• 한국운동역학회지
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• 제15권1호
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• pp.177-195
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• 2005

The purpose of this study was to analyze the kinematic variables of ankle joints and EMG signal of the lower limbs muscle activity for the different walking speed. The subjects were 6 males of twenties. It was classified into three different walking speed-0.75m/s, 1.25m/s, 1.75m/s. The walking performances were filmed by high speed video camera and EMG signal was gained by ME3000P8 Measurement Unit. Tibialis anterior(TA), Gastrocnemius medial head(GM), Gastrocnemius lateral head(GL), Ssoleus(SO) were selected for the dorsiflexion and plantarflexion of the ankle joint. The result of this study were as follows: 1. In the gait cycle, The time parameters for the phases were showed significant difference without the terminal stance phase and terminal swing phase for the different walking speed. 2. The angle of ankle joint was no significant difference for each time point and MDF, MPF but increasing walking speed the angle had the increasing pattern slightly. 3. The angular velocity of ankle joint was showed the significant difference for LHC, RTO, RKC, LHU, MPF and MDF point along the walking speed. 4. TA was showed about 2-3 times muscle activity at the 1.75m/s than 1.25m/s in some phases. And it was showed the similar muscle activity between the 0.75m/s and 1.25m/s but, showed a little much muscle activity in the 0.75m/s. GM was showed about 2-3 times muscle activity in the 1.75m/s than 1.25m/s, and even much muscle activity at the 0.75m/s than 1.25m/s in some phases. GL was showed increasing pattern of muscle activity specially in the initial swing phase as the walking speed increased. SO was showed about 3 times muscle activity in the 1.75m/s than 1.25m/s during the plantarflexion of ankle joint. It was showed the similar muscle activity between the 0.75m/s and 1.25m/s but, showed a little much muscle activity in the 1.25m/s.

• 한국정보통신학회논문지
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• 제11권8호
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• pp.1511-1518
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• 2007

최근 유비쿼터스 컴퓨팅에 대한 연구가 활발하게 전개되면서 영상 전송, 저장, 검색 및 원격 모니터링의 서비스에 대한 욕구가 PC뿐만 아니라 모바일 환경에서까지 증대되고 있다. 침입 탐지의 보안 서비스를 필요로 하는 곳에서는 주로 CCTV(Closed Circuit TV)와 DVR(Digital Video Recording)과 같은 보안 장비들이 사용되고 있는 반면 이러한 장비들은 고가이므로 일반 사용자나 가정 및 소규모 사업장에 도입하는 것은 어려울 뿐만 아니라 휴대하기도 쉽지 않고 모바일용의 카메라솔루션은 고기능을 지원하지 않으며 영상 화질 또한 VGA급의 저 화질을 지원한다. 이에 본 논문에서는 PC나 DVR급 장치에 못지않은 유비쿼터스형 모바일용 고화질 영상 전송장치의 임베디드 시스템 설계 및 구현에 관하여 기술하였다. 이를 위한 모바일용 전용 CPU 채용과 고화질을 위한 MPEG-4 H/W CODEC의 설계 및 구현 등에 관하여 기술하였다. 구현된 시스템은 모바일 환경에서 속도, 화질 등에 있어서 우수한 성능을 나타내었다.

• 한국운동역학회지
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• 제15권2호
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• pp.93-102
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• 2005

The purpose of this study was to examine the effect of step length on the joint moment. The subjects were 4 undergraduate and graduate students in their 20s with normal legs. The subjects were individually tested by the running timer at the walking speed of 0.67m/s, 134m/s, and 2.46m/s. The step length was regulated to -10% of normal, normal and +10% of normal step length using foot print. The walking performances of each subjects were filmed using a high speed video camera. The raw data were analyzed by LabVIEW Graphical Program and these data were analyzed by ANOVAs and Scheffe. The results of this study were as follows: The maximum dorsiflexion moment of the ankle joint increased as the step length increased only at the fast walking speed. Although there wasn't significant difference shown in the plantar flexion moment, regular pattern in the plantar flexion moment which increased as the step length increased was found. The first maximum extension moment of the knee joint increased only at the normal walking speed, but there appeared no significant difference in the maximum flexion and second extension moment. The maximum extension moment of the hip joint increased at the normal and fast walking speed. Although there wasn't significant difference, regular pattern in flexion moment which increased as the step length increased was found.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.30-37
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• 2004

The combustion and emission characteristics of a direct injection CI engine fuelled with DME(Dimethyl Ether) and diesel fuel were compared at idle engine speed(800 rpm) with various injection parameters. An optical single cylinder diesel engine equipped with a common-rail fuel injection system was constructed to investigate combustion processes of DME and diesel fuel. The combustion images were recorded with a high-speed video camera system. The results demonstrated that the DME-fuelled engine was superior to the conventional diesel engine in terms of engine performance and emissions. The optimal injection timing of DME was located around IDC(Top Dead Center), which was roughly same as that of diesel fuel. As the injection timing was advanced much earlier than TDC, NOx (Nitric Oxides) level increased considerably. NOx emission of DME was equal or a little higher than that for diesel fuel at the same injection pressure and timing because of higher evaporation characteristics of DME. Throughout all experimental conditions, DME did not produce any measurable smoke level.

• 한국자동차공학회논문집
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• 제8권1호
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• pp.48-53
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• 2000

The effects of the internal flow in a diesel injection nozzle on the atomization of the spray has been investigated experimentally. Flow visualization was made using a transparent acrylic model nozzle. And also, measurement of the sac chamber pressure was made for clartfying the effect of pressure fluctuation in the sac chamber on the wpray behaviors. The geometry of the model nozzle was scaled up 10 times of the actual nozzle and the injection pressure for the model nozzle was adjusted so as to achieve a Reynolds number at the discharge hole which was the same as the actual nozzle. Polystyrene tracers, a laser sheet light and a still/high speed video camera were used to visualize the flow pattern in the sac chamber. When the needle lift was small, the high turbulence in the sac chamber generated by the high velocity seat flow made the spread angle of the spray large. Cavitation which arose in the sky chamber induced the pressure fluctuation and then affects the spread angle of the spray.

• 한국운동역학회지
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• 제16권1호
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• pp.55-63
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• 2006

The purpose of this study is to prove the kinematical characteristics of Deff motion, the high bar performance, in terms of flying phases so that we can provide basic sources for improving gymnastic performance. To do this, we selected and analyzed the performance of two athletes who did Deff motion in the high bar competition of male artistic gymnastic in the 22nd Universiade 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes' movements, by using a high speed video camera. To make a successful performance, a performer releases the bar at a height of a high bar vertically and at a height of 82cm horizontally, and the flying performance should be made without moving forward, as maintaining the proper balance, in order to rise over 118cm high during the flying phase. When the performer is releasing the bar, an increase of the vertical speed in the center of the body and extension of a knee joint and a hip joint contribute to increasing a flying height. And when the moving body is twisted, leaning to left side is caused by the winding movement of a knee joint, which causes an unstable bar grasp. To grasp the bar stably, just before releasing the performer should gain propulsive force from twisting rotation through increasing the speed of shoulder rotation. And before the peak point, the performer should make sure of a body rotation distance over $164^{\circ}$ so that he or she can do an aerial rotary performance smoothly. When grasping the high bar, the center of the body should be above the bar and the angle of shoulder rotation should be maintained close to $540^{\circ}$ simultaneously. he high point performance(S1) has more speed on an ascending phase and less speed on a descending phase than the low point performance (S2). At the peak point, both the rotation angle of the body and that of the shoulder in high point performance are big as well. In conclusion, it is shown that a performer can make a jump toward the high bar easily with the body straight because the performer can hold the upper part of the body erect early in a descending phase.

• 인터넷정보학회논문지
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• 제16권1호
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• pp.1-8
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• 2015

본 논문에서는 초광각 무선 내시경을 제안하고 구현하였다. 내시경은 초광각 카메라 모듈과 무선전송 모듈로 구성된다. 162도의 초광광 렌즈와 이미지 센서 및 카메라 프로세서가 $3{\times}3{\times}9cm3$ 크기의 케이스에 함께 패키지 된다. 무선전송 모듈로 UWB 기반 및 WiFi 기반의 플랫폼을 각각 구현한다. UWB 기반 모듈은 의 고화질 영상을 MJPEG로 압축하여, $2048{\times}1536$ (QXGA)의 해상도에서 15 fps의 속도로 영상을 전송하며, 최대 데이터 전송속도는 41.2 Mbps에 달한다. 구현된 내시경은 의료용 내시경의 화각과 해상도 수준을 가지며, 상용 고성능 WiFi 내시경과 비교할 때 ~3X의 화각과 16X의 해상도를 갖는다. WiFi 기반의 모듈은 $640{\times}480$ (VGA)의 해상도에서 30 fps의 속도로 영상을 스마트 기기로 스트리밍 하며, 최대 1.5 Mbps의 데이터 전송속도를 보여준다. 구현된 모듈은 저가격의 의료용 무선 전자 내시경의 구현 가능성을 보여주며, U-헬스케어, 응급처치, 가정의료, 원격진료 등에 효과적으로 활용될 수 있을 것으로 기대된다.

• 전자공학회논문지SC
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• 제49권3호
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• pp.53-61
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• 2012

본 논문에서는 스테레오 적외선 카메라를 이용하여 소형 및 고온으로 날아가는 이동체의 거리를 실시간으로 측정하는 시스템을 제안한다. 이동체와 주변 환경의 온도 차이를 측정하고 고속으로 이동하는 소형 이동체의 거리를 자동으로 측정하기 위하여 적외선 스테레오 카메라 시스템을 구축하였다. 우선 적외선 카메라를 이용하여 취득한 고온의 이동체 영상으로부터 주변의 온도분포와 이동체간의 온도차를 이용하여 이동체영역을 검출하고, 이동체의 움직임 정보와 적외선 카메라 영상의 밝기정보를 결합하여 이동체를 추적한다. 좌우 적외선 카메라 영상에 대하여 각각 추출된 이동체 영역을 중심으로 스테레오 정합을 수행하여 시차정보를 추정하고, 카메라 파라미터와 시차정보를 이용하여 실시간으로 이동하는 이동체의 거리를 추정한다. 본 논문에서 제안하는 적외선 스테레오 카메라 시스템을 검증하기 위하여 고온의 이동체를 촬영할 때, 3차원 궤적(x,y,z) 측정기를 함께 가동하여 이동체가 이동하는 거리를 측정하여 이를 기준 거리(ground truth)로 설정하였다. 3차례의 비디오 데이터로부터 실험한 결과, 적외선 스테레오 카메라를 이용한 고온/소형 이동체의 거리오차 측정 결과는 평균적으로 9.68%로 추정되었다. 스테레오 적외선 카메라의 타이밍 문제(jitter)를 고려하면, 실제로 추정 오차는 줄어들 것으로 판단되기 때문에, 향후 적외선 카메라를 이용하는 다양한 이동체의 거리 및 위치를 측정하는데 응용할 수 있을 것으로 기대된다.

• 한국안전학회지
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• 제23권2호
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• pp.81-86
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• 2008

직사각형 폭발 챔버에서 전파하는 화염과 직사각형 장애물의 상관관계를 조사하기 위한 실험적 연구가 수행되었다. 챔버내에 10%, 20%및 30%의 blockage ratio를 가지는 3가지 직사각형 장애물들이 사용되었다. 전파하는 화염과 장애물의 상관관계를 조사하기 위해 고속카메라가 사용되었다. 고속카메라로 얻어진 화염 이미지로부터 장애물 주위의 국부 화염속도 및 그 화염속도의 확률밀도함수가 계산되었다. 실험결과, 전파하는 화염이 직사각형 장애물의 모서리와 상호작용할 때 국부 화염속도는 증가하였다. 그 증가속도는 장애물의 Blockage Ratio가 증가할 때 더욱 커지는 것으로 나타났다. 그러나, 평균화염속도는 Blockage Ratio에 큰 의존성을 가지지 않는 것으로 나타났다. 이 연구에서 사용된 작은 L(Lenlgth)/D(Diameter)비를 가지는 폭발 챔버내에서 전파하는 화염전면과 직사각형 장애물과의 상관관계는 L/D비가 큰 문헌에서 보고된 결과와 비교하면, Blockage Ratio에 따른 의존성은 작은 것으로 나타났다.

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1321-1328
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• 2005

The characteristics of the diesel spray have affected certain aspects of engine performance, such as the power, fuel consumption, and emissions. Therefore, this study was performed to investigate the effects of various injection parameters. In order to obtain the effect of injection parameters on diesel spray characteristics, the experiment is performed by using a high temperature and pressure chamber. The behaviors of the spray are visualized by using a high speed video camera, spray angle, penetration, and various other things. The results of the experiment are summarized as follows. (1) The correlation of the spray penetration can be expressed as follows. $$0< t $$t_{b} (2) The correlation of the spray angle can be expressed as follows $$T_a=293K\;tan({\theta}/2)=0.59({\rho}a/{\rho}f)^{0.437}$$ $$T_a=473K\;tan({\theta}/2)=0.588({\rho}a/{\rho}f)^{0.404}$$ (3) The measured macro characteristics that include the spray tip penetration and spray angle corresponded with the established correlations.