• Publications of The Korean Astronomical Society
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• v.24 no.1
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• pp.53-64
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• 2009

MIRIS is the main payload of the STSAT-3 (Science and Technology Satellite 3) and the first infrared space telescope for astronomical observation in Korea. MIRIS space observation camera (SOC) covers the observation wavelength from $0.9{\mu}m$ to $2.0{\mu}m$ with a wide field of view $3.67^{\circ}\times3.67^{\circ}$. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200 K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI (Multi Layer Insulation) of 30 layers, and GFRP (Glass Fiber Reinforced Plastic) pipe support in the system. Optomechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform Galactic plane survey with narrow band filters (Pa $\alpha$ and Pa $\alpha$ continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.1006-1014
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• 2000

Hemisphere type Luneberg lens antenna with a reflector(frequency : 9.375 GHz, -3 dB beam width 6$^{\circ}$, diameter 30.3 cm(about 10 A), which is miniaturized and lightweightized by attaching a reflector on a section of half the Luneberg lens antenna, is designed and fabricated on the basis of Luneberg lens antenna from which easy beam pointing is acquired only by movement of 1st radiator. Measurement shows -3dB beamwidth is 6.1$^{\circ}$ in case of E-plane and 5.5$^{\circ}$ in case of H-plane. These are good agreements with expected value. Gain of this antenna is 26dBi(Aperture efficiency for uniform distribution : $\pi$ = 44.97%) which is greater than that of 1st radiator(Rectangular microstrip antenna) by 20.4 dB. And, after calculating the approximated pattern of the 1st radiator, far-field pattern, whose source is the second aperture source farmed from the approximated pattern of the 1st radiator is computed. Comparing this far-field pattern with the expected pattern, a (relatively) good agreement is observed. Circular polarization Luneberg lens antenna is also manufactured by making 1st radiator so that it has the characteristics of LHCP and RHCP radiation. The results are as followings : -3 dB beamwidth 5.8$^{\circ}$ , side lobe level -15.3 dB, isolation between LHCP and RHCP radiation 2543, axial ratio 2 dB bandwidth about 1.4 GHz(14.9%).

• Journal of the Optical Society of Korea
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• v.15 no.2
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• pp.174-181
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• 2011

An airborne sensor is developed for remote sensing on an aerial vehicle (UV). The sensor is an optical payload for an eletro-optical/infrared (EO/IR) dual band camera that combines visible and IR imaging capabilities in a compact and lightweight package. It adopts a Ritchey-Chr$\'{e}$tien telescope for the common front end optics with several relay optics that divide and deliver EO and IR bands to a charge-coupled-device (CCD) and an IR detector, respectively. The EO/IR camera for dual bands is mounted on a two-axis gimbal that provides stabilized imaging and precision pointing in both the along and cross-track directions. We first investigate the mechanical deformations, displacements and stress of the EO/IR camera through finite element analysis (FEA) for five cases: three gravitational effects and two thermal conditions. For investigating gravitational effects, one gravitational acceleration (1 g) is given along each of the +x, +y and +z directions. The two thermal conditions are the overall temperature change to $30^{\circ}C$ from $20^{\circ}C$ and the temperature gradient across the primary mirror pupil from $-5^{\circ}C$ to $+5^{\circ}C$. Optical performance, represented by the modulation transfer function (MTF), is then predicted by integrating the FEA results into optics design/analysis software. This analysis shows the IR channel can sustain imaging performance as good as designed, i.e., MTF 38% at 13 line-pairs-per-mm (lpm), with refocus capability. Similarly, the EO channel can keep the designed performance (MTF 73% at 27.3 lpm) except in the case of the overall temperature change, in which the EO channel experiences slight performance degradation (MTF 16% drop) for $20^{\circ}C$ overall temperate change.

• Journal of Life Science
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• v.23 no.4
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• pp.602-608
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• 2013

The multifaceted role of chronic inflammation in multistep carcinogenesis has been extensively investigated and well documented. Periodontal diseases are associated with multifactorial agents, including bacterial endotoxins and the generation of an inflammatory response, indicating that poor oral health is associated with a variety of systemic diseases. The association between poor oral health, chronic inflammation, smoking, and increased alcohol consumption as risk factors for tumorogenesis is well established. More recently, associations between oral health and tooth loss and gastric, lung, and pancreatic cancers have been explored, with some studies pointing to smoking and oral health as a common link with an increased risk for malignant disease. In addition, epidemiological studies consistently indicate increased risks of various cancers with periodontal disease or poor oral condition caused by oral bacteria, which may activate alcohol- and smoking-related carcinogens locally or act through chronic inflammation. Appropriate oral care is vital in preventing cancer, as well as many other diseases. Thus, research on the correlation between oral care and periodontal inflammation and cancer is required. This review highlights the association between oral health and the risk of certain malignancies, such as periodontal disease-associated chemoprevention of inflammation" in this sentence.

• Journal of Music and Human Behavior
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• v.11 no.1
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• pp.21-37
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• 2014

The significant role of joint attention in the development of children with autism spectrum disorder (ASD) has highlighted the importance of early intervention. With the emphasis on the effective cueing and reinforcer for orienting to social stimuli in improving responding to joint attention (RJA) of children with ASD, the use of musical cue was hypothesized. This study aimed to examine the occurrence of RJA behaviors depending on the attentional cue, which differed in the level of information and type of auditory modality. Nine children with ASD participated in this study. The use of eight different joint attention cues were analyzed in terms of the frequency and accuracy of RJA behaviors elicited. The results of the study showed that RJA behaviors occurred more frequently with musical cues than with verbal cues and the mean accuracy rate of RJA was higher with musical cues (p = .047). Musically delivered eliciting and directing cues accompanied with pointing elicited the highest attentional shift and RJA accuracy. The significant increases in RJA with the use of musical cues indicated that incorporating musical elements into an attentional cue may provide more accurate cue information, enough to improve RJA behaviors of children with autism.

• The Korean Journal of Air & Space Law and Policy
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• v.28 no.2
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• pp.145-181
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• 2013

General aviation is an integral part of civil aviation and involves the widest range of aviation segments except commercial aviation. Featured with different operational procedures and practices to satisfy the economic needs and safety requirements of a sovereign state, general aviation tends to be regulated by an individual state. The last three decades have seen exponential growth of commercial air transport in China, but its general aviation sector has remained disproportionally underdeveloped. With the deepening of the reform of low-altitude airspace, the sector is poised for a radical change and rapid growth. However, legislation governing general aviation activities in China is distorted causing inconsistency and confusions in their application and implementation. This paper aims to analyse China's prevailing legislation regulating general aviation activities. It first discusses the various definitions adopted by ICAO and its member states and reviews the development of general aviation in the US, EU, Australia and China. It then examines the sources of China's general aviation laws, e.g. Chicago Convention and its annexes, and Chinese domestic legislature which covers legislation, laws, directives, rules and procedures. The paper continues to analyse and establish the deficiencies of its prevailing legal framework by pointing out the following: variation of definitions in different regulations, inconsistency of principles in existing laws and regulations, legal vacuum concerning government subsidy, environment protection, safety and security, and other operational areas such as aerial club, sightseeing, and search and rescue. In this process, the paper argues that a coherent, consistent and systematic legal framework is required in order to ensure fair competition and safety for a healthy, progressive and sustainable general aviation growth. Suggestions for rectification and improvement are proposed.

• Spatial Information Research
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• v.7 no.2
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• pp.159-173
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• 1999

GIS has been regarded as one of important tools or methodologies for various geoscience applications. Recently, spatial data integration schemes for site-specific or field-specific thematic mapping are newly developed and utilized. However, these kinds of approaches are somewhat insufficient quantitative assessment of integrated layers towards known targets in-detailed . Moreover, GIS analysis scheme is rarely extended to scientific approaches. In this study, simple approach of Multi-Buffer Zone Analysis , related to GIS analystical aspect, is addressed and an actual application for predicting or favorable mapping of mineral occurrences, one of GIS-based geoscientific approaches, is performed, As for geo-processing in GIS itself, this scheme can be regarded as extension or adaptiation of cell-based buffering or proximity analysis to geoscientific data interpretation. This study is based on rationale that surface geological pattern around primitives such as a point, a line, or a polygon in GIS, representing significant geological features, can be efficiently utilized to delineate complex geological behaviors or events, especially handling multiple dta sets originated from multiple sources such as airborne geophysical/radiometric exploration, field survey, and even a classified image of remote sensing. Conclusively, this methodology associated wit GIS is though to be helpful to analyze the spatial pattern of multiple data, pointing given sources, and is expected to effectively utilize for exploratory analysis of cell-based resultant layer integrated with complex or different data sources.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.213-216
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• 2013

This paper presents a combination of linear Fresnel lenses optimized for ${\times}25$ solar concentration. The combined lens consists of $5{\times}5$ linear Fresnel lenses. Each Fresnel lens is of $10{\times}10$ mm and optimized to tilt the incoming light onto a solar cell of the same size. All of the optimized Fresnel segments have the same pattern height of 35 ${\mu}m$, draft angle of $4^{\circ}$, and edge groove round of 1 ${\mu}m$ but with different facet angles varying from $14.1^{\circ}$ to $31.2^{\circ}$. The solar concentrating efficiency of the combination is shown to be over 80% and more robust than a conventional single ${\times}25$ circular Fresnel lens in terms of pointing misalignment and manufacturing errors. A sensitivity analysis finds that the edge groove round should be kept as small as machining allows since the concentrating efficiency drops ~5% per 1 ${\mu}m$ increase of the edge groove.

• Management & Information Systems Review
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• v.30 no.4
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• pp.475-509
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• 2011

Taking 195 Korean businesses and sorting them out according to the unit types, this study looks into how flexibility strategy in labor market, which consists of numerical flexibility and functional flexibility, takes effect on the organization's outcome variable, which in turn consists of productivity, labor-management cooperation, and job security. In addition, the present study analyzes the role of labor union's moderating effect on the relationship among labor market flexibility, labor-management cooperation, and job security. It is found out as a result that numerical flexibility has no meaningful relation with productivity, labor-management cooperation, and job security, while functional flexibility has a considerably positive relation with them. This result confirms the importance of functional flexibility of business strategy in labor market. The West has continuously insisted the importance of functional flexibility, pointing out problems of numerical flexibility. On the other hand, considering that this study has confirmed functional flexibility's meaningful relation, while it has not found out numerical flexibility's negative relation, it is necessary to study further on the relationship between these two kinds of flexibility. The result of analysis on the role of union power's moderating effect confirms only the union power's interaction effect in the relation between numerical flexibility and labor-management cooperation. The possibility of union's opportunistic behavior can be detected in this result.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.7
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• pp.978-984
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• 2018

Structural equation modeling is pointing to statistical procedures that simultaneously perform path analysis and confirmatory factor analysis. Today, this statistical procedure is an essential tool for researchers in the social sciences. There are as AMOS, LISREL and PLS representative tools that can perform structural equation modeling analysis. AMOS provides a convenient graphical user interface for beginners to use. PLS has the advantage of not having a constraint on normal distribution as well as a graphical user interface. Therefore, we compared and analyzed the three most commonly used tools (applications) in social sciences. Based on structural equation modeling, confirmatory factor analysis was performed using the IBM AMOS Ver. 23, the LISREL 8.70 and the SmartPLS 2.0. The comparative results show that LISREL has the highest explanatory power of dependent variables than other analytical tools. The path coefficients and T-values presented by the analysis results showed similar results for all three analysis tools. This study suggests practical and theoretical implications based on the results.