• 설비공학논문집
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• 제2권2호
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• pp.137-141
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• 1990

When the relative humidity is measured with an aspirated psychrometer, three factors, which affect the measurement of relative humidity, are atmospheric pressure, the size of wet element and the wind velocity. This paper investigated the effects of the above three factors, and the computer code was developed in order to enhance the accuracy of the relative humidity measurement. As results, it is found that the relative humidity decreases by 6%RH with increasing atmospheric pressure from 650 mbar to 1100 mbar. It is found that the relative humidity drops down when the size of the wet element increases, though the effect of the size of the wet element is not significant. Finally, relative humidity increases with the increasing wind velocity. The difference between the psychrometic table in the present KS and the present results is about 2%RH maximum. As a conclusion, the three factors mentioned above should be considered in order to secure accurate measurement of relative humidity.

• Structural Engineering and Mechanics
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• 제39권3호
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• pp.339-360
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• 2011

In the h-type adaptive analysis, when an element is refined or subdivided, new nodes are added. Among them are the transition nodes which are the corner nodes of the new elements formed by subdivision and, simultaneously, the mid-side nodes of the adjacent non-subdivided elements. To secure displacement compatibility, the slave-node approach in which the DOFs of a transition node are constrained by those of the adjacent nodes had been used. Alternatively, transition elements which possess the transition nodes as active mid-side/-face nodes can be used. For C0 plate analyses, the conventional slave-node constraints and the previously derived ANS transition elements are implemented. In both implementations, the four-node element is the ANS element. With reference to the predictions of the transition elements, the slave-node approach not only delivers erroneous results but also fails the patch test. In this paper, the patch test failure is resolved by developing a set of new constraints with which the slave-node approach surpasses the transition-element approach. The accuracy of the slave-node approach is further improved by developing a hybrid four-node element in which the assumed moment and shear force modes are in strict equilibrium.

• 인터넷정보학회논문지
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• 제7권1호
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• pp.59-64
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• 2006

GKRS(Global Key Recovery System)는 키복구 기관과 공개키 인증기관(CA)의 기능들을 결합한 시스템이다[1]. GKRS의 다른 특징으로 User-Dominance(즉, 사용자가 자신의 공개-비밀키 쌍과 특히 공개-비밀키 쌍의 유용성을 검증하기 위한 공개 인자(public element)를 선택하도록 한다.)가 GKRS의 광범위한 적용을 위한 아주 중요한 요소로서 제안되었다. 본 논문에서는 CA에 의해 채택된 User-Dominance 방식과 그에 해당하는 키 검증 방식이 CA에 대한 사용자들의 기만 공격을 허용함을 보임으로서 GKRS의 RSA 방식을 공격하고, 이와 같은 공격으로부터 안전한 개선된 GKRS 방식을 제안한다. 제안된 방식은 CA가 랜덤 수를 이용하여 사용자의 기만 공격 확률을 무시할 정도로 작게 함으로서 안전성을 확보하고 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.474-477
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• 2004

This paper deals with a design experience of Control Element Drive Mechanism (CEDM) that is used to withdraw or insert control rods in nuclear reactor. The design is carried out to satisfy the performance requirements for CEDM that were given to ensure reliable and secure actions of the rods. The electrical parameters for four coils that energize the mechanical actuators in CEDM are determined first, Then a computer simulation for CEDM with these coils is performed to see how it works. An adjustment of the coil parameters is made from the simulation results. Finally, it is shown that our final design is valid to guarantee the required performance since the FEM(finite Element Method) calculation shows sufficient vertical attraction forces of a lift armature and a latch magnet, and good dynamics with a full load.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.165-175
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• 2000

In order to improve the function of a door seal, its section design technique is discussed in this study, Its roles are prevention of an inflow of dusts, noise interception, insulation, wateproof, and the vibroisolating action which reduces vibration between the body and the door of a car while running, and the buffer action which sustain the proper reacting force as the door is closed. In this study, the optimal cross section of a door seal is designed using nonlinear finite element analysis (commercial finete element analysis program EASi-SEAL) and tables of orthogonal arralys with respect to relations between door and door seal to secure the satisfactory airtight property with the minimum force to shut the door.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1050-1055
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• 2007

In the case of a rail road bridge extension work, especially single track to double track, the foundation of new substructure which supports the extended part of superstructure could be interfered by the exist foundation of an old bridge. When these two foundations are jointed to prevent such fatal effects of the structure as unequal subsidence of soil foundations, it is important to prove the structural behaviour of the joining surfaces between new foundation and old foundation. 3-Dimensional Finite Element Analysis Method have been studied for the solutions of the structural behaviour of the foundations. In this analysis, 'Contact Element' which allows the sliding of each adjoining member is used for the joint of the boundary surface of the old and new pier foundations. Furthermore, Material Nonlinear Behaviour Analysis also supports the accuracy of the result in this study because the foundations consist of concrete main bodies and reinforced steel bars. These detailed analyses secure the verification of the structural safety of the foundations in the extension work more firmly.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.682-685
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• 2014

In this paper, we presented the window applicable blind-type frequency selective surface to control the coverage area of wireless communication in secure building or conference room. The proposed frequency selective structure has the reconfigurable frequency range depends on its blind rotation angle. To verify the proposed structure, we fabricated the window blind-type frequency selective surface with four-legged loaded element and ring-type element as a unit cell and performed measurements of the transmission characteristics for different blind rotation angles to prove the feasibility. The measurement results show good agreements with the simulation results. One of the advantages is that the proposed structure does not need to have a bias circuit, so it is very easy to implement at low cost and also can be applied to any planar surface for wireless security applications.

• Journal of Communications and Networks
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• 제12권6호
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• pp.592-599
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• 2010

In recent years, significant improvements have been made to the techniques used for analyzing satellite communication and attacking satellite systems. In 2003, a research team at Los Alamos National Laboratory, USA, demonstrated the ease with which civilian global positioning system (GPS) spoofing attacks can be implemented. They fed fake signals to the GPS receiver so that it operates as though it were located at a position different from its actual location. Moreover, Galileo in-orbit validation element A and Compass-M1 civilian codes in all available frequency bands were decoded in 2007 and 2009. These events indicate that cryptography should be used in addition to the coding technique for secure and authenticated satellite communication. In this study, we address this issue by using an authenticated key-exchange protocol to build a secure and authenticated communication channel for satellite communication. Our protocol uses identity-based cryptography. We also prove the security of our protocol in the extended Canetti-Krawczyk model, which is the strongest security model for authenticated key-exchange protocols, under the random oracle assumption and computational Diffie-Hellman assumption. In addition, our protocol helps achieve high efficiency in both communication and computation and thus improve security in satellite communication.

• 한국정보통신학회논문지
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• 제19권4호
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• pp.848-854
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• 2015

최근 데이터베이스 보안을 위한 다양한 암호화 방법이 제안되고 있다. 이러한 암호화 방법들은 사용자의 민감한 데이터를 효과적으로 보호할 수 있지만 데이터베이스 질의어에 대한 검색 성능이 저하된다. 본 논문에서는 이러한 단점을 보완하기 위하여 블룸필터에서의 선택적 요소 단위의 암호화 방식을 제안하였다. 그리고 다수의 질의어를 통하여 기존에 제안된 튜플 암호화 방식과 성능을 비교하였다. 결과적으로 민감한 정보에 대하여 요소 암호화 방법을 적용하고, 이에 대한 인덱스로서 블룸필터를 사용한 제안 방식이 기존에 제안된 방식보다 검색 시간이 매우 빠르게 나타남을 알 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.782-787
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• 2001

This paper is concerned with the global rupture of a nuclear reactor pressure vessel(RPV) in a severe accident. During the severe reactor accident of molten core, the temperature and the pressure in the nuclear reactor rise to a certain level depending on the initial and subsequent condition of a severe accident. While the rise of the temperature cause the thermal softening of RPV material, the rise of the internal pressure could cause failure of the RPV lower head. The global rupture of an RPV is simulated by finite element limit analysis for the collapse pressure and mode and this analysis results have been compared with a variation of the internal pressure of RPV. The finite element limit method is a systematic tool to secure the safety criteria of a nuclear reactor and to evaluate the in-vessel corium retention.