http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
K.-H. IM,N.-S. PARK,Y.-N. KIM,L.-Y. YANG 한국자동차공학회 2003 International journal of automotive technology Vol.4 No.4
This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP (Carbon-fiber reinforced plastics) laminate plates based on considerations of stress wave propagation theory, which were converted to measurements of load and displacement verses time. The delamination area of impacted specimens for the different ply orientations was measured with an ultrasonic C-scanner to determine the correlation between impact energy and delamination area. The energy absorbed by a quasi-isotropic specimen having four interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the greater the energy absorbed. The absorbed energy of a hybrid specimen embedding GFRP (Glass-fiber reinforced plastics) layer was higher than that of normal specimens. Also, a falling weight impact tester was built to evaluate the characteristics and impact strength of CFRPs.
Electrical conductivity enhancement of epitaxially grown TiN thin films
Khim Yeong Gwang,Park Beomjin,Heo Jin Eun,Khim Young Hun,Khim Young Rok,Gu Minseon,Rhee Tae Gyu,Chang Seo Hyoung,Han Moonsup,Chang Young Jun 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.5
Titanium nitride (TiN) presents superior electrical conductivity with mechanical and chemical stability and compatibility with the semiconductor fabrication process. Here, we fabricated epitaxial and polycrystalline TiN (111) thin flms on MgO (111), sapphire (001), and mica substrates at 640℃ and room temperature by using a DC sputtering, respectively. The epitaxial flms show less amount of surface oxidation than the polycrystalline ones grown at room temperature. The epitaxial flms show drastically reduced resistivity (~ 30 micro-ohm-cm), much smaller than the polycrystalline flms. Temperature-dependent resistivity measurements show a nearly monotonic temperature slope down to low temperature. These results demonstrate that high-temperature growth of TiN thin flms leads to signifcant enhancement of electrical conductivity, promising for durable and scalable electrode applications.
Khim, S.,Kim, J.S.,Kim, J.W.,Lee, S.H.,Balakirev, F.F.,Bang, Y.,Kim, K.H. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.suppl1
We study temperature dependent upper critical field H<SUB>c2</SUB> of a SrFe<SUB>1.85</SUB>Co<SUB>0.15</SUB>As<SUB>2</SUB> single crystal (T<SUB>c</SUB>=20.2K) along ab-plane and c-axis through resistivity measurements up to 50T. For the both crystalline directions, H<SUB>c2</SUB> becomes nearly isotropic at zero temperature limit, reaching ~48T. The temperature dependence of the H<SUB>c2</SUB> curves is explained by interplay between orbital and Pauli limiting behaviors combined with the two band effects.
Khim, Boo-Keun,Kim, Dong-Seon,Shin, Hyoung-Chul,Kim, Dong-Yup The Korean Society of Oceanography 2005 Ocean science journal Vol.40 No.3
A time-series sediment trap was deployed at 1,034 m water depth in the eastern Bransfield Strait for a complete year from December 25, 1998 to December 24, 1999. About 99% of total mass flux was trapped during an austral summer, showing distinct seasonal variation. Biogenic particles (biogenic opal, particulate organic carbon, and calcium carbonate) account for about two thirds of annual total mass flux $(49.2\;g\;m^{-2})$, among which biogenic opal flux is the most dominant (42% of the total flux). A positive relationship (except January) between biogenic opal and total organic carbon fluxes suggests that these two variables were coupled, due to the surface-water production (mainly diatoms). The relatively low $\delta^{13}C$ values of settling particles result from effects on C-fixation processes at low temperature and the high $CO_2$ availability to phytoplankton. The correspondingly low $\delta^{l5}N$ values are due to intense and steady input of nitrates into surface waters, reflecting an unlikely nitrate isotope fractionation by degree of surface-water production. The $\delta^{l5}N$ and $\delta^{l3}C$ values of sinking particles increased from the beginning to the end of a presumed phytoplankton bloom, except for anomalous $\delta^{l5}N$ values. Krill and the zooplankton fecal pellets, the most important carriers of sinking particles, may have contributed gradually to the increasing $\delta^{l3}C$ values towards the unproductive period through the biomodification of the $\delta^{l3}C$ values in the food web, respiring preferentially and selectively $^{12}C$ atoms. Correspondingly, the increasing $\delta^{l5}N$ values in the intermediate-water trap are likely associated with a switch in source from diatom aggregates to some remains of zooplankton, because organic matter dominated by diatom may be more liable and prone to remineralization, leading to greater isotopic alteration. In particular, the tendency for abnormally high $\delta^{l5}N$ values in February seems to be enigmatic. A specific species dominancy during the production may be suggested as a possible and speculative reason.
Graphical Displays for Multiple Comparisons
khim,Seong-Yeon 東亞大學校 經營問題硏究所 1985 經營論叢 Vol.8 No.-
관찰대상이 되는 경영현상에 있어서, 모집단이 일정한 기준에 의해 몇몇의 부모집단으로 분할되어 어떤 성질이 그 각각의 부모집단에서 동일한 정도로 현현하느냐에 연구촛점이 맞추어 질 경우(가령 어떤 상품의 대학 학년에 따른 선호도 차이의 문제 또는 A, B, C, 각각의 생산라인에서 산출된 제품의 불량품율의 차이에 관한 문제 등등) 그 동일성 문제의 검정에 관한 통계적 처리를 도표화함으로써 일목요연하게 그 결과를 파악할 수 있게끔 하는 평균비교의 도표화 과정에 관한 논문이다. 즉 이를 엄밀히 표현하면 일원배치에 있어서 k개의 수준에서의 평균을 비교하기 위한 도표화 과정에 관한 고찰이다. 반복수가 다른 일원배치의 평균비교에 있어서는 튜키-크래머 방법(Tukey-Kramer Method)을 직접 적용하여 도표화하기는 불가능하므로, 그것을 중심으로 1) 단순보존적인 과정(simple conservative procedure)과 2) 가브리엘-제바의 변형과정(Gabriel-Gheva modified simple conservative procedure) 그리고 3) 최량보존적인 과정(the best conservative procedure)에 의한 접근으로부터 구한 도표화 과정을 상호 비교하여 보았다. 그 결과 단순성에 있어서는 1), 2), 3)의 순서로 우월하였으며 정도(precision)에 있어서는 그 역순이었다.
Study on Energy Balance at the Operating Points of Staged Combustion Cycle LRE
Khim Boh Yeon,문인상 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.5
In the present research, liquid rocket engine (LRE) balancing was performed at the design and the off-design points to confirm the characteristics for a 9-tonf staged combustion cycle LRE whose propellant consists of LOx/kerosene. When an LRE is designed, basic specifications, such as combustion pressure and O/F ratio, are predetermined and the corresponding balancing values are decided. Nevertheless, an engine may run over a nominal point in actual operation. Thrust control valve (THCV) and O/F ratio control valve (OFCV) are activated to adjust the engine status in real operation whenever an engine runs out of the design point. The engine power balancing requires thermophysical properties of the LOx and the kerosene for the combustion process and those were adopted from the CEA, which is an open-source code written by NASA. Also, MATLAB was employed and symbolic generation and numeric calculation was proposed to help set up the governing system and to reduce computational load. The off-design points were suggested to be set at ± 7%, ± 5%, ± 3% variance range from the nominal combustion pressure and the O/F ratio. It has been derived from the results that the required power of the pump was greatest at OD3 while least at OD1. If the combustion pressure is higher than DP, the THCV pressure difference should be set lower than DP. If the O/F ratio is higher than DP, the OFCV pressure difference should be set higher than DP. When the combustion pressure is over 100 bar, the TIT is over 700 K. It should be taken carefully in this section for turbine safety.
A Vacuum-Compatible Air Bearing: Design Analysis and Optimization
Khim, G.H.,Park, Chun Hong,Lee, H.S.,Kim, S.W. Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.339 No.-
<P>This paper describes the vacuum-compatible air bearing designed with a cascaded exhaust scheme to minimize the leakage of air in a vacuum environment. The design of the air bearing, including the differential exhaust system, required great care because several design parameters, such as the number of exhaust stages, diameter and length of the exhaust tube, pumping speed and ultimate pressure of the vacuum pump, and seal length and gap greatly influenced the leakage of air and thus the degree of vacuum. A leakage analysis was performed to estimate the chamber pressure and an optimization method based on the genetic algorithm was proposed under several constraint conditions. The results showed that the degree of vacuum improved dramatically compared to the initial design, and that the distribution of the spatial design parameters and technical limit of the pumping speed were well achieved.</P>