• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1999년도 추계학술대회논문집
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• pp.111-121
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• 1999

From the traffic analyses, and model constructions and verifications for speed prediction on the freeway ramp junctions with 70mph speed limit, the following results obtained: ⅰ) The traffic flow distribution showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy distribution was also shown to be varied by a big difference depending on the time periods. Especially, the occupancy in the morning peak period showed over 100% increase when compared with the 24hours average occupancy, and the occupancy in the afternoon peak period over 25% increase when compared with the same occupancy.ⅲ) The speed distribution was not shown to have a big difference depending on the time periods. Especially, the speed in the morning peak period shown 10mph decrease when compared with the 24hours' average speed, but the speed did not show a big difference in the afternoon peak period.ⅳ) The analyses of variance showed a high explanatory power between the speed predictive models(SPM) constructed and the variables used, especially the upstream speed. ⅴ) The analysis of correlation for verifying the speed predictive models(SPM) constructed on the ramp junctions were shown to have a high correlation between observed data and predicted data. Especially, the correlation coefficients showed over 0.95 excluding the unstable condition on the diverge sectionⅵ) Speed predictive models constructed were shown to have the better results than the HCM models, even if the speed limits on the freeway were different between the HCM models and speed predictive models constructed.

• 한국산학기술학회논문지
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• 제17권12호
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• pp.363-370
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• 2016

본 연구의 목적은 속도가 다른 트레드밀 훈련이 다리 근두께에 어떠한 영향을 미치는지 알아보고자 하였다. 대상자는 대학생 남녀 36명을 평보군 (n=12)과 속보군 (n=12), 교차보행군 (n=12)으로 나누어 평보군은 평균 속도의 100%의 속도로 훈련을 실시하였고, 속보군은 평균 속도의 130%의 속도로 실시하였으며, 교차보행군은 130%의 속도와 100%의 속도를 각각 교차하면서 보행 훈련을 실시하였다. 훈련은 6주 동안 시행하였고, 주당 3회, 회당 60분간 시행하였다. 측정은 넙다리곧은근과 가쪽넓은근, 장딴지근, 앞정강근의 두께를 비교하기 위해 초음파영상장치를 이용하였다. 연구 결과 넙다리곧은근, 가쪽넓은근, 장딴지근에서 시간에 따라 유의한 증가가 있는 것으로 나타났고, 상호작용 또한 있는 것으로 나타났다. 그리고 앞정강근에서는 시간에 따라 유의한 증가가 있는 것으로 나타났다. 이상과 같은 결과로 보아 평속보다는 속도를 달리한 훈련을 실시하였을 때 다리 근육의 두께 변화에 영향을 미치는 것으로 생각되며, 추후 연구에서는 신경계나 근골격계 질환으로 인한 보행 장애를 가진 환자를 대상으로 재활 프로그램에 적용하는 연구가 지속적으로 이루어져야 할 것으로 생각된다.

• 한국화재소방학회논문지
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• 제31권1호
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• pp.36-41
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• 2017

단일 복도에서의 단방향 피난 이동 실험의 수행 결과, 평균 밀도 $2.36P/m^2$에서 0.55 m/s의 속도를 보이고 있다. S.F.P.E. Handbook에서 제시된 복도에서의 밀도기반 속도 수식 계산결과와 평균값을 비교할 때, 본 실험이 0.55 m/s, SFPE 수식이 0.53 m/s로서 0.02 m/s의 차이를 보였으며 데이터 별로 분석한 결과, 최대 0.38 m/s의 큰 차이를 나타내고 있다. 일부 실험결과는 보행속도의 증가에 따라 밀도가 높아짐을 보였으며 실험 결과분석은 전체 실험시간에 대한 평균 데이터를 사용하였다. 동영상에 대한 프레임단위 분석과 같은 세부적인 시간분석을 수행한다면 더욱 신뢰성 있는 데이터를 확보할 수 있을 것으로 보인다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1998년도 제17회 KOSCI SYMPOSIUM 논문집
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• pp.139-154
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• 1998

Under certain circumstance, premixed turbulent flame can be treated as wrinkled thin laminar flame and its motion in a hydrodynamic flow field has been investigated by employing G-equation. Past studies on G-equation successfully described certain aspects of laminar flame propagation such as effects of stretch on flame speed. In those studies, flames were regarded as a passive interface that does not influence the flow field. The experimental evidences, however, indicate that flow field can be significantly modified by the propagation of flames through the volume expansion of burned gas. In the present study, a new method to be used with G -equation is described to include the effect of volume expansion in the flame dynamics. The effect of volume expansion on the flow field is approximated by Biot-Savart law. The newly developed model is validated by comparison with existing analytical solutions of G -equation to predict flames propagating in hydrodynamic flow field without volume expansion. To further investigate the influence of volume expansion, present method was applied to initially wrinkled or planar flame propagating in an imposed velocity field and the average flame speed was evaluated from the ratio of flame surface area and projected area of unburned stream channel. It was observed that the initial wrinkling of flame cannot sustain itself without velocity disturbance and wrinkled structure decays into planar flame as the flame propagates. The rate of decay of the structure increased with volume expansion. The asymptotic change in the average burning speed occurs only with disturbed velocity field. Because volume expansion acts directly on the velocity field, the average burning speed is affected at all time when its effect is included. With relatively small temperature ratio of 3, the average flame speed increased 10%. The combined effect of volume expansion and flame stretch is also considered and the result implied that the effect of stretch is independent of volume release.

• Imaging Science in Dentistry
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• 제33권1호
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• pp.21-26
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• 2003

Purpose: To investigate the characteristics of the newly marketed, Insight dental X-ray film. Materials and Methods: Kodak Ultraspeed (DF-58), E-speed, Agfa Dentus M2, and Kodak Insight (IP-21) films were radiographed using a Trophy intra-oral radiographic machine. 10 step exposure times were prepared and each step exposure was monitored using a FH 40G (ESM Eberline Instruments) dosimeter for each of the 4 types of intra-oral film. All films were manually processed and the radiographic densities at 6 sites of each processed film were measured, and the characteristic curves of each of the 4 types intra-oral films were created utilizing these dosimetric data and radiographic densities, based on ISO 5779. The film contrast, speed, and base plus fog density of Insight film were compared with those of the 3 other films examined in this experiment. Results : E-speed film showed greatest average gradients followed by Insight film. E-speed and Ultraspeed film showed great average gradients at low density levels. Insight film showed the fastest speed followed by E-speed, Dentus M2 and Ultraspeed film. Dentus M2 film showed greatest base plus fog density level followed by Insight film. Conclusion : Kodak Insight film showed fastest film speed with comparable film contrast on characteristic curve.

• Journal of Biosystems Engineering
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• 제28권5호
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• pp.411-420
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• 2003

Physical and cultural properties were investigated on the rice-seed pellets made by the pelleting machine(Yu, 2003) as the changes with mixing ratios of soil to rice seed of 6 : 1, 7 : 1, and 8 : I, and rotating speeds of forming rolls of 7, 10, and 13 rpm. Average weight, average diameter, and average sphericity of the pellets were 1.70 g, 12.0 ㎜, and 99.1 ％, respectively. Average number of seeds per pellet was more than 3, and almost all pellets had more than 3 seeds in the cases of mixing ratios of 6 : 1, and 7 : 1 at the forming rolls' speed of 7 rpm. Gradual drying was needed because rapid drying caused cracks on surface of the pellets. Compression strength of the pellets dried in shady room was in the range of 132 ∼ 152 N, which was enough for handling. Comparing with the previous pellets(Park, 2002), average number of seeds per pellet, ratio of pellets including more than 3 seeds, and compression strength increased due to the effects of pressure feed of pellet materials, and improvements of the forming rolls. Emergence ratio of the pellets made at the mixing ratio of 6 : 1 and the forming rolls' speed of 7 rpm, was 100 % on dry paddy and was 97 % on flooded paddy surface. Good growth characteristics, and yield except number of seedling stand and ratio of missing plant were shown in planting of the pellets made at the mixing ratio of 7 : 1 and the forming rolls' speed of 7 rpm on flooded paddy surface field. Considering the cultural results, the mixing ratio of 6 : 1, and the forming rolls' speed of 7 rpm seems to be optimum operating condition for the improved pelleting machine.

• 대한교통학회지
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• 제30권2호
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• pp.117-126
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• 2012

교통부문에서 발생되는 $CO_2$ 배출량이 전체 $CO_2$ 배출 총량의 33%를 차지하고 있는 상황에서 지구 온난화를 방지할 수 있도록 교통부문 온실가스 저감 대책을 마련하는 것은 매우 중요하다. 효과적인 교통부문 온실가스 저감대책을 수립하기 위하여 자동차의 오염물질 배출량을 객관적이고 정확하게 산출할 수 있는 방법론 개발이 선행되어야 하지만, 현재까지 표준화된 교통부문 오염물질 배출량 산출 방법론이 정립되어 있지 못한 실정이다. 세계적으로 가장 널리 사용되고 있는 평균 차속 모형은 빠르고 간편하게 대기오염 영향을 산출할 수 있다는 장점을 갖지만, 다양한 도로조건과 교통조건을 반영하지 못하는 한계가 있다. 본 논문에서는 현행 평균 차속 모형을 통하여 산출된 배출량이 주행 여건에 따라 현실에서 발생하는 배출량과 많은 차이가 있음을 실제 데이터 분석을 통하여 확인하였으며, 향후에는 평균 차속 모형의 배출계수가 도로 유형과 교통 상황에 따라 구분될 필요가 있음을 제기하였다.

• Journal of Computing Science and Engineering
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• 제9권1호
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• pp.29-38
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• 2015

Human action recognition has become an important research topic in computer vision area recently due to many applications in the real world, such as video surveillance, video retrieval, video analysis, and human-computer interaction. The goal of this paper is to evaluate descriptors which have recently been used in action recognition, namely Histogram of Oriented Gradient (HOG) and Histogram of Optical Flow (HOF). This paper also proposes new descriptors to represent the change of points within each part of a human body, caused by actions named as Histogram of Changing Points (HCP) and so-called Average Speed (AS) which measures the average speed of actions. The descriptors are combined to build a strong descriptor to represent human actions by modeling the information about appearance, local motion, and changes on each part of the body, as well as motion speed. The effectiveness of these new descriptors is evaluated in the experiments on KTH and Hollywood datasets.

• 한국표면공학회지
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• 제36권2호
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• pp.116-121
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• 2003

Ti-Si-N coating layers were deposited onto WC-Co substrates by a hybrid system of arc ion plating (AIP) and sputtering techniques. The tribological behaviors of Ti-Si-N coating layers with various Si contents were investigated by the dry sliding wear experiments, which were conducted at three different sliding speeds, 0.1, 0.3, 0.5 m/s, against the steel and alumina balls. In the case of steel ball, the average friction coefficient slightly decreased with increasing the sliding speed regardless of Si content due to adhesive wear behavior between coating layer and steel ball. At constant sliding speed, the average friction coefficient decreased with increase of Si content. On the contrary, in the case of alumina ball, the average friction coefficient increased with increasing the sliding speed regardless of Si content, indicating that the abrasive wear behavior was more dominant when the coating layers slide against alumina ball. Through these experimental results, it was found that the tribological behaviors of Ti-Si-N coating layers were effected by factors such as Si content, sliding speed, and kinds of counterpart materials rather than the hardness of coating layer.

• 한국운동역학회지
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• 제28권2호
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• pp.93-100
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• 2018

Objective: The purpose of this study is to analyze the kinematic characteristics of the national speed skaters in the curve phase of 500-m race. Method: Seven national skaters participated in the study. Race images were acquired using a high - speed camera, and the three-dimensional motion was analyzed. Results: For skaters, whose average velocity in the curve phase is high, the velocity of entry into the straight phase was also fast. The fast skaters showed a larger maximum angle of extension of the knee joints than the relatively slow skaters, and the trunk ROM was smaller. Fast skaters tended to match the timing of the movement of the lower limb with the pelvis, while slow skaters tended to rotate the left pelvis backward. The velocity of the curve phase did not show a clear relationship with stroke time, average trunk angle, and lap time. Conclusion: It is important to skate close to the inner line, keep the trunk ROM below 10 degrees, extend the knee angle to over 160 degrees, and match the movement of the pelvis and lower limb to accelerate in the curve phase. The average velocity of the curves was fast for many athletes, but the competition rankings were low. Therefore, it is possible to improve the performance by optimizing the start technique, the running characteristics of the straight phase, and the physical factors.