• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.288-290
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• 1999

현재 국내에서는 암호이용에 대한 법 제정을 가지고 많은 문제들이 제기되고 있다. 일반인에게 암호의 사용은 피상적이지만, 일부 선진국에서는 전자상거래 및 인터넷에서의 암호사용에 대하여 구체화시켜 실행하는 단계에 이르고 있다. 그러나, 이러한 암호 선진국에 있어서도 암호의 양면성, 즉 암호의 기밀성을 통한 개인정보와 기업정보 등을 포함하는 데이터의 보호와 범죄의 은닉에 사용될 수 있다는 문제를 가지고 있으며, 이에 대한 해결책으로 키 복구 방법을 사용하고 있다. 그런, 키 복구 방법은 개인의 인권 침해라는 새로운 문제를 대두시켰으며, 암호선진국들은 인권보호단체와 민간단체 그리고 기업의 반발에 의하여 키 복구 방법에 대한 새로운 서비스를 제공하고 있다. 국내에서도 연구 및 개발은 미비하지만 키 복구로 인하여 암호이용에 대한 법 제정이 지연될 정도로 전자상거래에 있어서, 그 비중이 크다고 할 수 있다. 본 논문에서는 키 복구 서비스를 사용하면서, 개인의 인권을 보호할 수 있는 키 복구 시스템을 소개한다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.312-314
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• 1999

키복구는 암호화 제품의 사용자가 암호화키를 분실하여 데이터를 복호화할 수 없을 때 데이터를 복구하거나 수사기관등이 합법적인 절차로 암호화된 데이터를 복호화하기 위한 수단이다. 정보보호의 중요성에 대한 인식이 확대되어 앞으로 많은 종류의 암호화 제품이 개발될 것으로 예상되기 때문에 다양한 키복구 기술의 개발과 키복구 기술가느이 호환성의 해결이 시급한 실정이다. 본고에서는 공개키 방식에 기반을 둔 전자상거래와 전자정부등에서 채택할 수 있는 인캡슐레이션 키복구 기술과 이를 위한 절차에 관하여 논한다. 공개키기반구조에서 키복구는 사용자와 법집행기관 모두의 요구를 충족시켜야 한다. 키복구기관을 인증관리센터의 관리하에 두고 인증관리센터가 인증하는 키복구기관의 공개키를 이용하여 키복구필드를 생성하는 인캡슐레이션 기술을 사용함으로서 사용자는 자신이 직접 세션키를 제어할 수 있는 장점이 있고 법집행기관도 필요한 경우에 언제나 사용자의 세？키를 복호화할수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.274-277
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• 2008

Rekeying is the process of changing the encryption key of an ongoing communication. The main objective is to limit the amount of data encrypted with the same key. The IEEE 802.11 standard defines the Wired Equivalent Privacy, or WEP, encapsulation of 802.11 data frames. MAC at sender encrypts the payload (frame body and CRC) of each 802.11 frame before transmission using RC4 stream cipher. MAC at receiver decrypts and passes data to higher level protocol. WEP uses symmetric key stream cipher (RC4) where same key will be used for data encryption and decryption at the sender and the receiver. WEP is not promising with the advancement of the wireless technology existing today. We propose to use the existing information to define the security attributes. This will eliminate the steps that regenerated keys have to be sent to each other over certain period. The rekeying scheme is according to the number of bytes transmitted. Therefore, even the attacker has recorded the packets, it will be insufficient information and time for the attacker to launch the attacks as the key is not deterministic. We develop a packet simulation software for packet transmission and simulate our propose scheme. From the simulation, our propose scheme will overcome the weak WEP key attack and provide an alternative solution to wireless packet transmission. Besides that, our solution appears to be a software approach where only driver updates are needed for the wireless client and server.

• BMB Reports
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• v.44 no.2
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• pp.87-95
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• 2011

Enzymatic catalysis has been pursued extensively in a wide range of important chemical processes for their unparalleled selectivity and mild reaction conditions. However, enzymes are usually costly and easy to inactivate in their free forms. Immobilization is the key to optimizing the in-service performance of an enzyme in industrial processes, particularly in the field of non-aqueous phase catalysis. Since the immobilization process for enzymes will inevitably result in some loss of activity, improving the activity retention of the immobilized enzyme is critical. To some extent, the performance of an immobilized enzyme is mainly governed by the supports used for immobilization, thus it is important to fully understand the properties of supporting materials and immobilization processes. In recent years, there has been growing concern in using polymeric materials as supports for their good mechanical and easily adjustable properties. Furthermore, a great many work has been done in order to improve the activity retention and stabilities of immobilized enzymes. Some introduce a spacer arm onto the support surface to improve the enzyme mobility. The support surface is also modified towards biocompatibility to reduce non-biospecific interactions between the enzyme and support. Besides, natural materials can be used directly as supporting materials owning to their inert and biocompatible properties. This review is focused on recent advances in using polymeric materials as hosts for lipase immobilization by two different methods, surface attachment and encapsulation. Polymeric materials of different forms, such as particles, membranes and nanofibers, are discussed in detail. The prospective applications of immobilized enzymes, especially the enzyme-immobilized membrane bioreactors (EMBR) are also discussed.

• Food Science of Animal Resources
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• v.36 no.2
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• pp.267-274
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• 2016

The purposes of this study were to investigate the impacts of concentration levels of whey protein isolate (WPI) and inulin on the formation and physicochemical properties of WPI/inulin nano complexes and to evaluate their potential prebiotic effects. WPI/inulin nano complexes were produced using the internal gelation method. Transmission electron microscopy (TEM) and particle size analyzer were used to assess the morphological and physicochemical characterizations of nano complexes, respectively. The encapsulation efficiency of resveratrol in nano complexes was studied using HPLC while the potential prebiotic effects were investigated by measuring the viability of probiotics. In TEM micrographs, the globular forms of nano complexes in the range of 10 and 100 nm were successfully manufactured. An increase in WPI concentration level from 1 to 3% (w/v) resulted in a significant (p<0.05) decrease in the size of nano complexs while inulin concentration level did not affect the size of nano complexes. The polydispersity index of nano complexes was below 0.3 in all cases while the zeta-potential values in the range of -2 and -12 mV were observed. The encapsulation efficiency of resveratrol was significantly (p<0.05) increased as WPI and inulin concentration levels were increased from 1 to 3% (w/v). During incubation at 37℃ for 24 h, WPI/inulin nano complexes exhibited similar viability of probiotics with free inulin and had significantly (p<0.05) higher viability than negative control. In conclusions, WPI and inulin concentration levels were key factors affecting the physicochemical properties of WPI/inulin nano complexes and had potential prebiotic effect.

• Journal of Pharmaceutical Investigation
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• v.38 no.2
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• pp.99-104
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• 2008

PLGA micro/nano particles encapsulating ranitidine as a hydrophilic model drug were prepared by the double-emulsion solvent evaporation method. Surface morphology investigation by scanning electron microscope (SEM) showed that the emulsification by sonication could produce nanoparticles, whereas microparticles were prepared using high speed homogenizer. Moreover, while nanohalf-shell structure instead of spherical nanoparticle could be produced by adding poloxamer into oil phase (MC) with PLGA 504H, the addition of poloxamer didn't change particle shape in case of PLGA 502H. On the other hand, microparticle with poloxamer had more surface pores than those without poloxamer. The size and polydispersity (PDI) of particles were determined by particle size analyzer. Effective diameters of particles were in the range of $400{\sim}800\;nm$ and $1200{\sim}3300\;nm$ in case of nanoparticles and microparticles, respectively. Encapsulation efficiencies were in the range of $1.2{\sim}2.9%$. The addition of poloxamer produced the particles with higher encapsulation efficiency. In vitro release study in phosphate buffer (pH 7.4) at $37^{\circ}C$ showed common large initial burst release. However, the relative slower release profile could be observed in case of microparticles. Poloxamer addition increased the release rate, which was thought to be related to the increased surface area of particles.

• Journal of Animal Science and Technology
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• v.63 no.5
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• pp.1182-1193
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• 2021

The aims of this study were to develop a milk protein-based probiotic delivery system using a modified rennet-induced gelation method and to determine how the skim milk powder concentration level and pH, which can affect the rennet-induced intra- and inter-molecular association of milk proteins, affect the physicochemical properties of the probiotic delivery systems, such as the particle size, size distribution, encapsulation efficiency, and viability of probiotics in simulated gastrointestinal tract. To prepare a milk protein-based delivery system, skim milk powder was used as a source of milk proteins with various concentration levels from 3 to 10% (w/w) and rennet was added to skim milk solutions followed by adjustment of pH from 5.4 or 6.2. Lactobacillus rhamnosus GG was used as a probiotic culture. In confocal laser scanning microscopic images, globular particles with a size ranging from 10 ㎛ to 20 ㎛ were observed, indicating that milk protein-based probiotic delivery systems were successfully created. When the skim milk powder concentration was increased from 3 to 10% (w/w), the size of the delivery system was significantly (p < 0.05) increased from 27.5 to 44.4 ㎛, while a significant (p < 0.05) increase in size from 26.3 to 34.5 ㎛ was observed as the pH was increased from 5.4 to 6.4. An increase in skim milk powder concentration level and a decrease in pH led to a significant (p < 0.05) increase in the encapsulation efficiency of probiotics. The viability of probiotics in a simulated stomach condition was increased when probiotics were encapsulated in milk protein-based delivery systems. An increase in the skim milk powder concentration and a decrease in pH resulted in an increase in the viability of probiotics in simulated stomach conditions. It was concluded that the protein content by modulating skim milk powder concentration level and pH were the key manufacturing variables affecting the physicochemical properties of milk protein-based probiotic delivery systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1819-1831
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• 2018

This paper focuses on a header compression method for the Authentication Header (AH) and Encapsulation Security Payload (ESP) for application to 6LoWPAN. Based on the context, an extendible compression method is developed by analysing each field of the AH and ESP. The method is carried out by resetting the AH and ESP header compression formats, adding a MOD field, and setting different working modes. Authentication, encryption, and a mixture of certification and encryption are provided as flexible options. In addition, the value of the original IPv6 extensible header ID (EID) field can be retained, while the number of occupied NHC_ID values can be decreased for future extendibility. The experimental results show the feasibility and validity of the current compression method. By comparison with other solutions, the new mechanism is demonstrated to be advantageous in terms of compression ratio, flexibility and extendibility.

• Review of KIISC
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• v.16 no.3
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• pp.55-62
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• 2006

인터넷을 이용한 생활 패턴의 변화와 정보의 공유가 점차 이동 망과 무선망을 통해 확장되어, 이제는 유 무선의 경계가 없는 통신환경에서 살게 되었다. 이와 같은 접속환경의 변화와 확장은 더욱 네트워크 계층에서의 보안을 필요하게 만들었고, 이를 제공하는 IPSec은 네트워크 계층에서 IP 데이터 그램에 대한 인증, 무결성, 기밀성을 제공해 주는 표준 프로토콜로써 AH(Authentication Header), ESP(Encapsulation Security Payload), IKE(Internet Key Exchange)로 구성되며, 향후 통신의 발달과 함께 연구의 중요성이 부각되고 있다. 이 중에서 IKE는 IPSec에서 사용하는 보안연계(SA)를 자동으로 설정하는 기능을 가지고 있으며, 상호 인증 및 키 교환을 하는 하이브리드 프로토콜이다. IKEv1은 ISAKMP, DOI, SKEME등으로 구성되어 있다. 그러나 IKEv1은 상호호환성이 부족하기 때문에 구현이 용이하지 않으며, 서비스 거부 공격에 취약한 구조로 되어있다. IKEv2는 이러한 단점을 보안하기 위해 출현하였다. 본 논문에서는 IKEv2 설계시 요구사항에 대하여 알아보고, 그 설계를 기반으로 구현하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.616-619
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• 2005

OLED display are extremely sensitive to water and oxygen. Developing a thin film encapsulation for this technology has for a long time been elusive. Vitex has developed a multilayer barrier consisting of alternating inorganic and organic layers which can meet the requirements for a successful protection for such displays. In this paper we will discuss the basic process, the model, the results on top and bottom emission OLED displays as well as the application of Barix layers on plastic to create flexible OLED displays. We will show that for displays all the requirement for the telecommunication industry can be met and that the we can scale up to a mass manufacturing process.