• 전기학회논문지
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• 제66권1호
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• pp.211-215
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• 2017

The APF (All Pass Filter) method that utilizes the computational power of the controller is most commonly used. However, since the calculation of the filter coefficient is complicated, the calculation is carried out in advance. It is difficult to apply it to the frequency fluctuation environment because the coefficient value is fixed. In this paper, a new control method of single phase PLL that can be usefully used in PWM converter device for electric railway was explained. Comparison and examination of similarities and differences between the conventional APF method PLL controller method and the newly proposed modified MA filter method PLL technique were performed. The possibility of implementation of the modified MA filter method through computer simulation was analyzed. In conclusion, the method proposed as the conclusion was applied to the APU(Auxiliary Power System) of 8200 Series Electric Locomotive and its usefulness was confirmed.

• 대한화학회지
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• 제15권5호
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• pp.281-284
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• 1971

Copolymerization of glycidyl methacrylate(GMA) with methyl acrylate(MA) and the reaction of the copoly mer with primary amines were investigated. The monomer reactivity ratios were determined by Mayo-Lewis intersecting method. $r_1=0.22{\pm}0.03(GMA),\;r_2=0.50{\pm}0.07(MA)$. GMA and MA copolymerized to afford the polymer having good alternate arrangements of the units of the monomers.

• 암석학회지
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• 제10권3호
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• pp.172-178
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• 2001

1997읜 이후 한국기초과학지원연구원에 K-Ar 연대 측정 시스템이 도입되어 현재 이용중이다. 이 시스템은 흑연전기로, 가스 전처리 장치, 질량분석기와 자료획득장치로 구성되어 있으며 K-Ar연대 측정은 $^{38}$ Ar을 스파이크로 이용하는 동위원소 희석법에 의한 정밀한 Ar 농도 측정과 원자흡광분석을 통한 K 정량분석에의해 이루어진다. 연대가 잘 알려진 K-Ar 연대측정용 표준물질을 이용하여 시스템의 정밀성과 정확성을 확인하였다. 백만년 이하의 연대를 갖는 시료의 경우 질량분석기의 감도와 질량차별지수의 미약한 변화에도 큰영향을 받기 때문에 정확한 연대 측정이 곤란하나 중생대 및 제 3기의 K-Ar 연대를 갖는 표준시료의 연대를 측정했을 때, 믿을 만한 결과를 내고 있다. $92.6\pm$0.6 Ma의 연대가 알려진 SORI93혹운모의 경우 92.1$\pm$1.1 Ma의 연대를 얻을 수 있었고, $18.5\pm$0.6 Ma의 Bern4M 백운모는 권고치와 유사한 $17.8\pm$0.2 Ma의 연대를 얻을 수 있었다. .

• 한국학교수학회논문집
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• 제17권4호
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• pp.589-611
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• 2014

정도의 차이는 있겠지만 사람이면 누구나 불안을 경험하기 때문에 수학불안증에 대한 연구는 수학교육이 발달하면서부터 주요 주제가 되어왔다. 최근엔 기기의 발달로 그간 연구하기 힘들었던 뇌 과학 연구의 새 영역이 가능해진 바 본 연구에서는 시대적 변화에 따른 수학불안증을 재조명하고, 이를 측정할 수 있는 방법과 수학불안증 감소 방안에 대한 선행연구의 결과를 종합적으로 분석하여 앞으로의 연구방향에 시사점을 얻고자 하였다. 연구결과로써 몇 안 되는 뇌 과학적 접근을 시도한 연구에서는 단순연산과제만을 사용하였는데 심지어 대학생을 대상으로 한 연구에서도 이와 유사한 문제를 사용하였다. 검사지를 활용한 연구에서는 인지적, 정의적 영역을 모두 조사할 수 있는 다차원적 검사척도가 개발되었다. 수학불안증 감소를 위한 처치로는 인지적 행동적 방법에 체계적 둔감법, 이완훈련, 그리고 이들을 복합적으로 사용한 임상상담기법 등이 사용되었으며 교수 학습 방법으로 STAD 교수법, 쓰기기법 등 개발되었으나 좀 더 세분화되고 신뢰도 있는 방안들이 앞으로 더 많이 연구되어져야함을 알 수 있었다.

• 분석과학
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• 제33권1호
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• pp.23-32
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• 2020

Methamphetamine (MA) is the most common and available drug of abuse in Korea and its primary metabolite is amphetamine (AP). Detection of AP derivatives, such as MA, AP, phentermine (PT), MDA, MDMA, and MDEA by the use of immunoassay screening is not reliable and accurate due to cross-reactivity and insufficient specificity/sensitivity. Therefore, the analytical process accepted by most urine drug-testing programs employs the two-step method with an initial screening test followed by a more specific confirmatory test if the specimen screens positive. In this study, a gas chromatography-mass spectrometric (GC-MS) method was developed and validated for confirmation of MA and AP in human urine. Urine sample (500 µL) was added with N-isopropylbenzylamine as internal standard and ethyl chloroformate as a derivatization reagent, and then extracted with 200 µL of ethyl acetate. Extracted samples were analysed with GC-MS in the SIM/ Scan mode, which were screened by Cobas c311 analyzer (Roche/Hitachi) to evaluate the efficiency as well as the compatibility of the GC-MS method. Qualitative method validation requirements for selectivity, limit of detection (LOD), precision, accuracy, and specificity/sensitivity were examined. These parameters were estimated on the basis of the most intense and characteristic ions in mass spectra of target compounds. Precision and accuracy were less than 5.2 % (RSD) and ±14.0 % (bias), respectively. The LODs were 3 ng/mL for MA and 1.5 ng/mL for AP. At the screening immunoassay had a sensitivity of 100% and a specificity of 95.1 % versus GC-MS for confirmatory testing. The applicability of the method was tested by the analysis of spiked urine and abusers' urine samples.

• 한국세라믹학회지
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• 제53권1호
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• pp.24-33
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• 2016

The grafting reaction for maleic anhydride (MA) onto high density polyethylene (HDPE) was investigated from solution process with initiators. The chemical modification of neat HDPE was carried out with various contents of MA (3-21 wt.%) and initiator (0.2-1 wt.%) at different temperature ($80-130^{\circ}C$). The grafting degree was obtained from the titration and the highest grafting degree was 3.1%. The grafting degree increased as the content of MA and initiator increased, however, the highest grafting degree was demonstrated for a particular content of MA and initiator. In the non-isothermal crystallization kinetics, the Ozawa model was unsuitable method to investigate the crystallization behavior of MA onto HDPE, whereas the Avrami and Liu models found effective. The crystallization rate was accelerated as the cooling rate increased, but postponed by combination of MA onto neat HDPE backbone.

• 생약학회지
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• 제43권1호
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• pp.46-53
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• 2012

This study was conducted to investigate the change of antioxidant activity and ingredient in 4 species medicinal plant by processing. As a result, EtOAc extract and n-BuOH extract obtained from Cistanche deserticola Y. C. Ma and processed Cistanche deserticola Y. C. Ma showed difference on the experiment of antioxidant activity by DPPH method. Change of ingredient also was confirmed by TLC and HPLC analyses. Two main compounds of antioxidant activity change were isolated by column chromatography from the EtOAc extract and n-BuOH extract of Cistanche deserticola Y. C. Ma. The chemical structure of the compound 1 isolated from EtOAc extract of Cistanche deserticola Y. C. Ma was elucidated as 2'-acetylacteoside by means of IR and NMR analyses. Also, the chemical structure of the compound 2 isolated from n-BuOH extract of Cistanche deserticola Y. C. Ma was confirmed as acteoside. The antioxidant activity of processed Cistanche deserticola Y. C. Ma. was declined by 3 time decrements of 2'-acetylacteoside such as 1.89 mg/g to 0.62 mg/g and 2 time decrements of acteoside such as 5.81 mg/g to 2.67 mg/g by processing.

• 공업화학
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• 제32권4호
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• pp.483-486
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• 2021

Catalytic ozonation of methyl ethyl ketone (MEK) has been examined over mesoporous MnO_x/Al₂O₃ (MA) catalysts developed by a solvent deficient method using two different manganese precursors including manganese chloride (C) and manganese sulfate (S) at room temperature. The maximum catalytic activities of MA with C (MEK removal efficiency and ozone decomposition of 98.4 and 93.7%, respectively) were higher than those of MA with S (MEK removal efficiency and ozone decomposition of 96 and 68%, respectively). Also the catalytic stability of MA with C was much higher than that of MA with S. The physico-chemical properties of catalysts are well correlated with the activity results, which confirmed that fine dispersion of MnO_x species with high ratios of Mn³⁺/Mn⁴⁺ and more acid sites are attributed to the higher catalyst stability for the MA-C catalyst.

• 대한한의학원전학회지
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• 제26권1호
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• pp.1-15
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• 2013

Objective : We tried to seek for conflicts of views among the contents in Sasang Constitutional Medicine and Traditional Medicine based on Huangdi's Internal Classic, and to study about the Range of Lee Je-Ma's Works, therefore finding out the limit of Sasang Constitutional Medicine in view of learning contents and practice of theory. Method : Through the texts of Longevity and Life Preservation in Eastern Medicine, such subjects will be investigated as Lee Je-Ma(李濟馬)'s comments on Huangdi's Internal Classic and views on the herbal medicine, the relations among five viscera(五臟), taeguk(太極), four-constitution(四象), etc. Result : Lee Je-Ma's Sasang Constitutional Medicine does not goes well in harmony with the traditional physiology which is based on the functional five zang system developed in Huangdi's Internal Classic, and is hard to understand because of its four division method rooted in confucius academy. Conclusion : Lee Je-Ma's view of medicine is one of the practical and valuable parts of Korean Medicine, however, its extreme four-division structure theory could be difficult to be accepted as its whole form. This is because he studied himself as a confucian, so that his work might rather be confucian than medical. When he fully devoted himself to Sasang Constitutional Medicine, he already took his age much.

• 한국식품과학회지
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• 제26권5호
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• pp.545-551
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• 1994

식용 가능성이 있는 식물 49종의 열매, 줄기, 잎, 껍질 혹은 뿌리를 75% ethanol을 용매로 추출물을 얻고 이를 Listeria monocytogenes ATCC 19111, L. monocytogenes ATCC 19112, L. monocytogenes ATCC 19113, L. monocytogenes ATCC 19114 및 L. monocytogenes ATCC 15313을 대상으로 증식저해 정도를 disk method로 검색하고 효과가 있는 것은 액체 배지에 농도별로 첨가, 그 효과를 비교하였다. L. monocytogenes ATCC 19111에 비교적 높을 항균성을 보인 식물의 ethanol 추출물은 털진득찰, 뽕나무이고 L. monocytogenes ATCC 19112와 ATCC 19114에는 뽕나무, ATCC 19113에는 고삼, 뽕나무, ATCC 15313에는 뽕나무, 꿀풀, 회향 등 이었다 이들 식물 추출물중 광범위하게 항균성을 나타내는 뽕나무껍질 추출물은 실험한 L. monocytogenes 5종 모두에 대하여 500ppm 첨가 수준에서 대부분 완전 증식억제 현상을 보였다.