• 감성과학
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• 제7권2호
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• pp.141-148
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• 2004

일상생활의 대화중에 포함되는 잡음, 특히 모든 주파수 대역에 포함되는 백색잡음에 의해 오염된 음성신호는 청각적으로 심한 불쾌감과 거부감을 주며 대화의 명료성을 저해시키는 요인으로 작용할 수 있다. 본 논문은 이러한 잡음환경 하에서 음성인식을 위하여 음성에 부가된 잡음을 제거하는 방범으로 프레임 단위로 웨이브렛 변환을 하여 웨이브렛 계수의 표준편차를 이용하여 시간 적응 임계값을 정하는 새로운 방법을 제안한다. 음성의 특성을 고려하기 위하여 고주파 성분을 많이 가지는 무성음의 경우는 cD1 신호에서, 저주파 성분을 많이 가지는 유성음의 경우는 cA3 신호의 표준편차를 이용하여 시간 적응 임계값을 설정하였다. 실험을 통해 제안한 방법이 일반적인 웨이브렛 변환과 웨이브렛 패킷 변환을 이용한 방법보다 SNR과 MSE 측면에서 향상됨을 확인할 수 있었다. 또한 웨이브렛 변환과 웨이브렛 패킷 변환에서는 파열음, 마찰음 및 파찰음 성분이 많이 제거되는 반면 제안한 방법은 본래 신호와 유사하게 복원됨을 실험 결과 확인할 수 있었다.

• 한국식품영양과학회지
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• 제29권5호
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• pp.948-956
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• 2000

There is growing evidence that soy isoflavone play beneficial roles in the prevention of chronic diseases such as hormone dependent cancers, cardiovascular diseases, osteoporosis and also reduced incidence of menopausal symptoms. However current data are not sufficient to determine the effective doses for beneficial as well as harmful effects and to support dietary recommendation for isoflavones. Since soy products containing isoflavone are one of the common food items that Koreans consume daily basis, assessing consumption of soy isoflavone by Koreans will give a valuable information on making dietary recommendations for isoflavones. the present study was designed to assess dietary intake of isoflavone of Korean middle-aged women who might receive the most beneficial effects from isoflavone consumption thereby prevent post menopausal related symptoms and diseases. In this study isoflavone contents of soy products were analyzed and soy products and isoflavone consumption of these subjects were assessed by a self-reported dietary questionnaire and isoflavone intake data base. Subjects were consisted of 178 Korean women (35~60 y) who live in urban and rural area. All subjects provided detailed information on demographics, anthropometry, health history, menopausal symptoms, health history, menopausal symptoms, and dietary intake using food frequency questionnaire (FFQ) which was developed for Koreans. The average age of the subjects was 46.6 years. The soy products which the subjects frequently consumed were soybean paste soup, braised fried soybean, tofu residue stew, tofu, soy milk, natto stew, bean sprouts, and soybean broth which contained 10.68 mg, 3.34 mg, 2.44 mg, 2.42 mg, 2.42 mg, 1.12 mg, 1.02 mg, 0.33 mg of isoflavone per 100 g, respectively. The estimated daily intake (EDI) of isoflavones ranged from 0 to 144.3 mg, and the mean daily isoflavone (sum of daidzein and genisten) intake of the subjects was 24.41 mg.

• 한방재활의학과학회지
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• 제31권2호
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• pp.81-97
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• 2021

Objectives This study was designed to identify the changes of autonomic nervous system (ANS) which was induced by acupuncture at the field of the auricular branch of the vagus nerve. Methods 30 healthy adults were selected and classified into two groups; experimental group, control group. After providing mental stress, acupuncture was applied at external ear in experimental group and no treatment executed in control group. The evaluation of ANS function was measured by heart rate variability (HRV). We statically analyzed the difference of HRV parameters which include mean heart rate (MHRT), standard deviation of all N-N intervals (SDNN), square root of the mean of the sum of the squares of differences between adjacent N-N intervals (RMSSD), total power (TP), low frequency power (LF), high frequency power (HF), LF/HF ratio. Results All subjects showed significant increase in SDNN, LF after stress stimulation (p<0.05). Immediately after intervention, MHRT was significantly decreased (p<0.001) and RMSSD, HF were significantly increased in experimental group (p<0.05). After the end of intervention, SDNN, HF, RMSSD, TP, LF were significantly increased in experimental group (p<0.01, p<0.05). And when comparing baseline HRV, SDNN, LF were significantly increased in control group (p<0.01) and SDNN, RMSSD, TP, LF were significantly increased in experimental group (p<0.05). In the subgroup analysis, normal balance of ANS group showed significant increase in TP, LF, SDNN, HF (p<0.01, p<0.05). Conclusions We suggested that acupuncture at external ear, region of the vagus nerve distribution could increase parasympathetic activity and cause changes and reregulation of the ANS.

• 한국정보통신학회논문지
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• 제23권11호
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• pp.1407-1413
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• 2019

본 논문에서는 비직교 다중접속 시스템의 주파수 효율성 최대화를 위하여 다른 송신기가 동일한 주파수 대역에서 신호를 전송할 수 있다고 가정한다. 그리고 비직교 다중접속 시스템의 총 데이터 전송률의 최대화가 아닌 수신기의 데이터 전송률의 공정성 성능 개선에 집중한다. 따라서 본 논문에서는 간섭이 존재하는 비직교 다중접속 시스템을 고려하여 수신기의 평균 데이터 전송률에 대한 공정성 성능을 개선하기 위한 전력 할당 기법을 제안한다. 레일레이 페이딩 채널을 가정하여 수신기의 평균 데이터 전송률을 정의하고, 높은 신호 대 잡음비의 근사법을 이용하여 평균 데이터 전송률의 공정성 성능을 개선하기 위한 전력 할당 계수를 유도한다. 또한, 시뮬레이션을 통해 제안하는 전력 할당 기법이 간섭을 갖는 비직교 다중접속 시스템에서 데이터 전송률의 공정성 성능을 개선할 수 있음을 보인다.

• 대한의용생체공학회:의공학회지
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• 제44권6호
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• pp.384-391
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• 2023

Among the elderly, fatal injuries and deaths are significantly attributed to falls. Therefore, a pre-impact fall detection system is necessary for injury prevention. In this study, a robust threshold-based algorithm was proposed for pre-impact fall detection, reducing false positives in highly dynamic daily-living movements. The algorithm was validated using public datasets (KFall and FARSEEING) that include the real-world elderly fall. A 6-axis IMU sensor (Movella Dot, Movella, Netherlands) was attached to S2 of 20 healthy adults (aged 22.0±1.9years, height 164.9±5.9cm, weight 61.4±17.1kg) to measure 14 activities of daily living and 11 fall movements at a sampling frequency of 60Hz. A 5Hz low-pass filter was applied to the IMU data to remove high-frequency noise. Sum vector magnitude of acceleration and angular velocity, roll, pitch, and vertical velocity were extracted as feature vector. The proposed algorithm showed an accuracy 98.3%, a sensitivity 100%, a specificity 97.0%, and an average lead-time 311±99ms with our experimental data. When evaluated using the KFall public dataset, an accuracy in adult data improved to 99.5% compared to recent studies, and for the elderly data, a specificity of 100% was achieved. When evaluated using FARSEEING real-world elderly fall data without separate segmentation, it showed a sensitivity of 71.4% (5/7).

• 한국음향학회지
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• 제26권2호
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• pp.75-79
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• 2007

본 논문은 SVM(Support Vector Machines)을 이용한 음성신호 기반의 효과적인 성별인식 시스템을 제안한다. 분별적 이진(binary) 패턴 분류기인 SVM은 특징 공간에서 비선형 경계를 찾아 분류하는 방법으로 우수한 성능을 보인다고 알려져 있다. 연구에서는 기존의 성별인식에서 널리 쓰이고 있는 MFCC(Mel Frequency Cepstral Coefficients)를 사용하여 SVM과 기존의 GMM(Gaussian Mixture Model) 알고리즘의 성별인식 성능을 비교하였고, 특히, 보다 향상된 SVM의 성별인식을 위해 MFCC와 Pitch를 이용한 결합 특징 벡터를 적용하였다. 실험결과 MFCC 파라미터를 사용했을 때 제안된 SVM이 GMM보다 우수한 성별인식 성능을 보였고, 제안된 결합 특징 벡터를 사용 했을 때 우수한 성능을 보였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1315-1319
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• 2011

As government's policy is enacted to reduce greenhouse gas emission in transportation sector, railroad sector has to estimate amount of emission and propose feasible methods to reduce emission. To calculate accurate emission of railroad sector, we performed a study on the calculation model development for Tier 3 GHG emission factors. According to IPCC guide line, Tier 3 emission factor reflects individual characteristic of diesel locomotive. For this reason, we estimated GHG emission factor by stratified diesel locomotive and the result show difference of emission factor by notch changing. Therefore, the analysis of notch frequency during operation is required to develop Tier 3 emission factor, and we analysed a running pattern of diesel locomotive. As a result, idle and 8 notch consist about 70% of total running distance. In conclusion, the calculation model suppose that Tier 3 GHG emission factor is the sum of multiplied emission factor by weights in each notch. This result can contribute to Tier 3 emission factor calculation and reduction method development of emission in railroad sector by managing driving efficiency and technology development.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권8호
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• pp.2647-2662
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• 2014

This paper proposes an efficient and low complexity power-loading algorithm for MIMO-OFDM downlink based cognitive radio system that maximizes the sum rate of single secondary user (SU) under constraints on the tolerable interference thresholds between secondary user and primary user's frequency bands and the total transmission power. Our suboptimal algorithm is based on the $2^{nd}$ order interference tracking and nulling mechanism to allocate transmission power of the subcarriers among SU's scheme. The performance of our proposed suboptimal scheme is compared with the performance of the classical power loading algorithms, e.g., water filling, $1^{st}$ order interference tracking, nulling, and other suboptimal schemes. Numerical results show that our algorithm has low complexity but obtains a higher channel capacity than that of some previous suboptimal algorithms in some scenarios. We dedicate also that for a given interference threshold, the $2^{nd}$ order interference tracking mechanism has dynamic number of nulling position instead fixed number of nulling position.

• 간호행정학회지
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• 제7권1호
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• pp.15-23
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• 2001

This study was a methodological research to develop computerized patient classification system. The subjects of this investigation were 435 inpatients except redundant data and outliers in P University Hospital from January 18, 2000 to January 24, 2000. The data was analyzed by discrimination analysis and adopted discriminant variables were 1) sum of frequency for the nursing activities, 2) the number of nursing activities that do not need to consider intensity of the activities, and 3) total hours of nursing activities that need to consider their intensities. Discriminant function developed by this study classified the patients into 4 groups; class I, 251 ; class II, 125 ; class III, 39 ; class IV, 20. The Hit ratio was 89.23. Based on this study, following suggestions can be made for the future research 1. Inclusive patient classification system, which includes more expanded direct nursing care factors, need to be developed and examined. 2. This developed classification system can be utilized to evaluate patient distribution and to estimate adequate numbers of nursing staffs in each nursing unit.

• 비파괴검사학회지
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• 제29권6호
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• pp.570-578
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• 2009

Excitation and propagation of guided waves are very complex problems in pipes due to their dispersive nature. Pipes are commonly used in the oil, chemical or nuclear industry and hence must be inspected regularly to ensure continued safe operation. The normal mode expansion(NME) method is given for the amplitude with which any propagating waveguide mode is generated in the pipes by applied surface tractions. Numerical results are calculated based on the NME method using different sources, i.e., non-axisymmetric partial loading and quasi-axisymmetric loading sources. The sum of amplitude coefficients for 0~nineth order of the harmonic modes are calculated based on the NME method and the dispersion curves in pipes. The superimposed total field which is namely the angular profile, varies with propagating distance and circumferential angle. This angular profile of guided waves provides information for setting the transducer position to find defects in pipes.