• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.325-336
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• 2023

A significant component of many civil constructions such as buildings, reservoirs, bridges, and sports halls, concrete has become increasingly popular due to its versatile properties. Concrete's internal characteristics change due to the use of different types of fibers, including changes in its microstructure, volume, and hole dimensions. Additionally, the type, dimensions, and distribution of fibers in concrete can affect the results of flexural strength tests by affecting its compressive and tensile strength. Due to a lack of information, fiber concrete is a new composite material in the production industry that requires laboratory studies to determine its behavior. This study investigated the bending behavior of multilayer slabs made of concrete reinforced by polyamide-propylene fibers against impact in weight lifting exercises. Results showed that adding fibers to concrete slab samples improved the mechanical properties while replacing them hurt the mechanical properties and failure of polymer fiber-reinforced concrete. On the other hand, adding and replacing fibers increases durability and has a positive effect.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.1
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• pp.56-63
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• 2021

The feedwater ring is an assembly in steam generator internal piping, which distributes feedwater into the secondary side of the steam generator. It consists of an assembly of carbon steel piping, pipe fittings and J-nozzles which are inserted into the top of the feedwater ring and welded to the diameter of the ring. The feedwater ring at the attachment region of the J-nozzle may be susceptible to flow accelerated corrosion (FAC) due to flow turbulence which increases local fluid velocities. If a J-nozzle becomes a loose part, it can cause damage to tubing near the tube sheet. In this paper, the structural stress analysis for a wall thinned feedwater ring and integrity evaluations under assumed loading conditions are carried out in compliance with ASME B&PV SecIII, NB-3200.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.129-135
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• 2006

A gene encoding for a putative microsomal epoxide hydrolase (mEH) of a zebrafish, Danio rerio, was cloned and characterized. The putative mEH protein of D. rerio exhibited sequence similarity with mammalian mEH and some other bacterial EHs. A structural model for the putative mEH was constructed using homology modeling based on the crystallographic templates, 1 qo7 and 1 ehy. The catalytic triad consisting of $Asp^{233}$, $Glu^{413}$, and $His^{440}$ was identified, and the characteristic features such as two tyrosine residues and oxyanion hole were found to be highly conserved. Based on bioinformatic analysis together with EH activity assay, the putative protein was annotated as mEH of D. rerio. Enantiopure styrene oxide with enantiopurity of 99%ee and yield of 33.5% was obtained from racemic styrene oxide by the enantioselective hydrolysis activity of recombinant mEH of D. rerio for 45 min.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.286-289
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• 2001

Single phase CuGaS$_2$ thin film with the highest diffraction peak of (112) at diffraction angle (2$\theta$) of 28.8$^{\circ}$ was made at substrate temperature of 7$0^{\circ}C$, annealing temperature of 35$0^{\circ}C$ and annealing time of 60 min. And second highest (204) peak was shown at diffraction angle (2$\theta$) of 49.1$^{\circ}$. Lattice constant of a and c of that CuGaS$_2$ thin film was 5.37 $\AA$ and 10.54 $\AA$ respectively. The greatest grain size of the thin film was about 1${\mu}{\textrm}{m}$. The (112) peak of single phase of CuGaS$_2$ thin film at annealing temperature of 35$0^{\circ}C$ with excess S supply was appeared with a little higher about 10 % than that of no exces S supply And the resistivity, mobility and hole density at room temperature of p-type CuGaS$_2$ thin film with best crystalline was 1.4 $\Omega$cm, 15 cm2/V . sec and 2.9$\times$10$^{17}$ cm$^{-3}$ respectively. It was known that carrier concentration had considerable effect than mobility on variety of resistivity of the fabricated CuGaS$_2$ thin film, and the polycrystalline CuGaS$_2$ thin films were made at these conditions were all p-type.

• KSBB Journal
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• v.19 no.1
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• pp.42-49
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• 2004

A gene coding for epoxide hydrolase (EH) of Aspergillus niger LK, a fungus possessing the enantioselective hydrolysis activity for racemic epoxides, was characterized by phylogenetic analysis. The deduced protein of A. niger LK epoxide hydrolase shares significant sequence similarity with several bacterial EHs and mammalian microsomal EHs (mEH) and belongs to the a/${\beta}$ hydrolase fold family. EH from A. niger LK had 90.6% identity with 3D crystal structure of lqo7 in Protein Data Bank. Sequence comparison with other source EHs suggested that Asp$\^$l92/, Asp$\^$374/ and His$\^$374/ constituted the catalytic triad. Based on the multiple sequence comparison of the functional and structural domain sequence, the phylogenetic tree between relevant epoxide hydrolases from various species were reconstructed by using Neighbor-Joining method. Genetic distances were so far as 1.841-2.682 but characteristic oxyanion hole and catalytic triad were highly conserved, which means they have diverged from a common ancestor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.772-775
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• 2013

We have grown a p-GaN film on sapphire by MOCVD and explored the post-annealing effort on the film after depositing a $2500{\AA}$ thick $SiO_2$ protective layer on it. By etching the $SiO_2$ protective film after the heat treatment, the hole concentration was measured, and compared with the data values before the heat treatment. In addition to the concentration, the hole mobility was also monitored while varying the atmospheric gas ratio of $N_2$ and $O_2$, the rapid thermal annealing temperatures ($750^{\circ}C$ and $650^{\circ}C$) and times (1 to 15 min.) In order to investigate the optical and structural properties of the film, room temperature and low temperature PL measurements were conducted.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.683-690
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• 2008

When steel fabricators erect structural members in field, temporary tightening of fastener should be useful. However, if bolt holes are not aligned by production error or natural condition, additional effort andpain should be provided to align bolt holes. It lead to longer period than times of construction (a primarily day of construction) and more cost than originally cost. This problem will be overcomed by oversize or slotted holes. Early, AISC and Eurocode have included provision for design process such oversize or slotted holes. But, domestic design method is not refered about oversize and slotted holes. Meanwhile, domestic design method and construction environment are variance with Europe and the United States of America. Therefore, a suitable design method for oversize and slotted holes in domestic real condition is needed. In this study, we evaluated behavior of the joints and decided the friction coefficient on oversize and slotted holes of friction joints with high strength bolts.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.47.1-47.1
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• 2011

We report on a direct measurement of two-dimensional chemical and electrical distribution on the surface of photovoltaic Cu(In,Ga)$Se_2$ thin-films using a nano-scale spectroscopic and electrical characterization, respectively. The Raman measurement reveals non-uniformed surface phonon vibration which comes from different compositional distribution and defects in the nature of polycrystalline thin-films. On the other hand, potential analysis by scanning Kelvin probe force microscopy shows a higher surface potential or a small work function on grain boundaries of the thin-films than on the grain surfaces. This demonstrates the grain boundary is positively charged and local built-in potential exist on grain boundary, which improve electron-hole separation on grain boundary. Local electrical transport measurements with scanning probe microscopy on the thin-films indicates that as external bias is increases, local current is started to flow from grain boundary and saturated over 0.3 V external bias. This accounts for carrier behavior in the vicinity of grain boundary with regard to defect states. We suggest that electron-hole separation at the grain boundary as well as chemical and electrical distribution of polycrystalline Cu(In,Ga)$Se_2$ thin-films.

• Korean Journal of Materials Research
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• v.27 no.6
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• pp.325-330
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• 2017

Photoelectron-hole separation efficiency plays an important role in the enhancement of the photocatalytic activity of photocatalysts towards the degradation of organic molecules. In this study, $TiO_2/TiOF_2$ heterostructured composite powders with suitable band structures, which structures are able to separate photoelectron-hole pairs, have been synthesized using a simple and versatile ultrasonic spray pyrolysis process. In addition, their phase volume fractions have been controlled by varying the pyrolysis temperature from $400^{\circ}C$ to $800^{\circ}C$. The structural and optical properties of the synthesized powders have been characterized by X-ray diffraction, scanning electronic microscopy and UV-vis spectroscopy. The powder with a phase volume ratio close to 1, compared with single $TiOF_2$ and other composite powders with different phase volume fractions, was found to have superior photocatalytic activity for the degradation of rhodamine B. This result shows that the $TiO_2/TiOF_2$ heterostructure promotes the separation of the photoinduced electrons and holes and that this powder can be applicable to environmental cleaning applications.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.193-199
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• 2023

In this study, an analysis was conducted to analyze the structural stability of the piezoelectric power generation module and to determine the optimal burying hole interval for concrete, the installation site of the power generation module. A piezoelectric element refers to a functional ceramic having a piezoelectric direct effect that converts mechanical energy into electrical energy and a piezoelectric reverse effect. In the analysis of the piezoelectric power generation module, the load condition was applied with about 16 tons and a total of 10 wheels in consideration of the container trailer. The purpose was to evaluate the stability of major components of the piezoelectric power generation module through finite element analysis. In order to determine the optimal burying location of the concrete ground for burying the piezoelectric power generation module, the stability of the ground structure according to the distance of the holes was determined. As a result of the analysis, the maximum stress of the piezoelectric power generation module was generated in the support spring, showing a stress of about 276.7 MPa. It was found that the spacing of holes for embedding the piezoelectric power generation module should be set to a minimum of 100 mm or more.