• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.283-285
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• 2002

조합 경매는 구매자들이 원하는 상품들을 조합해서 입찰할 수 있는 경매다. 그러나 판매자의 이익을 최대로 하는 승자를 결정하는 문제는 NP-complete이다. 분기 한정법(branch and bound)을 사용해서 최적의 승자를 찾을 때, 어떤 비드(bid)를 선택해서 분기할 것인가를 결정해야 한다. 이 때, 비드를 선택하는 휴리스틱이 분기 한정법의 성능을 결정하는 중요한 역할을 한다. 본 논문에서는 조합경매의 승자를 결정하기 위해서 분기 한정법과 Linear Programming을 사용할 때, 분기할 비드와 충돌하는 비드들을 동시에 고려하는 비드 선택 휴리스틱을 제안한다. 실험을 통해서 제시하는 휴리스틱의 성능이 우수함을 보였다.

• Management Science and Financial Engineering
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• v.18 no.2
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• pp.1-4
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• 2012

We study optimal trading strategy of a market maker with stock inventory. Following Avellaneda and Stoikov (2008), we assume the stock price follows a normal distribution. However, we take a constant expected rate of the stock return and assume that the stock volatility is an inverse function of the stock price level. We show that the optimal bid-ask spread of the market maker is wider for a higher expected rate of stock returns.

• Asia Marketing Journal
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• v.16 no.3
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• pp.23-33
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• 2014

The selection of keywords for bidding is a critical component of paid search advertising. When the number of possible keywords is enormous, it becomes difficult to choose the best keywords for advertising and then subsequently to assess their effect. To this end, we propose an ultrahigh dimensional keyword selection approach that not only reduces the dimension for selections, but also generates the top listed keywords for profits. An empirical analysis using a unique panel dataset from a large online clothes retailer that advertises on the largest search engine in China (i.e., Baidu) is presented to illustrate the usefulness of our approach.

• Proceedings of the Korean Association for Survey Research Conference
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• 2001.04a
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• pp.83-107
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• 2001

The contingent valuation method used survey questions to elicit people's preferences for public goods by finding out what they would be willing to pay for specified improvement in them. The method is thus aimed at eliciting their willingness to pay in money amounts. It circumvents the absence of markets for public goods by presenting consumers with hypothetical markets in which they have the opportunities to buy the good in question. The hypothetical markets may be modeled after either a private goods market or a political market. Respondents are presented with material, often in the course of a personal interview conducted face to face. An on-site survey was conducted to 1107 randomly selected P-mountain users using a dichotomous choice questionnaire for the contingent valuation method. Seventeen different bid sets were chosen ranging from the lowest bid of 300won to the highest bid of 2,100won to elicit a reasonable entrance fee in the suggested bid had been determined, and the expected value of willingness to pay was estimated using binary-logit model. The average public value of P-mountain per individual user was estimated to be 1,055.92won∼1,995.61won according to the binary-logit model. The economic value of this P-mountain which includes both use value and existence value can be determined by aggregating the average value giving total willingness to pay for the entire population, in this case 5.491 billion ∼ 10.377 billion.

• Survey Research
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• v.2 no.2
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• pp.83-107
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• 2001

The contingent valuation method uses survey questions to elicit people's preferences for public goods by finding out what they would be willing to pay for specified improvement in them. The method is thus aimed at eliciting their willingness to pay in money amounts. It circumvents the absence of markets for public goods by presenting consumers with hypothetical markets in which they have the opportunities to buy the good In question. The hypothetical markets may be modeled after either a private goods market or a political market. Respondents are presented with material, often in the course of a personal interview conducted face to face. An on-site survey was conducted to 1107 randomly selected P-mountain users using a dichotomous choice questionnaire for the contingent valuation method. Seventeen different bid sets were chosen ranging from the lowest bid of 300won to the highest bid of 2, 100won to elicit a reasonable entrance fee in the hypothetical market. The probability of an individual user's willingness to pay for the suggested bid had been determined, and the expected value of willingness to pay was estimated using binary-1ogit model. The average public value of P-mountain per individual user was estimated to be 1,055.92won ~ 1,995.61won according to the binary-logit model. The economic value of this P-mountain which includes both use value and existence value can be determined by aggregating the average value giving total willingness to pay for the entire population, in this case 5.491 billion ~ 10.377 billion.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3289-3294
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• 2016

Naringin, a bioflavonoid found in Citrus seeds, inhibits proliferation of cancer cells. The objectives of this study were to investigate the mode and mechanism(s) of hepatocellular carcinoma HepG2 cell death induced by naringin. The cytotoxicity of naringin towards HepG2 cells proved dose-dependent, measured by MTT assay. Naringin-treated HepG2 cells underwent apoptosis also in a concentration related manner, determined by annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) employing flow cytometry. Mitochondrial transmembrane potential (MTP) measured using 3,3'-dihexyloxacarbocyanine iodide ($DiOC_6$) and flow cytometer was reduced concentration-dependently, which indicated influence on the mitochondrial signaling pathway. Caspase-3, -8 and -9 activities were enhanced as evidenced by colorimetric detection of para-nitroaniline tagged with a substrate for each caspase. Thus, the extrinsic and intrinsic pathways were linked in human naringin-treated HepG2 cell apoptosis. The expression levels of pro-apoptotic Bax and Bak proteins were increased whereas that of the anti-apoptotic Bcl-xL protein was decreased, confirming the involvement of the mitochondrial pathway by immunoblotting. There was an increased expression of truncated Bid (tBid), which indicated caspase-8 proteolysis activity in Bid cleavage as its substrate in the extrinsic pathway. In conclusion, naringin induces human hepatocellular carcinoma HepG2 cell apoptosis via mitochondria-mediated activation of caspase-9 and caspase-8-mediated proteolysis of Bid. Naringin anticancer activity warrants further investigation for application in medical treatment.

• Land and Housing Review
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• v.10 no.4
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• pp.13-30
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• 2019

Parking lot within housing site contains public interest of relieving parking space shortage problem and subject to public restriction. If auctioned off at higher price by excessive competition in general competitive bid for land bidders, the development of parking lot will be made against its original purpose supply. The core issue is that a bid price is quite often to be blown out of proportion by 150%~ 250% due to extreme competition and, could face serious problem if a winning bidder runs sale business. If it is rental business, although about 30% of the total floor space of the whole building to be used as neighborhood facilities, too high winning bid price cause to lose transparency. In case of sale at aggregate buildings, most business operators would sell 30% of the neighborhood facilities, spare the parking lot and manages thereof separately. According to Aggregate Buildings Act, neighborhood facilities are allowed for individual registration and ownership of parking lot by business operator or designated person by business operator. In this case, the parking lot becomes 70% of the total floor space of the whole building and 70% of the land share which makes the mortgage very valuable and easier for business operator to get financial loan. There used to be many cases such as owners of neighborhood facilities (aggregate buildings partial owners) who run parking lot to repay their loan running parking lot to repay loan, but found that very tough and reached auction and relatively disadvantaged. For parking lot within housing site, it is recommend to exclude the public factors that land has and take into account of public restriction in area (housing site). Business opportunity for operators and protection of property rights for buyers in aggregate buildings, land supply method is recommended to replace from highest bid method into draw or private contract. In terms of price, supply at estimated price (construction price) and restriction on usage (Co-ownership of parking lot) proposals are submitted.

• Korean Journal of Construction Engineering and Management
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• v.7 no.5
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• pp.167-176
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• 2006

It was found that Korean Standard of Estimate which has been used as the only basis of cost estimate of public construction projects had some side effects such as jerry-build construction and over-estimation because it failed to reflect the current price and the state-of-the-art construction methods in a changing construction environment. Therefore, the government decided to gradually introduce historical construction cost into cost estimate of public construction projects from 2004. This paper presents analytic criteria and a process model for deducing more current and reasonable historical construction cost for contract items from not only previous contract prices but also all of the other bid prices that were not contracted. The procedure of estimating actual unit cost proposed in this paper focuses on the removal of abnormal values including strategically too low or high prices and the time correction. In addition, basic research is conducted for the correction of actual unit cost through the analysis of fluctuation of bid price depending on bidding types and rates of successful bid. It is anticipated that the effective use of the proposed process model for estimating actual unit cost would make the cost estimation more current and reasonable.

• Journal of the Korea Society for Simulation
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• v.29 no.4
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• pp.65-72
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• 2020

The purpose of this study is to analyze the adequacy of product qualification criteria through Monte-Carlo simulation and association rule analysis. We first surveyed the similar procurement systems, then we simulated the bid situation that randomly generated several vendors participated in a bid, and they obtained the score according to the product qualification criteria's judgement area. Then, the company with the highest score will win the bid, and further analysis was performed in terms of performance indicator and satisfaction ratio. The results of this study can be summarized as follows; Although the items related to the credibility accounted for the largest number items, it did not affect the actual bid results. It was analyzed that it is desirable to increase the allocation points in the area of business status and technical capability review than the current one.

• Journal of the Korea Society for Simulation
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• v.18 no.1
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• pp.41-51
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• 2009

A discrete event simulation model is developed to evaluate the performances of three different revenue management methods for an air cargo network from Northeast China to North America and Europe. In the first method, a bid price model is applied only to the routes that pass through Incheon. In the second method, the bid price model is applied to all the routes. In third method, bid price and virtual nesting models are applied to the routes that pass through Incheon. The results show that the total revenue significantly increases with the employment of pricing and capacity control. The developed simulation model is a useful research tool to study marketing strategies for air cargo operations.