• PNF and Movement
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• 제12권3호
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• pp.143-150
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• 2014

Purpose: The corticospinal tract (CST) is known to be an important pyramidal tract for walking and motor function. However, very little is known about the functional role of the CST in the recovery of motor function. In the current study, we investigated the relation between the CST and motor function in chronic hemiparetic stroke patients. Methods: Fifty-four patients and 20 normal subjects were recruited. The Functional Ambulation Category (FAC) was used in measurement of the walking ability. We classified patients into three groups according to the ability to walk independently: group A, patients who could not walk independently (FAC: 0-2); group B, patients who could walk independently (FAC: 3); and group C, patd walk functionally (stairs and uneven surfaces, FAC 4-5). The Motricity Index (MI) was used to measure the motor function of the affected upper and lower extremities (maximum score: 100). The fractional anisotropy (FA) value, apparent diffusion coefficient (ADC) value, and fiber volume of the CST were used for the diffusion tensor imaging (DTI) parameters. Results: In terms of the CST of the unaffected hemisphere, the FA value of group A was significantly lower than that of normal controls (p <0.05). The fiber volume of group C was significantly higher than that of normal controls (p <0.05). In contrast, the ADC values of all patient groups and the control group did not show any difference (p >0.05). In terms of lower MI and total MI, significant differences were observed between all patient groups (p <0.05). In addition, significant differences in terms of the upper MI scores were observed between groups A and C and between groups B and C (p <0.05); however, no significant difference was observed between groups A and B (p>0.05). Conclusion: The increased fiber volume of the CST in the unaffected hemisphere appears to be related to functional walking ability in chronic stroke patients. This result would be useful for elucidation of the neural recovery mechanism of walking and the investigation of new modalities for the recovery of walking following a stroke with CST injury.

• Investigative Magnetic Resonance Imaging
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• 제21권3호
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• pp.162-170
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• 2017

Purpose: To evaluate the imaging findings of desmoid tumors using various imaging modalities and to evaluate whether diffusion-weighted imaging (DWI) can help differentiate between desmoid and malignant tumors. Materials and Methods: The study included 27 patients with pathologically confirmed desmoid tumors. Two radiologists reviewed 23 computed tomography (CT), 12 magnetic resonance imaging (MRI) and 8 positron emission tomography-computed tomography (PET-CT) scans of desmoid tumors and recorded data regarding the shape, multiplicity, size, location, degree of enhancement, and presence or absence of calcification or hemorrhage. The signal intensity of masses on T1- and T2-weighted imaging and the presence or absence of whirling or band-like low signal intensity on T2-weighted imaging were recorded. The apparent diffusion coefficient (ADC) values of the desmoid tumors in nine patients with DWIs were compared with the ADC values of 32 malignant tumors. The maximum standardized uptake value ($SUV_{max}$) on PET-CT images was measured in 8 patients who underwent a PET-CT. Results: The mean size of the 27 tumors was 6.77 cm (range, 2.5-26 cm) and four tumors exhibited multiplicity. The desmoid tumors were classified by shape as either mass forming (n = 18), infiltrative (n = 4), or combined (n = 5). The location of the tumors was either intra-abdominal (n = 15), within the abdominal wall (n = 8) or extra-abdominal (n = 4). Among the 27 tumors, 21 showed moderate to marked enhancement and 22 showed homogeneous enhancement. Two tumors showed calcifications and one displayed hemorrhage. Eleven of the 12 MR T2-weighted images showed whirling or band-like low signal intensity areas in the mass. The mean ADC value of the desmoid tumors ($1493{\times}10^{-6}mm^2/s$) was significantly higher than the mean of the malignant soft tissue tumors ($873{\times}10^{-6}mm^2/s$, P < 0.001). On the PET-CT images, all tumors exhibited an intermediate $SUV_{max}$ (mean, 3.7; range, 2.3-4.5). Conclusion: Desmoids tumors showed homogenous, moderate to marked enhancement on CT and MRI scans and a characteristic whirling or band-like pattern on T2-weighted images. DWI can be useful for the differentiation of desmoid tumors from malignant soft tissue tumors.

• 전기전자학회논문지
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• 제22권4호
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• pp.1012-1018
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• 2018

본 논문에서는 IoT 센서 처리를 위한 1.8V 공급전압의 CMOS SAR(Successive Approximation Register) A/D 변환기를 설계하였다. 본 논문에서 2개의 A/D 변환기를 병렬로 사용하여 샘플링 속도를 향상시킨 12비트 SAR A/D 변환기를 제안한다. 2개의 A/D 변환기 중 1개의 A/D 변환기는 12자리 비트를 모두 결정하고, 또 다른 A/D 변환기는 다른 A/D 변환기의 상위 6비트를 그대로 사용하여 전력소모와 스위칭 에너지를 최소화하였다. 두 번째 A/D 변환기는 상위 6비트를 결정하지 않기 때문에 컨트롤 회로와 SAR 로직이 필요하지 않아 면적을 최소화하였다. 또한 스위칭 에너지는 커패시터 용량과 C-DAC 내 전압 변화가 클수록 값이 커지는데 두 번째 A/D 변환기는 상위 6비트를 결정하지 않아 스위칭 에너지를 줄일 수 있다. 또한 커패시터 내 스플릿 커패시터 용량을 유닛 커패시터 용량과 동일하게 회로를 구성하여 C-DAC 내 공정오차를 줄일 수 있다. 제안하는 SAR A/D 변환기는 180nm CMOS 공정을 이용하여 설계하였고, 1.8V의 공급전압, 10MS/s의 변환속도, 10.2비트의 ENOB(Effective Number of Bit)이 측정되었다. 핵심 블록의 면적은 $600{\times}900um^2$, 총 전력소모는 $79.58{\mu}W$, FoM(Figure of Merit)는 6.716fJ/step로 확인할 수 있다.

• 한국전자파학회논문지
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• 제29권12호
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• pp.986-991
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• 2018

본 논문은 광대역 디지털 수신기의 동적 범위 개선을 위한 A/D 변환 모듈을 설계 및 제작하였다. 동적 범위 확장을 위한 A/D 변환 모듈은 입력신호 레벨에 따라 정상 경로와 증폭 경로로 신호를 분기하여 디지털 신호로 변환하는 방식이다. 제작 및 측정 결과, A/D 변환 모듈의 정상 경로는 입력 레벨 -57 dBm~-12 dBm 신호를 디지털 신호로 변환하고, 증폭 경로는 입력 레벨 -30 dBm~+12 dBm 신호를 왜곡 없이 디지털 신호로 변환하여 69 dB의 입력 동적 범위 특성을 나타내었다. 또한 순시 대역폭 100 MHz에서 일정한 출력 특성을 나타내고 있음을 확인하였다.

• Korean Journal of Radiology
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• 제23권5호
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• pp.539-547
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• 2022

Objective: To investigate the association between functional tumor burden of peritoneal carcinomatosis (PC) derived from diffusion-weighted imaging (DWI) and overall survival in patients with advanced ovarian carcinoma (OC). Materials and Methods: This prospective study was approved by the local research ethics committee, and informed consent was obtained. Fifty patients (mean age ± standard deviation, 57 ± 12 years) with stage III-IV OC scheduled for primary or interval debulking surgery (IDS) were recruited between June 2016 and December 2021. DWI (b values: 0, 400, and 800 s/mm²) was acquired with a 16-channel phased-array torso coil. The functional PC burden on DWI was derived based on K-means clustering to discard fat, air, and normal tissue. A score similar to the surgical peritoneal cancer index was assigned to each abdominopelvic region, with additional scores assigned to the involvement of critical sites, denoted as the functional peritoneal cancer index (fPCI). The apparent diffusion coefficient (ADC) of the largest lesion was calculated. Patients were dichotomized by immediate surgical outcome into high- and low-risk groups (with and without residual disease, respectively) with subsequent survival analysis using the Kaplan-Meier curve and log-rank test. Multivariable Cox proportional hazards regression was used to evaluate the association between DWI-derived results and overall survival. Results: Fifteen (30.0%) patients underwent primary debulking surgery, and 35 (70.0%) patients received neoadjuvant chemotherapy followed by IDS. Complete tumor debulking was achieved in 32 patients. Patients with residual disease after debulking surgery had reduced overall survival (p = 0.043). The fPCI/ADC was negatively associated with overall survival when accounted for clinicopathological information with a hazard ratio of 1.254 for high fPCI/ADC (95% confidence interval, 1.007-1.560; p = 0.043). Conclusion: A high DWI-derived functional tumor burden was associated with decreased overall survival in patients with advanced OC.

• 한국통신학회논문지
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• 제34권12C호
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• pp.1131-1137
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• 2009

본 논문에서는 OFDMA 기반의 디지털 이중화 방식을 위한 자원 관리 기법을 제안한다. 제안된 자원 관리 기법은 CS(Cyclic Suffix)를 사용하지 않으면서 TDoA(Time Difference of Arrival)에 의한 ISI(Inter Symbol Interference)와 ICI(Inter Carrier Interference)의 영향을 최소화 하며, SS(Subscriber Station)에 수신되는 신호의 dynamic range를 줄인다. 제안된 자원 관리 기법은 ADC(Analog to Digital Converter)의 비트 수를 줄이며, SINR(Signal to Interference and Noise Ratio)를 크게 향상시킴을 모의실험을 통하여 확인한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.538-540
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• 2004

Electrical currents generated by human heart activities create magnetic fields represented by MCG(MagnetoCardioGram). Since an MCG signal acquisition system requires precise and stable operation, the system adopts hundreds of SQUID(Superconducting QUantum Interface Device) sensors for signal acquisition. Such a system requires fast real-time data acquisition in a required sampling interval, i.e., 1 mili-second for each sensor. This paper presents designed hardware to acquire data from 256-channel analog signal with 1 ksamples/sec speed, using 12-bit 8-channel ADC devices, SPI interfaces, parallel interfaces, 8-bit microprocessors, and a DSP processor. We implemented SPI interface between ADCs and a microprocessor, parallel interfaces between microprocessors. Our result concludes that the data collection can be done in $168{\mu}sec$ time-interval for 256 SQUID sensors, which can be interpreted to 6 ksamples/sec speed.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.170-170
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• 2001

Purpose： To evaluate the relationship between reperfusion hyperemia in reversible cerebral ischem and the degree of programmed cell death. Method： We produced the animal models of reversible cerebral ischemia in 10 cats by mean of middle cerebral artery (MCA) occlusion with transorbital approach. MCA was occluded b microvascular clamp for an hour. MR imaging was performed at 0, 1, 2 days after ischemi and reperfusion. Perfusion (PWI) [Contrast enhanced GRE EPI, TR/TE= 1500/40, 40 Phases, 128 matrix, 12 cm FOV] and diffusion (DWI) (SE EPI, b=0, 500, 1000) weighted images were obtained using Philips Intera 1.57 system. rCBV and ADC maps were calculated wi IDL based postprocessing program. Tissue slices were obtained after the last MR imagin TUNEL, Calbin and Acid-Fuscin staining were done for corresponding slices as MR imagin We investigated the differences of degree of apoptosis in the area of reperfusion hyperemia.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.444-447
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• 2004

A heart diagnosis system adopts hundreds of Superconducting Quantum Interface Device(SQUID) sensors for precision MCG(Magnetocardiogram) or MEG(Magnetoencephalogram) signal acquisitions. This system requires correct and real-time data acquisition from the sensors in a required sampling interval, i.e., 1 mili-second. This paper presents our hardware design and test results, to acquire data from 256 channel analog signal with 1-ksample/sec speed, using 12-bit 8-channel ADC devices, SPI interfaces, parallel interfaces, and 8-bit microprocessors. We chose to implement parallel data transfer between microprocessors as an effective way of achieving such data collection. Our result concludes that the data collection can be done in 250 ${\mu}sec$ time-interval.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.953-955
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• 2014

최근 차량 충돌 방지를 위한 다양한 기술이 상용화되고 있다. FMCW 기반의 레이더 시스템은 구현의 용이성으로 많은 상용차에서 전면 충돌 방지 시스템에 적용되고 있다. 측면 충돌 방지를 위한 BSD(Blind Spot Detection)와 차선변경 보조 시스템(LCA, Lane Change Assistant system)에서는 전방 레이더보다 인식거리가 줄어들고 갱신율이 낮아지므로 고속 FFT 등을 수행하는 신호처리부를 저가격으로 설계가 가능할 것이다. 본 연구에서는 TI사의 MCU인 F28335를 사용하여 근거리를 인식하는 신호처리부를 설계하였다. 이 MCU는 16채널 12bit ADC와 68KB RAM 및 512KB 플래시 메모리를 내장하고, 150MHz 부동소수점 연산을 지원하여 단일 칩으로 신호처리부의 구현이 가능하다. 구현된 시스템은 20m내외의 거리에 있는 장애물에 대하여 10Hz로 갱신이 가능하여 BSD를 위한 기본 기능이 확인되었다. 이러한 구현은 이전의 고가의 DSP나 FPGA를 사용하지 않고 15$이내의 단일 MCU와 간단한 아날로그 회로로 설계되어 저가격의 시스템으로 상용화가 가능할 것이다.