• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1311-1317
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• 2021

In this study, an airborne alpha detection system, which consists of a passivated implanted planar silicon (PIPS) detector and an air filter, was developed. A collimator applied to the alpha detection system showed an enhancement in resolution and a degradation in detection efficiency. The resolution and detection efficiency were compared and analyzed to evaluate the performance of the collimator. Thus, the resolution was found to be more important than the efficiency as a determining factor of the detection system performance, from the viewpoint of radionuclide identification. The performance was evaluated on three properties of the collimator: hole shape, hole length, and the ratio between the hole and frame pitches. From the hole shape performance evaluation, a hexagonal collimator showed the highest resolution. Further, the collimator with a hole pitch of 14 mm was found to have the highest resolution while that with a frame pitch of 4-6 mm (i.e., 1.2-1.4 times longer than the hole pitch) showed the highest resolution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.269-286
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• 2018

Signal detection in symmetric alpha-stable ($S{\alpha}S$) distributed noise is a challenging problem. This paper proposes a detector based on a decreasing exponential function (DEF). The DEF detector can effectively suppress the impulsive noise and achieve good performance in the presence of $S{\alpha}S$ noise. The analytical expressions of the detection and false alarm probabilities of the DEF detector are derived, and the parameter optimization for the detector is discussed. A performance analysis shows that the DEF detector has much lower computational complexity than the Gaussian kernelized energy detector (GKED), and it performs better than the latter in $S{\alpha}S$ noise with small characteristic exponent values. In addition, the DEF detector outperforms the fractional lower order moment (FLOM)-based detector in $S{\alpha}S$ noise for most characteristic exponent values with the same order of magnitude of computational complexity.

• 정보처리학회논문지C
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• 제12C권4호
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• pp.609-616
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• 2005

시그너쳐 기반 침입탐지 기술은 과탐지(false positive)가 많고 새로운 공격이나 변형된 유형의 공격을 감지하기 어렵다 우리는 앞선 논문[1]을 통해 시그너쳐 기반 침입 탐지 시스템과 기계학습 기반 침입 탐지 시스템을 Alpha-cut 방법을 이용하여 결합한 모델을 제시 하였다. 본 논문은 Alpha-cut의 후속연구로 기존 모델에서 감지하지 못하는 미탐지(false negative)를 줄이기 위한 Beta-pick 방법을 제안한다. Alpha-cut은 시그너쳐 기반 침입탐지 시스템의 공격 탐지결과에 대한 정확성을 높이는 방법인 반면에, Beta-rick은 공격을 정상으로 판단하는 경우를 줄이는 방법이다. Alpha-cut과 Beta-pick을 위해 사용된 기계학습 알고리즘은 XIBL(Extended Instance based Learner)이며, C4.5를 적용했을 때와 차이점을 결과로서 제시한다. 제안한 방법의 효과를 설명하기 위해 시그너쳐 기반 침입탐지 시스템의 탐지결과에 Alpha-cut과 Beta-pick을 적용하여 오경보(false alarm)가 감소함을 보였다.

• Nuclear Engineering and Technology
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• 제52권4호
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• pp.841-845
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• 2020

An airborne alpha beta detection system using passivated implanted planar silicon (PIPS) detector was modeled with the MCNP6 code and its resolution and detection efficiency were analyzed. Simulation of the resolution performed using the Gaussian energy broadening (GEB) function showed that the full width at half maximum (FWHM) of 35.214 keV for alpha particles was within 34-38 KeV, which is the FWHM range of the actual detector, and the FWHM of 15.1 keV for beta particles was constructed with a similar model to 17 keV, which is the FWHM range of an actual detector. In addition, the detection efficiency and the resolution were simulated according to the distance between the detector and the air filter. When the distance was decreased to 0.2 cm from 0.8 cm, the efficiency of the alpha and beta particles detection decreased from 5.33% to 4.89% and from 5.64% to 4.27%, respectively, and the FWHM of the alpha and beta particles improved from 40.9 KeV to 29.84 keV and 25.76 keV-13.27 keV, respectively.

• KSBB Journal
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• 제30권4호
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• pp.197-201
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• 2015

Liquid chromatographic enantiomer separation of ${\alpha}$-amino acids and their methyl and ethyl esters as fluorenylmethoxycarbonyl (FMOC) derivatives was performed using a recently developed chiral column (Chiralpak IE) based on polysaccharide derivative under simultaneous UV detection and fluorescence detection. The degree of enantiomer separation of ${\alpha}$-amino acid esters as FMOC derivatives is generally higher than that of the corresponding ${\alpha}$-amino acids. Especially, ${\alpha}$-amino acid methyl esters showed the greatest enantioseparation. As this method developed in this study can be applied to determine the chemical and optical purity of ${\alpha}$-amino acids and esters, it is expected to be quite useful for their chiral separation using Chiralpak IE.

• Journal of Radiation Protection and Research
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• 제21권3호
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• pp.167-173
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• 1996

알파선 검출 효율 측정을 위한 고체비적검출기의 교정 방법을 제시하였으며, 제시된 교정 방법을 이용하여 CN-85와 LEXAN의 검출 효율을 측정하였다. $0{\sim}5.5MeV$ 에너지 영역의 알파선에 대한 검출 효율을 측정한 결과 CN-85와 LEXAN이 각각 97%, 57%였다. CN-85가 LEXAN에 비해 검출 효율이 높게 나타난 이유는 알파선에 대한 CN-85의 sensitivity가 LEXAN에 비해 좋을 뿐만 아니라 에너지 의존성이 CN-85가 LEXAN에 비해 낮기 때문인 것으로 분석되었으며, CN-85는 알파선의 유도 에너지가 약 3 MeV, LEXAN은 약 1.8 MeV에서 검출 효율이 최대로 나타났다.

• Journal of Communications and Networks
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• 제9권2호
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• pp.185-191
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• 2007

Alpha stable distribution is better for modeling impulsive noises than Gaussian distribution in signal processing. This class of process has no closed form of probability density function and finite second order moments. In general, Wiener filter theory is not meaningful in S$\alpha$SG environments because the expectations may be unbounded. We proposed a new adaptive recursive least p-norm Kalman filtering algorithm based on least p-norm of innovation process with infinite variances, and a new robust multiuser detection method based on least p-norm Kalman filtering. The simulation experiments show that the proposed new algorithm is more robust than the conventional Kalman filtering multiuser detection algorithm.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.320.2-320
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• 2001

• Bulletin of the Korean Chemical Society
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• 제23권3호
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• pp.427-431
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• 2002

A screen printed graphite electrode has been developed for a simple and sensitive determination of phenolic compounds in an aqueous solution. The electrode developed uses a simple and effective screen printing technique with ${\alpha}-Cyclodextrin({\alpha}-CD)$ modified graphite ink. Phenols were captured on the surface of the ${\alpha}-CD$ modified electrode through complex formation. The phenol/ ${\alpha}-CD$ complex was deposited and quantified electrochemically using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV). The optimization of the experimental parameters was performed in regard to electrode composition, pH, temperature, sample preconcentration time. Interferences from other organic compounds were investigated. The detection limit for phenols was 500 ${\pm}7$ nM for DPV, with the linear range of 0.5 ${\mu}M$ -25.0 ${\mu}M$ and 30 ${\pm}2$ nM for SWV, with the linear range of 30 nM - $50{\mu}M$, respectively.

• 한국식품과학회지
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• 제32권3호
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• pp.564-569
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• 2000

가공식품중의 우유단백질 분석을 위하여 효소면역측정법, ELISA를 개발하였다. 특이 항체를 생산하기 위해 열에 안정하고 우유의 주요한 단백질인 ${\alpha}_{s1}-CN$을 토끼에 면역하였다. 항${\alpha}_{s1}-CN$ 항체를 이용하여 간접경합 ELISA를 실시한 결과 검출한계는 $0.1\;{\mu}g/mL$ 이었고 ${\alpha}_{s1}-CN$, skim milk, ${\beta}-CN$과 whey protein isolate에 대한 특이항체의 반응성은 각각 100%, 37%, 0.14%과 0.04% 이었다. 그러나 다른 우유단백질인, ${\beta}-lactoglobulin,\;{\alpha}-lactalbumin$, bovine serum albumin 과 대두단백질인 isolated soy protein 에 대해서는 거의 반응성을 보이지 않았다. 샌드위치 ELISA 결과는 검출한계가 $0.01\;{\mu}g/mL$로 간접경합 ELISA 에 비하여 10배 정도 민감해져 따라서 이를 시료 분석에 이용하였다. 시유에 1-10%의 whole CN을 첨가한 spike test 결과 whole CN의 평균 회수율이 94.8%(CV, 8.2%)으로 나타났다. 식품재료와 유가공 제품에 대한 whole CN의 정량분석을 실시한 결과 탈지유는 29%, WPI는 0.03%, 농후 요구르트는 0.25%였으며 가공치즈는 6.9%로 나타났다.