Si 종형 Hall 소자의 자기감도 개선

류지구 ( Ji Goo Ryu ),김남호 ( Nam Ho Kim ),정수태 ( Su Tae Chung ) 한국센서학회 2011 센서학회지 Vol.20 No.4

The silicon vertical hall devices are fabricated using a modified bipolar process. It consists of the thin p-layer at Si-SiO2¸ interface and n-epi layer without n+ buried layer to improve the sensitivity and influence of interface effects. Experimental samples are a sensor type I with and type H without p+isolation dam adjacent to the center current electrode. The experimental results for both type show a more high current-related sensitivity than the former`s vertical hall devices. The sensitivity of type H and type I are about 150 V/AT and 340 V/AT, respectively. This sensor`s behavior can be explained by the similar J-FET model.

자기센서용 Fe78B13Si9/PZT/Fe78B13Si9 적층구조 소자의 ME 특성

류지구 ( Ji Goo Ryu ),전성즙 ( Seong Jeub Jeon ) 한국센서학회 2015 센서학회지 Vol.24 No.3

The magnetoelectric characteristics on layered Fe(78)B(13)Si(9)/PZT and Fe(78)B(13)Si(9)/PZT/Fe78B13Si9(t(m)=0.017, 0.034mm) composites by epoxy bonding for magnetic field sensor were investigated in the low-frequency range and resonance frequency range. The optimal bias magnetic field H(dc) of these samples was about 23~63 Oe range. The Me coefficient of Fe(78)B(13)Si(9)/PZT/Fe78B13Si9(t(m)=0.034mm) com-posites reaches a maximum of 186 mV/cm·Oe at H(dc)=63 Oe, f=50 Hz and a maximum of 1280 mV/cm·Oe at H(dc)=63 Oe, resonance frequency f(r)=95.5 KHz. The output voltage shows linearity proportional to ac fields H(ac) and is about U=0~130.6 mV at H(ac)=0~7 Oe, f=50 Hz, U=0~12.4 V at H(ac)=0~10 Oe, f(r)=95.5 KHz(resonance frequency). The optimal frequency(f=50 Hz) of this sample is around the utility ac frequency(f=60 Hz). Therefore, this sample will allow for ac magnetic field sensor at utility frequency and low bias magnetic fields H(dc).

2 차원 Si 종형 Hall 소자의 자기감도 개선

류지구 ( Ji Goo Ryu ) 한국센서학회 2014 센서학회지 Vol.23 No.6

The 2-dimensional silicon vertical Hall devices, which are sensitive to X,Y components of the magnetic field parallel to the surface of the chip, are fabricated using a modified bipolar process. It consists of the thin p-layer at Si-SiO2 interface and n-epi layer to improve the sensitivity and influence of interface effect. Experimental samples are a sensor type K with and type J without p+ isolation dam adjacent to the center current electrode. The results for both type show a more high sensitivity than the former`s 2-dimensional vertical Hall devices and a good linearity. The measured non-linearity is about 0.8%. The sensitivity of type J and type K are about 66 V/AT and 200 V/AT, respectively. This sensor’ behavior can be explained by the similar J-FET model.

자기센서용 Ni-PZT-Ni, Co, Fe 적층구조 소자의 ME 특성

류지구,전성즙,Ryu, Ji-Goo,Jeon, Seong-Jeub 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.2

The magnetoelectric characteristics on layered Ni-PZT-Ni, Co, Fe composites by epoxy bonding for magnetic field sensor were investigated in the low-frequency range. The ME coefficient of Ni-PZT-Ni, Ni-PZT-Co and Ni-PZT-Fe composites reaches a maximum of $200mV/cm{\cdot}Oe$ at $H_{dc}=110$ Oe, $106mV/cm{\cdot}Oe$ at $H_{dc}=90$ Oe and $87mV/cm{\cdot}Oe$ at $H_{dc}=160$ Oe, respectively. A trend of ME charateristics on Ni-PZT-Co, Ni-PZT-Fe composites was similar to that of Ni-PZT-Ni composites. The ME output voltage shows linearly proportional to ac field $H_{ac}$ and is about 0~150 mV at $H_{ac}$=0~7 Oe and f=110 Hz in the typical Ni-PZT-Ni sample. The frequency shift effect due to the load resistance $R_L$ shows that the frequency range for magnetic field sensor application can be modulated with appropriate load resistance $R_L$. This sample will allow for a low-magnetic ac field sensor in the low-frequency (near f=110 Hz).

Si 종형 Hall 소자의 동작과 잡음 특성

류지구,김남호,Ryu, Ji-Goo,Kim, Nam-Ho 한국정보통신학회 2008 한국정보통신학회논문지 Vol.12 No.10

In this paper, the Si vertical Hall devices ale fabricated by using standard bipolar process and investigated in terms of the opeating and noise properties. The sensitivity of device with P+ isolation dam(type B) has been increased up to about 1.2 times compared to that device without the dam also noise has been increased. With the condition of f=I[KHz], band-width 1[Hz], the resolution of magnetic-field detection were about $0.97[{\mu}T]$/ type B and $1.25[{\mu}T]$/ type A, respectively, thus we must consider correlation the low noise or good resolution and high sensitivity in the situation for device geometry design or even for the materials. 본 연구는 칩 표면에 수평 한 자기장을 검출하는 종형 Hall 소자를 바이폴라 기술로 제조하여 동작 및 잡음 특성을 조사하였다. P+ Isolation 댐을 설치한 소자(type B)가 설치하지 않는 소자(type A)보다 자기 감도는 약 1.2배 증가하였고, 역시 잡음도 증가하였다. 측정된 이 종형 Hall소자의 자기 검출 분해능은 f=1[KHz], 대역폭 1[Hz] 구동조건에서 type A는 약 $0.97[{\mu}T]$, type B는 $1.25[{\mu}T]$였다. 따라서 Hall 소자 구조 설계나 재료적인 면에서 볼 때, 낮은 잡음즉, 자기 검출분해능과 높은 감도 상관관계를 고려하여야 한다.

ME 소자의 저주파 등가회로 모델링

정수태,류지구,Chung, Su-Tae,Ryu, Ji-Goo 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.7

Magnetoelectric(ME) bulk composites with PZT-PNN-PZN/$Fe_2O_4$ were prepared by using a conventional ceramic methods and investigated on the ME voltage vs frequency of ac magnetic fields. We made the electric equivalent circuits by using the Maxwell-Wagner model and simulated the frequency dependence of ME voltage in low frequency region. ME devices were described by a series of two equivalent circuits of piezoelectric and magnetic, which have the relaxation time ${\tau}$ due to the interaction between ME device and load resistor. Equivalent circuit of piezoelectric material is independent of frequency. However ferrite magnetic materials have Debye absorption and dipolar dispersion, whose equivalent circuit is a function of frequency. Therefore we suggest the resistance in the equivalent circuit is proportion to $1+{\omega}^2{\tau}^2$ and the capacitance is in inverse proportion to $1+{\omega}^2{\tau}^2$ in the magnetic materials.

CMOS 공정을 이용한 2차원 SSIMT의 특성

송윤귀,류지구,Song, Youn-Gui,Ryu, Ji-Goo 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.8

A novel 2-Dimensional Suppressed Sidewall Injection Magnetotransistor (SSIMT) with high linearity has been fabricated on the standard CMOS technology and experimentally verified. The novel 2-Dimensional SSIMT overcomes the restriction of the standard CMOS technology. Experimental results of the fabricated 2-Dimensional SSIMT show that the variation of each collector output currents are extremely linear as a function of magnetic field from -200mT to 200mT at $I_B = 1 mA,\;V_{CE} = 5 V\;and\;V_{SE} = 5 V$. The relative sensitivity shows up to 13 %/T. The measured nonlinearity of the fabricated device is about 0.9%.

웨이브렛 변환을 이용한 훼손된 신호의 복원에 관한 연구

김남호,배상범,류지구,Kim Nam-Ho,Bae Sang-Bum,Ryu Ji-Goo 한국융합신호처리학회 2005 융합신호처리학회 논문지 (JISPS) Vol.6 No.1

데이터를 디지털화하거나 전송하는 과정에서 여러 가지 원인에 의해 열화가 발생하고 있으며, 이러한 열화의 주된 원인은 잡음이다. 따라서 잡음에 의해 훼손된 신호를 복원하기 위하여 웨이브렛을 이용한 방법들에 대한 연구가 활발히 진행되고 있다. 그리고 AWGN 환경에서 잡음을 제거하기 위한 가장 일반적인 연구 동향은 threshold에 기초한 방법들이다. 그러나 이러한 방법은 잡음에 대한 통계적인 특징만을 고려함에 따라 복원된 신호는 여전히 많은 잡음들을 포함한다. 따라서 본 논문에서는 웨이브렛 상세계수의 누적을 통한 새로운 신호 복원 방법을 제시하여, 신호의 edge 성분에 대한 복원과 잡음 제거 성능을 향상시켰다. 그리고 개선 효과의 판단 기준으로 SNR을 사용하였으며, 객관적인 판단을 위해 기존의 방법들과 비교하였다. Degradation is generated by several causes in the process of digitalization or transmission of data. And its essential cause is noise. Therefore, researches for wavelet-based methods which reconstruct signal degraded by noise have continued. In AWGN(addtive white gaussian noise) environment, the general trend for denoising is to use the thresholding method. Reconstructed signal includes a lot of noise because these methods only consider statistical characteristic regarding noise. In this paper, we present a new method which uses the cumulation of wavelet detail coefficients. As a result, reconstruction of edges and denoising performance are improved. Also we compare existing methods using SNR(signal-to-noise ratio) as the standard of judgement of improvemental effect.

(1-x) [0.5PZT-0.25PNN-0.25PZN]- x [Ni_0.9Zn_0.1Fe₂O₄] 세라믹스의 압전/자성 성질 및 자기전기적 효과

박영권,손세모,류지구,정수태,Park, Young-Kwon,Son, Se-Mo,Ryu, Ji-Goo,Chung, Su-Tae 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.11

Magnetoelectric composites with compositions (1-x)[0.5PZT-0.25PNN-0.25PZN](ferroelectric) - x[$(Ni_{0.9}Zn_{0.1})Fe_2O_4$](ferrite) in which x varies as 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 were prepared by conventional ceramic process. The presence of two phases (ferroelectric phase with large grain and ferrite phase with small grain) in the particulate ceramic composites was confirmed by XRD, SEM and EDX. The ferroelectric and magnetic properties of the composites were studied by measuring the P-E and M-H hysterisis loop on the composite composition (x=0, 0.1, 0.2, 1), they were strongly affects of the phase content in composite. The magnetoelectric votage was measured as a function of DC magnetic field and the maximum magnetoelectric voltage coefficient of 14 mV/cm Oe was observed in x=0.2(80 mol% ferroelectric and 20 mol% ferrite phase).

YCbCr칼라 모델에서 화재의 움직임 정보를 이용한 화재검출 알고리즘

박봉희(Feng-Ji Piao),류지구(Ji-Goo Ryu),문광석(Kwang-Seok Moon),김종남(Jong-Nam Kim) 한국멀티미디어학회 2010 한국멀티미디어학회 학술발표논문집 Vol.2010 No.2

본 논문에서는 화재검출을 위하여 카메라 입력영상으로부터 화재의 특징을 이용하여 화재영역을 검출하는 알고리즘을 제안하였다. 제안하는 화재검출 방법은 영상에서 움직임 객체를 찾는 것으로 1차적인 화재영역을 검출하고 다음 영상이 RGB칼라모델이 아닌 YCbCr칼라 공간에서 각 성분의 칼라정보를 이용하여 2차적인 화재영역을 검출하였으며 마지막으로 화재의 외부 경계추출, 노이즈 제거 등의 영역해석을 수행함으로써 화재영역를 검출한다. 실험결과 이전의 비전기반 화재 감지 기법에 비해서 좋은 결과를 나타내는 것을 볼수 있다.