• Resources Recycling
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• v.24 no.4
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• pp.50-55
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• 2015

In this study, we have investigated solvent extraction of Ga and recovery of high pure Ga solution from MOCVD dust for manufacturing of LED chip. Effect of extractan, concentration of extractant were examined for choosing the more effective extractant and high pure Ga solution was fabricated by multi-stage extraction/stripping process. For extraction/separation of Ga based on the analysis of raw-material in previous study, 3 different extractants PC 99A, DP-8R, Cyanex 272 has been investigated and the extraction efficiency of 1.5 M Cyanex 272 was 43.8%. It was conformed that extraction efficiency of Ga was 83% in multi-stage extraction and 5N high purity Ga stripping solution without impurities also obtained.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.389-395
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• 2023

This study evaluated the effects of gibberellic acid (GA₃) on the growth and quality of creeping bentgrass (Agrostis palustris Huds.). Experimental treatments included a No application of fertilizer and GA₃ (NFG) Control [3 N active ingredient (a.i.) g/m²], 0.3GA₃ (GA₃ 0.3 a.i. mg/m²/200 mL), 0.6GA₃ (GA₃ 0.6 a.i. mg/m²/200 mL), 1.2GA₃ (GA₃ 1.2 a.i. mg/m²/200 mL), and 2.4GA₃ (GA₃ 2.4 a.i. mg/m²/200 mL). Additionally, the study included a 1.5N+GA₃ experiment with similar GA₃ treatments combined with 1.5N a.i. g/m² : NFG, Control (3N a.i. g/m²), 1.5N+ 0.3GA₃ (1.5N a.i. g/m²+GA₃ 0.3 a.i. mg/m²/200 mL), 1.5N+0.6GA₃ (1.5N a.i. g/m²+GA₃ 0.6 a.i. mg/m²/200 mL), 1.5N+1.2GA₃ (1.5N a.i. g/m²+GA₃ 1.2 a.i. mg/m²/ 200 mL), and 1.5N+2.4GA₃ (1.5N a.i. g/m²+GA₃ 2.4 a.i. mg/m²/200 mL). Compared to the NFG, turf color index chlorophyll content was not significantly different (p< 0.05). However, shoot length in 1.2GA₃, 2.4GA₃, 1.5N+0.3GA₃, 1.5N+0.6GA₃, 1.5N+1.2GA₃, and 1.5N+2.4GA₃ treatments increased by 0.8%, 10.6%, 5.15%, 8.3%, 13.5 %, and 21.6%, respectively, compared to the control. As compared to the control, clipping yield in 1.5N+1.2GA₃ and 1.5N+2.4GA₃ treatments increased by 7.1% and 14.3 %, respectively. These results indicated that GA₃ application increased shoot length, with the 1.2GA₃ treatment showing shoot length similar to the control (3N a.i. g /m² ).

• Korean Journal of Plant Resources
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• v.28 no.2
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• pp.253-258
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• 2015

In South Korea, Pinus pumila (Pall.) Regel (dwarf stone pine) has been designated as a critically endangered species by the Korea Forest Service. We have difficulties in obtaining the seeds of P. pumila because P. pumila grows only in the Daecheongbong area (1550–1700 m above sea level) of Mt. Seorak and almost all of its cones are damaged by birds and rodents. For establishing an ex situ conservation stand of P. pumila, this study was conducted to figure out the effects of wet cold (cold stratification, prechilling) and GA₃ treatment on the germination of P. pumila seeds. After cold stratification (1, 2, 3, 4, 5 months), prechilling (1, 2, 3, 4, 5 months) and GA₃ treatment (0, 100, 500, 1,000, 2,000, 3,000 ㎎/L), seeds were placed on petri-dishes at 25℃ under light condition. The percentage of germination, mean germination time and the germination rate were investigated. The results showed that both of the cold stratification and prechilling were effective in improving germination performances. However, there were no significant differences in performances between the two cold treatments. Within each treatment, the germination performances improved with the period of treatment. However, after three months of treatment, the performances showed no significant improvement. The gibberellin treatment was also effective in improving seed germination of P. pumila. The percentage of germination reached 79.0% in the seeds treated with 100 ㎎/L of GA₃. However, the germination performances decreased at high concentration of GA₃ treatments (over 2000 ㎎/L). In conclusion, cold stratification (over 3 months) or 100 ㎎/L of GA₃ treatment was considered to be the appropriate method for seedling production of P. pumila.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.45-51
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• 1977

The studies were carried to know the effects of GA$_3$, Ethrel and $H_2O$$_2$ on dormancy and germination in ginseng seeds. GA$_3$ stimulated the embryo growth and increased dehiscent (Kaekapp) ratio of the seeds for more than Ethrel and $H_2O$$_2$ GA$_3$ not only increased germination ratio but also shortened the period of germination. Ethrel and $H_2O$$_2$ showed no effects on the germination and there were no significant differences among the treatment levels of GA$_3$. The slow germination of ginseng seeds seemed to be mainly due to the dormancy of endosperm or seed coat rather than of embryo.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.764-769
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• 2004

In order to reduce operating voltage of the GaN based blue-violet laser diodes, the effect of highly Mg doped GaN layer, which was grown below ohmic contact metals, on contact resistivity as well as operating voltage has been investigated. The addition of the highly Mg doped GaN layer greatly reduced contact resistivity of Pd/Pt/Au ohmic contacts from $5.2 \times {10}^-2 \Omegaㆍ$\textrm{cm}^2$ to 7.5 \times {10}^-4 \Omegaㆍ$\textrm{cm}^2$$. In addition, it also decreased device voltage at 20 mA by more than 3 V. Temperature- dependent sheet resistivity of the highly Mg doped GaN layer suggested that the reduction of the contact resistivity could be attributed to predominant current flow at the interface between the Pd/Pt/Au contacts and p-GaN through a deep level defect band, rather than the valence band.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.497-504
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• 2005

This experiment was conducted to improve germination rate of the seed treated duration of storage and $GA_3$ in Celosia argentea. With the seed directly after harvest, as increasing concentration of $GA_3$, ranged from 50ppm to 200ppm, and dipping hour, ranged from 6 to 24 hour, the rate of germination was also increased. The germination of seed dipping in 200ppm $GA_3$ for 24 hours was the highest with $52\%$ compared to the control with $12\%$. As increasing storage duration in $22{\pm}2^{\circ}C$, ranged from 2 weeks to 12 weeks, the rate of germination was also increased showing $84\%$ at 12 week. However, the rate of germination was not increased with the storage of $5^{\circ}C,\;0^{\circ}C,\;and\;-70^{\circ}C$. With the seed storage 16 weeks in $22{\pm}2^{\circ}C$ after harvest, the rate of germination was $84\%$. The rate of germination was increased $94\%\;to\;99\%$ by the $GA_3$ concentration, ranged from 50ppm to 400ppm, and dipping hour, ranged from 6 to 24 hour. The germination was finished 4 days after sowing.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.242-248
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• 1983

The effects of light source, plant growth regulators (GA, BA, ABA), and sodium hypochlorite (4% Cl, SH) on germination of 'G rand Rapid' lettuce (Lactuca sativa L.) seed were studied. Seed did not germinate under the conditions of dark and blue light. The treatment of GA or BA did not promote on germination under dark or blue light. The germination percentage under red light was very high, it was similar to the condition of white light. ABA inhibited lettuce seed germination. Although ABA was treated, BA 10ppm treatment was moderately effective under white light condition and BA 10ppm or 50ppm combined with GA 50ppm were also effective on seed germination under dark condition. Presoaking in sodium hypochlorite solution induced germination of lettuce seed in any condition of dark or white light. The optimum presoaking time in sodium hypochlorite solution was twenty min.

• Weed & Turfgrass Science
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• v.2 no.2
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• pp.152-158
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• 2013

Dandelion (Taraxacum officinale) is a member of family Asteraceae that grows all over the Korea. Recently, dandelion was cultivated for medicinal crops because of its positive medicinal effects. However, dandelion is considered as a troublesome weed in grass lawns of golf course and orchards. This study was conducted to investigate the effect of plant growth regulators [gibberellins ($GA_3$); kinetin; salicylic acid (SA); ethephon)] with different concentration on seed germination control of dandelion. Seed germination rates were increased in all concentration of $GA_3$ and kinetin treatment compared to control. In the 0.5 mM of ethephon application, seed germination rate was more increased than that of control while seed germination rate was reduced in 1.0 and 1.5 mM of ethephon treatments. Seed germination rate was significantly decreased with different SA dilutions compared to control. The germination rate was more reduced when SA was applied in combination with $GA_3$ than only SA treatments.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.159-159
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• 2010

본 논문은 테라헤르츠 소스로 저온 InGaAs를 대체하기 위한 저온 $In_{0.64}Al_{0.36}Sb$의 실리콘(Si) 도핑 농도에 따른 광학적 특성 변화를 photoluminescence (PL)과 time-resolved PL (TRPL) 측정을 이용하여 분석하였다. $In_{0.64}Al_{0.36}Sb$ 시료는 분자선 엑피탁시 (molecular beam epitaxy)법으로 GaAs 기판 위에 약 $420^{\circ}C$에서 $3.7\;{\mu}m$ 두께 성장하였다. Si은 $In_{0.64}Al_{0.36}Sb$ 시료에서 도핑 농도가 낮을 때는 어셉터(acceptor)로 작용하다가 도핑 농도가 증가함에 따라 도너(donor)로 작용하였다. 본 연구에 사용한 $In_{0.64}Al_{0.36}Sb$ 시료의 Si 도핑 농도는 $4.5{\times}10^{16}\;cm^{-3}$ (n형), $4{\times}10^{16}\;cm^{-3}$ (n형), $8{\times}10^{15}\;cm^{-3}$ (n형), $1{\times}10^{15}\;cm^{-3}$ (p형), $4{\times}10^{14}\;cm^{-3}$ (p형)인 다섯 개의 시료를 사용하였다. Si 도핑한 시료의 PL 피크는 undoped 시료보다 약 100-200 nm 단파장에서 나타나고 PL 세기도 크게 증가하였다. 그러나 Si 도핑 농도가 가장 낮은 n형과 p형 시료의 PL 피크가 가장 짧은 파장 (높은 에너지)에 나타나고 도핑 농도가 증가함에 따라 장파장으로 이동함을 보였다. n형 시료의 도핑 농도가 $8{\times}10^{15}\;cm^{-3}$에서 $4.5{\times}10^{16}\;cm^{-3}$로 증가하였을 때 PL 피크는 1232 nm에서 1288 nm까지 장파장쪽으로 이동하였으며, p형 시료는 도핑 농도가 $4{\times}10^{14}\;cm^{-3}$에서 $1{\times}10^{15}\;cm^{-3}$로 증가하였을 때 PL 피크가 1248 nm에서 1314 nm로 이동함을 보였다. 또한 시료 온도에 따른 PL 결과는 온도가 증가함에 따라 PL 피크는 장파장으로 이동하면서 PL 세기는 급격하게 감소하고 약 100 - 150 K에서 소멸하였다. 그러나 ~1500 nm 이상 장파장 영역에 매우 넓은 새로운 피크가 나타났으며 온도가 증가함에 따라 PL 세기가 증가함을 확인하였다. Si 도핑 농도에 따른 운반자 수명시간 변화를 TRPL을 이용하여 측정하였다. 운반자 수명시간은 double exponential function을 이용하여 얻었다. Si 도핑 시료의 운반자 수명시간이 undoped 시료에 비해 매우 길게 나타났으며, Si 도핑 시료에서는 p형 시료들보다 n형 시료들의 운반자 수명시간이 길게 나타났다. PL 방출파장에 따른 운반자 수명시간은 Si 도핑 농도에 따라 다르게 나타났다. 이러한 PL과 TRPL 결과로부터 $In_{0.64}Al_{0.36}Sb$의 발광 특성 및 운반자 동역학은 Si 도핑에 크게 영향을 받는다는 것을 확인하였다.

• Electronics and Telecommunications Trends
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• v.29 no.6
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• pp.1-13
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• 2014

GaN(Gallium Nitride)는 3.4eV의 넓은 에너지 갭으로 인하여 고전압에서 동작이 가능하고, 분극전하를 이용한 캐리어 농도가 높아 높은 전류밀도와 전력밀도를 얻을 수 있으며, 높은 전자 이동도와 포화 속도로부터 고속 동작이 가능하여 고주파 고출력 고효율 소형의 전력증폭기 소자의 재료로 적합하다. 본고에서는 민수 및 군수 겸용 Ku-대역 및 Ka-대역 GaN 고출력 전력증폭기(SSPA: Solid-State Power Amplifier)와 관련된 GaN 전력증폭 소자, GaN 전력증폭기 MMIC(Microwave Monolithic Integrated Circuit), 내부정합 패키지형 GaN 전력증폭기 및 GaN SSPA에 대하여, 국내외 특허 기술동향과 연구개발 기술동향을 중심으로 고찰하고자 한다. 국외의 GaN 고주파 고출력 전력증폭기 기술의 연구동향이나 특허동향을 심층분석하여 연구개발에 활용하고자 한다.