• 한국전자파학회논문지
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• 제19권4호
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• pp.411-417
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• 2008

본 논문에서는 UHF 대역 RFID 휴대 리더용 안테나로 원편파를 갖는 마이크로스트립 패치 안테나의 소형화를 제시한다. 제안된 안테나는 패치에 4개의 I 슬롯을 가지고 있으며, I 슬롯이 없는 같은 구조의 패치 안테나와 비교하여 안테나 크기가 감소하였다. 두께가 6.4 mm인 FR4 기판으로 제작된 안테나는 크기가 $76{\times}76\;mm$로 소형이면서, 반사 손실 -10 dB 대역폭은 $938{\sim}975\;MHz$, 대역폭 내 이득은 $-0.88{\sim}-2\;dBi$, 그리고 축비는 $3.27{\sim}13.21\;dB$를 가진다.

• 대한전자공학회논문지SD
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• 제47권1호
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• pp.14-19
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• 2010

전송폭과 굴절률이 서로 다른 다중모드 간섭 결합기 (MMICs)를 계단형으로 연결하면 전형적인 방법으로 설계된 다중모드 간섭 결합기의 결합길이를 현저하게 줄일 수 있는 새로운 구조가 본 논문에서 제안되었다. 전송폭이 82%의 cross 결합효율에 대하여, 결합길이는 약 6.7%가 줄어들었다. 그러나, 전송폭과 굴절률이 계단형인 다중모드 간섭 결합기에서는 약 93%의 결합 효율과 약 9%의 결합길이 축소가 발생하였다. 더욱이, 소형 다중모드 간섭 결합기를 설계하기 위하여 널리 사용되는 테이퍼 구조를 계단형으로 구성하면, 약 90%의 결합효율과 약 25%가 축소된 소형 다중모드 간섭 결합기를 설계할 수 있음을 보였다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.450-453
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• 2003

In this paper, the miniaturization of linear polarization microstrip patch antenna is studied by attached Irises near the square linear polarization microstrip patch antenna which are induced the increase of current path. Microstrip patch antenna having the Irises is designed and fabricated at the resonant frequency of 1.575 GHz. The result is like that the resonant length of patch is reduced 41.5 mm which correspond to 50.9 % of that of plane type(81.5mm). The return loss is -28.5 dBd and -10 dB bandwidth is 103 MHz( 6.5 %). And as the radiation pattern is broad through the size reduction of patch, the gain is 5.9 dBd and -3 dB beamwidth of E-plane is $111.9^{\circ}$.

• 한국CDE학회논문집
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• 제4권4호
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• pp.318-326
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• 1999

Recently, electronic systems including computers have been rapidly shrinking in size while at the same time the complexity and the capability of these systems continue to grow/sup [1]/. Thus, system volumes have decreased as system power has increased, resulting in dramatic increases in system heat density. The high temperature of the computer system is considered as the major reason for low performance and shortening life of the product. It is necessary to solve this problem due to the heat density increased and to develop the design skill of the computer cabinet according to miniaturization. M4500 desk-top computer was selected for analyzing the thermal management inside cabinet. The cabinet volume, the configuration of the heating devices, the size and location of air ventilation, and the fan selection have been investigated as the important parameters to find out an optimal cabinet design. The objectives of this project were to analyze which design parameters would affect cooling performance by thermal strategy, to design an optimal model, and to measure the temperatures of the main parts to confirm the effect of the thermal design. The temperatures of each part of the optimal model were compared with those of the existing model. As a result. the volume of this miniaturized model was about 16% smaller than that of M4500 without any change in operating performance.

• 한국광학회지
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• 제19권1호
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• pp.25-30
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• 2008

다중 모드 간섭 결합기를 소형화하기 위한 새로운 구조가 본 논문에서 제안되었다. N개의 입/출력 단자를 갖는 $N{\times}N$ MMI 결합기의 결합길이는 MMI 영역 폭의 증가에 따라 2의 급수에 비례하여 증가한다. 그 결과 많은 N개의 단자로 구성된 MMI 결합기를 설계 할 경우 소자의 크기가 기하급수적으로 커진다. 그러므로, 설계 시에 발생하는 문제를 해결하기 위하여 기존에 제안되어 왔던 MMI 결합기보다 더운 작은 소자크기를 갖는 새로운 나비형 격자구조 MMI 결합기를 제안하고 분석하였다. 또한, 제안한 소자에 대한 이론적 분석을 통하여 새로운 설계 기준을 제시하였고 수치해석적 결과와 비교 분석하였다.

• International Journal of Railway
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• 제8권1호
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• pp.10-14
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• 2015

Due to the characteristics of the vehicle structure, the magnetic levitation train has a confined bottom space thus a study on miniaturization and weight reduction of auxiliary power unit is essential. This auxiliary power unit is an essential device used for illumination, air conditioning, heating and air brake equipment excluding the motor. The previous auxiliary power unit for magnetic levitation train has used the hard switching having a high switching frequency with heavy loss in order to reduce the size of filter reactor and transformer but the reduction in volume was not significant. In this paper, by reducing the loss, reducing the size of the cooling unit and by increasing the switching frequency using the soft switching of resonant converter, it has miniaturized and reduced the weight of filter reactor and transformer which occupy significant space in the auxiliary power unit. This study has verified the performance of 50KVA grade prototype through simulated interpretation and analysis, and compared the size and weight of auxiliary power unit of the previous magnetic levitation train.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1171-1174
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• 2005

Manufacturing capability at the micro or nano scale production field is requested strongly in view of parts and product miniaturization. Miniaturized parts and products will introduce lots of benefits in terms of high precision functionality and low energy consumption. This paper presents the results of micro milling machine tool development for micro machining process. Finite element analysis has been performed to know the relationship between design dimensional variables and structural stiffness in terms of static, dynamic, thermal aspects. Performance evaluation through machining has been tested and discussed for achievable machining characteristics.

• 논리연구
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• 제15권3호
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• pp.307-322
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• 2012

프리드먼에 의해 제안된 "크루스칼 정리의 소형화 정리"가 2차 페아노 공리체계의 부분 시스템인 $(\prod_{2}^{1}-BI)_0$에서 증명될 수 없음을 증명한다. 또한 위 증명이 크루스칼 정리와 관련된 기존의 연구에서 알려진 중요한 정리들을 잘 조합함으로 해서 가능함을 보인다.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권2호
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• pp.76-80
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• 2005

In this paper, a miniaturized ring hybrid circuit is characterized based on a thin film microstrip (TFMS) on low-resistivity silicon. In order to obtain low-loss characteristics, a polyimide layer with 50 $\mu$m thickness is spin-coated onto the silicon to be used for the substrate. First, propagation characteristics of TFMS lines consisting of the ring hybrid circuit are presented. Then, a ring hybrid circuit based on TFMS is featured by employing the triple concentric circle approach for miniaturization. Triple concentric circle lines with $\lambda$$_{g}$/4 or 3$\lambda$$_{g}$/4 line lengths are implemented on the surface of the polyimide by circularly meandering to reduce the circuit size of the designed ring hybrid. Good agreement between measured and simulated results is obtained.

• 한국유체기계학회 논문집
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• 제10권4호
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• pp.21-28
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• 2007

The ratio of disk friction loss in a centrifugal pump is very large for the total pump loss in the range of very low specific speed. Therefore, impeller radius should be shortened to increase the pump efficiency because the disk friction loss is proportional to the fifth power of impeller radius. In order to compensate the decreased head by the shortened impeller radius, vane angle at impeller outlet should be increased. However, as the vane angle at impeller outlet becomes larger, performance instability occurs at low flow rate regions. In this study, J-Groove is adopted to suppress the performance instability and detailed examination is performed for the influence of the J-Groove on the pump performance. The results show that J-Groove gives good effect on the suppression of performance instability. Moreover, as J-Groove increases pump head considerably, the pump size can be smaller for head requirements.