• Journal of Korean Society for Atmospheric Environment
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• v.29 no.4
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• pp.353-368
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• 2013

All Koreans had suffered heavily from municipal and industrial air pollution problems since 1960's to 1980's. However the levels of $SO_2$, CO, and Pb have been dramatically decreased since 1990's due to various air pollutants' reduction policies under the provisions of the 1978 Environmental Preservation Act and the 1990 Air Quality Preservation Act such as increasing the supply of low-sulfur fuel, the use of cleaner fuel, no use of solid fuel, and so on. Even though the national ambient air quality standard has been strengthened to protect public health and welfare, the levels of $NO_2$, $O_3$, and $PM_{10}$ frequently exceed the corresponding standards; for example, only 4 stations (1.7%) out of 239 nationwide monitoring stations satisfied the 24-hr based PM10 standard in 2011. Moreover, upto the present time, since there are serious underlying policies of economism and growth-first which can not be solely solved by the environmental laws, it is difficult to root out undesirable social evils such as public indifference, passive academic activities, complacent government bureaucracy, insufficient social responsibility of enterprise, and radical activities of environmental groups. The paper initially reviewed air pollution history of Korea with surveying various environmental factors affecting in/out-door air pollution in the past Korea. Further this study extensively investigated legal and political changes on air pollution control and management for the last 50 years, and then intensively discussed the present environment-related laws and policies unreasonably enforced in Korea. It is necessary to practically revise many outdated legal policies based on health-oriented thinking and on our current economic levels as well.

• The Korean Journal of Nuclear Medicine
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• v.39 no.2
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• pp.94-99
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• 2005

Electrocardiogram-gated single photon omission computed tomography (SPECT) provides valuable information in the assessment of both myocardial perfusion and ventricular function. Tl-201 is a suboptimal isotope for gating. Tl-201 images are more blurred compared with Tc-99m tracers due to the increased amount of scattered photons and use of a smooth filter. The average myocardial count densities are approximately one-half those of conventional technetium tracers. However, Tl-201 is still widely used because of its well-established utility for assessing myocardial perfusion, viability and risk stratification. Gated SPECT with Tl-201 enables us to assess both post-stress and rest left ventricular volume and function. Previous studies with gated Tl-201 SPECT measurements of ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV) have shown high correlation with first-pass radionuclide angiography, gated blood pool scan, Tc-99m-MIBI gated SPECT, contrast ventriculography, echocardiography, and 3-dimensional magnetic resonance imaging. However, problems related to these studies include few agreement data of EDV and ESV, use of a reference method that is likely to have the same systemic errors (gated Tc-99m-MIBI SPECT), and other technical factors related to the count density of gated SPECT. With optimization of gated imaging protocols and more validation studies, gated Tl-201 SPECT would be an accurate method to provide perfusion and function information in patients with coronary artery disease.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.401-408
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• 2016

Desalination is getting more attention as an alternative to solve a global water shortage problem in the future. Especially, a desalination technology is being expected as a new growth engine of Korea's overseas plant business besides one of the solutions of domestic water shortage problem. In the past, a thermal evaporation technology was a predominant method in desalination market, but more than 75% of the current market is hold by a membrane-based reverse osmosis technology because of its lower energy consumption rate for desalination. In the future, it is expected to have more energy efficient desalination process. Accordingly, various processes are being developed to further enhance the desalination energy efficiency. One of the promising technologies is a desalination process combined with Pressure Retarded Osmosis (PRO) process. The PRO technology is able to generate energy by using osmotic pressure of seawater or desalination brine. And the other benefits are that it has no emission of $CO_2$ and the limited impact of external environmental factors. However, it is not commercialized yet because a high-performance PRO membrane and module, and a PRO system optimization technology is not sufficiently developed. In this paper, the recent research direction and progress of the SWRO-PRO hybrid desalination was discussed regarding a PRO membrane and module, an energy recovery system, pre-treatment and system optimization technologies, and so on.

• Journal of Periodontal and Implant Science
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• v.45 no.3
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• pp.94-100
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• 2015

Purpose: The aim of this study was to investigate the combined effects of physical and chemical surface factors on in vivo bone responses by comparing chemically modified hydrophilic sandblasted, large-grit, acid-etched (modSLA) and anodically oxidized hydrophobic implant surfaces. Methods: Five modSLA implants and five anodized implants were inserted into the tibiae of five New Zealand white rabbits (one implant for each tibia). The characteristics of each surface were determined using field emission scanning electron microscopy, energy dispersive spectroscopy, and confocal laser scanning microscopy before the installation. The experimental animals were sacrificed after 1 week of healing and histologic slides were prepared from the implant-tibial bone blocks removed from the animals. Histomorphometric analyses were performed on the light microscopic images, and bone-to-implant contact (BIC) and bone area (BA) ratios were measured. Nonparametric comparison tests were applied to find any significant differences (P<0.05) between the modSLA and anodized surfaces. Results: The roughness of the anodized surface was $1.22{\pm}0.17{\mu}m$ in Sa, which was within the optimal range of $1.0-2.0{\mu}m$ for a bone response. The modSLA surface was significantly rougher at $2.53{\pm}0.07{\mu}m$ in Sa. However, the modSLA implant had significantly higher BIC than the anodized implant (P=0.02). Furthermore, BA ratios did not significantly differ between the two implants, although the anodized implant had a higher mean value of BA (P>0.05). Conclusions: Within the limitations of this study, the hydrophilicity of the modSLA surface may have a stronger effect on in vivo bone healing than optimal surface roughness and surface chemistry of the anodized surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.31-34
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• 2002

HgTe quantum dots were synthesized in aqueous solution at room temperature by colloidal method. The synthesized materials were identified to be zincblende cubic structured HgTe quantum dots by X-ray diffraction and transmission electron microscopy image revealed that these quantum dots are agglomerate of a individual particle. The colloidally prepared HgTe quantum dots have the sphere-like shape with a diameter of approximately 4 nm. The optical properties of the HgTe quantum dots were investigated with photoluminescence(PL). The PL appears in the near-infrared region, which represent a dramatic shift from bulk HgTe behavior. The analytic results revealed that HgTe quantum dots have the broad size distribution, as PL emission spectrum covers the spectral region from 900 to 1400 nm. In this study, the factors affecting PL of HgTe quantum dots and particle size distributiont are described.會Ā᐀䁇?⨀젲岒Ā㰀會Ā㰀顇?⨀끩Ā㈀會Ā㈀?⨀䡪ఀĀ᐀會Ā᐀䡈?⨀Ā᐀會Ā᐀ꁈ?⨀硫ᜀĀ저會Ā저?⨀샟ගऀĀ저會Ā저偉?⨀栰岒ఀĀ저會Ā저ꡉ?⨀1岒Ā저會Ā저J?⨀惝ග؀Ā؀會Ā؀塊?⨀ග嘀Ā切會Ā切끊?⨀⣟ගĀ搀會Ā搀ࡋ?⨀큭킢Ā저會Ā저恋?⨀桮킢Ā저會Ā저롋?⨀⣅沥ࠀĀࠀ會Āࠀ၌?⨀샅沥Ā저會Ā저桌?⨀壆沥ሀĀ저會Ā저쁌?⨀o킢瀀ꀏ會Āᡍ?⨀棤좗ĀĀĀ會ĀĀ灍?⨀å좗ĀĀĀ會ĀĀ졍?⨀飥좗ĀĀĀ會ĀĀ⁎?⨀?ꆟᤀ

• Journal of the Institute of Convergence Signal Processing
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• v.20 no.2
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• pp.78-83
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• 2019

Sounds based machine fault diagnosis recovers all the studies that aim to detect automatically abnormal sound on machines using the acoustic emission by these machines. Conventional methods that use mathematical models have been found inaccurate because of the complexity of the industry machinery systems and the obvious existence of nonlinear factors such as noises. Therefore, any fault diagnosis issue can be treated as a pattern recognition problem. We propose here an automatic fault diagnosis method of hand drills using discrete wavelet transform(DWT) and pattern recognition techniques such as artificial neural networks(ANN). We first conduct a filtering analysis based on DWT. The power spectral density(PSD) is performed on the wavelet subband except for the highest and lowest low frequency subband. The PSD of the wavelet coefficients are extracted as our features for classifier based on ANN the pattern recognition part. The results show that the proposed method can be effectively used not only to detect defects but also to various automatic diagnosis system based on sound.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.1-12
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• 2015

The current scenario of the transportation sector reflects the urgent need to address issues such as depletion of traditional fuel reserves and ever growing pollution levels. Researchers around the world are focussing on alternatives as well as optimisation of currently employed devices to reduce the pollution levels generated by the commonly used fuels. One such optimisation involves the study of air flow within the intake manifolds of SI engines. It is a well-known fact that alterations in the air manifolds of engines have a significant impact on the engine performance parameters, fuel consumption and emission levels. Previous works have demonstrated the impacts of runner lengths, diameter, plenum volume, taper angle of distribution manifolds and other factors on in-cylinder fluid motion and engine performance. However, a static setup provides an optimal configuration only at a specific engine speed. This paper aims to investigate the variations in the same parameters on a four stroke, naturally aspirated single cylinder SI engine through varying the cross section design over the intake runner with the aid of Computational Fluid Dynamics. The system consists of segments that form the intake runner with projections on the inside that allow various permutations of the intake runner segments. The various configurations provide the optimised fluid flow characteristics within the intake manifold at specific engine speed intervals. The variations such as turbulence, air fuel mixing are analysed using the three dimensional CFD software FLUENT. The results can be used further for developing an automated or manually adjustable intake manifold.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.273-281
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• 1992

A new sputtering chamber, as Atomsource, for atomic absorption measurements was designed and built to have maximum ground state atoms in view and minimum emission. The high velocity gas jets not only change the visual and electrical characteristics of the discharge, but also increase the amount of material atomized, as is apparent from the craters that are produced in the sample where the jets strike the surface. The use of gas jets in a sputtering cell makes this a direct sampling method practical for atomic absorption spectrometry. The factors influencing absorption sensitivity and reproducibility have been investigated for the newly developed atomizer.

• Radiation Oncology Journal
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• v.37 no.1
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• pp.51-59
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• 2019

Purpose: We evaluated failure pattern and treatment outcomes of observational approach on regional lymph node (LN) in cutaneous melanoma of extremities and sought to find clinico-pathologic factors related to LN metastases. Material and Methods: We retrospectively reviewed 73 patients with cutaneous melanoma of extremities between 2005 and 2016. If preoperative 18-F-fluorodeoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) findings were non-specific for regional LNs, surgical resection of primary tumors with adequate margins was performed without sentinel lymph node biopsy (SLNB) and/or complete lymph node dissection (CLND), irrespective of tumor thickness or size. In patients with suspicious or positive findings on PET/CT or CT, SLNB followed by CLND or CLND was performed at the discretion of the surgeon. We defined LN dissection (LND) as SLNB and/or CLND. Results: With a median follow-up of 38 months (range, 6 to 138 months), the dominant pattern of failure was regional failure (17 of total 23 events, 74%) in the observation group (n = 56). Pathologic LN metastases were significant factor for poor regional failure-free survival (hazard ration [HR] = 3.21; 95% confidence interval [CI], 1.03-10.33; p = 0.044) and overall survival (HR = 3.62; 95% CI, 1.02-12.94; p = 0.047) in multivariate analysis. In subgroup analysis for cN0 patients according to the preoperative PET/CT findings, LND group showed the better trend of LRFFS (log rank test, p = 0.192) and RFFS (p = 0.310), although which is not statistically significant. Conclusion: Observational approach on regional LNs on the basis of the PET/CT in patients with cutaneous melanoma of extremities showed the dominant regional failure pattern compared to upfront LND approach. To reveal regional lymph node status, SLND for cN0 patients may of importance in managing cutaneous melanoma patients.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.4
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• pp.119-129
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• 2010

The joint use of remotely sensed data and field measurements has been widely used to estimate aboveground carbon stock in many countries. Recently, Korea Forest Research Institute has developed new carbon emission factors for kind of tree, thus more accurate estimate is possible. In this study, the aboveground carbon stock of Danyang area in South Korea was estimated using k-Nearest Neighbor(kNN) algorithm with the 5th National Forest Inventory(NFI) data. Considering the spectral response of forested area under the climate condition in Korea peninsular which has 4 distinct seasons, Landsat TM seasonal satellite images were collected. As a result, the estimated total carbon stock of Danyang area was ranged from 3542768.49tonC to 3329037.51tonC but seasonal trends were not found.