• Journal of information and communication convergence engineering
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• v.1 no.4
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• pp.228-232
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• 2003

The previous design work for very large final amplifier pumped by electron beam module was described from the point of view of energy characteristics. In this work, the design problems for phase front distortion, ASE, and gain control in large aperture amplifier are presented in detail.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.651-654
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• 1989

A rate equation model describing the ultrashort pulse formation is presented. The temporal and energy behavior of the distributed feedback dye laser predicted by the model has been compared the earlier papers on DFDL's. The observed good agreement allows application of the theoretical model for picosecond laser.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.335-336
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• 2008

We observe the distortion of the back scattered Stokes pulse and the complementary distortion of the transmitted pulse by the stimulated Brillouin scattering when a Q-switched Nd:YAG laser pulse injected into a single mode optical fiber. We determine the constant required energy for the SBS by comparing their temporal shapes.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.382-387
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• 2014

An all-reflective, simple noncollinear second harmonic (SH) autocorrelator is described for monitoring the shot-to-shot behavior of ultrashort high-power laser pulses. Two mirrors are used for the dispersion-free splitting of a pulse into two halves. One of the mirrors is able to adjust the delay time and angle between two halves of the laser pulse in a nonlinear crystal. We present the possibility of real-time measurement of the pulse duration, peak intensity (or energy), and the pointing jitters of a laser pulse, by analyzing the spatial profile of the SH autocorrelation signal measured by a CCD camera. The measurement of the shot-to-shot variation of those parameters will be important for the detailed characterization of laser accelerated electrons or protons.

• The KIPS Transactions:PartA
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• v.16A no.2
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• pp.69-78
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• 2009

One of the most effective way to improve cache performance is to exploit both temporal and spatial locality given by any program executive characteristics. In this paper we present a high performance and low power cache structure with a bank selection mechanism that enhances exploitation of spatial and temporal locality. The proposed cache system consists of two parts, i.e., a main direct-mapped cache with a small block size and a fully associative buffer with a large block size as a multiple of the small block size. Especially, the main direct-mapped cache is constructed as two banks for low power consumption and stores a small block which is selected from fully associative buffer by the proposed bank selection algorithm. By using the bank selection algorithm and three state bits, We selectively extend the lifetime of those small blocks with high temporal locality by storing them in the main direct-mapped caches. This approach effectively reduces conflict misses and cache pollution at the same time. According to the simulation results, the average miss ratio, compared with the Victim and STAS caches with the same size, is improved by about 23% and 32% for Mibench applications respectively. The average memory access time is reduced by about 14% and 18% compared with the he victim and STAS caches respectively. It is also shown that energy consumption of the proposed cache is around 10% lower than other cache systems that we examine.

• Journal of Soil and Groundwater Environment
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• v.20 no.7
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• pp.90-102
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• 2015

To understand the hyrogeochemical variation of bedrock aquifer during underground space construction, various graphical methods including multiple-component plots and chemical trends were used to estimate the mixing rate between seawater and freshwater and to investigate the evolution of water quality. The water chemistry and mixing rate between fresh and sea waters, which are generally localized in the construction area (MW-7, in land), shows typical characteristics of freshwater that doesn’t affect its validity as seawater intrusion. Especially, the water chemistry of a MW-4 (coastline) was classified as Na-Cl type, Na-HCO₃ type, and Ca-Cl type due to the influence of the seawater intrusion. And hydrogeochemical and isotopic data show that local freshwater is subjected to geochemical processes, such as reverse ion-exchange. Throughout the Chadha’s diagrams, four different case histories with the temporal and spatial variation of groundwaters in the study area were proposed, which is recommended to interpret the hydrogeochemical reactions effectively.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.3
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• pp.31-36
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• 2007

This paper proposes Co-MAC (Coexistence MAC), an energy efficient medium access control protocol designed for large-scale sensor networks. In Co-MAC protocol, an overall network is divided into independent subnets, and each subnet orthogonally operates on time line in a temporal fashion. The basic idea of Co-MAC is to evenly distribute sensor nodes in a certain geographic area based on subnets to minimize overhearing which means the reception of unnecessary data packets from neighboring nodes. In our simulation, it was observed that energy efficiency of Co-MAC outperforms conventional MAC protocols under the given conditions.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.54.1-54.1
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• 2011

The conventional energy-production system by burning fossil fuels releases many pollutants and carbon dioxide($CO_2$) to the environment. Therefore, many countries pay attention to new and renewable energy and invest in the development of these new technologies for the future energy security. One of the most promising of these technologies is a photovoltaic system. In this study, Life Cycle Assessment(LCA) is carried out to analyse the environmental issues(e.g. global warming, abiotic resource depletion) of CdTe photovoltaic system. The spatial and temporal scope of this study was set in Korea during 2004~2005. We assumed that CdTe photovoltaic system was installed in Mokpo where the amount of solar irradiation was higher than other places in Korea. Based on the present data and some assumptions, greenhouse gas emission was 39.2g $CO_2$-eq./kWh. Therefore the electricity produced by CdTe photovoltaic system is more environmentally friendly than the conventional power generation system.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.5
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• pp.554-561
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• 2014

Hybrid wind Diesel stand-alone power systems are considered economically viable and effective to create balance between production and load demand in remote areas where the wind speed is considerable for electric generation, and also, electric energy is not easily available from the grid. In Wind diesel hybrid system, the wind energy system is the main constitute and diesel system forms the back up. This type of hybrid power system saves fuel cost, improves power capacity to meet the increasing demand and maintains the continuity of supply in the system. Problem we face in this system is that even after producing enough power through wind turbine system, considerable portion of this power needs to be dumped due to short term oversupply of power and to maintain the frequency within close tolerances. As a result remaining portion of total energy supplied comes from the diesel generator to overcome the temporal energy shortage. This scenario decreases the overall efficiency of hybrid power system. In this study, efficient Simulink modeling for wind-diesel hybrid system is proposed and some simulations study is carried out to verify the feasibility of the proposed scheme.

• International Journal of High-Rise Buildings
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• v.2 no.2
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• pp.85-91
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• 2013

Tall building has some controversial aspects with low carbon city, but it is still a sensible choice for the metropolitan city. This paper aims to develop holistic urban design strategies to minimize impacts on the environment, increase energy efficiency and improve the quality of living in tall building communities by utilizing tall building characteristics. It puts forward the concept of integrated tall building-low carbon community design from the perspective of urban design, and summarizes five core strategies: Temporal state based on energy use, Complementary energy use state based on functions, Spatial state based on regional environment features, Transportation state based on low-carbon lifestyle and Waste utilization state based on tall building characteristics. It also applies the strategies to a practical project. The results show that the proposed urban design strategies are available approaches to mitigate the side effects of tall building on low carbon city.