• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.498-507
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• 2017

Electronic equipments comprised of high density components with various packaging types have been recently applied to a satellite. Therefore, to guarantee high reliability of electrical equipment, a design approach, which can reduce the development period and cost through an early diagnosis in potential risks of failure, should be established. In the previous research, the reliability assesment of the electronic equipments have based on Steinberg's fatigue failure theory. However, this theory was not enough for further investigation of life prediction and reliability of the electronic equipments comprised of various sizes and packaging types due to its theoretical limitations and analysis results sensitivity with regard to different modeling technic. In that case, if detailed finite element model is established, aforementioned problems can be readily solved. However, this approach might arise disadvantage of spending much time. In this paper, to establish strategy for high reliability design of electronic equipment, we performed mechanical reliability evaluation of CCB (Camera Controller Box) at qualification level based on the approach using Sherlock unlike design techniques applied to existing business.

• Journal of Welding and Joining
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• v.30 no.2
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• pp.59-64
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• 2012

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body are spot welding and $CO_2$ welding are used in a small part. In production field, $CO_2$ welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in $CO_2$ welding process frequently. But $CO_2$ welding process should be used at robot interference parts and closed parts where spot welding couldn't. Because of the 0.65mm ~ 2.0mm thickness steel sheet were used in the automotive industry, poor quality of welding area such as burn through and under fill were happened frequently in $CO_2$ process. In this paper, we will study about the penetration depth which gives a huge impact on burn through changing a degree of base metal, welding position and torch angle. Voltage, current and welding speed were fixed but degree of base metal, welding position and torch angle were changed. And Cold- Rolled(CR) steel sheet was used. Penetration depth was analysed by multiple regression analysis to derive approximate calculations. And reliability of approximate calculations were confirmed through additional experiments. As the results of this research, we confirmed the effect of torch and plate angle to bead shape. And we present a possibility that can simulate more accurate to weld geometry, as deduced the verification equations that has tolerance of less than 21.69%.

• Journal of Korea Water Resources Association
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• v.52 no.12
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• pp.985-999
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• 2019

Over the last decade, droughts have become more severe and frequent in many regions, and several studies have been conducted to explore the recent drought. Copula-based bivariate drought frequency analysis has been widely used to evaluate drought risk in the context of point frequency analysis. However, the relatively significant uncertainties in the parameters are problematic when available data are limited. For this reason, the primary purpose of this study is to develop a regional drought frequency model based on the Copula function. All parameters, including marginal and copula functions in the regional frequency model, were estimated simultaneously. Here, we present a case study of recent drought 2013-2015 over the Han-River watershed where severe drought risk is consistently found to increase. The proposed model provided a reliable way to significantly reduce the uncertainty of parameters with a Bayesian modeling framework. The uncertainty of the joint return period in the regional frequency analysis is nearly three times lower than that of the point frequency analysis. Accordingly, DIC values in the regional frequency analysis model are significantly decreased by 15. The results confirm that the proposed model is not only reliably representing characteristics of historical droughts and dependencies between drought variables, but also providing the efficacy of understanding regional drought characteristics.

• The Journal of the Korean bone and joint tumor society
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• v.14 no.2
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• pp.106-118
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• 2008

Purpose: Disturbed cell cycle regulatory proteins are key events underlying the development and/or progression of human malignancies. The aim of this study is to evaluate the protein expression status involved in G1/S cell cycle in human soft tissue sarcoma. Materials and Methods: We simultaneously evaluated the expression of Cyclin D1, Cyclin E, CDK4, CDK2, p16, p27, Rb, E2F1, p53 and Ki-67 by immunohistochemistry in 43 cases of soft tissue sarcoma Results: The Cyclin D1, Cyclin E, CDK4, CDK2, E2F1, and p53 were expressed in 25 (58.1%), 18 (41.9%), 13 (30.2%), 33 (76.7%), 20 (46.5%), and 18 cases (41.9%). The p16, p27, and Rb expressions were decreased in 26 (60.5%), 22 (51.2%) and 19 cases (44.2%). All of the cases showed alterations of more than one out of the above proteins. The increased Cyclin E expression and Ki-67 labeling index (LI) were significantly associated with histologic grade. The Cyclin E and E2F-1 expressions were increased in relapsed cases and the CDK4 expression was increased in cases of metastasis. Conclusion: Alterations of G1/S cell cycle regulatory proteins may play an important role in the tumoriogensis of soft tissue sarcomas. Our results suggest that increased expressions of Cyclin E, E2F1, and CDK4 were associated with tumor relapse or metastasis and could be considered as parameters of prognosis of soft tissue sarcoma.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.131-138
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• 2006

Methods of back calculation for either design procedures or elastic moduli obtained from FWD(Falling Weight Deflectometer) tests have widely been used to predict remaining life of airfield concrete pavements. Since the variation of the elastic modulus obtained from the FWD test depends on the back calculation methods, prediction of remaining life of airfield pavement using the back calculation method has not been reliable. In addition, the FWD method only concentrates on the structural integrity of the pavement without considering functional distress. In this study, a newly developed remaining life estimation procedure is proposed. This methodology includes both structural and functional consideration and suggests models and decision criteria for each stage. In order to improve the estimation procedure on remaining life of pavement, conducted the several tests on an old airfield concrete pavement. As a result, it is concluded that the load transfer efficiency on joint is better for predicting remaining life of pavement than the elastic modulus, which is commonly used. In order to verify applicability of the newly developed estimation procedure and detailed models, investigation and analysis were conducted according to the new methodology on C-airfield pavement. Finally, it is confirmed that the efficiency of the proposed method for practical application was good enough.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.1-8
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• 2008

We propose how to program the off-line buffing robot path along shoes' outsole shape in the footwear buffing process by a 5-axis microscribe system like robot mechanism. The microscribe system we developed consists of a 5-axis robot link with a turn table, a signal processing unit, PC and an application software program. Itmakes a robot path on the shoes' upper in accordance with the movement of a microscribe with many joints. The developed system calculates the encoder pulse values for the microscribe arm's rotation and transmits the angle pulse values to the PC through a processing unit. Denavit-Hartenberg's(D-H) direct kinematics is used to make the global coordinate from microscribe joint one. Problems with the microscribe's kinematics can be solved efficiently and systematically by D-H representation. With the coordinate values calculated by D-H equation, our system can draw a buffing gauge-line on the upper sole. We obtain shoes' outline points, which are 2 outlines coupled with the points and the normal vector based on the points. By applying the system to the buffing robot in a flexible manufacturing system, it can be used effectively to program the path of a real buffing robot.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1147-1155
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• 2014

Biomechanical models are often used to predict muscle and joint forces in the human body. For estimation of muscle forces, the body and muscle properties have to be known. However, these properties are difficult to measure and differ from person to person. Therefore, it is necessary to predict the change in muscle forces depending on the body and muscle properties. The objective of the present study is to develop a numerical procedure for estimating the muscle forces in the human lower extremity under uncertainty of body and muscle properties during rising motion from a seated position. The human lower extremity is idealized as a multibody system in which eight Hill-type muscle force models are employed. Each model has four degrees of freedom and is constrained in the sagittal plane. The eight muscle forces are determined by minimizing the metabolic energy consumption during the rising motion. Uncertainty analysis is performed using a first-order reliability method. The one-standard-deviation range of agonistic muscle forces is calculated to be about 150-300 N.

• Journal of Preventive Medicine and Public Health
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• v.39 no.3
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• pp.229-234
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• 2006

Objectives: Cardiovascular disease is one of the main causes of death and morbidity in Korea. In this study, the prevalence and incidence of developing hypertension in a male-workers' cohort were investigated during 3-years follow-up with a view to find the risk factors that affected the development of hypertension. Methods: Among the 5,374 people who participated in a routine health check up, 3,852 people with normal blood pressure and who had no history of hypertension were prospectively followed up for 3 years. The classification of hypertension was based on the JNC7 report (the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure). Life style factors and underlying diseases that were related to the risk factors of hypertension were collected by using a self-report questionnaires via the internet. Results: The prevalence of hypertension was 28.3% (1,520/5,374) at the first screening (2001). It was found that the incidence in 2004 of hypertension for the follow-up subjects (3,711) who had normal blood pressure in 2001 was 7.6 per 100 person-year. Multiple logistic regression analysis of the variables related to the risk factors of hypertension was carried out. The relative risks were 1.037 (95% CI=1.022-1.053) as the age increased 1 year and 1.039 (95% CI=1.023-1.055) as the body mass index increased $1kg/m^2$. The relative risk for the prehypertensive group was 2.501 (95% CI=1.986-3.149) compared to the normotensive group. These results showed that age, body mass index and the baseline blood pressure were significantly related to the incidence of hypertension. Conclusions: The incidence of hypertension was 7.6 per 100 person-year during follow-up. It was concluded that the risk factors for developing hypertension in the short-term were age, BMI, and prehypertension; Especially, this showed that it is necessary for prehypertensives to manage their body weight and blood pressure to prevent hypertension in middle-age by modifying their life style.

• Journal of Technology Innovation
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• v.23 no.3
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• pp.201-223
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• 2015

Existing research on international standardization has largely taken a qualitative approach focusing on comparative studies of national institutions and policies on standards or international rivalries from the perspectives of international relations or innovation studies. While there exists a handful of quantitative studies, they are mostly confined to simple numeric counts of essential patents, new work item proposals, or secretaries staffing international standards development organizations (SDOs). This study aims to contribute to our understanding of the dynamics of international standardization by the analysis of the data coding systematically national activities in the standardization process of the International Organization for Standardization (ISO), by far the largest international SDO. Our analysis of the four critical types of standardization documents generated in the Working Group 7 of the ISO/IEC Joint Technical Committee 1 reveals interesting dynamics among key players of global ICT standards regime. First, while the US takes a dominant share of the personnel as well as new work item proposals for standardization, its quality of activities rather falls behind as it mostly focuses on keeping in check other countries' standardization activities. Second, European countries tend to spread their effort evenly across different types of standardization activities. Finally, despite such differences between the US and European countries, both rely heavily on multinational companies to gain an advantage in the voting stage of standardization process.

• Journal of Conservation Science
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• v.20
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• pp.89-103
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• 2007

The bedrock beneath the Chokseongnu pavilion consists of sandstone with alternate dark-gray to light-brown siltstone and dark-gray shale of the Jinju Formation, where bedding is well developed toward the Chokseongmun gate. Large to small joints and overbreak from the erosion weathering have been developed in the bedrock. Besides, water leakage from development of discontinuity planes, fragmentation of shale, crack and joint by tree roots are observed on the bedrock. While shale and siltstone showed high sensitivity in physical and chemical weathering, respectively, sandstone indicated the highest weathering sensitivity in both. As the results of structural stability analysis, the whole bedrock has high instability in wedge failures, and especially section No. II slope is more instable than section No. I. Therefore, it is necessary for the bedrock to be strengthened by improvement method for soft foundations and the surface reinforcement. The trees causing mechanical collapse of the bedrock should be also removed and a water flow prevention measure or a water exhaust are required.