• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.405-411
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• 2016

This paper presented the theory related to a two dimensional linear cross-sectional analysis, recovery relationship and a one-dimensional nonlinear beam analysis for composite beam with initial twist and high aspect ratio. Using VABS including related theory, preceding research data of the composite wing structure has been modeled and compared. Cross-sectional analysis was performed and 1-D beam was modeled at cutting point including all the details of real geometry and material. The 3-D strain distribution and margin of safety at recovery point was calculated based on the global behavior of the 1-D beam analysis and visualize numerical results.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.229-236
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• 2005

To cope with increasing requirements of cost reduction, labor saving, and rapid construction, the purpose of this study is to investigate the structural behavior of PSC monolithic and spliced girders. Three tests were conducted on reduced-scale girder specimens having same type. This paper presents the result of experimental studies on the load-deflection behavior in which different joint and amount of tendon as major variables were investigated. The first one used a monolithic girder was arranged with three tendons. The second one used a spliced girder was joined with three tendons after producing five segments. And the third girder was produced in same conditions with the second girder and arranged with additional tendons. The experimental results show the difference of behavior between monolithic and spliced girders.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.5
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• pp.99-106
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• 2007

To satisfy with the increased requirements of cost reduction, labor saving, and rapid construction, the purpose of this study is to investigate the structural behavior of PSC monolithic and spliced girders. Three tests were conducted on small-scale girder specimens. This paper presents the result of experimental studies in terms of the load-deflection behavior. Different joint type and tendon amount were investigated as major variables. The monolithic girder was arranged with three tendons. The spliced girder consisted of five segments connected by three tendons. In addition, five-segmented girders connected by more than three tendons were built to examine the effect of the tendon amount. The experimental results show the difference of behavior between monolithic and spliced girders. Moreover, nonlinear finite element method analysis was utilized to verify the experimental result.

• Korea Real Estate Review
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• v.28 no.3
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• pp.65-77
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• 2018

The purpose of this study is to analyze the effect of the educational environment on the prices of studio apartments, known as officetels, in Korea. Since the revision of relevant laws in 2010, they have served as substitutes for residential purposes in areas suffering from housing shortage, especially where the educational environment is a significant factor. To assess the relation between the educational environment and rental rates, the hedonic price model and artificial neural networks were implemented. The national assessment of the academic performance of middle and high schools that were closest to each officetel, and the ratio of students going to special-purpose schools and private high schools were considered as independent variables. Research findings indicated that the positive effect of the dependent variable increased as the value of educational environment-related variables increased. This result could be utilized as a functional index for housing providers after considering educational environments.

• Research in Plant Disease
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• v.16 no.3
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• pp.299-305
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• 2010

Objective of this study is to examine whether pine wood nematode (PWN: Bursaphelenchus xylophilus) in the sawdust discharged from infected trees cause pine wood disease or not. For this, survival time of PWN in soil was examined in which soil moisture was controlled as 15%, 22.5%, and 30% in volume ratio, respectively. The pathogenicity tests were conducted under greenhouse and field conditions. Survival time of PWN in soil was about three days in the saturated (about soil moisture of 23% in volume ratio) and dark condition between 25 and $28^{\circ}C$ of room temperature. None of potted seedlings with non-wounded roots was infected by PWN in sawdust. In field, pine wood disease was not occur in any pine trees. These results indicated that PWN discharged on soil when the infected trees were cut by chain saw can not cause pine wood disease.

• Korean Journal of Heritage: History & Science
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• v.52 no.3
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• pp.240-251
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• 2019

This study examined the manufacturing technology used for the flat iron axes excavated from Ulsan Hadae. Their microstructures were analyzed using metallurgical methods. In addition, a variety of manufacturing technologies were examined and compared using existing research materials on flat iron axes. As a result of analyzing ten flat iron axes, which were excavated in the order that they were laid out in a row in one of the wooden coffin tombs at Ulsan Hadae, Tomb No. 44, it was possible to classify the flat iron axe manufacturing technology and system into three types: 'pure iron - shape processing', 'pure iron - shape processing - carburizing', and 'pure iron - shape processing - carburizing - decarburizing.' All of the flat iron axes were produced by forging, and most of them were made by beating the pure iron into their shapes. In particular, a number of the flat iron axes were reinforced through a carburizing process after shaping the iron. This appears as steel products forming the basis of the steel industry at the time were commonly used as an intermediary material or currency. On the other hand, it was commonly found in all samples that the hardening was not performed after shaping or carburizing. Since the microstructure of the flat iron axes made of pure iron contained a large number of impure inclusions and the result of analyzing the components of the non-metal inclusions showed characteristics of slag which contains a mixture of glass phase and wustite, it is possible that low-temperature reduction was used in the refining process.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.659-667
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• 2000

Quality attributes of fresh-cut green onion(Allium fistulosum L.) as affected by rinsing and packaging were investigated in terms of flesh weight, color, viable cell counts, sensory properties during storage at $10^{\circ}C$. Fresh green onions were trimmed, cut, and rinsed with cold water(approximately $5^{\circ}C$) as well as chlorine solution(100 mg/L) and then packaged in low density polyethylene film pouches of $63\;{\mu}m$ thickness. Rinsing treatments with cold water or chlorine solution did not significantly influence changes in microbial populations but sensory characteristics, resulting in cut green onions of better visual quality as compared to the control without rinsing. Fresh-cut green onions were also rinsed with cold water and packaged in sealed bags of low density polyethylene films with different thickness(22, 36, $63\;{\mu}m$), and stored at $10^{\circ}C$ for 18 days. Thickness of polyethylene film was a significant factor for microorganisms populations and sensory attributes. Mesophilic aerobic bacterial count after 13 days for the control, packed in punched film bags, was $3.07{\times}10^6}$ CFU/g, while those for samples in hermetically sealed bags ranged only $1.74{\sim}2.02{\times}10^5}$ CFU/g. Gas composition within the sealed packages changed from normal air to about $1.3{\sim}5.4%\;O_2$ and $4.0{\sim}8.0%\;CO_2$ after 13 days of storage. Particularly, the visual sensory quality of cut green onion samples was retained better in polyethylene film bags of $63\;{\mu}m$ thickness(gas transmission rate: 600 $O_2\;mL/day{\cdot}m^2{\cdot}atm;\;2,500\;CO_2\;mL/day{\cdot}m^2{\cdot}atm$) than in the others.

• Journal of agricultural medicine and community health
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• v.28 no.1
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• pp.79-92
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• 2003

Objectives: To investigate the reinfection rate of Helicobacter pylori and the factors related to reinfection of H. pylori, 86 persons were examined in April 2000 after 1 year follow-up period and 77 persons were examined in October 2001 after two and a half-year follow-up period in Gyeongju-si, Gyeongsangbuk-do, Korea. Methods: The subjects were confirmed as H. pylori negative by urea breath test(UBT), and asked to answer the questionnaire regarding demographic characteristics, dyspepsia symptoms, health-related behaviors and family history. Results: The reinfection rate on the first year of the eradication of H. pylori was 15.6%, when the 77 subjects have finished follow-up observation for one year. In the urea breath test performed after two and a half year, 13 out of 77 were positive, with the reinfection rate of 16.9%. Age, sex, socio-economical status, educational level and family history were not associated with the reinfection, while there was significant association between the reinfection and postprandial fullness and epigastric bloating in subjective dyspepsia that the subjects who were determined to be negative in the urea breath test for the following year. The treatment compliance and drinking were significant variables in univariate analysis. Meanwhile, the cases in which the dyspepsia symptom scores for the recent year were 2 to 3 points served as the only statistically significant variable in multiple logistic regression analysis, with the odds ratio of 4.5. The cases in which salt intake during meals was exceeded were 8.7 in the odds ratio, but statistically insignificant. Conclusions: Conclusively, the first-year reinfection rate was 15.6%, and the second-year reinfection rate was 16.9%. Thecomplaints of subjective dyspeptic symptoms and the treatment compliance, as the basis for predicting the H. pylori reinfection in communities, can be used as the basis to screen the subjects for follow-up examination to find out H. pylori infection.

• Journal of Chest Surgery
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• v.31 no.10
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• pp.982-987
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• 1998

Background: Surgical resection is the standad therapy for the stage I lung cancer. We analysed the risk facturs of stage I lung cancer patent and tryed to establish more effective and aggressive treatment modality. Materials and methods: A detailed analysis was undertaken to evaluate the surgical results and to define the risk factors associated with the recurrence and the survival time in 146 consecutive patients with stage I lung cancer who were diagnosed, and resected at Yonsei Medical Center from January 1990 to December 1996. Results: There were 115 males and 31 females. Their ages ranged from 27 to 79 years(mean age:58.9$\pm$9.3 years). The histologic types were squamous carcinoma in 72 cases(49.3%) and adenocarcinoma in 45 cases(30.8%). A pulmonary resection and mediastinal lymph node dissection were done in all cases. A lobectomy was performed in 96 cases(65.7%) and a pneumonectomy in 48 cases(32.9%). There were 5 operative mortalities(3.4%) and complications occured in 24 cases(16.5%). The overall 5-year survival was 64.1%, and survival time did not depend on the type of operation or histologic type. Significant predictors of decreased survival were visceral pleural invasion(p=0.0079), T2 lesion(p=0.0462), and tumor size($\geq$5 cm) in adenocarcinoma(p=0.0472). The overall incidence of recurrence was 33.3%(47 cases; local or regional 6.4%, distant 26.9%). Almost all recurrences(44cases) occurred in T2 lesions. The distant organs that failed were the contralateral lung in 13 patients, the brain in 12, the bone in 10, and other organs in 3. Conclusions: even in stage I lung cancer, we suggest that postoperative adjuvant therapy is recommended in patients with poor prognostic factors such as visceral pleural invasion, T2 lesions, and a tumor size($\geq$5 cm) in the adenocarcinoma.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.255-261
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• 2002

The purpose of this study was to compare the microleakage pattern of flowable composite resin to sealant, composite resin used in preventive resin restoration and glass ionomer cement used as liner. 120 extracted sound human molars were divided into 6 groups : group 1 and 2:sealant ; group 3 and 4:preventive resin restoration ; group 5 and 6:sandwich technique restoration. For the experimental groups(group 2, 4 and 6), flowable composite resin(Tetric flow) was used. For the control group, Concise was used as sealant material(group 1), Z-100 with Concise were used as preventive resin restoration(group 3), and Vitrebond was used as cavity liner(group 5). All the restorations were thermocycled and the degree of dye penetration was evaluated with stereomicroscope. The microleakage of each group was measured and statistically analyzed. The results of the present study were as follows : 1. In group 1 and 2, there was no statistically significant difference in microleakage between Concise and Tetric flow(p>0.05). 2. In groups of preventive resin restorations, there was no statistically significant difference in microleakage between Z-100 with Concise and Tetric flow(p>0.05). 3. The microleakage of Vitrebond and Tetric flow used as liner showed no statistically significant difference(p>0.05).