• Education of Primary School Mathematics
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• v.15 no.2
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• pp.91-106
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• 2012

This study reports pre-service teachers' problem solving process on the problem-based learning(PBL) employed in an elementary mathematics method course. The subjects were 6 pre-service teachers(students). The data were collected from classroom observation. The research results were described by problem solving stages. In understanding the problem stage, students identified what problem stand for and made a problem solving planned sheet. In curriculum investigation stage, students went through investigation and re-investigation process for solving the task. In problem solving stage, students selected the best strategy for solving the task and presented and shared about problem solving results.

• Journal of Chest Surgery
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• v.35 no.5
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• pp.392-396
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• 2002

Background: Video-thoracoscopy is known to be an useful method to provide accurate pre-resectional staging in patients with lung cancer in addition to the conventional radiologic studies and mediastinoscopy, for the pleural cavity is inspected directly and biopsy specimens call be obtained. This study is undertaken to evaluate how video-thoracoscopy can be used in deciding pre-resectional stage Material and Method: Video-thoracoscopy was performed in patients with lung cancer who were scheduled for surgical resection based on the radiologic staging and mediastinoscopic biopsy. 37 patients were included in this study. Pre-thoracoscopically 18 cases were in TNM stage 1, 7 in stage 2, and 12 in stage 3. Result: In 15 of 37 cases, video-thoracoscopy could not be performed effectively due to heavy adhesions in the pleural cavity, diaphragmatic and chest wall invasion of tumor and bulky tumor mass es. Mediastinal lymph nodes were positive postresectionally in 6 of these 15 cases. In 22 cases, video-thoracoscopy was performed as usual. Positive mediastinal lymph nodes were identified in 2 cases and exploratory thoracotomy was prevented. Surgical resection were carried out in remaining 20 cases and 5 cases among them had positive mediastinal lymph nodes. Conclusion: We believe that it is difficult to perform pre-thoracotorny video-thoracoscopy for all lung cancer patients for there were many cases that thoracoscory could not be undertaken doe to heavy adhesions in the pleural cavity, tumor involvement of the chest wall and/or diaphragm and bulky tumor mass. However we think it is helpful in preventing unnecessary exploratory thoracotomy for some patients with lung cancer whom pre-thoracotomy video-thoracoscopy was carried out.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.203-207
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• 2008

The production process of the 3D-animation roughly consists of the pre-production, the main-production and the post-production. The pre-production, which is not only the outset of whole procedure among them but also the process to predict and design overall plan collectively is the most important step. A much more specific and perfect pre-production structure is needed to produce a high quality 3D-animation. Moreover, the standard 3D efficient lighting model is gathering strength as 2D and 3D artworks which are completed in this step maintain colors and looks in the main as well as post-production consistently. This study will make up for the weak points and help both to predict the color range of the overall 3D-animation product and to promote the application range of the 3D lighting system on the pre-production stage by developing the standard 3D lighting model applicable on the early step and calculating its lighting parameter properties.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.517-520
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• 2008

The city refreshing development projects in the domestic recently have been performed under leading of public institution laying stress on new city and existing urban district. These development projects are still staying in safety control level despite risk factor management at preliminary estimation stage has been more important factor to success and add value creation. Understanding inaccurately about various risk analysis techniques that can analyze risk factors and the insufficient application of step that can analysis technique s could make projects more difficult. Therefore, this research suggests the more effective methods for risk analysis that can control the risks in the pre-project evaluation stage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.295-300
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• 2005

In this paper we have designed a two-stage Class I power amplifier operated at 2.4CHz for Class-1 Bluetooth application. The power amplifier employs class-I topology to exploit its soft-switching property for high efficiency. The latch-structured pre-amplifier with amplifiers makes its output signal as sharp as possible for soft switching of the next power amplifier. It improves the overall efficiency of the proposed power amplifier. It shows 65.8$\%$ PAE, 20dB power gain and 20dBm output power.

• Advances in environmental research
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• v.5 no.4
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• pp.251-262
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• 2016

The biodegradability and decomposition efficiencies increase with the pre-treatment of sludge in a digestion process. In this study, the feasibility of ultrasound coupled with potassium permanganate oxidation as a disintegration method and digestibility of aerobic reactor fed with disintegrated sludge with ultrasound coupled potassium permanganate were investigated. The first stage of the study focused on determining the optimum condition for ultrasonic pre-treatment for achieving better destruction efficiency of sludge. The second part of the study, the aerobic digestibility of sludge disintegrated with ultrasound and potassium permanganate oxidation alone and combined were examined comparatively. The results showed that when 20 min of ultrasonic pre-treatment applied, the specific energy output was 49384 kJ/kgTS with disintegration degree of 58.84%. During the operation of aerobic digester, VS/TS ratios of digesters fed with disintegrated sludge decreased indicating that disintegration methods could obviously enhance aerobic digestion performance. The highest reduction in volatile solids was 75% in the digester fed with ultrasound+potassium permanganate disintegrated sludge at the end of the operation compared to digester fed with raw sludge. Total Nitrogen (TN) and Total Phosphorus (TP) levels in sludge supernatant increased with this combined method significantly. Besides, it promoted the production of ${\bullet}OH$, thus enhancing the release of Carbon (C), Nitrogen (N) and Phosphorus (P) from the sludge. Disintegration with all methods used in this study could not improve Capillary Suction Time (CST) reduction in disintegrated digesters during the operation. The results demonstrated that the combined ultrasound treatment and potassium permanganate oxidation method improves the biodegradability compared to control reactor or their single application.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.601-614
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• 2018

Chitosan with a natural antimicrobial property has been introduced to protect horticultural crops from diseases as an environmentally friendly method. The purpose of this study was to investigate the effects of the pre-harvest application of chitosan on growth and quality during the late stage of fruit development and on the simulated marketing of the peach fruit (Prunus persica L.). The application of chitosan with calcium chloride ($100mg{\cdot}L^{-1}$) three times at one week intervals 4 weeks before the harvest significantly increased the fruit weight, changed the fruit shape, and reduced the fruit length/diameter ratio giving the peach fruits a round oblate shape. The calcium treatment contributed to enhancing or maintaining the storage potential by increasing the flesh firmness. However, at higher concentrations of $CaCl_2$, i.e., > $600mg{\cdot}L^{-1}$, the positive effects of the chitosan application were offset, and fruit growth was not affected by calcium alone. The application of the chitosan/calcium mixture delayed fruit softening; however, this effect was shortened when the storage temperature was $20^{\circ}C$ rather than $15^{\circ}C$. The internal quality of the fruit was profoundly affected by the concentration of calcium added to the chitosan, and delayed fruit maturation was observed at a higher concentration of calcium. The pre-harvest application of chitosan with calcium contributes to the enhancement of food safety by inhibiting the occurrence of diseases during postharvest handling. Considering the above results, chitosan has the potential to improve both the yield of peach fruits and their storability. Because chitosan can enhance the freshness and shelf-life of fresh produce, it is necessary to examine its effects on other horticultural crops.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.7 no.2
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• pp.164-176
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• 2000

Purpose : This study was done to identify the factors of decisional balance for smoking cessation among middle aged men in Korea. This was composed of a set of variables at the level of decision making when middle aged men decide to stop smoking. It was used to classify and identify the characteristics of the stages of change for smoking cessation to which the middle aged men belong, and was used to identify the variables of decisional balance which influenced the stages of change for smoking cessation in middle aged men. Methods : A convenience sample of 169 men who had smoked and were smoking, were between age 30 and 60 and lived in Seoul(mean age=44), were selected from the community. The data was collected from December 10, 1999 to February 28, 2000. The research instrument was the Decisional Balance Measure for Smoking Cessation (Velicer et al., 1985). and Stage of Change Measure(DiClemente et al., 1991). The data were analyzed using the SAS Program. Results : 1. According to stage of change measure, the 169 subjects were distributed in each stage of change for smoking cessation: in the pre-contemplation stage 63 subjects(32.7%), contemplation stage 60 subjects (35.5%), preparation stage 17 subjects(10.1%), and maintenance stage 29 subjects(17.2%). 2. Factor analysis identified 4 factors of decisional balance as appropriate factors for smoking cessation of middle aged men. There were named by the researchers; 1)'Perceived Burden to Self', 2)'Perceived Benefit to Others' 3)'Perceived Approval to Others', and 4)'Perceived Disapproval to Self'. 3. Analysis of variance showed that the three components, 1)'Perceived Burden to Self(F=8.50, P=.0001)', 2)'Perceived Benefit to Others(F=3.19, P=.025)' and 3)'Perceived DisApproval to Self(F=2.87, P=.038)were significantly associated with stage of change. 4. Through discriminant analysis, it was found that 'Perceived Burden to self' was the most influential variable in discriminating the four stages of change(pre-contemplation, contemplation, preparation, and maintenance). Conclusion : The results are consistent with the application of the Transtheoretical model, which has been used to understand how people change health behavior. Even though this study is a cross-sectional, not a longitudinal study, the findings of this study give useful information for smoking cessation intervention for the middle aged men.

• Membrane Journal
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• v.20 no.2
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• pp.97-105
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• 2010

This study was to evaluate the performance of the Double stage Pore controllable fiber (DP) filter system as the pre-treatment of the RO membrane. The evaluation for the pre-treatment filter was performed through the indirect method, SDI (Silt Density Index) measurement of the filtrate. This study was done during Jan. 3 of 2009 to Dec. 3 of 2009 at OO Water Treatment Plant that was suppling industrial water to plants, and the raw water was contaminated lake water and it was fed to the system after clarification with coagulation. The average turbidity of the feed water and that of the filtrate was 0.79 NTU (0.28~4.01 NTU), and 0.16 NTU (0.04~0.50) respectively. And so the average turbidity removal efficiency was 77%. The filtrate flow rate and the backwash water flow rate was about 230 $m^3$/day and about 8.7 $m^3$/day respectively, and so the backwash rate was 3.8%. The data for some samples were obtained after a few days storage, and it caused the higher turbidity and SDI15 as the storage time was increased. But average SDI value of the filtrate was 3.6 (2.26~5.00) which was lower than minimum value required by the RO membrane manufacturer as the RO feed water to guarantee the life time of the RO membrane. So, the DP filter system was enough for the application as the pre-treatment of the RO membrane.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.2
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• pp.115-122
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• 2012

Sound packages and damping materials have been widely applied on the floor to decrease the interior noise of a vehicle. Based on the previous researches on the low-noise vehicles, weight optimization through minimization of damping material usage is required while decreasing mid and high frequency range noise by application of sound packages. This paper describes the analysis process of robust design of vehicle body structure before applying damping materials and focuses on the analysis and test process of the location optimization at the stage of damping material application. A vibration experiment for the analysis of floor panel velocity with respect to the excitation of suspension attachment parts at the underfloor of a vehicle is performed. And through the improvement correlation between FEA and TEST, a design guide to optimize damping materials application in the early design stage is proposed. A research on vibration damping steel sheets and liquid acoustic spray on deadener(LASD) is performed to minimize manufacturing time and to minimize the space for pre-existing asphalt damping materials. As results of this study, panel stiffness is achieved through curved surface panel and bead optimization. And test baseline of optimum design is suggested through damping material optimization. And finally, through re-establishing the analysis process for vibration reduction of vehicle floors and lightweight design of damping materials, it is possible to design damping materials efficiently in the preceding stage of design.