• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.816-821
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• 2005

The cycloid reducer has very high efficiency, high ratios, high stiffness and small size, in comparison with a conventional gear mechanism, which makes it an attractive candidate for limited space and precision application such as industrial robot. There are several publications on analysis and design of the cycloid reducer, however, it was assumed that the contact stiffness of pin rollers and cycloid disk is constant regardless of their contact geometry. Moreover, the torsional stiffness of the cycloid reducer couldn't be calculated due to the assumption. In this paper, we present a new procedure of calculating torsional stiffness of the cycloid reducer using Hertz contact theory. First, conventional force analysis of the cycloid reducer is briefly reviewed. Then, iterative numerical calculation procedure of the contact stiffness is proposed based on the Hertz contact theory where the contact stiffness depends on the contact force. In addition, total torsional stiffness of the cycloid reducer is estimated considering its rolling element bearing stiffness. The torsional stiffness of the cycloid reducer is dominated by the rolling element bearing stiffness since the contact stiffness of the cycloid disk is too large.

• Mycobiology
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• 제44권2호
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• pp.79-84
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• 2016

A coelomycete with characters resembling the asexual morphs in the family Botryosphaeriaceae was isolated from a fallen leaf of an orchid collected in Thailand. Morphological and phylogenetic analyses placed the strain in Neoscytalidium. Phylogenetic relationships among Neoscytalidium species were inferred by analyzing internal transcribed spacers and large subunit of rRNA sequence data and indicate that our strain is a new species, which is introduced and illustrated herein as Neoscytalidium orchidacearum sp. nov.

• Smart Structures and Systems
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• 제30권4호
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• pp.421-432
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• 2022

Regarding the high significance of correct pan evaporation modeling, this study introduces two novel neuro-metaheuristic approaches to improve the accuracy of prediction for this parameter. Vortex search algorithms (VSA), sunflower optimization (SFO), and stochastic fractal search (SFS) are integrated with a multilayer perceptron neural network to create the VSA-MLPNN, SFO-MLPNN, and SFS-MLPNN hybrids. The climate data of Arcata-Eureka station (operated by the US environmental protection agency) belonging to the years 1986-1989 and the year 1990 are used for training and testing the models, respectively. Trying different configurations revealed that the best performance of the VSA, SFO, and SFS is obtained for the population size of 400, 300, and 100, respectively. The results were compared with a conventionally trained MLPNN to examine the effect of the metaheuristic algorithms. Overall, all four models presented a very reliable simulation. However, the SFS-MLPNN (mean absolute error, MAE = 0.0997 and Pearson correlation coefficient, R_P = 0.9957) was the most accurate model, followed by the VSA-MLPNN (MAE = 0.1058 and R_P = 0.9945), conventional MLPNN (MAE = 0.1062 and R_P = 0.9944), and SFO-MLPNN (MAE = 0.1305 and R_P = 0.9914). The findings indicated that employing the VSA and SFS results in improving the accuracy of the neural network in the prediction of pan evaporation. Hence, the suggested models are recommended for future practical applications.

• 한국전자통신학회논문지
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• 제16권4호
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• pp.625-632
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• 2021

본 논문은 잡음감쇠기에서 CNN(Convolutional Neural Network) 계층의 필터 수가 성능에 미치는 영향을 연구하였다 이 시스템은 적응필터 대신 신경망 예측필터를 이용하며 심층학습방법으로 잡음을 감쇠한다. 64-뉴런, 16-커널 CNN 필터와 오차 역전파 알고리즘을 이용하여 잡음이 포함된 음성신호로부터 음성을 추정한다. 본 연구에서 필터 수에 대한 잡음감쇠기의 성능을 검증하기 위하여 Keras 라이브러리를 사용한 프로그램을 작성하고 시뮬레이션을 실시하였다. 시뮬레이션 결과, 본 시스템은 필터 수가 16일 때 MSE(Mean Squared Error) 및 MAE(Mean Absolute Error) 값이 가장 작은 것으로 나타났으며 필터가 4개 일 때 성능이 가장 낮은 것을 볼 수 있다. 그리고 필터가 8개 이상이 되면 필터 수에 따라 MSE 및 MAE 값이 크게 차이나지 않는 것을 보여주었다. 이러한 결과로부터 음성신호의 주요 특징을 표현하기 위해서는 약 8개 이상의 필터를 사용해야 한다는 것을 알 수 있다.

• 대한약침학회지
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• 제13권1호
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• pp.129-144
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• 2010

Objective : Traumatic lumbar burst fracture causes significant spinal cord injury. This report is intended to estimate the efficacy using oriental treatment on a patient with lumbar burst fracture and spinal cord injury. Methods : From 21th December, 2009 to 5th February, 2010, 1 female inpatient diagnosed with lumbar burst fracture and spinal cord injury was treated with general oriental medicine therapy : mae-sun therapy ; acupuncture ; moxibustion ; pharmacopuncture ; physical therapy and herbal medication. TUG, SCIMII and VAS were used for evaluation of gait disturbance and pain in both feet. Measurement of self voiding amount and remaining amount through CIC was used for evaluation of neurogenic vesical dysfunction. Results : The patient showed a certain degree of improvement in gait disturbance, pain in both feet and neurogenic vesical dysfunction through above evaluation methods. Conclusion : Oriental treatments such as mae-sun therapy, acupuncture and moxibustion therapy, pharmacopuncture therapy and herbal medication can be effective for spinal cord injury due to traumatic lumbar burst fracture.

• 한국식품위생안전성학회지
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• 제14권4호
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• pp.365-371
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• 1999

인삼시료에 있는 quintozene, tolclofos-methyl 그리고 procymidone 등의 농약성분을 추출하기 위한 방법으로서 microwave를 이용할 수 있을 지의 여부와 인삼을 가공제품으로 만들기 전에 microwave를 이용하여 잔류농약 성분을 신속히 추출하여 제거시킬 수 있는지 알고자 하였다. 인삼분말 시료에 hexane을 추출용매로 이용한 microwave 추출의 최적 조건은 power 150 watts, 추출시간 2분이었고 그 추출 효율은 Soxhlet으로 7시간 동안 가열 환류 추출한 결과를 지수 100으로 하였을 때 quintozene 100, tolclofos-methyl 92, procymidone 100으로 거의 동일한 수준으로 나타났다. 그리고 microwave 추출법을 사용함으로써 실제 Soxhlet 추출법에서 사용된 용매양의 최소 7배 이상 감소시킬 수 있었고 추출 시간 또한 7시간에서 2분으로 훨씬 단축되었다. 인삼 엑기스 제조 전 잔류농약 성분의 제거 실험에 있어서 45%나 60% ethyl alcohol을 용매로 사용하고 microwave로 power 150 watts 추출시간 2분 이내로 1회 추출하여 quintozene 100%, tolclofos-methyl 69%, procymidone 83%정도의 제거효과를 얻었다.

• Journal of Korea Artificial Intelligence Association
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• 제1권2호
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• pp.15-20
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• 2023

This study aims to enhance the accuracy of fine dust predictions by analyzing various factors within the local environment, in addition to atmospheric conditions. In the atmospheric environment, meteorological and air pollution data were utilized, and additional factors contributing to fine dust generation within the region, such as traffic volume and electricity transaction data, were sequentially incorporated for analysis. XGBoost, Random Forest, and ANN (Artificial Neural Network) were employed for the analysis. As variables were added, all algorithms demonstrated improved performance. Particularly noteworthy was the Artificial Neural Network, which, when using atmospheric conditions as a variable, resulted in an MAE of 6.25. Upon the addition of traffic volume, the MAE decreased to 5.49, and further inclusion of power transaction data led to a notable improvement, resulting in an MAE of 4.61. This research provides valuable insights for proactive measures against air pollution by predicting future fine dust levels.

• 한국시뮬레이션학회논문지
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• 제24권3호
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• pp.89-96
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• 2015

무기체계를 보다 효과적으로 사용하기 위해 다양한 표적 유형별로 무기효과 평가방법이 발전되었다. 본 연구에서는 3차원 건물표적에 대한 공격시 파괴효과를 평가할 수 있는 가장 효과적인 방법론을 찾고자 하였다. 가능한 건물표적에 대한 파괴효과 평가 방법에는 기대손실파괴확률(EFD)과 단발명중파괴확률(SSPD)이 있다. 여기에 건물표적의 크기, 무기체계 원형공산오차(CEP), 건물평균유효파괴면적(MAE_bldg), 건물표적과 유도무기 조우조건인 입사각을 입력변수로 하여 무기체계의 파괴효과를 계산하였다. 무기체계 특성 CEP와 MAE_bldg의 변화에 따른 EFD와 SSPD 결과를 비교하고 입사각의 변화량과 표적건물 높이에 따른 파괴효과를 비교함으로써 3차원 건물표적에 대한 적합성을 분석하였다.

• Tuberculosis and Respiratory Diseases
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• 제69권3호
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• pp.184-190
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• 2010

Background: The purpose of this study was to determine the prognostic significance of chest computed tomographic (CT) parameters in acute submassive pulmonary embolism (PE). Methods: Between January 2006 and December 2009, 268 consecutive patients with acute submassive PE that was confirmed by chest CT with pulmonary angiography in emergency room were studied. One experienced radiologist measured CT parameters and judged the presence of right ventricular dysfunction. CT parameters were analyzed to determine their ability to predict a major adverse event (MAE). Results: There were 220 patients included and 61 (27.7%) had MAE. Left ventricular and right ventricular maximum minor axis ($36.4{\pm}8.0$ vs. $41.7{\pm}7.4$, p<0.01; $45.7{\pm}9.4$ vs. $41.5{\pm}7.6$, p<0.01), superior vena cava diameter ($19.2{\pm}3.4$ vs. $18.0{\pm}3.4$, p=0.02), azygos vein diameter ($10.0{\pm}2.2$ vs. $9.2{\pm}2.3$, p=0.02), septal displacement (19 vs. 18, p<0.01) were significantly higher in MAE group than in no MAE group. Patients with MAE had high right ventricular/left ventricular dimension ratio (RV/LV ratio) compared to patients without MAE ($1.34{\pm}0.48$ vs. $1.03{\pm}0.28$, p<0.01). The most useful cut-off value of RV/LV ratio for MAE was 1.3 and the area under the curve was 0.71 (0.62~0.79). Conclusion: RV/LV ratio on chest CT was a significant predictor of submassive PE related shock, intubation, in-hospital mortality, thrombolysis, thrombectomy within 30 days.

• 한국항해항만학회지
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• 제34권10호
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• pp.757-762
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• 2010

본 연구는 유산소운동능력의 차이를 보이는 두 집단이 각각 로윙에르고미터 최대하 운동을 실시한 후 혈중 활성산소의 변화에 어떠한 차이를 나타내는지 구명하는데 목적이 있으며 연구대상으로는 조정 선수집단 6명과 비선수집단 6명을 대상으로 최대유산소운동능력을 검사한 후 각각의 목표심박수 85~90%를 적용하여 로윙에르고미터 운동을 실시하였고 운동 전, 직후, 10분, 20분, 차30분에 각각 채혈하여 활성산소의 변화를 분석하였다. 그 결과는 유산소운동능력의 차이에 따른 활성산소의 변화에서 집단과 시기 간 상호작용 효과는 유의한(p<.05) 차이를 나타내어 시기에 따른 변화의 양상이 집단 간 차이가 있었고 사후검증 결과 회복기 10분에서 20분 그리고 20분에서 30분 구간에서 유의한 차이가 나타났다. 결론적으로 인체에 부정적인 영향을 미치는 활성산소로부터 유산소운동능력이 우수한 조정선수집단이 비선수집단에 비해 긍정적인 회복 패턴을 보였다.