• Korean Journal of Cognitive Science
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• v.28 no.4
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• pp.315-328
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• 2017

Even though assessment using information and communication technology will most likely lead the future of educational assessment, there is little domestic research on this topic. Computerized assessment will not only cut costs but also measure students' performance in ways not possible before. In this context, this study introduces a tool which can overcome the problems of multiple choice tests, which are most widely used type of assessment in current Korean educational setting. Multiple-choice tests, in which options are presented with the questions, are efficient in that grading can be automated; however, they allow for students who don't know the answer, to find the correct answer from the options. Park(2005) has developed a modified multiple-choice testing system (CMMT) using the interactivity of computers, that presents questions first, and options later for a short time when the student requests for them. The present study was conducted to find out if penalizing wrong answers could lower the possibility of students choosing an answer among the options when they don't know the correct answer. 116 students were tested with the directions that they will be penalized for wrong answers, but not for no response. There were 4 experimental conditions: 2 conditions of high or low percentage of penalizing, each in traditional multiple-choice or CMMT format. The results were analyzed using a two-way ANOVA for the number of no response, the test score and self-report score. Analysis showed that the number of no response was significantly higher for the CMMT format and that test scores were significantly lower when the penalizing percentage was high. The possibility of applying CMMT format tests while penalizing wrong answers in actual testing settings was addressed. In addition, the need for further research in the cognitive sciences to develop computerized assessment tools, was discussed.

• Journal of Chest Surgery
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• v.31 no.12
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• pp.1172-1182
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• 1998

Background: Primary goal of anticoagulation treatment in patients with mechanical heart valve is the effective prevention of thromboembolism and safe avoidance of bleeding as well. Material and Method: Two-hundred and nine patients with the St. Jude Medical prosthesis operated on between 1984 and 1995, for mitral(MVR 122), aortic(AVR 39) and double mitral and aortic valve replacement(DVR 48) respectively, were studied on the practically achieved levels of anticoagulation and the clinical outcomes. Patients were on Coumadin and followed up by monthly visit to outpatient clinic for examination and prothrombin time measurement to adjust the International Normalized Ratios(INRs) within the low-intensity target range between 1.5 and 2.5. Result: A total anticoagulation follow-up period was 1082.0 patient- years(mean 62.1 months) and INRs of 10,205 measurements were available for evaluation. The accomplished INRs among the replacement groups were not significantly different and only 65% of INRs were within the target range. And, in individual patients, only 37% of patients had INRs included within the target range in more than 70% of tests during follow-up period. The levels of INRs in patients with atrial fibrillation, which was found in 57% of patients, were definitely higher than the ones measured in patients with regular rhythm(p<0.001). Thromboembolisms were experienced by 15 patients with the incidence of 1.265%/patient- year(MVR 1.412%, AVR 0.462% and DVR 1.531%/patient-year) and major bleeding by 4 patients with the incidence of 0.337%/patient-year(MVR 0.424%, AVR none and DVR 0.383%/patient-year). Frequent as well as prolonged missing of prothrombin time tests was the main risk factor strongly associated with the thromboembolic complications(odds ratio 1.99). The proportion of INRs within target range of less than 60% in individual patient was the highly significant risk factor of both thromboembolic and overall embolic and bleeding complications(p<0.004 and p<0.002 respectively). Conclusion: In conclusion, the low-intensity therapeutic target range of INRs was adequate in patients with AVR and in sinus rhythm. However, the patients with replacement of the mitral valve were more likely to require higher target range of INRs, especially in the presence of atrial fibrillation, to achieve the practical levels of anticoagulation enough to prevent thromboembolic complications effectively. For the higher therapeutic target range of INRs between 2.0∼3.0, further accumulation of clinical evidences are required. It is highly desirable to improve the patients' compliance under continuous instructions in visiting outpatient clinic and in taking daily Coumadin without omission and to keep INRs consistently within optimal range with tight control for minimization of chances and of periods of exposure to the risk of complications. And, particularly, patients with high risk of complications and with wide fluctuation of INRs should be better managed with frequent monitoring anticoagulation levels.

• Journal of the Korean earth science society
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• v.41 no.3
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• pp.248-260
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• 2020

Oceanic current maps introduced in science and earth science textbooks can offer a valuable opportunity for students to learn about rapid climate change and the role of currents associated with the global energy balance problem. Previously developed oceanic current maps in middle and high school textbooks under the 2007 and 2009-revised national curriculum contained various errors in terms of scientific accuracy. To resolve these problems, marine experts have constructed a unified oceanographic map of the oceans surrounding the Korean Peninsula. Since 2010, this process has involved a continuous, long-term consultation procedure. By extensively gathering opinions and through verification process, a representative and scientific oceanic current map was eventually constructed. Based on this, the educational oceanic current maps, targeting the comprehension of middle and high school students, were developed. These maps were incorporated into middle and high school textbooks in accordance with the revised 2015 curriculum. In this study, we analyzed the oceanic current maps of five middle school science textbooks and six earth science textbooks that were published in high school in 2019. Although all the oceanic current maps in the textbooks were unified based on the proposed scientific oceanic current maps, there were problems such as the omission of certain oceanic currents or the use of a combination of dotted and solid lines. Moreover, several textbooks were found to be using incorrect names for oceanic currents. This study suggests that oceanic current maps, produced by integrating scientific knowledge, should be visually accurate and utilized appropriately to avoid students' misconception.

• Radiation Oncology Journal
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• v.26 no.1
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• pp.1-9
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• 2008

Purpose: To evaluate the impact of postoperative radiotherapy on loco-regional failure in patients with vulvar carcinoma and to determine the treatment strategy for inguinal lymph nodes. Materials and Methods: Sixty-six patients who received treatment for primary vulvar carcinoma at Seoul National University Hospital, from October 1979 through June 2004, were retrospectively analyzed. Sixteen patients were excluded from the analysis due to the following reasons: distant metastases in two patients; palliative intent for six patients; previous radiotherapy given to the pelvis in three patients; follow-up loss after surgery for four patient; insufficient medical records for one patient. Of 50 eligible patients, 35 were treated with surgery alone(S), ten were treated with surgery followed by radiotherapy(S+RT), and five were treated with radiotherapy alone. Results: The 5-year overall survival(OS) and disease-free survival(DFS) rates of all patients were 91% and 78%, respectively. Twelve patients(26%) experienced treatment failures and the sites of initial failure were as follows: a primary site in eight patients; regional lymph nodes in three patients; the lung in one patient. Although risk factors for failure were more common in the S+RT group than the S group of patients(p<0.05), the DFS rates were similar for the two groups(5-year DFS rates, 78% vs. 83%, p=0.66). The incidences of occult lymph node metastases was 10%. Ten of 31 patients with clinically negative lymph nodes did not received inguinal lymph node dissection, but no patient experienced regional failure. Conclusion: Postoperative radiotherapy may have a potential benefit for patients with risk factors for failure. The omission of inguinal dissection or elective radiotherapy to the inguinal lymph nodes may be considered in low-risk patients with clinically negative lymph nodes.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.4
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• pp.228-232
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• 2006

Purpose: electrophilic $^{18}F(T_{1/2}=110\;min)$ radionuclide in the form of $[^{18}F]F_2$ gas is of great significance for labeling radiopharmaceuticals for positron omission tomography (PET). However, its production In high yield and with high specific radioactivity is still a challenge to overcome several problems on targetry. The aim of the present study was to develop a method suitable for the routine production of $[^{18}F]F_2$ for the electrophilic substitution reaction. Materials and Methods: The target was designed water-cooled aluminum target chamber system with a conical bore shape. Production of the elemental fluorine was carried out via the $^{18}O(p,n)^{18}F$ reaction using a two-step irradiation protocol. In the first irradiation, the target filled with highly enriched $^{18}O_2$ was irradiated with protons for $^{18}F$ production, which were adsorbed on the inner surface of target body. In the second irradiation, the mixed gas ($1%[^{19}F]F_2/Ar$) was leaded into the target chamber, fellowing a short irradiation of proton for isotopic exchange between the carrier-fluorine and the radiofluorine absorbed in the target chamber. Optimization of production was performed as the function of irradiation time, the beam current and $^{18}O_2$ loading pressure. Results: Production runs was performed under the following optimum conditions: The 1st irradiation for the nuclear reaction (15.0 bar of 97% enriched $^{18}O_2$, 13.2 MeV protons, 30 ${\mu}A$, 60-90 min irradiation), the recovery of enriched oxygen via cryogenic pumping; The 2nd irradiation for the recovery of absorbed radiofluorine (12.0 bar of 1% $[^{19}F]fluorine/argon$ gas, 13.2 MeV protons, 30 ${\mu}A$, 20-30 min irradiation) the recovery of $[^{18}F]fluorine$ for synthesis. The yield of $[^{18}F]fluorine$ at EOB (end of bombardment) was achieved around $34{\pm}6.0$ GBq (n>10). Conclusion: The production of $^{18}F$ electrophilic agent via $^{18}O(p,n)^{18}F$ reaction was much under investigation. Especially, an aluminum gas target was very advantageous for routine production of $[^{18}F]fluorine$. These results suggest the possibility to use $[^{18}F]F_2$ gas as a electrophilic substitution agent.

• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.41-51
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• 2004

PURPOSE: Tourette's disorder (TD), which is characterized by multiple waxing and waning motor tics and one or more vocal tics, is known to be associated with abnormalities in the dopaminergic system. To testify our hypothesis that risperidone would improve tic symptoms of TD patients through the change of the dopaminergic system, we measured the dopamine transporter (DAT) densities between drug-naive children with TD and normal children, and investigated the DAT density before and after treatment with risperidone in drug-naive children with TD, using iodine-123 labelled $N-(3-iodopropen-2-yl)-2{\beta}-carbomethoxy-3beta-(4-chlorophenyl)tropane$ ($[^{123}I]IPT$) single photon omission computed tomography (SPECT). MATERIALS and METHODS: $[^{123}I]IPT$ SPECT Imaging and Yale Global Tic Severity Scale-Korean version (YGTSS-K) for assessing the tic symptom severity were carried out before and after treatment with risperidone for 8 weeks in nine drug-naive children with TD. Eleven normal children also underwent SPECT imaging 2 hours after an intravenous administration of $[^{123}I]IPT$. RESULTS: Drug-naive children with TD had a significantly greater increase in the specific/nonspecific DAT binding ratio of both basal ganglia compared with the normal children. However, no significant difference in the specific/nonspecific DAT binding ratio of the basal ganglia before and after treatment with risperidone in children with TD was found, although tic symptoms were significantly improved with risperidone. CONCLUSION: These findings suggest that DAT densities are directly associated with the pathophysiology of TD, however, that the effect of risperidone on tic symptoms in children with TD is not attributed to the change of dopaminergic system.

• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.30-40
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• 2004

Purpose: The aims of this study were to find brain regions in which gray matter volume was reduced and to show the capability of voxel-based morphometry (VBM) analysis for lateralizing epileptogenic zones in medial temporal lobe epilepsy (mTLE). The findings were compared with fluorodeoxyglucose positron omission tomography (FDG PET). Materials and Methods: MR T1-weighted images of 12 left mTLE and 11 right mTLE patients were compared with those of 37 normal controls. Images were transformed to standard MNI space and averaged in order to create study-specific brain template. Each image was normalized to this local template and brain tissues were segmented. Modulation VBM analysis was performed in order to observe gray matter volume change. Gray matter was smoothed with a Gaussian kernel. After these preprocessing, statistical analysis was peformed using statistical parametric mapping software (SPM99). FDG PET images were compared with those of 22 normal controls using SPM. Results: Gray matter volume was significantly reduced in the left amygdala and hippocampus in left mTLE. In addition, volume of cerebellum, anterior cingulate, and fusiform gyrus in both sides and left insula was reduced. In right mTLE, volume was reduced significantly in right hippocampus. In contrast, FDG uptake was decreased in broad areas of left or right temporal lobes in left TLE and right TLE, respectively. Conclusions: Gray matter loss was found in the ipsilateral hippocampus by modulation VBM analysis in medial temporal lobe epilepsy. This VBM analysis might be useful in lateralizing the epileptogenic zones in medial temporal lobe epilepsy, while SPM analysis of FDG PET disclosed hypometabolic epileptogenic zones.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.4
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• pp.205-210
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• 2006

Purpose: FDG uptake on positron omission tomography (PET) has been considered a prognostic indicator in non-small cell lung cancer (NSCLC). The aim of this study was to assess the clinical significance of maximum value of SUV (maxSUV) in recurrence prediction in patients with surgically resected NSCLC. Materials & methods: NSCLC patients (n=42, F:M =14:28, age $62.3{\pm}12.3$ y) who underwent curative resection after FDG-PET were enrolled. Twenty-nine patients had pathologic stage 1, and 13 had pathologic stage II. Thirty-one patients were additionally treated with adjuvant oral chemotherapy. MaxSUVs of primary tumors were analyzed for correlation with tumor recurrence and compared with pathologic or clinical prognostic indicators. The median follow-up duration was 16 mo (range, 3-26 mo). Results: Ten (23.8%) of the 42 patients experienced recurrence during a median follow-up of 7.5 mo (range, 3-13 mo). Univariate analysis revealed that disease-free survival (DFS) was significantly correlated with maxSUV (<7 vs. $\geq7$, p=0.006), tumor size (<3 cm vs. $\geq3$ cm, p=0.024), and tumor tell differentiation (well/moderate vs. poor, p=0.044). However, multivariate Cox proportional analysis identified maxSUV as the single determinant for DFS (p=0.014). Patients with a maxSUV of $\geq7$(n=10) had a significantly lower 1-year DFS rate (50.0%) than those with a maxSUV of <7 (n=32, 87.5%). Conclusion: MaxSUV is a significant independent predictor for recurrence in surgically resected NSCLC. FDG uptake can be added to other well-known factors in prognosis prediction of NSCLC.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.3
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• pp.169-176
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• 2006

Purpose: According to the development of CT scanner in PET/CT system, the role of CT unit as a diagnostic tool has been more important. To improve the diagnostic ability of CT scanner, it is a key aspect that CT scanning has to be performed with high dose energy and intravenous (IV) contrast. So we investigated the effect of IV contrast media on the maximum SUV (maxSUV) of normal tissues and pathologic lesions using PET/CT scanner with high dose CT scanning. Materials & Methods: The study enrolled 13 patients who required PET/CT evaluation. At first, the patients were performed whole body non-contrast CT (NCCT-120 kVp, 130 mAs) scan. Then contrast enhanced CT (CECT) scan was performed immediately. Finally PET scan was followed. The PET omission data were reconstructed twice, once with the NCCT and again with the CECT. We measured the maxSUV of 10 different body regions that were considered as normal in ail patients. Also pathologic lesions were investigated. Results: There were not seen focal artifacts in PET images based on CT with IV contrast agent. Firstly, 130 normal regions in 13 patients were evaluated. The maxSUV was significantly different between two PET images (p<0.00)). The maxSUV was $1.1{\pm}0.5$ in PET images with CECT-corrected attenuation and $1.0{\pm}0.5$ in PET images with NCCI-corrected attenuation. The limit of agreement was $0.1{\pm}0.3$ in Bland-Altman analysis. Especially there were significant differences in 6 of 10 regions, apex and base of the right lung, ascending aorta, segment 6 & segment 8 of the liver and spleen (p<0.05). Secondly, 39 pathologic lesions were evaluated. The maxSUV was significantly different between two PET images (p<0.001). The maxSUV was $4.7{\pm}2.0$ in PET images with CECT-corrected attenuation and $4.4{\pm}2.0$ in PET images with NCCT-corrected attenuation. The limit of agreement was $0.4{\pm}0.8$ in Bland-Altman analysis. Conclusion: Although there were increases of maxSUVs in the PET images based on CT with IV contrast agent, it was very narrow in the range of limit of agreement. So there was no significant effect to clinical interpretation for PET images that were corrected attenuation with high dose CT using IV contrast.

• The Korean Journal of Nuclear Medicine
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• v.35 no.6
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• pp.378-388
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• 2001

Purpose: In this study, we developed a new method for the determination of renal depth with anterior and posterior renal scintigrams in a dual-head gamma camera, considering the attenuation factor $e^{-{\mu}x}$ of the conjugate-view method. Material and Method: We developed abdomen and kidney phantoms to perform experiments using Technetium-99m dimercaptosuccinic acid ($^{99m}Tc$-DMSA). The phantom images were obtained by dual-head gamma camera equipped with low-energy, high-resolution, parallel-hole collimators (ICONf, Siemens). The equation was derived from the linear integration of omission ${\gamma}$-ray considering attenuation from the posterior abdomen to the anterior abdomen phantom surface. The program for measurement was developed by Microsoft Visual C++ 6.0. Results : Renal depths of the phantoms were derived from the derived equations and compared with the exact geometrical values. Differences between the measured and the calculated values were the range of 0.1 to 0.7 cm ($0.029{\pm}0.15cm,\;mean{\pm}S.D.$). Conclusion: The present study showed that the use of the derived equations for renal depth measurements, combined with quantitative planar imaging using dual-head gamma camera, could provide more accurate results for individual variation than the conventional method.