• Analytical Science and Technology
• /
• v.14 no.6
• /
• pp.510-515
• /
• 2001

There has been an increasing need for analytical methods of dissolved total iron (tFe) that are highly sensitive, rapid, inexpensive and simple for environmental samples. A sensitive flow injection analysis (FIA) method for determining the concentration of tFe in environmental samples was developed. The proposed method required 10 minutes and only $500{\mu}L$ of sample for and analysis. The standard deviation was 5.0% at $0.5{\mu}gL^{-1}$ (n=6), and the detection limit was $0.075{\mu}gL^{-1}$. The developed method was applied to environmental samples such as tap water, mineral water, rain, snow and cloud water. Since this FIA system was free form interferences of coexisting ions commonly found in samples, sub-${\mu}gL^{-1}$ level of tFe could be easily determined without further preconcentration and separation.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.1508-1509
• /
• 2007

본 논문에서는 TSMC 0.18um공정을 이용한 무선통신 수신기용 직접변환 방식의 Double Balanced Mixer를 설계 하였다. 제안된 mixer는 current bleeding기법과 내부에 인덕터를 추가하여 기존의 Gilbert Cell구조의 mixer에 비해 변환 이득과 Flicker Noise특성을 향상 시켰다. 모의실험결과 2.45GHz에서 11dB의 변환이득을 나타내었으며 Flicker Noise의 corner frequency는 510kHz이고 이때 잡음특성은 10.8dB이다. 이 회로의 동작전압은 1.8V이며 소모 전력은 8.8mW이다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10a
• /
• pp.505-510
• /
• 2006

This paper presents an improved algorithm for constructing the city Voronoi diagram under the Euclidean metric given a transportation network consisting of roads having a constant number of speeds and orientations. The algorithm applies the continuous Dijkstra paradigm and its efficiency follows from new geometric insights that are first observed in this paper.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10a
• /
• pp.508-510
• /
• 2001

본 XSLT 처리기는 객체모델링 기법인 UML을 기반으로 설계하였고 핵심적인 부분은 XSL 스타일 시트를 HTML 패스/스타일로부터 구성해 내는 것이다 즉 문서 작성자는 XML문서를 작성하고 파싱하여 패스 테이블을 형성하고 이 패스 테이블에 작성자는 HTML패스/스타일을 추가한다. 이를 통해 XSL의 복잡한 스타일에 대한 고려없이 문서구조와 정보에 집중하여 견고한 문서를 만들 수 있다. 즉 구조 문서인 XML과 콘텐츠 타인의 대중적인 문서형인 HTML을 이용함으로써 적은 비용으로 다양한 문서 스타일을 구성할 수 있게 하여 XML 기술을 쉽게 보급시키며 컴포넌트 제작을 통해 다른 산업영역 문서교환에서 활용할 수 있다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.10c
• /
• pp.508-510
• /
• 2002

기존 단일 침입탐지시스템의 단점을 해결하기 위한 노력으로 분산 침입탐지시스템에 관한 많은 연구가 진행중이다. 분산 침입탐지시스템은 다수의 침입탐지 에이전트들의 협력을 통해 침입을 판정하는 시스템으로, 에이전트간에 데이터의 전송이 요구된다. 더욱이 이들 데이터는 침입을 판정하기 위한 중요한 자료로, 데이터의 보안은 필수적이다. 하지만 지금까지의 대부분의 시스템들에서는 이 부분에 대한 해결책이 아직 미비한 상태이다. 본 연구에서는 분산 침입탐지 시스템의 성능 저하를 최소화하면서 전송 데이터를 보안하기 위한 새로운 키 관리 시스템을 제안하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2015.04a
• /
• pp.508-510
• /
• 2015

2014년을 기준으로 안드로이드 OS기반 태블릿이 전체 태블릿 시장의 67.4%를 차지하고 있고, 스마트폰은 약 80%에 육박하는 시장 점유율을 가지고 있으므로 스마트폰 사용자 5명 중 4명은 안드로이드 스마트폰을 사용한다. 스마트폰이 가진 편리성으로 인해 급속도로 확산되고 있는 스마트폰 중 특허 안드로이드 환경의 스마트폰의 보안 취약점을 이용한 보안사고가 꾸준히 증가하고 있다. 스마트폰에는 주소록, SMS, 위치 정보 등의 많은 개인정보들이 담겨 있는데, 스마트폰이 가지고 있는 다양한 종류의 보안 취약점을 이용하여 개인 정보를 갈취하고 악용하는 등의 악의적인 목적의 공격들이 끊임없이 발생하고 있다. 따라서 본 논문은 개인정보의 유출을 막기 위한 다양한 보안 기법에 대해 살펴보고자 한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2001.04a
• /
• pp.507-510
• /
• 2001

HTTP/1.1 standard reduces latencies and overhead from closing and re-establishing connections by supporting persistent connections as a default, which encourage multiple transfers of objects over one connection. HTTP/1.1, however, does not define explicitly connection-closing time but specifies a certain fixed holding time model. This model may induce wasting server's resource when server maintains conn ection with the idle-state client that requests no data for a certain time. This paper proposes the mechanism of a heuristic connection management supported by the client-side under persistent HTTP, in addition to HTTP/1.1's fixed holding time model on server-side. The client exploits the tag information within transferred HTML page so that decides connection-closing time. As a result, the mechanism allows server to use server's resource more efficiently without server's efforts.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.506-510
• /
• 2008

Ramjets are capable of much higher specific impulse than liquid rocket engines for high speed flight in the atmosphere. Ramjets, however, cannot generate thrust at low flight speed. Therefore, an additional propulsion device to accelerate the ramjet vehicle to a supersonic speed is required. In this study, we propose a novel ramjet propulsion system with a $H_2O_2$/Kerosene rocket as the accelerator for initial stage. In order to test the feasibility of this concept, consecutive reactors was built; one for the decomposition of $H_2O_2$ and the other for kerosene combustion. Decomposed $H_2O_2$ jet was injected to combustor through converging nozzle from gas generator and over this hot oxygen jet, kerosene was injected by spay injector. Through the various test cases, hypergolic ignition test was carried out and steady combustion was achieved.

• Korean Journal of Optics and Photonics
• /
• v.1 no.1
• /
• pp.28-32
• /
• 1990

We have constructed and operated a discharge heated copper vapor laser which generated green (510.6 nm) and yellow (578.2 nm) light. The plasma tube was made of high purity (99.8%) alumina tube which has an inner diameter 25 mm and a length 106 cm. The electrodes, made of molybdenum sheet, were separated 108 cm apart. The laser gave an average power of 10 W at repetition rate of 5 kHz, charging voltage of 10 kV, Ne buffer gas pressure of 40 mbar, and the laser tube temperature of $1500^{\circ}C$..

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.8 no.3
• /
• pp.125-131
• /
• 2006

This survey was carried out to investigate the characteristics of low temperature injury in rice plants at a southwestern alpine area of Korea in 2003. During vegetative, reproductive, and ripening stage in a southwestern alpine area, mean air temperature was lower by 0.4, 3.1 and $1.7^{\circ}C$, respectively, as compared to those of a normal year, Minimum air temperature during the reproductive and ripening stage was lower by 2.6 and $1.7^{\circ}C$, respectively, as compared to those of a normal year, Sunshine hours during vegetative, reproductive, and ripening stage were lower by 40.6, 81.3 and 8.4 hours, respectively, than those of a normal year. Spikelet-sterility type cold injury occurred from the latter part of June to the middle of July, which is from panicle formation stage to meiosis stage, at temperatures less than $17^{\circ}C$. Spikelet sterility under normal transplanting (May 20) ranged from 16 to 58%, which was lower than that under early transplanting in the latter part of April (29 to 83%). The total area impacted by cold damage was 2,723ha in Namwon, 510ha in Sunchang, 300ha in Jinan, 250ha in Muju, and 210ha in Jangsu. Average spiklet sterility in these regions was 44%. Rice cultivars Odaebyeo, Unbongbyeo, and Jinbubyeo showed greater tolerance to low temperature than CV, Chugwangbyeo.