• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.23-29
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• 2001

Three-dimensional flow through a tubular centrifugal fan with airfoil type blades are analyzed using CFX-TASCflow. Standard k - $\epsilon$ model and k - $\omega$ model are used as turbulence closures. The numerical schemes for convetion terms, i.e., Upwind Differencing Scheme(UDS), Mass Weighted Skewed Upstream Differencing Scheme(MWS), Linear Profile Skewed Upstream Differencing Scheme(LPS), and Modified Linear Profile Skewed Upstream Differencing Scheme(MLPS) are also tested. And, the performance of these schemes coupled with two turbulence models are evaluated. Computational static pressure distributions are compared with experimental data obtained in this work.

• Communications for Statistical Applications and Methods
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• v.29 no.3
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• pp.333-351
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• 2022

The skew-t distribution is an attractive family of asymmetrical heavy-tailed densities that includes the normal, skew-normal and Student's-t distributions as special cases. In this work, we propose an EM-type algorithm for computing the maximum likelihood estimates for skew-t linear regression models with censored response. In contrast with previous proposals, this algorithm uses analytical expressions at the E-step, as opposed to Monte Carlo simulations. These expressions rely on formulas for the mean and variance of a truncated skew-t distribution, and can be computed using the R library MomTrunc. The standard errors, the prediction of unobserved values of the response and the log-likelihood function are obtained as a by-product. The proposed methodology is illustrated through the analyses of simulated and a real data application on Letter-Name Fluency test in Peruvian students.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.42-53
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• 2011

This study is to present a method of compiling consistently accurate construction cost estimates in minimum of time. There are two kind of applications for estimating system based on quantity-per-unit and the daily work-crew. The former system is still applied 45% as a estimating method to construction job site by the second half of 2010. However, it is necessary for quantity-per-unit to complement the defect of standard integrating specification and improve the integrating method to the various construction conditions. The later system is intended to represent a standard or basic core which can be adopted in many type of construction estimating used across the wide variety of construction in advanced countries. In this study daily work-crew based on productivity is applied to the representative B.O.Q Item in road project. These results are compared to productivity of Japan and U.S.A estimated under the similar circumstances.

• Journal of the Korean Society of Safety
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• v.35 no.5
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• pp.1-8
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• 2020

Mobile elevating work platforms (MEWPs) consist of a work platform, extending structure, and chassis, and are used to move persons to working positions. MEWPs are useful but are composed of pieces of equipment, and accidents do occur owing to equipment defects. Among these defects, accidents caused by the fracture of bolts fixed to the extension structure and swing system are increasing. This paper presents a failure analysis of the fixing bolts of MEWP. Standard procedure for failure analysis was employed in this investigation. Visual inspection, chemical analysis, tensile strength measurement, microstructural characterization, fractography analysis by Optical Microscope(OM) and Scanning Electron Microscopy(SEM), and finite element analysis (FEA) were used to analyze the failure of the fixing bolts. Using this failure analysis approach, we found the root cause of failure and proposed a means for solving this type of failure in the future. First, the chemical composition of the fixing bolt is obtained by a spectroscopy chemical analysis method, which determined that the chemical composition matched the required standard. The tensile test showed that the tensile and yield strengths were within the required capacity. The stress analysis was carried out at five different boom angles, and it was determined that the fixing bolt of MEWP can withstand the loads at all the boom angles. The outcomes of the fatigue analysis revealed that the fixing bolt fails before reaching the design requirements. The results of the fatigue analysis showed primarily that the failure of the fixing bolt was due to fatigue. A visual inspection of the fractured section of the fixing bolt also confirmed the fatigue failure. We propose a method to prevent failure of the fixing bolt of the MEWP from four different standpoints: the manufacturer, safety certification authority, safety inspection agency, and owner.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.159-166
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• 2009

On freeways, factors inducing traffic accidents consist of two major elements such as driver factors and road environment factors. Research have been done and shown that there would be relationship between design elements such as radius, slopes, superelevations, and observed speeds and accident rates. The present paper confirms that these elements are correlated with accident rates. Furthermore, the paper identifies standard deviation of these elements as the design consistency and compare them with reduction of accident rates. This type of work leads to identify the fact that standard deviations based design consistency are correlated with accident rates. The results of the paper may contribute to encourage the quantified use of design consistency during highway design.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.436-443
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• 1992

Presented in the paper is a systematic approach to constructing a Petri net model of FAS (flexible assembly system). Petri net is widely used in modeling automated manufacturing systems. But, it found to be very difficult for an FA engineer to build a correct model of an FAS with Petri net symbols (ie, place, transition, and token) from the beginning. An automated manufacturing system in general is built from a set of "standard" hardware components. An FAS in particular is usually composed of assembly robots, work tables, conveyor lines, buffer storages, part feeders, etc. In the proposed modeling scheme, each type of standard resources is represented as a standard "module" which is a sub Petri net. Then, the model of a FAS can be conveniently constructed using the predefined modules the same way the FAS itself is built from the standard components. The network representation of a FAS is termed a JR-net (job resource relation net) which is easy to construct. This JR net is then mechanically converted to a formal Petri net (to simulate the behavior of the FAS). The proposed modeling scheme may easily be extended to the modeling of other types of automated manufacturing systems such as FMS and AS/RS.ch as FMS and AS/RS.

• 한국환경농학회:학술대회논문집
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• 2009.07a
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• pp.240-272
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• 2009

Recently, as Foot and Mouth disease(FMD) outbreaks in South-East Asia, Taiwan, China, we cannot loose our tense to sustain our FMD free country status. And we have increasing possibility of disease inflow because of continual outbreaks of FMD type A, O and Asia 1 in neighbored countries, foreign visitor and foreign workers. So we have to be urgently ready for strengthen surveillance, early-report and early-diagnosis. So the most important things in epidemic control of livestock are co-work between central and local epidemic control office and field epidemic control. However, potential risk for FMD recurrence and sporadic occurrence of epidemic disease still threaten our livestock farmhouse, so we have to be ready for bio-security against these threatening. For these reasons, I will introduce the concept, etiology and epidemiology of disease and investment/ analysis of health management standard of main animals like cattle and pig which is applied to the inside and outside of country. With these references, we have to manage livestock health management thoroughly by establishing livestock health management standard and notifying special veterinarian and livestock farmer of these standard. Later on, prevention and quarantine of epidemic outbreak and establishing livestock health management standard should be undertaken primarily for sustainable growth and stability of livestock farm industry.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.269-278
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• 2007

Nighttime construction is being adopted by many state DOT's as a way to mitigate the impact of construction operations on the traveling public. Although a number of states have developed standard specifications for nighttime lighting, these standards are usually in the form of generic requirement statements that only specify minimum illuminance levels. The lighting standards do not include specific ways to achieve this illuminance level such as lighting arrangements and configurations for various work zone plans and construction operations. This leaves confusion between the traffic engineers and the contractors and does not guarantee consistency in those plans, thus affecting productivity and safety (lighting conditions account for 18% to 28% of work zone accidents). The main objective of this study is to utilize three dimensional animation and lighting analysis software to study and model lighting conditions of a construction site. This is expected to increase the safety and productivity of construction operations by achieving consistency in work zone lighting schemes. A computerized model was developed, called Nitelite. Various lighting schemes can be studied using the software to provide for typical applications including lighting fixture's locations, luminance, mounting height, tilt angle, and fixture type. The results from the developed software tool were validated through comparisons with previous research conducted using field measurements.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.360-362
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• 2008

Based on classification systems of power and IT standard dictionaries, scientific and technological standard, SPARK, power IT fields of IEC and organization units of corporations, we propose a new classification system for the standardization of power of terminologies. The classification system consists of a hierarchical structure with general classification, application fields and specific technologies while keeping the conventional matrix-type classification system. Interpretation work of the power of terminologies confirms that the proposed classification system is efficient.

• Journal of the Korean Society of Safety
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• v.21 no.5 s.77
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• pp.77-83
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• 2006

The purpose of this study is to assess the organizational personality types, employee-organization fits and the job satisfaction/involvement in a Korea standard nuclear power plant(NPP), which is a representative safety work place. First we chose 427 procedures that are related to safety out of 777 officially managed procedures referenced by 13.5 of FSAR(final safety analysis report). Next, we finally chose 70 procedures of 8 divisions for 44 employees regarding the duties for NPPs' division, experiences of operations, an operational know-how, and the indication of operational weakness. This study used OPTI(organizational personality type indicators) and the combination of 4 preference types for determining the organizational personality to produce personality types of organizations for NPPs' division. To assess the job satisfaction and involvement, we used a questionnaire and an interview, for 300 employees(83.5%) of the Korea standard NPP.