• Investigative Magnetic Resonance Imaging
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• 제19권4호
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• pp.212-217
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• 2015

Purpose: For a single time-point hyperpolarized $^{13}C$ magnetic resonance spectroscopy imaging (MRSI) of animal models, scan-time window after injecting substrates is critical in terms of signal-to-noise ratio (SNR) of downstream metabolites. Pre-scans of time-resolved magnetic resonance spectroscopy (MRS) can be performed to determine the scan-time window. In this study, based on two-site exchange model, protocol-specific simulation approaches were developed for $^{13}C$ MRSI and the optimal scan-time window was determined to maximize the SNR of downstream metabolites. Materials and Methods: The arterial input function and conversion rate constant from injected substrates (pyruvate) to downstream metabolite (lactate) were precalibrated, based on pre-scans of time-resolved MRS. MRSI was simulated using two-site exchange model with considerations of scan parameters of MRSI. Optimal scan-time window for mapping lactate was chosen from simulated lactate intensity maps. The performance was validated by multiple in vivo experiments of BALB/C nude mice with MDA-MB-231 breast tumor cells. As a comparison, MRSI were performed with other scan-time windows simply chosen from the lactate signal intensities of pre-scan time-resolved MRS. Results: The optimal scan timing for our animal models was determined by simulation, and was found to be 15 s after injection of the pyruvate. Compared to the simple approach, we observed that the lactate peak signal to noise ratio (PSNR) was increased by 230%. Conclusion: Optimal scan timing to measure downstream metabolites using hyperpolarized $^{13}C$ MRSI can be determined by the proposed protocol-specific simulation approaches.

• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.70-74
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• 2019

Cerebral air embolism (CAE) is a rare complication of various medical procedures. It manifests with symptoms similar to those of typical acute cerebral infarction, however the treatment is quite different. We present a case of arterial CAE that was associated with a disconnected central venous catheter and appeared as punctate dark signal intensities with aliasing artifacts on the susceptibility-weighted filtered phase magnetic resonance image. The susceptibility-weighted filtered phase image can be helpful for diagnosing CAE and the magnetic resonance imaging reflects the pathophysiology of CAE.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2008년도 MR연수강좌
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• pp.60-69
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• 2008

• 한국광학회:학술대회논문집
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• 한국광학회 1996년도 Advance Program of 13th optics andquantum Electronics conference, 1996제13 회 광학 및 양자전자 학술 발표회 논문 요약집
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• pp.42-42
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• 1996

• 센서학회지
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• 제20권6호
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• pp.434-438
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• 2011

A portable surface plasmon resonance(SPR) based immunosensor using thiolated protein G and protein G was developed for the detection of immunoglobulin G(IgG). The protein G has specific affinity with Fc fragment of IgG and was thiolated by 2-Iminothiolane for introduction of thiol groups. Anti-IgG, bovine serum albumin(BSA), and IgG have been sequently injected after surface modification of gold sensor chip with protein G and thiolated protein G. The output signal was increased with the injection of each protein and the actual signal was measured by subtracting signal of reference channel from signal of sample injected channel. The experimental results showed the higher detection capability of IgG using thiolated protein G compared with protein G. From these results, we can conclude that the current surface modification technique and the portable SPR sensor system can be applied to various immunosensors for diagnosis.

• Investigative Magnetic Resonance Imaging
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• 제18권4호
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• pp.279-289
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• 2014

목적: 본 연구는 T2 강조영상에서 저신호강도를 보이는 연부조직 종양의 특징적 자기공명영상 소견을 병리학적 소견과 연관지어 알아보고자 하였다. 결론: T2 강조영상에서 저신호강도를 보이는 드문 연부조직 종양의 종류에 대해 인지하고 동시에 특징적 위치, 모양, 다른 강조영상에서의 신호강도를 아는 것은 비특징적인 연부조직 종양의 감별진단에 도움이 되었다.

• International Journal of Railway
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• 제5권2호
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• pp.77-83
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• 2012

Railroad signaling systems are to control intervals and routes of trains. There are ATS, ATP, ATO and ATC system. Trains are operated in the section which is met on the signaling system because various signaling systems are used in Korea. Hence, trains are not operated in the section which is used in the other signaling system. To solve this problem, recently combined on-board system has been developed. The combined on-board system designed by doubling the ATS, ATP and ATC system to ensure the safety of system. The inductance of antenna is change and in return the resonance frequency of antenna is varied by the electromagnetic induction. Therefore, the information signal is not received exactly in the combined on-board system and in return accidents between trains occur. In this paper, electric model of the combined on-board system for considering the ATS and ATP antenna is presented. Moreover, the mutual inductance including the distance between the ATS and ATP antenna is calculated. As a result of the frequency response of the antennas, the mutual inductance met on operation range of resonance frequency is defined.

• Imaging Science in Dentistry
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• 제33권2호
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• pp.63-70
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• 2003

Purpose: To describe the MRI findings of the retrodiskal tissue in patients presenting with TMJ internal derangement and to correlate these findings with clinical and other MRI manifestations. Materials and Methods: One hundred eighteen joints of 63 patients with TMJ internal derangement were examined by MRI. Tl-weighted sagittal MR images taken in both closed- and open-mouth were evaluated for the presence of demarcation between disk and retrodiskal tissue, the presence of low signal intensity, and the depiction of the temporal part of the posterior attachment. The results were correlated with the duration of TMJ internal derangement, the presence of pain, and other MRI findings, including the type of internal derangement, the extent of disk displacement, the degree of disc deformation, and the presence of osteoarthrosis. Results: A significant relationship between the presence of low signal intensity in the retrodiskal tissue and other MRI findings was determined. Low signal intensity on the open-mouth view was observed more frequently in patients with disc displacement without reduction, severe disc displacement and deformation, and osteoarthrosis (p<0.05). The demarcation between disk and retrodiskal tissue, and the depiction of the temporal part of the posterior attachment(TPA) were correlated neither with clinical, nor with other MRI findings. Conclusion: This study suggests that low signal intensity in the retrodiskal tissue on open-mouth MR image can be indicative of advanced stages of disk displacement.

• Journal of Information Processing Systems
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• 제14권4호
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• pp.941-947
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• 2018

Since the amplitudes of spin echo train in nuclear magnetic resonance logging (NMRL) are small and the signal to noise ratio (SNR) is also very low, this paper puts forward an improved de-noising algorithm based on wavelet transformation. The steps of this improved algorithm are designed and realized based on the characteristics of spin echo train in NMRL. To test this improved de-noising algorithm, a 32 points forward model of big porosity is build, the signal of spin echo sequence with adjustable SNR are generated by this forward model in an experiment, then the median filtering, wavelet hard threshold de-noising, wavelet soft threshold de-noising and the improved de-noising algorithm are compared to de-noising these signals, the filtering effects of these four algorithms are analyzed while the SNR and the root mean square error (RMSE) are also calculated out. The results of this experiment show that the improved de-noising algorithm can improve SNR from 10 to 27.57, which is very useful to enhance signal and de-nosing noise for spin echo train in NMRL.

• 한국식품저장유통학회지
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• 제16권3호
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• pp.371-375
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• 2009

ESR spectroscopy에 의한 방사선 조사 건조향신료의 조사여부의 정확한 판별에 필요한 기초자료를 얻고자 방사선 조사 유래의 cellulose radical에 대한 parameter를 분석하였다. 건조향신료 분말 4종(고추, 마늘, 양파, 후추)에 대하여 0, 1, 5, 10 kGy의 $^{60}Co$ 감마선을 조사한 후 ESR signal을 분석하였다. 방사선 조사된 4종의 건조향신료는 모두 방사선 조사 유래의 triplet signal인 cellulose radical을 나타내면서 center signal($g_2=2.00673$)은 좌우 3.0455 mT 간격의 특이적인 signal을 보였다. 조사시료에서 나타난 hyperfine triplet signal(cellulose radical)의 g-value, center field 및 저-고자장 signal의 간격은 조사선량이 변화하여도 일정하였으므로 이들 parameter들은 cellulose radical의 고유 특성임을 확인 하였다. 이로써 감마선 조사시료와 비조사 시료 간의 구별이 분명하였다. ESR signal intensity는 조사선량이 증가함에 따라 유의적으로 증가하였다($R^2=0.8452{\sim}0.9854$). 이상의 결과에서 cellulose radical의 parameter 분석은 건조향신료의 ESR 분석에서 조사여부의 판별에 대한 신뢰성을 뒷받침 해 주었다.