• 한국안전학회지
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• 제20권1호
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• pp.75-80
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• 2005

In this paper, when CF/EPOXY laminates for high efficiency space structure are subjected to FOD(Foreign Object Damage), the effects of temperature change on the impact damages(inter laminar separation and transverse crack) of CF/EPOXY laminates and the relationship between residual life and impact damages ale experimentally investigated. Composite laminates used in this experiment are CF/EPOXY orthotropic laminated plates, which have two-interfaces $[0^{\circ}_6/90^{\circ}_6]S$ and four-interfaces $[0^{\circ}_3/90^{\circ}_6/0^{\circ}_3]S$. CF/EPOXY specimens with impact damages caused by a steel ball launched from the air gun were observed by the scanning acoustic microscope under room and high temperatures. In this experimental results, various relations were experimentally observed including the delamination area vs. temperature change, the bending strength vs. impact energy and the residual bending strength vs. impact damage of CF/EPOXY laminates. And as the temperature of CF/PEEK laminates increases, the delaminaion areas of impact-induced damages decrease linearly. A linear relationship between the impact energy and the delamination areas were observed. As the temperature of CF/PEEK laminates increases, the delamination areas decrease because of higher initial delaminatin damage energy.

• 한국안전학회지
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• 제11권1호
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• pp.75-83
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• 1996

This paper was concerned with pool fire about many used kerosene and diesel oil. In order to know the thermal effects of kerosene and diesel oil, temperature change in the pool fire of these fuels were obtained as a variation of combustion time and the tank's height and diameter by using the data acquisition system, And fuel combustion velocity were derived as a function of the diameter and wall thickness of tanks and combustion time. As a result, when the tank's height was 15㎝, the greater diameter the higher temperature rising regardless of tank's wall thickness and fuels. But, when the tank's height is 30㎝, temperature rising was not higher than 15㎝. Also, temperature rising in the pool fire of kerosene much higher than diesel oil. Kerosene's combustion velocity was about two times faster than diesel oil. And, kerosene's combustion velocity was increased according to the increasing of tank's diameter and combustion time. But, diesel oil's combustion velocity was a little increased or not. Surrounding temperature change of tank with the pool fire was obtained temperature distribution of 0∼35℃ according to the change of tank's diameter and distance from the tank's wall.

• Advances in nano research
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• 제6권1호
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• pp.57-80
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• 2018

In this study, the thermal loading effect on free vibration characteristics of carbon nanotubes (CNTs) with multiple cracks is studied. Various boundary conditions for nanotube are taken in to account. In order to take the small scale effect, the nonlocal elasticity of Eringen is employed in the framework of Euler-Bernoulli beam theory. This theory states that the stress at a reference point is a function of strains at all points in the continuum. A cracked nanotube is assumed to be consisted of two segments that are connected by a rotational spring which is located in the position of the cracked section. Hamilton's principle is used to achieve the governing equations. Influences of the nonlocal parameter, crack severity, temperature change and the number of cracks on the system frequencies are investigated. Also, it is found that at room or lower temperature the natural frequency for CNT decreases as the value of temperature change increases, while at temperature higher than room temperature the natural frequency of CNT increases as the value of temperature change increases. Various boundary conditions have been applied to the nanotube.

• 수산경영론집
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• 제46권2호
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• pp.31-41
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• 2015

This study aimed to analyze the relationship between sea surface temperature as a climatic element and catch amount of offshore and coastal fisheries in Korea using annual time series data from 1970 to 2013. It also tried to predict the future changes in catch amount of fisheries by climate change. Time series data on variables were estimated to be non-stationary from unit root tests, but one long-term equilibrium relation between variables was found from a cointegration test. The result of Granger causality test indicated that the sea surface temperature would cause directly changes in catch amount of offshore and coastal fisheries. The result of regression analysis on sea surface temperature and catch amount showed that the sea surface temperature would have negative impacts on the catch amount of offshore and coastal fisheries. Therefore, if the sea surface temperature would increase, all other things including the current level of fishing effort being equal, the catch amount of offshore and coastal fisheries was predicted to decrease.

• 한국전기전자재료학회논문지
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• 제30권5호
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• pp.284-287
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• 2017

The electrocaloric effect in $0.94(Bi_{0.5}Na_{0.5})TiO_3+0.06KNbO3+0.9wt%$ G.F.ferroelectricceramics was observed in terms of the temperature change (${\Delta}T$) of the fabricated ceramics, Curie temperature $T_c$, and applied electric field. The specimens were fabricated by a conventional solid-state reaction. $T_c$ appeared near $165{\sim}170^{\circ}C$. The P-E hysteresis showed a tendency to slim down with a temperature increase and finally was slimmest near $150^{\circ}C$. With the increase of temperature, the polarization revealed a gradual decrease, and a sharp decline near $T_c$. When an electric field of 45 kV/cm was applied, the largest polarization was shown. The maximum value of the temperature change (${\Delta}T=0.31^{\circ}C$) was obtained at $165^{\circ}C$ under an applied electric field of 45 kV/cm.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.11-12
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• 2017

This study aims to analyze the properties of the temperature change in vertical reinforcements in outdoor wall structures in winter in relation to the different methods of bubble sheet installation, and to subsequently determine the possibility of initial frost damage to the concrete as a result of low temperature. As for the experimental variables, double bubble sheets were used as curing materials, and the curing method was to model the part where the slab and the wall intersect and the rebar is exposed, and to measure the change of temperature around the exposed rebar in accordance with the change of the coating curing. It was found that by employing curing method B, which is to install the bubble sheet between the vertical reinforcements, the most vulnerable area, which is 50mm below(④) the surface of the concrete, would be lowered to sub-zero temperature 20 hours later than when using curing method A, and that therefore it is more effective to install the bubble sheet between the vertical reinforcements for the prevention of initial frost damage.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.256-262
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• 2011

Environmental pollution by Using of a fossil fuel, a reckless and growth-oriented development since the Industrial Revolution has caused global change of environment. An issue largest among this is a climate change. A global mean temperature since 19th century has climbed up $0.4{\sim}0.8^{\circ}C$. After The Kyoto Protocol regarding a greenhouse gas reduction goal took effect, be situations that decrease of greenhouse gas was acutely required. Interest of utilization of the new & renewable energy is increasing every day. This study shows that at first divided a country to nine range by natural geography, and second executed Meteorological data analysis of recent 30 years considering level of significance by nine range. The results of this study are that in heating load calculation of building, periodic temperature data management is required because facility capacity and cost are affected greatly by outdoor temperature, and temperature by climate range needs consideration of pertinent area. Lastly, ground temperature was assumed of the weather in region, the ground and soil.

• Journal of the Optical Society of Korea
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• 제8권4호
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• pp.168-173
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• 2004

Brillouin scattering-based fiber optic sensors are useful to measure strain or temperature in a distributed manner. Since the Brillouin frequency of an optical fiber depends on both the strain and temperature, it is very important to know whether the Brillouin frequency shift is caused by the strain change or temperature change. This article presents a temperature compensation technique of a Brillouin scattering-based fiber optic strain sensor. Both the changes of the Brillouin frequency and the Brillouin gain power is observed for the temperature compensation using a BOTDA sensor system. Experimental results showed that the temperature compensated strain values were highly consistent with actual strain values.

• 열처리공학회지
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• 제23권6호
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• pp.315-322
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• 2010

Effect of hardenability, grain size and microstructural change according to the change of austenitizing temperature was analyzed in Jominy hardenability test of AISI 51B20 steel. Grain growth was small, 7 ${\mu}m$ and 12 ${\mu}m$ austenite grain sizes at austenitizing temperature of $900^{\circ}C$ and $1000^{\circ}C$, respectively, while rapid grain growth was observed up to 30 ${\mu}m$ austenite grain size at austenitizing temperature of $1100^{\circ}C$. As austenitizing temperature increased from $900^{\circ}C$ to $1100^{\circ}C$, hardenability in the region within 15 mm from end-quenched surface decreased due to the grains growth of bainite and martensite mixture, on the other hand the hardenability in the region exceeding 15 mm from end-quenched surface increased. Increased hardenability was attributed to different microstructures; pearlite, fine pearlite and bainite, and bainite and martensite structures at austenitizing temperature of $900^{\circ}C$, $1000^{\circ}C$ and $1100^{\circ}C$, respectively.

• 반도체디스플레이기술학회지
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• 제10권4호
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• pp.21-23
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• 2011

Uniformity of plasma etching processes critically depends on the wafer temperature and its distribution. The wafer temperature is affected by plasma, chucking force, He back side pressure and the surface temperature of ESC(electrostatic chuck). In this work, 3D mathematical modeling is used to investigate the influence of the geometry of coolant path and the temperature distribution of the ESC surface. The model that has the coolant path with less change of the cross-sectional area and the curvature shows low standard deviation of the ESC surface temperature distribution than the model with the coolant path of the larger surface area and more geometric change.