• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.489-493
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• 2012

Positron Annihilation Lifetime Spectroscopy is a non-destructive technique to study voids and defects in solids by the measurement of gammas from electron-positron annihilation. In this study, we measured the lifetime of CR, EPDM, NBR, all of which are widely used polymer in various fields. A conventional fast-fast coincidence system in KAERI(Korea Atomic Energy Research Institute) has been used to measure the lifetime spectra, Three lifetime components were analyzed from each lifetime spectra. According to Tao-Eldrup model equation, the size and fraction of free-volume were calculated. Mean radius and free volume fraction of CR, EPDM NBR are $0.1217nm^3$(1.9103%), $0.14780nm^3$(5.3147%), $0.1216nm^3$(2.6381%), respectively. Through these measurements, we identified the feasibility of the PAL system for polymer analysis.

• Journal of the Korean Geosynthetics Society
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• v.1 no.1
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• pp.43-51
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• 2002

In this study, free swell index of betonite was examined in several regeants; distilled water, leachate, seawater and 3% NaCl solution. Free swell index values of bontonite to be added Poly(acrlylic acid), PYA(Polyvinyl Alcohol) or SCMC (Sodium Carboxymethyl Cellulose) were evaluated and compared. From this, it was confirmed that hydraulic conductivities of GCL in seawater were examined and the hydraulic conductivities of GCL in seawater were compared to those in distilled water. The average values of free swell indices of bentonite were decreased in order of distilled water>leachate>seawater. It was shown that no significant differences were occurred for free swell index between seawater and 3% NaCl solution. For bentonite to be added PVA, the other reagents except distilled water didn't affect increase of swelling. Swelling properties of bentonite to be added SCMC were improved except 3% NaCl solution.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.125-134
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• 2009

This paper deals with the free vibrations of circular strip foundations which have uniform solid rectangular cross-section. The ground which supports circular strips was modeled as the two parameter elastic foundation. Differential equations governing the flexural-torsional free vibrations of circular strips supported by such foundation were derived, and solved numerically for obtaining the natural frequencies and mode shapes. Boundary condition of free-free ends was considered for numerical examples. Four lowest natural frequencies according to the variations of five system parameters i.e. subtended angle, depth ratio, contact ratio, elasticity ratio and soil parameter are reported in the non-dimensional forms. Also, typical mode shapes of both deformations and stress resultants are presented in the figures. Experiment was conducted for validating the theory developed in this study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.30-37
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• 2000

We studied on acquiring of transfer function and tuning of 2-DOF PID controller using ANFIS for the optimum control to turbine's variables variety. Since the shape of a membership function in the ANFIS based on the characteristics of plant. ANFIS based control method is effective for plant that its variable vary. On the other hand, a start-up time is very short and its variable's value for optimal start-up in gas turbine should be varied, but it is very difficult for such a controller to design. In this paper, we tune 2-DOF PID controller after apply a ANFIS to the operating data of Gun-san gas turbine and verify the characteristics. Its results is compared to the conventional PID controller and discuss. We expect this method will be used for another process because it is studied on the real operating data.

• Korean journal of communication and information
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• v.17
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• pp.7-36
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• 2001

This thesis discussed the nature of freedom of speech with emphasis on Locke's theory of social contract. First, I examined the nature of freedom of speech induced from Locke's social contract, and argued that the nature of Locke's freedom of speech exists on the self-ownership of humans. Secondly, I studied how Locke's right of self-ownership was related to the right of freedom of speech and how it is realized in civil society. I could analyze how freedom of speech was actualized with un-equality in the social relations. Thirdly, I investigated how locke's possessive freedom of speech was materialized in the market society. I tried to find out the nature of freedom of speech actualization in the capitalist market society. Finally, 1 studied to what extent the state of Locke could intervene the freedom of speech and reconsidered the meaning of locke's limit of natural risht in modern society. Conclusively, Locke's notion of Natural Right and Law of Nature have greatly influenced contemporary idea of free speech. His idea helps understand the position of liberal democratic speech. It also shows well the relation of freedom of speech and Natural Right and has helped us understand freedom of speech in terms of the position of the right of property.

• Journal of Korean Library and Information Science Society
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• v.33 no.3
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• pp.1-40
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• 2002

All libraries are forums for information and ideas. Therefore, libraries must have systematic devices through which library users can make use of library materials freely. The systematic devices usually have the form of Library Bill of Rights. The aim of this study is to offer basic data in case our country adopt Library Bill of Rights in the near future. In this thesis, the significance of Library Bill of Rights was investigated and the common components were drawn from the analysis of the changing processes and contents of Library Bill of Rights in the USA and Japan. In the USA and Japan, the Library Association an official institution adopted Library Bill of Rights and established permanent departments to keep and develop Library Bill of Right as well as to solve the problems such as infringement of freedom of library. The common components of Library Bill of Rights are as follows: freedom to collect materials, freedom to provide materials, right to refuse censorship, cooperation with the persons ind groups concerned, a person's rights to use a library, fair use of the library facilities, and protection users' privacy.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.75-85
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• 2000

When applying a system identification technique, which incorporates an experimental model to a corresponding finite element model of a structure, one of the major problems is the large difference in the numbers of degrees of freedom (dof) between the two models. While there are large number of dofs in a finite element model, the number of measurement points is practically limited. So it is very difficult to incorporate them. Especially rotational dofs are hard to measure. In this study a method is presented for estimating structural dynamic responses at unmeasurable locations in frequency domain. The proposed method is tested numerically and the feasibility for practical application has been demonstrated through an example structure under moving loads, where translational and rotational dofs of beam at a center point are estimated from the partial measurements of responses at accessible points.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.24-29
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• 2004

In this paper, we summarize the results of free drop wind tunnel test, separation analysis and flight test in order to verify the safety during the separations of an external fuel tank and the LAU-131 rocket launcher from XKO-l. The wind tunnel test was conducted to show the safety in free drop of the stores and to gather the trajectory data for fine tune of MSAP(Multi-body Separation Analysis Program). The enhanced MSAP was then used to predict the trajectories of the stores with and without the ejector forces. A correlation of MSAP results for free drop case was also made to show the safety of jettison with the free drop type bomb rack. Moreover, the flight test was conducted. and its results were compared to analysis results. Finally, the safe jettison boundary was determined from the flight test.

• Journal of Korean Philosophical Society
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• v.130
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• pp.47-77
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• 2014

The purpose of this paper is to justify the following four points. 1) Both communitarianism maintaining perfectionism and liberalism maintaining state neutralism are wrong. Communitarian liberalism is right. 2) If we accept a standpoint of communitarian liberalism, every state must make its own moral textbook for the achievement of common good. Of course, it dose not mean that a government must be an author of moral textbook. 3) The subjects of unification education and democratic citizenship education must be included in moral textbook. The crucial difference between moral education and civic education lies not in the educational subject but in the educational method. In order to internalize communal values and virtue, moral education prefer reflective internalization to indoctrination. But civic education prefer indoctrination to reflective internalization. 4) An desirable Korean who shares Korean values and virtue, provisional moral truth of Korea is a citizen of two isms, namely nationalism and cosmopolitanism.

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.36-41
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• 2017

As the space debris in the satellite orbit increases, the risk of collision between the currently operating satellites and the space debris is continuously increasing. Therefore, in this study, we designed one-degree-of-freedom capture device using simple deployment mechanism. The capture device consists of four link groups connected with net. To increase the reliability, each link group is connected to one driving part so that the total degree of freedom is 1. In addition, the links were stowed on each side of the satellites so that they would not affect the janitor satellite mission. Finally, to confirm the possibility of deployment in the space environment, we carried out deployment experiments in water similar to the microgravity environment, and confirmed the deployment of capture device and the possibility of capturing target satellite.