• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.232-239
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• 2001

Young Jong Grand Bridge is approach traffic road of New Inchon International Airport which covers hub airport function in northeast asia. The total span length of this bridge is $4,420{\cal}m$ and this main bridge type is, the first in the world, Double Deck Self Anchored Suspension Bridge, designed as double deck systems to be arranged by road and railroad. Approach bridges to be connected with main span also are composed double deck steel truss and steel box girder to consider a continuity with this span. Our company erected $1,375{\cal}m$(about 60,000tons) of double deck steel truss bridge type which is composed by 6 traffic lane on upper deck and 4 traffic lane and Double track railroad on lower deck. The original installation method of this bridge was planed to install about 75 meters bridge blocks to use floating crane, after temporary bent was constructed between permanent piers. But this method which had to construct many temporary bents in the sea had the matter that construction periods can become lengthen and construction cost can be risen. To overcome the uncertainty to ensure high qualify of bridge and economic project execution, our company developed new bridge erection method to assure both quality control and economic construction work. The new erection method which was developed by us was one that could transport and install long bridge block, $120{\cal}m$ unit at a time and that temporary bent was not required. We hope that this paper is used as technical data which will erect bridge in the western sea and others marine region.

• Korean Journal of Optics and Photonics
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• v.22 no.6
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• pp.262-268
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• 2011

MIRIS(Multi-purpose Infra-Red Imaging System) is the main payload of the STSAT-3(Korea Science and Technology Satellite. 3), which is being developed by KASI(Korea Astronomy & Space Institute). EOC(Earth Observation Camera), which is one of two infrared cameras in MIRIS, is the camera for observing infrared rays from the Earth in the range of $3{\sim}5{\mu}m$. The optical system of the EOC is a Cassegrain prescription with aspheric primary and secondary mirrors, and its aperture is 100mm. A ring type flexure supports the EOC primary mirror with pre-loading in order to withstand expected load due to the shock and vibration from the launcher. Here we attempt to use the same mechanism by which a retainer supports the lens. Through opto-mechanical analysis it was confirmed that the EOC primary mirror is effectively supported.

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.423-427
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• 2005

In this paper, we propose easily tooling method for Seidel third order aberration, which are not well utilized in actual design process due to the complication of mathematical operation and the difficulty of understanding Seidel third order aberration theory, even though most insightful and systematic means in pre-designing for the initial data of optimization. First, using paraxial ray tracing and Seidel third order aberration theory, spherical aberration coefficient is derived for a two-mirror system with a finite object distance. The coefficient, which is expressed as a higher-order nonlinear equation, consists of design parameters(object distance, two curvatures, and inter-mirror distance) and effective focal length(EFL). Then, the expressed analytical equation is solved by using a computer with numerical analysis method. From the obtained numerical solutions satisfying the nearly zero coefficient condition($<10^{-6}$), linear fitting process offers a linear relationship called the curvature linear equation between two mirrors. Consequently, this linear equation has two worthy meanings: the equation gives a possibility to obtain initial design data for optimization easily. And the equation shows linear relationship to a two-mirror system with a finite object distance under the condition of corrected third order spherical aberration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.2
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• pp.189-195
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• 1993

This study was conducted to obtain the .basic informations for developing soybean varieties and mechanizing cultivation at the Crop Experiment Station, Rural Development Administration, Suwon, Korea in 1990. Two determinate soybean varieties, Hwangkeurnkong and Jangyeobkong, and two indeterminate soybean varieties, Clark and Williams were planted at three planting densities (33,22,16 plants / $m^2$). Number of branches and number of nodes on branches per unit area ($m^2$) were greater in determinate varieties than in indeterminate ones, and number of nodes on mainstem were greater in indeterminate varieties than in determinate ones. The higher planting density increased those characters. Seed weight per unit area ($m^2$) was higher in determinate varieties than in indeterminate ones, and it was great at the higher planting density. Indeterminate varieties showed greater mainstem dependence rate for yield components than determinate ones did. Harvest index was higher in indeterminate varieties than in determinate ones. The lower planting density increased harvest index. Stem dry weight per unit area($m^2$) was greater in determinate varieties than in indeterminate ones, and it was greater at the higher planting density. Variations among plants were great in the order of branch-related yield characters > total plant-re-lated yield characters > mainstem-related yield characters > morphological characters of mainstem and 100 seed weight. Difference between determinate and indeterminate varieties was significant in branch-related characters. Indeterminate varieties showed greater variations than determinate ones did in branch-related yield characters at different planting densities.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.74-79
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• 1999

Langasite($La_3Ga_5SiO_14$) is a new piezoelectric material which is similar to quartz, LN($LiNbO_3$) and LT($LiTaO_3$) in its acoustic behavior. In this study, pure Langasite and Lagnasite family groups were synthesized by the solid state reactions in air. The diffusion species for synthesis were investigated and the sintered body was studied on dielectric property to comparison of characteristics. Also, Langasite single crystals were grown by self-designed Czochralski system and characterized.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.1
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• pp.50-54
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• 1999

Plasma display panel is a potential candidate for HDTV, due to the fact that the screen size can easily be increased by a thick film technology. In this study, transparent dielectric materials which satisfied the requirements of dielectrics for PDP was developed using lead alumina borosilicate glasses. The Paste which had thixotropic behavior suitable for screen printing was made of this glass composition. the paste became more thixotropic as the particle size decreased. After firing, the cross sectional area of the thick film was analyzed by SEM. The voids in the thick film were removed using bimodal particle system. The dielectric thick film showed good adhesion characteristics.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.626-631
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• 1997

AlSiCa powders were prepared from the domestic Hadong Kaolin ($Al_2O_3{\cdot}2SiO_2{\cdot}2H_2O$). As a result of the reaction of Hadong Kaolin and carbon powder at reducing atmosphere, $Al_2O_3{\cdot}SiC$ composite started to form at $1300^{\circ}C$ and completed at $1400^{\circ}C$. The optimum amount of carbon was 1:4 in mole ratio. It was found that only bright-green $\beta-SiC$ phase forms when the mixture was packed without carbon powder in alumina crucible.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.70-70
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• 2011

사장교의 적용지간이 증가하여 초장대화하면서 구조안전성을 확보하기 위한 다양한 노력이 시도되고 있다. 본 연구에서는 현재까지 시도된 적이 없는 주경간 1,200m 사장교의 내풍안정성을 검토하기위하여 3차원공탄성 모형을 제작하고 풍동실험을 수행하였다.(그림1 참조) 실험대상 구조물은 내풍안정성 증대를 위해 유선형 박스거더를 채용하고 케이블이 거더와 함께 비틀림에 저항하도록 2면 케이블을 적용하였다. 구조적인 측면에서는 보강형 자중감소를 위해 전경간을 강박스로 계획하였으며 측경간에 부반력제어를 위한 Counter Weight을 적용하였다. 실험대상 구조물은 완성계, 가설계95%, 가설계50%, 가설계45%로 모형을 해체하면서 진행하였고 가설단계 별로 내풍케이블의 수량과 형상을 달리하여 내풍안정성 개선효과를 확인하고자 하였다. 3차원 풍동실험 결과 완성계에서 교량의 안전성에 심각한 문제를 발생시킬 수 있는 와류진동, 플러터, 버페팅과 같은 유해한 진동현상이 발견되지 않았으며, 시공중 내풍안정성 확보를 위하여 대상교량에 내풍케이블을 설치하고 내풍케이블의 수량 및 배치형상에 따른 진동제어 효과를 검토하였다. 본 실험은 현재 풍동실험 요소기술을 이용하여 1,200m급 사장교 풍동실험을 수행하였고 이에 따라 교량이 초장대화 되면서 스케일다운에 따른 보강형질량, 케이블 간격 등 실험모형 제작상 문제점을 확인 할 수 있었으며 이러한 경험을 토대로 향후 1,000m 이상급 초장대 사장교 내풍설계를 위한 기초자료로 활용이 가능할 것으로 사료된다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.191-196
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• 1997

The micro-defects in the SiC single crystals were characterized using a variety of the microscopic techniques (OM, TEM, AFM). It was observed that the hexagonal-plate precipitates and the longitudinal micropipes are present inside of SiC wafers. TEM results exhibited that there are amorphous phase in the SiC wafer and the phase were originated from the formation of the nonstoichiometric $Si_{1-x}_xC_x$ phases during growth process.

• Electronics and Telecommunications Trends
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• v.35 no.4
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• pp.53-64
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• 2020

The terahertz (THz) region lies in between the millimeter and infrared spectral bands. A THz wave has the characteristics of non-invasiveness and non-ionization due to low photon energies, while having high penetrability in dielectrics. In addition, since the resonance frequencies of various molecules are included in the THz band, research on the application of spectral analysis and non-destructive testing has been widely studied. Towards this end, the research and development of THz detectors has become increasingly important in order to assess their applications in different areas such as astronomy, security, industrial non-destructive evaluations, biological applications, and wireless communications. In this report, we summarize the operating principles, characteristics, and utilization of various broadband technologies in THz detection devices. Further, we introduce the development status of our Schottky barrier diode technology as one of the broadband THz detectors that can be easily adopted as direct detectors in many fields of applications.