• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.4
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• pp.200-208
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• 1989

To the purpose of preparation for investigating aspect of material that not revealed by the light microscope and extending our knowledge in applicable field, a scanning acoustic microscope system of 200MHz was organized and appraised its performance with experiments. Professor N.CHUBACHI in Tohoku University in Sendai, Japan provided the ZnO transducer with lens. The system for transmitting and receiving ultrasonic pulses of 200nsec was organized with a rectangular audio wave generator for modulation of 200MHz carrier wave, gating system for transmitting and receiving, mixer for converting intermediate frequency, a directional coupler, ZnO transducer, radio frequency amplifiers. detecter and personal computer. The Scanning system was driven in micro steps with three stepping motors in the direction of x, y and z axes. The system was a reflecting type scanning acoustic microscope and the operation program processed graphics data from receiving echo intensities. Photograph of fish scale obtained by optical microscope was compared with its image by the scanning acoustic microscope organized here. The result was satisfiable.

• Journal of Integrative Natural Science
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• v.6 no.1
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• pp.1-7
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• 2013

Polyurethane resin containing isocyanate is marked by excellent tensile and mechanical strengths and this test aims to gauge its applicability as a medical high polymer. Tris [2-(acryloyloxy)ethyl]isocyanurate and hexamethylenediisocyanate were added to a basic mixing ratio of HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), NVP (n-vinyl-2-pyrrolidone) and crosslink agent, EGDMA (ethylene glycol dimethacrylate) with increasing proportions and copolymerized respectively. Also, the basic physical properties of the polymerized high polymers including refraction rate, tensile strength, light transmission and water content were measured to confirm that they are appropriate as hydrogelcontact lenses. After measuring the physical properties of high performance polymers produced by adding tris [2-(acryloyloxy) ethyl]isocyanurate, it was found that the average tensile strengths of sample TRIS1 to TRIS10 were between 0.285 and 0.612 kgf, while the average values of refractive index were ranged from 1.441 to 1.449 with water content from 30.00 to 37.35%.The measurement of physical properties of the copolymers generated by adding hexamethylenediisocyanate showed that the average tensile strength of sample HEXA1 to HEXA10 ranged from 0.267 to 1.742 kgf, the refractive index ranged from 1.443 to 1.475 and water contents were in the range of 21.22 to 35.58%. In all combinations the transmission rates satisfied the transmittance of general hydrogel contact lenses. From theresults, it is possible to conclude that the produced copolymers can be used as contact lens materials with excellent tensile strength.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.39-48
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• 2007

The stimulus of accommodation A, the stimulus of convergence C and the prism diopter ${\Delta}$ are reviewed and redefined more obviously. How the A and C are managed in the practice are reviewed and summarized. As a result, the common practical process of the binocular vision findings is most suitable in the case of the $l_c=26.67mm$, where the near distance is measured from the test lens to the near target and its value is 40 cm and the average of the P.D equal to 64 mm. The $l_c$ is the distance between the test lens and the center of rotation. Those values were used at calculating the various values in this paper. The error of the stimulus of accommodation values which are evaluated by the practically used formula (5) are calculated. Where the distance between lens and the principle point of eye is 15.07 mm ($=l_H$). The incremental stimulus of convergence values P' caused by the addition prism $P_m$ are evaluated by the recursion computation method. The P' are varied with the $P_m$, the distance $p_c$ between the prism and the center of rotation, the initial convergence value (or inverse target distance) $C_o$ and the refractive index n of the prism material. The recursion computation method and the other formulas are described in detail. In this paper n=1.7 is used. The two factors by which the P' is increased are exist. The one which is major is the property by which the values of convergence whose unit is ${\Delta}$ are not added in the generally way. The other is the that the actual power of the prism is varied with the angle of incidence light. And the P' is decreased remarkably by an increase in the $p_c$ and $C_o$. The $P^{\prime}/P_m$ are calculated and graphed which are varied with the $p_c$ and $C_o$, where the $P_m=20{\Delta}$, P.D=64 mm and n=1.7. The index n dependence of the $P^{\prime}/P_m$ is negligible (refer to fig. 6). The $p_c$ are evaluated at which the P' equal to the $P_m$ for various $P_m$ (refer to table 1). The actual values of the stimulus of convergence and accommodation which are manipulated simply in the practice are calculated. Two graphical forms are suggested. The one is like as the commonly used one. But the stimulus of convergence and of accommodation values in the practice are positioned at the exact positions when the graphic is made (refer to fig. 9). The other is the form that the incremental stimulus of convergence values caused by the addition prisms are represented at actual positions (refer to fig. 11).

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.129-134
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• 2003

A wide variety of unsaturated vinyl derivatives can be induced to undergo free-radical chain polymerization. The capability to carry out a thermodynamically feasible polymerization relies on its kinetic feasibility on whether the proceeds at a reasonable rate under a given set of reaction conditions. Initiator or promoter is often required to achieve the kinetic feasibility. Only a few unsaturated monomers including methyl methacrylate(MMA) are known to absorb light between 250 and 500 nm which is the most convenient wavelength range. Also, the polysilanes with unusual optical and electronic properties have been used as ceramic precursors, deep UV photoresists, photoconductors. The hydrosilation has been used to make many interesting types of silicon containing polymers such as copolymer, dendrimers. Bulk polymerization of monomers with different molar radio of hydrosilanes(9:1 through 1:9) were performed. A quartz test tube charged with monomer and hydrosilane was degassed and irradiated with 250 nm UV for 6 hours. The polymer was taken in toluene, precipitated in hexane, filtered off, and dried. It was found that the initiators appeared to competitively and concurrently function as both chain initiation and transfer agents in the polymerization of vinyl monomers.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.583-590
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• 2004

The autofocus is one of the important processes in the automated vision inspection or measurements using optical microscopes, because it influences the measuring accuracy. In this paper, we used the confocal microscope configuration based on not a pinhole but a single-mode optical fiber. A single mode fiber has the functions of source and detector by applying the reciprocal scheme. As a result, we acquired a simple system configuration and easy alignment of the optical axis. Also, we embodied a fast autofocus system by acquiring the focus error signal through a source modulation technique. The source modulation technique can effectively reduce physical disturbances compared with objective lens modulation, and it is easily applicable to general optical microscopes. The focus error signal was measured with respect to the modulation amplitude, reflectance of the specimen and inclination angle of the measuring surface. The performance of the proposed autofocus system was verified through autofocusing flat mirror surface. In addition, we confirmed that source modulation rarely degrades the depth resolution by the comparison between the FWHMs of axial response curves.

• Journal of Family Resource Management and Policy Review
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• v.17 no.2
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• pp.173-194
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• 2013

The purpose of this study was to examine the association between time-income availability and health-promoting behavior (physical practice, smoking, alcohol consumption) of older males (55-69). This study attempted to shed light on health-behavior changes during the transition period of male retirement. The availability of time resources was examined by addressing the amount of weekly paid labor hours. The availability of financial resources was calculated by using the debt-income ratio. The study sample comprised 1,372 (age range 55-69) male respondents of the 2006 Korean Longitudinal Study of Aging (2006 KLOSA wave 1). The results of CHAID (CHi-squared Automatic Interaction Detection) analysis uncovered four distinctive combinations of resource types: time-money poor, time rich, money rich, time-money rich. According to logit results, these four groups had different socio-demographic profiles and different health-behavior risks. The time-money poor males were unlikely to perform physical activities needed to improve their health or to quit smoking or alcohol consumption. This group was also more likely to consume alcohol compared to the time-money resource types. In contrast, the time-money rich group was more likely to exercise longer and more frequently than the reference group (time and money poor). The time-rich types, those who have time-only resources and less money, were likely to be smokers and have problems with alcohol consumption.

• Journal of the Optical Society of Korea
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• v.17 no.4
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• pp.344-349
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• 2013

This paper proposes a simulation algorithm to assess the gradual yellowing vision of the elderly, which refers to the predominance of yellowness in their vision due to aging of the ocular optic media. This algorithm employed the spectral transmittance property of a yellow filter to represent the color appearance perceived by elderly people with yellow vision, and modeled the changes in the color space through a spectrum change in light using the yellow filter effect. The spectral reflectivity data of 1269 Munsell matte color chips were used as reference data. Under the standard conditions of a D65 illuminant and a $10^{\circ}$ observer of 1964 CIE, the spectrum of the 1269 Munsell colors were processed through the yellow filter effect to simulate yellow vision. Various degrees of yellow vision were modeled according to the transmittance percentage of the yellow filter. The color differences before and after the yellow filter effect were calculated using the DE2000 formula, and the color pairs were selected based on the color difference function. These color pairs are distinguishable through normal vision, but the color difference diminishes as the degree of yellow vision increases. Assuming 80% of yellow vision effect, 17 color pairs out of $(1269{\times}1268)/2$ pairs were selected, and for the 90% of yellow vision effect, only 3 color pairs were selected. The result of this study can be utilized for the diagnosis system of gradual yellow vision, making various types of test charts with selected color pairs.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.103-103
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• 2014

Manufacturing of lens and mirror using Diamond Turning Machine (DTM) offers distinct advantages including short fabrication time and low cost as compared to grinding or polishing process. However, the DTM process can leave mid-frequency error in the optical surface which generates an undesirable diffraction effect and stray light. The mid-frequency error is expected to be eliminated by mechanical polishing after the DTM process, but polishing of soft surface of ductile aluminum is extremely difficult because the polishing process inevitably degrades the surface form accuracy. In order to increase its surface hardness, we performed electroless nickel plating on the surface of diamond-turned aluminum (Al-6061T6) off-axis mirrors, which was followed by the 6-hour-long baking process at $200^{\circ}C$ for improving its hardness. Then we polished the nickel plated off-axis mirrors to remove the mid-frequency error and measured polished mirror surfaces using the optical surface profilometer (NT 2000, Wyko Inc.). Finally, we ascertained that the mid-frequency error on the mirror surface was successfully removed. During the whole processes of nickel plating and polishing, we monitored the form accuracy using the ultra-high accurate 3-D profilometer (UA3P, Panasonic Corp.) to maintain it within the allowable tolerance range (< tens of nm). The polished off-axis mirror was optically tested using a visible laser source and a pinhole, and the airy pattern obtained from the polished mirror was compared with the unpolished case to check the influence of mid-frequency error on optical images.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1213-1219
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• 2012

A remote $CO_2$ laser system can rapidly change both the distance and the direction of the laser beam by moving a lens and rotating mirrors. It is then easy to weld complex patterns of weld lines. A conventional spot weld joint specimen and a remote $CO_2$ laser weld joint specimen with complex weld line patterns were prepared and tested both statically and dynamically. The relationships between the fatigue strength, i. e. the maximum cyclic force, and the fatigue life were obtained. The fatigue strength of the tested welded joints at two million cycles was found to be approximately 10% of the static strength. Furthermore, it was observed that the fatigue fracture mode changed with the level of the applied cyclic force. The fatigue crack origins were confirmed as the highest stress points found in the structural analysis. The maximum cyclic stress for different weld patterns converges as the fatigue life approaches two million cycles.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.217-223
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• 2013

White light MTF(Modulation Transter Function)s of biconvex trial lenses from 10 to 20 diopter (D) were represented as a function of angular frequency and visual acuity, and then they were compared with AIM(Aerial Image Modulation) curves. All of the biconvex trial lenses evaluated in on-axis mode had MTF performance that could resolve Landolt's ring up to visual acuity 2.0. However, in a half field angle of five degrees, the trial lens of 10 diopters was able to resolve Landolt's ring up to visual acuity 0.9, and that of 20 diopter only up to visual acuity 0.8. This means that the trial lenses in the case of a half field angle of five degrees do not have sufficient resolution to measure visual acuity by 1.0.