• Journal of Korean Ophthalmic Optics Society
• /
• v.6 no.2
• /
• pp.115-119
• /
• 2001

To research the refractive error of the eyes on the 30's employees, 510 eyes were tested by the object and subject methods. The results were as follows. 1. Among the 510 eyes, myopia is 74.4%, hyperopia is 0.9% and emmetropia is 24.7%, respectively. 2. In test, the low myopia (-0.50Dt < Spherical Equivalent ${\leq}$ -2.00Dt) is 24.1%, the middle myopia(-2.00Dt < Spherical Equivalent ${\leq}$ -6.00Dt) is 51.4%, the high myopia(-6.00Dt < Spherical Equivalent) is 14.8% and the low hyperopia(+0.50Dt < Spherical Equivalent ${\leq}$ +2.00Dt) is 1.2%, respectively. 3. In test of astigmatism, the amount of astigmatism with-the rule is 58.5%, the amount of astigmatism against-the rule is 22.6% and the amount of astigmatism with oblique is 18.9%, respectively.

• Journal of Korean Ophthalmic Optics Society
• /
• v.14 no.4
• /
• pp.89-96
• /
• 2009

Purpose: This study was to investigate and analyze understanding and knowledge of the eye in biological science education for middle and high school students in Busan. Methods: A total of 821 middle and high school students from four different schools participated by self-administered questionnaire test. The results were compared and analyzed by grade and gender. Results: In the survey of the understanding about the eye in the biological science curriculum, the results indicated that the more learning of the eye in biological science lecture led to the more understanding of the role of the eye. The difference of understanding the eye between learned and unlearned students in biological sciences lecture was significant (p<0.01). In the survey of the knowledge of the eye, students did not know about myopia and astigmatism (average value <50). Conclusions: As biological science education is one of the major factors to understand the role of the eye, this result suggests that more information about the eye in the curriculum of biology is included.

• Journal of Korean Ophthalmic Optics Society
• /
• v.8 no.1
• /
• pp.41-45
• /
• 2003

The researchers have studied on the effect of three main morphological types(nuclear, cortical, and subcapsular cataract) of age related cataract on refractive error. We also identified that spherical and cylinderical shift in each type of morphological cataract accoding to their locations and effect of intraocular pressure before and after cataract surgery. Nuclear cataract showed myopic shift while cortical cataract showed hyperopic shift, and subcapsular cataract showed not significant changes on both direction. Age related cataract subjects(120 eyes) only were recruited from sun-cheon area. We use optic section of slit lamp biomicroscope to identify the anatomical location of cataract, and optimal refractive correction determined by objective(retinoscope) and subjective refraction then spherical changes were calculated from the spherical eqivalent value. Intra-ocular pressure were measured by auto-tonometer before and 7 days after cataract has been replaced by IOL. The change in cylindrical power, usually A-P diameter decreased according to increases of age, A-P diameter increased because intra-ocular pressure rises by progression of cataract and this convertion with the rule astigmatism to against the rule astigmatism and this increases more by intra-ocular pressure.

• Explosives and Blasting
• /
• v.25 no.2
• /
• pp.47-60
• /
• 2007

The blast demolition technology has been used to demolish various industrial facilities and tall buildings since 1950s in the advanced countries such as USA and U.K. It is now considered as one of safe demolition methods in the above countries. In Korea, several companies have tried to introduce blast demolition technology in the early days of the 1990s. However, this technology is still at the beginning stage and not fully adopted due to situation of avoiding technology transfer by overseas technical tie-up companies, lack of objects to be demolished and low level recognition on blast demolition. This technology shall be considered as a cutting edge technology to be applicable to demolition of skyscrapers, various industrial structures and factory buildings in the near future. Blast demolition of a pier structure was carried out under the site condition where there were already the constructed 2 pier structures of up and down line which had safety problems in an expressway construction project. The pier structures need to be demolished and reconstructed for a short period of time in consideration of the construction work process to be followed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.4
• /
• pp.453-461
• /
• 2011

In order to use more efficiently limited frequency resources at the broadcasting band and to eliminate blanket area of the terrestrial broadcasting and to improve broadcasting quality. The importance of repeaters has increasing continuously. However, in case of T-DMB digital on channel repeater in OFDM systems, some of the signal radiated feedback again at the receiver antenna. So it generates feedback signal interference in repeater system. Also phase noise increases ICI(Inter Carrier Interference). It affects seriously the frequency domain equalizer. In this paper, we remove the feedback signal interference by LMS with correlation. Also we propose an effective equalizer algorithm that can remove ICI caused by phase noise and the power amplifier's back-off. In this simulation results, this system is satisfied the performance of BER=$10^{-4}$ at less than SNR=14 dB after compensation of phase noise.

• Journal of Korean Ophthalmic Optics Society
• /
• v.17 no.4
• /
• pp.469-476
• /
• 2012

Purpose: The purpose of this study is to investigate the changes of asphericity according to diameter and direction of the cornea. Methods: The changes of asphericity according to diameter and direction of cornea is measured by using Pentacam(Oculus Co., Germany), as targeting 57 adults (average $27.0{\pm}4.8$, 20 men, 37 women) without any ophthalmic diseases, which may be effective in eyesight, and refractive surgery. Results: As diameter increases in every direction based on the corneal vertex, asphericity has attentively increased (p<0.05), and the size of asphericity in each direction from every measured diameter showed as superior > nasal > inferior > temporal. In group comparison by nearsightness and astigmatism level, asphericity measured high when nearsightness and astigmatism levels were higher, and this appears to be statistically attentive.(p<0.05). Conclusions: Asphericity of cornea significantly increased according to increase of diameter of cornea, and as measured figure or increased quantity appeared differently in all directions based on corneal vertex, so it helps to understand shape of cornea, and considered that is the part to be considered during manufacturing and fitting of RGP lenses.

• Journal of Digital Convergence
• /
• v.11 no.11
• /
• pp.85-94
• /
• 2013

This paper presents a novel mobile measurement system with multi antennas which enable mobile measurement as well as fixed measurement with telescope mast. Proposed system installed 4 omni directional antennas for the space diversity process and one directional log periodic antenna for the simultaneous conventional fixed measurement. Whole antenna systems are connected to the custom DTV channel analyzers with Ethernet networks respectively and processed by the main controller to calculate real time average receive levels. To prove the performance of proposed system, the typical receive models are categorized as 3 area types - open area, building area and house area, and then intensive field tests were performed through mobile and fixed measurement phases. With these measurement data, the relationships between mobile and fixed measurement are analyzed, and the concept of compensation factor is proposed to assume the average receive level of signal. The field test is fulfilled as a co-work with public broadcasters and the proposed system is applied to the intensive coverage measurement projects for metropolitan areas by the korean government agencies.

• Journal of Korean Ophthalmic Optics Society
• /
• v.16 no.3
• /
• pp.313-317
• /
• 2011

Purpose: This study was to assess prevalence of refractive errors and uncorrected refractive errors in elementary school children in Mokpo and uncorrected refractive errors were to be used as the basic data. Methods: Vision tests were conducted on 400 subjects of 1st~6th grades at 3 elementary schools in Mokpo city, and subjective, objective refraction test were also performed to survey uncorrected refractive errors. Results: The prevalence of myopia was 256, 64% of total subjects, Hyperopia was 21, 5.3%, astigmatism was 19, 4.8%. The prevalence of uncorrected refractive errors were increased as higher grade and more oculus dexter higher than oculus sinister. Conclusions: Vision impairment which need an accurate vision correction for elementary school students requires the regular examination and actively correction in order to protect the elementary school students for basic welfare.

• Journal of the Korea Convergence Society
• /
• v.12 no.2
• /
• pp.113-120
• /
• 2021

The objective of this study is to identify the visual function impairment of children with each type of attention deficit hyperactivity disorder(ADHD). The subjects of this study were 49 children diagnosed with ADHD with visual function out of the normal range. The type of ADHD was investigated using the Korean-ADHD Rating Scale and visual function test. The attention deficit type(69.4%) of ADHD was the most common type among children with ADHD with vision problems. Although their overall naked-eye visual acuity was good, about 50% of the subjects showed problems with visual function. For those with the attention deficit type of ADHD, the myopia-related refractive error was high. For those with the hyperactivity type of ADHD, the astigmatism-related refractive error was higher. For those with vergence function disorder, convergence insufficiency was the most common. As there were differences in the visual impairment characteristics of children with different types of ADHD, it is necessary to approach a child's problem behavior through examination and screening for visual function disorders.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.35 no.1
• /
• pp.58-62
• /
• 2022

Objectives : The aim of this study is to report the effect of long-term acupuncture on a amblyopia derived from astigmatism. Methods : A 39-month-old-female child presented with decreased visual acuity with simple astigmatism and amblyopia in the left eye. She took long-term acupuncture treatment once or twice a week for almost four years. And the autorefractor follow-up were conducted per every 6 months. Results : At the initial visit, naked eye visual acuity was 0.1/0.7(OD/OS), Sph. +0.00D, Cyl. -2.25D, AXIS 148° in the right eye, and Sph. +0.00D, Cyl. -0.25D, AXIS 49° in the left eye. After acupuncture treatment for about 4 years without correctional glasses, the visual acuity of the right eye was 1.0, the right eye had Sph. +0.00D, Cyl -0.50D, AXIS 146°, and the left eye had Sph. -0.25D, Cyl -0.50D, AXIS 154°. The visual acuity was maintained until 1 year follow up as 0.9/1.0(OD/OS). Conclusions : This study shows the possibility of using acupuncture treatment for amblyopia derived from astigmatism.