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오실로메트릭 혈압 측정에서 커패시턴스 센서와 적응필터를 이용한 새로운 잡음제거방법에 관한 연구
최현석,박호동,이경중,Choi, Hyun-Seok,Park, Ho-Dong,Lee, Kyoung-Joung 대한의용생체공학회 2008 의공학회지 Vol.29 No.3
In this study, a new method using a capacitive sensor and an adaptive filter was proposed to deal with artifacts contaminating an oscillation signal in oscilometric blood pressure measurement. The proposed method makes use of a variation of the capacitance between an electrode fixed to a cuff and an external object to detect artifacts caused by the external object bumping into the cuff. The proposed method utilizes the adaptive filter based on linear prediction to remove the detected artifacts. The conventional method using linear interpolation and the proposed method using the adaptive filter were applied to three types of the artifact-contaminated oscillation signals(no overlap, non-consecutive overlap, and consecutive overlap between artifacts and oscillations) to compare them in terms of the artifact reduction performance. The proposed method was more robust than the conventional method in the case of consecutive overlap between artifacts and oscillations. The proposed method could be useful for measuring blood pressure in such a noisy environment that the subject is being transported.
장봉렬,박호동,이경중,Jang, Bong-Ryeol,Park, Ho-Dong,Lee, Kyoung-Joung 대한의용생체공학회 2007 의공학회지 Vol.28 No.1
MR(magnetic resonance) image of moving organ such as heart shows serious distortion of MR image due to motion itself. To eliminate motion artifacts, MRI(magnetic resonance imaging) scan sequences requires a trigger pulse like ECG(electro-cardiography) R-wave. ECG-gating using cardiac cycle synchronizes the MRI sequence acquisition to the R-wave in order to eliminate image motion artifacts. In this paper, we designed ECG/PPG(photo-plethysmography) gating system which is for eliminating motion artifacts due to moving organ. This system uses nonmagnetic carbon electrodes, lead wire and shield case for minimizing RF(radio-frequency) pulse and gradient effect. Also, we developed a ECG circuit for preventing saturation by magnetic field and a finger plethysmography sensor using optic fiber. And then, gating pulse is generated by adaptive filtering based on NLMS(normalized least mean square) algorithm. To evaluate the developed system, we measured and compared MR imaging of heart and neck with and without ECG/PPG gating system. As a result, we could get a clean image to be used in clinically. In conclusion, the designed ECG/PPG gating system could be useful method when we get MR imaging of moving organ like a heart.
Co계 자성합금 나노와이어의 특성에 영향을 미치는 전기화학적 변수
이종욱,박호동,이관희,김긍호,정원용,Lee, Jong-Wook,Park, Ho-Dong,Lee, Kwan-Hyi,Kim, Gyeung-Ho,Jeung, Won-Young 한국전기화학회 2005 한국전기화학회지 Vol.8 No.3
본 연구에서는 고순도 알루미늄 호일$(t=300{\mu}m)$양극산화 공정을 통해 AAO 나노템플레이트를 자체 제조하였고, 이렇게 제조된 형틀을 가지고 교류 나노전주법에 의해 경자성 합금인 CoP와 연자성 합금인 CoFe를 나노와이어로 제조하였다. 대표적인 Co계 자성합금인 CoP와 CoFe나노와이어는 각기 독특한 자기적 성질을 나타내었다. 경자성 CoP 합금 나노와이어의 경우 교류 인가전압에 따라 hcp와 fcc가 혼재된 구조가 형성되어 자기적 특성에 영향을 미쳤다. 또한 높은 포화자화 값을 갖는 CoFe연자성 합금 나노와이어는 박막 도금 시와는 달리 이상합금도금현상이 거의 나타나지 않았으며 $Co_{30}Fe_{70}$에서 가장 좋은 238emu/g의 포화자화 값을 나타내었다. We have investigated the electrochemical factors affecting the magnetic properties of hard magnetic CoP nanowires and soft magnetic CoFe nanowires fabricated by ac electrodeposition into self-made AAO(anodic aluminum oxide) nano-templates. AAO template having nano scale pores of high aspect ratio has been prepared through 2-step anodizing of aluminum foil in sulfuric acid. Hard Magnetic properties of CoP nanowires were highly conditional on the applied ac potential which could be a decisive factor to make CoP nanowires made up of either pure hcp crystals or a mixture of hop crystals and fcc crystals. On the contrary to CoFe films, there was no anomalous codeposition in the electrodeposition of soft magnetic CoFe nanowires which exhibited their best saturation magnetization of 238 emu/g at the composition of $Co_{30}Fe_{70}$.
III-V족 화합물 반도체 InSb 나노와이어의 전기화학적 합성 및 특성 평가
이관희,이종욱,박호동,정원용,이종엽,Lee, Kwan-Hyi,Lee, Jong-Wook,Park, Ho-Dong,Jeung, Won-Young,Lee, Jong-Yup 한국전기화학회 2005 한국전기화학회지 Vol.8 No.3
본 연구에서는 그동안 전기화학적으로 합성되지 못했던 III-V족 화합물 반도체 InSb를 구연산 용액으로부터 합성하였으며 자체 제조한 AAO를 나노템플릿으로 이용하여 정전압 도금을 실시하여 InSb 나노와이어를 제조하였다 제조된 InSb나노와이어는 X선 회절분석 결과 단결정의 나노와이어는 아니었으나 정확하게 화학양론을 만족시키는 화합물임을 확인하였고, 평판 박막 상태의 InSb와는 달리 나노와이어의 길이방향으로 (220) 방향의 결정이 주로 성장하는 우선결정방위를 가지고 있음을 알 수 있었다. 또한 집합적으로 배열된 상태에서 측정된 I-V특성 곡선에서는 n형 반도체의 특성을 보이되 밴드갭이 좁고, 전자이동도가 큰 InSb고유의 특성상 반금속과 유사한 전기적 특성을 보유하고 있음을 확인하였다. To the best knowledge, the formation and characterization of InSb nanowires have not been reported yet in spite of its good characteristics as a III-V compound semiconductor. The nanowire arrays were potentiostatically electrodeposited in a mixing solution of indium chloride, antimony chloride, citric acid, and potassium citrate according to our previous work on the electrodeposition of the stoichiometric InSb films. The electrical properties of nanowire arrays were measured by semiconductor parameter analyzer, and the microstructural analysis of the nanowires was conducted by employing XRD. Our experimental results indicate that the InSb nanowires have a highly preferred orientation of (220) direction and also exhibit electrical characteristics of n-type semiconductors which we, however, similar to semi-metals mainly due to their narrow band-gap and high electron mobility.
분체 이송관내 압력 조절을 위한 오리피스 주위에서의 입자 유동 및 마모 해석
조형희,이재근,박호동,서태원,Cho, Hyung-Hee,Lee, Jae-Keun,Park, Ho-Dong,Seo, Tae-Won 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.11
A numerical study is performed to investigate pressure drops, particle trajectories and erosion around orifice plates in pulverized coal pipe lines. Particle impaction rates change significantly with orifice shapes and Stokes numbers. At Reynolds number of $5{\times}10^5$, the pulverized coal flows well with streamlines and do not collide at the orifice plates at small sizes (${\sim}20{\mu}m$). However, the large particles (over $70{\mu}m$) impact on the front face of the orifice and erode the orifice surface. The pressure loss coefficients around the erode orifice are largely different from the designed original orifice.
도플러 레이더와 에어 매트리스를 이용한 무구속 방식의 신생아 감시 장치 설계
양성수,조성필,박호동,이경중,Yang, Seong-Soo,Cho, Sung-Pil,Park, Ho-Dong,Lee, Kyoung-Joung 대한의용생체공학회 2014 의공학회지 Vol.35 No.6
Continuous monitoring of heart rates and respiratory rates for newborns or infants is very important since the abnormal breathing and heart problems can threaten the life of newborns or infants. A noncontact baby monitoring system based on a Doppler radar and an air mattress was designed. The Doppler radar was used to acquire respiratory signals and the air mattress was employed to obtain heart rates. The performance of the designed system was evaluated using a commercialized infant simulator ($Simbaby^{TM}$) and a respiration belt transducer was used to measure respiration rates as a reference. Results for respiratory rates revealed that the correlation coefficients between I-and Q-channel and the respiration belt were 0.84 and 0.91 and the mean ${\pm}$ standard deviations of errors between them were $1.66{\pm}1.92$ (bpm) and $0.88{\pm}1.65$ (bpm). Heart rates showed that the correlation coefficient between air mattress and set value of the simulator was 0.73 and the mean ${\pm}$ standard deviation of errors between them was $1.09{\pm}3.45$ (bpm). These results indicate that the designed system holds the potential as an effective monitoring tool for continuous monitoring heart rates and respiratory rates of newborns or infants.
김범철,김은경,표동진,박호동,허우명 ( Bom Chul Kim,En Kyong Kim,Dong Jin Pyo,Ho Dong Park,Woo Myung Heo ) 한국물환경학회 1995 한국물환경학회지 Vol.11 No.3
Cyanobacterial blooms in eutrophic lakes often produce algal toxins causing death of cattle, wild animals, and fish. Many lakes and reservoirs in Korea are eutrophic and suspected for toxic cyanobacterial blooms. Phytoplankton were collected in late summer at the surface of 5 middle-stream reservoirs(Soyang, Choongju, Daechong, Jangsong, Hapchon), one estuarine reservoir(Yongsan), and a coastal lagoon(Yonglang). Phytoplankton communities were examined and the occurrence of toxic bloom was examined with mouse bioassay. In all the study lakes cyanobacteria were dominant phytoplankton. Especially, the appearance of Microcystis aeruginosa in all the study lakes that is a well-known toxin-producer species implies the possibility of toxic water bloom. Dried cells were extracted in saline solution and injected to mouse intraperitoneally for the test of toxicity. Mouse bioassay showed lethal effect for L. Yonglang, L. Hapchon, L. Jangsong, and L. Yongsan. The content of two cyanobacterial hepatotoxins(microcystin-RR and microcystin-LR) that have been reported to be most common were analyzed with HPLC. Microcystin-RR was detected in L. Daechong, L. Choongju, and L. Soyang. And microcystin-LR which has higher toxcicity was detected in L. Hapchon, L. Jangsong, L. Yonglang, and L. Yongsan. The coincidence of the microcystin-LR occurrence and the lethal effect in bioassay imply that microcystin-LR exerted more critical toxicity. From this study it was found that toxic cyanobacterial bloom is common in Korean lakes that are used for water supply.
최현석(Hyun-Seok Choi),박호동(Ho-Dong Park),이경중(Kyoung-Joung Lee) 대한전기학회 2008 정보 및 제어 심포지엄 논문집 Vol.2008 No.1
오실로메트릭 방법으로 휴대용 혈압 측정 시 빈번하게 발생하는 잡음에 의한 오실레이션 신호의 왜곡을 줄이기 위해 새로운 잡음 제거 알고리즘을 제안하였다. 제안된 잡음 제거 알고리즘은 선형 예측기 구조 기반의 적용 필터를 이용한다. 제안된 잡음 제거 알고리즘의 성능을 평가하기 위해 왜곡된 오실레이션 신호에 선형 보간법을 사용하는 기존의 방법과 적용 필터를 사용하는 제안된 방법을 적용하여 잡음 제거 성능을 비교하였다. 제안된 방법은 잡음이 오실레이션과 중첩되어 나타난 경우에 기존의 방법과 달리 잡음에 강인한 특징을 보여주었다.