• Atmosphere
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• v.33 no.5
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• pp.549-560
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• 2023

This study evaluates three distinct observation methods, CRDS, OA-ICOS, and OF-CEAS, in greenhouse gas monitoring equipment for atmospheric CO₂ and CH₄ concentrations. The assessment encompasses fundamental performance, high-concentration measurement accuracy, calibration methods, and the impact of atmospheric humidity on measurement accuracy. Results indicate that within a range of approximately 500 ppm, all three devices demonstrate high accuracy and linearity. However, beyond 1000 ppm, CO₂ accuracy sharply declines (84%), emphasizing the need for caution when interpreting high-concentration CO₂ data. An analysis of calibration methods reveals that both CO₂ and CH₄ measurements achieve high accuracy and linearity through 1-point calibration, suggesting that multi-point calibration is not imperative for precision. In dynamic atmospheric conditions with significant CO₂ and CH₄ concentration variations, a 1-point calibration suffices for reliable data (99% accuracy). The evaluation of humidity impact demonstrates that humidity removal devices significantly reduce air moisture levels, yet this has a negligible effect on dry CO₂ concentrations (less than 0.5% relative error). All three observation method instruments, which have integrated humidity correction to calculate dry CO₂ concentrations, exhibit minor sensitivity to humidity removal devices, implying that additional removal devices may not be essential. Consequently, this study offers valuable insights for comparing data from different measurement devices and provides crucial information to consider in the operation of monitoring sites.

• Journal of Information Technology Services
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• v.22 no.5
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• pp.1-16
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• 2023

This study aimed to provide fundamental insights into the digital customer experience by identifying its components and analyzing their importance and satisfaction levels among youths. To achieve this objective, the components of digital customer experience were identified through a review of prior research and consultation with experts. Subsequently, a survey was conducted with 200 youths in Seoul and Gyeonggi-do. The main findings of the study are as follows: First, The components of the digital customer experience consisted of 12 items grouped into three categories. Second, an analysis of the disparity between the importance and satisfaction levels of digital customer experience revealed statistically significant differences across all items. Third, By utilizing IPA (Importance-Performance Analysis), the digital customer experience was categorized into four quadrant, each with its own characteristics and recommendations for management: The first quadrant, the "current level maintenance area," encompassed items related to "entertainment" and "recommended service." This area is currently functioning well but necessitates continuous attention and management. The second quadrant, the "area to be supported first," included items such as "personalization," "security," "inducing participation," "privacy," and "individuality expression." Intensive management and improvements are imperative in this quadrant. The third quadrant, the "long-term improvement area," consisted of items like 'consistency,' 'information quality,' and 'convenience.' These items require focus on long-term enhancement efforts. The fourth quadrant, the "areas where efforts have already been invested," encompassed items like 'accessibility' and 'deliberation.' It appears that excessive investment has been made in these areas relative to their importance, calling for selective investments while considering the specific issues associated with each factor. These research findings serve as essential data for managing the digital customer experiences of youths.

• The Journal of the Acoustical Society of Korea
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• v.25 no.3
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• pp.121-128
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• 2006

Korean pyeongyeong, a set of sixteen L-shape chime stones covering one and one third octaves, is a standard instrument in the Korean traditional court music. We analyze the vibrational mode frequencies in a pyeongyeong replica which is played at the National Center for Korean Traditional Performance Arts and pyeongyeong remains which are exhibited at King Sejong Memorial Museum. The modal shapes on the Whangjong, the 1st stone and Cheonghyurjong, the 16th stone mapped by scanning accelerometer, TV holography and STAR system. The nominal frequencies in pyeongyeong replica at the National Center for Korean Traditional Performance Arts increase linearly with the thickness of the stones and the tones are tuned in line with the musical scale of Sambunsonik. The sexagenary cycles on the pyeongyeong remains at King Sejong Memorial. which show the Year of product indirectly, are different each other and the tones are not tuned in scale. The relative frequency ratios of each modes on stones differ more than just-noticeable differences from those on the pyeongyeong replica. Modal shapes are same for the two stones regardless of the thickness.

• Tribology and Lubricants
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• v.40 no.3
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• pp.91-96
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• 2024

Recently, extensive studies have been carried out to enhance various performance aspects such as the durability, lifespan, and hardness by combining diverse materials or developing novel materials. The utilization of superhydrophobic surfaces, particularly in the automotive, textile, and medical device industries, has gained momentum to achieve improved performance and efficiency. Superhydrophobicity refers to a surface state where the contact angle when water droplets fall is above 150°, while the contact angle during sliding motion is smaller than 10°. Superhydrophobic surfaces offer the advantage of water droplets not easily sliding off, maintaining a cleaner state as the droplets leave the surface. Surface modification involves two fundamental steps to achieve superhydrophobicity: surface roughness increase and surface energy reduction. However, existing methods, such as time-consuming processes and toxic organic precursors, still face challenges. In this study, we propose a method for superhydrophobic surface modification using lasers, aiming to create roughness in micro/nanostructures, ensuring durability while improving the production time and ease of fabrication. The mechanical durability of superhydrophobic samples treated with lasers is comparatively evaluated against chemical etching samples. The experimental results demonstrate superior mechanical durability through the laser treatment. Therefore, this research provides an effective and practical approach to superhydrophobic surface modification, highlighting the utility of laser treatment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.77-86
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• 2007

The repair technique utilizing surface impregnant is widely used due to its simple construction procedures and economical benefit. Surface protection through this reparing technique cannot increase the bearing capacity of concrete members much but increase the durability performance and service life efficiently. In this study, fundamental tests such as water suction and permeation are performed for concrete specimens with several organic/inorgarnic impregnant and suitable impregnant is selected on the basis of the results. Finally, durability tests such as carbonation, freezing and thawing, and chloride attack are carried out for the concrete specimens with selected impregnant and it is experimentally verified that they have good resistance to deteriorations.

• Korean Journal of Construction Engineering and Management
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• v.25 no.5
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• pp.3-14
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• 2024

Recently, both nationally and internationally, various BIM guidelines have been developed. These guidelines present fundamental principles and standards for the application of BIM. However, practical BIM guidelines for the schedule management area in the construction phase are lacking, making it difficult to apply them effectively in practical work settings. In this study, performance-based delivery guidelines are presented for the key functionalities of 4D CAD systems, which are representative BIM tools used in the construction phase. To achieve this, a survey analysis was conducted to determine the prioritization of these functionalities. Based on the characteristics of the project, delivery guidelines were formulated to allow users to selectively utilize the guidelines at different levels. Furthermore, practical ways to utilize performance-based delivery guidelines for schedule management using 4D CAD were proposed, validating the usability of these guidelines. The research findings suggest that these guidelines for BIM functionality in schedule management can hold practical significance as the utilization of BIM in construction phases continues to increase.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.38-41
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• 2024

In semiconductor manufacturing, the alignment process is fundamental to all manufacturing steps, and alignment errors are inevitably introduced. These alignment errors can lead to issues such as increased resistance, signal delay, and degradation. This study systematically analyzes the changes in the electrical characteristics of the bonding interface when alignment errors occur in metal interconnect and bonding structures. The results show that current density tends to concentrate at the edges of the bonding interface, with the middle part of the interface being particularly vulnerable. As alignment errors increase, the current path redistributes, causing previously concentrated current areas to disappear and an effect similar to an increase in contact area, resulting in a decrease in resistance in certain vulnerable parts. These findings suggest that proposing structural improvements to eliminate the vulnerable parts of the bonding interface could lead to interconnect with significantly improved resistance performance compared to existing structure. This study clarifies the impact of alignment errors on electrical characteristics, which is expected to play a crucial role in optimizing the electrical performance of semiconductor devices and enhancing the efficiency of the manufacturing process.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.805-811
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• 2004

In this paper, effects of mixture proportion and material condition on both fundamental properties, drying and autogenous shrinkage of high performance concrete are discussed. According to the results, for the effect of mixture proportion on the fundamental properties, decrease in W/B and unit water content results in reduction of fluidity, while air content has no variation. Compressive strength exhibits an decreasing tendency with an increase in W/B and unit water content do not remarkable affect the compressive strength. For the effect of materials on the fluidity, the fluidity of low heat portland cement(LPC) is smaller than that of ordinary portland cement(OPC). The use of Polycarbonic acid based superplasticizer(PS) has more favorable effect on enhancing fluidity than Naphtalene based superplasticlzer(NS) and Melamine based superplasticizer(MS). Air content of concrete using LPC is larger than that using OPC. The effects of superplasticizer type on the air content is larger in order of MS, PS and NS. The use of LPC exhibited lower strength development at early age than OPC, whereas after 91days, similar level of compressive strength is achieved regardless of cement type. Compressive strength of concrete is not affected by SP type. For the effect of mixture proportion and materials on drying and autogenous shrinkage, an increase in W/B results in reduction of drying shrinkage and an decrease in water content leads to reduce drying shrinkage. Autogenous shrinkage is not observed until 49 days with the concrete mixture with $35\%$ of W/B and $145 kg/m^3$ of water content. This is due to the combination effects of expansion admixture and shrinkage reducing admixture, which causes an offset of autogenous shrinkage. The use of LPC results in a reduction in autogenous shrinkage compared with OPC. SP type has little influence on the autogenous shrinkage. It is found from the results that mixture proportioning of high performance concrete incorporating fly ash, silica fume, expansion admixture and shrinkage reducing admixture is need to focus on the increase in W/B and the reduction in water content and the use of LPC and MS is also required to use to secure the stability against shrinkage properties.

• Journal of the Korean Wood Science and Technology
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• v.40 no.3
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• pp.186-193
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• 2012

The wood-concrete composite can be effectively applied for bridge superstructure, and the concept of fully composite action between each member is one of the most important consideration. Until now, related researches have been done mainly in North America and EU countries not enough to cover the fundamental studies. Therefore, this study is planned to perform one of the important issue for using the wood-concrete composite. The objective of this study is evaluation of shear performance with different anchorage length of steel rebar in wood. Prediction of the yield mode and the reference design value was firstly performed as the preliminary investigation. Then, initial stiffness, yield load and maximum load were derived from the shear test due to different anchorage length of the steel rebar (SD30A in Korean Standard) in wood. It was found out from this study that initial stiffness and yield load are not related with the anchorage length over 20 mm of anchorage length while maximum load shows increasing tendency till 60 mm of anchorage length. Pullout strength of inserted steel rebar in wood is considered to be one reason and this was also verified with the x-ray radiography.

• The Journal of the Korea Contents Association
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• v.12 no.4
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• pp.438-447
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• 2012

The objectives of this research are: to provide fundamental data for tourism policy and investigate medical tourism attributes by IPA(Importance-Performance Analysis) to attract Japanese medical tourists to Korea. Utilizing Japanese medical tourists as subjects of inquiry, this study evaluated the importance of medical tourism selection attributes and the rate at which these attributes were performed. Consequently, this study deduced 'convenience, service quality, differentiation, approximation' factors by factor analysis as well as the ranking among each selection attributes using T-test. The importance-performance analysis showed 'Concentrate Here' in quadrant I, 'Keep up the Good Work' in quadrant II, 'Low Priority' in quadrant III and 'Possible Overkill' in quadrant IV. The results show that "Concentrate Here" part in quadrant I is reservation procedure rapidity and information system simplicity. This means that these attributes are very important but they indicate low performance. Thus, concentration among tourism managers should be focused along these attributes. The study, then, suggests that employee who speaks Japanese fluently should be arranged during reservation procedure. Furthermore, Japanese class should become mandatory during basic employee training to improve reservation procedure rapidity. Moreover, clinic websites should concentrate on accessibility of Japanese users in such a way that they can consult their needs on line. Finally, managers should find diverse ways to bring about good service rapidly and conveniently.