• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.1377-1399
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• 2020

In search and rescue mission, micro aerial vehicles (MAVs) are typically used to capture image and video from an aerial perspective and transfer the data to the ground station. Because of the power limitation, a cluster of MAVs are required for a large search area, hence an ad-hoc wireless network must be maintained to transfer data more conveniently and fast. However, the unstable link and the intermittent connectivity between the MAVs caused by MAVs' movement may challenge the packet forwarding. This paper proposes a delay tolerant packet forwarding algorithm based on location estimation for MAV networks, called DTN_est algorithm. In the algorithm, ferrying MAVs are used to transmit data between MAVs and the ground station, and the locations of both searching MAVs and ferrying MAVs are estimated to compute the distances between the MAVs and destination. The MAV that is closest to the destination is selected greedy to forward packet. If a MAV cannot find the next hop MAV using the greedy strategy, the packets will be stored and re-forwarded once again in the next time slot. The experiment results show that the proposed DTN_est algorithm outperforms the typical DTN_geo algorithm in terms of packet delivery ratio and average routing hops.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.366-372
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• 2007

본 연구에서는 기 구축된 수도GIS 활용의 활성화 및 정보제공 기반의 체계성을 확보하여 수도관리 업무의 수행에 있어 과학화 달성을 위한 유비쿼터스 기반의 수도관리 방안을 수립하고자 하였다. 이를 위해 기구축된 수도GIS 추진현황 및 GIS DB를 분석하여 최신 IT기술 적용방안을 검토하고, 최신 기술 동향 분석을 통하여 수도GIS의 활용성 극대화를 위한 위치기반서비스(LBS; Location Based Service) 기술을 선정하여 업무전용 모바일 단말기 개발 및 LBS 시스템 설계 구축하였다. 또한, 실시간 수도관리 기술 확보를 위하여 유비쿼터스 기술 및 시스템 활용에 대한 분석을 통해 수도관리 업무의 체계적인 도입을 위한 기술을 검토하여 이를 활용할 수 있는 방안을 제시하였다.

• 한국정보과학회논문지:정보통신
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• 제29권3호
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• pp.216-223
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• 2002

본 논문에서는 차세대 셀룰라 이동통신망을 위한 효율적인 위치관리기법을 설계한다 제안된 기법에서는 사용자를 이동성 특성에 따라 HMU(high mobility user)와 LMU(low mobility user) 두 가지 클래스(class)로 분류하고, 각 사용자 클래스에 따라 각각 적합한 서로 다른 기법으로 위치를 관리한다. 제안된 기법과 순수 지능 페이징 기법의 성능을 컴퓨터 시뮬레이션을 이용하여 비교하여, 제안된 기법이 순수한 지능 페이징 기법에 비해 우수한 성능을 제공함을 보인다.

• 산업경영시스템학회지
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• 제32권2호
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• pp.57-65
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• 2009

In continuous review inventory model, (${\varrho}$, ${\gamma}$) system, order quantity(${\varrho}$) and reorder point(${\gamma}$) should be determined to calculate inventory-related cost that consists of setup, holding, and penalty costs. The procedure to obtain the exact value of ${\varrho}$ and ${\gamma}$ is complex. In this paper, a regression analysis is proposed to get the approximate inventory-related cost without the determination of ${\varrho}$ and ${\gamma}$ in the case that the standard deviation(${\sigma}$) of the lead time demand is small or that the mean(${\mu}$) of the lead time demand is proportional to ${\sigma}$. To save inventory-related cost, central warehouses with (${\varrho}$, ${\gamma}$) system can be built. Central warehouse can provide some stores with products with the consideration of the tradeoff between inventory-related cost and transportation cost. The number and the location of central warehouses to cover all the stores are determined by a regression-based approach. The performance of the proposed approach is tested by using some computational experiments.

• 한국항만경제학회지
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• 제21권4호
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• pp.161-181
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• 2005

This paper investigates the circumstances and conditions of Mokpo Port to develop it as an international logistics stronghold and seeks scheme to maximize the local economic ripple effect through construction and activation of Mokpo New Port. Under the circumstances in which neighboring ports vying with each other have built broad spheres of influence, and competition among ports becomes fierce, a priority cargo attraction strategy should be established by using Mokpo's favorable location compared to other ports in order to ensure that a large quantity of goods is transported from Mokpo New Port. Especially, Mokpo New Port needs to be developed as a vehicles-only exporting port, as well as a port for used car exports and an import port for stones and timber.

• Industrial Engineering and Management Systems
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• 제16권1호
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• pp.103-108
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• 2017

Tourism is a sector that plays an important role in the economic growth of Indonesia. Bandung as the capital of West Java province is known as the city with diverse tourism potential, both in the attractiveness of the city and surrounding natural beauty. DHR is a three stars resort hotel in the city with a strategic location. As a three stars resort hotel, DHR has been experiencing occupancy rate problems, consequently, it cannot often reach the set targets, both during high season and low season. The purpose of this study is to identify the factors of hotel performance that influences consumer staying back decision in the future. Questionnaires have been distributed to hotel guests to gather information regarding their interest and the performance assessment of the hotel services and facilities, and staying back decision in the future. Discriminant Analysis and Hypothesis Testing are used to determine which hotel performance variables will directly affect consumer staying back decision. The result of this study provide marketing strategy that should be implemented by the hotel management in order to increase its occupancy rate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.513-515
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• 2000

This paper deals with a method for determining an optimal operation strategy of dispersed generating sources considering thermal merits. The optimal operation of these sources can be determined by the principle of equal incremental fuel cost. This paper presents an optimal operation strategy using the Kuhn-Tucker's optimal conditions and also an priority method to decide the optimal location of those sources in power systems. The validity of the proposed algorithms are demonstrated using a model system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.24-26
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• 2005

This paper presents a framework for determining control strategies against unwanted tripping actions of relay operation that plays a very important role in cascading events leading to voltage collapse. The framework includes an algorithm for quick identification of possible zone 3 relay operation during voltage instability. The proposed approach comes up with control strategy of load shedding at the selected location with active power and relay margin criteria. In addition, Quasi Steady-State (QSS) simulation is employed to obtain time-related information which is valuable for both the timing and amount of control. The methodology is demonstrated through the modified New England 39-bus system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1044-1047
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• 2005

In this paper, we present the strategy of object search for distributed autonomous robotic systems (DARS). The DARS are the systems that consist of multiple autonomous robotic agents to whom required functions are distributed. For instance, the agents should recognize their surrounding at where they are located and generate some rules to act upon by themselves. In this paper, we introduce the strategy for multiple DARS robots to search a hidden object at the unknown area. First, we present an area-based action making process to determine the direction change of the robots during their maneuvers. Second, we also present Q learning adaptation to enhance the area-based action making process. Third, we introduce the coordinate system to represent a robot's current location. In the end of this paper, we show experimental results using hexagon-based Q learning to find the hidden object.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제10권S_3호
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• pp.97-106
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• 2001

To improve the water quality, particularly for sea bathers, the behaviour of wastewater from sewage outfalls in water adjacent to Swansea, UK, was studied using a mathematical model. The water quality in the sewage receiving basin was determined using factors like the outfall diffuser location(distance from land boundary), sewage treatment scheme, discharge time, and bacteria decay rate, etc. With respect to these factors, an optimal strategy for sewage discharge was then investigated to minimize bacteria levels along the bathing beaches. As water quality criteria, predicted faecal coliform levels were monitored along the coast adjacent to the outfall locations. The resultant values were compared with EC Mandatory(<2000, 95 % of 20 samples) and Guideline Standards(< 100, 80 % of 20 samples). For the advective-diffusion equation, the non linear advective terms were represented using the ULTIMATE algorithm and the third-order accurate QUICKEST scheme to avoid numerical diffusion. Details of the simulation results are then presented as an optimal policy for sewage discharge in the region.