• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.56 no.2
• /
• pp.163-171
• /
• 2020

Engaged in trawling in limited fishing grounds with a number of fish schools could cause collisions between fishing vessels. Therefore, providing accurate maneuver information according to the situation could be regarded as essential for improving seafarers safety and fishing efficiency as well as safety of navigation. It is difficult to obtain all maneuver information through sea trial tests only, so a method through empirical formula is necessary. Since most empirical formulas are developed for merchant ship types, especially the characteristics of hull shape parameter like C_bB/L and dC_b/B etc. are clearly different between fishing vessels and merchant ships, this could occur estimation errors. Therefore, in this study, the authors have selected target fishing vessels and merchant ships and analyzed the characteristics of hull shape parameter according to the ship types. Based on this analysis, the empirical formula developed for the merchant ship type has applied to the target fishing vessels; it has verified through the turning motion simulation that the estimation error could be generated. In conclusion, it is necessary to include the characteristics of the hull shape parameter of fishing vessels in the empirical formula in order to apply the empirical formula has developed for merchant ship types to fishing vessel types.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.21 no.5
• /
• pp.571-576
• /
• 2015

This paper presents a comparative study of wave height estimation method that was used for signal to noise ratio and shadowing ratio based on X-band marine radar. If the signal to noise ratio, and is widely used as a method for estimating an wave height, a new method is presented for shadowing ratio. In the case of radar images used in this study it is measuring the data from the coast of Ulsan Jujeon, compared with marine meteorological information from the Meteorological Agency measured a light beacon. We compared the measured data for about 34 days, the typhoon was measured, incluidng a period in the East Sea, and verify the results for various distribution of wave height. For estimate wave height using a shadowing ratio analysis, it does not require calibration and real-time advantages of this part, coming confirmed the possibility of the measurement, the cause detection error for radar image was caused due to determine.

• Journal of the Korean Institute of Gas
• /
• v.24 no.6
• /
• pp.91-97
• /
• 2020

Lithium-ion batteries (LIBs) have a longer lifespan, higher energy density, and lower self-discharge rates than other batteries, therefore, they are preferred as an Energy Storage System (ESS). However, during years 2017-2019, 28 ESS fire accidents occurred in Korea, and accurate capacity estimation of LIB is essential to ensure safety and reliability during operations. In this study, data-driven modeling that predicts capacity changes according to the charging cycle of LIB was conducted, and developed models were compared their performance for the selection of the optimal machine learning model, which includes the Decision Tree, Ensemble Learning Method, Support Vector Regression, and Gaussian Process Regression (GPR). For model training, lithium battery test data provided by NASA was used, and GPR showed the best prediction performance. Based on this study, we will develop an enhanced LIB capacity prediction and remaining useful life estimation model through additional data training, and improve the performance of anomaly detection and monitoring during operations, enabling safe and stable ESS operations.

• Journal of the Korean Society of Safety
• /
• v.30 no.4
• /
• pp.92-98
• /
• 2015

This paper was carried out to prove the relation between static loads acting on the sluice(hydrostatic) and dynamic loads (additional loads) arising from opening or closing of sluice, through measuring the operation of shell-type roller gate by using the method of measuring of the completely opening water gate, as measured from one excitation state, it was confirmed to be capable of measuring the natural frequency reliable measurement results. Throughout the test, we prove that it's a reasonable way to estimate the default margin of safety when calculated by dividing the sum of the hydrostatic stress to the maximum stress and additional stress. The application of this paper's safety estimation method can be utilized as the basic data for the systematic and rational maintenance management of dams and submerged weirs in the future, and it is expected that this study can bring forth.

• Aerospace Engineering and Technology
• /
• v.7 no.2
• /
• pp.123-130
• /
• 2008

Flight safety analysis, which includes risk estimation for the various abnormal flight modes in addition to normal flight, has to be performed necessarily to guarantee launch safety for the operation of space launch vehicles. For this purpose, a dedicated system has been developed such that all the necessary repetitive computations, result reports, and graphical presentations can be performed inside a single system for user convenience. In addition, the developed system is capable of representing computed results on a three dimensional Earth for the realistic presentation. The developed Flight Safety Analysis System will be employed for the launch operation of Korea Satellite Launch Vehicle-I.

• Journal of Navigation and Port Research
• /
• v.28 no.7
• /
• pp.609-617
• /
• 2004

The total tug capacity needed for berthing/unberthing operations of a ship may vary depending on the ship's type, size, loading conditions, and environmental circumstances. Traditionally, total tug capacity is determined based on the local guidelines of port authorities or on the rule of thumb. However, the social demands for the enhancement of ship safety at harbor and the economical demands for the cost-effectiveness of tug usage makes it necessary for port authorities to develop more reasonable and detailed guidelines on tug usage which takes various conditions into account. In this paper, the method to estimate the optimum tug capacity of VLCC is suggested by considering various ship conditions such as its size, loading conditions, and environmental circumstances including wind, wave, tidal currents, and geographical characteristics of a terminal. This method is applied to the VLCC terminal located in Gwang-Yang harbor of Korea and the results are compared with the local guidelines of the harbor, which shows that there may be a room for the amendment of local guidelines on tug usage.

• International Journal of Safety
• /
• v.11 no.2
• /
• pp.10-14
• /
• 2012

Recently, the combined power plants are refocused rapidly as a replaceable energy system of the nuclear power plant. The large turbine is revolved highly at 1800~3600 rpm. Thus, the turbine speed should be monitored with mechanical and electrical method for a safety. The electrical cutoff valve which blocks the flow channel with the electrical signal is with a built in. The aim of this study is to develop a manufacturing technology through by the localization of a solenoid actuated directional control valve. Especially the results show performances of the solenoid valve by the experiments and modeling and the reliability estimation. Applied load port pressure was changed rapidly on the form of a quadratic curve over time. And in the cases of square waveform when 0~100 V and 20~120 V input voltage, it was driven on a stable state until 13.4 Hz and 16.6 Hz, respectively. We think that this study will give useful data for the electricity safety system of the combined power plant gas turbine.

• Journal of the Korean Society of Safety
• /
• v.33 no.5
• /
• pp.28-34
• /
• 2018

Recently, various engineering approaches have been widely used in the accident investigation field to identify the cause of the accident and to predict damage by accident. Computational analysis is the most commonly used method of accident investigation technique. This technique is mainly used to identify the mechanism of the accident generation and to determine the cause when it is difficult to reproduce the situation at the time of the accident or when it is impossible to perform a reproduction experiment. In this study, The computational fluid dynamics analysis for nitrogen asphyxiation accident generated by defect of building structural between diffusion outlet and cooling tower was performed to determine the inflow path of the suffocation gas, death possibility by concentration of suffocation gas and predicted the time of death due to the accident using 3D modeling and FLACS program. We can quantify diffusion concentration of asphyxiation gas and predict mechanism of death occurrence by accident and evaluate the consequence Analysis through this study. In the future, This method can be widely used in the field of gas safety by improving the reliability and validity of the analysis.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2017.11a
• /
• pp.8-10
• /
• 2017

최근 빈번한 항해 사고에 대응하여 항해 안전에 대한 관심이 높아지고 있으며 특히 항해중인 선박의 안전 항해에 대한 육상 감시기술 개발에 많은 노력이 기울려 지고 있다. 이러한 육상용 항해안전 감시시스템은 항만 교통 번잡도에 따른 조종 위험성 평가 기능 및 해양기상에 따른 선박 안전성능 평가 기능 등으로 구성되며, 선박 안전성능 평가를 위하여 선박에서 전송되는 AIS정보를 운항정보로 변환하여 구축된 선박별 동특성 정보와 연결한 후 안전성능지수를 도출하는 기술 구현이 필요하다. 본 연구에서는 이러한 항해안전 감시시스템 개발을 위하여 환경 요인에 의한 항해중 선박의 위험 요소를 분석, 항해안전 평가 모델을 개발한 후 개발된 평가 모델에 대한 평가 기준을 제시하였고 각 평가 모델의 결과를 정량적 지수형태로 도출하여 안전항해 감시시스템의 정량적 평가 기능을 지원하였다.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.8
• /
• pp.807-813
• /
• 2011

High precision of planning in the preoperative phase can contribute to increase operational safety during computer-aided spinal fusion surgery, which requires extreme caution on the part of the surgeon, due to the complexity and delicacy of the procedure. In this paper, an advanced preoperative planning framework for spinal fusion is presented. The framework is based on spinal pedicle data obtained from CT (Computed Tomography) images, and provides optimal insertion trajectories and pedicle screw sizes. The proposed approach begins with safety margin estimation for each potential insertion trajectory that passes through the pedicle volume, followed by procedures to collect a set of insertion trajectories that satisfy operation safety objectives. The radius of a pedicle screw was chosen as 70% of the pedicle radius. This framework has been tested on 68 spinal pedicles of 8 patients requiring spinal fusion. It was successfully applied, resulting in an average success rate of 100% and a final safety margin of $2.44{\pm}0.51mm$.