• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.136-139
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• 2003

Thermal imaging system is electro-optical imaging device which can make visible the difference of infrared energy naturally emitted by objects. It is acquire the same images at any time of the day or night. There it has been readily available to the night observation such as fire control systems. In this study, we are manufacturing thermal image Al flat mirror. The surface roughness 3.539nm Ra and power 0.382 fringe(at 632.8nm), irregularity 0.835 fringe(at 632.8nm) for form waviness of thermal image Al flat mirror are very satisfied. The results will be reflected for development of the ultra precision application. And a brief review of Ultra-precision system in the field of Ultra-precision at Korea photonics technology institute (KOPTI) is present in this paper.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.720-725
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• 2007

This study investigated the pressing conditions in the molding of aspheric glass lenses for the mega pixel phone camera module using the DOE method. Tungsten carbide (WC; Japan, Everloy Co., 002K),which contained 0.5 w% cobalt (Co), was used to build the mold. The mold surface was ultra-precision ground and polished, and its form accuracy (PV) was 0.85um in aspheric surface. We selected four factors, pressing temperature, force and time of first step, and force of second step, respectively, as the parameters of the pressing process. in order to reduce the number of experiments, we applied fractional factorial design considering the main effects and two-way interactions. The analysis results indicate that the only two main effects, the pressing temperature and the time of pressing step 1, are available for the form accuracy (PV) of the molded lens. The analysis results indicated that the best combination of the factors for lowering the form accuracy(PV) value of molded lens was to have them at their low levels.

• Korean journal of applied entomology
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• v.20 no.3 s.48
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• pp.168-172
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• 1981

This work was carried out to study field biology of Agrotis tekienis B. in Korea for two years (1979 and 1980), The species was found to be the dominant species among cutworms giving damage to young Plants in Spring with making up approximately $80\%$ or more of cutworms collected at Suweon and Jeonju from March to early June. During April and May which is the most critical period as far as plant damage by cutworms is concerned, those of A. tokionis larvae collected were at 5th and 6th instar. A. tokionis larvae enter a summer diapause from late May to early July and Agrotis ipsilon became the dominant species. It is also suggested that A. tokionis larvae be called as the 'dark grey cutworm', based upon its larval body color.

• Journal of Aerospace System Engineering
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• v.8 no.2
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• pp.7-13
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• 2014

In order to enable fail-safe operation the electro-hydrostatic actuators can be dualized. When a symmetrical actuator is combined in series with an asymmetrical actuator with single rod cylinder, the flow rates of their cylinders are unmatched. If their position controller has same configuration, one of their pumps can supply too much flow rate under particular load conditions, which should be bypassed into low pressure side e.g. by a relief valve. In this paper it is shown how the hydraulic circuit for the asymmetrically combined electro-hydrostatic actuator can be designed without sacrificing power consumption.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.702-707
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• 2008

BTL projects for educational facilities were conceived in 2005 to supply public facilities in a timely and efficient manner After the projects were completed in March 2007, proper facility maintenance has become an increasingly important issue. However, BTL projects are still in an early developmental stage, and the data on the maintenance and operation of such facilities are not yet available because the operation of the facilities has just begun. Accordingly, this study is conducted to derive maintenance processes and to specify maintenance items for the efficient maintenance of BTL educational facilities. Then, database on the maintenance processes will be created, and a maintenance system module will be designed.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.1
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• pp.27-33
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• 2013

Helmet Mounted Display(HMD) has great advantages on the navigation and mission symbologies for the pilot's forward looking display and, therefore, has been remarkably drawing attention as the up coming display of the next generation aircraft. The essential technology to process the Line of Sight-Foward(LOS-F) data in real-time is to estimate exact helmet situation and position. In this paper, we research a acoustic helmet tracking technique. For the reason that mechanical acoustic noises might interfere with Helmet Tracking System(HTS) and unnecessary acoustic noises are inevitable when using acoustic technique, this approach has not been adapted. In order to overcome this problem. We propose that acoustic wave of which the wave length is longer than audio frequency and, especially, we used beating signal envelope which is composed of two close high frequency.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.45-50
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• 2007

The aspheric lens has become the most popular optical component used in various optical devices such as digital cameras, pick-up lenses, printers, copiers etc. Using aspheric lenses not only miniaturizes and reduces the weight of products, but also lower prices and higher field angles can be realized. Additionally, plastic lenses are being changed to glass lenses more recently because of low accuracy, low acid-resistance and low thermal-resistance in the plastic lenses. Currently, one fabrication method of glass lenses is using a glass-mold method with a high precision mold core for mass production. In this paper, DOE (Design Of Experiments) and compensation machining were adopted to improve the surface roughness and the form accuracy of the mold core. The DOE has been done in order to discover the optimal grinding conditions which minimize the surface roughness with factors such as work spindle revolution, turbine spindle revolution, federate and cutting depth. And the compensation machining is used to generate high form accuracy of the mold core. From various experiments and analyses, we could obtain the best surface roughness 5 nm in Ra, form accuracy $0.167\;{\mu}m$ in PV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.487-488
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• 2006

As DLC coating possesses such features as, high hardness, high elasticity, abrasion resistance and chemical stability, there have been exerted continuous efforts in research works in a variety of fields, and this technology has also been applied widely to industrial areas. In this research work, the optimal grinding condition was identified using Microlens Process Machine in order to contribute to the development of aspheric glass which is to be used for mobile phone module having 2 megapixel and $2.5{\times}$ zoom, and mold core (WC) was manufactured having performed ultra-precision machining and effects of DLC coating on shape accuracy(P-V) of mold core and surface roughness(Ra) as well were measured and evaluated.

• Journal of the Korean Society of Tobacco Science
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• v.17 no.1
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• pp.49-56
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• 1995

Morphology, chromosome and transmission of potato virus Y(PVY) of the green peach aphid populations collected from tobacco fields were examined. Based on the morphological characteristics, especially values of linear discriminant functions and length of ultimate rostral segment, 8 green peach aphid clones with different color morphs could be divided into two groups, namely Myzus persicae and M. nicotianae, according to the proposal by Blackman in 1987. The red (RED)-, Brown (BRN)- and green-colored (GR1, GR2) aphid clones belonged to the M. nicotianae type, while the pale green (PG1, PG2, PG3) and dark brown (DBR) clones to the M. persicae type. The karyotype of the pale green-colored clone (PG1, M. persicae type) appeared normal and was 2n=12 with no indication of chromosomal translocation. On the contrary, in the green-colored aphid clone (GR1, M. nicotianae type), translocation and dissociation of autosome 3 were often found, having karyotype of 2n=13. Both of the above aphid clones transmitted PVY-VN to tabacco plants (cv. Burley 21), but the GR1 clone had higher transmissibility than the PG1 clone.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.45-51
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• 2020

In this study, a response spectrum analysis of an electric distributing board (EDB) was conducted to investigate seismic integrity in the design stage. For the seismic analysis, the required response spectra of a safe shutdown earthquake with 2% damping (RRS/SSE-2%) specified in GR-63-CORE Zone 4 was used as the ground spectral acceleration input. A finite element method modal analysis of the EDB was also performed to examine the occurrence of resonance within the frequency range of the earthquake response spectrum. Furthermore, static stress caused by deadweight was analyzed. The resultant total maximum stress of the EDB structure was calculated by adding the maximum stresses from both seismic and static loads using the square root of the sum of the squares (SRSS) method. Finally, the structural safety of the EDB was investigated by comparing the resultant total maximum stress with the allowable stress.