• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.697-703
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• 2000

As device dimensions are lastly scaled down, impact ionization(I.I.) events are very important to analyze hot carrier transport in high energy region, and the exact model of impact ionization is demanded on device simulation. We calculate full band model by empirical pseudopotential method and the impact ionization rate is derived from modified Keldysh formula. We calculate impact ionization coefficients by full band Monte Carlo simulator to investigate temperature dependent characteristics of impact ionization for GaAs as a function of field. Resultly impact ionization coefficients are in good agreement with experimental values at look. We how energy is increasing along increasing the field, while energy is decreasing along increasing the temperature since the phonon scattering rates for emission mode are very high at high temperature. The logarithmic fitting function of impact ionization coefficients is described as a second orders function of temperature and field. The residuals of the logarithmic fitting function are mostly within 5%. We Dow, therefore, the logarithm of impact ionization coefficients has quadratic dependence on temperature, and we can save time of calculating the temperature dependent impact ionization coefncients as a function of field.

• Environmental Engineering Research
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• v.12 no.4
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• pp.176-193
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• 2007

The ability to measure groundwater contaminant flux is increasingly being recognized as crucial in order to prioritize contaminated site cleanups, estimate the efficiency of remediation technologies, measure rates of natural attenuation, and apply proper source terms to model groundwater contaminant transport. Recently, a number of methods have been developed and subsequently applied to measure contaminant mass flux in groundwater in the field. Flux measurement methods can be categorized as either point methods or integral methods. As the name suggests, point methods measure flux at a specific point or points in the subsurface. To increase confidence in the accuracy of the measurement, it is necessary to increase the number of points (and therefore, the cost) of the sampling network. Integral methods avoid this disadvantage by using pumping wells to interrogate large volumes of the subsurface. Unfortunately, integral methods are expensive because they require that large volumes of contaminated water be extracted and managed. Recent work has investigated the development of an integral method that does not require extraction of contaminated water from the subsurface. We begin with a review of the significance and importance of measuring groundwater contaminant mass flux. We then review groundwater contaminant flux measurement methods that are either currently in use or under development. Finally, we conclude with a qualitative comparison of the various flux measurement methods.

• The Korean Journal of Pharmacology
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• v.17 no.2
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• pp.63-67
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• 1981

Effect of acetazolamide on the diuretic action of furosemide was investigated in rabbits. The rates of urine flow and excretion of salts were significantly reduced when furosemide (0.5 mg/kg) was administered with acetazolamide (10 mg/kg) compared to the diuretic response of the single furosemide (0. 5 mg/kg) administration. Reduction in the fractional excretion rate of urine volume was more pronounced than the fractional excretion rate of salts. The results suggest that reduction of diuretic action on furosemide by combined administration of acetazolamide is probably due elevated urinary pH and interference in the mechanism of inhibition of chloride transport in the ascending Henle's limb.

• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.1
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• pp.39-46
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• 1998

This study presents a numerical model that can simulate changes of particle size distribution (PSD) of PCB-contaminated coastal sediments. The developed model has one spatial dimension including sedimentation and vortical dispersion as well as coagulation. The reason for considering the vortical transport mechanisms is to calculate residence time of the particles. Using the model and Initial PSD data based on actual coastal sediments contaminated with PCBs, this study shows results of model simulations. Within 48 hours of the simulation time, the PSD changed significantly and the particles were removed from water in different rates between different particle sizes. It also shows that coagulation can act an important role in this process. The model may be useful in assessing the range of resuspended sediments that can pollute neighboring areas during environmental remediation projects such as dredging.

• Environmental and Resource Economics Review
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• v.29 no.3
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• pp.389-418
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• 2020

Some OECD countries are showing signs of decoupling in the transportation sector. In terms of sustainable development, the decoupling of economic activities and greenhouse gas emissions in the transportation sector is very important. This study calculated a decoupling index of greenhouse gas emissions in the transportation sector for 25 OECD countries. Also this study analyzed the impact of energy transition on decoupling regimes. According to the analysis, a considerable number of countries have reached the decoupling phase, and some countries have shown strong decoupling regime in which greenhouse gas emissions are reduced despite economic growth. From ordered panel logit analysis, energy transition had significant impact on achieving decoupling phase. Electrification of transport had a positive effect on the decoupling, while the gasification was not significant. In addition, small traffic, high urbanization rates, strong environmental policies, and high trade opening have had significant effects on achieving decoupling.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1784-1791
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• 2020

The 14 MeV neutron generator facility is being developed by the Institute for Plasma Research India to conduct the lab scale experiments related to Indian breeding blanket system for ITER and DEMO. It will also be utilized for material testing, shielding experiments and development of fusion diagnostics. Occupational radiation exposure control is necessary for the all kind of nuclear facilities to get the operational licensing from governing authorities and nuclear regulatory bodies. In the same way, the radiation exposure for the 14 MeV neutron generator facility at the occupational worker area and accessible zones for general workers should be under the permissible limit of AERB India. The generator is designed for the yield of 10¹² n/s. The shielding assessment has been made to estimate the radiation dose during the operational time of the neutron generator. The facility has many utilities and constraints like ventilation ducts, accessible doors, accessibility of neutron generator components and to conduct the experiments which make the shielding assessment challenging to provide proper safety for occupational workers and the general public. The neutron and gamma dose rates have been estimated using the MCNP radiation transport code and ENDF -VII nuclear data libraries. The ICRP-74 fluence to dose conversion coefficients has been used for the assessment. The annual radiation exposure has been assessed by considering 500 h per year operational time. The provision of local shield near to neutron generator has been also evaluated to reduce the annual radiation doses. The comprehensive results of radiation shielding capability of neutron generator building and local shield design have been presented in the paper along with detailed maps of radiation field.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.460-464
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• 2000

As device dimensions are lastly scaled down, impact ionization(I.I.) events are very important to analyze hot carrier transport in high energy region, and the exact model of impact ionization is demanded on device simulation. We calculate full band model by empirical pseudopotential method and the impact ionization rate is derived from modified Keldysh formula. We calculate impact ionization coefficients by full band Monte Carlo simulator to investigate temperature-and field-dependent characteristics of impact ionization for GaAs. Resultly impact ionization coefficients are In good agreement with experimental values at 300k. We know energy is increasing along increasing the field. while energy is decreasing along increasing the temperature since the phonon scattering rates for omission mode are very high at high temperature. The logarithmic fitting function of impact ionization coefficients is described as a second orders function for temperature and field. The residuals of the logarithmic fitting function are mostly within 5%. We know, therefore, logarithm of impact ionization coefficients has quadratic dependence on temperature and field, and we can save time of calculating the temperature- and field-dependent impact ionization coefficients.

• Korean Journal of Cleft Lip And Palate
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• v.8 no.1
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• pp.11-22
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• 2005

There ate anteroposterior$\cdot$vertical maxillary underdevelopment, transverse maxillary deficiency and wide cleft alveolus$\cdot$oroanual fistula among cleft lip ant palate related maxillary deformities. For treatment of these deformities, ones have used conventional treatment methods, there were often unsatisfactory results to patients and operators both. Since llizarov introduced effective technique of bone lengthening and augmentation for a variety of limb defotmities, application of distraction osteogenesis on maxillofacial area has been used to solve those disadvantages of conventional methods. Authors introduced following three cases about use of distraction osteogenesis. The first case is the application of RED(rigid external distraction) II system for the treatment of the anteroposterior$\cdot$vertical maxillary hypoplasia after several times of surgery and end of development in bilateral cleft lip and palate patient. The second case is the application of the USPD(unilateral segmental palatal distraction) for the resolution of the unilateral posterior crossbite and transverse dental arch asymmetry after alveolorraphy in growing unilateral cleft lip and palate patient. The third case is the application of transport distraction osteogenesis far closure of the wide clef alveolus and oroantral fistula in growing bilateral cleft lip and palate patient. There were satisfactory results in these cases. Particularly, in comparison with the decreases of relapse rates, the reduction of the hospitalization time and post-operative discomfort owing to minimal surgical intervention.

• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.135-142
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• 2009

In this investigation, we prepared a 1 and 3-parallel serpentine single PEMFC, which has an active area of $100\;cm^2$ and a flow channel cross section of $1{\times}1mm$. Distribution and transport of water in a non-operating PEMFC were observed by varying flow types and the flow rates (250, 400, and 850 cc/min). This investigation was performed at the neutron imaging facility at the CO1d Neutron RAdiography facility (CONRAD), HMI, Germany of which the collimation ratio and neutron fluence rate are 250, $1{\times}10^{6}n/s/cm^2$, respectively. The neutron image was continuously recorded by a scintillator and lens-CCD coupled detector system every 10 seconds. It has been observed that although the distilled water was supplied into the cathode channel only, the neutron image showed a water movement from the cathode to the anode channel. The water at the cathode channel was completely discharged as soon as the pressurized air was supplied. But the water at the anode channel was not easily removed by the pressurized air except for the 3-parallel serpentine type with 850cc/min of air flow rate. Moreover, the water at the MEA wasn't removed for any of the cases.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.129-137
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• 2016

Transmission Control Protocol as a transport layer protocol provides steady data transfer service. There are some serious concerns about the performance of TCP over diverse networks. The vital concern in TCP network environment is congestion which may occur due to quick transmission rates or because of large number of new connections entering the network at the same time. Size of queues in routers grows thus resulting in packet drops. Retransmission of the dropped packets, and reduced throughput can prove costly. Explicit Congestion Notification (ECN) in conjunction with Active Queue Management mechanisms (AQM) such as Random early detection (RED) is used for packet marking rather than dropping. In IP packet header ECN bits can be added as a sign of congestion thus avoiding needless packet drops. The proposed ECN and AQM mechanism can be implemented with help of ns2 simulator and the performance can be tested on different TCP variants.