• International conference on construction engineering and project management
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• 2022.06a
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• pp.11-17
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• 2022

Design-bid-build (DBB) is the most common project delivery method among highway projects. State Highway Agencies (SHAs) usually apply a low-bid approach to select contractors for their DBB projects. In this approach, the Federal Highway Agency suggests SHAs heighten contractors' competition to lower bid prices. However, these attempts may become ineffective due to collusive bidding arrangements among certain contractors. One common strategy is the rotation of winning bidders of a group of contractors who bid on many of the same projects. These arrangements may also be specific to a particular region or vary in time. Despite the practices' adverse effects on bidding outcomes, an effective model to detect red-flag bidding patterns is lacking. This study fills the gap by proposing a novel framework that utilizes pattern mining techniques and statistical tests for unusual pattern detection. A case study with historical data from an SHA is conducted to illustrate the proposed framework.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.109-113
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• 2007

This paper introduces a system, Simulation based Stochastic Markup Estimation System (S2ME), for estimating optimum markup for a project. The system was designed and implemented to better represent the real world system involved in construction bidding. The findings obtained from the analysis of existing assumptions used in the previous quantitative markup estimation methods were incorporated to improve the accuracy and predictability of the S2ME. The existing methods has four categories of assumption as follows; (1) The number of competitors and who is the competitors are known, (2) A typical competitor, who is fictitious, is assumed for easy computation, (3) the ratio of bid price against cost estimate (B/C) is assumed to follow normal distribution, (4) The deterministic output obtained from the probabilistic equation of existing models is assumed to be acceptable. However, these assumptions compromise the accuracy of prediction. In practice, the bidding patterns of the bidders are randomized in competitive bidding. To complement the lack of accuracy contributed by these assumptions, bidding project was randomly selected from the pool of bidding database in the simulation experiment. The probability to win the bid in the competitive bidding was computed using the profile of the competitors appeared in the selected bidding project record. The expected profit and probability to win the bid was calculated by selecting a bidding record randomly in an iteration of the simulation experiment under the assumption that the bidding pattern retained in historical bidding DB manifest revival. The existing computation, which is handled by means of deterministic procedure, were converted into stochastic model using simulation modeling and analysis technique as follows; (1) estimating the probability distribution functions of competitors' B/C which were obtained from historical bidding DB, (2) analyzing the sensitivity against the increment of markup using normal distribution and actual probability distribution estimated by distribution fitting, (3) estimating the maximum expected profit and optimum markup range. In the case study, the best fitted probability distribution function was estimated using the historical bidding DB retaining the competitors' bidding behavior so that the reliability was improved by estimating the output obtained from simulation experiment.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.550-552
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• 2001

The vertically integrated power industry was divided into six generation companies and one market operator, where electricity trading was launched at power exchange. In this environment, the profits of each generation companies are guaranteed according to utilization of their own generation equipments. Especially, the electricity demand shows seasonal and weekly regular pattern, which the some capacity should be provided into ancillary service based on the past demand forecasting error and operating results of electricity market. Namely, if generation cost function is applied to SMP and BLMP as announced the previous day, the available generation capacity of the following day could be optimally distributed, and therefore contract capacity of ancillary service applied to CBP(Cost Based Pool) and TWBP(Two-Way Bidding Pool) is determined. Consequently, it is Possible to use the retained equipments optimally. This paper represents on efficient bidding strategies for generation equipments through the calculation of the contract and the application of each generator cost function based on the past demand forecasting error and market operating data.

• The Journal of Society for e-Business Studies
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• v.6 no.2
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• pp.87-99
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• 2001

Along with the rapid emergence of the Internet and e-commerce, online auctions are hitting the spotlights. The inconveniences found in off-line auctions, such as time and place restriction and limited number of items, are solved in the online auction. However, not so many auction sites have integrated auction information systems, which monitor the present status of auctions, resulting in greater inconvenience for the online auction users. Moreover, there is no auction site that suggests the appropriate starting or closing price that is useful for users when they make, their bids, What the online auction users need is an auction system that can solve such problems. This study is purported for solving the problems by designing and implementing a real time auction system that applies the comparison search functions and the agent functions. In other words, an integrated database system using a bidder-oriented agent for providing information is built so that the users can search and compare the information on the item they are interested in and make a faster and more accurate purchase. Also the appropriate starting and closing prices are offered to the sellers and bidders through the integrated system for a closer and more accurate comparison and analysis of the prices. For future work, the product recommendation service, which accurately reflects the bidding patterns, and the methods for studying the multi bidding pattern will be applied to the suggested system to realize a real time auction information system that supports CRM(Customer Relationship Management) .

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.569-580
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• 2008

If slope height was more than 20 meters, we conducted an analysis of stereographic projection and limit equilibrium at this slope. We proposed reduction of slope face angle and reinforcement of rock bolt depending on analysis. Blasting design : Standard pattern based on result of local test blasting was made for blasting design. Vibration criterion was set for less than 3.0mm/s because of outworn buildings and inhabitants opinions. Production blasting and Controlled blasting has been done as Construction standard pattern. After Vibration Monitoring has been done, so that we can control of complement. "Bidding Document" and AASHTO 2001 "A Policy on Geometric Design of Highways and Streets" were so for design criteria of earthwork but they were different actual design criteria and left something to be desired in Afghanistan. Therefore, although "Bidding Document" and "AASHTO 2001" were basic design criteria, domestic design criteria was reflected in this design criteria for complement by discussion with supervisor. Drainage design : For stability ratio, ditch of arch block and stonework was designed by rainfall data for the 13 years and discussion with supervisor. Pavement was designed as flexible pavement. Because these days in Afghanistan postwar repair works, especially urgent repairing of roads and newly making of roads, are very highly in progress, I think that Afghanistan is the region about which our construction technical experts should have great concerns.

• Journal of Energy Engineering
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• v.8 no.2
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• pp.265-271
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• 1999

In recent years, the electric utility industry in Korea has undergone fast change. Private power generation has been introduced by competitive bidding to improve economic efficiency and to strengthen the competitive generation market. In these private generation projects, the yearly pattern of purchase price between the utility and IPPs is very important. Currently, the levelized payment schedule is applied to capacity payment, and price escalation rates are reflected to energy payment. In this paper, we Proposed different patterns of payment and analyzed the outcomes. As a result, we found possibility of applying the partial front-loading pattern in Korean market to share the risk of the long-term business. And, the importance of discount rate is also found.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.162-164
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• 2005

This paper presents an hour-ahead System Marginal Price (SMP) forecasting framework based on a neural network. Recently, the deregulation in power industries has impacted on the power system operational problems. The bidding strategy of market participants in energy market is highly dependent on the short-term price levels. Therefore, short-term SMP forecasting is a very important issue to market participants to maximize their profits. and to market operator who may wish to operate the electricity market in a stable sense. The proposed hybrid neural network is composed of tow parts. First part of this scheme is pattern classification to input data using Kohonen Self-Organizing Map (SOM) and the second part is SMP forecasting using back-propagation neural network that has three layers. This paper compares the forecasting results using classified input data and unclassified input data. The proposed technique is trained, validated and tested with historical date of Korea Power Exchange (KPX) in 2002.

• Fashion & Textile Research Journal
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• v.5 no.5
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• pp.465-469
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• 2003

The present study revealed; that (1) The students majoring in a piano course were the preference type of the performance dress - best line was designed of upper form chest. It was 1.5cm shorter than armhole line, the princess line was preferred Top one piece without sleeves which was designed with slim by bottom line through west dart form best line. The expression method was showing embroidery and bidding, colors were in order to white, ivory, black and blue style. The material was in order to silk with glorious shinning, silk satin and race style. (2) The students majoring in a vocal music were the preference type of the performance dress - the princess line was designed shorter, the west line of back and forth was preferred the one piece of bulk style divided with three partitions. Neck line was 5cm shorter than the middle of back, 9cm shorter than the side neck position, 9cm shorter than the middle of forth, sweet heart neck line with circular sleeve designed 7cm shorter than the side neck position. Colors were in order to ivory, red and yellow style. The material was in order to silk with glorious shinning silk satin and race style.