• Geophysics and Geophysical Exploration
• /
• v.15 no.4
• /
• pp.199-208
• /
• 2012

High-amplitude swell noises (HASN) are very difficult to eliminate from the marine seismic data. In this paper, we applied F-X filter and median filter in order to suppress HASN. Test data have been acquired on the northern offshore of the South Shetland Islands in December, 2010. Parts of data have been contaminated by HASN caused by bad weather during the cruise. We applied F-X filter and median filter to test data with HASN. After F-X filtering, most of non-coherent noises and small-amplitude swell noises are eliminated effectively but HASN are still remained significantly. With median filter, HASN was suppressed better than F-X filter, however some of non-coherent noises are still remains. We applied a cascade of two filters and results show HASN and non-coherent noises are suppressed effectively. After the cascade of two filtering, it is possible to define reflection layers clearly on the velocity spectrum and to produce better stacked section with a good signal-to-noise ratio.

• Korean Journal of Optics and Photonics
• /
• v.18 no.1
• /
• pp.1-7
• /
• 2007

Filter colorimeters have a set of spectral bands for which spectral responsivity is the same as the color matching function defined by CIE (Commission Internationale de I'Eclairage). We have designed a set of color matching function filters denoted by $\bar{x}-filter,\;\bar{y}-filter,\;and\;\bar{z}-filter$. Because the $\bar{x}-function$ has two transmission bands, two $\bar{x}-filters$ are designed to cover the $\bar{x}-function$. To design the filters, we developed a nonlinear least square fit program which determines the thickness of the color glasses by minimizing its spectral mismatch value ($f{_1}'$) to below 3 %. The design has been validated by fabrication of the $\bar{y}-bar$ filter, of which $f{_1}'$ was measured to be 2.8 %. Considering a LCD flat panel display as a device under test, we have calculated the systematic error of the colorimetric measurement using the designed filters.

• Journal of the Microelectronics and Packaging Society
• /
• v.27 no.4
• /
• pp.97-105
• /
• 2020

Recently, as the data speed and operating frequencies of Ethernet keeps increasing, electro magnetic interference (EMI) also becomes increasing. The generation of such EMI will cause malfunction of near electronic devices. In this study, EMI filters were applied to reduce the EMI generated by DC-DC SMPS (switching mode power supply), which is the main cause of EMI generation of Ethernet switch. As the EMI filter, MLCCs with excellent withstanding voltage characteristics were used, which had advantages in miniaturization and mass production. Two types of EMI MLCC filters were used, which are X-capacitor and X, Y-capacitor. X-capacitor was composed of 2 MLCCs with 10 nF and 100 nF capacity and 1 Mylar capacitor. Y-capacitor was consisted of 6 MLCCs with a capacity of 27 nF. When only X-capacitor was applied as EMI filter, the conductive EMI field strength exceeded the allowable limit in frequency range of 150 kHz ~ 30 MHz. The radiative EMI also showed high EMI strength and very small allowable margin at the specific frequencies. When the X and Y-capacitors were applied, the conductive EMI was greatly reduced, and the radiation EMI was also found to have sufficient margin. In addition, X, Y-capacitors showed very high insulation resistance and withstanding resistance performances. In conclusion, EMI X, Y-capacitors using MLCCs reduced the EMI noise effectively and showed excellent electrical reliability.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.23 no.4
• /
• pp.59-64
• /
• 2023

In this paper, It is proposed through the empirical design of a Conducted EMI filter for noise reduction of power used in electronic devices. For the proposed structure, A-type, B-type, C-type, and D-type structures were designed, and conductive noise reduction was confirmed by using an LC network with various X-capacitors, Y-capacitors, and Air-inductors. 10 [μH] was used for L1 and L2, and 4.7 [nF] was used for C1 and C2. L3 for common mode used 13[μH], and C5, C6, C7 were designed using 10[nF]. The measured insertion loss values of the designed EMI filter were -74.4[dB] at 3.2MHz, -75.4[dB] at 4MHz, and -75.3[dB] at 13.56MHz. Therefore, the proposed EMI filter will be able to reduce power supply noise used in various electronic devices.

• 전기의세계
• /
• v.34 no.1
• /
• pp.19-23
• /
• 1985

LQG로 설계된 시스템이 LQR의 보증된 안정감도를 갖도록 $K_{f}$를 조정하는 한 LTR기법을 살펴보았다. q가 0이라면 필터는 실제의 프로세서 잡음의 Q = Q$_{0}$라는 점에서 최적이다. 그러나 q의 값이 증가함에 따라 $K_{f}$는 증가되고 x over ^에 따라서 시스템의 동특성은 관측에 의해 수정되는 항보다 상대적으로 소홀히 취급되어진다. 따라서 출력 y에 포함되어 지지않는 x의 추정치 xover^은 그 실제값과 차이가 많이 나타날 우려가 생긴다. 또한 관측잡음이 xover^에 크게 영향을 미치므로 잡음을 배척하는 필터의 성질도 모호해질 우려가 있다. 그러나 안정강도의 관점에서는 크게 개선되어진다는 것을 알 수 있다. 실제 설계에 있어서는 이 장점과 단점들을 잘 trade off시키는 단계가 필요할 것이다. 또한 추정치 xover^를 얻는데 정상상태의 칼만 필터를 이용하지 않고 극배치(Pole Placement)방법을 사용함도 고려할 수 있으며 이에 따른 LTR도 흥미있는 분야가 될 수 있을 것이다.다.

• ETRI Journal
• /
• v.14 no.4
• /
• pp.217-227
• /
• 1992

최근 이동통신 및 위성통신 등 마이크로웨이브를 이용하는 통신분야의 시장이 급속히 신장됨에 따라 RF(Radio Frequency) 부품의 산업적 중요성이 부각되고 있다. RF 부품은 크게 능동부품과 필터로 대표되는 수동부품으로 대별되는데, duplexer나 필터는 현재 대부분 마이크로웨이브 세라믹유전체를 사용 제조하고 있다. 본 연구에서는 이들 부품들에 사용가능한 세라믹유전체를 개발하기 위한 연구의 일환으로 BaO-$Sm_2$$O_3$-$TiO_2$계 세라믹의 마이크로웨이브 유전특성과 여기에$La_2\$$O_3$를 첨가한 계인 BaO-($Sm_1$$-_X$$La_X$$)_2$$O_3$-$TiO_2$ 세라믹유전체를 제조하여 마이크로웨이브 유전특성을 살펴보았다. RF 부품에 사용되는 세라믹유전체는 높은 유전율$\varepsilon_r$높은 품질계수 (Q) 및 안정된 온도특성 $\tau_f$ 등의 조건을 충족시켜야한다. 본 연구에서는 유전체의 $\varepsilon_r$ 및 Q의 측정에 디스크형 유전체공진기와 두개의 도체평행판을 사용한 Hakki-Coleman법을 사용하였으며, $\tau_f$는 fixture를 항온조에 넣어서 측정하였다. BaO-$Sm_2O_3-TiO_2$계의 경우 소결온도 $1350^{\circ}C$까지는 $\varepsilon_r$및 Q가 증가하나 그 이상의 소결온도에서는 감소한다. 그리고 $\tau_f$는 $-35_{ppm}/^{\circ}C$에서 소결온도에는 거의 의존하지 않았다. $La_2O_3$를 첨가한BaO-($Sm_1$$-_X$$La_X$$)_2$$O_3$-$TiO_2$ 세라믹의 마이크로웨이브 유전특성은 $La_2O_3$의 첨가량이 많을수록 $\tau_f$값이 음에서 양으로 이동함이 관찰되었으며, x=0.15에서 $\tau_f$가 0이 되어 마이크로웨이브 부품용 마이크로웨이브 세라믹유전체를 얻을 수 있음이 확인되었다.

• Journal of Korean Ophthalmic Optics Society
• /
• v.14 no.1
• /
• pp.47-56
• /
• 2009

Purpose: To find optimized luminosity factor of color from light transmission filter. Methods: To make $Y_{1-x}G_{x}$, $Y_{1-x}P_{x}$ by using CR-39 compound within dipping method, mixing up Y(Yellow), G(green) and P(pink) for optimize eye sensitivity. Modeling for relative luminous efficiency(relative sensitivity) curves in Luminose transmission, it could be resolved by Multiplying sensitivity of eye within transmission rate of Lens ($P_f({\lambda}=T({\lambda}){\cdot}P({\lambda}).)$.). To evaluate Wavelength between 400~700 nm, relative luminous efficiency curve in Area and Height value is being used. Results: In color filter of $Y_{1-x}G_{x}$ position of x equals to 0.04, 0.1, 0.08, 0.12, 0.14, 0.5 at ${\beta}=S_1/S_0{\cdot}100$ each consist value of 76.1, 77.9, 80.7, 81.6, 80.2, 18.6 In color filter of $Y_{1-x}P_{x}$ position of x equals to 1.00, 0.2, 0.6, 0.8 at ${\beta}=S_1/S_0{\cdot}100$ each consist value of 74.3, 74.0, 70.5, 33.0 The result from experiment $Y_{1-x}P_{x}$ value less than $Y_{1-x}G_{x}$, from evaluating luminous efficiency curve and test was successfully optimized. Conclusions: Optimized relative luminous efficiency curve result have value of X=0.12-0.14 at $Y_{1-x}G_{x}$.

• KIPE Magazine
• /
• v.9 no.3
• /
• pp.13-17
• /
• 2004

근래에 Texas Instruments(TI)사에서 개발된 TMS3320LF240x는 고정 소숫점 방식의 16비트 DSP으로써 저가, 고성능용으로 개발된 칩이다. 이 DSP는 비교적 빠른 계산속도에 다양한 입력/출력장치를 내장하고 있으므로 DSP 장점과 마이크로제어기의 장점을 모두 가지고 있다. 특히 Flash 메모리, RAM 등 메모를 포함하여 8-16채널 이상 A/D 컨버터, Timer, 직력통신과 함께 PWM인버터/컨버터용 PWM펄스까지 출력시킬 수 있으므로, 이 DSP는 각종 전동기 구동시스템과 SUP, 능동필터 제어 등 전력전자 분야에서 적합하게 설계된 DSP로 상당히 많이 사용되고 있다. 그런데 TMS320LF240x는 고정 소숫점 방식의 16비트 DSP이므로 연산량이 많은 시스템에서는 적용하기 힘들며, 또는 저장할 데이터량이 많은 제어시스템일 경우에는 내장된 flash 및 SRAM 등 메모리 용량이 부족하는 등 사용하는데 문제가 있을 가능성이 있다.(중략)

• The Journal of Engineering Geology
• /
• v.3 no.2
• /
• pp.167-176
• /
• 1993

The high resolution studies for shallow seismic reflection are carried out using 24-channel seismograph and the high sensitivity geophone(50-500Hz). In order to study the underground structures such as small faults, fractures, cracks and cavities, it is of great importance to enhance high resolution of the seisrnic records for the targets vertically and laterally. In analysis of high resolution seismic reflection, Nyquist frequency($F_N$) should be lager than the highest frequency in the records and the highest wave number should not be exceed the Nyquist wave number($1/2{\Delta}x$). The highest frequency above the Nyquist will be removed using low pass filter or antialias filter. The trace interval Ax should be taken into account so that the highest wave number(f/v) can be less than $1/2{\Delta}x$. The Fraunhofer diffraction of a hyperbola seismic section above the tunnel appeares on the common offset method, and little first arrivals of direct wave on the single-end shooting, delayed strong impulsive reflections are also shown above the tunnel. Ray Method(Cherveney and Psencik, 1983) also represents the same results that the reflected waves from the tunnel are delayed and single impulsive with little first arrivals, while transrnitted waves through the tunnel are delayed with low frequency.

• Progress in Medical Physics
• /
• v.27 no.1
• /
• pp.31-36
• /
• 2016

The paper discusses radiation dose of dual energy CT on which copper modulation layer, is mounted in order to improve diagnostic performance of the dual energy CT. The radiation dose is estimated using MCNPX and its results are compared with that of the conventional dual energy CT system. CT X-ray spectra of 80 and 120 kVp, which are usually used for thorax, abdominal, head, and neck CT scans, were generated by the SPEC78 code and were used for the source specification 'SDEF' card for MCNPX dose modeling. The copper modulation layer was located 20 cm away from a source covering half of the X-ray window. The radiation dose was measured as changing its thickness from 0.5 to 2.0 mm at intervals of 0.5 mm. Since the MCNPX tally provides only normalized values to a single particle, the dose conversion coefficients of F6 tally for the modulation layer-based dual energy CBCT should be calculated for matching the modeling results into the actual dose. The dose conversion coefficient is $7.2*10^4cGy/output$ that is obtained from dose calibration curve between F6 tally and experimental results in which GAFCHORMIC EBT3 films were exposed by an already known source. Consequently, the dose of the modulation layer-based dual energy cone beam CT is 33~40% less than that of the single energy CT system. On the basis of the results, it is considered that scattered dose produced by the copper modulation layer is very small. It shows that the modulation layer-based dual energy CBCT system can effectively reduce radiation dose, which is the major disadvantage of established dual energy CT.