• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.464-464
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• 2017

경사가 급한 산지하천은 대부분 전석이 산재한 자갈하상으로 되어 있다. 전석은 계곡이나 사면에서 발생한 토석류의 일부로 하천에 유입하여 하류로 이송되는 중에 하상에 퇴적된다. 이후 발생하는 홍수에 따라서 거대 전석은 단속적 이동하기 때문에 하천 흐름을 방해하는 돌출장애물로서 기능하는 경우가 많다. 본 연구에서는 개수로 흐름의 장애를 유발하는 돌출물이 경계층 높이에 어떤 영향을 미치는 지를 파악하기 위하여 장애물 돌출높이의 변화가 경계층고에 미치는 영향을 수리실험으로 조사하였다. 본 연구인 경계층분포 실험은 폭 0.6m, 길이 9m인 순환식 유량공급 개수로에서 진행하였으며 실제 경계층 측정 길이는 폭 0.6m, 최대 길이 1.2m, 수심 0.2m이다. 개수로에 돌출장애물을 부착 후 3차원 유속계를 이용하여 유속을 측정하였다. 유속계의 측정간격은 수로 방향, 폭 방향, 수심방향으로 각각 1cm씩 이동하며 유속 u, v, w를 측정하였으며 이때 흐름의 평균유속은 0.51m/s이다. 실험에 사용된 돌출 장애물의 크기는 가로와 세로는 6cm, 길이 6~10cm인 직육면체 콘크리트이다. 포설된 하상재료의 평균입경은 20.5mm의 강자갈이며 포설된 높이는 평균 20.5mm이다. 실험방법은 개수로 바닥에 돌출장애물을 부착 후 그 하류에서 수심, 유량, 유속, 수온을 측정한다. 또한 하상재료를 포설하고 위와 같은 방법으로 실험을 진행 후 결과를 비교, 분석한다. 본 연구는 결과를 정리하면, 동일한 높이의 돌출장애물이 있을 경우 개수로 유속분포는 자갈하상에서 기울기가 더 급하였다. 돌출 장애물에서 하류로 갈수록 무차원 경계층 두께는 감소하는 경향을 보였으나 자갈하상인 경우에는 진동을 나타내고 있어서 하상의 조도가 경계층 안정에 영향을 미치는 것으로 판단된다. 따라서 자갈하상과 같이 하상의 조도고가 클 때 경계층 변화에 미치는 기구를 파악하는 연구가 필요하다.

• Food Science of Animal Resources
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• v.44 no.1
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• pp.39-50
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• 2024

The projected growth of global meat production over the next decade is attributed to rising income levels and population expansion. One potentially more pragmatic approach to mitigating the adverse externalities associated with meat production involves implementing alterations to the production process, such as transitioning to cultured meat, hybrid cultured meat, and meat alternatives. Cultured meat (CM) is derived from animal stem cells and undergoes a growth and division process that closely resembles the natural in vivo cellular development. CM is emerging as a widely embraced substitute for traditional protein sources, with the potential to alleviate the future strain on animalderived meat production. To date, the primary emphasis of cultured meat research and production has predominantly been around the ecological advantages and ethical considerations pertaining to animal welfare. However, there exists substantial study potential in exploring consumer preferences with respect to the texture, color, cuts, and sustainable methodologies associated with cultured meat. The potential augmentation of cultured meat's acceptance could be facilitated through the advancement of a wider range of cuts to mimic real muscle fibers. This review examines the prospective commercial trends of hybrid cultured meat. Subsequently, the present state of research pertaining to the advancement of scaffolding, coloration, and muscle fiber development in hybrid cultured meat, encompassing plant-based alternatives designed to emulate authentic meat, has been deliberated. However, this discussion highlights the obstacles that have arisen in current procedures and proposes future research directions for the development of sustainable cultured meat and meat alternatives, such as plant-based meat production.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.1
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• pp.35-42
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• 2020

In this paper, we propose a method to keep the robot at a distance of 30 to 45cm from the user in consideration of each individual's minimum area and inconvenience by using a 2D LiDAR sensor LDS-01 as the secondary sensor along with a QR code. First, the robot determines the brightness of the video and the presence of a QR code. If the light is bright and there is a QR code due to human's presence, the range of the 2D LiDAR sensor is set based on the position of the QR code in the captured image to find and follow the correct target. On the other hand, when the robot does not recognize the QR code due to the low light, the target is followed using a database that stores obstacles and human actions made before the experiment using only the 2D LiDAR sensor. As a result, our robot can follow the target person in four situations based on nine locations with seven types of motion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.21-24
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• 2004

This paper describes a perception of small-obstacle using ultrasonic sensors in a mobile robot. The research on the avoidance of the large-obstacles such as a wall, a large box, etc. using ultrasonic sensors has been generally progressed up to now. But the mobile robot could meet a small-obstacle such as a small plastic bottle of about 1 l in quantity, a small box of 7${\times}$7${\times}$7 cm3 in volume, and so on in its designated path, and could be disturbed by them in the locomotion of the mobile robot. So, it is necessary to research on the avoidance of a small-obstacle. In this paper, the small-obstacle perceiving system was designed and fabricated by arranging four ultrasonic sensors on the plastic plate to avoid a small-obstacle. The small-obstacle perceiving system was installed on the above part of the mobile robot with the slope of 40.7$^{\circ}$ to a horizontal line. The static characteristic test and the dynamic characteristic test were performed to know the information of the used ultrasonic sensors. As a result, the mobile robot with the small-obstacle perceiving system could avoid a small-obstacle, and could move in indoor environment safely.

• Journal of the Korean Institute of Navigation
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• v.1 no.1
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• pp.17-26
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• 1977

A large number of the set-nets are set in Namhaedo coast of Korea. The floats of these set-nets are not only small even in case of large floats but also they scarcely have distinguishable marks such as light buoys or flags, so that they are very hard to be recognized by naked eyes and thus became probable obstacles to navigation for the passing ships and the fishing vessels. In order to research the capability of detecting such nets with Radar, the author investigated a maximum detectable range of the ordinarly large floatsand of a floating corner reflectors of various size and shape by Radar. The results obtained are as follows; 1. A maximum detectable range of large floats at a close range can be calculated by the Radar equation in sufficient accuracy. 2. Large floats of the large set-nets are also detectable by Radar even though it's detectable range boundary was within 0.2-0.65 miles. And the Radar picture of large floats was easier to be found with somewhat higher setting of the gain control on shorter range scale of the 1 mile. 3. Floating corner reflector rather suitable for set-net floats of "S" type reflector proposed in this paper, of which the dimension must be above 17cm in diameter to be detectable by Radar at 2 miles.t 2 miles.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1250-1256
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• 2017

In this research, a high-performance ultrasonic positioning system is proposed to track the positions of an indoor mobile object. Composed of an ultrasonic sender (mobile object) and a receiver (anchor), the system employs three ultrasonic time-off-flights (TOFs) and trilateration to estimate the positions of the object with an accuracy of sub-centimeter. On the other hand, because ultrasonic waves are interfered by temperature, wind and various obstacles obstructing the propagation while propagating in air, ultrasonic pulse debounce technique and Kalman filter were applied to TOF and position calculation, respectively, to compensate for the interference and to obtain more accurate moving object position. To perform tasks in real time, ultrasonic signals are processed full-digitally with a Zynq SoC, and as a software design tool, Vivado IDE(integrated design environment) is used to design the whole signal processing system in hierarchical block diagrams. And, a hardware/software co-design is implemented, where the digital circuit portion is designed in the Zynq's fpga and the software portion is c-coded in the Zynq's processors by using the baremetal multiprocessing scheme in which the c-codes are distributed to dual-core processors, cpu0 and cpu1. To verify the usefulness of the proposed system, experiments were performed and the results were analyzed, and it was confirmed that the moving object could be tracked with accuracy of sub-cm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.808-811
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• 2009

Robovie-R2 [1], developed by ATR, is a 110cm high, 60kg weight, two wheel drive, human like robot. It has two arms with dynamic fingers. It also has a position sensitive detector sensor and two cameras as eyes on his head for recognizing his surrounding environment. Recent years, we have carried out a project to integrate new functions into Robovie-R2 so as to make it possible to be used in a dining room in healthcare center for helping serving meal for elderly. As a new function, we have developed software system for adaptive movement control of Robovie-R2 that is primary important since a robot that cannot autonomously control its movement would be a dangerous object to the people in dining room. We used the cameras on Robovie-R2's head to catch environment images, applied our original algorithm for recognizing obstacles such as furniture or people, so as to control Roboie-R2's movement. In this paper, we will focus our algorithm and its results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.10
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• pp.775-778
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• 2011

TBP (tertiarybutylphosphine), a relatively new material for phosphorus, has been studied with EDMIn (ethyldimethylindium) as an indium source for the growth of InP by MOVPE (metalorganic vapor phase epitaxy). Mirror smooth and good crystalline InP layers were obtained at $500-600^{\circ}C$ with the TBP/EDMIn molar ratio as low as 21. The deposited InP layers are all n-type with the electron concentration in the range of (5-10)${\times}10^{16}\;cm^{-3}$, which is a lot higher than those from $PH_3$. This high concentration is due presumably to the high concentration of donor impurities in TBP. And it has been found that the formation of adduct occurs between EDMIn and TBP at room temperature when the partial pressure of EDMIn in the reactant mixture is above $1{\times}10^{-2}$ Torr. The high concentration of impurities in TBP and the adduct formation between EDMIn and TBP are major obstacles in replacing $PH_3$ and TMIn for the growth of device quality InP layers.

• Korean Journal of Applied Biomechanics
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• v.29 no.2
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• pp.97-104
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• 2019

Objective: The aim of this study was to investigate the strategies for avoiding moving and stationary walker using body segments during walking. Method: Ten healthy young adults (10 males, age: $24.40{\pm}0.49yrs$, height: $175.80{\pm}5.22cm$, body mass: $70.30{\pm}5.22kg$) participated in this study. Each participant was asked to perform a task to avoid collisions with another walker who was moving or stationary during walking on the 10 m walkway. Both walkers were performed at natural self-selected walking speed. Results: Medio-lateral avoidance displacement of the trunk and the pelvis were significantly increased when avoiding a stationary walker (p<.05). There were no significant differences in medio-lateral center of mass trajectory. Rotation angle of trunk, pelvis and foot on the vertical axis were significantly increased when avoiding a stationary walker (p<.05). Conclusion: Based on our results, when another walker moves continuously, the walker recognizes another walker as the object of social interaction and performs the avoidance strategies while expecting the cooperative distance. On the other hand, when another walker is stopped, it is determined that the walker has an obligation to avoid, and the walker performs a relatively safer avoidance strategy.

• Journal of Drive and Control
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• v.19 no.4
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• pp.62-69
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• 2022

Construction machinery is exposed to accidents such as collisions, narrowness, and overturns during operation. In particular, mobile crane is operated only with the driver's vision and limited information of the assistant worker. Thus, there is a high risk of an accident. Recently, some collision avoidance device using sensors such as cameras and LiDAR have been applied. However, they are still insufficient to prevent collisions in the omnidirectional 3D space. In this study, a rotating LiDAR device was developed and applied to a 250-ton crane to obtain a full-space point cloud. An algorithm that could provide distance information and safety status to the driver was developed. Also, deep-learning segmentation algorithm was used to classify human-worker. The developed device could recognize obstacles within 100m of a 360-degree range. In the experiment, a safety distance was calculated with an error of 10.3cm at 30m to give the operator an accurate distance and collision alarm.