• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.12
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• pp.55-67
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• 2010

The electrical properties of a back drilled via-hole (BDH) without the open-stub and the plated through via-hole (PTH) with the open-stub, which is called the conventional structure, in a high-count multi~layered (HCML) printed circuit board (PCB) were investigated for a high-speed digital system, and a selected inner layer to transmit a high-speed signal was farthest away from the side to mount the component. Within 10 GHz of the broadband frequency, a design of experiment (DOE) methodology was carried out with three cause factors of each via-hole structure, which were the distance between the via-holes, the dimensions of drilling pad and the anti-pad in the ground plane, and then the relation between cause and result factors which were the maximum return loss, the half-power frequency, and the minimum insertion loss was analyzed. Subsequently, the empirical formulae resulting in a macro model were extracted and compared with the experiment results. Even, out of the cause range, the calculated results obtained from the macro model can be also matched with the measured results within 5 % of the error.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.80-83
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• 2017

In this paper, the X-band reconfigurable frequency selective surface having flexible geometry was proposed. The proposed RFSS is composed of patterns of cross-shaped loop with inductive stub, which can control the frequency response for C-Band and X-band by ON/OFF state of PIN diode. To minimize the parasitic effect and to obtain the high level of isolation between the unit cell of FSS and the bias circuit, we designed the grid type bias line on bottom layer through via hole. The measured transmission characteristics show good agreement with the simulation results and good stability of frequency response for different incident angles and curvatures of surface.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.355-363
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• 2010

The objective of this study is to examine the structural performance on the Rectangular Steel Tube Column-to-H Beam connections using one-side bolts and T-stub. Although a rectangular steel tube comparing with a H-shaped steel has many advantages and is more efficient, its application is limited due to the lack of experiences and connection details. Existing steel moment connections using the rectangular steel tube are mainly using through plate diaphragms. Its processing of construction is so complicated that it is hard to apply in the field. In this study, the structural performance and the earthquake capacity for T-stub connection with one-side bolts were investigated. And it is performed a comparative analysis of strength, rigidity, total rotation and energy absorption capacity for the various connection details.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.36-36
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• 1999

한국중공업(주)에서 수행한 KSTAR 진공용기 시작품 제작이 완성됨에 따라 제작과 관련된 종합기술을 분석하여 보았다. KSTAR 진공용기 시작품(그림1)은 전체의 1/4섹터인 90도 부분으로서 NBI(Neutral Beam Injection) 포트를 포함하는 45도 섹터와 축소포트(Reduced Port)를 포함하는 45도 섹터를 각각 먼저 제작한 후 두 부분을 용접하여 최종 시작품을 완성하였다. 용접은 SMAW법과 GTAW법 등 두가지 방법을 사용하였으며, 초기 용접시는 용접 면적이 작기 때문에 GTAW법을 이용하였고, 마무리 용접과 같이 용접 면적이 넓고 거친 부분에는 SMAW법을 이용하여 용접하였다. 모든 용접이 완전통과 용접이기 때문에 구조적 안전 면에서 좋으나, 진공측면에서는 다소 미흡한 점이 있다. 시작품은 상하 대칭구조로서 원통부분, 원형부분, 원추부분, 너클부분 (그림2) 등으로 나뉘어 지며 이중 원형품은 금형을 이용하여 성형하였고, 나머지 부분은 굽힘가공 후 절단적업을 하였다. 진공용기 조립은 안쪽과 바깥쪽 내벽부터 용접한 후 폴로이달 리브를 용접하고 외벽을 용접한다. 수평포트와 수직포트를 위해 스터브를 용접한 후 미리 용접해둔 NBI 포트 및 축소포트를 부착시켰다. 용접부위의 누설시험을 위한 방법으로, 용접주위 표면에서 개구하고 있는 홈에 적색 침투액을 침투시켜 침투 후 이 액을 홈의 개구로부터 빨아 내어 용접부위 표면상태에서 실제의 홈의 폭보다 확대한 홈의 지시모양으로 나타내게 하여 누설여부를 알기 쉽게 하는 액체 침투 탐상법을 적용하였다. 지시모양의 크기가 5mm 이상인 부분에 대해서는 재용접을 하였다. 누설 시험으로 초음파 탐상시험이 본제품 제작시 수행되어야 한다. 완성된 시작품에 대해 3군데의 위치에서 각각의 부분들이 용접되기 전과 후에 치수를 각각 측정하여 비교하였다. 또한 포트들에 대해서도 용접 전후 치수를 각각 측정하였다. 이러한 측정은 줄자를 사용하여 측정하였으므로 차 후 3차원 정밀 측정이 수반되어야 한다. 이상과 같이 시작품 제작을 통하여 문제점을 파악하고 개선책을 마련함으로서 향 후 KSTASR 진공용기 본 제품 제작할 때 반영코자 한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.105-112
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• 2010

Recently, wireless communication systems have been developed and the circuits which operate with the broad-band for multiband uses were introduced. However, broad-band circuits have problems that inevitably increase the size. Dual-band circuit operates only two frequency, therefore, it will be able to miniaturize through unnecessary decreased elements. The Wilkinson power divider is the one of the most commonly used components in wireless communication system for power division. Nowaday, the Wilkinson power divider is also demanded dual-band. In this paper, I propose miniaturized dual-band Wilkinson power divider operating at 2.45 GHz and 5.2 GHz for IEEE 802.11n standard. Proposed dual-band Wilkinson power divider is used in parallel stub line. The design is accomplished by transforming the electrical length and impedance of the quarter wave sections of the conventional Wilkinson power divider into dual band ${\pi}$-shaped sections.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.833-842
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• 1998

In this paper, a K-band oscillator which is composed of a hair-pin resonator, a GaAs MESFET, and a frequency doubler, is suggested, implemented by HMIC(Hybrid Microwave Integrated Circuits) form, and characterized for its microwave performance. A $\lambda_g$/4 open stub is used in frequency doubler to suppress the fundamental frequency of 9 GHz which is the output of the hair-pin resonator oscillator and output matching network is optimized for its second harmonic freuency of 18 HGz. For the oscillator, the output power of -0.83 dBm, the fundamental frequency suppression of -23 dBc, and phase noise of -86 dBc/Hz at 18.20 GHz are obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.12 s.115
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• pp.1150-1155
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• 2006

In this paper, the equivalent circuit of tapped-line that is applied in the band-pass filter is suggested and the value of an equivalent circuit is mathematically defined. An equivalent circuit of tapped-line is composed by open stub and transmission line that has negative electrical length, and the position of tapped-line and the value of resonator's length can be obtained by the impedance of resonator and the inverter. The new design method using equivalent circuit leads to very good agreement compared with theoretical value. The hair-pin band-pass filter using equivalent circuit of tapped-line shows the insertion loss of 1.1 dB and the return loss of 20 dB at the center frequency of 2 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.493-500
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• 2008

This paper describes a design of internal frequency modulation(FM) radio antenna fur mobile terminal. In order to control of impedance at an operating frequency of the designed antenna, the lumped constant elements of R and L chip components are used. Patch and stubs located at antenna backside are added to control an exact resonance frequency and miniaturization. A fabricated antenna sire, the measured return loss, impedance, bandwidth, and gain are $40{\times}70{\times}1$ mm, -23 dB at 99 MHz, $55-j7{\Omega}$, 22 MHz($88{\sim}110$ MHz) below -10 dB, and -15 dBi, respectively. These measured results show a good agreement with simulated results. Especially, the measured gain of fabricated antenna is similar with value of a conventional ear-phone antenna in the designed frequency band. The measured radiation pattern agrees well with the calculated omni-directional pattern.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.913-921
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• 2007

In this paper, we propose a novel small antenna for direction finding applications. The proposed antenna employs a skirt type disk to eliminate the radiation null on the broad-side direction in the high frequency range. Additionally, the multi-section matching stub is used for impedance matching in the low frequency range, The size of the proposed antenna is reduced as a half of the 60cm dipole which has a same resonance frequency of 200MHz. The antenna maintains a donut shape radiation pattern with a broad beam width for a wide range of frequency while the 60cm dipole shows radiation nulls on the broad-side direction and the high side-lobe level from 700MHz to 1,300MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.745-751
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• 2018

This paper reports on the design of a multiband multiple-input and multiple-output(MIMO) antenna for long-term evolution(LTE) vehicular communication and includes an analysis of the throughput field test results that were acquired by mounting the antenna to a vehicle. The antenna used for the field test was designed as a planar structure and included multiple stubs to obtain multiband resonant characteristics operating in the LTE(0.8~0.9 GHz, 1.7~2.2 GHz), Wi-Fi(2.4~2.48 GHz), and wireless access in vehicular environments (WAVE)(5.8~5.9 GHz) frequency bands. For the field test, antenna prototypes were mounted on the dashboard and roof of a vehicle and connected to the experimental LTE modem. The data transfer rate(throughput), signal-to-interference-plus-noise ratio(SINR), and reference signal received quality(RSRQ) were measured and analyzed in various real-world radio wave environments. Based on these results, the relationship between the SINR and throughput according to the field intensity is confirmed.