• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.459-460
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• 2011

본 논문에서는 산과 골이 있는 복잡한 형상의 기어를 일정한 깊이로 열처리하기 위한 효율적인 유도가열에 관한 연구이다. 이를 위해 동시에 이중주파수를 발생하면서 출력을 각각 제어할 수 있는 인버터를 설계하였으며 두개의 인버터로 구동되는 방식을 기준으로 해석, 설계 및 부하와 매칭을 위한 필터 설계를 수행하여, MF(Medium frequency)와 HF(High frequency에서 공진주파수 운전을 위한 최적의 인버터를 설계 및 제작하고자 한다.

• The Journal of the Acoustical Society of Korea
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• v.19 no.7
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• pp.53-58
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• 2000

본 논문은 주파수 전이신호와 시간 전이 신호에 대해서 고조파 잡음 여기 방법과 시간 분리 여기 방법을 적용한 2.4 kbps 음성부호화 방법을 제안한다. 혼합 여기 부호화 방법은 주기 신호와 비 주기 신호를 효과적으로 표현하기 위해 하모닉 잡음 모델을 사용한다. 혼합신호에 대한 잡음 성분은 캡스트럴 분석 방법을 사용함으로써 추출되고, AR (Autoregressive Model) 모델에 의해 표현된다. 시간 전이구간 신호에서의 모호한 음성을 효과적으로 제거하기 위한 또 다른 방법이 제안된다. 제안된 시간 분리 방법은 시간 에너지 변화정도를 관찰함으로써 전이 시점을 감지하고 다른 시간 길이를 가지는 두 블록으로 분리하여 분석한다. 시간 분리 방법은 분석을 위한 비대칭 윈도우와 합성에서의 위상 합성 방법을 포함한다. 제안된 방법을 사용한 2.4 kbps 음성부호화 방법은 주관적 음질 평가에서 전이구간에서의 지각적 음질의 향상을 보여주었으며, 원본 음성 스펙트럼과의 고조파 비 매칭에 의한 윙윙거리는 기계적인 잡음을 감소시킨다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.2
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• pp.25-31
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• 1998

본 연구에서는 자동차 유리판에 초음파 대역 진동을 효율적으로 발생시킬 수 있는 압전 액츄에이터를 개발하고자 하였다. 자동차 유리판을 단순지지 평판으로 가정하였으며, 액츄에이터로는 PZT 진동자를 사용하였다. 유한 요소법(Finite Element Method)을 통하여 유리판의 최적 공진 주파수와 유리판에 부착할 압전 진동자의 구조 조건인 최적 위치와 개 수를 결정하였다. 설계 결과에 따라 자동차 유리판에 압전 진동자를 부착하여 임펄스 응답 해석(impulse response analysis)과 임피던스 해석(impedance analysis)을 수행하여 구동 주 파수를 확인하였다. 그 결과, 이 주파수로 가진하여 유리판 전면에 걸쳐 고른 초음파 진동이 분포함을 확인하였으며, 나아가 전기적 임피던스 매칭(impedance matching)을 통해 더 큰 효율의 진동을 발생시킬 수 있었다.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1942-1944
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• 2005

고주파 고투자율 자심재료를 이용하여 비접촉식 커플러를 제조하여 고주파대역의 신호전송 특성을 평가하였다. 고주파 임피던스 매칭을 통해 고주파 대역에서 비접촉식 커플러의 신호전송 특성을 향상시킬 수 있었고, air gap의 형성으로 포화전류가 300A 이상이고 $2{\sim}40 MHz$의 주파수 범위에서 $-3{\pm}2dB$의 신호전송 특성을 나타내는 비접촉식 커플러를 제조할 수 있었다. 또한 1:1의 권선비가 1:2보다 주파수 안정성이 우수하였고, 1:2는 저주파용 커플러에서 우수한 특성을 보일 것으로 평가되었다.

• Journal of the Korea Society of Computer and Information
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• v.5 no.3
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• pp.106-111
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• 2000

In this paper, we designed the DCO controller of frequency synthesizer by combing the m DS, DDS, and PLL methods to improve the performances(transition time, stability, re Designed DCO controller used parallel processing and pattern matching techniques. The designed DCO controller in this thesis profits the rapid and exact synchronization wh handed off in the mobile communication.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.215-220
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• 2016

In this paper, a wideband antenna accomplished by adding a double sleeve of a rectangular planar monopole structure is proposed. In order to impedance matching of proposed antenna, the antenna performance was improved by adding two gap sleeves and outer sleeve for double sleeve structure. HFSS simulator of ANSYS corp. was used in order to confirm the antenna parameter characteristic. According to the simulation results, the VSWR was less than 2 for the range of 2.5GHz~10.5GHz. The frequency bandwidth is 8GHz. The frequency range of the actual fabricated antenna was 2.92GHz~10.32GHz, the frequency bandwidth is 7.4GHz. The measured radiation pattern frequency is 3GHz, 6GHz and 9GHz. The results are similar with dipole antenna pattern in all frequency. The antenna size is $40{\times}40mm^2$. The utilization possibility of the ultra-wideband planar monopole antenna could be confirmed according to compare and analyze the simulation and measurement data.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.257-262
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• 2017

In this paper, we proposed a rectangular planar monopole antenna with a double sleeve that applied to a half-cut and a discontinuous feed structure. A rectangular planar monopole antenna with a double sleeve was cut in half along the magnetic symmetry line, and impedance matching was achieved by a discontinuous structure was applied to a feeder and by adjusting the double sleeve gap. We used the HFSS simulator of ANSYS company to confirm the antenna parameter property, and the antenna size was $21{\times}40mm^2$. In the proposed antenna, the simulation frequency range with VSWR of 2 or less was 2.6GHz to 10.25GHz. The bandwidth was 7.65GHz. The frequency range of the fabricated antenna was 3.3GHz to 9.75GHz, and the bandwidth was 6.45GHz. The measured radiation pattern frequencies were 3.5GHz, 5.5GHz, 7.5GHz, and 9.5GHz. A radiation pattern similar to the dipole antenna pattern was obtained at all frequencies.

• Journal of Advanced Navigation Technology
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• v.17 no.2
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• pp.177-182
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• 2013

In this paper, printed antenna which can be applied to a built-in wireless module of the security controller operating at global positioning system(GPS) L1 frequency band(1.575GHz) is proposed. The proposed antenna is basically composed of a microstrip patch antenna with inserting feed. In particular left and right slots which are respectively asymmetric are used for impedance matching, whereas slot with one open-end and shorting point are used on the bottom plane to set operating frequency and enhance bandwidth. It is observed at the desired GPS L1 frequency band that the radiation efficiency and gain of the proposed antenna are 90% and more than 4.8dBi respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.962-971
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• 2004

In this paper, we present the numerical analysis method for analyzing scattering characteristics of a rectangular waveguide with the conducting half cylinder using the mode matching method and compute scattering characteristics of a waveguide according to the rotation and changing radius of the half cylinder. Also, in conjunction with the generalized scattering method, the proposed method can be easily applied to a rectangular waveguide with cascade structure of conducting half cylinders. From the simulated result of a two pole filter, resonance frequency could be controlled by the rotation of half cylinders. The simulated result shows good agreement with the HFSS's result. The proposed structure and analysis method are easily applied to the design of waveguide components with conducting half cylinders.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1581-1592
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• 2009

Recently, we can hear various kinds of music in everywhere and anytime. If a user wants to find the music which was heard before in a street or cafe, but he does not know the title of the music, it is difficult to find it. That is the limitation of previous retrieval system of music data. To overcome these problems, we research a method of content-based retrieval of music data based on the recorded humming, the part of recorded music and the played musical instrument. In this paper, we investigated previous content-based retrieval methods of papers, systems and patents. Based on that, we research a method of content-based retrieval of music data. That is, in case of using the recorded humming and music for query, we extract the frequency information from the recorded humming/music and the stored music data by using FFT. We use a MIDI file in case of query by the played musical instrument. And by using dynamic programming matching, the error caused by the disparity of length between the input source with the stored music data could be reduced.