• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.471-478
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• 2020

In this paper, we develop the ground risk model of unmanned aerial vehicle (UAV) operation to quantify the ground risk when the UAV falls to the ground during the intended operation in case of UAV failure. The ground risk is computed by using the UAV failure probability, the probability of impact a person when UAV falls to the ground, the probability of fatality when UAV strikes the person. We mathematically derive each probability to evaluate the ground risk of UAV operation. Also, the population density map, building to land ratio map, car traffic database is used to estimate the number of people exposed to collision with UAV. Finally, we assumed the operations of a UAV with two paths in Daejeon city and evaluate the ground risk of each UAV operations.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.4
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• pp.541-547
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• 2010

Marine accidents do not correspond with another accidents because of a serious loss of lives and property. The many marine accidents can be attributed to human error like as carelessness and decision faults, and hence there is a strong need for decision-support tools for marine navigation. Much of researchers have introduced the techniques about the tools, but they hardly consider environmental factors (water depth, the width of waterway, a fishing ground, a current, the number of surrounding marine accidents, marine obstacles, etc), which are very important to the decision making of officers. In a previous research, we proposed the conceptual model of environmental risk assessment of ship navigation using fuzzy. This paper describes the detailed design of the environmental factors based on the opinion of navigation experts, and shows the validity of the conceptual model through a prototype system.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.493-498
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• 2015

When VTSOs(Vessel Traffic Service Operators) determine the degree of collision risk of two vessels, they consider comprehensively information about each vessel's course, speed, DCPA, TCPA and encountering situation. In this study, we proposed an algorithm in which two relative bearings as information about two vessel's encountering situation are used to evaluate the degree of collision risk. In order to verify whether the proposed algorithm is reasonable, we set twenty encountering situations and conducted a survey of collision risk on fifty three VTSOs about those situations. By comparing the degrees of collision risk with the proposed algorithm to the results of the survey, we found that relative bearing at CPA is very important factor for VTSO to recognize the level of collision risk when two vessels are in encountering situation.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.87-87
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• 2018

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.557-559
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• 2013

마콘도 사고 후 미국을 필두로 해양 석유 시추 및 생산활동에 대한 규제가 대폭 강화되었으며, 선진국 위주로 안전기준의 준수를 통상의 규제수단으로 이용하고 있다. 향후 해양플랜트 분야 진출을 시도하는 기업은 HSE 분야에 대한 적극적인 대응이 필요하다. 주요 선진국의 Offshore 분야 HSE 규제 동향과 안전관리시스템의 구축 방안에 대해 제안하였다.

• Journal of Navigation and Port Research
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• v.36 no.4
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• pp.321-327
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• 2012

Logistics in a supply chain network has become an important operational strategy in a competitive market. A number of internal and external risks involved in the logistics operations in a company tend to create problems in fulfilling customer orders. This research presents how ERM (enterprise risk management) can be used to identify, assess, and control logistics risks. An electronic company's logistics activities were used as an industry case to demonstrate a way to identify and assess risks surrounding global logistics function. This paper has further presented action plans to mitigate the impact of the risks that occur.

• Journal of Navigation and Port Research
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• v.35 no.9
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• pp.729-733
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• 2011

The maritime risk assessment is important not only to evaluate the safety level of the ports and waterways but also to reduce potential maritime accidents at sea in terms of the proactive measures of the maritime accidents. In this paper, the collision risk assessment in Mokpo waterways has been carried out based on the IALA recommended model, IWRAP. To evaluate the accident probabilities in Mokpo waterways, all data of vessels were collected from AIS and Radar observations data and the computer simulations were carried out. To assess the risk on the traffic, the scenario-base approach has been applied to the Mokpo waterway by using the maritime accident statics over the past 5 years.

• Journal of Navigation and Port Research
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• v.41 no.2
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• pp.71-78
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• 2017

This paper aims to investigate the time-varying systematic risk of the stocks of Korean logistics firms. For this purpose, the period from January 1991 to October 2016 was examined with respect to 21 logistics companies that are listed on the Korea Exchange. The systematic risk of the logistics stocks is measured in terms of the Capital Asset Pricing Model (CAPM) beta for which the sensitivity of a stock is compared to the return changes of the whole market. Overall, the betas of the stocks of the Korean logistics companies are significantly lower than those of the market unity; however, it was revealed that the logistics betas are not constant, but are actually time-varying according to different economic regimes, which is consistent with the previous empirical findings. This finding is robust across different measurements of the logistics betas. In addition, the impact of macroeconomic factors on the logistics betas was examined. The present study shows that the logistics betas are positively associated with foreign exchange-rate changes.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.145-150
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• 2004

This paper suggests an evaluation of risk level for damage of marine accidents in SRRs. Qualitative analyses in words is sometimes priorior to quantative analyses in numeric symbols. This paper intoduces a concept of fuzzy theory with the plenty of related literature riview and AHP in the Korean SRRs of RCC and RSC. The methodology of this paper is maxㆍmin composition of fuzzy extensive principle, defuzzifiation is centroid of gravity methods. At the result, the evaluation of risk level is especially over Serous for smarine accident of Taean, Gunsan, Mokpo, Yosu, Tongyoung, Busan SRR. This paper recommends that many Resale Vessels and Equipments need to the reduction of risk level about those.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1518-1520
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• 2008

Recent clinical studies have shown that computer navigation for total knee arthroplasty (TKA) provides improved component alignment accuracy. However, femoral stress fracture after computernavigated TKA have been reported due to the pin hole and we hypothesized that osteoporosis would be one of the key factors in pin hole fracture after computer-navigated TKA. We investigated the von-Mises stress around the femoral pin-hole for different elastic modulli and ultimate stresses and four different pin penetration modes to understand the aging effect on femoral stress fracture risk after computer-navigated TKA by finite element analysis. In this study, aging effect was shown to increase the femoral stress fracture risk for all pin penetration modes. Especially, aging effect was shown dramatically in the transcortical pin penetration mode.