• 열처리공학회지
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• 제36권2호
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• pp.69-76
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• 2023

In this study, we present a system for identifying equivalent grades of standardized wire rod steel based on alloy composition using machine learning techniques. The system comprises two models, one based on a supervised multi-class classification algorithm and the other based on unsupervised autoencoder algorithm. Our evaluation showed that the supervised model exhibited superior performance in terms of prediction stability and reliability of prediction results. This system provides a useful tool for non-experts seeking similar grades of steel based on alloy composition.

• 한국지능시스템학회논문지
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• 제23권3호
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• pp.262-267
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• 2013

The recognition of human emotional state is one of the most important components for efficient human-human and human- computer interaction. In this paper, four emotions such as fear, disgust, joy, and neutral was a main problem of classifying emotion recognition and an approach of visual-stimuli for eliciting emotion based on physiological signals of skin conductance (SC), skin temperature (SKT), and blood volume pulse (BVP) was used to design the experiment. In order to reach the goal of solving this problem, half-against-half (HAH) multi-class support vector machine (SVM) with Gaussian radial basis function (RBF) kernel was proposed showing the effective techniques to improve the accuracy rate of emotion classification. The experimental results proved that the proposed was an efficient method for solving the emotion recognition problems with the accuracy rate of 90% of neutral, 86.67% of joy, 85% of disgust, and 80% of fear.

• 대한원격탐사학회지
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• 제38권4호
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• pp.375-386
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• 2022

The city of Khartoum, the capital of Sudan, was heavily damaged by the flood of the Nile in 2020. Classification using satellite images can define the damaged area and help emergency response. As Synthetic Aperture Radar (SAR) uses microwave that can penetrate cloud, it is suitable to use in the flood study. In this study, Random Forest classifier, one of the supervised classification algorithms, was applied to the flood event in Khartoum with various sizes of the training dataset and number of images using Sentinel-1 SAR. To create a training dataset, we used unsupervised classification and visual inspection. Firstly, Random Forest was performed by reducing the size of each class of the training dataset, but no notable difference was found. Next, we performed Random Forest with various number of images. Accuracy became better as the number of images in creased, but converged to a maximum value when the dataset covers the duration from flood to the completion of drainage.

• 융합보안논문지
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• 제18권3호
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• pp.53-59
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• 2018

본 논문에서는 효율적인 사물 이미지 분류를 위한 계층적 이미지 분류 체계 방안에 대해 제안한다. 기존의 전체 이미지를 한 번에 분류하는 무 계층 이미지 분류에서는 상대적으로 유사한 모양을 가진 사물은 효율적으로 인식하지 못하는 모습을 보여줬다. 따라서 본 논문에서는 사물 이미지에 대해 계층적으로 분류를 시도하는 단계적 계층 구조에서의 이미지 분류 기법을 소개한다. 또한, 실제 시스템에 딥 러닝 이미지 분류가 적용되었을 때 발생할 수 있는 확장성에 대해서 고려하기 위해 확장성이 고려된 효율적인 클래스 구성 방식과 알고리즘도 소개한다. 이와 같은 방식은 상대적으로 유사한 형태를 보인 사물 이미지에 대해 더 높은 신뢰도로 이미지를 분류하는 것을 가능하게 한다.

• 전자공학회논문지SC
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• 제48권5호
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• pp.7-12
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• 2011

본 논문에서는 자료패턴을 분류하기에 적합한 특징을 추출하는 방법인, 클래스가 부가된 커널 주성분분석(class-augmented kernel principal component analysis)를 새로이 제안하였다. 특징추출에 널리 이용되는 부분공간 기법 중, 최근 제안된 클래스가 부가된 주성분분석(class-augmented principal component analysis)은 패턴 분류를 위한 특징을 추출하기 위해 이용되는 선형분류분석(linear discriminant analysis)등에 비해 정확한 특징을 계산상의 문제 없이 추출할 수 있는 기법이다. 그러나, 추출되는 특징은 입력의 선형조합으로 제한되어 자료에 따라 적절한 특징을 추출하기 어려운 경우가 발생한다. 이를 해결하기 위하여 클래스가 부가된 주성분분석에 커널 트릭을 적용하여 비선형 특징을 추출할 수 있는 새로운 부분공간 기법으로 확장하고, 실험을 통하여 성능을 평가하였다.

• Journal of Chest Surgery
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• 제28권9호
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• pp.822-828
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• 1995

This paper reports 15 native valve endocarditis cases had surgical operation in the past 10 years at the department of Cardiovascular and Thoracic Surgery, Chonbuk National University Hospital. In this study, 10 cases out of 15 were in class I or II by the New York Heart Association functional classification. None of the cases had a history of taking addictive drugs. Five cases were congenital heart disease, three cases were rheumatic heart disease and two cases were degenerative heart disease. Thus 10 cases had the underlying disease. All cases had antibiotics treatment for 3 to 6 weeks before operation. In the culture test, only four cases were positive in the blood culture and one case was positive in the excised valve culture. Organisms on blood and valve culture were Streptococcus epidermis, Streptococcus viridans, Staphylococcus aureus and Staphylococcus epidermidis. In the 10 cases without ventricular septal defect, the aortic valve was involved in four, mitral in four, both in two and involved valves in the 5 cases with ventricular septal defect were tricuspid in three, pulmonic in two. Eight cases had operation because they showed moderate congestive heart failure due to valvular insufficiency and vegetation with or without embolism. Seven cases had operation because they showed persistent or progressive congestive heart failure and/or uncontrolled infection. Five cases with ventricular septal defect underwent the closure of ventricular septal defect, vegetectomy and leaflet excision of the affected valves without valve replacement. In the cases without ventricular septal defect, the affected valves were replaced with St. Jude mechanical prosthesis. Postoperative complications were recurrent endocarditis in two, embolism in one, allergic vasculitis in two, spleen rupture in one and postpericardiotomy syndrome in one. At the first postoperative day, one case died of cerebral embolism. At the 11th postoperative month, one case died of recurrent endocarditis and paravalvular leakage in spite of a couple of aortic valve replacement. In the survived cases[13 cases in this study , all cases but one became class I or II by the New York Heart Association functional classification.

• 대한전자공학회논문지SP
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• 제40권3호
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• pp.203-216
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• 2003

In this paper a new feature extraction and target classification method is proposed for the recognition part of FLIR(Forwar Looking Infrared)-image-based ATR system. Proposed feature extraction method is "cluster(=set of classes)-based"version of previous fisherfaces method that is known by its robustness to illumination changes in face recognition. Expecially introduced class clustering and cluster-based projection method maximizes the performance of fisherfaces method. Proposed target image classification method is based on the mixture of experts model which consists of RBF-type experts and MLP-type gating networks. Mixture of experts model is well-suited with ATR system because it should recognizee various targets in complexed feature space by variously mixed conditions. In proposed classification method, one expert takes charge of one cluster and the separated structure with experts reduces the complexity of feature space and achieves more accurate local discrimination between classes. Proposed feature extraction and classification method showed distinguished performances in recognition test with customized. FLIR-vehicle-image database. Expecially robustness to pixelwise sensor noise and un-wanted intensity variations was verified by simulation.

• 대한치과교정학회지
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• 제21권2호
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• pp.457-468
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• 1991

This investigation was designed to categorize Angle's class III malocclusion groups through analyzing horizontal and vertical components of craniofacial skeleton in Angle's class III malocclusion. The material selected for this study consisted in standard lateral cephalogram of one hundred and fifty five children, seventy four boys and eighty one girls, aged 6 through 15 years, having Angle's class III malocclusion. On the basis of findings of this study, the following results were obtained. 1. In horizontal skeletal classifications,16 groups were classified FMN-A-B, SE-FMN-A according to the Ba-SE-Me, Ba-SE/R. 2. The sequences that have relatively high frequency are as follow; a) Horizontal Group l b) Horizontal Group 3 c) Horizontal Group 5 d) Horizontal Group 9 e) Horizontal Group 4 3. In vertical skeletal classification, 8 groups were classified according to the PMV/PP, PMV/OP, PMV/MP. 4. The sequences that relatively high are as follows; a) Vertical Group 1 b) Vertical Group 3 c) Vertical Group 4 d) Vertical Group 8.

• Journal of Chest Surgery
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• 제28권9호
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• pp.811-816
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• 1995

Repairs of atrial septal defect utilizing cardiopulmonary bypass were performed in 50 adults, ranging age from 16 to 53 years, since April 1986 up to October 1994. They occupied 38.8% of all adult congenital heart disease operated in the same period. Preoperatively, 16 patients were functional class II, 12 patients class III and 4 patients class IV[New York Heart Association Classification , respectively. Five patients combined with atrial fibrillation and the remainders revealed regular sinus rhythm. Cardiac catheterizations were performed in 43 out of 50 patients, and revealed a systolic pulmonary arterial pressure in excess of 51 mmHg in 4 patients but none had reversed shunt. 40 patients[80% were repaired with patch closure and remainings were repaired with direct closure. 49 patients were followed up for 2 months up to 102 months[average 55 months . A comparison of the preoperative and postoperative functional class demonstrated a mean decrease of one NYHA functional level[2.5$\pm$0.63 to 1.4$\pm$0.56 . There was no operative mortality. One patient died during the follow-up period and the death was unrelated to heart disease. Operative treatment is indicated for repair of atrial septal defect with left to right shunt in the adult patient and a considerable clinical improvement can be anticipitated with low mortality.

• Journal of Chest Surgery
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• 제26권7호
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• pp.521-525
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• 1993

Sixty-three patients who underwent open mitral commissurotomy at Sejong General Hospital during last 10 years from the August, 1983 to June, 1993 were reviewed There were fifty-one women and twelve men, and the mean age was 34.2 years. According to the NYHA classification, the distribution of patient preoperatively was as follows: class I, 5 patients ; class II, 26 patients ; class III, 30 patients ; class IV, 2 patients, and mean duration of symptome was 4.5 years. The mean mitral valvular area measured with echocardiogram preoperatively was 0.92cm2. All patients underwent open mitral commissurotomy and 41 patients required additional procedures for relief of subvalvular stenosis or other valvular disease. There were no operative death. 63 patients had three different types of mitral stenosis : type I, mobile cusps without subvalvular change [21 patients] ; typeII, thickened cusps with subvalvular change [34 patients] ; type III, rigid cusps with severe subvalvular change [8 patients]. The valvular calcification was seen in 11 patients [17%] and 15 patients [24%] had left atrial thrombus. The duration of follow-up was from 1 month to 168 months [mean, 39.6 months] and there were no late death. Six patients required reoperation and one patient had embolic episode. Conclusively,the open mitral commissurotomy represents a safe surgical precedure for treating mitral stenosis, allowing a complete removal of atrial thrombosis if present, and even when associated with subvalvular changes.