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원자흡수분광법에 의한 칼슘분석에서 양이온들의 방해작용에 따른 이트륨의 해방효과에 관한 연구
崔熙善 水原大學校 1987 論文集 Vol.5 No.-
In the atomic absorption spectrometry using an air-acetylene flame, theinterferences of ??,??,??, and ??, on the calcium absorption and the repression of this interference by the addition of yttrium have been studied. The interference by ?? and ?? is completely released by the addition of yttrium three times as much interfering cation, but the interference by ?? and ?? is not completely released.
敎育委員會의 位相에 관한 硏究 : 地方議會와의 關係를 中心으로
崔熙善 仁川敎育大學校 1993 論文集 Vol.27 No.1
This study intended to search policy direction and tasks of governing local education in the age of local control. Specifically, this study gave focuses on the status of the local of education with the relation of local assemblies. Namelly, (1) re-examining principles and directions of current "Act of Local Education Autonomy", (2) reallocating power and responsibilities of performing local educational tasks. The methodology employed in this study were literature reviews, interviews with central and local educational administrators, surveys through local educational agencies, expert conferences, etc. Some major findings of thie study were as followes: (1) Public education should become one of the most inportant tasks which local government must give a high priority on the development of education in their region, (2) The board of education in Korea have more powers and responsibilities for the regional education development, (3) The current problems related to the organzation of the board of education is found in status, member, election, etc, of it. It is not desirable to the current status of the board of education. Therefore, findings of this study are applicable for the improvement of status of the board of education in Korea and those countries with similiar educational governance and historical backgrounds.
최희선,김현태,송지수,신터전,현홍근,김정욱,장기택,김영재 대한소아치과학회 2023 大韓小兒齒科學會誌 Vol.50 No.4
This study aims to investigate changes in dental service use among pediatric patients during the COVID-19 pandemic. The analysis was performed by collecting information about the number of visits, age, gender, diagnoses, and treatments for patients at the Pediatric Dentistry Department of Seoul National University Dental Hospital from January 2017 to December 2022. Compared with the period from 2017 to 2019, the total number of visits decreased during the COVID-19 pandemic, with a substantial decline in 2020. Patients in all age groups, except those aged 10 - 14, experienced decreased visits, and there was no significant gender difference. Z29.8 (need for other specified prophylactic measures) declined in all age groups, especially among those aged 0 - 4, except for those 20 years and older. K02.1 (caries of dentine) was sought by the age groups in the following order: 10 - 14, 15 - 19, 5 - 9, and 0 - 4 years, with the most significant decrease in the 0 - 4 years age group compared to others. K07.4 (malocclusion, unspecified) decreased in younger groups aged 9 and below but increased in older groups aged 10 and above. During the period from 2020 to 2022, preventive, restorative, pulp, and trauma treatments decreased, but surgical and orthodontic treatments increased compared with the previous three years. The use of sedation decreased and general anesthesia increased during COVID-19 compared to pre-pandemic. This study describes the impact of the COVID-19 pandemic on pediatric dentistry, making it a valuable reference for future pandemics.
비이온성 미셀용액에서 Fe(Ⅲ), Co(Ⅱ), Ni(Ⅱ) 및 Cu(Ⅱ)의 분광광도법 정량
최희선 수원대학교 기초과학연구소 1996 基礎科學論文集 Vol.5 No.-
Various metal ions were determined by UV-visible spectrophotometry as their complexes with 1-nitroso-2-naphthol in the presence of micellar medium. In Tween 80 medium, it was found that the 1-nitroso-2-naphthol complexes of Fe(Ⅲ), Co(Ⅱ), Ni(Ⅱ), and Cu(Ⅱ) highly absorbed at pH 1.0, 5.0, 8.0 and 9.0, respectively, and that λ_max scarcely shifted around these pHs. The metal-1-nitroso-2-naphthol complexes could be quantitatively chelated if 1-nitroso-2-naphthol, chelating agent, was added to the sample solution more 20 times than the amount of metal ions. And, the calibration curves of metal-1-nitroso-2-naphthol with good linearity were obtained in 2.5% Tween 80 medium. Therefore, it is expected to determine various metal ions simply and conveniently in real samples.
Dibenzoylmethane 착물을 Benzophenone으로 흡착 분리한 후 Mn (Ⅱ)의 원자분광법 정량
崔熙善 水原大學校 2001 論文集 Vol.19 No.-
A method for the determination of Mn(Ⅱ) after separating by the adsorption of its dibenzoylmethane complex onto benzophenone was studied. When dibenzoylmethane as a complexing agent was added to the sample solution by 50 times of moles of Mn(Ⅱ). an effective separation was achieved. And, the other conditions such as pH of solution, amount of benzophenone, and stirring time were optimized to 6.0, 0.15g and 60min., respectively. Under the optimum conditions, the calibration curve of Mn(Ⅱ) was obtained over range 0.05∼1.0㎍/mL. The detection limit and the determination limit of Mn(Ⅱ) were 3.5ng/mL and 11.6ng/mL, respectively. Recovery yield of Mn(Ⅱ) in river water was more than 95%.