual compressive and split tensile strengths retention characteristics were studied. Test results indicated that weight and both compressive and tensile strengths significantly reduce, with an increase in temperature and are strongly dependent on cooling regimes adopted.

• Macromolecular Research
• /
• v.11 no.6
• /
• pp.481-487
• /
• 2003

Polypyrrole (PPy) was coated sequentially by chemical and electrochemical methods on a woven fabric, giving rise to a fabric having high electrical conductivity. We investigated the effects of the preparation conditions on the various properties of the resulting fabric. The PPy-coated fabric with optimum properties was obtained when it was prepared sequentially by chemical polymerization at the elevated temperature of 100$^{\circ}C$ under a pressure of 0.9 kgf/$\textrm{cm}^2$ and then electrochemical polymerization with a 3.06 mA/$\textrm{cm}^2$ current density at 25 $^{\circ}C$ for 2 hrs with the separator plate. The surface resistivity of the resulting fabric was as low as 5 Ω/$\square$ .The PPy-coated fabric prepared under the optimum conditions showed practically applicable heat generating property. When electrical power was supplied to the fabric using a commercial battery for a mobile phone (3.6 V, LGLl-AHM), the temperature of the fabric increased very quickly from room temperature to ca. 55 $^{\circ}C$ within 2 min and was maintained for ca. 80 min at that temperature. The heat generating property of the fabric was extremely stable, exhibiting similar behavior over 10 repeated cycles. Therefore, we suggest that the PPy-coated fabric in this study may be practically useful for many applications, including flexible, portable surface-heating elements for medical or other applications.