• Proceedings of the KSMRM Conference
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• 1997.10a
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• pp.26-26
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• 1997

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.135-144
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• 2024

Ultrasonography examination has limitations in quantifying hepatic fat quantification. Therefore, this study aimed to experimentally demonstrate whether changes in signal attenuation during ultrasound imaging can be quantified using simulated hepatic phantoms to assess hepatic fat content. Additionally, we aimed to evaluate the potential of ultrasound imaging for diagnosing hepatic fatty liver by analyzing the relationship between hepatic fat content and signal intensity in ultrasound images. In this study, we developed a total of five stimulated hepatic phantoms by homogeneously mixing water and oil. We confirmed the fat content of the phantoms using magnetic resonance imaging (MRI) and ultrasound imaging, and measured signal intensity according to distance in ultrasound images to analyze the correlation and mean comparison between fat content and signal intensity. We observed that as the fat content increased, the ultrasound penetration intensity decreased, confirming the potential for quantifying hepatic fat content using ultrasound. Additionally, the analysis of the correlation between the measured fat content using MRI and the signal intensity measured in ultrasound images showed a high correlation. Statistical analysis in our study confirmed that as the fat content increased, the slope representing signal during ultrasound imaging (US-GRE) decreased. In this study, it was statistically confirmed that the US-GRE value of ultrasound images gradually decreases as the fat content increases, and it is believed that US-GRE can serve as a biomarker expressing fatty liver content.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.05a
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• pp.153-157
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• 2002

자기 진단 센서는 자신의 상태를 스스로 진단하는 기능을 갖는 센서를 말한다. 이러한 기능을 갖기 위해서 자신의 상태를 판단 할 수 있는 정보를 얻는 것이 가장 중요하다. 본 연구에서는 자신의 노이즈 신호만으로 상태를 판단할 수 있는 자기 진단센서의 설계하는 방법을 제안하였다. 웨이브렛 및 ICA 분석기법을 이용하여 자신의 출력 신호로부터 대상목표의 측정물리량을 나타내는 신호성분을 제외한, 센서 자신으로부터 발생하는 특징 노이즈 신호만을 분류한 다음에, 이 신호를 PDS로 정량화하여 특징 데이터를 생성하였다. 실험을 통해 그 타당성을 입증하였다.

• Journal of KIISE
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• v.42 no.11
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• pp.1459-1466
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• 2015

Lockscreen is one of the most frequently encountered interfaces by smartphone users. Although users perform unlocking actions every day, there are no benefits in using lockscreens apart from security and authentication purposes. In this paper, we replace the traditional lockscreen with an application that analyzes facial expressions in order to collect facial expression data and provide real-time feedback to users. To evaluate this concept, we have implemented Quantified Lockscreen application, supporting the following contributions of this paper: 1) an unobtrusive interface for collecting facial expression data and evaluating emotional patterns, 2) an improvement in accuracy of facial expression detection through a personalized machine learning process, and 3) an enhancement of the validity of emotion data through bidirectional, multi-channel and multi-input methodology.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1249-1261
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• 2018

The quantitative representation for the magnetic force of a cylindrical permanent magnet acting on a ferromagnetic cylindrical object was derived on the basis of magnetization theories, and the Gilbert and Ampere models of magnetism. The magnetic force derived in this study is directly proportional to the remanent magnetization magnetic field, the cross-sectional area of the permanent magnet, the saturation magnetic field, and the cross-sectional area of the ferromagnetic object and is inversely proportional to the square of the quantity related to the distance between the permanent magnet and the ferromagnetic object. The magnetic forces of an AlNiCoV cylindrical permanent magnet and a Ferrite cylindrical permanent magnet, both with a radius of 0.4 cm and a length of 7 cm, acting on ferromagnetic objects at distances farther than the radius were calculated to be less than 3.6711 N and 0.1857 N, respectively.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.240-241
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• 2002

Tetragonal 구조를 갖는 정량적 Nd$_2$/Fe$_{14}$B (~Nd$_{12}$Fe$_{82}$B$_{6}$) 화합물에서의 Nd 양보다 적은 양의 Nd를 함유하는 Nd-Fe-B 합금에서는, 일반적으로 입자크기가 큰 연자성 $\alpha$-Fe가 과다하게 존재하면서 외부에서 가해주는 자장에 대해 강자성 Nd$_2$/Fe$_{14}$B와 별개의 자기적 거동을 보여주기 때문에, 보자력이 아주 적어 실용성이 없다. 그러나 이러한 합금을 급랭응고하여 미세 결정화하거나, 비정질화한 후 적절히 열처리 해주면 a-Fe와 Nd$_2$/Fe$_{14}$B 입자가 나노화하면서 이들 사이에 상호교환작용이 일어나 등방성 상태에서도 M$_{s}$ /2 보다 큰 잔류자화와 함께 적절한 크기의 보자력도 얻을 수 있다. (중략중략

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2018.06a
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• pp.86-86
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• 2018

• Journal of the Korean Magnetics Society
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• v.27 no.4
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• pp.145-152
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• 2017

The arterial spin labeling (ASL) is a magnetic resonance imaging (MRI) method that can evaluate tissue perfusion using blood in the body. The characteristic of non-invasive examinations without contrast agents and the quantitative measurement of perfusion volume is possible, which are increasingly being used for clinical and research purposes. Up to the present, The ASL method has lower SNR than the perfusion imaging method using contrast agent and because optimization of various parameter in the imaging process is difficult, Which may result in measurement errors. To improve this, ASL methods using various technologies are introduced. This paper briefly introduces the outline of ASL, its features in imaging process, various techniques, and clinical application.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.179-184
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• 1995

The ac magnetic susceptibility of {100} iron whiskers as a function of currents is studied with and without external field. The ac susceptibility depends on the magnitude and the direction of the applied dc current when a small external field is applied along the magnetization of the central domain of the whisker. Variation of the central domain size accounts for the current-dependent response. The measured magnetic responses are explained, using a micromagnetic calculation based on a simple model, as a function of applied currents over a wide range except critical values.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1124-1139
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• 2021

The objective assessment of atrophy and the measurement of brain volume is important in the early diagnosis of dementia and neurodegenerative diseases. Recently, several MR-based volumetry software have been developed. For their clinical application, several issues arise, including the standardization of image acquisition and their validation of software. Additionally, it is important to highlight the diagnostic performance of the volumetry software based on expert opinions. We instituted a task force within the Korean Society of Neuroradiology to develop guidelines for the clinical use of MR-based brain volumetry software. In this review, we introduce the commercially available software and compare their diagnostic performances. We suggest the need for a standard protocol for image acquisition, the validation of the software, and evaluations of the limitations of the software related to clinical practice. We present recommendations for the clinical applications of commercially available software for volumetry based on the expert opinions of the Korean Society of Neuroradiology.