• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.515-519
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• 1997

The purpose of this study is to reduce the fast neutron fluence at the reactor pressure vessel(RPV) and to provide a basis for plant-life extension. In this study, different neutron absorbers were employed in the core outer assemblies of Kori Unit 1 Cycle 14. The modified assemblies were used to calculate fast neutron fluence at the RPV and to evaluate reduction of outer assembly power and total power in core. By comparison with the case of no suppression fixture, the fast neutron fluence of a case with two rows stainless steel around the assembly with natural uranium pins is decreased by 85.8%. It is noted that the modification of outer assembly is more efficient than the previous low leakage loading pattern (LLLP) applied to Kori Unit 1. Also, compared fast neutron fluence in Cycle 1 with Cycle 14, fast neutron fluence at the RPV between Cycle 1 and Cycle 14 is not significantly different. It is found that LLLP applied to the Kori Unit 1 has not contributed to fast neutron fluence reduction at the RPV.

• 천문학회지
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• 제34권1호
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• pp.1-8
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• 2001

We present a fast reduction method of survey data obtained using a single-dish radio telescope. Along with a brief review of classical method, a new method of identification and elimination of negative and positive bad channels are introduced using cloud identification code and several IRAF (Image Reduction and Analysis Facility) tasks relating statistics. Removing of several ripple patterns using Fourier Transform is also discussed. It is found that BACKGROUND task within IRAF is very efficient for fitting and subtraction of base-line with varying functions. Cloud identification method along with the possibility of its application for analysis of cloud structure is described, and future data reduction method is discussed.

• ETRI Journal
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• 제44권3호
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• pp.379-388
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• 2022

This study proposes a novel low-complexity algorithm for computing inverse fast Fourier transform (IFFT)/fast Fourier transform (FFT) operations in binary phase shift keying-modulated orthogonal frequency division multiplexing (OFDM) communication systems without requiring any twiddle factor multiplications. The peak-to-average power ratio (PAPR) reduction capacity of an efficient PAPR reduction technique, that is, H-SLM method, is evaluated using the proposed IFFT algorithm without any complex multiplications, and the impact of oversampling factor for the accurate calculation of PAPR is analyzed. The power spectral density of an OFDM signal generated using the proposed multiplierless IFFT algorithm is also examined. Moreover, the bit-error-rate performance of the H-SLM technique with the proposed IFFT/FFT algorithm is compared with the classical methods. Simulation results show that the proposed IFFT/FFT algorithm used in the H-SLM method requires no complex multiplications, thereby minimizing power consumption as well as the area of IFFT/FFT processors used in OFDM communication systems.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.31-35
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• 2004

A new combustion strategy called LIFC(Late Injection ＆ Fast Combustion) was developed for simultaneous reduction of particulate matter(PM) and nitrogen oxides(NOx) in exhaust emission of diesel engines, In this study, effects of injection timing and injection pressure under relatively high EGR rate were investigated. The experiments were conducted in a conventional engine over a range of commercial engine speed. The test engine could be operated in LIFC up to 2000rpm / bmep 5 bar condition with significant reduction of NOx and PM. The experimental results showed potential for the mechanism of the simultaneous reduction of NOx and PM from HSDI diesel engines.

• Genomics & Informatics
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• 제16권4호
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• pp.37.1-37.3
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• 2018

Gene-gene interaction is a key factor for explaining missing heritability. Many methods have been proposed to identify gene-gene interactions. Multifactor dimensionality reduction (MDR) is a well-known method for the detection of gene-gene interactions by reduction from genotypes of single-nucleotide polymorphism combinations to a binary variable with a value of high risk or low risk. This method has been widely expanded to own a specific objective. Among those expansions, fuzzy-MDR uses the fuzzy set theory for the membership of high risk or low risk and increases the detection rates of gene-gene interactions. Fuzzy-MDR is expanded by a maximum likelihood estimator as a new membership function in empirical fuzzy MDR (EFMDR). However, EFMDR is relatively slow, because it is implemented by R script language. Therefore, in this study, we implemented EFMDR using RCPP ($c^{{+}{+}}$ package) for faster executions. Our implementation for faster EFMDR, called EMMDR-Fast, is about 800 times faster than EFMDR written by R script only.

• 정보보호학회논문지
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• 제25권2호
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• pp.241-251
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• 2015

유한체 연산을 기반으로 하는 공개키 암호 시스템은 고속 연산이 매우 중요한 과제이다. 본 논문에서는 8-bit ATmega128 프로세서 환경에서 이진 기약다항식 $f(x)=x^{271}+x^{207}+x^{175}+x^{111}+1$과 $f(x)=x^{193}+x^{145}+x^{129}+x^{113}+1$을 이용한 감산 연산의 효율성을 높이는 데에 중점을 두었다. 기존의 감산 연산 알고리즘인 Fast reduction의 최종적인 감산 결과 값을 제시함으로써, 중복 발생하는 메모리 접근을 최소화 하여 최적화된 감산 알고리즘을 제시한다. 제안하는 기법을 어셈블리 언어로 구현 시 기존의 감산 연산 알고리즘과 비교하여 각각 53%, 55% 향상된 결과를 얻었다.

• 한국식생활문화학회지
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• 제24권5호
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• pp.518-524
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• 2009

This study was conducted to investigate the effects of fast food customer's perceived risks on risk reduction behavior, attitude and purchase intention. A total of 268 usable surveys were collected using a stratified random sampling method. Descriptive analysis and factor analysis was then conducted using SPSS 12.0, and a Cronbach's $\alpha$ was generated to estimate the internal consistency of the survey items. Multiple regression analysis was used to evaluate the relationships among variables. The results indicated that fast food safety and monetary risks had a negative effect on customer feelings and satisfaction with fast food, which had a positive effect on buying purpose and recommendation purpose. Conversely, obesity and monetary risks only had a negative effect on buying purpose. An improved menu more effectively reduced the risk perceived by the fast-food customers than an improved image.

• 공업화학
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• 제17권4호
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• pp.414-419
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• 2006

연소 배기가스 중의 수분, 탄화수소 및 CO가 저온 플라즈마 및 $NH_{3}$ SCR (Selective Catalytic Reduction)공정이 복합된 탈질공정에 미치는 영향에 대한 연구가 수행되었다. 실험결과 일반적인 SCR 반응에 비해 매우 빠른 반응속도를 갖는 fast SCR 반응은 $150{\sim}200^{\circ}C$의 저온조건에서 탈질율의 상승을 가져다주지만, 처리가스 중에 탄화수소가 있는 경우 fast SCR 반응의 역할이 상당히 감소되는 것을 확인할 수 있었다. 이는 저온 플라즈마 반응기에서 부분산화반응을 통해 탄화수소 중 일부가 알데히드로 전환되며, 알데히드는 fast SCR 반응에 있어 중요한 변수인 $NO_{2}/NO_{x}$ 비율에 영향을 주기 때문인 것으로 설명되었다. 한편, 수분 및 CO가 fast SCR 반응에 미치는 영향은 탄화수소에 비해 상대적으로 적음을 확인할 수 있었다.

• 공업화학
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• 제24권3호
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• pp.333-336
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• 2013

산업현장에서 배출되는 저온($150{\sim}250^{\circ}C$)의 배기가스에 포함된 질소산화물($NO_x$)을 제거하기 위한 공정으로써 산화 촉매와 암모니아 SCR 공정을 복합시킨 fast SCR 탈질공정에 대한 실험적인 연구가 수행되었다. Fast SCR 탈질공정을 위해서는 산화촉매를 이용 NO를 $NO_2$로 전환하는 것이 요구된다. 산화촉매 부피(Oxidation Catalyst Volume, OCV)에 따른 NO 전환율을 실험적으로 확인하였다. OCV 563000 h, 375000 h, 281000 h 각 경우에 NO 전환율은 37% : 45% : 51%이었다. 온도에 따른 fast SCR 탈질효율은 $NO_2/NO_x$ 비율 45%일 때 가장 높았다. $NO_2/NO_x$ 비율 45%, 온도 $200{\sim}250^{\circ}C$ 및 공간속도 $10000{\sim}30000h^{-1}$에서 standard SCR과 fast SCR 탈질효율을 비교한 결과, standard SCR은 공간속도 에 따라 온도별로 차이를 보였으나 fast SCR은 차이를 보이지 않았다. Fast SCR 반응을 고려한 탈질운전에서 공간속도 $10000h^{-1}$에서의 촉매부피와 비교하여 공간속도 $30000h^{-1}$으로 운전할 경우, NH3 SCR 촉매부피를 50% 이상 줄일 수 있음을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.351-359
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• 2016

The Korean Prototype Gen-IV sodium-cooled fast reactor (PGSFR) is supposed to be loaded with a relatively-costly low-enriched U fuel, while its envisaged transuranic fuels are not available for transmutation. In this work, the U-enrichment reduction by improving the neutron economy is pursued to save the fuel cost. To improve the neutron economy of the core, a new reflector material, PbO, has been introduced to replace the conventional HT9 reflector in the current PGSFR core. Two types of PbO reflectors are considered: one is the conventional pin-type and the other one is an inverted configuration. The inverted PbO reflector design is intended to maximize the PbO volume fraction in the reflector assembly. In addition, the core radial configuration is also modified to maximize the performance of the PbO reflector. For the baseline PGSFR core with several reflector options, the U enrichment requirement has been analyzed and the fuel depletion analysis is performed to derive the equilibrium cycle parameters. The linear reactivity model is used to determine the equilibrium cycle performances of the core. Impacts of the new PbO reflectors are characterized in terms of the cycle length, neutron leakage, radial power distribution, and operational fuel cost.