• Journal of Powder Materials
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• v.12 no.4 s.51
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• pp.266-272
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• 2005

Transition metal ions($Ni^{2+}$, $Cr^{3+}$ and $V^{5+}$) doped $TiO_2$ nanostructured powders were synthesized by mechanical alloying(MA) to shift the adsorption threshold into the visible light region. The synthesized powders were characterized by XRD, SEM, TEM and BET for structural analysis, UV-Vis and photoluminescence spectrum for the optical study. Also, photocatalytic abilities were evaluated by decomposition of 4-chlorophenol(4CP) under ultraviolet and visible light irradiations. Optical studies showed that the absorption wavelength of transition metal ions doped $TiO_2$ powders moved to visible light range, which was believed to be induced by the energy level change due to the doping. Among the prepared $TiO_2$ powders, $NiO^{2+}$ doped $TiO_2$ powders, showed excellent photooxidative ability in 4CP decomposition.

• Journal of the Korean housing association
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• v.24 no.5
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• pp.69-76
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• 2013

The seriousness of greenhouse gas exhaustions and energy use of the building has increased, the world is making an effort with many requests and the consultation for sustainable development. For this reason, Green Building Certification Criteria has been implemented to reduce environmental load, high-performance and environmentally friendly in the United States, the United Kingdom and Germany. In response to the global trend like this, the Korean Government has induced the eco-friendly construction and sustainable development to implement the G-SEED (Green Building Certification Criteria of Korea) in 2002. However, in spite of the many authentication result, G-SEED has been pointed out that it needs for improve in the evaluation system of Apartment sector which accounts for more than 40% of the authentication. Therefore, the purpose of this study is to suggest improvements in the evaluation system. To achieve this, this study have selected for LEED, BREEAM, DGNB of comparison target, drawn improvements through comparing transition process in G-SEED.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2368-2375
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• 1992

The transition of turbulent kinetic energy(TKE) balance along the centerline of the flow unit, which is composed of straight-duct, contraction and free-jet, has been investigated by the hot-wire anemometry. It is found that the mean turbulent kinetic energy is balanced by the dissipation in the internal flow region ; by the production and the dissipation, through contraction ; and by the dissipation, in initial region(X〈8D) of free-jet. But in the developing region (8D〈X〈20D) it is balanced by all of the three(ie, diffusion, production and dissipation). Finally, in the downstream of free-jet, the mean TKE is balanced again by dissipation like as the beginning. The decay-laws along the centerline are checked in the region of free jet as well as in the straightduct. After the developing region of free-jet also exist the decay-laws, the exponent of the axial turbulence being bigger than of the radial.

• Journal of Welding and Joining
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• v.7 no.3
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• pp.28-35
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• 1989

It was reported that the toughness for welded region was influenced by various factors such as the gradient for prior austenite grain size, the variation of microhardness and the characteristic microstructure depending on distance from the fusion boundary. Therefore, in order to evaluate the fracture strength of the weldment in which the microstructures change continuously, it is important to assess the peculiar strength of each microstructure in welded region. It was known that the small punch(SP) test technique which was originally developed to study the irradiation damage effect for the structures of nuclear power plant was also useful to investigate the strength evaluating of nonhomogeneous materials. In this paper, by means of a small punch test technique the possibility of evaluating strength of parent and welded region in SS41 and SM53B steels was investigated. The obtained results are summerized as follows: 1) The small punch test which showed markedly the ductile-brittle transition behavior in this experiment may be applied to evaluation for the fracture strength of welded region. 2) It was shown that the ductile-brittle regime lied in Region III(plastic membrane stretching region) of the flow characteristics observed in SP test. 3) The SP test technique which shows a more precipitous energy change transition behavior than the other test technique is able to estimate the more precise transition temperature. 4) It could be seen that in comparision with the structure of parent the structure of weld HAZ in SS41 steel was improved while it in SM53B steel was deteriorated.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.10
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• pp.1299-1307
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• 2010

This study was conducted to evaluate the effect of dietary antioxidant and energy density on performance and antioxidative status in transition cows. Forty cows were randomly allocated to 4 dietary treatments in a $2{\times}2$ factorial design. High or low energy density diets (1.43 or 1.28 Mcal $NE_L$/kg DM, respectively) were formulated with or without antioxidant (AOX, a dry granular blend of ethoxyquin and tertiary-butylhydroquinone; 0 or 5 g/cow per d). These diets were fed to cows for 21 days pre-partum. During the post-partum period, all cows were fed the same lactation diets, and AOX treatment followed as for the pre-partum period. Feeding a high energy diet depressed the DMI, milk yield, and 4% fat-corrected milk (FCM) of cows. However, AOX inclusion in the diet improved the milk and 4% FCM yields. There was an interaction of energy density by AOX on milk protein, milk fat and total solids contents. Feeding a high energy diet pre-partum increased plasma glucose and ${\beta}$-hydroxybutyrate, whereas dietary AOX decreased plasma ${\beta}$-hydroxybutyrate value during the transition period. There were also interactions between time and treatment for plasma glutathione peroxidase activity and malondialdehyde content during the study. Cows fed high energy diets pre-partum had higher plasma glutathione peroxidase activity 3 days prior to parturition, compared with those on low energy diets. Inclusion of AOX in diets decreased plasma glutathione peroxidase activity in cows 3 and 10 days pre-partum. Addition of AOX significantly decreased malondialdehyde values at calving. Energy density induced marginal changes in fatty acid composition in the erythrocyte membrane 3 days post-partum, while AOX only significantly increased cis-9, trans-11 conjugated linoleic acid composition. The increase in fluidity of the erythrocyte membrane was only observed in the high energy treatment. It is suggested that a diet containing high energy density pre-partum may negatively affect the anti-oxidative status, DMI and subsequent performance. Addition of AOX may improve the anti-oxidative status and reduce plasma ${\beta}$-hydroxybutyrate, eventually resulting in improved lactation performance; the response to AOX addition was more pronounced on the high energy diet.

• Journal of Hydrogen and New Energy
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• v.22 no.2
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• pp.274-282
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• 2011

This paper overviews the concept of the strategic niche management, which emphasises the social aspects of new technologies and calls for relevant government policies for socio-technical transition. Hydrogen energy technologies remain in the niche level, thus the SNM perspective is appropriate to be applied. The reason why, and the way how to see hydrogen as a socio-technical niche are discussed, followed by an analytic argument on hydrogen policies and their SNM characteristics. Final part of the paper deals the design of the socio-technical experiment. It is expected that this paper would contribute to not only policy development but also improving understandings on the socio-technical nature of hydrogen energy of hydrogen community.

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.124-129
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• 1986

The effects of molecular attraction and orientations for the energy mismatch variance, vibrational energy level and double-quantum transition, in the vibration-vibration energy exchange, have been considered. The contribution of molecular attraction increases the exchange rate of the purely repulsive interaction, in general, significantly, but which becomes smaller as the temperature is increased. As the energy mismatch is increased, its contribution is also increased, but which is small. However, its contribution for the double-quantum transition is very paramount. At each orientation, the exchange rate constants have been calculated and compared with the results for rotational average, and it is found that the exchange rate is a strong function of the orientation angles of colliding molecules. We have also discussed about the system having the strong interaction such as the hydrogen bond, and it is found that for this system the preferred orientation should be considered in order to calculate the exchange rates.

• Journal of the Korean Chemical Society
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• v.65 no.2
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• pp.145-150
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• 2021

The present study describes a hands-on experiment to help students understand the concept of phase change or phase transition and its application in a phase change material (PCM). PCMs are substances that have the capability of storing and releasing large amounts of thermal energy. They act as energy storage materials that provide an effective way to save energy by reducing the electricity required for heating and cooling. Lauric acid (LA) was selected as an example of the PCM. Students investigated the temperature change of LA and the temperature (of air) inside the test tube. The differences in the temperatures of the systems helped students understand how PCMs work. A one-group pretest and posttest design was implemented with 34 grade-11 students in science and mathematics. Students' understanding was assessed using a multiple-choice test and a questionnaire. The findings revealed that the designed activity helped students understand the concept of phase change and its application to materials for thermal energy storage.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.8
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• pp.44-52
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• 1998

The theoretical modeling of transition energy and absorption coefficient for intersubband transitions in quantum wells in presented. We include, as well as hartree and exchange-correlation potentials, boht depolarization effect and exciton-like effect which play great roles in heavily doped cases where practically reasonable absorption coefficients are available. Also, the calculated results are compared with the existing experimental values for .delta.-doped Si quantum wells to check the validity of our theoretical calculation.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.2056-2065
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• 2021

The transition toward clean energy is an issue of great importance with growing debate in climate change mitigation. The complex nature of nuclear energy-CO₂ emissions nexus makes it difficult to predict whether or not nuclear acts as a clean energy source. Hence, we examined the relationship between nuclear energy consumption and CO₂ emissions in the context of the IPAT and Environmental Kuznets Curve (EKC) framework. Dynamic Auto-regressive Distributive Lag (DARDL), a newly modified econometric tool, is employed for estimation of long- and short-run dynamics by using yearly data spanning from 1971 to 2018. The empirical findings of the study revealed an instantaneous increase in nuclear energy reduces environmental pollution, which highlights that more nuclear energy power in the Indian energy system would be beneficial for climate change mitigation. The results further demonstrate that the overarching effect of population density in the IPAT equation stimulates carbon emissions. Finally, nuclear energy and population density contribute to form the EKC curve. To achieving a cleaner environment, results point out governmental policies toward the transition of nuclear energy that favours environmental sustainability.