• 정보과학회 논문지
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• 제42권12호
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• pp.1535-1543
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• 2015

뇌-컴퓨터 인터페이스는 사용자의 뇌전도(Electroencephalogram: EEG)를 획득하여 생각만으로 기계를 제어하거나 신체장애를 가진 사람에게 손 또는 발과 같은 신체를 대신하여 의사 전달 수단으로 사용될 수 있다. 본 논문에서는 동작 상상 EEG를 분류하기 위해 Sub-Band Common Spatial Pattern(SBCSP)를 기반으로 필터 선택을 하지 않는 특징 추출 방법에 대해 연구한다. 4~40Hz의 동작 상상 신호를 4Hz 대역마다 나눈 9개의 서브 밴드에 각각 CSP를 적용한다. 이후 Fisher's Linear Discriminant(FLD)를 사용하여 도출된 값들을 결합한 FLD 점수 벡터에 차원 축소를 위한 Principal Component Analysis(PCA)를 적용하여 클래스 구분을 위한 최적의 평면에 특징을 투영한다. 데이터베이스는 BCI CompetitionIII dataset IVa(2 클래스: 오른손 다리)를 이용하며, 추출된 특징은 Least Squares Support Vector Machine(LS-SVM)의 입력으로 사용된다. 제안된 방법의 성능은 $10{\times}10$ fold cross-validation을 이용하여 분류 정확도로 나타낸다. 본 논문에서 제안하는 방법은 피험자 'aa', 'al', 'av', 'aw', 'ay'에 대하여 각각 $85.29{\pm}0.93%$, $95.43{\pm}0.57%$, $72.57{\pm}2.37%$, $91.82{\pm}1.38%$, $93.50{\pm}0.69%$의 분류 정확도를 보였다.

• Korean Journal of Radiology
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• 제22권3호
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• pp.464-475
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• 2021

Objective: This study aimed to evaluate the tumor doubling time of invasive lung adenocarcinoma according to the International Association of the Study for Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) histologic classification. Materials and Methods: Among the 2905 patients with surgically resected lung adenocarcinoma, we retrospectively included 172 patients (mean age, 65.6 ± 9.0 years) who had paired thin-section non-contrast chest computed tomography (CT) scans at least 84 days apart with the same CT parameters, along with 10 patients with squamous cell carcinoma (mean age, 70.9 ± 7.4 years) for comparison. Three-dimensional semiautomatic segmentation of nodules was performed to calculate the volume doubling time (VDT), mass doubling time (MDT), and specific growth rate (SGR) of volume and mass. Multivariate linear regression, one-way analysis of variance, and receiver operating characteristic curve analyses were performed. Results: The median VDT and MDT of lung cancers were as follows: acinar, 603.2 and 639.5 days; lepidic, 1140.6 and 970.1 days; solid/micropapillary, 232.7 and 221.8 days; papillary, 599.0 and 624.3 days; invasive mucinous, 440.7 and 438.2 days; and squamous cell carcinoma, 149.1 and 146.1 days, respectively. The adjusted SGR of volume and mass of the solid-/micropapillary-predominant subtypes were significantly shorter than those of the acinar-, lepidic-, and papillary-predominant subtypes. The histologic subtype was independently associated with tumor doubling time. A VDT of 465.2 days and an MDT of 437.5 days yielded areas under the curve of 0.791 and 0.795, respectively, for distinguishing solid-/micropapillary-predominant subtypes from other subtypes of lung adenocarcinoma. Conclusion: The tumor doubling time of invasive lung adenocarcinoma differed according to the IASCL/ATS/ERS histologic classification.

• 대한조선학회논문집
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• 제54권2호
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• pp.151-160
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• 2017

Growing demand and rapid development of the synthetic fiber rope in mooring system have taken place since it has been used in deep water platform lately. Unlike a chain mooring, synthetic fiber rope composed of lightweight materials such as Polyester(polyethylene terephthalate), HMPE(high modulus polyethylene) and Aramid(aromatic polyamide). Non-linear stiffness and another failure mode are distinct characteristics of synthetic fiber rope when compared to mooring chain. When these ropes are exposed to environmental load for a long time, the length of rope will be increased permanently. This is called 'the creep phenomenon'. Due to the phenomenon, The initial characteristics of mooring systems would be changed because the length and stiffness of the rope have been changed as time goes on. The changed characteristics of fiber rope cause different mooring tension and vessel offset compared to the initial design condition. Commercial mooring analysis software that widely used in industries is unable to take into account this phenomenon automatically. Even though the American Petroleum Institute (API) or other classification rules present some standard or criteria with respect to length and stiffness of a mooring line, simulation guide considers the mechanical properties that is not mentioned in such rules. In this paper, the effect of creep phenomenon in the fiber rope mooring system under specific environment condition is investigated. Desiged mooring system for a Mobile Offshore Drilling Unit(MODU) with HMPE rope which has the highest creep is analyzed in a time domain in order to investigate the effects creep phenomenon to vessel offset and mooring tension. We have developed a new procedure to an analysis of mooring system reflecting the creep phenomenon and it is validated through a time domain simulation using non-linear mooring analysis software, OrcaFlex. The result shows that the creep phenomenon should be considered in analysis procedure because it affects the length and stiffness of synthetic fiber rope in case of high water temperature and permanent mooring system.

• Journal of Chest Surgery
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• 제28권6호
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• pp.571-578
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• 1995

Rastelli operation in which right ventricle[RV and pulmonary artery[PA is connected with an artificial graft is effective in increasing the pulmonary blood flow in certain types of congenital heart disease but, in many, it requires a reoperation because of the relative stenosis of graft that develops as the patients become old. The purpose of this study is to evaluate the various factors which many influence the long term outcome of such patients following a Rastelli operation. A total of 47 patients underwent a Rastelli operation during a 15 year period between November, 1978 and October 1993. The mean follow-up period is 76.1 51.3 months.1 Among the 47 patients, a valved conduit was used in 30[63.8% , and non-valved conduit in 17[36.2% patients. In the 8 patients[17.0% who died postoperatively, a valved conduit was used in 5 [16.6% and a non-valved conduit in 3[17.6% . There was no statistical difference in mortality between the 2 groups. There was a good linear correlation between the body surface area[X and the conduit size[Y [Y=3.86X + 14.6, R=0.55, P=0.01 .2 Ten patients underwent replacement of the conduit during the follow-up period. The type of conduit used and the frequency of subsequent replacement were as follows: Ionescu-Shiley, valved-33.3%, Carpentier-Edwards, valved-30.8%, Hancock, valved-80% and non-valved conduit-9.1%. The median period free of reoperation was 110 months for the valved and 79 months for the non-valved group, there being no statistical difference between the 2 groups. 3 The patients who did not require reoperation are all doing well [New York Heart Association Functional Classification: Class I . Pressure gradient between the RV and the PA was 20 mmHg in 10 randomly selected patients who did not require reoperation and 92 9 mmHg in 10 patients who did require reoperation.4 In the 10 patients who underwent a conduit replacement procedure.5 Among patients undergoing reoperation, 2 died from endocarditis.The remaining 8 patients are doing well without limitation in physical activity at a mean follow-up period of 32.7 33.9 months [range 2 to 89 months . 6 At 5, 7, and 10 years, the reoperation-free rates among all patients were 96%, 91% and 29% and the survival rates were 82%, 82% and 71%. In conclusion, Rastelli operation is an effective procedure in ameliorating symptoms in a select group of patients with congenital heart disease. Because of the inherent nature of relative graft stenosis and degeneration, a long-term follow-up is required under the proper selection of the graft material.

• 한국구조물진단유지관리공학회 논문집
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• 제24권6호
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• pp.206-216
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• 2020

국내의 노후 철도교량이 증가함에 따라 노후화로 인한 유지관리비가 점점 증가하고 있으며, 지속적인 관리가 더욱 더 중요해지고 있다. 하지만 관리해야하는 노후 시설물은 증가하지만, 노후 시설물을 점검 및 진단을 할 수 있는 전문 인력은 부족해지고 있다. 이러한 문제를 해결하기 위해 본 연구는 정적 변형률 응답 데이터를 적용하여 AI 기술의 머신러닝 기법으로 구조물의 국부적인 손상을 탐지하는 개선된 학습모델을 제시하고자 한다. 손상탐지 머신러닝 학습 모델을 구성하기 위해 우선 무도상 철도 판형교의 설계도면을 참고하여 교량의 해석모델을 설정하였으며, 설정된 해석모델로 손상시나리오에 따른 정적변형률 데이터를 추출하여 통계적 기법을 이용해 교량의 신뢰도 기반의 Local 손상 지수를 제시하였다. 손상 탐지는 손상 유무 탐지, 크기 탐지, 위치 탐지 3단계의 과정을 수행하여 손상 크기 탐지에서 선형 회귀 모델을 추가로 고려해 임의의 손상을 탐지하였으며, 최종적으로 손상 탐지 머신러닝 분류 학습 모델과 회귀 모델을 이용한 임의의 손상 위치를 추정 및 검증하였다.

• Steel and Composite Structures
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• 제5권2_3호
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• pp.181-192
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• 2005

The effective length method for flexural (column) buckling has been used for many decades but its use is somewhat limited in various contemporary design codes to moderately slender structures with elastic critical load factor (${\lambda}_{cr}$) less than 3 to 5. In pace with the use of higher grade steel in recent years, the influence of buckling in axial buckling resistance of a column becomes more important and the over-simplified assumption of effective length factor can lead to an unsafe, an uneconomical or a both unsafe and uneconomical solution when some members are over-designed while key elements are under-designed. Effective length should not normally be taken as the distance between nodes multiplied by an arbitrary factor like 0.85, 1.0, 2.0 etc. Further, the classification of non-sway and sway-sensitive frames makes the conventional design procedure tedious to use and, more importantly, limited to simple regular frames. This paper describes the practical use of second-order analysis with section capacity check allowing for $P-{\delta}$ and $P-{\Delta}$ effects together with member and system imperfections. Most commercial software considers only the $P-{\Delta}$ effect, but not member and frame imperfections nor $P-{\delta}$ effect, and engineers must be very careful in their uses. A verification problem is also given for validation of software for this type of powerful second-order analysis and design. It is a trend for popular and advanced national design codes in using the second-order analysis as a norm for analysis and design of steel structures while linear analysis may only be used in very simple structures.

• 한국측량학회지
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• 제34권3호
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• pp.243-251
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• 2016

일반적으로 라이다 데이터 처리 과정은 노이즈 제거, 지표면/비지표면 분리를 위한 필터링, 데이터 분류, 객체분할, 형태인식, 객체 모델링, 성과물에 대한 정확도 검증 등이다. 본 논문은 점군집 라이다 데이터를 이용한 3차원 곡면객체의 모델링과 정확도 검증에 중점을 두고 있다. 기존의 구형 및 원통형 객체 모델링 방법은 함수의 선형화, 미지계수의 초기 근사값 및 반복 계산이 요구되지만, 제안한 방법은 모델링 함수의 미지계수를 직접 결정하는 방법이다. 이를 위하여 객체를 형성하는 단위 객체면 형태를 분석하여 적합한 함수를 결정하고, 함수를 구성하는 미지변수를 추정한 후 정확도를 분석하여 타당성을 검증하였다. 제안한 방법을 반구형 및 반원통의 시뮬레이션 및 실제 건물 데이터에 적용하여 모델링 함수의 계수와 정확도를 산정하였으며, 다양한 형태의 객체 모델링의 자동화에 기여할 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권2호
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• pp.157-162
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• 2018

Objective: The aim of this study is to identify single nucleotide polymorphisms (SNPs) and genes related to pig IMF and estimate the heritability of intramuscular fat content (IMF). Methods: Genome-wide association study (GWAS) on 704 inbred Berkshires was performed for IMF. To consider the inbreeding among samples, associations of the SNPs with IMF were tested as random effects in a mixed linear model using the genetic relationship matrix by GEMMA. Significant genes were compared with reported pig IMF quantitative trait loci (QTL) regions and functional classification of the identified genes were also performed. Heritability of IMF was estimated by GCTA tool. Results: Total 365 SNPs were found to be significant from a cutoff of p-value <0.01 and the 365 significant SNPs were annotated across 120 genes. Twenty five genes were on pig IMF QTL regions. Bone morphogenetic protein-binding endothelial cell precursor-derived regulator, forkhead box protein O1, ectodysplasin A receptor, ring finger protein 149, cluster of differentiation, tyrosine-protein phosphatase non-receptor type 1, SRY (sex determining region Y)-box 9 (SOX9), MYC proto-oncogene, and macrophage migration inhibitory factor were related to mitogen-activated protein kinase pathway, which regulates the differentiation to adipocytes. These genes and the genes mapped on QTLs could be the candidate genes affecting IMF. Heritability of IMF was estimated as 0.52, which was relatively high, suggesting that a considerable portion of the total variance of IMF is explained by the SNP information. Conclusion: Our results can contribute to breeding pigs with better IMF and therefore, producing pork with better sensory qualities.

• 대한조선학회논문집
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• 제29권1호
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• pp.103-112
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• 1992

선박의 최종굽힘 모멘트는 설계에 적용되는 주요강도로써 이를 추정하는 여러방법들이 제안되었는데, 판과 보강재로 이루어진 구조요소의 압축 최종강도에 대한 추징에서 시작되는 것이 일반적이다. 본 논문에서는 최종굽힘 모멘트를 구하기 위해 보강판의 압축 강도추정을 지금까지 제안된 여러가지 방법을 정리하여 소개하고, 실선 설계에 적용될 수 있는 유용성 측면에서 검토하였다. 그 결과를 이용하여 3척의 살물선에 대한 신뢰성 해석을 수행하였다. 선박에 작용하는 파랑굽힘 모멘트는 선급규정에 의해 계산하였다. 본 연구의 신뢰성 해석 문제는 안전여유식의 형태가 비선형임을 고려하여 Advanced First-Order Reliability Method를 이용하였다. 몇가지의 해석예로부터 선체구조의 신뢰성 검토측면에서 최종강도 추정방법을 비교하였다.

• 한국지능시스템학회논문지
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• 제19권6호
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• pp.852-859
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• 2009

TFT-LCD 자동 검사 시스템에서 결함 검출을 위한 영상은 라인 스캔 카메라(line scan camera)나 에어리어 스캔 카메라 (area scan camera)에 의해서 획득하게 된다. 그러나 임펄스 잡음과 가우시안 잡음, CCD 혹은 CMOS 센서의 한계, 조명등의 영향으로 열화된 영상이 획득되며, 한도성 결함 영역을 인간의 육안으로 구분하기 어렵게 된다. 본 논문에서는 효율적인 결함 검출을 위해 특징 추출 방법과 결함 검출 방법을 제안한다. 특징 벡터로 웨버의 법칙을 이용한 결함 영역과 주변 배경 영역의 평균 밝기 차와 주변 배경 영역의 밝기 변화를 이용한 표준편차를 이용하며, 결함 영역 검출를 위해 추출된 특징 벡터를 이용하여 비선형 SVM을 적용한다. 실험 결과는 제안한 방법이 다른 방법들 보다 성능이 우수함을 보여준다.