• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.179-184
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• 1998

Colossal magnetoresistance is closely related to (but is not) the abrupt change of electrical resistivity in the vicinity of Curie temperature, which is caused by the temperature dependent paramagnetic-ferromagnetic phase transition and concurrent change of electrical conducting mechanism. A resistivity-temperature equation is presented to fully describe the overall behavior, especially the abrupt change. The main ingredients of the equation are a simple effective media theory and a function for the temperature dependent fraction of ferromagnetic phase. The model fits very well to the measured resistivity-temperature curve of $La_{0.7}Ca_{0.3}MnO_3$.

• The Journal of the Korea Contents Association
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• v.10 no.3
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• pp.92-100
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• 2010

Due to the development of digital appliance, role of TV causes both-way by introducing IPTV, and SNS service causes big change of watching environment and residence environment. There are good conditions on the role of integrated control because it is arranged in the living room which secures movement most effectively and because family members can easily use, and the degree of use is high. Therefore, we infer user's needs by analyzing user scenario and current role of TV in home network environment. Primarily, we collect surveys of development scenario and technology which companies suggest TV applied by home network service, and secondly, we comparatively study scenario which the companies mentioned above suggest through observing user scenario, and study the role of IPTV in the future through actual scenario-based experiment by ethnography. After analyzing user scenario through case study and experiment, there are integrated device studies mainly in company study because it can be made up inside home, security and entertainment. On the other hand, there are patterns of user behavior by scenario experiment mainly in auto-tainment, security, and it showed that it is insufficient for interaction between TV and home media peripheral. Through this paper, we analyze context of home user, and based on this, we could suggest effective use of service development. Also after analyzing user form, we could know it also should be considered of ratio between activity inside home and activity outside home.

• Convergence Security Journal
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• v.5 no.3
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• pp.59-65
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• 2005

Ubiquitous computing environment has a lot of different things as for applying existing security technical. It needs authentication method which is different kinks of confidence level or which satisfies for privacy of user's position. Using range localizes appoint workstation or it uses assumption which is satify environment of client in Kerberos authentication method which is representation of existing authentication method but it needs new security mechanism because it is difficult to offer the condition in ubiquitous computing environment. This paper want to prove the result which is authentication method for user authentication and offering security which are using wireless certificate from experiment in ubiquitous environment. Then I propose method which is offering security and authentication in ubiquitous environment.

• Electrical & Electronic Materials
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• v.10 no.2
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• pp.134-140
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• 1997

PbTiO$_{3}$-PbZrO$_{3}$-Pb(Ni$_{1}$3/Nb $_{2}$3/O$_{3}$)(PZT-PNN) thin films were prepared from corresponding metal organics partially stabilized with diethanolamine by the sol-gel spin coating method. Each mol rates of PT:PZ:PNN solutions were #1(50:40:10), #2(50:30:20), #3(45:35:20) and #4(40:40:20), respectively. The spin-coated PZT-PNN films were sintered at the temperature from 500.deg. C to 600.deg. C for crystallization. The P-E hysteresis curve was drawn by Sawyer-Tower circuit with PZT-PNN film. The coercive field and the remanent polarization of #4(40:40:20 mol%) PZT-PNN film were 28.8 kV/cm and 18.3 .mu.C/cm$^{2}$, respectively. Their dielectric constants were shown between 128 and 1120, and became maximum value in MPB(40:40:20 mol%). The leakage currents of PZT-PNN films were about 9.4x 10$^{-8}$ A/cm$^{2}$, and the breakdown voltages were about 0.14 and 1.1 MV/cm. The Curie point of #3(45:35:20 mol%, sintered at 600.deg. C) film was 330.deg. C.

• Korean Security Journal
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• no.57
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• pp.277-301
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• 2018

Korean society is a mixed risk society in terms of risk and distrust. This is because the risks and disasters of the farming and industrial societies, the modern and the information society, exist simultaneously in the present time. Ulrich Beck's point that the endless development of science and technology to acquire economic wealth is simultaneously entering a risk society is providing us with many implications. In this paper, we reviewed the Ulrich Beck's "reflexive modernization" theory in the late 20th century, pointing to the rise of a risk society as a result of the evolution of new modernization. This is because the "reflexive modernization" can be a direction in which we can reflect our wrong past from a human-centered perspective and design a desirable future. In this sense, it is important to present ways to overcome the dangerous society through the reinterpretation of Ulrich Beck, who advocated the modernization of reflectively. In order to overcome the future risks that the fourth industrial revolution will bring, we must provide direction for the government's security policies and public security consciousness.

• Korean Security Journal
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• no.8
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• pp.107-125
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• 2004

China is an ancient country that has one of the oldest civilizations on earth. Since the end of 1970s, China has made her administrative and economic reform and opening up to the outside world. Now the administrative and economic reforms has scored great success with a series of important accomplishments. China's peculiar political economy largely explained the changing reform initiatives over times. The problems confronting Chinese officials are markedly different from the West despite the fact the China and the West have engaged their efforts in undertaking administrative reforms in the last two decades or so. The purpose of this study is to analyze the bureaucracy, especially the police civil service system in China. Core features of the institution of China's civil servant system is discussed in this study.

• Electrical & Electronic Materials
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• v.3 no.2
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• pp.123-130
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• 1990

본 논문은 페라이트의 온도특성을 측정하기 위한 다중측정시스템의 설계에 관하여 연구한 것이다. 본 시스템은 전기로의 온도를 제어하기 위한 열전대 콘트롤러, 릴레이 동작을 제어하기 위한 릴레이 콘트롤러 및 릴레이를 구동시키기 위한 스윗칭부, 그리고 GPIB를 이용한 LCR메터 제어부와 이들을 마이크로 컴퓨터와 통신하기 버스 라인으로 구성하였다. 열전대 콘트롤러와 릴레이 콘트롤러는 8255A(Intel LSI)를 주로 이용하여 설계하였으며 릴레이로는 고주파용 릴레이를 사용하여 스윗칭 트랜지스터로 구동시키는 방법을 택하였다. 그리고 LCR-메터에는 GPIB(AD50488)보드를 사용하였다. 측정시료로서는 복합첨가제방식에 의하여 제작된 Mn-Zn-Fe계 페라이트의 시편을 사용하였으며 시료의 특성측정은 자체 제작한 자동계측시스템을 이용하여 분석하였다. 측정결과 온도보상점 T$_{o}$ 와 큐리온도 T$_{c}$ 바로 아래에서 투자율의 급격한 변화를 확인할 수 있었다. 그리고 특성의 계측에 있어서 일관성이 있고 정확한 자료를 얻을 수 있었으며 따라서 본 시스템이 인터페이스와 컴퓨터 사이의 연결성이 좋은 자동다중계측시스템으로 활용 할 수 있음을 확인한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1463-1466
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• 2005

상황인지로부터 알아 낼수 있는 여러가지 정보들 중에 하나가 위치정보이다. 위치인지는 어떠한 대상의 위치를 알아내는 것으로서 가장 대표적인 위치인지 시스템으로는 GPS 가 있다. 그러나 GPS 는 건물 내부에서 사용될 수 없는 단점을 지니고 있다. 이를 극복하기 위해 본 논문은 센서 네트워크 기반의 저전력 실내 위치인지 시스템 설계에 대해 기술한다. 구현된 실내 위치인지 시스템은 센서 네트워크 기반으로 설계되었다. 하드웨어 플랫폼은 모트를 기반으로 하고 있으며 운영체제는 Tiny OS 를 사용한다. 거리측정 방식은 RF 신호와 초음파 신호 사이의 시간차를 이용하고 위치측정은 삼각측량법을 이용하였다. 초음파를 이용한 다른 위치인지 시스템에 비해 저전력으로 동작한다는 점이 특징이며 위치추적이 정확하고 속도가 빠른 장점을 지니고 있다. 현재까지의 실내 위치인지 시스템은 몇가지 극복해야할 문제점들이 남아있지만 지속적인 연구를 통해 문제점들을 해결하면 홈 시큐리티나 오토메이션, 헬스케어 등과 연동하여 실내 환경에서 인간의 삶의 질 향상에 기여 할 수 있을 것이다.

• Convergence Security Journal
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• v.22 no.2
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• pp.77-90
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• 2022

Domestic and foreign automakers compete to lead the autonomous vehicle industry through continuously developing self-driving technologies. These self-driving technologies are evolving with dependencies on the connection between vehicles and other objects such as the environment of cars and roads. Therefore, cyber security vulnerabilities become more likely to occur in the self-driving environment, so it is necessary to prepare for them carefully. In this paper, we model the threats in autonomous vehicles and make the checklist to securely countermeasure them.

• Information Systems Review
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• v.19 no.3
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• pp.201-228
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• 2017

Vulnerability information, which can cause serious damage to information assets, has become a valuable commodity, thereby leading to the creation of a vulnerability market. Vulnerability information is traded on the vulnerability market from several hundred dollars to hundreds of thousands of dollars depending on its severity and importance, and the types and scope of the vulnerability markets are varying. Based on previous studies on vulnerability markets and hackers, this study empirically analyzed the effects of the security researcher's vulnerability research motivation on his/her vulnerability market use intention. The results are discussed as follows. First, vulnerability research self-efficacy had a significant effect on flow and on white and black market use intention but not on perceived benefit. Second, flow had a significant effect on perceived benefit and on black market use intention but had no effect on white market use intention. Third, perceived profit had a significant effect on white and black market use intention. Fourth, vulnerability research self-efficacy had a significant effect on perceived benefit through flow. Fifth, flow had a significant effect on white and black market use intention through perceived profit. These findings can be used to predict the behavior of security researchers who have experience in exploiting vulnerabilities.