• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.169-174
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• 2003

Design of a rational earth volume conversion coefficient is required as the earth volume conversion coefficient may give great influence on construction work volume and construction costs in the civil engineering works where large-scaled earth volume is excavated. However, there are a great deal of difficulties in the calculation of the exact spoil surface earth and Insufficient earth volume by adopting the figures presented on the generally used design specifications which are not the results obtained from the selection tests in calculating the earth volume conversion coefficient. In this connection, it would be desirable to calculate the earth volume conversion coefficient by carrying out large-scaled site test adequate for the relevant environment. In consequence, this study aims at calculating the exact earth volume conversion coefficient of cutting and banking areas of weathering rocks in large-scaled construction sites where land is being developed into home lots. For this, we have excavated the respective 20 sites of the cutting and banking areas in the said site and then calculated the volume after the excavation. As a result, the relative exactness degree of the crossing was calculated at 0.5% in average. The relative exactness degree of 0.5% in the volume may be judged as an exact measurement as it corresponds to 0.17% of the relative exactness degree in the length measurement. We have calculated the exact earth volume conversion coefficient by the use of function ratio as per the wet unit weight and the indoor soil quality test as per volume calculated. And then we have found out minor differences as a result of the comparison and analysis with the earth volume conversion coefficient determined by the dry unit weight test as per sand replacement method. This may be judged as a rational design method for the calculation of earth volume conversion coefficient, as well as high reliability of site test as a precision photogrammetry is adopted for volume measurement of the irregular excavating areas.

• Journal of Chest Surgery
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• v.50 no.5
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• pp.355-362
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• 2017

Background: Off-pump coronary artery bypass grafting (OPCABG) procedures can avoid the complications of an on-pump bypass. However, some cases unexpectedly require conversion to cardiopulmonary bypass during OPCABG. The risk factors associated with a sudden need for cardiopulmonary bypass were analyzed. Methods: This retrospective study included 283 subjects scheduled for OPCABG from 2001 to 2010. These were divided into an OPCABG group and an on-pump conversion group. Preoperative, operative, and postoperative variables were compared between the 2 groups. Results: Of the 283 patients scheduled for OPCABG, 47 (16%) were switched to on-pump coronary artery bypass grafting (CABG). The mortality of the both the OPCABG and on-pump conversion groups was not significantly different. The major risk factors for conversion to on-pump CABG were congestive heart failure (CHF) (odds ratio [OR], 3.5; p=0.029), ejection fraction (EF) <35% (OR, 4.4; p=0.012), and preoperative beta-blocker (BB) administration (OR, 0.3; p=0.007). The use of intraoperative (p=0.007) and postoperative (p=0.021) inotropics was significantly higher in the conversion group. The amount of postoperative drainage (p<0.001) and transfusion (p<0.001) also was significantly higher in the conversion group. There were no significant differences in stroke or cardiovascular complications between the groups over the course of short-term and long-term follow-up. Conclusion: Patients who undergo OPCABG and have CHF or a lower EF (<35%) are more likely to undergo on-pump conversion, while preoperative BB administration could help prevent conversions from OPCABG to on-pump CABG.

• Journal of Korea Multimedia Society
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• v.10 no.1
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• pp.49-57
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• 2007

Recently, CMOS RF integration has been widely explored in the wireless communication area to save cost, power, and chip area. The direct conversion architecture, rather than a more conventional super-het-erodyne, has been an attractive choice for single-chip integration because of its many advantages. However, the direct conversion architecture has several fundamental problems to solve in achieving performance comparable to a super-heterodyne counterpart. In this paper, we describe a programmable filter for mobile communication terminals using a direct conversion architecture. The proposed filter can be implemented with the active-RC filter and programmed to meet the requirements of different communication standards, including GSM, DECT and WCDMA. The filter can be tuned to select a detail frequency by changing the gate voltage of the MOS resistors. The gain of the proposed architecture can be programmed from 27dB to 72dB using the filter gain and VGA in 3dB steps.

• Journal of Korean Library and Information Science Society
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• v.45 no.3
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• pp.93-117
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• 2014

The goal of this study is to seek for the method of effective DB conversion and related system development for the integrated KORMARC Format on the basis of the case of Sogang University Library. Since the integrated KORMARC bibliographic format was established, libraries have been converting bibliographic DB according to the new format. Loyola Library of Sogang University internally proceeded DB conversion using bibliographic DB convertor, which was developed and customized with a system vendor for Sogang University Library. The internal conversion enabled to correct or supplement bibliographic data errors. Besides, it enhanced stability of conversion and shortened the project time by adopting sampling conversion method. It was effective to reduce the additional work for DB quality maintenance, so this kind of conversion is recommendable to the library that has limited manpower for manual data correction.

• Journal of Industrial Convergence
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• v.18 no.5
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• pp.1-13
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• 2020

The purpose of this study is to find out how much the investment effect of convertible bond(CB) is from the perspective of investors and to present efficient investment plans to investors. The research method is to investigate the coupon interest rate, maturity interest rate, conversion price, etc. for CBs. As a result of the study, it was analyzed that CB's investment efficiency was low because the conversion price excess days ratio was only about 1/4 of the conversion date. The conversion day yield was -6.3% and the maturity day yield was -5.2% on average. It was analyzed that the number of stocks with negative conversion day yield was 2.4 times higher than the number of positive stocks and 3.7 times higher than the number of positive stocks with a maturity day yield, so the expected return on equity conversion of CB was low.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.533-538
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• 2014

Today, silicon and epoxy resin are used as materials of conversion lenses for white LEDs on the basis of their good bonding and transparency in LED packages. But these materials give rise to long-term performance problems such as reaction with water, yellowing transition, and shrinkage by heat. These problems are major factors underlying performance deterioration of LEDs. In this study, in order to address these problems, we fabricated a conversion lenses using glass, which has good chemical durability and is stable to heat. The fabricated conversion lenses were applied to a remote phosphor type. In this experiment, the conversion lens for white LED was coated on a glass substrate by a screen printing method using paste. The thickness of the coated conversion lens was controlled during 2 or 3 iterations of coating. The conversion lens fabricated under high heat treatment temperature and with a thin coating showed higher luminance efficiency and CCT closer to white light than fabricated lenses under low heat treatment temperature or a thick coating. The conversion lens with $32{\mu}m$ coating thickness showed the best optical properties: the measured values of the CCT, CRI, and luminance efficiency were 4468 K, 68, and 142.22 lm/w in 20 wt% glass frit, 80 wt% phosphor with sintering at $800^{\circ}C$.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.653-657
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• 2011

Conversion characteristics of $CH_4$ and $CO_2$ was studied using an atmospheric pressure plasma for the preparation of synthesis gas composed of $H_2$ and CO. The effects of delivered power, total gas flow rate, and gas residence time in the reactor on the conversion of $CH_4$ and $CO_2$ were evaluated in a plasma reactor with the type of dielectric barrier discharge. The increase of reactor temperature did not affect on the increase of conversion if the temperature does not reach to the appropriate level. The conversion of $CH_4$ and $CO_2$ largely increased with increasing the delivered power. As the $CH_4/CO_2$ ratio increased, the $CH_4$ conversion decreased, whereas the $CO_2$ conversion increased. Generally, the $CH_4$ convesion was higher than the $CO_2$ conversion through the variation of the process parameters.

• Journal of Chest Surgery
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• v.57 no.3
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• pp.302-311
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• 2024

Background: Unexpected conversion to thoracotomy during planned video-assisted thoracoscopic surgery (VATS) can lead to poor outcomes and comparatively high morbidity. This study was conducted to assess preoperative risk factors associated with unexpected thoracotomy conversion and to develop a risk scoring model for preoperative use, aimed at identifying patients with an elevated risk of conversion. Methods: A retrospective analysis was conducted of 1,506 patients who underwent surgical resection for non-small cell lung cancer. To evaluate the risk factors, univariate analysis and logistic regression were performed. A risk scoring model was established to predict unexpected thoracotomy conversion during VATS of the lung, based on preoperative factors. To validate the model, an additional cohort of 878 patients was analyzed. Results: Among the potentially significant clinical variables, male sex, previous ipsilateral lung surgery, preoperative detection of calcified lymph nodes, and clinical T stage were identified as independent risk factors for unplanned conversion to thoracotomy. A 6-point risk scoring model was developed to predict conversion based on the assessed risk, with patients categorized into 4 groups. The results indicated an area under the receiver operating characteristic curve of 0.747, with a sensitivity of 80.5%, specificity of 56.4%, positive predictive value of 1.8%, and negative predictive value of 91.0%. When applied to the validation cohort, the model exhibited good predictive accuracy. Conclusion: We successfully developed and validated a risk scoring model for preoperative use that can predict the likelihood of unplanned conversion to thoracotomy during VATS of the lung.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.123-130
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• 2005

In this study, we evaluated the CH4 and CO conversion efficiencies over the oxidation catalysts for natural gas vehicle with lean-burn system. On the fresh catalyst, the conversion efficiency was increased when the loading of precious metal was increased. On the aged catalyst, the conversion efficiency was decreased as increasing the excess air ratio. We could confirm the measuring conversion efficiency of the unsteady state with the FTIR and that of steady state with the GC The temperature increasing ratio of unsteady state is acceptable from 3$^{\circ}C$/min. to 15$^{\circ}C$/min. for the evaluation of catalyst conversion performance , which has within the 4$\%$ of the difference of conversion efficiency. We observed a physical behavior of the thermal aged catalyst's surface using TEM and BET device. It was found that the precious metal was grown to the micro-scopic size by thermal aging process.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.80-86
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• 2005

In this study, we investigated the characteristics of the conversion efficiency and the effect of ageing Diesel Oxidation Catalyst (DOC). The DOC was composed of Warm-up Catalytic Converter (WCC) and Underbody Catalytic Converter (UCC). As the result, the conversion efficiency of THC was 10$\~$50$\%$ on WCC and 30$\~$40$\%$ on UCC .The conversion efficiency of CO was 80$\~$90$\%$ on WCC and remained 10$\~$20$\%$ of CO was purified on UCC. The WCC shows high conversion efficiency on CO. After 20 hours aging process of engine bench, conversion efficiencies of THC and CO were improved a little, because it was activated catalyst surface by 20 hours aging. In case of 80 hours aging, the conversion efficiencies of THC and CO were decreased on WCC. However, the UCC was not affected by aging process .