• Publications of The Korean Astronomical Society
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• v.20 no.1 s.24
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• pp.151-161
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• 2005

The reimaging optics of the KASINICS (KASI Near Infrared Camera System) includes many transparent components like an entrance window, band-pass filters, and blocking filters. As observational targets or in-field background objects, bright stars may cause optical ghosts that can significantly degrade the system performance of the KASINICS. We estimated analytically the relative brightness of ghost components with respect to a point source and examined the effects of tilting optical components as a method of suppressing ghosts. We also performed numerical ray tracings including all the optical components and found the results are consistent with those of the analytic estimations. We conclude that the KASINICS will not suffer from significant ghost effects with appropriate anti-reflection coatings and fittings for the optical components.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.93-97
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• 2004

Since powerline for powerline communications (PLC) is designed for supplying electric power using 60 Hz wave, they will have different electrical behaviors for high data rate PLC whose bandwidth is allocated between 1 MHz and 30 MHz. Thus, it is necessary to investigate the different properties in this frequency bandwidth for the high data rate PLC. In this paper, low voltage (220V) powerline impedance for indoor high data rate PLC in between 1 MHz and 30 MHz is measured. For measurement a low voltage coupling unit is made and a vector network analyzer is used. A T-equivalent circuit of the low voltage coupling unit is obtained and then powerline impedance is derived by measuring the reflection coefficient of the total powerline network. With the method proposed, impedance is measured in case of a general korean apartment and its property is analyzed. Measurement shows that the average impedance is about 100Ω.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.9
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• pp.6-12
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• 2011

In this paper, we propose a design method for a reliable and improved field-installable optical connectors(FIOC) which are needed for long-distance and low loss FTTH configuration. To this end, we optimize the angle of splicing between the inner fiber and the field fiber of the FIOC, so that the low loss connection of optical fibers is possible without using any angle alignment tools as well as angled cleavers. More precisely, we set the cutting angle of the inner filber and the field fiber to be $2^{\circ}$ by using an angled cleaver and $0^{\circ}{\sim}1^{\circ}$ by using a general fiber cutter, respectively. Splicing these two optical fibers without any further adjustment, we can keep the insertion loss within 0.3dB and the reflection loss within -60dB.

• Composites Research
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• v.29 no.3
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• pp.98-103
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• 2016

This paper deals with the fabrication and verification of the microwave absorbing structure using semiconductive fiber reinforced composite. Two kinds of fiber were used to fabricate composites. Electromagnetic properties of the composites were measured by freespace measurement system over X-band. Two single slab absorbers and a double slab absorber were designed by thickness optimization method. Single slab absorbers did not show good microwave absorption performance because the permittivity is away from non-reflection curve. Double slab absorber complemented the limitations on single slab absorber and it showed good microwave absorption performance. Double slab absorber showed -43.9 dB loss near 10 GHz.

• Journal of the Korean Institute of Navigation
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• v.25 no.1
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• pp.53-60
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• 2001

This paper presents the fabrication of the LNA which is operating at 2.13 ~ 2.16 GHz for IMT-2000 front-end receiver using series feedback and resistive decoupling circuit. Series feedback added to the source lead of a GaAs FET keeps the low noise characteristics and drops the input reflection coefficient of a low noise amplifier simultaneously. Also, it increases the stability of the LNA. Resistive decoupling circuit is suitable for input stage matching because a signal at low frequency is dissipated by a resistor in the matching network. The amplifier consists of GaAs FET ATF-10136 for low noise stage and VNA-25 which is internally matched MMIC for high gain stage. The amplifier is fabricated with both the RF circuits and self bias circuit on the Teflon substrate with 3.5 permittivity. The measured results of the LNA which is fabricated using the above design technique are presented more than 30 dB in gain, PldB 17 dB and less than 0.7 dB in noise figure, 1.5 in inputㆍoutput SWR(Standing Wave Ratio).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.484-491
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• 2007

Numerical experiments using a numerical wave tank have been performed to verier the nonlinear interaction between monochromatic waves and a submerged horizontal plate. As a model for numerical wave tank, we used a higher-order Boundary Element Method(BEM) based on fully nonlinear potential flow theory and CADMAS-SURF for solving Navier Stokes equations and exact free surface conditions. Both nonlinear models are able to predict the higher harmonic generation in the shallow water region over a submerged horizontal plate. CADMAS-SURF, which involves the viscous effect, can evaluate the higher harmonic generation by flow separation and vortices at the each ends of plate. The comparison of reflection and transmission coefficients with experimental results(Patarapanich and Cheong, 1989) at different lengths and submergence depths of a horizontal plate are presented with a good agreement. It is found that the transfer of energy from the incident fundamental waves to higher harmonics becomes larger as the submergence depth ratio decreases and the length ratio increases.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.3
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• pp.407-419
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• 2017

Based on clothing prohibition modelling characteristics, this paper studies historical costumes through the traditional Chinese historical dramas of the 'Kang-Qian' heyday during the 'Qing Dynasty'; represents the research object as a representative Chinese historical drama. This paper systematically analyzed the utilization and reflection of royal women clothing prohibition. The results of the study are as follows. The royal women clothing prohibition of this drama shows three aspects of characteristics found in traditional Chinese costume modeling. First, some special colors that integrated ancient and modern styles were mainly used in this drama such as champagne color, wine color, and macaron color. Second, it mainly utilized the modelling of modern artificial pigments and floral patterns that are different from Chinese traditional female costumes of the 'Qing Dynasty'. Third, stage costumes for this drama are focused more on using a personality method to reflect the beauty of each actress by the application of individual elements. This study analyzed and studied the clothing prohibition of female costume from to show the traditional Chinese costume prohibition in a Chinese historical drama as well as reveal a few aspects of traditional female costume characteristics in the 'Kang-Qian' heyday during the 'Qing Dynasty'. This study examined traditional female costumes characteristics in modern historical dramas based on different figures and dynasties as well as discussed the factors at a deeper level and from varied aspects.

• The Journal of the Korea Contents Association
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• v.8 no.5
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• pp.260-267
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• 2008

The portfolio provides a method which can properly evaluate the student's long term period of learning and growth, and this allows students to have practical learning through self-reflection. However, following the realities of portfolio's operation, the portfolio is being operated formally just once only for the evaluation due to the difficulty of long custody and its time-consuming process. In this paper, after grasping the overall process of learning and the result of growth, we design the 'e-portfolio' which combines both learning and evaluation in order to minimize the physical constraint factors along with operating portfolio. After operating our newly designed 'e-portfolio' based on blog in order to verify it's effect, we found the meaningful changes in student's academic achievement and the positive possibility of its application to teachers. Therefore, with the operation of our suggested 'e-portfolio', we are expecting progressed and integrated portfolio education which combines the function of the learning and the evaluation.

• The Journal of Internal Korean Medicine
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• v.36 no.2
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• pp.122-152
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• 2015

Objectives: This study was designed to develop a standard tool for pattern identification of gastroesophageal reflux disease (GERD) patients. Methods: Korean and Chinese literature was selected that mentioned pattern identification of GERD. We gathered the pattern identification and their symptoms and a Chinese medical doctor proficient in Korean translated the Chinese characters into Korean. A Korean linguist then confirmed the translation results to develop a draft of the standard tool for pattern identification of gastroesophageal reflux disease (PIGERD). The final PIGERD was developed after assessment by an expert committee composed of professors from the Korean Medicine University, using the following items: inclusion of the pattern identification and its symptoms, importance of items, and validity of translation. Results: Six pattern identifications and 94 symptoms were selected from 45 references and translated into Korean. Four pattern identifications [pattern/syndrome of liver qi invading the stomach (肝胃不和), spleen-stomach weakness (脾胃虛弱), spleen-stomach dampness-heat (脾胃濕熱), and stomach yin deficiency (胃陰不足)] and 49 symptoms were then selected through the Delphi method by the expert committee. The final standard PIGERD tool was completed after the assessment of translation validity and reflection of individual opinions by the expert committee. This tool consists of 40 items including tongue and pulse diagnosis. The weighted value was also computed from assessment of the importance of items. Conclusions: We developed a standard tool for pattern identification of gastroesophageal reflux disease (PIGERD) to clarify the pattern identification of patients with gastroesophageal reflux disease for standardized diagnosis.

• Archives of Plastic Surgery
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• v.33 no.1
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• pp.75-79
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• 2006

The upper and lower lateral cartilages provide the key to the lower cartilaginous portion of the nose. Lifting the cartilages is essential procedure for correction of unilateral cleft lip nose deformity. After correction of cleft lip nose deformity, authors used acoustic rhinometry (AR) to compare the lower nasal cavity of cleft side with non-cleft side. AR is a well known new, non-invasive diagnostic technique in which nasal geometry is assessed by means of acoustic reflection. From June 1996 to January 2004, we performed acoustic rhinometric analysis after correction of unilateral cleft lip nose deformity. This study involved 40 children of age ranged from 3 months to 8 years. Subjects were divided into the group of incomplete unilateral cleft lip nose deformity(20 subjects), and the group of complete unilateral cleft lip nose deformity(20 subjects). Results show that lower nasal cavity volume between non-cleft side and cleft side has no difference, and better results were obtained when nasal molding prong was applied at cleft side nostril. The results between incomplete type and complete type have no significant difference. In conclusion, AR is an effective method to calibrate cross sectional area and nasal cavity volume of unilateral cleft lip nose deformity, and furthermore effective in comparing the volume of cleft side with non-cleft side after unilateral cleft lip nose deformity correction with lifting the lower lateral cartilages to the upper lateral cartilages.