• 한국방재학회 논문집
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• 제11권1호
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• pp.45-49
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• 2011

본 연구에서는 소방방화복의 무게가 최대 신체활동 후 신체의 평형성과 민첩성에 미치는 영향을 조사하여 소방공무원의 안전을 위한 기초자료 제공을 목적으로 한다. 신체의 정적평형성 평가를 위하여 눈감고 한발로 서기와 동적평형성 평가로는 평균대 걷기를 실시하였으며, 신체의 정적민첩성 평가는 전신반응검사 동적민첩성 평가는 반복 옆뛰기를 실시하였다. 연구결과 최대 지친 상태에서 소방방화복의 무게는 신체의 정적평형성과 동적민첩성에 영향을 미치는 것으로 나타났으며 향후 소방공무원의 안전을 위한 실제적인 연구에 유용할 것으로 판단된다.

• 한국운동역학회지
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• 제19권1호
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• pp.49-58
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• 2009

본 연구는 여자대학 체조선수 3명을 대상으로 평균대의 좌측 턴 동작 시 성공과 실패에 따른 동적 자세조절에 미치는 신체중심(C.O.G) 변화와 안구 움직임(E.O.G)의 관계를 분석하는데 목적이 있다. 성공 시 몸통이 $180^{\circ}$ 회전하는 시점까지 C.O.G는 회전방향으로 이동되는 경향이었으며, 실패 시에도 동일한 경향이 나타났지만 C.O.G의 편차가 상대적으로 큰 이동을 보여 동적 자세 조절 유지에 영향을 미치는 특징이 있었다. 회전 동작 시 E.O.G는 몸통의 회전 방향과 안구가 반대로 이동한다는 사전 이론과 일치하였지만 중심이동 시점에서는 차이가 있었으며 동작의 성패에서는 확연한 차이가 나타났다. 또한 실패 시 상-하 E.O.G는 대부분이 하 방향으로 작용하는 특성을 나타내고 있어서 실패의 원인과의 연관성을 분석할 필요를 느꼈다. 따라서 평균대 턴 동작에서 동적 자세 조절능력과 E.O.G의 운동역학적인 후속연구가 심층적으로 수행된다면 미세한 원인을 규명할 수 있을 것으로 사료된다.

• 한국운동역학회지
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• 제18권3호
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• pp.61-69
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• 2008

본 연구는 평균대에서 필수요구조건(EGR)에 해당되는 동작인 옆공중돌기 동작의 성공과 실패를 운동역학적으로 비교 분석하였다. 연구대상은 국가대표 선수들로 하였으며, 연구의 목적은 기술의 실수 요인을 규명하여 지도자 및 선수들에게 과학적으로 유용한 정보를 제공하는데 있다. 성공시 옆공중돌기 동작의 신체중심은 평균대 중앙 중심으로 좌-우축으로 벗어나는 결과가 나타나고 동작의 특성상 회전하는 방향으로 신체중심이 이동한다는 것을 나타내고 있다. 도약구간인 event2와 3에서 성공시 상 하 변화가 크게 나타나 체공시간을 높이는 것으로 투사변인이 실패시 보다 높게 나타나는 결과를 뒷받침 해 주고 있다. 또한 공중 비약을 위해 다리를 차는 동작을 하는 오른쪽 고관절 각도와 속도, 각속도가 실패시 보다 성공시 동작에서 모두 크게 나타나 도약의 최적조건을 수행하고 있다. 어깨를 중심으로 상지분절의 속도와 견관절 각속도를 크게 함으로써 운동량을 증가시켰으며 그중 오른쪽 견관절 각속도가 크게 나타난 이유는 오른쪽 다리를 잡기 위한 결과이다. 옆 공중돌기 동작에서 실패시 보다 성공시 동작에서 x축을 중심으로 각운동량이 크게 나타나 공중 비행 동작은 x축을 중심으로 각운동량을 크게 하는 것이 중요한 요인으로 나타났으며 옆공중돌기 특성상 y축과 z축으로 각운동량도 적정한 비율로 동작이 이루어져야 성공적인 동작을 만들수 있다.

• 대한본초학회지
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• 제27권6호
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• pp.71-76
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• 2012

Objectives : The purpose of this study was to evaluate the neuroprotective effect of Pueraria lobata extract on focal cerebral ischemia in mice. Methods : Focal cerebral ischemia was induced by occlusion of the right middle cerebral artery using the intraluminal filament model. ICR male mice underwent 90 minutes of middle cerebral artery occlusion (MCAo) followed by 24 hours of reperfusion. Mice were administered Pueraria lobata extract orally at the dose of 300mg/kg just prior to reperfusion. Rotarod test and balance beam test were practiced to assess sensory-motor function 23 hours after MCAo. In rotarod test, the latency to fall on the accelerating rotarod was recorded for 5 min. In balance beam test, the score was graded according to number of slips and latency to cross. The infarct volume was measured 24 hours after MCAo using 2% 2,3,5-triphenyltetrazolium chloride (TTC) staining. Results : Pueraria lobata extract treated group showed significant reduction in infarct volume by 27.3% compared to control group (p<0.05). In rotatod test, it also showed significant extension of latency time compared to control group ($67.82{\pm}15.08$ vs. $5.62{\pm}1.06$, p<0.001). In contrast to performance in rotarod test, that in balance beam test did not improve with Pueraria lobata extract treatment. Conclusions : We conclude that Pueraria lobata extract has a significant neuroprotective effect and reduces damage of sensory-motor function in MCAo model. These findings suggest that Pueraria lobata could be a potent neuroprotective agent.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.284-287
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• 2001

This paper presents the robust control simulation of a composite beam using self-sensing actuators(SSA). The self-sensing actuator is a new concept for intelligent material, where a single piezoelectric element simultaneously functions as both a sensor and an actuator. In a practical implementation of the self-sensing actuator an electrical bridge circuit is used to measure strain. The circuit could provide significant information about strain in the element if it were well-balanced. Our aim is design a robust controller which guarantees that the performance of a self-sensing actuator is robust against perturbation of the bridge balance and to confirm the advantages of this technique. Simulation results show that the self-sensing actuator driven by the designed controller exhibits excellent performance in suppressing the vibration of a composite beam.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1779-1781
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• 1997

The 2.0 GeV Pohang Light Source (PLS) is consisted of a full energy Linac and a storage ring. Four kicker magnets are installed in the storage ring tunnel to move the stored beam orbit in the storage ring closer to the injected beam from the beam transfer line. The injected beam then falls into the storage ring beam dynamic aperture. A kicker magnet modulator drives all four kicker magnets to maintain field balance and also synchronized kick of the beam. The kicker modulator can handle 2 GeV full energy beam. The kicker magnet modulator is installed in the storage ring tunnel and under stable operation. Specification of the kicker magnet modulator is ${\sim}6.0{\mu}s$ pulse-width, 200 ns flat-top width with ${\pm}0.2%$ regulation, ${\sim}24\;kA$ peak current, and 10 Hz repetition rate. Two thyratron switches (EEV CX-1536AX) are used in the system. In this article, design, and experimental results of the kicker magnet modulator are discussed.

• 한국표면공학회지
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• 제37권4호
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• pp.220-225
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• 2004

A new ion beam extraction system is designed using a simple ion mass filter and a micro mass balance and a QMS based detecting system. A quadrupole Mass Filter is used for selective ion beam formation from inductively coupled high density plasma sources with appropriate electrostatic lens and final analyzing QMS. Also a quartz crystal microbalance is set between a QMF and a QMS to measure the etching and polymerization rate of the mass selected ion beam. An inductively coupled plasma was used as a ion/radical source which had an electron temperature of 4-8 eV and electron density of $4${\times}$10^{11}$＃/㎤. A computer interfaced system through 12bit AD-DA board can control the pass ion mass of the qmf by setting RF/DC voltage ratio applied to the quadrupoles so that time modulation of pass ion's mass is possible. So the direct measurements of ion - surface chemistry can be possible in a resolution of $1\AA$/sec based on the qcm's sensitivity. A full set of driving software and hardware setting is successfully carried out to get fundamental plasma information of the ICP source and analysed $Ar^{+}$ beam was detected at the $2^{nd}$ QMS.

• Structural Engineering and Mechanics
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• 제5권3호
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• pp.257-268
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• 1997

The elastic deflections and Euler buckling loads are investigated for a class of tapered and initially curved cantilevered beams subjected to loading at the tip. The beam's width increases linearly and its depth decreases linearly with the distance from the fixed end to the tip. Unloaded, the beam forms a circular are perpendicular to the axis of bending. The beam's deflection responses, obtained by solving the differential equations in closed form, are presented in terms of four nondimensional system parameters: taper ratio ${\kappa}$, initial shape ratio ${\Delta}_0$, end load ratio f, and load angle ${\theta}$. Laboratory measurements of the Euler buckling loads for scale models of tapered initially straight, corrugated beams compared favorably with those computed from the present analysis. The results are applicable to future designs of the end structures of highway guardrails, which can be designed to give the appropriate balance between the capacity to deflect a nearly head-on vehicle back to its right-of-way and the capacity to buckle sufficiently that penetration of the vehicle may be averted.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
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• pp.185-190
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• 1995

In recent years, many researcher have been interested in the stability of a thin beam. Among them, Pai and Nayfeh[1] had investigated the nonplanar motion of the cantilever beam under lateral base excitation and chaotic motion, but this study is associated with internal resonance, i.e. one to one resonance. Also Cusumano[2] had made an experiment on a thin beam, called Elastica, under bending loads. In this experiment, he had shown that there exists out-of-plane motion, involving the bending and the torsional mode. Pak et al.[3] verified the validity of Cusumano's experimental works theoretically and defined the existence of Non-Local Mode(NLM), which is came out due to the instability of torsional mode and the corresponding aspect of motions by using the Normal Modes. Lee[4] studied on a thin beam under bending loads and investigated the routes to chaos by using forcing amplitude as a control parameter. In this paper, we are interested in the motion of a thin beam under torsional loads. Here the form of force based on the natural forcing function is used. Consequently, it is found that small torsional loads result in instability and in case that the forcing amplitude is increasing gradually, the motion appears in the form of dynamic double potential well, finally leads to complex motion. This phenomenon is investigated through the poincare map and time response. We also check that Harmonic Balance Method(H.B.M.) is a suitable tool to calculate the bifurcated modes.

• Structural Engineering and Mechanics
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• 제73권3호
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• pp.287-302
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• 2020

This investigation deals with a size-dependent coupled thermoelasticity analysis based on Green-Naghdi (GN) theory in nano scale using a new modified nonlocal model of heat conduction, which is based on the GN theory and nonlocal Eringen theory of elasticity. In the analysis based on the proposed model, the nonlocality is taken into account in both heat conduction and elasticity. The governing equations including the equations of motion and the energy balance equation are derived using the proposed model in a nano beam resonator. An analytical solution is proposed for the problem using the Laplace transform technique and Talbot technique for inversion to time domain. It is assumed that the nano beam is subjected to sinusoidal thermal shock loading, which is applied on the one of beam ends. The transient behaviors of fields' quantities such as lateral deflection and temperature are studied in detail. Also, the effects of small scale parameter on the dynamic behaviors of lateral deflection and temperature are obtained and assessed for the problem. The proposed GN-based model, analytical solution and data are verified and also compared with reported data obtained from GN coupled thermoelasticity analysis without considering the nonlocality in heat conduction in a nano beam.