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Kim, Su Jae,Cha, Su Young,Kim, Ji Young,Shin, Jong Moon,Cho, Yong Chan,Lee, Seunghun,Kim, Won-Kyung,Jeong, Se-Young,Yang, Y. S.,Cho, Chae Ryong,Choi, H. W.,Jung, Myung-Hwa,Jun, Byeong-Eog,Kwon, Ki-Yon American Chemical Society 2012 The Journal of Physical Chemistry Part C Vol.116 No.22
<P>There have been many studies of ferromagnetism in ZnCoO, and the results have been controversial. Secondary phases, such as Co oxides and Co metal clusters, in ZnCoO are easily produced during treatment, but the formation conditions are not well understood. We fabricated samples under hydrogen-injection conditions at different heat-treatment temperatures and examined the conditions by using synchrotron X-ray analysis under which Co<SUB>3</SUB>O<SUB>4</SUB> appeared or was transformed into Co metal. We investigated the transforming process of the ferromagnetic origin from intrinsic to extrinsic nature via intermediate region competition by Co–H–Co and Co metal cluster and suggest conditions that induce ferromagnetic spin ordering in ZnCoO due to Co–H–Co complexes through hydrogen mediation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-22/jp300536w/production/images/medium/jp-2012-00536w_0010.gif'></P>
Design of a Thomson scattering diagnostic system for VEST
Kim, Young-Gi,Lee, Jong Ha,Lee, Jeongwon,An, YoungHwa,Dang, Jeong Jeung,Jo, Jungmin,Lee, HyunYeong,Chung, Kyoung-Jae,Hwang, Y.S.,Na, Yong-Su Elsevier 2015 Fusion engineering and design Vol.96 No.-
<P><B>Abstract</B></P> <P>A Thomson scattering diagnostic system is designed for Versatile Experiment Spherical Torus (VEST) to measure the spatial profiles of the electron temperature. The system is carefully designed to collect a sufficient number of photoelectrons and to reduce the noise sources, since relatively low electron densities and temperatures are expected in VEST due to the limited power capacity at present. The target electron temperature and the density are 10–200eV and 5×10<SUP>18</SUP> m<SUP>−3</SUP>, respectively which are extrapolated from the data of triple Langmuir probes measuring the edge plasma parameters at <I>R</I> =0.75m by assuming a parabolic density profile. The collecting optics is designed to have a wide-view angle and low cost by using a commercial photographic lens of low f-number and high transmittance optical fiber bundle. The bandwidths of the interference filters in the polychromator are designed for reliable measurements within the target electron temperature range. As a photo detector which is coupled with the filters, an avalanche photodiode (APD) with a low dark current and an adequate quantum efficiency near the laser wavelength is selected for the high signal-to-noise ratio. The number of photons transferred to the polychromator and the number of photoelectrons in the APD are calculated. At the commissioning phase, an oscilloscope with a high sampling rate will be adopted to check the necessity of the noise reduction by multi-shot signal accumulation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A Thomson scattering system for Versatile Experiment Spherical Torus is designed. </LI> <LI> The system is designed with care for the plasma with a low target electron density. </LI> <LI> APD of low dark current and enhanced sensitivity for near infrared has been chosen. </LI> <LI> A collecting optics system will provide a sufficient number of photoelectrons. </LI> <LI> A designed polychromator is able to measure the electron temperature of 10–1000eV. </LI> </UL> </P>
Do Yeob Kim,Min Su Kim,Tae Hoon Kim,김건식,Hyun Young Choi,Min Young Cho,H. H. Ryu,W. W. Park,D. Y. Lee,김진수,Jong Su Kim,J. S. Son,J. Y. Leem 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1
Self-assembled InAs quantum dots (QDs) embedded in GaAs/InxGa1-xAs strained layers with different In mole fractions were grown by using molecular beam epitaxy (MBE) and their optical properties were investigated by using photoluminescence (PL) spectroscopy. The InAs QDs were grown on GaAs(2 nm)/InxGa1-xAs(2 nm)×10 strained layers with x = 0.1, 0.32 and 0.52 and were capped with the same strained layer. The PL peak positions of the InAs QDs were red-shifted by increasing the In mole fraction of the GaAs/InxGa1-xAs strained layer. As a result, the emission wavelength of the QDs embedded in the GaAs/InxGa1-xAs strained layer with x = 0.52 was about 1.27um at room temperature. Compared to the PL spectra of the as-grown InAs QDs, the PL spectra of the InAs QDs grown on GaAs/In0:1Ga0:9As strained layers showed blue-shifts of about 100 meV with increasing annealing temperature up to 850℃ and signicant enhancements of the PL peak intensity.
Kadir, Mohammad Abdul,Kim, Su Jeong,Ha, Eun‐,Ju,Cho, Hong Y.,Kim, Bong‐,Soo,Choi, Donghyeuk,Lee, Sun‐,Gu,Kim, Bog G.,Kim, Sang‐,Wook,Paik, Hyun‐,jong WILEY‐VCH Verlag 2012 Advanced functional materials Vol.22 No.19
<P><B>Abstract</B></P><P>The use of nitrilotriacetic acid end‐functionalized polystyrenes (NTA‐PS) as a multifunctional nanocarrier for the aqueous dispersion of CdSe, <I>γ</I>‐Fe<SUB>2</SUB>O<SUB>3</SUB> and gold nanoparticles (NPs) is described. When the amphiphilic end‐ functionalized polystyrenes and NPs are dissolved together in tetrahydrofuran, the addition of water causes the spontaneous formation of micellar aggregates, resulting in the successful encapsulation and aqueous dispersion of NPs. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), photoluminescence (PL) spectroscopy, and vibrating sample magnetometer (VSM) are used to characterize the structure and properties of the NPs‐containing micellar aggregates (nanocarrier). After complexation of Ni<SUP>2+</SUP> with NTA on the surface of the nanocarrier containing <I>γ</I>‐Fe<SUB>2</SUB>O<SUB>3</SUB>, specific binding between Ni‐NTA complex and histidine‐tagged (His‐tagged) proteins enables selective separation of His‐tagged proteins using a magnet.</P>
Kim, Jongho,Kim, Min Su,Kim, Do Yeob,Park, Ho Jin,Kim, Jong Su,Lee, D Y,Kim, Jin Soo,Son, J S,Ryu, H H,Cho, Guan Sik,Jeon, Minhyun,Leem, J Y American Scientific Publishers 2009 Journal of nanoscience and nanotechnology Vol.9 No.7
<P>The post-growth thermal annealing effects of Mg doped GaAs epitaxial layers on the microstructural and optical properties grown by molecular beam epitaxy (MBE) have been investigated. The properties of Mg doped GaAs are estimated after the process of rapid thermal annealing (RTA) in the temperature range of 600 approximately 750 degrees C. The photoluminescence (PL) peak position of as-grown sample blueshifted from 1.473 to 1.485 eV as well as the pronounced enhancement in PL intensity by annealing at 600 degrees C. In the sample grown at the temperature of T(s) = 475 degrees C, the full-width at half maximum (FWHM) of double crystal X-ray diffraction (DCXRD) decreased form 27 to 8 arcsec with increasing of annealing temperature (600 approximately 700 degrees C). The crystalline quality variation of Mg doped GaAs layers by RTA is greatly dependent upon the doping level.</P>
장기체공무인기의 운항안전을 위한 남한지역 고도별 풍속 분석
조영준,하종철,최규용,김기훈,임은하,김수복,윤종환,Cho, Young-Jun,Ha, Jong-Chul,Choi, Reno K.Y.,Kim, Ki-Hoon,Lim, Eunha,Kim, Su-Bok,Yun, Jong-Hwan 한국군사과학기술학회 2016 한국군사과학기술학회지 Vol.19 No.4
We analyzed wind speed over South Korea for HALE UAV(High Altitude Long Endurance Unmaned Aerial Vehicle) flight safety. Annual variation of wind speed at 200 hPa showed that winter season was stronger than summer. According to latitude, wind speeds in January and August were found to be $52{\sim}74m\;s^{-1}$ and $15{\sim}26m\;s^{-1}$, respectively. Wind speed was stronger(weaker) at lower latitudes than higher latitudes in winter(summer). Frequency(%) of wind speed less than threshold value($18m\;s^{-1}$) for the operation date was investigated. The days showing the frequency greater than 60 % in all altitudes of surface ~ 50 hPa showed the range of 1 ~ 33 days at 7 stations. Operation date was the longest period at Gosan. The appropriate date of HALE UAV operation at Gosan and Osan is considered as the middle of July ~ middle of August and end of July ~ early August, respectively. These results can be used to determine the operation date of HALE UAV.
유승화 ( Seung-hwa Yu ),김영근 ( Young-keun Kim ),최일수 ( Il-su Choi ),우제근 ( Jea-keun Woo ),현창식 ( Chang-sik Hyun ),강태경 ( Tae-gyoung Kang ),전현종 ( Hyeon-jong Jun ),이상희 ( Sang-hee Lee ),김진구 ( Jin-gu Kim ),최용 ( Y 한국농업기계학회 2019 한국농업기계학회 학술발표논문집 Vol.24 No.2
최근 몇 년간 드론은 급격한 기술 발전을 이루었으며, 특히 농업 분야에 새로운 형태의 농용 플랫폼으로 자리 매김하였다. 농업용 드론은 빠르게 보급되고 있지만 이용 형태 등 현황 파악은 부족한 실정이다. 특히 드론용 노즐은 무인헬기용을 대부분 사용하고 있으나 드론은 멀티로터로 추력의 유동형태가 무인헬기와 달라 분무된 약액의 비산 또는 확산 특성이 다르므로 드론의 하향풍 유동 특성에 적합한 분무 노즐이 필요하다. 이에 본 연구에서는 영농 현장에서 사용되고 있는 드론 이용 형태를 조사하고, 드론의 분무 노즐 특성을 분석하여 노즐의 VMD를 제시하고자 하였다. 드론의 이용 현황을 정부 지원으로 보급된 기종을 중심으로 용도별, 지역별로 조사·분석한 결과, 농업용 드론은 총 706대를 작목반 등 일반 농가(309대)와 농협(215대), 영농법인(126대), 기술원·센터(56대)에서 이용하고 있었다. 무인헬기는 방제전용으로 농협(168대), 영농법인(61), 기술원·센터(10), 농가 등(6)로 총 245대를 보급하여 이용하고 있었다. 용도는 방제용 91.4%, 교육용 4.8, 시비·파종용 2.8, 예측용 0.7으로 조사되었으며, 드론을 이용한 농약 방제가 영농 현장에서 가장 큰 이용 효과가 있었다. 지역별로 살펴보면, 전남 40.9%, 전북 23.4, 충남 12.2 등이며, 무인헬기는 전남(30.6%), 전북(18.0), 경남(17.6) 등으로 나타났다. 전남·북지역에서 드론과 무인헬기의 이용률이 높게 나타나는 것은 지리적으로 평야지역이 많고 수도작(벼) 생산 단지가 많이 위치해 있어 드론 운용에 편리하기 때문인 것으로 판단되었다. 드론용 노즐의 분무 특성을 ISO/DIS 16119-5 규정을 기초로 분석한 결과를 ISO S10625의 컬러 코드로 나타내면, 40 psi(2.76bar)에서 노즐이 2개인 경우는 Orange(0.1GPM(0.38LPM)) ~ Red(0.4 GPM(1.51LPM)), 노즐 4∼6개는 Orange(0.1 GPM(0.38LPM)) ~ Yellow(0.2 GPM(0.76LPM))로 분석되었다. 이와 같이 노즐의 오리피스 분사량을 분석한 결과를 종합하여 비산 감소 액적 크기를 나타내면 Medium(Yellow, VMD 236∼340㎛)∼Extremely coarse(White, 503∼665㎛) 범위이다. 현재 농업용 드론에 시용되고 있는 노즐을 분석 결과 대부분의 노즐은 XR 계열(flat-fan type)로 유량범위는 0.1~0.2 GPM(0.38~0.76 LPM), 분무각은 80°, 110°, 액적 크기는 114~235 ㎛(Fine, Orange) 범위를 나타내고 있다. Hollow cone type의 TX 계열의 노즐 액적 크기는 61~144 ㎛(Very Fine, Red) 범위이다. 이때 Very Fine(61~144 ㎛) 범위의 액적 크기는 측면풍이 없고 호버링 조건에서 도포율을 향상시킬수 있지만 실제 드론 비행 조건에서는 비산에 매우 취약하다. 따라서 실제 비행 조건에서 취약점을 극복하기 위해서는 드론 방제에 약 236∼340㎛의 상용 노즐을 이용하면 비산을 줄이고 방제 효율 향상에 효과적이라고 판단되었다.