• The Korean Journal of Malacology
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• v.15 no.1
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• pp.57-62
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• 1999

Condition indices (Cl) are considered to be useful measurements of the nutritive and health status of bivalves although studies on Cl of bivalves are limited due to the lack of a standard formula for calculating Cl. This study attempts to generate Cl of the mussel, Mytilus coruscus inhabiting along the coastal area of Chuja Island in Cheju using three primary formulas. the formulas used in this study: (1) Cl-vol= [tissue dry weight (g) 1000] /shell cavity volume (ml). (2) Cl-wt= [tissue dry weight (g) 1000] / internal shell cavity capacity (g). (3) Cl-size= tissue wet weight (g)/[shell length (mm)]$\^$3/. Monthly condition indices calculated with the three formulas are compared using ANOVA, Duncan's multiple range test and Pearson correlation coefficient. In Chuja Island M. coruscus collected ranged from 50 to 180 mm in shell length. Monthly ranges of Cl-values were 67.48 to 140.61 (Cl-vol), 74.67 to 118.02 (Cl-wt) and 1.4 10$\^$-5) to 1.6 10$\^$-5/ (Cl-size). Cl-vol values in August were higher than two Cl-values in the other months. Monthly Cl-vol was significantly different from Cl-wt and Cl-size. (p<0.05). The results of this study suggest that volumetric condition index (Cl-vol) used in this study is acceptable as a standard measure to evaluate conditions of M. coruscus.

• Industry Promotion Research
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• v.2 no.1
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• pp.39-44
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• 2017

The purpose of this study is to analyze the effect of the Naeil Chaeum deduction system on job satisfaction. The results of the study are summarized as follows. A total of 159 small to medium-sized enterprise workers participated in the deduction for Naeil Chaeum. The data were analyzed using SPSS Statistics 20, which included frequency analysis, factor analysis, reliability analysis, correlation analysis, regression analysis, and post analysis. First, the suitability of the method of the Naeil Chaeum deduction system has the highest positive effect on the job satisfaction. Second, the correlation of job satisfaction after filling in Naeil Chaeum deductions showed that fitness (p <.01, ${\beta}=.307$) and efficiency (p <.01, ${\beta}=.296$) had a significant effect on job satisfaction. Third, the analysis of the difference of job satisfaction according to the academic ability of the workers who were enrolled in Naeil Chaeum deduction system was analyzed that professional college graduates (2.08) were higher than job college graduates (1.99).The purpose of this study is to analyze the impact of the Fill - Down System on the job satisfaction by analyzing the importance of quality of life, job satisfaction, and muscle strength, analyzing the difference according to the demographic characteristics of the workers, And helping to stabilize the work life, and to verify the effectiveness of the study.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.4
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• pp.44-55
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• 2013

Intelligent transportation systems allow us to have valuable opportunities for collecting reliable wide-area coverage traffic and weather data. Significant efforts have been made in many countries to apply these data. This study identifies the critical points for classifying rain intensity by analyzing the relationship between rainfall and the amount of speed reduction. Then, traffic prediction performance by rain intensity level is evaluated using relative errors. The results show that critical points are 0.4mm/5min and 0.8mm/5min for classifying rain intensity (slight, moderate, and heavy rain). The best prediction performance is observable when previous five-block speed data is used as inputs under normal weather conditions. On the other hand, previous two or three-block speed data is used as inputs under rainy weather conditions. The outcomes of this study support the development of more reliable traffic information for providing advanced traffic information service.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.28-34
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• 2011

In previous reports, we investigated a selective assembly method of fabricating single-walled carbon nanotubes (SWCNTs) on a silicon-dioxide ($SiO_2$) surface by using only a photolithographic process. In this paper, we have fabricated field effect transistors (FETs) with SWCNT channels by using the technique mentioned above. Also, we have electrically measured gating effects of these FETs under different source-drain voltages ($V_{SD}$). These FETs have been fabricated for sensor applications. Photoresist (PR) patterns have been made on a $SiO_2$-grown silicon (Si) substrate by using a photolithographic process. This PR-patterned substrate have been dipped into a SWCNT solution dispersed in dichlorobenzene (DCB). These PR patterns have been removed by using aceton. As a result, a selectively-assembled SWCNT channels in FET arrays have been obtained between source and drain electrodes. Finally, we have successfully fabricated 4 FET arrays based on SWCNT-channels by using our simple self-assembly technique.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.4
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• pp.98-106
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• 2011

Since prediction processes such as motion estimation motion compensation are not at the WZ video encoder but at its decoder, WZ video compression cannot have better performance than that of conventional video encoder. In order to implement the prediction process with low complexity at the encoder, WZ residual coding was proposed. Instead of original WZ frames, WZ residual coding encodes the residual signal between key frames and WZ frames. Although the proposed WZ residual coding has good performance in pixel domain, it does not have any improvements in transform domain compared to transform domain WZ coding. The WZ residual coding in transform domain is difficult to have better performance, because pre-defined quantization matrices in WZ coding are not compatible with WZ residual coding. In this paper, we propose a new quantization method modifying quantization matrix and quantization step size adaptively for transform domain WZ residual coding. Experimental result shows 22% gain in BDBR and 1.2dB gain in BDPSNR.

• Clean Technology
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• v.23 no.3
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• pp.270-278
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• 2017

This study introduces a method to easily fabricate highly monodisperse pectin hydrogel microfibers in a microfluidic device by using partial gelation. The hydrodynamic parameters between the pectin aqueous solution and the calcium ions containing oil solution are precisely controlled to form a stable elongation flow of the pectin aqueous solution, and partial gelation of the pectin aqueous solution is performed by the chelating of the calcium ions at the interface between the two phases. The partially gelled pectin aqueous solution is phase-separated from the oil solution in an aqueous calcium chloride solution outside the microfluidic device and is completely gelled to produce monodisperse pectin hydrogel microfibers. The thickness of the pectin hydrogel microfiber is controlled in a reproducible manner by controlling the volumetric flow rate of the initially injected pectin aqueous solution. The pectin hydrogel microfibers were 200 to 500 micrometers in diameter and had a coefficient of variation below 5% under all thickness conditions, indicating that the pectin hydrogel microfibers produced by partial gelation are highly monodisperse. In addition, biomaterials can be immobilized to the pectin hydrogel microfibers produced by a single process, demonstrating the possibility that our pectin hydrogel microfiber can be used as carriers for biomaterials or tissue engineering.

• Journal of dental hygiene science
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• v.17 no.4
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• pp.275-282
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• 2017

The purpose of this study was to improve work performance conducted at an actual clinical site by determining the relationship among critical thinking disposition, problem solving ability, and work performance. In this study, 335 dental hygienists completed self-administered survey. Final analysis was conducted with a total of 331 responses, excluding 4 questionnaire with unreliable responses and non-responses. The results indicated that as the age, educational background, and work experience of the subjects increased, their critical thinking disposition and problem solving ability scores increased and were statistically significant. For work performance, average total score was high for age, educational background and work experience, but only age and work experience were statistically significant. Critical thinking disposition, problem solving ability and work performance of the subject were relevant, and all of them were significant. Work performance was also influenced indirectly by mediating problem solving ability in critical thinking disposition. In other words, both direct and indirect effects were significant, and the existence of partial moderating effect was verified. Thus, in order to improve work performance of dental hygienists, a multilevel educational process that can simultaneously improve critical thinking disposition and problem solving ability of dental hygienists needs to be developed. Therefore, it is expected that the new dental hygiene company will be able to perform without any sense of disparity in the clinical field; this will solve the gap between dental hygiene education and practical skills.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.12 no.1
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• pp.1-9
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• 2018

This study is intended to identify how horseback riding affect the bone density of the elderly. A total of 31 normal senior citizens participated in the research, who were randomly divided into two groups: 15 in horseback riding exercise group and 16 in horseback riding machine exercise group. A horseback riding exercise program was carried out for 25 minutes twice a week for 12 weeks. A pre-test was conducted before starting the program and two post-tests were conducted 6 weeks and 12 weeks after exercises in the same way as the pre-test. Measured items were bone density of lumbar vertebrae and femur. In order to identify the changes in measurement variables before exercises and 6 weeks and 12 weeks after exercises, two-way repeated analysis of variance were used. The comparison of changes in the bone density in both groups revealed that there were significant differences in lumbar vertebrae L3, L4, femur trochanter in both groups over time. This study suggests that three-dimensional movements of horses through horseback riding exercises induce normal movements of senior citizens, providing positive effects on their bone density. If appropriate horse riding exercise programs are used considering the health status, time and economic conditions, and preferences of senior citizens, it would improve their quality of life.

• Elastomers and Composites
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• v.52 no.2
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• pp.114-130
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• 2017

Enhancing the properties of rubber, such as the tensile strength, modulus, and wear abrasion, by the addition of carbon black and silica as fillers is very important for improving the performance of rubber products. In this review, we summarize the general features of 'the reinforcement of rubber by fillers' and the equations for representing the reinforcement phenomena. The rubber reinforcement was attributed to enhancement of the following: the rubber, bound rubber, formation of networks, and combination between rubber chains and silica followed by entanglement. The reinforcement capability of silica species with different surface and networked states demonstrated the importance of the connection between the silica particles and the rubber chains in achieving high reinforcement. The model involving combination followed by entanglement can provide a plausible explanation of the reinforcement of rubber by carbon black and silica because the combination facilitates the concentration of rubber chains near the filler particles, and entanglement of the rubber chains around the filler particles enforces the resistance against deformation and breakage of rubber compounds, resulting in high reinforcement.

• Korean Journal of Optics and Photonics
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• v.5 no.3
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• pp.423-430
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• 1994

We designed and fabricated the single mode fiber pigtailed DFB-LD module for 2.5 Gbps optical communication system. In the design of the DFB-LD module, we made the module divided into two parts of inner sub-module and outer 14-pin butterfly package and cylindrical shaped sub-module contain quasi confocal 2 lens system including optical isolator and electrical connection between these parts via hybrid substrate of bias T circuit. Laser welding was used to assemble the sub-module which requires accurate fixing between optical elements. The fabricated DFB-LD module showed optical coupling efficiency of 20% and - 3 dB small signal response of more than 2.6 GHz. We confirmed mechanical reliability of the module by temperature cycle test where the tested module exhibit optical power fluctuation of less than 10%. Finally we evaluated the performance of the fabricated DFB-LD module as light source of 2.5 Gbps optical communication system, sensitivity of - 30.2 dBm was obtained through 47 km optical fiber transmission under the criterion of $1\times10^{-10}$ BER and transmission penalties were 1.5 dB caused by extinction ratio and 1.0 dB caused by chromatic dispersion of normal single mode fiber. fiber.