• 한국시뮬레이션학회논문지
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• 제33권1호
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• pp.1-17
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• 2024

숲을 체계적으로 관리하고 경영하기 위해서는 나무생장 변화에 대한 신뢰성 있는 예측이 필요하다. 독일의 아이펠 지역에서는 주요 목재종인 유럽너도밤나무가 식재되어 관리되어 지고 있다. 본 지역의 산림관리자의 실제 산림경영의 경험과 조언을 토대로, 다양한 산림 관리에 따른 단기 및 장기 효과를 예측하고자 지역 특수성을 지니는 시뮬레이션 모델의 접근방법을 개발하고자 하였다. 시뮬레이션 모델은 (1) 묘목 생성, (2) 나무 사멸 조절 (3) 나무 생장의 세 가지 모듈로 구성된다. 산림관리자에 의해 제공된 너도밤나무 숲의 실제 부피 변화를 근사화하기 위해 다양한 변수(나무수, 나무간 거리, 씨앗의 분포, 경쟁)를 반복적으로 수정하여 세 가지 모듈을 결합한 하이브리드 시뮬레이션 모델을 개발할 수 있었다. 본 연구를 통해 유럽너도밤나무 숲의 350년을 모의하여 생장 변화를 예측하였으며, 아이펠 지역의 세 가지 다른 관리 방법 (숲을 보호한 상태에서 목재벌채, 선택적 벌목, 보호림) 시나리오를 적용하였을 때 모의된 결과를 비교하였다. 시뮬레이션 결과를 통해 나무 생장의 변화가 현실적으로 잘 반영되었다는 것을 확인할 수 있었으며, 미래에 장기간 실제 축적된 산림 데이터를 획득하여, 검증과 보정의 과정을 반복한다면 더 높은 정확도의 지역 맞춤형 모델이 개발될 수 있을 것으로 사료된다.

• 한국경영과학회지
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• 제21권3호
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• pp.47-61
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• 1996

An ATM switch must deal with various kinds of input sources having different traffic characteristics and it must guarantee very small value of cel loss probability, about 10$^{8}$ -10$^{12}$ , to deal with loss-sensitive traffics. In order to estimate such a rate event probability with simulation procedure, a variance reduction technique is essential for obtaining an appropriate level of precision with reduced cost. In this paper, we propose a hybrid simulation technique to achieve reduction of variance of cell loss probability estimator, where hybrid means the combination of analytical method and simulation procedure. A discrete time queueing model with multiple input sources and a finite shared buffer is considered, where the arrival process at an input source and a finite shared buffer is considered, where the arrival process at an input source is governed by an Interrupted Bernoulli Process and the service rate is constant. We deal with heterogeneous input sources as well as homogeneous case. The performance of the proposed hybrid simulation estimator is compared with those of the raw simulation estimator and the importance sampling estimator in terms of variance reduction ratios.

• Advances in Energy Research
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• 제4권1호
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• pp.47-68
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• 2016

A well designed hybrid power system (HPS) can deliver electrical energy in a cost effective way. In this paper, model for HPS consisting of photo voltaic (PV) module and wind mill as renewable energy sources (RES) and solar lead acid battery as storage device connected to unidirectional grid is developed for peak demand reduction. Life time energy cost of the system is evaluated. One year hourly site condition and load pattern are taken into account for analysing the HPS. The optimal HPS is determined for least life time energy cost subject to the constraints like state of charge of the battery bank, dump load, renewable energy (RE) generation etc. Optimal solutions are also found out individually for PV module and wind mill. These three systems are compared to find out the most feasible combination. The results show that the HPS can deliver energy in an acceptable cost with reduced peak consumption from the grid. The proposed optimization algorithm is suitable for determining optimal HPS for desired location and load with least energy cost.

• 경영과학
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• 제30권2호
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• pp.31-42
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• 2013

The vehicle routing problem (VRP) can be described as a problem to find the optimum traveling routes from one or several depot (s) to number of geographically scattered customers. This study executes a revised Heterogeneous Vehicle Routing Problem (HVRP) to minimize the cost that needs to conduct efficiently the snow removal operations of Air Wing under available resources and limited operations time. For this HVRP, we model the algorithm of an hybrid Ant Colony System (ACS). In the initial step for finding a solution, the modeled algorithm applies various alterations of a parameter that presents an amount of pheromone coming out from ants. This improvement of the initial solution illustrates to affect to derive better result ultimately. The purpose of this study proves that the algorithm using Hybrid heuristic incorporated in tabu and ACS develops the early studies to search best solution.

• 대한안전경영과학회지
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• 제14권3호
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• pp.269-276
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• 2012

플라스틱 사출 제품은 다양한 가전제품과 하이테크 제품에 널리 사용되고 있다. 그러나 현재의 치열한 경쟁적 비즈니스 환경에서 플라스틱 사출 제품 제조업자들은 고객을 만족시키면서 경쟁력을 얻기 위하여 다른 경쟁자들보다 먼저 새로운 제품을 시장에 출시하고 신제품의 개발기간을 줄이기 위한 노력을 할 여유가 부족하다. 따라서 무한경쟁의 시장에서 살아남기 위해서는 제조업자들은 시장 마켓 점유를 빠르게 올리는 것과 동시에 제품의 가격 경쟁력을 가져야 한다. 특징기반 모델의 구조는 현재 연구에서 3D 제작 도구로서 일반적으로 적용되고 있으며 신제품 개발 엔지니어들이 새로운 제품의 개념을 개발하는 데에도 널리 사용되고 있다. 본 연구에서는 특징기반 플라스틱 사출제품을 위한 유전자 알고리즘과 Support Vector Regression (SVR) 기반의 새로운 하이브리드 비용 평가 모델을 제안한다. 제안하는 하이브리드 모델은 기존의 플라스틱 사출제품의 비용평가절차와 계산을 위해 필요로 하는 변수들을 극적으로 간단하게 하고 줄일 수 있다. 사례연구에서는 제안하는 하이브리드 모델과 기존의 multilayer perceptron networks (MLP) 및 pure SVR과의 비교분석을 통하여 제안모델이 플라스틱 사출 제품의 개발단계에서의 비용평가문제를 해결하는데 효율성과 효과성이 있음을 입증한다.

• 한국전자거래학회지
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• 제3권1호
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• pp.23-41
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• 1998

In a centralized database system, all system components reside at a single platform. In recent years there has been a rapid trend toward the integration of information systems over multiple sites that are interconnected via a communication network, and users' needs are changed to integration of multiple information sites. Multi database System is one of solutions for integrating distributed heterogeneous databases. However the problems in multi database system are restriction in distributed environment support, limitation in integrating heterogeneous media type data, static integration, and data-only of integration. In order to solve these problems, we propose a hybrid database integration model, HyDIM. HyDIM is used for the integrating legacy multimedia data, adopting CORBA, MDS, and mediator. We demonstrate a prototype system far PDM application domain.

• ETRI Journal
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• 제43권2호
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• pp.357-370
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• 2021

The evolution of blockchain-based systems has enabled researchers to develop nextgeneration e-voting systems. However, the classical consensus method of blockchain, that is, Proof-of-Work, as implemented in Bitcoin, has a significant impact on energy consumption and compromises the scalability, efficiency, and latency of the system. In this paper, we propose a hybrid consensus model (PSC-Bchain) composed of Proof of Credibility and Proof of Stake that work mutually to address the aforementioned problems to secure e-voting systems. Smart contracts are used to provide a trustworthy public bulletin board and a secure computing environment to ensure the accuracy of the ballot outcome. We combine a sharding mechanism with the PSC-Bchain hybrid approach to emphasize security, thus enhancing the scalability and performance of the blockchain-based e-voting system. Furthermore, we compare and discuss the execution of attacks on the classical blockchain and our proposed hybrid blockchain, and analyze the security. Our experiments yielded new observations on the overall security, performance, and scalability of blockchain-based e-voting systems.

• 대한안전경영과학회지
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• 제25권2호
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• pp.1-8
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• 2023

This paper is proposing a novel machine scheduling model for the unrelated parallel machine scheduling problem without setup times to minimize the total completion time, also known as "makespan". This problem is a NP-complete problem, and to date, most approaches for real-life situations are based on the operator's experience or simple heuristics. The new model based on the Memetic Algorithm, which was proposed by P. Moscato in 1989, is a hybrid algorithm that includes genetic algorithm and local search optimization. The new model is tested on randomly generated datasets, and is compared to optimal solution, and four scheduling models; three rule-based heuristic algorithms, and a genetic algorithm based scheduling model from literature; the test results show that the new model performed better than scheduling models from literature.

• 농촌계획
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• 제11권4호
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• pp.59-65
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• 2005

Proper management of small rural watershed is important since it does affect water quality improvement of larger scale watershed. Therefore, effective small watershed management guideline including participatory program of local people is required to achieve water environment improvement. Feasibility of water quality goal, short and long-term watershed management plan and funding sources were investigated by field monitoring of Hampyungchun watershed which has characteristics of rural stream, and literature review. The relevant parties and their roles fer watershed management were identified and suggested. A hybrid model, that is mixture of government driven model and NGO model, is recommended for watershed management organization in this study.

• 대한안전경영과학회지
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• 제9권6호
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• pp.205-214
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• 2007

Nowadays the customer is classified with external customers and the inside customers. Which are not only end users who consume products but also all people who contribute to their earnings through the management activity of the enterprise. Furthermore, the fact that the external customer satisfaction index and inside customer satisfaction index are closely related is supported by many researches. It is interpreted if the inside customer satisfaction is not improved, achievement of the external customer satisfaction cannot be easy. In this paper, First, we will deduce the inefficient index through DEA model in each department after setting up the weight of items of inside customer satisfaction and measuring them. Second, as well as research entire models about improvement methods of inside customer satisfaction getting improvement methods for reaching a goal in the minimum amount of efforts.