• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.271-272
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• 2009

We fabricated a hybrid aligned film using reactive rod-like mesogen to reduce light leakage of twisted nematic(TN) cell in off-axis of the dark state. We proved that the fabricated compensation film has hybrid alignment by changing phase retardation according to polar angle. In this paper, we confirmed characteristics of compensation film through simulation results and found the matching factor of simulation results and experimental result. In result, the maximum pretilt angle of hybrid compensated film is $19^{\circ}$ which has phase retardation 0.1445.

• Applied Microscopy
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• v.41 no.4
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• pp.223-228
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• 2011

White light scanning interferometry has been employed to analyze surface features of diverse specimens. Long established in the field of materials engineering, the technique provides quantitative three-dimensional data as well as qualitative morphological images. It uses white light that is split and reflected from a reference mirror and an object. Merged together, the light generates interference patterns representing topographical contours of the object surface. The amplitude of the z-axis data is differentiated by gray scale. The technique allows the rapid, noncontact, and wide-field measurements for morphometry of biological specimens including chondrocytes, tooth enamel, and plant leaves. Quantification of the dimension of surface structures such as width, length, and elevation angle could be achievable by white light scanning interferometry. The light reflection from plant leaves has been assumed to be sufficient for the technique. Without special specimen preparations like conductive metal coating, the technique can be increasingly used for quantitative three-dimensional surface measurements of biological specimens.

• Membrane Journal
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• v.8 no.3
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• pp.157-169
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• 1998

The effects of solvents (DMAc, NMP, 1,4-dioxane) and nonsolvents ($H_2O$, Methanol, n-hexane) on the morphology of 6FDA-p-TeMPD polyimide membrane, prepared by the wet phase inversion method, were studied. In the polymer/solvent/nonsolvent ternary system, the binodal curve, the coagulation value and the relative light transmission were measured, and the solubility parameter difference was calculated. The onset state and rate of liquid-liquid alemixing were predicted and the morphology of membrane was analyzed. It is found that the finger-like pores are formed within discontinuous polymer nodules when the binoclal curve is close to the polymer-solvent (P-S) axis, the coagulation value is small, the reduction of light transmission is easy to occur and the order of solubility parameter difference ($\Delta \delta_{i-j}$) is $\Delta \delta_{S-NS} > \Delta \delta_{P-NS} > \Delta \delta_{P-S}$. The dense skin with small nodules and the sponge type sublayer with macrovoid are formed in the case that the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is long and the order of $\Delta \delta_{i-j}$ is $\Delta \delta_{P-NS} >(\Delta \delta_{S-NS} < > \Delta \delta_{P-S})$. The thick layer of fine nodule coagulation and loosely grown sublayer of nodules appear when the binodal curve is distant from the P-S axis, the onset time of liquid-liquid demixing is very long and the order of $\Delta \delta_{i-j}$가 $\Delta \delta_{S-NS} > (\Delta \delta_{P-NS}$\lessgtr$ > (\Delta \delta_{P-NS} < >)\Delta \delta_{P-S}$ ).

• Journal of Sensor Science and Technology
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• v.25 no.3
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• pp.208-212
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• 2016

In this work, a loop sensor for Arc-Flash detections has been developed in order to trip a circuit breaker within 2.5 ms after an Arc-Flash event. For an efficient capturing of the flash light, plastic optical fibers, where light attenuations are larger than those in silica-based ones, with different diameters and surface conditions were utilized. The performance was comparatively analyzed with those of a point sensor and a commercialized product. The point sensor module was designed for hemisphere-like capturings of Arc-Flashes larger than 3 kA at 2 meters from the sensor. On the other hand, the loop sensor allowed 360-degree-detections around the fiber axis and the measurement range was dependent on the length of the fiber connected to the sensor module. The trip-level-dependent brightness measurement results showed that the fabricated point sensor and loop sensor satisfied a brightness condition, 10~40 klux, and the responses of the system to Arc-Flashes were completed within 2.5 ms.

• Journal of the Korean Wood Science and Technology
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• v.9 no.1
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• pp.1-12
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• 1981

The structure of spiral thickenings, particulary the appearance, arrangement and orientation of thickenings in compression wood of Torreya nucifera, were studied in detail by light and polarizing microscope, scanning and transmission electron microscope. The results obtained are as follows: (1) Using the inclined sections at an angle of 45 degrees to the fiber axis, it seems that we can not only observe the more accurate transverse view of the thickenings but also investigate the formation of their thickenings. (2) Generally 2-4 pieces of thickenings are projected to the cell lumen as nipple-like appearance in transverse section and are as frequent, well developed, forming pair and have the rope-like appearance in radial surface. (3) The secondary wall of early wood is composed of 3 layers (S1, S2, S3) and orientation of thickening appears S helix but that of late wood is of 2 layers (S1, S2) and that orientation shows Z helix. Above two regions are demaracted at several tracheid cells from the growth ring boundary. (4) Orientation of thickening seems to be a element showing the characteristics of compression wood in Torreya nucifera. (5) It believes that the thickenings of compression wood are integral part of the S3 in early wood tracheids and of the S2 in late wood and have the same orientations as the inner-most microfibrils in these layers. (6) Thickening and cavities seem to be not formed together in a secondary cell wall of same tracheids.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1105-1109
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• 1995

A CCD-camera, which is structured with vision system, was used to realize automatic seam-tracking system and 3-D information which is needed to generate torch path, was obtained by using laser-slip beam. To extract laser strip and obtain welding-specific point, Adaptive Hough-transformation was used. Although the basic Hough transformation takes too much time to process image on line, it has a tendency to be robust to the noises as like spatter. For that reson, it was complemented with Adaptive Hough transformation to have an on-line processing ability for scanning a welding-specific point. the dead zone,where the sensing of weld line is impossible, is eliminated by rotating the camera with its rotating axis centered at welding torch. The camera angle is controlled so as to get the minimum image data for the sensing of weld line, hence the image processing time is reduced. The fuzzy controller is adapted to control the camera angle.

• Applied Microscopy
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• v.14 no.2
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• pp.81-93
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• 1984

Structural differences in various divisions of the rabbit colon were investigated using light and scanning electron microscopy. For light microscopic study, various Portions of the colon from seven rabbits (2.5 kg body weight) were fixed in 10% neutral buffered formalin, and paraffin sections were stained with hematoxylin-eosin. Tissues for scanning electron microscopy were fixed in 1% glutaraldehyde-1.5% paraformaldehyde and postfixed in 1% $OsO_4$, dehydrated to 100% alcohol, transfered to isoamilacetate and dried by the critical point method. Subsequently, specimens were coated with gold and viewed with a JSM-35C scanning electron microscope. The colon displays a morphological diversity along its proximo-distal axis. Five regions can be discerned based on the macroscopic and microscopic characteristics. 1) The first segment immediately distal to the cecocolical junction possessing three teniae is approximately 5 cm ($4{\sim}6cm$) in length, and displays irregular folds of the mucosa oriented transversely similar to those of the cecum. 2) The second segment possessing three teniae is about 7 cm ($5{\sim}8cm$) in length, and is characterized by the papilla-like protrusions on the mucosal surface. 3) The third segment, possessing a single tenia is about 16 cm ($12{\sim}20cm$) in length, and also displays the papilla-like protrusions similar to the aforegoing segment. 4) Fusus coli, approximately 4 cm ($3{\sim}5cm$) in length, is free of teniae and exhibits longitudinal folds on the mucosal surface. These four portions together constitute the proximal colon. 5) The distal colon reaches a length of about 58 cm ($53{\sim}55cm$) and shows a pattern of surface irregularities with minor ridges on the mucosal folds.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.8
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• pp.758-765
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• 2011

Recently, the wind energy has been widely used as a renewable energy resource due to lack and environmental issues of the mostly used fossil fuel. This work is to develop a 500W class blade design of vertical axis wind turbine system which will be applicable to relatively low speed region like Korea and for the domestic use. For this wind turbine a high efficiency and low noise turbine blade was designed with the proposing aerodynamic design procedure, and a light composite structure blade. Structural analyses were performed using the Finite Element Method and fatigue life of the designed blade is estimated. Finally, in order to check its performance, the manufactured blade was tested by using truck and the results of test was good with respect to its analysis result.

• Journal of the Korean Wood Science and Technology
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• v.19 no.1
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• pp.64-70
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• 1991

In order ot obtain the information on wood quality of the Populus nigra $\times$ maximowiczii the distributions of crystalliferous substancess, ty loses and tension woods were examined through light microscopy or scanning electron microscopy. 1. The crystalliferous subtance, presumably calcium oxalate. partially occurred in vessel elements of heartwood, and sporadically in ray parenchyma, but not in the wood fibers The types of crystalliferous subtances were mainly crystal sand, $2-3{\mu}m$ in diameter. 2. The tyloses arranged in a ladder-like series were sporadically formed in the vessel elements of heartwood. 3. Although the woods were cut from the straightly grown stem without any evident disorientation with respect to gravitational axis, single or group of gelatinous fibers were irregularly distributed among normal wood fibers.

• Journal of Ginseng Research
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• v.19 no.3
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• pp.275-280
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• 1995

The formation of thylakoid membrane proteins and changes in the chloroplast ultrastructure of ginseng leaf were investigated as a function of time following the leaf emergence. The leaf chloroplast obtained just after the leaf emergence showed short rod-like thylakoids which were connected and arranged in 3~4 layers along the longitudinal axis of the chloroplast. The 10 DAE (days after emergence) chloroplast started to form grana structure. The typical grana structure was observed 17 DAE, and the grana was fully developed 28 DAE. The membrane proteins obtained from just after emerging leaf were separated into many minor bands indicating no CP-complex formation yet. LHC II was detected after 10 days. CP 47 and CP 43 were detected after 17 days. After 28 days, the PS I and PS II proteins were distinctly separated into CP 1, LHC II, CP 47, CP 43, CP 29, CP 27+24. Thus, the appearance of the light harvesting protein, LHC II, which was concentrated in grana stacks, was consis tent in time with the formation of grana stacks 17 DAE. Key words Chloroplast ultrastructure, grana, CP-complex, LHC II.