• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.2 no.2
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• pp.55-58
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• 1988

Electron mobility which is a basic parameter to represent gas state, is calculated for 38mm 20W fluorescent lamp. 2 Electron Group Model is u&ed for electron distribution function. To prove this result electron mobility in 38mm 20W fluorescent lamp is measured at various wall temperatures. In order to obtain electric field strength of positive column, the sum of anode and cathode fall voltages assumed to be 15(VJ) and dual slit is used to measure positive column length. The measured and calculated result is potted under $10-80^{\circ}C$ wall temperature.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.9-13
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• 2010

An experimental study for characteristics of soot were conducted at the post-flame region in jet diffusion flames, where carbon dioxide was used as additives in oxidizer stream. Light-extinction method was performed using He-Ne laser with wave length at 632.8nm for the measurement of relative soot density and soot volume fraction with dimensionless extinction coefficient, $K_e$ and mass specific extinction coefficient, ${\sigma}_s$. To increase of resolution, laser light was modified for sheet-form using concave, convex lenses and slit. C/H ratio was introduced for quantitative analysis of soot growth which is expressed by carbonization and dehydrogen. Also transmission electron microscopy(TEM) was used for observation of morphological shape. The results show that the relative soot density in the post-flame region was lower when carbon dioxide was added in oxidizer stream because of reduction of flame temperature.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.167-174
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• 1998

This paper presents an unoccluded cylindrical object pose measurement using a slit beam laser in which a robot recognizes all of the unoccluded objects from the top of jumbled objects, and picks them up one by one. The elliptical equation parameters of a projected curve edge on a slice are calculated using LSM. The coefficients of standard elliptical equation are compared with these parameters to estimate the object pose. The hamming distances between the estimated coordinates and the calculated ones are extracted as measures to evaluate a local constraint and a smoothing surface curvature. The edges between slices are linked using error function based on the edge types and the hamming distances. The linked edges on slices are compared with the model object's length to recognize the unoccluded object. This proposed method may provide a solution to the automation of part handling in manufacturing environments such as punch press operation or part assembly.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.675-682
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• 2011

Recently, in retrofit of RC structures using FRP (Fiber Reinforced Polymer), researches about Near-Surface-Mounted Rertofit (NSMR) method have been widely performed. In NSMR, FRP bar is normally inserted in the slit formed in the cover concrete and then bonded by using epoxy mortar. In this paper, the bond characteristic of NSMR using FRP plate instead of bar was studied experimentally. Fracture behavior is observed from bond test using the parameters of embedment length, shear key, and FRP plate layer. In addition, an equation to predict the splitting strength of NSMR using FRP is proposed using the test result. The results showed that when the longer embedment length and more layers of FRP are used, the higher bond strength is achieved. There was a good co-relationship between the test and calculated results using the proposed equation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1299-1308
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• 2003

This paper is studied to investigate the effect of slits and swirl vanes on the development of turbulent flow fields in gun-type gas burner with a cone type baffle plate because this gas burner is generally composed of eight slits and swirl vanes. All of turbulent characteristics including mean velocities were measured in the horizontal plane and cross section by using X-type hot-wire probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 l/min in the test section of subsonic wind tunnel. Slits cause the fast jets, and then they have the characteristic that the flow is not adequately spread to radial direction and has long flow length and very small flow velocity distribution in the central part. On the contrary, swirl vanes does not have long enough for adequate flow length to downstream because the rotational flow diffuses remarkably to radial direction. However, the suitable arrangement between slits and swirl vanes causes effective flow width and flow length, and then it promotes fast flow mixing over the entire region including central part to increase turbulence more largely and effectively. Therefore, it is thought as a very desirable design method in gun-type gas burner to locate slits on the outside of swirl vanes.

• The Journal of Korean Medicine
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• v.37 no.2
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• pp.53-61
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• 2016

Objectives: Considering high prevalence of myopia in Asian countries, social cost paid for myopia may gradually increase in Korea. However, studies for developing myopia treatment are deficient. The study was to evaluate whether the periocular acupressure with a medical massager is effective for suppressing myopia progression. Methods: This study was an investigator-sponsored, prospective, open-labeled, and superiority pre and post single-armed study. 14 myopia children aged 7-12 years wore a medical massager for 15 minutes to stimulate periocular acupoints. For 24 weeks, the participants used the device twice a day. Based on prior studies, the refraction change of naturally proceeded myopia was set as -0.38 D. The axial length change of naturally proceeded myopia was set as 0.228 mm. To assess the safety, we performed vital sign check, physical examination, visual acuity test, slit lamp examination, IOP measurement, and fundus examination. Results: The refraction and axial length of the participants increased. For 24 weeks, the change in refraction was -0.38 D at the right eye and -0.40 D at the left. The change in axial length was 0.21 mm at the right and 0.22 mm at the left. In the safety assessment, any adverse event did not occur. Conclusions: There was no significant difference between the control group and the intervention group. The effect of growth may have more contributed to our result than that of acupressure. Based on our result, a full-scale study will not be conducted.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.1
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• pp.67-71
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• 1996

During a 2-year period microsurgical vasovasostomies using permanent silicone stent(c-shaped stent with 0.6mm slit, 5mm in length, 0.8mm in outer diameter, 0.5mm in inner diameter) were performed in 30 patients for vasectomy revesal. The stent-assisted vasovasostomy(SVV) was intended to decrease the technical demand, the time requirement and the occurrence of reobstruction due to postoperative stricture. The effectiveness of the permanent silicone stent for vasovasostomy was compared with that of microsurgical two-layered vasovasostomy(VV). Sperms were present in all the ejaculates of the 25 men on semen analysis 1-2 months after SVV. Pregnancy occurred in 10 of 22 couples(45.5%) during 2-24 months of follow-up and it took 4-10 months(average 7.2 months) to get pregnant. Average operation time for the VV was 150 minutes and that for the SVV 125 minutes. Among 12 men who had sperms in the ejaculates 1-2 months after SVV, 4 revealed azoospermia 3-17 months postoperatively. Among the 4 patients with postoperative azoospermia, 2 underwent reoperation. On histopathologic examination, previously anastomsed sites showed obliterated lumen of the stent and strictures of vas proximal and/or distal to the stents due to granulation tissues. In conclusion, the SVV was not more efficacious in terms of patency and pregnancy rate than the VV.

• Journal of the Korean Society of Costume
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• v.56 no.7 s.107
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• pp.68-84
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• 2006

The aim of this study is to examine a structure of trousers worn by males in the western world during the 17th and 18th centuries in order to understand the characteristics of evolution in construction. it mainly examined engravings from these era because they provided me fine and detailed portrayals of what it needed to observe. Then, it classified them into models according to each era. it supplemented a flaw of depending on single type of studying material by examining other types of historical materials such as historical paintings and documents for comparative analysis of materials and decorations and previous studies on preserved historical documents to observe the examples of structures of trousers. Secondly, it studied both historical documents and previous studies on the trousers patterns used back in those days, analyzed the characteristics of each designing method by actually draping these patterns, and observed the differences in these completed patterns to understand the characteristics of changes in fashion design skill. As for the changes in length, these patterns show only a slight difference around above and below the knee line. However, the widths of waist, hip, girth and hem were significantly altered over the years to reduce wrinkles and the cutting lines became more refined to make the clothes fit to the body. As a result, a simple but fine patterning technique was born. In particular, new methods in cutting and sewing were invented for detailed parts such as waist, pocket, front and slit.

• Applied Microscopy
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• v.42 no.3
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• pp.124-128
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• 2012

Leaf surface structures were investigated in the Chinese juniper Juniperus chinensis by scanning electron microscopy. Adult scale leaves were collected from the tree, air-dried at room temperature, and sputter-coated with gold without further specimen preparation. Approximately fi ve stomata were locally distributed and arranged in clusters on the leaf surface. Stomata were ovoid and ca. 40 ${\mu}m$ long. The epicuticular wax structures of J. chinensis leaves were tubules and platelets. Numerous tubules were evident on the leaf regions where stomata were found. The tubules were cylindrical, straight, and ca. 1 ${\mu}m$ in length. They almost clothed the stomatal guard cells, and occluded the slit-shaped stomatal apertures. Moreover, the wax ridges were flat crystalloids that were connected to the surface by their narrow side. They did not have distinct edges, and their width/height ratio varied. In particular, the wax ridges could be discerned on the leaf regions where stomata were not present nearby. Since the wax ridges did not have distinct edges on their margin, they were identified as platelets. Instances were noted where platelets were oriented either parallel to each other or perpendicular to the cuticle surface. These results can be used in biomimetics to design the hierarchical structures for mimicking the plant innate properties such as hydrophobicity and self-cleaning effects of the leaf surface.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.65-73
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• 2010

In order to provide fundamental information for developing reaction model in the practical blended coal power plants, effects of particle size and blending ratio on combustion characteristics and thermal reaction in co-firing with bituminous and sub-bituminous coals were experimentally investigated using a TGA and a laboratory-scale burner. Characteristic parameters including ignition, burnout temperature and activation energy were determined from TG and DTG combustion profiles. Distributions of flame length and mean particle temperature were investigated from the visualization of flames in slit-burner system. As coal particle size decreased and volatile matter content increased, characteristic temperatures and activation energy decreased. The ignition/burnout characteristics and activation energy are linearly influenced by a variation in particle size and blending ratio. These results indicated that the control of the coal blending ratio can improve the combustion efficiency for sub-bituminous coals and the ignition characteristics for bituminous coals.