• The KIPS Transactions:PartC
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• v.18C no.6
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• pp.389-396
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• 2011

Recently, researches on the shared authentication based on single sign-on have been actively performed so as to solve the problems of current service provider-centric and isolated Internet authentications, including low usability, high cost structure, and difficulty in privacy protection. In order for the shared authentication model, where the authentications of an authentication provider are shared by several Internet service providers, to be accepted in real Internet environment, trustworthiness among users, service providers, and authentication providers on the level of authentication assurance and the level of authentication information protection is necessarily required. This paper proposes a framework for trustworthy and privacy-protected shared authentication protocol based on the user-centric operation and open trust provider network. The proposed framework is differentiated from previous works in the points that it is able to provide interoperable shared authentication services on the basis of open trust infrastructure.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.495-502
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• 2000

In this study, the wind tunnel test for Kwangju World Cup Stadium with long span roof was carried out and its results were considered in the two roofs: one is the case of one roof, and the other is the case of two roofs which are identical. In this experiment, a 1/400-scale model was used. As a result of measuring wind pressure in the case of one roof and then two, when two roofs are set up, wind load for structural frame decreases by 35%, compared to that of one roof. These results show that the current criteria for wind loadings, which specify that wind pressure on the roof depends only on the altitude, have limitations for adoption, and a wind tunnel test is essential to design.

• Journal of Broadcast Engineering
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• v.1 no.1
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• pp.67-73
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• 1996

In general, the high quality audio coding(HQAC) has the structure of the convertional data compression techniques combined with moodels of human perception. The primary auditory characteristic applied to HQAC is the masking effect in the spectral domain. Therefore spectral techniques such as the subband coding or the transform coding are widely used[1][2]. However no effort has yet been made to apply the temporal masking effect and temporal redundancy removing method in HQAC. The audio data compression method proposed in this paper eliminates statistical and perceptual redundancies in both temporal and spectral domain. Transformed audio signal is divided into packets, which consist of 6 frames. A packet contains 1536 samples($256{\times}6$) :nd redundancies in packet reside in both temporal and spectral domain. Both redundancies are elminated at the same time in each packet. The psychoacoustic model has been improved to give more delicate results by taking into account temporal masking as well as fine spectral masking. For quantization, each packet is divided into subblocks designed to have an analogy with the nonlinear critical bands and to reflect the temporal auditory characteristics. Consequently, high quality of reconstructed audio is conserved at low bit-rates.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.45-52
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• 2016

One commercial package for magnetic analysis was used to apply repulsive forces of permanent magnetics to bicycle cushion system. Reliabilities of finite element analysis were acquired by comparing with those of experimental measurements. Equivalent spring stiffnesses corresponding to various sizes of magnetics were implemented into the bicycle dynamic model with three degree of freedom. Input force caused at front and rear wheels due to road unevenness was considered in the dynamic model. Dynamic behaviors were observed in terms of vertical displacements of the rider and the front reach as well as pitching displacement of the mass center when the bicycle ran over half-triangular bump. The methodology suggested in this paper by the finite element analysis and numerical model will be an useful tool for more accurate prediction of cushion design for any vehicle system if magnetic forces are utilized.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.85-95
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• 2021

Structure design sensitivity was evaluated using the orthogonal array experimental method for passive-type deck support frame (DSF) developed for float-over installation of the offshore plant. Moreover, approximation characteristics were also reviewed based on various meta-models. The minimum weight design of the DSF is significantly important for securing both maneuvering performance and buoyancy of a ship equipped with the DSF and guaranteeing structural design safety. The performance strength of the passive type DSF was evaluated through structure analysis based on the finite element method. The thickness of main structure members was applied to design factors, and output responses were considered structure weight and strength performances. Quantitative effects on the output responses for each design factor were evaluated using the orthogonal array experimental method and analysis of variance. The optimum design case was also identified from the orthogonal array experiment results. Various meta-models, such as Chebyshev orthogonal polynomial, Kriging, response surface method, and radial basis function-based neural network, were generated from the orthogonal array experiment results. The results of the orthogonal array experiment were validated using the meta-modeling results. It was found that the radial basis function-based neural network among the meta-models could approximate the design space of the passive type DSF with the highest accuracy.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.32 no.1
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• pp.4-7
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• 2023

Since the end of the 1990s, zirconia, which has been applied to dental prostheses, has been used in the form of coping or framework. The prostheses made in this way have been successfully used in the anterior teeth because they have no metal components as a structure. But in the posterior teeth, its use was limited due to the fracture or chipping of the veneering porcelain during the function. Later, as a solution to this shortcoming, a monolithic zirconia restoration was proposed in which a strong coping material was used in the form of a complete prosthesis. But, this resulted in some unesthetic results due to the characteristics of zirconia, which has excellent resistance to strong forces but is very white and opaque. However, now, due to technological advances in increasing the translucency of zirconia, it is possible to produce strong and esthetic zirconia restorations not only in the posterior region but also in the anterior region. In this article, the structural characteristics of various types of zirconia materials that have been developed so far, were discussed, and where the zirconia products actually in use belong to was explained.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.320-320
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• 2012

III-V 화합물 태양전지는 실리콘, CdTe, CIGS, 염료, 및 유기 등 다른 태양전지에 비해 1sun 상 30% 이상의 고효율을 갖고 있고 앞으로도 계속 증가할 수 있는 가능성을 갖고 있다. 그 이유는 직접천이형 밴드갭, 높은 이동도 등의 고성능 물질특성과 더불어 3족과 5족의 비율을 조절함으로써 같은 결정구조를 갖고 에너지 밴드갭이 다른 물질들을 만들기에 용의하여, 태양전지 스펙트럼의 넓은 영역을 흡수할 수 있는 장점이 있기 때문이다. 그러나, 셀자체의 물질이 실리콘에 비하여 고가이므로, 고성능이 요구되는 우주 인공위성등에 적용이 되었지만, 2000년대 이후로 집광에 적용가능한 태양전지의 연구를 거듭하여 2005년부터는 값싼 프레넬 렌즈를 이용하여 1sun에 비해 500배 해당하는 빛을 셀에 집광하여 보다 효율을 증가시킴으로써 지상발전용에도 적용가능한 셀을 형성하게 되었다. 더불어 태양전지의 효율을 증가시키기 위한 개선된 구조적 변화의 시도도 많이 이루어지고 있다. 최근 보고에 의하면 실리콘 태양전지의 표면에 texture 또는 나노 구조를 주어 높은 흡수율과 낮은 반사율을 갖게 함으로써 효율을 증가시키는 사례가 많아지고, III-V 화합물 태양전지도 texturing에 의해 증가된 효율을 발표한바 있다. 본 연구에서는 태양전지의 효율을 증가시키기 위하여 III-V 화합물 태양전지 표면에 micro-hole array texture 구조를 형성한 후 나노 particle을 이용한 나노 texture 구조를 형성하였다. Photo-lithography와 chemical wet etching으로 micro-hole array texture 구조를 형성하였으며 micro-hole의 직경은 $5{\sim}20{\mu}m$, hole과 hole의 간격은 $3{\sim}15{\mu}m$로 다양하게 변화를 주었다. 형성된 micro-hole array texture 구조위에 수십 nm 크기의 particle을 만들어 chemical wet etching으로 나노 texture 구조를 형성하였다. 태양전지 표면에 texture 구조가 있는 경우와 없는 경우에 각각 효율을 측정, 비교 분석하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.658-660
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• 2005

최근 인터넷의 성장과 CDMA등의 무선 통신의 활성화로 인하여 이동 중인 차량 내에서 다양한 정보를 사용하기 위한 기술이 개발 중이다. 본 논문에서는 차량 단말에 여러가지 텔레매틱스 서비스를 제공하기 위한 차량 단말, 텔레매틱스 서비스 서버, 텔레매틱스 컨텐츠 서버의 3단계 구조를 가지는 텔레매틱스 서비스 시스템을 제안한다. 제안하는 시스템은 차량 단말과 서비스 서버 사이의 통신 방법 및 서비스 서버 내의 서비스 응용이 다양한 컨텐츠를 제공하기 위한 프레임워크를 제공한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.122-127
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• 1999

In this paper, the power factor correction circuit using a parallel drive method is proposed so that the high power inverter air-conditioner with 3[hp] compressor motor may obtain the cost down and the improved performance. The adequate design porcedures are presented to reduce the material costs by eliminating the power factor imprving LC filter and derating output capacitor and inverter switches. Using the determined components. the proto-type circuit with 6[kW] power consumption is built and tested to verify the operation of the proposed circuit.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1031-1036
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• 2007

Torsional vibration analysis is necessary at design stage to ensure the reliability of a system particularly when the driven machine is a reciprocating compressor. This paper contains the results of torsional vibration analysis and fatigue strength evaluation for 540 kW compressor driving motor. Torsional vibration analysis showed that the $2^{nd}$ torsional mode of the entire shaft system has the possibility of resonance with the $14^{th}$ order excitation of compressor and twin line frequency of motor at operating speed. Therefore, the analyses were required to ensure the structural reliability of the motor. The fatigue strength was evaluated for the shaft and inner fans using the results of forced vibration analysis. It is concluded that the motor has sufficient fatigue strength under normal operating condition.