• Composites Research
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• v.33 no.6
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• pp.371-376
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• 2020

The adhesive strength can be improved through surface treatment. The most common method is to improve physical bonding by varying the surface conditions. This study presents the effect of laser surface treatment on the adhesive strength of CFRP. The surface roughness was patterned using a 1064 nm laser. The effects of the number of laser shots and the direction and length of the pattern on the adhesion of the CFRP/CFRP single joint were investigated through tensile tests. Tests according to ASTM D5868 were performed, and the bonding mechanism was determined by analyzing the damaged surface after a fracture. The optimized number of the laser shots and the optimized depth of the roughness should be required to increase the bonding strength on the CFRP surface. When considering the shear stress in the tensile direction, the roughness pattern in the direction of 45° that increases the length of the fracture path in the adhesive layer resulted in an increase of the adhesive strength. The surface treatment of the bonding surface using a laser is a suitable method to acquire a mechanical bonding mechanism and improve the bonding strength of the CFRP bonding joint. The study on the optimized laser process parameters is required for utilizing the benefits of laser surface processing.

• Journal of Internet of Things and Convergence
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• v.8 no.6
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• pp.115-122
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• 2022

Recently, the importance of CPR training for the layperson has been emphasized to improve the survival rate of out-of-hospital cardiac arrest patients. An accurate and realistic training strategy is required for the CPR training effect for laypersons. In this study, we develop an extended reality (XR) based CPR training system and evaluate its usability. The XR based CPR training system consisted of three applications. First, a 3D heart anatomy image registered to the manikin is transmitted to the smart glasses to guide the chest compression point. The second application provides visual and auditory information about the CPR process through smart glasses. At the same time, the smartwatch sends a vibration notification to guide the compression rate. The 'Add-on-kit' is a device that detects the depth and speed of chest compression via sensors installed on the manikin and sends immediate feedback to the smartphone. One hundred laypersons who participated in this study agreed that the XR based CPR training system has realism and effectiveness. XR based registration technology will contribute to improving the efficiency of CPR training by enhancing realism, immersion, and self-directed learning.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.575-584
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• 2021

Objective : Cervical expansive laminoplasty is an effective surgical method to address multilevel cervical spinal stenosis. During surgery, the spinous processes of C2 and C7 are usually preserved to keep the insertion points of the cervical musculature and nuchal ligament intact. In this regard, dome-like laminectomy (undercutting of C7 lamina) instead of laminoplasty is performed on C7 in selected cases. However, resection of the lamina can weaken the C7 lamina, and stress fractures may occur, but this complication has not been characterized in the literature. The objective of the present study was to investigate the incidence and risk factors for C7 laminar fracture after C7 dome-like laminectomy and its impact on clinical and radiological outcomes. Methods : Patients who underwent cervical open-door laminoplasty combined with C7 dome-like laminectomy (n=123) were classified according to the presence of C7 laminar fracture. Clinical parameters (neck/arm pain score and neck disability index) and radiologic parameters (C2-7 angle, C2-7 sagittal vertical axis, and C7-T1 angle) were compared between the groups preoperatively and at postoperatively at 3, 6, 12, and 24 months. Risk factors for complications were evaluated, and a formula estimating C7 fracture risk was suggested. Results : C7 lamina fracture occurred in 32/123 (26%) patients and occurred at the bilateral isthmus in 29 patients and at the spinolaminar junction in three patients. All fractures appeared on X-ray within 3 months postoperatively, but patients did not present any neurological deterioration. The fracture spontaneously healed in 27/32 (84%) patients at 1 year and in 29/32 (91%) at 2 years. During follow-up, clinical outcomes were not significantly different between the groups. However, patients with C7 fractures showed a more lordotic C2-7 angle and kyphotic C7-T1 angle than patients without C7 fractures. C7 fracture was significantly associated with the extent of bone removal. By incorporating significant factors, the probability of C7 laminar fracture could be assessed with the formula 'Risk score = 1.08 × depth (%) + 1.03 × length (%, of the posterior height of C7 vertebral body)', and a cut-off value of 167.9% demonstrated a sensitivity of 90.3% and a specificity of 65.1% (area under the curve, 0.81). Conclusion : C7 laminar fracture can occur after C7 dome-like laminectomy when a substantial amount of lamina is resected. Although C7 fractures may not cause deleterious clinical outcomes, they can lead to an unharmonized cervical curvature. The chance of C7 fracture should be discussed in the shared decision-making process.

• Journal of Communication Design
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• v.65
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• pp.530-538
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• 2018

Recently, museums are attracting the attention of visitors and society. However, research on museum interpretation conducted at domestic and foreign is relatively limited. The plan design of the museum commentary system was mainly based on the perspective of the experts, and most of them do not reflect the desire of the visitors. This study focused on visitors' experience of using museum Interpretation system. Through analyzing the effect of the Interpretation system of the museum that the visitor feels, we examined whether the Interpretation system of the museum meets the cultural needs of the visitors and identified the problems and deficiencies in the system. After that, the problems were rearranged and suggested the main elements of the commentary system of the museum finally, so as to help improve the museum commentary system and the educational function.In the first part of the study, the four major explanatory methods existing in the museum were confirmed. After that, we conducted in - depth interviews on four types of commentary methods and collected existing problems and deficiencies. The results of the type analysis were grouped into 14 types and the questionnaire was used to conduct a general survey on 14 problems. In this study, the user 's discomfort and problems were identified in the museum Interpretation system, and based on this, five key elements necessary for the museum Interpretation system were derived. Among them, inhalation is the weakest element in the museum commentary system, and future research will be conducted on how to apply each factor. I hope that you will be a reference material when you carry out research on the optimization of the Interpretation system of the museum and the improvement of the Interpretation experience.

• Animal Bioscience
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• v.34 no.3_spc
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• pp.434-442
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• 2021

Objective: This study aims to evaluate the influence of dietary flavonoids on the growth performance, blood and intestinal profiles, and carcass characteristics of broilers by employing a meta-analysis method. Methods: A database was built from published studies which have reported on the addition of various levels of flavonoids from herbs into broiler diets and then monitored growth performance, blood constituents, carcass proportion and small intestinal morphology. A total of 42 articles were integrated into the database. Several forms of flavonoids in herbs were applied in the form of unextracted and crude extracts. The database compiled was statistically analyzed using mixed model methodology. Different studies were considered as random effects, and the doses of flavonoids were treated as fixed effects. The model statistics used were the p-values and the Akaike information criterion. The significance of an effect was stated when its p-value was <0.05. Results: Dietary flavonoids increased (quadratic pattern; p<0.05) the average daily gain of broilers in the finisher phase. There was a reduction (p<0.01) in the feed conversion ratio of the broilers both in the starter (linear pattern) and finisher phases (quadratic pattern). The mortality rate tended to decrease linearly (p<0.1) with the addition of flavonoids, while the carcass parameter was generally not influenced. A reduction (p<0.001) in cholesterol and malondialdehyde concentrations (both linearly) was observed, while super oxide dismutase activity increased linearly (p<0.001). Increasing the dose of flavonoids increased (p<0.01) the villus height (VH) and villus height and crypt depth (VH:CD) ratio (p<0.05) in the duodenum. Similarly, the VH:CD ratio was elevated (p<0.001) in the jejunum following flavonoid supplementation. Conclusion: Increasing levels of flavonoids in broilers diet leads to an improvement in growth performance, blood constituents, carcass composition and small intestinal morphology.

• Journal of Industrial Convergence
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• v.19 no.1
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• pp.53-63
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• 2021

As tourists travel to other regions, they encounter numerous facts that conflict with their views. At that time, we change our view of coping with life. In this respect, tourism is a new way of learning. As a new learning method, tourism experience research is a new approach. In this study, the relationship between experience and learning experienced in tourist destinations was analyzed by applying the activity theory. The analysis units applied in the activity theory were set as subjects, goals, communities, roles, methods and rules, outcomes, and relevance to local communities. Based on this, in-depth interviews were conducted with commentators and guides who had a great influence on the tourism experience to analyze the learning process of tourists. As a result of the analysis, the experiences of tourists during the tour were interactive in various forms within the unit as well as the unit of the activity system of the commentator and guide. This interaction induces changes in the tourism experience activity system, enabling tourists to learn. The content is that the value of learning increases as the role of guide and commentator increases, that the social and cultural dimension of tourism experience is included in the learning effect, and the contradictions that arise from interactions within or between activity systems. The fact that they find the solution process themselves, and that tourism activity is not an isolated unit, but exists at the intersection of hierarchies and networks, is affected by the activities and environments of others.

• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.53-65
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• 2021

While the hydrogen refueling station is rapidly expanded and installed, the safety inspection of the hydrogen pressure vessel in the station should be very important. Of these, according to ASME, hydrogen embrittlement tests must be performed for hydrogen vessel that store hydrogen above a certain pressure. The main test method for hydrogen embrittlement inspection is to carry out fracture tests and fatigue fracture tests in a high pressure hydrogen atmosphere, which allows the durability limit of the pressure vessel to be measured and the endurable limit to be determined in the hydrogen atmosphere. In detail, the critical crack depth can be calculated by the stress intensity factor(K), and the service life can be determined by da/dN (fatigue growth rate). API579-1/ ASME FFS-1 part 9 exemplifies the calculation method according to the mode of crack-like flaws, but for various shapes such as plates and cylinders, there are about 55 modes according to the shape and location of the crack. Due to the fairly complex formula, it is not easily accessible. In this study, we will show you how to calculate fracture mechanics numerically via Excel and VBA. In addition, this was applied to analyze the effects of the thickness and inner diameter of the pressure vessel on the service life.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.313-319
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• 2022

AlGaN/GaN based HfO₂ MOSHEMT (metal oxide semiconductor high electron transistor) with different gate recess depth was simulate to demonstrate a successful normally-off operation of the transistor. Three types of the HEMT structures including a conventional HEMT, a gate-recessed HEMT with 3 nm thick AlGaN layer, and MIS-HEMT without AlGaN layer in the gate region. The conventional HEMT showed a normally-on characteristics with a drain current of 0.35 A at V_G = 0 V and V_DS = 15 V. The recessed HEMT with 3 nm AlGaN layer exhibited a decreased drain current of 0.15 A under the same bias condition due to the decrease of electron concentration in 2DEG (2-dimensional electron gas) channel. For the last HEMT structure, distinctive normally- off behavior of the transistor was observed, and the turn-on voltage was shifted to 0 V.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1524-1532
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• 2021

In this study, Gomchwi (Ligularia fischen) derived from Taebaek-si, Gangwon-do was extracted with 70% ethanol (LFE) and antioxidant activity was measured. The following experimental techniques were used to evaluate the antioxidant efficacy of LFE. Total phenolic contents, ABTS/DPPH radical scavenging analysis, cell viability assay, NO assay, and quantitative real-time PCR technique. The content of polyphenol and flavonoid was each 113.97±0.37 mg GAE/g or 29.22±2.06 mg QE/g in LFE. DPPH radical scavenging activity was measured to be 25 ㎍/㎖ 11.26±0.95%, 50 ㎍/㎖ 17.12±0.63%, 100 ㎍/㎖ 29.54±0.36%, 250 ㎍/㎖ 68.31±0.28%, 500 ㎍/㎖ 75.12±0.05%, and 1000 ㎍/㎖ 75.75±1.57%. In addition, ABTS radical scavenging activity was identified as LFE 25 ㎍/㎖ 13.75±0.21%, 50 ㎍/㎖ 26.71±0.20%, 100 ㎍/㎖ 56.92±0.22%, 250 ㎍/㎖ 91.30±0.12%, 500 ㎍/㎖ 93.40±0.02, and 1000 ㎍/㎖ 93.19±0.04%. There was no significant cytotoxicity of LFE. NO production was significantly decreased to LFE 50 ㎍/㎖ 79.40±2.64%, 100 ㎍/㎖ 55.01±5.36%, and 200 ㎍/㎖ 30.93±3.11%. Also, the NOS2 gene expression was significantly reduced to LFE 50 ㎍/㎖ 0.94±0.11, 100 ㎍/㎖ 0.59±0.05, and 200 ㎍/㎖ 0.32±0.04. This result objectively confirmed the antioxidant effect of Gomchwi. We will continue to conduct in-depth research. Therefore, it is believed that the possibility of using Gomchwi as a cosmetic and functional food material can be established.

• The Journal of the Korea Contents Association
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• v.22 no.6
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• pp.369-385
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• 2022

This thesis was a phenomenological study of an after-school picture book making program for middle school students. This study attempted to establish a theoretical system for picture book making activity by analyzing the process of self-discovery and healing through the picture book making activity. The participants were six middle school students, the picture book making activity program was organized into five stages, and in-depth interviews of the study participants and their interpretation of picture books were described. According to the research results, first, the making activity of picturebooks can construct one's own world through hyper-reality that is more excessive than the original. Second, it can be said that the fearful existence of a monster has developed awareness and insight to view its own problems from various angles through defamiliarization. These results might be that the making activity of picturebooks is a way of revealing one's existence to the world, and through this, the process of exploring and constructing the meaning of oneself and daily life. Discussion was made based on this about the creation of another world where the picturebook making activity is different from the original, the stimulating effect of the subconscious mind through the defamiliarization device, and the establishment of self-existence in picturebook creation.