• Advances in concrete construction
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• v.4 no.2
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• pp.123-143
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• 2016

Use of heavy fuel fly ash (HFFA) (diesel and cracked fuel) for power generation in Saudi Arabia has generated and accumulated large quantities of HFFA as a byproduct. In this research, HFFA is studied with the emphasis on the utilization of this waste material in concrete blocks and asphalt concrete mixes. Two types of mixes, one with low and other with high cement content, were studied for concrete blocks. Different mixes having varying percentages of HFFA (0% to 25%), as cement/sand replacement or as an additive, were studied. The performance of concrete blocks is evaluated in terms of compressive strength, water absorption, durability and environmental concerns. The results showed that blocks cannot be cast if more than 15% HFFA is used; also there is a marginal reduction in the strength of all the mixes before and after being exposed to the sulfate solution for a period of ten months. HFFA is studied in asphalt concrete mixes in two ways, as an asphalt modifier (3&5%) and as a filler (50%) replacement, the results showed an improvement in stiffness and fatigue life of mixes. However, the stability and indirect tensile strength loss were found to be high as compared to the control mix due to moisture damage, indicating a need of using antistripping agents. On environmental concerns, it was found that most of the concerned elements are within acceptable limits also it is observed that lower concentration of barium is leached out with the higher HFFA concentrations, which indicates that HFFA may work as an adsorbent for this leaching element.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.632-637
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• 2019

The cable tray design of an offshore plant production design is to optimally arrange the 3D modeling so that the cable can be installed without interfering with the structural members and various outfit equipment, and it is performed using a PDMS (Plant design management system), which is a 3D CAD system for an offshore plant layout. This study reviewed the development of PML (Programmable macro language) for a PDMS supporting offshore plant cable tray design and examined the efficiency compared to the existing method. Cable tray design PML developed in this paper enables fully parametric design using electrical outfit template library, allowing a rapid response to frequent modifications due to design changes and minimizing repetitive work fatigue by reflecting the accumulated design experience. In addition, the developed system was applied to the offshore plant structure module and it improved the work efficiency by more than 50% compared to the existing method.

• Korean Journal of Occupational Health Nursing
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• v.6 no.1
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• pp.23-43
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• 1997

The work-related diseases due to continuous overwork are mainly cerebro- and cardio-vascular ones, which is commonly called 'Karoshi', death from overwork. Many factors are capable for Karoshi : occupational stress in relation to technological renovation and industrial rationalization, competitive social structure, and accumulated fatigue accured to long time or irregular working. And its occurence is on the rise. The World Labor Report 1993 released by ILO, pointed out the diseases related to overwork and stress as one of the most important occupational health problem. In Korea, social awareness of Karoshi is at an infant stage, and reliable statistics for its occurence are not compiled in a convenient manner. Despite the rising Karoshi, there are no reliable clauses in workmen's compensation enough to settle down the disputes. Therefore, it is not uncommon that the Labour Ministry and Civil Court find difficulties in reaching an agreement. This study was intended to provide proper compensation and prevention program for workers by suggesting reasonable compensation clauses for the death from overwork. This study consists of two comparative reviews on the compensaton clauses for the death from overwork. One is to review legal standards of Karoshi among three countries, such as Korea, Japan and Taiwan. The other is to investigate the cases of Karoshi in Korea, 121 cases identified at the Labor Welfare Corperation and the Labour Ministrial process of examination and reexamination, and 73 leading cases at the High Court of Justice. The main findings of the study are as follows : 1. Comparisons of comperative review on compensation clauses for the death from overwork among three countries. 1) All of three countries have the same kinds of disease for compensation, which were cerebro-and cardiao-vascular diseases, while for cardiac disease group, Korea has the smaller number of diseases for compensation than Japan. 2) As for the definition of overwork, the three countries share equally that overload for one week prior to collapse is considered as an important factor, but accumulated chronic fatigue is disregarded. 3) As the basis of overwork, in Japan, there is a tendency to move from the conditions of an ordinary healthy adult to those of the individual concerned in Japan, whereas there is no such concern yet in Korea. 4) All the three countries use a common standard of medical judgement in demonstrating causal relationship between a job and a disease. However, Korea is progressive in the sense that in the case of CVA at worksite, the worker himself has no obligation to prove the cause. 2. The results of a comparative review on excutive decisions by Labor Ministry and judicial decisions by the Court in Korea : A judicial decision is based on the legalistic probability, but a excutive decision is not. Therefore, excutive decisions have such restrictions that : 1) TIA (transitory ischemic cerebral attack) and myocarditis are excluded from compensation, and there is little consistency of decision in the case of cause-unknown death. 2) There is a tendency not to compensate for the death from overwork since the work terms such as repeated long-time working, shift work or night-shift work are not considered as overloading. 3) There is a tendency to regard the conditions of a ordinary healthy adult rather than those of the individual concerned(age, existing diseases, health state, etc.) as the comparative basis of overload. 4) There remains a tendency not to compensate for the death from overwork in the case of collapse occuring out of workplace, on the ground of 'on the course of working' and 'in the cause of accident'. Through the study, the fact manifests itself that Korea's compensation clauses for work-related diseases due to overwork are very restrictive. So, it is necessary to extend the Labor Ministry's clauses of compensation for the death from overwork following to the recent changes of other countries and internal judicial decisions. This is very important in the perspective of occupational health that aims at health promotion of workers including prevention of the Karoshi.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.79-85
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• 2011

Bridge Weigh-in-Motion(BWIM) system calculates a travelling vehicle's weight without interruption of traffic flow by analyzing the signals that are acquired from various sensors installed in the bridge. BWIM system or data accumulated from the BWIM system can be utilized to development of updated live load model for highway bridge design, fatigue load model for estimation of remaining life of bridges, etc. Field test with moving trucks including various load cases should be performed to guarantee successful development of precise BWIM system. In this paper, a numerical simulation technique is adopted as an alternative or supplement to the vehicle traveling test that is indispensible but expensive in time and budget. The constructed numerical model is validated by comparison experimentally measured signal with numerically generated signal. Also vehicles with various dynamic characteristics and travelling conditions are considered in numerical simulation to investigate the variation of bridge responses. Considered parameters in the numerical study are vehicle velocity, natural frequency of the vehicle, height of entry bump, and lateral position of the vehicle. By analyzing the results, it is revealed that the lateral position and natural frequency of the vehicle should be considered to increase precision of developing BWIM system. Since generation of vehicle travelling signal by the numerical simulation technique costs much less than field test, a large number of test parameters can effectively be considered to validate the developed BWIM algorithm. Also, when artificial neural network technique is applied, voluminous data set required for training and testing of the neural network can be prepared by numerical generation. Consequently, proposed numerical simulation technique may contribute to improve precision and performance of BWIM systems.

• Fire Science and Engineering
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• v.29 no.3
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• pp.59-64
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• 2015

This study analyzed results of the causes of failure in 1,022 fire trucks currently being used in South Korea (aerial ladder, aerial platform, pumper, and chemical fire trucks). The results show that 46% of aerial ladder trucks have defective in the elevator brake systems, 29% of aerial platform trucks have contamination in the hydraulic oil, 37% of pumpers have defective in the pneumatic cylinders of the air supply system, and 39% of chemical fire trucks have defective in the powder fire extinguishing systems. The principal reasons for malfunctions are deterioration of the apparatuses, and accumulated fatigue from repetitive use of certain components, such as pneumatic cylinders in the air supply system and wire rope jamming in rollers in the ladder apparatus. These manufacturing defects should be improved upon in the manufacturing process. As a result, the fire trucks, which are used for 5 years or more, need precise inspections in accordance with the Regulation on Fire Apparatus Maintenance. Fire apparatuses have a service life of 10 to 12 years or more. They need to be replaced or require life extension, and they should be kept in top shape with the best maintenance for public safety.

• Journal of the Korean Institute of Gas
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• v.14 no.2
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• pp.1-6
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• 2010

The strength safety of high pressure gas cylinder has been analyzed by using a finite element method. In this study, the internal gas pressures of a steel bombe include a service charging pressure of $9kg/cm^2$, high limit charging pressure of $18.6kg/cm^2$, high limit of safety valve operation pressure $24.5kg/cm^2$, and hydraulic testing pressure of $34.5kg/cm^2$. The computed FEM results indicate that the strength safety for a service charging pressure of $9kg/cm^2$ and high limit charging pressure of $18.6kg/cm^2$ is safe because the stress of a gas cylinder is within yield strength of steel. But the stress for a hydraulic testing pressure of $34.5kg/cm^2$ sufficiently exceeds the yield strength and remains under the tensile strength. If the hydraulic testing pressures frequently apply to the gas cylinder, the bombe may be fractured because a fatigue residual stress is accumulated on the lower round end plate due to a plastic deformation. The computed results show that the concentrated force in which is applied on a skirt zone does not affect to the lower round end plate, and the most weak zone of a bombe is a middle part of a lower round end plate between a bombe body and a skirt for a gas pressure. Thus, the FEM results show that the profile of a lower round end plate is an important design parameter of a high pressure gas cylinder.

• Journal of the Ergonomics Society of Korea
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• v.34 no.4
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• pp.313-326
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• 2015

Objective: The objective of this research is to quantitatively analyze muscle activities of arm and shoulder, according to direction in various types of one-handed manual material handling, based on surface electromyography. Background: Workers in industrial sites frequently carry out one-handed manual material handling using arm and shoulder muscles. Therefore, chronic load and accumulated fatigue occur to arm and shoulder muscles, which becomes a main cause of upper arm and shoulder musculoskeletal disorders. The shoulder muscles have widely range of motion, and complex interactions take place among various muscles including rotator cuff muscles. In this regard, research on interactions among should muscles, according to such various dynamic motions, is required. Method: Ten male subjects in their 20s participated in this research. This research considered upward, downward, leftward, rightward, forward and backward directions and fourteen muscles around arm and shoulder (biceps brachii and trapezius, etc.) as independent variables. The mean muscle activity was set as the dependent variable. This research extracted $4^{th}{\sim}7^{th}$ repetition signals according to ten times of repetitive muscle contraction, and analyzed the muscle activity concerned using the envelope detection technique. Results: The mean muscle activity of upward direction was analyzed highly statistically significant. The reason is that the effect of gravity works to arm and shoulder muscles. Also, it is conjectured that deformation of coracoacromial ligament was caused, and its contact pressure increased, due mainly to the shoulder flexion, and therefore load was analyzed high. Muscle activity was analyzed significantly low, according to concentric ballistic motion used in the concentric contraction phase by storing elastic energy in the eccentric contraction phase with a motion to bring the weight to the front of subject's body as to downward, leftward and backward directions. Because, elbow joint's flexion-extension motions mainly occurred, biceps brachii was analyzed high muscle activity as the prime mover. Conclusion: The information on the quantitative load of muscles can be applied to ergonomic work design for one-handed manual material handling to minimize muscle load. Application: This research has effectively identified muscle activity according to dynamic contraction by applying an envelope detection technique. The results can be used for ergonomic work design to minimize muscle load during the one-handed manual material handling, according to each direction. The research results are expected to be used for musculoskeletal disorder prevention and physiotherapy in the rehabilitation medical field, based on the muscle load of arm and shoulder in various directions.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.9-16
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• 2018

Hangover after drinking is different from person to person symptoms and degree, but usually thirst, fatigue, headache, general boredom, gastrointestinal disorder, vomiting, diarrhea, deficiency of vitamin appears. This hanging phenomenon is caused by the action of precursors such as ethyl acetate and acetaldehyde, which are the by products of fermentation contained in alcohol and alcohol accumulated in hepatocytes and body. In order to solve the hangover phenomenon, the same Origin as polysaccharide Polydeoxyribonucleotide, which is a nucleic acid-sugar-phosphate complex, which is a semen or testicular extract in salmon extract, and a water soluble salmon extract powder having the same structure and lower price than Polydeoxyribonucleotide And D-Glucuronic acid and N-Acetyl glucosamine. It has excellent biocompatibility, viscoelasticity and moisturizing power. It has effect on reduction of body water loss and skin moisture content in hangover phenomenon. It is antioxidant and skin moisturizing effect Hyaluronic acid was irradiated with gamma rays, and the composition was prepared by using the salmon extract powder and the main raw material. The ethanol degradation, the acetaldehyde reduction amount, the blood acetaldehyde concentration and the acetic acid concentration were measured to evaluate the alcoholysis effect, Skin moisture evaporation rate To examine the evaluation unit water content of the skin was improved determine whether the antioxidant and provide skin moisturizing effect. The addition of ethanol extracts of salmon extracts showed a decrease of 5 to 7 times compared with no addition, and a decrease of 3 to 5 times of acetaldehyde. In addition, the change of acetaldehyde concentration and acetic acid concentration in blood showed a rapid decrease compared to the no - added control group. In addition, when the raw material of hyaluronic acid was used, skin moisture content was high and skin moisture evaporation amount was decreased. Therefore, hyaluronic acid, which is a polysaccharide polymer, has excellent viscoelasticity and moisturizing ability, It is considered to provide antioxidant and skin moisturizing effect. Therefore, it can be said that the composition containing salmon extract powder and hyaluronic acid as a main ingredient is effective for the hangover phenomenon which occurs after drinking.