• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.51-57
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• 1985

In the design of civil engineering structures, the designers are invariably faced to the uncertainties and the randomness of the design parameters such as material properties and loads. Even when the structures are built, the actual geometries of the structures are also subject to their random variations from their nominal design values. Thus, the reliability of a structure in terms of these uncertainties and variations becomes a matter of great concern to the structural designers. This study employs the First Order Second Moment Method to evluate numerically the reliability of a simple tension member and discusses the influence on the final failure probability of that structure due to: 1) use of equivalent normal distribution in place of non-normal distribution, 2) linearization of non linear limit state equation. A discussion is also made on the necessity of fundamental studies on the distrubution characteristics of the strength of locally produced construction materials and those of the loads frequently encountered in the structural design.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.2
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• pp.52-57
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• 2001

ln this study, the questionnaire survey was performed to obtain the basic data on current situations and challengeable aspects of vermicomposting industries. The questionnaire contained the four main categories such as vermicomposting facilities, feeling marerials, earthworm breeding and cast handling. The results was summarized as followings: 1. Vermicomposting facilities area was becoming larger, and earthworm feed was also expending to various organic sludges. These trends showed that Vermicomposting is being enlightened to treat and recycle the organic wastes in Korea. 2. Present Vermicomposting technology needs the broad land. Because of the high cost of land in Korea, the land saving technology such as multistage must be needed. And present operation practices are mostly based on human power, mechanization and automation is needed. Also, present control practices are based on individual experience need the scientific base control system. 3. Considering situations of organic wastes management in Korea, the technical development and the practical improvement of Vermicomposting as the waste recycling will be needed.

• The Korean Journal of Applied Statistics
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• v.23 no.2
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• pp.295-304
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• 2010

Coating thickness is one of target variables in quality control process in steel industry. To predict coating thickness and to control quality of anti-fingerprint steel coils, ultraviolet-visible spectra are measured. We propose a variable-interval selection procedure based on the variable importance in projection in partial least square model. Using the proposed variable interval selection method, prediction performance gets better in the reduced model than the full model with full spectra absorbance. It is also shown that the first differencing as a data preprocessing technique does work well for the prediction of coating thickness.

• Journal of Korean Society for Quality Management
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• v.43 no.3
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• pp.273-288
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• 2015

Purpose: In this study, we apply environmental stress screening (ESS) to battle management system (BMS) of a tank and use the ESS profile based on production process data, guided by MIL-HDBK-781/344/2164. Methods: To optimize ESS Profile of the BMS of a tank, we estimate ESS model parameters (e.g., defect density, screening strength) using primary production failure reporting and corrective action system (FRACAS) data of military supply contract firm. Results: First, we collect the Primary production FRACAS data of military supply contract firm. Second, we compute curve fitting approach to find patent defect density and latent defect density using FRACAS data. Third, we solve the equation of Defect Density(patent defect density + latent defect density)($D_{IN}$) and Screening Strength(SS) Using second step data. As a result of analysis according to the order, we calculate $D_{IN}$(Temperature stress case : 74.02, Vibration stress : 10.252) and : SS(Temperature stress case : 0.4632, Vibration stress : 0.4142) and confirm the Condition II-D based on MIL-HDBK-344. According to Condition II-D, it is necessary to modify existing ESS profile through decreasing the $D_{IN}$ and increasing the SS. Conclusion: Identification of defect causes through ESS approach reduce defect densities for production. It provides feedback to a lessons-learned data base to avoid similar problems on next generation tank BMS.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.53-62
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• 2005

Efficient snow-removing work is one of important processes of winter road management. Calcium chloride has been used as a typical deicing agent in Korea. It presents superial performance as snow deicing agents, however it has been known to give serious environmental problem and to deteriorate durability of concrete structure in road by corrosion. The environment-friendly road deicing agents made from the waste material which is liquid phase organic matter that is Ca Mg and reactant of organic acid (nitric acid and propionic acid) have been introduced by number of researchers. They indicated the calcium magnesium salt of organic acids have advantage over the calcium choride in terms of lower production unit cost by resources recycling and can solve environmental problem and durability deterioration of structures. In this study, the deicing performance of calcium magnesium salt of organic acids(CMO) is investigated based on the series of experiments including the test for heat of dissolution, freezing point, ice melting test and ice penetration test.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.117-123
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• 2003

In succession to the previous paper, the tritium injection system and the regeneration system of the tritium handling system are presented. Both systems should be placed inside glove boxes since there can be potential leakage of tritium from these systems. The tritium injection system should be capable of measuring the exact amount of the injected tritium to keep track of the tritium inventory. The tritium injection system is designed to recover the remaining tritium from the system after injection for the minimization of tritum release to the environment as well as for the recovery of precious resource. TRS equipment such as MS, Ni catalyst bed, and metal getter are regenerated with a standalone regeneration system. Unlike other equipments which can be regenerated by heating and purging with appropriate gas, regeneration of the metal getter used to recover tritium is somewhat complicated.

• Journal of Engineering Education Research
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• v.3 no.2
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• pp.3-13
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• 2000

The paper has analyzed and summarized about the theoretical problem occurred in the CAQC, and has developed the learning model focused on the histogram as a case study. The range of study is to systematize the basic method of histogram generally used, and to make step by step procedures under the interactive relation with the improvement of the theory that must be added in case of the calculation by the aided of MS-Excel software. A histogram is the theory to understand the population distribution from which samples are extracted, so alternative methods are presented to estimate the population shape through an experiment and a practice. In order to enlarge the application area of the histogram in the factory, the theory of normal test, the criteria of process capability index and the probability calculation of PPM are added to the histogram. The learning model of CAQC education is proposed that is consistent with the target of histogram to control and search the cause of item defectives fast and correctly.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.147-155
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• 2008

The economics of most chemical plants are heavily dependent upon the management of the utilities used in the plants. The utilities are supplied by the centralized utility system of the plant. Among the various utilities the steam is by far the most important energy source and the management of the electricity and the process water are greatly affected by the steam. Therefore it is necessary to educate students and new employees the basic concepts about the effective distribution of the utilities and the fundamental strategies to apply the concepts in actual plant operations. The OOUS (Optimal Operation of Utility System) is an GUI educational system designed to educate the effective generation of the steam and the optimal steam distribution schemes within short period. The OOUS deals with various utility equipments and processes and shows how to save operation costs by displaying the optimal operation conditions based on the process models and the operational knowledgebase.

• The Journal of the Acoustical Society of Korea
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• v.22 no.5
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• pp.408-417
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• 2003

In this paper, we have studied the enhancement of the acoustic image by combining bases of support for SFR (Spatial Frequency Response) taken at multi-frequencies. The scanning acoustic microscope system have been constructed using the quadrature detector that is able to measure the amplitude and phase of the reflected signal simultaneously. Both real and quadrature components of reflected signal have been acquired at 4.4 ㎒ to 5.6 ㎒ reliably and accurately. In this experimental result, better depth resolution can be obtained by numerically combining images taken at several different frequencies. Image intensity have been better about 3.4 times at multi-frequency than one at a single frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.11
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• pp.2100-2106
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• 2016

The automation system uses PLC to monitor the manufacturing process status of the production product and processes the sensor information transmitted from the sensor. In this paper, we propose a remote surveillance system to monitor the status of control relay used in automation system. The proposed system consists of a control relay module, a one-chip processor module, a computer monitoring system, and a database system that inputs and manages the details of the control relay. The computer monitoring system is configured to monitor the operating condition and life time of the control relay. The database is configured so that the input date of the control relay can be input and corrected, and the operating state information of the control relay can be automatically printed. In the remote monitoring system, the failure status of the control relay is recognized in real time, and the time required for normal operation can be minimized by quickly replacing faulty parts.