• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.68-73
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• 2015

Purpose The purpose of this study was to evaluate image quality change by truncated region in field of view (FOV) of attenuation correction computed tomography (AC-CT) in brain PET/CT. Materials and Methods Biograph Truepoint 40 with TrueV (Siemens) was used as a scanner. $^{68}Ge$ phantom scan was performed with and without applying brain holder using brain PET/CT protocol. PET attenuation correction factor (ACF) was evaluated according to existence of pallet in FOV of AC-CT. FBP, OSEM-3D and PSF methods were applied for PET reconstruction. Parameters of iteration 4, subsets 21 and gaussian 2 mm filter were applied for iterative reconstruction methods. Window level 2900, width 6000 and level 4, 200, width 1000 were set for visual evaluation of PET AC images. Vertical profiles of 5 slices and 20 slices summation images applied gaussian 5 mm filter were produced for evaluating integral uniformity. Results Patient pallet was not covered in FOV of AC-CT when without applying brain holder because of small size of FOV. It resulted in defect of ACF sinogram by truncated region in ACF evaluation. When without applying brain holder, defect was appeared in lower part of transverse image on condition of window level 4200, width 1000 in PET AC image evaluation. With and without applying brain holder, integral uniformities of 5 slices and 20 slices summation images were 7.2%, 6.7% and 11.7%, 6.7%. Conclusion Truncated region by small FOV results in count defect in occipital lobe of brain in clinical or research studies. It is necessary to understand effect of truncated region and apply appropriate accessory for brain PET/CT.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.2
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• pp.373-379
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• 2002

This paper was the design of aerosol generator for inhalation toxicology study of lead and evaluation with real time monitoring, and applied several engineering methodology to classical aerosol generator to cope with it's disadvantages. According to the testing conditions, source temperature 50℃ and inlet-duct band heater temperature 150℃, aerosol generation results for sodium chloride and lead acetate were as followings: CPM(Count Per Minute) for Sodium chloride that used for the testing material in aerosol generation and inhalation system was decreased in the 2nd and the 3rd hour's serial trials, but CVs(coefficient of variation) were maintained within 10%. CPMs for 5 and 2.5 gram of lead acetate that used for aerosol generation and inhalation exposure of lead showed similar results because of the sedimentation of lead acetate on piezoelectric crystal with time. For that reason, heating and mixing of nebulizing solution will be needed to generate lead aerosol with stable profile and maximum generation efficiency. Fluctuations of 10 and 5 gram lead acetate were low but 2.5gram was high. However, CVs for 10, 5, and 2.5gram lead acetate were within 10%. Considering the theoretical efficiencies for sodium chloride and lead acetate, 5gram sodium chloride and 2.5gram lead acetate were appropriate choice. Aerosol generation characteristics for two materials with 1 hour interval were different with respect to the fluctuation of CPM and the decrease to 10gram in it's material. For that reason, sodium chloride can not be used to estimate the aerosol generation and it's related parts for lead acetate. According to the testing conditions, source temperature 20, 50, 70℃, and inlet-duct band heater temperature 20, 50, 100, 150, 200℃, aerosol generation results for sodium chloride and lead acetate were as followings: Excluding inlet-duct band temperature 200℃, maximum CPM for sodium chloride was manifested in source temperature 70℃ with each inlet-duct band temperature conditions. We suggest that this condition was the optimum in the design of aerosol generator, inhalation system, and the testing. Maximum CPMs for 10, 5, and 2.5gram sodium chloride were from source temperature 70℃ and inlet-duct band temperature 20℃. Excluding inlet-duct band temperature 50, 200℃, maximum CPMs for lead acetate were indicated in source temperature 50℃ with each inlet-duct band temperature conditions. We suggest that this condition was the optimum in the design of aerosol generator, inhalation system, and the testing for lead inhalation study. Source and inlet-duct band temperatures for 10, 5, 2.5gram lead acetate were 50 and 100℃, 50 and 100℃, 50 and 150℃, respectively. In conclusion, considering above 2 paragraphs of results for aerosol generation, 5gram efficiencies for sodium chloride, lead acetate were higher than 2.5gram's. If inlet-duct band temperature was same, aerosol generation was increased with increase of source temperature. To get maximum aerosol generation will be the conditions that set the appropriate inlet-duel band temperature for each materials and increase the source temperature.

• Journal of the Korean Wood Science and Technology
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• v.19 no.1
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• pp.31-63
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• 1991

It was proved that in conventional kiln drying of disks piling position in the kiln exerted a great influence on drying rates, and the larger the variation of disk diameter, the more undulating drying rates of disks. While in vacuum drying disks there was no influence on drying rates. By the end-wrapping treatments and the radial direction of disks tangential surface stresses in the core of disks were slightly compressive in three species. In control disks the drying stresses distributed into one step-style that compressive stresses in the pith side of 6cm from pith were larger than those in the bark side, while in the disks end-wrapped with Korean paper the drying stresses distributed uniformly, because flow rates of free water in disks had no difference between heart-and sap-wood by obstruction of evaporating water from surface of disks by end-wrapping with Korean paper. And end-wrapping with Korean paper considerably restrained those. Tangential differential shrinkage stresses developed the maximum tensile stress near the bark and with approaching the pith the stresses gradually reduced and changed into compressive stresses in near the pith. At the end of vacuum drying the maximum tangential tensile stresses of disks end-wrapped with Korean paper were smaller than those of control disks, and critical moisture contents causing the V-shaped crack of disks end-wrapped with Korean paper were lower than those of control disks because of the set by obstruction of evaporating water of end-wrapping with Korean paper. In the experiment of vacuum drying stress distribution the disks end-wrapped with Korean paper or aluminum foil in three species were free from V-shaped cracks and control disks were defected very slightly by V-shaped cracks. And also disks end-wrapped with Korean paper were free from heart checks in Alnus japonica and Juglans sinensis, and heart checks were occurred very slightly in others. Especially, not to speak of disks end-wrapped with Korean paper, vacuum drying of disks end-wrapped with aluminum foil prevented effectively drying defects, moreover drying times could be shortened, that is. Ginkgo biloba, Alnus japonica, and Juglans sinensis disks could be dried from green to in-use moisture content in 110 hours, 272 hours, and 407 hours, respectively.

• Journal of Chest Surgery
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• v.34 no.11
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• pp.831-842
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• 2001

Background: Patients with cardiac diseases who have structural defects in their heart bring about metabolic insult such as preoperative acid-base imbalance. Cardiac operation requires many nonphysiologic procedures such as extracorporeal circulation, hypothermia, and hemodilution. We studied the acid-base status of surgical heart diseases pre-operatively, during extracorporeal circulation, and post-operatively and researched the treatment indications of acid-base disturbances. Material and Method: From January 1997 to May 1999, fifty two cases of open heart surgery were carried out under extracorporeal circulation, which divided into a set of pediatric and adult groups, congenital and acquired groups, non-cyanotic and cyanotic groups, The $\alpha$ -stat arterial blood gas analysis was done in each group during the preoperative period, during the operation with extracorporeal circulation, and during the postoperative period. Result: Before surgery, all patients present metabolic acidosis, PaO2 was low in adult group and acquired group and compensatory respiratory alkalosis was noted in cyanotic group. During extracorporeal circulation, adult group revealed alkalosis and normal in acquired group. Pediatric group presents low Pa$CO_2$, metabolic acidosis and respiratory alkalosis. Congenital group and non-cyanotic group showed non-compensatory alkalosis trend and non-compensatory respiratory acidosis were observed in cyanotic group during extracorporeal circulation. Postoperative acid-base status of adult group was recovered to normal and the standard bicarbonate was increased in the acquired group. All of the pediatric, congenital non-cyanotic, and cyanotic groups revealed the lack of buffer base.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.199-210
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• 2002

In this paper, we carried out the study on speech recognition using the KM-Net topology design algorithm based on decision tree state-clustering to improve the performance of acoustic models in speech recognition. The Korean has many allophonic and grammatical rules compared to other languages, so we investigate the allophonic variations, which defined the Korean phonetics, and construct the phoneme question set for phonetic decision tree. The basic idea of the HM-Net topology design algorithm is that it has the basic structure of SSS (Successive State Splitting) algorithm and split again the states of the context-dependent acoustic models pre-constructed. That is, it have generated. the phonetic decision tree using the phoneme question sets each the state of models, and have iteratively trained the state sequence of the context-dependent acoustic models using the PDT-SSS (Phonetic Decision Tree-based SSS) algorithm. To verify the effectiveness of the above algorithm we carried out the speech recognition experiments for 452 words of center for Korean language Engineering (KLE452) and 200 sentences of air flight reservation task (YNU200). Experimental results show that the recognition accuracy has progressively improved according to the number of states variations after perform the splitting of states in the phoneme, word and continuous speech recognition experiments respectively. Through the experiments, we have got the average 71.5%, 99.2% of the phoneme, word recognition accuracy when the state number is 2,000, respectively and the average 91.6% of the continuous speech recognition accuracy when the state number is 800. Also we haute carried out the word recognition experiments using the HTK (HMM Too1kit) which is performed the state tying, compared to share the parameters of the HM-Net topology design algorithm. In word recognition experiments, the HM-Net topology design algorithm has an average of 4.0% higher recognition accuracy than the context-dependent acoustic models generated by the HTK implying the effectiveness of it.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.175-182
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• 2001

The main focus of this study was set to help college students in Kangwon province to improve and correct dietary habits and to maintain healthy life. The nutritional status and food preference of college students were examined from May to July, 1999. The collection of the research data has been made on the basis of questionnaries for 184 college students residing in Kangwon province. Statistical analysis of the data was performed using SAS package program for descriptive frequency and statistical significance. The meal skipping ratio of the subjects were 2% and for the reasons of meal skipping 45% responded "lack of time". As for main dishes, cooked rice turned out to be the most preferred by the subjects and the second and third favored by female students were bread and noodle respectively. Most preferred side-dishes were meat soup, kimchi, laver Kui,squid Bockeum, fried squid, beef Chon, squid Chorim, soy Namul, Dubuk Changachi and squid Muchim. Less preferred side-dishes include radish soup, white kimchi, mugwort fry, liver Bockeum, liver sheon and egg plant Kui. No one-plate food was disliked by the subjects. Male liked Manndukuk and female liked cuttle fish rice. The intakes of nutrient except for energy, iron and calcium for female students were the same or above the Recommended Dietary Allowances (RDA) for Koreans.

• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.493-500
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• 2017

In this study, data analysis has been conducted by INFINITT program to analyze the effect of signal to noise ratio(SNR) and contrast to noise ratio(CNR) of flow related enhancement(FRE) and computed tomography Angiography(CTA) on cerebrovascular diseases for qualitative evaluations. Based on the cerebrovascular image results achieved from 63 patients (January to April, 2017, at C University Hospital), we have selected 19 patients that performed both FRE-MRA and CTA. From the 19 patients, 2 were excluded due to artifacts from movements in the cerebrovascular image results. For the analysis conditions, we have set the 5 part (anterior cerebral artery, right and left Middle cerebral artery, right and left Posterior cerebral artery) as the interest area to evaluate the SNR and CNR, and the results were validated through Independence t Test. As a result, by averaging the SNR, and CNR values, the corresponding FRE-MRA achieved were: anterior cerebral artery ($1500.73{\pm}12.23/970.43{\pm}14.55$), right middle cerebral artery ($1470.16{\pm}11.46/919.44{\pm}13.29$), left middle cerebral artery ($1457.48{\pm}17.11/903.96{\pm}14.53$), right posterior cerebral artery ($1385.83{\pm}16.52/852.11{\pm}14.58$), left posterior cerebral artery ($1318.52{\pm}13.49/756.21{\pm}10.88$). by averaging the SNR, and CNR values, the corresponding CTA achieved were: anterior cerebral artery ($159.95{\pm}12.23/123.36{\pm}11.78$), right middle cerebral artery ($236.66{\pm}17.52/202.37{\pm}15.20$), left middle cerebral artery ($224.85{\pm}13.45/193.14{\pm}11.88$), right posterior cerebral artery ($183.65{\pm}13.47/151.44{\pm}11.48$), left posterior cerebral artery ($177.7{\pm}16.72/144.71{\pm}11.43$) (p < 0.05). In conclusion, MRA had high SNR and CNR value regardless of the cerebral infarction or cerebral hemorrhage observed in the 5 part of the brain. Although FRE-MRA consumed longer time, it proved to have less side effect of contrast media when compared to the CTA.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.47-60
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• 2010

Most of the researches about classification usually have used kNN(k-Nearest Neighbor), SVM(Support Vector Machine), which are known as learn-based model, and Bayesian classifier, NNA(Neural Network Algorithm), which are known as statistics-based methods. However, there are some limitations of space and time when classifying so many web pages in recent internet. Moreover, most studies of classification are using uni-gram feature representation which is not good to represent real meaning of words. In case of Korean web page classification, there are some problems because of korean words property that the words have multiple meanings(polysemy). For these reasons, LSA(Latent Semantic Analysis) is proposed to classify well in these environment(large data set and words' polysemy). LSA uses SVD(Singular Value Decomposition) which decomposes the original term-document matrix to three different matrices and reduces their dimension. From this SVD's work, it is possible to create new low-level semantic space for representing vectors, which can make classification efficient and analyze latent meaning of words or document(or web pages). Although LSA is good at classification, it has some drawbacks in classification. As SVD reduces dimensions of matrix and creates new semantic space, it doesn't consider which dimensions discriminate vectors well but it does consider which dimensions represent vectors well. It is a reason why LSA doesn't improve performance of classification as expectation. In this paper, we propose new LSA which selects optimal dimensions to discriminate and represent vectors well as minimizing drawbacks and improving performance. This method that we propose shows better and more stable performance than other LSAs' in low-dimension space. In addition, we derive more improvement in classification as creating and selecting features by reducing stopwords and weighting specific values to them statistically.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.65-70
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• 2009

Reduction of groundwater surface tension prior to air sparging (SEAS, surfactant-enhanced air sparging) was known to increase air saturation in the aquifer under influence, possibly enhancing the removal rates of volatile contaminants. Although SEAS was known to be efficient for increasing air saturation, little information is available for different hydrogeological settings including soil particle sizes and the depth of aquifer. We investigated water saturations in the sparging influence zone during SEAS using one-dimensional column packed with sands of different particle sizes and different aquifer depths. An anionic surfactant was used to suppress the surface tension of water. Two different sands were used; the air entry pressures of the sands were measured to be $15.0\;cmH_2O$, and $36.3\;cmH_2O$, respectively. No significant difference was observed in the water saturation-surface tension relationship for sands with different particle sizes. As the surface tension decreased, the water saturation decreased to a lowest point and then it increased with further decrease in the surface tension. Both sands reached their lowest water saturations when the surface tension was set approximately at 42 dyne/cm. SEAS was conducted at three different aquifer depths; 41 cm, 81 cm, and 160 cm. Water saturation-surface tension relationship was consistent regardless of the aquifer depth. The size of sparging influence zone during SEAS, measured using two-dimensional model, was found to be similar to the changes in air saturation, measured using one-dimensional model. Considering diverse hydrogeological settings where SEAS to be applied, the results here may provide useful information for designing SEAS process.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.98-103
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• 2014

Purpose: The effective half life of I-131 is useful to calculate radiation dose, period of hospitalization, and exposure dose of surrounding people from patient. However, it is difficult to measure. This study estimates the effective half life in whole body and thyroid in using of value of residual radioactivity obtained from the early and delay images of Dual time I-131 whole body scan. Also, the correlations between the effective half life and serum creatinine, GFR, and administration dose were investigated in this study. Materials and Methods: The targets were 50 patients administration high dose of I-131 from February to August in 2013, having normal range of serum creatinine and over $30{\mu}IU/mL$ of TSH levels. After administration radioactive I-131, the early scan in the 3rd day and the delay scan in the 5-6th days were performed. To measure the residual radioactivity in the whole body and thyroid, ROI was set and then background radioactivity was corrected to estimate. The effective half life was estimated by calculating the ratio of measured values between the early and delay images. To compare the effective half lives of the whole body and thyroid, it was analyzed by Independent t-test, and each correlation of the effective half life, GFR, serum creatinine, and the dose of administration were analyzed by calculating the pearson's correlation coefficient. All of the analysis were determined to be statistically significant when P<0.05. Results: The effective half life of the whole body was $17.06{\pm}5.50$ hours and of the thyroid was $17.22{\pm}5.41$ hours. The two effective half life did not show significant difference (P=0.887). As the value of GFR was increased, the effective half life of whole body (r=-0.407, P=0.003) and of thyroid (r=-0.473, P=0.001) were significantly decreased; as the value of serum creatinine was increased, the effective half life of whole body (r=0.309, P=0.029) and of thyroid (r=0.371, P=0.008) were significantly increased. In the administration dose, effective half life did not have correlations. Conclusion: The effective half life of I-131 of patients treated for their thyroids were estimated only by using the images of Dual time I-131 whole body scan. Also, the correlations with the effective life, GFR, and serum creatinine were examined. This study might be utilized for a study on optimization for the period of hospitalization of patients treated by high dose of I-131 and on evaluation for internal absorbed dose of MIRD schema in application of the effective half life.