• The KIPS Transactions:PartD
• /
• v.10D no.3
• /
• pp.407-416
• /
• 2003

As the usage of database systems dramatically increases and the amount of data pouring into them is massive, the performance administration techniques for using database systems effectively are getting more important. Especially in data warehouses, the performance management is much more significant mainly because of large volume of data and complex queries. The objectives and characteristics of data warehouses are different from those of other operational systems so adequate techniques for performance monitoring and tuning are needed. In this paper we extend functionalities of the DBMax, a performance administration tool for Oracle database systems, to apply it to data warehouse systems. First we analyze requirements based on summary management and ETL functions they are supported for data warehouse performance improvement in Oracle 9i. Then, we design architecture for extending DBMax functionalities and implement it. In specifics, we support SQL tuning by providing details of schema objects for summary management and ETL processes and statistics information. Also we provide new function that advises useful materialized views on workload extracted from DBMax log files and analyze usage of existing materialized views.

• Journal of KIISE:Databases
• /
• v.35 no.2
• /
• pp.97-111
• /
• 2008

Commercial data mining tools basically support binary attributes only in mining association rules, that is, they can mine binary association rules only. In general, however. transaction databases contain not only binary attributes but also quantitative attributes. Thus, in this paper we propose a systematic approach to mine quantitative association rules---association rules which contain quantitative attributes---using commercial mining tools. To achieve this goal, we first propose an overall working framework that mines quantitative association rules based on commercial mining tools. The proposed framework consists of two steps: 1) a pre-processing step which converts quantitative attributes into binary attributes and 2) a post-processing step which reconverts binary association rules into quantitative association rules. As the pre-processing step, we present the concept of domain partition, and based on the domain partition, we formally redefine the previous bipartition and multi-partition techniques, which are mean-based or median-based techniques for bipartition, and are equi-width or equi-depth techniques for multi-partition. These previous partition techniques, however, have the problem of not considering distribution characteristics of attribute values. To solve this problem, in this paper we propose an intuitive partition technique, named standard deviation minimization. In our standard deviation minimization, adjacent attributes are included in the same partition if the change of their standard deviations is small, but they are divided into different partitions if the change is large. We also propose the post-processing step that integrates binary association rules and reconverts them into the corresponding quantitative rules. Through extensive experiments, we argue that our framework works correctly, and we show that our standard deviation minimization is superior to other partition techniques. According to these results, we believe that our framework is practically applicable for naive users to mine quantitative association rules using commercial data mining tools.

• Journal of Digital Convergence
• /
• v.13 no.12
• /
• pp.75-87
• /
• 2015

The current study examines whether consumers' perceived usefulness of and trust in the integrated mobile payments services positively influence consumer loyalty to the payments system as well as to the online shopping websites where they have used the payments system. Moreover, the study investigates the effects of individual characteristics and brand awareness of the provider of mobile payments on perceived usefulness and trust. Online survey was administered to consumers ranging in age from 20s to 40s. Data analysis reveals that as consumers' perceived usefulness of and trust in the mobile payments system positively influence consumer loyalty to mobile payments and shopping mall websites. The results of the study suggests that e-commerce's user interface design, particularly the transaction system, should receive greater attention as a basic web element of e-commerce building rather than a set of plug-ins or so.

• KDI Journal of Economic Policy
• /
• v.26 no.2
• /
• pp.179-208
• /
• 2004

With the outbreak of the financial crisis in mid-1997, the Korean government has removed a majority of M&A-related regulations in order to facilitate M&A transactions. This was based upon the belief that M&As are one of the most efficient ways to restructure financially distressed firms compared to other government-driven restructuring programs. In this paper, we try to empirically assess the role of M&A in restructuring distressed firms in Korea following the financial crisis. In doing so, three empirical analyses have been conducted. The first analysis attempts to identify financial characteristics of the insolvent M&A targets. The second exercise directly tests the change in performance of insolvent M&A targets before and after such M&A transactions. The third analysis is a more general assessment on the role of M&A transactions to determine if being involved in an M&A transaction (regardless of its motivate) has reduced the probability of becoming insolvent in the future. Overall, we find some evidence supporting that M&A activities after the financial crisis have played a positive role in restructuring financially distressed firms in Korea.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
• /
• v.14
• /
• pp.257-287
• /
• 2000

Many problems and complaints have been caused by applying the UCP to the standby credit. To solve the problem, International Standby Practices were established. ISP and UCP are similar in that both of them generally regulate the transaction of credit. However, when the ISP is compared with the UCP, the following features are found : 1. In the UCP, when Force Majeure such as acts of God or strikes cause temporary work stoppage, the expiration date cannot be extended. In the ISP, the expiration date can be extended to 30 days afte the place for presentation re-opens for business in the same situation. 2. The UCP does not specify who the issuer of a document must be because there can be many issuers of documents. In the ISP, it is specified that all required documents are to be issued by the beneficiary. 3. In the UCP, compliance between presented documents is required. In the ISP, a discrepancy between presented documents is allowed. 4. In the UCP, if drawings and/or shipments are required by a credit to be made in instalments, and a required drawing/instalment is not made, the credit ceases to be available for any subsequent instalment. In ISP, there is no loss of effect and no influence on the right of beneficiaries, even in the same situation. 5. In the UCP, multiple transfers are not permitted, but partial transfers are. ISP states just the opposite. Multiple transfers are permitted, but partial transfers are not. 6 The UCP obligate each bank (issuer, confirming and nominated bank) to complete their review within a 'reasonable time' but not more than seven banking days. In the ISP, less than three business days is deemed to be not unreasonable and more than seven days is deemed to be unreasonable. 7. ISP, unlike UCP, recognizes that issuers and confirmers may spread their risk through syndication and participation of standby credits. However, the thing to remember is that the ISP should be reviewed carefully before application. If necessary, a partial addition or modifications can be made. Usually, the best advantage of the ISP is given to the issuers. A positive use of the ISP can be made by issuers but, applicants should consider using the UCP to the their rights and duties.

• Journal of Korean Society for Geospatial Information Science
• /
• v.23 no.4
• /
• pp.35-41
• /
• 2015

Real estate appraisal methods include profit-based, cost-based and comparison-based measures. The purpose of this study is to scientifically quantify the comparison-based method mostly utilized in valuating real estate property among the appraisal methods. The comparison method is to estimate the value of target property from other previously-traded property cases by comparing and adjusting their temporal gap, spatial gap and space-time gap. In appraisal practices, this comparison method is used generally for land property. If based on previous transactions; prices, time point of transaction, region and individual factors were analyzed to valuate. If based on official land values; official value, time point, region and individual factors are analyzed. Of these, the individual factors are an important process of comparing individual characteristics where real estate appraisers' subjective assessment could intervene. Though appraisers, as experts make generally precise assessment, still, it is a subjective judgment open to difference between appraisers themselves, causing disputes from time to time. In this recognition, the study seeks to quantify such a subjective assessment of appraisers by running GIS analysis on individual factor components including street condition, access condition;and plotting condition.

• Archives of design research
• /
• v.14 no.1
• /
• pp.63-70
• /
• 2001

Thanks to the inter-connection of information servers throughout the world based on the internet technology, the new sphere which actual transaction can be made like in the visible market has become conspicuous as the virtual space. The movement to realize the new business through the cyber space has been actively ongoing. In the domestic market, a lot of corporations knowing the needs of internet shopping malls have entered into this e-business but they have not made a big success comparing with internet's potentials. And, it can be attributed to the simple planes and the limitations of information provided by the cyber malls, which means that the needs of better information transfer we apparent Accordingly, in this thesis, the research on the 3-D based products and shopping malls has been made through the inter-complementary composition between the 2-D shopping malls and 3-B ones. This research consists of 3 parts. Firstly, through the research on references and existing data, it presents the analysis on consumer's characteristics and sales limits of the internet shopping mall's products. Secondly, the background of 3-D shopping mall's advent and the virtual reality technology data are put together. Finally, it presents how the development of 3-D based product modeling and shopping malls can increase the consumer's purchase power and furthermore the directions of shopping malls to go.

• Journal of KIISE:Computing Practices and Letters
• /
• v.9 no.1
• /
• pp.33-46
• /
• 2003

A Home Location Register(HLR) database system manages each subscriber's location information, which continuously changes in a cellular network. For this purpose, the HLR database system provides table management, index management, and backup management facilities. In this thesis, we propose using a two-level index method for the mobile directory number(MDN) as a suitable method and a chained bucket hashing method for the electronic serial number(ESN). Both the MDN and the ESN are used as keys in the HLR database system. We also propose an efficient backup method that takes into account the characteristics of HLR database transactions. The retrieval speed and the memory usage of the two-level index method are better than those of the R-tree index method. The insertion and deletion overhead of the chained bucket hashing method is less than that of the modified linear hashing method. In the proposed backup method, we use two kinds of dirty flags in order to solve the performance degradation problem caused by frequent registration-location operations. For a million subscribers, proposed techniques support reduction of memory size(more than 62%), directory operations (2500,000 times), and backup operations(more than 80%) compared with current techniques.

• Journal of Distribution Science
• /
• v.16 no.8
• /
• pp.79-89
• /
• 2018

Purpose - This research aims to investigate the factors that influence consumer's overseas online shopping behavior. Consumers adopt overseas online shopping as a new buying way and more and more consumers prefer overseas online shopping than traditional shopping ways. Consumers' behaviors in this shopping experience can be different from other shopping experiences. With the increase of overseas online shopping, we need to find antecedents and results of overseas online shopping. Especially there would be positive or negative factors which influence overseas online shopping motivation. To find the relationship, this study examines self-efficacy and impulsivity as major factors which influence overseas online shopping. We also suggest that several attitude factors increase self-efficacy and it is positively related to customer satisfaction. On the other hand, we assume that overseas online shopping factors influence impulsivity of buying and it will decrease customer satisfaction. Research design, data, and methodology - This empirical study data were collected from Korean people who experience overseas online shopping. The subjects for this study were confined to shoppers who used overseas online shopping within the past six months. A total of 267 responses were gathered. SPSS 23.0, PLS 2.0 software were used in the data analysis. Descriptive statistics were used to show sample characteristics. We examined reliability, validity test for constructs. All measurement items used seven-point scales(1= very strong disagree, 7 = very strongly agree) drawn from previously published papers. Partial Least Square method was applied to find the relationship between antecedent factors and dependent factors and hypotheses were estimated. Results - Results show that perceived superiority, perceived ease of use, perceived transaction safety, perceived behavioral control positively affect self-efficacy. Self-efficacy influences positively to consumer's post purchase satisfaction. Perceived monetary benefit and perceived uniqueness motivated impulse buying. This can make consumer's post purchase dissatisfaction. Conclusions - This paper attempted to confirm the existence of both the positive and negative faces of overseas online shopping. The result reveals that self-efficacy is a major factor which may increase satisfaction in the overseas online shopping. Usually, we can think monetary benefit and uniqueness of products motivate overseas online shopping. But it can also intrigue impulse buying and negatively affect customer relationship. Therefore companies should provide enough products information to their potential customers and they might apply adequate processes such as recommendation, comparing systems to build long term relationship with their customers.

• KIEE International Transaction on Systems and Control
• /
• v.2D no.2
• /
• pp.78-91
• /
• 2002

In the thermal power plant, there are six manipulated variables: main steam flow, feedwater flow, fuel flow, air flow, spray flow, and gas recirculation flow. There are five controlled variables: generator output, main steam pressure, main steam temperature, exhaust gas density, and reheater steam temperature. Therefore, the thermal power plant control system is a multinput and output system. In the control system, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, strict control of the steam temperature must be maintained to avoid thermal stress. Maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature versus changes in fuel flow rate, difficulty of control of the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, and the fluctuation of inner fluid water and steam flow rates during the load-following operation. Up to the present time, the Proportional-Integral-Derivative Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on the characteristic comparison of the PID controller and the modified 2-DOF PID Controller (Two-Degrees-Freedom Proportional-Integral-Derivative) on the DCS (Distributed Control System). The method is to design an optimal controller that can be operated on the thermal generating plant in Seoul, Korea. The modified 2-DOF PID controller is designed to enable parameters to fit into the thermal plant during disturbances. To attain an optimal control method, transfer function and operating data from start-up, running, and stop procedures of the thermal plant have been acquired. Through this research, the stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Also, this paper addressed whether an intelligent tuning method based on immune network algorithms can be used effectively in tuning these controllers.