• 전자공학회논문지
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• 제50권6호
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• pp.3-8
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• 2013

비트 패턴 미디어 (BPM) 저장장치는 기존 자기 기록장치의 한계를 극복하기 위한 기술 중 하나로 주목 받고 있다. 하지만 고밀도의 BPM 저장창치에서는 트랙간의 간섭 (ITI), 심벌간의 간섭 (ISI), 잡음이 비트 오율 (BER)을 심각하게 저하시키는 문제가 있다. 본 논문에서는 ITI와 ISI의 악영향을 경감시키기 위해 축약사상 기반의 단순 반복적 2차원 등화기를 제안한다. 또한 제안한 2차원 등화기에 대한 BPM 저장장치의 채널 특성이 수렴 조건을 만족함을 살펴보았다. 모의실험에서 1차원 등화기와 2차원 등화기의 비트 분리 특성 차이를 보였고, 제안한 등화기의 BER 성능을 다른 등화 방법과 비교하여 평가하였다. 실험결과에 의하면 본 논문에서 제안한 등화기는 적당한 복잡도를 유지하면서 고밀도 BPM 저장장치를 위한 훌륭한 등화기라 할 수 있다.

• Korea-Australia Rheology Journal
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• 제21권4호
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• pp.225-233
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• 2009

In various attempts to relate the behaviour of highly-elastic liquids in complex flows to their rheometrical behaviour, obvious candidates for study have been the variation of shear viscosity with shear rate, the two normal stress differences $N_1$ and $N_2$, especially $N_1$, and the extensional viscosity $\eta_E$. In this paper, we shall be mainly interested in 'constant-viscosity' Boger fluids, and, accordingly, we shall limit attention to $N_1$ and $\eta_E$. We shall concentrate on two important flows - axisymmetric contraction flow and "splashing" (particularly that which arises when a liquid drop falls onto the tree surface of the same liquid). Modern numerical techniques are employed to provide the theoretical predictions. It is shown that the two obvious manifestations of viscoelastic rheometrical behaviour can sometimes be opposing influences in determining flow characteristics. Specifically, in an axisymmetric contraction flow, high $\eta_E$ can retard the flow, whereas high $N_1$ can have the opposite effect. In the splashing experiment, high $\eta_E$ can certainly reduce the height of the so-called Worthington jet, thus confirming some early suggestions, but, again, other rheometrical influences can also have a role to play and the overall picture may not be as clear as it was once envisaged.

• 한국정보통신학회논문지
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• 제16권9호
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• pp.2021-2030
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• 2012

조기심실수축(PVC)은 가장 보편적인 부정맥으로 심실세동, 심실빈맥 등과 같은 위험한 상황을 유발할 수 있는 가능성을 가지고 있기 때문에 이의 조기 검출은 매우 중요하다. 특히 일반인들의 건강상태를 지속적으로 모니터링 해야 하는 헬스케어 시스템에서는 이를 위한 심전도 신호의 실시간 처리가 필요하다. 즉, 최소한의 연산량으로 정확한 R파를 검출하고, 대상 환자의 특징을 파악하여 PVC를 분류할 수 있는 적합한 알고리즘의 설계가 필요하다. 따라서 본 연구에서는 PVC 실시간 분류를 위한 환자 적응형 패턴 매칭 기법을 제안한다. 이를 위해 전 처리 과정과 적응 가변형 문턱 값과 윈도우를 통해 R파를 검출하였으며, 검출 대상에 따른 정상신호 군을 선별하고 이를 벗어나는 신호를 이상신호로 분류하기 위해 해쉬 함수를 통한 패턴 매칭 기법을 적용하였다. 제안한 알고리즘의 R파 검출 및 정상신호 분류 성능을 평가하기 위해서 MIT-BIH 부정맥 데이터베이스를 사용하였다. 성능평가 결과, R파는 평균 99.33%, 이상신호 분류에 대한 에러율은 0.32%로 나타났다.

• 한국정보통신학회논문지
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• 제23권2호
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• pp.117-126
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• 2019

부정맥 분류를 위한 기존 연구들은 분류의 정확성을 높이기 위해 신경망, 퍼지, 시계열 주파수 분석, 비선형 분석법 등이 연구되어 왔다. 이러한 방법들은 분류율를 향상시키기 위해 정확한 특징점과 많은 양의 신호를 처리해야 하기 때문에 데이터의 가공 및 연산이 복잡하며, 다양한 부정맥을 분류하는데 어려움이 있다. 본 연구에서는 AR(Auto Regressive) 모델링 기반의 특징점 추출과 SVM(Support Vector Machine)을 통한 조기수축 부정맥 분류 방법을 제안한다. 이를 위해 잡음을 제거한 ECG 신호에서 R파를 검출하고 QRS와 RR 간격의 특정 파형 구간을 모델링하였다. 이후 최적 세그먼트 길이(n1, n2), 최적 차수( p1, p2)의 4가지 AR 모델링 변수를 추출하고 SVM을 통해 Normal, PVC, PAC를 분류하였다. 연구의 타당성을 입증하기 위해 MIT-BIH 부정맥 데이터베이스를 대상으로 한 R파의 평균 검출 성능은 99.77%, Normal, PVC, PAC 부정맥은 각각 99.23%, 97.28, 96.62의 평균 분류율을 나타내었다.

• 호남수학학술지
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• 제27권4호
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• pp.665-672
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• 2005

By its simplicity and efficiency, subdivision is a widely used technique in computer graphics, computer aided design and data compression. In this paper we prove a regularity theorem for ternary interpolatory subdivision scheme that can be applied to non-stationary subdivision. This theorem converts the convergence of the limit curve of a ternary interpolatory subdivision to the analysis of the rate of the contraction of differences of the polygons.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.38.1-38.1
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• 2005

• 대한인간공학회지
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• 제4권2호
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• pp.25-31
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• 1985

Mechanical energy consumption during human running was studied. The subject was modeled by an eleven segment planar open linkage system and analyzed by Newtonian equations of motion from film data with a sampling rate of 50 Hz. The motion data from films were smoothed by lower 7 harmonics before analysis. And this study was tried for a normal male subject running on a concrete floor. The mechanical energy consumption was evaluated from the five different criteria suggested by others and a joint energy consumption criterion newly devised based on the muscle contraction.

• 대한산업공학회지
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• 제25권3호
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• pp.330-335
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• 1999

The goal of the study is to determine the most sensitive parameter to represent the degree of muscle force and fatigue. Various numerical parameters such as the first coefficient of Autoregressive (AR) Model, Root Mean Square (RMS), Zero Crossing Rate (ZCR), Mean Power Frequency (MPF), Median Frequency (MF) were tested in this study. Ten healthy male subjects participated in the experiment. They were asked to extend their trunk by using the right and left erector spinae muscles during a sustained isometric contraction for twenty seconds. The force levels were 15%, 30%, 45%, 60%, and 75% of Maximal Voluntary Contraction (MVC), and the order of trials was randomized. The results showed that RMS was the best parameter to measure the force level of the muscle, and that the first coefficient of AR model was relatively sensitive parameter for the fatigue measurement at less than 60% MVC condition. At the 75% MVC, however, both MPF and the first coefficient of AR Model showed the best performance in quantification of muscle fatigue. Therefore, the sensitivity of measurement can be improved by properly selecting the parameter based upon the level of force during a sustained isometric condition.

• 영어어문교육
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• 제12권2호
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• pp.87-105
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• 2006

Style is considered a pivotal construct in sociolinguistic variation studies. While previous studies have examined style in traditional forms of language such as speech, very little research has examined new and emerging styles such as computer-mediated discourse. Thus, the present study attempts to investigate style in the online communication mode of chat. In so doing, the study compares text-based online chat with speech and writing. Online chat has been previously described as a hybrid form of language that is close to speech. Here, the exact nature of online chat is elucidated by focusing on contraction use. Differential acquisition of stylistic variation is also examined according to English learning background. The empirical component consists of data from Korean speakers of English. Data is taken from a written summary, an oral interview, and a text-based online chat session. A multivariate analysis was conducted. Results indicate that online chat is indeed a hybrid form that is difficult to delineate from speech and writing. Text-based online chat shows a somewhat similar rate of contraction to speech, which confirms its hybridity.. Lastly, some implications of the study are given in terms of the learning and acquisition of style in general and in online contextual modes.

• 생약학회지
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• 제17권3호
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• pp.215-222
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• 1986

Although the 'Insamyangwee-tang' has been widely used in clinical purposes in the oriental medicine, its clinical efficacy is only documentated for the cases of gastritis, gastric ulcer and enteritis, but the experimental study on these has not been undertaken. So, to investigate the clinical efficacy of 'Insamyangwee-tang' comparing with animal experiments, This study was carried out. The results showed that relaxing action was shown on the isolated ileum in mice and that strong antagonistic actions were seen on $BaCl_2$, acetylcholine and histamine induced contraction of the ileum in mice, rats, rabbits and guinea-pigs that the relaxing effect of the intestinal smooth muscle was recognized. Inhibitory effects on transport rate in the small intestine of mice. Strong antagonistic actions were seen on acetylcholine induced contraction of duodenum in rats and remarkably inhibiting actions were seen of duodenum in rats. Inhibitory action on the secretion of gastric juice and pepsin, anti-ulceration effect was recognized.