• 한국정보전자통신기술학회논문지
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• 제3권1호
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• pp.24-30
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• 2010

본 논문에서는 전기적 소형 모노폴 형태의 안테나가 제시되었다. 크기가 매우 짧은 (${\iota}{\approx}{\lambda}_g/15$ ) 모노폴은 용량성 소자로 동작하며, 접지면 위에 놓여진 개방형 슬롯구조는 유도성 소자로 동작하므로, 이 들 두 소자를 결합시킨 구조는 LC 공진기를 형성하게 된다. 안테나에 대한 등가회로 모델 은 안테나의 해석 및 설계의 정확성을 파악하기 위하여 사용되었다. 제안된 안테나는 매우 작은 전기적인 크기를 갖고 있으나 양호한 성능을 나타내고 있다. 측정된 안테나의 최대 이득과 효율은 주파수 2.1 GHz에서 각각 3.6 dBi 및 77.8 %를 나타내었다.

• 한국전자파학회논문지
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• 제20권9호
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• pp.829-834
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• 2009

본 논문에서는 아래위로 7.6 mm의 간격을 갖고 있는 두 개의 금속판을 단락 핀으로 연결하고, 그 사이에 급전점을 위치시킴으로써 MediaFLO(Media Forward Link Only)/GPS(Global Positioning System)/Bluetooth 대역의 안테나 구현하였다. 안테나는 각각 사용 주파수 밴드별로 $0.5\;{\lambda}$ 슬롯 안테나와 단락된 패치 안테나의 배열로 해석이 가능하다. 제안된 안테나는 최근에 늘어나고 있는 금속 몸체를 갖는 이동 통신 단말기에서 별도의 안테나 없이, 단말기의 몸체를 안테나로 재활용할 수 있는 가능성을 제시하였다.

• 한국인터넷방송통신학회논문지
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• 제10권5호
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• pp.105-111
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• 2010

본 논문에서는 결함추출 알고리즘을 퍼지이론을 적용하여 유연성을 제시하고 실험을 통하여 타당성을 확인 하였다. 균열의 검출츨 위하여 퍼지형태학을 이용한 기본 연산자를 정의하였다. 이 연산자를 기초로 하여 퍼지집합에 대해 ${\lambda}$-퍼지척도를 이용하여 무게중심을 구하여 결함을 추출하였다.. 결함추출 알고리즘의 경우 양호한 결과를 낼 수 있었다. 하지만 균열이 매우 미세한 경우 영상 획득부분에 해당하는 조명장치를 얼마나 잘 설계하느냐가 중요하였다. 소프트웨어적으로는 룩업테이블을 사용하여 메모리의 사용을 최소화 시켜 좀 더 빠른 검사속도를 꾀하였다.

• 한국경영과학회지
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• 제17권3호
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• pp.67-78
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• 1992

MODM (multiobjective decision-making) problem is very complex system for the analyst. The problem is more complex if the goals of each of the objective functions are expressed imprecisely. It requires suitable MODM method to deal with imprecisions. Therefore, we present a new interactive fuzzy decision making method for solving multiobjective nonlinear programming problems by assuming that the decision maker (DM) has imprecise goals that assume fuzzy linguistic variable for each of the objective functions. The imprecise goals of the DM are quantified by eliciting corresponding membership functions through the interactive with the DM out of six membership functions. After determining membership functions, in order to generate the compromise or satisficing solution which is .lambda.-pareto optimal, .lambda.-max problem is solved. The higher degree of membership is chosen to satisfy imprecise goals of all objective functions by combining the membership functions. Then, the values are the compromise or satisficing solution. On the basis of the proposed method, and interactive computer programming is written to implement man-machine interactive procedures. Our programming is a revised version of sequential unconstrained minimization technique. Finally, a numerical example illustrates various aspects of the results developed in this paper.

• 정보처리학회논문지C
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• 제12C권6호
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• pp.793-798
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• 2005

본 논문에서는 방송, 통신, 인터넷이 통합되는 BcN 환경에서 멀티캐스트(Multicast) 서비스를 지원하기 위한 네트워크의 분기점(Rendezvous Point)에서 시스템 모델을 살펴본다 서비스에 따른 다중의 큐와 단일 서버로 이루어진 버퍼를 기하 분포의 배치 확률을 가지는 입력이 들어올 때, 단일 큐와 단일 서버로 모델링하여 입력률 $\lambda$에 따른 버퍼의 크기를 보이고, 서비스 제공자와 네트워크 운영자 사이의 관계를 알아본다. 이때 두 관점의 이익이 같아지는 최적의 입력률 ${\lambda}_{opt}$를 기준으로 새로운 서비스 요청에 대하여 이익을 기반으로 하는 호 수락 제어를 할 수 있는 범위를 제시한다.

• 천문학회지
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• 제41권3호
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• pp.77-81
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• 2008

As a continuation of a previous work by Park et al. (2006), we have developed a two-element radio interferometer that can measure both the phase and amplitude of a visibility function. Two small radio telescopes with diameters of 2.3 m are used as before, but this time an external reference oscillator is shared by the two telescopes so that the local oscillator frequencies are identical. We do not use a hardware correlator; instead we record signals from the two telescopes onto a PC and then perform software correlation. Complex visibilities are obtained toward the sun at ${\lambda}\;=\;21\;cm$, for 24 baselines with the use of the earth rotation and positional changes of one element, where the maximum baseline length projected onto UV plane is ${\sim}\;90{\lambda}$. As expected, the visibility amplitude decreases with the baseline length, while the phase is almost constant. The image obtained by the Fourier transformation of the visibility function nicely delineates the sun, which is barely resolved due to the limited baseline length. The experiment demonstrates that this system can be used as a "toy" interferometer at least for the education of (under)graduate students.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1026-1030
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• 2009

A novel Schiff base ligand (N, O system) 5-methoxy-2-phenyliminomethylphenol ($5-CH_3O-PMP$) was synthesized. Using the synthesized ligand as a fluorescent reagent, a fluorometric method was developed for the quantitative analysis of Al(III) ion. The quantitative analysis of Al(III) ion was performed by making the complex compound between Al(III) ion and $5-CH_3O-PMP$ in ethanol-water solution (85/15, v/v, pH 6.2). The excitation wavelength (${\lambda}em$) of the complex compound was 397 nm while the emmision wavelength (${\lambda}em$) was 498 nm. The quantitative analysis of Al(III) ion was carried out by estimating the fluorescence intensity. The various calibration curves were used for the quantitative analysis in the range of 0.27$\sim$27 ng/mL Al(III) ion concentrations. The detection limit was 0.027 ng/mL. Using the fluorometric method developed in this study, satisfying results were obtained from various samples such as tap water, hot spring water, river water, sea water and waste water, which contained considerable amounts of interfering ions.

• 한국세라믹학회지
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• 제34권7호
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• pp.693-698
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• 1997

The refractive index and dispersion in the (100-x)(0.6CaO.0.4Al2O3).xSiO2(x=0~30) glasses were investigated. As the amount of SiO2 increased, the refractive index decreased. The change of refractive index was attributed to the change of the molar refraction rather than the molar volume. When the amount of SiO2 was smaller than 20 mol%, the average electronic transition energy gaps(E0) and the electronic oscillator strengths(Ed) were about 10.9($\pm$0.1) nd 18($\pm$0.5)eV, respectively. However E0 and Ed of the glass (CAS30) with 30 mol% SiO2 increased to 12.63 and 19.89eV, respectively. The similar results was observed in the variation of Abbe Number. Abbe number of the glass in the range of 0~20 mol% SiO2 was about 46 and that of CAS30 increased to 60. The zero-material dispersion wavelength({{{{ lambda }}0) of pure calcium aluminate glass was 1.8 ${\mu}{\textrm}{m}$. As the amount of SiO2 increased, the zero-material dispersion wavelength shifted to a shorter wavelength. {{{{ lambda }}0 of CAS30 was 1.5 ${\mu}{\textrm}{m}$, that is currently using for the optical telecommunication system.

• 한국기계가공학회지
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• 제12권6호
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• pp.23-29
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• 2013

In this paper, pure $I_{ph}$ and hybrid carbon nanotube reinforced $I_{ph}$ were sintered using the SPS(spark plasma sintering) method for high densification. A nanosecond laser (${\lambda}=1063nm$, ${\tau}P=10ns$) and a femtosecond laser (${\lambda}=1027nm$, ${\tau}P=380fs$) were installed on an optical system for the micromachining test. The ablation characteristics of the pure $I_{ph}$ and CNT/$I_{ph}$ composites, such as thermal effect and ablation depth, were investigated using FE-SEM and a confocal microscope device. Laser machining results for the two mating materials showed improved performances: CNT/$I_{ph}$ composites showed good surface morphology of hole drilling without a melting zone due to the composites' high thermal properties; also, the ablated depth of CNT/$I_{ph}$ was higher than that of pure $I_{ph}$.

• 센서학회지
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• 제25권1호
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• pp.13-19
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• 2016

Nowadays, most major automobile manufacturers are very interested, and actively involved, in developing driver alcohol detection system for safety (DADSS) that serves to prevent driving under the influence. DADSS measures the blood alcohol concentration (BAC) from the driver's breath and limits the ignition of the engine of the vehicle if the BAC exceeds the reference value. In this study, to optimize the sensor array of the DADSS, we selected sensors by using three different methods, configured the sensor arrays, and then compared their performance. The Wilks' lambda, stepwise elimination and filter method (using a principal component) were used as the sensor selection methods [2,3]. We compared the performance of the arrays, by using the selectivity and sensitivity as criteria, and Sammon mapping for the analysis of the cluster type of each gas. The sensor array configured by using the stepwise elimination method exhibited the highest sensitivity and selectivity and yielded the best visual result after Sammon mapping.