• Horticultural Science & Technology
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• v.19 no.4
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• pp.465-470
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• 2001

This study was carried out to investigate the effect of application dosage and methods of selenium (Se) on mineral contents in garlic. The content of Se was higher in upland than paddy fields. Application of higher dosage of Se salt increased higher content of Se in leaf sheath and bulb of garlic. Se was detected also in the non-treated plot but its amount was negligible. Absorption of Se in garlic was higher when Se was applied in the form of sodium selenate. Foliar application of sodium selenate enriched Se content in garlic as compared with the soil dressing. However, Se content in garlic fluctuated depending on growing conditions. Se content of garlic grown on the artificial soil (vermiculite and commercial soil) in the plastic house was higher than the garlic grown in the paddy field. The growth of garlic was not affected by types, dosage and application methods of selenium. Mineral contents in garlic such as Mg, S and K were higher in the selenium treatment than control. However, this trend was not evident according to dosages of selenium fertilizers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.829-833
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• 2017

Recently, pirate incidents involving passing ships have been continuously occurring in the seas southwest of the Philippines, the Sulu Sea and the Celebes Sea. Pirates in these areas are members of the "Abu Sayyaf Group", which consists of Islamic armed rebels. They have abducted and confined 59 ship crews over the last 13 months to obtain money for group operations. The activities of these pirates, abducting and killing crews, have became a significant threat for marine security in the Sulu and Celebes Seas and for logistic activities in Asia. This study examines and analyzes 22 recent incidents in terms of ships gross tonnage, kind, nationality, incident time, location, etc. The identity of the Abu Sayyaf Group, which has been committing this piracy and represents the de facto power behind the actors responsible, is also unpacked, along with current challenges to resolving these conflicts. Finally, responses passing ships, shipping companies, related countries and the international community should make are proposed.

• Korean Journal of Comparative Education
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• v.19 no.2
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• pp.147-173
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• 2009

This research deals with Freinet School in France as a model of open public schools, with focus on the school's operating philosophy, operating contents and characteristics, the cases of educational practices and suggestions for Korea's public education reform. Freinet School has been operated based on the educational philosophy of the French education activist Célestin Freinet(1896-1966). This researcher approached the following four research subjects in order to examine what effects Freinet School can have on the change and reform of Korea's public schools. First: What are the educational effects that Freinet School has on the public educational system in France? Second: What are the operating principles of Freinet School and what are the characteristics of the school's viewpoints and roles towards its teachers and students? Third: What are the kinds of the educational activities and the status of utilization of time and space with regard to Freinet School's operating regulations and the cases of educational practices? Fourth: What suggestions can Freinet School provide for Korea's public educational reform? This researcher have conducted preceding and philological researches on Freinet School pedagogy and analyzed such data as moving images, interviews with teachers, and the books published by Freinet School Teachers' Association.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.46.1-46.1
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• 2011

본 연구에서는 Cu-In-Se나노입자 합성, 코팅 및 후열처리에 의한 비진공 CIS 박막 제조 공정 및 이를 이용하여 제작한 태양전지의 특성에 대해 고찰하고자 한다. Cu-In-Se 나노입자 전구체는 금속 요오드계 출발물질을 피리딘 용매에, 소듐 셀레나이드를 메탄올에 용해시킨 후 이를 혼합하여 저온 콜로이달 방식으로 제조하였다. 제조된 입자를 Raman 분석 결과, Cu-Se 및 In-Se 이원계 상이 혼재되어 있는 것을 알 수 있었다. 본 연구에서는 이와 같이 준비된 나노 입자 전구체를 닥터 블레이드 방법으로 코팅 후 셀렌화 열처리한 결과 약 4%의 광변환 효율을 갖는 태양전지를 제작할 수 있었다.

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.143-144
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• 2007

낮은 포논 에너지를 가지는 대표적인 비정질 광소재인 Ge-Ga-Sb-Se 조성의 셀레나이드 유리에 CsI를 첨가한 찰코할라이드 유리 샘플을 제작하고 CsI 함량에 따른 소재의 광 특성 및 첨가된 $Pr^{3+}$ 이온의 광 특성 변화를 조사하였다. 안정한 비정질 상태를 유지하는 CsI의 함량은 약 7.5 몰%로 제한되었으며, 첨가량에 비례하여 단파장 흡수단 파장이 짧아지는 경향을 보였으나 weak absorption tail이 증가 하였다. $Pr^{3+}$ 이온으로부터 발생하는 1.6 ${\mu}m$대역 형광의 제반특성은 CsI의 첨가와 비교적 무관한 것으로 밝혀졌으며 1.06 ${\mu}m$장에서 측정한 비선형 흡수 계수 역시 CsI의 첨가에 영향을 거의 받지 않는 것으로 판명되었다.

• Journal of Integrative Natural Science
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• v.3 no.2
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• pp.112-116
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• 2010

Prepared CdSe nanoparticles were systems, one of the most studied and useful nanostructures. Semiconductor quantum dots (QDs) have been the subject of much interest for both fundamental reseach and technical applications in recent years, due mainly to their strong size dependent properties and excellent chemical processibility. CdSe nanocrystals were synthesized by using sol-gel process. Synthesized CdSe quantum dots were studied to evaluate the optical, electronic and structural properties using UV-absorption, and photoluminescence (PL) measurement. Prepared CdSe nanoparticles were subjected to sense hydrofluoric acid. Photoluminescence was quenched upon adding of hydrofluoric acid.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.69.1-69.1
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• 2012

원자 한층 또는 수층의 두께를 가진 그래핀과 2차원 나노물질들은 그들의 적층형태의 3차원 물질들과는 두드러지게 다른 전기적, 전자적, 광학적, 화학적, 기계적 성질을 지닌다. 그래핀은 탄소원자들간에 sp2공유결합을 형성하여 뛰어난 기계적, 윤활적 특성을 가지고 있으며, 이황화몰리브덴 또한 좋은 윤활적 특성을 가지고 있다. 본 발표에서는 원자현미경을 이용해서 그래핀, 이황화몰리브덴, 질화붕소, 니오븀 다이셀레나이드 등의 원자 두께 수준의 2차원 나노물질들에서 나타나는 특이한 마찰적 특성들을 보고한다. 특별히 원자수준으로 얇아짐으로 두께에 따른 마찰력의 변화와 2차원물질의 주름에 따른 방향성있는 마찰특성 그리고, 기판에 따른 마찰력의 특성변화를 보고하도록 한다.

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.94-98
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• 2020

The core/shell of nanowires (NWs) with Cu-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We presented CdSe with Cu2+ dopants that were synthesized by a colloidal process. An improvement of the recombination barrier, due to shell supplementation with Cu-doped CdSe quantum dots. The enhanced cell steady state was attributable to TiO2 with Cu-doped CdSe QD supplementation. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 arrays was investigated to represent the merit of core/shell as an electron transport layer in effective devices.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.618-622
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• 2004

Excitation spectra of the 1.6 rm emission originating from $Ho^{3＋}$：$^{5}$ I$_{5}$ \longrightarrow$^{5}$ I$_{7}$ transition in fluoride, sulfide, and selenide glasses were measured at wavelengths around 900nm where the fluorescing $^{5}$ I$_{5}$ level is located. In specific energy range where the frequency upconversion populating $^{5}$ F$_{1}$ state happens, the excitation efficiency of the 1.6 fm emission was deteriorated in fluoride and sulfide hosts. In selenide however spectral line shapes of the excitation spectrum and the '$^{5}$ I$_{8}$ \longrightarrow$^{5}$ I$_{5}$ absorption spectrum looked seemingly identical to each other. Differences in optical nonlinearity as well as electronic band gap energy of the host glasses used are responsible for the experimental observations. On the other hand, codoping of rare earths such as Tb$^{3+}$, Dy$^{3+}$, Eu$^{3+}$, and Nd$^{3+}$ was effective in decreasint the terminating $^{5}$ I$_{7}$ level lifetime. However, at the same time, some of the codopants increased unnecessary absorption at the 1.6 $\mu$m wavelengths via their ground state absorption. Though the lifetime quenching effect of Eu$^{3+}$ was moderate, it exhibited no additional extrinsic absorption at the 1.6 $\mu$m band.EX>m band.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.147-154
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• 2006

Effects of water temperature, salinity and irradiance on the growth of toxic dinoflagellate Alexandrium catenella (AlCt-01) were investigated, which was isolated from Jinhae Bay, Korea. The maximum growth of A. catenella strain was obtained at $150{\mu}E\;m^{-2}s^{-1}$. The ranges of temperature and salinity for the growth of the strain were $15\sim25^{\circ}C$ and $20\sim34$ PSU. The maximum growth rate of A. catenella determined was $0.45d^{-1}$ at $20^{\circ}C$, 30 PSU and $150{\mu}E\;m^{-2}s^{-1}$ We also examined the Se and Fe effects on the toxic dinoflagellate A. catenella in optimal growth conditions. As Fe concentration of medium increased from 0 to $11.7{\mu}M$, growth rate of A. catenella increased and the maximum growth rate(k=0.48 $d^{-1}$) was obtained at $11.7{\mu}M$ of Fe cone. Growth of A. catenella were stimulated at> 1nM of Se.