• Journal of Radiation Protection and Research
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• 제29권3호
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• pp.165-172
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• 2004

피폭상자 내에서 벼를 생육단계별로 80 분 간 $I_2$ 증기에 피폭시키고 작물체 직접오염 관련 인자를 조사하였다. $I_2$ 증기의 경엽부 침적속도$(m\;s^{-1})$는 피폭시기에 따라 $1.4{\times}10^{-5}-1.3{\times}10^{-4}$의 범위로 생육 전반기 피폭시 비교적 낮았다. 이삭 침적속도는 $2.5{\times}10^{-5}-6.7{\times}10^{-5}$의 범위였다. 전체 작물체에 대한 침적속도는 $1.4{\times}10^{-5}-1.8{\times}10^{-4}$의 범위로 8월 18일(출수 시작후 7일) 피폭시 가장 높았다. 침적속도를 생육밀도 기준으로 나타내면 시기에 따른 변이 정도가 대체로 감소하였다. 기온, 일광 및 습도에 대한 이렇다할 침적속도의 경향성은 관찰되지 않았다. 요오드의 현미 전류계수는 $3.3{\times}10^{-5}-4.7{\times}10^{-4}$의 범위로 8월 23일 피폭에서 가장 높았다. 출수전 경엽부에 침적한 요오드도 상당량 현미로 전류하는 것으로 나타났다.

• Journal of Advanced Marine Engineering and Technology
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• 제41권2호
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• pp.140-145
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• 2017

Newly designed vapor-injection heat pumps have been proposed and analyzed in the present study. An economizer-type vapor-injection (V-I) system has been employed as the standard system because of its reliability and simple control method. The V-I system has a re-cooler and re-heater for cooling and heating, respectively. Solar panels have been installed in the V-I heat pump as well as in the re-heater in order to enhance heating capacity and performance. R410A has been employed as a working fluid and performance analysis has been conducted under various conditions. Results are summarized as follows: (1) The V-I system with the re-cooler yielded a marginally higher coefficient of performance (COP) than the conventional V-I refrigeration system. (2) By increasing the re-cooler cooling capacity, enhanced system performance as compared to the conventional V-I system was observed. (3) The re-heater negatively affected the system performance; hence, the V-I heat pump with the re-heater yielded a lower COP than that of the conventional V-I heat pump used for heating. (4) Although the solar panels increased the system performance, this increase could not offset performance degradation by the re-heater.

• Food Science and Biotechnology
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• 제17권2호
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• pp.330-335
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• 2008

Water vapor adsorption kinetics of 3 different types of chitosan-based films, i.e., control chitosan, chitosan/montmorillionite (Na-MMT), and chitosan/silver-zeolite (Ag-Ion) nanocomposite films, were investigated at temperature range of $10-40^{\circ}C$. In all the films, water vapor is initially adsorbed rapidly and then it comes slowly to reach equilibrium condition. Reasonably good straight lines were obtained with plotting of 1/($m-m_0$) vs. l/t. It was found that water vapor adsorption kinetics of chitosan-based films was accurately described by a simple empirical model and the rate constant of the model followed temperature dependence according to Arrhenius equation. Arrhenius kinetic parameters ($E_a$ and $k_o$) for water vapor adsorption by chitosan-based films showed a kinetic compensation effect between the parameters with the isokinetic temperature of 315.52 K.

• 한국의류학회지
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• 제14권4호
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• pp.281-291
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• 1990

Experiment I and II had done to develop the solar heat proof hat for field work in the summer. In the experiment I physical characteristics of several fabrics was tested to determine which one Is proper to make the solar heat proof hat. On the base of above results in the experiment II three improved solar heat proof hat was deviced and tested solar heat proof effect and compared the existing summer working hat by wearing trials in the environmental chamber. The results obtained were as follows. 1. In the view of the physical characteristics of six fabrics (Blue T/C, White poplin, Vapor transfer silver coating nylon taffeta, No vapor trans(or silver coating nylon taffeta, Aluminum coating T/C, Microporous fabric), the light color T/C and no vapor transfer silver coating nylon ta(feta is proper to make improved solar heat proof working hat. 2. Three improved hats that are made of white T/C, grey T/C and no vapor transfer silver coating nylon taffeta have more solar heat proof effect than the existing summer working hat. 3. Among the three improved hats, the improved hat that is made of no vapor transfer silver coating nylon taffeta is most effective to proof the solar heat.

• 대한기계학회논문집B
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• 제25권5호
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• pp.688-696
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• 2001

Vaporizing characteristics of two GDI injectors with different spray angles were investigated using exciplex fluorescence method. Injector I has narrower spray angle, while injector II has wider one. The exciplex system of fluorobenzene and DEMA in a non-fluorescing base fuel of hexane was employed. In quantifying concentration of fuel vapor, quenching of concentration and temperature was corrected. Droplet size and velocity were also measured by PDPA under non-vaporizing condition. From obtaining the images of liquid and vapor phases, vaporizing GDI sprays could be divided as two regions: cone and mixing regions. For injector I, vortex region was not developed. High concentration of fuel vapor due to vaporization of many fine droplets was distributed near the spray axis. For injector II, droplets with the diameter of about 10 $\mu$m were distributed in the vortex region. The vortex region had high concentration of fuel vapor due to vaporization of these droplets. Particularly, higher and lower concentrations of fuel vapor were balanced at 2ms after the start of injection for injector II.

• 한국세라믹학회지
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• 제35권12호
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• pp.1329-1336
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• 1998

A twt -step carbothermal reduction scheme has been employed for the synthesis of SiC whiskers in an Ar or a H2 atmosphere via vapor-solid two-stage and vapor-liquid-solid growth mechanism respectively. It has been shown that the whisker growth proceed through the following reaction mechanism in an Ar at-mosphere : SiO2(S)+C(s)-SiO(v)+CO(v) SiO(v)3CO(v)=SiC(s)whisker+2CO2(v) 2C(s)+2CO2(v)=4CO(v) the third reaction appears to be the rate-controlling reaction since the overall reaction rates are dominated by the carbon which is participated in this reaction. The whisker growth proceeded through the following reaction mechaism in a H2 atmosphere : SiO2(s)+C(s)=SiO(v)+CO(v) 2C(s)+4H2(v)=2CH4(v) SiO(v)+2CH4(v)=SiC(s)whisker+CO(v)+4H2(v) The first reaction appears to be the rate-controlling reaction since the overall reaction rates are enhanced byincreasing the SiO vapor generation rate.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.298.1-298.1
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• 2016

Two-dimensional materials have been received significant interest after the discovery of graphene due to their fascinating electronic and optical properties for the application of novel devices. However, graphene lack of certain bandgap which is essential requirement to achieve high performance field-effect transistors. Analogous to graphene materials, molybdenum disulfide ($MoS_2$) as one of transition-metal dichalcogenides family presents considerable bandgap and exhibits promising physical, chemical, optical and mechanical properties. Here we studied nonvolatile memory based on $MoS_2$ which is grown by chemical vapor deposition (CVD) method. $MoS_2$ growth was taken on $1.5{\times}1.5cm^2$ $SiO_2$/Si-substrate. The samples were analyzed by Raman spectroscopy, atomic force microscopy and X-ray photoelectron spectroscopy. Current-voltage (I-V) characteristic was carried out HP4156A. The CVD-$MoS_2$ was analyzed as few layers and 2H-$MoS_2$ structure. From I-V measurement for two metal contacts on CVD-$MoS_2$ sample, we found typical resistive switching memory effect. The device structures and the origin of nonvolatile memory effect will be discussed.

• 대한안전경영과학회지
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• 제2권4호
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• pp.33-43
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• 2000

The consequence analysis for the unconfined vapor cloud explosion(UVCE) accident by the continuous release of butane vapor was performed and effects of process parameters on consequences were analyzed in standard conditions. For the case of continuous release(87.8 kg/s) of butane vapor at 8 m elevated height in the debutanizing process of tile naphtha cracking plant operating at 877 kPa ＆ 346.75 K, we found that combustion ranges of dispersed vapor estimated by HMP model were 11.2~120.2 m and overpressures estimated by TNT equivalency model at 200 m were about 37.35~55.1 kPa. Also, overpressures estimated by Model UVCE I based on advective travel time to $X_{LFL}$ were smaller than those estimated by Model UVCE IIbased on real travel time between $X_{UFL}$ and $X_{LFL}$. At the same time, damage intensities at 200 m and effect ranges by overpressure could be predicted. Furthermore, simulation results showed that effects of operating pressures on consequences were larger than those of operating temperatures and results of accidents were increased with increasing operating pressures. At this time, sensitivities of overpressures for UVCE accident by the continuous release were about 5 kPa/atm.

• Carbon letters
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• 제18권
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• pp.37-42
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• 2016

Graphene was grown on molybdenum (Mo) foil by a chemical vapor deposition method at different growth temperatures (1000℃, 1100℃, and 1200℃). The properties of graphene were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and Raman spectroscopy. The results showed that the quality of the deposited graphene layer was affected by the growth temperature. XRD results showed the presence of a carbide phase on the Mo surface; the presence of carbide was more intense at 1200℃. Additionally, a higher I_2D/I_G ratio (0.418) was observed at 1200℃, which implies that there are fewer graphene layers at this temperature. The lowest I_D/I_G ratio (0.908) for the graphene layers was obtained at 1200℃, suggesting that graphene had fewer defects at this temperature. The size of the graphene domains was also calculated. We found that by increasing the growth temperature, the graphene domain size also increased.

• Bulletin of the Korean Chemical Society
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• 제10권5호
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• pp.426-430
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• 1989

Two crystal structures of iodine sorption complexes of dehydrated partially Co(Ⅱ )-exchanged zeolite A, $Co_{3.5}Na_5-A{\cdot}xI_2$, x = 2.5 and 5.0, have been determined by single crystal X-ray diffraction techniques. Both structures were solved and refined in cubic space group, Pm3m at $21(1)^{\circ}C$. The structures of $Co_{3.5}Na_5-A{\cdot}2.5I_2$(a = 12.173(1) ${\AA}$) and $Co_{3.5}Na_5-A{\cdot}5.0I_2$(a = 12.130(1) ${\AA}$) were refined to the final error indices, $R_1$ = 0.081 and $R_2$ = 0.077 with 261 reflections and $R_1$ = 0.103 and $R_2$ = 0.112 with 225 reflections, respectively, for which I>3${\sigma}$(I). In both structures, 3.5 $Co^{2+}$ ions and 4.5 $Na^+$ ions per unit cell lie at two crystallographically different 6-ring positions. 0.5 $Na^+$ ion lines in an 8-oxygen ring plane. Dehydrated $Co_{3.5}Na_5$-A sorbs 2.5 iodine molecules per unit cell at $70^{\circ}C$ (vapor pressure of $I_2$ is ca. 8.3 torr) within 30 minutes and 5 iodine molecules per unit cell at $80^{\circ}C$ (vapor pressure of $I_2$ is ca. 14.3 torr) within 24 hours. Each iodine molecule makes a close approach, along its axis to framework oxygen atom with I-I-O = $175^{\circ}$.