• Clean Technology
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• v.29 no.4
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• pp.305-312
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• 2023

Due to the strengthening of environmental requirements, aging denitrification facilities need to improve their performance. The present study aims to suggest the possibility of improving performance using computational analysis techniques. This involved modifying both the geometric design and the operating conditions, including the flow path shape of the equipment such as the inlet guide vane and the curved diffusing part, and the flow control of the ammonia injection nozzle. The conditions presented in this study were compared with existing operating conditions in terms of the flow uniformity, the NH₃/NO molar ratio of the mixed gas flowing into the catalyst layer, and the total pressure drop of the facility. The flow field applied in the computational analysis ranged from the outlet of the economizer in the combustion furnace to the inlet of the air preheater, the full domain of the denitrification facility. The performances were derived by solving the flow fields using ANSYS-Fluent and the injection amount of ammonia was adjusted for each nozzle using Design Xplorer. Compared to the denitrification performances of the equipment currently in operation, the conditions proposed in this study showed an improvement in the flow uniformity and NH₃/NO composition ratio by 45.1% and 8.7%, respectively, but the total pressure drop increased by 1.24%.

• Korean Journal of Materials Research
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• v.33 no.10
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• pp.393-399
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• 2023

In this study, changes in the microstructure and mechanical properties of cast and extruded Al-2Li-1Ce alloy materials were investigated as the Mg content was varied. The density decreased to 2.485, 2.46 and 2.435 g/cm³ when the Mg content in the Al-2Li-1Ce alloy was increased to 2, 4 and 6 wt%, respectively. Intermetallic compounds of Al₁₁Ce₃ were observed in all alloys, while the β-phase of Al₃Mg₂ was observed in alloys containing 6 wt% of Mg. In the extruded material, with increasing Mg content the average grain size decreased to 84.8, 71.6 and 36.2 ㎛, and the fraction of high-angle grain boundaries (greater than 15°) increased to 82.8 %, 88.6 %, and 91.8 %, respectively. This occurred because the increased Mg content promotes dynamic recrystallization during hot extrusion. Tensile test results showed that as the Mg content increased, both the yield strength and tensile strength increased. The yield strength reached 86.1, 107.3, and 186.4 MPa, and the tensile strength reached 215.2, 285, and 360.5 MPa, respectively. However, it is worth noting that the ductility decreased to 27.78 %, 25.65 %, and 20.72 % as the Mg content increased. This reduction in ductility is attributed to the strengthening effect resulting from the increased amount of dissolved Mg, and grain refinement due to dynamic recrystallization.

• The Journal of Korean Academic Society of Nursing Education
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• v.4 no.2
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• pp.236-248
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• 1998

This survey study was attempted for two purposes : 1) to grasp Korea National Open University(KNOU) students' changing aspects for their education need through comparison analyses with 1996 data ; 2) to establish foundation of the systematic network formation by investgating students' opinion about network framework. Among randomly assigned 4,500 students, 1,505 KNOU nursing students who allowed to participate in the study completed the questionnaires. The data were collected by mail. For the comparison 1996 data were also used. The data were analyzed using descriptive statistics, chi-square test, and t-test. Results of this study were as follows 1. The admission purposes of the KNOU nursing students were 'in order to get a bachelor's degree (70.7%)', 'to do studying and working simultaneously(43.0%)', or 'to be admitted for the graduate school (41%)' etc. Comparing the admission purposes by age, the investigator found 4 items which are 'small amount of tuition', 'graduate school admission', 'aspiration for the university', 'promotion or commencement of work' showed statistically significant differences. These 4 items were also found to show significant differences by marital status. 2. In relation to the learning media, the study showed most students(74%) got effective informations from the school newspaper(36.5%) or peer group(37.7%). The result showed that few students (0.7%) used the computer for communication. The research indicated that KNOU nursing students have tendency to rely on printed materials more than on broadcasting media. This is almost the same result as that of 1996. 3. The results revealed that 12.4% of the respondents had ever experienced unregistration or temporary withdrawal. The most common reason for the unregistration was 'due to family affairs or their job (71.3%)'. There were no change for this aspects with 1996. 4. As for the professors-students network formation. The result revealed that 38.5% students among respondents had heard of the network formation. 78.7% of respondents, however, positively responed that they would willingly participate in the networking if it is made. Especially the students showed much interest in 'the improvement for the understanding of study' and 'strengthening of the relations between professors and students'.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.61-66
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• 2019

Unlike NG supplied through pipes, LPG is mainly used for independent storage of cylinders or small storage tanks. As LPG is widely used in islands and underdeveloped areas, accidents due to neglect of safety management are high. Houses and businesses that have LPG accidents are likely to be damaged due to relatively high population density. Therefore, the necessity of strengthening the safety management of LPG is constantly raised. Accordingly, in 1996, Korea Gas Safety Corporation conducted an LPG leak test. In this study, based on the 96-year experiment, the gas leakage measurement of LPG vessels was conducted by adding several conditions such as outside temperature and pipe condition. Through this, the trend of leakage for various scenarios of LPG leakage was examined. In the case of a gas leak, when the article which may affect the pressure such as a regulator is not connected, the leakage amount is greatly changed by the outside air temperature, and when the regulator is fastened, the influence of the outlet pressure is large. It is expected that the experiment can be used as basic data for determining gas accidents and leakages that may occur later.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.1
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• pp.125-133
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• 2010

Researches and studies which have been conducted so far on external confinement of long span concrete columns have mainly concentrated on concentric loading. But, long span bridge concrete columns over the sea are mainly subjected to concentrated axial load, and at the same time lange amount of moment by eccentric load. This paper experimentally investigates the performance of externally confined high-strength concrete columns subjected to loading mechanism and evaluates the effectiveness of two confinement materials carbon fibre and high performance glass fibre. Twelve short columns with the same dimensions were cast and tested Six columns were reinforced with hoop bars, the remaining six columns were reinforced with spiral bars and wrapped with three layers of carbon failure and high performance glass FRP sheets. Test variables considered were the shape of internal reinforcement and strengthening materials according to loading location. The experimental results showed that eccentric load could obviously lower down the maximum failure load of FRP-confined concrete columns, compared with the columns under concentric load. And compared with the carbon FRP-confined reinforced concrete columns, high performance glass FRP-confined columns displayed a higher load capacity and ductility, when tested both concentrically and eccentrically.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.281-288
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• 2019

The purpose of this study is to identify the impact on patient safety management activities. In this study, 134 nurses from three local hospitals were investigated for patient safety culture recognition, patient safety capacity, and patient safety management activities, and the impact on patient safety management activities was thus attempted. The patient safety culture recognition level was 4.25/5, the patient safety capacity was 4.37/5, the patient safety management activity was 4.26/5, and the patient safety awareness and patient safety capability(r=.765, p<.001) and Patient Safety Capacity and Patient Safety Management Activity (r=.837, p<.001) and Patient Safety Capacity and Recognition of Patient Safety Culture(r=.728, p<.001) had a significant amount of correlation. Factors affecting patient safety management activities(β=.582, p<.001), Patient Safety Culture Recognition(β=.3632, p<.001), position(β=-.132, p=.009) Patient safety requires strengthening the capabilities of nurses and systematic training and evaluation of continuous patient safety activities.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.275-282
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• 2014

Particle-reinforced metal matrix composites exhibit a strengthening effect due to the particle size-dependent length scale that arises from the strain gradient, and thus from the geometrically necessary dislocations between the particles and matrix that result from their CTE(Coefficient of Thermal Expansion) and elastic-plastic mismatches. In this study, the influence of the size-dependent length scale on the particle-matrix interface failure and ductile failure in the matrix was examined using finite-element punch zone modeling whereby an augmented strength was assigned around the particle. The failure behavior was observed by a parametric study, while varying the interface failure properties such as the interface strength and debonding energy with different particle sizes and volume fractions. It is shown that the two failure modes (interface failure and ductile failure in the matrix) interact with each other and are closely related to the particle size-dependent length scale; in other words, the composite with the smaller particles, which is surrounded by a denser dislocation than that with the larger particles, retards the initiation and growth of the interface and matrix failures, and also leads to a smaller amount of decrease in the flow stress during failure.

• The Korean Journal of Financial Management
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• v.23 no.1
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• pp.227-242
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• 2006

This paper analyzes insurance crimes using a game theoretic model. In blackmailing cases involving automobile accidents, insurance criminals deliberately induce innocent drivers(victims) to commit a moving violation such as crossing over the center dividing yellow line, and collide with the victims. After the collision, the criminals and the victims effectively engage in a bargaining game over the amount of the settlement for the damage. Because the penalty for that kind of moving violation is very severe (even criminally prosecuted), the victims do not have much bargaining power. Exploiting the weak bargaining power of the victims, the criminals demand and receive huge compensation (including settlement) from the victims. In the model, it is shown that under the current law agents have perverse incentives leading to insurance crimes. The criminals have incentive to induce car collisions and extract huge settlement from the victims. Based on the analysis, it is suggested that lowering the severity of penalty for certain kind of violation may be needed to prevent insurance crimes, in addition to increasing the crime investigation activities and strengthening punishment for insurance criminals.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.205-213
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• 2010

This study was to analyze the past regime's real estate policy and the time-series data on real estate price index from 1986 to 2009 in 24 years. Also, the real estate index and macroeconomic variables, the impact on house price index variable conducted to regression analysis and to analyze whether and how much is affected. Analyzed as follows: First, Korea's real estate policy was the post-policy and the past regime's real estate policy was inconsistent with each other. Second, in the normal phase whenever real estate issues, the measures of the strengthening regulation and of the economic recovery were only to repeat periodically. Third, the timing and means of policy enforcement was an inappropriate and Real estate market was getting worse at the time whenever a real estate policies performed. Fourth, The apartments prices index of the housing types rose the highest and were the most popular for 24 years. Increase or decrease the amount of the price index for apartments, Roh Tae-woo(65.0%) - Kim Dae-jung (42.5%) - Roh Moo-hyun (32.8%) were in order. Fifth, the results of the regression analysis carried out: The impact on housing prices among independent variables were followed by Cap Construction- one per capita income - Housing consumer price index - Accompanying Composite Index - Trailing Composite Index - Home subscription Subscriber account - Leading Composite Index.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.18-24
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• 2012

In this study, hybrid method using polyvinyl acetate (PVAc) which has a strong adhesion and flexibility in which acrylic copolymer chemical-reaction reacts with cement, and is eco-friendly, is to improve the watertightness. The hybrid method is applied applied primarily waterproof stuff comprising silicate system and secondary mortar mixed with PVAc on the concrete surface. And then, in order to evaluate the performance, the properties of bond strength and amount of water absorption were measured. Based on the above experiments, mock-up specimens for field application were fabricated, and then the properties were evaluated as laboratory experiments. As the results, specimens cast from hybrid method using PVAc showed the best results on watertightness and bond strength. And also, with respect to experiment of mock-up specimens, the properties were in agreement with laboratory results. Especially, it could know that PVAc has strengthening effect from the results of the compressive strength. Due to outstanding results of carbonation depth and resistance to chloride ion penetration, it may be applied in weak areas such as underground and marine structures.