• Title/Summary/Keyword: gains rate

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Empirical Analysis on Exchange Rate Determination in Global Foreign Exchange Markets : The Case of 10 Major Countries (글로벌 외환시장의 환율 결정구조 분석에 관한 실증연구 : 주요 10개국을 중심으로)

  • Rhee, Hyun-Jae
    • International Area Studies Review
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    • v.14 no.3
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    • pp.221-246
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    • 2010
  • The paper is basically attempted to reveal a mechanism of exchange rate determination in global foreign exchange markets. For a theoretical framework, uncovered interest rate parity(UIRP), covered interest rate parity(CIRP), and real interest rate parity(RIRP) are tentatively adapted, and GARCH-M model is employed for an econometric methodology. Empirical evidence shows that the UIRP is superior to others, and the RIRP is better than the CIRP in explaining how exchange rates are determined in global exchange markets. All of them, however, is not fully supported by economic theories. Following Frankel(1989), country premium, volatility premium, and currency premium are evaluated to see if which premium is a crucial in disturbing the RIRP, and it is found that country and currency premiums are a major components in disturbing the RIRP. To this end, market-oriented and market-determined systems has to be built to avoid currency disputes which is undergoing hot issue in global foreign exchange market.

Optimization of coding and PRML detection scheme for perpendicular magnetic recording systems (수직 자기기록 시스템을 위한 코딩 및 PRML 검출 방법의 최적화)

  • Lee Joo hyun;Lee Jae jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.3C
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    • pp.59-63
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    • 2005
  • We propose non-DC-free generalized PRML (GPRML) that are suppressed DC contents for matching to the response of perpendicular magnetic recording channel with a ring-head. In addition, DC-free encoding is considered to prevent low-frequency disturbances. The SNR performance is obtained by combining the various PRML channels with DC-free and non-DC-free codes during the normalized recording density increases from 2.5 to 3.5. The GPRML detections without using DC-free code get SNR gains more than 1dB compared to the conventional PRML systems at 10/sup -5/BER. We confirmed that the rate 127/136 DC-free coded GPRML systems show good performances compared with the 16/17 non-DC-free coded GPRML systems. In results, DC-free coded GPRML detections get gains about 1.4dB and 2.0dB at the density of 3.3 and 3.5, respectively.

Design of Excitation Control System of Synchronous Generator on Board Ships (선박용 동기 발전기의 여자 제어시스템 설계)

  • Lee, Youngchan;Jung, Byung-Gun
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.3
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    • pp.298-305
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    • 2015
  • This paper provides experimental results of an excitation control system of the synchronous generator on board ships in accordance with rules of classification society to make sure its performance. The experiment compares and reviews control results between PID control and fuzzy logic control applied to change of loads of the generator in order to make sure to satisfy the rules of classification society. Both of them are written by Labview program. In case of PID Control, this paper firstly adjusts the gains by ultimate sensitive method and the gains is more tuned by engineer's experience. And the fuzzy logic controller uses Mamdani method to make membership function for error between reference voltage and measuring voltage, differential error rate and output voltage. This paper is to make sure the experimental results of the proposed excitation control system applied to actual small synchronous generator with PID control and fuzzy logic written by using Labview program and it is proved on stability and improvement through experiments.

Analysis of a TC-16ADPSK Performance for Transmitting Different Information on One Channel Simultaneously (TC-16ADPSK을 사용한 이종 정보 동시 전송용 변조방식의 성능 분석)

  • 이원석;강희훈;이성백
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.37 no.5
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    • pp.71-76
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    • 2000
  • A TC-16ADPSK scheme for transmitting different kinds of information simultaneously is proposed in this paper. The scheme is designed for simultaneously transmitting two kinds of Information on one channel. In signal mapping, a data of two kinds of information is used to phase modulation on Star-16APSK constellation and the other to amplitude modulation. In detection, each data independently recovers from mixing signal on each detector Therefore, we can transmit two kinds of Information on one channel can be transmitted efficiently. BER performance of the proposed scheme is analyzed on AWGN channel and Rayleigh fading channels on a computer with Matlab communication toolbox. On same SNR, the Gray code mapping has more 0.5-1.5dB coding gains than Ungerboeck's code mapping gains.

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Water Layer in Course of Corrosion of Copper in Humid Air Containing $SO_2$

  • Sasaki, Takeshi;Itoh, Jun;Ohtsuka, Toshiaki
    • Corrosion Science and Technology
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    • v.2 no.2
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    • pp.88-92
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    • 2003
  • The technique for in situ simultaneous measurements of IR-RAS and QCM, which has been developed for investigation of corrosion in gaseous environments, was employed to study the effects of an extremely thin water layer on the corrosion rate. An evaporated copper film on a QCM element was exposed to air containing water vapor and $SO_2$, and time-resolved IR-RAS spectra were measured and mass gains were simultaneously followed with QCM. The tested ranges of relative humidity (RH) and concentration of $SO_2$ were 60% - 90% and 1 - 20 ppm, respectively. On the basis of 2D-IR analysis, the corrosion products were determined to be Chevreul's salt ($CuSO_3Cu_2SO_3{\cdot}2H_2O$) and $CuSO_4{\cdot}5H_2O$. By constructing curves of the relations between band intensities of IR spectra and mass gains of QCM for the corrosion products, the time variations in each product were determined from spectral experiments on copper plates. The thicknesses of physically adsorbed water layers in course of the corrosion process were also determined from water band intensities. The results showed that the thickness of the physically adsorbed water layer increased with increase in RH, and it also increased with increase in accumulation of corrosion products. The latter is probably due to the capillary effect of the corrosion products.

Adaptive OFDMA with Partial CSI for Downlink Underwater Acoustic Communications

  • Zhang, Yuzhi;Huang, Yi;Wan, Lei;Zhou, Shengli;Shen, Xiaohong;Wang, Haiyan
    • Journal of Communications and Networks
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    • v.18 no.3
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    • pp.387-396
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    • 2016
  • Multiuser communication has been an important research area of underwater acoustic communications and networking. This paper studies the use of adaptive orthogonal frequency-division multiple access (OFDMA) in a downlink scenario, where a central node sends data to multiple distributed nodes simultaneously. In practical implementations, the instantaneous channel state information (CSI) cannot be perfectly known by the central node in time-varying underwater acoustic (UWA) channels, due to the long propagation delays resulting from the low sound speed. In this paper, we explore the CSI feedback for resource allocation. An adaptive power-bit loading algorithm is presented, which assigns subcarriers to different users and allocates power and bits to each subcarrier, aiming to minimize the bit error rate (BER) under power and throughput constraints. Simulation results show considerable performance gains due to adaptive subcarrier allocation and further improvement through power and bit loading, as compared to the non-adaptive interleave subcarrier allocation scheme. In a lake experiment, channel feedback reduction is implemented through subcarrier clustering and uniform quantization. Although the performance gains are not as large as expected, experiment results confirm that adaptive subcarrier allocation schemes based on delayed channel feedback or long term statistics outperform the interleave subcarrier allocation scheme.

Effect of Brewery Waste Replacement of Concentrate on the Performance of Local and Crossbred Growing Muscovy Ducks

  • Dong, Nguyen Thi Kim;Ogle, R.Brian
    • Asian-Australasian Journal of Animal Sciences
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    • v.16 no.10
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    • pp.1510-1517
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    • 2003
  • Two experiments were carried out to evaluate the effects of brewery waste (BW) replacement of concentrate (C) in growing duck diets. In Exp. 1, which was carried out on-station, 300 ducklings were allocated in a $2{\times}5$ factorial experiment: Two breeds (local Muscovy and crosses of French and local Muscovy)${\times}5$ levels of C and with BW offered ad libitum. Concentrate only ad libitum as the control diet (C100), and levels of 75% (C75), 50% (C50), 25% (C25) and 0% (C0) of the amount of the control diet consumed, and with BW ad libitum. In Exp. 2, 200 ducklings were allocated in a $2{\times}2$ factorial experiment on five smallholdings: two breeds (local and crossbred Muscovy ducks)${\times}2$ diets (the C100 and C50 diets from Exp.1). In Exp.1 total dry matter (DM), BW, crude fiber (CF) and crude protein (CP) intakes were highest on the C0 diet and ME and lysine intakes lowest (p<0.001). Daily live weight gains were higher for the crossbred ducks than for the local Muscovies (p<0.05) and were highest for treatments C100 and C50, and lowest for treatment C0 (p<0.05). Weights of breast muscle, liver and abdominal fat were significantly higher for the crossbred ducks. Breast and thigh muscle and abdominal fat weights were significantly higher for the C100, C75 and C50 diets, while gizzard weights were highest for the C25 and C0 treatments. Net profits were higher for the crosses, and for treatments C50 and C25. In Exp. 2 total DM, CF and CP intakes were significantly higher for the C50 diet, and ME intakes lower (p<0.001). Daily gains of the crosses were significantly higher than those of the local Muscovy ducks, and were similar for the C100 and C50 diets. The highest net profits were from the crosses and ducks fed the C50 diet. It was concluded that BW can replace 50% of the concentrate in growing Muscovy duck diets without reducing daily live weight gains and with improved economic benefits.

The Economic Effects of Tax Incentives for Housing Owners: An Overview and Policy Implications (주택소유자(住宅所有者)에 대한 조세감면(租稅減免)의 경제적(經濟的) 효과(效果) : 기존연구(旣存硏究)의 개관(槪觀) 및 정책시사점(政策示唆點))

  • Kim, Myong-sook
    • KDI Journal of Economic Policy
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    • v.12 no.2
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    • pp.135-149
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    • 1990
  • Housing owners in Korea have a variety of tax advantages such as income tax exemption for the imputed rent of owner-occupied housing, exemption from the capital gains tax and deduction of the estate tax for one-house households. These tax reliefs for housing owners not only conflict with the principle of horizontal and vertical equity, but also lead to resource misallocation by distorting the housing market, and thus bring about regressive distribution effects. Particularly in the case of Korea with its imperfect capital market, these measures exacerbate the inter-class inequality of housing ownership as well as inequalities in wealth, by causing the affluent to demand needlessly large housing, while the poor and young experience difficulties in purchasing residential properties. Therefore, the Korean tax system must be altered as follows in order to disadvantage owner-occupiers, especially those owners of luxury housing. These alterations will promote housing-ownership, tax burden equity, efficiency of resource allocation, as well as the desirable distribution of income. First, income tax deductions for the rent payments of tenants are recommended. Ideally, the way of recovering the fiscal equivalence between the owner-occupiers and tenants is to levy an income tax on the former's imputed rents, and if necessary to give them tax credits. This, however, would be very difficult from a practical viewpoint, because the general public may perceive the concept of "imputed rent" as cumbersome. Computing the imputed rent also entails administrative costs, rendering quite reasonable, the continued exemption of imputed rent from taxation with the simultaneous deduction in the income tax for tenants. This would further enhance the administrative efficiency of income tax collection by easing assessment of the landlord's income. Second, a capital gains tax should be levied on the one-house household, except with the postponement of payments in the case that the seller purchases higher priced property. Exemption of the capital gains tax for the one-house household favors those who have more expensive housing, providing an incentive to the rich to hold even larger residences, and to the constructors to build more luxurious housing to meet the demand. So it is not desirable to sustain the current one-house household exemption while merely supplementing it with fastidious measures. Rather, the rule must be abolished completely with the concurrent reform of the deduction system and lowering of the tax rate, measures which the author believes will help optimize the capital gains tax incidence. Finally, discontinuation of the housing exemption for the heir is suggested. Consequent increases in the tax burden of the middle class could be mitigated by a reduction in the rate. This applies to the following specific exemptions as well, namely, for farm lands, meadows, woods, business fields-to foster horizontal equity, while denying speculation on land that leads to a loss in allocative efficiency. Moreover, imperfections in the Korean capital market have disallowed the provision of long term credit for housing seekers. Remedying these problems is essential to the promotion of greater housing ownership by the low and middle income classes. It is also certain that a government subsidy be focused on the poorest of the poor who cannot afford even to think of owning a housing.

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Embedded Image Compression Scheme Using Rate-Distortion Optimized Block Coding of Wavelet Coefficients (웨이브렛 계수의 비트율-왜곡 최적화 기반 블록 부호화를 이용하는 임베디드 영상 압축 방법)

  • Yang, Chang Mo;Chung, Kwangsue
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.11
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    • pp.625-636
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    • 2014
  • In this paper, we propose a new embedded image compression scheme which uses rate-distortion optimized block coding of wavelet coefficients. Unlike to previous works in which set-partition or block-partition is performed according to the magnitude of wavelet coefficients, the proposed scheme achieves rate-distortion optimization by sorting wavelet coefficients or blocks according to their expected rate-distortion slope. At the same time, it performs the optimized block-partition coding using the expected rate-distortion slope of blocks. The proposed scheme also uses various relationship of wavelet coefficients for the entropy coding. Experimental results demonstrate that the proposed image compression scheme provides better overall performance than the existing embedded coding schemes such as SPIHT and EBCOT, in which the PSNR gains of the proposed scheme are about 0.11~1.16dB and -0.18~0.52dB, respectively.

Modeling and State Observer Design of HEV Li-ion Battery (하이브리드 전기자동차용 리튬이온 배터리 모델링 및 상태 관측기 설계)

  • Kim, Ho-Gi;Heo, Sang-Jin;Kang, Gu-Bae
    • The Transactions of the Korean Institute of Power Electronics
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    • v.13 no.5
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    • pp.360-368
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    • 2008
  • A lumped parameter model of Li-ion battery in hybrid electric vehicle(HEV) is constructed and system parameters are identified by using recursive least square estimation for different C-rates, SOCs and temperatures. The system characteristics of pole and zero in the frequency domain are analyzed with the parameters obtained from different conditions. The parameterized model of a Li-ion battery indicates highly dependent of temperatures. To estimate SOC and polarization voltage, a Luenberger state observer is utilized. The P- or PI-gains of observer based on a suitable natural frequency and damping ratio is adopted for the state estimation. Satisfactory estimation accuracy of output voltage and SOC is especially obtained by a PI-gain. The feasibility of the proposed estimation method is verified through experiment under the conditions of different C-rates, SOCs and temperatures.