• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1040-1043
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• 2006

Every mechanical system has a series of natural frequencies at which it will vibrate and to which it will respond if an external stimulus or excitation at this frequency is applied. Vibration is not of itself dangerous, and is always anticipated in an operating unit. However, if the frequency of operation is coincidental with one of the natural frequency of the blade system or the blade has a natural frequency near coincide with the exciting stimulus, then the amplitude of vibration of the blade may increase to the destructive damage can result. In this paper We investigated damage of blade when turbine operated.

• 대한기계학회논문집A
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• 제30권6호
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• pp.722-727
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• 2006

Bone fracture healing is one of the important topics in biomechanics, demanding computation simulations due to the difficulty of obtaining experimental or clinical results. In this study, we adopt the design space optimization method which was established by the authors as a tool for the simulation of bone growth using its evolutionary characteristics. As the mechanical stimulus, strain energy density is used. We assume that bone tissues over a threshold strain energy density will be differentiated and bone tissues below another threshold will be resorbed. Under compression and torsion as loadings, the filling process of the defect is well illustrated following the given mechanical criterion. It is shown that the design space optimization is an excellent tool for simulating the evolutionary process of bone growth, which has not been possible otherwise.

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1183-1194
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• 2006

The aim of this study was to identify the characteristics of the flexion withdrawal reflex modulated by the hip angle and hip movement in spinal cord injury (SCI). The influence of the hip position and passive movement were tested in 6 subjects with chronic SCI. Each subject placed in a supine position and lower leg was fixed with the knee at 5 -45 degree flexion and the ankle at 25-40 degree plantar flexion. A train of 10 stimulus pulses were applied at 200 Hz to the skin of the medial arch to trigger flexion reflexes. From results of the regression analysis, static properties of normalized muscle activation of flexor muscles have the linear relationship with respect to hip angle (P< 0.05). In order to verify the neural contribution of flexion reflex, we compared the static and dynamic gains of estimated muscle activations with measured EMG of ankle flexor muscle. Form this study, we postulate that the torque and muscle response of flexion withdrawal reflex have linear relationship with hip angle and angular velocity.

• 대한의용생체공학회:의공학회지
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• 제33권2호
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• pp.98-103
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• 2012

The purpose of this study was to compare premotor time(PMT) and electro-mechanical delay(EMD) between sitting and standing posture. Twenty four healthy young subjects(12 women and 12 men) participated in this study. Subjects were instructed to perform maximal, voluntary, isometric contraction of ankle muscle(tibialis anterior and gastrocnemius muscles) in reaction to auditory stimulus. PMT and EMD, calculated from stimulus, EMG and torque profile were compared between sitting and standing postures. As statistical analysis, paired t-test was performed to assess difference between sitting and standing posture. In both tibialis anterior and gastrocnemius muscles, EMD was found to be significantly longer for standing than sitting. However, PMT in standing posture was longer than that in sitting posture only in gastrocnemius muscles. These result indicate that increased reaction time, particularly, increased EMD of ankle muscles in standing posture may be caused by co-contraction of ankle muscles for postural control in standing posture.

• The Korean Journal of Physiology
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• 제24권2호
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• pp.305-317
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• 1990

The present study was performed to investigate modification in the electrophysiological characteristics of cat dorsal horn cells during neurogenic inflammation induced by mustard oil. The results obtained were summarized as follows: 1) Following subcutaneous injection of mustard oil the majority of wide dynamic range (WDR) cells (10/15 units) showed enhanced responses (80%) to brush, while the responses to all types of mechanical stiumli were enhanced in 3/15 units. One cell was further activated by pinch and the another was not affected at all after induction of inflammation. 2) The sensitization of WDR cell was resulted from subcutaneous injection of mustard oil either inside or outside of the receptive field (RF), whereas the spontaneous activity increased only after mustard oil was injected inside of the RF. 3) In the animal with inflammation the responses of high threshold (HT) cell to noxious stimulus were not altered, while HT cell responded to such mechanical stimulus as pressure which was usually ineffective in normal animals. 4) After induction of inflammation, low threshold (LT) cell appeared to be converted to WDR cell, showing responses not only to brush but also to pressure and pinch. 5) The mustard oil-induced inflammation enhanced responses of WDR and HT cells to the thermal stimuli and also resulted in a pronounced after-discharge in WDR cells. 6) After subcutaneous injection of lidocaine, the increased background activity of WDR cells due to inflammation was almost completely abolished. 7) A subcutaneous injection of mustard oil inside of the RF invariably desensitized the dorsal horn cells which receive sensory inputs from the inflamed RF. From the results of Present study it was revealed that a neurogenic inflammation induced by mustard oil resulted in an enhancement of responses of cat dorsal horn cells to mechanical and thermal stimuli.

• 유통과학연구
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• 제18권3호
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• pp.87-97
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• 2020

Purpose: The aim of this study is to understand the internal and external responses that consumers experience when they are exposed to an innovative system in retail stores. This study considered the SST(Self-Service Technology) system in a retail setting as a type of functional environmental stimuli and selected a smart shopping cart as an example of SST system. The influences of functional environmental stimuli on consumers' emotional, cognitive, and behavioral responses were examined by applying S-O-R model. In addition, this study attempted to extend the traditional S-O-R model by (a) incorporating personal characteristics variables such as time pressure and perceived crowding and (b) considering not only emotional but also cognitive aspects of consumers' internal responses. Research Design, Data, and Methodology: This study used a video-scenario technique. Participants watched a video about grocery shopping situations using a smart shopping cart and responded to their emotional, cognitive, and behavioral responses. An online survey was conducted using Amazon's Mechanical Turk (N = 185). All participants were US consumers over 20 years old and had been shopping at the grocery store in the last month. Data were analyzed through structural equations modeling with AMOS 20. Results: Test results showed that consumers who perceived higher levels of time pressure and perceived crowding in usual shopping situations were more likely to evaluate the SST system favorably. The results showed that personal characteristics have a significant impact on consumers' evaluation of functional environmental stimuli in retail setting. As consumers evaluated the SST system favorably, they experienced more positive affect and less negative affect during their shopping behaviors. Positive affect led to good service quality inference, which further increased patronize intention. However, negative affect did not show a significant impact on service quality inference, but only on patronize intention. Conclusions: This study attempted to investigate the influence of SST system by extending the traditional S-O-R model. This study classified the SST system as functional environmental stimulus of retail stores and analyzed the effect of stimulus on consumers' internal and external responses. The results of this study showed that the introduction of innovative SST can serve as an effective store differentiation strategy in an increasingly competitive retail environment.

• 한국의류학회지
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• 제24권3호
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• pp.429-439
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• 2000

This study was aimed to investigate the handle and mechanical properties of silk woven fabrics according to the fabric structure and yarn types 56 male and female students evaluated 16 black specimens with semantic differential scale of 20 hand adjectives. Mechanical parameters such as surface properties, bending properties and compression properties were tested using by KES-FS system. Data were analyzed through factor analysis, pearson correlation coefficient and t-test using PC SAS package. The results were as follows: The hand adjectives were grouped as 4 'surface roughness', 'flexibility', ;sense of thermal', and 'dryness'. 'Surface roughness' was highly sensed at satin fabrics of hard-twist yarn, noil yarn and spun yarn, while it was not at the fabrics of normal satin and twill at all. 'Flexibility' was reverse to 'surface roughness'. Thermal sense was felt highly at satin fabrics of noil-yarn, while low at plain fabrics of normal yarn. 'Dryness' was high at satin fabrics of hard-twist yarn and while it was low at normal satin fabrics. Predicted equations for subjective hand from mechanical properties of fabrics were developed using Stevens's law and stepwise regression and the coefficients of determination were high.

• 한국정밀공학회지
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• 제28권6호
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• pp.678-686
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• 2011

When one sensor cannot provide information by sensory deficit or loss, the sensory information can be provided by substituting other sensors for the defected sensor. This sensory substation might be influence on the deteriorated motion perception that consists of multi-sensory information such as visual, vestibular and somatosensory information. In this study, to investigate whether the additional sensation by sensory substitution could be integrated into the motion perception, we examined the effect of substituted postural sway sensation on the directional perception of body movement. Deteriorated motion perception by the reduced plantar sensation was enhanced under sensory substitution condition that provided the body sway information as the plantar vibratory stimulus. These results imply that the additional sensation might be integrated into and improve the motion perception.

• Tribology and Lubricants
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• 제32권2호
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• pp.39-43
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• 2016

Magnetorheological elastomers (MREs) are a type of “smart” material, and their properties can be controlled rapidly and reversibly under the influence of an external stimulus. The application of an external magnetic field can change the shear modulus, hardness, and friction coefficient of MREs. The friction can cause vibration; moreover, the vibration can affect friction. The change of friction depends on the relative motion, normal force, roughness of the rubbing surfaces, material type, temperature, lubrication, relative humidity, and vibration condition. As MREs are a type of “smart material,” their friction coefficient can be reduced by applying an external magnetic field—the applications of this feature in engineering have been widely studied. However, the friction properties of MREs under vibration have not been tested to date. In this study, MRE samples and a reciprocating friction tester were fabricated. The friction coefficient was measured to evaluate the friction properties under various vibration conditions; subsequently, the wear depth and wear surface profile of the MRE were observed in order to evaluate the wear properties. The results show that the friction coefficient of the MREs decreased when a magnetic field was applied. Moreover, the friction coefficient decreased when the vibrational amplitudes increased. The wear depth of the MRE also decreased as the vibrational amplitudes increased.

• 대한정형외과 초음파학회지
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• 제2권2호
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• pp.94-98
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• 2009

침술은 중국에서 3,000년 이상의 기원을 가진 가장 대중적인 보완대체의학 치료 방법으로 전세계적에서 널리 시행되고 있다. 초음파는 교육과 연구목적, 신경과 늑막과 같은 위험한 구조 주위 경혈에 침술을 시행할 때 도움이 된다. 또한 초음파는 조직에서 침 수기의 생 기계적 효과를 평가하는 데 이상적인 영상 검사로 조직 형태와 생 기계적 정보의 영상을 제공하는 특징적 장점을 가지고 있다. 탄성영상은 내부 혹은 외부에서 발생하는 기계적 자극에 의한 조직의 기계적 성질 혹은 반응을 정량화 할 수 있다. 그러므로 초음파와 탄성영상의 결합은 침술에 의한 인체 결합조직 구조의 동적변화를 정량적으로 평가할 수 있다.