• Journal of environmental and Sanitary engineering
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• v.24 no.2
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• pp.17-30
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• 2009

In Iksan city, there have been a lot of complaints caused by offensive odor from residents living near the public environmental infrastructures and the Iksan industrial complex. To solve these problems, it is important to know the present condition of odor pollution level in these areas, the emission characteristics of malodorous gases in temporal and spatial variations in addition to meteorological components, and the facilities of major sources emitting malodorous compounds. The objectives of this study is to make the odor monitoring network for 20 people who lived and worked in areas where the environmental infrastructures and the Iksan industrial complex are located and their neighboring areas for six months from June 1st to October 31st in 2008 in Iksan and to monitor the temporal and regional frequency and characteristics of odor intensity using direct olfactory methods. As a result of odor monitoring, the highest frequency of sensed odor per month and 20 people for six months was found to be 107 in July, followed by 84 in September, 80 in August, 54 in June, 38 in October, respectively. Odor intensity trend showed a regional trend in the decreasing order of Dongsan-dong, Busong-dong, and Palbong-dong. Odor was widely perceived from night through next morning and considered as the sense of excreta, chemicals, sewage, compost, waste, etc. When high odor intensity was sensed, there were constant meteorological characteristics: relative humidity was 80~90%, wind speed was less than 0.5~1 m/sec, and main wind directions were from the east, the southeast, and the south.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.05a
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• pp.341-346
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• 2004

In the present work, for various energy and electricity generating systems to be compared in view of integrated social impacts, nuclear, coal-fired, heavy oil-fired, and LNG, and hydroelectricity systems are considered as electricity generating options. The following assessment factors are selected: economic effect, health effect, environmental effect, and benefit at the national level. As a preliminary study, these factors are represented as power generation cost, estimated mortality, Carbon Dioxide gas emission, and fuel supply stability, respectively. For integrated representation of a multi-criteria decision-making (MCDM) problem, radar charts are introduced to facilitate a comparative recognition of estimates. In the near future, based on the estimates, a MCDM methodology for both qualitative and quantitative comparison will be developed.

• Journal of Environmental Impact Assessment
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• v.9 no.3
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• pp.203-214
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• 2000

Health risk assessment is applied to streamlining LCA(Life Cycle Assessment) using Monte carlo simulation for probabilistic/stochastic exposure and risk distribution analysis caused by data variability and uncertainty. A case study was carried out to find benefits of this application. BTC(Benzene, Trichloroethylene, Carbon tetrachloride mixture alias) personal exposure cases were assumed as production worker(in workplace), manager(in office) and business man(outdoor). These cases were different from occupational retention time and exposure concentration for BTC consumption pattern. The result of cancer risk in these 3 scenario cases were estimated as $1.72E-4{\pm}1.2E+0$(production worker; case A), $9.62E-5{\pm}1.44E-5$(manger; case B), $6.90E-5{\pm}1.16E+0$(business man; case C), respectively. Portions of over acceptable risk 1.00E-4(assumed standard) were 99.85%, 38.89% and 0.61%, respectively. Estimated BTC risk was log-normal pattern, but some of distributions did not have any formal patterns. Except first impact factor(BTC emission quantity), sensitivity analysis showed that main effective factor was retention time in their occupational exposure sites. This case study is a good example to cover that LCA with probabilistic risk analysis tool can supply various significant information such as statistical distribution including personal/environmental exposure level, daily time activity pattern and individual susceptibility. Further research is needed for investigating real data of these input variables and personal exposure concentration and application of this study methodology.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.90-100
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• 2015

Green technologies such as renewable energy resources, Electric Vehicles and Plug-in Hybrid Electric Vehicles (EVs/PHEVs), electric locomotives, etc. are continually increasing at the existing power network especially distribution levels, which are Medium Voltage (MV) and Low Voltage (LV). It can be noted that the increasing level of green technologies is driven by the reduction emission policies of carbon dioxide ($CO_2$). The green technologies can affect the quality of power, and hence its impacts of are analysed. In practical, the environment such as wind, solar irradiation, temperature etc. are uncontrollable, and therefore the output power of renewable energy in that area can be varied. Moreover, the technology of the EVs/PHEVs is still developed in order to improve the performance of supply and driving systems. This means that these developed can cause harmonic distortion as the control system is mostly used power electronics. Therefore, this paper aims to analyse the voltage variation and harmonic distortion in distribution power network in urban area in Europe due to the combination between wind turbine, hydro turbine, photovoltaic (PV) system and EVs/PHEVs. More realistic penetration levels of SSDGs and EVs/PHEVs as forecasted for 2020 is used to analyse. The dynamic load demands are also taken into account. In order to ensure the accurate of simulation results, the practical parameters of distribution system are used and the international standards such as Institute of Electrical and Electronics Engineers (IEEE) standards are also complied. The suggestion solutions are also presented. The MATLAB/Simulink software is chosen as it can support complicate modelling and analysis.

• Journal of The Korean Astronomical Society
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• v.50 no.4
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• pp.125-129
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• 2017

We investigate the solar cycle variation of microwave and extreme ultraviolet (EUV) intensity in latitude to compare microwave polar brightening (MPB) with the EUV polar coronal hole (CH). For this study, we used the full-sun images observed in 17 GHz of the Nobeyama Radioheliograph from 1992 July to 2016 November and in two EUV channels of the Atmospheric Imaging Assembly (AIA) $193{\AA}$ and $171{\AA}$ on the Solar Dynamics Observatory (SDO) from 2011 January to 2016 November. As a result, we found that the polar intensity in EUV is anti-correlated with the polar intensity in microwave. Since the depression of EUV intensity in the pole is mostly owing to the CH appearance and continuation there, the anti-correlation in the intensity implies the intimate association between the polar CH and the MPB. Considering the report of Gopalswamy et al. (1999) that the enhanced microwave brightness in the CH is seen above the enhanced photospheric magnetic field, we suggest that the pole area during the solar minimum has a stronger magnetic field than the quiet sun level and such a strong field in the pole results in the formation of the polar CH. The emission mechanism of the MPB and the physical link with the polar CH are not still fully understood. It is necessary to investigate the MPB using high resolution microwave imaging data, which can be obtained by the high performance large-array radio observatories such as the ALMA project.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.6
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• pp.491-497
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• 2012

A hull-form for a 32,000G/T class Ro-Pax ferry has developed in accordance with a need of ferry operators to reduce fuel oil consumption(FOC) due to the drastic increase in oil prices recently and strengthening of environmental rules and regulations such as CO2 emission. A twin-skeg type is applied as the hull-form in lieu of an open-shaft type in order to improve propulsion performance. In order to achieve this object, flow control devices are installed to reduce a propeller induced vibration which is a main reason to obstruct the application of twin-skeg type passenger vessels owing to an uncomfortable vibration level. Numerical simulation by using an in-house code and a commercial code (Fluent) has performed to find out an optimum design of the flow control devices and to check an improvement in cavity volume. Model tests in Samsung Ship Model Basin are carried out to evaluate propulsion performance with the developed twin-skeg type hull and a reference hull of open-shaft type. In conclusion, it is shown that the twin-skeg type hull is better than the open-shaft in FOC by around 7% and in cavity volume by 20% as well.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.212-222
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• 2015

The characteristics of noise emission from tram systems should be investigated in order to design and construct an urban tram network that raises fewer environmental noise problems. In this paper, the characteristics of rolling noise from a tram were studied and a desired stiffness of the rail supports was proposed using a noise prediction model. The mobilities of embedded rails and resilient wheels were predicted using the Timoshenko beam model and the finite element model, respectively. The predicted mobilities were compared with the measured results. Compared with the measured values, the calculated noise level near the track showed small errors for frequencies higher than 300 Hz. Then, the source strengths of rail and wheel components were examined by varying the rail supporting stiffness and the slab supporting stiffness so that suitable stiffness values could be estimated that would reduce noise radiated from rails and wheels but that would not greatly increase the ground vibration.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.13-19
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• 2008

In this study, a variable induction and exhaust system is applied to turbocharged diesel engine to improve the volumetric efficiency, especially, in a low and transient engine speed range where much of the pollutant matters are expelled out. The volumetric efficiency is known as one of the most important factor which affects significantly engine performance, fuel economy and further emission and noise level. As the torque increase with the engine speed up, the gas flow in an exhaust pipe become pulsating and then has an effect on boost up capacity of air charging into the cylinder and expelling capacity to atmosphere simultaneously. But at a low and idling speed, the pulsation effect was not so significant. Accordingly, resonator was employed to compensate their loss. The variable induction system consists of the secondary pipe, resonator, intercooler, and torque variance were examined with extended operating conditions. In the mean time, for interpretation and well understanding for the phenomena of wave action that arising during intake and exhaust process between turbocharger and variable intake system, the concept of the combined supercharging was introduced. Some of results are depicted which deal with a pressure history during valve events of induction process. Consequently, by the governing of these phase and amplitude of pulsating wave, it enables us to estimate and evaluate for the intake system performance and also, designing stage of the system layout.

• Korean Journal of Cleft Lip And Palate
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• v.11 no.1
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• pp.1-12
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• 2008

In cleft palate patient, characteristic of speech disorder is the resonance disorder result from velopharyngeal incompetence. Clinically VPI caused by congenital factor as congenital palatal incompetence, submucosal cleft palate, and caused by acquired factor as CNS damage, tumor, palatal palsy. The clinicians more concerned about the speech disorders after cleft palate surgery rather than language pathologist. The resonance disorder devided for hypernasality, hyponasality and nasal emission, but as a rule, hypernasality is typical phenomenon of the resonance disorder. Traditionally clinicians and language pathologists evaluated four-stage or five-stage of hypernasality by subjective assessment. Although language pathologist is well-trained, results of the language level should be different. In late 1980s, Kay Elemetrics Corp. developed nasometer that objective nasalance identified with well-trained language pathologist and originate from nasometer Tonar I and II were developed by Fletcher. Therefore objective nasalance test was possible, the nasometer used in hospital, collage and speech clinic both and home and abroad. Standardization of the cleft palate speech assessment must be settled without delay because of different character result in different language and different assessment results by dialect in same language. In our study, we provide the data base for the standardization of cleft palate speech assessment which through report of objective assessment method, speech therapy effects and problems result in interdisciplinary teamwork by nasometer use in treatment of cleft palate patient.

• Korean Journal of Materials Research
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• v.27 no.1
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• pp.48-52
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• 2017

In this study, we used I-V spectroscopy, photoconductivity (PC) yield and internal photoemission (IPE) yield using IPE spectroscopy to characterize the Schottky barrier heights (SBH) at insulator-semiconductor interfaces of Pt/$HfO_2$/p-type Si metal-insulator-semiconductor (MIS) capacitors. The leakage current characteristics of the MIS capacitor were analyzed according to the J-V and C-V curves. The leakage current behavior of the capacitors, which depends on the applied electric field, can be described using the Poole-Frenkel (P-F) emission, trap assisted tunneling (TAT), and direct tunneling (DT) models. The leakage current transport mechanism is controlled by the trap level energy depth of $HfO_2$. In order to further study the SBH and the electronic tunneling mechanism, the internal photoemission (IPE) yield was measured and analyzed. We obtained the SBH values of the Pt/$HfO_2$/p-type Si for use in Fowler plots in the square and cubic root IPE yield spectra curves. At the Pt/$HfO_2$/p-type Si interface, the SBH difference, which depends on the electrical potential, is related to (1) the work function (WF) difference and between the Pt and p-type Si and (2) the sub-gap defect state features (density and energy) in the given dielectric.