• Resources Recycling
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• v.16 no.5
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• pp.51-56
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• 2007

Plastics are widely used in everyday life as very useful material. In Korea, about 4 million tons of plastic wastes are generated annually. However, recycling ratio is below 30%, and most of plastic wastes are disposed by landfill and incineration. Hence, the development of material separation technique that can recycle plastic wastes is a necessary situation. In this study, Triboelectrostatic separation for recovery of PET from final plastic wastes obtained from the sink product after wet-type gravity separation has been carried out. In the charging properties, the charge polarity and charge density of PET and PVC were very effective with the tirbo-charger made of PP and HDPE with the decrease in relative humidity. In material separation using HDPE cyclone charger, a PET grade of 96.80% and a recovery of 85.0% were achieved at 30 kV and the splitter position -2cm from the center. In order to obtain PET grade of 98.5%, PET recovery should be sacrificed by 24% with moving the splitter from the center to -6cm position.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.17-25
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• 2014

Wide spread application and non-biodegradability of the poly(ethylene terephthalate) generate a huge amount of waste and disposal, posing serious environmental problems. Disposal of the PET wastes also can be thought as an economic loss of valuable chemical resources. We present various ways of feedstock recycling of PET waste to deal with environmental and economic problems. Feedstock recycling is one of promising technologies. It is based on the concept of depolymerizing the condensation polymer such as PET through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high quality chemical products.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.423-430
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• 2012

This study focused on the characterization of recycle PE/PET/TPE blend with compatibilizers. The heat resistance and impact strength of a weak point on PET/HDPE blend has been improved. TPE added polyester-based recycle heat-resistant properties to $150^{\circ}C$ showed more than $50^{\circ}C$ higher than HDPE added. Elastomer applied is a significant increase in the impact strength, and then it is possible to apply for safety materials in industries requiring heat-resistance and elasticity. Also using PET blend compatibilizer improves the strength of the polyolefin resin. The mechanical properties of recycle HDPE and PET blend has been greatly improved, and the reduction in the size of the dispersed phase by the addition of compatibilizers on morphology characteristics were observed uniformity becomes.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.1
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• pp.42-48
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• 2007

Purpose: The purpose of this study is to image metastaic lung melanoma model with optimal pre-conditions for animal handling by using $[^{18}F]FDG$ small animal PET and clinical CT. Materials and Methods: The pre-conditions for lung region tumor imaging were 16-22 h fasting and warming temperature at $30^{\circ}C$. Small animal PET image was obtained at 60 min postinjection of 7.4 MBq $[^{18}F]FDG$ and compared pattern of $[^{18}F]FDG$ uptake and glucose standard uptake value (SUVG) of lung region between Ketamine/Xylazine (Ke/Xy) and Isoflurane (Iso) anesthetized group in normal mice. Metastasis tumor mouse model to lung was established by intravenous injection of B16-F10 cells in C57BL/6 mice. In lung metastasis tumor model, $[^{18}F]FDG$ image was obtained and fused with anatomical clinical CT image. Results: Average blood glucose concentration in normal mice were $128.0{\pm}23.87$ and $86.0{\pm}21.65\;mg/dL$ in Ke/Xy group and Iso group, respectively. Ke/Xy group showed 1.5 fold higher blood glucose concentration than Iso group. Lung to Background ratio (L/B) in SUVG image was $8.6{\pm}0.48$ and $12.1{\pm}0.63$ in Ke/Xy group and Iso group, respectively. In tumor detection in lung region, $[^{18}F]FDG$ image of Iso group was better than that of Ke/Xy group, because of high L/B ratio. Metastatic tumor location in $[^{18}F]FDG$ small animal PET image was confirmed by fusion image using clinical CT. Conclusion: Tumor imaging in small animal lung region with $[^{18}F]FDG$ small animal PET should be considered pre-conditions which fasting, warming and an anesthesia during $[^{18}F]FDG$ uptake. Fused imaging with small animal PET and CT image could be useful for the detection of metastatic tumor in lung region.

• Journal of Chest Surgery
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• v.36 no.2
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• pp.79-85
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• 2003

Diagnosing and determining the stage of lung cancer by means of positron emission tomography (PET) ha.. been proven valuable because of the limitations of diagnosis by computed tomography (CT). We compared the efficacy of PET with that of CT in diagnosing pulmonary tumor and staging of lung cancer Material and Method: We performed F-18 FDG PET to determine the malignancy and the staging on patients who have been suspicious or were diagnosed as lung cancer by chest X-ray and CT. The findings of PET and of CT of 41 patients (male, 29: female, 12: mean age, 59) were compared with pathologic findings obtained from a mediastinoscopy and thoracotomy. Result: Out of 41 patients, 35 patients had malignant lesions (squamous cell carcinonla 19 cases, adenocarcinoma 14 cases, adenosquamous cell carcinoma 2 cases) and 6 patients had benign lesions. Diagnosing of lung cancer, the sensitivity, specificity and accuracy of CT and PET were the same for two method and the numbers were 100%, 50%, and 92.7% respectively. Eighteen LN groups out of 108 mediastinal LN groups who recieved histologic examination proved to be malignant. Pathologic lymph node (LN) stage was N0-Nl 31 cases, N2 8 cases, N3 2 cases. The correct identification of the nodal staging with CT, PET scans were 31 cases (75.6%), 28 cases (68.3%) respectively. The LN group was underestimated in each 6 cases of CT and PET. In 4 cases of CT and 7 cases of PET, they were overestimated in compare to histologic diagnosis. In the detection of mediastinal LN groups invasion, the sensitivity, specificity and accuracy of CT were 39.8 %, 93.3 %, and 84.3 % respectively. For PET, they were 61.1 %, 90.0 %, and 85.2 %. When two methods considered together (CT+PET), they were increased to 77.8 %, 93.3 %, and 90.7 % respectively. Conclusion: PET appears to be similar to CT in the diagnosis and the nodal taging of pulmonary tumor. Two tests may stage patients with lung cancer more accurately than CT alone.

• Journal of radiological science and technology
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• v.29 no.4
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• pp.249-255
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• 2006

Purpose: The diagnostic utility of fluorine-18 2-deoxy-D-glucose positron emission tomograhpy ($^{18}F-FDG $PET) for the non-invasive differentiation of focal lung lesions originated from cancer or inflammation disease by combined visual image interpretation and semi-quantitative uptake value analysis has been documented. In general, Standardized Uptake Value(SUV) is used to diagnose lung disease. But SUV does not contain dynamic information of lung tissue for the glucose. Therefore, this study was undertaken to hypothesis that analysis of dynamic kinetics of focal lung lesions base on $^{18}F-FDG$ PET may more accurately determine the lung disease. So we compared Time Activity Curve(TAC), Standardized Uptake Value-Dynamic Curve(SUV-DC) graph pattern with Glucose Metabolic Rate(MRGlu) from Patlak analysis. Methods: With lung disease, 17 patients were examined. They were injected with $^{18}F-FDG$ over 30-s into peripheral vein while acquisition of the serial transaxial tomographic images were started. For acquisition protocol, we used twelve 10-s, four 30-s, sixteen 60-s, five 300-s and one 900-s frame for 60 mins. Its images were analyzed by visual interpretation TAC, SUV-DC and a kinetic analysis(Patlak analysis). The latter was based on region of interest(ROIs) which were drawn with the lung disease shape. Each optimized patterns were compared with itself. Results: In TAC patterns, it hard to observe cancer type with inflammation disease in early pool blood area but over the time cancer type slope more remarkably increased than inflammation disease. SUV-DC was similar to TAC pattern. In the result of Patlak analysis, In time activity curve of aorta, even though inflammation disease showed higher blood activity than cancer, at first as time went by, blood activity of inflammation disease became the lowest. However, in time activity curve of tissue, cancer had the highest uptake and inflammation disease was in the middle. Conclusion: Through the examination, TAC and SUV-DC could approached the results that lung cancer type and inflammation disease type has it's own difference shape patterns. Also, it has outstanding differentiation between cancer type and inflammation in Patlak and MRGlu analysis. Through these analysis methods, it will helpful to separation lung disease.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.153-159
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• 2014

During the winter and spring seasons in Korea, structures such as buried water supply pipelines, roads, railways are frequently damaged due to frost heaving and thawing. Until now, the method of substituting the frost susceptible soil with the gravel or rubbles those are non-frost susceptible materials have been employed in Korea to prevent frost heaving. A series of laboratory soil tests and indoor frozen soil engineering experiments, as well as laboratory frost heaving tests were conducted for seeking the means of utilizing recycled PET bottles as substitute material.

• Resources Recycling
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• v.32 no.3
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• pp.57-67
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• 2023

The treatment of waste plastic has primarily been entrusted to small companies, which has resulted in challenges in obtaining an accurate overview of the current state of affairs and ensuring profitability. Consequently, despite the presence of recycling technology, their practical application has proven to be challenging. In this study, as part of the waste plastic material recycling plan, it is assumed that the PET/OPP laminated waste film is peeled off at the waste film generation site for the second use. The recycling rate of PET/OPP delaminated waste film is assumed to be 2%, 10%, and 30% referring to the figures suggested by "Life-cycle Post Plastic Measures" from the Korean government. In this study, a physical separation method was developed as a recycling approach for waste PET. A result of cost-benefit analysis was conducted to evaluate the economic viability of the recycling process based on changes in the recycling rate. The findings indicated that a recycling rate of waste PET was 30% or higher resulted in a cost-benefit ratio (Benefit-cost ratio, BCR) of 1.32, exceeding the threshold of BCR ≥1, which is considered to meet the minimum requirement for cost-benefit balance. As the government's allocation ratio and unit price are expected to increase in the future, the cost-benefit ratio is expected to increase further. This case is expected to serve as a pilot initiative for waste PET recycling and foster profit creation for businesses in similar industries.

• Tuberculosis and Respiratory Diseases
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• v.55 no.6
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• pp.589-596
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• 2003

Background : The solitary pulmonary nodule(SPN) presents a diagnostic dilemma to the physician and the patients in the our nation with high incidence of tuberculoma. We could not exclude whether the SPN was benign or malignant by the change of the size at chest radiograph and findings of chest CT. Recently, positron emission tomography(PET) have been tried as the differential diagnostic method of SPN. We evaluated the efficacy of PET for differentiating malignant from benign SPN and the relationship between standardized uptake values(SUV) of PET and serum glucose. Method : Between January 2001 and July 2002, sixty-one patients with pulmonary nodule were examined by the chest CT and PET. The SPN has been finally diagnosed by the transthorasic needle aspiration and biopsy, bronchoscopic biopsy, and open lung biopsy. Results : Forty eight patients had a malignant nodule(23 squamous cell lung carcinoma, 16 adenocarcinoma, 9 small cell lung cancer) and thirteen patients had a benign nodule(3 tuberculoma, 9 inflammatory granuloma, 1 cryptococcosis). The mean size of malignant and benign nodule was 40.6 mm and 20.0 mm, respectively. All malignant nodules showed a marked increase in 18 fluorodeoxyglucose (FDG) uptake. Mean SUV of malignant was $9.52{\pm}5.20$ and benign nodule was $1.61{\pm}3.60$. There were false positive cases with an increase in 18-FDG uptake (2 tuberculoma, 1 inflammatory granuloma). The SUV of malignant nodule in diabetes patients has no difference in non diabetes patients($9.10{\pm}4.51$ vs $9.65{\pm}5.46$). The sensitivity and specificity of the PET scan for SPN were 100%, 77%, respectively. The positive and negative predictive values were 94% and 100%. Conclusion : PET scanning showed highly accurate result in differentiating the malignant and benign SPN. There were no significant differences between the SUV and serum glucose in the patients with lung cancer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.102-108
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• 2010

The main objective of this study was to evaluate the effect of recycled PET (RPET) fiber made from waste PET bottles to examine application on concrete member. To evaluate the reinforcement effect of RPET fiber in concrete member, experimental tests were performed, such as mechanical property tests (compressive strength, modulus of elasticity and splitting tensile strength) and drying shrinkage test. In mechanical property tests, compressive strength and modulus of elasticity in concrete mixed with RPET fiber gradually decreased, but splitting tensile strength gradually increased as volume fraction of fiber increased. In drying shrinkage test, free drying shrinkage increased. In restrained case, in contrast, crack occurrence was delayed because of tensile resistance increase by RPET fiber. The comparison of RPET and PP fiber added concrete specimen's properties showed that two materials had similar properties. In conclusion, RPET fiber is an alternative material of PP fiber, even finer for its excellence in eco-friendliness due to the recycling of waste PET bottles and its possible contribution to the pollution declination.