• Journal of Welding and Joining
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• 제25권6호
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• pp.71-77
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• 2007

Until now, many researches on laser-arc hybrid welding processes have been conducted mainly for high power CW laser and high direct current arc to weld the thick steel plates for shipbuilding. Recently, however the usage of thin steel plates, which tend to be deformed easily by thermal energy, is been increasing because of demand of light structure such as car body in the automobile industry. Accordingly, heat sources having relatively low heat input such as pulsed laser, dip-transfer DC GMA and pulsed GMA seem to be applied more increasingly and the study about those heat sources is needed more intensively. Any heat source mentioned above can not stand alone without weld defects at a relatively high welding speed for increasing the welding productivity. This is main reason to apply the hybrid welding process which uses pulsed laser and low-heat-input GMA heat sources simultaneously to weld the thin steel plate. In this study, parameters of pulsed laser and dip-transfer DC GMA welding are studied firstly through preliminary experiments, and then analyzed in the viewpoint of their physical phenomena. Before conducting the hybrid welding, a pulse control technique is developed based on the parallel port communication and Visual C++ 6.0. Owing to development of this technique, interactions of laser and arc pulses can be controlled consistently. Using the pulse control technique, the hybrid welding is conducted and then its interactive welding phenomenon is analyzed.

• 태양에너지
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• 제18권2호
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• pp.123-135
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• 1998

자연대류에서 정사각형 밀폐공간의 중앙에 고립된 전도성 장애물이 들어 있을 때 열전도도의 효과를 수치해석적으로 연구하였다. Pr=0.17, $Ra=1.0{\times}10^4,\;1.0{\times}10^5,\;1.0{\times}10^6$, 유체와 전도체의 열전도율비인 $K^*$=1.0, 6.6, 34.0 그리고 전도성 장애물의 비 ${\zeta}$=0.5,1.0,2.0에서 수치연구를 수행하였다. 그 결과들은 유선, 등온선 그리고 Nusselt수로 나타내었다. Ra and $K^*$ 값이 일정한 상태에서 평균 Nusselt수가 증가함에 따라 ${\zeta}$ 가 증가하였다. ${\zeta}=1.0$(장애물의 형상비)일 경우 Rayleigh수에 관계없이 $K^*$(장애물의 열전도율비)가 증가할수록 평균 Nusselt수는 감소한다. 장애물의 크기와 열전도율비가 동일할 때 대류열전달 효과는 ${\zeta}=0.5$인 경우보다 ${\zeta}=2.0$일 때 더 향상되었다.

• 대한한방내과학회지
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• 제39권4호
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• pp.495-510
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• 2018

Objective: This study was designed to investigate the possibility of quantification of the diagnosis of abdominal coldness (AC) in patients with functional dyspepsia (FD). Methods: Forty-four patients with FD were enrolled in this study. Three Korean medicine doctors each randomly examined all abdomens. Diagnosis of AC was made by consensus of at least two of the doctors. Body temperature (oral by digital oral thermometer) and skin temperature (by digital infrared thermal imaging [DITI]) were measured, followed by administration of the Cold and Heat questionnaire (CHQ) and the Instrument of Pattern Identification for Functional Dyspepsia (IPIFD). Results: Of the 44 patients with FD, 22 were assigned to the AC group and 22 to the non-AC group. The concordance rate of diagnosis among the three doctors was 63.6% (28/44), with a ${\kappa}$ of 0.504, indicating means moderate agreement). Neither the oral nor the skin temperatures showed statistically significant differences between the AC and non-AC groups. However, the CHQ scores and 'Simultaneous Occurrence of Cold and Heat Syndromes pattern' scores of the IPIFD were higher in AC group and showed statistically significant differences (p=0.010 and 0.009). Conclusions: This is the first study conducting quantitative measurements of abdominal coldness in patients with FD. Although oral and skin temperature showed no statistical significance between AC and non-AC groups, the concordance rate of diagnosis of AC among the three Korean Medicine doctors was moderate. The CHQ scores and 'Simultaneous Occurrence of Cold and Heat Syndromes pattern' scores of the IPIFD also suggest that diagnosis of AC is relevant to cold and heat patterns, and these questionnaires could be utilized as supportive data for the diagnosis of AC. Further studies should be conducted for the purpose of quantifying and standardizing abdominal examinations in Korean Medicine.

• 한국정보통신학회논문지
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• 제13권5호
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• pp.1008-1013
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• 2009

본 논문에서는 피실험자의 체온, 맥박, 호흡수, 혈압을 수집할 수 있는 무선 센서를 이용하여 수집된 생체 신호를 분석하는 시스템을 제안하였으며, 생체 신호를 분석하기 위하여 전문가 시스템을 사용하여 역전파 신경망을 설계 하였다. 제안된 시스템은 하드웨어 (UStar-2400 ISP, UStar-2400, Wireless sensors) 부분과 소프트웨어 부분 (Knowledge Base module, Inference Engine module, User Interface module)으로 구성되며 소프트웨어 부분은 HOST PC에 삽입된다. 그리고 시스템의 정확도를 개선하기 위하여 전방향 에러 정정 시스템(LDPC)을 구현하였다. 지식기반 모듈에서 100개의 데이터 집합을 사용하여 역전파 신경망을 훈련하였으며, 지식기반 모듈의 128개의 데이터 집합을 사용하여 실험한 결과 약 95%의 정확도를 가졌으며, 무선 센서를 사용하여 13명의 학생을 대상으로 실험한 결과 약 85%의 정확도를 획득하였다.

• Molecules and Cells
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• 제20권3호
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• pp.315-324
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• 2005

Pain is an unpleasant sensation experienced when tissues are damaged. Thus, pain sensation in some way protects body from imminent threat or injury. Peripheral sensory nerves innervated to peripheral tissues initially respond to multiple forms of noxious or strong stimuli, such as heat, mechanical and chemical stimuli. In response to these stimuli, electrical signals for conducting the nociceptive neural signals through axons are generated. These action potentials are then conveyed to specific areas in the spinal cord and in the brain. Sensory afferent fibers are heterogeneous in many aspects. For example, sensory nerves are classified as $A{\alpha}$, $-{\beta}$, $-{\delta}$ and C-fibers according to their diameter and degree of myelination. It is widely accepted that small sensory fibers tend to respond to vigorous or noxious stimuli and related to nociception. Thus these fibers are specifically called nociceptors. Most of nociceptors respond to noxious mechanical stimuli and heat. In addition, these sensory fibers also respond to chemical stimuli [Davis et al. (1993)] such as capsaicin. Thus, nociceptors are considered polymodal. Recent advance in research on ion channels in sensory neurons reveals molecular mechanisms underlying how various types of stimuli can be transduced to neural signals transmitted to the brain for pain perception. In particular, electrophysiological studies on ion channels characterize biophysical properties of ion channels in sensory neurons. Furthermore, molecular biology leads to identification of genetic structures as well as molecular properties of ion channels in sensory neurons. These ion channels are expressed in axon terminals as well as in cell soma. When these channels are activated, inward currents or outward currents are generated, which will lead to depolarization or hyperpolarization of the membrane causing increased or decreased excitability of sensory neurons. In order to depolarize the membrane of nerve terminals, either inward currents should be generated or outward currents should be inhibited. So far, many cationic channels that are responsible for the excitation of sensory neurons are introduced recently. Activation of these channels in sensory neurons is evidently critical to the generation of nociceptive signals. The main channels responsible for inward membrane currents in nociceptors are voltage-activated sodium and calcium channels, while outward current is carried mainly by potassium ions. In addition, activation of non-selective cation channels is also responsible for the excitation of sensory neurons. Thus, excitability of neurons can be controlled by regulating expression or by modulating activity of these channels.