• 한국전산유체공학회지
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• 제7권3호
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• pp.17-26
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• 2002

Computational fluid dynamic(CFD) analysis has been frequently applied to the waste incinerators to understand the flow performance for various design and operating parameters. Since the computational modeling inevitably requires many simplifications and complicated sub-models, validity of the results should be carefully evaluated. In this study, major computational modeling and procedure of usual simulation methods for the grate-type waste incinerators were assessed. Usual simulation method does not explicitly incorporate the waste combustion, simply by assuming the combustion gas properties from the waste bed which is treated as an inlet plane. However, effect of this arbitrary assumption on the overall flow pattern is not significant, since the flow pattern is dominated by strong pattern of jet flows of the secondary air. Thus, this method is valid in understanding the effect of flow-related parameters. In analyzing the results, deriving conclusive information directly from temperature and chemical species concentration should be avoided, since the model prediction for the gaseous reaction and the radiation reveals significant discrepancies against the actual phenomena. Use of quantitative measures such as residence time is very efficient in evaluating the flow performance.

• 한국연소학회지
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• 제4권1호
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• pp.1-15
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• 1999

In order to analyze the sensitivity on the pulverized coal flames of the several variables, a numerical study was conducted at the gasification process. Eulerian approach is used for the gas phase, whereas lagrangian approach is used for the solid phase. Turbulence is modeled using the standard $k-{\varepsilon}$ model. The turbulent combustion incorporates eddy dissipation model. The radiation was solved using a Monte-Carlo method. One-step two-reaction model was employed for the devolatilization of Kideco coal. In pulverized flame of long liftoff height, the initial turbulent intensity seriously affects the position of flame front. The radiation heat transfer and wall heat loss ratio distort the temperature distributions along the reactor wall, but do not influence the reactor performance such as coal conversion, residence time and flame front position. The primary/secondary momentum ratio affects the position of flame front, but the coal burnout is only slightly influenced. The momentum ratio is a variable only associated with the flame stabilization such as flame front position. The addition of steam in the reactor has a detrimental effect on all the aspects, particularly reactor temperature and coal burnout.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.275-279
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• 2011

Sterilization of Escherichia coli (E. coli) is examined using a unique pulsed ultra-violet (UV) elliptical reactor based on Nd:YAG laser resonator, UV radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV contained. Sterilization method by using the UV light is fast, environment-friendly and it does not cause secondary pollution. A Nd:YAG laser resonator having elliptical shape has advantage of concentrating the radiation of the UV light at two foci as the quart sleeve filled with E. coli. The primary objective of this research is to determine the important parameters such as pulse per second (pps), the applied voltage for sterilizing E. coli by using an UV elliptical reactor. From the experiment result, the sterilization effect of UV elliptical reactor is better than that of UV cylindrical reactor, and it can be 99.9% of sterilization at 800V regardless of the pps within 10 minutes.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권2호
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• pp.77-82
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• 2005

We compare electrical and optical properties of organic light emitting diodes (OLEDs) using rhodium-oxide-coated indium-tin-oxide ($O_2$-Rh/ITO) to that using $O_2$-plasma-treated ITO (ITO) anodes. The turn-on voltage decreased from 7 V to 5 V and luminance value increased when the $O_2$ plasma treated Rh layer was deposited on ITO. Synchrotron radiation photoelectron spectroscopy results showed the dipole energies of both ITO and $O_2$-Rh/ITO were same with each other, - 0.3 eV, meaning the formation of same amount of interface dipole. The secondary electron emission spectra revealed that the work function of $O_2$-Rh/ITO is higher hy 0.2 eV than that of ITO, resulting in the decrease of the tum-on voltage via reduction ofhole injection barrier.

• Archives of Plastic Surgery
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• 제34권3호
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• pp.388-391
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• 2007

Purpose: Malignant fibrous histiocytoma (MFH) is mainly a soft tissue sarcoma containing fibroblast-like cells and histiocytic cells. MFH in bone accounts for 5% of all malignant bone tumors. MFH of the maxilla is extremely rare and difficult to diagnose due to its scarcity. Treatment mainstay is a complete surgical excision. Radiation therapy is also available when surgery alone is incomplete. Prognosis is not clear but can be devastating. Authors report one case of MFH developed in the maxilla. Methods: A 24-year-old man firstly diagnosed as fibrous dysplasia based on CT findings. Considering facial contour, partial excision was done. But pathology report confirmed malignant fibrous histiocytoma and secondary wide excision was done including zygoma and grossly all affected area. After surgery, radiation therapy was continued. Results: There are no evidence of tumor recurrence after clinical and radiological treatment. Conclusion: MFH of maxilla is very rare and this can leads to misdiagnosis in many clinicians. Surgeon should differentiate this disease from fibrous dysplasia and pathology and MRI are accurate methods for diagnosis of MFH.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.90-98
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• 2011

Noises from diesel engine are the major issues for noise pollution as well as affect customers' purchasing needs to vehicles powered by diesel engine. This study investigates to screen-out main factors that contribute to noises from diesel engine using VGT 2000cc engine developed recently. Changes of fuel temperature, intake temperature and the presence of three way catalyst don't affect the 'Engine Radiation Noise' and the solely three way catalyst influence on the 'Tail Pipe Noise'. Especially, there are no effects of the presence of three way catalyst on torque, which is main subject that should be considered in secondary study.

• 대한방사선치료학회지
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• 제7권1호
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• pp.45-53
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• 1995

목적 : 뇌정위 방사선수술은 AVM(ateriovenous malformation)이나 작은 크기의 종양에 1회에 고선량의 방사선을 조사하는 기술이다. 선형가속기를 이용한 방사선 수술을 하기 위하여 최근 본원에 설치한 Philips SL 75-5 선형가속기와 isocentric sub system(ISS)에 의한 뇌정위 방사선 수술에 있어서 표적의 위치선정과, gantry와 couch의 회전시 기하학적 오차가 중요시 되는데 isocentric sub system의 오차를 분석 하였다. 대상 및 방법 : 방사선원으로는 Philips SL 75-5 선형가속기의 5MV 광자선을 사용하였고, 원형의 작은 광자선속을 위하여 isocenter에서의 직경이 26mm인 secondary cone을 gimbal baaring에 삽입하여 사용하였다. 표적의 크기와 좌표를 정하기 위하여 CT나 angio localizer를 이용하고, 표적좌표 선정을 위하여 BRW phantom base와 target pointer를 이용하여 임의의 BRW-coordinator를 바꾸어 가면서 gantry angle와 ISS head 각도를 임의로 바꾸어 가면서 film에 방사선을 조사하였다. 흑화된 film을 view box 위에 놓고 광학판독기구로 film 가장자리의 오차를 scale 확대경으로 측정하여 오차를 분석하였다. 결과 : 표적좌표 선정의 정확도를 확인하기 위하여 임의의 표적좌표에 gantry의 10개각도 ISShead의 10개각도에서 각각 광자선을 조사시켜 film을 이용하여 오차를 측정한 결과 collimator cone의 직경이 26mm일때 전체 평균오차가 0.219+-0.03mm이었다. 결론 : Isocentric sub system은 gantry head와 ISS arm 사이에 gimbal bearing이 있어서 이 부위를 flexible하게 연결함으로 gantry의 회전에 무관하게 정확한 isocenter를 유지시켜 주고 ISS head는 couch와 독립되어 움직이므로 isocentric sub system isocenter의 오차를 최대한 줄일수 있음을 알았다.

• Journal of Plant Biology
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• 제25권3호
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• pp.123-133
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• 1982

The tropic structure and the function of a small pone ecosystem under the tree stand were studied in terms of energy flow. About 28% of total solar radiation was intercepted by the tree canopy over the pond. Primary producers converted 1.1%(3,382 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$) of solar radiation (320,000 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$) into gross primary production. The amount of energy availble to the pond snail was 1,683 kcal.m-2.y-1 of the net production by primary producers and 1,033 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$ of the litter fallen into the pond. The amount of gross secondary production by the pond snail was 245 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$. Judging from these, supply of both net primary production and the litter was indispensable for the maintenance of the pond ecosystem. The total amont of energy as gross primary production plus litter was 4,415 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$(100%). Since the total respiration loss was calculated to be 1,917 kcal$\cdot$$m^{-2}$$\cdot$$y^{-1}$(43.4%), the rate of energy accumulation in the pond estimated to 56.6%.

• 한국전기전자재료학회논문지
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• 제23권7호
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• pp.550-553
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• 2010

The enhancement of quantum efficiency using a surface modified Ag anode in top-emitting organic light emitting diodes (TEOLEDs) is reported. The operation voltage at the current density of $1\;mA/cm^2$ of TEOLEDs decreased from 9.3 V to 4.3 V as the surface of anode coated with $CuO_x$ layer. The work function of these structures were quantitatively determined using synchrotron radiation photoemission spectroscopy. Secondary electron emission spectra revealed that the work function of the Ag/$CuO_x$ structure is higher by 0.6 eV than that of Ag. Thus, the $CuO_x$ structure acts as a role in reducing the hole injection barrier by about 0.6 eV, resulting in a decrease of the turn-on voltage of top-emitting light emitting diodes.

• Asian Pacific Journal of Cancer Prevention
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• 제17권2호
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• pp.749-754
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• 2016

Extended follow-up of Hodgkin lymphoma (HL) survivors indicates that these patients are at high risk of secondary malignant neoplasms (SMNs) contributing to increased morbidity and mortality. This study examined the characteristics of HL survivors who developed SMNs with the aim to report any correlation with radiotherapy (RT) dose. In this retrospective multi-center cohort study of HL patients treated between 1990 and 2011 at three major teaching hospitals in Lebanon, classification was into two groups including those treated with combined modality (RT and chemotherapy-CHT) and those treated with CHT alone. Approval from the University Institutional Review Board (IRB) was obtained. Of the 112 patients evaluated, 52.7% (59) received the combined modality while 47.3% (53) received CHT alone. There were 6 cases of SMNs in the combined modality cohort and 5 cases in the CHT cohort. The mean RT dose in the combined modality cohort was 34.5 Gray (Gy) ($SD{\pm}5.3$). A statistically significant increase (1.5 fold) in the risk of developing SMNs was observed among patients who received a dose higher than 41 Gy compared to a dose between 20 to 30 Gy (OR= 1.5; 95% confidence interval= 0.674 to 3.339, p=0.012). The risk of SMNs was not significantly higher among patients who received extended field compared to involved field RT (p=0.964). This study showed that the risk of developing SMNs is higher among patients treated with RT dose greater than 31 Gy, independent of the RT type used.