• Journal of the Korea Safety Management & Science
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• v.4 no.3
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• pp.177-187
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• 2002

The contamination problem is getting worse now a day because of the industrial activities. Recently it has been announced that there's environmental hormone in river and lake which produces clean water, also there's too many of algae reproduces under the water and some virus in the drinking water. The quality of water is very important. pure and clean water is not only a precondition for human being to live but a basic factor to improve the quality of life. so a water purification system must be developed. This study is about the surface washing treatment technique. We tried to use a rotary nozzle to get a tush degree of efficiency, for it was not enough with present way of washing. The nozzle is run by water pressure. The results of the experiment are as follows. We got a clean and equal surface after washing. After washing, the water's maximum consistency was 330NTU and it shows that this way is better than before one with 215NTU. Clean level of the filter was 6$^{\circ}$and it's 2.8 times higher than 17$^{\circ}$with the old way. We can see the results that the new way of washing is more effective than old way based on this study.

• The Korean Journal of Financial Studies
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• v.2 no.2
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• pp.315-344
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• 1995

The relationship of information flow and market price formation are central to the basic tenets of financial economics. Whereas information is usually treated as being either public or private(monopolistic), most empirical studies focus on the price effects of public announcements. More recent research has centered more on the role of private information, such as insider trading, in efficient pricing and whether such trading increases investor welfare. Typically, 'insider trading' refers to an officer that trades in his/her company's shares. Insider trading, however, also refers to anyone who generates private, albeit costly, information concerning a stock's fundamental value. Normally, such insider activity is more difficult to ascertain. One way in which negative information is revealed is through short-selling activity, especially the monthly short-interest positions reported by the national stock exchanges. Diamond and Verrecchia(1987) provide a theoretical paradigm that predicts a negative price adjustment upon announcement of n company's monthly short interest, if the short interest displays an unusual increase and is correlated with negative information that is not yet public. Empirical studies of the short-run, negative price effect predicted by Diamond and Verrecchia find mixed results. One explanation is that the time period studied is too short for the market to absorb the informational content of these announcements. One reason is that these announcements are an ambiguous signal that requires more individuals and time to collect and act on the same information before full revelation occurs or before the implicit information becomes publicly known. This 'long delayed reaction' also serves as a motivation for related research on the wealth effect of mergers, share repurchases, and initial equity offerings in which long-run performance differs from the initial, short-run reaction to such announcements or offerings.

• Restorative Dentistry and Endodontics
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• v.47 no.3
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• pp.32.1-32.11
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• 2022

Objectives: This study aimed to evaluate the influence of inorganic composition and filler particle morphology on the mechanical properties of different self-adhesive resin cements (SARCs). Materials and Methods: Three SARCs including RelyX Unicem-2 (RUN), Maxcem Elite (MAX), and Calibra Universal (CAL) were tested. Rectangular bar-shaped specimens were prepared for flexural strength (FS) and flexural modulus (FM) and determined by a 3-point bending test. The Knoop microhardness (KHN) and top/bottom microhardness ratio (%KHN) were conducted on the top and bottom faces of disc-shaped samples. Sorption (Wsp) and solubility (Wsl) were evaluated after 24 hours of water immersion. Filler morphology was analyzed by scanning electron microscopy and X-ray energy dispersive spectroscopy (EDS). FS, FM, %KHN, Wsp, Wsl, and EDS results were submitted to 1-way analysis of variance and Tukey's post-hoc test, and KHN also to paired t-test (α = 0.05). Results: SARC-CAL presented the highest FS value, and SARC-RUN presented the highest FM. SARC-MAX and RUN showed the lowest Wsp and Wsl values. KHN values decreased from top to bottom and the SARCs did not differ statistically. Also, all resin cements presented carbon, aluminum, and silica in their composition. SARC-MAX and RUN showed irregular and splintered particles while CAL presented small and regular size particles. Conclusions: A higher mechanical strength can be achieved by a reduced spread in grit size and the filler morphology can influence the KHN, as well as photoinitiators in the composition. Wsp and Wsl can be correlated with ions diffusion of inorganic particles.

• Journal of KIISE:Software and Applications
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• v.30 no.1_2
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• pp.58-72
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• 2003

The objects generated by the keyword new in Java are automatically managed by the garbage collector Inside Java Virtual Machine (JVM) not like using the keywords free or delete in C or C++ programming environments. This provides a means of freedom of memory management burden to the application programmers. The garbage collector however. inherently has its own run time execution overhead. Thus it causes the performance degradation of JVM significantly. In order to mitigate the execution burden of a garbage collector, we propose a novel way of dynamic memory management scheme in Java environment. In the proposed method, the application programmers can explicitly manage the objects In a simple way, which in consequence the run-time overhead can be reduced while the garbage collector is under processing. In order to accomplish this, Java application firstly calls the APIs that arc implemented by native Jana, and then calls the subroutines depending on the JVM, which in turn support to keep the portability characteristic Java has. In this way, we can not only sustain the stability in execution environments. but also improve performance of garbage collector by simply calling the APIs. Our simulation study show that the proposed scheme improves the execution time of the garbage collector from 10.07 percent to 52.24 percent working on Mark-and-Sweep algorithm.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.597-600
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• 2005

The software streaming technology enables telematics software to be automatically updated through a wireless network. When the software starts running, software streaming system inspects its version and then, automatically download latest one. The software streaming system breaks the software into several pieces that are streamed to the user as needed. In this way, software streaming system can improves the telematics application load time while updating the software through wireless network. In our experiments, the application load time was reduced about 7 times compared to downloading whole software at best case.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.264-269
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• 1993

In this paper, we develop the basic robot commands on the level of VAL robot language and the integrated environment software of the robot management system to give users an easy way of programming and running the robot. The developed software is designed to support Korean language and to be run by the pop-up menus for programming commands and inputs. Geometrical and dynamical features can be viewed on a computer monitor by graphics and the taught works can be interfaced with a computer and controllers.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.5-9
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• 2003

Stress and deflection of Active Fiber Composite(AFC) embedded and/or attached composite structures are numerically investigated at the constituent level by the Direct Numerical Simulation(DNS). The DNS approach which models and simulates the fiber and matrix directly using 3D finite elements need to be solved by efficient way. To handle this large scale problem, parallel program for solving piezoelectric behavior was developed and run on the parallel computing environment. Also, the stress result from DNS approach is compared with that from uniform field model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.717-720
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• 2007

With the convergence of mobile devices and the Internet ubiquitous computing promises to revolutionalize the way that we access services and run application. However, ubiquitous computing environments, in particular, mobile and wireless environments interfaced with the Internet, currently possess security vulnerabilities that are ripe for attack from cyber-threats. Thus, this paper discusses the Limitation of current security mechanisms in ubiquitous computing environments

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.366-368
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• 2011

In this paper, we introduce a new kind of expressions for privacy protection techniques in database, such as K-anonymity L-diversity and t-closeness. With such kind of expressions, we provide a new way to solve the privacy protection problems, such as Linear programming, Non-linear programming, Integer programming and so on. Also most of the heuristic techniques are also efficient to be adopted under the expressions given.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.152-157
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• 1999

In this paper, we introduce the concept of web-based simulation and some reviews on the distributed simulation on the World Wide Web (WWW) and classify the features of current web-based simulation under the distributed way. And then we suggest the structure of distributed web-based simulation which can achieve parallel simulation and reduce simulation run time and show how the callback mechanism works to enable the distributions of jobs to clients with push service in Remote Method Invocation (RMI). Finally we present a prototype of distributed web-based simulation.