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MREIT of Postmortem Swine Legs using Carbon-hydrogel Electrodes
Minhas, Atul S.,Jeong, Woo-Chul,Kim, Young-Tae,Kim, Hyung-Joong,Lee, Tae-Hwi,Woo, Eung-Je The Korean Society of Medical and Biological Engin 2008 의공학회지 Vol.29 No.6
Magnetic resonance electrical impedance tomography(MREIT) has been suggested to produce cross-sectional conductivity images of an electrically conducting object such as the human body. In most previous studies, recessed electrodes have been used to inject imaging currents into the object. An MRI scanner was used to capture induced magnetic flux density data inside the object and a conductivity image reconstruction algorithm was applied to the data. This paper reports the performance of a thin and flexible carbon-hydrogel electrode that replaces the bulky and rigid recessed electrode in previous studies. The new carbon-hydrogel electrode produces a negligible amount of artifacts in MR and conductivity images and significantly simplifies the experimental procedure. We can fabricate the electrode in different shapes and sizes. Adding a layer of conductive adhesive, we can easily attach the electrode on an irregular surface with an excellent contact. Using a pair of carbon-hydrogel electrodes with a large contact area, we may inject an imaging current with increased amplitude primarily due to a reduced average current density underneath the electrodes. Before we apply the new electrode to a human subject, we evaluated its performance by conducting MREIT imaging experiments of five swine legs. Reconstructed conductivity images of the swine legs show a good contrast among different muscles and bones. We suggest a future study of human experiments using the carbon-hydrogel electrode following the guideline proposed in this paper.
Chemical Shift Artifact Correction in MREIT
Minhas, Atul S.,Kim, Young-Tae,Jeong, Woo-Chul,Kim, Hyung-Joong,Lee, Soo-Yeol,Woo, Eung-Je The Korean Society of Medical and Biological Engin 2009 의공학회지 Vol.30 No.6
Magnetic resonance electrical impedance tomography (MREIT) enables us to perform high-resolution conductivity imaging of an electrically conducting object. Injecting low-frequency current through a pair of surface electrodes, we measure an induced magnetic flux density using an MRI scanner and this requires a sophisticated MR phase imaging method. Applying a conductivity image reconstruction algorithm to measured magnetic flux density data subject to multiple injection currents, we can produce multi-slice cross-sectional conductivity images. When there exists a local region of fat, the well-known chemical shift phenomenon produces misalignments of pixels in MR images. This may result in artifacts in magnetic flux density image and consequently in conductivity image. In this paper, we investigate chemical shift artifact correction in MREIT based on the well-known three-point Dixon technique. The major difference is in the fact that we must focus on the phase image in MREIT. Using three Dixon data sets, we explain how to calculate a magnetic flux density image without chemical shift artifact. We test the correction method through imaging experiments of a cheese phantom and postmortem canine head. Experimental results clearly show that the method effectively eliminates artifacts related with the chemical shift phenomenon in a reconstructed conductivity image.
Minha Kim,So-Dam Kim,Kyoung In Kim,전은혜,Min Gee Kim,Yu-Ree Lim,Enkhmaa Lkhagva-Yondon,Yena Oh,Kwangmin Na,정영철,진병관,송윤선,Myung Shin Jeon 한국뇌신경과학회 2021 Experimental Neurobiology Vol.30 No.2
Stroke causes systemic immunosuppression. T lymphocytes are involved in infarct size in the early stages of stroke. However, the phenotypes of T lymphocytes and their functions in peripheral immune organs and the brain have not been well analyzed in the acute and chronic phases of stroke. Here, we investigated pathological phenotypic alterations in the systemic immune response, especially changes in T lymphocytes, from one day to six months after ischemic stroke in mice. Impairment in thymocyte numbers, development, proliferation, and apoptosis were observed for up to two weeks. The number of mature T cells in the spleen and blood decreased and showed reduced interferon-γ production. Increased numbers of CD4- CD8- CD3+ double-negative T cells were observed in the mouse brain during the early stages of stroke, whereas interleukin (IL)-10+ Foxp3+ regulatory T lymphocytes increased from two weeks during the chronic phase. These phenotypes correlated with body weight and neurological severity scores. The recovery of T lymphocyte numbers and increases in IL-10+ Foxp3+ regulatory T lymphocytes may be important for long-term neurological outcomes. Dynamic changes in T lymphocytes between the acute and chronic phases may play different roles in pathogenesis and recovery. This study provides fundamental information regarding the T lymphocyte alterations from the brain to the peripheral immune organs following stroke.
Minha Hong,Kyung-Sook Lee,Jin-Ah Park,Ji-Yeon Kang,Yong Woo Shin,Young Il Cho,Duk-Soo Moon,Seongwoo Cho,Ram Hwangbo,Seung Yup Lee,Geon Ho Bahn 대한소아청소년정신의학회 2022 소아청소년정신의학 Vol.33 No.1
Objectives: Early detection of developmental issues in infants and necessary intervention are important. To identify the comorbid conditions, a comprehensive evaluation is required. The study’s objectives were to 1) generate scale items by identifying and eliciting concepts relevant to young children (12–71 months) with developmental delays, 2) develop a comprehensive screening tool for developmental delay and comorbid conditions, and 3) assess the tool’s validity and cut-off. Methods: Multidisciplinary experts devised the “Infant Comprehensive Evaluation for Neurodevelopmental Delay (ICEND),” an assessment method that comes in two versions depending on the age of the child: 12–36 months and 37–71 months, through monthly seminars and focused group interviews. The ICEND is composed of three parts: risk factors, resilience factors, and clinical scales. In parts 1 and 2, there were 41 caretakers responded to the questionnaires. Part 3 involved clinicians evaluating ten subscales using 98 and 114 questionnaires for younger and older versions, respectively. The Child Behavior Checklist, Strengths and Difficulties Questionnaire, Infant-Toddler Social Emotional Assessment, and Korean Developmental Screening Test for Infants and Children were employed to analyze concurrent validity with the ICEND. The analyses were performed on both typical and high-risk infants to identify concurrent validity, reliability, and cut-off scores. Results: A total of 296 people participated in the study, with 57 of them being high-risk (19.2%). The Cronbach’s alpha was positive (0.533–0.928). In the majority of domains, the ICEND demonstrated a fair discriminatory ability, with a sensitivity of 0.5–0.7 and specificity 0.7–0.9. Conclusion: The ICEND is reliable and valid, indicating its potential as an auxiliary tool for assessing neurodevelopmental delay and comorbid conditions in children aged 12–36 months and 37–71 months.
Minha Park,Moon Seok Kang,Geon‑Woo Park,Hyoung Chan Kim,Hyoung‑Seok Moon,Byoungkoo Kim,Jong Bae Jeon,Hyunmyung Kim,Hee‑Sang Park,Se‑Hun Kwon,Byung Jun Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
High-Mn (over 24 wt%) austenitic steels recently have been developed with excellent mechanical properties such as highstrength and ductility at very low temperatures for cryogenic application. Especially, cold-rolling process is and effectivemethod to increased yield and tensile strength of high-Mn steel when making products. In our previous work, we haveinvestigated the correlation between microstructure and mechanical properties due to recrystallization without consideringthe characteristics of the cold-rolling direction of high-Mn steels.In this study, we evaluated the effects of anisotropicbehaviors on the heat treatment of cold-rolling high-Mn steels. Despite the heat treatment, differences between transverseand longitudinal direction in the cold-rolled conditions generally affected the recrystallized microstructure. Such anisotropicbehaviors caused changes in mechanical properties such as tensile and Charpy impact test, as microstructure along coldrollingdirection.
Minha Hong,Seung-Yup Lee,Young Sik Lee,Bongseog Kim,Yoo Sook Joung,Hanik K Yoo,Eui-Jung Kim,Soyoung Irene Lee,Su-Bin Park,Soo-Young Bhang,Doughyun Han,Geon Ho Bahn 대한소아청소년정신의학회 2019 소아청소년정신의학 Vol.30 No.3
Objectives: Awareness of attention-deficit/hyperactivity disorder (ADHD) in adults has significantly increased; however, clinical data specific to the Korean population are insufficient. Clinical experience of ADHD may differ based on whether psychiatrists have received pediatric psychiatry-specific training. In order to prepare a practice parameter for adult ADHD patients in Korea, we examined questionnaire data to observe how pediatric psychiatry training could affect clinical practice for adults with ADHD. Methods: A questionnaire about the diagnosis and treatment process was distributed to both general psychiatrists (GPsy) and child and adolescent psychiatrists (CAP) at the summer and winter workshop meetings of Korean Academy of Child and Adolescent Psychiatry. Results: In total, 142 psychiatrists participated in the survey (86 GPsy, 56 CAP). GPsy and CAP preferred pharmacotherapy (GPsy 82.40%, CAP 64.30%) as the primary treatment option and answered that the clinical psychiatric interview is the most necessary step in diagnostic assessment (GPsy 22.16%, CAP 19.00%). The GPsy responded with an optimal and average treatment duration that was shorter than that reported by CAP. Conclusion: Identification of the initial presenting symptom as the correct diagnosis and the optimal duration of pharmacotherapy differed between GPsy and CAP in practice, whereas concepts in diagnosis and treatment of ADHD in adults were similar for both groups. These results suggest the urgent need for the Continuing Medical Education program for psychiatrists treating adults with ADHD.
Multi-Target Radar Tracking Estimation Algorithm for Automotive Embedded Applications
Minha Park,Seunghwan Seo,Gyutae Jung,Kukki Im 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
This paper presents tracking estimation algorithm and its feasibility analysis in computation load for the situation of multi-target automotive radar applications. Tracking algorithms have been evolved for many decades and played very important roles in space, military, and civilian sectors. Among many tracking methods, it is very critical task to utilize the most appropriate approach for each target application because there is always trade-off among performance, robustness, the computation load and etc. In the automotive world, unlike space and military industries, more constraints like cost and size should be taken into account in development within a certain limited time frame. Among them, the computation load is very significant in real-time embedded applications because the more computation capability is totally proportional to the cost increase of the system indeed. Based on literature researches and simulations, a couple of Kalman Filters were proposed as multi-target radar tracking estimation method and simulated and both elapsed time in simulation environments and in target board were compared and analyzed. As the system needs better performance and robustness in all situations, it will require more computation load in the processor resulting in the higher cost to the end. In the further research, the computation load should be analyzed in more details to adopt the most appropriate model for the specific application.