• 한국건설관리학회논문집
• /
• 제10권3호
• /
• pp.139-147
• /
• 2009

Accurate construction cost estimation in the initial stage of building project plays a key role for project success and for mitigation of disputes. Total construction cost(TCC) estimation of apartment projects in Vietnam has become more important because those projects increasingly rise in quantity with the urbanization and population growth. This paper presents the application of artificial neural networks(ANNs) in estimating TCC of apartment projects. Ninety-one questionnaires were collected to identify input variables. Fourteen data sets of completed apartment projects were obtained and processed for training and generalizing the neural network(NN). MATLAB software was used to train the NN. A program was constructed using Visual C++ in order to apply the neural network to realistic projects. The results suggest that this model is reasonable in predicting TCCs for apartment projects and reinforce the reliability of using neural networks to cost models. Although the proposed model is not validated in a rigorous way, the ANN-based model may be useful for both practitioners and researchers. It facilitates systematic predictions in early phases of construction projects. Practitioners are more proactive in estimating construction costs and making consistent decisions in initial phases of apartment projects. Researchers should benefit from exploring insights into its implementation in the real world. The findings are useful not only to researchers and practitioners in the Vietnam Construction Industry(VCI) but also to participants in other developing countries in South East Asia. Since Korea has emerged as the first largest foreign investor in Vietnam, the results of this study may be also useful to participants in Korea.

• 한국산림과학회지
• /
• 제88권3호
• /
• pp.400-407
• /
• 1999

본 연구에서는 가치평가를 위한 설문내용은 일치하지만 상이한 질문형에 따라 평가된 휴양가치의 차이가 나타나는 지를 밝히는 데 목적을 두였다. 자료 수집을 위해 속리산 국립공원 방문객을 대상으로 폐쇄형인 양분선택 방식과 개방형인 직접지불 방식, 두 가지 질문형에 대해 동일한 피설문자에게 설문조사를 실시하였다. 이 때 얻고자 하는 방문객의 휴양가치는 동등변이에 기초한 최대지불의사액이었다. 분석에서 사용된 독립변수는 여행비용과 월 개인소득이다. 가치평가를 위한 기본모형은 단순선형을 가정하였으며 폐쇄형은 프로빗, 개방형은 토빗모형에 근거한 이변량정규분포모형을 사용하였다. 분석 결과, 응답자가 동일한 경우에 산출된 지불의사액은 질문형에 따라 차이가 없는 것으로 나타났으며 성인 방문객 1인의 5년간 속리산 국립공원에 대한 휴양가치는 25,556원으로 산출되었다.

• 대한교통학회지
• /
• 제32권4호
• /
• pp.401-409
• /
• 2014

본 연구는 시설 확장비용과 승객들의 지체시간 감소에 따른 편익을 고려한 항공의 핵심 시설 확장 문제를 다루고자 한다. 이를 위해 우리는 시계열 예측방법으로 널리 알려진 ARIMA model를 활용하여 계절 및 주기를 갖는 항공피크 수요를 예측한다. 승객이 공항에 도착한 후에 공항 내에서의 승객들의 흐름과 지체를 고려하여 실제 지체 편익을 추정하기 위해 이산사건 시뮬레이션 모형을 설계한다. 비용과 편익 간의 상충관계를 통해 우리는 컨베이어의 경제적 확장 대수를 결정한다. 인천공항의 사례를 활용한 실험이 수행되었으며, 실험 결과는 본 접근방법이 계절에 따른 승객의 도착 유형과 공항 내의 동적인 흐름을 반영한 시설의 확장 문제를 해결하는 데 효과적임을 보인다.

• 한국정보기술학회논문지
• /
• 제17권7호
• /
• pp.123-131
• /
• 2019

본 논문에서는 기존의 관련 연구를 SW 중심의 대가 산정, 비용-편익분석, 보안성 지속서비스 대가 산정으로 구분하여 조사하였고, 사례 분석은 미국과 일본, 국내 A기관을 대상으로 하였다. 이를 바탕으로 현 제도와의 비교를 통해 개선모델을 마련하였다. 비용-효용분석 측면에서 효용성이 높은 서비스 수준 협약(SLA ; Service Level Agreement)과 NIST Cybersecurity Framework를 적용하여 정보보호서비스별 특성과 수행기준, 가중치를 기준으로 대가를 산정하는 방식인 SCS(Security Continuity Service) 성과평가체계 기반 정보보호서비스 대가 산정 모델을 제안한다. 이 모델은 공공기관에서 정보보호서비스 대가를 객관적으로 산정하는 도구로 활용할 수 있다. 또한, 현재 권고수준인 법률을 적용 강제성 수준으로 강화, 국가기관 및 공공기관의 평가제도 개선, 국가인증기관의 정보보호서비스 검증제도 도입, 모든 정보시스템 및 서비스로의 확대 등을 통해 본 제도의 정착될 수 있을 것으로 기대된다.

• Management Science and Financial Engineering
• /
• 제10권1호
• /
• pp.25-41
• /
• 2004

There have been many studies to build a model that can help investors construct optimal portfolio. Most of the previous models, however, are based upon the path-breaking Markowitz model (1959) which is a quantitative model. One of the most important problems with that kind of quantitative model is that, in reality, most of the investors use not only quantitative, but also qualitative information when they select their optimal portfolio. Since collecting both types of information from the markets are time consuming and expensive, making a set of target assets smaller, without suffering heavy loss in the rate of return, would attract investors. To extract only desired assets among all available assets, we need knowledge that identifies investors' preference for the risk of the assets. This study suggests two-layer decision-making rules capable of identifying an investor's risk preference and an architecture applying them to a quantitative portfolio model based on risk and expected return. Our knowledge-based portfolio system is to build an investor's preference-oriented portfolio. The empirical tests using the data from Korean capital markets show the results that our model contributes significantly to the construction of a better portfolio in the perspective of an investor's benefit/cost ratio than that produced by the existing portfolio models.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권5호
• /
• pp.1790-1806
• /
• 2015

Utility-based routing is a special type of routing approach using a composite utility metric when making routing decisions in ad hoc and sensor networks. Previous studies on the utility-based routing all use fixed retry limit and a very simple distance related energy model, which makes the utility maximization less efficient and the implementation separated from practice. In this paper, we refine the basic utility model by capturing the correlation of the transmit power, the retry limit, the link reliability and the energy cost. A routing algorithm based on the refined utility model with adaptive transmit power and retry limit allocation is proposed. With this algorithm, packets with different priorities will automatically receive utility-optimal delivery. The design of this algorithm is based on the observation that for a given benefit, there exists a utility-maximum route with optimal transmit power and retry limit allocated to intermediate forwarding nodes. Delivery along the utility-optimal route makes a good balance between the energy cost and the reliability according to the value of the packets. Both centralized algorithm and distributed implementations are discussed. Simulations prove the satisfying performance of the proposed algorithm.

• Management Science and Financial Engineering
• /
• 제16권3호
• /
• pp.21-47
• /
• 2010

Quantity discounts provide a practical foundation for supply chain inventory policies, improving the supplier's profit and reducing the buyer's inventory cost simultaneously. Traditional quantity-discount research, which deals with inventory coordination between a buyer and a supplier, is extended to a stationary stochastic environment. This research shows that the magnitude of the optimal discounts scheduled by the deterministic quantity discount models may not be large enough to cover the buyer's additional inventory stocking risks under uncertain conditions. As a result, the buyer's total inventory cost may often increase rather than decrease. In contrast, the proposed model allows the supplier to identify the discount level, which shares the buyer's amplified risk associated with temporary overstocking and ensures that both buyer and supplier benefit economically. The performance of the proposed model was tested in the continuous review environments via numerical experiments. The experimental results support the proposed method as a feasible alternative in coordinating inventory decisions under stochastic demand.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권10호
• /
• pp.4157-4175
• /
• 2020

Moving target defense, as a 'game-changing' security technique for network warfare, realizes proactive defense by increasing network dynamics, uncertainty and redundancy. How to select the best countermeasure from the candidate countermeasures to maximize defense payoff becomes one of the core issues. In order to improve the dynamic analysis for existing decision-making, a novel approach of selecting the optimal countermeasure using game theory is proposed. Based on the signal game theory, a multi-stage adversary model for dynamic defense is established. Afterwards, the payoffs of candidate attack-defense strategies are quantified from the viewpoint of attack surface transfer. Then the perfect Bayesian equilibrium is calculated. The inference of attacker type is presented through signal reception and recognition. Finally the countermeasure for selecting optimal defense strategy is designed on the tradeoff between defense cost and benefit for dynamic network. A case study of attack-defense confrontation in small-scale LAN shows that the proposed approach is correct and efficient.

• KEPCO Journal on Electric Power and Energy
• /
• 제1권1호
• /
• pp.67-71
• /
• 2015

The concept known as Vehicle-to-Grid (V2G) is to provide power to help balance loads by charging at night when demand is low and sending power to the grid when demand is high. Therefore, it is important to model the cost-benefit characteristics of Electric vehicle(EV)'s operation considering the negawatt market in real time. This paper proposes a methodology to formulate the various costs and economic benefits for sending the EV's power back to the grid, including a concept of inconvenience costs caused by operating the EV as a battery. This paper also introduces the general decision-making process based on the cost-benefit analysis in order to simulate the reasonable participation of V2G service. In the case study, it is confirmed by two-case simulations that the proposed approach is useful to help EV owners' decision-making. In the future, it is expected that the proposed methodology can be used as a decision-making guideline to help prepare the EV' power transmission.

• 대한임상독성학회지
• /
• 제19권1호
• /
• pp.1-7
• /
• 2021

Purpose: The purpose of this study was to conduct a systematic review to investigate the socio-economic benefits of the poison control center (PCC) and to assess whether telephone counseling at the poison control center affects the frequency of emergency room visits, hospitalization, and length of stay of patients with acute poisoning. Methods: The authors conducted a medical literature search of the PubMed, EMBASE, and Cochrane Library databases. Two reviewers evaluated the abstracts for eligibility, extracted the data, and assessed the study quality using a standardized tool. Key results such as the cost-benefit ratio, hospital stay days, unnecessary emergency room visits or hospitalizations, and reduced hospital charges were extracted from the studies. When meta-analysis was possible, it was performed using RevMan software (RevMan version 5.4). Results: Among 299 non-duplicated studies, 19 were relevant to the study questions. The cost-benefit ratios of PCC showed a wide range from 0.76 to 36 (average 6.8) according to the level of the medical expense of each country and whether the study included intentional poisoning. PCC reduced unnecessary visits to healthcare facilities. PCC consultation shortened the length of hospital stay by 1.82 (95% CI, 1.07-2.57) days. Conclusion: The systematic review and meta-analysis support the hypothesis that the PCC operation is cost-beneficial. However, when implementing the PCC concept in Korea in the future, it is necessary to prepare an institutional framework to ensure a costeffective model.