• Journal of applied mathematics & informatics
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• v.17 no.1_2_3
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• pp.73-91
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• 2005

The application of Green's function in calculation of flow characteristics around submerged and floating bodies due to a regular wave is presented. It is assumed that the fluid is homogeneous, inviscid and incompressible, the flow is irrotational and all body motions are small. Two methods based on the boundary integral equation method (BIEM) are applied to solve associated problems. The first is a low order panel method with triangular flat patches and uniform distribution of velocity potential on each panel. The second method is a high order panel method in which the kernels of the integral equations are modified to make it nonsingular and amenable to solution by the Gaussian quadrature formula. The calculations are performed on a submerged sphere and some floating spheroids of different aspect ratios. The excellent level of agreement with the analytical solutions shows that the second method is more accurate and reliable.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.120-126
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• 2006

A gate driver with Boot-strap chain is proposed to drive Multi-level PDP sustain switches. The proposed gate driver uses only one boot-strap capacitor and one diode per each MOSFETs switch without floating power supply. By adoption of this gate driver circuits, the size, weight and the cost of the driver board can be reduced.

• Ocean Systems Engineering
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• v.6 no.2
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• pp.203-216
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• 2016

Over recent years the offshore wind turbines are becoming more feasible solution to the energy problem, which is crucial for Egypt. In this article a three floating support structure, tension leg platform types (TLP), for 5-MW wind turbine have been considered. The dynamic behavior of a triangular, square, and pentagon TLP configurations under multi-directional regular and random waves have been investigated. The environmental loads have been considered according to the Egyptian Metrological Authority records in northern Red sea zone. The dynamic analysis were carried out using ANSYS-AQWA a finite element analysis software, FAST a wind turbine dynamic software, and MATLAB software. Investigation results give a better understanding of dynamical behavior and stability of the floating wind turbines. Results include time history, Power Spectrum densities (PSD's), and plan stability for all configurations.

• Korean Journal of Cognitive Science
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• v.2 no.1
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• pp.73-86
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• 1990

This study aims to give a syntactic and semantic analysis of the phe- nomenon of Quantifier Floating in the framework of Generalixed Cate- gorial Grammar. Floated quantifiers like neys-i as in Hakayngtul-i neys-i swul-ul masyessta are syntactically analyxed as VP modifiers(VP/VP), and semantically as involving nominalixed properties. Related forms like neys(NP/NP) and neys-ul(TV-TV) are also given rigorous syntactic and semantic analysis. A successful anaysis sheds light on the possiblity of using Categorial Grammar, which is subject to adjacency principle, for the (computer) processing od Korean.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.151-156
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• 2000

Yb/YAG single crystals were grown from the melt composition of Y/sub 1-x/Yb/sub x/)₃Al/sub 5/O/sub 12/ where x equal to 5, 10, 15, 20, 25, 33, 50, 75 and 100 at % by floating zone method. Optimum growth parameters to get high quality single crystals were 3.5 mm/h of growth rate and 20 rpm of rotation rate under the N₂ atmosphere. After the growth, color of crystals was appeared with pale blue due to the lack of oxygen, but it was disappeared after annealing at 1450℃ for 2 hr. Absorption coefficients were linearly increased depending on the concentration of Yb/sup 3+/ ions. Broad emission band was measured in the range of 1020 to 1050 nm with the peak intensity at 1031 nm and 1051 nm because of ²F/sub 5/2/(1)→²F/sub 7/2/(3) and ²F/sub 5/2/(1)→²F/sub 7/2/(4) transition respectively. When Yb/sup 3+/ ions were substituted with high rates, there were tendency to decrease the measured fluorescent lifetime for Yb ions depending on the concentration of Yb/sup 3+/ ions.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.440-441
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• 2002

지구온난화를 유발하는 온실가스의 대표적인 성분으로는 이산화탄소, 메탄, 아산화질소, CFC 등을 들 수 있으며, 주요 온실기체들에 대한 대기 중 농도가 과거보다 현저하게 증가되었음이 확인되고 있다. $N_2$O은 대기 중의 농도는 낮으나 상대적으로 지구온난화에 기여하는 정도가 $CO_2$에 비해 질량기준으로 310배가 높고, 생체 발생량이 크기 때문에 지구규모수지에 있어서 신중하게 고려되어야 한다. 온실기체의 국가배출자료는 기후변화협약과 관련된 국제협상 및 국내 저감대책 수립에 없어서는 안될 중요한 기초자료이다. (중략)

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.7
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• pp.358-363
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• 2004

A new 600 V dual gate transistor employing thyristor action, which incorporates floating PN junction and trench gate IGBT, is proposed to improve the forward current-voltage characteristics and the short circuit ruggedness. Our two-dimensional numerical simulation shows that the proposed device exhibits low forward voltage drop and eliminates the snapback phenomena compared with conventional trench gate IGBT and EST The proposed device achieves high current saturation characteristics by separating floating N+ emitter and cathode. The proposed device achieves low saturation current value compared with conventional devices, and the short-circuit ruggedness is improved. The proposed device may be suitable for the use of high voltage switching applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.1
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• pp.188-198
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• 2005

The Goldschmidt iterative algorithm for finding a floating point square root calculated it by performing a fixed number of multiplications. In this paper, a variable latency Goldschmidt's square root algorithm is proposed, that performs multiplications a variable number of times until the error becomes smaller than a given value. To find the square root of a floating point number F, the algorithm repeats the following operations: $R_i=\frac{3-e_r-X_i}{2},\;X_{i+1}=X_i{\times}R^2_i,\;Y_{i+1}=Y_i{\times}R_i,\;i{\in}\{{0,1,2,{\ldots},n-1} }}'$with the initial value is $'\;X_0=Y_0=T^2{\times}F,\;T=\frac{1}{\sqrt {F}}+e_t\;'$. The bits to the right of p fractional bits in intermediate multiplication results are truncated, and this truncation error is less than $'e_r=2^{-p}'$. The value of p is 28 for the single precision floating point, and 58 for the doubel precision floating point. Let $'X_i=1{\pm}e_i'$, there is $'\;X_{i+1}=1-e_{i+1},\;where\;'\;e_{i+1}<\frac{3e^2_i}{4}{\mp}\frac{e^3_i}{4}+4e_{r}'$. If '|X_i-1|<2^{\frac{-p+2}{2}}\;'$ is true, $'\;e_{i+1}<8e_r\;'$ is less than the smallest number which is representable by floating point number. So, $\sqrt{F}$ is approximate to $'\;\frac{Y_{i+1}}{T}\;'$. Since the number of multiplications performed by the proposed algorithm is dependent on the input values, the average number of multiplications per an operation is derived from many reciprocal square root tables ($T=\frac{1}{\sqrt{F}}+e_i$) with varying sizes. The superiority of this algorithm is proved by comparing this average number with the fixed number of multiplications of the conventional algorithm. Since the proposed algorithm only performs the multiplications until the error gets smaller than a given value, it can be used to improve the performance of a square root unit. Also, it can be used to construct optimized approximate reciprocal square root tables. The results of this paper can be applied to many areas that utilize floating point numbers, such as digital signal processing, computer graphics, multimedia, scientific computing, etc.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.413-420
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• 2005

The Newton-Raphson iterative algorithm for finding a floating point reciprocal square mot calculates it by performing a fixed number of multiplications. In this paper, a variable latency Newton-Raphson's reciprocal square root algorithm is proposed that performs multiplications a variable number of times until the error becomes smaller than a given value. To find the rediprocal square root of a floating point number F, the algorithm repeats the following operations: '$X_{i+1}=\frac{{X_i}(3-e_r-{FX_i}^2)}{2}$, $i\in{0,1,2,{\ldots}n-1}$' with the initial value is '$X_0=\frac{1}{\sqrt{F}}{\pm}e_0$'. The bits to the right of p fractional bits in intermediate multiplication results are truncated and this truncation error is less than '$e_r=2^{-p}$'. The value of p is 28 for the single precision floating point, and 58 for the double precision floating point. Let '$X_i=\frac{1}{\sqrt{F}}{\pm}e_i$, there is '$X_{i+1}=\frac{1}{\sqrt{F}}-e_{i+1}$, where '$e_{i+1}{<}\frac{3{\sqrt{F}}{{e_i}^2}}{2}{\mp}\frac{{Fe_i}^3}{2}+2e_r$'. If '$|\frac{\sqrt{3-e_r-{FX_i}^2}}{2}-1|<2^{\frac{\sqrt{-p}{2}}}$' is true, '$e_{i+1}<8e_r$' is less than the smallest number which is representable by floating point number. So, $X_{i+1}$ is approximate to '$\frac{1}{\sqrt{F}}$. Since the number of multiplications performed by the proposed algorithm is dependent on the input values, the average number of multiplications Per an operation is derived from many reciprocal square root tables ($X_0=\frac{1}{\sqrt{F}}{\pm}e_0$) with varying sizes. The superiority of this algorithm is proved by comparing this average number with the fixed number of multiplications of the conventional algorithm. Since the proposed algorithm only performs the multiplications until the error gets smaller than a given value, it can be used to improve the performance of a reciprocal square root unit. Also, it can be used to construct optimized approximate reciprocal square root tables. The results of this paper can be applied to many areas that utilize floating point numbers, such as digital signal processing, computer graphics, multimedia, scientific computing, etc.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.95-102
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• 2005

The Newton-Raphson iterative algorithm for finding a floating point reciprocal which is widely used for a floating point division, calculates the reciprocal by performing a fixed number of multiplications. In this paper, a variable latency Newton-Raphson's reciprocal algorithm is proposed that performs multiplications a variable number of times until the error becomes smaller than a given value. To find the reciprocal of a floating point number F, the algorithm repeats the following operations: '$'X_{i+1}=X=X_i*(2-e_r-F*X_i),\;i\in\{0,\;1,\;2,...n-1\}'$ with the initial value $'X_0=\frac{1}{F}{\pm}e_0'$. The bits to the right of p fractional bits in intermediate multiplication results are truncated, and this truncation error is less than $'e_r=2^{-p}'$. The value of p is 27 for the single precision floating point, and 57 for the double precision floating point. Let $'X_i=\frac{1}{F}+e_i{'}$, these is $'X_{i+1}=\frac{1}{F}-e_{i+1},\;where\;{'}e_{i+1}, is less than the smallest number which is representable by floating point number. So, $X_{i+1}$ is approximate to $'\frac{1}{F}{'}$. Since the number of multiplications performed by the proposed algorithm is dependent on the input values, the average number of multiplications per an operation is derived from many reciprocal tables $(X_0=\frac{1}{F}{\pm}e_0)$ with varying sizes. The superiority of this algorithm is proved by comparing this average number with the fixed number of multiplications of the conventional algorithm. Since the proposed algorithm only performs the multiplications until the error gets smaller than a given value, it can be used to improve the performance of a reciprocal unit. Also, it can be used to construct optimized approximate reciprocal tables. The results of this paper can be applied to many areas that utilize floating point numbers, such as digital signal processing, computer graphics, multimedia scientific computing, etc.