• Plant Journal
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• v.12 no.2
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• pp.31-35
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• 2016

A method of failure data management for Reliability-Centered Maintenance was shown for a boiler feedwater pump of a power plant. The major part of it is an analysis of failure mode, failure cause, and failure effects, which is the main component of a failure data base like OREDA(Offshore Reliability Data). Case study shows main element of the preventive maintenance planning such as the maintenance period can be statistically determined from the failure data.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1400-1404
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• 2005

This paper presents the temperature control of aluminum plate by using Peltier element. Peltier effect is heat pumping phenomena by electric energy as one of the thermoelectric effect. So if current is charged to Peltier element, it absorbs heat from low temperature side and emits heat to high temperature side. In this experiment, Peltier element is used to control the temperature of small aluminum plate with current control and operating cooling fan only while cooling duration. Operating cooling fan only while cooling duration is proper to get more rapid heating and cooling duration. As a result of experiment, it takes about 100sec period to repeating temperature between $35^{\circ}C$ and $70^{\circ}C$ and about 80sec from $40^{\circ}C$ to $70^{\circ}C$ in ambient air temperature $25^{\circ}C$ and while operating cooling fan only in cooling duration. Future aim is to apply this temperature control method in actuating SMHA(special metal hydride actuator) which is applicable in Siver project acting in low frequency range by using Peltier element for heating and cooling.

• KIEAE Journal
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• v.17 no.4
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• pp.75-81
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• 2017

Purpose: Most contemporary office buildings supply external views, a sense of openness and a sense of time to their occupants by adopting the curtain walls, which are equipped with an outer cover having large window area. As a result, the amount of radiation increases, adversely affecting cooling load during the summer in office buildings. Although solar radiation decreases heating load and reduces energy costs during the winter period, due to the characteristics of offices where occupants work largely during daytime, the cooling load is important compared to the heating. Therefore, diverse measures to resolve those trade-offs and annual energy cost have been investigated. Method: In this study, the annual thermal load was comparatively analyzed according to the slat angle of the venetian blind along with lighting control technique. Result: After selecting effective conditions, in order to resolve such issues, this study established automated control strategies of slat angle depending on the window-to-wall ratio and zone orientation, so that the findings of this study can be effectively generalized to other circumstances.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1700-1716
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• 1996

The two-dimensional, unsteady, laminar conservation equations for mass, momentum, energy and species transport in the gas phase and mass, momentum and energy in the liquid phase are solved simultaneously in spherical coordinates in order to study heating and vaporization of a droplet entrained in the oscillating flow. The numerical solution gives the velocity and temperature distribution in both gas and liquid phase as a function of time. When the gas flow oscillates around an vaporizing droplet, the liquid flow circulates in the clockwise or counterclockwise direction and the temperature distribution in the liquid phase changes its shapes, depending on the gas fow direction. When the gas flow changes its direction of circulating liquid flow is opposite to the gas flow, forming two vortex circulating in the opposite direction. During the heating period, the difference in the maximum and minimum temperature is large, followed by the almost uniform temperature slightly below the boiling temperature. The mass and heat transfer from the droplet depend on the droplet temperature, droplet diameter and the magnitude of relative velocity, giving the droplet lifetime different from the d$^{2}$-law.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.66-72
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• 2008

In this study, the ground source heat pump was installed at a research center in Jeju Island to verify the performance of the system and to give an information for a economic feasibility. The performance test was conducted until the heat storage tank temperature reached at $5^{\circ}C$ from $50^{\circ}C$ in the cooling operation, and until the storage temperature goes up to $50^{\circ}C$ from $10^{\circ}C$ in the heating mode. As results, the system performance shows that $2.2{\sim}3.5$ for the cooling operation and $2.5{\sim}3.5$ for heating operation. It is found that the underground is good heat source for the heat pump with $3{\sim}10^{\circ}C$ variation range. The ground source heat pump could be connected one of air conditioning system without any problem in system performance. Based on the economic analysis, the initial cost for the ground source heat pump will be compensated after 4 years operation. If the system runs 20 years, approximately 300 million Won will be saved when the air conditioning system adapt the ground source heat pump based on Life Cycle Cost analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.5
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• pp.496-504
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• 2005

Heat recovery ventilators (HRV) are developed in order to satisfy both energy conservation and the improvement of indoor air quality as an alternative for current natural ventilation systems and local mechanical ventilation systems in kitchens and bathrooms. However, the performance of HRV system and the consequent effect on heating and cooling energy saving have not been sufficiently validated quantitatively in case of the application of HRVs in real residences. In this study, field measurement and computer simulation were conducted in both summer and winter period to assess the performance and validate energy conservation effect of HRVs. Under the Korea weather condition, average total heat recovery efficiency was $27\%$ in summer and $46\%$ in winter. According to the field measurement, HRV system can save the energy by $10\%$ in summer and 15$\%$ in winter. Furthermore, according to the simulation assessment, HRV system can save the energy by $17\%$ in summer and $17\%$ in winter.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1497-1502
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• 2009

The present study has been conducted economic analysis of heat storage type ground source heat pump system(HSGSHP) and normal ground source heat pump (GSHP) and central boiler system with individual air conditioning facility which are installed at the same building in the shared an apartment house. Cost items, such as initial construction cost, annual energy cost and maintenance cost of each system are considered to analyze life cycle cost (LCC) and simple payback period (SPP) with initial cost different are compared. The initial cost is a rule to the Government basic unit cost of production. LCC applied present value method is used to assess economical profit of both of them. Variables used to LCC analysis are prices escalation rate and interest rate mean values of during latest 10 years. The LCC result shows that HSGSHP (1,351,000,000won) is more profitable than central boiler system with individual air conditioning facility by 86.7% initial cost. And SPP appeared 8.0 year overcome the different initial cost by different annual energy cost.

• Journal of environmental and Sanitary engineering
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• v.7 no.2
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• pp.141-152
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• 1992

Simple correlation analysis, factor analysis, and multi-verite analysis have been performed to analyze the relationship between air pollution and meteorological factors for air pollution and meteorological data measured at Kwanghwamun in Seoul during the period of one year (January 1990" December 1990). As a result of simple correlation and factor analysis, $SO_2$, TSP and CO concentrations have shown high negative correlation with temperature and among these indicating that these are related with pollutants emission trend based upon heating fuel usage. Ozone has a good correlation with solar radiation and relative humidity to have a closed relation with $0_3$ generation reaction mechanism. The result of multi-variate correlation analysis shows that the concentration of $SO_2$ and CO are adequate for correlation model with ambient temperature and wind speed and 0$_{3}$ concentrations are adequate for that with solar radiation and wind speed. $SO_2$ and CO levels are considered to be affected first of all by heating fuel usage as a emission source and wind speed as a dispersion effect. The $SO_2$ concentration in the condition that the temperature fall below zero is explained by multiplicative model with wind speed, only one variable.

• Journal of architectural history
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• v.25 no.4
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• pp.31-44
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• 2016

Geum'yeok-dang house in Andong was originally constructed in 1558. The original floor plan of the upper base featured a 90-degree tilted '日' shape, and had inner court(內庭) on each side of 'Jungdang(中堂, center hall)' building that was placed on the south-north axis. When designing the building, the Neo-Confucian client of Geum'yeok-dang applied his understanding of how Ga'rye("家禮") defined the structure of ritual space. Consequently, 'Daecheong(大廳)', the place where guests were greeted and ancestral rites and coming of age ceremonies for male were held, was built in a protruding fashion. 'Jungdang'[otherwise known as 'Jeongchim(正寢)'], where coming of age ceremonies for females were held, the master of the house faced death, and memorials for close ancestors were held, was placed at the center of the residence on the south-north axis. The Geum'yeok-dang today was greatly renovated in the early and mid 18th century, due to the spread of 'Ondol' heating system. As the Ondol heating system became popular, the pre-existing drawbacks and the inconvenience of the house stood out clearly. As a result, the house was renovated into today's structure consisting of '口' shape 'Anchae' and 'Daecheongchae' in separate building.

• Journal of Korea Foundry Society
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• v.2 no.1
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• pp.2-11
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• 1982

In order to investigate the relationship between the thermal characteristics of the various molds as green sand mold, dry sand mold, $CO_2$ mold and shell mold, and the solidification characteristics of molten metal, the thermal analysis of rarious molds and melt were performed. The structure of Al-Castings was a/so observed. Results obtained in this experiment were as follows : 1) The heating rate of the molds was increased in the order of green sand mold, $CO_2$ mold, dry sand mold and shell mold, On the other hand the solidification time of the melts was shortened in the order of dry sand mold castings, $CO_2$ mold castings, green sand mold castings and shell mold castings. 2) The arrest temperature period in the heating curve of the green sand mold was resulted from the eraporation of moisture contained in mold, which was transfered to the outer side of the mold. 3) The temperature fluctuation of the melt in the shell mold was considered to be resulted from the combution heat of resin contained in the mold. 4) The amounts of heat absorption of the molds were increased in the order of dry sand mold, $CO_2$ mold, green sand mold and shell mold. 5) The higher the solidification rate was, the longer was its shrinkage pipe and the finer its grain size.