• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.4
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• pp.29-38
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• 2005

Because IEEE 802.11 has several security vulnerabilities, IEEE 802.11i was proposed and accepted. But IEEE 802.11i has much overhead for most of users for the web surfing. Besides not only node the authentication but also the packet authentication is needed to communicate. Although IEEE 802.11i uses TKIP(Temporal Key integrity Protocol) and CCMP(CTR with CBC-MAC Protocol), they have a lot of overheads. In this paper, Lightweight Packet Authentication(LIPA) is proposed. LIPA has less overhead and short delay so that it can be affordable for simple web-surfing which does not need stronger security. After comparing performances of LIPA with those of TKIP and CCMP, LIPA is more efficient than other schemes for transmitting packets.

• ALGAE
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• v.34 no.4
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• pp.289-301
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• 2019

Mixotrophy in marine organisms is an important aspect of ecology and evolution. The discovery of mixotrophic abilities in phototrophic dinoflagellates alters our understanding of the dynamics of red tides. In the phototrophic dinoflagellate genus Alexandrium, some species are mixotrophic, but others are exclusively autotrophic. There are differences in the ecological roles of autotrophic and mixotrophic Alexandrium in marine food webs. However, of the 34 known Alexandrium species, the mixotrophic ability of >20 species has yet to be explored. In this study, the mixotrophic capabilities of Alexandrium insuetum CCMP2082, Alexandrium mediterraneum CCMP3433, Alexandrium pacificum CCMP3434, Alexandrium tamutum ATSH1609, and Alexandrium margalefii CAWD10 were investigated by providing each species with 22 diverse prey items including bacterium-sized microbeads (1 ㎛), the cyanobacterium Synechococcus sp., algal prey species, and the ciliate Mesodinium rubrum. None of the 5 Alexandrium species fed on any of the prey items. These results increase the number of Alexandrium species lacking mixotrophic abilities to 9, compared to the 7 known mixotrophic Alexandrium species. Furthermore, the Alexandrium phylogenetic tree based on the large subunit ribosomal DNA contained 3 large clades, each of which had species with and without mixotrophic abilities. Thus, the acquisition or loss of mixotrophic abilities in Alexandrium might readily occur.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.11
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• pp.10-17
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• 1999

In this paper, CMOS IADC(Current-mode Analog-to-Digital Converter) which consists of only CMOS transistors is proposed. Each stages is made up 1.5-bit bit cells composed of CSH(Current-mode Sample-and-Hold) and CCMP(Current Comparator). The differential CSH which designed to eliminate CFT(Clock Feedthrough), to meet at least 9-bit resolution, is placed at the front-end of each bit cells, and each stages of bit cell ADSC (Analog-to-Digital Subconverter) is made up two latch CCMPs. With the HYUNDAI TEX>$0.65\mu\textrm{m}$ CMOS parameter, the ACAD simulation results show that the proposed IADC can be operated with 47 dB of SINAD(Signal to Noise- Plus-Distortion), 50dB(8-bit) of SNR(Signal-to-Noise) and 37.7 mW of power consumption for input signal of 100 KHz at 20 Ms/s.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.839-842
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• 2015

소형 모바일 IoT장비에서는 사양과 환경 등 많은 제약이 따르기 때문에 컴퓨터에서의 인터넷 보안을 똑같이 제공할 수 없다. 많은 제약 조건에도 불구하고 소형 모바일 IoT에서 보안을 적용할 수 있도록, 암/복호화 프로토콜을 제안한다. 현재 무선랜에서 사용하고 있는 암/복호화 프로토콜인 CCMP를 IoT 환경에 맞게 응용한 프로토콜 $CCMP^*$의 진행과정을 소개한다.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.591-594
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• 2005

This paper describes a design of AES-based CCM Protocol for IEEE 802.11i Wireless LAN Security. The CCMP core is designed with 128-bit data path and iterative structyre which uses 1 clock cycle per round operation. To maximize its performance, two AES cores are used, one is for counter mode for data confidentiality and the other is for CBC(Cipher Block Chaining) mode for authentication and data integrity. The S-box that requires the largest hardware in AES core is implemented using composite field arithmetic, and the gate count is reduced by about 23% compared with conventional LUT-based design. The CCMP core designed in Verilog-HDL has 35,013 gates, and the estimated throughput is about 768Mbps at 66-MHz clock frequency.

• ALGAE
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• v.23 no.1
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• pp.15-29
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• 2008

Many species in Gymnodiniales, which are unarmored dinoflagellates, are responsible for marine algal blooms and some of them have potent toxin in the cell. Their taxonomy has so far been well-defined, and several genera (e.g. Akashiwo, Gymnodinium, Karenia) have recently been re-described. In Korea, few works have been carried out on their taxonomical and molecular studies. This study focused on comparison of both morphological and molecular characteristics of five unarmored dinoflagellates on Korean coastal water: Akashiwo sanguinea, Cochlodinium polykrikoides, Gymnodinium catenatum, Gymnodinium impudicum and Karenia aureolum (=K. mikimotoi). Morphological characteristics observed here was in good accordance with the original descriptions of individual species. In addition, none of difference was found in morphological comparisons between the Korean and foreign strains. Furthermore, molecular analysis showed that the SSU rDNA sequences were generally identical according to each species. In some distinct features, A. sanguinea, which has generally the same morphological features, were divided into two groups: one was Korean isolates including European isolates, the other was American isolates. In the two groups, the nucleus was positioned differently: middle of the cells in the Korean isolates (GnSg02, GnSg03), near the epicone in American isolates (CCMP1593, CCMP1837). In addition, this was strongly supported by phylogenetic analysis, inferred from the SSU rDNA sequences. K. aureolum (GrAr01) was corresponded to European G. aureolum (=K. mikimotoi) in shape and position of nucleus, chloroplast, however, which is similar to K. digitata in view of having a finger-like sulcus. This was in good agreement with phylogenetic study of these species. G. catenatum have identical morphology except the ridge location, and their genotype of SSU rDNA was also identical to GenBank data of the same species. From this study, we found that the five Korean unarmored dinoflagellates are identical morphological characteristics and genotype to each species of foreign isolates.

• ALGAE
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• v.22 no.3
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• pp.147-152
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• 2007

We described two brownish freshwater Cryptomonas species, C. marssonii Skuja and C. pyrenoidifera Geitler as first records in Korea. The identification was based on light microscopy, scanning electron microscopy, and nuclear SSU rDNA sequences analysis. Cryptomonas marssonii is characterized by its sigmoid shape with a sharply pointed and dorsally curved antapex, dorso-ventrally flattened cell, two lateral plastids without pyrenoid, and its dimension of 18-25 μm in length and 8-13 μm in width. Cryptomonas pyrenoidifera is characterized by ovoid to elliptical shape with a partially twisted or rounded antapex, dorso-ventrally biconvex cell, lateral plastids with two pyrenoids, and the dimensions of 15-22 μm in length and 10-14 μm in width. Nuclear SSU rDNA sequences between C. marssonii WCK01 from Korea and CCAC0086 from Gernmay, and between C. pyrenoidifera WCK02 from Korea and CCMP152 from Australia were identical, respectively.

• ALGAE
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• v.29 no.2
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• pp.75-99
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• 2014

A small dinoflagellate, Ansanella granifera gen. et sp. nov., was isolated from estuarine and marine waters, and examined by light microscopy, scanning electron microscopy, and transmission electron microscopy. In addition, the identity of the sequences (3,663-bp product) of the small subunit (SSU), internal transcribed spacer (ITS) region (ITS1, 5.8S, ITS2), and D1-D3 large subunit (LSU) rDNA were determined. This newly isolated, thin-walled dinoflagellate has a type E eyespot and a single elongated apical vesicle, and it is closely related to species belonging to the family Suessiaceae. A. granifera has 10-14 horizontal rows of amphiesmal vesicles, comparable to Biecheleria spp. and Biecheleriopsis adriatica, but greater in number than in other species of the family Suessiaceae. Unlike Biecheleria spp. and B. adriatica, A. granifera has grana-like thylakoids. Further, A. granifera lacks a nuclear fibrous connective, which is present in B. adriatica. B. adriatica and A. granifera also show a morphological difference in the shape of the margin of the cingulum. In A. granifera, the cingular margin formed a zigzag line, and in B. adriatica a straight line, especially on the dorsal side of the cell. The episome is conical with a round apex, whereas the hyposome is trapezoidal. Cells growing photosynthetically are $10.0-15.0{\mu}m$ long and $8.5-12.4{\mu}m$ wide. The cingulum is descending, the two ends displaced about its own width. Cells of A. granifera contain 5-8 peripheral chloroplasts, stalked pyrenoids, and a pusule system, but lack nuclear envelope chambers, a nuclear fibrous connective, lamellar body, rhizocysts, and a peduncle. The main accessory pigment is peridinin. The SSU, ITS regions, and D1-D3 LSU rDNA sequences differ by 1.2-7.4%, >8.8%, and >2.5%, respectively, from those of the other known genera in the order Suessiales. Moreover, the SSU rDNA sequence differed by 1-2% from that of the three most closely related species, Polarella glacialis, Pelagodinium bei, and Protodinium simplex. In addition, the ITS1-5.8S-ITS2 rDNA sequence differed by 16-19% from that of the three most closely related species, Gymnodinium corii, Pr. simplex, and Pel. bei, and the LSU rDNA sequence differed by 3-4% from that of the three most closely related species, Protodinium sp. CCMP419, B. adriatica, and Gymnodinium sp. CCMP425. A. granifera had a 51-base pair fragment in domain D2 of the large subunit of ribosomal DNA, which is absent in the genus Biecheleria. In the phylogenetic tree based on the SSU and LSU sequences, A. granifera is located in the large clade of the family Suessiaceae, but it forms an independent clade.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.2.1-2
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• 2003

WLAN의 매체 특성상 AP beacon영역 내의 모든 STA들은 다른 STA의 송수신 데이터 내용에 접근할 수 있다. 따라서 상호 또는 그룹 간의 데이터프라이버시와 상호인증 서비스는 무선 랜의 중요한 이슈중의 하나이다. 무선랜을 통한 네트워크 접속 보안으로는 사용자와 AP 사이의 무선 접속구간 보안과 AP와 AS사이의 유선 구간 보안으로 정의되며, 상대적으로 취약한 무선 구간 보안이 초점이 된다. 현재 무선 구간 보안에는 WEP이 사용된다. 그러나 WEP 방식은 WEP 키와 IV 크기가 작고, 노출된 공유키를 사용하며, 암호 알고리즘(RC4)와 무결성 알고리즘(CRC-32)이 근본적으로 취약하다. 이러한 문제에 대한 해결 방법으로 IEEE 802.11i는 두 가지 접근 방식을 채택하였다. 하나는 WEP의 보안 문제점을 소프트웨어적으로 개선한 TKIP이고 다른 하나는 기존의 WEP과는 하드웨어적으로 상이한 AES을 기반으로 한 CCMP이다. 이 논문에서는 각 알고리즘에 대한 키의 흐름 및 그 안전성을 분석하였다. 이러한 방법을 통해 WEP 구조의 보안상의 취약점을 확인하고, TKIP이 WEP을 대체할 수 있을 만큼의 안전성을 갖는지를 검증한다. 또한 고려될 수 있는 공격 모델을 제시하고, 이에 대하여 알고리즘에 부가적으로 요구되는 보완점에 대해 논한다.

• Korean Journal of Environmental Biology
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• v.32 no.2
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• pp.129-137
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• 2014

In order to understand the Heterosigma akashiwo (Raphidophyceae) bloom, we investigated the cell division pattern of its strains under various physicochemical conditions from three different origin. Among the three tested strains, HYM06HA and NFHTS-AK-1, are belong to South Korea and CCMP452 strain was from USA. Interestingly among three strains, HYM06HA was established from the cyst in Korea. Our study results showed that these three strains were indistinguishable under various salinity and iron (Fe) conditions. All strains were survived at 10 to 40 psu and the growth patterns under different iron (Fe) concentrations were observed to be similar. The growth patterns under different N:P ratios and selenium (Se) concentrations led to classification of strains into Korean and USA strain. Briefly these results indicated that the growth pattern from different strains of H. akashiwo could be dominant using their salinity tolerance. Furthermore nutritional enhancer seemed to be different based on geographical origin.