• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.1
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• pp.145-149
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• 2015

A reconfigurable lighting engine for widely used lighting models is proposed for low-power GPU shaders. Conventionally, lighting operations that involve many complex arithmetic operations were calculated by the shader programs on the GPU, which led to a significant energy overhead. In this letter, we propose a lighting engine to improve the energy-efficiency by supporting the widely used advanced lighting models in hardware. It supports the Blinn-Phong, Oren-Nayar, and Cook-Torrance models, by exploiting the logarithmic arithmetic and optimizing the trigonometric function evaluations for the energy-efficiency. Experimental results demonstrate 12.7%, 42.5%, and 35.5% reductions in terms of power-delay product from the shader program implementations for each lighting model. Moreover, our work shows 10.1% higher energy-efficiency for the Blinn-Phong model compared to the prior art.

• Wind and Structures
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• v.19 no.5
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• pp.505-522
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• 2014

While effects of the atmospheric boundary layer flow on engineering infrastructure are more or less known, some local transient winds create difficulties for structures, traffic and human activities. Hence, further research is required to fully elucidate flow characteristics of some of those very unique local winds. In this study, important characteristics of observed vertical velocity profiles along the main wind direction for the gusty Bora wind blowing along the eastern Adriatic coast are presented. Commonly used empirical power-law and the logarithmic-law profiles are compared against unique 3-level high-frequency Bora measurements. The experimental data agree well with the power-law and logarithmic-law approximations. An interesting feature observed is a decrease in the power-law exponent and aerodynamic surface roughness length, and an increase in friction velocity with increasing Bora wind velocity. This indicates an urban-like velocity profile for smaller wind velocities and rural-like velocity profile for larger wind velocities, which is due to a stronger increase in absolute velocity at each of the heights observed as compared to the respective velocity gradient (difference in average velocity among two different heights). The trends observed are similar during both the day and night. The thermal stratification is near neutral due to a strong mechanical mixing. The differences in aerodynamic surface roughness length are negligible for different time averaging periods when using the median. For the friction velocity, the arithmetic mean proved to be independent of the time record length, while for the power-law exponent both the arithmetic mean and the median are not influenced by the time averaging period. Another issue is a large difference in aerodynamic surface roughness length when calculating using the arithmetic mean and the median. This indicates that the more robust median is a more suitable parameter to determine the aerodynamic surface roughness length than the arithmetic mean value. Variations in velocity profiles at the same site during different wind periods are interesting because, in the engineering community, it has been commonly accepted that the aerodynamic characteristics at a particular site remain the same during various wind regimes.

• Journal for History of Mathematics
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• v.27 no.6
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• pp.409-419
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• 2014

In school mathematics, the logarithmic function is defined as the inverse function of an exponential function. And the natural logarithm is defined by the integral of the fractional function 1/x. But historically, Napier had already used the concept of logarithm in 1614 before the use of exponential function or integral. The calculation of the logarithm was a hard work. So mathematicians with arithmetic ability made the tables of values of logarithms and people used the tables for the estimation of data. In this paper, we first take a look at the mathematicians and mathematical principles related to the appearance and the developments of the logarithmic tables. And then we deal with the confusions between mathematicians, raised by the estimation data which were known as proportional parts or mean differences in common logarithmic tables.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1891-1898
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• 2013

To efficiently execute 3D graphic APIs, such as OpenGL and Direct3D, special purpose arithmetic unit(SFU) which supports floating-point sine, cosine, reciprocal, inverse square root, base-two exponential, and logarithmic operations is designed. The SFU uses second order minimax approximation method and lookup table method to satisfy both error less than 2 ulp(unit in the last place) and high speed operation. The designed circuit has about 2.3-ns delay time under 65nm CMOS standard cell library and consists of about 23,300 gates. Due to its maximum performance of 400 MFLOPS and high accuracy, it can be efficiently applicable to mobile 3D graphics application.

• Communications of the Korean Mathematical Society
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• v.34 no.1
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• pp.239-251
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• 2019

In this paper we introduce a new formulation of symmetric homogeneous bivariate means that depends on the variation of a given continuous strictly increasing function on (0, ${\infty}$). It turns out that this class of means includes a lot of known bivariate means among them the arithmetic mean, the harmonic mean, the geometric mean, the logarithmic mean as well as the first and second Seiffert means. Using this new formulation we introduce a lot of new bivariate means and derive some mean-inequalities.

• Bulletin of the Korean Mathematical Society
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• v.56 no.2
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• pp.521-533
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• 2019

In this paper, we define a mean of two positive numbers called the k-golden mean and study some properties of it. Especially, we show that the 2-golden mean refines the harmonic and the geometric means. As an application, we define the k-golden ratio and give some properties of it as an generalization of the golden ratio. Furthermore, we define the matrix k-golden mean of two positive-definite matrices and give some properties of it. This is an improvement of Lim's results [2] for which the matrix golden mean.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.8
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• pp.53-60
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• 2009

A low-power/small-area 128-point FFT processor is designed, which is based on logarithmic number system (LNS) and some design techniques to minimize both hardware complexity and arithmetic error. The complex-number multiplications and additions/subtractions for FFT computation are implemented with LNS adders and look-up table (LUT) rather than using conventional two's complement multipliers and adders. Our design reduces the gate counts by 21% and the memory size by 16% when compared to the conventional two's complement implementation. Also, the estimated power consumption is reduced by about 18%. The LNS-based FFT processor synthesized with 0.35 ${\mu}m$ CMOS standard cell library has 39,910 gates and 2,880 bits memory. It can compute a 128-point FIT in 2.13 ${\mu}s$ with 60 MHz@2.5V, and has the average SQNR of 40.7 dB.

• Journal of Ginseng Research
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• v.22 no.4
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• pp.223-228
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• 1998

As part of a study on the ability of fungicides to control disappearing root rot of ginseng (Panax quinquvdius) caused by Cylindruarpn destmtans, 15 fungicides were screened for toxicity to the fungus in vitro. Highly toxic fungicides were Benlate (benomyl), Thiram (thiram), and Orbit (propiconazole). EC5O values (mg a.i./L) were less than 1 and EC95 values were less than 10. Crown (carbathiin and thiabendazole), ASC-66835 (fluazinam), and UBI-2584 (tebuconazole) were moderately toxic, with EC5O values in the range 1-10 and EC95 values in the range 32-45. Weakly toxic fungicides (EC5O in the range 20-80, EC95 in the range 35-140) included UBI-2643 (thiabendazole), UBI-2565 (cyproconazole), and Vitaflo-280 (carbathiin and thiram). Anvil (hexaconazole), Vitaflo-250 (carbathiin), UBI-2383 (triadimenol), Daconil (chlorothalonil), CGA-173506 (fludioxonil), and CGA-169374 (difeno- conazole) were considered nontoxic to C. destmtan (EC5O 1.29->600, EC95>500). Relations between proportional inhibition of growth and concentration of fungicide were linear on arithmetic plots (Benlate, UBI-2643, UBI-2565, Vitaflo-280) or logarithmic plots (all other fungicides). Based on toxicity in vitro and formulation, it is recommended that Benlate, Orbit, and ASC-66835 be tested as soil drenches, and Benlate, Thiram, UBI-2584, and Crown be tested as seed treatments for controlling disappearing root rot.

• Journal of Preventive Medicine and Public Health
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• v.19 no.1 s.19
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• pp.130-136
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• 1986

The particle size of suspended particulates was measured by a Anderson air sampler from Mar. 1982 to Feb. 1984 in a part of Seoul. It was concluded as follows : 1) The arithmetic concentration of suspended particulates was $147.8{\mu}g/m^3$ in Spring, 136.9 in Summer, 131.9 in Autumn and 158.1 in Winter respectively. 2) The cumulative distribution of suspended particulates size in logarithmic diagram showed similar to normal log distribution. 3) The atmospheric particulate matters showed a bimodal size distribution on the base of unit particle concentrations, which divided at approximately $2{\mu}m$ in the diameter. 4) While the fine particulates less than $2.1{\mu}m\;was\;35.4{\sim}45.0%$, the coarse particulates was $55.0{\sim}64.5%$. 5) The higher the concentration of suspended particulates, the more increased the ratio of fine particulates. The higher the concentration of suspended particulates, the lower median size of suspended particulate as well. 6) The respirable dust particulates less than $4.7{\mu}m\;was\;52.2{\sim}62.9%$ in seasonal average through the 2 year samples. With the above result, air pollution concerned with public health could be evaluated and the control measures also are suggested.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.809-811
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• 2010

In most floating-point operations related with 3D graphic applications for mobile devices, properly approximated data calculations with reduced complexity and low power are preferable to exactly rounded floating-point operations with unnecessary preciseness with cost. Among all the sophisticated floating-point arithmetic operations, multiplication and division are the most complicated and time-consuming, and they can be transformed into addition and subtraction repectively by adopting the logarithmic conversion. In this process, the most important factor for performance is how high we can make an approximation of the logarithm conversion. In this paper, we cover the trends in studying the logarithm conversion circuit designs. We also discuss the important factor in design issues and the applicable fields in detail.