• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.161-168
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• 2021

This paper is a maintenance system for bridge represented by Class 3 and other than by law bridges. Domestic bridge are divided into Class 1 & 2 bridges and Class 3 & other than by law bridges. The number of type 3 and other than by law bridges is very large. But, it is considered to be of relatively low importance compared to Class 1 & 2 Bridge Bridge. So, in this paper is propose a maintenance system and procedure for small & medium-sized bridges. However, because the number of small & medium-sized bridges is large, it is not possible to evaluate the performance of all bridges like Class 1 & 2 bridge. The reason is the lack of manpower and budget. Based on the Risk Matrix method, a maintenance procedure was created to select the bridge for which performance evaluation should be performed first. For this purpose, basic information of the bridge is used. And, the developed maintenance procedures were applied to the bridges in actual use.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.585-592
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• 2017

Most sewer lines buried in the city are likely to be collapsed due to serious aging. Also, due to the high concentration of development and high population density and traffic, the collapse of the sewer will cause enormous social and economic damage. Therefore, proactive maintenance is required to prevent accidents caused by deteriorated sewer pipe. In order to utilize limited budget effectively, risk-based prioritization methods should be proposed that simultaneously consider the consequence of failure and the probability of failure. In this study, the method of risk-based prioritization of sewer was examined by reviewing various cases of overseas studies and applied to the urban sub-catchment. First, the impact factors that can be secured through the sewer GIS DB in Seoul were derived, and the weight, sub-criteria, and impact score of each impact factor were determined and the consequence of failure was calculated by weight sum method. In addition, the probability of failure was calculated by dividing the service life by the estimated useful life, and the consequence of failure and the probability of failure were classified into five grades by the Jenks natural breaks classification method. The prioritization method was applied to sub-catchment in the Seoul to derive a risk matrix and a risk grade. As a result, 26% of all subjects were selected as the inspection priority subjects with 4-5 risk grade. Therefore, using the risk-based CCTV prioritization methodology, it will be possible to systematically determine the objects that need investigation first.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.624-635
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• 2019

Bird strike accidents, a collision between aircraft and birds, have been increasing annually due to an increasing number of aircraft operating each year to meet heavier demand for air traffic. As such, many airports have conducted studies to assess and manage bird strike risks effectively by identifying and ranking bird species that can damage aircraft based on the bird strike records. This study was intended to investigate the bird species that were likely to threaten aircraft and compare and discuss the risk of each species estimated by the single-matrix and multi-matrix risk assessment models based on the Integrated Flight Information Service (IFIS) data collected in Gimpo, Gimhae and Jeju Airports in South Korea from 2005 to 2013. We found that there was a difference in the assessment results between the two models. The single-matrix model estimated 2 species and 6 taxa in Gimpo and Gimhae Airports and 2 species and 5 taxa in Jeju Airport to have the risk score above "high," whereas the multi-matrix model estimated 3 species and 5 taxa in Gimpo Airport, 4 species and 5 taxa in Gimhae Airport, and 2 species and 3 taxa in Jeju Airport to have the risk score above "very high." Although both models estimated the similar high-risk species in Gimpo and Gimhae Airports, there was a significant difference in Jeju Airport. Gimpo and Gimhae Airports are near the estuary of a river, which is an excellent habitat for large and heavy waterbirds. On the other hand, Jeju Airport is near the coast and the city center, and small and light bird species are mostly observed. Since collisions with such species have little effect on aircraft fuselage, the impact of common variables between the two models was small, and the additional variables caused a significant difference between the estimation by the two models.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.05a
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• pp.468-473
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• 2003

유화중합은 물을 용매로 사용하기 때문에 화재와 폭발의 위험성이 없고 환경문제가 없으며 원료 원가 면에서 저렴한 특징이 있기 때문에 수요가 매년 증가하고 있는 실정이다. 이 같은 장점을 지닌 유화중합은 물을 분산매로 폴리머를 제조하는 유용한 기술이지만 유화제, 이온성의 개시제 등과 같이 폴리머 본래의 성질을 저하시키며 물에 잘 용해되는 성분을 수반한다. 따라서 이러한 기존 유화중합법의 단점을 보완한 새로운 에멀젼 라텍스 제조기술로서, 유화제 대신에 폴리비닐알콜과 같은 보호폴로이드 또는 유기 과산화물을 사용하는 무유화제 제조기법에 대한 연구가 이루어지고, 이와 같이 제조된 에멀젼 라텍스는 기존 공정에 의해 제조된 제품에 비해 내수성과 건조된 필름의 인장 강도 및 여러 매트릭스에 대한 부착력이 향상된다. 그러나 이들 방법으로 제조된 폴리머도 복합 물성이 요구되는 분야에는 한계가 있어 복합 라텍스 제조에 대한 새로운 연구가 최근에 많이 되고 있다.(중략)

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.139-140
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• 2020

우리나라는 국제해사기구에서 제시한 자율수준 3단계의 자율운항선박 기술개발 사업을 추진 중에 있으며, 자율운항선박 및 원격운항센터의 사이버보안에 관한 기술개발이 핵심과제로 포함되어 있다. 국제해사기구는 현존선의 대한 사이버 위협에 대한 조치로 제98차 해사안전위원회에서 '해상 사이버 위험관리 지침(Guidelines on maritime cyber risk management)'을 채택 및 승인하였다. 자율운항선박이 디지털 센서의 거대시스템임을 고려할 때 기술개발 완료시 해상에서 기존 선박과 자율운항선박의 공동 운항을 고려하여 해상교통관제체계(VTS)에 대한 사이버보안 측면을 고려 할 필요가 있다. 이 논문에서는 부산항 VTS 관제사(VTSO)를 대상으로 하여 자율운항선박 운영을 고려한 VTS 관제시스템의 사이버보안 만족도를 조사하였다. VTSO를 대상으로 한 사이버보안 만족도 조사 및 분석방법은 IPA(Importance Performance Analysis) 매트릭스를 적용하였다.

• Journal of the Korea Society of Computer and Information
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• v.25 no.8
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• pp.151-157
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• 2020

The first thing we can consider to prevent juvenile delinquency is to punish those criminals. However, this is not always the proper solution. In consideration to the feature of juvenile period when they lack in proper judgment it is better to provide education than punishment so that they are not branded as criminals in our society. Also, by returning to the society, they can obtain social techniques and obtain the opportunity of making contribution to the society, which is also good for their career development. Combining international examples on juvenile delinquency prevention, there is a need to comprehensively evaluate level of probation and risk exposure of juvenile based on placement matrix of comprehensive strategy program in the US. Also, control solution by juvenile crime development phase should be made. In terms of control treatment based on crime phase, crime history should be considered when applying control. For the subject of preventing juvenile crime, it shouldn't be legal organizations like before but shall be home, school, local society, and legal organization together.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.477-484
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• 2014

Caldera is a large depression commonly formed by collapse of the ground following explosive eruption of a large body of stored magma. On earth, calderas and caldera complexes range in size from kilometers to tens of kilometers. Historical eruptions associated with caldera collapse have led to huge fatalities in Indonesia as well as left global impacts. This study presents case study on calderas in Indonesia which resembles to Mount Baekdu located at the border of China and North Korea; in the perspectives of similar characteristics, principal hazard, recent symptom of volcanic activity and the threat if eruption occurs in the near future. Calculation by using weighted evaluation matrix for Mount Krakatau, Mount Tambora, Mount Ijen, Tengger Caldera, Mount Rinjani and Ranau Caldera were taken for the selection of a site for future case study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.563-569
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• 2020

Presenting the impact of meteorological disasters departs from the traditional weather forecasting approach for meteorological phenomena. It is important to provide impact forecasts so that precautions against disruption and damage can be taken. Countries such as the United States, the U.K., and France already conduct impact forecasting for heavy rain, heavy snow, and cold weather. This study improves and applies forecasts of the impact of heavy rain among various weather phenomena in accordance with domestic conditions. A total of 33 impact factors for heavy rain were constructed per 1 km grids, and four impact levels (minimal, minor, significant, and severe) were calculated using standard normal distribution. Estimated criteria were used as indicators to estimate heavy rain risk impacts for 6 categories (residential, commercial, utility, community, agriculture, and transport) centered on people, facilities, and traffic.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.2
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• pp.139-145
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• 2017

Recently, gusts, typhoon and tsunamis have been occurring more frequently around the world. In such an emergency situation, a moored vessel can be used to predict and analyze other vessel behavior, but if the mooring system is destroyed, marine casualties can occur. Therefore, it is necessary to determine quantitatively whether a vessel should be kept in the harbour or evacuate. In this study, moored ship safety in an exclusive wharf according to swell effects on motion and mooring load have been investigated using numerical simulations. The maximum tension exerted on mooring lines exceeded the Safety Working Load for intervals 12 and 15 seconds. The maximum bollard force also exceeded 35 tons (allowable force) in all evaluation cases. The surge motion criteria result for safe working conditions exceeded 3 meters more than the wave period 12 seconds with a wind speed of 25 knots. As a result, a risk rating matrix (risk category- very high risk, high risk and moderate risk) was developed with reference to major external forces such as wind force, wave height and wave periods to provide criteria for determining the control of capabilities of mooring systems to prevent accidents.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.8
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• pp.287-300
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• 2021

Collaborative Cyber-Physical Systems (CCPS) are those systems that contain tightly coupled physical and cyber components, massively interconnected subsystems, and collaborate to achieve a common goal. The safety of a single Cyber-Physical System (CPS) can be achieved by following the safety standards such as ISO 26262 and IEC 61508 or by applying hazard analysis techniques. However, due to the complex, highly interconnected, heterogeneous, and collaborative nature of CCPS, a fault in one CPS's components can trigger many other faults in other collaborating CPSs. Therefore, a safety assurance technique based on fault criticality analysis would require to ensure safety in CCPS. This paper presents a Fault Criticality Matrix (FCM) implemented in our tool called CPSTracer, which contains several data such as identified fault, fault criticality, safety guard, etc. The proposed FCM is based on composite hazard analysis and content-based relationships among the hazard analysis artifacts, and ensures that the safety guard controls the identified faults at design time; thus, we can effectively manage and control the fault at the design phase to ensure the safe development of CPSs. To justify our approach, we introduce a case study on the Platooning system (a collaborative CPS). We perform the criticality analysis of the Platooning system using FCM in our developed tool. After the detailed fault criticality analysis, we investigate the results to check the appropriateness and effectiveness with two research questions. Also, by performing simulation for the Platooning, we showed that the rate of collision of the Platooning system without using FCM was quite high as compared to the rate of collisions of the system after analyzing the fault criticality using FCM.