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수포작용제(HD) 분석을 위한 단일방울 미세농축법 연구
박양기,김성기,손병훈,박명주,Park, Yang-Ki,Kim, Sung-Ki,Son, Byung-Hoon,Park, Myeong-Ju 한국군사과학기술학회 2008 한국군사과학기술학회지 Vol.11 No.2
A fast, simple, inexpensive, and reproducible sample preparation for extraction and analysis of HD in water was studied using single-drop microextraction(SDME) and GC-MS. Operation parameters, such as extraction solvent, extraction time were optimized. The optimized conditions were $1\{mu}L$ trichloroethylene and 10 min extraction time. In these conditions, about 42 times higher enrichment factor(EF) was obtained. The detection limit of HD was $1\{mu}g/L$, and the precision expressed as relative standard deviation was about 9.0%.
3,5-Disubstituted Isoxazole의 합성 및 그 광분해에 관한 연구
박양기,주동준 慶熙大學校 1988 論文集 Vol.17 No.-
The reaction of 1,3-dicarbonyl compounds with hydroxylamine is the method most widely used for the synthesis of 3,5- substituted isoxazoles, such as 3-methyl-5-phenylisoxazole. In this study, 3,5-dimethylisoxazole is treated with methyl iodide and n-butyl bromide in the presence of sodium amide to yield alkylated product at the 5-position of isoxazole ring. Some other 3,5-drsubstituted isoxazoles have been prepared in good to excellent yield by oxidation of the corresponding αβ-unsaturated ketoximes. Isoxazole is known to undergo photoisomerization to form a different 5-membered ring compound. Thus the 3,5-disubstituted is oxazole has been converted to 2,5-disubstituted oxazole upon UV irradiation. In the course of this rearrangement, an azirine intermediate has peen identified. 2-Methyl-5-phenyloxazole, the photolysis product of 3-methyl 5-phenyl-isoxazole with 254 nm, is converted back to the starting material upon irradiation with 300nm UV.
CDMA 스마트 안테나 시스템의 설계 및 구현경 문 건·강 양 기·장 경 희·신 응 순·박 윤 옥·박 재 준본
경문건,강양기,장경희,신응순,박윤옥,박재준 에스케이텔레콤 (주) 1999 Telecommunications Review Vol.9 No.2
본 논문은 (1) 주요 빔형성 방식, 적응처리 알고리즘 및 채널추정 방식에 대해 비교 정리한 후, (2) CDMA 시스템에 적용한 알고리즘 레벨, 송·수신기 레벨, 그리고 시스템 레벨의 설계 및 구현의 예를 보이고, (3) 그 현장시험 성능 결과를 소개함으로써 CDMA 스마트 안테나 시스템을 통한 성능 및 서비스 품질 개선의 실현 가능성을 진단한다. 본 논문에서 제시하는 설계 및 구현 방식은 W-CDMA 시스템에도 적용가능하나, 지면 관계상 역방향 링크상의 N-CDMA 스마트 안테나 시스템의 설계 및 구현 예에 그 논의를 국한시킨다. IS-95/N-CDMA에 기초하여 CDMA 스마트 안테나 테스트베드 시스템이 설계 제작되었으며, 제작된 시스템은 채널코딩, 인터리빙, Long PN 코드, 상용수준의 전력제어 알고리즘 및 RAKE 복조기 운용 등을 생략한 가운데서도 운용시험결과, 약 5×10-3의 평균 BER을 갖는 매우 양호한 수신성능을 보였다. 이 성능은 또한 IMT-2000/W-CDMA 스마트 안테나 시스템 성능에 대한 외삽된 성능(extrapolated performance)으로 평가해 볼 수 있다.
홍양기 ( Yang-ki Hong ),송미영 ( Mi-young Song ),박희원 ( Hee-won Park ),강정하 ( Jung-ha Kang ),이완옥 ( Wan-ok Lee ) 한국어류학회 2017 韓國魚類學會誌 Vol.29 No.2
2014년 9월부터 2015년 8월까지 국내 9개 지점에서 채집된 Anguilla japonica 454개체의 생물학적 특성을 조사한 결과, silvering index (SI) 구분과 GSI의 차이가 큰 pseudo-silver eel 이 소양호에서 2개체 (PS1~PS2)와 금강하구에서 1개체 (PS3)가 확인되었다. Pseudo-silver eel은 외부형태 기준으로는 S2 단계였으나, GSI, 소화관지수 (Gut index) 및 안경지수 (Eye index)에서는 모두 yellow eel 단계인 Y1 및 Y2였고, 생식소 발달단계와 난경에서도 Y2 단계였다. Three pseudo-silver eels (PS1~PS3) were found by analysis of silvering index and biological characteristics of 454 eels, Anguilla japonica, collected from the 9 sites of Korean fresh and brackish waters from September 2014 to August 2015. Two specimens (PS1~PS2) from Lake Soyang and one (PS3) from Geum river estuary were identified as pseudo-silver eel showing a large difference between silvering index and GSI. The external morphology of the pseudo-silver eels were in S2 (late silver eel) stage, but they were classified into Y1 (yellow eel) and Y2 (late yellow eel) stage in GSI, Gut index, Eye index and Y2 stage in gonadal development and mean egg diameter.
박 찬,양기성 강원대학교 경영경제연구소 2022 Asia-Pacific Journal of Business Vol.13 No.2
Purpose - This study compares the performances of dynamic asset allocation strategies using Korean stocks and U.S. dollar, which have been negatively correlated for a long time, to examine the diversification effects in the portfolios of them. Design/methodology/approach - In the current study, we use KOSPI200 index, as a proxy of the aggregated portfolio of Korean stocks, and USDKRW foreign exchange rate to implement various portfolio management strategies. We consider the equally-weighted, risk-parity, minimum variance, most diversified, and growth optimal portfolios for comparison. Findings - We first find the enhancement of risk adjusted returns due to risk reduction rather than return increasement for all the portfolios of consideration. Second, the enhancement is more pronounced for the trading strategies using correlations as well as volatilities compared to those using volatilities only. Third, the diversification effect has become stronger after the global financial crisis in 2008. Lastly, we find that the performance of the growth optimal portfolio can be improved by utilizing the well-known momentum phenomenon in stock markets to select the length of the sample period to estimate the expected return. Research implications or Originality - This study shows the potential benefits of adding the U.S. dollar to the portfolios of Korean stocks. The current study is the first to investigate the portfolio of Korean stocks and U.S. dollar from investment perspective.
민양기,석승한,박현영,정진성,양현덕,도승연,강지숙,이성익 대한의학회 2013 Journal of Korean medical science Vol.28 No.6
Periodontal disease is a predictor of stroke and cognitive impairment. The association between the number of lost teeth (an indicator of periodontal disease) and silent infarcts and cerebral white matter changes on brain CT was investigated in community-dwelling adults without dementia or stroke. Dental examination and CT were performed in 438stroke- and dementia-free subjects older than 50 yr (mean age, 63 ± 7.9 yr), who were recruited for an early health check-up program as part of the Prevention of Stroke and Dementia (PRESENT) project between 2009 and 2010. In unadjusted analyses, the odds ratio (OR) for silent cerebral infarcts and cerebral white matter changes for subjects with 6-10 and > 10 lost teeth was 2.3 (95% CI, 1.38-4.39; P = 0.006) and 4.2 (95% CI, 1.57-5.64; P < 0.001), respectively, as compared to subjects with 0-5 lost teeth. After adjustment for age, education, hypertension, diabetes mellitus, hyperlipidemia, and smoking, the ORs were 1.7 (95% CI, 1.08-3.69; P = 0.12) and 3.9 (95% CI, 1.27-5.02;P < 0.001), respectively. These findings suggest that severe tooth loss may be a predictor of silent cerebral infarcts and cerebral white matter changes in community-dwelling,stroke- and dementia-free adults.