• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1354-1357
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• 2017

Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for $^{252}Cf$ and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-of-flight kinematics can be used. With this system, energy spectra can also be obtained as a function of position. Spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.363-364
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• 2010

Most LED drivers uses current control method to adjust LED current. Using AC power grid such as off-line converter, Buck topology is popular because input voltage of LED driver is much higher than LED output voltage. Normally DCM current control is more popular than CCM current mode control in the range of below 50W, But DCM characteristics are dependent on the input voltage variation. This paper deals with what should be considered in DCM for LED driver with valley fill circuit.

• Nuclear Engineering and Technology
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• 제37권1호
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• pp.101-108
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• 2005

The neutron induced nuclear cross-section data for Pd-105, Ag-109, Xe-131, and Cs-133 were calculated and evaluated from an unresolved energy to 20 MeV. The energy dependent optical model potential parameters were extracted based on recent experimental data and applied up to 20 MeV. A spherical optical model and a statistical model for the equilibrium energy, and a multistep direct and a multistep compound model for the pre-equilibrium energy were used in the calculation. The direct capture model was recently introduced for fast neutron capture. The theoretically calculated cross-sections were compared with the experimental data and the evaluated files. The total and capture cross-sections calculated using the model were in good agreement with the reference experimental data. The evaluated cross-section results were compiled in ENDF-6 format and merged with the resonance component, already adopted in the ENDF/B-VI release 8. New data library files covering from thermal to 20 MeV were created. They are at the preliminary stage of an ENDF/B- VII release.

• 한국수소및신에너지학회논문집
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• 제35권3호
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• pp.269-279
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• 2024

Saudi Arabia is transitioning from its traditional oil-dependent economy to become a leader in the hydrogen industry. This paper explores the kingdom's strategic investments in hydrogen production and infrastructure as key components of its energy diversification and sustainability efforts. The focus is on enhancing green hydrogen production to meet domestic needs and strengthen its position in the global market. The urgency of diversifying energy sources is emphasized, with projects like the NEOM Green Hydrogen Project illustrating Saudi Arabia's commitment to renewable energy integration. These initiatives are positioned to centralize Saudi Arabia in the global shift toward sustainable energy, signaling a significant pivot in its economic and environmental policies.

• Nuclear Engineering and Technology
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• 제9권2호
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• pp.75-81
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• 1977

원자력 발전소에서 나오는 방사성 핵종이 clay 속에 고정되는 반응기구를 분석하기 위해서 clay의 양이온 교환능을 Sawhney 방법으로 측정했다. Clinoptilolite, vermiculite 및 sodalite들의 PH dependent CEC를 측정한 결과 총 양이온 교환능의 약 70% 정도가 영구 고정되어진다고 생각되는 neutral salt CEC에 의해 일어나고 나머지는 가역과정인 clay 속의 유기물질과 다른 급속(Al, Mg)의 치환에 의해서 일어난다는 결론을 얻었으며, pH 9 이상에서 clay에 의한 방사성 핵종의 제거는 이온 교환 기구에 의한 고정보다 오히려 중금속 이온의 침전에 의해서 더 많이 일어난다는 것도 밝혀냈다. 그리고 연속 치환에 의해서 처리된 Na-clay는 방사성 핵종제거에 상당히 향상된 제거 효율을 나타내고 있다.

• 한국태양에너지학회 논문집
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• 제33권6호
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• pp.98-104
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• 2013

At the moment, in Korea, over 90% of energy resources depend on imports, and nearly 60% of electric energy is produced using fossil fuel. Therefore, the government adopted the Climatic Change Convention and has implemented the RPS system since 2012 to actively cope with the dependence on imported energy, and to grow and expand the new renewable energy industry. This study examined the performance results of mandatory supply of solar photovoltaic energy and non-solar photovoltaic energy assigned to providers and the present state after implementation of the RPS system. As a result, the achievement rate in 2012 was 64.7%. Especially, solar photovoltaic energy showed a high achievement rate of 95.7%, whereas non-solar photovoltaic energy showed a low achievement rate of 63.3% due to several problems and was highly dependent on the government. In 2013, the burden of each provider has increased due to more mandatory supply and addition of unfulfilled supply of 2012, and the separate mandatory supply of solar photovoltaic energy established for protection of the solar photovoltaic market is restricting investment. Therefore, there is a need to assign mandatory supply in consideration of the available amount of each new renewable energy.

• Design & Manufacturing
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• 제13권1호
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• pp.19-24
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• 2019

Currently, the world is paying keen attention to the production of renewable energy along with environmental issues, and the share of renewable energy in the world is rising above that of nuclear power. Especially when Korea, which is heavily dependent on foreign countries, needs to reconsider its national competitiveness due to the recent high oil prices, the government's energy policy is to develop and use renewable energy that replaces fossil fuels. In particular, solar energy, the most actively studied and commercialized field of renewable energy, is the main research for solar energy and is commercialized and used. However, the efficiency of solar energy has already reached saturation. Studies are also focusing on increasing the reflectivity of solar energy to increase efficiency. Therefore, this paper proposes a solar collection system that can utilize solar energy rather than solar energy. The proposed solar heat collection system uses solar tracking systems to effectively collect solar energy, particularly those that can be easily produced using single-modular reflectors and have price competitiveness. In addition, temperature measurement experiments with temperature measuring sensors were conducted to ensure reliability in order to verify the results interpreted.

• 신재생에너지
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• 제6권3호
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• pp.13-21
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• 2010

This paper analyzes the factors of renewable energy consumption in Korea, China and Japan. We consider renewable energy consumption per capita as dependent variable, GDP per capita, $CO_2$ emissions per capita and real oil prices as independent variables. To analyze this model, this paper uses three econometric methods such as OLS, fixed effect model and panel GLS, utilizing data from 1990 to 2006 in Korea, China and Japan. According to the results by OLS for each country, an increase in GDP per capita or $CO_2$ emissions per capita or oil prices leads to an increase in renewable energy consumption. According to the results by fixed effect model, an increase in GDP per capita or $CO_2$ emissions per capita leads to an increase in renewable energy consumption. And real oil prices do not have a significant impacts on this model. According to the results by panel GLS, an increase in real GDP per capita as a proxy of income leads to an increase renewable energy consumption. And both $CO_2$ emissions per capita and real oil prices do not correlated closely with renewable energy consumption. Thus oil is not substituted to renewable energy in Northeast asian countries.

• 한국태양에너지학회 논문집
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• 제26권1호
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• pp.99-104
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• 2006

This paper presents an analysis of heating energy for apartment houses in apartment building, paying special attention on the effect of pilotis which is increasing recently. A four-zone model composed of one conditioned and three unconditioned space is developed in this study. IES VE is adopted to estimate heating energy. Especially, we used Apache module for a heating energy calculated. The predicted result shows fairly good agreements with the available measured data and simulation data. Heating energy needed for an apartment located on the pilotis floors is far greater compared with the case of intermediate floors. Insulation thickness of walls, floors and underground structure appears to be a dominant factor affecting heating energy, which leads to needs of revision of the related regulation. It is finally concluded that the location dependent, severe imbalance in heating energy should be improved and reflected in the policy making process and the design standards.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.559-563
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• 2015

Identification of energy use patterns in buildings has a great opportunity for energy saving. To find what energy use patterns exist, clustering analysis has been commonly used such as K-means and hierarchical clustering method. In case of high dimensional data such as energy use time-series, data reduction should be considered to avoid the curse of dimensionality. Principle Component Analysis, Autocorrelation Function, Discrete Fourier Transform and Discrete Wavelet Transform have been widely used to map the original data into the lower dimensional spaces. However, there still remains an ongoing issue since the performance of clustering analysis is dependent on data type, purpose and application. Therefore, we need to understand which data reduction techniques are suitable for energy use management. This research aims find the best clustering method using energy use data obtained from Seoul National University campus. The results of this research show that most experiments with data reduction techniques have a better performance. Also, the results obtained helps facility managers optimally control energy systems such as HVAC to reduce energy use in buildings.