• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.2
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• pp.163-170
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• 2011

An optimal layout condition of the offshore wind turbines is studied by using the response surface analysis which is a kind of the design of experiments. Based on the assumption that total 36 turbines would be installed in the offshore wind farm, the number and distance of the rows and columns are used as the design variables and the efficiency decrease of power generation due to the wake decay by the interactions of turbines and the installation cost of the internal electric grid are considered as the objective functions of the response surface analysis for the layout design of turbines. Useful design information can be derived by analyzing the relationship between the design variables and target functions. It is found that the row number and the distance between rows should be minimized, and the optimal distance between columns should be estimated and adopted to the layout design within the specified design range in order to ensure the economics for the offshore wind farm.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.90-94
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• 2015

We stuidied liauid crystal alignment treatment using solution process for making thin oxide layer in liquid crystal display. It is the one of very effient and popular process in making thin oxide layer in electronical industrial fields. Particularly, this process has highly potential value in liquid crystal display industrial fields because it cause automatically induced alignment process without tranditional alignment process in liquid crystal alignment process. We made several different kinds of mol density solutions using strontium oxide solution. And those solutions were treated for solidification layers using annealing process for 2 hours. And we stuided pretilt angle properties of these alignment layers of strontium oxide for clarifying the relationship of liquid crystal molecules and thin strontium oxide layer. And we also tested the existence of strontium oxide thin layer on substrate using XPS measurement. We expected the hig gain of electro-optical properties in liquid crystal display using strontium oxide thin layer because it has high K property material than the other metal-based oxide layers. In this results, we measured 1.447 to 1.613 thresholds volts as 0.1 mol to 0.4 mol density in 0.1 mol density steps. This is significant better characteristics than conventional liquid crystal display as higher than 1.85 thresholds volts. And it make possible to making next-generation liquid crystal display which present low-power consumption and wide gray scale in liquid crystal display.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2999-3004
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• 2010

In comparison with some other light sources, LED has merits such as long lifetime, pollution free, and high energy efficiency. Lately, due to development of LED with high brightness and capacity, LED, which has been applied in display system only, has applied in the field of lighting system. As power LED for lighting system can be burned out by heat problem, the driving current of power LED has to be controlled below the designed value. In this paper, power LED photovoltaic lighting system, which has the current limitting function, has been described. After photovoltaic power is generated from PV panel. it is charged into a battery. And then, after the charged power is converted to DC24[V] through a boost DC-DC converter, it is supplied to power LED at night. It has been validated by designing and testing of 72[W] power LED lighting system, which includes a PV charger, a boost DC-DC converter and a current limiter for driving power LED.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.4
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• pp.567-573
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• 2002

In this paper, we propose a new symbol time synchronization scheme suitable for the OFDM system with an interpolator. The proposed scheme performs the following three steps. In the first step, the coarse symbol time synchronization is achieved by continuously measuring the average power of the received envelope signal. Based on this average power, the detection possibility for the symbol time synchronization is determined. It the signal is sufficient for synchronization, we next perform a relatively accurate symbol time synchronization by measuring the correlation between a short training signal and the received envelope signal. Finally, an additional frequency synchronization is performed with a long training signal to correct symbol synchronization errors caused by the phase rotation. From the simulation results, one can see that the proposed synchronization scheme provides a good synchronization performance over frequency selective channels.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.3
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• pp.485-490
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• 2012

In this paper, driver circuit of LED lights for ships is designed and implemented to replace conventional lights with filament which have short life time due to vibration of ships. The driver of LED module is switching circuit without transformer to reduce volume and cost. As switch circuit controls input 220 VAC with PWM, LED module is reliably driven. Power factor is improved by using valley-fill PFC compensation circuit which is handled to pulse current of switching circuit. Serial-parallel LED circuit is applied to reduce change period of lights of long-term navigation ships. Array of serial-parallel can operate even if some of LEDs is damaged. It is suitable for ships that power consumption and power factor of lights including developed drive circuit have 39Watt and 0.925 respectively.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.253-260
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• 2004

This paper proposes a novel algorithm for hybrid lossless audio coding, which employs an integer wavelet transform and a linear prediction model. The proposed algorithm divides the input signal into flames of a proper length, decorrelates the framed data using the integer wavelet transform and linear prediction and finally entropy-codes the frame data. In particular, the adaptive Golomb-Rice coding method used for the entropy coding selects an optimal option which gives the best compression efficiency. Since the proposed algorithm uses integer operations, it significantly improves the computation speed in comparison with an algorithm using real or floating-point operations. When the coding algorithm is implemented in hardware, the system complexity as well as the power consumption is remarkably reduced. Finally, because each frame is independently coded and is byte-aligned with respect to the frame header, it is convenient to move, search, and edit the coded, compressed data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.138-141
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• 2015

K-water operates many Water Treatment Plants(WTP) to supply clean water to people. There are automation process control equipments collecting data at each step in WTP. The data collected is big enough to 370,000Tag/min from the K-water Water Treatment Plants. In the past, this big data was not important, we focused on the operating water purification process using the data. Currently, we increased the importance of attention to take advantage of Big Data. The research about the accident reduction and efficiency improvement in WTP are ongoing by data collection and analysis. In this paper, we analyzed the flow rate, power and pressure obtained in the accident case in WTP. We researched the methods for accident prediction and reduction.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.27-31
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• 2006

Millimeter over Fiber (MMoF) technique modulates millimeter wave signal optically to transmit it through an optical fiber for long distances with small loss. MMoF system usually uses optical single sideband (OSSB) modulation scheme to reduce fiber chromatic dispersion and obtain high bandwidth efficiency. The optical link of MMoF system using OSSB is treated as a nonlinear amplifier, and the AM/AM characteristic function of the amplifier is a Bessel function of the first kind of order 1. In this paper, we investigate the performance of OFDM MMoF system considering nonlinearity of OSSB modulation. We estimate a power of the nonlinear distortion noise to analyze the theoretical bit error rate(BER), and perform a simulation to verify the theoretical BER.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.102-108
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• 2011

The existing vessels lighting control system has several problems, which are complexity of construction and high cost of establishment and maintenance. In this paper, We designed low cost and high performance lighting control system at digital vessel environment. We proposed a system which recognize the user's emotions after obtaining the biological informations about user's bio information(pulse sensor, blood pressure sensor, blood sugar sensor etc) through wireless sensors controls the LED Lights. This system classified emotions using backpropagation algorithm. We chose 3,000 data sets to train the backpropagation algorithm. As a result, obtained about 88.7% accuracy. And the classified emotions find the most appropriate point in the method of controlling the waves or frequencies to the red, green, blue LED Lamp comparing with the 20-color-emotion models in the HP's 'The meaning of color' and control the brightness or contrast of the LED Lamp. In this method, the system saved about 20% of the electricity consumed.

• Journal of IKEEE
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• v.19 no.1
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• pp.45-51
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• 2015

Recently, as WPAN (Wireless Personal Area Network) becomes the necessary feature in IoT (Internet of Things) devices, the importance of data security also hugely increases. In this paper, we present the low-complexity 128-bit AES-$CCM^*$ hardware IP for IEEE 802.15.4 standard. For low-cost and low-power implementation which is essentially required in IoT devices, we propose two optimization methods. First, the folded AES(Advanced Encryption Standard) processing core with 8-bit datapath is presented where composite field arithmetic is adopted for reduced hardware complexity. In addition, to support $CCM^*$ mode defined in IEEE 802.15.4, we propose the mode-toggling architecture which requires less hardware resources and processing time. With the proposed methods, the gate count of the proposed AES-$CCM^*$ IP can be lowered up to 57% compared to the conventional architecture.