• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.143-151
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• 2007

This study presents the experimental results of frost durability including resistance to freezing-thawing and surface scaling of concrete. Mixing design was proportioned with the various water-binder ratio between 0.37 and 0.47 and three different binder compositions corresponding to Type I cement without any supplementary cementitious materials(OPC), Type II cement with 50% blast-furnace slag replacement(BFS50), and ternary cement with Type III cement, 15% fly ash, and 35% slag replacement (BFS35%+FA15%). Test results showed that the mixing design with BFS50% and BFS35%+FA15% exhibited higher durability factor than that made with OPC only. Finally, the use of blend cement containing slag can be used effectively in terms of frost durability of the concrete exposed to severe condition under coastal environment like as flying salt, sea water spray, etc.

• Structural Engineering and Mechanics
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• v.89 no.5
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• pp.525-538
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• 2024

An explosion from a specific source can generate high pressure, causing damage to structures and people in and around them. For the design of protective structures, although explosion overpressure is considered the main loading parameter, parts are only considered using standard design procedures, excluding special installations. Properties of the explosive, such as molecular structure, shape, dimensional properties, and the physical state of the charge, determine the results in a high-grade or low-grade explosion. In this context, it is very important to determine the explosion behaviors of the structures and to take precautions against these behaviors. Especially structures in areas with high explosion risk should be prepared for blast loads. In this study, the behavior of non-anchored blast resistant modular buildings was investigated. In the study, analyzes were carried out for cases where modular buildings were first positioned on a reinforced concrete surface and then directly on the ground. For these two cases, the behavior of the modular structure placed on the reinforced concrete floor against burst loads was evaluated with Stribeck curves. The behavior of the modular building placed directly on the ground is examined with the Pais and Kausel equations, which consider the structure-ground interaction. In the study, head and neck injuries were examined by placing test dummies to examine human injury behavior in modular buildings exposed to blast loads. Obtained results were compared with field tests. In both cases, results close to field tests were obtained. Thus, it was concluded that Stribeck curves and Pais Kausel equations can reflect the behavior of modular buildings subjected to blast loads. It was also seen at the end of the study that the human injury criteria were met. The results of the study are explained with their justifications.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.4
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• pp.669-676
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• 2024

This study aims to evaluate battery damage and heat transfer mechanisms through fire tests on lithium-ion batteries, and to explore ways to improve the efficiency and safety of battery management systems (BMS). Temperature changes in each sector are measured at points T1, T2, and T3 observing and recording the reactions of surrounding cells for 10 minutes after applying electricity to the ignition electrode. The results show that the batteries in sectors A and B fully ignite, causing severe physical damage, while the batteries in sector C do not ignite and sustain minimal damage. This confirms that the distance between sectors plays a crucial role in reducing ignition and heat propagation. The study suggests that considering the distance between sectors in the design of thermal management systems for lithium-ion batteries can significantly mitigate ignition and heat spread. Future experiments with various battery models and conditions will further propose the ways to enhance the efficiency and safety of BMS.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.4
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• pp.677-684
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• 2024

In this paper, the design method of a step-up DC-DC converter based on PWM control was studied for solar power system application. The operating principle of the switching mode step-up type DC-DC converter was analyzed and the basic design method was studied. For photovoltaic system application, an output voltage feedback control algorithm based on PWM control was developed to enable the converter's output voltage to follow the target voltage under variable input conditions. As a procedure to verify the effectiveness of the proposed algorithm, a prototype of a step-up DC-DC converter with a single feedback output voltage was designed and made by boosting the input voltage DC 10V to DC 30V. In experiments with prototypes, it was confirmed that the output voltage of the oscilloscope and LCD accurately followed the target output voltage. In the performance evaluation test, it was confirmed that the output voltage of the oscilloscope and LCD accurately followed the target output voltage by showing an error rate within 1 [%] of the reference voltage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.615-627
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• 2012

The market penetration of the smart phones has brought significant changes to the related industries. As the mobile phone market as well as the smart phone application market are growing rapidly, competition among small-size application developers has become severe. However, due to the severe competition and expensive market entry costs, the developers argue that it is necessary to develope the applications from the perspective of the users. However, studies on application development from the users' perspectives are still in the early stages and they have not provided various approaches. Therefore, based on the Open Coding method of Ground Theory, this study collected data on applications review from related communities and blogs of Korean web portal sites, and identified indices which users consider important when they use the applications. In addition, we conduct a comparative analysis between those indices by calculating their frequency of exposure. As a result, a total of 30 sub-categories of indicators such as amusement, controllability, versatility and ease of use appeared to be predominant to users and those lower categories were grouped into five categories; sensibility, design, technology, price, and social skills. The results of this study suggest to the application developers the guidelines of user oriented design and development. It can be used to develop the evaluation tool for application usability.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.4
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• pp.373-385
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• 2009

A new indexing methodology so called KTH-index was developed to quantitatively evaluate a potential level for tunnel collapse hazard, which has been successfully applied to tunnel construction sites to date. In this study, an attempt is made to apply this methodology for validating an outcome of tunnel design by checking the variation of KTH-index along longitudinal tunnel section. In this KTH-index simulation, it is the most important to determine the input factors reasonably. The design factor and construction condition are set up based on the designed outcome. Uncertain ground conditions are arranged based on borehole test and electro-resistivity survey data. Two scenarios for ground conditions, best and worst scenarios, are set up. From this simulation, it is shown that this methodology could be successfully applied for providing quantitative validity of a tunnel design and also potential hazard factors which should be carefully monitored in construction stage. The hazard factors would affect sensitively the hazard level of the tunnel site under consideration.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.63-72
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• 2013

HTB (hybrid truss bridge) steel truss webs instead of concrete webs in prestressed box girder bridges has been widely used in, because of its structural benefit such as relatively less self-weight and good aesthetics due to open web structure. Since the core technology of this bridge is the connection system between concrete slabs and steel truss members, several connection systems were proposed and experimentally evaluated. Also, the selected joint system was applied to the real bride design and construction. The researches were performed on the connection system, since it can affect the global behavior of this bridge such as flexural and fatigue behaviors as well as the local behavior around the connection region. The evaluation study showned that HTB applied to a curved bridge or a eccentric loading bridge, characteristic has a weak torsional capacity compared to an ordinary PSC box girder bridges due to the open structure of HTB. In this study, three box shaped hybrid truss specimens were made and the torsional test and evaluation for them were performed in order to find out the torsional behavior of HTB according to the connection system.

• The Journal of Korean Academy of Sensory Integration
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• v.6 no.1
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• pp.35-46
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• 2008

Objective : This study verifies the effects of sensory integrative (SI) therapy on vestibular- and proprioceptive sensory (BPS) processing ability of a child with Asperger Syndrome (AS). Method : A boy who is 11 years and 2 months old took the Functional Independence Measure for Children (Wee-FIM), Canadian Occupational Performance Measure (COPM), Short Sensory Profile, Bruininks-Oserestky Test of Motor Proficiency-2 (BOT-2), and Test of Playfulness (ToP) for the baseline. The child participated in 3 evaluation sessions and 8 therapy sessions based on the AB research design. Duration of each session is 50 min and the therapy session is divided into 40 minutes for treatment and 10 minutes for evaluation. Since the vestibular sense and proprioception build up one's ability of postural control, several tests were employed to evaluate the child' postural control as outcome measure; distance from front leg of chair to heel of the child with sitting (C-H distance), angle between trunk and thigh (hip joint angle) with sitting, and the 'prone-extension posture' which is a subtest of Clinical Observation of Motor and Postural Skill (COMPS) to examine postural control embodied with integration of reflex and BPS processing. Result : During the therapy, average data of the C-H distance is decreased from 27.33cm to 11.69cm, average data of the hip joint angle is also decreased from $43.3^{\circ}$ to $20^{\circ}$, and average time for the prone-extension posture is increased from 13.15seconds to 24.84seconds. Conclusion : This result indicates that the ability to postural control in sitting and to maintain the prone-extension posture can be improved by sensory integrative therapy, with enhanced BPS processing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.284-295
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• 2012

The purpose of this study was to develop and evaluate patient safety reporting promoting strategy for nurses to improve nursing care quality. The process included three phase - construction, implementation and evaluation phase. Before the construction phase has two kinds of subcategories as analysis and verification. Analysis phase was consisted of literature review and field study, and verification was conducted by two specialist. At the construction phase, patient safety reporting system, educational materials, planning for public relation, and reward preparation were developed. After implementation during 12 weeks, we evaluated pre-post scores of satisfaction, stress of conscience, job performances. The participants were 51 nurses working for a hospitals. The program was developed and then administered to the experimental group for 12 weeks. One group pretest-posttest design was used for this study. Data were analyzed using descriptive analysis, paired t-test with the SPSS WIN 18.0 program. After the intervention, job performance scores improved significantly from 3.62 to 3.75(t=2.653, p=.009). But job stress didn't changed significantly(t=.785, p=.434). These strategy can be applied to many clinical setting that will be helpful to promote patient safety reporting for nurses.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.269-275
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• 2020

In this study, flexural tests of precast concrete panels according to the thickness of cross-sectional and the with or not of reinforcement were carried out in order to develop and assess of a lightweight precast concrete panel using ultra high performance concrete. For the test, four panels were fabricated, and consisted of one normal concrete panel and three ultra high performance concrete panels. As a test result, it was found that the plain precast panel using ultra high performance concrete had a lower flexural performance than the reinforced normal concrete panel, regardless of the cross-sectional size. The flexural performance of the hollow-sectional precast panel applying ultra high performance concrete, is improved by 150% compared to that of the reinforced normal concrete panel. That is, through additional performance verification and optimization of the cross-sectional design of the panel, the ultra high performance concrete precast panel can be made lighter. Also, the practical use of lightweight precast panels with ultra high performance concrete can be available through evaluation on shear, joint connection and anchoring, etc.