• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.887-892
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• 2019

In this study, after 20nm-thick $SiO_2$ thin film was deposited by PECVD method on the PES substrate, which is known to have the highest heat resistance among plastic substrates, as a buffer layer, ITZO thin films were deposited by RF magnetron sputtering method to investigate the electrical and optical properties according to the working pressure. The ITZO thin film deposited at the working pressure of 3mTorr showed the best electrical properties with a resistivity of $8.02{\times}10^{-4}{\Omega}-cm$ and a sheet resistance of $50.13{\Omega}/sq.$. The average transmittance in the visible region (400-800nm) of all ITZO films was over 80% regardless of working pressure. The Figure of merit showed the largest value of $23.90{\times}10^{-4}{\Omega}^{-1}$ in the ITZO thin film deposited at 3mTorr. This study found that ITZO thin films are very promising materials to replace ITO thin films in next-generation flexible display devices.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1186-1190
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• 2009

강수량이 예년에 비해 적은 양상은 여름강수량에 대한 부족으로 기인한다. 우리나라의 경우 장마기간의 강수와 태풍으로 인해 발생하는 강수가 전체 강수량에 많은 부분을 차지하고 있기 때문에 여름강수량이 적게 나타나게 되면 가을 가뭄 및 봄 가뭄에 대한 발생 압력도 그 만큼 커지게 되는 것이 일반적이다. 기존 연구들이 단순히 강수량을 가정하거나 시나리오를 기반으로 가뭄을 전망하는데 그치고 있으나 본 연구에서는 2009년 가뭄전망을 위해서 전지구기후모형(GCMs)의 3개월 기상예측 결과를 활용하고자 한다. 즉, APEC 기후예측 센터로부터 제공 받은 3개월 GCM Multi-Model Ensemble 예측 결과를 바탕으로 가뭄상태를 평가하였다. 따라서 본 연구의 목적은 Large-scale의 기후예측 시스템과 기상관측지점의 강수 및 온도를 연결시켜 가뭄을 전망할 수 있는 시스템을 구축하는데 있다. GCM 예측 결과를 바탕으로 2009년도 매월 강수량 및 평균 온도를 추정하여 PDSI 가뭄지수 산정에 이용하였다.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.541-546
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• 2003

Experimental vapor pressure measurements available in the literature for the inert gases have been rigorously analyzed and used to evaluate the constants A, B, C, D, and exponent of the following equation in the form of reduced vapor pressure and reduced temperature : $InP_r=A+{\frac{B}{T_r}+CInT_r+DT_n^r}$ According to varying exponent n all four constants have been obtained for the inert gases by the error analysis. This has provided us the best n and four constants for each of the inert gases ; Argon, krypton, xenon, helium, and neon. In order to obtain the calculated vapor pressure by the above equation, only the normal boiling point and the critical pressure and critical temperature are necessary to get the vapor pressure for an overall average deviation of 0.31 % for 406 experimental vapor pressure points consisting of five gases available in the literature. The average deviation for argon, krypton, and xenon is 0.24%, 0.09%, and 0.22%, respectively, for neon 1.31% and for helium 0.61%. These results are not unexpected in view of the significant quantum effects associated with helium and to a lesser degree with neon.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.33-38
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• 2013

A study was carried out on the effect of particle size (mean diameter) on magnesium dust explosion. Experimental investigations were conducted in a 20-L explosion sphere, using 10 kJ chemical ignitors. Explosion tests were performed with three different dusts having mean diameter (38, 142, $567{\mu}m$) and the dust concentrations were up to $2250g/m^3$. The lower explosion limits(LEL) of magnesium dusts were about $30g/m^3$ at $38{\mu}m$ and $40g/m^3$ at $142{\mu}m$. LEL tended to increase with particle size and this means that the explosion probability of magnesium dust decreased with increase of particle size. The maximum explosion presssure ($P_m$) and $K_{st}$ (Explosion index) decreased with the increase of particle size. For magnesium powder of $567{\mu}m$, however, the explosive properties were not observed in the 5 kJ ignition energy.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.592-600
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• 1997

Background : The level of imposed work of breathing (WOB) is important for patient-ventilator synchrony and during weaning from mechanical ventilation. Triggering methods and the sensitivity of demand system are important determining factors of the imposed WOB. Flow triggering method is available on several modern ventilator and is believed to impose less work to a patient-triggered breath than pressure triggering method. We intended to compare the level of imposed WOB on two different methods of triggering and also at different levels of sensitivities on each triggering method (0.7 L/min vs 2.0 L/min on flow triggering ; $-1\;cmH_2O$ vs $-2cm\;H_2O$ on pressure triggering). Methods : The subjects were 12 patients ($64.8{\pm}4.2\;yrs$) on mechanical ventilation and were stable in respiratory pattern on CPAP $3\;cmH_2O$. Four different triggering sensitivities were applied at random order. For determination of imposed WOB, tracheal end pressure was measured through the monitoring lumen of Hi-Lo Jet tracheal tube (Mallincrodt, New York, USA) using pneumotachograph/pressure transducer (CP-100 pulmonary monitor, Bicore, Irvine, CA, USA). Other data of respiratory mechanics were also obtained by CP-100 pulmonary monitor. Results : The imposed WOB was decreased by 37.5% during 0.7 L/min on flow triggering compared to $-2\;cmH_2O$ on pressure triggering and also decreased by 14% during $-1\;cmH_2O$ compared to $-2\;cmH_2O$ on pressure triggering (p < 0.05 in each). The PTP(Pressure Time Product) was also decreased significantly during 0.7 L/min on flow triggering and $-1\;cmH_2O$ on pressure triggering compared to $-2\;cmH_2O$ on pressure triggering (p < 0.05 in each). The proportions of imposed WOB in total WOB were ranged from 37% to 85% and no significant changes among different methods and sensitivities. The physiologic WOB showed no significant changes among different triggering methods and sensitivities. Conclusion : To reduce the imposed WOB, flow triggering with sensitivity of 0.7 L/min would be better method than pressure triggering with sensitivity of $-2\;cm\;H_2O$.

• Journal of the Korean Institute of Gas
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• v.18 no.4
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• pp.21-26
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• 2014

In this study, the explosion characteristic of aluminium powders have been investigated as a function of particle size using by a 20 L dust explosion apparatus (K$\ddot{u}$hner). The tested aluminium particle sizes were the volume mean diameter of 16, 33 and $88{\mu}m$. The lower explosion limit increases gradually with the increasing of dust particle diameter, respectively 40, 60, $125g/m^3$ in mean diameter of 16, 33 and $88{\mu}m$. Also the increase in particle size for each aluminum dusts was found to cause an decrease in explosion pressure and Kst of dust explosion index, and a increase in the lower explosion concentration. Research results may have important implications for aluminum powders utilization and safety operation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6066-6075
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• 2014

The aim of this study was to analyze the productivity changes in government-funded research institutes for Economics & Humanities and Social Sciences. From Malmquist total factor productivity index analysis, the average productivity decreased 6.5% between 2006 and 2010. Further analysis showed that technical efficiency increased 4.7% annually while the technology change rate decreased 10.8% on average. Under pressure for innovation from the outside, research institutes responded to managerial efficiency improvement, which lead to increases in technical efficiency. On the other hand, for productivity improvement of government funded research institutes, they must pursue technological advances by securing an outstanding research workforce, expanding the R&D budget, and changing the R&D method. Each institute must perceive the cause of an individual institute's productivity change, and establish strategies for increasing productivity.

• Sleep Medicine and Psychophysiology
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• v.13 no.1
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• pp.27-32
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• 2006

Objectives: Nasal continuous positive airway pressure (nCPAP) is the treatment of choice and has been shown to reduce the frequency of nocturnal respiratory events, improve sleep architecture, and decrease daytime sleepiness in patients with obstructive sleep apnea syndrome (OSAS). However, little is known about the compliance of nCPAP treatment in Korea. Our objective was to look into the nCPAP compliance and examine the factors influencing it. Methods: We reviewed the records of one hundred and twenty consecutive patients with OSAS referred for nocturnal polysomnography with nCPAP pressure titration during the period of January 1995 through April 1999 to the Seoul National University Hospital. We performed a telephone interview and obtained data from eighty-three patients. Results: In sixty patients who had accepted nCPAP treatment, twenty-six patients (43.3%) were still using nCPAP device, while thirty-four patients (56.7%) stopped using it. Fifteen patients (25%) were using nCPAP device everyday. In thirty-four patients who discontinued nCPAP use, twenty-five patients (73.5%) did within the first three months, and thirty-one (91.2%) within the first year. Significant predictor of long-term nCPAP use was the presence of subjective daytime sleepiness before nCPAP application. Conclusions: Long-term compliance with nCPAP treatment appears to be associated with the presence of subjective daytime sleepiness before nCPAP application. Long-term compliance with nCPAP may be mostly predicted from the usage pattern within the first three months of use.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.576-582
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• 2016

To cope with international regulations, such as Energy Efficiency Design Index (EEDI), Ship Energy Efficiency Management Plan (SEEMP) and so forth, and to enforce limitations on $CO_2$ emissions, green-ship technology to lower fuel consumption has been actively researched, and the development of an energy-saving device (ESD) is being pursued. In order to design an ESD for small and medium-sized domestic vessels, an analysis on flow characteristics has been performed in the present study. Through a model test and numerical analyses, the characteristics of flow around the stern bilge and bulb have been compared to improve wake quality and resistance performance. As a result of these comparisons and analyses, a vertical plate has been adopted,, as a new ESD. Design criteria for the proposed ESD are also suggested. By applying this new ESD, it is expected that the total resistance and average nominal wake can be reduced by 3.04 % and 18.8 %, respectively.

• Journal of the Korean Chemical Society
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• v.45 no.4
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• pp.293-297
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• 2001

The existing vapor pressure measurements reported in the literature for parahydrogen between the triple point and the critical point have been employed to establish the constants and exponent of the following equation in the form of reduced vapor pressure and reduced temperature: ln $lnP_r=2.64-{\frac{2.75}{T_r}}+1.48129lnT_r+0.11T^5_r$Only the normal boiling point ($T_b$= 20.268K), the critical pressure ($P_c$= 1292.81 kPa), and the critical temperature ($T_c$= 32.976K) are necessary to calculate the vapor pressure for an overall average deviation of 0.21% for 153 experimental vapor pressure data.