• International conference on construction engineering and project management
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• 2013.01a
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• pp.502-506
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• 2013

The cash flow forecasting is normally done by contractors in construction industry at early stages of the project for contractual decisions. The decision making in such situations involve uncertainty about future cash flows and assessment of working capital requirements gains more importance in projects constrained by cash. The traditional approach to assess the working capital requirements is deterministic in and neglects the uncertainty. This paper presents an alternate approach to assessment of working capital requirements for contractor based on fuzzy set theory by considering the uncertainty and ambiguity involved at payment periods. Statistical methods are used to deal with the uncertainty for working capital curves. Membership functions of the fuzzy sets are developed based on these statistical measures. Advantage of fuzzy peak working capital requirements is demonstrated using peak working capital requirements curves. Fuzzy peak working capital requirements curves are compared with deterministic curves and the results are analyzed. Fuzzy weighted average methodology is proposed for the assessment of peak working capital requirements.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.16 no.1
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• pp.72-80
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• 2016

Re-auction happens when a bid winner defaults on the payment without making second in-line purchase declaration even after determining sales permission. This is a process of selling under the court's authority. Re-auctioning contract price of real estate is largely influenced by the real estate business, real estate value, and the number of bidders. This paper is designed to establish a statistical model that deals with the number of bidders participating especially in apartment re-auctioning. For these, diverse factors are taken into consideration, including ratio of minimum sales value from the point of selling to re-auctioning, number of bidders at the time of selling, investment value of the real estate, and so forth. As an attempt to consider ambiguous and vague factors, this paper presents a comparatively vague concept of real estate and bidders as trapezoid fuzzy number. Two different methods based on the least squares estimation are applied to fuzzy regression model in this paper. The first method is the estimating method applying substitution after obtaining the estimators of regression coefficients, and the other method is to estimate directly from the estimating procedure without substitution. These methods are provided in application for re-auction data, and appropriate performance measure is also provided to compare the accuracies.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2240-2250
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• 2016

MIFARE Classic is the most popular contactless smart card, which is primarily used in the management of access control and public transport payment systems. It has several security features such as the proprietary stream cipher Crypto 1, a challenge-response mutual authentication protocol, and a random number generator. Unfortunately, multiple studies have reported structural flaws in its security features. Furthermore, various attack methods that target genuine MIFARE Classic cards or readers have been proposed to crack the card. From a practical perspective, these attacks can be partitioned according to the attacker's ability. However, this measure is insufficient to determine the optimal attack flow due to the refined random number generator. Most card-only attack methods assume a predicted or fixed random number, whereas several commercial cards use unpredictable and unfixable random numbers. In this paper, we propose optimal MIFARE Classic attack procedures with regards to the type of random number generator, as well as an adversary's ability. In addition, we show actual attack results from our portable experimental setup, which is comprised of a commercially developed attack device, a smartphone, and our own application retrieving secret data and sector key.

• Environmental and Resource Economics Review
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• v.20 no.3
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• pp.595-628
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• 2011

This study investigates the issues and suggests reform measures in applying CV methods to the Korea Development Institute's (KDI's) Preliminary Feasibility Test (PFT) of public projects. Most public projects on culture, science and environment evaluated under the PFT system belong to the category of "nonstandard" projects whose outputs are non-marketed, and CV is currently the main tool used for their benefit estimation. A careful discussion and investigation is recommended for the selection of target population, payment vehicle, and number of payment times. Operating expert reviews, focus group interviews, and pre-tests is highly recommended to reduce the potential bias involved in the CV studies. A single or double bounded dichotomous choice format is the most popular design of questionnaire, but we identify several undissolved issues in designing and implementing the format. Some other forms of inducing WTPs may still deserve our consideration. Various specifications of the WTP function need to be tried and tested based on their stability, in particular. Employing a nonparametric approach is also recommended. Treatments of 0 or negative WTPs and protest bids are shown to be the most serious issues that affect the estimation results significantly. We review diverse measures of handling those issues and summarize their advantages and shortcomings.

• Journal of Digital Convergence
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• v.11 no.10
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• pp.217-224
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• 2013

Due to the development of mobile technologies, the carrier (telecommunications) billing service market is rapidly growing. carrier (telecommunications) billing service allows users to make on-line purchases through mobile-billing. Users find this particularly convenient because the payment acts as a credit transaction. Furthermore, the system is commonly believed to be secure through its use of SMS (Short Message Service) authentication and a real-time transaction history to confirm the transaction. Unfortunately, there is a growing number of fraudulent transactions threaten the future of this system. The more well documented types of security breaches involves hackers intercepting the authentication process. By contaminating the device with security breaching applications, hackers can secretly make transactions without notifying users until the end of month phone bill. This study sheds light on the importance of this societal threat and suggests solutions. In particular, "secure" systems need to be more proactive in addressing the methods hackers use to make fraudulent transactions. Our research partially covers specific methods to prevent fraudulent transactions on carrier billing service providers' systems. We discuss about the proposed improvements such as complement of electronic payment systems, active promotion for fraudulent transactions enhanced monitoring, fraud detection and introduce a new authentication service. This research supports a future of secure communications billing services, which is essential to expanding new markets.

• Journal of the Korea Institute of Building Construction
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• v.11 no.2
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• pp.108-115
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• 2011

This study investigates the construction management selection methods for fair competition within the construction management market by analyzing the current status of domestic construction management, the 2010 publication on the status of construction management, and the construction management evaluation criteria. Also, the 2009 publication of top CM service establishments, the average proportion of tender for 120 CM services from 2002 to 2010, and six assessment results which are open to the parties directly involved were statistically analyzed to review the adequacy of the evaluation criteria. This analysis shows that the evaluation criteria for the CM service impedes the development of the construction management industry and companies, since the criteria are decided by the service payment, and the technical skills assessed by technical proposals have no ties with contract prices. Therefore, this study proposes an improvement of the selection methods in accordance with the project characteristics and the technical requirements. However, more research is still needed to derive a detailed classification method of the technical requirement, the owner's evaluation criteria selection, and the preparation of an institutional foundation for the construction manager's post-evaluation.

• Asia pacific journal of information systems
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• v.24 no.2
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• pp.211-232
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• 2014

Recently, there is a growing interest toward social commerce using SNS(Social Networking Service), and the size of its market is also expanding due to popularization of smart phones, tablet PCs and other smart devices. Accordingly, various studies have been attempted but it is shown that most of the previous studies have been conducted from perspectives of the users. The purpose of this study is to derive user-centered CSF(Critical Success Factor) of social commerce from the previous studies and analyze the CSF perception gap between social commerce service providers and users. The CSF perception gap between two groups shows that there is a difference between ideal images the service providers hope for and the actual image the service users have on social commerce companies. This study provides effective improvement directions for social commerce companies by presenting current business problems and its solution plans. For this, This study selected Korea's representative social commerce business Ticket Monster, which is dominant in sales and staff size together with its excellent funding power through M&A by stock exchange with the US social commerce business Living Social with Amazon.com as a shareholder in August, 2011, as a target group of social commerce service provider. we have gathered questionnaires from both service providers and the users from October 22, 2012 until October 31, 2012 to conduct an empirical analysis. We surveyed 160 service providers of Ticket Monster We also surveyed 160 social commerce users who have experienced in using Ticket Monster service. Out of 320 surveys, 20 questionaries which were unfit or undependable were discarded. Consequently the remaining 300(service provider 150, user 150)were used for this empirical study. The statistics were analyzed using SPSS 12.0. Implications of the empirical analysis result of this study are as follows: First of all, There are order differences in the importance of social commerce CSF between two groups. While service providers regard Price Economic as the most important CSF influencing purchasing intention, the users regard 'Trust' as the most important CSF influencing purchasing intention. This means that the service providers have to utilize the unique strong point of social commerce which make the customers be trusted rathe than just focusing on selling product at a discounted price. It means that service Providers need to enhance effective communication skills by using SNS and play a vital role as a trusted adviser who provides curation services and explains the value of products through information filtering. Also, they need to pay attention to preventing consumer damages from deceptive and false advertising. service providers have to create the detailed reward system in case of a consumer damages caused by above problems. It can make strong ties with customers. Second, both service providers and users tend to consider that social commerce CSF influencing purchasing intention are Price Economic, Utility, Trust, and Word of Mouth Effect. Accordingly, it can be learned that users are expecting the benefit from the aspect of prices and economy when using social commerce, and service providers should be able to suggest the individualized discount benefit through diverse methods using social network service. Looking into it from the aspect of usefulness, service providers are required to get users to be cognizant of time-saving, efficiency, and convenience when they are using social commerce. Therefore, it is necessary to increase the usefulness of social commerce through the introduction of a new management strategy, such as intensification of search engine of the Website, facilitation in payment through shopping basket, and package distribution. Trust, as mentioned before, is the most important variable in consumers' mind, so it should definitely be managed for sustainable management. If the trust in social commerce should fall due to consumers' damage case due to false and puffery advertising forgeries, it could have a negative influence on the image of the social commerce industry in general. Instead of advertising with famous celebrities and using a bombastic amount of money on marketing expenses, the social commerce industry should be able to use the word of mouth effect between users by making use of the social network service, the major marketing method of initial social commerce. The word of mouth effect occurring from consumers' spontaneous self-marketer's duty performance can bring not only reduction effect in advertising cost to a service provider but it can also prepare the basis of discounted price suggestion to consumers; in this context, the word of mouth effect should be managed as the CSF of social commerce. Third, Trade safety was not derived as one of the CSF. Recently, with e-commerce like social commerce and Internet shopping increasing in a variety of methods, the importance of trade safety on the Internet also increases, but in this study result, trade safety wasn't evaluated as CSF of social commerce by both groups. This study judges that it's because both service provider groups and user group are perceiving that there is a reliable PG(Payment Gateway) which acts for e-payment of Internet transaction. Accordingly, it is understood that both two groups feel that social commerce can have a corporate identity by website and differentiation in products and services in sales, but don't feel a big difference by business in case of e-payment system. In other words, trade safety should be perceived as natural, basic universal service. Fourth, it's necessary that service providers should intensify the communication with users by making use of social network service which is the major marketing method of social commerce and should be able to use the word of mouth effect between users. The word of mouth effect occurring from consumers' spontaneous self- marketer's duty performance can bring not only reduction effect in advertising cost to a service provider but it can also prepare the basis of discounted price suggestion to consumers. in this context, it is judged that the word of mouth effect should be managed as CSF of social commerce. In this paper, the characteristics of social commerce are limited as five independent variables, however, if an additional study is proceeded with more various independent variables, more in-depth study results will be derived. In addition, this research targets social commerce service providers and the users, however, in the consideration of the fact that social commerce is a two-sided market, drawing CSF through an analysis of perception gap between social commerce service providers and its advertisement clients would be worth to be dealt with in a follow-up study.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.4
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• pp.529-540
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• 1999

The purpose of this study is examine how price attitude and risk perception affect6 consumer's attitude to clothing discount stores. As for the methods of the research 313 female consumers who just finished shopping at discount stores were interviewed and questioned. The result is as the following. 1. The factors such as discount price inclination effective value inclination price-quality association and price-social grade association in the price attitude as well as social psychological risk and the risk of losing opportunity in the risk perception affected consumer's attitude to clothing discount store. 2. The domestic national brand discount store acquired the highest scores in all factors but discount inclination factor and low price inclination factor. No difference was seen between stores in terms of the risk perception. 3. The determining factors for repurchase intention were found to be store satisfaction and the attitude to clothing discount store. 4. The convenience of transportation the availability of exchange or repair the payment option the quality of the product and the attributes of the store e, g, good quality with relatively low price affected the store satisfaction. 5. Domestic national brand discount store showed higher score in 'good quality with relatively low price' than domestic casual brand discount store did. And difference between groups was found in repurchase intention, Conclusively most consumers using clothing discount stores are effective value-oriented.

• Journal of the Korea Fashion and Costume Design Association
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• v.15 no.3
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• pp.51-67
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• 2013

This study aims to examine impacts of the Internet shopping orientation of Korean and Chinese consumers on their selection criteria of shopping malls and apparel products, frequencies and amounts of purchase, and information search in the Internet shopping mall. A survey was carried out with Korean and Chinese female consumers in their 20s and 30s who have the Internet shopping experiences. The results of this study were as follows: First, the Internet shopping orientation of Korean and Chinese respondents clearly showed factorial structures including the pleasure-conscious, fashion-conscious, price-conscious, and convenience-conscious orientation. From a result of the cluster analysis on four factors of the Internet shopping orientation, Korean and Chinese respondents were classified into three groups of the Internet shopping-unconscious, the Internet shopping-loyalty, and pleasure convenience-conscious. Second, there were significant differences in selection criteria of both the Internet shopping mall and apparel products among three groups of the Internet shopping orientation in Korea and China. Third, significant differences were identified in visiting frequencies, apparel purchase frequencies and amounts, payment methods, and information sources during the Internet shopping among three groups of the Internet shopping orientation in Korea and China.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.52
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• pp.25-44
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• 2011

Possibility of credit risk, foreign exchange risk and interest rate risk of exporter increases in the recent international Commercial transactions, due to financial crisis of Europe and liberalization of Middle East. Under this circumstance, Forfaiting is trade finance that forfaiter purchase negotiable debt instrument without recourse from exporter, which occurred related with international commercial transactions, and credit risk, contingency risk, foreign exchange risk and interest rate risk of exporter can be transferred to forfaiter. Forfaiting is typically medium-term finance(three to five years) concluded at fixed interest rate, although it can also arranged on a floating interest-bearing basis for periods from six months to ten years or more. But Forfaiting service of Korea has limitation as follows. First, forfaiting in Korea deals with unrestricted irrevocable documentary credit as debt instruments. Period that forfaiting is provided is short and amount of money is limited, compared with advanced forfaiting. But forfaiting provided in advanced countries deals with various methods such as guarantee for bill, payment guarantee, and can be resold in financial market. Recently importance of forfaiting is increasing in international commercial transactions. Therefore profound study on forfaiting is required. The study will examine the risk that happens to the concerned parties in forfaiting, and its management measures. The study adopted literature review method such as local and foreign books and papers about trade finance, internet information about forfaiting, and professional journal related with international finance.