• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.5
• /
• pp.657-666
• /
• 2017

In this study, factor analysis was performed to reduce the friction in the elevation motion of a stand for a 50-inchtelevision. Pipe type cross-section control was used for accurate positioning control of the piston rod. The pipe type was also compared with a labyrinth-type crosssection for the orifice. The frictional force was then reduced using gas seal lip technology. Specifications were chosen, and a volume compensation experiment was carried out using an apparatus for compensating the volume of the cylinder, which is compressed by the volume of the piston rod. Based on CAE and experimental considerations, the labyrinth-type orifice is preferred for reducing friction. For the gas seal lip technology, outer and inner diameters of ${\Phi}20$ and ${\Phi}8$ for the hollow rod were more appropriate when assuming the weight of a 50-inch television to be 30kgf. The third is that the result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod ?8x?4 and riveting system. The last is that the labyrinth orifice is not founded that of the ${\O}0.4{\sim}0.6$ orifice both tests on 300 mm intervals.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.434-435
• /
• 2012

Plasma enhanced chemical vapor deposition (PECVD) silicon dioxide thin films have many applications in semiconductor manufacturing such as inter-level dielectric and gate dielectric metal oxide semiconductor field effect transistors (MOSFETs). Fundamental chemical reaction for the formation of SiO2 includes SiH4 and O2, but mixture of SiH4 and N2O is preferable because of lower hydrogen concentration in the deposited film [1]. It is also known that binding energy of N-N is higher than that of N-O, so the particle generation by molecular reaction can be reduced by reducing reactive nitrogen during the deposition process. However, nitrous oxide (N2O) gives rise to nitric oxide (NO) on reaction with oxygen atoms, which in turn reacts with ozone. NO became a greenhouse gas which is naturally occurred regulating of stratospheric ozone. In fact, it takes global warming effect about 300 times higher than carbon dioxide (CO2). Industries regard that N2O is inevitable for their device fabrication; however, it is worthwhile to develop a marginable nitrous oxide free process for university lab classes considering educational and environmental purpose. In this paper, we developed environmental friendly and material cost efficient SiO2 deposition process by substituting N2O with O2 targeting university hands-on laboratory course. Experiment was performed by two level statistical design of experiment (DOE) with three process parameters including RF power, susceptor temperature, and oxygen gas flow. Responses of interests to optimize the process were deposition rate, film uniformity, surface roughness, and electrical dielectric property. We observed some power like particle formation on wafer in some experiment, and we postulate that the thermal and electrical energy to dissociate gas molecule was relatively lower than other runs. However, we were able to find a marginable process region with less than 3% uniformity requirement in our process optimization goal. Surface roughness measured by atomic force microscopy (AFM) presented some evidence of the agglomeration of silane related particles, and the result was still satisfactory for the purpose of this research. This newly developed SiO2 deposition process is currently under verification with repeated experimental run on 4 inches wafer, and it will be adopted to Semiconductor Material and Process course offered in the Department of Electronic Engineering at Myongji University from spring semester in 2012.

• Journal of the Korean Data and Information Science Society
• /
• v.26 no.6
• /
• pp.1409-1416
• /
• 2015

The change of temperature influences on the various aspect, especially human health, plant and animal's growth, economics, industry, and culture of the country. In this article, the autoregressive error (ARE) model has been considered for analyzing the monthly temperature data at the Suwon monitoring site in Korea. In the ARE model, five meteorological variables, four greenhouse gas variables and five pollution variables are used as the explanatory variables for the temperature data set. The five meteorological variables are wind speed, rainfall, radiation, amount of cloud, and relative humidity. The four greenhouse gas variables are carbon dioxide ($CO_2$), methane ($CH_4$), nitrous oxide ($N_2O$), and chlorofluorocarbon ($CFC_{11}$). And the five air pollution explanatory variables are particulate matter ($PM_{10}$), sulfur dioxide ($SO_2$), nitrogen dioxide ($NO_2$), ozone ($O_3$), and carbon monoxide (CO). Among five meteorological variables, radiation, amount of cloud, and wind speed are more influence on the temperature. The radiation influences during spring, summer and fall, whereas wind speed influences for the winter time. Also, among four greenhouse gas variables and five pollution variables, chlorofluorocarbon, methane, and ozone are more influence on the temperature. The monthly ARE model explained about 43-69% for describing the temperature.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.6
• /
• pp.463-468
• /
• 2013

The level of nitrous oxide ($N_2O$), a long-lived greenhouse gas, in atmosphere has increased mainly due to anthropogenic source, especially application of nitrogen fertilizers. Quantifying $N_2O$ emission from agricultural field is essential to develop national inventories of greenhouse gases (GHGs) emission. The objective of the study was to develop emission factor to estimate direct $N_2O$ emission from agricultural field in Gangwon-do, Korea by measuring $N_2O$ emissions from potato (Solanum tuberosum), red pepper (Capsicum annum L.), and Chinese cabbage (Brassica campestris L.) cultivation lands from 2009 to 2012. Accumulated $N_2O$ emission was $1.48{\pm}0.25kg$ $N_2O-N\;ha^{-1}$ for red pepper, $1.27{\pm}0.27kg$ $N_2O-N\;ha^{-1}$ for potato, $1.49{\pm}0.06kg$ $N_2O-N\;ha^{-1}$ for Chinese cabbage cultivated in spring, and $1.14{\pm}0.22kg$ $N_2O-N\;ha^{-1}$ for fall Chinese cabbage. Emission factor of $N_2O$ calculated from accumulated $N_2O$ emission, nitrogen fertilization rate, and background $N_2O$ emission was $0.0051{\pm}0.0016kg$ $N_2O-N\;ha^{-1}$ N for cropland in Gangwon province. More extensive study is deserved to be conducted to develop $N_2O$ emission factor for upland crops in Korea through examining the emission factors from various regions and crops because $N_2O$ emission is influenced by many factors including climate characteristics, soil properties, and agricultural practices.

• The Korean Journal of Ecology
• /
• v.16 no.4
• /
• pp.397-408
• /
• 1993

Gas exchange rates and concentrations of ascorbate and glutathlone were measured in needles of eastern white pine(Pinus strohltr) trees differing in foliar sensitivity to ambient oxidant pollution during a ten month period beginning in mid-June, 1988. Current-year needle dry mass and length was 60 to 75% and 45 to 60% less, respectively, in sens~tive trees than in a tolerant tree. Net photosynthesis ($P_n$) and needle conductance ($g_n$) were greatest in the tolerant individual through late September when the rates begin to decline In trees. Needle transpiration rates showed a trend similar to $P_n$ and $g_n$. Ascorbate and total glutathione concentrations in current-year needles increased through the summer and fall, reached a maximum in mid-winter, and then decreased in the spring. Consistently throughout the year, ascorbate concentration was highest in the tolerant tree until the initial springtime decline began in April. The difference In needle ascorbate between the tolerant and sensitive individuals was greater in the summer months (25 to 30%) than in the winter months (8 to 19%). Glutathione content was similar, as was the ratio or oxidized /reduced glutathione, in both tolerant and sensitive trees.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2000.11b
• /
• pp.91-95
• /
• 2000

With 106 detached houses where the aged people live alone, this study was conducted to perform a location survey of their residential environment. The result of this study is summarized as follows: While the surveyed houses' safety, sanitation and convenience appeared to be positive, with respect to the conditions of location, 73％ of the surveyed houses did not meet the requirement for comfort. The average area of each space indicated that the bedding room was 12.05$m^2$, the living room 14.71$m^2$, the kitchen 9.06$m^2$, the bathing room 4.05$m^2$, and the rest room 2.59$m^2$. Then, 93.3％ of the bedding rooms had the doorsill. Also, 97.2％ of the surveyed houses had retrievable space. The form of their living room door showed a hinged door(54.5％) and a sliding door(45.5％) which were similar with each other. The finished material was that wood accounted for 42.6％ which was highest. The cooking table form of kitchen was mainly "\ulcorner"-shaped(49.5％) and "\ulcorner"-shaped(48.5％) which were highest, and their average height appeared to be 815mm. The fuel used for kitchen was that gas accounted for 93.3％, while 95.2％ of the surveyed houses was not equipped with any gas-warning device. 75.5％ had an integrated type of bath room and toilet. In addition, the stepped difference between the bath room and other space was that 70.8％ had the difference, but they had no a satisfactory sliding-prevention device(Not for 91.6％) or heating system(Not for 92.9％).stem(Not for 92.9％).

• Journal of the Korean Institute of Gas
• /
• v.11 no.4
• /
• pp.85-90
• /
• 2007

This paper presents the finite element analysis on the strength safety of a full containment LNG storage tank system with damping safety structures. For the FEM analysis of the inner tank, the combined loads in which are related to a hydrostatic pressure, a cryogenic temperature load, BOG pressure, LNG weight, and a sinking force at the comer of the inner tank have been applied to the inner tank structure. The FEM computed results show that the conventional inner tank is safe for the given combined loads, but the damping safety structure such as compressive springs may be more useful structures to increase the safety of the tank system. The increased stiffness and the appropriate position of the springs are very important design parameters for increasing the damping strength safety of the tank system.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.14 no.4
• /
• pp.1-9
• /
• 2010

Fuel shutoff valve of a gas generator controls propellant mass flowrate of a rocket engine, by using pilot pressure and spring force. The developing fuel shutoff valve can be self sustained even though pilot pressure is removed in an actuator. Therefore, it is necessary to analyze the characteristics of the forces with respect to the opening and closing of the valve in order to evaluate its performance. In light of this, the valve has been designed to adjust the control pressure for the opening of the poppet and to determine the working fluid pressure at which the valve starts to close. This paper also has been designed dynamic model using the AMESim and predicted flow coefficient of the valve by Fluent CFD analysis. Various results from the prediction and the analysis have been compared with experiments. Finally, dynamic characteristics of the valve have been verified with experimental results.

• Korean Journal of Soil Science and Fertilizer
• /
• v.50 no.6
• /
• pp.530-537
• /
• 2017

Composted animal manure added for improving soil quality and enhancing crop productivity can lead to greenhouse gas emissions such as nitrous oxide ($N_2O$) by processes of nitrification and denitrification. In addition, the amount of $N_2O$ emission from composted manure amended soils can vary greatly with composted manure type or different soil type. Therefore, the influence of cattle composted manure on $N_2O$ emissions was evaluated during growth of sweet potato (Ipomoea batatas). The treatments included control, conventional fertilization (CF), and CF + cattle composted manure (CCM) $10Mg\;ha^{-1}$ were applied in the spring. $N_2O$ emissions were significantly affected by composted manure and chemical fertilizer and the CCM had greater N2O emissions compared with other treatments. The majority of $N_2O$ emissions occurred shortly after composted manure and chemical fertilizer application compared with the rest of the growing seasons for all treatments. Also, $N_2O$ flux was associated with water-filled pore space (WFPS) at all treatments. On average of $N_2O$ emission accumulation, the CCM was 1.5 times greater than control treatment while there was no difference between CF and control.

• Journal of East-West Nursing Research
• /
• v.29 no.2
• /
• pp.129-140
• /
• 2023

Objectives: Suicide rate in South Korea is one of the major public health concerns. This study examined the factors influencing the suicide methods of people who committed suicide in Gyeonggi-do, which accounts for one-fourth of the population of South Korea. Methods: This study analyzed the data of a total of 13,945 suicide deaths in Gyeonggi-do over a five-year period (2016-2020) provided by the Statistics Korea and the influence of social and demographic characteristics on the analyzed suicide methods. The differences in suicide methods according to the social and demographic characteristics of suicide victims were compared and analyzed through chi-squared, and items with significant differences in univariate tests were analyzed by multiple logisitic regression analysis. Results: Among suicide deaths, the most common method of suicide was hanging (52.4%). In particular, women, were employed, and stayed at home were higher risk of being hanged. The second most common method of suicide was leaping (17.7%). Women under the age of 30, those with a college degree or higher, those who were not working, time of death (6-12), and those outside the home were more likely to choose to take the leap. The third most common method of suicide was gas poisoning (15.8%). Young people under the age of 65, college graduates or higher, without a spouse, were employed, and spring season were at increased risk of choosing gas poisoning. Conclusions: The results highlight the need for policies that consider risk factors such as gender, age, education, marital status, employments status, time of suicide, and place of suicide in order to block access to suicide methods for suicide victims in Gyeonggi-do.