• Annals of Clinical Neurophysiology
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• 제2권1호
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• pp.13-20
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• 2000

Background and Objective : Visual evoked potentials(VEPs) is considered to be a reliable diagnostic procedure for examining patients with anterior visual pathways. Some abnormalities in the recordings on monocular stimulation have been said to indicate retrochiasmal lesion, but less consistent results have been reported. This study is to evaluate the positive predictability of VEP for the detection of retrochiasmal lesion. Methods : We reviewed VEPs that could be interpreted as indicative of a retrochiasmal lesions, based on amplitude or latency asymmetry recorded on the left(O1) and right(O2) occipital regions. Bilateral absent VEPs on both recording(O1 and O2) without evidence of prechiasmal lesion were included. During 5 years, we identified 31 patients who met the above criteria and who had undergone magnetic resonance imaging(MRI) of brain(one patient underwent computerized tomography). Twenty three patients underwent pattern reversal VEPs and others underwent flash goggle VEPs. Results : Brain imagings were abnormal in 29 and were normal in 2. Of the 29 abnormal scans, lesions in posterior visual pathway were detected in 21 scans(predictive value=68%). The predictive value was not significantly different between flash goggle VEP(75%) and pattern reversal VEP(68%). The predictive value was higher in patient with visual field defect(100%) than those without visual field defect(25%). The pathologic nature of lesion also showed close relations to the predictive value. VEPs is usually paradoxically lateralized(78%), but not in all patients. Conclusion : VEPs abnormalities suggesting retrochiasmal lesion were usually corresponded with brain MRI findings. Diagnostic reliability could be increased when considering the visual field defect and nature of lesion. Therefore, the authors suggest that VEPs studies could be useful in evaluating the patients with the retrochismal lesion.

• Asian Pacific Journal of Cancer Prevention
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• 제16권16호
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• pp.7381-7384
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• 2015

This study was conducted to 1206 women who had cervical cancer screening at Chonburi Cancer Hospital. The spilt-sample study aimed to compare the efficacy of abnormal cervical cells detection between liquid-based cytology (LBC) and conventional cytology (CC). The collection of cervical cells was performed by broom and directly smeared on a glass slide for CC then the rest of specimen was prepared for LBC. All slides were evaluated and classified by The Bethesda System. The results of the two cytological tests were compared to the gold standard. The LBC smear significantly decreased inflammatory cell and thick smear on slides. These two techniques were not difference in detection rate of abnormal cytology and had high cytological diagnostic agreement of 95.7%. The histologic diagnosis of cervical tissue was used as the gold standard in 103 cases. Sensitivity, specificity, positive predictive value, negative predictive value, false positive, false negative and accuracy of LBC at ASC-US cut off were 81.4, 75.0, 70.0, 84.9, 25.0, 18.6 and 77.7%, respectively. CC had higher false positive and false negative than LBC. LBC had shown higher sensitivity, specificity, PPV, NPV and accuracy than CC but no statistical significance. In conclusion, LBC method can improve specimen quality, more sensitive, specific and accurate at ASC-US cut off and as effective as CC in detecting cervical epithelial cell abnormalities.

• 한국가축번식학회지
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• 제7권2호
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• pp.72-85
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• 1983

This presentation firstly is discussed the characteristics of estrus, the time of first postpartum estrus, and the relative accurate of various estrus detection aids and secondly discussed the abnormalities of estrus and ovarian function and its control by treatment of exogenous hormones in cattle and pig. Longer estrus cycles as well as the shorter than 18 day cycles showed the lowered conception rates as compared to the normal cycles of 18 to 25 days. Other characteristics of est겨s such as duration of estrus, intensity of estrus and time of estrus are reviewed to affect fertility. The first postpartum ovulation and estrus in cows usually occurs about 20 to 30 days and 40 to 50 days after parturition, respectively. Irregularities in estrus cycle length have been conducted during early postpartum period. In sows, weaning is followed by ovulation and estrus although there is some individual variation. The most common method of estrus detection is direct visual observation on standing estrus behavior, but various aids of estrus detection have been empolyed with varying degree of effectiveness. The results from heat detector devices are about as accurate as twice-daily observation(about 90%). The abnormal estrus can be classified into three types; irregular or continuous estrus, silent estrus and anestrus. Cystic ovarian disease, follicular cysts and luteal cysts, is a serious cause of reproductive failure in cattle and pig. The follicular cysts are much more common than luteal cysts and the incidence of ovarian cysts in dairy cattle is higher than beef cattle and pig. The occurrences of ovarian cysts have been closely associated with levels of milk production, stages of postpartum period, nutritional levels and seasons. The luteal cysts and persistent corpora lutea are responsive to the luteolytic effects of the recently synthetic analogues of PGF2$\alpha$ in cows and sows and recently GnRH or LH-RH has been successfully used as a treatment for cows and sows with ovarian follicular cysts.

• Advances in pediatric surgery
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• 제3권1호
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• pp.15-23
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• 1997

During a 6-year period, from January 1990 to December 1995, 101 neonates with congenital anomalies were admitted to the division of Pediatric Surgery of Youngdong Severance Hospital. All of them had prenatal screening more than once with ultrasound. Fifty eight of them had prenatally detectable anomalies by ultrasonography. However abnormalities were prenatally detected in 24 neonates(41%). The detection rate was 70% in patientws who had the prenatal screening at our hospital, whereas, the rate was 24% when it was performed at other medical facilities. Duodenal and jejuno-ileal atresia showed the highest detection rate(86%) followed by abdominal mass. Esophageal atresia was suggested by maternal polyhydramnios in 3 patients (25%). Only one patient with diaphragmatic hernia(1.75%) was prenatally detected and none with gastroschisis. The mean interval from birth to operation was 32 hours in the prenatally detected patients and 50 hours in the non detected. The complication rate and the mortality after emergency operation were 20% and 7% in the detected group, and 58% and 23% in the nondetected, respectively. The average period of the hospitalization was 20 days in the detected group and 39 days in the nondetected. We conclude that the prenatal detection of anomalies is necessary to ensure adequate care for the mothers and the babies with congenital anomalies. This includes early transfer, timing of optimal delivery and operation.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제12권2호
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• pp.137-142
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• 2012

The temporal subtraction technique as one of computer aided diagnosis has been introduced in medical fields to enhance the interval changes such as formation of new lesions and changes in existing abnormalities on deference image. With the temporal subtraction technique radiologists can easily detect lung nodules on visual screening. Until now, two-dimensional temporal subtraction imaging technique has been introduced for the clinical test. We have developed new temporal subtraction method to remove the subtraction artifacts which is caused by mis-registration on temporal subtraction images of lungs on MDCT images. In this paper, we propose a new computer aided diagnosis scheme for automatic enhancing the lung nodules from the temporal subtraction of thoracic MDCT images. At first, the candidates regions included nodules are detected by the multiple threshold technique in terms of the pixel value on the temporal subtraction images. Then, a rule-base method and artificial neural networks is utilized to remove the false positives of nodule candidates which is obtained temporal subtraction images. We have applied our detection of lung nodules to 30 thoracic MDCT image sets including lung nodules. With the detection method, satisfactory experimental results are obtained. Some experimental results are shown with discussion.

• 정보보호학회논문지
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• 제30권5호
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• pp.957-966
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• 2020

최근 산업기밀보호센터의 통계에 의하면 국내 기밀유출 사고의 경우 전·현직 직원에 의해 기업기밀유출의 약 80%를 차지하고 이러한 내부자에 의한 정보유출 사고의 대다수가 허술한 보안 관리체계와 정보유출 탐지기술의 이유로 발생하고 있다. 내부자의 기밀유출을 차단하는 업무는 기업보안 부문에서 매우 중요한 문제이지만 기존의 많은 연구들은 내부자에 의한 유출위협보다는 외부 위협에 의한 침입에 대응하는데 초점이 맞추어져 있다. 따라서 본 논문에서는 기업 내에서 발생하는 다양한 비정상 행위를 효과적이고 효율적으로 탐지하기 위해 내부정보 유출 시나리오를 설계하고 시나리오에서 도출 된 유출 징후의 핵심 위험지표를 데이터 분석(Data analytics)함 으로써 정교하지만 신속하게 유출행위를 탐지하는 모형을 제시하고자 한다.

• 한국산학기술학회논문지
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• 제22권3호
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• pp.20-29
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• 2021

4차산업혁명 시대에는 대량의 데이터를 학습하여 예측과 분류의 정확성을 향상시킬 수 있는 인공지능의 활용이 핵심적이다. 그러나, 기존 이상탐지를 위한 방법은 제한된 데이터를 다루는 전통적인 통계 방법에 의존하고 있어, 정확한 이상탐지가 어렵다. 그러므로, 본 연구는 인공지능 기반 이상탐지 방법을 제시하여 예측 정확도를 높이고, 새로운 데이터 패턴을 정의하는 것을 목적으로 한다. 특히, 자동차의 경우 공회전 기간의 센서 데이터가 이상 탐지에 활용될 수 있다는 관점에서 데이터를 수집하고 분석하였다. 이를 위해, 예측 모델에 입력되는 데이터의 적정 시간 길이를 결정하고, 공회전 기간 데이터와 전체 운행 데이터의 분석 결과를 비교하며, 다양한 센서 데이터 조합에 의한 최적 예측 방법을 도출하였다. 또한, 인공지능 방법으로 선택된 CNN의 예측 정확성을 검증하기 위해 LSTM 결과와 비교하였다. 분석 결과, 공회전 데이터를 이용하고, 공회전 기간보다 1.5배 많은 기간의 데이터를 이용하며 LSTM보다는 CNN을 활용하는 것이 더 좋은 예측결과를 보였다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권5호
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• pp.2051-2055
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• 2014

Background: To evaluate the performance of Siriraj liquid-based cytology (LBC) for cervical neoplasia screening after increasing use of this technology. Materials and Methods: Cytological reports of 103,057 Siriraj-LBC specimens obtained in 2007-2009 were compared with those of 23,676 specimens obtained in 2006. Results: Comparing with the year 2006, the 2007-2009 patients were slightly older ($43.4{\pm}12.yr$ vs $42.7{\pm}12.2yr$, p <0.001), and their specimens had much lower proportion of unsatisfactory slides (OR=0.06, 95%CI 0.04-0.09) with comparable detection rates (3.96% vs 3.70%, p=0.052) but different proportions of various cytological abnormalities (p<0.001). The 2007-2009 Siriraj-LBC had a negative predictive value (NPV) for cervical intraepithelial neoplasia 2+ (CIN2+) of 97.6% and an overall positive predictive value (PPV) of 43.9%. The PPV for CIN2+ varied with types of abnormal cytology, from 13.7% to 93.8% in atypical squamous cells of undetermined significance (ASCUS), low-grade squamous intraepithelial lesion (LSIL), atypical squamous cells cannot exclude HSIL (ASC-H), high-grade squamous intraepithelial lesion (HSIL), atypical glandular cells (AGC), to squamous cell carcinoma (SCC), respectively. The PPVs for CIN2+ in ASCUS and LSIL were comparable, but the PPV for CIN1 was higher for LSIL than for ASCUS (41.63% vs 16.32%). Conclusions: Siriraj-LBC has demonstrated a stable detection rate and NPV for CIN2+ of >95% since the first year of use. The comparable PPVs for CIN2+ of ASCUS and LSIL suggests that these two conditions may undergo similar management; other cytological abnormalities need immediate evaluation.

• 한국멀티미디어학회논문지
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• 제16권6호
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• pp.678-688
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• 2013

단일 공격과 달리 DDoS 공격들은 네트워크에 분산된 봇넷이 동시에 타겟 서버에 공격을 개시한다. 이 경우 타겟 서버에서는 정상적인 사용자의 편의를 고려해야 하기 때문에 DDoS로 간주되는 패킷에 대하여 접속거부 조치를 취하기 어려운 점이 있다. 이를 고려하여 본 논문에서는 사용자 네트워크단위로 DDoS 공격을 탐지하고 네트워크 관리자가 조치를 취할 수 있도록 하여 전체적으로 봇넷의 규모를 줄여서 타겟 서버의 부담을 줄일 수 있는 DDoS 봇넷 탐지 시스템을 구현 하였다. 본 논문에서 제안한 DDoS 봇넷 탐지 시스템은 공격 트래픽의 시간 단위 흐름을 분석하고 수집한 이상상태에 대한 데이터베이스를 바탕으로 공격을 탐지 하도록 프로그램을 구현하였다. 그리고 패킷들의 평균개수와 표준편차를 이용하여 현재 트래픽의 임계치(Threshold)를 계산하고 이 임계치를 이용하여 DDoS 공격 여부를 판단하였다. 공격의 대상이 되는 서버를 중심으로 이루어졌던 봇넷 탐지 단위를 DDoS 봇에 감지된 공격 모듈이 속한 네트워크 단위 탐지로 전환함으로써 DDoS 공격에 대한 적극적인 방어의 개념을 고려해 볼 수 있었다. 따라서 DDoS와 DoS 공격의 차이점이라 할 수 있는 대규모 트래픽 흐름을 사전에 네트워크 관리자가 차단함으로써 봇넷의 규모를 축소시킬 수 있다. 또한, 라우터 장비 이하의 네트워크 통신에서 트래픽 공격을 사전에 차단할 수 있다면 타겟 서버의 부담뿐만 아니라 WAN 통신에서 라우터의 네트워크 부하를 상당부분 감소시킬 수 있는 효과를 얻을 수 있을 것으로 기대한다.

• 인터넷정보학회논문지
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• 제25권1호
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• pp.109-121
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• 2024

섬유, 자동차와 같은 여러 제조 공정에서 설비가 고장이 나 멈추게 되면 기계가 작동하지 않게 되고 이는 기업의 시간적, 금전적 손실로 이어진다. 따라서 설비의 고장이 발생하기 전, 고장을 예측하여 정비할 수 있도록 설비의 이상을 사전에 탐지하는 것이 중요하다. 대부분의 설비 고장 원인은 설비의 필수 부품인 베어링의 고장으로, 베어링의 고장을 진단하는 것은 설비예지보전 연구의 핵심이기도 하다. 본 논문에서는 베어링의 진동 신호를 분석하여 SWT-SVD 전처리 알고리즘을 제안하고 이를 시계열 이상탐지 모델 네트워크 중 하나인 어노멀리 트랜스포머에 적용하여 베어링 이상탐지 모델을 구현한다. 제조공정의 베어링 진동신호는 실시간으로 센서값들의 이력이 작성되어 노이즈가 존재하므로, 이를 줄이기 위해 본 연구에서는 정상 웨이블릿 변환(Stationary Wavelet Transform)을 사용하여 주파수 성분을 추출하고, 특이값 분해(Singular Value Decomposition) 알고리즘을 통해 유의미한 특징들을 추출하는 전처리를 진행한다. 제안하는 SWT-SVD 전처리 방법을 적용한 베어링 이상탐지 모델 실험을 위해 IEEE PHM학회에서 제공하는 PHM-2012-Challenge 데이터 세트를 활용하였으며, 실험 결과는 0.98의 정확도와 0.97의 F1-Score로 우수한 성능을 보였다. 추가로, 성능 향상을 입증하기 위해 선행 연구들과 성능 비교를 진행한다. 비교 실험을 통해 제안한 전처리 방법이 기존의 전처리보다 높은 성능을 보임을 확인하였다.