• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.9-17
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• 2018

For Earth observation, a small satellite camera has relatively weak structural stability compared to medium-sized satellite, resulting in misalignment of optical components due to severe launching and space environments. These alignment errors can deteriorate the optical performance of satellite cameras. In this study, we proposed a 3-axis focus mechanism to compensate misalignment in a small satellite camera. This mechanism consists of three piezo-electric actuators to perform x-axis and y-axis tilt with de-space compensation. Design requirements for the focus mechanism were derived from the design of the Schmidt-Cassegrain target optical system. To compensate the misalignment of the secondary mirror (M2), the focus mechanism was installed just behind the M2 to control the 3-axis movement of M2. In this case, flexure design with Box-Behnken test plan was used to minimize optical degradation due to wave front error. The wave front error was analyzed using ANSYS. The fabricated focus mechanism demonstrated excellent servo performance in experiments with PID servo control.

• Journal of Digital Contents Society
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• v.11 no.2
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• pp.195-201
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• 2010

Globalization, conversions, and OSMU (One Source Multi Use) in modern cultural industry is expanding fast, and global competition is soaring with a changing environment today. In fact, the development of one nation depends on its cultural creativity. Yet, there is an increasing need for a connection between space and culture since globalization homogenizes a nation's unique cultural identity and provides low level of utilization in digital cultural contents in terms of saving, conserving and maintaining data. In order to invigorate the cultural industry, there must be some information that provides public culture contents, which they can be freely searched, displayed, and re-produced. Ultimately, these public culture contents should be able to provide Culture Space. This text discusses how individuals produce the Culture Space, which provides digital information of time and space, from a relationship between culture and space. It also introduces the public Culture Contents service framework in order to provide culture information and combined Culture Contents.

• Analytical Science and Technology
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• v.7 no.3
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• pp.285-291
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• 1994

A microbial BOD sensor for the continuous estimation of BOD was been developed by immobilizing Trichosporon cutaneum, which was immobilized between a dialysis and a gas-permeable membrane, on an oxygen electrode. The optimum pH and temperature for BOD measurement using this sensor were pH 7.0 and $32{\sim}33^{\circ}C$, respectively. The best result was obtained at 2~3ml/min flow rate in 0.1M phosphate buffer solution. A linear relationship was observed between ${\Delta}DO$ and the concentration of standard GGA solution below 60mg/l(90ppm $BOD_5$). The reproducibility was found to be within 3% for the standard solution containing glucose 30mg/l and glutamic acid 30mg/l. The output DO value of this sensor was almost constant for 30 dalys. The response time and the recovery time were about 5 and 10 min, respectively. This sensor was employed for the BOD measurement of waste pollutants and was compared with $BOD_5$ method.

• Fire Science and Engineering
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• v.24 no.2
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• pp.126-132
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• 2010

The Housing Performance Rating System, enacted on 9 January 2006, an active measure containing provisions on improved quality and advanced performance of the Fire-Protection System for equalized ability to secure safety of life to some extent, is a desirable policy in fire-safety regard. The study of theoretical background of each performance rating section for the purpose of active and wide application of The Fire-Protection System category of the Housing Performance Rating System currently in effect internally. In accordance with the result of the study, the reform measures for the currently detailed evaluation criteria have been suggested to improve the performance of the Fire-Protection area of The Housing Performance Rating System currently being in force based on the assumption of prior settlement of the following; upward settlement of the point distribution standards on the performance ratings of each head backed up by an institutional Government policy with overriding priority; and urgently enacted Fire-Protection related laws and regulations.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.957-960
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• 2008

The purpose of this study is to explore a safe, advanced, and environment-friendly demolition equipments and their operation methods. As an initial achievement, the capacity of the existing equipments have been evaluated through technical discussions and demonstrations with some experts in the related industry. From these evaluations, it was concluded that a haptic based remote control with force feed-back mechanism and sensor fusion functions would be the most appropriate to the demolition equipments. Therefore, a novel haptic device that is adequately designed for the demolition equipments is proposed in this paper. Top-down demolition method is also proposed, which is very effective in the demolition of high-rise buildings.

• Journal of Korea Game Society
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• v.18 no.5
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• pp.103-112
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• 2018

"Ito2", an early childhood educational coding game that allows students to learn sequential, loop, and conditional statement concepts through games is introduced. The developed game is a two-stage process of mock and practical classes for children in actual nursing cares, and coding education is conducted for actual children to determine its effectiveness. The degree of change is observed by observing trends in childhood cognitive development performance in all six areas, including parts and the overall, space, observation, shape and measurement, classification, comparison, and listing, as the coding training is conducted. In this paper, the improvement of cognitive development and spatial perceptual abilities were achieved by children playing games with infant functional coding with fun elements plus learning factors.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.24-30
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• 2018

Dental implants are currently widely used as artificial teeth due to their good chewing performance and long life cycle. A dental implant consists of an abutment as the upper part and a fixture as the lower part. When chewing forces are repeatedly applied to a dental implant, gap at the interface surface between the abutment and the fixture is often occurred, and results in some deteriorations such as loosening of fastening screw, dental retraction and fixture fracture. To cope with such problems, a sealing-type abutment having a number of grooves along the conical-surface circumference was previously developed, and shows better sealing performance than the conventional one. This study carries out optimization of the groove shape by genetic algorithm(GA) as well as structural analysis in consideration of external chewing force and pretension between the abutment and the fixture. The overall optimization system consists of two subsystems; the one is the genetic algorithm with MATLAB, and the other is the structural analysis with ANSYS. Two subsystems transmit and receive the relevant data with each other throughout the optimization processes. The optimization result is then compared with that of the conventional one with respect to the contact pressure and the maximum stress. The result shows that the optimized model gives better sealing performance than the conventional sealing abutment.

• Journal of the Korea Institute of Building Construction
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• v.22 no.1
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• pp.23-34
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• 2022

The purpose of this study is to evaluate the adhesion properties of polymer cement composites for crack repair of an RC structure. Polymer cement composites are manufactured from cement, three types of polymers and silica fume, and the mixture is designed by adjusting the water cement ratio and AE reducing agent so that the viscosity target of the polymer cement composites is 700mPa·s or less. According to the test results, the Type-A adhesion in tension of the polymer cement composite exceeded the adhesion standard of 1.0MPa of the polymer finishing material, and furthermore, depending on the type of polymer, the adhesion in tension was highest for SAE, followed in descending order by EVA, and SBR. In addition, the adhesion in tension of Type-B is up to 1/4.5 lower than that of Type-A, but the incorporation of silica fume shows a significant improvement in terms of adhesion in tension. Based on this study, the basic mixing design of the polymer cement composites required for viscosity and adhesive performance required for crack repair of the RC structure was completed. It could be proposed as an optimal mixing design under conditions for intermixing polymer type EVA, SAE, and P/C 80%-100%.

• Journal of agricultural medicine and community health
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• v.21 no.2
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• pp.173-193
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• 1996

This study was carried out to elucidate the causes of farmer's disease and greenhouse disease in the rural area of Kyungnam province during 1996. 2,171 (69.1%) of the 3,140 adults above 20 years old who had lived in the selected 20 villages in Uiryong County of Kyungnam Province were selected in order to over both residents who live in the green house distracts and conventional rural area. The results were as follows: 1. Among the subjects, the male was 42.2% and female was 57.6%. The average age for the male was 52.3, 55.6 for the female. 2. The proportion of the farmers in the subjects was 81.5%. Among these 78.0% were engaged in the greenhouse farming. 3. Among the eight symptoms of Nofusho(japanese farmer's comples), lumbago was the most frequently complained and followed by shoulder stiffness and parenthesis of hand or foot. 4. The total score of farmer's disease was evidently higher in the female and the older the score was clearly bigger. 5. The prevalence of Nofusho(Japanese farmer's comples)was 26.8% and 43.15% was for the suspected Nofusho. In the male, the prevalence of Nofusho was 13.6% and 40.9% for the suspected Nofusho and in the female 36.5% and 44.7% were shown, comparatively. 6. According to the multiple classification analysis, sex, age, and occupation were selected as significant variables to explain the total score of Nofusho. 7. The correlations between the total score of Nofusho and the number of sick day, working years, and age were significant, comparatively. 8. According to the multiple classification analysis corolling interaction between independent variables, age was the only variable which was significant in the male and age, pesticide work in the female. 9. The score of greenhouse disease was highest in the group who engaged in greenhouse farming and conventional farming(2.76 for male, 3.77 for female) followed by the group who engaged only in greening house farming(2.66 for male, 3.49 for female) and by the group who engaged only in conventional farming(2.27 for male, 3.05 for female) 10. According to the multiple classification analysis with the total score of greenhouse disease as dependent variable, corolling interaction between independent variables, age and pesticide work were revealed as significant variables in the male, while, pesticide work and farming type were significant in the female. According to the above results, the following could be suggested. Because lumbago, shoulder stiffness, paresthesia of hand and foot were the most frequently complained symptoms in the respondent, the development of farming tool to reduce the body burden and periodical physical exercise and rest is highly recommended. It is revealed that both in the farmer' disease and greenhouse disease the score was higher in the female than in the male. So the reasonables measures is recommended to reduce the working hours of the female. Pesticide work was revealed as the significant variable in the female in farmer's disease and both in the male and the female in greenhouse disease. So the development of the safe method of pesticide spraying including safety education should be introduced. Particularly the female should be excluded in pesticide spraying.

• Journal of Preventive Medicine and Public Health
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• v.29 no.2 s.53
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• pp.173-186
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• 1996

This is a cross-sectional study to evaluate the relationships between physical fitness, leisure time physical activity, and serum lipid levels in middle-aged male workers. Physical fitness was measured by a step test score, and leisure time physical activity was self-reported on a questionnaire. Serum total cholesterol was negatively related to physical fitness(r=-0.27), and positively to obesity index(r=0.27). But leisure time physical activity was related to total cholesterol negatively(r=-0.20) only in subjects whose total cholesterol levels were above 170mg/dl. High density lipoprotein(HDL) cholesterol was positively related to physical fitness(r=0.15), negatively to obestiy index(r=-0.22), and positively to weekly alcohol consumption(r=0.14). Total cholesterol/HDL cholesterol ratio was related to physical fitness(r=-0.23), obesity index(r=0.32), total cigarette index (r=0.13), weekly alcohol consumption(r=-0.13), and vegetable preference(r=0.13). Physical fitness was also related to leisure time physical activity(r=0.19) and obesity index(r=-0.18). In multiple linear regression models, physical fitness(beta=-0.23) and obesity index(beta=0.18) were significantly associated with total cholesterol, obesity index(beta=-0.25) with HDLcholesterol, and obesity index(beta=0.30), physical fitness(beta=-0.16) and vegetable preference (beta=0.14) with total cholesterol/HDL cholesterol ratio. In conclusion, as physical fitness has a stronger relationship with serum lipid levels than leisure time physical activity, and the association between physical fitness and leisure time physical activity is modest, physical fitness should be added as an important variable in addition to activity in future epidemiologic studies.