• Journal of Korean Ophthalmic Optics Society
• /
• v.3 no.1
• /
• pp.75-86
• /
• 1998

The purpose of this study is to evaluate the effects of continuing work on VDT(video display terminal), therefore this study examined visual fatigue, unaided visual acuity, refractive error, accommodation and horizontal phoria of 152 subjects who did two hour long VDT work. For the ocular symptoms, the greatest number was tired eyes accounting for 45.71%. In the visual symptoms, blurred vision was the hightest rate of 80.39% and in case of systemic symptoms shoulder pain was 33.33% marked top ranking. The average of near visual acuity decresed almost 10% from 0.47 to 0.42, but refractive error increased about 0.10D to the direction of myopic shift. The amplitude of accommodation decreased approximately 0.72D from 7.46D to 6.74D. Accommodation facility was delayed from 2.27 second to 2.50 second, the amplitude of positive relative accommodation was decreased from 4.76D to 4.16D and the amplitude of negative relative accommodation was decreased from 2.46D to 2.33D. The horizontal phoria shifted to the direction of esophoria from $1.82{\Delta}$ to $3.24{\Delta}$.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.2
• /
• pp.255-261
• /
• 2015

Purpose: purchasing status and understanding trends of Functional progressive addtions lenses buyers', Correlation analysis of the Binocular Function value to determine ADD then can be apply sales and prescriptions. Methods: Years 2011 to 2014, 298 patients who were prescribed functional progressive lenses were analysed based on the prescription data and SPSS (Ver. 20.0) was treated using the statistics. Results: Results: The average age of our customers are $27.66{\pm}11.55$ years, average addition power is $+0.73{\pm}0.36D$, customers are using take a prescription of ADD $+0.75{\pm}0.28D$ was the highest 44.33% to 132 people. Near point of convergence of 276 people (92.62%) was mostly less than 10 cm, and near point of accommodation of 134 people (44.97%) was also below 10 cm, within 11~15 cm were 122 people (40.94%). Most of people were within normal range in terms of Near point of convergence and near point of accommodation, near point of accommodation tend to be longer than Near point of convergence. As you can see this result shows most of customers need extra help in their near point of accommodation instead of they are leak at it. FCC (Fused cross cylinder) check Value and ADD (addition power) tests showed that the value of a strong correlation (p=0.00), NPC and NPA were also p=0.001, the correlation of the NPC and ADD is p=0.003, In addition, NPA and ADD also showed a significant correlations (p=0.005). Near Point of Accommodation, negative relative accommodation, and positive relative accommodation are all significantly correlated (p=0.00). The short distance-related variables of the ADD which are NPC, NPA, Age, also appeared to side correlate significantly with each other. Conclusion: Binocular function values of the subjects were highly correlated with each other so precise examination is required. when Age young people are working at short distance, low ADD values was prescribed for solving discomfort. So, in the case of early presbyopia, accommodative insufficiency, or people feel fatigue when they often working at near although their accommodation function is normal, when functional progressive lenses are prescribed, expectation of this should be exactly notified.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.2
• /
• pp.219-228
• /
• 2015

Purpose: The current study was performed to compare the difference in binocular visual function depending on variable background colors at near work. Method: Fifty four adults (18 males, 34 females) who consented to the present study and had no ocular disease, ocular surgery history, strabismus and amblyopia with normal binocular vision were participated into this study. The subjects were asked to read the novels with black letter printed on white, red, green and blue background for 15 min. Then, their heterophoria, AC/A ratio, near point of convergence, accommodation facility, relative accommodation and vergence were measured before and after reading. The difference of measurements were compared. Result: Overall heterophoria was tended to decrease with regardless of background color. AC/A ratio showed a tendency of increase after reading the novels with all backgrounds except white background. Near point of convergence was significantly increased compared to before reading at all background color. Accommodative facility of dominant and non-dominant eyes were also significantly increased after reading however, binocular accommodative facility showed a tendency of decrease. Negative relative accommodation also decreased at all background colors however, the change of positive relative accommodation was not significantly different. In case of vergence, there was significant difference in break point of far BO and recovery point of far BI by the wavelength of background color. Conclusions: From the results, it was known there is convergence change depending on the wavelength of light even though same amount of accommodation and convergence is required when doing near work for certain period. Thus, it can be suggested that the adjustment of the near working environment which perception of various color was required, should be conducted according to the main wavelength.

• Journal of Korean Ophthalmic Optics Society
• /
• v.17 no.2
• /
• pp.177-184
• /
• 2012

Purpose: In this study, the effect of the eye movement direction on visual function related to accommodation was investigated when playing computer games for a certain period of time. Methods: Total 60 subjects in 20s who had the visual acuity of 1.0 or higher without any ocular disease and accommodative dysfunction were asked to play computer games separately in horizontal and vertical directions for 40 and 90 minutes and then measured their accommodative amplitude, accommodative facility, accommodative lag and relative accommodations. Thevisual function when not doing the computer game was regarded as a control value, and further compared and analyzed. Results: The accommodative amplitude, accommodative facility, accommodative lag and relative accommodations showed the tendency of decrease after the computer game for 40 minutes, and more reduced values of the visual functions were shown when the computer game extended up to 90 minutes except positive relative accommodation. Positive relative accommodation had a tendency to increase slightly after the computer game for 90 minutes. Meanwhile, the change of the visual functions was primarily influenced by the eye movement in horizontal direction rather than by the eye movement in vertical direction during computer game when analyzed by the direction of eye movement. Conclusions: Over all accommodative functions tended to decrease with the extended VDT working time by computer game, and the frequent eye movement in horizontal direction during VDT tasks could be the main cause of eyestrain since the eye movement in horizontal direction rather than vertical direction significantly affected the change of accommodative function.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.2
• /
• pp.195-200
• /
• 2015

Purpose: This study was performed in order to figure out the influence of illumination on visual function. Methods: 40 adults (male 21, female 19) of average age $23.93{\pm}1.59$ years were participated in this study. The test chart surface illumination was adjusted to 5, 50, 200, 500 and 800 lx, and then amplitude of accommodation, near point of convergence, far and near distance phoria, far and near distance fusional vergence, relative accommodation, and accommodation lag were measured at each illumination condition. Results: As illumination intensity of test chart was reduced, amplitude of accommodation was significantly decreased (p<0.05), accommodation lag was also decreased, near point of convergence was receded, and horizontal phoria showed a tendency of esodeviation. In the case of negative fusional vergence, with reduction of illumination intensity, the break point and the recovery point were decreased but in the case of positive fusional vergence, the break point was increased. The negative and positive relative accommodation were significantly decreased (p<0.05) with reduction of illumination intensity. Conclusions: In clinical practice, visual functional test should be performed under condition of adequate illumination level through patient's living environment and job.

• Journal of Institute of Control, Robotics and Systems
• /
• v.6 no.3
• /
• pp.298-308
• /
• 2000

In this paper a new two-arm cooperative assembly(or insertion) algorithm is proposed. As a force-guided control method for the cooperative assembly the adaptive accommodation controller is adopted since it does not require any complicated contact state analysis nor depends of the geometrical complexity of the assembly parts. Also the RMRC(resolved motion rate control) method using a relative jacobian is used to solve inverse kinematics for two manipulators. By using the relative jacobian the two cooperative redundant manipulators can be formed as a new single redundant manipulator. Two arms can perform a variety of insertion tasks by using a relative motion between their end effectors. A force/torque sensing model using an approximated penetration depth calculation a, is developed and used to compute a contact force/torque in the graphic assembly simulation . By using the adaptive accommodation controller and the force/torque sensing model both planar and a spatial cooperative assembly tasks have been successfully executed in the graphic simulation. Finally through a cooperative assembly task experiment using a humanoid robot CENTAUR which inserts a spatially bent pin into a hole its feasibility and applicability of the proposed algorithm verified.

• Journal of Agricultural Extension & Community Development
• /
• v.27 no.3
• /
• pp.135-144
• /
• 2020

The aim of this study is to analyze the factors affecting rural tourists' expenditure. This study used the data from the fact-finding survey on rural tourism, and analyzed 4,223 cases who had experienced rural tourism for one year in 2018. The linear multiple regression analysis were used to identify factors affecting rural tourists' expenditure. The result indicate that the factors influencing the rural tourists' total expenditure were age, monthly income, number of accompany, length of stay, accommodation type(pension), accommodation type(friend's house/relatives'house), accommodation type(camping), distance to the destination, accompany(family/relatives), accompany(solo traveler), occupation(white color), motivation(daily escape and rest), motivation(new experience). The result indicate that the higher the age, the higher the average monthly income of the household, the fewer companions, the longer the length of stay higher the expenditure. As for the accommodation, the pension, motel/inn, hotel/condominium, and recreational forest higher probability of expenditure, while, friend/relative's house or camping higher the probability of less expenditure. The longer the distance to the destination, the solo traveler higher the probability of expenditure in rural tourism.

• Journal of Korean Ophthalmic Optics Society
• /
• v.15 no.3
• /
• pp.287-291
• /
• 2010

Purpose: The aim of this study was to compare binocular functions such as near point of convergence (NPC), AC/A ratios, heterophoria, accommodation, accommodation lag, positive relative accommodation (PRA), negative relative accommodation (NRA), positive relative convergence (PRC), negative relative convergence (NRC) in normal subjects and convergence insufficiency. Methods: 86 subject (male n=45, female n=41, mean $age{\pm}SD=23.27{\pm}2.85$ years) without amblyopia, strabismus, and ocular pathology were studied. Forty three patients each group were classified as normal subjects and convergence insufficiency group based on AC/A ratio and far and near phoria. Binocular function of the two groups was measured using phoropter. r. Results: The values between normal subjects and convergence insufficiency were 5.71 cm and 7.07 cm for NPC, 5.28 and 2.81 for Heterophria AC/A, 0.92 exo/3.36 exo and 2.17 exo/10.84 exo for far and near phoria, 15.49/23.30/13.30 and 13.50/20.02/9.09 for PRC, respectively. However, there were no significant differences between normal subjects and convergence insufficiency for accommodative amplitude, accommodative lag, PRA, NRA, BI vergence test, BO vergence test, NRC. Conclusions: Both groups were a significant difference for cover test, NPC, Heterophria AC/A, far and near phoria, break point of PRC, and recovery point of PRC.

• Journal of Korean Ophthalmic Optics Society
• /
• v.13 no.4
• /
• pp.127-134
• /
• 2008

Purpose: The purpose of this study was to determine the expected values of accommodation and vergence system for analysis of binocular vision. Methods: Seventy three healty subjects without past history of eye disease were selected for this study, Patients showing clinical binocular anomalies including manifest squint and intermittent heterotropia were excluded and data was collected on 54 patients(mean age, 25.3${\pm}$2.7 year). Near point of convergence, distance and near phoiras were measured based on objective deviation angle. And then AC/ A ratio, relative accommodation were measured and all of the data were compared with the Morgan's expected values. Results: The values of distance and near heterophoria were 1.24${\pm}$2.72${\Delta}$ and 2.70${\pm}$4.91${\Delta}$ respectively and the gradient AC/A ratio was 3.92${\pm}$2.17${\Delta}$/D which were all about the same compared with the Morgan's expected values. The values of distance negative fusional convergence was same, however, distance positive fusional convergence was 7${\Delta}$ greater than the Morgan's one. There were no significant differences in the range values of both near vergences while the range of distance vergence was relatively larger than the Morgan's one. Positive relative accommodation was +0.37D greater and negative relative accommodation was -0.63D greater than the Morgan's values. Conclusions: The findings in this study appear that the Morgan's expected values have a possibilities of including considerable proximal convergence value. In comparison with Morgan's values, Korean's normal expected values have much different values of especially BO limit, so if the Morgan's values are directly applied to binocular vision analysis for Korean people, it may lead to an inaccurate binocular vision diagnosis. This results can be used to diagnose the accommodation and vergence system of Korean normal young adults.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.2
• /
• pp.253-260
• /
• 2014

Purpose: The present study was conducted to investigate whether near work with smartphone could induce the change of accommodative function. Methods: Total 63 subjects(26 male and 37 female) in their 20s were firstly examined their visual functions related to accommodation and uncorrected spherical equivalent power as the control. After that, the subjects were asked to read a book for 30 min and sequentially watch a movie on smartphone for the same time after 30 min-break under the indoor light or as it was in the reverse order to avoid time-ordered effect. Their accommodative functions, 1) accommodative amplitude, 2) accommodative facility, 3) relative positive/negative accommodation, and 4) accommodative lag and their uncorrected spherical equivalent power were examined again following each task and compared with the control values. Results: The monocular accommodative amplitude was significantly decreased after smartphone watching compared with it after reading. The monocular and binocular accommodative facilities were tended to reduce after smartphone watching and book reading but were not significantly different. Neither significant change in positive relative accommodation was determined after smartphone watching nor book reading. Negative relative accommodation after smartphone watching was almost unchanged unlike reading a book. The accommodative lag after smartphone work was significantly higher than after book reading. Conclusions: The near work with a smartphone for 30 min induced the change of some accommodative functions, which was significantly greater than when reading under the same working environment.