• Korean Journal of Health Education and Promotion
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• v.11 no.2
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• pp.87-106
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• 1994

Owing to the use of many cultural facilities, the elevation of life standards and the high level progress of industry, visual impairment was on increasing trends. Especially due to studying for many hours, the myopia of adolescents became a serious social issue. The purpose of this study was to understand adolescent's wearing glasses and eyesight condition, whether the primary myopia factor and the subjective symptoms were different between the myopia group and the normal group, between the wearing glasses group and the non-wearing glasses group, and the effect on physical, mental and study activity of myopia. The subject of investigation was 627 middle school students in Seoul and the investigation was accomplished from July 7th, 1993 to July 12th, 1993. The data were analyzed by the percentage, x²-test, t-test and ANOVA of SPSS. The results were as followed; 1. The rate of the right and left eyesights higher than 0.8 in the normal group was 47.0%, and those less than 0.7 in the myopia group was 53.0%. In the boy students, the normal group was 54.1%, the myopia group was 45.9%. In the girl students, the normal group was 39.2%, the myopia group was 60.8%. Therefore the girl students' myopia rates were higher than the boy students', and this result was significant(p<0.01). 2. The rate of wearing glasses of the middle school students was 44.6%. The rate of wearing glasses of the girl students was 56.8%. The rate of wearing glasses of the girl students was higher than that of the boy students 43.2%. The rate of necessary glasses of the middle school students was 6.1% and the rate of necessary glasses of the boy students was 7.9%, the rate of necessary glasses of the girl students was 4.1%. 3. In case of a family member of the student wear glasses, the rate of wearing glasses was higher. 4. In the myopia group, the main reason for not wearing glasses was "Uncomfortable"(63.3% in the boy students, 40% in the girl students). In case of the girl students, "Nonpermission of their parents" was 18.7% and remarkably higher than 5.1% in case of the boy students. 5. The factor of myopia was that "The bad attitude of watching TV closely" was 19.9%, that "The dimly-lit room" was 6.6%. 6. In order to protect eyesight, the rate of the students who practiced "Looking at something from afar 3∼4times a day" was 37.3%, the rate of the students who did "Eye exercise" was 17.5%, the rate of the students who took "A medicine for promoting nutrition" was 12.9%. The rate of taking the medicine was higher than 3.5% in the normal eyesight group. 7. After near working, the point of subjective symptoms was higher in the myopia group than in the normal group and in the wearing glasses group than in the unwearing group and in the girl students than in the boy students. 8. The longer time to watch TV, the higher point of subjective symptoms. The longer distance to watch TV, the lower point of subjective symptoms(p<0.05).

• Journal of Korean society of Dental Hygiene
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• v.11 no.2
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• pp.213-222
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• 2011

Objectives : The purpose of this study is to arrange basic data necessary for education of AIDS and to prevent AIDS on undergraduates' knowledge or attitude toward AIDS. Methods : A self-administered questionnaire survey was used among 350 undergraduates in some of Jeonbuk and Gyeongnam area from September 9, 2009 to December 10, 2009 and then obtained the following results. Results : 1. Information route on AIDS was indicated to be higher in order of school education with 37.1% and TV & newspaper with 31.5% as for the health-related department. The health-unrelated department was indicated to be the highest in TV & newspaper with 67 people(43.8%), and had statistically significant difference(p<0.01). 2. The whole knowledge score on AIDS was indicated to be $12.72{\pm}2.67$ for the health-related department, resulting having been higher than the health-unrelated department with $11.84{\pm}3.30$. There was significant difference(p<0.01). The attitude score on AIDS was indicated to be $4.85{\pm}1.67$ for the health-related department, resulting having been higher than the health-unrelated department with $4.38{\pm}1.58$. There was significant difference(p<0.01). 3. Knowledge and attitude toward general AIDS stood at r=.112(p<0.05), thereby having had positive correlation. Knowledge and attitude toward AIDS infection stood at r=-.220(p<0.01), thereby having had negative correlation. Relationship between the whole knowledge and attitude toward AIDS stood at r=-.105(p<0.05), thereby having had negative correlation. Conclusions : AIDS is exponentially increasing in the whole world and is getting more serious. Even in our country, it is the tendency that the infected are gradually increasing. Health care of AIDS, which is impossible to be fully recovered and has no vaccine, is preferential to prevent infection. A continuous and efficient preventive education program is thought to be necessary for straightening wrong knowledge and prejudice on this by grasping right knowledge and attitude toward AIDS.

• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.29-32
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• 2007

Zinc gallate, $ZnGa_2O_4:Mn^{2+}$ co-doped with different concentrations of $Mg^{2+}$ (0.001- 0.5 mol%) was prepared by solid state synthesis method. These compositions were investigated for their photoluminescence and cathodoluminescence properties. The optimized composition $Zn_{0.990}Mg_{0.005}Ga_2O_4:Mn_{0.005}$ shows higher luminescence intensity compared to the parent phosphor. The intense green emission peak was found at 504 nm. The $Mg^{2+}$ doping does not affect much the decay time. It remains <10 ms for these compositions which make them potential candidate for application in TV screens.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.443-451
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• 2010

This paper describes a fully integrated CMOS low-IF mobile-TV RF tuner for Band-III T-DMB/DAB applications. All functional blocks such as low noise amplifier, mixers, variable gain amplifiers, channel filter, phase locked loop, voltage controlled oscillator and PLL loop filter are integrated. The gain of LNA can be controlled from -10 dB to +15 dB with 4-step resolutions. This provides a high signal-to-noise ratio and high linearity performance at a certain power level of RF input because LNA has a small gain variance. For further improving the linearity and noise performance we have proposed the RF VGA exploiting Schmoock's technique and the mixer with current bleeding, which injects directly the charges to the transconductance stage. The chip is fabricated in a 0.18 um mixed signal CMOS process. The measured gain range of the receiver is -25~+88 dB, the overall noise figure(NF) is 4.02~5.13 dB over the whole T-DMB band of 174~240 MHz, and the measured IIP3 is +2.3 dBm at low gain mode. The tuner rejects the image signal over maximum 63.4 dB. The power consumption is 54 mW at 1.8 V supply voltage. The chip area is $3.0{\times}2.5mm^2$.

• Journal of Preventive Medicine and Public Health
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• v.25 no.3 s.39
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• pp.247-268
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• 1992

This study was conducted to evaluate the effect of VDT work on eyes and vision among workers in a TV manufacturing plant. The study subjects consisted of 264 screen workers and 74 non-screen workers who were less than 40 years old male and had no history of opthalmic diseases such as corneal opacities, trauma, keratitis, etc and whose visual acuity on pre-employment health examination by Han's test chart was 1.0 or above. The screen workers were divided into two groups by actual time for screen work in a day : Group I, 60 workers, lesser than 4 hours a day and group II, 204 workers, more than 4 hours a day. From July to October 1992 a questionnaire was administered to all the study subjects for the general charateristics and subjective eye symptoms after which the opthalmologic tests such as visual acuity, spherical equivalent, lacrimal function, ocular pressure, slit lamp test, fundoscopy were conducted by one opthalmologist. The proportion of workers whose present visual acuity was decreased more than 0.15 in comparison with that on the pre-employment health examination by Han's test chart was 20.6% in Group II. 15.0% in Group I and 14.9% in non-screen workers. However, the differences in proportion were not statistically significant. The proportion of workers with decreased visual acuity was not associated with the age, working duration, use of magnifying glass and type of shift work (independent variables) in all of the three groups. However, screen workers working under poor illumination had a higher proportion of persons with decreased visual acuity than those working under adequate illumination (P<0.05) . The proportion of workers whose near vision was decreased was 27.5% in Group II, 18.3% in Group I, and 28.4% in non-screen workers and these differences in proportion were not statistically significant. Changes of near vision were not associated with 4 independent variables in all of the three groups. Six out of seven subjective eye symptoms except tearing were more common in Group I than in non-screen workers and more common in Group II than in Group I (P<0.01). Mean of the total scores for seven subjective symptoms of each worker(2 points for always, 1 point for sometimes, 0 point for never) was not significantly different between workers with decreased visual acuity and workers with no vision change. However, mean of the total scores for Group II was higher than those for the Group I and non-screen workers (P<0.01). Total eye symptom scores were significantly correlated with the grade of screen work, use of magnifying glass, and type of shift work. There was no independent variable which was correlated with the difference in visual acuity between the pre-employment health examination and the present state, the difference between far and near visions, lacrimal function, ocular pressure, and spherical equivalent. Multiple linear regression analysis for the subjective eye symptom scores revealed a positive linear relationship with actual time for screen work and shift work(P<0.01). In this study it was not observed that the VDT work decreased visual acuity but it induces subjective eye symptoms such as eye fatigue, blurred vision, ocular discomfort, etc. Maintenance of adequate illumination in the work place and control of excessive VDT work are recommended to prevent such eye symptoms.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.6
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• pp.543-547
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• 1990

Diurnal courses of $CO_2$ concentration and air temperature in the rice seedbed tunnel covered with polyethylene film, subjected to three different ventilation methods, were traced. Regaredless of ventilation methods, $CO_2$ concentrations in the tunnel on a clear day were lower than that in ambient air, and vice versa before dawn. $CO_2$ concentration during the day was lowest in the tunnel with non-ventilation (NV), followed by horizontal slit ventilation (HSV) and traditional one(TN), reaching down to the lowest level of 58ppm, 155ppm and 272ppm, respectively. Air temperature in the tunnel reached 46$^{\circ}C$ in NV, 37$^{\circ}C$ in HSV and 32$^{\circ}C$ in TV at the daytime when ambient air temperature was 22$^{\circ}C$. Even at night time of ambient air temperature below 15$^{\circ}C$, HSV was more effective than TV in raising the air temperature in the tunnel. The dry weight of 40-day old seedling weighed heaviest in HSV, followed by TV and NV.

• Imaging Science in Dentistry
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• v.52 no.2
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• pp.171-179
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• 2022

Purpose: The aim of this study was to assess the accuracy of cone-beam computed tomographic (CBCT) images obtained using different voxel sizes in measuring trabecular bone microstructure in comparison to micro-CT. Materials and Methods: Twelve human skull bones containing posterior-mandibular alveolar bone regions were analyzed. CBCT images were obtained at voxel sizes of 0.075mm(high: HI) and 0.2mm(standard: Std), while microCT imaging used voxel sizes of 0.06 mm (HI) and 0.12 mm (Std). Analyses were performed using CTAn software with the standardized automatic global threshold method. Intraclass correlation coefficients were used to evaluate the consistency and agreement of paired measurements for bone volume (BV), percent bone volume (BV/TV), bone surface (BS), trabecular thickness (TbTh), trabecular separation (TbSp), trabecular number (TbN), trabecular pattern factor(TbPf), and structure model index (SMI). Results: When compared to micro-CT, CBCT images had higher BV, BV/TV, and TbTh values, while micro-CT images had lower BS, TbSp, TbN, TbPf, and SMI values (P<0.05). The BV, BV/BT, TbTh, and TbSp variables were higher with Std voxels, whereas the BS, TbPf, and SMI variables were higher with HI voxels for both imaging methods. For each imaging modality and voxel size evaluated, BV, BS, and TbTh were significantly different(P<0.05). TbN, TbPf, and SMI showed statistically significant differences between imaging methods(P<0.05). The consistency and absolute agreement between micro-CT and CBCT were excellent for all variables. Conclusion: This study demonstrated the potential of high-resolution CBCT imaging for quantitative bone morphometry assessment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.4
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• pp.251-258
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• 1986

There is much redundancy in image data such as TV signals and many techniques to redice it have been studied. In this paper, Hadamard transform is studied through computer simulation and experimental model. Each element of hadamard matrix is either +1 or -1, and the row vectors are orthogonal to another. Its hardware implementation is the simplest of the usual orthogonal transforms because addition and sulbraction are necessary to calculate transformed signals, while not only addition but multiplication are necessary in digital Fourier transform, etc. Linclon data (64$ imes$64) are simulated using 8th-order and 16th-order Hadamard transform, and 8th-order is implemented to hardware. Theoretical calculation and experimental result of 8th-order show that 2.0 bits/sample are required for good quality.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.862-865
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• 2011

WebGL is a cross-platform web standard for a low-level 3D graphics API based on OpenGL ES 2.0 and presents 3D graphics in web browsers without installing extra plug-ins. The reason that WebGL is notable is because it is included in the HTML5 standard which is getting the spotlight as a next-generation RIA(Rich Internet Application) platform for variable devices such as PCs, smart phones, table PCs, and smart TVs. In this research, we would like to introduce and develop a behavior engine for easy and rapid authoring of complicated interactions and 3D object's behavior models in WebGL-based contents.

• Korean Journal of Health Education and Promotion
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• v.17 no.2
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• pp.151-163
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• 2000

Adopting the theory of enter-educate, this study was conducted to prevent the smoking by middle school students who had not started smoking yet. A famous pop music singer with high popularity among teenagers was cast on the public sponsored advertisement (PSA) on smoking prevention. This PSA was televised through major TV stations for two months. The effectiveness of this project was evaluated seven times. The effectiveness of the PSA, the role of the cast singer, the rate of seeing the PSA, and the impression about the PSA were evaluated. The viewer survey since the second period of the PSA revealed that most of the middle school students (79~94 percent) watched it. Among TV stations, MBC recorded the highest viewer rate as 69.6~72.0 percent of the middle school students watched the PSA at least once from this station. Also, the viewer rates of such cable TV stations as Mnet and OCN were quite high for their advertisement prices. The overall impression about the PSA was favorable. The contribution of the singer to this positive outcome was 60 percent and over. The effect of smoking prevention was also high as 93.7 percent of the middle school students replied that they would not start smoking. However, since this study dealt with the general public, it was not possible to control the effect of other factors systematically. Also, we could not measure the differences bewteen the pre-PSA and the post-PSA periods, so that the interpretation of the results has some limitation.