• Journal of the Korea Institute of Information Security & Cryptology
• /
• 제28권4호
• /
• pp.1009-1019
• /
• 2018

Bitcoin is the first application utilizing the blockchain, but it has limitations in terms of scalability. The concept of Lightning Network was recently introduced to address the scalability problem of Bitcoin. In this paper, we found that the real-world Bitcoin Lightning Network shows the scale-free property. Therefore, the Bitcoin Lightning Network can be vulnerable to the intentional attacks targeting some specific nodes in the network while it is still robust to the random node failures. We experimentally analyze the robustness of the Bitcoin's Lightning Network via the simulation of network attack model. Our simulation results demonstrate that the real-world Lightning Network is vulnerable to target attacks that destroy a few nodes with high degree.

• Journal of the Korean Institute of Educational Facilities
• /
• 제21권6호
• /
• pp.3-12
• /
• 2014

After the introduction of the 7th education program, educational facilities have been requested to change to face new curriculums and have been planned. The purpose of this study is to fill up a gap between the study of education facilities, building planning and real educational spot and also find difference of plan composition by analyzing latest middle school floor plans. In this regard, floor plans of 8 middle schools proposed in LH design competition is compared and analyzed in this study. To sum up this analysis, the guide lines suggested from Korean educational development institute(KEDI) has not been followed in many building planning. For subject classrooms, guide lines from KEDI were ignored and support facilities did not planned as necessary space calculated through scale estimation program. To select a planned proposal in the future, demand of scale estimation, various studies, real educational spot and etc. should be reflected.

• Journal of the Korean Solar Energy Society
• /
• 제34권3호
• /
• pp.49-56
• /
• 2014

A fiat-plate or vacuum tube solar collector have been mainly used for hot water supply of house because of some being difficult to get uniform energy density, so little applied into industrial field. This study is to apply the PTC(parabolic trough collector) solar collector into industrial field such as sludge dewatering system for energy reduction. The real scale system which composed of PTC Solar Collector and Thermal Dewatering (TDW) is established. PTC solar collector is designed to produce a hot water with $80^{\circ}C$ of temperature. And size of TDW is $630{\times}630mm$. Hot water produced from PTC solar collector is supplied into heating plate of TDW, and sludge like waterworks or wastewater is dewatered. PTC solar collector with $10m^2$ of area produce energy of average 5,618 kcal. As according to results from real scale performance, solar collector takes charge 94 % of the amount that TDW consume energy which is so large part if compare with boiler. It means that PTC solar collector is useful to apply industrial field under the condition of sufficient solar radiation. And it is analyzed that TDW by PTC solar collector has an economical validity.

• Journal of Environmental Science International
• /
• 제29권12호
• /
• pp.1153-1170
• /
• 2020

With global warming and the rapid increase in urbanization accompanied by a concentration of population, the urban heat island effects (UHI) have become an important environmental issue. In this study, rooftop greening and permeable asphalt pavement were selected as measures to reduce urban heat island and applied to a simple virtual urban environment to simulate temperature change using ENVI-met. A total of five measures were tested by dividing the partial and whole area application of each measure. The results showed that the temperature range of the base experiment is 33.11-37.11 ℃, with the UTCI comfort level described as strong heat and very strong heat stress. A case applied permeable asphalt has a greater temperature difference than a rooftop greening case, the larger the area where each condition was applied, the greater the temperature change was.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• 제13권1호
• /
• pp.99-113
• /
• 2003

As a research on PKI(Public Key Infrastructure) is being very popular, the study relating to certificate status and path validation is being grown with aim to reduce an overhead of the protocol and to provide an efficient operation. But in spite of a lot of related research there is still almost no protocol that we can use for real-time based client-server environment with large scale like internet banking. In this paper, we shows that the existing standards or protocols are not suitable to be used for such a real-time based client-server environment with large scale, and then proposes an efficient certificate status and path validation system.

• International Journal of Computer Science & Network Security
• /
• 제22권2호
• /
• pp.199-208
• /
• 2022

The world health organization classified the emerging coronavirus (known as Covid-19) as a pandemic after confirming the extent of spread and scale. As a matter of fact, outbreaks of similar scale or even worse have been witnessed throughout history. Thus, the development of prevention strategies exists to protect against such calamaties. One of the widely proven measures that controls the spread of any contagious diseases is social distancing. As a result, this paper will demonstrate the concept of an application "Be Aware" on enabling the implementation of this preventive measure. In particular "Be aware" evaluates the extent of congestion in public places using current time data. The proposed project will use Global Positioning System (GPS), and Application Programming Interface (API), to ensure information accuracy, and the API use Crowdsourcing to collect Real-Time Data (RTD) from the selected places. One line

• Journal of the Korea Institute of Building Construction
• /
• 제21권6호
• /
• pp.617-627
• /
• 2021

In this study, a numerical analysis using a three-dimensional numerical simulation was performed to assess the applicability of foundation reinforcing method using load transfer apparatus which can be used in the remodeling of deteriorated structures. The numerical model was validated through comparison with the real scale experimental results, and then a parametric study was performed to investigate the effect of friction coefficient of load transfer apparatus and axial stiffness of pile on the performance of foundation reinforcing method. It was confirmed that the foundation reinforcing method considered in this study can efficiently control the load applied to an existing foundation.

• Structural Monitoring and Maintenance
• /
• 제9권4호
• /
• pp.359-371
• /
• 2022

Bridges are critical to the civil engineering infrastructure network as they facilitate movement of people, the transportation of goods and services. Given the aging of bridge infrastructure, federal officials mandate visual inspections biennially to identify necessary repair actions which are time, cost, and labor-intensive. Additionally, the expansion joints of bridges are rarely monitored due to cost. However, expansion joints are critical as they absorb movement from thermal effects, loadings strains, impact, abutment settlement, and vehicle motion movement. Thus, the need to monitor bridge expansion joints efficiently, at a low cost, and wirelessly is desired. This paper addresses bridge joint monitoring needs to develop a cost-effective, real-time wireless system that can be validated in a full-scale bridge structure. To this end, a wireless expansion joint monitoring was developed using commercial-off-the-shelf (COTS) sensors. An in-service bridge was selected as a testbed to validate the performance of the developed system compared with traditional displacement sensor, LVDT, temperature and humidity sensors. The short-term monitoring campaign with the wireless sensor system with the internet protocol version 6 over the time slotted channel hopping mode of IEEE 802.15.4e (6TiSCH) network showed reliable results, providing high potential of the developed system for effective joint monitoring at a low cost.

• IEMEK Journal of Embedded Systems and Applications
• /
• 제19권2호
• /
• pp.73-81
• /
• 2024

Recently, mobile manipulators have been utilized in agriculture industry for weed removal and harvest automation. This paper proposes a domain adaptive fruit detection method for harvest automation, by utilizing OWL-ViT model which is an open-vocabulary object detection model. The vision-language model can detect objects based on text prompt, and therefore, it can be extended to detect objects of undefined categories. In the development of deep learning models for real-world problems, constructing a large-scale labeled dataset is a time-consuming task and heavily relies on human effort. To reduce the labor-intensive workload, we utilized a large-scale public dataset as a source domain data and employed a domain adaptation method. Adversarial learning was conducted between a domain discriminator and feature extractor to reduce the gap between the distribution of feature vectors from the source domain and our target domain data. We collected a target domain dataset in a real-like environment and conducted experiments to demonstrate the effectiveness of the proposed method. In experiments, the domain adaptation method improved the AP50 metric from 38.88% to 78.59% for detecting objects within the range of 2m, and we achieved 81.7% of manipulation success rate.

• The Journal of Korean Association of Computer Education
• /
• 제17권3호
• /
• pp.1-10
• /
• 2014

Smartphone addiction and internet addiction cause a serious negative social problem due to the spread of the new media which is combined with the ubiquitous function. To evaluate the degree of Internet addiction and smartphone addiction of college students in the nearby areas, K-scale of internet addiction self-diagnosis scale and S-scale of smartphone addiction self-diagnosis scale for Korean adults were applied. This study aims to develop the survey questions, which get the basic internet patterns and access the web site, and to find the hidden addicts that is not found by general K-scale and S-scale using computers and smartphones. The result shows that a method of addiction diagnosis using the tolerance degree which is calculated by smart phone's internet main activities and using time(anticipated and real time) apart from K-scale and S-scale. So hidden internet and smartphone addicts could be found through the SPSS statistical analysis program.