• 한국통신학회논문지
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• 제19권7호
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• pp.1213-1223
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• 1994

저속데이타 전용 지구국시스템은 상업 위성통신분야에서 새로운 개념으로 알려져 있으며 성형망 구조로 사용자들에게 직접 정보를 제공하는데 이용된다. 본 시스템의 특성은 지구국 가격이 낮고, 크기가 작고, 설치가 간단하며 다양한 응용(신용조회, 전자우편, 화상회의, 예약시스템, DB요청, 참가신청등)을 가능하게 한다. 그러므로 VSAT서비스에 대한 요구가 상당히 커지고 있다. 본 논문은 무궁화위성을 이용하는 VSAT망의 링크설계에 관한 연구이다. 본 논문에서 위성통신시스템의 성능계산을 하는데 필요한 기본 공식 및 기준데이타를 편리하게 나열하였고, 지구국의 안테나 및 HPA출력크기 그리고 링크마진을 계산하였다. 일반적으로 VSAT시스템에서 중심국의 안테나 크기는 단말국의 안테나보다 크기 때문에 본 논문에서 인바운드(Inbound)와 아웃바운드(Outbound)의 반송과 전력분배 기법을 도입하였으며 중심국과 단말국의 안테나 크기는 각각 3.7m와 1.2 m로 설계되었다.

• 지능정보연구
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• 제12권1호
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• pp.125-137
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• 2006

컨테이너 터미널에서의 효율적인 운영을 위한 장치장 운용계획은 터미널 생산성을 향상 짓는 중요한 요소이다. 본 연구에서는 장치장 운용 시 고려되는 의사결정 요소들을 살펴보고 그 대안을 제시하였다. 의사결정 요소는 크게 두 가지로 장치 장에 컨테이너 저장 시 고려되는 블록의 용도구분에 관한 것과 각 블록에 할당하는 RMGC(Rail Mounted Gantry Crane) 야드 크레인의 대수를 결정하는 것이다. 각 요소 별 제시되는 대안은 시뮬레이션기법을 통하여 평가해 보고자 한다.

• 산업경영시스템학회지
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• 제43권4호
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• pp.59-66
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• 2020

In this study, we consider the problem of forecasting the number of inbound foreigners visiting Korea. Forecasting tourism demand is an essential decision to plan related facilities and staffs, thus many studies have been carried out, mainly focusing on the number of inbound or outbound tourists. In order to forecast tourism demand, we use a seasonal ARIMA (SARIMA) model, as well as a SARIMAX model which additionally comprises an exogenous variable affecting the dependent variable, i.e., tourism demand. For constructing the forecasting model, we use a search procedure that can be used to determine the values of the orders of the SARIMA and SARIMAX. For the exogenous variable, we introduce factors that could cause the tourism demand reduction, such as the 9/11 attack, the SARS and MERS epidemic, and the deployment of THAAD. In this study, we propose a procedure, called Measuring Impact on Demand (MID), where the impact of each factor on tourism demand is measured and the value of the exogenous variable corresponding to the factor is determined based on the measurement. To show the performance of the proposed forecasting method, an empirical analysis was conducted where the monthly number of foreign visitors in 2019 were forecasted. It was shown that the proposed method can find more accurate forecasts than other benchmarks in terms of the mean absolute percentage error (MAPE).

• 대한안전경영과학회지
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• 제10권2호
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• pp.187-193
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• 2008

Cross docking is a warehouse management concept in which items delivered to a distribution facility by inbound trucks are immediately sorted out and reorganized based on customer demands and are routed and loaded into outbound trucks for delivery to customers without actually being held in inventory in the distribution facility. In this research, the design of distribution facility for cross docking systems was studied. The objective of this research is to find the minimum number of receiving docks and shipping docks, respectively, in order to meet the daily demand of the distribution center. Two solution approaches are employed in modeling and solving the problem The first approach is mathematical modeling and the second approach is a simulation. The logic developed in the simulation model is expected to apply to the real world situation.

• Ocean Systems Engineering
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• 제9권1호
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• pp.43-77
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• 2019

A local-analytic-based Navier-Stokes solver has been employed in conjunction with a compound ocean structure motion analysis program for time-domain simulation of passing ship effects induced by multiple post-Panamax class ships in the exact condition of a real waterway. The exact seabed bathymetry was reproduced to the utmost precision attainable using the NOAA geophysical database for Virginia Beach, NOAA nautical charts for Hampton Roads and Norfolk harbor, and echo sounding data for the navigation channel and waterfront facilities. A parametric study consists of 112 simulation cases with various combinations of ship lanes, ship speeds, ship heading (inbound or outbound), channel depths, drift angles, and passing ship coupling (in head-on or overtaking encounters) were carried out for two waterfront facilities at NAVSTA Norfolk and Craney Island Fuel Terminal. The present paper provides detailed parametric study results at both locations to investigate the site-specific passing ship effects on the motion responses of ships moored at nearby piers.

• 경영과정보연구
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• 제32권3호
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• pp.107-125
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• 2013

본 연구에서는 공장-물류센터-고객으로 이어지는 공급사슬 네트워크를 구축하려는 기업의 의사결정에 도움을 주기 위해 2단계 공급사슬네트워크 설계를 위한 수학적 모형을 제시하고, 현실적인 문제를 대상으로 다양한 시나리오를 통한 민감도 분석을 수행하였다. 본 연구에서는 기존의 연구에서와는 달리 공장과 물류센터의 동시 입지선정, 공장과 물류센터의 용량 수준 결정, 공장과 물류센터의 설치 개수 제한과 같은 조건들을 모두 문제에 반영함으로써 현실 상황에 가장 가까운 문제를 대상으로 수학적 모형을 제시하였다. 기존의 연구들은 대부분 근사해를 찾아내는 효율적인 휴리스틱 해법 개발에 초점을 맞추었다. 그러나 본 연구에서는 공급사슬 네트워크 설계를 위해 다양한 시나리오들을 설정하고 각 시나리오별 결과를 분석하여 최적의 의사결정을 내리는데 도움을 주고자 하였다. 이를 위해 문제 크기별로 서로 다른 $5{\times}10{\times}30$, $10{\times}10{\times}100$, $10{\times}20{\times}200$ 등 세 가지 형태의 예제 문제를 만들고 엑셀의 해찾기 기능을 적용하여 풀어 보았다. 이 중에서 공장 후보지 10군데, 물류센터 후보지 20군데, 최종 고객 대리점 200군데인 $10{\times}20{\times}200$ 문제에 대해 공장과 물류센터 설치 개수에 대한 상한 제약조건을 배제한 문제를 추가적으로 풀어 보았다. 공장의 최적 입지 선정 결과를 고정시킨 채 물류센터 설치 개수를 변화시켜 가면서 모두 7가지 시나리오를 설정하여 민감도 분석을 수행해 보았다. 물류센터 설치 개수가 늘어남에 따라 inbound 수송비와 outbound 수송비가 어떻게 변하는지를 알아봄으로써, 기업 입장에서 비용뿐만 아니라 고객의 서비스 수준도 함께 고려하여 의사결정을 내리는데 도움이 될 수 있음을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2781-2800
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• 2016

Emerging attacks aim to access proprietary assets and steal data for business or political motives, such as Operation Aurora and Operation Shady RAT. Skilled Intruders would likely remove their traces on targeted hosts, but their network movements, which are continuously recorded by network devices, cannot be easily eliminated by themselves. However, without complete knowledge about both inbound/outbound and internal traffic, it is difficult for security team to unveil hidden traces of intruders. In this paper, we propose an autonomous anomaly detection system based on behavior profiling and relation mining. The single-hop access profiling model employ a novel linear grouping algorithm PSOLGA to create behavior profiles for each individual server application discovered automatically in historical flow analysis. Besides that, the double-hop access relation model utilizes in-memory graph to mine time-sequenced access relations between different server applications. Using the behavior profiles and relation rules, this approach is able to detect possible anomalies and violations in real-time detection. Finally, the experimental results demonstrate that the designed models are promising in terms of accuracy and computational efficiency.

• 기술사
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• 제34권1호
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• pp.14-22
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• 2001

Kimpo International Airport, located within the Seoul metropolitan district, experienced a sudden surge of passengers and cargo in recent years. In 1990, MOCT sponsored feasibility studios and Youngjong Island location was selected as the most suitable choice among four proposed sites to build a new airport. The construction work was then commenced in November 1992. Phase I project facilities are scheduled to start its operation in March 2001 with an annual capacity of 27 million passengers and 1.7 million tons of cargo for both enplaning and deplaning from International liners. Kimpo International Airport will remain in operation primarily for domestic passengers and cargo only. Phase II project construction work will add two more runways with its related facilities by 2005. Inchon International Airport will then conveniently serve 100 million passengers for enplaning and deplaning, and 7 million tons of inbound and outbound cargo annually in its full capacity. All the airport facilities In phase I and phase II periods are constructed to meet international standards. A fully integrated transportation network and logistics function systems should be accomplished prior to the full operation of the airport. With these sccomplishments, the state-of-the-art airport is poised to meet the needs of a rapidly growing worldwide air transport industry, and will more than adequately fulfill its role as a hub airport for the Northeast Asia region.

• 대한산업공학회지
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• 제37권4호
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• pp.331-341
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• 2011

This paper considers an inbound lot-sizing and outbound dispatching problem for a single product in a thirdparty logistics (3PL) distribution center. Demands are dynamic and finite over the discrete time horizon, and moreover, each demand has a delivery time window which is the time interval with the dates between the earliest and the latest delivery dates All the product amounts must be delivered to the customer in the time window. Ordered products are shipped by multiple vehicle types and the freight cost is proportional to the vehicle-types and the number of vehicles used. First, we formulate a mixed integer programming model. Since it is difficult to solve the model as the size of real problem being very large, we design a conventional genetic algorithm with a local search heuristic (HGA) and an improved genetic algorithm called adaptive genetic algorithm (AGA). AGA spontaneously adjusts crossover and mutation rate depending upon the status of current population. Finally, we conduct some computational experiments to evaluate the performance of AGA with HGA.

• Industrial Engineering and Management Systems
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• 제11권3호
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• pp.276-287
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• 2012

Determining storage locations of containers is an important issue for efficient operation of container terminals. This study assumes a storage yard with a horizontal layout in which blocks are laid out in parallel to the quay and trucks enter at the side of a block to deliver (receive) a container to (from) the yard crane. Various storage rules for determining storage locations of containers are introduced. Simulation studies are conducted for evaluating various rules. The following guidelines are derived from the result of our simulation study: when designing a block, consider a block configuration in which the longest gantry and the longest trolley travel times of rail-mounted gantry cranes (RMGCs) are similar; do not restrict the types of containers that can be stored in a storage area; if different roles are to be assigned to different storage areas, one possible way is to divide a bay into two areas so that some rows in the bay are allocated to inbound containers while the other rows in the same bay are allocated to outbound containers; reserve the space in bay unit for a high productivity of RMGCs but reserve the space in stack unit when the storage space is not enough; when the storage space is not sufficient, allocate storage location in a way of starting from the end and ending at the middle of a block; for reducing the travel distance of internal trucks, provide a higher priority to a block nearer to the berthing position of the corresponding vessel.