• ETRI Journal
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• 제29권2호
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• pp.240-242
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• 2007

This letter proposes a simplified maximum likelihood detection (SMLD) scheme to improve the detection performance of multiple-input multiple-output receivers. The SMLD detects V streams according to the first detected V sub-streams. Through an ML test, the most probable stream is selected. Moreover, to detect the layer with the worst post-detection SNR accurately, reverse ordering is applied to the SMLD. Simulation results show that the performance of the Vertical Bell Laboratories layered space-time (V-BLAST) system can be improved by adopting the SMLD technique. In the case of reverse ordering, the SMLD can achieve a similar ML performance with significant reduction in computational complexity.

• 전자공학회논문지B
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• 제32B권1호
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• pp.85-95
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• 1995

The error intensity models for the ML estimation of a signal parameter have been developed in a companion paper [1]. While the methods described in [1] are applicable to any estimation problem with continuous parameters, our main application in this paper is the time delay estimation, and comparisons among the models derived in [1] (i.e. LC, LM, and ALM models)have been made. We first consider the case where only additive Gaussian noise is involved, and then the shot noise environment where coherent impulsive noise is also involved in addition to the Gaussian noise. We compare the models in terms of the probability of error, MSE(Mean Squared Error), and the computational complexity, which are the most important performance criteria in the analysis of parameter estimation. In conclusion, the ALM model turned out to be the most adequate model of all from the viewpoints of the criteria mentioned above.

• 소성∙가공
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• 제16권5호통권95호
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• pp.348-353
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• 2007

The propagation of a macro-scale crack and the accompanying transformation zone around it was visualized in an Y-TZP ceramic using a mechano-luminescence (ML) technique. The technique allows realistic fractures that take place catastrophically in actual applications to be realistically stimulated. Unlike conventional quasi-static R-curves, the ML technique on a relatively fast time frame permitted a so-called quasi-dynamic R-curve in the crack speed range from 50 to 140 m/sec. to be measured. Effective toughening then commenced and the applied stress intensity factor increased to 27 $MPa{\sqrt{m}}$. The transformation zone height obtained from the ML observations was in good agreement with that predicted by the Marshall model, and coincided with previously observed results for quasi-static conditions by Raman spectorscopy and x-ray analysis.

• ETRI Journal
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• 제31권4호
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• pp.454-456
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• 2009

The maximum likelihood linear spectral transformation (ML-LST) using a numerical iteration method has been previously proposed for robust speech recognition. The numerical iteration method is not appropriate for real-time applications due to its computational complexity. In order to reduce the computational cost, the objective function of the ML-LST is approximated and a closed-form solution is proposed in this paper. It is shown experimentally that the proposed closed-form solution for the ML-LST can provide rapid speaker and environment adaptation for robust speech recognition.

• Smart Structures and Systems
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• 제10권6호
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• pp.547-555
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• 2012

Measuring crack length in concrete fracture test is not a trivial problem due to high speed crack propagation. In this study, mechanoluminascent (ML) material, which emits visible light under stress condition, was employed to visualize crack propagation during concrete fracture test. Three-point bending test was conducted with a notched concrete beam specimen. The cracking images due to ML phenomenon were recorded by using a high speed camera as a function of time and external loadings. The experimental results successfully demonstrated the capability of ML material as a promising visualization tool for concrete crack propagation. In addition, an interesting cracking behavior of concrete bending fracture was observed in which the crack propagated fast while the load decreased slowly at early fracture stage.

• 한국환경보건학회지
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• 제10권2호
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• pp.89-97
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• 1984

The possible effects of garlic (Aliium sativurn L.) extract on growth and aflatoxin production by Aspergillus parasiticus R- 716 were investigated. Various solvent extracts of garlic strongly inhibited growth and sporulation by Aspergillus parasiticus R-716, and effective solvents used for extraction of garlic were chloroform, benzene, and water-chloroform. The growth and aflatoxin production decreased with the increase in extract concentration, and extract equivalent 1.5g of raw garlic weight in 25ml SLS medium completely inhibited, and at a level of 1.25g garlic, total aflatoxin was reduced 64% (472 ${\mu}g$/25ml) of that produced in the control (1, 352 ${\mu}g$/25 ml). During cultivation inhibitory rate of growth was reduced from 89.1% to 40% and aflatoxin $B_2$, $G_1$ production increased with the laps of time. Especially garlic extract appeared to have a stimulatory effect on lipid accumulation on the contrary aflatoxin production.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.929-944
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• 2019

Many critical applications require accurate real-time human action recognition. However, there are many hurdles associated with capturing and pre-processing image data, calculating features, and classification because they consume significant resources for both storage and computation. To circumvent these hurdles, this paper presents a recognition machine learning (ML) based system model which uses reduced data structure features by projecting real 3D skeleton modality on virtual 2D space. The MMU VAAC dataset is used to test the proposed ML model. The results show a high accuracy rate of 97.88% which is only slightly lower than the accuracy when using the original 3D modality-based features but with a 75% reduction ratio from using RGB modality. These results motivate implementing the proposed recognition model on an embedded system platform in the future.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.443-451
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• 2023

Machine Learning has introduced many solutions in data science, but its application in IoT faces significant challenges, due to the limitations in memory size and processing capability of constrained devices. In this paper we design an automatic gamma radiation detection and identification embedded system that exploits the power of TinyML in a SiPM micro radiation sensor leveraging the Edge Impulse platform. The model is trained using real gamma source data enhanced by software augmentation algorithms. Tests show high accuracy in real time processing. This design has promising applications in general-purpose radiation detection and identification, nuclear safety, medical diagnosis and it is also amenable for deployment in small satellites.

• 핵의학기술
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• 제25권2호
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• pp.15-24
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• 2021

SPECT/CT는 보급 초기에 뛰어난 보정방법과 융합영상을 기반으로 한 정성적 기능이 주목받았고, 최근 동반진단치료(Theranostics)등의 도입으로 그 정량적 기능에 대한 관심과 활용이 증가되는 추세이다. PET/CT와 달리 SPECT/CT의 절대 정량화는 조준기의 종류, 검출기 회전과 같은 조건들이 영상획득과 재구성 방법 등에 까다로운 요소로 작용하고 있다. 따라서 본 연구에서는 SPECT/CT 촬영조건 중 투영상수와 투영상당 획득시간에 따른 총 획득시간(검사시간)의 증·감이 방사능농도 추정치에 미치는 영향을 알아보고자 한다. 부피 9,293 ml의 원통형 팬텀에 멸균수를 가득 채운 후 99mTcO4- 91.76 MBq를 희석하여 총 획득시간 600 sec(10 sec/frame × 120 frames, matrix size 128 × 128)의 조건으로 기준영상을 촬영하였고, 체적감도와 교정인자를 확인하였다. 기준영상을 중심으로 총 획득시간을 60(-90%), 150(-75%), 300(-50%), 450(-25%), 900(+50%), 1200(+100%) sec/frame으로 증·감시켜 비교영상을 획득하였고, 각 영상별 세부조건은 투영상당 획득시간(sec/frame)을 1.0, 2.5, 5.0, 7.5, 15.0, 20.0 sec/frame(투영상수 120frames 고정)로, 투영상수를 12, 30, 60, 90, 180, 240 frames(투영상당 획득시간 10 sec/frame 고정)로 설정하였다. 획득된 각 영상에서 관심체적을 통하여 측정한 계수를 바탕으로 정성적 평가로서 CNR(Contrast to Noise Ratio)의 변동률(%)을 확인하였고, 방사능농도 추정치의 변동률(%)을 통해서는 정량적 평가를 시행하였다. 이때 방사능농도 추정치(cps/ml)와 실제 방사능농도(Bq/ml)의 관계는 회복계수(RC_Recovery Coefficients)를 지표로 비교·분석하였다. 투영상수 변화에 따른 결과[CNR 변동률(%), 방사능농도 추정치 변동률(%), RC]는 총 획득시간 증감률(%) -90%에서 [-89.5%, +3.90%, 1.04], -75%에서 [-77.9%, +2.71%, 1.03], -50%에서 [-55.6%, +1.85%, 1.02], -25%에서 [-33.6%, +1.37%, 1.01], +50%에서 [+33.7%, +0.71%, 1.01], +100%에서 [+93.2%, +0.32%, 1.00]이었으며, 투영상당 획득시간 변화에 따른 결과는 총 획득시간 증감률(%)-90%에서 [-89.3%, -3.55%, 0.96], -75%에서 [-73.4%, -0.17%, 1.00], -50%에서 [-49.6%, -0.34%, 1.00], -25%에서 [-24.9%, 0.03%, 1.00], +50%에서 [+49.3%, -0.04%, 1.00], +100%에서 [+99.0%, +0.11%, 1.00]이었다. SPECT/CT에서 총 획득시간의 증·감에 따라 획득된 총 계수와 그에 따른 영상품질(CNR)은 비례하여 변화하는 양상을 보였지만, 절대 정량화를 통한 정량적 평가에서는 모든 실험조건에서 5% 미만(-3.55에서 +3.90%)의 변화를 보여 큰 영향을 받지 않고 정량적 정확성(RC 0.96에서 1.04)을 유지하였다. 검사시간의 증가보다는 단축을 우선하여 고려하였을 때 총 획득시간 감소는 정성적 기능에 있어서 기존에도 배제할 수 없었던 사항이지만 정량적 기능은 큰 손실 없이 적용 가능하여 임상적으로 실효성이 있다고 판단된다. 다만 총 획득시간의 증·감 시 동일한 검사시간이라면 투영상수의 변경보다는 투영상당 획득시간의 변경이 정성적, 정량적으로 조건변화에 따른 변동 폭이 적은 것으로 나타났다.

• Journal of Gastric Cancer
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• 제14권2호
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• pp.105-110
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• 2014

Purpose: The advantages of totally laparoscopic surgery in early gastric cancer (EGC) are unproven, and some concerns remain regarding the oncologic safety and technical difficulty. This study aimed to evaluate the technical feasibility and clinical benefits of totally laparoscopic distal gastrectomy (TLDG) for the treatment of gastric cancer compared with laparoscopy-assisted distal gastrectomy (LADG). Materials and Methods: A retrospective review of 211 patients who underwent either TLDG (n=134; 63.5%) or LADG (n=77; 36.5%) for EGC between April 2005 and October 2013 was performed. Clinicopathologic features and surgical outcomes were analyzed and compared between the groups. Results: The operative time in the TLDG group was significantly shorter than that in the LADG group (193 [range, 160~230] vs. 215 minutes [range, 170~255]) (P=0.021). The amount of blood loss during TLDG was estimated at 200 ml (range, 100~350 ml), which was significantly less than that during LADG, which was estimated at 400 ml (range, 400~700 ml) (P<0.001). The hospital stay in the TLDG group was shorter than that in the LADG group (7 vs. 8 days, P<0.001). One patient from each group underwent laparotomic conversion. Two patients in the TLDG group required reoperation: one for hemostasis after intraabdominal bleeding and 1 for repair of wound dehiscence at the umbilical port site. Conclusions: TLDG for distal EGC is a technically feasible and safe procedure when performed by a surgeon with sufficient experience in laparoscopic gastrectomy and might provide the benefits of reduced operating time and intraoperative blood lossand shorter convalescence compared with LADG.