• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.46-53
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• 2005

We have analyzed the temperature and humidity aging test results of a composite solid propellant. The temperature aging test was performed to evaluate the storage life of a propellant, while the humidity aging test could provide the hygroscopicity of Ammonium Perchlorate(AP) exposed to .elative humidity (RH) 10, 30, $50\%$ environment. A specimen was used in the temperature test, and a block of propellant from the actual motor was used in the humidity test. We report that the 4-month storing at 60 degree is equivalent to the 10-year 60 degree condition. The composite solid propellant with HTPB binder showed signs of hardening with time lapse but the effect of humidity up to RH $50\%$ was not noticeable.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.105-108
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• 2008

Nowadays, as there is so much interest in environment, hydrogen peroxide attracts attention as an eco-propellant. Hydrogen peroxide is widely used for mono-propellant of thruster, and oxidizer of bi-propellant rocket. Especially, it is used as mono-propellant of the thruster for attitude control of satellite and military weapons. So, the need of long time storage of hydrogen peroxide appears and storage test is required. In this paper, necessity of storage test of hydrogen peroxide and some conditions and methods are introduced. In addition, the results of storage tests under some condition are compared and analyzed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.157-162
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• 2012

The basic study for combustion characteristics of micron-sized aluminum powder with water suspension was carried out. Under atmospheric pressure, the combustion characteristics of aluminum powder with water suspension was studied by adjust the equivalent ratio and the density of a mixture which effect on burning rate. Based on atmospheric pressure's result, the device for the combustion characteristics of aluminum powder with water suspension under high-pressure environment was developed. In the pressure range from 2 to 50 atm the effect of pressure to burning rate was same as the case of nano-aluminum with water suspension, but the pressure range from 50 to 70 atm the sharp increase in burning rate was observed. In the experiment of varying the equivalence ratio, the combustion did not proceed in the condition of excess oxidizer (eq = 1.5).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.3
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• pp.103-109
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• 2016

The purpose of this study is to perform comparative economic evaluation for the systems of ground source heat pump (GSHP) and district heating and cooling (DHC) by focusing on the analysis of operation case of GSHP. The adapted research object is a public office building located in Seoul. The capacity of ground source pump is about 3,900 kW. Ground heat exchanger is closed loop type. The analysis period for life cycle cost is 30 years. Economic evaluation is assessed from the viewpoints of the following four parts: initial cost, energy cost, maintenance and replacement cost, and environment cost. The total life cycle cost of GSHP is approximately 8,447 million won. The cost of the DHC System is approximately 3,793 million won. The cost of the DHC is approximately 46% lower than GSHP system under the condition of current rate for GSHP and DHC.

• Journal of the Korea Safety Management & Science
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• v.19 no.4
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• pp.25-34
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• 2017

Offshore plants should be managed at a high level of safety condition. Because the offshore plant has cramped space and has difficult access when a fire occurred, a fire can be critical to the plants. LED lighting can reduce the risk of fire by its lower energy consume suitable to intrinsic safety and lower heat radiation that can reduce the possibility of ignition. Also LED has a long lifetime. Though LED luminaire has various advantages for offshore plants, an international standard for the luminaire has not provided because it is new technology. Because there is no international and domestic standard specially provided for the LED luminaire, a guideline is required for developing the LED light and for the future establishment of an international standard. This study was conducted to develop the guideline for LED luminaire for offshore plants. Firstly, relevant standards were analyzed for the guideline. Then we found that there are editorial differences between international standards and domestic standards. So the guideline was developed based on international version and the differences between the domestic and international standard were provided to let Korean developers recognize the differences.

• Hwankyungkyoyuk
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• v.21 no.3
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• pp.26-40
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• 2008

This study aims to analyze the science content in secondary school environmental education(EE) textbooks and the environment-related content in secondary school science text- books. Firstly, a total of 73 EE and science textbooks for secondary students were reviewed, which three kinds of textbooks, secondary school EE textbooks and the 10th grade "Science" textbooks, were finally selected for analysis. Three researchers separately analyzed the textbooks using NAAEE framework(1996) for the development of EE materials. In condition that there was a disagreement in their opinion, they had discussed until they came to an agreement. The results showed that secondary school EE textbooks contained more and deeper science concepts than the 10th grade "Science" textbooks, which were evaluated better in all perspectives of the analysis framework. The 10th grade "Science" textbooks had more various teaching and learning activities than EE textbooks. It it expected that the new EE textbook developers should consider the ultimate goal of EE which focused the affective perspectives rather than the cognitive perspectives.

• Plant Journal
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• v.7 no.4
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• pp.58-66
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• 2011

The power plant companies reached the culmination for growth in the domestic market. Besides, we have faced many challenges such as an electricity opening market trend for overseas, banning the use of coal due to the United nations framework convention on climate change, and the meticulous attention regarding the government's electricity charge plan. On the other hand, the overseas business has been a critical issue since China and many other developing countries expanded their projects abroad. Another factor is that power plant industry is being privatized, and it made the market regulation a bit loose. Thus, the market environment became favorable toward those companies which planned many overseas businesses. In this research, the power plant company's current condition for construction and operation as well as its technical competitiveness were analyzed, and an alternative plan using SWOT analysis for entering an oversea market was made. It dealt with both internal and external factors. Also, examined was the current situation under the power plant industry dealing with restructure for electric industry, lack of fossil fuel, and the United nations framework convention on climate change. From the research, it was suggested that many successful strategies to enter the overseas business by using the market trend I researched.

• Steel and Composite Structures
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• v.25 no.2
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• pp.197-207
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• 2017

In this paper, Coriolis effect on vibration behavior of a rotating rectangular plate made of functionally graded (FG) materials under thermal loading has been investigated. The material properties of the FG plate are supposed to get changed in parallel with the thickness of the plate and the thermal properties of the material are assumed to be thermo-elastic. In this research, the effect of hub size, rotating speed and setting angle are considered. Governing equation of motion and the associated boundary conditions are obtained by Hamilton's principle. Generalized differential quadrature method (GDQM) is used to solve the governing differential equation with respect to cantilever boundary condition. The results were successfully verified with the published literatures. These results can be useful for designing rotary systems such as turbine blades. In this work, Coriolis and thermal effects are considered for the first time and GDQM method has been used in solving the equations of motion of a rotating FGM plate.

• Current Photovoltaic Research
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• v.9 no.3
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• pp.106-109
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• 2021

In order to perform photovoltaic (PV) operation and management (O&M) efficiently, individual PV module monitoring is becoming more important. In this research, we developed wireless IoT sensor which can monitor individual photovoltaic modules. This IoT sensor can detect the output voltage, current and module temperature of individual modules and provide monitored data by wireless communication. Measured voltage error was 1.23%, and it shows 16.6 dBM, 0.42sec and 7.1 mA for voltage, transmittance output, response time and mean power consumption, respectively. IoT sensors were demonstrated in the test field with real climate environment condition and each of 5 sensors showed precise results of voltage, current and temperature. Also, sensors were compared with commercial power-optimizers and showed result difference within 5%.

• Journal of Environmental Health Sciences
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• v.44 no.6
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• pp.599-607
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• 2018

Objectives: Carbon dioxide ($CO_2$) may be one of the biggest causes of climate change. The purposes of this study were to reduce greenhouse gases and to increase strawberry production by developing the supply devices in livestock facilities using the membrane technology Methods: Carbon dioxide was collected from beside to livestock facilities. The injection of $CO_2$ was stopped when it reached 1,000 ppm in the facility house. Case group with injection of $CO_2$ was compared to control group with normal environment. The experiments were conducted for 8 days from December 11, 2017. Results: Total strawberry production was found to be 1,317 kg in the case group and 1,176 kg in the control group. The correlation between $CO_2$ and crop yields has led to some statistical evidence that carbon dioxide helps to grow (${\beta}=0.832$, p<0.05). Conclusions: This study identified the potential for efforts to reduce the $CO_2$ in farming households. Increased concentrations of $CO_2$ have shown that strawberries have a better growth condition. In addition, it can be explained that the plants need wide leaves to quickly absorb much $CO_2$.