• 한국안전학회지
• /
• 제37권2호
• /
• pp.76-87
• /
• 2022

Lithium-ion batteries (LIBs) have attracted much interest for their high energy density (>150 mAh/g), high capacity, low self-discharge rate, and high coulombic efficiency. However, with the successful commercialization of LIBs, fire and explosion incidents are likely to increase. The thermal runaway is known as the major factor in battery-related accidents that can lead to a series of critical conditions. Considering this, recent studies have shown an increased interest in countering the safety issues associated with LIBs. Although safety standards for LIB use have recently been formulated, little attention has been paid to the safety around the manufacturing process for battery products. The present study introduces a risk assessment method suitable for assessing the safety of the LIB-manufacturing process. In the assessment method, a compensation parameter (Z-factor) is employed to correctly evaluate the process's safety on the basis of the type of material (e.g., metal anode, liquid electrolyte, solid-state electrolytes) utilized in a cell. The proposed method has been applied to an 18650 cell-manufacturing process, and three sub-processes have been identified as possibly vulnerable parts (risk index: >4). This study offers some crucial insights into the establishment of safety standards for battery-manufacturing processes.

• 소음진동
• /
• 제9권5호
• /
• pp.991-997
• /
• 1999

It is getting higher the demand on a good sound in a car. Like some other sensory qualities, achieving a good sound is still treated as a black-box followed by the individual taste of tuning engineers. This study aims to define the attributes of a good car audio sound and the assessment factors affecting the sound quality. With a variety of surveys on professional listening groups and car audio installers, 26 most frequently used vocabularies are selected as typical presentations of car audio sound quality. After repetitions of listening tests with deliberately selected test CD, pre-recorded 15 different digital car-recordings, headphones replay system, and three different listening groups, it is proved that there are at least 5 different assessment factors which significantly affect the car audio sound quality. They are high fidelity, spectral balance, tonal accuracy, sound stage and acoustic fault.

• 국제강구조저널
• /
• 제18권4호
• /
• pp.1242-1251
• /
• 2018

Not all loads contribute to fatigue crack propagation in the welded detail of steel bridges when they are subjected to variable amplitude loading. For fatigue assessment, therefore, non-contributing stress cycles should be truncated. However, stress range truncation is not considered during typical fatigue reliability assessment. When applying the first order reliability method, stress range truncation occurs mismatch between the expected number of cycles to failure and the number of cycles obtained at the time of evaluation, because the expected number of cycles only counts the stress cycles that contribute to fatigue crack growth. Herein, we introduce a calibration factor to coordinate the expected number of cycles to failure to the equivalent value which includes both contributing and non-contributing stress cycles. The effectiveness of stress range truncation and the proposed calibration factor was validated via case studies.

• 국제학술발표논문집
• /
• The 3th International Conference on Construction Engineering and Project Management
• /
• pp.1231-1236
• /
• 2009

Many work-related risk factors can cause construction site hazards. Therefore, safety management begins with measuring the magnitude of risk involved in a project. This study proposes a methodology for risk assessment of major trades at a particular construction site. To assess risk, this methodology integrates hazard severity and frequency, and their magnitude is calculated based on actual work-site hazards. This methodology also considers the influence factors that affect the frequency of work-related hazards. To select the appropriate influence factors, a two step approach is deployed. First, the predominant factors are identified through a literature review. Second, a selective process filters out the influence factors that are difficult to analyze quantitatively, and these extracted factors are weighted using expert surveys. Finally, the factors are combined and a quantitative risk assessment methodology is proposed.

• Earthquakes and Structures
• /
• 제20권4호
• /
• pp.389-403
• /
• 2021

Skewed bridges, being irregular structures with complicated dynamic behavior, are more susceptible to earthquake damage. Reliable seismic-resistant design of skewed bridges can be achieved by accurate determination of nonlinear seismic demands. However, the effect of geometric characteristics on the response modification factor (R-factor) is not accounted for in bridge design practices. This study attempts to investigate the effects of changes in the number of spans, skew angle and bearing stiffness on R-factor values and to assess the seismic fragility of skewed bridges. Results indicated that changes in the skew angle had no significant effect on R-factor values which were in consonance with code-prescribed R values. Also, unlike the increase in the number of spans that resulted in a decrease in the R-factor, the increase in bearing stiffness led to higher R-factor values. Findings of the fragility analysis implied that although the increase in the number of spans, as well as the increase in the skew angle, led to a higher failure probability, greater values of bearing stiffness reduced the collapse probability. For practicing design engineers, it is recommended that maximum demands on substructure elements to be calculated when the excitation angle is applied along the principal axes of skewed bridges.

• 환경영향평가
• /
• 제20권3호
• /
• pp.313-324
• /
• 2011

The purpose of this study is to present the raw data for establishing the plan of top soil conservation in soil environment and preventing the soil loss by establishing the potential amount of soil loss using RUSLE. The results are as follows. To apply the RUSLE model, we calculated the potential amount of soil loss by using 5 factors; rainfall erosion factor(R), topographical factor(LS), soil erosion factor(K), land cover factor(C) and erosion control factor(P). The assessment map of soil loss was drawn up by classifying 5 grades. According to the soil loss estimation by the RUSLE, it showed that approximately 83.9% of the study area had relatively lower possibility of soil loss which was the 1 ton/ha in annual soil loss. Whereas, the 7.0% of the study area was defined as high risk area which was the 10 ton/ha in annual. Therefore, this area was needed that there was environment-friendly construction of farm land, improvement of cultivation environment and so forth. In future, if we will analyze the amount of soil loss of Gyeongju national park and Hyeongsan river watershed, we will offer the help to establishing the conservation plan of soil environment in Gyeongsangbuk-do.

• Journal of Welding and Joining
• /
• 제35권1호
• /
• pp.55-60
• /
• 2017

There are many Industry Code and Standard (ICS) for Structural Integrity Assessment (SIA) on welded structure with defect. The general ICSs, such as R6, BS 7910 and API 579-1/ASME FFS-1, provide equations to determine the upper bound residual stress profiles based on collections from many literatures. However, these residual stress profiles used in the SIA cause the conservative design for welded structures. In this study, the structural integrity assessment for girth weld in pipeline has been conducted based on fracture mechanics. In addition, thermo-elastic plastic FE analysis was performed for evaluating the residual stress of girth weld in pipeline. The weight function solution is used to determine the stress intensity factor using the residual stress profile obtained by the FE analysis. This approach can account for redistribution and relaxation of residual stress as the defects grow. In order to the evaluate quantitative comparison between BS 7910 and weight function solution, structural integrity assessment determining allowable crack size on cracked pipe was performed with failure assessment diagram.

• 한국환경보건학회지
• /
• 제48권5호
• /
• pp.266-271
• /
• 2022

Background: The selection of distributions of input parameters is an important component in probabilistic exposure assessment. Goodness-of-fit (GOF) methods are used to determine the distribution of exposure factors. However, there are no clear guidelines for choosing an appropriate GOF method. Objectives: The outcomes of probabilistic consumer exposure assessment were compared by using five different GOF methods for the selection of input distributions: chi-squared test, Kolmogorov-Smirnov test (K-S), Anderson-Darling test (A-D), Akaike information criterion (AIC) and Bayesian information criterion (BIC). Methods: Individual exposures were estimated based on product usage factor combinations from 10,000 respondents. The distribution of individual exposure was considered as the true value of population exposures. Results: Among the five GOF methods, probabilistic exposure distributions using the A-D and K-S methods were similar to individual exposure estimations. Comparing the 95th percentiles of the probabilistic distributions and the individual estimations for 10 CPs, there were 0.73 to 1.92 times differences for the A-D method, and 0.73 to 1.60 times differences (excluding tire-shine spray) for the K-S method. Conclusions: There were significant differences in exposure assessment results among the selection of the GOF methods. Therefore, the GOF methods for probabilistic consumer exposure assessment should be carefully selected.

• 디지털융복합연구
• /
• 제12권2호
• /
• pp.119-128
• /
• 2014

본 연구는 비행청소년을 대상으로 재비행위험성 정도에 가장 영향을 미치는 요인은 무엇인지 알아보고, 이 요인들을 설명하는 심리적인 특성을 찾아보고자 하였다. 피험자는 서울시 ${\bigcirc}{\bigcirc}$경찰청에서 비행행동으로 비행행동촉발 조사서와 PAI 검사를 받은 268명이었으며, 남자 220명, 여자 48명이었다. 비행 촉발요인에 대한 재비행 위험성 집단간 차이는 가족구조를 제외한 5가지 요인, 즉 가족기능, 학교생활, 가출경험, 비행전력, 개인경험에서 차이가 있었다. 재비행 위험성 집단 간 PAI 검사 결과는 신체호소, 우울, 망상, 정신분열, 경계선, 반사회성, 음주문제, 약물사용의 임상척도와 공격성, 자살관념, 스트레스 비지지의 치료고려 척도, 그리고 지배성과 온정정의 대인관계 척도에서 집단간 차이가 있었다. 비행촉발요인과의 PAI 척도의 관련성에서는 대부분의 척도에서 유의미한 상관이 있었으며, 특히 우울은 모든 비행촉발요인과 상관이 나타났다. 비행촉발 요인 중 가족구조에 대한 설명력은 스트레스와 온정성이, 가족기능에서는 비지지와 음주문제가, 학교생활에서는 음주문제와 우울이, 가출경험에서는 음주문제와 스트레스가, 비행전력에 대해서는 음주문제가, 그리고 개인경험에 대해서는 음주문제와 지배성, 경계선이 설명력을 가졌다. 전체적으로 보면, 재비행위험성 정도에 따라, 음주문제, 우울, 그리고 대인관계관련 척도가 비행촉발요인을 설명하였다. 비행의 원인으로 다양한 입장들이 있고, 개입요인들도 그에 따라 달라지지만, 비행청소년의 심리적인 측면에 대한 개입을 통해 비행행동의 재발을 예방하는 데 효과가 있을 것으로 사료된다.

• Architectural research
• /
• 제16권4호
• /
• pp.131-137
• /
• 2014

Recently, the development of sustainable building assessment tools as means to invigorate the dissemination of sustainable buildings has been actively progressed. However, many assessment tools involve various problems in terms of assessment method and system framework, which greatly impede their credibility and applicability. If these problems persist over time, the role of sustainable building assessment tools as decision making measures during the design stage will be greatly limited. The objective of the study is to suggest a systematic model for sus- tainable building assessment tools by establishing a logical system of performance assessment framework. For this purpose, the Environmen- tal Impact Assessment(EIA) framework used in selected and modified to fit the building performance assessment. The analysis of performance assessment tools for sustainable buildings was conducted using the EIA framework. Based on the results of the analysis, a framework for the performance assessment of sustainable buildings was established.