• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.53-57
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• 2005

This paper presents development of a classification system for an electrical fire investigation. In order to reduce an electrical fires and establish detailed prevention plans, the collection of an electrical fire causes and base data are very important. Based on this data, a new classification system for an electrical fire investigation was developed and the direction to the classification system was suggested by fundamental analysis. All of the collected information is analyzed by bottom-up method. Criteria items which based on base data were categorized to classify items. The classification of items were found out as follows : basic condition fire scene condition, fire sign, fire cause. Particularly, the fire cause category is classified. A new developed classification system for an electrical fire investigation will be used to analyse electrical fires easily and efficiently.

• Structural Engineering and Mechanics
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• v.20 no.3
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• pp.363-380
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• 2005

The cable tension plays an important role in the construction, assessment and long-term health monitoring of cable structures. The cable vibration equation is nonlinear if cable sag and bending stiffness are included. The engineering implementation of a vibration-based cable tension evaluation is mostly carried out by the simple taut string theory. However, the simple theory may cause unacceptable errors in many applications since the cable sag and bending stiffness are ignored. From the practical point of view, it is necessary to have empirical formulas if they are simple and yet accurate. Based on the solutions by means of energy method and fitting the exact solutions of cable vibration equations where the cable sag and bending stiffness are respectively taken into account, the empirical formulas are proposed in the paper to estimate cable tension based on the cable fundamental frequency only. The applicability of the proposed formulas is verified by comparing the results with those reported in the literatures and with the experimental results carried out on the stay cables in the laboratory. The proposed formulas are straightforward and they are convenient for practical engineers to fast estimate the cable tension by the cable fundamental frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.312-316
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• 2002

Recently, mixers are being widely used in the water purification plant in order to increase the filtration efficiency. It has been found that a severe vibration was being felt on a upper structure of a mixer facility during steady state operation. The cause of the excessive vibration of the structure to which the mixer's shaft is supported has been evaluated through modal analysis on the shaft and vibration measurements during operation. The fundamental natural frequency of the mixer's shaft is found to be around 1.8 Hz and the main vibratory frequency around 30 Hz. It has been tuned out that the main vibratory frequency, 30 Hz is coincident with the fundamental holding frequency of the upper structure, and that the acceleration signal of the upper structure and the displacement signal of the mixer's shaft showed highly coherent to each other. Accordingly, it reveals that the main cause of the excessive vibration is due not to the mixer's vibration but to the natural frequency of the upper structure excited by flow turbulence.

• Journal of the Korean Society of Safety
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• v.17 no.1
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• pp.94-98
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• 2002

This study aimed to search for the fundamental accident causes using a categorical analysis, a kind of statistical methods. As the analysis methods, correlation analysis, independence test and logistic regression analysis were used. And the SPSS package, a general-purpose mathematical library, was used to obtain statistical characteristics. As the result of this study, the accident causes associated with factor of 'lost working days' were factors such as 'employed periods', 'sex', 'type of accident', 'month'. In case of applying independence test method, the most important cause was the factor of 'month'. In case that logistic regression analysis method was applied, the cause contributed to the increase structure'. 'less than 6 month'. On the basis of these results, the plan for accident prevention and the proper investment for accident prevention expenditure could be carried out in each workshop.

• International Journal of Fluid Machinery and Systems
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• v.10 no.2
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• pp.119-137
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• 2017

Although the stall stagnation phenomena have often been experienced in site and also analytically in numerical experiments in surges in systems of compressors and flow paths, the fundamental causes have not been identified yet. In order to clarify the situations, behaviours of infinitesimal disturbance waves superposed on a main flow were studied in a simplified one-dimensional flow model. A ratio of the amplifying rate of the system instability to the characteristic slope of the compressor element was surveyed as the instability enhancement factor. Numerical calculations have shown the following tendency of the factor. In the situation where both the sectional area ratio and the length ratio of the delivery flow-path to the suction duct are sufficiently large, the enhancement factors are greater in magnitude, which means occurrence of ordinary deep surges. However, in the situation where the area ratio and/or the length ratio is relatively smaller, the enhancement factor tends to lessen significantly, which situation tends to suppress deep surges for the same value of the characteristic slope. It could result in the stall stagnation condition. In the domain of area ratio vs. length ratio of the delivery duct to the suction duct, contour-lines of the enhancement factor behave qualitatively similar to those of the stall stagnation boundaries of a fan analytically obtained, suggesting that a certain range of the enhancement factor values could specify the stagnation occurrence. The significant decreases in the factors are observed to accompany appearances of phase lags and travelling waves in the wave motions, which macroscopically suggests breaking down of the complete surge actions of filling and emptying of the air in the delivery duct. The strength of the action is deeply related with acoustic interferences and is evaluated in terms of the volume-modified reduced resonance frequency proposed by the author. These observations have shown the fundamental cause and the sequence of the stall stagnation in principle.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.12
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• pp.253-276
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• 1999

CISG articles 34 and 37 clearly allow the seller to cure any nonconformity in documents of sale or performance prior to the date for delivery if it does not cause the buyer unreasonable inconvenience or unreasonable expense. CISG article 48 allows a seller to cure the performance even after the date for delivery if it does not cause the buyer unreasonable delay, unreasonable inconvenience or unreasonable uncertainty of reimbursement by the seller of expenses advanced by the buyer. The wording any failure to perform is broad enough to include a delay. The seller's right to cure relates to all his obligations. The seller may remedy 'any failure to perform his obligations'. This language is broad enough to include a defect in documents. In some cases the fact that the seller is able and willing to remedy the non-conformity of the goods without inconvenience to the buyer, may mean that there would be no fundamental breach unless the seller failed to remedy the non-conformity within an appropriate time. It cannot generally be said what unreasonable inconvenience means. This can only be decided on a case-by-case basis. The seller must bear the costs involved in remedying a failure to perform. The curing of a failure to perform may have influence on the amount of the damage claimed. Insofar as the seller has the right to cure, the buyer is in that case obliged to accept the cure. If he refuses to do so, he can neither avoid the contract nor declare a reduction in price. This rule clearly shows the underlying concept of the CISG, to keep to the contract, if possible. Should the buyer requires delivery of substitute goods and the seller offers repair, it depends on the expense each case. The buyer must receive the request or notice by the seller. The relationship between the seller's right to cure and the buyer's right to avoid the contract is unclear. The buyer's right to avoid the contract should not nullify the seller's right to cure if the offer is reasonable. In addition, whether a breach is fundamental should be decided in the right of the seller's offer to cure.

• Journal of The Korean Astronomical Society
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• v.29 no.2
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• pp.223-243
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• 1996

We have constructed a line-by-line model of the A-X system of CO in order to analyze the CO bands appearing in the UV spectra of comets. The model includes electronic, rotational, vibrational transitions, excitations by solar UV radiation, and effects of neutral and electron collisions. The major bands of the A-X system occur in the $1200 - 1800{\AA}$ range where the temporal variation of solar irradiation is significant. The solar spectrum in this spectral range shows many emission lines, which cause a significant Swings effect. We derived fluorescence efficiencies of the bands as functions of heliocentric velocity and cometocentric distance using a high resolution spectrum of the sun. We compared our model with a spectrum of comet P/Halley obtained with the IUE, and estimated that the UV Swings effects are less than 20 fluorescence efficiencies for the most bands of the A-X system. We discuss the temporal variation of solar UV irradiation and its effects on the fluorescence efficiencies. The study of the A-X system also requites knowledge of vibrational and rotational fluorescent processes in the infrared and radio regions because the majority of CO molecules in the coma is in the ground rotational states. The solar infrared spectrum near 5 microns, where the fundamental band of CO occurs, contains strong absorption lines of the fundamental band and hot bands of CO and its isotopes. We derived fluorescence efficiencies of the infrared band as functions of heliocentric velocity and cometrocentric distance. The solar absorption lines near 5 microns cause a 20 reduction of the g-factor of the fundamental band at heliocentric velocities close to 0 km/sec. We discuss the effects of neutral and electron collisions on the fluorescence efficiencies of the infrared and UV bands.

• Journal of Korean Society for Quality Management
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• v.47 no.3
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• pp.417-424
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• 2019

Purpose: In this study, the goal is to analyze this case to prevent the same accidents when using one-shot rifle. Methods: Detailed analysis of damaged parts must first be made in order to determine the cause of the abnormal explosion. The cause of abnormal operation can be determined by analyzing the information of damaged components and the firing mechanism of the weapon step by step. Also we can refer to a statement of shooter, witness and accident scene situation. Based on this theory, cause of abnormal firing can be narrow down. Results: Fracture of pin for fixing firing and latch is cause of abnormal operation of firing. Conclusion: It is deemed that periodic inspection and fundamental improvement of the structure are required to prevent the same accident as this.

• Journal of Korean Society for Quality Management
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• v.51 no.4
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• pp.735-749
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• 2023

Purpose: The purpose of this study is to derive solutions and prevent similar cases from occurring by analyzing the causes of cracks found in temperature cycling tests of rocket motor. Methods: By combining the results of the current state confirmation test, non-destructive test, domestic and foreign rocket motor comparison test, cutting test, and adhesion test according to the number of times to apply mold release agent, a Cause and Effect Diagram analysis was performed to derive the cause of cracks. Results: Through this study, 26 factors that could cause cracking in rocket motors during temperature cycling tests were identified. Through various additional test results, a total of five causes were identified, including chemical and structural design of the joint between the propellant and stress relief insert, omission of procedure in the manufacturing procedures, natural aging due to temperature, and load accumulation due to temperature changes. The fundamental cause was confirmed to be insufficient consideration of the release properties of the propellant and stress relief insert. Conclusion: During the design process, it was confirmed that this could be solved by structurally or chemically designing the insert so that it does not combine with the propellant, or by applying a mold release agent during the manufacturing process.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.35-40
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• 2016

Pulse diagnosis is one of the representative diagnostic methods in Oriental medicine. In this study, a pulse pressure sensor array coated with silicone, which includes 6 piezo-resistive sensors and 1 thermistor, is fabricated for pulse measurement. It is necessary to coat the pulse sensor array with silicone to avoid the fracture or damage of pressure sensors when the sensor is in contact with the skin and a constant pressure is applied. However, the silicone coating on the pulse sensor array can cause signal interference among the sensors in the pulse sensor array. The interference number (IN), a calculation for expressing the degree of interference among channels, is changed according to the silicone thickness on the pulse sensor array. The IN is increased by a thick silicone coating, but the fabrication error, an important index for the mass production of the sensor array, is reduced by the thickness of the silicone coating. We propose that the thickness of the silicone on the pulse sensor array is an important consideration for the performance of the fabricated sensor and manufacturing repeatability.