• 제어로봇시스템학회논문지
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• 제15권7호
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• pp.683-687
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• 2009

Track jump control is a random access strategy for short distance movement. The most common track jump scheme is a bang-bang control of a kick and brake manner. In a conventional track jump scheme, a track-following compensator is turned off during kick and brake periods, and restarted at a target track for track pull-in. The inevitable controller switching with non-zero initial condition results in undesirable transient response, and excessive overshoot in the transient response causes track pull-in failure. In this paper, a new track jump scheme is proposed for enhancing track jump stability. Instead of control switching, internal states of a track-following controller are artificially manipulated for kick and brake actions in a digital control environment. Experimental results are provided in comparison with conventional track jumps.

• 대한기계학회논문집B
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• 제33권3호
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• pp.164-169
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• 2009

The slip velocity and the temperature jumps for low-speed flow in microchannels are investigated using Langmuir slip boundary condition. This slip boundary condition is suggested to simulate micro flow. The current study analyzes Langmuir slip boundary condition theoretically and it analyzed numerically micro-Couette flow, micro-Poiseuille flow and grooved microchannel flow. First, to prove validity for Langmuir slip condition, an analytical solution for micro-Couette flow is derived from Navier-Stokes equations with Langmuir slip conditions and is compared with DSMC and an analytical solution with Maxwell slip boundary condition. Second, the numerical analysis is performed for micro-Poiseuille flow and grooved microchannel flow. The slip velocity and temperature distribution are compared with results of DSMC or Maxwell slip condition and those are shown in good agreement.

• 대한기계학회논문집A
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• 제24권3호
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• pp.543-549
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• 2000

Results of theoretical investigations of the stability characteristics of an actively controlled externally pressurized air journal bearing are presented. Proportional control and derivative control are used for the control algorithm of active air bearing. The stability characteristics of the actively controlled bearing operating at zero steady-state eccentricity is investigated with the step jump method. The speed at onset of instability is raised for both proportional control and derivative control of bearing. Proportional control increased the stability threshold without affecting the whirl ratio. But for derivative control of bearing, stability threshold increase is accompanied by a parallel reduction of the whirl ratio. Results show active control of bearing can be adopted for the stability improvement of air journal bearing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.289-294
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• 2001

Three kinds of viscoelastic damper model, which has a non-linear spring as an element is studied analytically and numerically. The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by a non-linear constitutive equation and an additional equation of motion. Harmonic balance method is applied to get analytic solutions of the system. The frequency-response curves show that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurrences of such non-linear phenomena.

• 한국소음진동공학회논문집
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• 제12권1호
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• pp.57-64
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• 2002

Three kinds of viscoelastic damper model, which has a non-linear spring as an element is studied analytically and numerically The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by a non-linear constitutive equation and an additional equation of motion. Harmonic balance method is applied to get analytical solutions of the system. The frequency-response curves sallow that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurrences of such non-linear Phenomena.

• 천문학회보
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• 제43권1호
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• pp.64.2-64.2
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• 2018

지금으로부터 100년 전, 하버드대학교 천문대에서 에드워드 찰스 피커링과 윌리어미나 플레밍, 애니 점프 캐넌 등의 여성 천문학자들이 분광관측 자료를 가지고 헨리 드레이퍼 목록(HD catalog)을 만들기 시작했다. 이는 항성분류의 근간을 마련하고 현대 천문학의 본격적인 시작을 알리는 일이었다. 현재 국립청소년우주센터는 이를 기념하여, 디지털 이미지로 보유중인 1975년에서 1999년에 걸쳐 발간된 "Michigan catalog of HD stars"의 사진건판을 활용한 연구를 진행 중이다. 본 센터를 방문하는 청소년이 100년 전 그들과 한 것과 같은 고전적 항성 분류과정을 체험하며, 별의 스펙트럼을 이해하고 우주를 이해하는데 필수적인 분광학에 대한 이해를 높이길 기대한다. 이를 위한 선행 작업인 대물프리즘 사진건판 이미지에서 별의 스펙트럼을 추출하는 과정을 소개하고자 한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1427-1432
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• 2008

This paper describes the locomotion of a water jumping robot which attempts to emulate the fishing spider’s ability to jump on the water surface. While previous studies of the robots mimicking arthropods living on water were focused on recreating their horizontal skating motions, here we aim to achieve a vertical jumping motion. The robot jumps by pushing the water surface with rapidly released legs which were initially bent. The motion is triggered with a latch driven by the shape memory alloy actuator. The robot is capable of jumping to the maximum height of 26mm. Jumping efficiency, defined the maximum jumping height on water over the maximum jumping height on rigid ground, is 0.26 This work represents a first step toward robots that can locomote on water with superior versatility including skating and jumping.

• 한국정보과학회논문지:시스템및이론
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• 제36권6호
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• pp.437-450
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• 2009

본 논문에서는 임의의 피보나치 트리에 에지번호매김을 하여 피보나치 수들의 집합 {$F_k|k\;{\geq}\;2$}, {$F_{2k}|k\;{\geq}\;1$} 그리고 {$F_{3k+2}|k\;{\geq}\;0$}인 세가지 경우의 에지번호 집합을 얻는 7가지의 에지번호매김방법들을 제안한다. 이러한 에지번호들의 집합은 상호연결망의 일종인 원형군의 설계시 점프열로 사용할 수 있으므로 망척도 중 하나인 분지수를 결정한다.

• 한국운동역학회지
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• 제17권4호
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• pp.107-113
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• 2007

The purpose of this study were to investigate the effects of knee brace on the knee muscular neuro-biomechanical variables during the rebound in female highschool basketball players. Twelve high school female ($17.9{\pm}0.8years$) basketball players rebound jumped for maximal vertical height to sufficiently stress the anterior cruciate ligament with and without knee brace. Kinematic data were collected to estimate the knee flexion, abduction angles and jump height. The EMG data from the biceps femoris and rectus femoris was used to estimate the ratio of quadriceps muscle activity. Female athletes with knee brace showed more reduced the knee abduction angle and the ratio of quadriceps muscle activity at foot contact phase than without knee brace. In conclusion, Female athletes with brace reduced knee anterior cruciate ligament loads.

• 한국통신학회논문지
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• 제22권1호
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• pp.127-138
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• 1997

In this paper, we study new HOL-LJ scheme to guarantee the QoW of low priority cell with simple hardware which is not realizable in previously proposed HOL and HOL-PJ. the performance of the proposed scheme is evaluated by analysing an equivalent /M/M/1/N queuing system. In case of using the proposed scheme, we confirmed that good performance compared with HOL-PJ through simpulation and mathematical analysis. We also applied HOL-LJ algorithm to convetional Dual Buffer and Partial Buffer, and we analyzed the performance through computer simulation.