• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.469-479
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• 2014

N-RTK(Network based RTK) methods are able to improve the accuracy of GNSS positioning results through modelling of the distance-dependent error sources(i.e. primarily the ionospheric and tropospheric delays and orbit errors). In this study, the comparison of the TTFF(Time-To-Fix-First ambiguity), accuracy and discrepancies in horizontal/vertical components of N-RTK methods(VRS and FKP) with the static GNSS at 20 Unified Control Stations covering Incheon metropolitan city area during solar storms(Solar cycle 24 period) were performed. The results showed that the best method, compared with the statics GNSS survey, is the VRS, followed by the FKP, but vertical components of both VRS and FKP were approximately two times bigger than horizontal components. The reason for this is considered as the ionospheric scintillation because of irregularities in electron density, and the tropospheric scintillation because of fluctuations on the refractive index take the place. When the TTFF at each station for each technique used, VRS gave shorter initialization time than FKP. The possible reasons for this result might be the inherent differences in principles, errors in characteristics of different correction networks, interpolating errors of FKP parameters according to the non-linear variation of the dispersive and non-dispersive errors at rover when considering both domestic mobile communication infra and the standardized high-compact data format for N-RTK. Also, those test results revealed degradation of positing accuracy, long initialization time, and sudden re-initialization, but more failures to resolve ambiguity during space weather events caused by Sunspot activity and solar flares.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.178-178
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• 2016

최근 Zn-Mg 합금 박막은 고내식성의 합금상 형성, 치밀한 부식생성물의 부식억제 등으로 인해 순수한 Zn 박막 및 기타 Zn 계 합금 박막 대비 우수한 내식성을 나타난다고 보고되고 있다. 그러나 여러 문헌에서 보고된 Zn-Mg 박막 각기 다른 결정구조, 미세조직을 나타내며, 이는 Zn-Mg 박막이 낮은 융점을 나타내기 때문에 박막 합성 공정 중에 발생하는 열량에 따라 Zn-Mg 박막의 결정구조, 미세조직 등이 변화한 것으로 판단된다. 본 연구에서는 Zn-Mg 박막의 결정구조에 따른 내식특성을 평가하기 위하여 비대칭 마그네트론 스퍼터링 공정 중 합성온도를 제어하며 Zn-Mg 박막을 합성하였으며 그에 따른 박막의 결정구조, 내식성에 관해 연구하였다. Zn-Mg 박막은 10wt.% Mg 합금 타겟을 사용하였으며, 합성 온도는 상온에서 최고 $150^{\circ}C$로 제어하였다. Zn-Mg 박막의 결정구조, 미세조직은 X선 회절 분석기 (XRD)와 전계방출형 주사전자현미경 (FE-SEM)을 사용하여 분석하였으며, 동전위 분극시험을 통해 결정구조에 따른 Zn-Mg 박막의 내식성을 분석하였다. 상온에서 합성한 Zn-Mg 박막은 비정질의 결정구조가 형성되었으며, 상온이상 $50^{\circ}C$이하에서는 결정질의 Zn 상과 비정질상이 공존하는 Zn-Mg 박막이 합성되었다. 또한 $100^{\circ}C$이상에서는 Zn, $Mg_2Zn_{11}$, $MgZn_2$ 상이 공존하는 결정질의 Zn-Mg 박막이 합성되었다. 상온에서 합성된 Zn-Mg 박막의 경우 급냉이 이루어지는 스퍼터링 공정의 특성상 비정질의 결정구조가 형성되었으나, Zn는 융점이 낮아 상온부근에서도 재결정이 이루어지기 때문에 $50^{\circ}C$ 이하의 낮은 온도에서 합성하여도 결정질의 Zn 상이 형성되었다. $Mg_2Zn_{11}$, $MgZn_2$ 과 같은 Zn와 Mg의 합금상의 경우 형성과정에서 일정 수준의 열이 요구되기 때문에 낮은 온도에서는 형성이 억제되고 일정 이상의 온도에서 형성되었다. FE-SEM 분석 결과를 통하여 $50^{\circ}C$ 이하의 낮은 온도에서 합성한 Zn-Mg 박막은 치밀한 미세구조를 나타내었으며, $100^{\circ}C$이상에서 합성한 Zn-Mg 박막의 미세구조는 밀도가 비교적 낮은 구조임을 확인하였다. 3.5% NaCl 수용액에서의 동전위 분극시험 결과 낮은 온도에서 합성한 Zn-Mg 박막이 고온에서 합성한 Zn-Mg 박막 대비 치밀한 구조가 형성되었기 때문에 우수한 내식성을 나타내었다.

• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.1-7
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• 2006

Anatomical and physical properties of kenaf grown in Chuncheon, Korea were investigated using light and scanning electron microscopy and X-ray diffraction method. Bast fiber, phloem ray, cortex parenchyma cell and sieve tube member were observed in phloem, and vessel element, fiber and ray in xylem. Solitary and multiple radial pores in xylem existed. The cell types of ray parenchyma in radial section were procumbent, upright and square cells. The length of bast fiber increased with increasing the growth period. The length of wood fiber was 0.74~0.82 mm, but was not significantly different between the growth period and stem height. Relative crystallinity was 53~74% in phloem and 43~58% in xylem. Cellulose crystallinity width was 2.68~3.24 nm in phloem and 2.46~2.95 nm in xylem. The green moisture content and green density increased but basic density decreased with increasing the stem height.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.50-56
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• 2006

We investigated the adsorption of benzene and pyridine on $Si(5\;5\;12)-2\times1$ at 80 K by using variable-low temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The benzene molecule most strongly binds to two adatoms on the D3 and D2 units in a tilted butterfly configuration, which consists of $di-\sigma$ bonds between C atoms and Si adatoms and two C=C double bonds in the benzene molecule Pyridine molecules interact with adatom(s) on the D2 and D3 units through both Si-N dative bonding and $di-\sigma$ bonds. The dative bonding through the lone pair electrons of N atom produces a vertical configuration (pyridine-like), which is more stable than $di-\sigma$ bonds $Di-\sigma$ bonds can be formed either through Si-N1 and Si-C4 or Si-C2 and Si-C5.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.2
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• pp.25-35
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• 1997

오늘날 열대림 면적의 급격한 감소, 지구온난화등 지구환경 보전의 관점에서 이들 목재이외의 자원의 활용 및 양마와 같은 새로운 비목재자원 개발의 중요성이 재인식되기에 이르렀으며, 이 가운데서 양마는 생장이 라르고 수확량이 크며, 목질부의 단섬유는 물론 긴 섬유장을 가진 인피부섬유로 구성되어 있고, 실리카함량도 매우 적어, 특히 산림자원이 부족한 개발도상국에서 펄프.제지용 자원으로서 주목되고 있다. 양마가펄프.제지용자원으로서 오늘날과 같은 세계적 주목을 받게 된 것은 미국 농무성 북부지역연구센타 에서 이루어진 “새로운 섬유작물”에 관한 기초연구에서 양마가 제지용 섬유작물로서 높이 평가되고 있다. 양마의 경우 인피부는 비교적 리그닌함량이 적고, 목질부는 활엽수재에 가까운 리그닌을 함유하고 있는데다, 섬유형태에 있어서도 인피부와 목질부간에 큰 차이가 발견된다. 본 연구에서는 양마를 중성아황산법으로 전처리하여 제조한 반화학펄프로 부터 제조한 종이의 광학적 성질을 검토하였다 펄프의 광학적 성질은 원료의 화학적 조성,섬유의 형태, 부위.화학적 처리정도, 원료의 저장기간 및 충전제의 첨가에 따라 크게 영향을 받았다. 장섬유와 낮은 리그닌함량을 가진 전간부 펄프시트는 불투명도가 낮았으며, 목질부 펄프로부터 상대적으로 밀도가 다소 높고, 불투명도도 높은 종이를 만들 수 있었다. 펄프원료의 저장기간이 백색도를 낮추었으며, 불투명도에는 그다지 영향하지 않았다. 약품전처리 및 표백이 백색도 및 불투명도에 크게 영향하였고, 특히 충전제 첨가로 광산란을 증가시켜 불투명도가 높은 종이를 제조할 수 있었다.6. CL종의 난황콜레스테롤 수준에 대한 계란의 일령 상호간에는 전체적으로 상호간에 차이가 없었다. 7. 26주령시 혈중콜레스테롤 수준은 CL종이 다른 두 육계종들 보다 유의적 (P$\leq$0.05)으로 높았다. 8. 성별간 혈중콜레스테롤 수준의 차이는 CL종, BR1 및 BR2 중에서 CL종에서만 나타났으며, 수컷은 암킷보다 혈액 100 mL당 약 90 mg이 낮았다.구체적인 생화학적인 연구가 이루어져야 될 것으로 여겨진다.야 할 것으로 사료된다. 냉장 저장을 하고 저장기간이 길어질 경우는 냉동저장을 사용하는 것이 바람직하다고 생각된다.S, FOS나 말티톨로 대체된 스폰지 케익은 설탕 100% 사용한 케익과 비교하여 크게 나쁘지 않거나 휠씬 나은 특성을 보이므로 스폰지 케익 제조에 그들의 이용이 가능함을 확인하였다.thione 같은 다른 항산화제의 절약 효과, CYP2El의 유도 저하를 통하는 것으로 생각되며 그중 어떤 것에 가장 큰 영향을 받는 지는 아직 알려지지 않았고 더욱 많은 연구가 요구된다.우와 사료에 $\omega$3계 지방산 급원을 첨가, 동물에게 이행시켜 $\omega$3계 지방산 강화식품을 제조하는 두 가지 방법이 있을 수 있는데 전자는 통조림, 과자, 건강보조식품류에 다용되며 후자는 다양한 기능성 축산식품에 활용되고 있다. $\omega$3계 지방산 강화 축산식품에는 돼지고기, 우유, 치이즈, 계란, 분유, 햄 등 다양한 제품에 활용, 개발되고 있으며 최근에는 이러한 식품 개발에 더욱 박차가

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.327-332
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• 2011

Plasma polymerized styrene (ppS) thin films were prepared on ITO coated glass substrates for a MIM (metal-insulator-metal) structure with thermally evaporated Au thin film as metal contact. Also the ppS thin films were applied as organic insulator to a MIS (metal-insulatorsemiconductor) device with thermally evaporated pentacene thin film as organic semiconductor layer. After the I-V and C-V measurements with MIM and MIS structures, the ppS revealed relatively higher dielectric constant of k=3.7 than those of the conventional poly styrene and very low leakage current density of $1{\times}10^{-8}Acm^{-2}$ at electric field strength of $1MVcm^{-1}$. The MIS structure with the ppS dielectric layer showed negligible hysteresis in C-V characteristics. It would be therefore expected that the proposed ppS could be applied as a promising dielectric/insulator to organic thin film transistors, organic memory devices, and flexible organic electronic devices.

• Journal of Energy Engineering
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• v.18 no.1
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• pp.56-62
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• 2009

With weld metal of X65 steel, hydrogen was charged by electro-chemical method and mechanical behavior such as strength was measured by the small punch test. The weld metal was more sensitive to hydrogen charging than the case of base metal. The small punch (SP) strength was decreased as the hydrogen contents increased. Magnitude of strength decrease was dependent on current density, temperature, charging time. Current density and charging time have significant effect on the mechanical properties but temperature of electrolyte has limited effect. Fractured surfaces of the tested specimens were observed by SEM (scanning electron microscope). In the hydrogen charged specimens cleavage fracture were observed, which is consistent with the SP test results. Since the testing procedure for studying hydrogen embrittlement proposed in this study has shown good reproducibility of test results, the proposed method can be assumed to be a reliable test procedure. Using the electrochemical charging and the small punch test, the change of SP strength for X65 weld metal due to hydrogen embritlement could be evaluated sensitively.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.307-317
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• 2013

This study aims to investigate the research equipment establishing relationship by looking at research equipment information transfer that follows the network's structural and positional characteristics and the research institute's responsibilities to increase the possibility of research equipment usage by using the SNA(Social Network Analysis) method. Consequently, with the given structural characteristics of research institute, it can be concluded that because of its low density, it appears to be difficult to transfer research equipment information within the network. Government-funded research institutes that can effectively deliver research equipment information within the network system through comparison positional characteristics are ETRI, KITECH, KRICT, Sungkyungwan University, and Kyungbook National University. In addition, a virtualization node not only invigorates the network system but also acts as an intermediary factor to effectively deliver research equipment information. As results, there can be three conceivable alternatives to increase the possibility of research equipment usage. Those includes: 1. policy to encourage relationship building among research institutes 2. utilizing suitable institutes for effective delivery of research equipment information and lastly, 3. establishing a virtual intermediary institute for information sharing and utilization of isolated institutes' research equipments.

• Applied Biological Chemistry
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• v.29 no.4
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• pp.359-365
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• 1986

Exponentially growing cells of S. cerevisiae were cultivated in the concomitant presence of $2{\times}10^{-3}\;M$ paraquat for 12 hours. Cellular growth became slower as the time passed and then, it was completely inhibited after 6 hours of cultivation. More than 70 percent of the yeast cells were killed with in 12 hours of paraquat treatment. It was observed that size of the yeast cell varied from $4.5{\times}5.5{\um}m$ to $2.5{\times}3.5{\um}m$ in diameter, while that of control was uniform. The number of budding cells became rare, Cell wall of the paraquat treated cell was thinner$(0.15{\mu}m)$ than that of control cell$(0.20{\mu}m)$. Outer part of the cell wall had higher density than inner part. Membrane structures such as plasma membrane and mitochondria was decomposed during the paraquat treatment for 12 hours.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.521-528
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• 2009

While it is well known that space environment can produce spacecraft anomaly, defining space environment effects for each anomalies is difficult. This is caused by the fact that spacecraft anomaly shows various symptoms and reproducing it is impossible. In this study, we try to find the conditions of when spacecraft failures happen more frequently and give satellite operators useful information. Especially, our study focuses on the geosynchronous satellites which cost is high and required high reliability. We used satellite anomaly data given by Satellite News Digest which is internet newspaper providing space industry news. In our analysis, 88 anomaly cases occurred from 1997 to 2008 shows bad corelation with Kp index. Satellite malfunctions were likely to happen in spring and fall and in local time from midnight to dawn. In addition, we found the probability of anomaly increase when high energy electron flux is high. This is more clearly appeared in solar minimum than maximum period.