• Journal of Microbiology
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• v.44 no.1
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• pp.64-71
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• 2006

To investigate the effects of the nucleotide sequences in Shine-Dalgarno (SD) and the spacer region (SD-ATG) on bovine growth hormone (bGH) gene expression, the expression vectors under the control of the T7 promoter (pT7-7 vector) were constructed using bGH derivatives (bGH1 & bGH14) which have different 5'-coding regions and were induced in E. coli BL21 (DE3). Oligonucleotides containing random SD sequences and a spacer region were chemically synthesized and the distance between the SD region and the initiation codon were fixed to nine bases in length. The oligonucleotides were annealed and fused to the bGH1 and bGH14 cDNA, respectively. When the bGH gene was induced with IPTG in E. coli BL21(DE3), some clones containing only bGH14 cDNA produced considerable levels of bGH in the range of $6.9\%\;to\;8.5\%$ of total cell proteins by SDS-PAGE and Western blot. Otherwise, the bGH was not detected in any clones with bGH1 cDNA. Accordingly, the nucleotide sequences of SD and the spacer region affect on bGH expression indicates that the sequences sufficiently destabilize the mRNA secondary structure of the bGH14 gene. When the free energy was calculated from the transcription initiation site to the +51 nucleotide of bGH cDNA using a program of nucleic acid folding and hybridization prediction, the constructs with values below -26.3 kcal/mole (toward minus direction) were not expressed. The constructs with the original sequence of bGH cDNA also did not show any expression, regardless of the free energy values. Thus, the disruption of the mRNA secondary structure may be a major factor regulating bGH expression in the translation initiation process. Accordingly, the first stem-loop among two secondary structures present in the 5'-end region of the bGH gene should be disrupted for the effective expression of bGH.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.454-454
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• 2014

Silicon microwire array is one of the promising platforms as a means for developing highly efficient solar cells thanks to the enhanced light trapping efficiency. Among the various fabrication methods of microstructures, deep reactive ion etching (DRIE) process has been extensively used in fabrication of high aspect ratio microwire arrays. In this presentation, we show precisely controlled Si microwire arrays by tuning the DRIE process conditions. A periodic microdisk arrays were patterned on 4-inch Si wafer (p-type, $1{\sim}10{\Omega}cm$) using photolithography. After developing the pattern, 150-nm-thick Al was deposited and lifted-off to leave Al microdisk arrays on the starting Si wafer. Periodic Al microdisk arrays (diameter of $2{\mu}m$ and periodic distance of $2{\mu}m$) were used as an etch mask. A DRIE process (Tegal 200) is used for anisotropic deep silicon etching at room temperature. During the process, $SF_6$ and $C_4F_8$ gases were used for the etching and surface passivation, respectively. The length and shape of microwire arrays were controlled by etching time and $SF_6/C_4F_8$ ratio. By adjusting $SF_6/C_4F_8$ gas ratio, the shape of Si microwire can be controlled, resulting in the formation of tapered or vertical microwires. After DRIE process, the residual polymer and etching damage on the surface of the microwires were removed using piranha solution ($H_2SO_4:H_2O_2=4:1$) followed by thermal oxidation ($900^{\circ}C$, 40 min). The oxide layer formed through the thermal oxidation was etched by diluted hydrofluoric acid (1 wt% HF). The surface morphology of a Si microwire arrays was characterized by field-emission scanning electron microscopy (FE-SEM, Hitachi S-4800). Optical reflection measurements were performed over 300~1100 nm wavelengths using a UV-Vis/NIR spectrophotometer (Cary 5000, Agilent) in which a 60 mm integrating sphere (Labsphere) is equipped to account for total light (diffuse and specular) reflected from the samples. The total reflection by the microwire arrays sample was reduced from 20 % to 10 % of the incident light over the visible region when the length of the microwire was increased from $10{\mu}m$ to $30{\mu}m$.

• Economic and Environmental Geology
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• v.44 no.4
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• pp.289-302
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• 2011

Since the frequency of the earthquake occurrence in Korean peninsular is continuously increasing, the possibility that massive landslides are triggered by earthquake is also growing in Korea. Previously, the landslide is known to be induced by large magnitude earthquake, whose magnitude is larger than 6.0. However, the landslide can be induced by only small magnitude earthquake, especially in the fully saturated soil. Therefore, the susceptibility of landslide caused by small magnitude earthquake in fully saturated soil is analyzed in this study. For that, the topographical and geological characteristics of the site were obtained and managed by GIS software. In the procedure of the study, slope angle, cohesion, friction angle, unit weight of soil were obtained and constructed as a spatial database layer. Combining these data sets in a dynamic model based on Newmark's displacement analysis, the landslide displacements were estimated in each grid cell. In order to check out the possibility of the earthquake induced landslides, the level of the groundwater table is varied from dry to 80% saturated soil. In addition, in order to analyze the effect of the magnitude of earthquake and distance to epicenter, four different earthquakes epicenters were considered in the study area.

• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.105-114
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• 1973

The crystal structure of morpholinothiosemicarbazide has been determined by single crystal X-ray analysis. The lattice constants are a = 4.19(2), b = 6.56(2) and c = 26.67(4)${\AA}$. The unit cell contains 4 molecules and the space group is$P2_12_12_1$. The atomic parameters have been refined by least-squares method to a final R value of 0.07, based on the 651 observed reflexions. The amino nitrogen atom forms hydrogen bonds to the sulfur atoms of the other molecules related by the two-fold screw axis parallel to the a-axis, the distances of the hydrogen bonds being 3.48 and 3.49${\AA}$. On the other hand, the imino nitrogen atom forms a hydrogen bond to the amino nitrogen atom of the other molecule related by the two-fold screw axis parallel to the a-axis, the distance of the hydrogen bond being 3.04${\AA}$. These three hydrogen bonds arrange the molecules around the two-fold screw axis. Apart from the hydrogen bonding system the structure is held together by van der Waals forces.

• Korean Journal of Food Science and Technology
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• v.34 no.4
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• pp.631-636
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• 2002

Lethality of high intensity light pulse on the pre-determined microbial populations has been investigated. Prior to the treatment, Lactobacillus plantarum, Lactobacillus brevis, Leuconostoc mesenteroides and Pediococcus pentosaceus were cultivated separately onto the surface of Lactobacilli MRS agar. Pre-determined microbial populations were applied to the test media and these sample were exposed to high intense light source with an exposure time ranging from 1 to $2500\;{\mu}s$. Results showed that at least 200 light pulses of $1\;{\mu}s$ duration were required to reduce L. Plantarum cells by 90% at 25 kV, the greater the number of light pulses, the larger the reduction in viable cell numbers. Viable cells of L. plantarum and the others were reduced by more than 5 and 6 log cycles at the upper exposure level of $750\;{\mu}s$, respectively. These study shows that pulsed light emissions can significantly reduce populations of lactic acid bacteria on exposed surface with exposure times. Killing efficiency for L. plantarum significantly increased with decreasing the distance between the lamp and the surface of samples.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.629-636
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• 2022

Domestic eco-friendly vehicles currently account for 5.8% of the total registered vehicles in Korea. Hydrogen vehicles, one of the representative eco-friendly vehicles, have grown rapidly as they have been expanded to the market based on the government's policy to boost the hydrogen industry. Therefore, it is time to expand the safety review of hydrogen vehicles in various directions according to the increase in supply. In this study, the effect of internal heat damage was analyzed when a jet flame was generated by a hydrogen car in a road tunnel. It was simulated using Fluent, and the amount of jet flame injection was selected in consideration of the hydrogen tank capacity of commercial hydrogen vehicles for road tunnels. In addition, the study was conducted with the direction of the jet flame and the nozzle distance from the tunnel wall as variables. From the results, when the jet flame erupted in the road tunnel, high radiant heat emission of more than 20 kW/m² was generated in most areas within ±5 m in the longitudinal direction based on the vehicle (spray nozzle) and 5 to 7 m in the lateral direction based on the adjacent tunnel wall.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.7
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• pp.418-425
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• 2017

ZnO nanoparticles (ZnO NPs) are mainly used in semiconductors, solar cells, biosensors, and cosmetics (sunscreen). In this study, we investigated the behavior of ZnO NPs in aquatic and soil environments and their effects on plants (Artemisia annua L.) in hydroponic cultivation. It was confirmed that the ZnO NPs size increased and their dissolution decreased with increasing in pH. Leaching distance of ZnO NPs was less than 2.5 cm, indicating that ZnO NPs had a little potential to leach into deeper soil layers. When ZnO NPs were exposed to plant, the total weights of plants decreased. The effects on the length of root and shoot were not observed. In addition large amount of ZnO NPs were adsorbed on the surface of plant root and didn't translocate into shoot. These results suggest that ZnO NPs block the pores of the root cell wall and decrease the bioavailability of plant nutrients. Therefore it can be speculated that the particles increase in size and settle down in the water environment and may adversely affect the plant growth by firmly adhering to the root surface when the ZnO NPs are exposed to the environment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.1
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• pp.41-46
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• 2011

Reliable information on the surface solar radiation is indispensable for rebuilding food production system in the famine plagued North Korea. However, transfer of the related modeling technology of South Korea is not possible simply because raw data such as solar radiation or sunshine duration are not available. The objective of this study is restoring solar radiation data at 27 synoptic stations in North Korea by using satellite remote sensing data. We derived relationships between MODIS radiation estimates and the observed solar radiation at 18 locations in South Korea. The relationships were used to adjust the MODIS based radiation data and to restore solar radiation data at those pixels corresponding to the 27 North Korean synoptic stations. Inverse distance weighted averaging of the restored solar radiation data resulted in gridded surfaces of monthly solar radiation for 4 decadal periods (1983-1990, 1991-2000 and 2001-2010), respectively. For a direct application of these products, we produced solar irradiance estimates for each sub-grid cell with a 30 m spacing based on a sun-slope geometry. These products are expected to assist planning of the North Korean agriculture and, if combined with the already prepared South Korean data, can be used for climate change impact assessment across the whole Peninsula.

• Korean Journal of Ecology and Environment
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• v.34 no.1 s.93
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• pp.45-53
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• 2001

Transport of cyanobacterial toxins (microcystin-LR, -RR, -YR) were assessed from a eutrophic lake, Lake Suwa, through the outflowing river, the Tenryu River, and its irrigation channel branch. Temporal variation of phytoplankton species composition in the river coincided with those of the lake; Microcystis ichthyoblabe dominated from June to July, and M. viridis dominated from August to September. When cyanobacterial bloom occurred, microcystins were continuously detected at the concentration of $0.3{\sim}3.2\;{\mu}g/l$ even at 32 km downstream. The change of the content of three microcystin variants were related both with the total cell density of Microcystis and with the change of Microcystis species composition. When Microcystis ichthyoblabe dominated during July, only microcystin-RR (MC-RR) and -LR (MC-LR) were detected, while when Microcystis viridis dominated between August and October, microcystin-RR,-YR (MC -YR) and -LR were detected. Along 29 km flowing distance (flow time 11 hours) between site 2 and site 5 in the Tenryu River, cyanobacterial density and microcystin concentration were reduced by 73% and 72%, respectively, which is mostly contributed by the dilution effect of tributary waters (61% and 57%, respectively) . In the artificial irrigation channel microcystins and cyanobacterial cells were decreased less than in the natural river. The results indicate that cyanobacterial toxins can be transported far downstream without much removal and give hazards to water usage in downstream of eutrophic lakes with cyanobacterial blooms.

• The Korean Journal of Cytopathology
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• v.11 no.1
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• pp.1-10
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• 2000

The purpose of this study is to describe the cellular characteristics of endometrial hyperplasia without/with atypia in cervical smears. These cellular features were compared with those of normal endometrium and endometrial carcinoma. We reviewed 265 cervical smears : 64 normal proliferative endometrium, 118 endometrial hyperplasia without atypia, 21 endometrial hyperplasia with atypia, and 62 endometrial adenocarcinoma. Of these smears, 72(27.2%) smears which had diagnostic endometrial epithelial cells were selected for this study. The cytologic abnormalities about cellularity, background, changes in cellular architecture, alterations in nuclear size, anisokaryosis, chromatin pattern, nucleoli, cytoplasmic vacuoles, and mitosis were observed. Nuclear enlargement(1.6 to 2 times of the nucleus in the intermediate squamous cell) and anisokaryosis(${\geq}$2 fold in size variation) were highly suggestive of endometrial hyperplasia without/with atypia. The nuclei from endometrial hyperplasia with atypia were more coarsely granular in chromatin patterns than hyperplasia without atypia(33.3% vs 3.4%). Micronucleoli were observed in all endometrial conditions, but the presence of macronucleoli were more suggestive of hyperplasia with atypia(22.2%) and adenocarcinoma(55%). The changes in cellular architecture(loss of polarity, uneven internuclear distance, overlapping and loose arrangement) were seen in hyperplasia with atypia and adenocarcinoma. Characteristically, bloody background was seen in endometrial hyperpiasia, and cellular detritus or granular proteinaceous material was only observed in endometrial adenocarcinoma. Mitoses were also observed in adenocarcinoma. In conclusion, although there is no single parameter useful for the cytologic differential diagnosis of endometrial lesions, combined cytologic evaluation can be used to diagnose hyperplasia cytologically.