• 대한인간공학회지
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• 제14권1호
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• pp.9-23
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• 1995

The objectives of the study were twofole: (1) to investigate effects of rhythmic contraction and sustained contraction methods on recovery rate of isometric endurance capacity and (2) to compare aptterns of muscle recruitment of both arms observed during each contraction period. In the experiment, each of two subjects performed five successive rhythmic or sustained isometric contractions at 50% MVC with both arms to the point of fatigue, which was the failure to maintain the required tension. In making the contractions, the subjects stood erect with upper arms held at an angle of approximately 90 .deg. to the forearm. The interval between the successive contractions was kept constant at 3, 7, 20, or 40 minutes. Regardless of the contraction methods, the recovery rate was least at the shortest interval and was highest at the longest interval. However, a statistical analysis showed that the recovery rates for the rhythmic contractions were significantly lower than those for the sustained contractions throughout 4 different intervals. Furthermore, as the frequency of the rhythmic contractions per min, increased 4 to 6 times, the recovery rate of isometric endurance capacity decreased. From an EMG anglysis, recruitment pattern of the muscules of both arms was found to be common between two different contraction methods. The biceps muxcles of the upper arms played a major role in exerting 50% MVC, while the brachioradialis muscles of the forearms acted as synergists. As the contraction proceeded, the role of the biceps muscles as a prime mover lessened due to the fatigue. Then, the brachioradialis muscles exerted more strength to sustain 50% MVC. The implications of these finding were discussed.

• 한국군사과학기술학회지
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• 제14권6호
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• pp.979-985
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• 2011

This paper includes that there are results of designing the flash hider and analyzing fluid dynamics of a front area of the barrel to shorten the length of small arms. Generally, the muzzle flash can be generated out of the barrel by the reaction between the oxygen in the air and unburned gunpowder contained in the propellant gas if a barrel is not long enough to burn gunpowder fully inside of the barrel. Though, the hugh muzzle flash, which is a characteristic of small arms with short barrel length, caused a soldier to aim at the target at night by making the soldier blind for a while and endangers his life by revealing firing position to enemies. Besides, the heat of muzzle flash can weaken the performance of thermal sights, which are attached to small arms for night battlefield. In this paper, flash hiders with several different shapes were designed for a newly developed 5.56mm caliber rifle with short barrel length. The performance of each flash hider to reduce the muzzle flash was compared theoretically and experimentally. Through the authorized test procedure, a highly efficient design of flash hider for reducing the muzzle flash was identified. The result of the paper can be helpful when designing flash hiders for small arms with short barrel length.

• 융합보안논문지
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• 제19권2호
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• pp.147-156
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• 2019

본 논문의 연구목적은 1950년대 이래 한반도에서 있었던 남북한 간 평화체제 구축을 위한 제안들과 협상중점을 과거와 '9.19 군사분야합의서'로 대변되는 현 문재인 정부의 조치들을 군비통제이론 측면에서 비교 분석하여 남북한 간 군비통제 추진방안을 제시하는 것이다. 이를 위해 현재까지 정립된 이론을 비교 분석하여, 최적의 분석의 틀을 정립하였다. 과거는 주로 1990년 9월 제1차 남북고위급 회담부터 2008년 1월 노무현 정부말기까지를 중점적으로 분석하였으며, 이를 현 문재인 정부에서 추진하고 있는 군비통제 정책과 비교 분석하였다. 그 결과 나타난 특징은 유럽과는 달리 남북한 군비통제 정책은 군사적 신뢰구축이 정치적 신뢰구축과 동시 병행적으로 추진된다는 것이었다. 이를 토대로 한반도 평화정착 과정에서 협의되어야 할 신뢰구축과 군비통제, 군축 추진전략을 제시하였다. 중요한 점은 나아가면 갈수록 군비통제의 필요성은 증대될 것이며, 통일정책과 상호 보완적으로 추진되어야 한다는 것이었다.

• Bulletin of the Korean Chemical Society
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• 제26권11호
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• pp.1861-1864
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• 2005

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.305-308
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• 2014

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.3101-3104
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• 2009

• 대한의생명과학회지
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• 제24권1호
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• pp.43-49
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• 2018

Electrocardiogram (ECG) is a widely used method to diagnose electrical activity of heart. Although it is a reliable and easy method, ECG could be interfered by electrical signals. One of the interfering signals is electromyogram (EMG) that is caused by muscle contraction in any parts of the body except heart. To avoid the EMG noise, an examinee is advised to be relaxed on supine position while measuring ECG. Sometimes, patients who can't put their arms and legs down on bed due to some reasons such as cast on arms or legs necessarily have the EMG noise. But detailed information about how much of the noise could be induced by positional change of arms and legs has not been reported. Here we examined the noise by analyzing ECG data from 14 candidates, 7 males and 7 females. The ECG data was obtained using the standard 12 lead ECG. EMG noise was induced by raising arms and legs at $90^{\circ}$, $60^{\circ}$ or $30^{\circ}$. Because arms are located close to the heart, noise by the raised arms was analyzed toward left or right arm separately. All of the examinees showed similar pattern of the EMG noise. EMG noise by positional change of left or right arm was clearly monitored in different limb leads. Change of leg positions induced the noise that was monitored in aVF of augmented leads and II and III of limb leads. There was a difference in degree of the noise between male and female examinees. In addition to the EMG noise, decrease of PR interval was monitored in particular positional changes, which was prominent in male examinees. These results will enlarge fundamental understanding about EMG noise in ECG.

• 천문학회보
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• 제40권1호
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• pp.48.4-49
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• 2015

Stellar spiral arms and magnetic fields in disk galaxies are important in the formation of gaseous structures such as spurs/feathers and wiggles as well as in angular momentum transport between stars and gas. We present our recent results of global magnetohydrodynamic simulations to study nonlinear responses of self-gravitating and magnetized gas to an imposed stellar spiral potential. We vary the arm strength, the arm pattern speed, and magnetic field strength to explore various galactic situations. Magnetic fields not only reduce the peak density of galactic spiral shocks but also make angular momentum transport more efficient via magnetic pressure and tension forces. The extent and shapes of gaseous arms as well as the radial mass drift rate depend rather sensitively on the magnetic field strength. The wiggle instability apparent in unmagnetized models is suppressed with increasing magnetic field strength, while magnetic fields promote the development of magneto-Jeans instability of the arms and magnetic islands in between arms. We quantify the angular momentum transport by spiral shocks, focusing on the effects of magnetic fields. We also present physical interpretations of our numerical results and discuss astronomical implications of our findings.

• 제어로봇시스템학회논문지
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• 제6권2호
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• pp.190-196
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• 2000

A hybrid position/force control scheme to regulate the force and position by dual arms is proposed where two arms are treated as one rm in a kinematic viewpoint. The force error calculated from the information of two force/torque sensors attached to the end of each arm is transferred to minimum configuration space coordinates and then is distributed to total system joint coordinates, The position adjustment at the total con-figuration coordinates is computed based on the effective compliance matrix with respect to total joint coordinates which is obtained by coordinate transformation between the task coordinates and the total joint coordinates. The proposed scheme is applied to sawing task. When the trajectory of the saw is planned to follow a line in a horizontal plane 2 position parameters are to be controlled(i.e., two translational positions) Also a certain level of contact force has to be controlled along the vertical direction(i.e. minus z-direction) not to loose the contact with the object to be sawn. We experimentally show that the performance of the velocity and force response are satisfactory. The proposed hybrid control scheme can be applied to arbitrary two cooperating arm system regardless of their kinematic structure and the number of actuated joints.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.743-746
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• 1996

A hybrid control scheme to regulate the force and position by dual arms is proposed, where two arms are treated as one arm in a kinematic viewpoint. Our approach is different from other hybrid control approaches which consider robot dynamics, in the sense that we employ a purely kinematic based approach for hybrid control, with regard to the nature of position-controlled industrial robots. The proposed scheme is applied to sawing task. In the sawing task, the trajectory of the saw grasped by dual arms is planned in an offline fashion. When the trajectory of the saw is planned to follow a line in a horizontal plane, 3 position parameters are to be controlled(i.e, two translational positions and one rotational position). And a certain level of contact force has to be controlled along the vertical direction(i.e., minus z-direction) not to loose the contact with the object to be sawn. Typical feature of sawing task is that the contact position where the force control is to be performed is continuously changing. Therefore, the kinematic mapping between the force controlled position and the joint actuators has to be updated continuously. The effectiveness of the proposed control scheme is experimentally demonstrated. The proposed hybrid control scheme can be applied to arbitrary dual arm systems, regardless of their kinematic structure and the number of actuated joints.