• Journal of the Korean Geotechnical Society
• /
• v.40 no.3
• /
• pp.41-54
• /
• 2024

Regular monitoring plays a crucial role in ensuring the safety of geotechnical structures. Currently, nondestructive methods are employed to monitor such structures to minimize the impact, e.g., sensor-based accelerometers, displacement meters, image-based lasers, and drone imaging. These technologies can observe surface changes; however, they frequently suffer difficulties in terms of identifying changes in internal properties. To monitor changes in internal properties, in situ geotechnical investigations can be employed. A nondestructive test that can be used for this purpose is the spectral analysis of surface wave (SASW) test using geophones. The SASW test is a nondestructive method; however, due to the time required for data interpretation and the difficulty in analyzing the data, it is challenging to use the SASW test for monitoring applications that require frequent observations. However, it is possible to apply the first-step analysis, which yields the dispersion curve, for monitoring rather than the complete SASW analysis, which yields the shear wave velocity. Thus, this paper presents a fundamental study on the phase difference that derives the dispersion curve to utilize the SASW test for monitoring. The reliability of each phase difference interval is examined to determine the boundary to the subjected monitor. The study used phase difference data obtained using a geophone from a single-layered, homogeneous ground site to evaluate reliable boundaries. The findings of this study are expected to improve the utility of monitoring by identifying the ideal boundary for phase difference data.

• Journal of the Society of Disaster Information
• /
• v.20 no.2
• /
• pp.302-314
• /
• 2024

Purpose: This study proposes a fall detection model based on a top-down deep learning pose estimation model to automatically determine falls of multiple workers in an underground utility tunnel, and evaluates the performance of the proposed model. Method: A model is presented that combines fall discrimination rules with the results inferred from YOLOv8-pose, one of the top-down pose estimation models, and metrics of the model are evaluated for images of standing and falling two or fewer workers in the tunnel. The same process is also conducted for a bottom-up type of pose estimation model (OpenPose). In addition, due to dependency of the falling interference of the models on worker detection by YOLOv8-pose and OpenPose, metrics of the models for fall was not only investigated, but also for person. Result: For worker detection, both YOLOv8-pose and OpenPose models have F1-score of 0.88 and 0.71, respectively. However, for fall detection, the metrics were deteriorated to 0.71 and 0.23. The results of the OpenPose based model were due to partially detected worker body, and detected workers but fail to part them correctly. Conclusion: Use of top-down type of pose estimation models would be more effective way to detect fall of workers in the underground utility tunnel, with respect to joint recognition and partition between workers.

• Information Systems Review
• /
• v.22 no.4
• /
• pp.185-203
• /
• 2020

With the advent of 4th industrial revolution, the manufacturing industry is converging with ICT and changing into the era of smart manufacturing. In the smart factory, all machines and facilities are connected based on ICT, and thus security should be further strengthened as it is exposed to complex security threats that were not previously recognized. To reduce the risk of security incidents and successfully implement smart factories, it is necessary to identify key security factors to be applied, taking into account the characteristics of the industrial environment of smart factories utilizing ICT. In this study, we propose a 'hierarchical classification model of security factors in smart factory' that includes terminal, network, platform/service categories and analyze the importance of security factors to be applied when developing smart factories. We conducted an assessment of importance of security factors to the groups of smart factories and security experts. In this study, the relative importance of security factors of smart factory was derived by using AHP technique, and the priority among the security factors is presented. Based on the results of this research, it contributes to building the smart factory more securely and establishing information security required in the era of smart manufacturing.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.26 no.1
• /
• pp.19-37
• /
• 2024

Rockbolts are the primary-supports in NATM tunnels and are widely used at tunnel construction sites. Among the rockbolts methods applied in domestic tunnel design, fully grouted rockbolts are the most representative and frequently used. Fully grouted rockbolts exhibit relative behavior between the bolt and the ground due to the grout material. However, during numerical analysis for tunnel design, fully grouted rockbolts are often modeled in a way that does not reflect their behavior characteristics. This may result in underestimating or overestimating the force of the supports. Based on a literature review, it was analyzed that fully grouted rockbolts are modeled using truss element or cable element. To analyze the effect of grout properties of cable elements on rockbolts behavior, this paper compared the behavior of rockbolts in two models: one estimating grout properties based on rockbolt pull-out test data, and another assuming complete adhesion between the rockbolts and the ground by applying large grout properties. Under identical tunnel conditions, the numerical analysis was conducted by modeling the fully grouted rockbolts differently using truss and cable elements, and the tunnel behavior was analyzed. The research results suggest that modeling fully grouted rockbolts as a function of the interface effect between the bolts and the ground, specifically considering grout, is desirable. The use of pull-out test data to simulate the behavior of actual fully grouted rockbolts was considered as a valid approach.

• Journal of Venture Innovation
• /
• v.7 no.1
• /
• pp.17-39
• /
• 2024

The purpose of this study was to analyze the effect of the government's R&D support and the use of stock options by venture companies on the innovation of venture companies, that is, innovation capabilities and innovation performance. An empirical analysis was conducted using the partial least squares structural equation modeling (PLS-SEM) method using the data from the detailed survey of venture companies conducted on domestic venture confirmation companies. As a result of the analysis, it was found that the benefit of government R&D support had a positive (+) effect on strengthening the innovation capabilities of venture companies, and R&D support also had a positive (+) effect on the innovation performance of venture companies. Next, it was found that the use of stock options by venture companies had a positive (+) effect on the reinforcement of the innovation capabilities of companies and a positive (+) effect on the innovation performance of venture companies. In addition, it was found that the innovation capabilities of venture companies significantly mediate between the government's R&D support and the use of stock options by venture companies and the innovation performance of companies. These analysis results show that the government's R&D support and the use of stock option systems can play a meaningful role in the innovation of venture companies, and also show that the innovation capabilities of venture companies have an important meaning in the process of innovation. Therefore, it is necessary to continue the stance of R&D support for ventures and at the same time to introduce multi-faceted policy measures to support corporate capacity building, and legal and institutional maintenance and policy support to revitalize the stock option system need to be continuously provided.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.19 no.3
• /
• pp.1-11
• /
• 2024

Content is now recognized as a key resource to sustain competitive advantage in the OTT market and for e-commerce companies. Coupang is pursuing a content growth strategy to maximize the lock-in effect that binds consumers to the subscription economy and its ecosystem. Given this background, this study aims to explain Coupang's content growth momentum through a case study method and examine Coupang's content strategy in detail. Based on this, this study describes Coupang's content growth strategy in detail and confirms that Coupang differentiates its content from the competition by focusing on sports and low prices to build a lock-in effect in the subscription economy. As a result, we can summarize that the purpose of Coupang's content strategy is to build a lock-in effect for the subscription economy based on content differentiation focused on sports, a bundle strategy linked to e-commerce, and a low-cost strategy. This study contributes to the field of venture creation research by carefully analyzing how Coupang grew from a venture firm to a Decacorn corporation and developed the influence of its content in a completely different industry, and systematically explains the importance of content strategy in strengthening the lock-in effect for the subscription economy. Future research should compare the impact of content strategy of venture and startups in the contents industry to broaden the scope of research in the field and suggest deeper lessons learned.

• Applied Chemistry for Engineering
• /
• v.35 no.3
• /
• pp.200-208
• /
• 2024

Chung's equations-IX and Chung's equation-XII were utilized to predict the fire risk and evaluate fire risk ratings for four types of wood: camphor, cherry, rubber, and elm trees. The combustion tests were conducted using a cone calorimeter test method by ISO 5660-1 standards. The fire risk and fire risk rating (FRR) were compared for Fire Risk Index-IX (FRI-IX) and Fire Risk Index-XII (FRI-XII). The results yielded Fire Performance Index-XI (FPI-XI) ranging from 0.08 to 11.48 and Fire Growth Index-XI (FGI-XI) ranging from 0.67 to 111.89. The Fire Risk Index-XII (FRI-XII), indicating fire risk rating, exhibited an increasing order of cherry (0.45): Grade A (Ranking 5) < PMMA (1): Grade A (Ranking 4) < elm (1.23): Grade A (Ranking 3) < rubber (1.56): Grade A (Ranking 2) << camphor (148.23): Grade G (Ranking 1). Additionally, the fire risk index-IX (FRI-IX) was cherry (0): Grade A (Ranking 3) ≈ rubber (0): Grade A (Ranking 3) ≈ elm tree (0): Grade A (Ranking 3) < PMMA (1): Grade A (Ranking 2) << camphor tree (66.67): Grade G (Ranking 1). In general, camphor was found to have the highest fire risk. In conclusion, although the expression of the index is different as shown based on the standards of FRI-IX and FRI-XII, predictions based on fire risk assessment of combustible materials showed similar trends.

• Journal of Christian Education in Korea
• /
• v.76
• /
• pp.119-147
• /
• 2023

Purpose of study: The purpose of this study is to propose an education for biblical Shalom for the future of education in relation to UNESCO 2050. Research content and method: The education for Shalom is about experiencing Shalom in fellowship with God. Moreover, it expands that shalom into relationships with self, neighbors, the earth, and technology, and then helps achieving balance between Shalom and those mentioned above. In order to provide education for Shalom, this study presented five relational dimensions of experiencing Shalom. First, the joy of serving God and neighbors in a proper personal relationship with God is most important. Second, it is the joy of building a right community and living in it through harmonious relationships with neighbors. Third, it is the joy of living in a harmonious relationship with nature. Fourth, it is the joy of being respected for human rights that are dignified as the image of God and living while enjoying rights. Fifth, it is the joy of enjoying fair use and benefits from technological innovation without being alienated, excluded and treated unfairly, or receiving disadvantages. Based on that, a model of education for Shalom has been developed. Conclusions and Suggestions: The educational model for Shalom forms view of values, knowledge, and human nature through the Bible. It consists of learning strategies to maintain a balance between the form of knowledge and the five relational dimensions. This model has a structure that carries out education for Shalom while interacting with each other.

• Journal of the Korean Geotechnical Society
• /
• v.40 no.4
• /
• pp.69-79
• /
• 2024

Field geotechnical data are obtained from various field and laboratory tests and are documented in geotechnical investigation reports. For efficient design and construction, digitizing these geotechnical parameters is essential. However, current practices involve manual data entry, which is time-consuming, labor-intensive, and prone to errors. Thus, this study proposes an automatic data extraction method from geotechnical investigation reports using image-based deep learning models and text-mining techniques. A deep-learning-based page classification model and a text-searching algorithm were employed to classify geotechnical investigation report pages with 100% accuracy. Computer vision algorithms were utilized to identify valid data regions within report pages, and text analysis was used to match and extract the corresponding geotechnical data. The proposed model was validated using a dataset of 205 geotechnical investigation reports, achieving an average data extraction accuracy of 93.0%. Finally, a user-interface-based program was developed to enhance the practical application of the extraction model. It allowed users to upload PDF files of geotechnical investigation reports, automatically analyze these reports, and extract and edit data. This approach is expected to improve the efficiency and accuracy of digitizing geotechnical investigation reports and building geotechnical databases.

• Journal of Korea Water Resources Association
• /
• v.57 no.8
• /
• pp.549-559
• /
• 2024

This study aims to investigate the feasibility of using image analysis methods to examine the flow characteristics of air bubbles discharged underwater. A bubble screen was created using multiple nozzles in a laboratory flume filled with stagnant water. The flow characteristics of the bubbles were analyzed, and the suitability of the analysis method was evaluated. Several parameters, such as projection area ratio and depth ratio, were defined to conduct laboratory experiments and analyze the flow characteristics of the bubbles. Correlation and regression analyses were performed to assess the relationships between various variables. Specifically, the correlation between the bubble's projection area and its rising speed across eight water depth ratios was examined. The results indicated that as the depth ratio increased, the bubble size exhibited a linear increase with a strong correlation as it rose to the water surface due to pressure effects. Regarding the sensitivity of different grid sizes in the ten analysis grids when applying image analysis methods, it was observed that the sensitivity to grid size based on the projection area ratio (0.09~0.96) was not significant. These findings suggest that image analysis techniques can be effectively utilized to observe the flow characteristics of bubbles.