• Proceedings of the Korea Information Processing Society Conference
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• 2003.11c
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• pp.2033-2036
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• 2003

최근에 공공장소에서의 보다 안정적이고 고속의 무선 인터넷 접속에 대한 욕구가 커지면서 무선랜에 대한 수요가 많아지고 있고, 유무선 사업자들은 무선랜 시장을 선점하기 위해서 서비스를 서두르고 있다. 이와 같은 무선랜환경에서 안전하게 사용자를 인증하고 서비스를 제공하기 위한 표준으로 802.1aa 와 802.11i 가 있다. 이와 같은 802.1aa 와 802.11i를 지원하는 액세스포인트를 위해서는 두 표준을 지원할 수 있는 라디우스 클라이언트가 필요하다. 본 논문에서는 위의 액세스포인트가 라디우스 프로토콜을 사용하여 무선단말 사용자를 인증시켜 주고 WEP(Wired Eaulvalent Privacy)을 위한 키를 교환할 수 있는 라디우스 클라이언트를 설계하고 구현하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.371-373
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• 2003

최근에 공공장소에서의 보다 안정적이고 고속의 무선 인터넷 접속에 대한 욕구가 커지면서 무선랜에 대한 수요가 많아지고 있고, 유무선 사업자들은 무선랜 시장을 선점하기 위해서 서비스를 서두르고 있다. 이와 같은 무선랜환경에서 안전하게 사용자를 인증하고 서비스를 제공하기 위한 표준으로 802.laa와 802.11i가 있다. 이와 같은 802.laa와 802.11i를 지원하는 액세스포인트를 위해서는 두 표준을 지원할 수 있는 라디우스 클라이언트가 필요하다. 본 논문에서는 위의 액세스포인트가 라디우스 프로토콜을 사용하여 무선단말 사용자를 인증시켜 주고 WEP(Wired Equivalent Privacy)을 위한 키를 교환할 수 있는 라디우스 클라이언트를 설계하고 구현하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.286-288
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• 2004

무선 통신의 발달로 언제 어디서나 누구와도 통신이 자유롭게 되었다 하지만, 무선 통신을 사용하게 됨으로써 통신 사용자와 액세스 포인트, 액세스 포인트와 서버(Server)가 통신을 할 경우 유선 네트워크와는 다른 인증 방식이 요구되었다. 무선 네트워크에서 사용자 인증을 위해 801.x EAP, SSID, CHAP 및 WEP를 이용한 다양한 인증 방식이 사용되고 있다. 본 논문에서는 사용자를 안전하게 인증할 수 있는 효율적인 인증 방법을 제안한다. 절기서는 기존의 PPP CHAP을 수정하여 인증 서버와 사용자간의 상호 인증을 할 수 있도록 했다. 또한 강한 일-방향 해시 함수(Strength One-Way Hash Function)을 사용하여 생성된 결과 값을 일회용 패스워드(One Time Password:OTP)로 사용하여 재공격(Reply Attack)을 방지했다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1086-1089
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• 2009

UPnP(Universal Plug and Play) 홈네트워크에서 무선랜은 위치에 상관없이 쉽게 설치하여 사용할 수 있어 사용자에게 편의성을 제공 하지만, AP(Access Point)는 해킹을 통한 MAC 주소 및 SSID(Service Set Identifier), WEP(Wired Equivalent Privacy)의 암호를 쉽게 알 수 있어 보안에 취약하다. 또한 UPnP 는 TCP/IP 를 사용하는 인터넷 표준과 기술을 기반으로 하고 있고 HTTP, UDP, SSDP, GENA 등의 표준 프로토콜을 사용하기에 보안 대책에 취약점을 가지고 있다. 본 논문에서는 댁외에서 UPnP 홈네트워크에 사용되는 AP 를 해킹하고, 해킹한 AP 정보를 이용하여 UPnP 홈네트워크의 디바이스 정보를 취득하고, 댁내 컨트롤 포인트(Control Point)를 해킹하여 MAC 주소 및 IP 주소를 댁외 컨트롤 포인터로 변조하여 UPnP 홈네트워크 디바이스를 제어하는 실험으로 UPnP 홈네트워크 보안의 취약점에 대해 분석한다.

• Structural Engineering and Mechanics
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• v.63 no.3
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• pp.347-359
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• 2017

Blast resistant gates are required to be lightweight and able to mitigate extreme loading effect. This may be achieved through innovative design of a gate and its supporting frame. The first is well covered in literature while the latter is often overlooked. The design of supporting frame depends mainly on the boundary conditions and corresponding reaction forces. The later states the novelty and the aim of this paper, namely, the analysis of reaction forces in supporting structure of rectangular steel gates subjected to "far-field explosions". Flat steel plate was used as simplified gate structure, since the focus was on reaction forces rather than behaviour of gate itself. The analyses include both static and dynamic cases using analytical and numerical methods to emphasize the difference between both approaches, and provide some practical hints for engineers. The comprehensive study of reaction forces presented here, cover four different boundary conditions and three length to width ratios. Moreover, the effect of explosive charge and stand-off distance on reaction forces was also covered. The analyses presented can be used for a future design of a possible "blast absorbing supporting frame" which will increase the absorbing properties of the gate. This in return, may lead to lighter and more operational blast resistant gates.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.708-711
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• 2008

Wireless Lan is rapidly increased, but now most of wireless lan are being used to cover physical boundary of wired tan. If Users who communicate each other send cipher data, other users can not change or interrupt and the data is guaranteed for integrity. Otherwise, if user lose key for any reason, the data is not guaranteed for integrity. So it is important to control and manage to offer key. This Thesis examine problems of using existing wireless lan. Moreover, for users using small wireless lan, this offers installing server for controling and sharing and improves security problems.

• Structural Engineering and Mechanics
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• v.87 no.3
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• pp.273-282
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• 2023

Concrete construction, one of the oldest building practices, is commonly used in all parts of the world. Concrete is the primary building material for both residential and commercial constructions. The challenge of protecting the buildings, hence nation, against the attack of terrorism has raised the importance to explore the understanding of building materials against the explosion. In this research, a security check-post (reinforced concrete frame filled with plain cement concrete) has been chosen to study the behavior of structural elements under blast loading. Eight nitroglycerines-based dynamite blasts with varying amounts of explosive charge, up to 17 kg weight has been carried out at various scale distances. Pressure and acceleration time history records are measured using blast measuring instruments. Security check post after being exposed by explosive loading are photographed to view cracking/failure patterns on the structural elements. It is noted that with the increase of quantity of explosive, the dimensions of spalling and crack patterns increase on the front panels. Simple empirical analyses are conducted using ConWep and other design manuals such as UFC 3-340-02 (2008) and AASTP-1 (2010) for the purpose of comparison of blast parameters with the experimental records. The results of experimental workings are also compared with earlier researchers to check the compatibility of developed equations. It is believed that the current study presents the simple and preliminary procedure for calculating the air blast and ground shock parameters on the structures exposed to blast explosion.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.1
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• pp.67-74
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• 2008

As wireless network market is increasing rapidly, the biggest issue is to transfer safe data and to authenticate users. This paper proposes ECbA(Elliptic Curve based Authentication) which consists of the mutual authentication mechanism that users can ascertain the identity of an authentication server and the user authentication mechanism that an authentication server can make sure users' identity, by using Elliptic Curve algorithms. The proposed ECbA system diminishes the message quantity and the execution time by using the small elliptic curve algorithm with the small key length in authentication. In addition, as this paper reduces the authentication steps of existing EAP_TLS into 6 authentication steps, the communication cost and mutual authentication time can be saved. As this paper distributes new keys, whenever authenticating users by using key exchange mechanism, it provides safe encryption communication and prevents DoS attack by controlling the users authentication request by authentication server.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.396-401
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• 2006

The objective of this study was to investigate the antitumor activity of suspension cultures of tea callus cells grown in the presence of different concentrations of the growth regulator 2,4-dichlorophenoxy acetic acid (2,4-D) with or without light irradiation. The methanol and ethanol extracts of precipitated cells (MEP, EEP) exhibited stronger inhibitory effects on the growth of tumor cell lines than the water extract of precipitated cells (WEP) or the supernatant Compared to culture under dark conditions, exposure to light irradiation led to significantly higher antitumor activity. The MEP from light irradiated cells at $250{\mu}g/mL$ with 2.0mg/L 2,4-D displayed more than 64% growth inhibition of HEP-2 cells, whereas normal cells showed less than 25% growth inhibition. The some fractions of MEP obtained from Diaion HP-20 column chromatography displayed the majority of inhibitory activity against the HEP-2 cell line. These results show that 2,4-D, and light stimulated the synthesis of antitumor compounds.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1983-1989
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• 2012

The IEEE 802.1x standard provides an architectural framework which can be used various authentication methods. But, IEEE 802.1x also has vulnerabilities about the DoS(Denial of Service), the session hijacking and the MiM(Man in the Middle) attack due to caused by structural of authentication protocol. In this paper, we propose a WLAN system which can offer safety communication by complement of IEEE 802.1x vulnerabilities. The WLAN system accomplishes mutual authentications between authentication servers, clients and the AP using PKI and prevents an illegal user from intervening in communication to disguise oneself as a client, the AP or authentication servers. Also, we guarantee the safety of the communication by the Dynamic WEP key distribution between clients and the AP.