• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.38.3-38.3
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• 2021

We are developing an optomechanical design of infrared telescope for the CubeSat and Unmanned Aerial Vehicle (UAV) which adapts the Linear Astigmatism Free- Three Mirror System in the confocal off-axis condition. The small entrance pupil (diameter of 40 mm) and the fast telescope (f-number of 1.9) can survey large areas. The telescope structure consists of three mirror modules and a sensor module, which are assembled on the base frame. The mirror structure has duplex layers to minimize a surface deformation and physical size of a mirror mount. All the optomechanical parts and three freeform mirrors are made from the same material, i.e., aluminum 6061-T6. The Coefficient of Thermal Expansion matching single material structure makes the imaging performance to be independent of the thermal expansion. We investigated structural characteristics against external loads through Finite Element Analysis. We confirmed the mirror surface distortion by the gravity and screw tightening, and the overall contraction/expansion following the external temperature environment change (from -30℃ to +30℃).

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.181-194
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• 1999

Both the chemical components and the physical and mechanical properties of the compacted and undisturbed weathered granite soils were estimated to investigate the influences of the degree of weathering and saturation on the shear strength. The weathered granite soils used in this study were taken from six different sites in Korea. The results showed that the shear strength of weathered granite soil decreased with increasing the degree of weathering and saturation. Under the normal stresses less that 40kPa, the shape of Mohr-Coulomb failure envelope followed curved or hyperbolic relationship and a half of cohesion value obtained by the common shear test was observed. Using the Sueoka's method, the values of CWI were ranged from 21.5 to 31.26 which can be characterized as a completely weathered granite soil. Large decrease in shear strength and remarkable variation in dilatancy were observed in saturated granite soil compared to unsaturated soil. It was also found that the shear strength of undisturbed weathered granite soil of Pungam site can be expressed approximately by the equation of ${(\tau)_{sat}= 1.0(\tau)_{unsat}-12.48}$ and this equation can be extended to the other sites considered in this study.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.454-459
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• 2009

In order to identify the effect of soil salinity on saturated hydraulic conductivity in reclaimed paddy soils, we established the soil columns uniformly packed with soils collected at every 20 cm up to 60 cm from the reclaimed paddy area with high and low salinity which has been cultivated rice plants for the last 30 years. The soil textures were sandy loam and loamy sand for high-salinity and low-salinity topsoils, respectively. For high-salinity and low-salinity soils the ECes were ranged from 25.2 to $37.8dS\;m^{-1}$ and 3.0 to $3.4dS\;m^{-1}$ while the ESPs were ranged from 7.70 to 20.84 % and from 5.12 to 11.33 %, respectively. The bulk densities of the soil columns were adjusted to $1.15{\pm}0.03g\;cm^{-3}$. The results of the soil column experiments shows that the stabilized saturated hydraulic conductivity of low-salinity soil was $0.62cm\;hr^{-1}$ at the topsoil while there were little water flow at the bottom of the soil columns packed with high-salinity soils. After removal of $Na^+$ ions with $1N\;NH_4OAc$ from the high-salinity soil, Ksat of the saline soil was drastically increased to $0.23cm\;hr^{-1}$. Soil columns of high-salinity topsoil treated with four different concentration of NaCl influent after removal of soluble and exchangeable cations with $1N\;NH_4OAc$ show Ksat in the range of $0.1{\sim}0.15cm\;hr^{-1}$ and the Ksat slightly decreased as the concentration of NaCl influent was increasing. Conclusively, we could assume that $Na^+$ can be significantly contributed to the saturated hydraulic conductivity in newly reclaimed sandy soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.81-88
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• 2007

The evaluation of soybean germplasm has mainly been carried out by morphological characters at Genetic Resources Division, Rural Development Administration (RDA). However, this information has been limited serving a diverse information for user and effectively managing the soybean germplasm. To resolve this problem, soybean collection conserved at RDA gene bank was profiled using nine soybean SSR (Simple Sequence Repeat) markers. Soybean SSR allele was confirmed using genescan and genotyper softwares of automatic sequencer for accurate genotyping of each accession and continuous accumulation of data. SSR profiling of soybean germplasm has been carried out from 2,855 (Satt458) to 4,368 (Satt197) accessions by locus. The number of allele revealed 267 with an average of 29.6 in total accession, and varied from a low of 21 (Satt532 and Satt141) to a high of 58 (Sat_074). Although the number of accessions of wild soybean is less than that of soybean landraces, Korean wild soybean is more variable than other soybean landraces populations in total number of alleles. However, Korean soybean landraces were more variable than Korean wild soybeans in 5 loci. In the allele frequency, wild soybean accessions showed an even distribution in all alleles and higher distribution in low ladder than in high ladder. Also, Korean soybean landraces revealed a high condensed frequency in Satt286 (202 bp, 232 bp), Chinese soybean landraces in Satt197 (171 bp) and Satt458 (173 bp), and Japanese soybean landraces in Sat_074 (244 bp) and Satt458 (170 bp). These SSR profile information will be provided as indications of redundancies or omissions of accessions and can aid in managing soybean collection held at RDA gene bank. The information on diversity analysis could help to enlarge the genetic diversity of materials in breeding program, and could be used to develop a core collection of soybean germplasm.

• Journal of Plant Biology
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• v.39 no.3
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• pp.203-207
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• 1996

On the basis of karyotypic analysis performed by conventional staining and Giemas C-banding technique, cytological relationship was inferred for 21 lines of Paeonia lactiflora Pal. cultivated in Korea. It was very difficult to infer their organized karyotypic classification system using the composition of somatic chromosomes involving sat-chromosomes, relative length of chromosomes, arm ratio and karyotypic formulae by conventional staining. From the distribution and number of Giemsa C-bands on the chromosomes b and c, 21 lines can be subclassified into 5 groups. It seems that the karyotypic polymorphism is observed in 21 lines of cultivated P. lactiflora because peony mainly propagates by outbreeding.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.244-247
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• 1999

In this paper, a low voltage CMOS analog four-quadrant multiplier is presented. The proposed multiplier is composed of a pair of transconductor and lowers supply voltage down to $V_{T}$+2 $V_{Ds,sat}$+ $V_{DS,triode}$. The designed analog four-quadrant multiplier have simulated by HSPICE using 0.25${\mu}{\textrm}{m}$ n-well CMOS process with a 1.2V supply voltage. Simulation results show that the THD can be 1.28% at maximum differential input of 0.7 $V_{p-p}$././.

• Journal of Astronomy and Space Sciences
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• v.32 no.2
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• pp.145-149
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• 2015

A newly designed Tissue Equivalent Proportional Counter (TEPC) has been developed for the CubeSat mission, SIGMA (Scientific cubesat with Instruments for Global Magnetic field and rAdiation) to investigate space radiation. In order to test the performance of the TEPC, we have performed heavy ion beam experiments with the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. In space, human cells can be exposed to complex radiation sources, such as X-ray, Gamma ray, energetic electrons, protons, neutrons and heavy charged particles in a huge range of energies. These generate much a larger range of Linear Energy Transfer (LET) than on the ground and cause unexpected effects on human cells. In order to measure a large range of LET, from 0.3 to $1,000keV/{\mu}m$, we developed a compact TEPC which measures ionized particles produced by collisions between radiation sources and tissue equivalent materials in the detector. By measuring LET spectra, we can easily derive the equivalent dose from the complicated space radiation field. In this HIMAC experiment, we successfully obtained the linearity response for the TEPC with Fe 500 MeV/u and C 290 MeV/u beams and demonstrated the performance of the active radiation detector.

• Economic and Environmental Geology
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• v.39 no.1 s.176
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• pp.95-102
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• 2006

To properly interpret and define climatic warming trends of the last $100\~150$ years.; climatic changes over the past several centuries must be constrained. High resolution surface air temperatures (SATs) to reconstruct global temperature trends extend back only to the late of 19th century. Fortunately, on long time scale and over large areas, ground surface temperatures (GSTs) track SATs. GST changes penetrate into the subsurface and are recorded as transient temperature perturbation. Therefore, borehole temperatures can be used to recover climate change over the last millennium in an area; paleoclimate change inferred from borehole temperatures can be used to interpret global warming over the last century, little ice age, and medieval warm period.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.6
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• pp.847-853
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• 2016

Applications of Si have been increasingly exploited and extended to More-Moore, More-than-Moore, and beyond-CMOS approaches. Ge is regarded as one of the supplements for Si owing to its higher carrier mobilities and peculiar band structure, facilitating both advanced and optical applications. As an emerging metal-oxide device, the junctionless field-effect transistor (JLFET) has drawn considerable attention because of its simple process, less performance fluctuation, and stronger immunity against short-channel effects due to the absence of anisotype junctions. In this study, we investigated lateral field scalability, which is equivalent to channel-length scaling, in Si and Ge JLFETs. Through this, we can determine the usability of Si CMOS and hypothesize its replacement by Ge. For simulations with high accuracy, we performed rigorous modeling for ${\mu}_n$ and ${\mu}_p$ of Ge, which has seldom been reported. Although Ge has much higher ${\mu}_n$ and ${\mu}_p$ than Si, its saturation velocity ($v_{sat}$) is a more determining factor for maximum $I_{on}$. Thus, there is still room for pushing More-Moore technology because Si and Ge have a slight difference in $v_{sat}$. We compared both p- and n-type JLFETs in terms of $I_{on}$, $I_{off}$, $I_{on}/I_{off}$, and swing with the same channel doping and channel length/thickness. $I_{on}/I_{off}$ is inherently low for Ge but is invariant with $V_{DS}$. It is estimated that More-Moore approach can be further driven if Si is mounted on a JLFET until Ge has a strong possibility to replace Si for both p- and n-type devices for ultra-low-power applications.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.1027-1035
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• 2021

We presents a design of 3U cubesat MIMAN (Monochrome imaging for monitoring aerosol by nano-satellite) for aerosol monitoring mission with high spatial resolution. The main objective of MIMAN mission is to take images of aerosols around Korea and to provide auxiliary data for GK 2B cloud masking. For this mission, we derived mission requirements and constraints for the MIMAN mission. We designed the mission architecture and concept of operations. To reduce risk factors in space operation, we considered the safety of the communication. In every operation modes, UHF communication is available so that the cubesat can operate based on the ground commands. So, we can handle every problem at the ground station during mission operations. Based on the mission and concept of operations, we confirmed that the system design satisfied the system requirements. We designed the system interface considering data flow of each hardware, and evaluated the safety of the system with system budget analysis.