• 한국멀티미디어학회논문지
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• 제21권11호
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• pp.1327-1332
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• 2018

An AGV(Automated Guided Vehicle) where is running on production automated system is related efficiency of production system similarly. On previous study proposed a path collision avoidance algorithms using shortest path of AGV. Running time about loading and unloading with shortest path of AGV is important factor to decide the production system efficiency. In this paper, we propose a method of shortest path and shortest time. Also propose the decision making method of collision avoidance position for setup a shortest runway for next command. To do verify the proposed method consist a simulation for AGV. Finally, we compare and analyse the proposed system between the existing system and show that our system can effectively the performance.

• 상하수도학회지
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• 제12권1호
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• pp.81-87
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• 1998

The possibility of collision of two particles slowly settling one after another in water can be described using the collision efficiency factor in differential sedimentation (${\alpha}_{DS}$). ${\alpha}_{DS}$ was found to be a function of several parameters particle size, particle size ratio, Hamaker constant, density of liquid and particle, gravity acceleration. Previous researches were limited to the case when there is no electric repulsion assuming that the suspension is destabilized. In this paper, ${\alpha}_{DS}$ is calculated for the stabilized condition. The relative trajectory of two particles are calculated including hydrodynamics, attraction and repulsion forces. Ionic strength and surface potential significantly affect the collision possibility of two settling particles. Depending on the surface potential and ionic strength, ${\alpha}_{DS}$ value is divided into three regions; stable, unstable and transition zone. ${\alpha}_{DS}$ increases as the ionic strength increases, and as the surface charge decreases. This result can be used to model both destabilized and stabilized suspension incorporating the collision efficiency factors of the other coagulant mechanisms such as fluid shear and Browian motion.

• 상하수도학회지
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• 제19권2호
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• pp.161-172
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• 2005

Recently, water treatment methods utilizing microbubbles such as DAF and EF are gaining interest and being studied. Current study is focused on the fundamental research of electroflotation by examining the characteristics of microbubbles and particles. The objects of this research consist of two things; (1) theoretical modeling of microbubble-particle collision, (2) the experimental investigation of removal efficiency of turbidity in electroflotation. From investigation, the mechanism of electroflotation can be explained not only by the characteristics of microbubbles and particles but also the chemistry of aluminum dissolved from aluminum electrode during the electroflotation experiment.

• 한국통신학회논문지
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• 제36권9B호
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• pp.1092-1097
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• 2011

An anti-collision protocol which tries to minimize the collision probability and identification time is the most important factor in all identification technologies. This paper focuses on methods to improve the efficiency of tag's process in identification systems. Our scheme, Binary Slotted Query Tree (BSQT) algorithm, is a memoryless protocol that identifies an object's ID more efficiently by removing the unnecessary prefixes of the traditional Query Tree (QT) algorithm. With enhanced QT algorithm, the reader will broadcast 1 bit and wait the response from the tags but the difference in this scheme is the reader will listen in 2 slots (slot 1 is for 0 bit Tags and slot 2 is for 1 bit Tags). Base on the responses the reader will decide next broadcasted bit. This will help for the reader to remove some unnecessary broadcasted bits which no tags will response. Numerical and simulation results show that the proposed scheme decreases the tag identification time by reducing the overall number of request.

• 한국항해학회지
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• 제12권1호
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• pp.71-84
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• 1988

For traffic proceeding in random directions on a plane surface the frequency of collision, if no avoiding action in taken ,is approximately proportional to the square of the traffic density and directly proportional to the size and speed of the ship, Avoiding is normally taken and the rte of collisions is therefore also governed by additional factors such as the visibility, the effectiveness of the collisionavoidance rules, the competence of personnel or watchkeeping attitude, the maneuverability of the ship and the efficiency of radar and other equipments. From the viewpoint of watchkeeper who is responsible for maneuvering, watchkeeping attitude such as lookout and action to avoid collision is the most controllable factor among those mentioned above. In practice, according to the investigation of the institution of marine courts, about 50% co collisions occurred is caused by disorbedience to steering and sailing rules of international regulations for preventing collision at sea including lookout. So we classify the process of collisions with first sight of another ship , assessment of risk of collisions and action to avoid collisions and make a factural survey about lookout and action to avoid collisions from the point on "time" and " distance", namely relationship among ship's size, speed, first sight time of another ship, action to avoid collisions ,and distance from sight of another ship to collision occurred. According to the results of the actual survey , we come to conclude that most of collisions occurred are due to improper lookout and ineffective action to avoid collision which means time lag from first sight of another ship to time of action taken to avoid collision is relatively long. is relatively long.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2625-2634
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• 2022

Discretization errors are extremely challenging conundrums of discrete ordinates calculations for radiation transport problems with void regions. In previous work, we have presented a multi-collision source method (MCS) to overcome discretization errors, but the efficiency needs to be improved. This paper proposes a goal-oriented algorithm for the MCS method to adaptively determine the partitioning of the geometry and dynamically change the angular quadrature in remaining iterations. The importance factor based on the adjoint transport calculation obtains the response function to get a problem-dependent, goal-oriented spatial decomposition. The difference in the scalar fluxes from one high-order quadrature set to a lower one provides the error estimation as a driving force behind the dynamic quadrature. The goal-oriented algorithm allows optimizing by using ray-tracing technology or high-order quadrature sets in the first few iterations and arranging the integration order of the remaining iterations from high to low. The algorithm has been implemented in the 3D transport code ARES and was tested on the Kobayashi benchmarks. The numerical results show a reduction in computation time on these problems for the same desired level of accuracy as compared to the standard ARES code, and it has clear advantages over the traditional MCS method in solving radiation transport problems with reflective boundary conditions.

• 정보처리학회논문지B
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• 제10B권5호
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• pp.567-574
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• 2003

최근 하드웨어의 급속한 발전으로 3차원 그래픽의 적용 분야도 다양화 되어가고 있다. 3차원 가상도시를 배경으로 하는 3D MMORPG(Massive Multi-play Online Role Playing Game)와 같은 게임을 설계하기 위하여 필요한 세부 기술은 다양한 이론이 병합되어야 한다. 3D MMORPG 게임엔진은 거대한 3차원 도시의 수많은 빌딩과 개체론 실시간으로 빠르게 처리되어야 하기 때문에 렌드링의 처리뿐만 아니라 속도에 영향을 미치는 많은 요소를 가지고 있다. 이러한 게임엔진의 설계에서 중요하게 다루어지는 것은 처리 속도이다. 기존의 3D MMORPG에서 충돌검출의 방법으로 경계상자를 적용하지만 이 방법은 거대지형에서의 충돌 검출 시 속도가 느려지기 때문에 적용하기에는 바람직하지 않다. 따라서 본 논문은 거대지형상의 3D MMORPG 게임에서 발생되는 충돌검출 속도를 향상시키고자 한다. 즉 이러한 처리에서 본 논문은 다음과 같이 제시한다. 첫째 폴리곤의 충돌검사를 모두 하지 않고 빠른 시간에 충돌검출을 판단할 수 있다. 둘째 경계상자의 충돌검출에 대한 비용이 3차원 개체 개수에 대해 비례하여 증가하는 데에 대한 개선 방법을 제시한다. 그 처리 과정은 3D MMORPG 넓은 가상공간을 동적으로 처리하기 위해서는 제한적 OSP를 사용하여 공간분할을 한다. 분할된 3차원 공간을 계층적 경계상자를 이용함으로써 충돌검출에 필요한 개체를 검색하고 이론 통하여 충돌검출 속도를 개선시킬 수 있을 것이다.

• 한국재료학회지
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• 제13권4호
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• pp.271-278
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• 2003

Conventional backlight for liquid crystal display (LCD) uses mercury which leads to environmental pollution. In this study, characteristics of AC coplanar type mercury-free plasma flat lamp have been studied. Pollution-free Xe-He is adopted as a discharge gas system. Since the Xe gas has a lower efficiency in generating vacuum ultraviolet (VUV) than mercury, the improvement of luminance and luminous efficiency in the Xe gas system is very important. The electrode, dielectric, and phosphor layers constituting lamp are formed on the bottom glass by the screen printing method. The effects of pulse shape, on-time, and pulse frequency on the luminance and luminous efficiency have been examined. For Xe(5%)-He gas, the lamp exhibits higher efficiency with sharper pulse shape, higher peak voltage, and shorter pulse on-time (up to 2 $\mu\textrm{s}$). Higher efficiency and lower consumption of power were obtained at 30 kHz than at 60 kHz. The collision of ion to bottom electrodes is a dominant factor to raise the lamp temperature. Therefore the high voltage and low current discharge system is necessary for reduction of the lamp temperature as well as for enhancement of the luminous efficiency.

• Journal of information and communication convergence engineering
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• 제4권4호
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• pp.141-146
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• 2006

In these days, wireless data services are becoming ubiquitous in our daily life because they offers several fundamental benefits including user mobility, rapid installation, flexibility, and scalability. Moreover, the requests for various multimedia services and the Quality of Service (QoS) support have been one of key issues in wireless data communications. Therefore the research relative to Medium Access Control (MAC) has been progressing rapidly. Especially a number of QoS-aware MAC schemes have been introduced to extend the legacy IEEE 802.11 MAC protocol which has not guaranteed any service differentiation. However, none of those schemes fulfill both QoS features and channel efficiency although these support the service differentiation based on priority. Therefore this paper studies a novel MAC scheme, referred to as Enhanced Distributed Coordination Function with Network Adaptation (EDCF-NA), for enhancements of both QoS and medium efficiency. It uses a smart factor denoted by ACK rate and Network Load Threshold (TH). In this paper, we study how the value of TH has effect on MAC performance and how the use of optimal TH pair improves the overall MAC performance in terms of the QoS, channel utilization, collision rate, and fairness. In addition, we evaluate and compare both the performance of EDCF-NA depending on several pairs of TH and the achievement of various MAC protocols through simulations by using Network Simulator-2 (NS-2).

• 한국항해항만학회지
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• 제37권6호
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• pp.587-595
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• 2013

항만건설 및 운영에서 해양교통시설의 설치와 운영은 해상충돌방지 및 안전에서 매우 중요한 인자이다. 그리고, 해상교통시설의 설치 및 운영은 IMO SOLAS 5장 제13조에 의하여 당국의 의무사항으로 규정되어 있다. 해양교통시설은 과거의 시각적(광학, 형상) 시설에서 AIS, DGPS 및 기타 전파표지 등을 활용한 e-Navigation의 개념으로 발전하고 있다. 그러나 이러한 해양교통시설의 자동화 흐름에도 불구하고 선박의 안전한 항해를 위한 광파표지 및 형상표지의 역할은 여전히 절대적이다. 본 연구에서는 시각표지의 운영관리 효율을 향상시키기 위한 해양교통시설 서비스수준의 결정방법으로 해상교통관련 전체 시설을 하나의 관리시스템으로 조합하고 더욱 효율적인 시스템 관리방안으로서 항로표지 운영율을 제안하였다. 해외의 서비스 수준에 대한 비교와 이론적 배경을 분석하고, 제안된 서비스수준을 인천해역에 실제 적용하여 항로의 안전성을 평가한 사례를 제시하였다.