• 대한기계학회논문집
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• 제12권3호
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• pp.505-512
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• 1988

본 연구에서는 상술한 $\boxDr$한계정유길이$\boxUl$를 찾아내는 것을 주요수단으로 하여, 그 전파 하한계응력으로서의 피로한도와의 관계를 정량적으로 검토하고, 미소크랙전파 거동이 미시조직 또는 피로부하이력등에 민감함을 감안하여, 이들 인자가 미소크랙 전 파의 하한계조건에 미치는 영향에 관하여 검토하기로 하였다.

• Bulletin of the Korean Chemical Society
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• 제16권9호
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• pp.801-803
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• 1995

• The Korean Journal of Physiology and Pharmacology
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• 제12권6호
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• pp.299-306
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• 2008

Sometimes, spinal cord injury (SCI) results in various chronic neuropathic pain syndromes that occur diffusely below the level of the injury. It has been reported that behavioral signs of neuropathic pain are expressed in the animal models of contusive SCI. However, the observation period is relatively short considering the natural course of pain in human SCI patients. Therefore, this study was undertaken to examine the time course of mechanical and cold allodynia in the hindpaw after a spinal cord contusion in rats for a long period of time (30 weeks). The hindpaw withdrawal threshold to mechanical stimulation was applied to the plantar surface of the hindpaw, and the withdrawal frequency to the application of acetone was measured before and after a spinal contusion. The spinal cord contusion was produced by dropping a 10 g weight from a 6.25 and 12.5 mm height using a NYU impactor. After the injury, rats showed a decreased withdrawal threshold to von Frey stimulation, indicating the development of mechanical allodynia which persisted for 30 weeks. The withdrawal threshold between the two experimental groups was similar. The response frequencies to acetone increased after the SCI, but they were developed slowly. Cold allodynia persisted for 30 weeks in 12.5 mm group. The sham animals did not show any significant behavioral changes. These results provide behavioral evidence to indicate that the below-level pain was well developed and maintained in the contusion model for a long time, suggesting a model suitable for pain research, especially in the late stage of SCI or for long term effects of analgesic intervention.

• 대한기계학회논문집
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• 제12권2호
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• pp.271-277
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• 1988

본 연구에서는 항공기, 압력용기 및 지상운송차량 등에 고강도와 용접성이 요구되는 고강도 알류미늄합금 7017T651, 7020T651 및 5083 H115에 대해 균열진전 하한계특성 및 안정 균열진전 하한계특성에 미치는 영향을 고찰 하고자 한다.

• 대한기계학회논문집A
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• 제31권6호
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• pp.686-693
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• 2007

To perceive body movement, the nervous system uses multi-sensory cues such as vision, vestibular signals, and somatosensation. Among the multi-sensory modality, the previous researchers reported that the lower limb somatosensation plays an important role on maintaining postural balance. In this study, we examined the contribution of somatosensory cues to linear motion perception by measuring the detection threshold of the direction of linear motion with and without lower limb somatosensory constraints. Six healthy male volunteers participated in randomly ordered 33 single sinusoidal acceleration trials with the stimulus at 0.25Hz with peak magnitude ranged from 0 to 8mG. After each stimulus, subjects reported their perceived direction of motion by button press. Results showed that the reduced lower limb somatosensation significantly increased perception threshold. Without constraints, mean threshold was $0.82{\pm}0.23mG$, while it was $1.23{\pm}0.35mG$ with reduced lower limb somatosensation. The results suggest that without visual cues, perception of the movement direction strongly depends on the lower limb somatosensory information.

• 한방안이비인후피부과학회지
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• 제12권1호
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• pp.143-153
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• 1999

Background: The vasoreactivity of cerebral artery is currently the subject of increasing interest Transcranial Doppler The purpose of this study was to investigate the analgesic effect of acupuncture in a model of neuropathic pain produced by segmental spinal nerve injury (SSI) in rats. The left L5 and L6 spinal nerves of Sprague-Dawley rats were tightly ligated, and one week later, manual or electro-acupuncture was applied for 30 minutes to the contralateral hindlimb (right side) while the animal was lightly anesthetized with halothane. The mechanical threshold of the paw for ipsilateral (left side) hind limb flinching was determined prior to and 0.5, 1, 2, 4, and 24 hours after termination of acupuncture. The mechanical threshold for flinching was significantly elevated for about 4 hours after manual acupuncture applied to the BL. 60 (Kunlun) point or electro-acupuncture to the BL. 60 and BL. 40 (Weizhong) points. However, manual acupuncture applied to the ST. 36 (Zusanli) point was not effective. Furthermore, systemic naloxone pretreatment had no effect on the acupuncture induced threshold elevation. These data suggests that acupuncture produces a point specific, naloxone independent analgesia in a rat neuropathic pain model. ※ This paper is supported by a grant from the '1996 Jusan Foundation of Wonkwang university.)

• 대한기계학회논문집
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• 제13권5호
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• pp.938-946
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• 1989

본 연구에서는 CT시험편을 이용하여 소규모 항복조건하에서 하한계(near threshold)영역과 안전균열성장(제II)영역의 균열진전거동을 파악하고 피로균열 진전속도와 음향방출거동, 파단면 특성을 각각 비교, 고찰하여 각 파라미터간의 상관 관계 및 유용성을 검토하고자 한다.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.721-727
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• 2013

본 연구는 모음에 따라 발성역치압력과 비성도의 차이를 비교하고자 하였다. 2012년 5월부터 8월 동안에 대학에 재학 중인 20~30대의 정상성인 여성 28명을 대상으로 실시하였다. 발성역치압력은 객관적인 공기역학적 검사도구인 PAS(Phonatory aerodynamic system, model 6600, KAY electronics, Inc)를 이용하였으며, /p/와 세가지 모음 /a, i, u/를 각 5번씩 측정하여 가운데 3개를 비교하여 분석하였다. 또한 비성도는 Nasometer${\Pi}$(model 6450, KAY electronics, Inc)를 이용하였으며, 세가지 모음 /a, i, u/를 5초 이상 연장발성하여 측정하였다. 그 결과, 모음에 따른 발성역치압력은 유의한 차이를 나타내었으며, 모음에 따른 비성도도 유의한 차이를 보였다. 발성역치압력과 비성도간의 상관관계도 매우 높은 상관성을 나타내었다. 따라서 모음간의 발성역치압력은 연인두 폐쇄정도를 예측할 수 있으며 그에 따른 비성도와 매우 연관성이 깊음을 알 수 있었다.

• Macromolecular Research
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• 제14권4호
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• pp.456-460
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• 2006

The electrical, morphological, and mechanical properties of poly carbonate (PC)/multi-walled carbon nan-otube (MWNT) composites were studied by electrical conductivity, electromagnetic interference shielding efficiency (EMI SE), scanning electron microscopy, and tensile strength measurements. In the electrical property analysis of the PC/MWNT composites, the percolation threshold of the PC/MWNT composites was observed between 1.5 and 2.5 wt% MWNT content. From the electrical conductivity and EMI SE studies, the theoretical values of the EMI SE were in good agreement with the experimental values of the EMI SE. From the morphology of the PC/MWNT composites, it was observed that MWNT is dispersed homogenously in the PC matrix. From the electrical conductivity and morphological studies, it was suggested that the percolation threshold of the PC/MWNT composites is related with the morphological results in that MWNT is apparently interconnected to form an electrical pathway. The mechanical properties of the PC/MWNT composites peaked at the MWNT content of 2.5 wt%.

• Current Optics and Photonics
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• 제7권4호
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• pp.387-397
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• 2023

Tooth surface shape error is an important parameter in gear accuracy evaluation. When tooth surface shape error is measured by laser interferometry, the gear interferogram is highly distorted and the gray level distribution is not uniform. Therefore, it is important for gear interferometry to extract the foreground region from the gear interference fringe image directly and accurately. This paper presents an approach for foreground extraction in gear interference images by leveraging the sinusoidal variation characteristics shown by the interference fringes. A gray level mask with an adaptive threshold is established to capture the relevant features, while a local variance evaluation function is employed to analyze the fluctuation state of the interference image and derive a repair mask. By combining these masks, the foreground region is directly extracted. Comparative evaluations using qualitative and quantitative assessment methods are performed to compare the proposed algorithm with both reference results and traditional approaches. The experimental findings reveal a remarkable degree of matching between the algorithm and the reference results. As a result, this method shows great potential for widespread application in the foreground extraction of gear interference images.