• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.221-227
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• 2008

This paper is to show the designing for LED lights driver unit. The main purpose of driver designing is high electrical efficient performance and intelligent control LED driver. Nowadays, a lightning system with some of charactestics such as an environmentally friendly purposes with a possible reduction of electric power consumptions. We constitute a intelligent contron LED control system that helps to save an electric energy, and a communication system to control the system. This LED driver can be used for intelligent light control. This product expects to improve the light control by dimming instead of interlace on/off light control that increases the social cost such as car accidents and etc.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1212-1221
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• 2010

Recently, various types of ships are facing with a challenge to adopt the high efficient and environment-friendly power generating systems. For the reduction of exhaust emissions, improvement of thermal efficiency, and lowering the noise and vibration levels, fuel cells are gaining the much more interests. This paper projects the future marine fuel cell market on the basis of considering the historical world shipbuilding and marine engine market. To do this, the number of total ship is, at first, obtained by forecasting the number of annual new shipbuilding orders and completions. Finally, fuel cell market is forecasted by obtaining the engine capacity for annual world total number of ships and engine orders.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.135-139
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• 2017

In recent years, the optical fiber laser has been widely used in industrial fields due to its excellent economical efficiency and its suitability for industrial applications. This usage has increased even further since the KW class Laser was developed. In this paper, structural analysis and heat transfer analysis of a 500W class optical fiber laser end cap module was performed. The stability of end cap housing with the efficient heat dissipation structure of a 500W-class end cap was evaluated. This research determined the optimal design that should be applied to the design and evaluation of future KW class laser output modules.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.390-392
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• 2006

단일 서스테인 구동회로서 패널을 수평으로 이등 분할하고 직렬 연결하여 구동회로의 전류 스트레스를 저감하는 새로운 단일 에너지 회수 서스테인 구동회로를 제안한다. 기존의 단일 서스테인 구동회로는 +Vs 및 -Vs의 양극성 전원을 사용함에 따라 기존 구동회로에 비해 전류 스트레스는 그대로이면서 스위치 전압 스트레스가 두 배가 되어 회로 손실 및 발열이 높은 단점을 가지고 있다. 이를 개선하기 위해 제안하는 패널 분할 직렬 연결 단일 에너지 회수 서스테인 구동회로는 패널을 수평으로 이등 분할하고 하프 브리지 인버터를 각각 연결하여 구동 회로의 가스 방전 전류 및 패널 캐패시터의 변위 전류를 기존의 절반으로 줄여 스위치들의 전류 스트레스를 저감하게 된다. 또한 에너지 회수 회로는 능동소자로서 단 하나의 스위치와 단하나의 다이오드만을 사용하므로 그 구조가 단순하여 원가를 절감할 수 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.307-310
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• 2001

A parameterized complex-number multiplier (PCMUL) core IP (Intellectual Property), which can be used as an essential arithmetic unit in baseband signal processing of digital communication systems, is described. The bit-width of the multiplier is parameterized in the range of 8-b~24-b and is user-selectable in 2-b step. The PCMUL_GEN, a core generator with GUI, generates VHDL code of a CMUL core for a specified bit-width. The IP is based on redundant binary (RB) arithmetic and a new radix4 Booth encoding/decoding scheme proposed in this paper. It results in a simplified internal structure, as well as high-speed, low-power, and area-efficient implementation. The designed IP was verified using Xilinx FPGA board.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.186-186
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• 2009

The characterization strategy of fracture networks are classified into a deterministic or statistical characterization according to the type of required information. A deterministic characterization is most efficient for a sparsely fractured system, while the statistics are sufficient for densely fractured rock. In this study, the ensemble mean and variability of the effective connectivity is systematically analyzed with various density values for different network structures of a power law size distribution. The results of high resolution Monte Carlo analyses show that statistical characteristics can be a necessary information to determine the transport properties of a fracture system when fracture density is greater than a percolation threshold. When the percolation probability (II) approaches unity with increasing fracture density, the effective connectivity of the network can be safely estimated using statistics only (sufficient condition). It is inferred from conditional simulations that deterministic information for main pathways can reduce the uncertainty in estimation of system properties when the network becomes denser. Overall results imply that most pathways need to be identified when II < 0.5 statistics are sufficient when II $\rightarrow$ 1 and statistics are necessary and the identification of main pathways can significantly reduce the uncertainty in estimation of transport properties when 0.5$\ll$1. It is suggested that the proper estimation of the percolation probability of a fracture network is a prerequisite for an appropriate conceptualization and further characterization.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.38-46
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• 2012

This paper discusses the energy consumption for a mid-size electric vehicle(EV) under various conditions. In order to analyze which driving style is more efficient in terms of the system of the EV, we develop the electric vehicle model and apply several types of speed profiles such as different steady speeds, acceleration/deceleration, and a real world driving cycle including the elevation profile obtained from a GPS device. The results show that the energy consumption of the EV is affected by the operating efficiency of components when driving at low speed, while it depends on required power at wheels when driving at high speed. Also this paper investigates the effect of the elevation of a road and the rate of electrical braking on the energy consumption as well as the fuel economy of a conventional vehicle model under the same conditions.

• Current Photovoltaic Research
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• v.8 no.2
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• pp.60-65
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• 2020

In perovskite solar cells with planar heterojunction configuration, selection of proper charge-transporting layers is very important to achieve stable and efficient device. Here, we developed solution processible Cu doped NiO_x (Cu:NiO_x) thin film as a hole-transporting layer (HTL) in p-i-n structured methylammonium lead trihalide (MAPbI₃) perovskite solar cell. The transmittance and thickness of NiO_x HTL is optimized by control the spin-coating rate and Cu is additionally doped to improve the surface morphology of undoped NiO_x thin film and hole-extraction properties. Consequently, a perovskite solar cell containing Cu:NiO_x HTL with optimal doping ratio of Cu exhibits a power conversion efficiency of 14.6%.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.4
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• pp.83-91
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• 2018

Land reclamation, coastal construction, coastline extension and port construction, all of which involve dredging, are increasingly required to meet the growing economic and societal demands in the coastal zone. During the land reclamation, a portion of landfills are lost from the desired location due to a variety of causes, and therefore prediction of sediment transport is very important for economical and efficient land reclamation management. In this study, laboratory disposal tests were performed using an open channel, and suspended sediment transport was analyzed according to flow velocity and grain size. The relationships between the average and standard deviation of the deposition distance and the flow velocity were almost linear, and the relationships between the average and standard deviation of deposition distance and the grain size were found to have high non-linearity in the form of power law. The deposition distribution of sediments was demonstrated to have log-normal distributions regardless of the flow velocity. Based on the experimental results, modeling of suspended sediment transport was performed using deep neural network, one of deep learning techniques, and the deposition distribution was reproduced through log-normal distribution.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.429-436
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• 2004

Circulating fluidized bed combustion (hereafter CFBC) technology enables an efficient combustion for the materials with low heating values such as high ash coal and sludges. It also has desulfation function by adding limestone directly to combustor. The CFBC has been considered as one of the best processes for low grade coal containing with large contents of ash and sulfur. In this paper, in order to various tests were performed to find the optimum desulfation condition for CFBC using Korean Anthracite. We surveyed possible parameters and conducted desulfation efficiency test in D Thermal Power Plant. In addition, the result of some fundamental theoretical consideration was discussed with CFBC. Optimum limestone size could be considered to be 0.1-0.3mm irrespective of combustion temperature and Ca/S molar ratio variation. Desulfation efficiency increased as the molar ratio increased. Because desulfation process occurs at the surface at higher temperature, inner side of limestone can＇t be utilized. When surface area is not appropriate, some SO$_2$ emit without reaction. Optimum molar ratio should be decided after considering chemical and physical properties of limestone and coal thoroughly such as particle size, pore size and HGI. Commercial CFBC is operated at Ca/S 1.6. Combustor temperature 840-87$0^{\circ}C$ shows good desulfation efficiency.