• 한국전자파학회논문지
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• 제8권1호
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• pp.52-60
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• 1997

MPIE 수치해석적 기법과 초고주파대 CAD 소프트웨 어 인 EEsof를 활용하여 2단 23 GHz대 저잡음 증폭기를 설계하였다 이 회로는 먼저 EEsof를 이용하여 기초 설계를 하고 MPIE 기볍에 의해 수정과 상세 해석을 실시 하는 방법으로 하였다. 입.출력단의 정합 부분은 평행 결합 여파기 형태로 하였는데 이는 임피던스 정합과 DC 차단을 동시에 실시할 수 있을 뿐만 아니라 불연속 부분이 적고 설계시 해석의 오차가 적은 장점을 가지고 있다. FET칩은 접지 급속 변에서 직접 부착하였다. 제작된 증폭기는 이득이 콘넥터 손실 1.8 dB를 고려하지 않은 상태에서 15.2 dB, 잡음지수가 2.7 dB를 나타냈다. 이와 같은 결과는 본 논문에서 사용한 설계 기법과 정합 기술이 20 GHz대 이상의 회로설계 및 제작에 적합하다고 할 수 있다.

• 한국해양공학회지
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• 제15권1호
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• pp.7-11
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• 2001

In this paper, trapezoid sections and prominence sections were examined to improve the performance of floating breakwater in long waves. The linear potential theory is used and the boundary element method with a matching boundary is employed for numerical computation. The effects of the side slope of the trapezoid section and the geometry ratio of the prominence section on the floating breakwater were examined. It was found that trapezoid sections show lower transmission coefficients than the rectangular sections in the long wave range. In prominence sections the size of the sides are more important than the size of the top. Proper choices of the pontoon type geometry may move the local minimum point of the wave transmission coefficient toward the longer wave ranges and improve the performance of the floating breakwater in the long wave range for a given wave period.

• 대한원격탐사학회지
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• 제40권2호
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• pp.219-228
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• 2024

Vessels can operate with their Automatic Identification System (AIS) turned off, prompting the development of strategies to identify them. Among these, utilizing satellites to collect radio frequency (RF) data in the absence of AIS has emerged as the most effective and practical approach. The purpose of this study is to develop a matching algorithm for RF with AIS data and find the RF's applicability to classify a suspected ship. Thus, a matching procedure utilizing three RF datasets and AIS data was employed to identify ships in the Yellow Sea and the Korea Strait. The matching procedure was conducted based on the proximity to AIS points, ensuring accuracy through various distance-based sections, including 2 km, 3 km, and 6 km from the AIS-based estimated points. Within the RF coverage, the matching results from the first RF dataset and AIS data identified a total of 798 ships, with an overall matching rate of 78%. In the cases of the second and third RF datasets, 803 and 825 ships were matched, resulting in an overall matching rate of 84.3% and 74.5%, respectively. The observed results were partially influenced by differences in RF and AIS coverage. Within the overlapped region of RF and AIS data, the matching rate ranged from 80.2% to 98.7%, with an average of 89.3%, with no duplicate matches to the same ship.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.343-346
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• 2005

Radiation properties of flush mounted circular patch antenna are investigated. The patch is fed axis-symmetrically by a coaxial cable. Rigorous analysis is given using integral transform and mode matching techniques. The presented method accommodates radiating patch, and integrated matching sections and band pass filter.

• 한국전자파학회논문지
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• 제19권8호
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• pp.862-877
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• 2008

두 종류의 넓은 대역폭을 갖는 ring hybrids(하나는 coupled line이 포함되어 있고, 다른 하나는 left-handed transmission line을 포함한 ring hybrids)가 비교되었으며, 비교 결과로부터 coupled line을 포함한 ring hybrid가 모든 면에서 우수한 특성을 가짐을 보여줬다. 그러나, coupled line을 포함한 ring hybrid는 -3 dB coupling power를 가질 경우에 한해서만이 perfect matching이 이루어지기 때문에, perfect matching을 갖는 coupled line ring hybrid는 2차원으로 구현하기는 거의 불가능하다. 이 문제를 해결하기 위해서 coupled line을 해석했고, 그 해석 결과로부터 coupling coefficient에 관계없이 어느 경우에도 perfect matching을 이룰 수 있는 설계 식을 유도했다. 이 설계식을 이용하여, transmission line의 길이가 ${\pi}$보다 큰 경우에도 적용될 수 있는 크기를 줄이기 위한 새로운 형태의 transmission line 등가회로를 제시했다. 이 새로운 형태의 transmission line의 등가회로를 이용하면 기존의 ring hybrid의 $3\;{\lambda}/4$의 transmission line을 줄이는 데 사용할 수 있기 때문에 ring hybrid의 크기를 더욱 줄이는데 장점이 될 수 있다. 이 등가회로를 증명하기 위해서, coupling power를 고정하고 또는 transmission line의 길이를 고정하는 2가지 형태의 simulation을 하였으며, 대역폭은 coupled line의 coupling power에 직접적인 상관 관계가 있음을 보였다. 기존의 등가회로와 새로운 형태의 등가회로를 이용하여, 작고 넓은 대역폭을 가지는 ring hybrid를 제시하였다. 새로 제시된 ring hybrid를 이용하여, 기존의 ring hybrid와 비교하였다. 비교 결과로부터, 본 논문에서 제시한 ring hybrid의 전체 ring 둘레가 1/3보다 더 작음에도 불구하고, 대역폭이 훨씬 넓음을 보여줬다. 작고 넓은 대역폭을 가지는 ring hybrid를 측정했으며, 측정 결과는 -2.78 dB, -3.34 dB, -2.8 dB, -3.2 dB의 power division 특성을 보여줬으며, matching과 isolation은 20 % 이상의 대역폭에서 -20 dB보다 좋은 특성을 보여줬다.

• 전자공학회논문지D
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• 제34D권3호
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• pp.9-16
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• 1997

A 23GHz 1-stage LNA was designed by using new topology of coupled line type with EEsof softwares and modified by using MPIE numerical analysis. The parallel coupled filter-type matching sections give impedance matching and DC blocking simultaneously, and have small discontinuities. This matching scheme has simple structure in the design process and give small error. The EFT chip was directly attached to the ground metal. The designed LAN gives 6.2dB gain and 2.5dB noise figure without considering the loss of connectors. Through these results, it was verified that our design process, matching schemes and fabrication technologies was valied for developing 20GHz-band LNA.

• Journal of electromagnetic engineering and science
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• 제9권2호
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• pp.85-97
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• 2009

As operating frequency is raised and as more integration with active and passive elements is required, it becomes difficult to fabricate more than 120 ${\Omega}$ characteristic impedance of a mierostrip line. To solve this problem, an equivalent high impedance transmission-line section is suggested, which consists mainly of a pair of coupled-line sections with two shorts. However, it becomes a transmission-line section only when its electrical length is fixed and its coupling power is more than half. To have transmission-line characteristics(perfect matching), independently of coupling power and electrical length, two identical open stubs are added and conventional design equations of evenand odd-mode impedances are modified, based on the fact that the modified design equations have the linear combinations of conventional ones. The high impedance transmission-line section is a passive component and therefore should be perfectly matched, at least at a design center frequency. For this, two different solutions are derived for the added open stub and two types of high impedance transmission-line sections with 160 ${\Omega}$ characteristic impedance are simulated as the electrical lengths of the coupled-line sections are varied. The simulation results show that the determination of the available bandwidth location depends on which solution is chosen. As an application, branch-line hybrids with very weak coupling power are investigated, depending on where an isolated port is located, and two types of branch-line hybrids are derived for each case. To verify the derived branch-line hybrids, a microstrip branch-line hybrid with -15 dB coupling power, composed of two 90$^{\circ}$ and two 270$^{\circ}$ transmission-line sections, is fabricated on a substrate of ${\varepsilon}_r$= 3.4 and h=0.76 mm and measured. In this case, 276.7 ${\Omega}$ characteristic impedance is fabricated using the suggested high impedance transmission-line sections. The measured coupling power is -14.5 dB, isolation and matching is almost perfect at a design center frequency of 2 GHz, showing good agreement with the prediction.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2118-2126
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• 2017

The large-scale power system blackouts have indicated that conventional protection relays that based on local signals cannot fit for modern power grids with complicated setting or heavily loaded-flow transfer. In order to accurately detect various faulted lines and improve the fault-tolerance of wide-area protection, a novel multi-section weighed fault matching and detecting algorithm is proposed. The real protection vector (RPV) and expected section protection vectors (ESPVs) for five fault sections are constructed respectively. The function of multi-section weighed fault matching is established to calculate the section fault matching degrees between RPV and five ESPVs. Then the fault degree of protected line based on five section fault degrees can be obtained. Two fault detecting criterions are given to support the higher accuracy rate of detecting fault. With the enumerating method, the simulation tests illustrate the correctness and fault-tolerance of proposed algorithm. It can reach the target of 100% accuracy rate under 5 bits error of wide-area protections. The influence factors of fault-tolerance are analyzed, which include the choosing of wide-area protections, as well as the topological structures of power grid and fault threshold.

• 한국통신학회논문지
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• 제22권5호
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• pp.974-980
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• 1997

The 23GHz 1-state LNA was designed by using MPIE numerical analysis and conventional design EEsof softwares. The circuit was designed using conventional tools but analyzed and modified by using numerical MPIE tools. he matching sections was designed with parallel coupled filter-type, which gives impedance matching and DC blocking and has small discontinuities. THe FET chip is directly attached to the graound metal. The designed LNA gives 5.8dB gain and 2.5dB noise figure withoug considering the loss and impedance shift of connectors that degenerate the gain and noise figure considerably. this results gives very promising characteristics for our design process and matching schemes and fabrication technologies.

• 전자공학회논문지B
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• 제31B권7호
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• pp.190-198
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• 1994

In this paper, we propose the cross-section processing method which is simple in describing the SHGC of objects in a range image and which can describe the SHGC of occluded objects for the recognition of 3D objects. This method produces the cross-sections of an object along the assumed axis of the SHGC and describes the SHGC of the object by processing the produced cross-sections of the object using $\psi$ -S curves with invariant properties in position and size. Our method is simple in a process and can descirbe the SHGC of partially occluded objects because it uses range images with 3-D informations of objects without matching contours of objects with a model base. Thus it is a useful description method of a range image for the recognition of 3D objects shaped in SHGC form and we proved the usefulness of it in experiments.