• Journal of the Korean Society of Radiology
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• v.85 no.3
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• pp.607-617
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• 2024

Purpose Recent studies have demonstrated the usefulness of diffusion-weighted MR neurography (DW MRN) for assessing nerve roots. This study aimed to evaluate the utility of DW MRN with a unidirectional motion-probing gradient (MPG) for the lumbar nerve roots at 1.5T MR. Materials and Methods Sixty-four lumbar spine MRI scans with DW MRN using anteroposterior unidirectional MPG were retrospectively analyzed. Any changes in the 512 lumbar spinal nerve roots from L3 to S1 were evaluated using T2-weighted imaging (T2WI), contrast-enhanced T1-weighted imaging (CE T1WI), and DW MRN, with agreement and correlation analysis. Results T2WI revealed compression of 78 nerve roots, and CE T1WI revealed 52 instances of nerve root enhancement. Sixty-seven nerve roots showed swelling and hyperintensity on DW MRN. A total of 42 nerve roots showed changes in the CE T1WI and DW MRN sequences. Moderate to substantial agreement and moderate positive correlation were observed between DW MRN and CE T1WI, as well as DW MRN and T2WI (κ = 0.59-0.65, ρ = 0.600-0.653). Conclusion DW MRN with unidirectional anteroposterior MPG can help evaluate neuritisrelated changes in spinal nerve roots and could serve as a sequence capable of complementing or substituting gadolinium CE imaging.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.35-38
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• 2018

This paper describes a low-power MPPT interface for DC-type energy harvesting sources. The proposed circuit consists of an MPPT controller, a bias generator, and a voltage detector. The MPPT controller consists of an MPG (MPPT Pulse Generator) with a schmitt trigger, a logic gate operating according to energy type (light, heat), and a sample/hold circuit. The bias generator is designed by employing a beta multiplier structure, and the voltage detector is implemented using a bulk-driven comparator and a two-stage buffer. The proposed circuit is designed with $0.35{\mu}m$ CMOS process. The simulation results show that the designed circuit consumes less than 100nA of current at an input voltage of less than 3V and the maximum power efficiency is 99.7%. The chip area of the designed circuit is $1151{\mu}m{\times}940{\mu}m$.

• Tissue Engineering and Regenerative Medicine
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• v.15 no.6
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• pp.711-719
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• 2018

BACKGROUND: Collagen organization within tissues has a critical role in wound regeneration. Collagen fibril diameter, arrangements and maturity between connective tissue growth factor (CTGF) small interfering RNA (siRNA) and mismatch scrambled siRNA-treated wound were compared to evaluate the efficacy of CTGF siRNA as a future implement for scar preventive medicine. METHODS: Nanocomplexes of CTGF small interfering RNA (CTGF siRNA) with cell penetrating peptides (KALA and $MPG^{{\Delta}NLS}$) were formulated and their effects on CTGF downregulation, collagen fibril diameter and arrangement were investigated. Various ratios of CTGF siRNA and peptide complexes were prepared and down-regulation were evaluated by immunoblot analysis. Control and CTGF siRNA modified cells-populated collagen lattices were prepared and rates of contraction measured. Collagen organization in rabbit ear 8 mm biopsy punch wound at 1 day to 8 wks post injury time were investigated by transmission electron microscopy and histology was investigated with Olympus System and TS-Auto software. CONCLUSION: CTGF expression was down-regulated to 40% of control by CTGF siRNA/KALA (1:24) complexes (p<0.01) and collagen lattice contraction was inhibited. However, down-regulated of CTGF by CTGF $siRNA/MPG^{{\Delta}NLS}$ complexes was not statistically significant. CTGF KALA-treated wound appeared with well formed-basket weave pattern of collagen fibrils with mean diameter of $128{\pm}22nm$ (n = 821). Mismatch siRNA/KALA-treated wound showed a high frequency of parallel small diameter fibrils (mean $90{\pm}20nm$, n = 563). CONCLUSION: Controlling over-expression of CTGF by peptide-mediated siRNA delivery could improve the collagen orientation and tissue remodeling in full thickness rabbit ear wound.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.282-283
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• 2006

The transport phenomena of arsenic (As) doped amorphous selenium(a-Se:As) thin film for digital X-ray conversion material has been reported. The effect of As addition on the carrier mobility and recombination lifetime in a-Se:As sample has been measured using the moving photo-carrier grating (MPG) technique. An Increase in hole mobility and recombination was observed when 0.3% arsenic, was added into a-Se sample, whereas electron mobility decrease with arsenic addition due to the defect density. The fabricated a-Se:03% As device exhibited the highest X-ray sensitivity.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.957-959
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• 1999

In this paper we proposed a new fuzzy modeling method by Fuzzy Equalization(FE) based on probability theory. FE concerns a process of building membership function without learning using back-propagation of neural network. Therefore, we compare the proposed method with Adaptive Network-based Inference System based on hybrid learning. Finally, we will show better performance and its usefulness for a new fuzzy modeling to automobile mpg prediction.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1401-1402
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• 2015

급작스레 발병하는 혈관 질환으로 인해 실시간 혈압 추정 연구가 많이 진행되어지고 있다. 본 논문에서는 자기장을 이용하여 혈압을 추정할 수 있는 자계용적맥파 시스템을 개발하였다. 자기장을 이용한 방법은 온도에 강하며 혈류와 상관성이 있기에 사용하였다. 혈압 추정의 과정은 총 3부분 나눌 수 있다. MPG측정, ECG측정 그리고 신호처리 부분이며 신호처리는 PC에서 디지털 필터링 및 PTT 계산을 실시하게 된다. 비교 기준 혈압으로 Omron 혈압계를 사용하여 동시 측정하였으며 결과로 각 PTT간 기준 수축기 및 이완기 혈압을 비교 할 수 있었다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1399-1400
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• 2015

광용적맥파는 인체 내에 흐르는 혈류의 움직임을 빛을 이용하여 관찰 및 측정하며, 자계용적맥파는 코일 주변에 발생하는 자기장을 이용하여 신호를 측정한다. 본 논문에서는 매질별 광용적맥파형과 자계용적맥파형을 혈류 시뮬레이터를 이용하여 비교하였다. 혈류 시뮬레이터의 출력파형은 동맥혈압파형으로 설정하여 실험을 진행하였다. 매질은 음용수와 식염수를 이용하였으며, 매질별 광용적맥파형의 변화는 거의 드러나지 않았으나 자계용적맥파의 파형은 변화가 있음을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.47-48
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• 2005

The moving photocarrier grating(MPG) technique for the determination of the carrier mobilities and the recombination lifetime in a-Se:As films have been studied. The electron and hole drift mobility and the recombination lifetime of a-Se films with arsenic (As) additions have been obtained. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film. However, the electron mobility exhibits no observable change up to 0.5% As addition in a-Se films.0.3% As added a-Se film also exhibits the maximum short circuit current densities per laser intensity of $5.29\times10^{-7}$ A/W.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.252-253
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• 2005

The effects of As addition in amorphous selenium (a-Se) films on the carrier mobilities and the recombination lifetime have been studied using the moving photo-carrier grating (MPG) measurements. The electron and hole mobility, and recombination lifetime of a-Se films with arsenic (As) additions up to 1% have been obtained. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density from shallow traps.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 1998.07a
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• pp.27-28
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• 1998

Whole body (fetus)의 경우 수정후 8일부터 10일, 15일까지 계속적으로 증가하였으며, 18일에는 약간 감소하였으나 높게 유지되는 것이 관찰되었다. 간 (liver)에서는 15일에서의 발현이 18일에서보다 높았으며, 뇌 (brain)조직에서도 역시 15일째의 발현이 약간 높았다. 그런데, 모체의 태반에서의 발현을 보면 착상 초기인 8일에 가장 높았으며, 10일, 15일까지 감소하다가 18일에는 매우 약하게 발현되었다. 즉, fetus에서는 착상후 기관형성기에는 대체로 왕성한 발현을 보이다가 기관형성이 마무리되는 시점에 발현이 감소하는 현상이 관찰되었다. 그러나, 태반조직의 경우는 8일이후 계속적으로 발현이 감소되는 것이 관찰되었다. 기관형성기의 배 (embryo)와 태반은 발생시기별 유전자 발현에서 서로 상반된 결과를 보였다.