• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11B
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• pp.1903-1908
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• 2000

사다리형 디지털필터는 일반적으로 IIR 필터의 직접형, 병렬형 또는 종속형과 비교하여 주파수응답 감도가 뛰어나기 때문에 최근 많이 이용되고 있다. 사다리형 디지털필터는 모델의 형식에 따라 연분수 전개가 다르고 주어지는 전달함수에 따라 실현 가능한 형식과 불가능한 형식이 있다. 본 논문에서는 연분수 형태의 제 III 사다리형 디지털필터를 모델로 하여 방형성 결합기와 광섬유를 이용한 사다리형 광섬유필터의 실현조건과 설계방법을 논하였다.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.102-109
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• 2002

This paper proposes a new design algorithm to optimize the withdrawal weighted SAW ladder devices, Withdrawal weighting on SAW resonators gives enhanced bandwidth and transition band characteristics, so an optimization algorithm was developed for ladder type SAW filters. To illustrate the validity of the technique, this method was applied to the design of RF band CDMA TX SAW filters, and the design results were confirmed to show good agreement with experimental performance.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.367-370
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• 1999

일반적 인 SAW 필터에서 발생하는 선형성의 한계 및 천이대역의 특성을 개선하기 위한 새로운 구조의 이중구조 사다리형 SAW 필터의 최적 설계 방법을 제시하고 그 가능성을 확인하였다. 이중구조 SAW 필터는 일반적인 사다리형 필터의 구조를 바탕으로 하되, 두 개의 서로 다른 필터가 각각 주어진 대역사양을 반반씩 만족시켜 전체의 필터특성이 구현될 수 있도록 하였다. 특히 고주파 대역에서 만족시키기 어려운 정재파비 및 뛰어난 천이대역 특성을 만족시킬 수 있는 장점을 가지며, 이를 위해 withdrawal 가중기법 및 기판상에 encp화된 마이크로 스티 립라인 인덕터를 이용하였다. 우선 이중 구조 필터구조를 결정한 후, microstrip 라인 인덕터의 위치 및 인덕턴스 변화에 따른 필터특성 변화를 살펴보았으며, 필터의 각종 형상변수의 변화에 따른 필터 특성변화를 조사하였다. 이상의 결과를 바탕으로 새로운 방법의 이중구조 SAW 필터의 설계방법을 제시하였으며 그 타당성을 검증하기 위해 1.8 GHz 대역의 RF 필터에 대한 설계 결과를 나타내었다.

• The Journal of the Acoustical Society of Korea
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• v.18 no.1
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• pp.16-24
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• 1999

Design of SAW ladder filters has been performed by a rather trial and error method, that is, by modifying the design variables step by step until designed performance of the filter satisfies given specifications. In this work, optimal design method has been developed that automatically determines the detailed pattern of the SAW ladder filter to meet the specification once desired performance is given. As a first step for the development, the analysis tool for the SAW ladder filter has been produced by means of the Smith equivalent circuit analysis technique, and its validity has been verified through comparison of its calculation result with experimental data. With the analysis tool, we have investigated the performance variation of the filter with the change of its design factors, and the result has led to the optimal design algorithm. Validity and efficiency of the algorithm has been checked through test design of several SAW ladder filter samples on the market.

• The Journal of Korean Association of Computer Education
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• v.21 no.6
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• pp.39-47
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• 2018

This paper dealt with investigating the number of minimal spanning ladders originated from ladder game and their properties as well as the related computational thinking aspects. The author modified the filtering techniques to enhance Mathematica project where a new type of graph was generated based on the algorithm using a generator of firstly found minimal spanning graph by repeatedly applying independent ladder operator to a subsequence of ladder sequence. The newly produced YC graphs had recursive and hierarchical graph structures and showed the properties of edge-symmetric. As the computational complexity increased the author divided the whole search space into the each floor of the newly generated minimal spanning graphs for the (5, 10) YC graph and the higher (6, 15) YC graph. It turned out that the computational thinking capabilities such as data visualization, abstraction, and parallel computing with Mathematica contributed to enumerating the new YC graphs in order to investigate their structures and properties.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.162-167
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• 2013

X-ray or ${\gamma}$-ray spectroscopy systems are widely used for analyzing material characteristics. Pile-up pulses are very often encountered for several reasons in XRF systems. Thus, it is necessary to reject or recover pile-up pulses to accurately analyze the material under test. In this paper, a pile up pulse rejection and recovery method is presented for XRF systems using trapezoidal pulse shaping of the input signals. Since the proposed method is based on the trapezoidal pulse shaping method widely-used in XRF systems, only two counters and a few registers are needed to implement the additional function of pile-up pulse rejection and recovery. Consequently, the proposed system is much simpler than conventional pulse reconstruction systems. It is shown that the proposed method can detect and reject pile-up pulses exactly. It is also shown that the pile-up pulses can be recovered if some conditions are satisfied.

• The Journal of the Acoustical Society of Korea
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• v.21 no.1
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• pp.47-55
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• 2002

This paper proposes a new improved lumped element equivalent circuit analysis method to analyze withdrawal weighted SAW resonators of irregular electrode configurations, which enables to calculate the frequency response of withdrawal weighted SAW resonators. This method has led to the derivation of Smith equivalent circuit's y-parameters for a single ground electrode and formulated the resonator's admittance by calculating the total current into an IDT assembly. To illustrate the effectiveness of the technique, this method was applied to the design of a simple ladder filter and the change of the filter performance was investigated in relation to the weighting of the series and parallel resonators, respectively. The results shows that the withdrawal weighted resonator ladder filters provide better performance in their bandwidth and transition characteristics than normal ones. This new equivalent circuit analysis method can also serve as a better tool to design and analyze general SAW resonator filters.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.3
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• pp.1-9
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• 2003

In this paper, we designed a highly suppressed sidelobe ladder type RF SAW bandpass filter based on 1-port resonator, for 800 MHz mobile communication system. In order to get the highest device characteristics, we optimized some important parameters such as the electrode thickness, electrode lambda weghting of the reflectors, and static capacitance ratio. Furthermore, we fabricated the Tx and Rx. filter using optimized parameters. Implemented filters can be used in 800 MHz mobile communication system and external impedance matching circuits are not needed. RF filter was fabricated on 36$^{\circ}$LiTaO$_3$ substrates with Al-Cu (W 3 %)and mounted 3.8mm$\times$3.8mm$\times$1.5mm SMD package. Developed filters has 2.3 dB insertion loss in the 25 MHz pass-band, 33MHz with 3-dB insertion loss, stop-band rejection of 30 dB, passband ripple is less than 0.5 The power durability of the filters measured about 3.5W and the maximum temperature variation within -2$0^{\circ}C$~8$0^{\circ}C$ was 0.09 dB/$^{\circ}C$ of 3-dB insertion loss.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.393-396
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• 2000

기존의 탄성표면파 듀플렉서 필터는 1/4 파장 정합선로를 이용한 격리회로를 이용하기 때문에 패키지 상에 스트립라인을 구성하는 제작상의 어려움이 있다 본 연구에서는 격리회로가 송신용, 수신용 필터와 함께 온칩상에 위치할 수 있는 새로운 형태의 탄성표면파 필터를 설계하였다. 그 과정으로 송수신 대역을 각각 담당하는 사다리형 필터를 설계하였고, 집중소자 즉, 인덕터와 캐패시터로 구성되는 탄성표면파 듀플렉서 필터의 격리회로를 구성하였으며, 우수한 성능을 가질 수 있도록 각각의 집중소자들의 값을 최적화하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.381-382
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• 2022

흘수는 선체가 물속에 얼마나 잠겨있는지를 나타내는 용어로, 선박에서는 화물의 양을 계산하거나 안정성을 평가하기 위해 흘수를 측정한다. 흘수를 측정하는 방법으로는 항해사가 부두에서 육안으로 확인하거나, 사다리를 타고 내려가 직접 확인하는 방법이 있다. 이러한 방법들은 경우에 따라 흘수 측정이 불가능하거나, 추락의 위험이 항상 존재한다는 문제가 있다. 이러한 문제를 해결하기 위해 드론 등을 통해 카메라로 선박의 흘수선 부근을 촬영하고, 필터링 및 이미지 검출 기법을 사용하여 선박의 흘수선을 탐지하는 방안을 제시하였다.