• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.693-698
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• 2006

In Class I cavity, the highest C-factor could be obtained and it means the highest polymerization shrinkage stress. In this study, high C-factor model was designed. The pulpose of present study was to determine differences of Microtensile bond strength (MTBS) of class I cavity pulpal and axial wall specimens in primary molar. Twenty clean mandibular 2nd primary molars were randomly divided into two groups Different composite Resins (Filtek Z250, 3M ESPE & Filtek Supreme, 3M ESPE) were bulk filled and photo cured. Axial wall specimens and pulpal specimens were prepared at the same teeth, All specimens were divided into 4 groups and MTBS were evaluated. Group ZP : Filtek Z250-Pulpal wall Group ZA : Filtek Z250-Axial wall Group SP : Filtek Supreme - Pulpal wall Group SA : Filtek Supreme - Axial wall The results were as follows: 1. Mean MTBS of ZP & ZA and SP & SA were significantly different(p<.001). 2. There was no significant difference between MTBS of ZP & SP and ZA & SA.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.8
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• pp.683-691
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• 2015

Circulating Fluidized Bed(CFB) combustion has the several advantages which are the fuel flexibility, the economy, the efficiency and the environment. It is necessary to apply a renewable energy to produce electricity due to the Renewable Portfolio Standard(RPS) mandates recently. So, in this study, co-combustion with a coal and a wood pellet was investigated to evaluate the combustibility and the environment as function of blending ratio of them in a Lab-scale CFB reactor. To investigate the characteristics of the co-combustion, the blending ratio which is the weight of wood pellet by the total calorific value of the supplied, was considered. Bed material was a river sand(No. 7). As increasing the blending ratio, the exhausted gas emissions such as CO, NOx, HC and SOx were decreased. But in case of wood pellet over 30%, CO, HC and SOx emission were increased. And the gas temperatures at the downstream were decreased.

• Toxicological Research
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• v.26 no.4
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• pp.293-300
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• 2010

tert-Butyl acetate (TBAc) is an organic solvent, which is commonly used in architectural coatings and industrial solvents. It has recently been exempted from the definition of a volatile organic compound (VOC) by the Air Resources Board (ARB). Since the use of TBAc as a substitute for other VOCs has increased, thus its potential risk in humans has also increased. However, its inhalation toxicity data in the literature are very limited. Hence, inhalation exposure to TBAc was carried out to investigate its toxic effects in this study. Adult male rats were exposed to TBAc for 4 h for 1 day by using a nose-only inhalation exposure chamber (low dose, $2370\;mg/m^3$ (500 ppm); high dose, $9482\;mg/m^3$ (2000 ppm)). Shamtreated control rats were exposed to clean air in the inhalation chamber for the same period. The animals were killed at 2, 7, and 15 days after exposure. At each time point, body weight measurement, bronchoalveolar lavage fluid (BALF) analysis, histopathological examination, and biochemical assay were performed. No treatment-related abnormal effects were observed in any group according to time course. Based on those findings, the median lethal concentration ($LC_{50}$) of TBAc was over $9482\;mg/m^3$ in this study. According to the MSDS, the 4 h $LC_{50}$ for TBAc for rats is over $2230\;mg/m^3$. We suggested that this value is changed and these findings may be applied in the risk assessment of TBAc which could be beneficial in a sub-acute study.

• Journal of Life Science
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• v.22 no.1
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• pp.80-86
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• 2012

This study was conducted to improve quality of takju where natural honey is used to control the ripening fermentation and the amount of sediment derived from takju mash. A koji was prepared using rice starch and Aspergillus awamori var. kawachii. Takju mash was prepared by alcohol fermentation with Saccharomyces cerevisiae and a 3-step addition of steamed rice. The clean part of the mash (CPM) was separated from the sediment at $5^{\circ}C$ and 5% (w/v) of natural honey was added and then ripened for 23 days at 5, 10, or $15^{\circ}C$. Temperature, pH, acidity, and total sugar content showed no significant differences, but a 0.2 percent reduction in alcohol content occurred during storage. However, CPM ripened with honey had a comparatively higher score on sensory evaluation than did immature CPM with added honey added. Takju with 8% alcohol content was prepared by mixing the water from the mixed CPM ripened with honey together with 100, 50, and 25% of the frozen sediment. Several quality characteristics of the takju were checked over 37 days of fermentation at $10^{\circ}C$. The pH was sustained between 4.1 and 4.3, and changes in the number of viable yeast cells, acidity, total sugar amounts, and alcohol content showed similar patterns but differences in scale. Smaller amounts of sediment affected the stability of the takju. Mixing the CPM ripened with natural honey at low temperature moderately reduced the amount of sediment in the mash and resulted in a highly flavorful takju with an extended shelf life.

• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.112-121
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• 1997

In this paper, we study a model parameter compensation method for noise-robust speech recognition. We study model parameter compensation on a sentence by sentence and no other informations are used. Parallel model combination(PMC), well known as a model parameter compensation algorithm, is implemented and used for a reference of performance comparision. We also propose a modified PMC method which tunes model parameter with an association factor that controls average variability of gaussian mixtures and variability of single gaussian mixture per state for more robust modeling. We obtain a re-estimation solution of environmental variables based on the expectation-maximization(EM) algorithm in the cepstral domain. To evaluate the performance of the model compensation methods, we perform experiments on speaker-independent isolated word recognition. Noise sources used are white gaussian and driving car noise. To get corrupted speech we added noise to clean speech at various signal-to-noise ratio(SNR). We use noise mean and variance modeled by 3 frame noise data. Experimental result of the VTS approach is superior to other methods. The scheme of the zero order VTS approach is similar to the modified PMC method in adapting mean vector only. But, the recognition rate of the Zero order VTS approach is higher than PMC and modified PMC method based on log-normal approximation.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.668-673
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• 2008

The objective of this study is to optimize the leaching conditions of sequential leaching and extracting processes for selective Ni recovery from spent Ni-Mo-based catalyst. The selective Ni recovery process consists of two processes of leaching and extracting process. In this 2-step process, Ni component is dissolved from solid spent Ni-Mo-based catalyst into leaching agent in leaching process and sequentially extracted to Ni complex with an extracting agent in the extracting process. The solutions of nitric acid ($HNO_3$), ammonium carbonate ($(NH_4)_2CO_3$) and sodium carbonate ($Na_2CO_3$) were used as a leaching agent in leaching process and oxalic acid was used as an extracting agent in extracting process. $HNO_3$ solution is the most efficient leaching agent among the various leaching agent. Also, the optimized leaching conditions for the efficient and selective Ni recovery were the leaching temperature of $90^{\circ}C,\;HNO_3$ concentration of 6.25 vol% and elapsed time of 3 h. As a result, Nickel oxalate having the highest yield of 88.7% and purity of 100% was obtained after sequentially leaching and extracting processes under the optimized leaching conditions.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.235-244
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• 2007

Potentials of AR CDM project in North Korea are assessed and feasible land area for AR CDM project is estimated. According to our estimation, There could be 515,000 hectares of forest lands deforested before 1990 in North Korea and 8,854 hectares at the regional level of Gae-sung City, which are eligible for AR CDM project, based on researches of satellite image analyses conducted from 1980's to 1990's. A baseline scenario assumed 44.73 tones of carbon stored in soil per hectare with no vegetation above ground remained during the project period following the default value of IPCC's Good Practice Guidance for LULUCF considering soil structure, climate and land use of the project area. The scenario also assumes that black rocust (Robinia pseudoacacia) is planted and the CDM project is implemented for 20 years. The costs for producing greenhouse gases CER (certified emission reduction) credits include costs of tree planting and forest management, and costs of project negotiation and transactions for issuing the credits. It is estimated that 376 tones of carbon dioxide per hectare can be accumulated and 503 temporary CER credits per hectare and 265 long-term CER credits per hectare could be produced during the project period. It is estimated to cost US$ 4.04 and US$ 7.67 to provide one unit of temporary credit and long-term credit, respectively. These values can be regarded as the cost of conferring emission commitment of a country or a private entity. However, it is not clear which option is better economically because the replacement periods are different in these two cases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.337-346
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• 2014

This study aimed to understand the mode characteristics of a droplet subject to periodic forced vibration and the detachment of a droplet placed on a plate surface. An surface was coated with Teflon to clearly observe the behavior of a droplet. The contact angle between the droplet and surface and the hysteresis were found to be approximately $115^{\circ}C$ and within $25^{\circ}C$, respectively. The coating process was performed in a clean room that had an environment with a low level of contaminants and impurities such as air dust, detergents, and particles. To predict the resonance frequency of a droplet, theoretical and experimental approaches were applied. Two high-speed cameras were configured to acquire side and top views and thus capture different characteristics of a droplet: the mode shape, the detachment, the separated secondary droplet, and the waggling motion. A comparison of the theoretical and experimental results shows no more than 18 discrepancies when predicting the resonance frequency. These differences seem to be caused by contact line friction, nonlinear wall adhesion, and the uncertainty of the experiment. For lower energy inputs, the contact line of the droplet was pinned and the oscillation pattern was axisymmetric. However, the contact line of the droplet was de-pinned as the oscillation became more vigorous with increased energy input. The size of each lobe at the resonance frequency is somewhat larger than that at the neighboring frequency. A droplet in mode 2, one of the primary mode frequencies, exhibits vertical periodic movement as well as detachment and secondary ejection from the main droplet.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.10
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• pp.4297-4302
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• 2015

Background: To evaluate HPV testing by Hybrid Capture II (HCII) in conjunction with cytology in detecting the residual/recurrence disease after treatment of high-grade cervical intraepithelial neoplasia (CIN II-III) with loop electrosurgical excision procedure (LEEP). Materials and Methods: A retrospective review of 158 patients with histologically confirmed CIN II-III who underwent LEEP between January 2011 and October 2012 was conducted. Post-treatment control was scheduled at the 3rd, 6th, 12th and 18th month. All patients were followed up by Pap smear and HR-HPV genotype and viral load testing. Results: Pre-treatment, HR-HPV DNA, was detected in all specimens of the patients. At follow-up, 25 patients were diagnosed as the residual/recurrent disease during the FU visit, among whom, 16 patients with positive margin: 13 patients (52%) with HR-HPV DNA+/cytology+, 2 patients (8%) with HR-HPV DNA+/cytology-, 1 patient (4%) with cytology+/HR-HPV DNA-; 9 patients with clean margin - 5 patients (55.6%) with HR-HPV DNA+/cytology+; 2 patients (22.2%) with HRHPV DNA+/cytology-, 2 patients (22.2%) with cytology+/HR-HPV DNA-. None of them persisting HR-HPV DNA-/cytology-with positive or negative margin was identified as the residual/recurrent disease. The majority of residual/recurrent disease was detected at the 12th and 18th month FU, and there was almost no difference in the sensitivity and negative predictive value (NPV) between at the 3rd month and the 6th month FU visits. 14 residual/recurrence disease (14/46:30.4%) had pre-treatment high viral load (>5 000 RUL/PC) and 11 (11/112, 9.8%) with pre-treatment low viral load, P<0.05. Conclusions: (1) The persistence HR-HPV DNA is the root cause of the residual/recurrent disease for the women treated for high-grade CIN; the pre-treatment viral load and margin can be seen as the predictor. (2) The FU visit beginning at the 6th month post-treatment and lasting at least 24 months with the combination of cytology and HPV testing. (3) Patients with high pre-treatment HPV load, which is considered as one risk of developing the residual/recurrent disease, should be paid more attention (especially above 500RUL/PC) to by clinicians.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.167-175
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• 2018

Natural gas is a clean fuel that discharges almost no air-contaminating substances. This study examined the simultaneous reduction of $CH_4$ and NOx of NGOC/LNT catalysts for CNG buses related to the improvement of the $de-CH_4/NOx$ performance, focusing mainly on identifying the additive catalysts, loading of the washcoat, stirring time, and types of substrates. The 3wt. % Ni-loaded NGOC generally exhibited superior $CH_4$ reduction performance through $CH_4$ conversion, because Ni is an alkaline, toxic oxide, and exerts a reducing effect on $CH_4$. A excessively small loading resulted in insufficient adsorption capacity of harmful gases, whereasa too high loading of washcoat caused clogging of the substrate cells. In addition, with the economic feasibility of catalysts considered, the appropriate amount of catalyst washcoat loading was estimated to be 124g/L. The NOx conversion rate of the NGOC/LNT catalysts stirred from $200^{\circ}C$ to $550^{\circ}C$ for 5 hours showed 10-15% better performance than the NGOC/LNT catalysts mixed for 2 hours over the entire temperature range. The NGOC/LNT catalysts exhibitedapproximately 20% higher $de-CH_4$ performance on the ceramic substrates than on the metal substrates.