• The KIPS Transactions:PartD
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• v.16D no.3
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• pp.451-462
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• 2009

Collaborative Filtering (CF), one of the most successful technologies among recommender systems, is a system assisting users in easily finding the useful information. However, despite its success and popularity, CF encounters a serious limitation with quality evaluation, called cold start problems. To alleviate this limitation, in this paper, we propose a unique method of building models derived from explicit ratings and applying the models to CF recommender systems. The proposed method is divided into two phases, an offline phase and an online phase. First, the offline phase is a building pre-computed model phase in which most of tasks can be conducted. Second, the online phase is either a prediction or recommendation phase in which the models are used. In a model building phase, we first determine a priori predicted rating and subsequently identify prediction errors for each user. From this error information, an error-reflected model is constructed. The error-reflected model, which is reflected average prior prediction errors of user neighbors and item neighbors, can make accurate predictions in the situation where users or items have few opinions; this is known as the cold start problems. In addition, in order to reduce the re-building tasks, the error-reflected model is designed such that the model is updated effectively and users'new opinions are reflected incrementally, even when users present a new rating feedback.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.120-129
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• 2009

The purpose of this study was to investigate the pulpal response to direct pulp capping with dentin sialoprotein (DSP) -derived synthetic peptide in teeth of dogs, and to compare its efficacy to capping substances $Ca(OH)_2$ and white mineral trioxide aggregate (WMTA). A total of 72 teeth of 6 healthy male beagle dogs were used. The mechanically exposed pulps were capped with one of the following: (1) DSP-derived synthetic peptide (PEP group): (2) $Ca(OH)_2$ (CH group): (3) a mixture paste of peptide and $Ca(OH)_2$ (PEP+CH group): or (4) white MTA (WMTA group). The access cavity was restored with a reinforced glass ionomer cement. Two dogs were sacrificed at each pre-determined intervals (2 weeks, 1 month, and 3 months). After the specimens were prepared for standard histological processing, sections were stained with hematoxylin and eosin. Under a light microscope, inflammatory response and hard tissue formation were evaluated in a blind manner by 2 observers. In the PEP group, only 3 of 17 specimens showed hard tissue formation, indication that the DSP-derived synthetic peptide did not induce proper healing of the pulp. Compared with the CH group, the PEP group demonstrated an increased inflammatory response and poor hard tissue formation. The CH and WMTA groups showed similar results for direct pulp capping in mechanically exposed teeth of dogs.

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.631-643
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• 2006

Moving objects in a mobile environment to change their position based on the change of time require a query with their position as a basis. Efficient Regional Decision for Continuous Skyline Queries requires objectively pre-calculating the OSR(Optimal Skyline Region) regardless of the speed and direction of the moving objects. It proposes techniques to reduce the frequency of continuous queries by choosing a VCircle(Validity Circle) as safe location which has radius of the distance to the closest region with position on the moving object at center. But, a VCircle's area varies based on the Moving object's position from first marked time of continuous query. Therefore, the frequency of its continuous query is variable and also when the object moves inside of OSR, query can re-occur frequently In this paper, we suggest a technique of selecting an IVCircle(Interior Validity Circle) in a Skyline Region as the static Safe Region using the characteristics of the OSR. An Interior IVCircle can be calculated in advance when the OSR is decided. Our experiment shows that the frequency of using IVcircle as safe region reduced than that of using VCircle as safe region by 52.55%.

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.578-589
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• 2006

Owing to the proliferation of Radio Frequency Identification (RFID) technologies which is being watched as a core technology of ubiquitous computing, applications which offer convenience to people using RFID technologies are more and more increased. To easily develop these applications, a middleware system which acts as a bridge between RFID hardware and application is essential. In this paper, we propose a novel XML-based RFID middleware system called UbiCore (Ubiquitous Core). UbiCore has following features: First, UbiCore employs its own query language called XQueryStream (XQuery for Stream Data) which is originated from XQuery. Second, UbiCore has the preprocessing phase called pre-filtering prior to query evaluation and reuses the intermediate result of previous evaluation to speed up the processing of RFID tag data stream. Third, UbiCore supports query on both continuously generated stream data and archived historical data. And last, UbiCore offers a distinct markup language called Context-driven Service Markup Language (CSML) to easily specify the linking information between context and service.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6274-6281
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• 2015

Radio-based train control system has driving headway shortening effect by real-time train interval control using two-way radio communication between onboard and wayside systems, and reduces facility investment because it does not require any track-circuit. Automatic train protection(ATP), the most significant part of the radio-based train control system, makes sure a safe distance between preceding and following trains, based on real-time train location tracing. In this paper, we propose the overall ATP train interval control algorithm to control the safe interval between trains, and preprocessing-based speed profile calculation algorithm to improve the processing speed of the ATP. The proposed speed profile calculation algorithm calculates the permanent speed limit for track and train in advance and uses as the most restrictive speed profile. If the temporary speed limit is generated for a particular track section, it reflects the temporary speed limit to pre-calculated speed profile and improves calculation performance by updating the speed profile for the corresponding track section. To evaluate the performance of the proposed speed profile calculation algorithm, we analyze the proposed algorithm with O-notation and we can find that it is possible to improve the time complexity than the existing one. To verify the proposed ATP train interval control algorithm, we build the train interval control simulator. The experimental results show the safe train interval control is carried out in a variety of operating conditions.

• The KIPS Transactions:PartD
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• v.11D no.2
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• pp.325-338
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• 2004

A data warehouse stores information that is collected from multiple, heterogeneous information sources for the purpose of complex querying and analysis. Information in the warehouse is typically stored In the form of materialized views, which represent pre-computed portions of frequently asked queries. One of the most important tasks of designing a warehouse is the selection of materialized views to be maintained in the warehouse. The goal is to select a set of views so that the total query response time over all queries can be minimized while a limited amount of time for maintaining the views is given(maintenance-cost view selection problem). In this paper, we propose an efficient solution to the maintenance-cost view selection problem using a genetic algorithm for computing a near-optimal set of views. Specifically, we explore the maintenance-cost view selection problem in the context of OR view graphs. We show that our approach represents a dramatic improvement in terms of time complexity over existing search-based approaches that use heuristics. Our analysis shows that the algorithm consistently yields a solution that only has an additional 10% of query cost of over the optimal query cost while at the same time exhibits an impressive performance of only a linear increase in execution time. We have implemented a prototype version of our algorithm that is used to evaluate our approach.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.247-256
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• 2002

In a wireless multicasting when a mobile host moves to the new bate station being in the same multicast group it needs to exchange information about data delivery between base stations to receive data from the new base station at once. However it is inefficient to use the existence schemes because it takes too much time to exchange information and many overheads. The next, a mobile host moving to the base station not being in the same multicast group, the old base station will pre-forward data to neighboring base stations to avoid transmission delay. However, if other mobile hosts move at short interval, the old base station may retransmit the same data to the same neighboring base stations. In this paper we proposed called Information Exchange Scheme (IES). In IES in the same multicast grope the base stations exchange information locally so it takes the minimum time and overheads to use IES. Also in IES the neighboring base stations delay to delete data for continuous moving of other MHs. We also present how our scheme is efficient by producing cost ad simulating.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.775-782
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• 2001

Recently the use of Linux OS is increasing to tremendous figures. But due to the fact that Linux is distributed on an open-source policy, the need of security is an upcoming question which leads to widespread development of security on a Linux based environment. Cryptography, however, can cause various problems because of difficulty of key management. A lot of researchers have been concentrating on the key recovery technique to eliminate the reverse effect of using these kinds of security and to promote positive aspects of using it. In this thesis I am suggesting an mechanism based on the key recovery technique, as a method to save time in recovery and resetting a disconnection between two end-users through IPSec (IP Security) protocols in a VPN (Virtual Private Network) environment. The main idea of the newly suggested mechanism, KRFSH (Key Recovery Field Storage Header), is to store the information of the session in advance for the case of losing the session information essential to establish a tunnel connection between a SG and a host in the VPN environment, and so if necessary to use the pre-stored information for recovery. This mechanism is loaded on the IPSec based FreeS/WAN program (Linux environment), and so the VPN problem mentioned above is resolved.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.90-96
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• 2013

The anti-obesity effect of ethanol xtract and their fractions from Rumex Crispus L. on the differentiation of 3T3-L1 pre-adipocytes to adipocytes was investigated by suppressing adipocyte differentiation and lipid accumulation with Oil red O assay, western blot and real-time PCR analysis. Ethyl acetate fraction of Rumex crispus L. significantly inhibited adipocyte differentiation when treated during the adipocyte differentiation process, as assessed by measuring fat accumulation using Oil red O staining. In inducing differentiation of 3T3-L1 preadipocytes in the presence of an adipogenic cocktail, isobutylmethylxanthine (IBMX), dexamethasone- and insulin-along with ethyl acetate fraction residue processing treatment significantly decreased protein expression of obesity-related proteins, such as peroxisome-proliferators-activated-receptor-${\gamma}$ ($PPAR{\gamma}$) and CCAAT enhancer-binding-proteins ${\alpha}$ ($C/EBP{\alpha}$). These results indicate that ethyl acetate fraction of Rumex crispus L. is the most effective candidate for preventing obesity. However further studies will be needed to identify the active compounds that confer the anti-obesity activity of ethyl acetate fraction from Rumex crispus L.

• Food Science of Animal Resources
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• v.29 no.3
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• pp.356-363
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• 2009

This study was carried out to investigate the effect of hot boning and curing condition on the quality characteristics of ground chicken breast. Treatments were cured by four conditions follows; control (general curing method), T1 (after hot-boning and then immediately cured), T2 (after hot-boning and immediately cured, then frozen), and T3 (after hot-boning, immediately frozen, refrigerated and then cured). The pH of chicken breast in the state of pre-rigor was 6.22. The pH of cold storage or freezing chicken breast meat respectively were 5.70 or 5.61. The pH of T1 and T2 treatments were significantly higher than those of control and T3 treatment (p<0.05). After stored for 1 wk, the pH value of T1 treatment had a higher value than those of other treatments. T1 treatment had the highest water holding capacity and the lowest cooking loss among all treatments, regardless of the cooking methods. The reduction in diameter for T1 and T2 treatments was lower than those of control and T3 treatment (p<0.05). T1 treatment had the lowest fat loss and moisture loss among all treatments, and the emulsifying capacity of T1 treatment was the highest. The protein solubility of T1 treatment was significantly lower than that of T3 treatment.