• Current Optics and Photonics
• /
• v.6 no.1
• /
• pp.23-31
• /
• 2022

Heterodyne efficiency is an indicator to evaluate the performance of space coherent laser communication systems. It is affected by signal light and local oscillator (LO) light amplitude, phase and polarization state. In this paper, based on the common heterodyne efficiency, a heterodyne efficiency model that can reflect polarization aberration of optical system is proposed. The heterodyne efficiency is analyzed when the signal light and the LO light are linearly polarized or circularly polarized. For a coherent communication optical system, when the incident signal light is right-circularly polarized light and the incident LO light is 45° linear polarized light. Based on the three-dimensional ray tracing theory and the heterodyne efficiency proposed in this paper, the change of polarization states and the distribution of heterodyne efficiency of the signal light and LO light influenced by the optical system's polarization aberration are analyzed. Analysis shows that the heterodyne efficiency model proposed in this paper can be used to evaluate coherent communication systems and reflect the influence of optical system polarization aberration.

• Journal of information and communication convergence engineering
• /
• v.20 no.4
• /
• pp.280-287
• /
• 2022

Recently, the number of mobile ransomware types has increased. Moreover, the number of cases of damage caused by mobile ransomware is increasing. Representative damage cases include encrypting files on the victim's smart device or making them unusable, causing financial losses to the victim. This study classifies ransomware apps by analyzing several representative ransomware apps to identify trends in the malicious behavior of ransomware. We present a technique for recovering from the damage, from a digital forensic perspective, using reverse engineering ransomware apps to analyze vulnerabilities in malicious functions applied with various cryptographic technologies. Our study found that ransomware applications are largely divided into three types: locker, crypto, and hybrid. In addition, we presented a method for recovering the damage caused by each type of ransomware app using an actual case. This study is expected to help minimize the damage caused by ransomware apps and respond to new ransomware apps.

• Journal of Navigation and Port Research
• /
• v.45 no.3
• /
• pp.95-101
• /
• 2021

Marine Incidents based on Heinrich's law are very important in preventing accidents. However, marine Incident data are mainly qualitative and are used to prevent similar accidents through case sharing rather than statistical analysis, which can be confirmed in the marine Incident-related data posted in the Korea Maritime Safety Tribunal. Therefore, this study derived quantitative results by analyzing the causes of marine incidents during berthing using various methods of statistical analysis. To this end, data involving marine incidents from various shipping companies were collected and reclassified for easy analysis. The main keywords were derived via primary analysis using text mining. Only meaningful words were selected via verification by an expert group, and time series and cluster analysis were performed to predict marine incidents that may occur during berthing. Although the role of an expert group was still required during the analysis, it was confirmed that quantitative analysis of marine incidents was feasible, and iused to provide cause and accident prevention information.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2005.05a
• /
• pp.272-277
• /
• 2005

• Proceedings of the Korean Information Science Society Conference
• /
• 2010.06a
• /
• pp.5-6
• /
• 2010

• Proceedings of the ESK Conference
• /
• 1996.04a
• /
• pp.83-90
• /
• 1996

The purpose of an accident analysis is to obtain accurate, objective information about the causes of accidents in order to prevent the incident from reoccurring. This study is concerned with the analysis of characteristics and causes for industrial accidents in Korean industry. For the purpose, from 1972 to 1994, statistics of industrial accidents are surveyed from the 'Analysis of industrial accidents' published in Ministry of Labor. The results show that industrial accident rates have fallen considerably since the late 1970's. Also, there are some patterns in the records of industrial accidents.

• Journal of Korean Academy of Nursing Administration
• /
• v.20 no.1
• /
• pp.82-94
• /
• 2014

Purpose: This study was conducted to define the experiences of nursing activities in Gwangju area during the May 18 (5 18) Democratic Uprising over 30 years ago. Methods: Data were collected in 2010 and 2011 through individual in-depth interviews. Ten nurses who worked in general hospitals in the Gwangju area during the 5 18 Democratic Uprising were interviewed using open-ended questions. Each interview lasted about 2~3 hours. Verbatim transcripts were analyzed using Van Kaam's method of phenomenological analysis. Results: Four categories emerged from the analysis: anxiety about the incident which was experienced for the first time; progress of the 5 18 events and relationship to participants; changes in nursing environment; retrospection and wishes related to the 5 18 incident. Conclusion: This oral history study revealed more clearly of the experiences of nursing activities in the Gwangju area during the 5 18 Democratic Uprising. The data may provide a basis for writing history nursing in the community, and can be a basis for guidelines covering nursing care in crisis.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.5
• /
• pp.1058-1076
• /
• 2013

The WBAN(Wireless Body Area Network) supplies mobile convenience to our medical services. But if we have few effective control variables across this service deployment, the hidden distortions or defects of the system might threaten the lives and rights of the stakeholders. Therefore we need to increase the service credibility, to get WBAN effective. This study proposes a governance mechanism using feasible variables that are currently in use in practices in WBAN environments against medical incidents. Control variables were tested in Seoul National University hospital and related medical industries of South Korea. We assume that WBAN systems would be open based on integrating patients, medical employees and law enforcements to get smart theater operations against medical incidents by implementing proposed MJA(Multilateral Joint Analysis) model. MJA model also contributes to the convergence of computer systems and medical services by demonstrating flexible SOA(Service Oriented Architecture) dashboard of healthcare services with credibility factors in medicine. The important components in MJA model across WBAN, were found to be "Safety, Accuracy and Reliability" in priority order. Factor analysis, correlations and ANOVA were used to evaluate this model and an IT dashboard with a realization of mobile application, was used to support participants' decision-making.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.4
• /
• pp.95-104
• /
• 2002

The theoretical and analytical studies on dynamic signals(force and acceleration signals) measured at SPT rod are actively made. In this paper, the characteristics of stress wave(force signals) in SPT rod were studied experimentally using model rod system. It was noted that the amplitude ratios of reflected wave over incident wave in different end conditions were well matched with theoretical results. The impedance of soil could be determined if the characteristics of incident and reflected waves could be evaluated quantitatively in situ SPT test. On the other hand, the results of model tests showed that the effect of reflected wave caused by side friction was negligible, and therefore, the analysis model considering only end resistance of sampler could be applicable in dynamic analysis of SPT.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.7
• /
• pp.719-725
• /
• 2009

An efficient time-domain numerical method for the analysis of broadband noise generation and propagation due to turbulence-cascade interaction is developed. The core algorithm of the present method is based on the B-periodicity of the acoustic response function of the flat-airfoil cascade to the ingesting gust(B denotes the number of airfoils in the cascade). To confirm this periodicity, gust-cascade interaction problem are solved by using the time-domain method, which shows that the incident gust with the circumferential mode number having the same remainders when divided by the airfoil number excites the same acoustic response of the cascade. Using the proposed fast algorithm with this periodicity, we show that the total computation time for the model broadband problem using the total 525 incident gust modes can be reduced to about 1/4 of that taken in using the previous time-domain program.