효율적인 모델 학습을 위한 심층 특징의 평균값을 활용한 의미 있는 비디오 프레임 추출 기법

윤혁(Yoon, Hyeok),김영기(Kim, Young-Gi),한지형(Han, Ji-Hyeong) 한국방송·미디어공학회 2021 한국방송공학회 학술발표대회 논문집 Vol.2021 No.6

최근 정보통신의 발달과 함께 인터넷에 접속하는 사용자 수와 그에 따른 비디오 데이터의 전송량이 늘어나는 추세이다. 이렇게 늘어나는 많은 비디오 데이터를 관리하고 분석하기 위해서 최근에는 딥 러닝 기법을 많이 활용하게 된다. 일반적으로 비디오 데이터에 딥 러닝 모델을 학습할 때 컴퓨터 자원의 한계로 인해 전체 비디오 프레임에서 균등한 간격 또는 무작위로 프레임을 선택하는 방법을 많이 사용한다. 하지만 학습에 사용되는 비디오 데이터는 항상 시간 축에 따라 같은 문맥을 담고 있는 Trimmed 비디오라고 가정할 수가 없다. 만약 같지 않은 문맥을 지닌 Untrimmed 비디오에서 균등한 간격 또는 무작위로 프레임을 선택해서 사용하게 된다면 비디오의 범주와 관련이 없는 프레임이 샘플링 될 가능성이 있기 때문에 모델의 학습 및 최적화에 전혀 도움이 되지 않는다. 이를 해결하기 위해 우리는 각 비디오 프레임에서 심층 특징을 추출하여 평균값을 계산하고 이와 각 추출된 심층 특징들과 코사인 유사도를 계산해서 얻은 유사도 점수를 바탕으로 Untrimmed 비디오에서 의미 있는 비디오 프레임을 추출하는 기법을 제안한다. 그리고 Untrimmed 비디오로 구성된 데이터셋으로 유명한 ActivityNet 데이터셋에 대해서 대표적인 2가지 프레임 샘플링 방식(균등한 간격, 무작위)과 비교하여 우리가 제안하는 기법이 Untrimmed 비디오에서 효과적으로 비디오의 범주에 해당하는 의미 있는 프레임 추출이 가능함을 보일 것이다. 우리가 실험에 사용한 코드는 https://github.com/titania7777/VideoFrameSampler에서 확인할 수 있다.

Vari-METRIC을 개선한 다단계 재고모형의 효과측정

윤혁(Hyouk Yoon),이상진(Sangjin Lee) 한국경영과학회 2011 經營 科學 Vol.28 No.1

In the Multi-Echelon maintenance environment, METRIC(Multi-Echelon Technique for Repairable Item Control) has been used in several different inventory level selection models, such as MOD-METRIC, Vari-METRIC, and Dyna- ETRIC. While this model's logic is easy to be implemented, a critical assumption of infinite maintenance capacity would deteriorate actual values, especially Expected Back Order(EBO)s for each item. To improve the accuracy of EBO, we develop two models using simulation and queueing theory that calculates EBO considering finite capacity. The result of our numerical example shows that the expected backorder from our model is much closer to the true value than the one from Vari-METRIC. The queueing model is preferable to the simulation model regarding the computational time.

Phase-type 수리시간을 갖는 장비의 적정 예비장비수 결정

윤혁(Hyouk Yoon),이상진(Sang-jin Lee) 한국경영과학회 2009 한국경영과학회 학술대회논문집 Vol.2009 No.5

The probability distribution of a repair process should be determine to choose the optimal spare level of a machine in a queueing model. Though most machines have a multi-step repair process, previous studies use the exponential distribution for the multi-step repair process. But the PH distribution is more appropriate for it. This research utilizes a PH distribution on a queueing model and solves it with MGM(Matrix Geometric Method). In conclusion, the optimal spare level was obtained using a PH distribution and the difference between PH and exponential distribution was shown.

Phase-type 수리시간을 갖는 무기체계의 적정예비품수 결정

윤혁(Hyouk Yoon),이상진(Sangjin Lee) 한국경영과학회 2009 經營 科學 Vol.26 No.3

The probability distribution of the repair process should be determined to choose the optimal spare level of a weapon system with a queueing model. Though most weapon systems have a multi-step repair process, previous studies use the exponential distribution for the multi-step repair process. But the PH distribution is more appropriate for this case. We utilize the PH distribution on a queueing model and solve it with MGM(Matrix Geometric Method). We derive the optimal spare level using the PH distribution and show the difference of results between the PH and exponential distribution.

Phase-type 수리시간을 갖는 장비의 적정 예비장비수 결정

윤혁(Hyouk Yoon),이상진(Sang-jin Lee) 대한산업공학회 2009 대한산업공학회 춘계학술대회논문집 Vol.2009 No.5

The probability distribution of a repair process should be determine to choose the optimal spare level of a machine in a queueing model. Though most machines have a multi-step repair process, previous studies use the exponential distribution for the multi-step repair process. But the PH distribution is more appropriate for it. This research utilizes a PH distribution on a queueing model and solves it with MGM(Matrix Geometric Method). In conclusion, the optimal spare level was obtained using a PH distribution and the difference between PH and exponential distribution was shown.

불확실한 환경에서의 이미지 분류 성능 향상을 위한 Mix Channel Split 데이터 증강 기법

윤혁(Hyeok Yoon),강수한(Soohan Kang),한지형(Ji-Hyeong Han) Korean Institute of Information Scientists and Eng 2020 정보과학회논문지 Vol.47 No.6

We propose a new data augmentation method that works by separating the RGB channels of an image to improve image classification ability in uncertain environments. Many data augmentation methods, using technique such as flipping and cropping, have been used to improve the image classification ability of models. while these data augmentation methods have been effective in improving image classification, they have unperformed in uncertain conditions. To solve this problem, we propose the ChannelSplit that separates and reassembles the RGB channels of an image, along with the Mix ChannelSplit, that adopts the concept of MixUp[1,2] to express more diversity. In this paper, the proposed ChannelSplit and Mix ChannelSplit are called ChannelAug because they only utilize channels and do not perform any other image operations. Also, we compare ChannelAug to other image augmentation methods to prove it enhances robustness and uncertainty measures on image classification.

복부 팽만 환자에서 리팍시민의 임상적 효과

윤기철 ( Kichul Yoon ),김나영 ( Nayoung Kim ),이주엽 ( Ju Yup Lee ),오동현 ( Dong Hyun Oh ),서아영 ( A Young Seo ),윤창용 ( Chang Yong Yun ),윤혁 ( Hyuk Yoon ),신철민 ( Cheol Min Shin ),박영수 ( Young Soo Park ),이동호 ( Dong Ho 대한소화기학회 2018 대한소화기학회지 Vol.72 No.3

Background/Aims: Abdominal bloating is a troublesome complaint due to insufficient understanding of the pathophysiology. The aim of this study was to evaluate the efficacy of rifaximin in reducing bloating associated with functional gastrointestinal disorders (FGIDs). Methods: A total of 63 patients were treated with rifaximin for FGIDs with bloating or gas-related symptoms between 2007 and 2013 at Seoul National University Bundang Hospital. Rifaximin was administered at a dose between 800 mg/day and 1,200 mg/day for 5 to 14 days. The proportion of patients who had adequate relief of global FGID symptoms and FGID-related bloating was retrospectively assessed. The response was recorded when the symptoms were reduced by at least 50% at the follow-up after treatment cessation. Results: The mean age was 56.8±14.2 years; 49.2% were females. According to Rome III criteria, 20.6% (13/63) had irritable bowel syndrome (IBS) with constipation, 9.5% (6/63) had IBS with diarrhea, 4.8% (3/63) had mixed IBS, 23.8% (15/63) had functional dyspepsia, and 12.7% (8/63) had functional bloating. Of the 51 subjects who were followed-up, 30 (58.8%) had adequate relief of global FGID symptoms and 26 (51.0%) experienced improvement of abdominal bloating after rifaximin treatment. The proportion of female was slightly higher in non-response group than in the response group (60.0% vs. 34.6%, p=0.069). Otherwise, there was no difference between the two groups. Conclusions: Despite the limitations of this retrospective study, our data confirms that rifaximin may be beneficial for abdominal bloating. Further prospective clinical trial with a larger cohort is needed. (Korean J Gastroenterol 2018;72:121-127)

Improving Program Efficiency of 3D NAND Cell Structure Based on Artificial Neural Network

Kyeongrae Cho(조경래),Hyeok Yun(윤혁),Hyundong Jang(장현동),Kihoon Nam(남기훈),Chanyang Park(박찬양),Jun-Sik Yoon(윤준식),Hyun-Chul Choi(최현철),Rock-Hyun Baek(백록현) 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.6

3D NAND Flash cell structures were optimized to improve program efficiency using fully-calibrated TCAD and machine learning (ML) techniques. Program efficiency is determined by the number of charges trapped in the charge trap nitride (CTN) layer at the given program voltage step. Usually, a higher and constant Incremental Step Pulse Programming (ISPP) slope is suitable for various program voltage levels. Using a neural network, we trained a forward model of the relationship between NAND electrical characteristics and structure parameters, then designed a backward model to optimize NAND Flash cell structure having excellent program efficiency. Finally, we validated the optimized NAND structure with TCAD simulation and compared it with hardware reference data.

Correlations Among Endoscopic, Histologic and Serologic Diagnoses for the Assessment of Atrophic Gastritis

이주엽,김나영,이혜승,Jane C Oh,권용환,최윤진,Kichul Yoon,Jae Jin Hwang,Hyun Joo Lee,AeRa Lee,정연상,조현진,윤혁,신철민,박영수,이동호 대한암예방학회 2014 Journal of cancer prevention Vol.19 No.1

Atrophic gastritis is a precancerous condition, which can be diagnosed by several methods. However, there is no consensus for the standard method. The aim of this study was to evaluate the correlations among endoscopic, histologic, and serologic findings for the diagnosis of atrophic gastritis. Methods: From March 2003 to August 2013, a total of 2,558 subjects were enrolled. Endoscopic atrophic gastritis was graded by Kimura-Takemoto classification and histological atrophic gastritis was assessed by updated Sydney system. Serological assessment of atrophic gastritis was based on serum pepsinogen test. Results: The serum pepsinogen I/II ratio showed a significant decreasing nature when the extent of atrophy increased (R2=0.837, P<0.001) and the cut-off value for distinguishing between presence and absence of endoscopic atrophic gastritis was 3.2. The serum pepsinogen I and pepsinogen I/II ratio were significantly lower when the histological atrophic gastritis progressed and the cut-off value was 3.0 for a diagnosis of histological atrophic gastritis. A significant correlation between endoscopic and histological atrophic gastritis was noted and the sensitivity and specificity of endoscopic diagnosis were 65.9% and 58.0% for antrum, 71.3% and 53.7% for corpus, respectively. Conclusions: The endoscopic, histological, and serological atrophic gastritis showed relatively good correlations. However, as these three methods have a limitation, a multifactorial assessment might be needed to ameliorate the diagnostic accuracy of atrophic gastritis.

위식도 역류 질환의 유무에 따른 비결핵성 항산균 폐 질환의 유병률

강재빈 ( Jae Bin Kang ),이동호 ( Dong Ho Lee ),권수훈 ( Soo Hoon Kwon ),김나영 ( Nayoung Kim ),박영수 ( Young Soo Park ),윤혁 ( Hyuk Yoon ),신철민 ( Cheol Min Shin ),최윤진 ( Yoon Jin Choi ) 대한소화기학회 2018 대한소화기학회지 Vol.71 No.1

목적: 위식도 역류 질환 및 역류성 식도염은 위산이나 위 내용물의 식도 역류로 인한 불편감과 이로 인한 합병증을 총칭하는 용어로, 이 질환은 기관지 천식, 만성 기관지염, 기관지 확장 등의 여러 폐 질환과 연관이 있다는 것이 여러 연구에서 밝혀지고 있다. 위식도 역류증 환자에서 보이는 위산의 반복적인 흡인은 기관지의 만성 염증을 일으키고, 이로 인해 기관지 상피의 정상적인 점막방어기전이 파괴될 수 있다. 따라서 이들은 정상인에 비해 비결핵성 항산균 폐 질환이 더 많이 발생할 것이라고 가정하였다. 이 연구에서 저자들은 비결핵성 항산균 폐 질환이 있는 환자에서 내시경적 변화를 보이는 역류성 식도염의 유병률을 조사하였고, 또한 이를 일반 대조군에서의 역류성 식도염의 유병률과 비교하였다. 대상 및 방법: 2011년 1월부터 2015년 12월까지 본원에서 진단된 비결핵성 항산균 폐 질환 환자 중 본원에서 건강검진으로 상부위장관 내시경을 받은 93명을 대상으로 하였다. 이에 대한 대조군은 2008년 Lee 등8이 대한민국에서 건강검진 환자를 대상으로 한 일반 인구집단에서의 역류성 식도염의 유병률을 조사한 다기관 연구를 참조하였다. 결과: 총 93명의 비결핵성 항산균 폐 질환 환자 중 미소변화형 식도염의 비율은 29.0%로 대조군의 11.9%에 비해 더 높았으며, 이는 통계적으로 유의하였다. 결론: 역류성 식도염이 있는 환자는 만성적인 위산의 역류로 인한 기관지 점막의 파괴로 고유의 점막 방어막이 소실되어 역류성 식도염이 없는 집단에 비해 비결핵성 항산균 폐 질환의 유병률이 높아질 수 있으며, 앞으로 좀 더 큰 규모의 연구를 통해 이에 대한 검증이 필요하겠다. Background/Aims: Gastrointestinal reflux disease (GERD) is defined as 'a condition that develops when the reflux of stomach contents causes troublesome symptoms and/or complications'. It is associated with various lung diseases, including bronchial asthma, chronic bronchitis, and bronchiectasis. GERD may also affect nontuberculous mycobacterial (NTM) lung disease. We presumed that the normal mucosal barrier of the bronchial epithelium is broken due to the aspiration of gastric juice and consequent chronic bronchial inflammation. This study investigated the prevalence of GERD in accordance with the presence or absence of NTM lung disease and analyzed the difference. Methods: We screened patients with NTM lung disease in this hospital between January 2011 and December 2015. Among these patients, gastroscopic examinations as a health check-up were performed on 93 patients. We obtained the prevalence of Reflux esophagitis (RE) in patients with NTM and compared it with the prevalence of RE in the normal control subjects. Results: Among 93 patients with NTM, patients without RE was 66.7% (62/93). RE-minimal change was diagnosed in 29.0% (27/93), and RE LA-A was diagnosed in 4.3% (4/93). Comparing the prevalence of RE minimal change, 29.0% (27/93) had NTM and 11.9% (3043/25536) did not have NTM. This was statistically significant. Conclusions: We showed a greater prevalence of RE minimal change in patients with NTM than those without NTM with statistical significance. (Korean J Gastroenterol 2018;71:18-23)