• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.496-502
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• 2020

The electronic attendance management system is being introduced and operated on a pilot basis by some universities and educational institutions. However, most of the related systems have installed and operated the existing barcode and magnetic card systems. Classroom attendance is managed by introducing RF cards, but it causes problems such as recognition distance (less than 5cm) and the need for a check process in which students have to read the card each time with a reader for attendance. Also, it is not possible to respond in real time to the situation of midterm (early leave, absence from the second lecture time, etc.) because it is used in the lecture time of one subject with the record checked once. In order to solve these problems, the various mobile attendance systems proposed to solve these problems are also unable to fundamentally solve problems such as interim attendance and proxy attendance because they check attendance using only the application of a smartphone. In this paper, we use geofencing technology, which is a positioning-based technology that detects the entry and exit of people, objects, etc. in areas separated by virtual boundaries. The proposed system solves the problem of intermediate attendance and alternate attendance by setting the student to automatically record the access record when entering and leaving the classroom set as a geofence with a smartphone. In addition, it also provides a function to prevent unintentional mistakes that occur through the smartphone by limiting some of the functions of the smartphone such as silence, vibration, and Internet use when entering the classroom.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2567-2572
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• 2007

The suppression of fluid force acting on a square prism near plane wall was studied by attaching fences on the corners of the prism. The height of the fence was 10% of the square width and the range of Reynolds number considered was Re=$2.0{\times}10^4$. The experimental parameters were the attaching position and numbers of fences, the space ratios G/B(G/B=0.1${\sim}$1.2) between prism and plane wall. The average drag coefficients were increased and the average lift coefficients were decreased and increased with the space ratios toward plane wall. The drag of the prism was reduced average 7.6% with the space ratios by attaching the normal fence at the rear and upper corner and the horizontal normal fence at the rear and lower corner on the prism. In this case, the separated flow at the front and upper corner was reattached on the upper side of the prism and the vortex streets between the prism and plane wall were appeared more slowly than that of prism without fences.

• Journal of Digital Convergence
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• v.12 no.8
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• pp.211-217
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• 2014

In this paper, by using geofencing technology to set the area you want to move tourists. Geofence set of tourists in the region enters the smartphone by sending e-mail or SMS alarm to display a detailed map of the area to visit assistance. When you arrive at the destination of the museum exhibits or exhibits to the NFC tag attached to each corresponding to a web server for a detailed description of the exhibits from the get-down. Multimedia content using an existing exhibits described. Media of exhibition space and the interaction between the visitors tour guide system capable was built.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.957-962
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• 2013

This paper presents a performance testing device for safety fences of domestic professional baseball stadiums. Safety fences of professional stadiums have been fabricated and installed without adhering to any safety regulations, safety fences demonstrate critically low safety performances and many outfielders are severely injured every season. In this study, we designed and fabricated a performance testing device for safety fences and investigated its validity and reproducibility. A HIC (head injury criterion) was used for the statistical analysis of colliding data. We found that the optimal expulsion pressure and eliminated the accelerometer by replacing it with a velocity sensor using an estimation of the correlation between the momentum data obtained from velocity sensor and the impulse data from the accelerometer.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.8-14
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• 2005

Understanding of the flow past a bluff body close to a moving ground is very important in automobile and aeronautical fields because of aerodynamic characteristic and instability induced by unsteady vortex shedding. The passive control method that mounted the vertical and horizontal plates at the lower surface of the cylinder is studied to suppress the unsteady oscillation motion. When the grounds moves, the diminish of the shear layer on the ground promotes the interaction between the lower and the upper separated shear layers of the cylinder, hence vortex shedding occurs at the lower gap height than the stationary ground.

• Cartoon and Animation Studies
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• s.9
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• pp.143-160
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• 2005

This study was performed on purpose to consider the charade function of props in directing animation. The prop is gradually expanded its role and scope in modern animation. Its scope covers dramatic factors, creating and changing characters, the means of psychological description or emotional expression, mise-en-scene, montage, creating products etc. Like this, the prop has an important function emotionally or indispensably in human life. Thus, the prop should be a subject that can speak to audiences or viewers, not worthless and silent subject. Hence, the prop should be recognized as a charade having productional function. Nevertheless, the prop has been unnoticed up to now. The function of props should be valued hereafter. The prop itself is meaningless, but it always speaks to audiences on the screen.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1861-1863
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• 2001

본 연구에서는 국내에서도 아직 초기단계 기술이라고 할 수 있는 간섭계를 이용한 주요 시설물(변전소등) 안전 감시 혹은 항만 감시 및 방어용 광섬유 격자 그물망 구현을 위한 광섬유 시스템 적용성을 연구한 것이다. 연구에서는 마흐젠더 간섭계의 구성에 비해 구성이 용이한 Sagnac간섭계를 구성 실험하였다. 이 간섭계의 성능 검증을 위하여 1550nm의 중심파장을 방사하는 레이저, 싱글모드 광섬유, 3${\times}$3 커플러 등의 광소자를 사용하였고, 광섬유의 길이의 변화를 주기 위하여 PZT 위상 변조기에 교류 전원을 인가하여 PZT 위상 변조기의 진동을 유도하였다. 또한, 전체 길이 약 180cm, 17${\times}$7, 철봉의 직경 6m의 철망 구조물을 제작후, 센서 부분의 역할을 담당한 광섬유 케이블을 일정한 간격으로 철망 구조물에 케이블 타이로 고정하였다. 철망 구조물에서 발생할 수 있는 각종 외부 가진에 대해, 철망 구조물에 가속도계를 설치하여, Sagnac 간섭계에서의 광 간섭 신호와 가속도계의 신호를 비교 검증 하였다. 본 실험결과를 통하여 광섬유 펜스는 주요 시설물(변전소등) 안전 감시 혹은 항만 감시 및 방어용 경보 시스템에 적합하다고 판단된다.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.94-99
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• 2008

The characteristics of the flowfield of a square prism having fences on the corner was investigated by the PIV. Strouhal numbers, velocity vectors and velocity profiles around the square prism were observed at various positions of the fences, and Reynolds number of $Re=0.6{\times}10^4{\sim}1.0{\times}10^4$. As the results in case of the prism having fences the Strouhal numbers were all smaller than in case of the prototype prism. In case of the prism having vertical fences on the front corners the concentrated intensity of the vorticity was the strongest and the size of separated shear layer was the largest. While in case of the prism having vertical fences on the rear corners the concentrated intensity of the vorticity was the weakest and the size of separated shear layer was the smallest. Also in this case, the flow separated in front corner was reattached around the rear corner and made circulation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.7
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• pp.915-926
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• 1998

Velocity fields of near turbulent was behind a porous wind fence were measured using the 2-frame PTV method in a circulating water channel. The fences used in this study had different geometric porosity(.epsilon.) of 0, 20, 40 and 65%. The fence was embedded in a thin laminar boundary layer, i.e., .delta./H ~ = 0.1. Reynolds number based on the fence height H and free stream velocity(U$\_$o/) was about 8,400. As a result, a recirculating flow region was formed behind the fence for the .epsilon.=0% and 20% wind fence. For the wind fences having porosity larger than .epsilon.=40%, it was difficult to see separation bubbles behind the fence. The .epsilon.=20% porous fence reveals the maximum velocity reduction, however, the turbulent intensity and Reynolds shear stress are much greater than those of .epsilon.=40% fence. Among the wind fence tested in this study, the porous wind fence of .epsilon.=40% porosity is the most effective for abating wind erosion.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.7
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• pp.69-74
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• 2003

By employing vane tip concept, a new rotor blade (NRSB-I) has been designed to enhance the noise characteristics of BERP blade. Numerical analyses have been performed for hovering rotor and the results are compared with respect to those of original BERP blade. Although the thrust of designed rotor decreases by 6-7% due to cutout at the tip region, the results indicate that the actual performance loss is negligible because power reduction is greater than thrust loss. It is also found that aerodynamic fence is required at the outboard kink to obtain clearly separated twin-vortices because the vortex generated at kink is diffused during the convection over the blade surface.