• 전력전자학회논문지
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• 제8권4호
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• pp.313-320
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• 2003

본 논문에서는 부가적인 회로의 추가 없이 IPM 내부 IGBT의 게이트 저항을 시스템에 최적화된 값으로 선정하여 dv/dt 및 di/dt를 감소시키고 이로 인한 전도 EMI 노이즈를 저감하여 엘리베이터 시스템에 최적화된 전련변환장치를 설계한다. 주문형 IPM을 엘리베이터용 인버터 시스템에 최적화하기 위하여 시스템에 적용될 전력변환장치의 게이트 저항에 따른 Spike 전압 및 전동기 서지전압, 스위칭 손실에 따른 IPM 케이스와 방열판의 온도 변화등을 시뮬레이션 및 계측한다. 결과적으로 IPM의 게이트 저항을 시스템에서 요구하는 수명에 따라 최적화하여 전도되는 EMI 노이즈가 특정 주파수 대역에서 약 5∼10 [dB$\mu$Vl 저감됨을 확인할 수 있다.

• Structural Engineering and Mechanics
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• 제89권3호
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• pp.283-300
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• 2024

Machine learning (ML) models based on artificial neural network (ANN) and decision tree (DT) were developed for estimation of axial capacity of concrete columns reinforced with fiber reinforced polymer (FRP) bars. Between the design codes, the Canadian code provides better formulation compared to the Australian or American code. For empirical models based on elastic modulus of FRP, Hadhood et al. (2017) model performed best. Whereas for empirical models based on tensile strength of FRP, as well as all empirical models, Raza et al. (2021) was adjudged superior. However, compared to the empirical models, all ML models exhibited superior performance according to all five performance metrics considered. The performance of ANN and DT models were comparable in general. Under the present setup, inclusion of the transverse reinforcement information did not improve the accuracy of estimation with either ANN or DT. With selective use of inputs, and a much simpler ANN architecture (4-3-1) compared to that reported in literature (Raza et al. 2020: 6-11-11-1), marginal improvement in correlation could be achieved. The metrics for the best model from the study was a correlation of 0.94, absolute errors between 420 kN to 530 kN, and the range being 0.39 to 0.51 for relative errors. Though much superior performance could be obtained using ANN/DT models over empirical models, further work towards improving accuracy of the estimation is indicated before design of FRP reinforced concrete columns using ML may be considered for design codes.

• 한국치위생학회지
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• 제13권4호
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• pp.597-604
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• 2013

Objectives : The purpose of the study is to compare and investigate oral health status between Korean adults living in Korea and the US. Methods : Subjects were 1,785 persons including 399 Korean adults living in Virginia, US and those from the second year 2011 of the 5th National Health and Nutrition Survey. Darta were analyzed using SPSS 12.0 for frequency analysis, t-test, one-way ANOVA, and post-hoc Tukey. Results : 1. In general characteristics, adult living in Korea revealed higher DT and DMFT than those in the US. 2. In oral health status, adult living in Korea revealed higher DT and DMFT than those in the US. 3. The variables affecting oral health status in Korean adults in the US were age, private health insurance and number of tooth brushing. 4. The variables affecting oral health status in adults in Korea included gender, age, private health insurance, smoking, drinking, use of secondary oral hygienic products and number of tooth brushing. Conclusions : It is necessary to emphasize the importance of oral health care and to establish the oral health education in dental care agencies.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 제2회 추계심포지움
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• pp.147-172
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• 1994

Aziridinylbenzoquinones such as 3, 6-diaziridinyl-1, 4-benzoquinone (DZQ) and its 2, 5-methyl analog (MeDZQ) require bioreductive activation in order to elicit their anticancer activities. To determine the involvement of DTD in the activation of these drugs, we have used a ligation-mediated polymerase chain reaction to map the intracellular alkylation sites in a sing1e copy gene at the nucleotide level. We have performed this analysis in two human colon carcinoma cells, one proficient (HT-29) and one deficient (BE) in DT-diaphorase (DTD) activity. In the DTD proficient HT-29 cell line, DZQ and MeDZQ were found to alkylate both 5'-(A/T)G(C)-3' and 5'-(A/T)A-3' sequences. This is consistent with the nucleotide preferences observed when DZQ and MeDZQ are activated by purified DTD to reactive metabolites capable of alkylating DNA in vitro [Lee, C. -S., Hartley, J. A., Berardini, M. D., Butler, J., Siegel., D., Ross, D., & Gibson, N. W. (1992) Biochemistry, 31: 3019-3025]. Surprisingly in the DTD-deficient BE cell line a pattern of alkylation induced by DZQ and MeDZQ similar to that observed in the DTD-proficient HT-29 cells was observed. This suggests that reductive enzymes other than DTD can be involved in activating DZQ and MeDZQ to DNA reactive species in vivo.

• 대한한방소아과학회지
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• 제30권4호
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• pp.77-86
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• 2016

Objectives Hataedock (HTD) is an oral Korean herbal medical oral treatment that removes fetal toxic heat and meconium from new born babies. The purpose of this study is to evaluate whether Hataedock treatment of Duchi extracts has anti-inflammation effects in atopic dermatitis-like skin lesions in House Dust Mite-Induced NC/Nga Mice. Methods The mice were divided into 3 groups (n=10 per group) as follows: the control group (Ctrl group), AD-induced group (AE group), AD-induced with HTD treatment group (DT group). 3-week-old NC/Nga mice were introduced to Hataedock treatment, made of Duchi extract. After 4 weeks, House Dust Mite-Induced application was used six times per week for 3 weeks to induce the first atopic dermatitis, and second AD in 7 weeks after. To examine skin injuries and anti-inflammatory effect, PKC, MMP-9, iNOS immunohistochemistry were used. Results The alleviate effect of the skin damage and angiogenesis was observed in DT group. The damage of stratum corneum, hyperplasia, edema, infiltration of lymphocytes and distribution of capillary were decreased in DT group. Also, the study results suggested that Hataedock treatment made of Duchi extracts in DT group remarkably decreased skin damages by 51% (p < 0.001), as well as PKC by 91%, MMP-9 by 48% (p < 0.001), iNOS by 51% (p < 0.001). Conclusions Based on the study results, we observed that Hataedock treatment of Duchi extracts alleviates AD by diminishing various inflammatory cytokines, initial steps of AD development, in the skin lesions. Potential applications for prevention and treatment of atopic dermatitis are expected.

• 대한의용생체공학회:의공학회지
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• 제12권4호
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• pp.261-266
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• 1991

As the ensemble averaged dz/dt signal during exercise gets smoothed, it is difficult to find the distinctive marks for estimation of stroke volume. The cross correlation function was made use of estimating these marks for automatic calculation by computer from the ensemble averaged dz/dt signal. LVET( Left Ventricular Ejection Time) and stroke volume were estimated based on the calculated parameters from the characteristic points. LVET, stroke volume calculated by hand, by the ensemble average and the cross correlation were compared for accuracy validation.

• 한국안전학회지
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• 제8권4호
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• pp.95-100
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• 1993

In power transistor switching circuit have shunt snubber(dv/dt limiting capacitor) and series snubber (di/dt limiting inductor). The shunt snubber is used to reduce the turn-off switching loss and the series snubber is used to reduce the turn-on switching loss. Design procedures are derived for selecting the capacitance, inductor and resistance to limit the peak voltage and current values. The action of snubber is analyzed and applied to the design for safety PWM inverter.

• 대한의용생체공학회:의공학회지
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• 제28권6호
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• pp.817-824
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• 2007

Tractography using Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) is a method to determine the architecture of axonal fibers in the central nervous system by computing the direction of the principal eigenvector in the white matter of the brain. However, the fiber tracking methods suffer from the noise included in the diffusion tensor images that affects the determination of the principal eigenvector. As the fiber tracking progresses, the accumulated error creates a large deviation between the calculated fiber and the real fiber. This problem of the DT-MRI tractography is known mathematically as the ill-posed problem which means that tractography is very sensitive to perturbations by noise. To reduce the noise in DT-MRI measurements, a tensor-valued median filter which is reported to be denoising and structure-preserving in fiber tracking, is applied in the tractography. In this paper, we proposed the modified gradient descent method which converges fast and accurately to the optimal tensor-valued median filter by changing the step size. In addition, the performance of the modified gradient descent method is compared with others. We used the synthetic image which consists of 45 degree principal eigenvectors and the corticospinal tract. For the synthetic image, the proposed method achieved 4.66%, 16.66% and 15.08% less error than the conventional gradient descent method for error measures AE, AAE, AFA respectively. For the corticospinal tract, at iteration number ten the proposed method achieved 3.78%, 25.71 % and 11.54% less error than the conventional gradient descent method for error measures AE, AAE, AFA respectively.

• Journal of Microbiology and Biotechnology
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• 제4권1호
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• pp.36-40
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• 1994

A water sample was taken from a black smoker chimney of a deep-sea hydrothermal vent by using an unmanned submersible "Dolphin 3K". The temperature of the hydrothermal fluid from the black smoker was $276^{\circ}C$. After isolation by repeated serial dilutions, An extremely thermophilic bacterial strain was selected. The strain designated as DT1331, was an anaerobic, non-motile, coccoid shaped bacterium with about 0.5 to $1.0\;\mu\textrm{m}$ in diameter. The strain DT1331 could grow up to $93^{\circ}C$, but the optimum temperature of this strain was $80^{\circ}C$. The growth occurred in the pH range of 4.5 to 8.5 and the optimum pH was 6.0. The strain DT1331 required 1% to 5% NaCl for growth and cell lysis was observed below 1% NaCl concentration. The bacterium could grow on polypeptides such as tryptone, peptone, soytone and on proteins such as casein or gelatin. However, no growth was observed on single amino acids, sugar and organic acids. Hydrogen gas was detected slightly during growth. This bacterium obligately required elemental sulfur and hydrogen sulfide gas was produced during growth.

• Journal of Korean Neurosurgical Society
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• 제55권4호
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• pp.208-211
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• 2014

Recently, the increasing rates of facial nerve preservation after vestibular schwannoma (VS) surgery have been achieved. However, the management of a partially or completely damaged facial nerve remains an important issue. The authors report a patient who was had a good recovery after a facial nerve reconstruction using fibrin glue-coated collagen fleece for a totally transected facial nerve during VS surgery. And, we verifed the anatomical preservation and functional outcome of the facial nerve with postoperative diffusion tensor (DT) imaging facial nerve tractography, electroneurography (ENoG) and House-Brackmann (HB) grade. DT imaging tractography at the 3rd postoperative day revealed preservation of facial nerve. And facial nerve degeneration ratio was 94.1% at 7th postoperative day ENoG. At postoperative 3 months and 1 year follow-up examination with DT imaging facial nerve tractography and ENoG, good results for facial nerve function were observed.