• Composites Research
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• v.33 no.4
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• pp.177-184
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• 2020

Flame retardant(FR) clothes prohibit additional fire diffusion and make the personnel do their tasks without a hitch in a flammable environment. The existing FR clothes, however, are heavy and give high thermal fatigue. Therefore, it is strongly demanded to develop a light, convenient, and eco-friendly clothes. Recently, many works have been reported to make FR fabrics with phosphorus compounds, but their performance could not satisfy the specified criteria in appraisal standards of domestic and American FR clothes or combat uniforms. In this paper, two kinds of phosphorus compounds were applied to cotton fabric. Graphene oxide functionalized with a phosphorus-rich deep eutectic solvent and ammonium polyphosphate were coated on cotton fabric by eco-friendly padding procedure. The coated fabrics were analyzed with thermogravimetric analysis, vertical flame resistance test(ASTM D6413), cone calorimeter test(ISO 5660-1), and method of test for limited flame spread(ISO 15025). It was revealed that the as-made cotton with those two materials simultaneously had better flame resistance than the cottons with each one. Furthermore, an additional coating for hydrophobicity on the FR cotton was tried for better washing fastness.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.7-17
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• 2016

The present study experimentally considers dynamic performance of large floating wave-offshore hybrid power generation platform in extreme conditions. In order to evaluate the motion performance of the large floating hybrid power generation platform, 1/50 scaled model was manufactured. A mooring line was also manufactured, and free-decay and static pull-out tests were carried out to check the mooring model. A mooring line table was introduced to satisfy the water depth, and environmental conditions were checked. Motion responses in regular waves were measured and complicated environmental conditions including wave, wind, and current were applied to see the dynamic performance in extreme/survival conditions. Maximum motion and acceleration were judged following the design criteria, and maximum offset and mooring tension were also checked based on the rule. The characteristics of hybrid power generation platform are discussed based on these data.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.751-760
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• 2007

The purpose of this study is to evaluate the seismic performance of the frame which is assumed to be used with Welded Unreinforced Flange-Bolted web (WUF-B) connections and detailed in compliance with FEMA 350 recommended seismic design criteria. In FEMA 350, these types of connections are only valid for Ordinary Moment-Resisting Steel Frames (OMRSFs). For this purpose, based on test results, we proposed an analytical model for the Post-Northridge WUF-B connections with different panel zone strength ratios. Using the connection model, SAC Phase II three and nine-story frames were modeled and analyzed. From a nonlinear static pushover analysis, ductility, maximum strength, and the maximum interstory drift ratio were investigated for buildings with Post-Northridge details. Moreover, the maximum interstory drift ratio of each performance level (IO and CP) was also investigated through Incremental Dynamic Analysis (IDA). Analytical results were compared with those of buildings with either Pre-Northridge connection or ductile connections with no fracture. The analytical results showed that buildings with Post-Northridge WUF-B connections provide superior strength and interstory drift ratio capacity than buildings with Pre-Northridge WUF-B connections.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.705-713
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• 2018

An automotive ball joint connects the suspension system to the steering system and helps to enable rotational and linear motion between the two elements for steering. This study examines a ball joint used in medium and large-sized pickup trucks. Ball joints consist of a stud, socket, bearing, and plug. The main structural performance metrics of ball joints are the pull-out strength and push-out strength. These structural parameters must meet certain criteria to avoid serious accidents. Test and simulation methods are used to investigate the design requirements, but tests are time-consuming and costly. In this study, we modeled ball joints in SolidWorks and performed a finite element analysis in Abaqus to predict structural performance. The analysis was used to obtain the structural performance required for the static analysis of a 2D axisymmetric model. The uncertainties in the manufacturing of the ball joint were assumed to be the manufacturing tolerances, and the dimensional design variables were identified through case studies. The manufacturing tolerances at each level were defined, and the results were compared with experimental results.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.957-972
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• 2018

Tunnels constructed in cold regions can cause serious defects such as cracks and leaks due to external temperature changes in the portals and vents. In order to prevent the freezing damage of the tunnel, appropriate measures should be applied to the section where the freeze damage is concerned. However, the specific criteria and contents for judging whether or not the anti-freeze measures are applied are not presented. In this study, the laboratory freezing tests on the temperature changes of the concrete specimens under freezing conditions were carried out. And the freeze-thaw repetition cycle (F), which can judge the possibility of freezing damage, were presented based on the heat transfer quantity (W) by experimental results of case studies. Also, we propose a classification of cold regions considering the climatic characteristics of Korea for using it to efficient design and maintenance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.520-527
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• 2020

Hwangtoh is the rich resource that accounts for about 15.0% of the domestic soil, and can be used as the admixture of concrete with Pozzolan characteristics if activated by rapidly freezing after burning with high temperature. In this study, the mortar curbs containing active hwangtoh were produced, based on the mixture for the mortar curbs sold on the market. The substitution rate of active hwangtoh were considered 10.0% and 25.0%, and the test items were selected to compressive and flexural strength tests, freezing/thawing resistance tests, accelerated carbonation tests, and accelerated chloride diffusion tests. In the results of the mechanical performance, it was showed that the highest strength was evaluated in OPC mixture, and the increase in strength was small by the increase of age, which was believed to be due to the fact that most of the strength in each mixture was created in three days of steam curing. The results of the freezing/thawing tests for 28 aged days showed the reduction rate of compressive strength was 85.0% or higher for all specimen, meeting the criteria presented. The accelerated carbonation tests were carried out on the specimen at 28 days of age, and the results showed that the mortar with active hwangtoh had lower carbonation resistance performance than mortar with OPC. The passed charge of each mixture was assessed in accordance with ASTM C 1202 on 28 and 91 aged days. The OPC mixture had "Low" rate and the mortar with active hwangtoh had "Moderate" rate. So it was thought that the mortar with active hwangtoh had appropriate resistance performance for chloride attack.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.9
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• pp.796-805
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• 2016

As a part of the first stage in the helicopter flight simulator development, this study numerically evaluates handling qualities of the dynamics model. The flight dynamics model was generated using public information for AS365 N2, the target aircraft of the simulator. The flight simulator is under development as a pilot training and research tool for firefighting missions. The assessment of the model intends to validate general characteristics and suitability before the model is enhanced with flight test data. The evaluation is based on the ADS-33E-PRF(Aeroautical Design Standard Performance Specification Handling Qualities Requirement) criteria, with consideration of category of the aircraft, missions, and environment. The numerical operations follow required or recommended procedures of flight test for compliance demonstration. Evaluation results are evaluated according to the rating specified in maneuverability ADS-33E-PRF. Results have identified to provide a satisfactory platform for flight dynamic model in the general helicopter simulator generated based on the RotorLibFDM, and can be used as a base for basic training and research.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.61-68
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• 2020

In this study, the international standard ISO TS 16774 Part 3 Test Method for Water (wash out) Resistance and KS F 4935 ｢Sealant Injection type for water leakage maintenance of adhesive flexible rubber asphalt series｣, which are standardized as a quality control method of injection type repair materials used for water leakage cracks in underground concrete structures, are currently used in Korea. As a result, considering the performance criteria of "mass change rate -0.1%" stipulated in KS F 4935, the remaining 13 types repair materials, excluding RG-2 of synthetic rubber and UG-1 of urethane, need to be reviewed for stabilization of the loss resistance due to the flow of ground water. The results of this study are determined to be available as a basic indicator for the selection of repair materials used for cracks in concrete structures. In addition, it is expected that the results of this study can be utilized as reference data that can be reflected in the improvement of the quality of repair materials that will be researched and developed later.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.10
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• pp.1580-1586
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• 2007

The objective of this study was to compare the bioefficacy of L-lysine sulfate relative to L-lysine${\cdot}$HCl for 10 to 20 kg pigs. Two experiments were conducted to determine the bioefficacy of the two sources of lysine using daily gain, feed conversion, plasma urea nitrogen and nitrogen retention as the response criteria. In experiment 1, 168 crossbred barrows ($Landrace{\times}Large$ White), weaned at $28{\pm}3$ d ($9.07{\pm}0.78$kg body weight), were allotted to one of seven dietary treatments in a $2{\times}3$ (two lysine $sources{\times}three $ lysine levels) factorial arrangement of treatments with an added negative control treatment group. The basal diet was based on corn, peanut meal and soybean meal and provided 0.67% lysine. The basal diet was supplemented with 0.1, 0.2 or 0.3% lysine equivalents supplied from either L-lysine sulfate or L-lysine${\cdot}$HCl. Each treatment was fed to six pens of pigs with four pigs per pen. The trial lasted 21 days. The relative bioefficacy value of lysine in L-lysine sulfate using daily gain, feed conversion and plasma urea nitrogen as response criteria was 1.01, 1.05 and 1.04 of the lysine in L-lysine${\cdot}$HCl, respectively. In experiment 2, 42 crossbred ($Landrace{\times}Large$ White) pigs ($16.03{\pm}1.58$ kg body weight) were housed in stainless steel metabolism cages for 10 d and fed the seven diets used in the nitrogen-balance trial. The relative bioefficacy value of L-lysine sulfate was estimated to be 0.95 as effective as L-lysine${\cdot}$HCl for nitrogen retention on an equimolar basis. The t-test analysis revealed that bioefficacy of lysine in L-lysine sulfate was not significantly different from lysine in L-lysine${\cdot}$HCl, which was set at 1.00. In conclusion, L-lysine sulfate can be used instead of L-lysine${\cdot}$HCl to fortify lysine-deficient diets fed to 10 to 20 kg pigs.

• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.15-21
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• 2020

Currently, in KS C IEC 60079-10-1, the leakage hole radius of secondary leakage is expressed as a recommendation. Underestimation of leak hole size can lead to underestimation of the calculated values for leak rates, and conservative calculations of leak hole sizes, which are considered for safety reasons, can be overestimated, resulting in an overestimated risk range. This too should be avoided. Therefore, a careful and balanced approach is necessary when estimating the size of leaking holes.Based on this logic, this study examines the stability by grasping the concentration inside the gas box when leaking dangerous substances as a result of experiments based on SEMI S6, an international safety standard applied in the semiconductor industry and The scope of explosion hazardous area was determined by applying the formula of KS C IEC 60079-10-1 according to SEMI F15 leak rate criteria and SEMI S6 leak rate criteria. Based on this, we will examine whether the exhaust performance needs to be improved as an alternative to FAB facilities that are difficult to apply to explosion hazards such as semiconductor industry.