• 한국소음진동공학회논문집
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• 제20권4호
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• pp.414-421
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• 2010

The proper orthogonal decomposition(POD) is used to the vibration analysis of microcantilever in tapping mode atomic force microscopy(AFM). The proper orthogonal modes (POM) are extracted from vibrating signals of microcantilever when it resonates and taps the sample. We present recent ideas based on POD and detailed experiments that yield new perspectives into the microscale structures such as the tapping cantilever. The linearized modeling technique based on POD is very useful to show the principal characteristics of the complex dynamic responses of the AFM microcantilever.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.125-128
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• 2004

AFM(Atomic Force Microscope) becomes a versatile tool in the nanoscale measurements and processes. Especially the tapping mode is a very useful mode in AFM operation to measure and process at the nanoscale. Although the tapping mode has a great potential for the novel techniques such as phase imaging, however, it is not clearly known the fundamental mechanics affected by complex tip-sample interactions. This paper shows the various nonlinear dynamic features in tapping mode AFM microcantilevers including hysteretic jumps and period doublings of the microcantilevers. Also it is discussed the complex dynamics of CNT(Carbon Nanotube) probes and the opportunities on the nanoscale nonlinear dynamics.

• 대한인간공학회지
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• 제28권4호
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• pp.167-169
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• 2009

Korean vowels have special feature such that same vowels do not appear sequentially in a syllable. And two vowels appear with consistent rules. Using this feature, functional key stroke methods are available to Korean computer keyboard. Tapping a key makes diphthong easily. This will be used to Korean computer keyboard design.

• 대한인간공학회지
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• 제31권5호
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• pp.647-655
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• 2012

Objective: The purpose of this study was to confirm difference between angular foot movement time and existing foot Fitts' law predicting times, and to develop the angular foot Fitts' law in the foot tapping task. Background: Existing studies of foot Fitts' law focused on horizontal movement to predict the movement time. However, when driving a car, humans move their foot from the accelerator to the brake with a fixed heel. Therefore, we examined the experiment to measure angular foot movement time in reciprocal foot tapping task and compared to conventional foot Fitts' law predicting time. And, we developed the angular foot Fitts' law. Method: In this study, we compared the angular foot movement time in foot tapping task and the predicted time of four conventional linear foot Fitts' law models - Drury's foot Fitts' law, Drury's ballistic, Hoffmann's ballistic, Hoffmann's visually-controlled. 11 subjects participated in this experiment to get a movement time and three target degrees of 20, 40, and 60 were used. And, conventional models were calculated for the prediction time. To analyze the movement time, linear and arc distance between targets were used for variables of model. Finally, the angular foot Fitts' law was developed from experimental data. Results: The average movement times for each experiment were 412.2ms, 474.9ms, and 526.6ms for the 89mm, 172mm, and 253mm linear distance conditions. The results also showed significant differences in performance time between different angle level. However, all of conventional linear foot Fitts' laws ranged 135.6ms to 401.2ms. On the other hand, the angular foot Fitts' law predicted the angular movement time well. Conclusion: Conventional linear foot Fitts' laws were underestimated and have a limitation to predict the foot movement time in the real task related angular foot movement. Application: This study is useful when considering the human behavior of angular foot movement such as driving or foot input device.

• Journal of Oral Medicine and Pain
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• 제21권1호
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• pp.55-65
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• 1996

This study was performed to investigate the effects of head posture and occlusal splint on the vertical dimension in mandibular rest position and swallowing. Thirty health dental students ware selected lot this study and BioEGNⓡ(Bioresearch Inc., USA) was used for measuring interocclusal distance during rest - swallowing - rest - tapping movement. This swallowing movements were observed in both normal head posture(NHP) and forward head posture (FHP). Thickness of occlusal splint was about 2mm at posterior molar area and even tooth contact were achieved on light biting. The four mandibular positions at which interocclusal distance measured were swallowing position, after swallowing position in which interocclusal distance was maximum, rest position follows swallowing, and tapping position after rest. Changes of distance in each position were measured for three mandibular planes, that is, sagittal, frontal, and horizontal plane, respectively. The results obtained were as follows : 1. In normal head posture, the mandible was raised 1.03mm without splint, and 0.77mm with splint on swallowing, and there was no significant difference between the two. In horizontal plane, however, mandible was displaced more anteriorly in both swallowing position and tapping position with splint. 2. In forward head posture, the mandible was less raised with splint on swallowing, but features in horizontal plane were almost same as those in normal head posture. 3. In natural dentition, significant difference between NHP and FHP were observed in horizontal plane trajectory for swallowing and tapping position. But the difference for same positions were observed in frontal trajectory with splint. 4. Total amount of mandibular movement of two groups classified with sagittal interocclusal distance of swallowing position generally showed significant difference between the higher and the lower height group in head posture without splint. 5. Correlationship among total amount of mandibular movement for three mandibular planes were observed between sagittal plane and horizontal plane, and between sagittal plane and frontal plane in head posture without splint.

• 대한의용생체공학회:의공학회지
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• 제31권3호
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• pp.240-244
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• 2010

The purpose of this study is to compare finger tapping (FT) movement of patients with Parkinson's disease (PD) with normal subjects. A gyrosensor system was used for the measurement of FT movement, because it provides angular velocity free from the gravitational artifact and it can be used during clinical FT test listed in unified PD rating scale (UPDRS). Forty PD patients (age: 65.7 ${\pm}$ 11.1 yrs, H&Y stage:2.3 ${\pm}$ 0.5), 14 age-matched elderly subjects (65${\pm}$3.9 yrs) and 17 healthy young subjects (24${\pm}$2.1yrs) participated in this study. Angular velocity of finger tapping movement was measured in both right and left index finger. As quantitative measures, root-mean-squared (RMS) angular velocity, RMS angle, peak power and total power were used. ANOVA showed that all measures were significantly different among three groups (p<0.001) in all quantitative measures. Post-hoc test revealed that all quantitative measures except peak power in patients with PD were significantly smaller than in both healthy elderly and young subjects (p<0.01). This suggests that the measures developed in this study can distinguish patients with PD from normal subjects.

• 한국인터넷방송통신학회논문지
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• 제19권6호
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• pp.153-160
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• 2019

본 논문은 손가락의 운동능력을 개선시킬 수 있는 재활 기기와 콘텐츠를 구현함으로서 누구나 편리하고 재미있게 재활 훈련을 할 수 있도록 돕고자 한다. 그래서 손가락의 조절 능력, 정밀도, 민첩성을 측정할 수 있는 Finger Tapping Device를 제작하고, 이 기기를 사용할 수 있는 콘텐츠로 트래킹, 시각 반응, 손가락 조절을 구현하였다. 이에 대한 유용성 검증은 손가락 움직임에 가장 많이 관여하는 심지굴근에 sEMG를 부착한 후 3종류의 콘텐츠를 수행하는 동안 sEMG의 신호를 분석하여 확인하였다. 실험 결과로서 모든 콘텐츠 수행하는 동안 심지굴근의 근육 활성화가 이루어졌다. 또한 시각 반응에 따른 각 손가락 별 반응 시간을 측정하여 민첩성의 차이가 있음을 확인할 수 있었다.

• 한국컴퓨터정보학회논문지
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• 제17권3호
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• pp.113-120
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• 2012

기존의 IP 망을 이용하여 음성 데이터 서비스를 제공하는 VoIP는 최근 많은 관심을 받고 있다. VoIP 서비스는 다양한 보안 취약성을 포함한다. VoIP 서비스의 주요 공격 유형으로는 도 감청, DoS 공격, 스팸, 서비스 오용 공격 등을 들 수 있다. 이 중에서 도 감청으로 인한 기밀 정보의 유출은 매우 중요한 문제로 다루어지고 있다. VoIP 미디어 정보에 대한 도 감청 방지를 위해 SRTP나 ZRTP와 같은 암호화 기법이 주로 사용되고 있다. 일반적으로 VoIP 서비스는 단일 사설망 내에서의 운용과 서로 다른 사설망간의 운용으로 구분할 수 있는데, SRTP나 ZRTP는 단일 사설망 내에서의 통신 시에는 VoIP 미디어 정보를 암호화 한다. 그러나 두 가지 방법 모두 서로 다른 사설망간의 통신 시에는 암호화를 수행하지 못하는 문제를 가지고 있다. 이러한 문제를 해결하기 위해 본 논문에서는 기존의 SRTP 프로토콜의 일부를 수정하여 서로 다른 사설망간의 통신 시에도 VoIP 미디어 정보에 대한 암호화를 수행할 수 있는 암호화 기법을 제안한다.

• 대한치과보철학회지
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• 제40권6호
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• pp.560-571
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• 2002

Jaw relations and the recording methods have been controversial aspects of dentistry. The purpose of this study was to quantify the relative muscle activity of the masseter and temporal muscles in relation to different intermaxillary relations recorded by intra-oral tracer during maximal clenching and to decide the optimal mandibular position. Ten volunteers with healthy TMJ were studied. Intra-oral tracer was assembled and bite block was fabricated in the articulator. Intra-oral tracer was placed in the mouth, and four mandibular positions were recorded. EMG activity was recorded on a BIO-PAK system (Bio-Research Associates, Inc. USA.) in masseter and temporal muscle and compared in each mandibular positions. The results were as follows: 1. In comparison with maximum intercuspation, the chewing position was the most similar followed by tapping position, myocentric position and posterior border position. However the differences were not statistically significant. 2. In comparison of bilateral symmetry of masseter muscle, tapping position was the most symmetrical followed by chewing position and maximum intercuspation. Myocentric position and posterior border position were not symmetrical. (P<.05). 3. In comparison of bilateral symmetry of anterior temporal muscle, chewing position was the most symmetrical followed by posterior border position, maximum intercuspation, myocentric position and tapping position. However the differences were not statistically significant. 4. In comparison of proportionality of anterior temporal muscle to masseter muscle activity on left side, posterior border position was the greatest followed by myocentric position, taping position, chewing position and maximum intercuspation. And the proportionality of posterior border position was greater than that of maximum intercuspation. (P<.05). 5. In comparison of proportionality of anterior temporal muscle to masseter muscle activity on right side, myocentric position was the greatest followed by posterior border position, tapping position, maximum intercuspation and chewing position. However the differences were not statistically significant.

• 전기학회논문지
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• 제59권11호
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• pp.2114-2118
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• 2010

The purpose of this study was to analyze bradykinesia of toe tapping movement in patients with Parkinson's disease (PD) as compared to those of normal subjects. 39 PD patients (age: $65.5{\pm}11.2$ yrs, H&Y stage:$2.3{\pm}0.5$), 14 eldelry subjects with comparable mean age ($65.0{\pm}3.9$ yrs) and 17 healthy young subjects ($24.1{\pm}2.1$ yrs) participated in this study. Angular velocity during repetitive toe tapping movement was measured in both feet using a gyro sensor system. Suggested quantitative measures of bradykinesia were root-mean-squared (RMS) angular velocity, RMS angle, peak power and total power which were derived from the angular velocity signal. ANOVA showed that all measures were significantly different among three groups (p<0.001). Subsequent post-hoc test revealed that all measures in PD patients were significantly smaller than in healthy elderly and healthy young subjects (p<0.02). All measures were significantly correlated with UPDRS scores(r=-0.689~-0.825). These results suggest that the developed system can be used as quantitative measures of the lower limb bradykinesia in PD patients.