Earticle

에너지원으로서 천연가스의 비중이 점차적으로 증가하고 있으며 천연가스의 경우 전체 에너지 소비량 대비 15% 이상 을 소비할 만큼 중요한 에너지원의 역할을 가지고 있다. LNG의 경우, 천연가스의 청정성, 편리성 및 경제성이라는 장점 으로 인하여 수요가 늘어나고 있으며 또한 LNG 연료추진선박, LNG 자동차 및 버스의 공급을 위한 소형 LNG 저장설비 의 수요가 급증하고 있다. 본 연구에서는 소형 LNG 저장설비에서 가장 큰 사고로 이를 수 있는 Rollover에 대하여 초저 온 유체 계면에서의 Vapor-Liquid Equilibrium을 이용하여 해석을 수행하였다. 해석된 결과를 이용하여 소형 LNG 저장 설비에서의 누출 피해예측 및 분석을 통한 사고영향평가를 수행하여 추후 건설 예정 중인 설비에 대한 안전성을 검토하 고자 한다.

The share of natural gas as an energy source is gradually increasing, and natural gas has an important role as major energy source role that consumes more than 15% of the total energy consumption. In case of LNG, there is an increasing demand due to the advantage of cleanliness, convenience and economy of natural gas and also, demand for the small LNG storage facilities for fuel supplying LNG fuelled vessels, LNG cars and buses is increasing rapidly. In this study, we analyze the rollover case, which is the biggest LNG leakage accident in small LNG storage facility, by using Vapor- Liquid Equilibrium at the cryogenic fluid interface. Using this calculated results, we evaluate the accident impact by prediction and analysis of leakage damage in small LNG storage facility and examine the safety assessment for facilities to be constructed in the future.

In this paper, we introduce a platform of advanced multiple antenna system based on orthogonal frequency-division multiplexing (OFDM). The advanced multiple antennas have beamforming gain using array antenna. In array antenna systems, received signal has phase delay caused distance of each antennas, therefore it should compensate with optimum weight vector which calculated by Lagrange algorithm. To implement the presented above procedures using Digital Signal Processor (DSP), we should fixedpoint design. The performance of implemented platform is verified through MATLAB® simulations with various signal environments.

일반적으로 많이 사용되는 12 펄스 컨버터에서, 인버터 1차측(전원측)에 고조파 저감용 리액터를 연결하 여 고조파의 영향을 어느 정도 줄일 수 있다. 고조파가 발생하면 일차적으로 해당 전원측 변압기의 발열이나 이상 소음 등이 생길 수 있고 인버터와 변압기 사이의 차단기(보통 공기차단기, ACB: Air Circuit Breaker)가 소음이 나 발열, 또는 간선에도 소음과 발열이 생길 수 있다. 고조파가 생기면 전선과 그 회로 내부에 전자레인지를 사용 하는 듯 소음과 발열을 동반하는 수가 대부분이다. 고조파 발생은 대부분의 반도체 스위칭 회로가 있으면 어떤 것 이든 발생된다. 인버터, UPS(Uninterubtable Power Supply System, 무정전전원장치), 고주파전로(용광로) 등 고 조파로 인하여 소음과 발열로 인한 어려움이 많다. 그러므로 컨버터에서는 이러한 고조파를 줄이는 방향의 연구가 절실한 상황이다. 이에 본 연구에서는 기존 12 펄스 컨버터에 적용 가능한 보조컨버터를 활용한 새로 제안된 컨버 터에서의 고조파를 분석하여 고조파 절감의 효과성을 검증하고 확인하고자 한다. Matlab을 이용하여 FFT 고조파 분석 결과 새로 제안된 컨버터에서 고조파 성분이 전반적으로 작음을 확인할 수 있었다.

In the commonly used 12-pulse converter, a harmonic mitigation reactor can be connected to the inverter primary side (power side) to reduce the harmonic impact to a certain extent. When a harmonic wave occurs, it is possible to primarily generate heat or abnormal noise from the power side transformer, and the circuit breaker between the inverter and the transformer may also produce noise, heat, or even noise and heat in the main line. When a harmonic wave occurs, it is most often accompanied by noise and heat, as if a microwave oven were used inside the wires and circuits. Harmonic generation occurs with anything with most semiconductor switching circuits. Due to the harmonics such as inverters, UPS, and high-frequency furnaces, there are many difficulties caused by noise and heat. Therefore, in converter, research in the direction of reducing these harmonics is urgent. Accordingly, in this study, we will analyze the harmonics in the newly proposed converter utilizing the auxiliary converter applicable to the 12 pulse converter to verify and confirm the effectiveness of harmonic savings. FFT harmonic analysis using Matlab confirmed that the harmonic component was overall small in the newly proposed converter.

Photovoltaic (PV) are generally modeled using mathematical equations that describe the PV system behavior. Most of the modeling approach is very simple in terms of that PV module temperature is calculated from nominal constant cell temperature such as ambient temperature and incoming solar irradiance. In this paper, we newly present MATLAB model particularly embedding the effect of wind speed to describe more accurate cell temperature. For analyses and validate purpose of the proposed model, solar power is obtained and compared with and without wind speed from the 50Wp PV module provided by vendor datasheet. In the simulation result, we found that power output of the module is increased to 0.37% in terms of cell temperature a degreed down when we consider the wind speed in the model. This result is well corresponded with the well-known fact that normal PV is 0.4% power changed by cell temperature a degree difference. Therefore it shows that our modeling method with wind speed is more appropriate than the methods without the wind speed effect.

We performed the quantitative analysis using MATLAB for slice thickness, spatial resolution, and low contrast resolution with the 50 received images which have suitable judgement by scanning AAPM phantom using GE, PHILIPS, SIEMENS, and TOSHIBA. Slice thickness and spatial resolution were measured by using full width at half maximum(below FWHM). Spatial resolution was confirmed that FWHM interval more than 1.0 mm size. Low contrast resolution was measured that how close by using Roundness Index(below RI) until 6.4 mm size. The spatial resolution 9 images and low contrast resolution 10 images which have disapproved judgement were also had the quantitative analysis. The statistic analysis was judged to have statistically significant differences when p-value is less than 0.05 through SPSS statistics 19.0 and T-test (paired t-test). For slice thickness 5 mm, the average qualitative evaluation group shows 4.98 mm and quantitative evaluation group shows 5.02. For slice thickness 10 mm, the average qualitative evaluation group shows 9.98 mm and quantitative evaluation group shows 9.86. No significant differences (p=0.07, p=0.06) with 5 mm and 10 mm. It confirmed the interval for all FWHM until 1.75, 1.50, 1.25, 1.00 mm as approved images on spatial resolution ,and the average distance was 0.102 mm and the minimum distance 0.054 mm. For disapproved images, all interval was not showed under 1.00 mm. For low contrast resolution, spproved image’s RI value shows average 0.81 and minimum 0.77. The disapproved image’s RI average shows 0.70. Statiscally significant differences were presented (all p<0.05) following hole size.

Stochastic Frontier Analysis (SFA) is a modified econometric approach to the estimation of productive efficiency. Since MATLAB has a syntax similar with the matrix algebra, one can easily create and understand MATLAB code for SFA. A simple MATLAB module called "SFAALS" and its illustrative implementation with an input-output data set of 90 American university research libraries are provided.

MATLAB-based simulation technology can support the analysis and design of relay protection sport systems. A simulation model is built for the study of sport system relay protection. As an example, the sport system fault simulation, zero-sequence current protection simulation and transformer differential protection simulation are presented herein. The case studies show that the simulation of sport system relay protection is effective and feasible.

The saturation characteristic of the core varies with operation of magnetically saturation controlled reactor’s (MSCR). Consequently its harmonic characteristic is needed to take in consideration. The arithmetic representation of MSCR is derived in accordance with the structural characteristic and operational rules. The characteristic analysis investigates the function of voltage as well as current over all magnetic field parameters of harmonics. After that, it concludes that the working current of MSCR’s is an odd harmonic function, including primary and odd harmonic components; controlling current and voltage are even harmonic functions, restraining DC and even harmonic components; Again magnetic point of view, the magnetic components are also surrounding the DC and its own fundamental part too. Finally, a simulation model for MSCR is fabricated with MATLAB/Simulink. This paper demonstrates that the analysis is very precise. So, this paper can be a reference to provide further instruction for analysis and proposition of new harmonic suppression methods of MSCR.

A two-bar plane truss is builtin MATLAB based on mathematical model. Then the authors use genetic algorithm toolbox to solve this problem. The parametric truss model is set up in the finite element analysis software ANSYS. It is analyzed by first-order algorithm. The comparison of two kinds results show the pure genetic algorithm doesn’t always have an advantage over other algorithms. In the end, a joint optimization method is put forward on the basis of genetic algorithm. It combines genetic algorithm based on MATLAB toolbox and numerical algorithm based on quasi-Newton method. This method is illustrated by the numerical example of the two-bar plane truss. The results show this joint optimization method can get the global optimal solution of this problem every time.

Beam forming is a technique in signal processing that has found widespread applications in fields such as radar, wireless communication, bio-medical ultrasounds and so on. Beam forming consist of an array of antennas whose radiation pattern are adjusted to a particular direction. This paper aims in implementing a two stage design for acoustic beam forming using MATLAB and Verilog HDL. First stage is a delay and sum beam former used to obtain beams from a particular direction while the second stage is an LMS model based on Least Mean Square (LMS) algorithm. This stage improves the efficiency of delay sum by removing the unwanted signals. Different hardware parameters like logic utilization, memory usage, CPU time and delay of this design are analyzed to determine its characteristics as compared to delay sum and LMS. This study found that the two stage model gives better beam forming and noise removal than when the stages are implemented independently.

By using MATLAB, a kind of software decoder is designed which has filter and fault correction function and is used in aviation radio communication. Through Morse code text, using dits and dashes to uniquely represent characters such as alphabets、numbers and punctuations (41), those characters are coded through algorithm. A new decoding algorithm is designed which is composed of filtration, binary, difference and zero removal operation. This decoding method is robust and interference immunity, it also has such functions as filtering and fault correction. It can filter the random noise and Gaussian noise so as to reduce the error rate of aviation radio communication and thereby increase the quality of aviation radio communication. This method is checked though an example to decode the word “Hello”.

This paper deals about image processing of log internal decays using MATLAB technique. Specifically, image enhancement, image edge detection and decay area extraction and calculation on the two-dimension image of log inner decays that were derived by using the non-destructive inspection technique of stress wave were conducted. The results showed that the testing image of stress wave can visually reflect wood inner decay, and the image resolution can also be improved by using the functions of image enhancement and edge detection in MATLAB software. The detection precision of stress wave is closely associated with the ratio of log internal decay area to tested wood cross-sectional area. When the ratio between wood actual inner decay area and tested log cross-sectional area increased from 4.77% to 45.52%, the relative error between tested decay area and actual decay area reduced from 16.42% to 7.39%. The study has provided an advanced method to judge the degree of wood inner decay for most forest practioners and researchers. Through the image processing and computing on the images derived by stress wave testing, the accuracy of logs internal decay discrimination can be significantly improved.

Today, the primary constrain in wireless communication system is limited bandwidth and power. Wireless systems involved in transmission of speech envisage that efficient and effective methods be developed (bandwidth usage & power) to transmit and receive the same while maintaining quality-of-speech, especially at the receiving end. Speech coding is a technique, since the era of digitization (digital) and computerization (computational and processing horsepower - DSP) that has been a material- of- research for quite sometime amongst the scientific and academic community. Amongst all elements of the communication system (transmitter, channel and receiver), transmission channel (carrier of information/data, also called the medium) is the most critical and plays a key role in the transmission and reception of information/data. This paper proposes some modifications in the Long Term Gain and selection of Grid position sections of 13kbps GSM Full Rate coder so that it can be mapped to bitrates of GSM Enhanced Full Rate at12.2kbps. Here, Objective analysis is carried out on a proposed system using MATLAB to evaluate its performance and the results obtained are then compared to the results of GSM Full Rate coder. Proposed coder, at bitrates of 12.2 kbps, provides moderately low computational complexity [1] as its implementation is with reference to GSM full rate coder rather than using Algebraic Code Excited Linear Prediction (ACELP) algorithm in case of standard GSM EFR coder but it offers small degradation in speech quality compared to standard GSM EFR coder. In comparison with standard GSM Full Rate coder, here the proposed coder offers other benefit of saving of 0.8kbps which can be useful for better error protection during channel coding while also provides satisfactory results for the parameters of Objective analysis.

본 연구에서는 지문 인식과정 중 이미지 개선 기능을 포함한 특징점 추출단계 전체를 자동화 하는 프로그램 개발의 전 단계로서 새로운 지문 특징점 추출 알고리즘을 제안하였다. 입력된 지문에서 특징점을 추출한 후 지문 데이터와 대조하여 개인 식별을 가능하게 하는 지문인식시스템에서 지문의 특징점을 가능한 정확하게 추출하는 작업이 매우 중요하다. 본 알고리즘은 이미지 개선, 특징점 추출 그리고 지문 이미지상의 표시 등의 3단계로 구성하여 코딩하였다. 이미지의 균질화를 위하여 이진화된 지문 이미지에 침식과정을 추가하여 세선화 단계에서 나타나는 불필요한 선이 생성되지 않도록 하 였다. 융선의 가장자리에 위치한 픽셀을 제거하여 한 픽셀 폭으로 표현된 세선화 이미지에서 분기점과 종단점을 각각 추출하였다. 이같이 고안된 알고리즘을 적용한 결과, 지문 인식에 필요한 대부분의 특징 점이 양호하게 추출됨을 알 수 있었다. 경찰에서 현재 사용하는 AFIS는 사용에 제한이 있어 직접 비교 가 불가하였으나 미국 개인생체식 별 시스템 회사의 VeriFinger와 비교하였을 경우에 더 많은 특징점을 추출하는 것으로 확인되었다.

In this study, to suggest the new fingerprint minutiae extraction algorithm (FMEA) of the preliminary of automatic process with image enhancing step using MATLAB. It is very important extraction of the minutiae exactly on the fingerprint recognition system that enables the personal identification by comparing the extracted features between the extracted input fingerprint minutiae and fingerprint data. The FMEA was coded in three main processes composed of image enhancement, minutiae extraction and overlaying of the result image. Add the erosion function after binarization for the normalization of the image to prevent unnecessary branches on the thinning process. And extracted the bifurcation and the ridge ending from the thinned image. The result derived by applying the algorithm to the fingerprint image, extracted minutiae was enough for fingerprint recognition. The direct comparison with AFIS was limited, so compared with ‘VeriFinger’ developed by ‘Neorotechnology’ (USA). As a result, a newly developed algorithm was extracted more number of minutiae.

With the development of modern high precision processing technology, precise microminiature electromechanical products have been widely used. Most of the precise microminiature electromechanical products are assembled from microminiature parts.Due to dimensions of the microminiature parts involved are in micro-and nanoscale, which cannot be reached by ordinary cameras, it cannot effectively capture the image of those parts to be assembled, thus affects the assembly. A microscopic vision measurement system of stereo microscope that combined with high resolution CCD camera was developed based on micro machine vision, which uses the MATLAB software to deal with the collected images of microminiature parts such as image smoothing, image sharpening, image segmentation and edge extraction, etc. to study the structures, identification, location and assembly process of microminiature parts. The results show that the visual system we used has accomplished the automatic measurement and precise assembly of miniature parts excellently.

A mobile ad hoc network is a special kind of wireless mobile communication network, featuring equal status of all terminals, ad hoc, no need for prior arrangement of any network facilities or central control nodes, dynamically changing topology and bandwidth and energy restriction. In recent years, research on mobile ad hoc networks, especially research on media access control and routing protocols have research focus. In this paper, the well-known on-demand routing protocol AODV is analyzed and is improved as AODV-CLMP, with a simulation platform used to evaluate its performance, with some meaningful conclusions drawn. In this paper, the origin, characteristics, application and current development of mobile ad hoc networks are introduced briefly, followed by research on two kinds of well-known on-demand routing protocols for mobile ad hoc networks, i.e. AODV and AODV-CLMP. Finally, commonly used network simulation software is compared to conduct evaluation and analysis of the performance of the AODV and AODV-CLMP protocols. Through the analysis of the simulation result of such evaluation indicators as average end-to-end delay, packet delivery fraction and throughput, the following conclusions are drawn: the average delay, packet deliveryfractionand throughput of AODV-CLMP protocol are superior to those ofAODV protocol, indicating thatAODV-CLMP protocol can transmit information more rapidly and steadily.