Seunghwan Kim

Speed Estimation From a Tri-axial Accelerometer Using Neural Networks

We propose a speed estimation method with human body accelerations measured on the chest by a tri-axial accelerometer. To estimate the speed we segmented the acceleration signal into strides measuring stride time, and applied two neural networks into the patterns parameterized from each stride calculating stride length. The first neural network determines whether the subject walks or runs, and the second neural network with different node interactions according to the subjects status estimates stride length. Walking or running speed is calculated with the estimated stride length divided by the measured stride time. The neural networks were trained by patterns obtained from 15 subjects and then validated by 2 untrained subjects patterns. The result shows good agreement between actual and estimated speeds presenting the linear correlation coefficient r = 0.9874. We also applied the method to the real field and track data.

The expression of tumor-associated macrophages in papillary thyroid carcinoma.

Background Tumor-associated macrophages (TAMs) play a tumorigenic role related to advanced staging and poor prognosis in many human cancers including thyroid cancers. Yet, a functional role of TAMs in papillary thyroid carcinoma (PTC) has not been established. The aim of this study was to investigate TAM expression in human PTC with lymph node (LN) metastasis. Methods Thirty-six patients who underwent surgery after being diagnosed with PTC with LN metastasis were included. Primary tumor tissues were immunohistochemically stained with an anti-CD68 antibody and clinical characteristics according to TAM density were evaluated. Results The TAM densities (CD68+ cells) varied from 5% to 70%, in all tumor areas, while few cells were stained in adjacent normal tissues. TAMs were identified as CD68+ cells with thin, elongated cytoplasmic extensions that formed a canopy structure over tumor cells. Comparing clinicopathologic characteristics between tumors with low (<25%) and high (25% to 70%) TAM densities, primary tumors were larger in the high density group than in the low density group (2.0±0.1 vs. 1.5±0.1; P=0.009). Conclusion TAMs were identified in primary PTC tumors with LN metastasis and higher TAM densities were related to larger tumor sizes, suggesting a tumorigenic role of TAMs in human PTCs.

A Preliminary Study for Portable Walking Distance Measurement System Using Ultrasonic Sensors

Efforts have been made to measure the distance traveled by humans in motion, in ways that are compact and accurate, for a long time. There are several ways to measure the distance moved by walking or running in daily life, some of which already use commercial products, but those methods are inaccurate. In this study, a new method is provided using ultrasonic sensors, and this is the fundamental study. The newly devised Portable Walking Distance Measurement System was developed using ultrasonic wave characteristics and has approximately 90% accuracy. This result provides an opportunity to estimate human activities and the developed system would provide more comfort and an exact way to measure the walking distance in daily life and could be applied to exercise.

Identification and expression of uvi31(+), a UV-inducible gene from Schizosaccharomyces pombe

The Schizosaccharomyces pombe uvi31+ gene has been previously isolated as a UV‐inducible gene [Lee JK et al. (1994) Biochem Biophys Res Commun 202:1113–1119]. This gene encodes a protein of about 12 kDa with 57% amino acid sequence similarity to Escherichia coli BolA protein which is known to be involved in switching between the cell elongation and septation systems during the cell division cycle. The putative Mlul cell cycle box (MCB), SWI4/6‐dependent cell cycle box (SCB), and gear‐box elements are found in the upstream region of uvi31+ gene, suggesting that this gene shows the cell cycle‐regulated and growth phase‐dependent expression. Interestingly, the level of uvi31− transcript varies throughout the cell cycle, peaking in G1 phase before septation, and also shows the growth phase‐dependent pattern during cellular growth, increasing maximally at the diauxic shift phase just before stationary phase. Furthermore, the transcript level of this gene is raised after S phase arrest, and is also increased maximally at 4 hr after UV irradiation of 240 J/m2. These results suggest that the delayed induction of uvi31+ gene after UV irradiation may be caused by cell cycle control of this gene after DNA replication checkpoint arrest. Thus, the uvi31+ gene may play a role in controlling the progress of the cell cycle after DNA damage (UV irradiation). Environ. Mol. Mutagen. 30:72–81, 1997

Conductive rubber electrode for wearable health monitoring

For the continuous health monitoring, physiological signal must be able to measure for a long time in daily life. Therefore, health monitoring device was made as small as possible, and sensors must have a small effect by motion artifact. To reduce impedance between the user skin and the electrode, a conductive gel was applied to the metallic electrode, thereby facilitating converting ion current flowing in a living body into an electric current. However, commercial disposable electrode using the conductive gel incurred a skin trouble such as a reddish skin and stinging pain, when used to measure electrocardiogram (ECG) for a long-time. In this paper, we evaluated the performance of the conductive rubber electrode to use the electrode of wearable health monitoring device. These electrode were made the rubber electrode included a good conductive metal compound and had some viscosity. In addition, conductive yarn was tested to replace connecting wire between electrode and measurement device. The ECG signal measured by the conductive yarn rubber electrode cable was good quality. However, conductive yarn must be isolated to use in garment

The echotextural characteristics for the diagnosis of the liver cirrhosis using the sonographic images

Various statistical parameters have been tried for the computer-aided diagnosis of the liver fibrosis. The region of interest (ROI) for the liver and spleen parenchymas have been chosen, and the hepatolienal textural contrast for each ultrasound (US) image has been examined. The selectively chosen textural parameters are linearly combined with the pre-determined coefficients to give the computer-aided diagnostic parameter for the liver fibrosis, whose final stage is named as cirrhosis. From the comparison with the clinical diagnosis it is suggested that the proposed calculation scheme using the textural parameters show the quite promising classification performance for the computer-aided diagnosis of the liver cirrhosis.

Computer-assisted Sonographic Analysis of the Hepatorenal and Textural Features for the Diagnosis of the Fatty Liver

We investigated the B-mode ultrasound (US) images of abdomen by normalizing the gray level values of the liver with the representative gray levels (RGLs) of the liver parenchyma, renal cortex, subcutaneous fat, to quantify the fatty infiltration of the liver (FIL). The RGLs were compared with the clinical diagnosis of the FIL showing good correlation between them

Performance Study of the Wearable One-Lead Wireless Electrocardiographic Monitoring System

This study attempts to compare and assess the performance of a wearable electrocardiogram (ECG) using a sensing fabric electrode and a Bluetooth network with a conventional ECG. A one-lead ECG examination was performed using Bioshirt and an iWorx 214 while walking or running at 3, 6, and 9 km per hour. A correlation coefficient of a heart rate variability (HRV) between these two devices was higher than 0.96 and power spectral density of HRV measured also showed an excellent agreement. Thus, both of these two ECG devices showed similar detection capability for R peaks. The measured values for wave duration and intervals of both devices concur with each other. The intensity of noise is controversial. The ECG device using a sensing fabric electrode and a wireless network showed an ECG signal detection and transmission capability similar to that of a conventional ECG device.

Present Status and Analysis for IEEE 11073 Personal Health Device Specializations

Increasing interest of life expectancy and health has made the u-health industry activating and the several international standard developing organizations(SDO) are dealing with u-health services and technologies. Among them, IEEE 11073 PHD(Personal Health Devices) Work Group is developing standards of personal health device communication for interoperability. There are many studies for introducing SDOs and analyzing the IEEE 11073-20601 standard. However, due to the rare study of PHD sta ndards analysis, there are a lot of difficulties to utilize the standards. In this paper, present status of national and international SDOs including IEEE 11073 standards for PHD will be introduced. Moreover, device specialization standards such as thermometer, weighing scale, glucose meter, blood pressure monitor, electrocardiograph (ECG) etc.. will be analyzed based on the IEEE 11073-20601.

Quantitative Analysis of White Matter on DTI Images of Patients with Tinnitus: Preliminary Report

Tinnitus is defined as an unwanted auditory perception of internal origin, usually localized, and rarely heard by others. Persisting appearances of tinnitus are most commonly combined with diseases or damage in the inner ear or neuro-auditory pathway. Diffusion tensor magnetic resonance imaging (DTI) is a new imaging method with the capability of providing non-invasive information on tissue microstructure not available in routine clinical MRI images. Since white matter regions of the brain are an ordered structure due to the myelination and directionality of axons and have a high degree of anisotropy, the ability to detect changes in anisotropy can be extremely useful in the study of diseases such as tinnitus and multiple sclerosis, which are assumed to involve the demyelination of axons. While several studies investigated tinnitus using MRI, few studies tried to analyze neurological disorders quantitatively using DTI. In this study, the cerebral volume of white matter on DTI images of patients with tinnitus was measured using the semi-automated and intuitive menu based image processing tool (Human Analyzer, ETRI, Korea). Total number of ten patients with tinnitus including three women was examined