• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.983-991
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• 2009

The heat transfer phenomenon was investigated in this study when a circular water jet with low velocity flows to the downward facing heated circular plate and against the direction of gravity. Data are presented for jet flow rate between 0.23 and 2.3 l/min, jet fluid temperature of 24$^{\circ}C$, heat fluxes between 345 and 687 W/m$^2$, H/D=1, 2 and 3 with a single round jet diameter 2mm. The effects of heat flux, jet velocity and H/D on the local heat transfer are investigated in for the various regions of jet impingement. The local heat transfer distributions are analyzed based on the visualization of jet flow field. Data from experimental results are correlated by expressions of the form Nu=0.01$Re^{0.58}{\cdot}Pr^{0.4}$.

• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.45-50
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• 1995

The excellent c-axis oriented zinc oxide thin films were prepared by the RF magnetron sputtering method on glass substrates. Optimum fabrication conditions of the ZnO films were such that RF power, substrate temperature, and gas pressure of mixture Ar(50%):$O_{2}$(50%) were 150 W, $200^{\circ}C$, and 5 mTorr, respectively. In these conditions, the deposition rate was $310\;{\AA}/min$, and the resistivity of the film was $1{\times}10^6\;{\Omega}{\cdot}cm$. The ZnO film also showed high c-axis orientation and crystalinity according to XRD pattern and SEM photograph. A fabricated interdigital transducer generated 1st mode surface acoustic wave at 46.6 MHz and 2nd mode surface acoustic wave at 52.5 MHz. At the 1st mode, the phase velocity of surface acoustic wave and the electromechanical coupling coefficient were 2795 m/sec and 0.031 %, respectivly. At the 2nd mode, they were 3149 m/sec and 0.019 %. respectivly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.814-820
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• 2009

Antimony (Sb) doped ZnO thin films (0.1 at.%) were deposited on sapphire (0001) substrates at various temperatures (200 - 600$^{\circ}C$) by using pulsed laser deposition technique. All the thin films have been characterized by X-ray diffractometer, atomic force microscopy and spectrophotometer to investigate their structural, morphological and optical properties, respectively. Hall measurements were also carried out to identify the electrical properties of the thin films. These thin films were constituted in wurtzite structure with the preferential orientation of (002) diffraction plane and had as high as 80% optical transmission in the visible range. The bandgap energy also was determined by spectrophotometer which was around 3.28 eV. Hall measurements results revealed that the Sb dope ZnO thin film (0.1 at.%) grown at $500^{\circ}C$ exhibited p-type conduction with a carrier concentration of $8.633\times10^{16}\;cm^{-3}$, a mobility of $1.41\;cm^2/V{\cdot}s$ and a resistivity of $51.8\;\Omega{\cdot}cm$. We have successfully achieved p-type conduction in antimony doped ZnO thin films with low doping level even though the electrical properties are not favorable. This paper suggests the feasibility of p-type doping with large-size-mismatched dopant by using pulsed laser deposition.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.1
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• pp.33-39
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• 2019

The goal of this study was to investigate how the characteristics of growth and yield are affected by various planting densities in wide-row drill seeding cultivation suitable for mechanized harvesting. Two cultivars ('Hwanggeum' and 'Leebackchal') of proso millet (Panicum miliaceum L.) were planted at varying planting densities [row spacing (20, 30, and 50 cm) and plant spacing (3, 5, 10, and 15 cm)]. The culm length was highest at the planting density of $50{\times}3cm$ and $50{\times}5cm$ for 'Hwanggeum' and $20{\times}3cm$ for 'Leebackchal'. The culm diameter became thinner as the planting density increased. The number of tillering and panicle length showed the same tendency to increase in quantity or length as planting density decreased and was highest at $50{\times}15cm$ when the planting density was lowest. The number of seeds per individual increased as planting density decreased. The thousand grain weight showed no significant differences among treatment plots. The greatest yield of 'Hwanggeum' was obtained at a planting density of $50{\times}3cm$ ($314.9kg{\cdot}10a^{-1}$) and that of 'Leebackchal' was obtained at $50{\times}3cm$ and $50{\times}5cm$ ($358-356kg{\cdot}10a^{-1}$).

• Korean Journal of Medicinal Crop Science
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• v.22 no.4
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• pp.295-300
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• 2014

This study was carried out to produce more Parasenecio firmus in forest farming. In order to achieve this purpose, it was surveyed the growth and photosynthetic characteristics of P. firmus. Relatively light intensity was controlled by 100%, 60%, 30% and 5% of full sunlight. Height was the highest under 5% of full sunlight. Shoot diameter was the highest in full sunlight. Fresh weight (leaf, stem, root and total) and dry weight (leaf, root and total) were the highest under 30% of full sunlight. S (leaf+stem)/R (root) ratio was the lowest under 30% of full sunlight and the highest under 5% of full sunlight. In leaf characteristics, leaf area, SLA and LAR were getting higher in the lower light level and the highest under 5% of full sunlight ($176.1cm^2$, $420.5cm^2{\cdot}g^{-1}$ and $123.5cm^2{\cdot}g^{-1}$). Especially, leaf area was surveyed higher under 30% of full sunlight in the next. Leaf thickness was getting lower in the lower light level and the lowest under 5% of full sunlight (overall 0.14~0.24 mm). As a result of surveying the whole experiment, P. firmus grows well under 30% and 5% of full sunlight in forest farming.

• Horticultural Science & Technology
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• v.32 no.6
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• pp.917-921
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• 2014

'Hei-G' is a new tomato cultivar originating from the cross of two inbred lines, the maternal plant TKUI-3 separated from 'Kame' in 2007, and the paternal plant AL-1 developed by pedigree breeding. The new cultivar was registered as 'Hei-G' named 'JTB026 (Jeonnam-2)' based on characteristics and yield trials carried out in the spring of 3 years, from 2010 to 2012. 'Hei-G' is an indeterminate type with strong plant vigor. The fruit is round and the ripening fruit is blackish red. The average fruit weight of 'Hei-G' is about 43.4 g, and its marketable yield is $4,944kg{\cdot}10a^{-1}$. The lycopene content of 'Hei-G' ($11.8mg{\cdot}100g^{-1}$) is higher than that of other tomatoes (e.g., cv. Rapido, 3.1 mg). In addition, 'Hei-G' is suitable for environment-friendly protected cultivation because of its resistance to powdery mildew.

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.21-28
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• 1995

N-아실 아미도에틸 N-아미도 카르복시산 유도체들의 물리적 특성과 계면성이 연구되었다. 묽은 용액의 표면장력은 $22{\sim}32dyne/cm$의 값을 나타냈으며 이들 cmc의 범위는 $0.8{\sim}6.0mmol/L$이었다. 표면장력 저하능은 소수성의 알칼사슬이 길어질수록 그리고 카르복시기와 아미드기 사이의 메틸렌기의 수가 감소할수록 증가하였다. 반응생성물의 구조와 계면성의 관계를 비교 ${\cdot}$ 검토한 바 온화한 Krafft point와 뛰어난 습윤성, 낮은 기포력을 나타내었다.

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.41-50
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• 1995

2염기성 산의 모노메틸에스테르류와 에틸렌디아민을 반응시켜 얻은 아미도아민 유도체류를 고급지방산 염화물로 아실화하여 N-아실 아미도에틸 N-아미도카르복시산 유도체 9종을 합성하였다. 카르복시기와 디아미드기 그리고 소수성의 긴 알칼사슬을 갖는 모든 반응생성물들은 얇은 막 크로마토그래피와 컬럼크로마토그래피로 분리 ${\cdot}$ 정제하였다. 합성 수율은 $74{\sim}87%$였으며 그들의 구조를 FT-IR, $^1H-NMR$, 그리고 원소 분석으로 확인하였다.

• Korean Journal of Metals and Materials
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• v.49 no.1
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• pp.40-45
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• 2011

Using the spark plasma sintering process (SPS process), the WC-6wt.%Co hard materials were densified using an ultra fine WC-Co powder. The WC-Co was almost completely dense with a relative density of up to 100% after the simultaneous application of a pressure of 60 MPa and the DC pulse current for 3 min without any significant change in the grain size. The average grain size of WC that was produced through this experiment was about $0.2{\sim}0.8{\mu}m$. The hardness and fracture toughness were about $1816kg/mm^2$ and $15.1MPa{\cdot}m^{1/2}$, respectively, for 60 MPa at $1200^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.57-64
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• 2004

Effects of light and temperature on the nitrate uptake and germling growth of Enteromorpha compressa (L.) Greville (Chlorophyta) were studied based on samples from Cheongsapo near Busan, Korea. In addition, their effects on fatty acids composition in thallus were examined. Nitrate uptake showed saturation kinetics. $V_{max}$ (maximal uptake rate) and its $K_s$ (half-saturation constant) at $20^{\circ}C,\;80\;{\mu}mol\;m^{-2}s^{-1},$ white light were $1.571\;{\mu}mol{\cdot}g\;fr\;wt^{-1}{\cdot}h^{-1}$ and 3.56 ${\mu}M$, respectively. In nitrate uptake with irradiance, wavelength and temperature, its rate represented respectively the highest value as $1.405\pm0.020,\;0.623\pm0.040,\;1.422\pm0.022\;{\mu}mol{\cdot}g\;fr\;wt^{-1}{\cdot}h^{-1}\;at\;100\;{\mu}mol\;m^{-2}s^{-1},$ red light, $20^{\circ}C$ and exhibited significant difference among the examined conditions (p<0.001). Germling growth of E. compressa also showed saturation kinetics, and $V_{max}$ and its $K_s$ value at $20^{\circ}C,\;100\;{\mu}mol\;m^{-2}s^{-1},$ 12:12 h were $56.18\%\;day^{-1}$ and 0.33 ${\mu}M$, respectively. SGR (specific growth rate) recorded a maximal value as 49.33-54.80, 39.07-50.72, $47.20-54.53\%\;dat^{-1}$ at $120\;{\mu}mol\;m^{-2}s^{-1},$ blue light and $18^{\circ}C$ respectively, and showed significant difference (p<0.001). Red light made the effective nitrate uptake, but germling growth was largely limited by the light. In fatty acids analysis, PUFAs (polyunsaturated fatty acids) were high at blue light, $18^{\circ}C,\;100\;{\mu}M\;NO_3^-.$ However, irradiance did not affect the production of PUFAs. In conclusion, nitrate uptake and germling growth of E. compressa showed saturation kinetics to external nitrate concentration, and were significantly affected by irradiance, wave length and temperature. Fatty acid composition was also influenced by the factors except for irradiance. Their maximal values, together with the highest production of PUFAs, were found at blue light band, $20^{\circ}C,\;100\;{\mu}mol\;m^{-2}s^{-1},\;and\;100\;{\mu}M\;NO_3^-.$