• Environmental Engineering Research
• /
• 제24권2호
• /
• pp.347-353
• /
• 2019

Although membrane distillation (MD) has great promise for desalination of saline water sources, it is crucial to improve its thermal efficiency to reduce the operating cost. Accordingly, this study intended to examine the thermal energy efficiency of MD modules in a pilot scale system. Two different modules of hollow fiber membranes were compared in direct contact MD mode. One of them was made of polypropylene with the effective membrane area of $2.6m^2$ and the other was made of polyvinylidene fluoride with the effective membrane area of $7.6m^2$. The influence of operation parameters, including the temperatures of feed and distillate, feed flow rate, and distillate flow rate on the flux, recovery, and performance ratio (PR), was investigated. Results showed that the two MD membranes showed different flux and PR values even under similar conditions. Moreover, both flow rate and temperature difference between feed and distillate significantly affect the PR values. These results suggest that the operating conditions for MD should be determined by considering the module properties.

• 대한수학회보
• /
• 제30권2호
• /
• pp.265-275
• /
• 1993

In this paper, we study the monotonicity of the Dittert function (abb. MD) on the line segment from A .mem. $K_{n}$ to J$_{n}$ generalizing both the Dittert conjecture and the Monotonicity conjecture for permanent, and obtain a sufficient condition on A .mem. $K_{n}$ for which the MD holds. It is also proved that if A .mem. $K_{n}$ satisfies the Dokovic inequality (1.2) then MD holds for A, and a subclass of $K_{n}$ for which MD holds is found. is found.

• Bulletin of the Korean Chemical Society
• /
• 제35권8호
• /
• pp.2403-2409
• /
• 2014

Absolute isotope ratio is a critical constituent in determination of atomic weight. To measure the absolute isotope ratio using a mass spectrometer, mass discrimination factor, $f_{MD}$, is needed to convert measured isotope ratio to real isotope ratio of gas molecules. If the $f_{MD}$ could be predicted, absolute isotope ratio of a chemical species would be measureable in absence of its enriched isotope pure materials or isotope references. This work employed gravimetrically prepared isotope mixtures of argon (Ar) to obtain $f_{MD}$ at m/z of 40 in the magnetic sector type gas mass spectrometer (gas/MS). Besides, we compare the nitrogen isotope ratio of nitrogen trifluoride ($NF_3$) with that of nitrogen molecule ($N_2$) decomposed from the same $NF_3$ thermally in order to identify the difference of $f_{MD}$ values in extensive m/z region from 28 to 71. Our result shows that $f_{MD}$ at m/z 40 was $-0.044%{\pm}0.017%$ (k = 1) from measurement of Ar artificial isotope mixtures. The $f_{MD}$ difference in the range of m/z from 28 to 71 is observed $-0.12%{\pm}0.14%$ from $NF_3$ and $N_2$. From combination of this work and reported $f_{MD}$ values by another team, IRMM, if $f_{MD}$ of $-0.16%{\pm}0.14%$ is applied to isotope ratio measurement from $N_2$ to $SF_6$, we can determine absolute isotope ratio within relative uncertainty of 0.2 %.

• International Journal of Advanced Culture Technology
• /
• 제8권2호
• /
• pp.12-17
• /
• 2020

This study was a similar experimental study that analyzed the effect by applying the learning portfolio completion. The study period lasted from October 1, 2019 to November 20, 2019. A total of 47 people participated in the study, and the effectiveness of the program was analyzed with the SPSS 18.0 program for critical thinking disposition. The statistical analysis method was frequency analysis and paired t-test. As a result of the analysis, the critical thinking disposition increased significantly in the application of the learning portfolio completion (Truth-seeking MD= -0.05, p <0.01), Open-mindness MD= 0.11, p <0.001), Analyticity MD= 0.76, p <0.001), Systematicity MD= -.25, p <0.001), Self-confidence MD=-0.54, p <0.001), Inquisitiveness MD=0.29, p <0.001), Maturity MD=-.0.33, p <0.001). In conclusion, the teaching method applied with the learning portfolio completion actually helped nursing students learn nursing students learn based on critical thinking. Based on these result, further research using learning portfolio is to be done and more systematic and practical application of learning portfolio completion to nursing students. This study would be used as a basic data for the study guideline development for learners.

• Bulletin of the Korean Chemical Society
• /
• 제23권1호
• /
• pp.107-111
• /
• 2002

The OSS2 (Oj？me-Shavitt-Singer 2)[L. Oj？me et al., J. Chem. Phys. 109, 5547 (1998)] model for the solvated proton in water is examined for $H_2O,\;H_3O^+,\;H_5O_2^+,\;H_7O_3^+,\;and\;H_9O_4^-$ by molecular dynamics (MD) simulations. The equilibrium molecular geometries and energies obtained from MD simulations at 5.0 and 298.15 K agree very well with the optimized calculations.

• Nutrition Research and Practice
• /
• 제7권4호
• /
• pp.281-286
• /
• 2013

We examined the effect of parental folate deficiency on the folate content, global DNA methylation, folate receptor-alpha (FR${\alpha}$), insulin-like-growth factor-2 (IGF-2) and -1 receptor (IGF-1R) in the liver and plasma homocysteine in the postnatal rat. Male and female rats were randomly fed a folic acid-deficient (paternal folate-deficient, PD and maternal folate-deficient, MD), or folic acid-supplemented diet (paternal folate-supplemented, PS and maternal-folate-supplemented, MS) for four weeks. They were mated and grouped accordingly: $PS{\times}MS$, $PS{\times}MD$, $PD{\times}MS$, and $PD{\times}MD$. Pups were killed on day 21 of lactation. The hepatic folate content was markedly reduced in the $PD{\times}MD$ and $PS{\times}MD$ and $PD{\times}MS$ as compared with the $PS{\times}MS$ group. The hepatic global DNA methylation was decreased in the $PD{\times}MS$ and $PS{\times}MD$ groups as much as in the $PD{\times}MD$ group, and all the three groups were significantly lower as compared to the $PS{\times}MS$ group. There were no significant differences in the hepatic FR${\alpha}$, IGF-2 and IGF-1R expressions among the groups. Positive correlations were found between the hepatic folate content and global DNA methylation and protein expressions of FR${\alpha}$, IGF-2 and IGF-1R, whereas an inverse correlation was found between hepatic folate content and plasma homocysteine level in the 3-week-old rat pup. The results of this study show that both paternal and maternal folate deficiency at mating can influence the folate content and global DNA methylation in the postnatal rat liver.

• 대한생식의학회:학술대회논문집
• /
• 대한불임학회 2006년도 The 5th Biannual Meeting of Pacific Rim Society for Fertility and Sterility
• /
• pp.161.2-161.2
• /
• 2006

• Journal of Dairy Science and Biotechnology
• /
• 제32권2호
• /
• pp.147-156
• /
• 2014

본 연구는 원유로부터 비만 억제 능력이 있는 젖산균을 분리 및 동정하고, 이 균주의 생리적 특성을 규명하여 상업적으로의 이용가능성을 검토하고자 실시하였다. 이를 위해 Modified MRS 분별배지를 사용하여 노란색 집락을 형성하는 균주를 대상으로 각각 Anti-lipase activity와 Anti-adipogenic activity가 우수한 균주를 선발한 결과, MD366 균주가 최종 선발되었다. MD366 균주는 lipase 억제활성 $65.03{\pm}0.94%$, 지방분화억제활성 $27.4{\pm}1.4%$로나타났으며, 동정결과Enterococcus faecalis로 판명되었고, Enterococcus faecalis MD366으로 명명하였다. E. faecalis MD366의 최적 생장 온도는 $37^{\circ}C$ 이었으며, 담즙산과 산성의 pH에서 모두 우수한 생존력을 나타내었다. 효소활성은 전반적으로 낮았으나 acid phosphatase에 대해 비교적 높은 효소 활성을 나타내었다. 항생제 내성 실험 결과 neomycin, kanamycin, vancomycin에 내성이 있는 반면, novobiocin에 감수성을 나타냈으며, Escherichia coli, Salmonella Typhimurium과 Staphyloccous aureus에 대해 각각 80.4%, 60.2%와 65.4%의 억제 효과를 지니고 있는 것으로 나타났다.

• The Plant Pathology Journal
• /
• 제18권2호
• /
• pp.98-101
• /
• 2002

Using phytoplasma universal primer pair Pl and P7, a fragment of about 1.8 kb nucleotide sequences of 16S rRNA gene and 16S-23S rRNA intergenic spacer region, and a portion of 23S rRNA gene of jujube witches'broom (JWB) and mulberry dwarf(MD) phytoplasmas were determined. The nucleotide sequences of JWB and MD were 1,850 bp and 1,831 bp long, respectively. The JWB phytoplasma sequence was aligned with the homologous sequence of MD phytoplasma. Twenty-eight base insertions and nine base deletions were found in the JWB phytoplasma sequence compared with that of MD phytoplasma. The similarity of the aligned sequences of JWB and MD was 84.8%. The near-complete 16S rRNA gene DNA sequences of JWB and MD were 1,529 bp and 1,530 bp in length, respectively, and revealed 89.0% homology. The 16S-23S rRNA intergenic spacer region DNA sequences were 263 bp and 243 bp in lengths respectively, while homology was only 70% and the conserved tRNA-lle gene of JWB and MD was located into the intergenic space region between 16S-23S rRNA gene. The nucleotide sequences were 77 bp long in both JWB and MD, and showed 97.4% sequence homology. Based on the phylogenetic analysis of the two phytoplasmas, the JWB phytoplasma belongs to the Elm yellow phytoplasma group (16S rV), whereas, the MD phytoplasma belongs to the Aster yellow group (16S rI).

• 한국멀티미디어학회논문지
• /
• 제6권2호
• /
• pp.194-207
• /
• 2003

본 논문에서는 객체 데이터베이스 시스템에서 중포 속성에 대한 색인구조로 다차원 색인구조를 이용하는 다차원 중포 속성 색인구조(Multidimensional Hefted Attribute Index: MD-NAI)의 최적 설계 기법을 제시한다. MD-NAI는 $B^{+}$-tree와 같은 일차원 색인구조를 이용한 중포 속성 색인구조에서 지원할 수 없는 클래스 계층과 중포 속성이 포함된 복합 형태의 질의들에 대한 처리를 잘 지원할 수 있다. 그러나, MD-NAI는 사용자 질의 형태에 따라 색인검색의 성능이 매우 나빠질 수 있다 본 논문에서는 질의 형태에 따른MD-NAI의 성능 개선을 위하여, 먼저 중포 술어에 대한 질의 정보로서 색인 페이지 영역의 최적 모양을 결정하고, 이 최적 모양을 갖는 색인페이지 영역의 모양이 되도록 하는 영역분할 전략을 적용하여 최적의 MD-NAI를 구성한다. 또한, 성능평가를 위하여 MD-NAI를 이용하여 다양한 중포 술어의 형태와 객체 분포에 대하여 실시한 실험 결과를 제시한다. 성능평가의 결과에 의하면, 주어진 질의 패턴에 따라 최적 의 MD-NAI를 구성할 수 있었으며, 삼차원 MD-NAI의 경우에 질의 영역의 구간비가 1:16:256일 때 기존의 순환분할 전략에 의한 MD-NAI에 비해 성능이 5.5배 이상까지 향상되었다.