• Journal of Astronomy and Space Sciences
• /
• v.1 no.1
• /
• pp.5-21
• /
• 1984

The airflow along the surface of a launch vehicle together with base flow of clustered nozzles cause problems which may affect the stability or efficiency of the entire vehicle. The problem may occur when the vehicle is on the launching pad or even during flight. As for such problems, local steady-state loads, overall steady-state loads, buffet, ground wind loads, base heating and rocket-nozzle hinge moments are examined here specifically.

• Bulletin of the Korea Photovoltaic Society
• /
• v.6 no.1
• /
• pp.69-75
• /
• 2020

Mongolia is located between Russia and China in Central Asia. In coal-rich corners, both the energy and energy sectors of our country prevail. Mongolia has vast resources of renewable energy and limited hydropower plants, such as wind and solar. In their first iNDC (intended Nationally Determined Contributions) submitted in 2015, Mongolia has pledged to increase the share of renewables capacity to 20% by 2020, and 30% by 2030 while reducing their energy related GHG emissions.

• Journal of Bio-Environment Control
• /
• v.27 no.1
• /
• pp.64-70
• /
• 2018

In this study, eleven major coastal areas were selected and the climate environment and the greenhouse direction were analyzed. This research investigates the greenhouse heat loss according to the wind environment at target areas. The target areas were selected based on heated greenhouse cultivation area and wind environment standard. Temperature, wind speed, and wind direction among weather data for 30 years were collected and analyzed. The data were divided into the minimum, average, and maximum temperatures and the Meteorological Agency criteria applied to the weather and wind direction criteria. Data were collected in the range of $0{\sim}180^{\circ}$ considering the symmetry of the shape of the greenhouse. In addition, the wind direction is different for each region and the applied wind direction can be different when referring to the longitudinal direction of the greenhouse and the data are collected in the range of $0{\sim}90^{\circ}$. The results of this study are expected to be used to calculate the heating load of greenhouse installed in places wind speed high.

• 한국태양에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.56-61
• /
• 2009

Paradigm depending only on fossil fuel for building heat source is rapidly changing. Accelerating the change, as it has been known, is obligation for reducing green house gas coming from use of fossil fuel, i.e. reaction to United Nations Framework Convention on Climate Change. In addition, factors such as high oil price, unstable supply, weapon of petroleum and oil peak, by replacing fossil fuel, contributes to advance of environmental friendly renewable energy which can be continuously reusable. Therefore, current new energy policies, beyond enhancing effectiveness of heat using equipments, are to make best efforts for national competitiveness. Our country supports 11 areas for new renewable energy including sun light, solar heat and wind power. Among those areas, ocean thermal energy specifies tidal power generation using tide of sea, wave and temperature differences, wave power generation and thermal power generation. But heat use of heat source from sea water itself has been excluded as non-utilized energy. In the future, sea water heat source which has not been used so far will be required to be specified as new renewable energy. This research is to survey local heating system in Europe using sea water, central solar heating plants, seasonal thermal energy store and to analyze large scale central solar heating plants in German. Seasonal thermal energy store necessarily need to be equipped with large scale thermal energy store. Currently operating central solar heating system is a effective method which significantly enhances sharing rate of solar heat in a way that stores excessive heat generating in summer and then replenish insufficient heat for winter. Construction cost for this system is primarily dependent on large scale seasonal heat store and this high priced heat store merely plays its role once per year. Since our country is faced with 3 directional sea, active research and development for using sea water heat as cooling and heating heat source is required for seashore villages and building units. This research suggests how to utilize new energy in a way that stores cooling heat of sea water into seasonal thermal energy store when temperature of sea water is its lowest temperature in February based on West Sea and then uses it as cooling heat source when cooling is necessary. Since this method utilizes seasonal thermal energy store from existing central solar heating plant for heating and cooling purpose respectively twice per year maximizing energy efficiency by achieving 2 seasonal thermal energy store, active research and development is necessarily required for the future.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
• /
• v.24 no.1
• /
• pp.29-45
• /
• 1996

Before (March 26, 1994) or after the occurrence of a downslope windstorm (March 29), the NO, $NO_2$, and $SO_2$ at the ground level of Kangnung city were monitored with high concentrations in the afternoon, due to a large amount of gases emitted from combustion of motor vehicle and heating apparatus, especially near 1600-1800 LST and 2000-2100 LST, but at night, they had low concentrations, resulting from small consumptions of vehicle and heating fuels. When both moderate westerly synoptic-scale winds flow over Mt. Taegwallyang and easterly meso-scale sea breeze during the day, atmospheric pollutants should be trapped by two different wind systems, resulting in higher concentration at Kangnung city in the afternoon. At night, the association of westerly synoptic wind and land breeze can produce relatively strong winds and the dissipation by the winds cause these low concentrations to lower and lower, as nightime goes on. From March 27 through 28, an enforced localized windstorm could be produced along the lee side of the mountain near Kangnung, generating westerly internal gravity waves with hydraulic jump motions. Sea breeze toward inland appartantly confines to the bottom of the eastern side of the mountain, due to the interruption of eastward violent internal gravity waves. As the windstorm moves down toward the ground, an encountering point of two opposite winds approaches Kangnung, and a great amount of NO and $NO_2$ were removed by the strong surface winds. Thus, their maximum concentrations are found to be near 18 and 20 LST, 17 and 21 LST. In the nighttime, the more developed storm should produce very strong surface winds and the NO and $NO_2$ could be easily dissipated into other place. The $SO_2$ concentration had no maximum value, that is, almost constant one all day long, due to its removal by the strong surface winds. Especially, the CO concentrations were slightly lower during the strom period than both before or after the strom, but they were nearly constant without much changes during the during the daytime and nighttime.

• Journal of Environmental Impact Assessment
• /
• v.16 no.6
• /
• pp.381-391
• /
• 2007

The air quality modeling was carried out to assess the impact of air quality for large scale urban development. The site for the assessment is Multi-fuctional Administrative City which locates in Yeongi-gun, Chungcheongnam-do and estimated population in 2030 is 500,000. Two automatic weather monitoring stations were installed to monitor the meteorological variables for a year and upper air meteorological parameters were measured using radiosonde for 5 days with 4 hours interval in every season. The air quality of standard air pollutants were also measured for 5 days continuously in every season. The results of wind field analysis based on the site measurements and CALMET modeling showed that the valley and mountain winds were prevailed when the sypnotic wind was weak. It also showed that wind speed and directions were highly space-variable within the site basin. The variable wind characteristics implies that the Gaussian dispersion model such ISC3 and AERMOD are not appropriate and the unsteady-sate Lagrangian model such as CALPUFF is preferable. CALPUFF model was applied to assess air quality impact of new sources. The new sources were those for individual and group heating facilities as well as the traffic increases. The results showed that the estimated concentrations of CO and $SO_2$ pollutants by summing the impact concentration of new sources by the dispersion model and the ambient air concentrations by the site measurements were acceptable but those of PM-10 and $NO_2$ would violate ambient air quality standards at several locations due to high ambient air concentrations. It is recommended that the emission reductions near the site should be enforced to improve the ambient air quality.

• 한국태양에너지학회:학술대회논문집
• /
• 2008.11a
• /
• pp.202-207
• /
• 2008

Measures for coping with energy shortage are being sought all over the world. Following such a phenomenon, effort to use less energy in the design of buildings and equipment are being conducted. In particular, a program to evaluate the performance of a building comes into the spotlight. However. indispensable standard wether data to estimate the exact energy consumption of a building is currently unprepared. Thus, after appling standard weather data for four weather factors which were used in previous researches to Visual DOE 4.0, we compared it with the result of the existing data and evaluated them. For the monthly cooling and heating load of our target building, we used revised data for June, July, August, and September during which cooling load is applied. When not the existing data but the revised data was used, the research shows that an average of 14.9% increased in June, August, and September except for July. Also, in a case of heating load, the result by the revised data shows a reduction of an average of 11.9% from October to April during which heating load is applied. In particular, the heating loads of all months for which the revised data was used were more low than those of the existing data. In the maximum cooling and heating load according to load factors, the loads by residents and illumination for which the revised data was used were the same as those of the existing data, but the maximum cooling loads used by the two data have a difference in structures such as walls and roofs. Through the above results, the research cannot clearly grasp which weather data influences the cooling and heating load of a building. However, in the maximum loads by the change of weather data in four factors (dry-bulb temperature, web-bulb temperature, cloud amount, and wind speed) among 14 weather factors, the research shows that 5.95% in cooling load and 27.56% in heating load increased, and these results cannot be ignored. In order to make weather data for Performing energy performance evaluation for future buildings, the flow of weather data for the Present and past should be obviously grasped.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.5
• /
• pp.1340-1350
• /
• 1995

The effects of thermal stratification on the flow past a heated circular cylinder with various heating rates were examined in a wind tunnel. Turbulent intensities, r.m.s.values of temperature and turbulent convective heat flux distributions in the cylinder wakes with and without thermal stratification were measured by using a hot-wire and cold-wire combination probe. The phase averaging method was also used to estimate coherent contributions to the turbulent flow field in the near wake. The results show that the scalar mixing process is very different according to the mean temperature fields especially in the upper part of the wake. The coherent structure of the temperature field makes a large contribution to the time mean value like velocity components. However, the coherency of the temperature fluctuation is very different with the change of mean temperature fields, though the velocity coherent motions are quite similar in all experimental conditions.

• Journal of the Korean Society of Safety
• /
• v.29 no.3
• /
• pp.20-27
• /
• 2014

Cooling equipment is the frequent occurrence of fire despite the absence of the heating element. National fire statistics in 2013 show that a total of 263 fires occurred in the cooling equipment and the number of electric fan has 145 fire cases. This is accounted for 55.1% of the whole. Electric fan is the electrical appliance that the heat is generated on the winding wire and the iron core. If such characteristic is not controled properly, fire would break out at the electric fan. also there is a gap filled with an insulator between connection terminals of the capacitor in the electric fan. But in case that the gap on the capacitor is covered with some conductive material such as dust, there would be a fire as well caused by electrical heating locally. Although many studies related with those have been conducted, electric fan fire is continuously occurred. In this study, thermal characteristics and current signal in various conditions such as the heat generation of windings including iron cores of the motor and the dielectric breakdown of terminals on the capacitor connected to the motor were detected. In order to measure the maximum temperature, "third level" wind velocity button was pushed and the time selection switch to "continuation" was set. Analyzed data would be available for the fire safety of the electric fan.

• Journal of the Korean Solar Energy Society
• /
• v.22 no.4
• /
• pp.107-119
• /
• 2002

A review on the papers published in the Korean Journal of Solar Energy between 2000 and 2002 has been done. Focus has been put on current status of research in the aspect of Insolation. Solar Collector and Storage System, Solar Heating and Cooling System, Solar Cell and Lighting System, Active and Passive Solar Building, Heat Transfer in Solar Energy and Natural Energy. The conclusions are as follows. 1) Many studies on Insolation were conducted to optimize the usage of Solar Energy. 2) A review of the recent studies on solar thermal shows that there were many papers on solar collector and storage system. However, studies on the HVAC system using solar energy were relatively insufficient. 3) To produce high efficient solar cell. various experimental and numerical papers were published. However studies on control system, solar cell and lighting were seemed to be insufficient. 4) Studies on using solar energy in passive solar buildings were widely carried out, however, studies based on synthetic analysis of buildings and BIPV were insufficient. 5) Studies on heat transfer were mainly about heat exchanger, performance of heat pipe and multi air conditioner. 6) Studies on energy resources except for solar energy, such as hydraulic power and wind power etc. were very few.