• Journal of the Korean Society of Physical Medicine
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• v.5 no.3
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• pp.445-453
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• 2010

Purpose : The purpose of this study was to investigate the effect of pelvic tilt exercise with changing the body position on foot contact pattern in the hemiplegic patients. Methods : Thirty seven hemiplegic patients were randomly divided 3 groups; control group (CG), sitting exercise group (SIEG) and standing exercise group (STEG). F-mat system and F-scan system were used for the measurement of foot contact pattern of hemiplegic side in walking. Data were analyzed statistically using paired t-test and one-way ANOVA. Results : The results were as follows : 1) Contact area of CG and SIEG were not significant difference in walking. Contact area of STEG was significant increased in walking. 2) Anteroposterior distance of COP of SIEG and STEG were significant increased in walking. Conclusion : These results suggest that pelvic tilt exercise in sitting and standing position are effective in the improvement of Anteroposterior distance of COP and gait stability are increased in only standing position.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.222-228
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• 2023

This study aimed to analyze the applicability of the improved median filter in positron emission tomography (PET)/magnetic resonance (MR) fusion images based on parallel imaging using generalized autocalibrating partially parallel acquisition (GRAPPA). In this study, a PET/MR fusion imaging system based on a 3.0T magnetic field and ¹⁸F radioisotope were used. An improved median filter that can set a mask of the median value more efficiently than before was modeled and applied to the acquired image. As quantitative evaluation parameters of the noise level, the contrast to noise ratio (CNR) and coefficient of variation (COV) were calculated. Additionally, no-reference-based evaluation parameters were used to analyze the overall image quality. We confirmed that the CNR and COV values of the PET/MR fusion images to which the improved median filter was applied improved by approximately 3.32 and 2.19 times on average, respectively, compared to the noisy image. In addition, the no-reference-based evaluation results showed a similar trend for the noise-level results. In conclusion, we demonstrated that it can be supplemented by using an improved median filter, which suggests the problem of image quality degradation of PET/MR fusion images that shortens scan time using GRAPPA.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.161-164
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• 2005

As the power of influence of the Internet grows steadily, attacks against the Internet can cause enormous monetary damages nowadays. A worm can not only replicate itself like a virus but also propagate itself across the Internet. So it infects vulnerable hosts in the Internet and then downgrades the overall performance of the Internet or makes the Internet not to work. To response this, worm detection and prevention technologies are developed. The worm detection technologies are classified into two categories, host based detection and network based detection. Host based detection methods are a method which checks the files that worms make, a method which checks the integrity of the file systems and so on. Network based detection methods are a misuse detection method which compares traffic payloads with worm signatures and anomaly detection methods which check inbound/outbound scan rates, ICMP host/port unreachable message rates, and TCP RST packet rates. However, single detection methods like the aforementioned can't response worms' attacks effectively because worms attack the Internet in the distributed fashion. In this paper, we propose a design of distributed worm detection system to overcome the inefficiency. Existing distributed network intrusion detection systems cooperate with each other only with their own information. Unlike this, in our proposed system, a worm detection system on a network in which worms select targets and a worm detection system on a network in which worms propagate themselves cooperate with each other with the direction-aware information in terms of worm's lifecycle. The direction-aware information includes the moving direction of worms and the service port attacked by worms. In this way, we can not only reduce false positive rate of the system but also prevent worms from propagating themselves across the Internet through dispersing the confirmed worm signature.

• Korean Journal of Digital Imaging in Medicine
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• v.17 no.1
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• pp.33-41
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• 2015

This study attempts to examine the clinical usefulness of High b-value DWI (diffusion weighted imaging) for brain tumors with an edema. Subjects were seven patients selected from 65 patients who received an MRI scan for suspected encephalopathy and confirmed diagnosis at our hospital from February to July 2015 (male: 7, average age : 66 years old). As test equipment, 3.0T MR System (ACHIEVA Release, Philips, Best, The Netherlands) and 8Channel SENSE Head Coill were used. DWI checks on the use of the variable TR 5460ms, TE 132ms, Slice Thickness 4mm, gap 1mm, Slice number 29 is, 3D T1WI is TR 8.4ms, TE 3.9ms, matrix size $240{\times}240$, Slice can set 180 piecesIt was. b value of 0, 1,000, 2,000 s/mm2 with DWI acquisition and 3D T1WI enhancement five minutes after the Slice Thickness 3mm, gap 0mm to reconstruct the upper face axis (MPR TRA CE) was. As for the experiment, in b-value 1,000 and 2,000 images, SNR and the lesion at the lesion site and CNR in the normal site opposite to the lesion are measured. WW(window width) and WL(window level) are made equal in MRICro software, and the volume of the lesion is measured from each of b-value and MPR TRA CE image. Using SPSS ver. 1.8.0.0 Mann Whitney-test was analyzed for SNR and CNR, while Kruskal-Wallis test was analyzed for volume.

• Childhood Kidney Diseases
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• v.7 no.1
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• pp.52-59
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• 2003

Purpose : The renin-angiotensin system(RAS) plays an important role in renal growth and development. We have studied the prevalence of renal anomalies and documented the association between karyotype and renal anomalies using IVP and ultrasonography. Furthermore, to investigate the impact of RAS gene polymorphism on renal anomaly in Turner syndrome, we examined the ACE I/D genotype, angiotensinogen(AGT) gene M235T, angiotensin receptor type 1(ATR) gene A1166C. Methods : Cytogenetic analysis was performed in 33 Turner syndrome patients on peripheral blood lymphocytes. Ultrasonography(US) of the kidneys and collecting system and intravenous pyelography(IVP) were perfomed in all patients. Nuclear scintigraphy{Tc 99m dimercaptosuccinic acid(DMSA) scan} was also performed for the definite renal diagnosis if indicated. And, ACE I/D genotype, angiotensinogen(AGT) gene M235T, angiotensin receptor type 1(ATR) gene A1166C were examined by PCR amplification of genomic DNA samples. Results : The prevalence of renal anolmalies in Turner syndrome was 36.4%(12/33). The Karyotype 45, X was observed in 18 of the 33 girls(54.5%), of whom 8(44.4%) had renal anomalies. Mosaic karyotypes were observed in 11(33.3%) and four(12.2%) had a non-mosaic structural aberration of the X chromosome. In this group 4(25.7%) had renal anomalies. More renal anomalies were associated with the 45, X karyotype than those with mosaic/structural abnormalities of X chromosome, but the difference was not statistically significant(P>0.05). And, there was no significant differences in the RAS gene polymorphism and allele frequencies between renal anomaly group and normal group in Turner syndrome. Conclusion : The prevalence of renal anolmalies in Turner syndrome was 36.4%. There is no significant differences in the RAS gene polymorphism and allele frequencies between the renal anomaly group and the normal group in Turner syndrome.

• The Korean Journal of Nuclear Medicine Technology
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• v.26 no.1
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• pp.27-32
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• 2022

Purpose When performing a whole-body bone scan, many patients are experiencing psychological difficulties due to the close distance to the detector. Recently, in the medical field, there is a report that using virtual reality (VR) equipment can give pain relief to pediatric patients with weak concentration or patients receiving severe treatment through a distraction method. Therefore, in this paper, VR equipment was used to provide psychological stability to patients during nuclear medicine tests, and it is intended to evaluate whether it can be used in clinical practice. Materials and Methods As VR equipment, ALLIP Z6 VR (ALLIP, Korea) was used and the experiment was conducted after connecting to a mobile phone. The subjects were 30 patients who underwent whole-body bone examination from September 1, 2021 to September 30, 2021. After intravenous injection of 99mTc-HDP, 3 to 6 hours later, VR equipment was put on and whole body images were obtained. After the test, a survey was conducted, and a Likert scale of 5 points was used for psychological anxiety and satisfaction with VR equipment. Hypothesis verification and reliability of the survey were analyzed using SPSS Statistics 25 (IBM, Corp., Armonk, NY, USA). Results Anxiety about the existing whole-body bone test was 3.03±1.53, whereas that of anxiety after wearing VR equipment was 2.0±1.21, indicating that anxiety decreased to 34%. When regression analysis of the effect of the patient's concentration on VR equipment on anxiety about the test, the B value was 0.750 (P<0.01) and the t value was 6.181 (P<0.01). decreased and showed an influence of 75%. In addition, overall satisfaction with VR equipment was 3.76±1.28, and the intention to reuse was 66%. The Cronbach α value of the reliability coefficient of the questionnaire was 0.901. Conclusion When using VR equipment, patients' attention was dispersed, anxiety was reduced, and psychological stability was found. In the future, as VR equipment technology develops, it is thought that if the equipment can be miniaturized and the resolution of VR content images is increased, it can be used in various clinical settings if it provides more realistic stability to the patient.

• Journal of radiological science and technology
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• v.26 no.2
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• pp.57-61
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• 2003

The purpose of this study is to compare both 1.5T and 4.7T in Praietal White matter material Phantom using the same methodology at both field strengths. Data at both field strengths are compared in terms of $T_2$ relaxation times, line widths and SNRs MR imaging and $^1H$ MR spectroscopy were performed on GE 1.5T SIGNA system and Broker Biospec 4.7T/30 MRI/MRS system. After phantom axial scan $^1H$ MRS was obtained from T2 weighted image by 3-dimensional localization technique(PRESS : Point RE solved spectroscopy Sequence) this phantom is composed of an aqueous solution 36.7 mmol/L of NAA, 25.0 mmol/L of Cr, 6.3 mmol/L of choline chloride, 30.0 mmol/L or Glu, and 22.5 mmol/L of MI(adjusted to a pH of 7,15 in a phosphate buffet). Data processed using software developed inhouse. At 1.5T, T2 relaxation times for Cho, Cr, and NAA were $0.41{\pm}0.07,\;0.26{\pm}0.04,\;0.46{\pm}0.07$ while at 4.7T they were $0.17{\pm}0.03,\;0.14{\pm}0.05,\;0.20{\pm}0.03$ respectively. At 1.5T, line widths for water, Cho, Cr and NAA were $2.9{\pm}0.7,\;1.6{\pm}0.7,\;1.7{\pm}0.8,\;2.2{\pm}0.02Hz$ while at 4.7T they were $5.2{\pm}1.1,\;4.6{\pm}1.9,\;4.01{\pm}1.8,\;4.8{\pm}1.9Hz$ respectively. It can be seen that $T_2$ relaxation times were significantly shorter at 4.7 compared to 1.5T and that the line widths were also broader. The average SNRs for NAA for subjects at short and long TEs were $23.5{\pm}11.3$ at TE=20 msec ; $15.4{\pm}7.7$ at TE=272 msec at 1.5T and $40{\pm}8.3$ and $17{\pm}3.5$ respectively at 4.7T higher field strength is superior because of improved sensitivity and chemical shift dispersion. However these improvements are partially offset by increased line widths and decrease $T_2$ relaxation times, which act to reduce both sensitivity and resolution. In our experiments with the equipment available to us, 4.7T proton spectra at short TEs exhibit moderately improved sensitivity compared to 1.5T.

• Investigative Magnetic Resonance Imaging
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• v.8 no.2
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• pp.79-85
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• 2004

Purpose : To evaluate the usefulness and reproducibility of $^1H$ MRS in different 1.5 T MR machines with different coils to compare the SNR, scan time and the spectral patterns in different brain regions in normal volunteers. Materials and Methods : Localized $^1H$ MR spectroscopy ($^1H$ MRS) was performed in a total of 10 normal volunteers (age; 20-45 years) with spectral parameters adjusted by the autoprescan routine (PROBE package). In all volunteers, MRS was performed in a three times using conventional MRS (Signa Horizon) with 1 channel coil and upgraded MRS (Echospeed plus with EXCITE) with both 1 channel and 8 channel coil. Using these three different machines and coils, SNRs of the spectra in both phantom and volunteers and (pre)scan time of MRS were compared. Two regions of the human brain (basal ganglia and deep white matter) were examined and relative metabolite ratios (NAA/Cr, Cho/Cr, and mI/Cr ratios) were measured in all volunteers. For all spectra, a STEAM localization sequence with three-pulse CHESS $H_2O$ suppression was used, with the following acquisition parameters: TR=3.0/2.0 sec, TE=30 msec, TM=13.7 msec, SW=2500 Hz, SI=2048 pts, AVG : 64/128, and NEX=2/8 (Signa/Echospeed). Results : The SNR was about over $30\%$ higher in Echospeed machine and time for prescan and scan was almost same in different machines and coils. Reliable spectra were obtained on both MRS systems and there were no significant differences in spectral patterns and relative metabolite ratios in two brain regions (p>0.05). Conclusion : Both conventional and new MRI systems are highly reliable and reproducible for $^1H$ MR spectroscopic examinations in human brains and there are no significant differences in applications for $^1H$ MRS between two different MRI systems.

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.128-135
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• 2000

Purpose : The aim of this study is to develope the Magnetic Resonance Spectroscopy(MRS) data processing S/W which plays an important role as a diagnostic tool in clinical field. Materials and methods : Post-processing software of MRS based on graphical user interface(GUI) under windows operating system of personal computer(PC) was developed using MATLAB(Mathwork, U.S.A.). This tool contains many functions to increase the quality of spectrum data such as DC correction, zero filling, line broadening, Gauss-Lorentzian filtering, phase correction, etc. And we obtained the normal human brain $^1H$ MRS data from parietal white matter, basal ganglia and occipital grey matter region using 1.5T Gyroscan ACS-NT R6 (philips, Amsterdam, Netherland) MRS package. The analysis of the MRS peaks were performed by obtaining the ratio of peak area. Results : The peak ratios of NAA/Cr, Cho/Cr, MI/Cr for the different MRS machines have a little different values. But these peak ratios were not significantly different between different echo time MRS peak ratios in the same machine (p<0.05). Conclusion : MRS post-processing S/W based on GUI using PC was developed and applied to the analysis of normal human brain $^1H$ MRS. This independent MRS processing job increases the performance and throughput of patient scan of main console. Finally, we suggest that the database for normal in-yivo human MRS data should be obtained before clinical applications.

• Ocean and Polar Research
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• v.44 no.4
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• pp.355-364
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• 2022

When the 60-ton-class patrol boat '72' of the Korea Coast Guard (KCG) was on duty and she accidentally collided with another patrol boat ('207', 200-ton-class) and sank. A month-long search found a small amount of lost items, but neither the crew nor the ship was found. For the first time in 39 years since the accident, the Korea Institute of Ocean Science and Technology (KIOST) searched the boat 72 using the latest integrated geophysical techniques. A number of sonar images presumed to be of a sunken ship was acquired using a combined system of side scan sonar and marine magnetometer, operated at an altitude of approximately 30 m from the seabed. At the same time, a strong magnetic anomaly (100 nT) was detected in one place, indicating the presence of an iron ship. A video survey using a remotely operated underwater vehicle (ROV) confirmed the presence of a shielding part of a personal firearm at the stern of the sunken vessel. Based on these comprehensive data, the sunken vessel discovered in this exploration was assumed to be '72'. This result is meaningful in terms of future ocean exploration and underwater archaeology, as the integrated system of various geophysical methods is an efficient means of identifying objects present in the water.