• 정보보호학회논문지
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• 제27권6호
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• pp.1385-1395
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• 2017

본 논문에서는 정상과 이상 트래픽이 불균형적으로 발생하는 상황에서 기계 학습 기반의 효과적인 침입 탐지 시스템에 관한 연구 결과를 소개한다. 훈련 데이터의 패턴을 학습하여 정상/이상 패킷을 탐지하는 기계 학습 기반의 IDS에서는 훈련 데이터의 클래스 불균형 정도에 따라 탐지 성능이 현저히 차이가 날 수 있으나, IDS 개발 시 이러한 문제에 대한 고려는 부족한 실정이다. 클래스 불균형 데이터가 발생하는 환경에서도 우수한 탐지 성능을 제공하는 기계 학습 알고리즘을 선정하기 위하여, 본 논문에서는 Kyoto 2006+ 데이터셋을 이용하여 정상 대 침입 클래스 비율이 서로 다른 클래스 불균형 훈련 데이터를 구축하고 다양한 기계 학습 알고리즘의 인식 성능을 분석하였다. 실험 결과, 대부분의 지도 학습 알고리즘이 좋은 성능을 보인 가운데, Random Forest 알고리즘이 다양한 실험 환경에서 최고의 성능을 보였다.

• 한국식품저장유통학회지
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• 제24권1호
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• pp.100-106
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• 2017

본 연구는 환자용 균형영양식으로 제조하여 감마선 조사처리를 통해 살균한 모델식품의 유전독성 여부를 평가하기 위해 수행되었다. 4 kGy 이상의 흡수선량으로 감마선 조사 처리한 시료에서 생균수가 1 log CFU/g의 검출한계 이하로 나타났기 때문에 살균을 위한 조사처리 선량으로 4 kGy를 설정하였다. 복귀돌연변이 유발성 평가 결과, 모델식품의 열수 추출물과 메탄올 추출물은 처리한 용량과 대사활성계 존재 여부와는 상관없이 음성대조구(멸균증류수 또는 DMSO)와 유사한 수준의 복귀돌연변이 발생빈도를 나타내었다. 염색체 이상 시험에서 실험군들의 정상 염색체의 수는 음성대조군과 유사하였으며, 용량 및 대사활성계에 대한 비의존성을 나타내어 염색체 이상 유발능은 없는 것으로 판단하였다. 또한 최고 2,000 mg/kg 체중의 농도로 모델식품을 경구 투여한 마우스의 골수세포에서도 소핵 다염성적 혈구의 발생빈도는 음성대조군에 비해 유의적인 차이를 나타내지 않았다. 따라서 4 kGy의 흡수선량으로 감마선 조사처리한 환자용 균형영양식은 본 실험 조건하에서 유전독성을 나타내지 않는 것으로 사료된다.

• 대한의용생체공학회:의공학회지
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• 제29권6호
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• pp.466-476
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• 2008

The more people use ambulatory electrocardiogram(ECG) for arrhythmia detection, the more researchers report the automatic classification algorithms. Most of the previous studies don't consider the un-balanced data distribution. Even in patients, there are much more normal beats than abnormal beats among the data from 24 hours. To solve this problem, the hierarchical classification using 21 features was adopted for arrhythmia abnormal beat detection. The features include R-R intervals and data to describe the morphology of the wave. To validate the algorithm, 44 non-pacemaker recordings from physionet were used. The hierarchical classification model with 2 stages on domain knowledge was constructed. Using our suggested method, we could improve the performance in abnormal beat classification from the conventional multi-class classification method. In conclusion, the domain knowledge based hierarchical classification is useful to the ECG beat classification with unbalanced data distribution.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.471-479
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• 2017

White spot syndrome virus (WSSV) is a major threat to the shrimp farming industry and so far there is no effective therapy for it, and thus early diagnostic of WSSV is of great importance. However, at the early stage of infection, the extremely low-abundance of WSSV DNA challenges the detection sensitivity and accuracy of PCR. To effectively detect low-abundance WSSV, here we developed a pre-amplification PCR (pre-amp PCR) method to amplify trace amounts of WSSV DNA from massive background genomic DNA. Combining with normal specific PCR, 10 copies of target WSSV genes were detected from ${\sim}10^{10}$ magnitude of backgrounds. In particular, multiple target genes were able to be balanced amplified with similar efficiency due to the usage of the universal primer. The efficiency of the pre-amp PCR was validated by nested-PCR and quantitative PCR, and pre-amp PCR showed higher efficiency than nested-PCR when multiple targets were detected. The developed method is particularly suitable for the super early diagnosis of WSSV, and has potential to be applied in other low-abundance sample detection cases.

• Journal of Electrochemical Science and Technology
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• 제12권4호
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• pp.415-423
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• 2021

For a battery module where single cells are connected in series, the single cells should each have a similar state of charge (SOC) to prevent them from being exposed to an overcharge or over-discharge during charge-discharge cycling. To detect the existence of unbalanced SOC cells in a battery module, we propose a simple measurement method using a single-frequency response of electrochemical impedance spectroscopy (EIS). For a commercially available graphite/nickel-cobalt-aluminum-oxide lithium-ion cell, the cell impedance increases significantly below SOC20%, while the impedance in the medium SOC region (SOC20%-SOC80%) remains low with only minor changes. This impedance behavior is mostly due to the elementary processes of cathode reactions in the cell. Among the impedance values (Z, Z', Z"), the imaginary component of Z" regarding cathode reactions changes heavily as a function of SOC, in particular, when the EIS measurement is performed around 0.1 Hz. Thanks to the significant difference in the time constant of cathode reactions between ≤SOC10% and ≥SOC20%, a single-frequency EIS measurement enlarges the difference in impedance between balanced and unbalanced cells in the module and facilitates an ~80% improvement in the detection signal compared to results with conventional EIS measurements.

• Journal of Magnetics
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• 제17권4호
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• pp.298-301
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• 2012

In order to know the effect of surface irregularity in the detection of local wall thinning of pipeline using pulsed eddy current (PEC), the lift-off effects on PEC signal have been investigated. Three kinds of parameters in the PEC signal, which is "peak amplitude", "time to peak amplitude" and "time to zero crossing" are analyzed to separate the lift-off effects in the PEC signal. The distance from sensor to the bottom of sample which is the total thickness of combined insulator and sample is kept constant. The magnitude of the differential peak amplitude is increased with increasing sample thickness, the time to peak amplitude is increased with increasing the sample thickness. To determine the effect of lift-off, a number of balanced transient responses combining wall thinning locations and lift-off distances were plotted.

• 응용통계연구
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• 제7권2호
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• pp.201-211
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• 1994

다구찌에 의해서 개발된 파라미터 설계법에서는 교호작용효과를 무시하고 직교배열을 이용하여 실험을 분석하는 것이 일반적인 방법으로 사용되고 있다. 본 논문에서는 직교배열과 거의 유사한 통계적 성질을 가지면서 최소의 실험횟수로 2인자 교호작용까지 분석할 수 있는 실험계획을 제시하고, 이러한 계획법에 의해 파라미터 설계법을 분석하고 유의적인 2인자 교호작용까지 검출하는 방법을 제시하였다.

• 조명전기설비학회논문지
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• 제26권3호
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• pp.61-68
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• 2012

This paper deals with a fault diagnosis algorithm for open faults in the switching devices of PWM inverter-fed IPMSM (Interior Permanent Magnet Synchronous Motor) drive. The proposed diagnostic algorithm is realized in the controller using the informations of three-phase currents or reference line-to-line voltages, without requiring additional equipments for fault detection. Under switch open fault conditions, the conventional dq model used to control an AC motor cannot directly be applied for the analysis of drive system, since three-phase balanced condition does not hold. To overcome this limitation, a fault model based on the line-to-line voltages is employed for the simulation studies. For comparative performance evaluation through the experiments, the entire control system is implemented using digital signal processor (DSP) TMS320F28335. Simulations and experimental results are presented to verify the validity of the proposed diagnosis algorithm.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2018년도 추계학술대회
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• pp.117-118
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• 2018

본 논문에서는 작은 객체를 검출하기 위한 수정 된 YOLOv3-tiny 를 제안한다. 컴퓨터 비전에서 작은 객체 검출은 제한된 해상도와 정보로 검출하기 어렵다. 이 문제를 해결하기 위해 기존 방법의 대부분은 높은 정확도 향상을 위해 속도를 희생한다. 본 논문은 정확도와 속도가 균형적인 성능을 통해 빠른 속도로 작은 객체를 검출하는 것을 목표로 한다. 실험은 WIDER FACE 와 자체 수집한 데이터베이스에서 기존 YOLOv3-tiny 보다 높은 87.48% mAP 를 얻었으며, 속도는 각각 100.5FPS 로 YOLOv3-tiny 보다는 느리지만 높은 정확도와 YOLOv3 보다는 빠르지만 낮은 정확도를 통해 균형적인 성능을 얻을 수 있다.

• Journal of Power Electronics
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• 제14권6호
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• pp.1303-1313
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• 2014

Dynamic behavior of the harmonic detection part of an active power filter (APF) has an essential role in filter compensation performances during transient conditions. Instantaneous power (p-q) theory is extensively used to design harmonic detectors for active filters. Large overshoot of p-q theory method deteriorates filter response at a large and rapid load change. In this study the harmonic estimation of an APF during transient conditions for balanced three-phase nonlinear loads is conducted. A novel fuzzy instantaneous power (FIP) theory is proposed to improve conventional p-q theory dynamic performances during transient conditions to adapt automatically to any random and rapid nonlinear load change. Adding fuzzy rules in p-q theory improves the decomposition of the alternating current components of active and reactive power signals and develops correct reference during rapid and random current variation. Modifying p-q theory internal high-pass filter performance using fuzzy rules without any drawback is a prospect. In the simulated system using MATLAB/SIMULINK, the shunt active filter is connected to a rapidly time-varying nonlinear load. The harmonic detection parts of the shunt active filter are developed for FIP theory-based and p-q theory-based algorithms. The harmonic detector hardware is also developed using the TMS320F28335 digital signal processor and connected to a laboratory nonlinear load. The software is developed for FIP theory-based and p-q theory-based algorithms. The simulation and experimental tests results verify the ability of the new technique in harmonic detection of rapid changing nonlinear loads.