• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.4
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• pp.67-76
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• 2002

Kerberos is designed to provide strong authentication between client and application servers which are working in distributed network environment by using symmetric-key cryptography, and supposed to trust other systems of the realm. In this paper, we design an efficient and strong authentication mechanism by introducing the public/private-key to Kerberos. In the mechanism to make a system more secure, the value of the session key is changed everytime using MAC(message authentication code) algorithm with the long-term key for user-authentication and a random number exchanged through the public key. Also, we employ a mutual authentication method, which is used on challenge-response mechanism based on digital signatures, to improve trust between realms, and present a way of reducing the number of keys by simplifying authentication steps.

• Fire Science and Engineering
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• v.20 no.3 s.63
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• pp.35-41
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• 2006

In this study, we presented the problems in the insulation cover of 22.9kV transformer bushing through investigating actual conditions. After thermal stress applied to the insulation cover, deterioration patterns, thermogravimetric and infrared characteristics were analyzed, and the results were applied to the cause analysis of accidents and judgement of safety. The insulation covers are used to protect exposed terminals of transformer, but they had improper size and length. Therefore, they could not show efficient insulation function. In case that thermal stress of $150^{\circ}C$ was applied to the insulation covers, plastic insulation covers(A, B, D, E) damaged severely, whereas rubber insulation cover(C) showed normal shapes. In the result of thermogravimetric analysis, the thermal gravity of plastic covers(A) decreased about 33.3% at $307.8^{\circ}C\;to\;405.9^{\circ}C$. and he thermal gravity of rubber covers (C) decreased about 53.7% at $258.8^{\circ}C\;to\;32.9^{\circ}C$. In the result of FT-IR analysis, plastic covers showed peaks characteristic of $CH_2,\;CH_3$, C=O and C=C bonds, whereas rubber covers showed peaks characteristic of OH, $CH_2,\;CH_3$, C=O, C=N and C=C bonds.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.8 no.3
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• pp.49-62
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• 1998

본 논문은 객체 모델링 기법을 이용하여 다단계 보안 데이터베이스 응용에 대한 구조적 특징을 표현하기 위한 모델을 제시한다. 즉, 응용 영역에 대한 데이터와 보안 의미르 통합한다. 이는 응용 영역의 데이터에 대한 불법적 유출이나 수정을 방지하는 도구가 된다 . 개발한 도구를 기초로 한 구현 모델에서는 다단계 데이터베이스를 단일 보안등급 데이터베이스들로 분해한다. 인스턴스뿐만 아니라 스키마도 보호하며 속성값 다중 인스턴스화 기법을 이용하여 커버 스토리를 표현한다. 그리고 그 모델에서의 생성, 검색, 삭제, 그리고 갱신과 같은 연산 의미를 설명한다.

• Journal of the Korea Convergence Society
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• v.10 no.7
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• pp.149-154
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• 2019

This paper is to study the durability through structural analysis on the front undercover of SUV car for offroad. It was investigated which model became structurally best by analyzing three kinds of models which are similar to the configuration of undercover for the protection of the part under car body which has been used really. The models of undercover were designed through CATIA program and analyzed by using ANSYS program as three kinds of models A, B and C. Through the analysis results, model B was expressed to have the best durability as model B has the least equivalent stress and the longest fatigue life among three models. As the design data with the durability of undercover obtained on the basis of this study result are utilized, the esthetic sense can be shown by being grafted onto the machine or structure at real life.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.5
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• pp.195-200
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• 2021

Due to the development of video sharing platforms, the amount of video uploads is exploding. Such videos often include various types of music, among which cover songs are included. In order to protect the copyright of music, an algorithm to find the original song of the cover song is essential. However, it is not easy to find the original song because the cover song is a modification of the composition, speed and overall structure of the original song. So far, there is no known effective algorithm for searching the original song of the cover song. In this paper, we propose an algorithm for searching the original song of the cover song using the inflection points of the melody line. Inflection points represent the characteristic points of change in the melody sequence. The proposed algorithm compares the original song and the cover song using the sequence of inflection points for the representative phrase of the original song. Since the characteristics of the representative phrase are used, even if the cover song is a song made by modifying the overall composition of the song, the algorithm's search performance is excellent. Also, since the proposed algorithm uses only the features of the inflection point sequence, the memory usage is very low. The efficiency of the algorithm was verified through performance evaluation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.2
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• pp.90-96
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• 1985

The properties of plasma-enhanced CVD phosphorous silicate glass (PECVD PSG) for passivation layer are studied . Phosphorous contentration was analyzed with X-ray fluores-cence. As a result, PECVD PSG has a limiting phosphors concentration of about 8 mole%. Curves relating to etcll rate, infrared absorption ratio, and sheet resistivity were adapted to monitor phosphorous concentration indirectly Dielectric properties, step coverage, crack resistance, and gettering effect are discussed in both of atmospheric pressure CVD (APCVO) and PECVD oxide. PECVD SiO2 film have density of about 2.4 g/㎤ at deposition rate of 450$\AA$/min, refractive index of about 1.53, and breakdown at fields of II-13 MV/cm. Crack resistance of PECVD oxide is greater than APCVD oxide. PECVD PSG films contained with 2 mole % phosphorous show good step coverage and gettering ability. The obtained results show more advantages in PECVD PSG than in APCVD PSG for device passivation.

• Journal of Korea Multimedia Society
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• v.8 no.3
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• pp.379-388
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• 2005

Image steganography Is a secret communication scheme to transmit a secret message, which is embedded into an image. The original image and the embedded image are called the cover image and the stego image, respectively. In other words, a sender embeds a secret message into a cover image and transmits a stego image to a receiver, while the receiver takes the stego image, extracts the message from it, and reads the message. General requirements for steganography are great capacity of secret messages, imperceptibility of stego images, and confidentiality between a sender and a receiver. In this paper, we propose a method for being satisfied with three requirements. In order to hide a secret message into a cover image safely, we use a difference value of two consecutive pixels and a secret quantization range. The former is used for the imperceptibility and the latter for the confidentiality. Furthermore, the number of insertion bits is changed according to the difference value for the imperceptibility. Through experiments, we have shown that our method is more good quality of stego images than many other related methods and increases the amount o( message insertion by performing dual insertion processing for some pixels.

• Research in Community and Public Health Nursing
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• v.8 no.2
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• pp.403-415
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• 1997

이 논문은 지난 10년간(1986-1995)의 영국의 사건강보험(private health insurance) 시장의 전반적 추이를 관찰, 국민 의료 써비스(National Health Service)와의 관계 및 역할 변화를 고찰한 것이다. 가장 대표적인 PMI(private medical Insurance)와 PHI(permanent health Insurance), LTCI(long term care insurance)를 집중 연구하였으나 지면관계상 PMI를 중점적으로 다루고 PHI나 LTCI는 간략히 소개하였으며 관련도표는 모두 생략하였다. 영국의 사건강보험 시장은 1990년대 초의 정체기를 거친후 이제 서서히 가시적인 성장을 보이고 있다. 많은 영국 국민들은 정부가 기본적인 복지혜택 외에는 더 이상의 치료와 미래 간호를 보장할 수 없다는 사실을 이해하고 있으나 아직 대부분은 어떤 형태로든 NHS 외의 보호장치를 가지고 있지 못하다. 따라서 영국민의 사건강보험에 대한 관심은 점차 고조되고 있는 것이 현실이다. 사건강보험 시장의 성장은 몇가지 중요한 요소에 좌우된다 첫째, NHS의 capacity이다. 달리 말하면, NHS에 대한 정부의 각종 정책과 태도는 시장에 직접적인 영향을 미친다. 둘째, 경제성장은 상당히 결정적인 요소이다. 1990년대 초의 침체에서 이미 보았듯이 경기후퇴와 그와 동반된 높은 실업은 사적 의료써비스의 구매력을 감소시킨다. 셋째, 시장을 극대하려는 보험회사의 노력 또한 배놓을 수 없는 중요한 요소이다. 새로운 구매자를 위해서 또 시장에서의 치열한 경쟁에서 살아 남기 위해서 보험회사들은 폭넓은 범위의 상품을 개발하고 노동자들을 위한 값이 저렴한 상품들을 소개시켜 왔다. 비록 이런 종류의 저렴한 상품들은 커버하는 범위가 불충분하지만 총 인구의 보험 가입을 증가시킨다. 현 상황에서 PMI는 NHS에 대한 대안이 되지 못하고 단지 부분적 대용책일 뿐이다. 또한 시장을 극대시키려는 정부의 노력에도 불구하고 극소수의 사람들만이 PHI에 커버되고 있다. LTCI는 너무 비싸 지극히 부자들만이 구매할 수 있을 뿐, 평균임금 또는 그 이하의 사람들은 보험료를 감당할 수 없다. 한편. 영국의 사건강보험 시장에 대한 전망 또한 복합적이다. 즉 PMI 부문은 서서히 성장, PHI 부문은 계속적으로 꾸준히 증가, LTCI 부문은 제한적이기는 하나 발전하리라 보는 것이다. 따라서 미래시장을 예견하는 것은 그리 쉽지 아니하다. 결론적으로 영국국민은 질병, 또는 치료가 필요한 경우 전적으로 NHS에 의존하고 있으며 현재의 사건강보험은 다양한 질병위험에 대한 보호를 제공하기보다는 단순히 부가적인 혜택에 지나지 않을 뿐이다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.2
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• pp.109-114
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• 2021

As various users increase in a network environment, it is difficult to protect sensitive and confidential information transmitted and received from attackers. Concealing bitwise secret data in an image using the LSB technique can be very vulnerable to attack. To solve this problem, a hybrid method that combines encryption and information hiding is used. Therefore, an effective method for users to securely protect secret messages and implement secret communication is required. A new approach is needed to improve security and imperceptibility to ensure image quality. In this paper, I propose an LSB steganography technique that hides Hangul messages in a cover image based on MSB and LSB. At this time, after separating Hangul into chosung, jungsung and jongsung, the secret message is applied with Exclusive-OR or Exclusive-NOR operation depending on the selected MSB. In addition, the calculated secret data is hidden in the LSB n bits of the cover image converted by Fibonacci technique. PSNR was used to confirm the effectiveness of the applied results. It was confirmed 41.517(dB) which is suitable as an acceptable result.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.79-84
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• 2015

Steganography is to conceal the existence of secrete data itself. The Emulab is a framework to provide real systems and network topology that can set up at anytime by researchers. In this paper, we show that steganography techniques can be applied in the Emulab environment. Steganography methods are evaluated on a standalone and sharing environments using the color bitmap images. The cover image is divided into RGB channels and then embedded the secret data at each client. The experimental results demonstrate that execution time is better in client/server environment as cover image size is increasing.