• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집A
• /
• pp.13-18
• /
• 2000

Nowadays, 60 percent of thermal power plants already have been operated over their own design life. These operations of old power plant over their design life have caused a fracture accident of degradation a loss of economic and human. Therefore, the new life assessment and prediction technology is necessary to improve the safety and reliability of high pressure and high temperature power plant facilities. In this paper, innovative electrochemical test method have been used and results have been compared to the conventional test. Finally, the electrochemical test is applied to the in-field HP turbine and a database is currently in progress for the development of the life assessment standard and procedure.

• Journal of the Korean Wood Science and Technology
• /
• 제24권2호
• /
• pp.1-6
• /
• 1996

This study was performed to investigate the feasibility of using sonic stress-wave technique in the longitudinal direction for the assessment of incipient decay of radiata pine wood. Decayed bending specimens by Tyromyces palustris and Gloeophyllum trabeum for varoious periods were tested nondestructively using stress-wave technique in the longitudinal direction and destructively. Decay detection, quantitative assessment of decay, and the prediction of residual strength of decayed wood with less than five percent weight loss can be feasible using stress-wave parameters (wave velocity, wave impedance, stress-wave elasticity) measured by stress-wave technique in the longitudinal direction and their percent reduction due to decay.

• 대한안전경영과학회지
• /
• 제14권3호
• /
• pp.39-48
• /
• 2012

Risk Assessment to list possible safety disasters and their probability and severity is the starting point for effective safety management on construction project site. However, the safety managers in owners, construction supervisors, contractors, and sub-contractors still have difficulties in judging the priorities of safety activities and preparing responses to each potential safety disasters. Therefore, this study aimed to suggest a systematic method in assessing safety risk prior to commencement with the agreement of stakeholders. FMECA(failure mode effects and criticality analysis) was selected as a main assessment tool and it was modified according to the characteristics of construction projects and trades. Each risk is, firstly, evaluated with occurrence probability, possible loss and impacts to projects, and detections, and then risk priority number(RPN) is calculated. Subsequently, the managers of each stakeholder discuss the types, timing, and responsibilities of responses as a group decision-making process.

• Journal of Periodontal and Implant Science
• /
• 제38권1호
• /
• pp.15-22
• /
• 2008

Purpose: The attachment level is strongly associated with tooth loss and provides useful information on patterns of destruction of the periodontium. The presence of horizontal attachment loss would not be detected in clinical measurement. Therefore, the purpose of the present study was to estimate the patterns of periodontal destruction based on the attachment area and horizontal attachment loss in extracted teeth due to severe periodontitis. Materials and Methods: 307 teeth satisfied the criteria for assessment. An indirect method, based on digital images obtained from a digital camera and an image analysis program, was used to calculate the area of root surface and attachment loss and the extent of horizontal attachment loss. The data were analysed using SPSS. Results: No statistically significant differences among root surfaces were observed in anterior teeth on the loss of attachment area. However, in posterior teeth statistically significant differences in palatal surfaces of maxillary and mandibular premolar and molar surfaces compared with buccal surfaces were observed. Horizontal attachment loss was observed in 21.5% of the teeth examined. Frequency of horizontal attachment loss was highest in the maxillary first premolar (34.8%), followed by the maxillary second premolar (27.3%) and maxillary canine (25%). The mean length of horizontal attachment loss was 1.5mm. Conclusion: More meticulous examination will be needed of the palatal surfaces of maxillary and mandibular premolar and molar teeth. The percentage of teeth with horizontal attachment loss greater than 2.1 mm was 5.2%. Considering the length of curette blades, about 5.2% of teeth were not properly debrided. Therefore, Additional supportive therapy such as local drug delivery has to be considered in treatment of the first maxillary, second premolar and canine due to the high prevalence of horizontal attachment loss.

• 한국토양비료학회지
• /
• 제47권2호
• /
• pp.71-79
• /
• 2014

Climate change has been social and environmental issues, it typically indicates the trend changes of not only temperature but also rainfall. There is a need to consider climate changes in a long-term soil erosion estimation since soil loss in a watershed can be varied by the changes of rainfall intensity and frequency of torrential rainfall. The impacts of rainfall trend changes on soil loss, one of climate changes, were estimated using Sediment Assessment Tool for Effective Erosion Control (SATEEC) employing L module with current climate scenario and future climate scenario collected from the Korea Meteorological Administration. A 62 $km^2$ watershed was selected to explore the climate changes on soil loss. SATEEC provided an increasing trend of soil loss with the climate change scenarios, which were 182 ton/ha/year in 2010s, 169 ton/ha/year in 2020s, 192 ton/ha/year in 2030s,182 ton/ha/year in 2040s, and 218 ton/ha/year in 2050s. Moreover, it was found that approximately 90% of agricultural area in the watershed displayed the soil loss of 50 ton/ha/year which is exceeding the allow able soil loss regulation by the Ministry of Environment.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.430-431
• /
• 2011

Recently the power system consists of the more complicated structure, due to increase of power demands. In this circumstance, the congestion and loss capacity in transmission line is also increased. Accordingly, the investment planning of transmission system is required to reduce the congestion and loss of the transmission line. In study of the planning of domestic and international transmission expansion, the reliability of transmission planning and minimizing Investment cost is focused. However, the study has not been performed systematically in economic aspects. Typically, the congestion and loss costs have been individually calculated. It is not consider the mutual relationship between the congestion cost and the loss cost. This paper proposes a method to compute concurrently the congestion and loss costs. This purpose is to calculate the more exact value for economic assessment of the power system operation.

• Geomechanics and Engineering
• /
• 제37권6호
• /
• pp.565-576
• /
• 2024

In this study, the earthquake risk assessment of single-story RC precast buildings in Turkey was carried out using loss curves. In this regard, Kocaeli, a seismically active city in the Marmara region, and this building class, which is preferred intensively, were considered. Quality and period parameters were defined based on structural and geometric properties. Depending on these parameters, nine main sub-classes were defined to represent the building stock in the region. First, considering the mean fragility curves and four different central damage ratio models, vulnerability curves for each sub-class were computed as a function of spectral acceleration. Then, probabilistic seismic hazard analyses were performed for stiff and soft soil conditions for different earthquake probabilities of exceedance in 50 years. In the last step, 90 loss curves were derived based on vulnerability and hazard results. Within the scope of the study, the comparative parametric evaluations for three different earthquake intensity levels showed that the structural damage ratio values for nine sub-classes changed significantly. In addition, the quality parameter was found to be more effective on a structure's damage state than the period parameter. It is evident that since loss curves allow direct loss ratio calculation for any hazard level without needing seismic hazard and damage analysis, they are considered essential tools in rapid earthquake risk estimation and mitigation initiatives.

• 터널과지하공간
• /
• 제30권2호
• /
• pp.149-163
• /
• 2020

본 연구에서는 지리정보시스템 환경에서 지하매설물 정보를 이용하여 토립자 유실을 고려한 도시 지반 함몰 취약성을 평가하였다. 지하 환경에서 물의 흐름이나 지하수위 변화에 의한 토립자 유실은 지하공동의 발생과 확장을 유도하고, 이는 지반함몰 발생에 직접적인 원인이 된다. 토립자 유실은 지하 환경에 따라 그 정도가 달라질 수 있기 때문에 본 연구에서는 지하매설물 2종(상수도 관망, 하수관로)과 지하철 선로 권역별로 지반함몰에 영향을 주는 인자를 각각 4개씩 선정하였다. 로지스틱 회귀분석 기법을 이용하여 지하매설물 및 지하철 선로 권역 별로 지반함몰 이력과 영향인자 간의 상관성을 분석하고 회귀식을 도출하였으며, 이를 토대로 3개의 지반함몰 취약성 지도를 작성하였다. 본 연구 결과는 도시 지반함몰 위험 예·경보 시스템 구축을 위한 지반함몰 고위험지역 및 지반 안전 상시 모니터링 지역 선정 근거에 대한 기초 자료를 제공할 수 있을 것으로 기대한다.

• 한국CDE학회논문집
• /
• 제22권2호
• /
• pp.141-149
• /
• 2017

Vulnerability assesses the loss of major performance functions of GCV (Ground Combat Vehicles) when it is hit by enemy's shell. To decide the loss of major functions, it is determined what effects are on the performance of GCV when some components of GCV are failed. M&S (Modeling and Simulation) technology is used to vulnerability assessment. The hydro-pneumatic suspension is used as a sample part. The procedures of vulnerability assessment of the hydro-pneumatic suspension are shown as follows: 1) The components of the suspension are defined, and shot lines are generated evenly around the part. 2) The penetrated components are checked by using the penetration equation. 3) The function model of the suspension is designed by using IDEF0. 4) When the failure of the critical components of the suspension happens, its effect on the function of the suspension can be estimated using DMEA (Damage Mode and Effects Analysis). 5) The diagram of FTA (Fault Tree Analysis) is designed by exploiting DMEA. 6) The damage probability of the suspension is calculated by using FTA and vulnerable area method. In this paper, SLAP (Shot Line Analysis Program) which was developed based on COVART methodology. SLAP calculates the damage probability and visualizes the vulnerable areas of the suspension.

• 한국안전학회지
• /
• 제35권6호
• /
• pp.78-84
• /
• 2020

The F&EI technique is one of the risk assessments with many advantages. It can save time and effort compared to quantitative risk assessment (QRA). By using the evaluation result of this technique, it is possible to check the effectiveness of the investment cost. In addition, a relative risk ranking can be created and used to establish the facility management cycle and to prioritize investment. However, evaluating the target process can be evaluated more than the actual risk since the LCCF, a loss prevention measure, is too limited. In addition, calculating premiums via this method can result in excessive premiums, making it difficult to evaluate the risk precisely. Therefore, new safety guard was added to the LCCF of the F&EI risk assessment with reference to HAZOP and LOPA techniques. Newly added LCCFs are Deflagration arrester, Check valve, SIS, and Vacuum beaker, etc. As a case study, F&EI risk assessment was performed on Acetone storage tank of a API (Active pharmaceutical ingredient) plant to compare actual MPPD. The estimated loss amount was 592,558$ for the existing technique and 563,571$ for the improved technique, which was reduced by about 5% compared to the previous one.This proved that a more precise evaluation is possible and that the efforts for safety at the workplace are reflected in the evaluation results.