• The Journal of the Acoustical Society of Korea
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• v.26 no.6
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• pp.250-258
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• 2007

Current speech recognition technology s achieved high performance with the development of hardware devices, however it is insufficient for some applications where high reliability is required, such as voice control of powered wheelchairs for disabled persons. For the system which aims to operate powered wheelchairs safely by voice in real environment, we need to consider that non-voice commands such as user s coughing, breathing, and spark-like mechanical noise should be rejected and the wheelchair system need to recognize the speech commands affected by disability, which contains specific pronunciation speed and frequency. In this paper, we propose non-voice rejection method to perform voice/non-voice classification using both YIN based fundamental frequency(F0) extraction and reliability in preprocessing. We adopted a multi-template dictionary and acoustic modeling based speaker adaptation to cope with the pronunciation variation of inarticulately uttered speech. From the recognition tests conducted with the data collected in real environment, proposed YIN based fundamental extraction showed recall-precision rate of 95.1% better than that of 62% by cepstrum based method. Recognition test by a new system applied with multi-template dictionary and MAP adaptation also showed much higher accuracy of 99.5% than that of 78.6% by baseline system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.109-116
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• 1984

In order to assess the protein nutritional quality of salted and dried yellow corvenia, which was prepared using the different salting methods like dry and brine salting, the changes of trypsin indigestible substrate(TI) and in vitro apparent protein digestibility were studied during storage at room temperature($24{\pm}1^{\circ}C$). It was also examined the retention of available lysine and formation of nonenzymatic brown pigments under the same conditions of preparing and storage mentioned above and confirmed the relationship between in vitro digestibility and the antinutritional factors, such as nonenzymatic browning, unavailability of lysine and TI content, TI content was gradually increased during the storage and in showed $1.5{\sim}2$ times more after 57 days storage than at the initial stage which ranged from 0.11 to 0.17mg/g solid. Of all the products, $25\%$ brine salting product contained the least TI content in 0.21 mg/g solid, while $10\%$ dry salting products was the most abundant in 0.30 mg/g solid using Hamerstrand method(1981). In vitro protein digestibility of all dried products was decreased significantly up to 30 days as the contents of TI increased, except $25\%$ brine salted products. After storing for 57 days, the in vitro digestibility was only $4\%$ drip showed in $25\%$ brine salted products. The nonenzymatic brown pigments were also developed on the level of available lysine reduced as in vitro protein digestibility was decreased throughout storage. Of all the various salted and dried products of yellow corvenia, $25\%$ salting product showed the lowest rate of browning development and loss of available lysine. Therefore, it was revealed that unavailability of lysine and development of nonenzymatic brown pigments were major factors influencing the protein quality in salted and dried yellow corvenia.

• Journal of Environmental Policy
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• v.4 no.1
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• pp.93-111
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• 2005

Defining soil quality in scopes and applications is one of the prerequisite for the sustainable management of soil environment to orient researches, strategies and policies. However, definition of soil quality is controversial depending upon a viewpoint of soil science or soil environment. Soil quality can be, irrespective of the disciplines, defined as the capacity of a soil to function within ecosystem boundaries to sustain biological productivity, maintain environmental quality and promote plant and animal health. Common to all of the soil quality concepts can be summarized as the capacity of soil to function effectively at present and in the future. The OECD includes soil quality as one of the agri-environment indicators. This article intends to i) summarize the current soil quality research, and ii) provide information on protocol of soil quality assessment. A framework for soil quality was divided into three steps: indicator selection as minimum data set (MDS), scoring of the selected indicators, and integration of scores into soil quality index. Korean government suggested possible physical and chemical indicators such as bulk density and organic matter for paddy and upland soils to OECD. The framework of soil quality assessment is not yet implemented in Korea. Countries such as USA, Canada and New Zealand have constructed the framework on soil quality assessment and developed a user-friendly version of soil quality assessment tools to evaluate the integrated effects of various soil management practices. The protocol provided in this review might help policymakers, scientists, and administrators improve awareness about soil quality and understand the way of soil environment management.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.355-362
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• 2014

Purpose : When head&neck cancer radiation therapy, thermoplastic mask is applied for patients with fixed. The purpose of this study is to evaluate usefulness of thermoplastic mask for SRS in tomotherapy by conparison with the conventional mask. Materials and Methods : Typical mask(conventional mask, C-mask) and mask for SRS are used to fix body phantom(rando phantom) on the same iso centerline, then simulation is performed. Tomotherapy plan for orbit and salivary glands is made by treatment planning system(TPS). A thick portion and a thin portion located near the treatment target relative to the mask S-mask are defined as region of interest for surface dose dosimetry. Surface dose variation depending on the type of mask was analyzed by measuring the TPS and EBT film. Results : Surface dose variation due to the type of mask from the TPS is showed in orbit and salivary glands 0.65~2.53 Gy, 0.85~1.84 Gy, respectively. In case of EBT film, -0.2~3.46 Gy, 1.04~3.02 Gy. When applied to the S-mask, in TPS and Gafchromic EBT3 film, substrantially 4.26%, 5.82% showed maximum changing trend, respectively. Conclusion : To apply S-mask for tomotherapy, surface dose is changed, but the amount is insignificant and be useful when treatment target is close critical organs because decrease inter and intra fractional variation.

• Journal of the Korean Electrochemical Society
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• v.3 no.1
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• pp.49-56
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• 2000

In the present we.k, temperature dependence of oxygen diffusivity in the polyvinyl chloride (PVC) film $D_f$ formed on gold electrode was investigated using steady-state rotating disk electrode (RDE) technique and modulated electrohydrodynamic (EHD) impedance technique. Both the diffusion rate defined as the ratio of oxygen diffusivity in the PVC film to the film thickness $D_f/\delta_f$ and the time constant $\delta_f^2/D_f$ for oxygen diffusion through the PVC film were obtained from plot of the limiting current versus disk rotation speed and from filing the EHD impedance spectra experimentally measured to those theoretically calculated on the basis of the diffusion equation for mass transport through the non-conductive and porous film, respectively. By combining measured $D_f/\delta_f$ with $\delta_f^2/D_f$, we determined $\delta_f\;and\;D_f$ at room temperature separately. As temperature increased, it appeared that the $D_f$ value measured for the PVC film-covered gold RDE was enhanced more rapidly than that $D_s$ value in the solution measured for the PVC film-free gold RDE. This means that the pores glowing with increasing temperature act as effective diffusion paths within the film. The present in-situ steady-state and modulated EHD measurements prove to be effective for determining $\delta_f\;and\;D_f$, separately and at the same time the porosity of the PVC film at temperatures below glass temperature $T_g$ of the film.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.1
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• pp.67-75
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• 2018

Purpose The purpose of this study is to investigate and analyze the external dose rates of $^{18}F-FDG$ Whole Body PET/CT patients by distance, and to identify the main factors that contribute to the reduction of radiation dose by checking the cumulative doses of nuclear medicine technologist(NMT). Materials and Methods After completion of the $^{18}F-FDG$ Whole Body PET/CT scan($75.4{\pm}3.3min$), the external dose rates of 106 patients were measured at a distance of 0, 10, 30, 50, and 100 cm from the chest. Gender, age, BMI(Body Mass Index), fasting time, diabetes mellitus, radiopharmaceutical injection information, creatine value were collected to analyze individual factors that could affect external dose rates from a patient's perspective. From the perspective of NMT, personal pocket dosimeters were worn on the chest to record accumulated dose of NMT who performed the injection task($T_1$, $T_2$ and $T_3$) and scan task($T_4$, $T_5$ and $T_6$). In addition, patient contact time with NMT was measured and analyzed. Results External dose rates from the patient for each distance were calculated as $246.9{\pm}37.6$, $129.9{\pm}16.7$, $61.2{\pm}9.1$, $34.4{\pm}5.9$, and $13.1{\pm}2.4{\mu}Sv/hr$ respectively. On the patient's aspect, there was a significant difference in the proximity of gender, BMI, Injection dose and creatine value, but the difference decreased as the distance increased. In case of dialysis patient, external dose rates for each distance were exceptionally higher than other patients. On the NMT aspect, the doses received from patients were 0.70, 1.09, $0.55{\mu}Sv/person$ for performing the injection task($T_1$, $T_2$, and $T_3$), and were 1.25, 0.82, $1.23{\mu}Sv/person$ for performing the scan task($T_4$, $T_5$, $T_6$). Conclusion we found that maintaining proper distance with patient and reducing contact time with patient had a significant effect on accumulated doses. Considering those points, efforts such as sufficient water intake and encourage of urination, maintaining the proper distance between the NMT and the patient(at least 100 cm), and reducing the contact time should be done for reducing dose rates not only patient but also NMT.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.52-57
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• 2010

Although chemical sedimentation and ion exchange are usually applied to the treatment of heavy metal ions and radioactive cations, they have some serious disadvantages like a great consumption of chemicals, the disposal of valuable metals, and the secondary pollution of soil by the solid-waste. The advanced countries recently have studied the electrochemical ion exchange, combined electrochemical reduction and ion exchange, for the development of the alternative technique. This study has been performed to investigate the optimum condition for the preparation of the nickel hexacyanoferrate (NiHCNFe) which is an electrochemical ion exchanger. NiHCNFe film was deposited on the surface of nickel plate by chemical method or electrochemical method. The morphology and composition of NiHCNFe were observed by SEM and EDS, respectively. The peak current density of NiHCNFe was measured from the cyclic voltammograms of the continuous oxidation-reduction reaction in a parallel plane ion exchange electrode reactor. It was found that the chemical preparation method was better than the electrochemical method. The concentrated NiHCNFe was apparently deposited on nickel plate when dipping in the preparing solution for 118 h, especially. It also had a best durable performance as an ion exchange electrode.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.218-226
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• 2020

An experimental study was conducted on baseline model updating and damage estimation techniques for the health monitoring of offshore wind turbine tripod substructures. First, a procedure for substructure health monitoring was proposed. An initial baseline model for a scaled model of a tripod substructure was established. A baseline model was updated based on the natural frequencies and the mode shapes measured in the healthy state. A training pattern was then generated using the updated baseline model, and the damage was estimated by inputting the modal parameters measured in the damaged state into the trained neural network. The baseline model could be updated reasonably using the effective fixity model. The damage tests were performed, and the damage locations could be estimated reasonably. In addition, the estimated damage severity also increased as the actual damage severity increased. On the other hand, when the damage severity was relatively small, the corresponding damage location was detected, but it was more difficult to identify than the other cases. Further studies on small damage estimation and stiffness reduction quantification will be needed before the presented method can be used effectively for the health monitoring of tripod substructures.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.869-876
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• 1996

Purification of 2,6-dimethylnaphthalene(2,6-DMNA) from the distillate containing a mixture of dimethylnaphthalene(DMNA) isomers of very high concentration was investigated by crystallization-recrystallization combination as a after-treatment for separation and purification of 2,6-DMNA in the light cycle oil(LCO). The separation of individual isomers of DMNA was studied by crystallization with the distillate as a feed. 2,6-DMNA, 2,7-dimethylnaphthalene(2,7-DMNA) and 2,3-dimethylnaphthalene(2,3-DMNA) were concentrated to crystal, and it was fould that separation between a group of 2,6-, 2,7-, 2,3-DMNA isomers and a group of the other DMNA isomers was possible. However, it was not possible to separate 2,6-, 2,7- and 2,3-DMNA from one another. To select the most suitable recrystallization solvent for purification of 2,6-DMNA, several conventional solvents, which have been employed commercially as recrystallization solvents for high purity performance, were tested, through measurement of solubility of 2,6- and 2,7-DMNA. The solvent used were hexane, iso-propyl ether, ethyl acetate and ethanol. From the solubility results for 2,6- and 2,7-DMNA, ethanol seemed to be the most suitable solvent for purification of 2,6-DMNA. Finally, with crystal recovered by crystallization as a feed and ethanol as a solvent, recrystallization experiments were conducted under various conditions. Purification of 2,6-DMNA was easily done with increasing operating temperature and solvent to feed ratio. These results show that the crystallization-recrystallization combination is an effective one for separation of individual isomers of DMNA.

• The Journal of the Acoustical Society of Korea
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• v.30 no.1
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• pp.22-32
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• 2011

The present study examined the effects of the complexity of the 3D models on the results of acoustic simulation which is the predominant tool of the acoustical design of buildings. Also, the effects of the 3D model on the auralized sounds were investigated. In order to carry out the study, four 3D models with different levels of complexity were introduced for a real auditorium which have different numbers of surfaces in the persuit of the guidance of odeon room acoustic software. The set-up of models was also based on the level of transition order of the program. And the acoustic experiments were performed measuring room acoustic parameters including SPL, RT, C80, D50. Acoustic computer simulations were performed using four different models. Then, the results of the computer modeling were compared with the measured acoustical parameters. In addition, sound sources were recorded in the field and auralized sounds were made in convolution with the impulse source made from acoustic modeling. Then, subjective tests were undertaken using auralized sounds. As the results, it was found that the result of the acoustic simulation were closer to the real room acoustic properties when 3D model was more particularly made. For the subjective test, the listening materials were acknowledged as similar with the real sound source when more complex 3D model was used. Then, it could be concluded that the complexity of the 3D model affects the results of the acoustic modeling as well as subjective tests.