• Explosives and Blasting
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• v.28 no.2
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• pp.37-49
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• 2010

Ground vibration caused by blasting in the urban area close to structures can give some indirect damage to human body and may lead to structural damage to buildings. At the stage of design or when complaints were filed by residents, the test blasting in borehole, which is most practical for expressing simple vibration wave form quantitatively, is usually chosen for assessing the degree of damage to structures. In this paper, some lessons gained from the application of electronic detonator triggering system in borehole test blasting are presented. The difference in delay time of detonator when borehole is blasted by electronic detonator and electric detonator are discussed. The peak particle velocities measured at the structure embedded in the similar rock layer to main line of tunnel at test site and measured at the road surface just above the tunnel having different overburden layers were analysed to draw their relationship. By comparing the results with those appearing in some published literatures, the usefulness of the borehole test blasting and the importance of delay time of detonator are addressed.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.7 no.2
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• pp.19-24
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• 2001

The design criteria of ventilating container is not provided yet in Korea. This caused strength reduction due to the ventilating hole and bad ventilating performance. The purposes of this study were to survey the present situation of ventilating container in Korea, to analyze the strength reduction on the atmosphere condition variation, and to provide the criteria for the optimum design of ventilating container. The ventilating area of container was $1.41{\sim}2.65%$, and strength reduction due to the varied pattern, size and location of ventilating hole was $8.5{\sim}20.2%$. The effect on the strength reduction from the pattern and location of ventilating hole was bigger than that from the ventilating area. Equilibrium arrival time of temperature and relative humidity was shorter as the ventilating area was bigger, and temperature reached to the equilibrium state earlier than the relative humidity. There was no significant difference on the ventilating hole pattern between equilibrium arrival time of temperature and relative humidity and equilibrium arrival temperature and relative humidity if the ventilating area was the same.

• Journal of KIISE:Databases
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• v.34 no.6
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• pp.518-527
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• 2007

It is an important issue to find out the difference between RDF documents, because RDF documents are changed frequently. When RDF documents contain blank nodes, we need a matching technique for blank nodes in the change detection. Blank nodes have a nested form and they are used in most RDF documents. A RDF document can be modeled as a graph and it will contain many subtrees. We can consider a change detection problem as a minimum cost tree matching problem. In this paper, we propose a change detection technique for RDF documents using the labeling scheme for blank nodes. We also propose a method for improving the efficiency of general triple matching, which used predicate grouping and partitioning. In experiments, we showed that our approach was more accurate and faster than the previous approaches.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.203-210
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• 2013

To look into site characteristics of the Hwacheon borehole seismic station, we analyzed property of earthquake and microtremor recorded on surface and borehole seismometers. Acoording to analysis result of microtremor, the surface-to-borehole energy ratio was approximately 15 times greater during the daytime than during the nighttime, and the surface-to-borehole ratios of spectral amplitudes as frequency increases. For earthquake data, amplitude spectra and dominant frequency were computed using surface and borehole data. As a result, small earthquakes with short distance recorded on surface seismometer peaked at 8 Hz, 46 Hz. This result corresponds to resonance frequencies (7.4 Hz, 46 Hz) calculated by H/V spectral ratio. We confirmed amplification effect by site characteristics of overburden. Background noise level was approximately 20,000 times smaller at borehole seismic station than surface seismic station. These results provide strong evidence for the superior recording of earthquakes using borehole seismometers instead of surface seismometers.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.235-243
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• 2011

In this study, a control blast method, which utilizes crack guide holes, is suggested to achieve smooth fracture plane and minimize blast damage zone (BDZ) in smooth blasting. In order to verify the effectiveness of crack guide holes on the fracture plane control in blasting, fracture process analyses which consider regular smooth blasting and guide hole smooth blasting had been conducted and the fracture planes resulting from the analyses had been compared. The analyses models considered the ignition of the blast holes using detonation cords and each guide hole placed between blast holes. From the results, the smooth blasting utilizing guide holes showed lower fracture plane roughness than regular smooth blasting method in the hole spacing range between 20 to 40cm.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.3
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• pp.275-281
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• 2011

One of the major technology issues in the ship production processes is the curved hull forming process that is a bottle neck and performed by experienced workers. In order to automate the curved hull forming process, there are a lot of attempts to develop the automation system by many shipbuilding companies and academic labs. However they have some problems which put the developed system in the difficulties to be used and maintained in the yard. In this paper, the problems are formed and solved by using tailored Systems Engineering Process which consists of four steps, those are requirement definition, system design, implementation of subsystem and components, and system integration and verification. A prototype for the proposed system development methodology is implemented. From the consideration of the prototype implemented, it is verified that this methodology can be an alternative to solve the problems.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.75-85
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• 2003

Laboratory model blast and in-situ rock blast tests were conducted to determine blast-induced stress wave propagation characteristics under different explosive types, different loading conditions and different mediums. Dynamic numerical approaches were conducted under the same conditions as experimental tests. Stress magnitudes at mid-point between two blast holes which were detonated simultaneously increased up to two times those of single hole detonation. The rise time of maximum stress in a decoupled charge condition was delayed two times that of a fully charged condition. Dynamic numerical analysis showed almost similar results to blast test results, which verifies the effectiveness of numerical approaches fur optimizing the tunnel blast design. Dynamic numerical analysis was executed to evaluate rock behavior and damage of the contour hole, the sloping hole adjacent to the contour hole in the road tunnel blasting pattern. The rock damage zone of the sloping hole from the numerical analysis was larger than that of the contour hole. Damage in the sloping hole can be reduced by using lower density explosive, by applying decoupled charge, or by increasing distance between the sloping hole and the contour hole.

• Journal of Bio-Environment Control
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• v.6 no.1
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• pp.55-65
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• 1997

This study was conducted to develop a robotic transplanter for bedding plants. The robotic transplanter consisted of machine vision system, manipulator attached with the specially designed gripper, and plug tray transfer system. Results of this study were as follows. 1. A machine vision system for a robotic transplanter was developed. The success rates of detecting empty cells and bad seedlings in 72-cell and 128-cell plug-trays for cucumber seedlings were 98.8％ and 94.9％ respectively. The success rates of identifying leaf orientation for 72- cell and 128-cell plug-trays were 93.5% and 91.0%, respectively. 2. A cartesian coordinate manipulator for a robotic transplanter with 3 degrees of freedom was constructed. The accuracy of position control was $\pm$ 1mm. 3. The robotic transplanter was tested with a shovel-type finger. Without considering leaf orientation, the success rates of transplanting healthy cucumber seedlings for 72-cell and 128-cell plug-trays were 95.5% and 94.5%, respectively. Considering leaf orientation, the success rates of transplanting healthy cucumber seedling in 72-cell and 128-cell plug-trays were 96.0% and 95.0%, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.259-259
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• 2018

최근 우리나라는 기후변화에 따른 태풍발생빈도 증가 및 이상강우, 유역내 토지이용의 고도화로 인한 유역특성 변화로 유역내 홍수량은 증가하고 홍수 도달시간이 짧아지는 양상을 보이고 있다. 이로 인해 홍수에 따른 치수방어 대책으로 하천의 제방축조 및 보강방법이 주로 채택되었으나, 최근에는 홍수시 직접적인 하천내 수위 저감을 위한 방안으로 하도내 저류효과를 확대하기 위한 보 설치 및 하도정비를 통한 하도준설을 시행하고 있다. 그러나 본류 하상저하에 따른 지류하천의 하상변동(두부침식)으로 하도내 세굴 침식에 의한 하천시설물 피해 사례가 늘게 되면서 과거 홍수에 의한 제방월류 피해에서 하상변동에 의한 하천시설물 붕괴로 하천피해 양상이 바뀌게 되었다. 이와 같은 피해를 방지하기 위해 지류하천 합류부에 하상변동 방지책으로 하상유지공을 설치하고 있지만 국내에는 이와 관련된 구체적 설계기준 및 연구가 미비하여 일선에서는 아직도 하천구조물의 용도가 다른 보나 낙차공의 설계기준을 준용하는 등 하상유지공 용도에 특성화된 설계기준(최적 위치선정 및 형식 등)이 없는 실정이다. 본 연구에서는 감천(낙동강 지류하천)유역내 하도준설 및 홍수로 인한 하상유지공의 유실에 따른 지류하천의 피해사례를 통해 수치해석결과 및 실측자료를 바탕으로 하상유지공 계획의 중요성을 검증하고자 하였다. 또한 하도준설로 생성된 지류합류부의 단차구간에 안정성을 확보한 최적의 하상유지공 위치 및 형식 등을 선정 검토하고 설치 유 무에 따른 유수흐름 및 하상변화양상을 비교 분석하였다. 본 연구의 결과를 토대로 향후 하도굴착 및 하상유지공 계획시 고려해야할 사항(지형현황 및 수리특성 등)을 인지하고 극한상황에서도 안전한 하상유지공의 위치 및 형식 등을 선정하는데 활용 가능할 것으로 판단된다.

• Journal of IKEEE
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• v.26 no.2
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• pp.150-159
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• 2022

In this paper, we propose a physics simulation for augmented reality (AR) billiards content. The characteristics of the physics simulation for the proposed AR billiards content are as follows. First, physical equations are derived by calculating the force and moment of inertia applied to the billiards ball to realize the motion of the billiards ball similar to the real one in the AR environment. Then, we determine the velocity and angular velocity of the virtual billiards ball associated with the rotation of the virtual billiards ball with respect to the impact point. Second, using some vectors such as incidnet vector, normal vector, reflection vector, the trajectory of the virtual billiards ball would be implement. these equations are applied to AR environment so that AR billiards content could be implement. This physics simulation allows users to feel like the real world using a virtual pool table and induce them to interact with the real environment. As a result of the experiment, the accuracy range between the path of the real billiards ball and the path of the virtual billiards ball was calculated to be 97.75% to 99.11%. Therefore, it was determined that the performance of the physics simulation for the AR billiards content proposed in this paper performs similarly to the path of the real billiards ball.