• Progress in Medical Physics
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• v.23 no.2
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• pp.71-80
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• 2012

In order to verify exact dose distributions in the state-of-the-art radiation techniques, a newly designed three-dimensional dosimeter and technique has been took strongly into consideration. The main purpose of our study is to verify the optimized parameters of polymer gel as a real volumetric dosimeter in terms of the various study of MRI. We prepared a gel dosimeter by combing 8% of gelatin, 8% of MAA, and 10 mM of THPC. We used a Co-60 gamma-ray teletherapy unit and delivered doses of 0, 2, 4, 6, 8, 10, 12, and 14 Gy to each polymer gel with a solid phantom. We used a fast spin-echo pulse to acquire the characterized T2 time of MRI. The signal noise ratio (SNR) of the head & neck coil was a relatively lower sensitivity than the body coil; therefore the dose uncertainty of head & neck coil would be lower than body coil's. But the dose uncertainty and resolution of the head & neck coil were superior to the body coil in this study. The TR time between 1,500 ms and 2,000 ms showed no significant difference in the dose resolution, but TR of 1,500 ms showed less dose uncertainty. For the slice thickness of 2.5 mm, less dose uncertainty of TE times was at 4 Gy, as well, it was the lowest result over 4 Gy at TE of 12 ms. The dose uncertainty was not critical up to 6 Gy, but the best dose resolution was obtained at 20 ms up to 8 Gy. The dose resolution shows the lowest value was over 20 ms and was an excellent result in the number of excitation (NEX) of three. The NEX of two was the highest dose resolution. We concluded that the better result of slice thickness versus NEX was related to the NEX increment and thin slice thickness.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.110-114
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• 2014

Purpose: The advancement in PET/CT test devices has decreased the test time and popularized the test, and PET/CT tests have continuously increased. However, this increases the exposure dose of radiation workers, too. This study aims to measure the radiation shielding rate of $^{18}F-FDG$ with a strong energy and the shielding effect when worker wore an apron during the PET/CT test. Also, this study compared the shielding rate with $^{99m}TC$ to minimize the exposure dose of radiation workers. Materials and Methods: This study targeted 10 patients who visited in this hospital for the PET/CT test for 8 days from May 2nd to 10th 2013, and the $^{18}F-FDG$ distribution room, patient relaxing room (stand by room after $^{18}F-FDG$ injection) and PET/CT test room were chosen as measuring spots. Then, the changes in the dose rate were measured before and after the application of the APRON. For an accurate measurement, the distance from patients or sources was fixed at 1M. Also, the same method applied to $^{99m}TC's$ Source in order to compare the reduction in the dose by the Apron. Results: 1) When there was only L-block in the $^{18}F-FDG$ distribution room, the average dose rate was $0.32{\mu}Sv$, and in the case of L-blockK+ apron, it was $0.23{\mu}Sv$. The differences in the dose and dose rate between the two cases were respectively, $0.09{\mu}Sv$ and 26%. 2) When there was no apron in the relaxing room, the average dose rate was $33.1{\mu}Sv$, and when there was an apron, it was $22.3{\mu}Sv$. The differences in the dose and dose rate between them were respectively, $10.8{\mu}Sv$ and 33%. 3) When there was no APRON in the PET/CT room, the average dose rate was $6.9{\mu}Sv$, and there was an APRON, it was $5.5{\mu}Sv$. The differences in the dose and dose rate between them were respectively, $1.4{\mu}Sv$ and 25%. 4) When there was no apron, the average dose rate of $^{99m}TC$ was $23.7{\mu}Sv$, and when there was an apron, it was $5.5{\mu}Sv$. The differences in the dose and dose rate between them were respectively, $18.2{\mu}Sv$ and 77%. Conclusion: According to the result of the experiment, $^{99m}TC$ injected into patients showed an average shielding rate of 77%, and $^{18F}FDG$ showed a relatively low shielding rate of 27%. When comparing the sources only, $^{18F}FDG$ showed a shielding rate of 17%, and $^{99m}TC$'s was 77%. Though it had a lower shielding effect than $^{99m}TC$, $^{18}F-FDG$ also had a shielding effect on the apron. Therefore, it is considered that wearing an apron appropriate for high energy like $^{18}F-FDG$ would minimize the exposure dose of radiation workers.

• The Korean Journal of Nuclear Medicine
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• v.36 no.4
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• pp.244-254
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• 2002

Purpose: This study investigated the differences between technetium-99m ethyl cysteinate dimer (Tc-99m ECD) and technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) uptake in the normal brain by means of statistical parametric mapping (SPM) analysis. Materials and Methods: We retrospectively analyzed age and sex matched 53 cases of normal brain SPECT. Thirty-two cases were obtained with Tc-99m ECD and 21 cases with Tc-99m HMPAO. There were no abnormal findings on brain MRIs. All of the SPECT images were spatially transformed to standard space, smoothed and globally normalized. The differences between the Tc-99m ECD and Tc-99m HMPAO SPECT images were statistically analyzed using statistical parametric mapping (SPM'99) software. The differences bgetween the two groups were considered significant ant a threshold of corrected P values less than 0.05. Results: SPM analysis revealed significantly different uptakes of Tc-99m ECD and Tc-99m HMPAO in the normal brains. On the Tc-99m ECD SPECT images, relatively higher uptake was observed in the frontal, parietal and occipital lobes, in the basal ganglia and thalamus, and in the superior region of the cerebellum. On the Tc-99m HMPAO SPECT images, relatively higher uptakes was observed in subcortical areas of the frontal region, temporal lobe, and posterior portion of inferior cerebellum. Conclusion: Uptake of Tc-99m ECD and Tc-99m HMPO in the normallooking brain was significantly different on SPM analysis. The selective use of Tc-99m ECD of Tc-99m HMPAO in brain SPECT imaging appears especially valuable for the interpretation of cerebral perfusion. Further investigation is necessary to determine which tracer is more accurate for diagnosing different clinical conditions.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.21-27
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• 1993

Fluid inclusion has been widely used to study the origin and physiochemical conditions of ore deposits. However, it is difficult to get the accurate physiochemical data from fluid inclusion study due to the error of microthermometric data and the complexity of calculation of density and isochore of fluid inclusion. The computer programs HALWAT, $CO_2$, and CHNACL written by Nicholls and Crowford (1985) partly contributed to improve the accuracy of physiochemical data by using complicated equations. These programs are applied to determine the densities and isochores of fluid inclusions for the Cretaceous Keumhak mine using Choi and So's data (1992) and for the Jurassic Samhwanghak mine using Yun's data (1990). The estimated PoT for Keumhak mine from calculated isochores of coexisting fluid inclusions are $230^{\circ}{\sim}290^{\circ}C$ and 500~800 bar which matche well to the poT estimated by Choi and So ($280^{\circ}{\sim}360^{\circ}C$ and 500~800 bar, 1992). However, the poT for Samwhanghak mine estimated in this study by combining the calculated isochores and sulfur isotope geothermometer data by Yun (1990) are about 4~7 kb at $329{\pm}50^{\circ}{\sim}344{\pm}55^{\circ}C$ which are quite different form the P-T estimates by Yun ($255^{\circ}{\sim}294^{\circ}C$ and 1.2~1.9kb, 1990). This discrepancy caused by misinterpretation of homogenization temperature (Th) of fluid inclusion and by application of inappropriate isochores. The application of homogenization temperature and/or inappropriately selected isochore to determine the trapping PoT condition of ore-deposits should be avoided, particularly for ore-deposits formed at pressures higher than 1~2 kb.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.7
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• pp.387-395
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• 2015

Anaerobic mesophilic batch test of several organic wastes were carried out by a graphical statistic analysis (GSA) to evaluate their ultimate biodegradability and two distinctive decay rates ($k_1$ and $k_2$) with their corresponding degradable substrate fractions ($S_1$ and $S_2$). Each 3 L batch reactor was operated for more than 100 days at the substrate to inoculum ratio (S/I) of 0.5 as an initial total volatile solids (TVS) mass basis. Their Ultimate biodegradabilities were obtained respectively as follow; 69% swine waste, 45% dairy cow manure, 66% slaughterhouse waste, 79% food waste, 87% food waste leachate, 68% primary sludge and 39% waste activated sludge. The readily biodegradable fraction of 89% ($S_1$) of Swine Waste BVS ($S_o$) degraded with in the initial 31 days with $k_1$ of $0.116day^{-1}$, where as the rest 11% slowly biodegradable fraction ($S_2$) of BVS degraded for more than 100 days with the long term batch reaction rates ($k_2$) of $0.004day^{-1}$. For the Food Waste and Waste Activated Sludge, their readily biodegradable portions ($S_1$) appeared 89% and 80%, which degrades with $k_1$ of $0.195day^{-1}$ and $0.054day^{-1}$ for an initial 15 days and 28 days, respectively. Their corresponding long term batch reaction rates ($k_2$) were $0.003day^{-1}$ and $0.002day^{-1}$. Results from other organic wastes are addressed in this paper. The theoretical hydraulic retention times (HRTs) of anaerobic digesters treating organic wastes are easily determined by the analysis of multiple decay rate coefficients ($k_1$ and $k_2$) and their corresponding biodegradable substrate fractions ($S_1$ and $S_2$).

• Tuberculosis and Respiratory Diseases
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• v.58 no.6
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• pp.570-575
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• 2005

Introduction : Diffuse interstitial lung diseases (DILD) comprise of a large group of lung diseases with diverse etiologies. They are classified into four categories based on the etiology and pathological findings. In Korea, epidemiological data on DILD has never been reported in a prospective manner. Method : From May 2002 to April 2004, total 487 patients with DILD were prospectively registered at Samsung Medical Center. The prospective observational analysis of the etiologies, its classification based on 2002 ATS/ERS (American Thoracic Society/European Respiratory Society) guidelines, as well as diagnostic tests and the retrospective analysis of the treatment modalities were carried out. Any infectious and malignant causes were excluded. Results : 1) The patients were classified into idiopathic interstitial pneumonia (IIP) in 269 patients (55.2%), known causes of DILD in 168 patients (34.5%), sarcoidosis in 27 patients (5.5%), other forms of DILD in 14 patients (2.9%), and undetermined DILD in 9 patients (1.9%). 2) The diagnostic test showed that most patients had undergone chest high resolution computed tomography (HRCT) and pulmonary function test (PFT) (97%, 89%). Transbronchial lung biopsy (TBLB) and surgical lung biopsy (SLB) were performed in limited patients (38%, 29%). 3) Among 269 patients with IIP, 220 (82%) had idiopathic pulmonary fibrosis (IPF) while 23 (9%) had nonspecific interstitial pneumonia. SLB was carried out in 36% of patients with IIP. 4) Symptomatic supportive care was given to 67% of IPF, but specific medical treatment including corticosteroids was administered to 89% of non-IPF patients. Conclusion : A nationwide registry of DILD patients is required to determine the annual incidence, etiology, and practice pattern of diagnosis and treatment in Korea.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.425-430
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• 2014

Foods contain various nutrients such as carbohydrates, protein, oil, vitamins, and minerals. Among them, carbohydrates, protein, and oil are the main constituents of foods. Usually, these constituents are analyzed by the Kjeldahl and Soxhlet method and so on. However, these analytical methods are complex, costly, and time-consuming. Thus, this study aimed to rapidly and effectively analyze carbohydrate, protein, and oil contents with near-infrared reflectance spectroscopy (NIRS). A total of 517 food samples were measured within the wavelength range of 400 to 2,500 nm. Exactly 412 food calibration samples and 162 validation samples were used for NIRS equation development and validation, respectively. In the NIRS equation of carbohydrates, the most accurate equation was obtained under 1, 4, 5, 1 (1st derivative, 4 nm gap, 5 points smoothing, and 1 point second smoothing) math treatment conditions using the weighted MSC (multiplicative scatter correction) scatter correction method with MPLS (modified partial least square) regression. In the case of protein and oil, the best equation were obtained under 2, 5, 5, 3 and 1, 1, 1, 1 conditions, respectively, using standard MSC and standard normal variate only scatter correction methods with MPLS regression. Calibrations of these NIRS equations showed a very high coefficient of determination in calibration ($R^2$: carbohydrates, 0.971; protein, 0.974; oil, 0.937) and low standard error of calibration (carbohydrates, 4.066; protein, 1.080; oil, 1.890). Optimal equation conditions were applied to a validation set of 162 samples. Validation results of these NIRS equations showed a very high coefficient of determination in prediction ($r^2$: carbohydrates, 0.987; protein, 0.970; oil, 0.947) and low standard error of prediction (carbohydrates, 2.515; protein, 1.144; oil, 1.370). Therefore, these NIRS equations can be applicable for determination of carbohydrates, proteins, and oil contents in various foods.

• Science of Emotion and Sensibility
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• v.11 no.4
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• pp.613-628
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• 2008

Mind reading is an essential part of normal social functioning and empathy plays a key role in social understanding. This study investigated how individual differences can have an effect on reading emotions in facial expressions, focusing on empathizing and systemizing. Two experiments were conducted. In study 1, participants performed emotion recognition test using facial expressions to investigate how emotion recognition can be different as empathy-systemizing type, facial areas, and emotion type. Study 2 examined how emotion recognition can be different as empathy-systemizing type, facial areas, and emotion type. An emotion discrimination test was used instead, with every other condition the same as in studies 1. Results from study 2 showed mostly same results as study 1: there were significant differences among facial areas and emotion type and also have an interaction effect between facial areas and emotion type. On the other hand, there was an interaction effect between empathy-systemizing type and emotion type in study 2. That is, how much people empathize and systemize can make difference in emotional discrimination. These results suggested that the empathy-systemizing type was more appropriate to explain emotion discrimination than emotion recognition.

• Journal of the Korean Arthroscopy Society
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• v.10 no.1
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• pp.26-32
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• 2006

Purpose: We evaluated the result of the degree of reduction and anterior instability after arthroscopic treatment of tibial spine fractures. Materials and Methods: Thirty-two cases of tibial spine fractures treated with arthroscopic procedure could be evaluated and the mean follow-up period was $18\;(12{\sim}48)$ months. Evaluations included Lachman test, rotatory instability examination and side to side difference (SSD) using KT-2000 arthrometer. The degree of radiologic reduction was classified as accurate reduction, anterior elevation and reduction failure, according to which the degree of anterior instability was measured. Results: There were twenty three cases (71%) of accurate duction, eight cases (25%) of anterior elevation and one case (4%) of education failure. Eight (29%) of twenty eight cases with pull-out method showed anterior elevation. The SSDs of the accurate reduction and the anterior elevation group were 2.0 mm and 2.8 mm, respectively showing no significant difference. However, the percent age of grade 0 Lachman test and SSD less than 3 mm of the accurate reduction group were significantly higher. Conclusion: Accurate reduction is important in reducing anterior instability especially in unstable fractures. Therefore, arthroscopic pull-out method should be performed with great caution to avoid anterior elevation of the fracture fragment.