• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.410-418
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• 2021

This study was conducted in 8.2m wide single-span greenhouse to investigate the effect of presence or absence of rafter steel pipe joint and foundation conditions on greenhouse structural performance. Structural performance was evaluated by static loading test using the structural performance evaluation system for single-span greenhouse. The measured displacement was compared with the predicted result by numerical analysis. The displacement of each measurement location showed a significant difference regardless of the conditions of the foundation and presence or absence of rafter steel pipe joint. Compared to the hinge conditions, the difference in structural performance of the greenhouse in the fixed conditions was seen to be relatively large. The difference in structural performance according to presence or absence of rafter steel pipe joints, the lateral stiffness of the joint was 8.1% greater.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.435-444
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• 2019

In this study, two types of nonionic saccharide biosurfactants, GP-6 and GP-7, were prepared from coconut oil and the structure of resulting products was investigated by FT-IR, $^1H-NMR$ and $^{13}C-NMR$ spectrophotometer. The interfacial properties of GP-6 and GP-7 were found to be excellent from interfacial property measurements such as critical micelle concentration, static and dynamic surface tensions, interfacial tension, emulsification power, wetting property and foam stability. Detergency test evaluated by using a Terg-o-tometer showed moderately good detergency compared to that of conventional surfactants used in detergent formulations. Biodegradability, acute oral toxicity, acute dermal irritation and acute eye irritation tests revealed that both surfactants possess excellent mildness and superior environmental compatibility indicating the potential applicability to detergent products formulations. In particular, GP-6 can be considered as a strong candidate in detergent formulations since it is more surface active, mild and readily biodegradable than GP-7.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.457-467
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• 2018

Currently, the regulation and rules for public surveying and the UCPs (Unified Control Points) adapts those of the triangulated traverse surveying. In addition, such regulations do not take account of the unique characteristics of GNSS (Global Navigation Satellite System) surveying, thus there are difficulties in field work and data processing afterwards. A detailed procesure of GNSS processing has not yet been described either, and the verification of accuracy does not follow the generic standards. In order to propose an appropriate procedure for field surveys, we processed a short session (30 minutes) based on the scenarios similar to actual situations. The reference network in Seoul was used to process the same data span for 3 days. The temporal variation during the day was evaluated as well. We analyzed the accuracy of the estimated coordinates depending on the parameterization of tropospheric delay, which was compared with the 24-hr static processing results. Estimating the tropospheric delay is advantageous for the accuracy and stability of the coordinates, resulting in about 5 mm and 10 mm of RMSE (Root Mean Squared Error) for horizontal and vertical components, respectively. Based on the test results, we propose a procedure to estimate the daily solution and then combine them to estimate the final solution by applying the minimum constraints (no-net-translation condition). It is necessary to develop a web-based processing system using a high-end softwares. Additionally, it is also required to standardize the ID of the public control points and the UCPs for the automatic GNSS processing.

• Journal of the Korea Institute of Building Construction
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• v.19 no.3
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• pp.201-207
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• 2019

In this study, the direct tensile properties of amorphous metallic fiber-reinforced cement based composites according to the strain was evaluated. A thin plate-shape amorphous metallic fiber with 15mm and 30mm in length was used. And fiber-reinforced cement based composites were prepared with contents of 1.0, 1.5, 2.0%. The direct tensile test was conducted under the conditions of $10^{-6}/s(static)$ and $10^1/s(dynamic)$ strain rate. As a results, amorphous metallic fiber with a length of 15mm was observed in pull-out behavior from the cement matrix because of the short fiber length and large portion of mixed fiber. On the other hand, amorphous metallic fiber with a length of 30mm were not pulled out from matrix because the bonding force between the fiber and matrix was large due to rough surface and large specific surface area. However, fracture occurred because thin plate shape fibers were vulnerable to shear force. Tensile strength, strain capacity and toughness were improved due to the increase in the fiber length. The dynamic increase factor of L15 was larger that of L30 because the bonding performance of the fiber-matrix interface is significantly affected by the strain rate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1103-1109
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• 2021

ECS is a control device so that the warship can perform the mission stably by controlling and monitoring the entire propulsion system. As the recent provisions of the warship, it's propelling system is complicated than past, as the demand performance and mission of the warships are diverse. In accordance with the complicated propulsion system configuration, the demand for automatic control function of the ECS is increasing for convenient and stable propulsion system control for convenient and stable. As a result, verification of ECS stability and reliability is required. In this paper, we develop an interlocking signal simulator for verifying ECS control logic and communication protocol for warship with CODLOG propulsion systems. The simulator developed was implemented to simulate a signal of gas turbine, propulsion motors, diesel generator and 11 kinds of auxiliary equipment. The reliability of ECS was verified through the ECS communication program and the I/O signal static test with the simulator.

• The Journal of Advanced Prosthodontics
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• v.13 no.6
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• pp.385-395
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• 2021

PURPOSE. To characterize the microstructure of three yttria partially stabilized zirconia ceramics and to compare their hardness, indentation fracture resistance (IFR), biaxial flexural strength (BFS), and fatigue flexural strength. MATERIALS AND METHODS. Disc-shaped specimens were obtained from 3Y-TZP (Vita YZ HT), 4Y-PSZ (Vita YZ ST) and 5Y-PSZ (Vita YZ XT), following the ISO 6872/2015 guidelines for BFS testing (final dimensions of 12 mm in diameter, 0.7 and 1.2 ± 0.1 mm in thicknesses). Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed, and mechanical properties were assessed by Vickers hardness, IFR, quasi-static BFS and fatigue tests. RESULTS. All ceramics showed similar chemical compositions, but mainly differed in the amount of yttria, which was higher as the amount of cubic phase in the diffractogram (5Y-PSZ > 4Y-PSZ > 3Y-TZP). The 4Y- and 5Y-PSZ specimens showed surface defects under SEM, while 3Y-TZP exhibited greater grain uniformity on the surface. 5Y-PSZ and 3Y-TZP presented the highest hardness values, while 3Y-TZP was higher than 4Y- and 5Y-PSZ with regard to the IFR. The 5Y-PSZ specimen (0.7 and 1.2 mm) showed the worst mechanical performance (fatigue BFS and cycles until failure), while 3Y-TZP and 4Y-PSZ presented statistically similar values, higher than 5Y-PSZ for both thicknesses (0.7 and 1.2 mm). Moreover, 3Y-TZP showed the highest (1.2 mm group) and the lowest (0.7 mm group) degradation percentage, and 5Y-PSZ had higher strength degradation than 4Y-PSZ group. CONCLUSION. Despite the microstructural differences, 4Y-PSZ and 3Y-TZP had similar fatigue behavior regardless of thickness. 5Y-PSZ had the lowest mechanical performance.

• Journal of the Korean Wood Science and Technology
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• v.30 no.1
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• pp.11-17
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• 2002

This study was performed to determine the characteristics of particleboard made from three-months-old bamboo, (Phyllostachys nigra var henonis Stapf) grown in Damyang district, Korea. Total 60 particleboards were manufactured with 1% of liquid wax emulsion using urea-formaldehyde resin content 9%,11% and 13%, respectively. The particle boards consisted of three layers, in which face layer had the same proportion of a weight 25% of the particleboard each. And the core layer had a weight 50% of the board. The core layer and face layer had the particle dimension passing 6 mesh (3.35 mm), 12 mesh (1.70 mm), respectively. The study was carried out to determine the effect of the growing time of 3 months and 3 years on particleboard properties. The physical and mechanical properties of boards were measured and compared to the Korean standard (KS) requirements of particle boards. The results were as follows; 1. The longer the growing time, the higher the density of bamboo. Density of the upper part of bamboo showed higher than that of lower part. 2. Density and moisture content of the two particle boards did not show significant differences. Three-months-old bamboo particleboard gave higher thickness swelling than three-years-old bamboo particleboard. Bamboo particleboard passed the thickness swelling test of KS. 3. The static bending and internal bond strength of three-months-old bamboo particleboard were higher than those of three-years-old bamboo. Increase of resin contents in bamboo particleboard increased bending and internal bond strength, proportionally. Strength properties of bamboo particle board were above KS. 4. Formaldehyde emission of all the bamboo particleboards satisfied E₂ level (5.0 mg/L) of KS F 3104.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.1-10
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• 2023

Recently, numerous structures have been constructed near the Nakdong river estuary, with pile foundations embedded in sand and gravel layers. In this study, the side resistance for six drilled shafts embedded in that region was evaluated based on the results of bi-directional and static axial compressive pile load tests. Subsequently, these results were compared with the side resistance calculated using domestic and foreign design codes such as FHWA (1999), KDS (2021), and AIJ (2004). Based on the test results, the evaluated side resistances ranged from 120 to 444kPa. However, the estimated values obtained from the design codes ranged from 69.3 to 170kPa, which were less than 50% of the evaluated values. It was observed that the empirical methods and correlations used in design codes provide a conservative estimation of the side resistance for drilled shafts embedded in sand and gravel layers. It implies that a suitable domestic approach should be developed to accurately estimate the side resistance of pile in sandy gravel and gravel layers near the Nakdong river estuary.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.99-106
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• 2006

In the present study, in order to clarify the effects of latent hydraulic property of granulated blast furnace slag (GBF slag) on the liquefaction, GBF slag was cured in the high temperature alkali water (adding the calcium hydroxide, pH=12, water temperature is about $30^{\circ}C$), and then the cyclic and the static tri-axial compression tests were carried out. Then the results were compared with those for Japanese standard sand of Toyoura sand and natural sand of Genkai sand. From the test results, it is clarified that the liquefaction strength of the GBF slag increases with the increase of the curing period by the hardening due to the latent hydraulic property. It is also shown that GBF slag with Dr=50% and 80% which was cured for 189 days in the fresh-water shows cohesion due to developing of latent hydraulic property. In addition, as for the liquefaction strength of GBFS during the hardening process, a linear relation between the cyclic stress ratio $R_{20}$ at the number of stress cycles Nc=20 and cohesion $C_{d}$ was observed. It is also clarified that the liquefaction strength for cured GBF slag in the high temperature alkali water is predicted by the cohesive strength or the unconfined compressive strength.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.264-271
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• 2023

In this study, ASCO^Ⓡ SLES-430 surfactant was synthesized by adducting 3 moles of ethylene oxide and 1 mole of propylene oxide to lauryl alcohol followed by a sulfation process, and the structure of the synthesized ASCO^Ⓡ SLES-430 was elucidated by performing FT-IR, ¹H-NMR and ¹³C-NMR analyses. Interfacial properties such as critical micelle concentration, static surface tension, emulsification index, and contact angle were measured, and environmental compatibility indices such as oral toxicity and skin irritation were also estimated for ASCO^Ⓡ SLES-430. Both results were compared with ASCO^Ⓡ SLES-226 and ASCO^Ⓡ SLES-328 SLES surfactants possessing 2 moles and 3 moles of ethylene oxide, respectively. In particular, both foaming ability and foam stability were evaluated for ASCO^Ⓡ SLES-430 and compared with ASCO^Ⓡ SLES-226 and ASCO^Ⓡ SLES-328, which have been widely used in detergent products, in order to test the potential applicability of ASCO^Ⓡ SLES-430 in detergent product formulation for a small capacity built-in washing machine.