• 조명전기설비학회논문지
• /
• 제20권9호
• /
• pp.40-44
• /
• 2006

This study investigated a new tuneable bandpass filter based on coplanar waveguide coupled line structure, and using the varactor diode for tuning the center frequency of the filter. The filter was designed by a commercial simulator and had a tuning range of 180[MHz] from 0.95[GHz] to 1.13[GHz]. The filter acceptable values regarding the insertion loss was less than 3[dB] and its return loss greater than 12[dB]. The figure of merit of the implemented tuneable filter increased with the reverse bias voltage up to 14[V] on the varactor diode. The proposed filter has a promising future as it can be used in integration processes and in various materials as substrate.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.1412-1415
• /
• 1996

In this paper, a new identification method of the cascade control system is proposed which can overcome the weak points of Krishnaswamy and Rangaiah(1987)'s method. This new method consists of two steps. One is on-line process identification using the numerical integration to approximate the two process dynamics with a high order linear transfer function. The other is a model reduction technique to derive out low order transfer function(FOPTD or SOPTD) from the obtained high order linear transfer function to tune the controller using usual tuning rules. While the proposed method preserves the advantages of the Krishnaswamy and Rangaiah(1987)'s method, it has such a simplicity that it requires only measured input and output data and simple least-squares technique. Simulation results show that the proposed method can be a promising alternative in the identification of cascade control systems.

• 전기학회논문지
• /
• 제57권7호
• /
• pp.1123-1128
• /
• 2008

The necessity of online dynamic security assessment is getting apparent under Electricity Market environments, as operation of power system is exposed to more various operating conditions. For on-line dynamic security assessment, fast transient stability analysis tool is required for contingency selection. The TEF(Transient Energy Function) method is a good candidate for this purpose. The clustering of critical generators is crucial for the precise and fast calculation of energy margin. In this paper, we propose a new method for fast decision of mode of instability by using stability indices and energy margin. The method is a new version of our previous paper.[1] Case studies are showing very promising results.

• 한국레이저가공학회지
• /
• 제15권4호
• /
• pp.16-19
• /
• 2012

Due to the fact that the dimensions of circuit lines of IC substrates have been forecast to reduce rapidly, engraving the circuit line patterns with laser has emerged as a promising alternative. To engrave circuit line patterns in an IC substrate, we used a projection ablation technique in which a metal (INVAR) mask and a DPSS UV laser instead of an excimer laser are used. Results showed that the circuit line patterns engraved in the IC substrate have a width of about 15um and a depth of $13{\mu}m$. This indicates that the projection ablation with a metal mask and a DPSS UV laser could feasibly replace the semi-additive process (SAP).

• 대한안전경영과학회지
• /
• 제7권3호
• /
• pp.85-96
• /
• 2005

This paper is concerned with the integrated problem of line balancing and model sequencing in mixed model assembly lines(MMALBS), which is important to efficient utilization of the lines. In the problem, we deal with the objective of minimizing the overall line length To apply the GAs to MMALBS problems, we suggest a GA representation which suitable for its problems, an efficient decoding technique for the objective, and genetic operators which produce feasible offsprings. Extensive experiments are carried out to analyze the performance of the proposed algorithm. The computational results show that our algorithm is promising in solution quality.

• 한국국방경영분석학회지
• /
• 제28권2호
• /
• pp.116-124
• /
• 2002

In just-in-time production systems, U-shaped production lines rather than traditional straight lines are often adopted since they have some advantages. The advantages of U-lines over straight lines are that the workstations required can be reduced and the necessary number of workers can be easily adjusted when the demand rates are changed. In this paper, we present a new genetic algorithm(GA) to minimize the number of workstations primarily and improve the work relatedness secondarily in the U-line production systems. Also, a new heuristic method is presented according to the work related factors and characteristics of U-line balancing. Some major aspects of the proposed GA are discussed, with emphasis on representation, decoding and evaluation function. Extensive experiments are carried out on well-known test-bed problems in the literature to verify the performance of our algorithm . The computational results show that our algorithm is a promising alternative to existing heuristics.

• 한국전자파학회논문지
• /
• 제19권2호
• /
• pp.257-262
• /
• 2008

본 논문에서는 열전도도가 우수한 AIN 기판에 $CO_2$ Laser 장비 를 이용하여 Thru-hole과 scribing line을 형성하기 위해 $CO_2$ laser의 파라미터(촛점 거리, 공기량, 레이저 빔 시간, 펄스 개수)를 실험하고, 자체 정렬 마스킹 기법을 이용한 5 um 두께의 Cu 도금으로 AIN 기판에 전송 선로와 나선형 평면 인덕터를 제작하였다. AIN 기판에서의 마이크로스트립 라인의 전송 손실은 10 GHz에서 0.1 dB/mm, 6 nH 나선형 평면 인덕터는 1 GHz에서 56의 품질 계수를 얻었고, 이를 통해 열전도도가 우수한 AIN 기판의 고전력 RF 응용이 가능할 것으로 기대한다.

• Journal of Mechanical Science and Technology
• /
• 제14권10호
• /
• pp.1168-1177
• /
• 2000

Hydrocarbon adsorber is considered as a promising technology to reduce cold start HCs in automotive exhaust gas. In this study, three in-line adsorber systems were tried to reduce the cold start emission. To check the basic characteristics of adsorber converters, surface areas, TPD and TP A were examined after a hydrothermal aging. Also idle engine bench was used to find the adsorption and desorption capabilities of the adsorber systems at cold start. Finally a practicability of the adsorber systems for the LEV achievement was checked with FTP test on a 2.0 D MIT vehicle. The results of this study indicate that hydrocarbon adsorber system is one of the promising passive technologies to meet the ULEV regulation.

• Journal of Advanced Marine Engineering and Technology
• /
• 제34권2호
• /
• pp.325-331
• /
• 2010

본 논문에서는 주기적 접지구조(PPGS)를 가지는 소형 단파장의 미앤더 선로를 GaAs MMIC(Monolithic Microwave Integrated Circuit) 상에 구현하였다. PPGS구조를 이용한 미앤더 선로는 기존의 미앤더 선로에 존재하던 용량 $C_a$와 함께 추가적인 용량 $C_b$를 가짐으로써 전체적인 용량이 커지게 되어, 단파장 특성을 보여주었다. 기존의 미앤더 선로는 주기적 구조가 아닌데 반해 PPGS 구조의 미앤더 선로는 주기적 구조이므로 $\beta$값이 큰 slow-wave가 존재하며, 이로 인해 종래의 미앤더 선로에 비해 선로 상에서 훨씬 더 큰 위상변화량을 보여준다. 본 논문에서는 상기 미앤더 선로의 특성을 실험적으로 고찰하여 PPGS 구조의 미앤더 선로를 병렬 인덕터로 사용할 경우, 기존 미앤더 선로를 사용할 때 보다 높은 인덕턴스 값을 가지므로 동일한 길이의 기존 선로보다 큰 인덕턴스 값을 가지는 정합 소자로써 사용할 수 있음을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권8호
• /
• pp.1248-1256
• /
• 2008

In this paper, basic characteristics of transmission line employing PPGM (periodically perforated ground metal) were investigated using theoretical and experimental analysis.According to the results, unlike the conventional PBG (photonic band gap) structures, the characteristic impedance of the transmission line employing PPGM structure showed a real value, which exhibited a very small dependency on frequency. The transmission line employing PPGM structure showed a loss (per quarter wave length) higher by $0.1{\sim}0.2\;dB$ than the conventional microstrip line. According to the investigation of the dependency of RF characteristic on ground condition, the RF characteristic of the transmission line employing PPGM structure was hardly affected by the ground condition in the frequency lower than Ku band, but fairly affected in the frequency higher than Ku band, which indicated that coplanar waveguide employing PPGM structure was optimal for RF characteristic and reduction of size. Considering above results, impedance transformer was developed using coplanar waveguide with PPGM structure for the first time, and good RF characteristics were observed from the impedance transformer. In case that {\lambda}/4$ impedance transformer with a center frequency of 9 GHz was fabricated for a impedance transformation from 20 to10 {\Omega}$, the line width and length were 20 and $500\;{\mu}m$, respectively, and its size was only 0.64 % of the impedance transformer fabricated with conventional microstrip lines. Above results indicate that the transmission line employing PPGM is a promising candidate for a development of matching and passive elements on MMIC.