• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.37 no.1
• /
• pp.33-40
• /
• 2024

The volume of shells, a prominent form of marine waste, is steadily increasing each year. However, a significant portion of these shells is either discarded or left near coastlines, posing environmental and social concerns. Utilizing shells as a substitute for traditional aggregates presents a potential solution, especially considering the diminishing availability of natural aggregates. This approach could effectively reduce transportation logistics costs, thereby promoting resource recycling. In this study, we explore the feasibility of employing wasted shell aggregates in 3D concrete printing technology for marine structures. Despite the advantages, it is observed that 3D printing concrete with wasted shells as aggregates results in lower strength compared to ordinary concrete, attributed to pores at the interface of shells and cement paste. Microstructure characterization becomes essential for evaluating mechanical properties. We conduct an analysis of the mechanical properties and microstructure of 3D printing concrete specimens incorporating wasted shells. Additionally, a mix design is proposed, taking into account flowability, extrudability, and buildability. To assess mechanical properties, compression and bonding strength specimens are fabricated using a 3D printer, and subsequent strength tests are conducted. Microstructure characteristics are analyzed through scanning electron microscope tests, providing high-resolution images. A histogram-based segmentation method is applied to segment pores, and porosity is compared based on the type of wasted shell. Pore characteristics are quantified using a probability function, establishing a correlation between the mechanical properties and microstructure characteristics of the specimens according to the type of wasted shell.

• Journal of Internet Computing and Services
• /
• v.25 no.1
• /
• pp.147-155
• /
• 2024

Currently, the 4th Industrial Revolution, like other revolutions, is bringing great change and new life to humanity, and in particular, the demand for and use of drones, which can be applied by combining various technologies such as big data, artificial intelligence, and information and communications technology, is increasing. Recently, it has been widely used to carry out dangerous military operations and missions, such as the Russia-Ukraine war and North Korea's reconnaissance against South Korea, and as the demand for and use of drones increases, concerns about the safety and security of drones are growing. Currently, a variety of research is being conducted, such as detection of wireless communication abnormalities and sensor data abnormalities related to drones, but research on real-time detection of threats using radio frequency characteristic data is insufficient. Therefore, in this paper, we conduct a study to determine whether the characteristic data is normal or abnormal signal data by collecting radio frequency signal characteristic data generated while the drone communicates with the ground control system while performing a mission in a HITL(Hardware In The Loop) simulation environment similar to the real environment. proceeded. In addition, we propose an unsupervised learning-based threat detection system and optimal threshold that can detect threat signals in real time while a drone is performing a mission.

• The Journal of the Acoustical Society of Korea
• /
• v.26 no.6
• /
• pp.250-258
• /
• 2007

Current speech recognition technology s achieved high performance with the development of hardware devices, however it is insufficient for some applications where high reliability is required, such as voice control of powered wheelchairs for disabled persons. For the system which aims to operate powered wheelchairs safely by voice in real environment, we need to consider that non-voice commands such as user s coughing, breathing, and spark-like mechanical noise should be rejected and the wheelchair system need to recognize the speech commands affected by disability, which contains specific pronunciation speed and frequency. In this paper, we propose non-voice rejection method to perform voice/non-voice classification using both YIN based fundamental frequency(F0) extraction and reliability in preprocessing. We adopted a multi-template dictionary and acoustic modeling based speaker adaptation to cope with the pronunciation variation of inarticulately uttered speech. From the recognition tests conducted with the data collected in real environment, proposed YIN based fundamental extraction showed recall-precision rate of 95.1% better than that of 62% by cepstrum based method. Recognition test by a new system applied with multi-template dictionary and MAP adaptation also showed much higher accuracy of 99.5% than that of 78.6% by baseline system.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.6
• /
• pp.542-547
• /
• 2009

In this in vivo study, correlations of lumbar and femoral bone mineral densities (BMDs) with calcaneal speed of sound (SOS) were investigated in 36 osteoporotic women. Areal BMDs of the L2-L4 lumbar spine and the right femoral neck were measured by using dual energy X-ray absorptiometry (DEXA). SOS of the right calcaneus was measured by using ultrasound bone densitometry. Pearson's correlation coefficient (r) and level of significance (p) were used to evaluate the correlations between measurements. Lumbar BMD was highly correlated with femoral BMD (r=0.81). Lumbar and femoral BMDs exhibited similar comparable negative correlations with age (r=-0.52 and r=-0.55). A moderate negative correlation was found between calcaneal SOS and age (r=-0.45). Calcaneal SOS was significantly correlated with lumbar and femoral BMDs, with a higher correlation with femoral BMD rather than with lumbar BMD (r=0.54 and r=0.62). However, calcaneal SOS may not be an optimum index for the estimation of BMD of the most important fracture sites, such as the lumbar and the femur, because it showed lower correlations with lumbar and femoral BMDs compared to that with calcaneal BMD. Therefore, the development of a quantitative ultrasound technology for the direct measurement of acoustic properties at the lumbar and the femur is required to estimate BMD of these sites more accurately.

• Journal of Industrial Convergence
• /
• v.22 no.5
• /
• pp.89-96
• /
• 2024

This is a descriptive research study to confirm the mediating effect of empathy in the relationship between communication skills and interpersonal relationship of MZ generation nursing students. The subjects of this study were 129 nursing students born in 1981 to 2006, corresponding to the MZ generation, and the data collection period was from May 20 to July 30, 2023. The collected data were analyzed using the SPSS 25.0 program, and the mediating effect of empathy was tested by Baron and Kenny's three-step mediating effect verification procedure, and Sobel test was conducted to test the statistical significance of the mediating effect. As a result of the analysis, communication skills (β=.45, p<.001) and empathy (β=.18, p=.008) had a significant effect on interpersonal relationship. These variables were found to have 48.4% explanatory power for interpersonal relationship. Empathy had a partial mediating effect (z=2.39, p=.016) in the relationship between communication skills and interpersonal relationship. Based on the results of this study, it is necessary to understand the characteristics of the MZ generation familiar with the non-face-to-face culture that will be in charge of future nursing and to develop effective programs to improve their interpersonal relationship.

• Journal of Korea Water Resources Association
• /
• v.57 no.1
• /
• pp.45-58
• /
• 2024

Drought risk is expected to increase as the frequency, intensity, and duration of droughts increase due to climate change. Drought risk is related to not only hydro-meteorological factors, but also water supply and demand. Recently, along with climate change, socioeconomic factors have also been recognized to increase drought risk. Therefore, it is necessary to outlook the drought risk considering various conditions for coping with future extreme droughts in a timely manner. In addition, considering various drought scenarios help reduce the uncertainty in future drought outlook. In this study, drought scenarios considering climate change scenarios, population, and water demand were created to outlook drought risk for 160 administrative districts in Korea, then new levels of drought risk were assigned based on the results of drought risk outlook to suggest drought management measures. The results showed that the drought risk will increase in the future in 2020, 2025, and 2030, compared to past. Especially the drought risk is likely twice as high in 2030 under the baseline and high scenarios. Applying the drought outlook results from this study to the new methodology for setting the risk levels shows that most regions are in Response (V) in 2020 and 2030 for baseline and high scenarios.

• Knowledge Management Research
• /
• v.24 no.4
• /
• pp.131-152
• /
• 2023

One of the key domains within a smart tourism city, smart mobility, encompasses advanced transportation means and services rooted in Information and Communication Technology (ICT). This includes shared bicycles, scooters, car-sharing services, smart transportation infrastructure, and more, aiming to surpass limitations of conventional transport and improve the movement of people and goods. It also serves tourists as an affordable and convenient mode of transport between attractions while also enhancing the overall travel experience. This study has defined 'smart tourism mobility' as a form of mobility grounded in ICT, exhibiting exceptional connectivity, serving public interest, and serving as a mode of transport for both residents and tourists in a smart tourism city. The research aimed to outline the scope of smart tourism mobility-related industries through expert Delphi surveys and estimate their economic effects within a smart tourism city. Specifically, this study updated 2015 input-output table and made 2020 regional input-output table of Seoul adopting RAS method and location quotient method. The results showed that the about 2.8 billion KRW investment of Seoul in smart tourism mobility may create more than 4.1 billion KRW in production inducement effect which is expected to create more than 1.6 billion KRW of income-inducing effect, 3.6 billion KRW of value-added-inducing effect, and 54 employment across all industries in Seoul in 2022.

• Knowledge Management Research
• /
• v.24 no.4
• /
• pp.219-235
• /
• 2023

The advancement of digital technology and the impact of COVID-19 have brought about changes in corporate innovation and organizational culture, thereby highlighting the significance of Smart Learning in the field of HRD (Human Resource Development). This trend has led to an increased interest in personalized Smart Learning among employees due to the growth of hybrid work and the widespread adoption of smart work practices. This study aimed to illuminate the relative importance of the factors that constitute Smart Learning from the perspective of HRD practitioners. Through a review of prior literature, Smart Learning hierarchy and factors most fitting to the current context were identified, and their relative importance was determined using the AHP method. Consequently, in the first-tier factors, importance was confirmed in the order of 'Learning Activities', 'Teaching Activities', 'Learning Content', 'Assessment and Evaluations', and 'Learning Time and Space'. At the second-tier encompassing all factors, 'Pedagogical Strategy', 'Learning Results', 'Learning Tasks', 'Learning Goal', and 'Learning Support' emerged within the top five factors. These findings are significant in that they redefine the concept of smart learning and propose an academic framework for future research. Additionally, from a practical perspective, it is anticipated that this study will contribute valuable insights for HRD practitioners, aiding them in focusing on which factors to prioritize for enhancing and advancing Smart Learning initiatives.

• Science of Emotion and Sensibility
• /
• v.26 no.4
• /
• pp.71-92
• /
• 2023

This study investigates the symbolism and meaning of the bead design, its relationship with the Silla culture, and the conditions of glass bead manufacturing to verify the theory of Silla's production of Silla face-inlaid glass beads with excellent artistry and technology. The research method includes investigating the design analysis, ancient documents, myths, relics, glass, and metal production techniques. Moreover, Hongshan cultural relics and other cases of inlaid glass beads were collected. There are records in the literature that the people of Makhan, Buyeo and Silla of ancient Korea people considered beads as treasures and used them for accessories. It was confirmed that all the design elements of the bead-patterned hair topknot, golden crown, birds, and flower trees were closely related to the myth of Kim Al-ji of Silla, the oviparous tales and the sacred birds and divine beasts of the north. Moreover, the pattern and arrangements were found to be similar in other Silla relics. The origin of beads and face pendants was Hongsan culture, and a stone cast for beads was discovered in Bukpyo of Gojoseon, the lower-level culture of Hajiajeom. In addition, excavating inlaid glass beads from Sik-ri tombs of Korea and a face-inlaid glass bead from Toganmori tombs in Japan confirms the theory of Silla's production. The fact that the Baekje people of ancient Korea had a glass bead manufacturing office in Japan in the fifth centuries suggests that the Silla people also had a manufacturing plant in Java, Indonesia, because this place was a crossroads of Silla's Sea Silk Road and a source of raw materials and labors with a close relationship to Silla. Therefore, the face-inlaid glass bead was indeed self-made by Silla, who possessed the tradition of bead myths and hair topknot, and the high-level skills such as gold crowns and metal inlays.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.25 no.6
• /
• pp.469-478
• /
• 2023

The deep tunnel in urban area is a future-oriented construction plan that allows the above-ground space to be used as an eco-friendly park and transportation infrastructure to be constructed in the underground space. However, tunnel construction is often depicted as to cause ground collapse in some media and movies. In fact, while the construction of a deep tunnel in the urban area is underway, the project face with difficulties due to opposition complaints from residents near the route. In this study, we sought to identify perceptions on deep space development and citizen concerns through a public opinion survey regarding deep tunnels. By analyzing laws relevant with the promotion of deep tunnel construction, we reviewed the possibility of public engagement at each stage of the construction and investigated separated surface rights related to compensation for underground space. Through the results of the public opinion survey, it was identified that the concerns of citizens were problems that current technology could solve. Citizen's concerns were improved into a system that confirmed the stability of tunnel construction through public participation, and improvement measures were presented to encourage cooperation from those concerned regarding the establishment of divided superficies.