• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.236-243
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• 2018

A series of $Er^{3+}/Yb^{3+}$ co-doped fluorophosphate glasses with varying $YbF_3$ concentration were prepared by a high temperature melt quenching technique. Absorption and emission cross-sections were determined by using the McCumber theory. The larger emission cross-section ($9.86{\times}10^{-21}cm^2$) and longer fluorescence lifetime (12.37 ms) were obtained for the $^4I_{13/2}{\rightarrow}^4I_{15/2}$ transition of ABS3Er4Yb glass. The sensitivity and temperature of the maximum sensitivity were evaluated by the fluorescence intensity ratio method from the measured upconversion spectra. The results were discussed and compared to the other reported glasses.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.705-712
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• 2006

The synthesis of a new series of 1 $\beta$-methylcarbapenems having 5-(1,2-disubstituted ethyl)pyrrolidine moiety are described. Their in vitro antibacterial activities against both Gram-positive and Gram-negative bacteria were tested and the effect of substituents on the pyrrolidine ring was investigated. Among them, compound (IIIc) having 1-methoxyimino-2-hydroxyethyl moiety showed the most potent antibacterial activity.

• Journal of Korean Neurosurgical Society
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• 제67권2호
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• pp.237-248
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• 2024

Objective : Postoperative data on Cushing's disease (CD) are equivocal in the literature. These discrepancies may be attributed to different series with different criteria for remission and variable follow-up durations. Additional data from experienced centers may address these discrepancies. In this study, we present the results obtained from 96 endoscopic transsphenoidal surgeries (ETSSs) for CD conducted in a well-experienced center. Methods : Pre- and postoperative data of 96 ETSS in 87 patients with CD were included. All cases were handled by the same neurosurgical team between 2014 and 2022. We obtained data on remission status 3-6 months postoperatively (medium-term) and during the latest follow-up (long-term). Additionally, magnetic resonance imaging (MRI) and pathology results were obtained for each case. Results : The mean follow-up duration was 39.5±3.2 months. Medium and long-term remission rates were 77% and 82%, respectively. When only first-time operations were considered, the medium- and long-term remission rates were 78% and 82%, respectively. The recurrence rate in this series was 2.5%. Patients who showed remission between 3-6 months had higher long-term remission rates than did those without initial remission. Tumors >2 cm and extended tumor invasion of the cavernous sinus (Knosp 4) were associated with lower postoperative remission rates. Conclusion : Adenoma size and the presence/absence of cavernous sinus invasion on preopera-tive MRI may predict long-term postoperative remission. A tumor size of 2 cm may be a supporting criterion for predicting remission in Knosp 4 tumors. Further studies with larger patient populations are necessary to support this finding.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3635-3639
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• 2012

A series of new diarylureas possessing aminoisoquinoline scaffold was synthesized, and their in vitro antiproliferative activity against A375P human melanoma cell line was tested. Compounds 1d, 1l, 1n, 1p, 1q, and 1t showed superior potency against A375P to Sorafenib. The highest potency was shown by compound 1p possessing 3,5-bis(trifluoromethyl)phenyl terminal ring with $IC_{50}$ value of $0.41{\mu}M$.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2003년도 하계학술대회 논문집
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• pp.137-137
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• 2003

• 한국농림기상학회지
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• 제23권4호
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• pp.415-423
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• 2021

NCAM-LAMP 중기예측 자료의 통계적 후처리와 개선을 위하여 R 기반의 지점 시계열 자료 검증 체계를 구축하였다. 이 시계열 검증체계를 이용하여 기상청 AWS 관측 자료와 NCAM-LAMP, KMA GDAPS 중기예측 모델 자료를 비교하였다. 이를 위해 관측 지점에 가장 근접한 모델 위도 및 경도 자료를 추출하여 총 9개 지점을 선정하였다. 각 지점에 대해 NCAM-LAMP, GDAPS 모델의 기온, 강수량, 풍속 일평균 예측 자료를 관측과 비교한 결과, 모델들은 풍속의 과대예측 경향을 뚜렷이 보였으며, 기온과 강수의 경우에는 두 모델의 예측력이 월별 및 변수별로 다르게 나타났다. 이를 바탕으로 본 연구에서는 통계적 기법을 개발하여 NCAM-LAMP가 가지고 있는 오차를 줄이고자 하였다. 모델 오차를 줄이기 위해 일반적으로 쓰이는 MOS(Model Output Statistics)기법 중에 인공지능 SVM(Support vector machine) 방식을 8~10월 기간에 적용한 결과, 8월에 비해서 10월이, 기온 변수에 비해서 바람과 강수 변수가 개선된 효과를 보여주었다. 이러한 결과는 풍속의 과대예측을 줄이고, 농림 가뭄지수와 산사태 예측 등을 개선시키며, 지역 수치예보 모델이 시간 적분됨에 따라 영역 내 예측가능성이 점점 저하되는 현상을 완화시키는데 SVM 방법이 일정 부분 기여할 수 있음을 가리키며, 현업 표출 중인 NCAM Agro-Meteogram 개선에도 도움을 줄 것으로 기대된다.

• 한국정보시스템학회지:정보시스템연구
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• 제31권3호
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• pp.197-220
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• 2022

Purpose The purpose of this study is to identifies the demand pattern categorization of repair parts of Automotive After-sales Service(A/S) and proposes a demand prediction model for Auto repair parts using Long Short-Term Memory (LSTM) of artificial neural networks (ANN). The optimal parts inventory quantity prediction model is implemented by applying daily, weekly, and monthly the parts demand data to the LSTM model for the Lumpy demand which is irregularly in a specific period among repair parts of the Automotive A/S service. Design/methodology/approach This study classified the four demand pattern categorization with 2 years demand time-series data of repair parts according to the Average demand interval(ADI) and coefficient of variation (CV²) of demand size. Of the 16,295 parts in the A/S service shop studied, 96.5% had a Lumpy demand pattern that large quantities occurred at a specific period. lumpy demand pattern's repair parts in the last three years is predicted by applying them to the LSTM for daily, weekly, and monthly time-series data. as the model prediction performance evaluation index, MAPE, RMSE, and RMSLE that can measure the error between the predicted value and the actual value were used. Findings As a result of this study, Daily time-series data were excellently predicted as indicators with the lowest MAPE, RMSE, and RMSLE values, followed by Weekly and Monthly time-series data. This is due to the decrease in training data for Weekly and Monthly. even if the demand period is extended to get the training data, the prediction performance is still low due to the discontinuation of current vehicle models and the use of alternative parts that they are contributed to no more demand. Therefore, sufficient training data is important, but the selection of the prediction demand period is also a critical factor.

• Archives of Pharmacal Research
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• 제22권5호
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• pp.491-495
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• 1999

In order to examine the effects of N-substituted alkyl group on the anticonvulsant activities of N-Cbz-$\alpha$-aminoglutarimides as novel anticonvulsants with broad spectrum, a series of (R) or (S) N-Cbz-$\alpha$-amino-N-alkylglutarimides (1 and 2) were prepared from the corresponding (R) or (S) N-Cbz-glutamic acid and evaluated for the anticonvulsant activities in the maximal electroshock seizure (MES) test and pentylenetetrazol induced seizure(PTZ) test, including the neurotoxicity. The most potent compound in the MES test was (S) N-Cbz-$\alpha$-amino-N-methylglutarimide($ED_{50}$=36.3 mg/kg, PI=1.7). This compound was also most potent in the PTZ test ($ED_{50}$=12.5 mg/kg, PI=5.0). The order of anticonvulsant activities against the MES test as evaluated form $ED_{50}$ values for (R) series was N-methyl > N-H > N-ethyl > N-allyl ; for the (S) series N-methyl > N-H > N-ethyl > N-alkyl > N-isobutyl compound. Against the PTZ tests, the order of anticonvulsant activities showed similar pattern ; for the (R) series, N-methyl > N-H > N-ethyl > N-allyl ; for the (S) series N-methyl > N-H > N-ethyl > N-allyl > N-isobutyl compound. From the above results, N-substituted alkyl groups were though to play an important role for the anticonvulsant activities of N-Cbz-$\alpha$-amino-N-alkylgutarimides.

• 대한기계학회논문집B
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• 제36권8호
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• pp.797-802
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• 2012

본 연구에서는 두 대의 히트펌프를 이용하여 $60^{\circ}C$의 난방 공급을 하는 경우에 대하여, 병렬운전을 할 경우의 성능과 직렬운전을 할 경우의 성능을 서로 비교함으로써, 직렬운전에 의한 성능 향상 가능성을 연구하였다. 두 경우의 성능을 공정하게 비교하기 위하여, 히트펌프를 구성하는 열교환기의 전열면적을 고정하였으며, 부하측 및 열원측의 입구 유량 및 온도 조건을 고정하였다. 또한, 보다 현실적인 결과를 위하여 열교환기 내 열전달 및 압력강하 특성을 고려하였다. 시뮬레이션 결과, 직렬운전 시스템의 난방성능계수가 병렬운전 시스템의 난방성능계수에 비해 본 연구의 시뮬레이션 조건 하에서 약 5% 향상 될 수 있음을 관찰하였다.

• Journal of Power Electronics
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• 제4권3호
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• pp.138-151
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• 2004

In this paper, a constant frequency phase shifting PWM-controlled voltage source full bridge-type series load resonant high-frequency inverter using the $4^{th}$ generation IGBT power modules is presented for innovative consumer electromagnetic induction heating applications, such as a hot water producer, steamer and super heated steamer. The bridge arm side link passive capacitive snubbers in parallel with each power semiconductor device and AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is evaluated and discussed on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency inverter topology, what is called, DE class type, including the variable-power variable-frequency regulation function can expand zero voltage soft switching commutation area even under low output power setting ranges, which is more suitable and acceptable for newly developed induction heated dual pack fluid heaters. Furthermore, even the lower output power regulation mode of this high-frequency load resonant tank inverter circuit is verified so that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.